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TAMIL NADU WATER SOLUTIONS

Our purpose is to positively impact lives, transform communities and make the world a more resilient and better place, through sustainable projects

Our core values and philosophy recognise that our business success is founded upon a commitment to certain principals. We lead by example At all levels, we act in a way that exemplifies what we expect of each other and our clients. We are collaborative We work together with communities, companies, governments and NGOs to bring out the best in each other and create strong successful working relationships. We respect the individual The expertise, passion and leadership of our talented people around the world make our success possible. We respect and encourage our people’s ideas, diversity and cultures. We are sustainable Sustainability is at the forefront of every project and decision we make. We promote safety We are a company that puts safety first. We are all accountable for keeping our colleagues and ourselves safe, and for delivering work safely to our clients. We act with integrity We constantly strive to uphold the highest professional standards, provide effective designs and rigorously maintain our independence.

Website http://tamilnaduwater.wix.com/potablewater

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Table of Contents Executive Summary ........................................................................................................... 6

1. Water Demand ................................................................................................................ 7

2. Stakeholder Engagement ............................................................................................ 8 2.1 Who are the stakeholders? .................................................................................................................... 8 2.2 Collaboration with Local Engineering Consultancy .................................................................... 8 2.3 Public Consultations ................................................................................................................................ 9 2.4 Conflict mitigation .................................................................................................................................... 9 2.5 Fraud and Corruption Reporting App ............................................................................................... 9 2.6 Annual Event ............................................................................................................................................ 10

3. Quality of Raw Water ................................................................................................. 11

4. Water Treatment Process ........................................................................................ 12 4.1 Background ............................................................................................................................................... 12

4.1.1 Introduction .............................................................................................................................................. 12 4.1.2 Water Quality Parameters of Concern .......................................................................................... 12 4.1.3 Importance of Certain Water Quality Parameters ................................................................. 13

4.2 Process Flow diagram (PFD) ............................................................................................................. 15 4.3 Chemical Treatment Design ............................................................................................................... 16

4.3.1 Basis for Unit Sizing and Process Design ..................................................................................... 16 4.3.2 Clarification ............................................................................................................................................... 16 4.3.3 Rapid Gravity Filtration ...................................................................................................................... 26 4.3.4 Disinfection ................................................................................................................................................ 35 4.3.5 Sludge Thickening .................................................................................................................................. 40 4.3.6 Sludge Dewatering ................................................................................................................................. 44 4.3.7 Plant Layout .............................................................................................................................................. 48

5. Sludge Treatment Process ....................................................................................... 51 5.1 Sludge Tank Structure Design ........................................................................................................... 52

6. Water Conveyance ...................................................................................................... 53 6.1 Water Demand......................................................................................................................................... 53 6.2 System and Component Design ........................................................................................................ 53

6.2.1 System Characteristics and Component Selection .................................................................. 53 6.2.2 Pipe Cross Sections ................................................................................................................................. 55

6.3 Pump Stations & Housing ................................................................................................................... 56 6.4 Intake........................................................................................................................................................... 58

6.4.1 Suction Bell Design ................................................................................................................................. 58 6.4.2 Suction Piping .......................................................................................................................................... 58 6.4.3 Intake Pump .............................................................................................................................................. 58

6.5 Valves .......................................................................................................................................................... 58 6.5.1 Wash Out Valves ...................................................................................................................................... 58 6.5.2 Air Valves .................................................................................................................................................... 58 6.5.3 Stop Valves ................................................................................................................................................. 58

6.6 Surge Protection ..................................................................................................................................... 58

7. Bridge Design over Bhima River ............................................................................ 59

8. Bridge Design over Arkavathi River ..................................................................... 63

9. Over-ground Pipeline Crossing Design ............................................................... 67 9.1 Public consultation ................................................................................................................................ 67 9.2 Consideration of local wildlife .......................................................................................................... 67 9.3 Crossing design drawings ................................................................................................................... 67

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10. Under-road Pipeline Tunnelling Design .......................................................... 71

11. Service Reservoir ...................................................................................................... 72 11.1 Tank Structure Design ....................................................................................................................... 73 11.2 Inlet Design ............................................................................................................................................ 75 11.3 Outlet Design ......................................................................................................................................... 75 11.4 Inlet and Outlet connection ............................................................................................................. 75 11.5 Ventilation Design ............................................................................................................................... 76 11.6 Baffle Wall Design................................................................................................................................ 77

12. Control Systems......................................................................................................... 78 12.1.Water Treatment Plant Control System ..................................................................................... 78 12.2 Sludge Storage Control System ...................................................................................................... 78 12.3 Pumps Control System ...................................................................................................................... 80 12.4 Pipeline Control System .................................................................................................................... 81 12.5 Service Reservoir Control System ................................................................................................ 81

13. Lighting ........................................................................................................................ 83 13.1 Control centre lighting....................................................................................................................... 83

13.1.1 Control Room ......................................................................................................................................... 84 13.1.2 Kitchen ...................................................................................................................................................... 84 13.1.3 WC ............................................................................................................................................................... 84 13.1.4 Emergency Lighting ............................................................................................................................ 84 13.1.5 External Lighting ................................................................................................................................. 84

14. Construction Process .............................................................................................. 85 14.1 Inlet construction ................................................................................................................................ 86 14.2 Underground pipeline construction ............................................................................................ 87 14.3 Over-ground pipeline construction ............................................................................................. 88 14.4 Pump House construction ................................................................................................................ 90 14.5 Water Treatment Plant construction .......................................................................................... 91 14.6 Tank construction – Sludge Store and Service Reservoir ................................................... 93 14.7 Bhima River Crossing – Truss Bridge .......................................................................................... 94 14.8 Arkavathi River Crossing – Cable Stayed Bridge .................................................................... 96 14.9 Over-ground Pipeline Crossing ...................................................................................................... 99 14.10 Under-road tunnelling construction ....................................................................................... 101 14.11 Service Reservoir construction ................................................................................................. 103

14.11.1 Stage 1 – Excavations and foundations ............................................................................... 103 14.11.2 Stage 2 – Floor Slabs ..................................................................................................................... 104 14.11.3 Stage 3 – Tank Walls .................................................................................................................... 104 14.11.4 Stage 4 – Tank Roof ....................................................................................................................... 105

15 Risk Assessment....................................................................................................... 108

16. Capital Costs of Project ......................................................................................... 109 16.1 Pipeline Cost ........................................................................................................................................ 109 16.2 Water Treatment Plant Capital & Operational Costs .......................................................... 110 16 3 Service Reservoir Cost ..................................................................................................................... 111 16.4 Under-road Tunnelling Cost .......................................................................................................... 112 16.5 Sludge Tank Cost ................................................................................................................................ 112 16.6 Truss Bridge Cost............................................................................................................................... 113 16.7 Over-ground Pipe Crossing Cost ................................................................................................. 113 16.8 Cable-stayed Bridge Cost ................................................................................................................ 114 16.9 Sludge Removal .................................................................................................................................. 114 16.10Total Project Costing ...................................................................................................................... 115 16.11 Life-time and decommissioning costs .................................................................................... 115

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Appendices ....................................................................................................................... 116

References ........................................................................................................................ 250

Academic Appendix ...................................................................................................... 257

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Executive Summary The treated water will meet the quality requirements set out in the Water Supply (Water Quality) Regulations 2000 for England and Wales (Statutory Instrument 2000 No. 3184) (DEFRA, 2000) – ensuring a high standard of drinking water for the residents of Sandalwood. Analysis of the water quality data and comparison with the water quality regulations, identified parameters of concern to be highlighted early in the design process – it was ensured that the proposed process meet the standards expected by the client. Water will be drawn from NBR via an inlet will be submerged 2 metres below the water surface and the flow required by the system will be met by a total of 48 pumps in distributed into 8 stations. The pipeline will be 120km long and will have go through underground and over-ground phases and be made from DIP. The water treatment plant consists of the following units:

x Six Floc Blanket clarifiers dosed with alum sulphate, lime and polyelectrolyte

x Eleven Rapid gravity filters in both of the filtration stages (total of 22) with chlorine and lime added to the filters in the second stage

x Two Chlorine tanks dosed with chlorine and sulphuric acid with lime added after the water has left the tank

x Five Gravity thickeners dosed with polyelectrolyte x Five Plate and frame filter presses x One sludge storage tank sized for three days storage located after the

thickener x Two polyelectrolyte storage tanks each sized for a week’s storage x One sludge holding tank sized for a day’s storage x Two storage tanks for each of the other chemicals, sulphuric acid, lime

and alum for the conditions they were provided in each sized for a week’s storage

x One storage tank for the lime slurry created on site from the lime provided and excess water

A steel truss bridge structure will be used to cross the pipeline over the 25m-wide Bhima River. A cable-stayed bridge structure will be used to cross the pipeline over the 250m-wide Arkavathi River. Crossing points will be constructed over the above-ground pipeline every 350m, to allow the local population and wildlife to remain unaffected by the over-ground pipeline obstruction. Two grade 50 steel sludge silos will be installed with the capacity to hold 1 week’s sludge each - one for emergency. These will be emptied daily to landfill via trucks. Four structural steel service reservoirs will be constructed; each one can hold 28,000m3 of water. Each reservoir will have one inlet and two outlets - one for emergency.

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1. Water Demand The 2030 population of Sandalwood will demand a flow rate of 1.15m3/s of potable water. Due to inevitable leakages in the pressurised system, the intake of reservoir water will be 1.4m3/s. This equates to approximately 450 million litres of water a year – a considerable amount of water. In a world where water demand is rising exponentially and fresh water reserves are depleting, Tamil Nadu Water Solutions (TNWS) is committed to promoting resilient and sustainable projects. Deeply rooted in TNWS’s philosophy is be challenging and be committed to fostering good relationships. To protect the environment and reduce the water we take from it, TNWS propose a future project collaboration in which the City of Sandalwood’s wastewater is treated and directly returned to the customer in a closed loop – as is the case with Singapore’s ‘New Water’.

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2. Stakeholder Engagement Deeply rooted in the ethos of TNWS is the importance of understanding and responding to the views and expectations of customers and wider stakeholders. Community engagement and consideration of stakeholders’ concerns is fundamental to TNWS’s ‘Social Responsibility Strategy’ and is key to the implementation of a successful project. (Thames Water, 2015)

2.1 Who are the stakeholders? The stakeholders are all those with an interest in the project. Particular attention is to be given to identifying those with no direct involvement in the project, but who might be negatively affected as a result of the work. A Stakeholder Engagement Team has been established with the responsibility of fostering relationships and communicating with the key stakeholders identified in fig. 1. Fig. 1 – Stakeholder Map

2.2 Collaboration with Local Engineering Consultancy As a world leading engineering company, TNWS have had continued success with a variety of international engineering projects. Through vast experience abroad, TNWS have appreciated the value of local knowledge. To ensure the success of the project, TNWS will partner with a local engineering consultancy to gain expertise on specific local challenges – from technical knowledge to gaining recommendations about cultural and social aspects of the project.

Government

City of Sandalwood

City of Kanakapura

Local Engineering Company

Customers Rural Communities

NGOs and Pressure Groups

Sandalwood Water Supply Board

International Alert

Local Regional National

State of Karnataka Cauvery Water Disputes Tribunal

State of Tamil Nadu

Contractor

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2.3 Public Consultations The planned pipe route passes by Kanakapura and rural communities – some of which also use the supply reservoir for self-sustaining agriculture. It is therefore critically important to actively engage with these stakeholders to ensure disturbance to them is minimised. All stakeholders will be notified of project updates in the effort to remain as transparent as possible. Local farmers that use the water source will also be involved in the early research and planning stages of the project. These individuals are local experts and have been using the water source for generations. It is vital to engage with them in order to better understand region-specific challenges.

2.4 Conflict mitigation The city of Sandalwood lies in the Tamil Nadu region, but close to the border with the Karnataka region. The sharing of the Cauvery River has been the source of serious conflict between these two states. While the Cauvery Water Disputes Tribunal came to a formal agreement and issued a final order to share the water (CWDT, 2007), TNWS must be wary of the sensitivity of this post-conflict region. TNWS will work with peace building NGO ‘International Alert’, who are experts in the field of advising private companies in post-conflict scenarios. Bray (2007) highlights how “companies’ most significant social impact will come from the way that they conduct their core activities and in particular from their relationships with local communities and sub-contractors”. Stakeholder engagement is therefore regarded as fundamental to maintaining peace.

2.5 Fraud and Corruption Reporting App Since the recent controversy surrounding engineering projects and corruption charges in India (World Bank, 2013), TNWS actively work to eradicate corruption and act to lead the industry into a more socially responsible future. TNWS is therefore committed to transparency and, under the responsibility of the Stakeholder Engagement Team, have developed an anti-corruption strategy. Under the recommendation of the World Bank (2012), a Reporting App has been developed – accessible to all stakeholders. The app allows all those involved in the project to report all instances of corruption for further investigation. Additional comments, questions and concerns about the project can also be reported through the app, in an effort to fully engage all stakeholders. Those without access to smart technology are able to report corruption and other concerns directly to the Stakeholder Engagement team through consultation events.

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2.6 Annual Event Throughout the project, TNWS will continue to engage with all stakeholders through annual engagement events. Stakeholders will be given project updates and will also have the opportunity to provide feedback and voice any concerns. In accordance with the sustainability strategy, TNWS will use these events to raise the awareness of sustainability issues. Workshops will be run and publicity material distributed to educate consumers on the need to preserve water and reduce their demand.

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3. Quality of Raw Water The treated water will meet the quality requirements set out in the Water Supply (Water Quality) Regulations 2000 for England and Wales (Statutory Instrument 2000 No. 3184) (DEFRA, 2000) – ensuring a high standard of drinking water for the residents of Sandalwood.

Fig. 2 – Diagram showing the water qualities of concern, with their peak raw water value and the regulatory values

160 PtCo

Organic material from soil causes natural colour in water and needs to be removed for aesthetic reasons and due to the risk of highly coloured water producing THM.

20 PtCo

200 NTU

Turbidity is removed for aesthetic reasons and because high turbidity can reduce the efficiency of disinfection.

1 NTU

0.05 mg/L

Is removed as human consumption of arsenic, in either food or drinking water, can result in an increased risk of lung and bladder cancer (WHO, 2007).

0.01 mg/L

0.05 mg/L

Lead is removed due to health risks such as impaired renal function, impaired fertility, cardiovascular disease and neurodevelopmental effects (WHO, 2007).

0.03 mg/L

0.42 mg/L

Manganese is largely removed for aesthetic reasons.

0.05 mg/L

10.8 mg/L

Iron is removed for aesthetic reasons and can also increase the water’s turbidity enough to effect disinfection.

0.2 mg/L

19 mg/L

While fluoride has dental benefits, it is reduced as high concentrations have negative health affects such as dental fluorosis and skeletal fluorosis (WHO, 2007).

1.5 mg/L

1.51 mg/L

Acts as an indicator of bacterial sewage and animal waste pollution. Toxicological effects are only observed at exposures above 200mg/kg body weight (WHO, 2007).

0.5 mg/L

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4. Water Treatment Process 4.1 Background 4.1.1 Introduction In this section of the report, the water treatment process chosen will be clearly explained, thus allowing the client to understand the thought process involved in the process selection. With one of the most important features of the process selected being the final water quality, reference will be made to each individual water quality legislation met. Each section of the water treatment plant will be covered in detail starting with an introduction to the particular section including a brief description, the main objectives and processes employed for said section Followed by a description of any chemicals required for the section including their purpose, storage requirements, method of dosing and the process control employed. Next a description of the detailed design of the processes employed in the section will be described including dimensions and materials Finally the process control required for each section will be described in full detail. Final costs will be included in the costing section of the report. 4.1.2 Water Quality Parameters of Concern Processes were chosen based on the water quality requirements set out in the Water Supply(Water Quality) Regulations 2000 for England and Wales (Statutory Instrument 2000 No. 3184) (DEFRA, 2000), thus ensuring a high standard of drinking water for the residents of Sandalwood. Analysis of the water quality data and comparison with the water quality regulations, identified parameters of concern to be highlighted early in the design process – it was ensured that the proposed process meet the standards expected by the client. Listed below with the corresponding water quality legislation are the water quality parameters that were of concern. Where recommended values for a given water quality parameter could not be found in the Water Supply (Water Quality) Regulations 2000 for England and Wales (Statutory Instrument 2000 No. 3184) (DEFRA, 2000), regulatory data was obtained from the World Health Organisation (WHO).

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Table 1: Table of water qualities of concern and the regulatory value. Raw water peak values obtained from raw water data provided by the client

Water Quality Parameter (Units of Measurement)

Raw Water Value (Peak

Value) Regulatory Value

Colour (PtCo) 160 20 Turbidity (NTU) 200 1 Ammonium (mg/L) 1.51 0.5 Iron (mg/L) 10.8 0.2 Manganese (mg/L) 0.419 0.05 Fluoride (mg/L) 19 1.5 Lead (mg/L) 0.05 0.025 Arsenic (mg/L) 0.05 0.01 Total coliform (/100 ml) * taken as 100 <100 0 Faecal coliform (/100 ml) *taken as 20 <20 0

The importance of each water quality parameter in Table 1 is explained below. 4.1.3 Importance of Certain Water Quality Parameters Colour: Organic material leached from soil gives rise to natural colour (humic and fulvic acids) in water particularly in upland moorland area. Colour needs to be removed from the water for aesthetic reasons and due to the concern of highly coloured water leading to the production of triahalomethane (THM) at concentrations in excess of the drinking water regulated value. Chemical coagulation followed by clarification and rapid sand filtration is normally used to remove colour. Turbidity: Turbidity is also removed for aesthetic reasons but also because high turbidity can impact the efficiency of disinfection, which is crucial to effective water treatment. A combination of chemical coagulation and rapid sand filtration is the most widely used process for turbidity removal, although slow sand filtration with suitable pre-treatment such as coagulation and rapid sand filtration can also be used for waters containing high turbidity. Iron, manganese and aluminium: Again, iron, manganese, aluminium are largely removed for aesthetic reasons. Iron concentrations can also increase the water’s turbidity enough to have an impact on the effectiveness of disinfection. Iron is found in natural fresh waters and may also be present as a result of the use of iron coagulants or the corrosion of steel and cast iron pipes (WHO, 2007) There is also concern over reported links between aluminium being present in water supplies and Alzheimer’s disease. A suitable adjustment of pH to within the range of 5 to 8 precipitates the aluminium and iron, thus allowing them to be removed from water using chemical coagulation followed by clarification and rapid sand filtration (Crittenden et al., 2012). Ammonia: the term ammonia includes the non-ionized (NH3) and (NH4+), and occurs in water sources as a result of metabolic, agricultural and industrial processes. It also

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acts as an indicator of bacterial sewage and animal waste pollution. Toxicological effects are only observed at exposures above 200 mg/kg body weight (WHO, 2007). Fluoride: traces of fluoride are frequently found in many water types, and are also present in consumer foodstuffs and products such as toothpaste because of the dental benefits. However, if the concentrations in drinking water are too high, negative health effects such as dental fluorosis and skeletal fluorosis (WHO, 2007) Lead: the primary source of lead in drinking water is from service connections and plumbing in buildings, with factors such as pH, temperature and water hardness affecting the amount dissolved in the water from plumbing systems. The main technical solution to reducing the lead concentrations in water is to remove any plumbing and fixtures containing lead components. In poorer where replacement of all lead-containing plumbing is not an option, it is strongly recommended that effective corrosion control is employed. Exposure to water contaminated with lead is associated with numerous health risks such as impaired renal function, impaired fertility, mortality (as a result of cardiovascular disease) and neurodevelopmental effects (WHO, 2007). Arsenic: odourless and tasteless, arsenic is used for industrial processes such as metals, drugs, and mining and as a wood preservative. Human consumption of arsenic, in either food or drinking water, can result in an increased risk of lung and bladder cancer (WHO, 2007).

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4.2 Process Flow diagram (PFD) Figure 3: Process Flow diagram for water treatment plant

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4.3 Chemical Treatment Design 4.3.1 Basis for Unit Sizing and Process Design The mass balance was solved for the max turbidity case as this is what the plant was designed for and the units sized accordingly due to the max turbidity and its corresponding colour conditions yielding more sludge solids than the max colour and its corresponding turbidity conditions. The mass balance figures are presented in kg/day and to 2 decimal places. The larger volume of sludge produced in this case was assumed to be the maximum the plant produced. The detailed mass balance and assumptions are included in the appendices. 4.3.2 Clarification 4.3.2.1 Introduction to Clarification Section Description: Following the flocculation of the suspended, colloidal and dissolved particulate matter, clarification is required to reduce the solids load prior to the next stage of treatment, filtration. This involves removing the floc particles from the treated water, and sending the separated flocs to waste treatment where the stream is dewatered and thickened to ensure it has the desired solids content set by the client.

Main objectives:

(i) Reduce the solids load on the processing units downstream, particularly the filtration system, by separating the floc particles/bundles from the treated water.

(ii) Send a waste stream to the waste treatment section of the plant which contains as high a solids content as possible. The higher the solids content of the waste stream, the less water needs to be removed and recycled to the treatment process after waste thickening and dewatering.

Process employed: Floc blanket clarification. In a floc blanket clarifier, the coagulated water enters up through a blanket of previously formed solids, thus encouraging the contact of free moving floc particles with the floc bundles in the sludge blanket, resulting in improved flocculation. Over time the sludge blanket thickens and is suspended at the base of the tank as a result of the upwards motion of the entering water. Once the sludge blanket thickness reaches the design thickness, the top of the blanket will settle into the hopper where it can be sent to waste treatment.

Given below is a comparison of the three main clarification technologies available. Data used to provide a fair comparison were obtained from: (Schutte, 2006), (Baruth, 2005), (Binnie and Kimber, 2013), (Crittenden et al., 2012), (Droste, 1996), (Johnson et al., 2009)

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Table 2 – Summary of the advantages of using a floc blanket clarifier.

4.3.2.2 Pretreatment Required The raw water entering the WTP must be pre-treated prior to entering the clarification system. Described in this section are:

x Purpose of chemical addition

x Storage of chemical

x Method of chemical dosing

x Process control employed

Alum Dosing: Purpose of chemical addition: added to the raw water prior to clarification in order to enhance coagulation of raw water impurities and thus improve their removal in the clarification process.

Storage of chemical: As requested by the client, two weeks worth of chemical will be available on-site. For the dosages of alum required this equates to 210 m3 of storage, 110 m3 each tank (see Appendix 17). The dimensions of these two storage vessels are given below (rounded up to nearest 0.25m). Recommended material of construction is included also (Alumina Chemical Solutions, 2003):

Table 3: Summary of alum storage tank dimensions and construction materials.

Dimension Height 10 m Diameter 4 m Volume 125.67 m3 Material of construction Type 316 stainless steel Location on-site NW corner

Floc Blanket Clarification Pros x Hopper-bottomed clarifiers the preferred option for high turbidity

waters, with the safe upper limit being 500 NTU (as long as equipped with suitable scrapers)

x Low head loss operation x No air saturator required so operating costs are reduced x More flexible to changes in operating conditions x Able to deal with large fluctuations in contaminants x Development of established clarification technology (hopper-bottomed

upward flow clarifiers) x Combines flocculation, coagulation and sedimentation

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Method of chemical addition: The coagulant must come into contact with all of the suspended particles present in the raw water in order for the coagulation process to be effective, therefore it is recommended that the alum is added to the raw water at a point of high turbulence as this will provide ideal conditions for effective mixing/coagulation (EPA, 2002).

Normally, such mixing is provided by either static mixers or by flash mixers depending on the nature of the chemical and the degree of mixing required. For addition of alum it was decided to employ in-line static mixers for the reasons listed (Kawamura, 1991):

x Commonly used for alum dosing in the water treatment industry x Lack of moving parts reduces risk of mechanical/maintenance issues x No requirement for external energy input as is required in flash mixers

The main operational disadvantage of employing static mixers is they are motionless and so the degree of mixing that they provide is simply a function of the flowrate passing the mixer. Since the throughput of water to the system will be controlled at a constant rate, the static mixer will be designed to provide sufficient mixing for the expected flowrate of raw water that is going to be permitted and so this operational disadvantage will not pose an issue.

Since these mixers are commonly used for alum dosing it has been assumed that they will provide sufficient mixing performance throughout the year, including during monsoon season. During monsoon season the coagulant dose will be much greater as a result of the higher colour and turbidity of the raw water, and so it will be necessary for the mixer to ensure the higher coagulant doses are mixed effectively with the influent raw water stream.

Helical static mixers have been shown to perform as effectively as traditionally employed back mixers, whilst producing equal filtered water turbidity when using 30 % less alum compared to when a back mixer was used (Amirththarajah, 2007). An illustration of the mixer chosen is given below:

Figure 4: Illustration of in-line static mixer flow

Process Control Employed: See Figure 4 for an illustration of the process control. The control for both chemical additions have been combined in a single P&ID since it gives a better idea of how the addition of both chemicals is related.

Lime Dosing Purpose of chemical addition: Lime is added to the raw water stream to adjust the pH of the water to the optimal pH for coagulation. When alum (coagulant) is added, the pH of the raw water falls below the optimal pH for coagulation/flocculation and so must be raised by chemical addition.

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Storage of chemical: Unlike alum storage, lime is stored in two forms on-site. Supplied as a powder, lime is first stored in two vertical silos, holding a total volume of 74.44 m3 of lime powder. The dimensions of the lime silos are given below, along with material of construction (Indachem, 2007):

Table 4: Summary of lime powder storage tank dimensions.

Dimensions Height 7 m Diameter 3 m Volume of each unit 49.5 m3 Material of construction Type 316 stainless steel Location on-site NW corner

Before the lime can be mixed with the process water it must be made into a slurry by mixing it with a set amount of water. Once the slurry is made it is then sent to a lime slurry storage vessel which allows for 2 days worth of lime slurry (based on highest turbidity conditions) to be stored and ready for use, rather than depending on the slurry being made on demand. Two days’ worth of lime slurry equates to a volume of 140 m3 of storage which will be kept in a single storage tank. In order to ensure the lime stays mixed in the solution, the lime slurry storage tank will be equipped with a mechanical stirrer and baffles.

The dimensions of the lime slurry storage tank are given in Table 5, with materials of construction (Indachem, 2007):

Table 5: Summary of lime slurry storage tank dimensions.

Dimensions Height 9 m Diameter 4.5 m Volume 143.14 m3 Material of construction Carbon steel Location on-site NW corner

Method of chemical dosing: The lime slurry storage tank will provide the necessary flow of lime slurry (see control description after P&ID) to the pH adjustment tank. This is simply a stirred tank in which the raw water, alum stream and the lime slurry will be mixed in order to provide the clarifiers with water of the correct pH for optimal performance.

Process control employed: Figure 4 shows a P&ID for the lime and alum dosing system which pre-treats the raw water prior to clarification, followed by a tabulated list of control measures in place.

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Figure 4: P&ID illustrating the flow of materials and the process control in place in the alum and lime dosing system.

Alum Storage TankLIC

SAFETY BUND

Tank Delivery

DRAIN

Raw Water From NBR

QT

FC

DRY LIME SILO

To ClarificationSystem

Tank Delivery

MDRY FEEDER

LC

DRAIN

Mains Supply

pH

M

MILOADING CELL

Dust Vent

STATIC MIXER

Lime prep/pH Adjustment

Alum dosing

P-A-101

FCV-A-101

FC

LIME SLURRY STORAGE

M

SLURRY MIXINGTANK

pH ADJUSTMENTTANK

FULL FILENAME

DRAWN BYAndrew MacDonald

REVISED

21/11/2015

PAGE

1 OF 1

TITLE

WTP Alum/Lime dosingREVISION NO.

3

P&ID

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Process Control cont.

Table 6: A list of the control valves and measuring instruments in place in the alum/lime dosing section illustrated above:

Effected Unit/Line Control valve Measurements Purpose Alum feed line

before static mixer

FC on dosing pump, P-A-101

Quality of raw water, based on

colour and turbidity

Controls the flow of alum required to allow effective turbidity/colour removal during coagulation/flocculation and sets the dosing pump flow

Lime slurry feed to pH adjustment

tank

FCV –A-102 pH of stream being sent to

clarification

Controls the flowrate of lime slurry permitted into the pH adjustment tank in order to ensure the optimal stream pH for clarification

Additional control comments:

In order to ensure there is never a shortage of lime available for pH adjustment, there is a mass indicator fitted to each silo with an alarm system which will signal when the mass of the lime silo reaches a set minimum value. This will allow:

x The lime supply to be switched to the secondary silo x Efficient time management of the dry lime deliveries to match the time at which

it is required so there is never a shortage Installed on the dry lime silos will be a dust vent. This will prevent a flammable atmosphere being created and ensure there is no risk of a dust explosion occurring on-site.

The 2 days worth of lime slurry will be replenished at the start of every working day, rather than being in continuous operation. This will reduce the time during which an operator will have to monitor the lime powder system.

4.3.2.3 Detailed Design For the detailed design the following design aspects are provided for the client:

x Optimal number of floc blanket clarifiers with cost analysis x Physical parameters x Operating parameters x Critical analysis/Operation in non-ideal conditions

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Optimal number of floc blanket clarifiers In deciding the optimal number of clarifiers to be used it was necessary to evaluate the following:

x Total cost – includes M&E and Civil costs

x Operability – how much capacity does the spare clarifier offer?

From the cost analysis (see Appendix 17) it was possible to determine the optimal number of operational floc blanket clarifiers to be 5, which equates to 6 in total to allow for the spare unit requested by the client. This choice will offer the client the best option in terms of total costs, and provides 17 % spare clarification capacity in the event that a clarifier needs to be taken off the system.

Physical Parameters The main physical parameters are provided below. Sources which were used to provide guidelines for operating and physical parameters were: (General Electric, 2013), (EPA, 2002), (Water Environment Federation, 2005), (Michigan Environmental Department, 2002), (Parsons and Jefferson, 2006), (Kawamura, 1991), (Celenza, 2000).

The physical parameters of importance are tabulated below:

Table 7: physical dimensions of designed floc blanket clarifier.

Physical Parameter Diameter 15.1 m Depth 6 m Weir width 0.5 m Flow distribution method Equally distributed flow control through pipe

splitting Floc blanket clarifier type Hopper-bottomed

Operational Parameters The main operational parameters of importance are:

Surface loading rate: Provided in the process brief (Hyde, 2015), this value expresses the volumetric rate per square meter clarifier. Given as 4 m3/m2h, this was increased by 50 % by addition of polyelectrolyte prior to clarification.

Weir overflow rate: This is the flow rate of the clarifier effluent per length of overflow weir. It is vital that the velocity of treated water approaching the weir is below a certain value, otherwise excessive solids carryover may occur.

Detention time: This is the time that the wastewater remains in the clarifier for. It is important that enough time is given for solids to settle out, otherwise they will be carried into the effluent weir and require processing downstream.

Solids loading rate: This indicates the amount of solids which can be removed for each square meter of clarifier liquid surface area. If the solids loading increases above the design value then it can be expected that there will be an increase in the solids content

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of the effluent. Therefore, it is important that this value is monitored and maintained within the design conditions.

Waste removal mechanism: Sludge cones will allow floc particles to settle and be collected as they are carried upwards in the clarifier as a result of the fluid flow.

Table 8: Operating parameters for the floc blanket clarifiers designed.

Operating Parameter Hydraulic loading rate 6 m3/m2/h Weir overflow rate 24.32 m2/h Detention time 60 seconds Solids loading rate 2.46 kg/m2h Waste removal mechanism Sludge cones Please refer to the Appendices 17 for sample calculations.

Each of the operating parameters for the designed clarification system meet the guidelines set in a number of literature sources: (Water Environment Federation, 2005), (Celenza, 2000), (Kawamura, 1991).

4.3.2.4 Process Control Provided in Figure 5 is an illustration of the flows through and the process control in place to ensure effective clarification in the floc blanket clarifiers designed.

Add to P&ID

FIC on inlet

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Figure 5: P&ID for floc blanket clarification section.

From

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Table 9: A list of the control valves and measuring instruments in place in the clarification section illustrated above:

Effected Unit/Line

Control valve

Measurements Purpose

pH adjusted water entering

FBC

FCV-B-101 Flow of water entering the clarifier

If too high a flowrate of water is admitted it may disturb the floc blanket present, as well as running the risk of allowing carryover of floc bundles into the treated water outlet weir.

Sludge cone line FCV-B-102 1.Floc blanket level in tank 2. Mass of sludge in sludge cones

Both measurements are fed to the FCV and only once either the floc blanket level reaches a certain level, or the mass of sludge in the cones a certain mass, will the FCV remove the sludge from the cones.

In addition to this control there are quality transducers which monitor the turbidity reduction through the clarification. No control is linked to these measurements but this will help provide the client with performance data which will allow them to pinpoint any segments of the WTP which can be improved or may simply require maintenance.

Note: in the P&ID measurements are only shown on one side of the clarifier. In practice this would not be the case, but leaving the other measurements allows easier understanding of the process control in place.

Additional comments:

x It is imperative that the throughput of the clarifiers is kept at a constant rate, as is the case for all of the main processing units in the treatment plant which should ideally be operated at consistent flow conditions. If for some reason the throughput does have to change, the water flowrate should be very gradually ramped up rather than allowing a sudden surge of fluid to enter the vessel. Any fluctuations in demand/supply should be dealt with either at the NBR or the service reservoir where the impact of such changes has less of an impact on the water quality produced.

x Mass of sludge in cones is important since if they are left full for too long a period, some of the sludge present in the cones may be unable to pass into the sludge cones and as a result continue their flow upwards into the filtered water weir. This is undesirable since it results in increased turbidity water passing to the filtration system (rapid sand filters). The same outcome will occur if the floc blanket layer is allowed to get too close to the effluent weir.

x The two streams leaving the process are the clarified water which passes onto the filtration system, and the sludge which goes to a balancing tank, which allow a non-uniform flow of waste water to be collected, mixed with different waste

26

sources and pumped to the waste treatment section of the plant at a uniform rate.

4.3.3 Rapid Gravity Filtration 4.3.3.1 Introduction to Filtration Section Description: After clarification has effectively removed the floc particles formed as a result of the coagulation/flocculation process, it is necessary to carry out filtration. Since the clarification stage removes such a large portion of the suspended solids in the raw water stream, filtration is seen as a polishing process which removes limited quantities of particulate matter, but acts as a secondary particulate matter removal process, removing most of the solids which have passed through the clarification stage. Process employed: Rapid gravity bed filtration is being used in both the first and second stage of filtration. Two separate filtration stages are required due to the difference in operating conditions required to move two of the main substances which it is desirable to remove – iron (stage 1) and manganese (stage 2). This method involves passing the clarified water downwards through a granular bed where solid removal occurs within the voids on the top surface of the sand filter where they accumulate during filtration. Due to their efficient backwashing system, rapid sand filters are the ideal choice for water treatment systems which are required to operate during monsoon season, since frequent backwashes can ensure the upper layer of floc particles is removed thus preventing any significant head loss from developing as a result of pore clogging. Additionally, they offer good performance over a range of water qualities and have a proven track record in the water treatment industry. First stage of filtration: For the first stage of filtration, the clarified water will be passed through a rapid gravity filter which has been designed to effectively oxidise iron and remove it from the treated water prior to further downstream filtration for manganese removal. A pH of 7 is suitable for iron oxidation and so no chemical addition is required for pH adjustment. Additionally, iron can be oxidised using oxygen present in the filter bed and does not require any chemical additive to act as an oxidising agent. Therefore, no pre-treatment is required for the stream entering the first stage of filtration, except the clarification process upstream. Second stage of filtration: The pH of the raw water effluent leaving the first stage of filtration must be raised to enhance the oxidation of manganese in the second stage of filtration, which cannot be oxidised by oxygen alone like iron can. As was described for the clarification pre-treatment stage, lime slurry will be mixed with the raw water stream to raise the pH to 9.5, ideal for manganese removal. In both stage the oxidation of both substances results in their precipitation and subsequent removal during backwash of the filters. A summary of the advantages of using rapid gravity filtration are given below, with information obtained from: (Schutte, 2006), (Crittenden et al., 2012), (Johnson et al., 2009), (Binnie and Kimber, 2013), (Baruth, 2005)

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Table 10 – Summary of the advantages of employing rapid gravity filtration.

4.3.3.2 Pretreatment Required As for the clarification pre-treatment stage, the following aspects of pre-treatment will be covered:

x Purpose of chemical addition x Storage of chemical x Method of chemical dosing x Process control employed

Lime dosing (Filtration Stage 2) Purpose of chemical addition: Added to the raw water stream entering the second stage of filtration to raise the pH to 9.5, the ideal pH for manganese oxidation. Storage of chemical: Same lime slurry storage as described for lime dosing in the clarification section (see section 4.3.2) Method of chemical dosing: As for lime dosing in the clarification system, lime slurry will be added to the raw water in a mixing vessel, ensuring the pH of the raw water entering the second stage of filtration is ideal for manganese removal. Process control employed: Please refer to the P&ID of the second stage of rapid sand filter in which the process control for both chlorine and lime addition has been included, along with the control employed in the rapid gravity filter.

Rapid Sand Filtration

Pros

x Most common type of filter used x Can deal with a wide range of turbidity levels, as will be the case

during monsoon season x Backwashing of filtration media takes very little time x Produce excellent results when dealing with NTU up to 5, with

reasonable performance 10-20 NTU x Significantly lower land use compared with slow sand filtration x Backwash cycle is quick and so frequent backwashes can be used,

e.g. during monsoon season when filter bed requires frequent washing

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Liquefied chlorine addition (Filtration Stage 2) Purpose of chemical addition: Manganese removal by means of chemical oxidation will not occur with air alone, as it does for iron precipitation in the first stage of filtration. Manganese requires a stronger oxidation agent and chlorine is a commonly used oxidant for this purpose. Storage of chemicals: As requested by the client, two weeks’ worth of chemicals will be available on-site. Chlorine is used in this part of the process, and is also added after this stage of filtration as pre-treatment for disinfection (see section 4.3.4). Therefore, the storage of liquefied chlorine will be sufficient to supply both demands for two weeks. This equates to 5.08 m3 of storage, which provides a two week store of 5.08 tonnes of liquefied chlorine. The dimensions of these two pressurised storage vessels are given below, with storage material guidelines obtained from the following sources: (Severn Trent, 2003), (WHO, 2001), (The Chlorine Institute, 2008), (White, 2010). Table 11: Dimensions and material of construction for liquefied chlorine storage. Dimension Height 1.2 m Diameter 3 m Volume 8.5 m Material of construction Welded steel storage container Location on site East (next to chlorine contact tanks) Method of chemical dosing: Liquefied chlorine gas will be injected to the system, as shown below (IEC Fabchem Ltd, 2015):

Figure 6: Dosing system used for liquefied chlorine addition, before injection into flash mixer.

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Pressurised chlorine gas leaves the storage vessel and reaches the chlorine gas feeder where it passes through a pressure reducing valve which converts the inlet chlorine stream to a constant pressure (mild vacuum) for downstream use by a pressure reducing valve. The flow of chlorine gas is then measured by a rotameter. A vacuum differential regulator ensures the pressure difference over the control orifice is maintained to allow a stable flow of chlorine gas to be permitted downstream. Poor control of this orifice would result in variable flow of chlorine downstream which is undesirable. The chlorine gas then passes onto the injector. Injectors generate the vacuum necessary for safe chlorine dosing, whilst at the same time providing easy dispersion of chlorine gas into the necessary water stream. Process control employed: Refer to Figure 7, the P&ID for the filtration stage which illustrates the addition and control of chlorine dosing. 4.3.3.3 Detailed Design For the detailed design the following design aspects are provided to the client:

x Optimal number of filtration units for both stages of filtration x Physical parameters x Operating parameters x Operation in non-ideal conditions

Optimal number of filtration units for both stages of filtration Filtration Stage 1: As was done for the clarification system, the number of rapid gravity settlers was chosen based on:

x Total cost – includes M&E and Civil costs x Operability – how much capacity does the spare clarifier offer?

The client has requested that 2 spare rapid gravity settlers be available at any time. Since they will replace the rapid gravity settler that is being taken offline, it must be of the same capacity in order to maintain a steady throughput for each of the rapid gravity settlers. From the cost analysis performed it was found that 9 operational rapid gravity filters was the optimal choice for the first stage of filtration, based on total cost being minimal, as well as each of the 2 spare filters each offering 11 % spare capacity, so 11 rapid gravity filters in total for the first stage. This also meets the recommended requirement of each individual filter having a maximum surface area of 100 m2 (Binnie and Kimber, 2013). More filters could have been added with a marginal increase in cost but it was decided that the spare capacity provided would not be sufficient, being under 10 % spare capacity in the event of filter system failure. This method of choice was used when deciding the optimal number of operational filters for the second stage of filtration as well.

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Filtration Stage 2: The same cost analysis was performed for the second stage of rapid gravity filtration. The main difference in design is the loading rate of 16 m3/m2/h which can be used to filter out manganese, compared to a much lower loading rate of 6 m3/m2/h which can be used for the first stage of filtration when the primary aim is to remove iron. From the cost analysis performed (See Appendix 17) it was found that 9 operational rapid gravity filters was the optimal choice for the second stage of filtration, based on total cost being minimal, as well as each of the 2 spare filters each offering 11 % spare capacity, so a total of 11 filters for the second stage of filtration. Physical Parameters: The main physical parameters are provided below. Sources which were used to provide guidelines for operating and physical parameters were: (Engelhardt, 2012), (The Water Treatments, 2010), (Schutte, 2006), (Kawamura, 1991), (Crittenden et al., 2012), (Droste, 1996), (NPTEL, 2010). Table 12: Physical parameters of importance in designing the RGF’s for filtration stage 1 (S1) and stage 2 (S2). Physical Parameter Length (m) 9.87 m (S1), 5.98 m (S2) Breadth (m) 9.87 m (S1), 5.98 m (S2) Height (m) 5.5 m Available surface area per filter (m2) 97.3 m2 (S1), Depth of filter layers (m) 0.3 m anthracite (upper layer)

0.7 m sand (lower layer) Water depth above sand bed (m) 1.5 m Underdrain system Precast concrete perforated lateral Operational Parameters: Table 13: Operational parameters of importance in designing the RGF’s for filtration stage 1 (S1) and 2 (S2): Operational Parameter Filtration rate control type Constant rate Throughput per filter 584 m3/h (S1), 572 m3/h (S2) Hydraulic loading rate 6 m3/m2h (S1), 16 m3/m2h (S2) Available headloss 3.5 m Backwash system Air scour and high wash rate Backwash water volume 2% works throughput Backwash frequency Every 48 hours Conc. of sludge in backwash < 0.01 % Backwash source Backwash storage tank (pumped) Dirty wash water storage Sludge balancing tank 4.3.3.4 Process Control Please see Figure 7 for a P&ID for the first stage of filtration, and Figure 8 for the second stage of filtration.

31

Figure 7: P&ID for the first stage of filtration.

Filter Fe

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Air Scour

Backwash

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Figure 8: P&ID for the second stage of filtration, including control for addition of chlorine and lim

e.

Filtered W

aterFro

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1

FCV-C-109

Air Scour

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FCV-C-108

FCV-C-110

FC

FCV-C-112

Lime

Chlorine Gas

pHIC

FCV-C-106

FCV-C-107

pH ADJUSTMENT

TANK

STATIC MIXER

33

Process Control cont: Table 14 shows a list of the control valves and measuring instruments in place in the first stage of filtration. Table 14: A summary of control for the first stage of filtration. Effected Unit/line Control

valve Measurements Purpose

Air scour line F-C-101 N/A Sets the flow of air permitted during air scouring of the sand filter. This will be a set value and so no measurement is required to set this flow.

Backwash water feed line

F-C-102 N/A Sets the flow of backwater fed to the RGF during backwashing. As for the air scour, this flow will not be changed for each run but will most likely be checked every month.

Filtered water effluent line

F-C-103 Pressure difference between water influent and effluent

As the head loss over the filter bed increases during operation, the flow controller will open the valve to maintain a desired pressure difference, and thus a constant filtration rate.

Filtered water effluent line

F-C-104 Quality (turbidity) difference of influent and effluent.

Once the reduction in turbidity is below a desirable value the effluent flow to RGF stage 2 will be stopped and redirected to the dirty wash water balancing tank.

Dirty backwash water line

F-C-105 N/A This will only be opened to allow backwash water into the balancing tank during backwash or during poor turbidity reduction,

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Table 15 shows a list of the control valves and measuring instruments in place in the second stage of filtration: Table 15: A summary of control for the second stage of filtration. Effected Unit/line Control valve Measurments Purpose Lime slurry feed line

FCV-C-106 pH of water leaving pH adjustment tank

Controls the amount of lime added to the pH adjustment tank to achieve the optimal pH for manganese oxidation

Liquefied chlorine injection line

FCV-C-107 Quality (chlorine residual) transducer on the filtered water effluent line.

It is desirable to ensure that the chlorine being added is sufficient to oxidise the manganese and so a set residual level will be maintained by setting the chlorine injection flow based on the residual level on the effluent.

Air scour line FCV-C-108 N/A Sets the flow of air permitted during air scouring of the sand filter. This will be a set value and so no measurement is required to set this flow

Backwash water feed line

FCV-C-109 N/A Sets the flow of backwater fed to the RGF during backwashing. As for the air scour, this flow will not be changed for each run but will most likely be checked every month

Filtered water effluent line

FCV-C-110 Pressure difference over filter bed

As the head loss over the filter bed increases during operation, the flow controller will open the valve to maintain a desired pressure difference, and thus a constant filtration rate.

Filtered water effluent line to chlorination tank

FCV-C-111 Quality (turbidity) transducer on filter outlet and inlet

Once the reduction in turbidity is below a desirable value the effluent flow to RGF stage 2 will be stopped and redirected to the dirty wash water balancing tank.

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4.3.4 Disinfection 4.3.4.1 Introduction to Disinfection Section Description: As the raw water from the NBR passes through the treatment plant a large fraction of the disease causing organisms are removed. However, various pathogenic microorganisms may still remain in the water, and therefore it is vital to disinfect this water to prevent the possibility of water-borne diseases being spread by pathogens present in the water.

The final stage of treatment in a water treatment plant is the disinfection of water, which focuses specifically on the killing of any pathogenic organisms, those which may cause disease. Disinfection of water refers to the addition of a calculated amount of a chemical agent (the disinfectant) for a specified period of time under specific conditions of pH and temperature.

Main objectives:

(i) Inactivate harmful pathogens to avoid the spread of waterborne diseases (ii) Provide disinfectant residual

Description: There are three main types of pathogenic microorganism which may still be present in the filtered water; viruses (Hep A & Polio), bacteria (typhoid, E.coli) and protozoa (Cryptosporidium parvum and Giardia lamblia). It must be noted that the two protozoa mentioned are resistant to disinfection by means of chlorination (using dosages acceptable in the water industry), and are best removed by treatment, rather than inactivated by disinfection. It was decided to design the disinfection process to ensure that effective control of the most resistant pathogen likely to be in the wastewater was treated.

Disinfection also ensures that any pathogenic organisms encountered from the point at which the water leaves the treatment plant to point of consumption are inactivated. In order to achieve this a residual disinfectant is added, thus ensuring if any pathogens come into contact with the treated water, the residual disinfectant will kill the harmful pathogenic organism. There is not always a need for residual disinfectant as some distribution lines will be clean and well maintained to the point it can be said there will be no pathogenic organisms present between the treatment process and the point of use.

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Process employed: chlorination with liquefied chlorine will be used to disinfect the filtered water. The advantages of using liquefied chlorine are summarised on the next page:

Table 16: Summary of the advantages of using liquefied chlorine for disinfection.

4.3.4.2 Pre-treatment Required The filtered water leaving the second stage of rapid gravity filtration must be pre-treated prior to entering the chlorination contact. Described in this section are:

x Purpose of chemical addition

x Storage of chemical

x Method of chemical dosing

x Process control employed

Sulphuric acid: Purpose of chemical addition: the pH of the stream leaving the filtration system is approximately 9.5 and must be lowered to a pH of 6.5, the ideal pH for disinfection with chlorine (Kawamura, 1991).

Storage of chemical: as requested by the client two weeks’ worth of chemical will be stored on-site. For the dosages of sulphuric acid required (peak turbidity conditions), two 1.4 m3 storage tanks were required. The dimensions and construction materials necessary are given below (Severn Trent, 2003):

Table 17: Summary of sulphuric acid storage tank dimensions and material of construction.

Dimension Height 1.92m Diameter 0.96 m Volume 1.39 m3 Material of construction Carbon steel Location on-site North

Chlorine Gas (Cl2)

Pros

x Maturity of technology which is well-established in industry x Flexibility of dosing control x Proven method for reducing bacterial and viral infections passed in water x Ease of use x Effective at even low concentrations x Effective in providing residual disinfectant for long distribution lines x Cheaper disinfection method than Ozonation and UV treatment

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Method of chemical addition: very small doses of sulphuric acid are required (only 3 mg/l) and the chemical is delivered as a 98% solution (remaining 2% is water). Thus the required dosage can be added directly to the raw water without a need for a mixing tank or static mixer.

Process control employed: please refer to Figure 8, the P&ID for the second stage of filtration in which sulphuric acid is added to lower the pH.

Lime slurry: Purpose of chemical addition: the pH of the disinfected water leaving the chlorine contact tank must be controlled at 7 to ensure it is suitable for human consumption. Leaving the contact tank the pH will be approximately 6 and so must be raised by chemical addition.

The storage of lime, the method of chemical dosing required are the same as for lime slurry added in the clarification pre-treatment, please refer to section 4.3.2.

Liquefied chlorine: Purpose of chemical addition: to disinfect pathogenic organisms present in the water and provide a disinfectant residual.

The storage of liquefied chlorine, the method of chemical dosing is the same as for chlorine addition before in filtration stage 2.

Process control employed: please refer to Figure 8, the P&ID for the second stage of filtration in which chlorine is required as an oxidising agent to allow the removal of managanese.

4.3.4.3 Detailed Design For the detailed design the following design aspects are provided for the client:

x Physical parameters x Operating parameter

Physical Parameters: The main physical parameters are provided below. Sources which were used to provide guidelines for operating and physical parameters were: (White, 2010, The Chlorine Institute, 2008, Schutte, 2006, Droste, 1996).

Table 18: Physical parameters of chlorine contacting tank.

Physical Parameter Length 14.3 m Breadth 14.3 m Volume 2898 m Baffle type Straight rectangular

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2.3.2 Operational Parameters: Table 19: Operating parameters for the chlorine contacting tank Operating Parameter Throughput 1.4 m3/s Residence time 30 minutes Chlorine dose 2 mg/l Chlorine residual 1 mg/l Chlorine requirements 241.92 kg/day

4.3.4.4 Process Control Please refer to the P&ID provided over the page. Following the P&ID will be a description of the process control in place.

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Figure 9: P&ID for chlorine contact tank

Wate

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Sulphuric AcidFCV-D-101

Chlorine Contact Tank

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Process Control cont.

Tabulated below is a list of the control valves and measuring instruments in place in the chlorination contact tank section illustrated above:

Table 20 – Control valves for chlorination

Effected Unit/Line Control valve Measurements Purpose Sulphuric acid feed FCV-D-101 pH of inlet water Controls the flow of

sulphuric added to the water inlet stream to lower the pH to the ideal pH for chlorination

Lime slurry feed to chlorine tank effluent

FCV –D-102 pH of outlet water stream

After disinfection it is necessary to raise the pH to 7 for distribution to the service reservoir.

Chlorine feed FCV-D-103 Quality (choliform) control on water effluent

Correct chlorine dosing will ensure effective disinfection. If choliform level is measured to be too high the chlorine dose will be increased accordingly.

4.3.5 Sludge Thickening 4.3.5.1 Introduction to Sludge Thickening section Description: The Thickening process reduces the volume of the waste produced by the water treatment plant from its Floc blanket clarifier (FBC) and Rapid Gravity Filter (RGF)sections and produces a sludge which is more concentrated in order to be further treated by the dewatering process (AWWA, 2011). Main Objectives:

1. Reduce the volume of the waste by removing water from the combined waste stream.

2. Produce a more concentrated sludge of higher solids content to be treated by the dewatering process.

3. Recycle the water removed by the thickener back to the main process of the plant.

Process Employed: A Gravity Thickener was chosen for the thickening process. The water industry almost exclusively uses gravity thickeners for sludge thickening. A Gravity Thickener consists of circular tank fitted with collectors or scrappers. The sludge is fed into the tank using a centre well and is allowed to settle and compact. Gentle agitation of the sludge before settling develops channels in the sludge matrix which the water can escape through and induces an increase in density of the solids. The thickened sludge is collected and withdrawn at the bottom of the tank (EPA, 2003 and Crittenden et al, 2012).

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Gravity thickeners have multiple advantages and are ultimately the best method for the thickening process. They are simple to operate and maintain with lower operating costs able to handle higher solid concentrations than other thickening methods such as Dissolved Air Flotation (DAF) In addition, no extra energy input is required and they are widely used, making gravity thickening a relatively mature technique. (AWWA, 2011, ICE, 2013, Crittenden, J.C et al, 2012, EPA, 2003, Waterworld.com, 2015). A sludge holding tank is used to contain sludge outputted from FBC and the two RGF sections. A sludge storage tank is also required to collect the sludge from these streams and to allow the sludge to settle before dewatering respectively. Detailed calculations of the sizing and cost of these are included in the Appendix 17. The holding tank has a capacity for one day holding and the storage tank for three days. 4.3.5.2 Pre-treatment Required The sludge entering the gravity thickener section must be pre-treated prior to entering the section. Described in this section are:

x Purpose of chemical addition x Storage of chemical x Method of chemical dosing x Process control employed

Purpose of chemical addition: Polyelectrolyte is required to be added to assist in the thickening process of the sludge as stated in the process brief. Gravity Thickeners are polymer dependent, i.e they will not thicken the sludge properly unless polyelectrolyte is added accordingly. Storage of the chemical: The dose required is 5 kg per tonne of dry solids as stated in the process briefs. The calculated polyelectrolyte dose is given in the thickener specifications table in the following detailed design section. Detailed calculations of the polyelectrolyte dose and the storage tank required are given in the appendices. Two weeks’ worth of chemical storage will be available on site as requested by the client. The specifications of the polyelectrolyte storage tanks are given below:

Table 21 – Polyelectrolyte storage tank specifications

Unit Polyelectrolyte storage tank Number of units required 2 Volume of polyelectrolyte to be held 2.09 m3 Volume of tank 2.46 m3 Tank shape Circular Diameter of tank 1.37 m Area of tank 1.47 m2

Depth(height) of tank 1.67 m Location on-site Method of chemical dosing: Polyelectrolyte is provided as a powder and is stored as such. It can be added straight to the combined sludge stream entering the thickener as powder without dilution with water as the polyelectrolyte dissolves upon addition to the water.

42

Process control employed: See Figure 12, the P&ID for the sludge thickening and dewatering section. 4.3.5.3 Detailed design For the detailed design the following design aspects are provided for the client:

x Design specifications of the gravity thickener, sludge holding tank and sludge storage tank including tables of parameters and gravity thickener diagram

Design specifications: The mass of sludge solids produced in the water treatment plant was calculated based on the formula provided in the design brief (see Appendix 17). Detailed calculations on how to size the thickener and tanks can be found in the appendices. Included below are the specifications for the thickener and the tanks alongside a diagram of the thickener. Table 22: Gravity Thickener specifications Unit Gravity Thickener Number of units required 4 in operation with 1 backup unit Depth 3 m Diameter for each thickener 14.3 m Area for each thickener 160.6 m2

Volume for each thickener 481. 8 m3

Total Thickener diameter 71.5 m Total Thickener area 803 m2

Total Thickener volume 2409 m3

Polyelectrolyte dose 268.14 kg/day Table 23: Sludge holding tank specifications Unit Sludge Holding Tank Number of units required 1 Volume of sludge to be held 8887.42 m3 Volume of tank 10500 m3 Tank shape Rectangular Length of tank 50 m Width of tank 35 m Area of tank 1750 m2

Depth of tank 6 m Table 24: Sludge storage tank specifications Unit Sludge Storage Tank Number of units required 1 Volume of sludge to be held 3217.66 m3

Volume of tank 3780 m3

Tank shape Circular Tank diameter 32.7 m Area of tank 840 m2

Depth of tank 4.5 m

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Figure 10: Typical Gravity thickener diagram (AWWA,2011): 4.3.5.4 Process Control Please see Figure 12 for a P&ID for the sludge thickening and dewatering section. Table 25 below gives a summary of the control affecting the sludge thickening process. Process control cont: Tabulated below is a list of control valves in place in the thickening process of the waste treatment section illustrated above Table 25: Control valves in thickening section Effected Unit Control valve Measurements

taken Purpose

Sludge holding tank, Thickener

FCV-E1 Sludge solids flowrate level

To manipulate the polymer dose added to the sludge stream(stream 33) for the thickener

Main Process line FCV-E2 Flowrate of the recycle stream from the thickener(stream 39)

To control the recycle stream flowrate back to the main process line

Sludge storage tank

FCV-E3 Sludge flowrate present in the gravity thickener

To control the sludge outflow from the thickener to the sludge storage tank

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4.3.6 Sludge Dewatering 4.3.6.1 Introduction to the Sludge Dewatering section Description: Following the thickening process. The Dewatering process is used downstream of the gravity thickener and sludge tanks to further reduce the water content of the waste streams in order to meet the requirements for disposal to landfill Main Objectives:

1. Reduce the volume of the sludge stream from the thickener by removing more water.

2. Produce a more concentrated sludge of solids content of 20% to be disposed of to landfill to meet the legislation requirement.

3. Recycle the water removed from the thickener output sludge stream back to the main process of the plant

Process employed: A plate and frame filter press was ultimately chosen for the dewatering process. The process is carried out at high pressure. The design consists of a number of plates or trays supported in a frame with a filter cloth mounted on each plate’s face. Sludge is then pumped into the press. For the plate and frame press, this is carried out until the chambers or cavities between the trays are completely filled. The liquid is then forced through the filter cloth and plate outlet by applying pressure. Finally the plates are separated and the sludge is removed (Crittenden et al, 2012). Filter presses are the best choice for the dewatering process due to their multiple advantages such as their high dewatering efficiency (a 20% solids content can be obtained), producing the highest solids content of all the dewatering methods, low chemical consumption and they are a relatively mature technique. 4.3.6.2 Detailed Design For the detailed design the following design aspects are provided for the client:

x Design specifications of the gravity thickener, sludge holding tank and sludge storage tank including tables of parameters and gravity thickener diagram

Design specifications:

Detailed calculations on how to size the Filter presses can be found in the appendices. Included below are the specifications of the filter presses and a typical filter press diagram.

45

Table 26: Filter Press specifications Unit Filter Press Number of units required 4 in operation with 1 backup unit Plate Size 1500 mm Overall Press width 2225 mm No of pressings per week 112 (28 per press) Cake thickness 40 mm Dry Solids Load 375. 39 tonne/week Cake Volume 14.74 m3

Number of chambers 86 (per press) 430 (total) Overall Press Length 39307.31 mm Total Press Area 87.5 m2

Area per press 17.5 m2

Figure 11: Typical Filter Press diagram (AWWA, 2011) 4.3.6.3 Process Control For an illustration of the flows in this section of the water treatment plant and the necessary process control in place to ensure effective waste treatment is carried out see the thickening section. The dewatering part is included in the P&ID included there Tabulated below is a list of control valves in place in the dewatering part of the waste treatment section:

46

Table 27: Effected unit Valve Measurements

taken Function

Filter Press FCV-F1 Flowrate of sludge in sludge storage tank

To control the level of sludge entering the press from the sludge storage tank

Filter Press PCV-F1 Pressure of the filter press

To control the pressure levels in the filter press

Filter Press PSV-F1 Pressure of the filter press

Relive pressure in the filter press i.e prevent overpressure

47

Figure 12: P&ID for sludge thickening and dew

atering section.

48

4.3.7 Plant Layout In this section, the main factors which determined the proposed plant layout will be discussed. The client specified the treatment site dimensions as 210 m by 120 m, thus the site plan designed aimed to fit within those area requirements. The main factors considered in creating the plant layout were (Johnson et al., 2009) (Baruth, 2005):

1. Hydraulic profile – where possible, flow through the plant should be gravitational. This has both operational and financial incentives. From an operational standpoint, it is inadvisable to pump water between clarifiers and filters since this can be detrimental to the floc formations and result in the break-up. From a financial standpoint, making efficient use of gravitational flow can reduce O&M costs of removing pumps from the system.

2. Climatic conditions – for a plant which is located in an area prone to severe monsoon seasons, it is important to avoid sitting any structures below the highest flooding levels. Doing so helps avoid the costly and difficult operation of uplift problems.

3. Ease of access – this serves a number of purposes on-site, including raw material delivery, access to allow site maintenance without any difficulty and unsafe conditions arising. The internal road layout must provide adequate space for chemical delivery and unloading without resulting in road blockages when delivery trucks are parked.

4. Chemical storage and dosing lines – any pipeline transporting chemicals should not be laid in areas where a leakage could result in damage to other lines or cause injury to personnel.

5. Degree of redundancy – standby units have been included as requested by the client, thus space will be taken up on-site by units which are not always operational. From an operational standpoint, increasing the total number of units reduced the total area required, though the degree of process flexibility available was reduced since the number of spare units is fixed.

6. Provision of site security – serves two main purposes. Preventing public access on-site helps prevent any trespassers which will be unaware of the potential hazards on site, and will prevent trespassers from causing any damages on-site, both undesirable outcomes. This is vital in ensuring the people of Sandalwood are provided with a safe source of drinking water.

7. Location of support facilities – maintenance workshops, laboratories and office workspaces have to be included. Maintenance workshops allow for equipment to be fixed/cleaned/repaired on-site rather than having to rely and wait on an external company. Plant laboratories allow for process control testing and analysis of water quality at different points in the treatment process. These results can then be compared to expected performance to highlight any areas which are not performing to a satisfactory standard.

49

Fig. 13 – Final Plant Layout

50

4.3.7.1 Hydraulic Gradient At the initial intake point to WTP the flowrate will be at 1.4m3/s after this point this section covers the flow through the rest of the WTP. Flow though the water treatment plant has been design to ensure efficient use of space and taking best advantage of the gradient of the slope to design a layout; which reduces consequent operation running costs to the client. Additionally, pipe selection charts will be used at each point to select a pipe diameter which has the least losses for required mass flow. The gradient from the high-point to lowest in the treatment plant is known to be 10m from South West to North East (project brief(Bob Hyde), 2015). It was important to design the layout of each process to take best advantage of this natural slope. Head losses because of the use for two rapid gravity filters is estimated to be 3m each, therefore contributing to a total head loss of 6m. Effects of viscous friction in processes and pipes are ignored due to the complexity of the calculations. Figure 108 in appendix 17 shows the Hydraulic Gradient through the process plant, plant layout ensures a head drop between every process, from this it can be assume pumping will not be required between processes; the water will flow purely under the effects of gravity. However, small a pump will be placed between processes 2 and 3 to overcome the head loss at the filter stage. Transporting water between gravity filters, pumps from the outlet located at the bottom of one to the top of the second filter. This will be a 35kW pump able to pump at the required flowrate at 1.4m3/s. From process 3 and 4 excavation work to lower the foundations of the Process 4 (Clarification Tanks) by 0.5m will consequently eliminate the need for a pump. The sludge treatment section of the plant makes best use of hydraulic gradient where possible. Although it was decided it was not efficient to rely solely on hydraulic gradient to carry the flow through the process due to the composition of sludge. Whereby, due to the thickness of the sludge it could not be certain that friction in the pipes and viscous friction may cause blockages in the pipes. Therefore, between each process a sludge pump will be used to ensure flowrate does not drop below the desired level.

51

5. Sludge Treatment Process The detailed calculations and design justifications for the sludge treatment process and can be found in appendix 18. Fig, 14 – Diagram of sludge storage process

Sludge Dewatering process produces waste sludge with 20% solids.

MAIN SLUDGE STORAGE TANK: - Capacity ≈ 2200m3 - Diameter = 12m - Height = 20m

Sludge is temporarily stored in large storage tanks, capable of storing 1 week worth of sludge each

Sludge pipeline splits into two – taking sludge to a main tank and to a secondary tank for use as a contingency. The secondary tank will be used if the main tank fails or if future demand increases and expansion is required

SECONDARY SLUDGE STORAGE TANK: - Capacity ≈ 2200m3 - Diameter = 12m - Height = 20m

SLUDGE REMOVAL: Six 10,000gallon trucks will remove the sludge from the tanks daily LA

NDF

ILL

AMENITIES: - Cleaning room - PPE storage

PUMPS: - Wangen Hopper Feed screw pump for each pipe VALVES:

- A control valve will be placed in each pipe

Mass flow rate = 255tonnes/day Sludge density = 1080kg/m3 Volume flow rate ≈ 240m3/day

NOTE: If further investigation deems it appropriate, a rail link could be built to the landfill site, to make sludge removal easier and minimise the traffic disruption.

52

5.1 Sludge Tank Structure Design Detailed design calculations of the tank structure, as per British Standards, can be found in appendix 18. Fig. 15 – Detailed drawing of sludge storage tank (Drawing not to scale)

Tank diameter = 12m Tank capacity = 2200m3

Tank

hei

ght =

20m

Lower course height = 3m, Steel wall thickness = 10mm

Upper course height = 17m, Steel wall thickness = 5mm

5m from bottom of tank to ground

ROOF THICKNESS = 5mm

BOTTOM PLATE THICKNESS = 125mm

A structural steel frame will be used to support the tank. The tank will be raised to allow trucks to easily pass underneath.

53

6. Water Conveyance 6.1 Water Demand To begin any water conveyance design, it is important to determine the required demand. This design is based on the expected 2030 population of Sandalwood calculated in Appendix 19. Fig. 16 – Estimated water demand and design value of water demand for a 2030 population.

6.2 System and Component Design

6.2.1 System Characteristics and Component Selection A pumped pipe network acts as a system and therefore both the pump and pipe must be designed together. The outline method and results are given in this section and detailed calculated are included in Appendix 19.

Fig. 17 – Outline method of system characteristic construction. After applying this method, the following components can be determined:

- Pipe diameter - Number of pump stations - Number of pumps in parallel - Total number of pumps - Pump power rating

The results are detailed on Figure 18.

Construct the pipe

characteristic curves for each phase comparing each of the

four diameters

Construct the pump

characteristic curves for a number of

pumps

Superimpose both curves

and manipulate to

achieve the required flow

at an acceptable efficiency

Every working

solution can then be

compared economically and the most cost effective

solution is chosen

Sandalwood Potable Water

Demand in 2030:

1.15m3/s

After considering 20% leakages in the system

Design Value of Water

Demand in 2030:

1.4m3/s

54

Fig. 18 – Map displaying the phases and design information concerning pump selection and number of pumps per phase.

PHASE A Pipe Diameter: 1.2m Pump Stations: 1 Number of pumps in parallel: 3 Total Number of Pumps: 6 Pump Power Rating: 500kW

PHASE B Pipe Diameter: 1.2m Pump Stations: 4 Number of pumps in parallel: 3 Total Number of Pumps: 24 Pump Power Rating: 900kW

PHASE C Pipe Diameter: 1.2m Pump Stations: 3 Number of pumps in parallel: 3 Total Number of Pumps: 18 Pump Power rating: 900kW Pump Power Rating: 900kW

55

6.2.2 Pipe Cross Sections The following drawings are general cross sections and profiles of the pipeline with dimensions calculated in Appendix 19.12. Phase A and C are both over-ground while Phase B is underground. The material, encasement and lining are discussed in Appendix 19.15 Fig. 19 – Side elevation of above ground pipeline set up Fig. 20 - Cross section of above ground pipeline set up

6.1m

6.1m

1.226m 0.66m 0.35m

2m

0.19m

2.66m

0m

-2m

0.5m

SOIL

BEDROCK

PIPELINE

Pipeline support

Pipe tie

BEDROCK

SOIL

-2m

0m

1.4m

2m 2.66m

0.66m 0.35m

Internal diameter = 1200mm Pipe thickness = 13mm

PIPE MATERIAL: Ductile Iron INTERNAL LINING: 19mm spun concrete ENCASEMENT: Light-coloured protective paint

56

Fig. 21 – Cross section of below ground pipeline set up

6.3 Pump Stations & Housing All justifications and calculations can be found in Appendix 19.5

Fig. 22 – Typical sketch of the pumping houses

SOIL

BEDROCK

-2m

0m 1.4m

2m Internal diameter = 1200mm Thickness = 12mm

TYPE 1 FILL

PIPE MATERIAL: Ductile Iron INTERNAL LINING: 19mm spun concrete ENCASEMENT: Polyethylene film

57

Fig. 23 – Typical dimensions of the pumping houses Fig. 24 – Flow diagram of a typical pump station layout

Pumps

58

6.4 Intake The intake design covers the main features of removal of water from NBR and subsequent transportation to WTP. The elements of the intake design are as follows:

- Suction Bell Design - Suction Piping - Intake Pump

6.4.1 Suction Bell Design Important factors when designing the suction bell are too reduce the risk of vortex formation and ensure no large object are in the water flow. The suction bell will have a chamfered edge and a stainless steel strainer. A foot valve is located at the bell of the suction pipe, this is essential for the initial priming of the system. The suction bell will be position a minimum of 2m below the average water level calculation shown in Appendix 19.6.

6.4.2 Suction Piping The pipes are designed to reduce the length of pipe used and ensure they are as smooth as possible to reduce loses and create a more efficient design. Eccentric reducers are installed just before the pumps to further reduce the risk cavitation.

6.4.3 Intake Pump The pump at the intake needs to be able to pump raw water. Horizontal Split Case Pumps have the capacity to pump raw water therefore are used. Further details of the pump used can be seen in Appendix 19.10.

6.5 Valves The following valves have calculations and justifications found in Appendix 19.14.

6.5.1 Wash Out Valves Wash out valves and branches of 200mm diameter should be installed at every low point in every 10km section between the butterfly valves and the discharge should be in to a concrete pit with an overflow to the nearest watercourse.

6.5.2 Air Valves Recommended general locations for air valves can be found in Appendix 19.14.2. Specific locations can only be determined once detailed topographical maps are investigated.

6.5.3 Stop Valves Stop valves every 10km have been specified and will be achieved using butterfly valves.

6.6 Surge Protection Surge protection of the pipeline takes the form of mechanical prevention. All stop valves will have a minimum time of closure of 3 seconds.

59

7. Bridge Design over Bhima River A steel truss bridge structure will be used to cross the pipeline over the 25m-wide Bhima River. Figures 25 - 30 show detailed drawings of the truss arrangement. A ‘deck truss’ form has been used to allow the pipeline to cross over the truss, without members causing obstructions during construction and maintenance. The detailed calculations and design justifications for the truss bridge can be found in appendix 22, along with a table showing the maximum forces in each member.

Fig. 25 – Full side elevation of Truss bridge over the Bhima River

27m

25m

≈3.5m

6m span between pipeline supports at truss nodes

1.5m

Concrete Bridge abutment

Concrete Bridge abutment

GRANITE EMBANKMENT

GRANITE EMBANKMENT

Gate at either end to prevent unauthorised access PIPELINE

Handrail around bridge to protect maintenance workers using the walkway

on either side of the pipeline

60

Fig. 26 – Side elevation detail of truss structure

6m spacing between pipeline supports on truss nodes – supported on cross members

3m

1.5m

45° 45°

0.35m

Pipe external diameter = 1226mm

Railing width (large) = 2m Railing width (small) = 1m

Railing height = 1.1m

0.55m Pipe support height = 0.66m

61

Fig. 27 – Detail of pin support Fig, 28 – Detail of roller support

0.1m

Steel square section truss members, where:

- Width = 0.1m - Area = 0.01m2 - Strength = 205MPa

0.22m

0.2m

CONCRETE ABUTMENT

PIPELINE

GAT

E

RAILING BANNISTER

0.06m

CONCRETE ABUTMENT

0.22m

0.2m

0.06m

Pipeline support thickness =

0.19m

0.1m

62

Fig. 29 – Detail of truss joint Fig. 30 – Section through truss structure

0.1m

Each member has a connection fillet attached that can be bolted onto the adjoining joint piece

0.5m

0.14m

0.14m

0.01m

0.14m

0.2m 0.2m

1m-wide walkway for maintenance

1.1m

1.5m

0.1m

3.4m

1.4m

0.35m 0.66m

0.03m deep steel grate flooring

Handrail to protect maintenance and construction workers Pipe external

diameter = 1226mm

Steel pipe support

63

8. Bridge Design over Arkavathi River A cable-stayed bridge structure will be used to cross the pipeline over the 250m-wide Arkavathi River. Figures 31 - 37 show detailed drawings of the bridge. The detailed calculations and design justifications for the cable-stayed bridge can be found in appendix 23. Fig. 31 – Full side elevation of cable-stayed bridge over Arkavathi River

250m

Cable spacing on deck = 14.7m

Tower height = 50m

Cables stretching back on to land are anchored to the ground with concrete abutments – detailed in fig. 37

64

Fig. 33 – Section through deck Fig. 32 – Section through tower and deck

Steel able diameter = 90mm

1m-wide walkway either side of pipe for maintenance access

Column width = 800mmx800mm Detail cross section in fig. 35

1100

mm

Steel grate walkway = 30mm thick

Deck is comprised of 3 steel I-beams – Section 914x305x224

1m

0.66m

0.8m 0.05m steel plate

0.05m steel plate

0.05m

910mm

1.5m 1.5m 0.6m 0.6m

Cable

65

Fig. 34 – Front Elevation of Tower

Fig. 35 – Concrete tower cross-section

0.8m

0.8m

0.8m

0.8m

1m

3.4m

Cable spacing on tower = 6.25m 20m

20m

6.6m

50m

0.8m

0.8m

0.8m

8 steel reinforcing bars of 40mm each

Cover = 50mm 50mm

66

Fig. 36 – Side elevation detail of tower The cables extend away from the river for 125m. Rather than extending the deck out this far, the cables are anchored to the ground using large concrete abutments – detailed below. Fig. 37 – Detail of cable abutment on land either side of river

0.8m

Cable spacing on tower = 6.25m

Railing on either side of deck to protect maintenance workers on the walkway

Fencing and gate on either side of bridge to prevent unauthorised access

Pipe support spacing on deck = 6m

Cable diameter = 90mm

Θ = 23°

2m

1.5m

1m

0.5m

67

9. Over-ground Pipeline Crossing Design Between the reservoir and the water treatment plant (Phase A), the pipeline will run over-ground for approximately 25km. The pipeline will also run over-ground for 50km between Kanakapura and the service reservoir (Phase C). This section outlines the designs that ensure the disruptions of an over-ground pipe to the local population and animals are minimised.

9.1 Public consultation The stakeholder engagement team will take responsibility for liaising between the local population and design team to establish appropriate crossing points over the pipe. Crossing points along the over-ground pipeline will allow farmers and animals to cross and the crossing points must therefore be strong enough to protect the pipe from heavy vehicles and large animals.

9.2 Consideration of local wildlife It is assumed that the existing road is already a deterrent to animals and therefore the over-ground pipeline will have a minimal additional disruption to the local wildlife. Local ecologists and farmers will be consulted to establish the behaviours of local wildlife – from this appropriate crossing points can be designed. The pipeline will be raised 0.35m to allow smaller animals to pass underneath the pipe. This will also provide access to the whole surface area of the pipe for maintenance and repairs. Crossing points will be constructed over the pipeline approximately every 350m (ESRD, 2014).

- Phase A = 70 crossings - Phase C = 140 crossings

Total number of crossings = 210 As per environmental guidelines (ESRD, 2014), these crossings will be 8m wide and have an approach slope of 1:6. Trees and excess soil from the underground pipe excavations will be used to landscape the areas around the over-ground pipe to naturally guide wildlife towards the pipeline crossings.

9.3 Crossing design drawings Figures 38-41 show drawings of the proposed crossing point design.

68

2m

2m

2m

2m

2m

1.4m

0.1m

1:6 sloped approach to crossing

Fig. 38 – Perspective view of over-ground pipe crossing

69

EXI

STI

NG

RO

AD

8m

4m

12m 12m

2m 0m

0m

2m

PIP

ELI

NE

Fig. 39 – Plan of over-ground pipe crossing

1:6 sloped approach to

crossing

Landscaping around crossing point to naturally draw wildlife towards the crossing and away from the pipeline

Section A

70

Fig. 40 – Side elevation detail of concrete pipe support for over-ground crossing Fig. 41 – Section A detail of concrete

-2m

2m

0m 0.9m

2m

1.75m

0.35m 1m

0.3m

D=1.3m

BEDROCK

SOIL

CONCRETE

2m

-2m

0m

2m

2m

3.9m 0.35m

1m

D=1.3m

BEDROCK

SOIL

GRAVEL AND SOIL BACKFILL

CONCRETE

71

10. Under-road Pipeline Tunnelling Design The underground pipeline in phase B must cross underneath the existing road, between the water treatment plant and the Arkavathi River. To ensure minimum disruption, a micro-tunnelling technique will be used to install the pipeline beneath the road, without closing the road for the local population. Micro tunnelling is a specialised form of pipe jacking which involves a Hydraulic jack forcing a tunnel boring head (shield) through the soil, with the pipe casing being driven immediately behind. The water pipeline is subsequently pushed through the pre-installed pipe casing using the same hydraulic jack. Figure 42 shows a sketch of the tunnelling process. The detailed calculations and design justifications for the under-road tunnelling can be found in appendix 24.

Fig. 42 – Sketch showing the micro-tunnelling process

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11. Service Reservoir To ensure a constant supply of treated water, four service reservoir tanks will store enough water to satisfy the demand for 24 hours – providing enough time for any repairs to be made to the water treatment and conveyance infrastructure. Figures 43-51 show detailed drawings of the service reservoir tanks. The detailed calculations and design justifications for the service reservoir can be found in appendix 25.

Fig. 43 – Arrangement of Service Reservoir pipe network

DIAMETER OF EACH TANK = 60m CAPACITY OF EACH TANK = 28,000m3 TOTAL RESERVOIR CAPACITY = 112,000m3

Pipe to City: Diameter = 300mm

Pipe to City: Diameter = 300mm

Pipe to City: Diameter = 300mm

Pipe to City: Diameter = 300mm

Main pipeline: Diameter = 1200mm

Splitting chamber

Inlet pipeline: Diameter = 300mm

Reservoir Tank 1

Reservoir Tank 2

Reservoir Tank 3

Reservoir Tank 4

Drainage Pipes: Diameter = 300mm

Inlet pipeline: Diameter = 300mm

Inlet pipeline: Diameter = 300mm

Inlet pipeline: Diameter = 300mm

2 doors on each tank allow maintenance workers to enter the tanks when empty.

73

11.1 Tank Structure Design Fig. 44 – Side Elevation of Service Reservoir Tank Stiffening rings around the outside of the tank will add strength – making it more resilient to wind loading and negative pressures.

A top corner stiffening ring will be at the top of the reservoir tank

Two secondary stiffening rings will be 5m and 10m from the bottom of the tank

Fig. 45 – Section detail of top corner ring Fig. 46 – Section detail of secondary stiffening ring

74

Fig. 47 – Plan view of tank roof

A central ring beam in the roof connects the roof beams to a ring beam at the top of the tank inside the wall

Fig. 51 – Section detail of central ring beam

Primary beams and secondary beams support the tank roof

Fig. 49 – Section detail of Secondary Roof beam Fig. 48 – Section detail of Primary

Roof beam

Fig. 50 – Section detail of outer ring beam on wall

75

11.2 Inlet Design If the water in the reservoir reaches a critically high level then to help prevent backflow of water in the pipe a rubber duckbill non return valve will be inserted at the end of the pipe as shown in Figure 52 as well as having a flow control valve to shut off the incoming flow.

Fig. 52 – Rubber duckbill non-return valve on inlet pipe to prevent backflow

11.3 Outlet Design Each service reservoir will have 2 outlet pipes:

- One for delivering potable water to Sandalwood - One for emergency cases where the primary outlet fails/in event of

overflowing. Each of the outlet pipes will then merge into one pipe, which will provide the water to Sandalwood. If the water becomes contaminated then a valve will open which will divert the water to drainage. The outlet pipes will be installed 100mm above the reservoir base to prevent the intake of debris.

11.4 Inlet and Outlet connection Inlet and outlet pipes will connect to the reservoir tank with a hubbed slip-on flange in which the pipe can be fillet welded onto the flange and the flange bolted to the service reservoir wall.

Figure 53: Design dimensions for inlet/outlet flanges.

D=585mm K=500mm L=42mm B1=327.5mm R=12mm N2=355.9mm C2=68mm H1=80mm

76

This flange will use 16 size M39 bolts each with 3 flanges on each reservoir: 1 for inlet and 1 for each outlet. The flange is displayed in Figure 54.

Figure 54 – Flange connection for inlet/outlet pipe to service reservoir.

11.5 Ventilation Design The ventilation will help to relieve pressure and prevent vacuum conditions. Figure 55 displays the vent design for the roof, each vent will contain a screen for catching debris to protect the reservoir interior from becoming polluted. Due to the large size of each service reservoir there will be one vent near the roof centre and 4 extra ones placed near the walls separated by 90° to promote cross flow ventilation.

Figure 55 – Vent for service reservoir roof.

77

11.6 Baffle Wall Design Baffle walls will promote plug flow in the service reservoir tanks. Each baffle wall will be 40m long, 30mm thick and 10m high constructed from high strength steel. Figure 56 shows the proposed baffle wall arrangement for each tank.

Figure 56 – Proposed baffle wall arrangement for the Sandalwood service reservoirs. They will be supported on their bottom length and one side to attach them to the service reservoir base and wall respectively using the support in Figure 57; the support itself will be welded to the reservoir floor/wall. M30 bolts will be used for each threaded hole every metre; 40 bolts on each base and 10 on each wall giving a total number of 100 bolts.

Figure 57: Segment of the baffle wall supports.

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12. Control Systems The monitoring and control of the various parts are crucial to the continuous operation of the potable water scheme; the P&ID’s of high risk elements are displayed in this section. All results will be sent electronically to the local control panel from the measuring instruments which will also be transmitted to a central control unit in the WTP to record a history of all technical issues throughout the project and with the intention that future action can be taken to prevent any of these occurances.

12.1.Water Treatment Plant Control System P&ID’s are provided for the WTP:

- Alum/lime dosing - Floc blanket clarification - Rapid gravity filtration - Disinfection - Sludge treatment

These have been included in Section 17.

12.2 Sludge Storage Control System A number of parameters need to be monitored and controlled in the silo during operation; Figure 58 displays a P&ID of the silo’s control system.

Figure 58: P&ID of sludge silo control system.

79

Table 28: P&ID symbol meanings for the silo control system. Component Symbol

Sludge pump (screw)

Level transmitter 1

Level transmitter 2

Pressure transmitter

Local control panel

Relief valve

Alarm (light and sound)

Control valve

Process direction

Signal

Electrical connection

Piping Pressure plays an important role in the safe operation of the storage silo and will be monitored through a pressure sensor. If the sensor detects pressure levels above the specified safe limit it will send a signal to the control panel located at the silo site which will in turn activate the relief valve at the top of the silo relieving the pressure. If the pressure has not been reduced to a safe working level then another signal will be sent to the control panel which will shut off the conveyance of sludge to the silo and instead the incoming sludge will be sent to the smaller emergency silo until the problem has been resolved. The control system must also contain a method of measuring how full the silo is. A level sensor will be installed 0.5m and 19m from the bottom of the silo to measure if the silo is almost empty and if it is filling up to a critically high level respectively. The upper level sensor will send a signal to the control panel to shut off the sludge intake and redirect the incoming sludge to the emergency silo as well as sound the alarm.

80

12.3 Pumps Control System Figure 59 displays the P&ID for each pump with Table 29 containing the component symbols that are new to this diagram. This control system will measure:

x Pressure x Temperature x Flow rate x Vibrations

If any of these exceed allowed limits during the pump’s operation will cause the local control panel to shut off the butterfly valves in the pipeline.

Figure 59: P&ID of a pump. Table 29: P&ID symbol meanings for a pump.

Component Symbol Butterfly valve

Temperature transmitter

Vibration transmitter

Horizontal split case pump

Venturi meter

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12.4 Pipeline Control System Figure 60 displays the P&ID for the pipeline. Flow rate is the most important parameter to measure here and is measured through a venturi meter; if an abnormal flow rate is detected then a signal will be send to the local control panel in the pumping station as well as the main control centre. The local control panel will send a signal to the discharge valve to shut off the flow and an alarm will activate notifying a member of staff to try and solve the problem. Table 30 displays any additional component symbols which are not in Table 28 or Table 29.

Figure 60: P&ID of a section of the pipeline.

Table 30: P&ID component symbols for the pipeline. Component Symbol Check valve

12.5 Service Reservoir Control System Figure 61 displays a P&ID of the proposed control system arrangement. Table 30 displays additional component symbols for the service reservoir which have not been displayed in any previous tables. Each service reservoir will have a pressure level sensor enabling the measurement of the water level. If the water level is too high in the service reservoir a signal will be sent to the reservoir’s emergency outlet which will open until it reaches a predefined safe level, after which it will open the inlet again. If the pressure level sensor has indicated that it is almost empty then the sensor will send a signal to the control panel indicating that there may be a problem

82

with supply to that reservoir. When checking for maintenance this sensor must indicate that the reservoir is empty before workers perform any repairs.

Fig. 61 – P&ID of service reservoir.

Table 31 – P&ID symbol meanings for the service reservoir Component Symbol

Pressure level transmitter

83

13. Lighting As the control system is critically important to ensuring continuous supply of good quality water, the control centre must be manned 24 hours a day. Adequate lighting must therefore be designed.

13.1 Control centre lighting The WTP will have the potable water scheme’s main control centre plus a kitchen and 2 WC’s for the workers. Figure 62 displays the plan view for the facilities available in the WTP.

Fig. 62 – Control centre plan view The lighting arrangements in each room must adhere to the following lighting regulations (BS EN 12464-1, 2002):

- Control centre: 150-300 lux - Kitchen: 150-300 lux - WC: 100 lux

84

DIALux lighting software was used to simulate each room to find the optimum lighting arrangements and model. Thorn Lighting has been used for simulations. The lighting arrangements, model specifications and results imported from DIALux are shown in Appendix %.

13.1.1 Control Room This room was modelled with the work-plane at a height of 0m to calculate the lighting on the floor and a room height of 2.8m where the light will be installed. Four collinear ‘Thorn Petrelux ExEn’s’ were the light arrangement of choice for this room as this meets the regulations and so is recommended to the client.

13.1.2 Kitchen This room was modelled with the work-plane at a height of 0.8m to ensure that the workers can see countertops clearly, which is the most important level for a room like this; a room height of 2.8m will be used. Three collinear ‘Thorn Menlo3 Semi-Recessed’ lights were used in this arrangement as this meets the regulations and so is recommended to the client.

13.1.3 WC These rooms were modelled with the work-plane at a height of 0m and a room height of 2.8m. Two WC’s have been installed and will consist of a single ‘Thorn Menlo3 Semi-Recessed’ light each, which meets the requirements.

13.1.4 Emergency Lighting Each of these lights can function as an emergency light. In the case of an emergency it is recommended that the light in the WC’s will work on emergency mode with a lower lux value, the same should apply with the bottom and 3rd bottom light in the control room and the bottom and top light in the kitchen – top/bottom is in reference to Figure 62.

13.1.5 External Lighting It is recommended to the client to plan and install external lighting around the WTP and service reservoir once construction has started for these areas to assist with light fixture locations.

85

14. Construction Process This section details the construction processes of the project. Fig. 63 show

s a map of the required construction sections of the w

ater treatm

ent supply system.

Fig. 63 – Map of the proposed construction

Inlet

Truss bridge

Cable-stayed bridge

4 Reservoir tanks

‘Phase A’ 25km

over-ground pipe

‘Phase C’ 50km

over-ground pipe

‘Phase B’ 45km

underground pipe

140 ‘Phase C’ over-ground pipe crossings

3 ‘Phase C’ pum

p stations

Under-road

tunnelling

1 ‘Phase A’ pum

p station

70 ‘Phase A’ over-ground pipe crossings

3 ‘Phase B’ pum

p stations Water treatm

ent plant

Sludge storage cylinder

86

14.1 Inlet construction Fig. 64 – Gantt chart for the construction of the Inlet at the raw water reservoir

0 5 10 15 20 25 30 35 40

Setting out

Excavation of foundations for inlet support

Construct formwork and falsework for concrete crossing block

Pour concrete

Let concrete cure

Install inlet pipe support

Install inlet pipe

Clear site

Testing

Day

87

14.2 Underground pipeline construction

Fig. 65 – Stage 1: Excavation and pull pipe

Fig. 66 – Stage 2: Install pipe

Fig. 67 – Stage 3: Backfill the excavation

Excavation & Pull Pipe - Continuous process along pipe section - Pipe can be transported using flatbed lorries and then carried into position by excavator with a strong sling. - Trench boxes should be used to mitigate risk of wall failure.

Install Pipe - Use sand to create a smooth graded surface for the pipeline to rest on. - Wrap the pipe in polyethylene encasement applying the appropriate taping techniques. - Lower the pipe onto the graded surface using a excavator with a strong sling.

Backfill the Excavation - Backfill should be a Type 1 material and measures should be taken to ensure that all cavities in the excavation have been filled. - An excavator can be used to backfill the excavation.

88

Fig. 68 – Gantt chart for the construction of a typical underground 10km section

14.3 Over-ground pipeline construction

Fig. 69 – Stage 1: Excavate foundation and blind

Fig. 70 – Stage 2: Construct formwork and pour concrete

0 20 40 60 80 100

Setting out

Excavate Trench

Pull Pipe

Install Pipe

Install Stop Valve

Install Air Valves

Install Washout Valve

Backfill Excavation

Day

Excavate Foundation & Blind - Use an excavator to construct the trench ready for formwork to be constructed - Blind the bottom of the excavation to allow a smooth surface for the main concrete pour to bind to.

Construct formwork & pour concrete - Due to the amount of concrete being poured, it would be advantageous to have a continuous supply of concrete trucks and a dedicated concrete gang. - Formwork should have a sufficient strength to withstand earth pressures from the trench walls. - Formwork should try to be reused to improve efficiency and cost.

89

Fig. 71 – Stage 3: Install pipe

Fig. 72 – Gantt chart for the construction of a typical over-ground 10km section

0 10 20 30 40 50 60

Setting out

Excavate Foundations

Pull Pipe

Construct Formwork

Pour Concrete

Remove Formwork

Install Pipe

Install Stop Valve

Install Air Valves

Install Washout Valve

Day

Install Pipe - Leave enough time for the concrete to harden to a sufficient strength to hold the weight of the pipe. - Lay pipe with an excavator, strong sling and guide ropes to help position the DIP into its push on joints. - Use metal steel straps to attach the DIP to the concrete support.

90

14.4 Pump House construction

Fig. 72 – Gantt chart for the construction of a typical pump station

0 5 10 15 20

Setting out

Excavate

Blind

Shutter

Install Reinforcement

Concrete Base Pour

Install Pumps

Construct Substation

Install Plant Items (electrical)

Testing

Clear Site

Day

91

14.5 Water Treatment Plant construction

Clarification Filtration 1 Filtration 2

Chlorination

SCALE

1: 3m

Service Reservoir

MAIN ROAD

Liquefied Chlorine Storage

Alum storageLime storage

Sulphuric acid storage

Sludge Balancing Tank

NBR

Lime Slurry Tank

Thickeners

Thickened Sludge

Storage Tank

Sludge Thickening

RGF-1.1 RGF-1.2

RGF-1.3 RGF-1.4

RGF-1.5 RGF-1.6

RGF-1.7 RGF-1.8

RGF-1.9

RGF-2.1

RGF-2.2

RGF-2.3

RGF-2.4

RGF-2.5

RGF-2.6

RGF-2.7

RGF-2.8

RGF-2.9

Unit Naming:FBC – floc blanket clarifierRGF 1 – stage 1 rapid gravity filter RGF 2 – stage 2 rapid gravity filterTH – thickenerFP – filter pressCT – chlorine contact tankSS – sludge siloCR – control room

Sludge DewateringFP -1-5

KeyProcess Lines:Water being treatedSludge wasteRecycle/SupernatantWash WaterAuxilliary:Site FenceRoad accessArea Limits

TH-1 TH-2

TH-3 TH-4

TH-5

SS SS

CT-1

CT-2

CR

FBC-1 FBC-2

FBC-3 FBC-4

FBC-5

Fig. 73 – Construction zone diagram for WTP

Construction Zone 2

Construction Zone 3

Construction Zone 4

Construction Zone 1

92

050

100150

200250

300

Setting out for excavationRoad construction

Excavate Zone 1Blind Zone 1

Install Formw

ork Zone 1Pour Concrete Zone 1

Let Concrete cure Zone 1Install pipew

ork Zone 1Excavate Zone 2

Blind Zone 2Install Form

work Zone 2

Pour Concrete Zone 2Let Concrete cure Zone 2

Install pipework Zone 2

Excavate Zone 3Blind Zone 3

Install Formw

ork Zone 3Pour Concrete Zone 3

Let Concrete cure Zone 3Install pipew

ork Zone 3Install steel storage tanks Zone 3

Excavate Zone 4Blind Zone 4

Install Formw

ork Zone 4Pour Concrete Zone 4

Let Concrete cure Zone 4Install pipew

ork Zone 4Install steel storage tanks Zone 4

Day

Fig. 74 – Gantt chart of WTP construction sequence

93

14.6 Tank construction – Sludge Store and Service Reservoir Note: The construction sequence is the same for both the sludge storage and service reservoir tanks. The Gantt chart for the construction of the sludge storage tank is shown in figure 75.

Fig. 75 – Gantt chart for the construction of the Sludge Storage Tank

0 10 20 30 40 50 60

Setting out and excavationsConstruct formwork for foundations

Pour concreteAllow concrete curing

Construct tank support frameConstruct tank bottom plates

Construct tank wallsConstruct tank roof

Install pumpsInstall pipe

Install pipe valvesBuild cloakroom

Install toiletsConstruct cleaning station

Install lightingInstall level transmitter

Install pressure transmitterInstall local control panel

Install alarmsTesting

Site clearance

Day

94

14.7 Bhima River Crossing – Truss Bridge

Fig. 76 – Stage 1: Abutment construction

Fig. 77 – Stage 2: Truss construction

Fig. 78 – Stage 3: Deck Construction

Fig. 79 – Stage 4: Railing and pipe support construction

- Set out and excavate granite banks with an excavator - Construct formwork and false-work for concrete abutments - Pour concrete and allow curing

- Pre-construct truss bridge on land, ready to move over river - Using a telescopic crawler crane, push the finished structure out over to the other abutment

- Fix structure to support pin and roller joints - Install steel walkway grating

- Install railings - Install pipeline supports

95

Fig. 80 – Stage 5: Installation of pipe and testing of bridge

Fig. 81 – Gantt chart for the construction of the truss bridge

- Install pipeline - Install fencing and gate around bridge - Testing and commissioning

0 5 10 15 20 25 30 35 40 45

Setting outConstruct formwork and falsework for…

Pour concrete for abutmentsLet concrete cure

Construct Truss structure near riverMove truss structure into place

Install walkwaysInstall Railings

Install pipeline supportsInstall pipeline

Install fencing and gateClear site

Testing

Day

96

14.8 Arkavathi River Crossing – Cable Stayed Bridge

Fig. 82 – Stage 1: Setting out and tower foundation construction

Fig. 83 – Stage 2: Tower construction

Fig. 84 – Stage 3: Tower and bridge deck construction

- Set out and excavate granite banks with excavator - Construct formwork and false-work for concrete foundations - Pour concrete and allow curing

- Using temporary works construct sections of the tower with in-situ concrete - Make formwork for bottom section, pour concrete and allow to curing. Raise temporary works and formwork and construct next section of tower.

- While concrete tower is being constructed in sections from the bottom, the steel cables can be added from the bottom and the deck can be built out from the towers at either side of the river

97

Fig. 85 – Stage 4: Extend deck from towers, adding cables from the bottom up the tower

Fig. 86 – Stage 5: Add railings, walkway grating, pipe supports and pipeline

- Install pipeline - Install fencing and gate around bridge - Testing and commissioning

98

17

Fig. 87 – Gantt chart for the construction of the truss bridge 050

100150

200250

Setting outConstruct form

work and falsew

ork for concrete tower foundations

Construct formw

ork and falsework for concrete cable abutm

entsPour concrete for abutm

entsLet concrete cure

Construct bottom 10m

of concrete tower form

work for each tow

erPore concrete for 10m

of tower

Let concrete cureConstruct next 10m

of concrete tower form

work for each tow

erPore concrete for next 10m

of tower

Let concrete cureConstruct next 10m

of concrete tower form

work for each tow

erPore concrete for next 10m

of tower

Let concrete cureConstruct next 10m

of concrete tower form

work for each tow

erPore concrete for next 10m

of tower

Let concrete cureConstruct final 10m

of concrete tower form

work for each tow

erPore concrete for final 10m

of tower

Let concrete cureAdd bottom

cable to each tower

Construct deck from tow

er out to first cableAdd next 2 cables to each tow

erConstruct deck out further to 3rd cable

Add next cable to each tower

Construct deck out further to 4th cableAdd next 2 cables to each tow

erConstruct deck out further to 6th cable

Add final 2 cables to each tower

Complete the deck out to m

eet the deck constructed from the other side

Install walkw

aysInstall Railings

Install pipeline supportsInstall pipeline

Install fencing and gateClear site

Testing

Day

99

14.9 Over-ground Pipeline Crossing Fig. 88 – Stage 1: Setting out and excavation of earth for crossing Fig. 89 – Stage 2: Formwork and casting of concrete crossing Fig. 90 – Stage 3: Earthworks and construction of ramp

- Set out area for excavation - Using an excavator, excavate down to bedrock - Install trench walls for safety

- Construct formwork for concrete crossing - Cast concrete - Allow time for curing - Remove formwork and trench boxing

- Using earth from excavated soil from underground pipeline section, construct the ramp over the concrete crossing

100

Fig. 91 – Stage 4: Landscaping of surrounding area and testing

Fig. 92 – Gantt chart for the construction of the over-ground pipeline crossing

- Excess earth from underground pipeline excavation is used for landscaping around the crossing to naturally lead wildlife to crossing and not to the obstructing pipeline - Install pipeline through concrete crossing - Testing and commissioning

0 2 4 6 8 10 12 14

Setting out

Excavation of crossing area

Construct formwork and falsework forconcrete crossing block

Pour concrete

Let concrete cure

Earthworks - construct ramp

Landscape surrounding area

Day

101

14.10 Under-road tunnelling construction Fig. 93 – Stage 1: Excavation of entry and exit chambers Fig. 94 – Stage 2: Micro-tunnelling equipment installed Fig. 95 – Stage 3: Tunnel under road

- Excavation of entry chamber/ shaft (wide excavation) – {pipeline leads down to this} (Up to 7m in length) – longer than the receiving chamber - Excavation of receiving chamber (pipeline will lead up from this)

Install: - Thrust wall - Hydraulic Jacks - Shield (drilling head) - Lubricating system - Flushing system (slurry)

- Shield pushed through the ground by Hydraulic Jack - Hydraulic Jack fitted with a laser-guided system to remotely direct the shield through the soil – controlling speed and direction - Micro-tunnel Boring Machine (MTBM) excavates tunnel beneath road - Simultaneously the system installs the pipe casing, while spoil is removed

102

Fig. 96 – Stage 4: Pipe is installed through tunnel to other side of road Fig. 97 – Stage 5: Backfill chambers and clean site Fig. 98 – Gantt chart for the construction of the under-road tunnel

- Ductile iron pipe then placed inside the steel pipe casing, and pushed through by hydraulic jack as before.

- Shield is removed and excavations are back filled - Site clean up and testing

0 5 10 15 20 25 30 35 40 45 50

Setting out ExcavationExcavation of Working Shaft

Construct formwork and falsework for Thrust WallPour concrete for Thrust Wall

Let concrete cureInstallation of Hydraulic Jack

Installation of Tunnel Boring Machine (TMB)Installation of Slurry Machine

Tunneling + Installation of Pipe CasingInstallation of Ductile Iron Pipe

Removal of Slurry MachineRemoval of Tunnel Boring Machine

Removal of Hydraulic JackFill in exavation

Day

103

14.11 Service Reservoir construction

14.11.1 Stage 1 – Excavations and foundations Fig. 99 – Stage 1: Excavation and tank foundations

14.11.1.1 Excavations - The area to be excavated for the service reservoirs (80m x 325m), will be set out by 2 site engineers using a Robotic Theodolite. - 2 long thin areas to be excavated for: access roads/ Tower Crane foundation (7m x 375m) will also be set out by the site engineers. - The 1.95m of topsoil will then be removed by a team of machine-men operating JCB JS370 Excavators. - The ground will then be levelled by

x -This groundworks operation will be conducted at both ends of the planned excavation site in order to minimise the task time.

x The periphery of the foundations will be a 3:1 wide excavation to minimise risk.

- The excavators will load Liebherr TA230 Litronic Articulated Dump Trucks. These have a dump capacity of 19m3. - The excavation operation should be conducted in a manner that minimises waiting time for excavators and dumper trucks, to maximise efficiency. - It should be noted that the long thin excavations should be conducted first. This enables the long strip foundations for the access roads to be constructed early on in the project. This will subsequently minimise the dirt on the existing main road from construction machinery/ vehicles exiting the site.

14.11.1.2 Foundations -The remaining 5mm cover of top soil will be levelled with bulldozers - Dump trucks will deliver the layer 1 material to the excavation, which will subsequently be: levelled with the bulldozers, and compacted with vibratory rollers. - This process is repeated for layer 2 and 3. (However the sand-bitumen mix in layer 3 will not be compacted to the same degree as layers 1 and 2). - Formwork is then constructed around the outside of the section of concrete slab that is to be constructed. - Liebherr HTM 1504 Truck Mixers will deliver the wet mix of concrete into the formwork.

- Set out and excavate for tank foundations using excavators - Level and prepare surrounding ground - Construct tower crane rails on either side of the line of tanks and erect two tower cranes - Construct formwork - Pour concrete and allow curing

104

- The concrete is levelled-off by a gangs of foundation workers. - The presence of ‘Retarding Admixures’ slows the rate of curing to enable the concrete to set to the desired strength. - This process is then repeated for the entire foundation. - The Slabs will left for 28 days to cure before tank construction begins.

14.11.2 Stage 2 – Floor Slabs Fig. 100 – Stage 2: Construct tank floor slabs - A team of 3 Site Engineers will set out the layout of:

x The outer edge of the annular ring plates x The arrangement of the jointing between the bottom plates.

- The bottom plates will be lifted by a 78m Wilbert WT 2405L Tower Crane with a horizontal plate lifting clamp. - Once a course of steel plates are in position, a team of welders will weld the Steel Floor Plates and Annular Ring Plates together. - Note that if bottom plates are welded in the Monsoon Season, a tented cover will need to be constructed over the bottom plates so that the risks of welding in the rain are minimised.

14.11.3 Stage 3 – Tank Walls Fig. 101 – Stage 3: Construct tank walls - The Tank Bottom must be checked to be level - Site Engineer sets out the tank walls with erection nuts

105

- Construct Scaffolding around the outside and inside of the position of the proposed shell wall. This will be built up ahead of each course of the tank wall being constructed. - Wilbert WT 2405L Tower Crane lifts the first course of wall plates into position using a vertical plate clamp attachment - The foundations that were laid for the access road can now temporarily be used as a base for the tower crane rails – which will enable tower cranes to move up and down the site with ease. - Welders weld Tank Wall Plates together (from the inside and the outside), as the plates are lifted into position. - ‘Fit-up’ equipment is used to ensure the stability of the wall plates. - A ‘Tub Ring’ must be ‘shimmed up’ the tank walls after each course has been constructed to ensure the roundness of the tank. - The Stiffness Rings will be delivered in section and welded to the tank wall once the relevant tank course has been constructed - The final stage of wall construction will be the welding of the Top Corner Ring to the top of Course 4 of the tank wall. - This will be constructed in the same manner as the stiffening rings. - It is necessary for one steel wall plate on the first course to purposefully not be installed until the entire roof has been completed. This is so that the scissor lifts used for erecting the roof can exit the tank once the roof is completed. - The wall plates above this gap will be supported by a temporary jack.

14.11.4 Stage 4 – Tank Roof Fig. 102 – Stage 4: Construct tank roof and testing The roof comprises of 24 primary roof beams (spanning between the Top Corner Ring and the Centre Ring) supporting a series of secondary roof beams, upon which the Steel Roof Plates are fixed.

14.11.4.1 Primary Roof Beams - A temporary tower scaffold will be constructed at the centre of the tank. - The Centre Ring beam will be lifted on to the temporary tower by the tower crane. - The Primary roof beams will be lifted into position using the 78m Wilbert WT 2405L Tower Crane.

106

- Such a crane is required, as it must be able to: Lift the Primary Beams into position

Load (1 primary beam) = F.O.S. x Self Weight = 1.5 x (98.25kg/m * 24m) = 1.5 x 2360kg = 36 tonnes

Lift the Primary beams into position Distance from Crane to Primary Beam

= ∑ 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒(𝑓𝑟𝑜𝑚 𝐶𝑟𝑎𝑛𝑒 𝑡𝑜 𝑇𝑎𝑛𝑘) + 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑡𝑎𝑛𝑘 = 10m + 60m = 70m

- Therefore, a suitable crane is the 78m Wilbert WT 2405L Tower Crane, as it can lift a capacity of 36 tonnes at a radius of 71m. - The 2 opposite primary beams must be simultaneously lifted into position using the tower cranes so that there are balanced forces acting on the centre ring. This can be coordinated via by 2 signallers on the tower scaffolding via radio to the crane operators. - 2 teams of steel fixers will bolt the primary beam at either end, as it is being held in position by the crane. - Once all the primary beams have all been installed, the ribbed structure will be self-supporting. Therefore, at this point the tower scaffold can be disassembled and removed by the tower crane.

14.11.4.2 Secondary Roof Beams - The secondary roof beams for one tank can again be lifted into position by a single tower crane. - The secondary roof beams will be fixed to primary roof beams from the inside via bolting. The steel fixers conducting these works will conduct their works from a GS 5390 Self Propelled Scissor lift (which can elevate workers to a height of 18.15m) inside the tank. - The exterior Bolting will be conducted by steel fixers in harasses fixed to guide lines along the roof, moving along the primary and secondary beams.

14.11.4.3 Roof Plates - The roof plates will be lifted into position using one of the tower cranes with a horizontal plate lifting clamp. - The underside of roof plates will be fixed to the secondary beams, and fixed to one another via welding as the roof plates are held in position by the crane. Welders will conduct their works from the scissor lift inside the tank. - The exterior welding will be conducted by welders in harasses fixed to guide lines along the roof, moving along the primary and secondary beams. - The final segment of the roof will be a 3m diameter roof cap which will be fixed to the surrounding roof plates in the same manner.

107

Fig. 103 – Gantt chart for the construction of the service reservoir tank

0 100 200 300 400 500 600

Setting out for excavationExcavation (for all 4 tanks)

Prepare ground for concrete slab foundations (for all 4…Seting out for Foundations

Construct formwork and falsework for slab foundationsPour concrete for abutments

Let concrete cureSetting out for Tank Bottom

Construct Tank BottomSetting out for Tank Walls

Construct Tank WallsConstruct Tank Roof

Seting out for FoundationsConstruct formwork and falsework for slab foundations

Pour concrete for abutments

Day

108

15 Risk Assessment

Figure 104 is a graphical representation of the risks in the project and highlights the areas of the project that carry a greater risk. The risks can be divided into 8 categories detailed below

: Social risks – Risks that im

pact on social issues such as conflicts Econom

ic risks

– Risks

that incur

a financial loss and delay to the project Construction risks – H

ealth and safety risks during the construction process O

peration risks – Risks post construction, during the operation of the system

System

condition risks – Risks associated w

ith degradation of the system

Public safety risks – Risks to the general public’s health and safety Environm

ental risks – Risks associated w

ith weather and ground m

ovement

Other risks – Risks that fall outside of the

above categories

Fig. 104 – Summ

ary of risks in the project

Figure 104 shows that the m

ajority of risks are associated w

ith the construction, operation and lasting condition of the infrastructure – these areas w

ill require

the highest

levels of

risk m

anagement.

Appropriate mitigation m

ethods are in place to ensure no high level risks are present. The hazards and m

itigations are detailed in Appendix 27.

109

16. Capital Costs of Project 16.1 Pipeline Cost Table 32 – Capital Costs of Pipe Material

Nominal Diameter of Pipe

(m)

Total Mass (tons)

Installation Cost (M£)

Material Cost (M£)

Total Cost (M£)

1.2 78628.9 6.48 2.25 8.73 Density of Iron was taken as: 7100kg/m3

Table 33 – Capital Costs of Pump & Pipeline Item Quantities Cost (£) Pump Purchase NA 293,000 Pipeline Materials and Installation

NA 8,730,000

Concrete for overground supports

14000m3 1,092,000

Formwork for overground supports

79800m2 1,277,000

Pump housing building cost

1728 m2 836,000

Excavation of overground supports

10640 m3 21,000

Excavation of underground pipeline

127008 m3 254,000

Fill of underground pipeline

110018 m3 1,320,000

Disposal of Excavated Material

137648 m3 936,000

Site Clearance 600000 m2 3,000,000 Total (£) 17,759,000 Total (M£) 17.8 Operating Costs 9.13M/year

110

16.2 Water Treatment Plant Capital & Operational Costs Detailed costing calculations for all units in the water treatment plant can be found in the appendices. A summary table is included below consisting of construction and the first year of operation costs for each section of the water treatment. Table 14: Cost breakdown for the water treatment plant

Annual Costs of Water Treatment Plant

Associated Cost Cost (£) Clarification

M&E costs 370,000 Civil costs 1,286,000 Chemical Costs (including M&E costs)

520,000

Total costs 2,166,000 Filtration Stage 1 M&E costs 2,037,000 Civil costs 2,781,000 Total costs 4,819,000 Filtration Stage 2 M&E costs 1,006,000 Civil costs 1,521,000 Chemical costs (including M&E costs)

576,000

Total costs 3,104,000 Disinfection M&E costs 90,000 Civil costs 112,000 Chemical costs (including M&E costs)

612,000

Total costs 814,000 Thickening M&E costs 266,000 Civil costs 65,000 Chemical costs 142,000 Total costs 473,000 Dewatering M&E costs 444,000 Total costs 444,000

Overall TOTAL COST £11,828,000

111

16 3 Service Reservoir Cost Table 35: Capital Costs of Constructions to Service Reservoir

Access Road (access road/ tower crane foundations

Amount Units Price per unit (£)

Cost (£)

Excavation 9975 m3 2 19,950 Foundations - Imported material (foundation layers 1-3)

2100 m3 12 25,200

Foundations Formwork (access roads/ tower crane foundations)

5250 m2 16 84,000

Foundations - Concrete for Slab Foundations

5250 m3 78 409,500

TOTAL COSTS 538,650

Table 36: Capital Costs of 4 Service Reservoirs

4 Service Reservoir Tanks

Amount Units Price per unit

(£)

Cost (£)

Excavation 49400 m3 2 98,800 Foundations - Imported material (foundation layers 1-3)

10400 m3 12 124,800

Foundations Formwork (tanks) 22500 m2 16 360,000 Foundations - Concrete for Slabs Foundations

22500 m3 78 1,755,000

Steel Floor Plates 133.171953

tonnes 569 76,000

Steel Wall Plates 19.236425 tonnes 569 11,000 Steel Roof Plates 39.99 tonnes 569 23,000 Primary Beams 60.0525 tonnes 569 34,000 Secondary Beams 21.650111

6 tonnes 569 12,000

Total Cost of Service Reservoir 2,494,000 Total Cost of Acess Road £538,650 TOTAL CONSTRUCTION COSTS £3,032,650

112

16.4 Under-road Tunnelling Cost Table 37: Capital Costs of Micro-tunnelling

Micro-tunnelling

Amount Units Price per unit (£)

Cost (£)

Excavation 200 m3 2 400 Thrust Wall (reinforced concrete)

30 m2 72 2,160

Hire of Tunnel Boring Machine

2 days 10,000 20,000

Hire of Hydraulic Jack 2 days 3,000 6,000 Hire of Slurry Machine 2 days 2,000 4,000 Tunnel Boring Oprerator 1 days 300 300 TOTAL COST 32,860

16.5 Sludge Tank Cost Table 38 – Capital Costs of Sludge Tank

Sludge Tank Amount Units Price per unit

(£) Cost (£)

Excavation 616 m3 2 1,200 Foundations - Imported material (foundation layers 1-3)

130 m3 12 1,500

Foundations Formwork (tanks)

324 m2 16 5,200

Foundations - Concrete for Slabs Foundations

324 m3 78 25,000

Steel Floor Plates 15 tonnes 569 8,500 Steel Wall Plates 37 tonnes 569 21,000 Steel Roof Plates 18 tonnes 569 10,000 Primary Beams 20 tonnes 569 11,500 Secondary Beams 7 tonnes 569 4,000 Total Construction Cost 86,900

113

16.6 Truss Bridge Cost Table 39: Capital Costs of Truss Bridge

Truss bridge

Item Quantity Units Price per

unit Total Price

Steel Truss members 20 tonne £569.00 £11,500 Concrete Abutments 22 m3 £78.00 £1,800

Steel Walkway Grating 1.62 tonne £569.00 £900 Pipe Supports 0.06 tonne £569.00 £35

Railings 0.54 tonne £569.00 £300 Gates 0.05 tonne £569.00 £30

Telescopic crawler crane rental

1 days £2,000.00 £2,000

Concrete formwork 35 m2 £16.00 £560 TOTAL

COST £17,125

16.7 Over-ground Pipe Crossing Cost Table 40: Capital Costs of Over-Ground pipe crossing

Over-ground pipe crossing

Item Quantity Units Price per

unit Total Price

Concrete 65 m3 £78.00 £5,070 Concrete formwork 80 m2 £16.00 £1,280 Excavating material 32 m3 £2.00 £65

Fill with excavated material 190 m3 £0.05 £10 Landscaping with

underground pipeline excavation

485 m3 £0.05 £25

Additional landscaping 200 m2 £5.00 £1,000 TOTAL

COST PER CROSSING

£7,380

Number of

crossings 210

TOTAL COST

£1,549,800

114

16.8 Cable-stayed Bridge Cost Table 41: Capital Costs of Cable stayed bridge

Cable stayed bridge

Item Quantity Units Price per

unit Total Price

Concrete Abutments for deck 30 m3 £78.00 £2,500 Concrete formwork for abutments 35 m2 £16.00 £600

Concrete formwork for towers 700 m2 £16.00 £11,500 Concrete Towers 150 m3 £72.00 £10,800

Concrete abutments for cables 224 m3 £78.00 £17,500 Concrete formwork for cable

abutments 15 m3 £78.00 £1,200

Reinforcement for towers 2.5 tonne £600.00 £1,500 Cables 50 tonne £569.00 £28,500

Steel Beams in deck 80 tonne £569.00 £45,500 Steel walkway grating 15 tonne £569.00 £8,500

Pipe Supports 0.4 tonne £569.00 £250 Railings 5 tonne £569.00 £3,000

Gates 0.05 tonne £569.00 £30 Crane rental for 2 cranes 200 days £2,000.00 £400,000

TOTAL COST

£550,000

16.9 Sludge Removal Table 42: Operational Operation of Removal to Landfill

Removal to Landfill

Removed (m3)= 1653 ` Total(£)= 11,240

115

16.10Total Project Costing The table presents the client our expected Capital Costs for the entire project. These costs are to be assume to be accurate to +/-30% Table 43 – Total capital costs

TOTAL CAPTIAL COSTS OF PROJECT Project Cost (£Million) Pump & Pipeline 17.8 Water Treatment Plant 11.8 4 Service Reservoirs 3.0 Microtunneling 0.03 Sludge Tank 0.09 Truss Bridge 0.02 Over-Ground pipe crossing 1.5 Cable stayed bridge 0.55 LABOUR COSTS (Multiply by 3) TOTAL CAPITAL COSTS 104.7 The table below show operation costs for one year, these costs are assume to be accurate to +/- 30% Table 44 – Operation costs

TOTAL OPERTIONAL COSTS OF PROJECT

Project Cost (£Million)

Electrical Cost 9.13

Chemical Cost 1.84 Removal to Landfill 0.01 TOTAL OPERATIONAL COSTS 10.98

16.11 Life-time and decommissioning costs If adequately maintained the water treatment system will have a design life of approximately 60 years. The decommissioning costs and process must be considered – in an effort to act more sustainably, elements of the infrastructure can be designed to be recycled and have other uses after their lifetime in the water system.

116

Appendices

117

Table of Contents for Appendices 17. Water Treatment Plant......................................................................................... 121 17.1 Mass balance ........................................................................................................................................ 121

17.1.1 Assumptions made ............................................................................................................................ 121 17.1.2 Mass balance tables ......................................................................................................................... 123

17.2 Clarification .......................................................................................................................................... 125 17.2.1 Assumptions made: .......................................................................................................................... 125 17.2.2 Clarifier cost analysis ...................................................................................................................... 125 17.2.3 Sizing and costing calculations: ................................................................................................. 126

17.3 Filtration................................................................................................................................................ 130 17.3.1 Optimal number of filters cost analysis .................................................................................. 130 17.3.2 Sizing and costing calculations .................................................................................................. 131

17.4 Disinfection .......................................................................................................................................... 132 17.4.1 Assumptions made: .......................................................................................................................... 132 17.4.2 Sizing and costing calculations .................................................................................................. 132

17.5 Waste treatment-general ............................................................................................................... 134 17.5.1 Assumptions made ............................................................................................................................ 134

17.6 Waste treatment-Thickening ........................................................................................................ 135 17.6.1 Assumptions made: .......................................................................................................................... 135 17.6.2 Sizing and costing calculations .................................................................................................. 135 17.6.3 Operation in non-ideal conditions............................................................................................. 139

17.7 Waste treatment-Dewatering ....................................................................................................... 139 17.7.1 Assumptions made: .......................................................................................................................... 139 17.7.2 Sizing and costing calculations .................................................................................................. 140 17.7.3 Operation in non-ideal conditions............................................................................................. 142

17.8 Plant Layout ......................................................................................................................................... 143

18. Sludge Storage and Management ...................................................................... 144 18.1 Silo Capacity ......................................................................................................................................... 144 18.2 Sludge Pump ........................................................................................................................................ 144 18.3 Overflow ................................................................................................................................................ 145 18.4 Construction ........................................................................................................................................ 145 18.5 Waste Management of Sludge ...................................................................................................... 145 18.6 Amenities .............................................................................................................................................. 145 18.7 Sludge Tank Structure Design ...................................................................................................... 146

18.7.1 Wall Thickness .................................................................................................................................... 146 18.7.2 Stiffening Ring Design ..................................................................................................................... 147 18.7.2 Roof Design .......................................................................................................................................... 149 18.7.3 Bottom plate thickness ................................................................................................................... 149

19. Water Conveyance .................................................................................................. 151 19.1 Water Demand .................................................................................................................................... 151 19.2 System Characteristics .................................................................................................................... 152

19.2.1 Pipe Characteristic Curve .............................................................................................................. 152 19.2.2 Pump Characteristic Curves ......................................................................................................... 157 19.2.3 System Characteristic Curves ...................................................................................................... 157

19.3 Economic Comparison ..................................................................................................................... 160 19.3.1 Capital Cost of Pipe Material ....................................................................................................... 160 19.3.2 Annual Pump Operating Costs .................................................................................................... 161 19.3.3 Capital Cost of Pumps ..................................................................................................................... 162 19.3.4 Discussion ............................................................................................................................................. 162

19.4 Pump Locations .................................................................................................................................. 164

118

19.5 Pump Station Design ........................................................................................................................ 165 19.5.1 Dimensions ........................................................................................................................................... 166 19.5.2 Pump Station Layout ....................................................................................................................... 167

19.6 Intake Pump ......................................................................................................................................... 168 19.6.1 Suction Piping ..................................................................................................................................... 168 19.6.2 Suction Pipe ......................................................................................................................................... 169 19.6.3 Intake Pump ........................................................................................................................................ 169 19.6.4 Suction Bell Depth ............................................................................................................................ 170

19.7 Pump Efficiency Curve .................................................................................................................... 172 19.8 Energy Demand and Supply .......................................................................................................... 173 19.9 Priming .................................................................................................................................................. 174 19.10 Pump Design ..................................................................................................................................... 174

Pump Specifications ..................................................................................................... 174 19.11 Control Technology ........................................................................................................................ 178 19.12 Over-ground Pipe Dimension Design ..................................................................................... 179

19.12.1 Initial Calculation of Saddle Width ........................................................................................ 179 19.12.2 Pressure Class due to Localised Stress at Supports ........................................................ 180 19.12.3 Pressure Class due to Hoop Stress Due to Internal Pressure ...................................... 181 19.12.4 Pressure Class due to Flexural Stress at Centre of Span ............................................... 181 19.12.5 Deflection at Midspan .................................................................................................................. 182 19.12.6 Recalculated Saddle Width ........................................................................................................ 182 19.12.7 Conclusion .......................................................................................................................................... 182

19.13 Underground Pipe Dimension Design .................................................................................... 183 19.14 Valves ................................................................................................................................................... 183

19.14.1 Wash Out Valves ............................................................................................................................. 183 19.14.2 Air Valves............................................................................................................................................ 183 19.14.3 Stop Valves......................................................................................................................................... 184 19.14.4 Surge Protection by Limiting Valve Closure ...................................................................... 184

19.15 Pipe Material and Encasement .................................................................................................. 185 19.15.1 Pipe Material .................................................................................................................................... 185 19.15.2 Pipe Encasement ............................................................................................................................. 185 19.15.3 Pipe Lining ......................................................................................................................................... 186

20. Over-ground Pipeline Crossing ......................................................................... 187

21. Bridge loading ......................................................................................................... 188 21.1 Pipe self-weight .................................................................................................................................. 188 21.2 Water loading ...................................................................................................................................... 188 21.3 Bridge deck self-weight ................................................................................................................... 188 21.4 Railing self-weight ............................................................................................................................. 189 21.5 Wind loading ....................................................................................................................................... 189 21.6 Other loading ....................................................................................................................................... 189 21.7 Total distributed loading ................................................................................................................ 190

22. Bhima River Crossing – Truss Bridge Design ............................................... 191

23. Arkavathi River Crossing – Cable-Stayed Bridge Design .......................... 194 23.1 Initial Design Proposal .................................................................................................................... 194 23.2 Bridge loading ..................................................................................................................................... 194 23.3 Bridge form .......................................................................................................................................... 195 23.4 Reactions in members ..................................................................................................................... 195 23.5 Size of steel cables ............................................................................................................................. 195 23.6 Size of Bridge Deck ............................................................................................................................ 196 23.7 Size of Tower ....................................................................................................................................... 197

119

24. Under-road Pipeline Tunnelling ....................................................................... 198 24.0.1 Soil Testing ....................................................................................................................................... 199 24.0.2 Set-up: ................................................................................................................................................. 199 24.1 Additional Checks: ............................................................................................................................. 199

24.1.1 Surface Checks .................................................................................................................................... 199 24.1.2 Shield and Jacking load checks ................................................................................................... 200 24.1.3 Manufacturer ...................................................................................................................................... 200 24.1.4 Micro-tunnelling Subcontractor ................................................................................................ 200

24.2 Working Shaft: .................................................................................................................................... 200 24.3 Thrust Wall ........................................................................................................................................... 200 24.4 Hydraulic Jack: .................................................................................................................................... 200 24.5 Shield (Tunnel Machine) Selection............................................................................................. 201

24.5.1 Tunnel Boring Machine (TBM) ................................................................................................... 201 24.6 Slurry Machine .................................................................................................................................... 201 24.7 Pipes ........................................................................................................................................................ 202

24.7.1 Pipe Casing ........................................................................................................................................... 202 24.7.2 Internal Ductile Iron Water Pipe ............................................................................................... 202

24.7.3 Support facilities required on site: ......................................................................................... 202

25. Service Reservoir Design ..................................................................................... 204 25.1 To determine the Service Reservoir Capacity ....................................................................... 204 25.2 To determine the Service Reservoir Tank Dimensions ..................................................... 204 25.3 Designing the Tank Structure ....................................................................................................... 205

25.3.1 Determining the wall thickness of the tank .......................................................................... 205 25.3.2 Shell Plate Arrangement ................................................................................................................ 207 25.3.3 Stiffening Ring Design ..................................................................................................................... 208 25.4.4.3 Roof ...................................................................................................................................................... 210 25.4.4.4 Roof Plates ........................................................................................................................................ 211 25.4.4.5 Secondary Roof Beams (Purlins) ............................................................................................ 213 25.4.4.6 Primary Roof Beams (Ribs) ...................................................................................................... 216

25.4 Access (For Maintenance) .............................................................................................................. 220 25.4.1 Access to the Top Corner Ring..................................................................................................... 220 25.4.2 Top Corner Ring ................................................................................................................................. 220 25.4.3 Roof Opening ....................................................................................................................................... 220

25.5 Foundations ......................................................................................................................................... 220 25.5.1 Location ................................................................................................................................................. 220 25.5.2 Requirements ...................................................................................................................................... 220 25.5.3 Design ..................................................................................................................................................... 221 25.5.4 Excavation of Soil around foundations ................................................................................... 222 25.5.5 Drainage System ................................................................................................................................ 222 25.5.6 Tolerances: ........................................................................................................................................... 222

25.6 Tank Bottom ........................................................................................................................................ 222 25.6.1 Foundations Support ....................................................................................................................... 223 25.6.2 Tank Bottom ........................................................................................................................................ 223

25.7 Steel Bottom Plates ........................................................................................................................... 223 25.7.1 Plate Arrangement ........................................................................................................................... 223 25.7.2 Plate Connections .............................................................................................................................. 223 25.7.3 Thickness: ............................................................................................................................................. 223 25.7.4 Plate Overlap ....................................................................................................................................... 224

25.8 Ring of Annular Plates ..................................................................................................................... 224 25.8.1 Requirement ........................................................................................................................................ 224 25.8.2 Sizing....................................................................................................................................................... 224 25.8.3 Arrangement ....................................................................................................................................... 224 25.8.4 Thickness of Annular plates ......................................................................................................... 224

120

25.8.5 Connection (Annular Plate – Annular Plate) ....................................................................... 225 25.8.6 Connection (Annular Plate – Tank Wall Plate) ................................................................... 225 25.8.7 Connection (Bottom Plates - Annular Plates) ...................................................................... 225

25.9 Inlet and Outlet design .................................................................................................................... 225 25.9.1 Inlet .......................................................................................................................................................... 225 25.9.2 Outlet ...................................................................................................................................................... 226 25.9.3 Connections .......................................................................................................................................... 226

25.10 Ventilation ......................................................................................................................................... 227 25.11 Overflow ............................................................................................................................................. 227 25.12 Baffles .................................................................................................................................................. 227 25.13 Access ................................................................................................................................................... 230 25.14 Stairways ............................................................................................................................................ 231 25.15 Amenities............................................................................................................................................ 231

26. Lighting ...................................................................................................................... 232 26.1 Lighting layouts for each room .................................................................................................... 232 26.2 Lighting results for each room ..................................................................................................... 233

27. Risk Assessment...................................................................................................... 236 27.1 Social Risk Assessment ................................................................................................................... 236 27.2 Economic Risk Assessment ........................................................................................................... 237 27.3 Construction Risk Assessment ..................................................................................................... 238 27.4 Operation Risk Assessment ........................................................................................................... 240 27.5 System Condition Risk Assessment ........................................................................................... 244 27.6 Public Risk Assessment ................................................................................................................... 246 27.7 Environmental Risk Assessment ................................................................................................. 248 27.8 Other Risk Assessment .................................................................................................................... 249

References ........................................................................................................................ 250

Academic Appendix ...................................................................................................... 257

121

17. Water Treatment Plant 17.1 Mass balance

17.1.1 Assumptions made 1. The mass of the solids at the beginning of the process was the total sludge

solids(calculated from the equation provided in the process briefs) minus the mass of the metal in the coagulant solution added and the 5% dry solids not removed by the filter press

2. 0.15% extra water than that supplied to Sandalwood at the end of the process will be present in the raw water flowrate

3. The dry solids term was assumed to apply to just the sludge solids present and not the polyelectrolyte or the lime added to the water

4. The sludge stream from the floc blanket clarifier (FBC) (stream 30) was approximately 3% of the throughput (the mass going through the FBC). This was stated in the process briefs document provided

5. The FBC sludge stream contained approximately 1.36% dry solids as opposed to the rough 0.5% figure given in the brief. This assumption was required for the mass balance to work

6. The dose required for polyelectrolyte in the FBC was 0.25 mg/l 7. The sludge stream of each of the Rapid Gravity Filters (RGFs) (streams 31 and 32

respectively) were approximately 2% of their throughput (also stated in the process briefs provided)

8. The backwash streams for the RGFs (streams 12, 13, 20 and 21) only contained the water present in their respective sludge streams. The solids and other chemicals were held up in the RGFs

9. The sludge streams of each of the RGFs contained 0.01% dry solids (also stated in the process brief provided)

10. The sulphuric acid added was of 98% concentration and a dose of 3 mg/l required (as discussed with supervisors). The water added was assumed to be negligible in the mass balance calculations

11. The lime dose for each process it was required for was 30 mg/l (stated in the process costings document provided). The water added to the lime was not considered in solving the mass balance

12. The lime added at each stage except for the final addition in stream 28 prior to the water being sent to sandalwood will leave the process in the sludge stream leaving the filter press

13. The Polyelectrolyte dose for the thickener was 5 kg/tonne of dry solids 14. All the polyelectrolyte added to the plant leaves the plant in the sludge stream

from the filter press which is sent to landfill 15. The Alum solution was 4% metal and the remaining 96% water 16. The water added to the liquefied chlorine gas was not considered in solving the

mass balance (as discussed with supervisors)

122

17. The Chlorine dose required for 1 mg/l for manganese removal in the second RGF and 2 mg/l for chlorination

18. The supernatant stream(recycle stream from the thickener, stream 39) could be no more than 10% of the raw water flowrate

19. The filter presses will remove 95% of the dry solids with the remaining 5% recycled back through the process.

20. The sludge stream leaving the thickener(stream 39) will contain 5% dry solids 21. The sludge stream leaving the filter press (stream 40) will contain 20% dry

solids

123

17.1.2 Mass balance tables

Table 45: Mass balance

Stream

Component

1 2

3 4

5 6

7 8

Flowrate in

kg/day

Solids 50171.29

52852.67 52852.67

0.00 53627.60

0.00 53627.60

0.00 Coagulant

0.00 0.00

0.00 774.93

0.00 0.00

0.00 0.00

Lime

0.00 0.00

0.00 0.00

0.00 3894.60

3894.60 0.00

Polymer

0.00 0.00

0.00 0.00

0.00 0.00

0.00 30.28

Chlorine 0.00

0.00 0.00

0.00 0.00

0.00 0.00

0.00 Sulphuric acid

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Water

121137200.84 121952310.12

129767451.03 18598.32

129786049.35 0.00

129786049.35 0.00

Total 121187372.13

122005162.79 129820303.70

19373.25 129839676.95

3894.60 129843571.55

30.28

Component

9 10

11 12

13 14

15 16

Flowrate in

kg/day

Solids 53627.60

499.04 246.98

0.00 0.00

246.98 0.00

246.98 Coagulant

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Lime

3894.60 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Polymer

30.28 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Chlorine 0.00

0.00 0.00

0.00 0.00

0.00 120.93

120.93 Sulphuric acid

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Water

129786049.35 125946179.75

125946179.75 2520319.69

2520319.69 123425860.05

0.00 123425860.05

Total 129843601.83

125946678.78 125946426.73

2520319.69 2520319.69

123426107.03 120.93

123426227.96

Component

17 18

19 20

21 22

23 24

Flowrate in

kg/day

Solids 0.00

246.98 0.00

0.00 0.00

0.00 0.00

0.00 Coagulant

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Lime

3702.08 3702.08

0.00 0.00

0.00 0.00

0.00 0.00

124

Polymer

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Chlorine 0.00

120.93 0.00

0.00 0.00

0.00 241.92

241.92 Sulphuric acid

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Water

0.00 123425860.05

123425860.05 2465860.04

2465860.04 120960000.01

0.00 120960000.01

Total 3702.08

123429930.04 123425860.05

2465860.04 2465860.04

120960000.01 241.92

120960241.93

Component

25 26

27 28

29 30

31 32

Flowrate in

kg/day

Solids 0.00

0.00 0.00

0.00 0.00

53128.56 252.06

246.98 Coagulant

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Lime

0.00 0.00

0.00 3628.80

3628.80 3894.60

0.00 3702.08

Polymer

0.00 0.00

0.00 0.00

0.00 30.28

0.00 0.00

Chlorine 0.00

241.92 241.92

0.00 241.92

0.00 0.00

120.93 Sulphuric acid

362.88 362.88

362.88 0.00

362.88 0.00

0.00 0.00

Water

0.00 120960000.01

120960000.01 0.00

120960000.01 3839869.60

2520319.69 2465860.04

Total 362.88

120960604.81 120960604.81

3628.80 120964233.61

3896923.05 2520571.75

2469930.03

Component

33 34

35 36

37 38

39 40

Flowrate in

kg/day

Solids 53627.60

0.00 53627.60

53627.60 53627.60

50946.22 0.00

2681.38 Coagulant

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Lime

7596.68 0.00

7596.68 7596.68

7596.68 7596.68

0.00 0.00

Polymer

30.28 268.14

298.42 298.42

298.42 298.42

0.00 0.00

Chlorine 120.93

0.00 120.93

120.93 120.93

120.93 0.00

0.00 Sulphuric acid

0.00 0.00

0.00 0.00

0.00 0.00

0.00 0.00

Water

8826049.33 0.00

8826049.33 1010908.42

1010908.42 195799.14

7815140.91 815109.28

Total 8887424.83

268.14 8887692.97

1072552.06 1072552.06

254761.40 7815140.91

817790.66

125

17.2 Clarification

17.2.1 Assumptions made: (i) Algae is not present in any sufficient quantities. In the three years of

water quality data that was provided by the client there was no data on algae concentrations in the water which would imply algae does not pose any issues. Additionally, algae growth is usually prone to areas which offer sufficient nutrients such as nitrogen and phosphorous (EPA, 2014), and even though there is a reasonably small agriculturally dependant village in the surrounding area which may result in the addition of nitrogen and phosphorous (typical fertilizer components), the impact of such a small operation would be expected to have a very minor impact, if any at all, on the algae concentrations present in the reservoir. In the event that the client needs algal treatment the first preference would be to use reservoir management techniques, or ensuring that the water withdrawn from the reservoir at levels where algae are present in low numbers (Binnie and Kimber, 2013).

(ii) The floc particles produced will be suited better to sedimentation as opposed to flotation due to their density in comparison to that of water. This assumption follows on from the assumption that algae is not present in sufficient quantities, since high concentrations of algae usually result in lighter flocs which are better removed by flotation, such as dissolved air flotation, since the settling times required are too large. In practice, the density of the floc particles would be tested to allow for a more accurate design choice to be made.

(iii) The clarifier selected will be able to process the highest turbidity waters expected (200 NTU). Floc blanket clarifiers are able to process water of extremely high turbidity (500 NTU) when the appropriate modifications are made to the system, such as installing a sludge scraper at the base of the tank to ensure efficient removal of the greater sludge loads(Crittenden et al., 2012).

(iv) During periods of high turbidity it is expected that the clarification system will help ensure that sufficient turbidity reduction is achieved as explained above, though in the event that the turbidity of the clarified water is higher than normal an additional rapid sand filters and frequent backwashing will allow for sufficient turbidity removal to be achieved. In practice, it would be beneficial to test the technical viability of the proposed clarification/filtration setup by constructing a pilot plant, as this would give a realistic idea of the performance that could be expected during the monsoon season when there is a significant increase in the water turbidity.

17.2.2 Clarifier cost analysis The client has requested that 1 spare floc blanket clarifier be available at any time. Since this will replace the clarifier that is being taken offline, it must be of

126

the same capacity in order to maintain a steady throughput for each of the clarifiers. The installed area was found by adding the operating area to the spare FBC area, e.g. if only 1 FBC was provided plus the spare FBC requested by the client, then the total installed area would be double the required operating area. For fully worked calculation of the FBC cost analysis please refer to the following sizing and costing calculations. An illustration of the incremental cost incurred by installing different numbers of floc blanket clarifiers is given below: Fig.105: Clarifier Cost Analysis

17.2.3 Sizing and costing calculations: Floc Blanket clarifier:

Knowing the volume of chemical to be stored it was possible to determine the diameter and height of each:

𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑣𝑒𝑠𝑠𝑒𝑙 =𝜋𝑑2

4× ℎ𝑒𝑖𝑔ℎ𝑡

Taking an Height/Diameter ration of 2.5:

𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑣𝑒𝑠𝑠𝑒𝑙 =2.5𝜋𝑑3

4

2

3

45 6

78

910

5

1640

1660

1680

1700

1720

1740

1760

1780

1800

2 3 4 5 6 7 8 9 10

Incr

emen

tal c

ost (

£000

s)

No. of Operational Clarifiers

Clarifier Cost Analysis

127

Rearranging for d:

𝑑 = (4 × 𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑣𝑒𝑠𝑠𝑒𝑙

2.5 × 𝜋)

13

For example, the alum storage tank required a volume of 120 m3 and so:

𝑑 = (4 × 1202.5 × 𝜋

)13

= 3.94 𝑚

Knowing the diameter and the height/diameter ratio:

ℎ = 2.5𝑑 = 2.5 × 3.94 𝑚 = 9.85 𝑚

Rounding these dimensions to standard sizes gives: d = 4 m & h = 10 m.

Knowing the total hourly throughput to the clarification system, and the surface loading rates specified in the process briefs document, the total surface area required was found:

𝑇𝑜𝑡𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 =𝑇𝑜𝑡𝑎𝑙 ℎ𝑜𝑢𝑟𝑙𝑦 𝑓𝑙𝑜𝑤

𝐻𝑜𝑢𝑟𝑙𝑦 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑙𝑜𝑎𝑑𝑖𝑛𝑔 𝑟𝑎𝑡𝑒

𝑇𝑜𝑡𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 =5400 𝑚3

ℎ

6 𝑚3

𝑚2ℎ

= 900 𝑚2

𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑝𝑒𝑟 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟 =𝑇𝑜𝑡𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑𝑁𝑜. 𝑜𝑓 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟𝑠

𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 𝑝𝑒𝑟 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟 =900 𝑚2

5 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟𝑠= 180 𝑚2

The diameter of each clarifier was found simply by:

𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎 =𝜋𝑑2

4

Rearranging for d:

𝑑 = (4 × 𝑆𝐴

𝜋)

12

= (4 × 180

𝜋)

12

= 15.1 𝑚

The clarifiers were sized as cylinders.

With a height of 6 m and diameter of 15.1 m, the volume of each clarifier was determined:

128

𝑉𝑜𝑙𝑢𝑚𝑒 = 𝑆𝐴 × ℎ𝑒𝑖𝑔ℎ𝑡

𝑉𝑜𝑙𝑢𝑚𝑒 = 180 𝑚2 × 6 𝑚 = 1080 𝑚3

𝐷𝑒𝑡𝑒𝑛𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 =𝐶𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒

𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝑟𝑎𝑡𝑒 𝑝𝑒𝑟 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟=

𝐶𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒𝑇𝑜𝑡𝑎𝑙 𝑖𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝑟𝑎𝑡𝑒

𝑁𝑜. 𝑜𝑓 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟𝑠

The influent rate was obtained from the mass balance (see mass balance section of appendicies).

𝐷𝑒𝑡𝑒𝑛𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 =1080 𝑚3

(54005 ) 𝑚3

ℎ

= 1 ℎ𝑜𝑢𝑟

Weir overflow rate was calculated as:

𝑊𝑒𝑖𝑟 𝑜𝑣𝑒𝑟𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 =𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝑓𝑙𝑜𝑤 𝑝𝑒𝑟 𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟

𝑊𝑒𝑖𝑟 𝑙𝑒𝑛𝑔𝑡ℎ

Weir width of 0.5 m was assumed and thus the weir length was calculated as:

𝑊𝑒𝑖𝑟 𝑙𝑒𝑛𝑔𝑡ℎ = 𝜋 × (𝑐𝑙𝑎𝑟𝑖𝑓𝑖𝑒𝑟 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 − 2 × 0.5 𝑚)

𝑊𝑒𝑖𝑟 𝑙𝑒𝑛𝑔𝑡ℎ = 𝜋 × (15.1 − 1) = 44.3 𝑚

And so the weir overflow rate was found:

𝑊𝑒𝑖𝑟 𝑜𝑣𝑒𝑟𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 =1080 𝑚3

ℎ44.3 𝑚

= 24.37𝑚3ℎ

The costing formula provided for civil and M&E costs are given below:

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡𝑠 (£000𝑠) = 1023 × 𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝑎𝑟𝑒𝑎0.6442 × 𝑁𝑜. 𝑜𝑓 𝐹𝐵𝐶′𝑠0.1

𝑀&𝐸 𝑐𝑜𝑠𝑡𝑠 (£000𝑠) = 246.4 × 𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝑎𝑟𝑒𝑎0.6341 × 𝑁𝑜. 𝑜𝑓 𝐹𝐵𝐶′𝑠0.1

Where the installed area is given in terms of 1,000 m2.

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡𝑠 = £1285944.85

𝑀&𝐸 𝑐𝑜𝑠𝑡𝑠 = £370224.33

Coagulant dose and costing for FBC:

𝐶𝑜𝑎𝑔𝑢𝑙𝑎𝑛𝑡 𝑑𝑜𝑠𝑒 (𝑚𝑔 𝐶/𝑙) = 𝐴𝑊 ∗ (𝑎 + 𝑏 ∗ 𝑐𝑜𝑙𝑜𝑢𝑟 + 𝑐 ∗ 𝑡𝑢𝑟𝑏𝑖𝑑𝑖𝑡𝑦),

Where

• C is the coagulant metal ion (either iron Fe3+, or aluminium Al3+)

• AW is the atomic weight of the coagulant ion (Fe3+ = 56; Al3+ = 27)

129

• a is a constant = 0.0545

• b is a constant = 0.000885

• c is a constant – 0.000740

• Colour is the raw water colour as oHazen (PtCo)

• Turbidity is the raw water turbidity as NTU

So for Alum Sulphate, at the maximum turbidity (200 NTU) and the corresponding colour (21 PtCo), the required coagulant dose could be determined as follows:

Coagulant dose (mgCl) = 27 ∗ (0.0545 + 0.000885 ∗ 21 + 0.000740 ∗ 200)

Coagulant dose (mgCl) = 5.969295 mg/l

Coagulant dose (mgCl) = 5.97 mg/l

For Aluminium sulphate

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 145.88 ∗ 𝐶𝑎𝑝0.3868

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £88/𝑡𝑜𝑛𝑛𝑒 𝑎𝑠 𝐴𝑙3+

At maximum turbidity and corresponding colour, coagulant dose = 5.97 mg/l = 5.97 mg/kg of water

Cap = Installed Al capacity in 000 kg/day = Coagulant dose x Water flowrate entering FBC (obtained from mass balance)

Cap = 5.97 x 129820333.1 = 774935865 mg/day =774.94 kg/day

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 145.88 ∗ (774.941000

)0.3868

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 132.1790054

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £132179.01

Again assuming costs in terms of a year

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £88 × (774.94 × 365)/1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £24890.75

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = 𝑀&𝐸 𝑐𝑜𝑠𝑡 + 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £132179.01 + £24890.75

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £157069.76

130

Lime:

The lime costing for ph adjust just before FBC was calculated in the same manner as for just after the chlorination as shown in said section:

Polyelectrolyte for FBC:

Assume a dose of 0.25 mg/l

So mass of polyelectrolyte required = Polyelectrolyte dose x water flowrate to the clarifier

Mass of polyelectrolyte = (0.25/10^6) kg/l x 121137200.8 l/day = 30.28 kg/day

Costing was done in the same manner as for the polyelectrolyte used in the thickener detailed below.

17.3 Filtration 17.3.1 Optimal number of filters cost analysis Filtration Stage 1

The installed area was found in the same manner as for the clarification system.

An illustration of the total cost (M&E plus Civil costs) incurred by installing different numbers of RGF’s is given below:

Figure. 106: Cost analysis plot for varying number of operational filters, stage 1

2

3

45

6 7 8 9 10 11 12 13 14 15

4500

5000

5500

6000

6500

7000

1 3 5 7 9 11 13 15

Incr

emen

tal C

ost I

ncre

ase

(£00

0s)

No. of Operational Units

Rapid Gravity Filtration Stage 1 Cost Analysis

131

An illustration of the total cost (M&E plus Civil costs) incurred by installing different numbers of RGF’s is given below in Figure 107.

Fig. 107: Cost analysis plot for varying number of operational filters, stage 2.

17.3.2 Sizing and costing calculations The costing formula provided for civil and M&E costs are given below:

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡𝑠 (£000𝑠) = 32.808 × 𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝑎𝑟𝑒𝑎0.6021 × 𝑁𝑜. 𝑜𝑓 𝑅𝐺𝐹′𝑠0.1

𝑀&𝐸 𝑐𝑜𝑠𝑡𝑠 (£000𝑠) = 9.2869 × 𝐼𝑛𝑠𝑡𝑎𝑙𝑙𝑒𝑑 𝑎𝑟𝑒𝑎0.704 × 𝑁𝑜. 𝑜𝑓 𝑅𝐺𝐹′𝑠0.2

Auxiliary Chlorination for Filtration stage 2:

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 174.35 ∗ 𝐶𝑎𝑝0.3126

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £160/𝑡𝑜𝑛𝑛𝑒 (𝑔𝑎𝑠)

Chlorine dose required = 1 mg/l = 1 mg/kg of water

Flowrate entering rapid sand filter 2 (obtained from mass balance) = 120932909.2 kg/day

Cap = Installed CI2 capacity in 000 kg/day = Chlorine dose required x water flowrate entering rapid sand filter 2

Cap = 1 x 120932909.2 = 120932909.2 mg/day = 120.93 kg/day

1

2

3

45 6 7 8 9 10 11 12 13 14 15

2400

2600

2800

3000

3200

3400

3600

3800

4000

1 3 5 7 9 11 13 15

Incr

emen

tal C

ost I

ncre

ase

(£00

0s)

No. of Operational Units

Rapid Gravity Filtration Stage 2 Cost Analysis

132

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 174.35 ∗ (120.931000

)0.3126

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 90.0856822

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £90085.68

Assume costs in terms of year, so cap for chemical cost = 120.93 x 365

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £160 ∗120.93 × 365

1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £7062.31

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = 𝑀&𝐸 𝑐𝑜𝑠𝑡 + 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £90085.68 + £7062.31

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £97147.99

Lime:

The lime costing for ph adjust just before FBC was calculated in the same manner as for just after the chlorination as shown in said section:

17.4 Disinfection 17.4.1 Assumptions made:

(i) A disinfection residual of 1 mg/l of chlorine must be provided at the end of the disinfection stage

(ii) All harmful pathogens will be killed by the disinfection method chosen

(iii) Chlorination by sodium hypochlorite and chlorine dioxide could not be costed or sized due to the required information not being available

(iv) UV was not required to be sized at this stage due to the ability to calculate the costs from the UV throughput which was known

(v) Protozoa will not be present in the water treated 17.4.2 Sizing and costing calculations Chlorination:

For the Chlorine supply and storage

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 174.35 ∗ 𝐶𝑎𝑝0.3126

Chlorine dose required = 2 mg/l = 2 kg/ML

Water flowrate at disinfection stage = 1.4 m3/s = 120.96 ML/day

Cap = Installed CI2 capacity in 000 kg/day = Chlorine dose required x water flowrate at disinfection stage

Cap = 2 x 120.96 = 241.92 kg/day

133

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 174.35 ∗ (241.921000

)0.3126

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 111.881363

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £111881.36

For the contact tank:

Civil cost (£000s) = 176.56 ∗ Vol0.5402

Contact time = 30 minutes (given in the process briefs)

Max flowrate = Water flowrate at disinfection stage = 1.4 m3/s = 84 m3/minute

𝐶𝑇 𝑣𝑜𝑙𝑢𝑚𝑒 = 𝑀𝑎𝑥 𝑓𝑙𝑜𝑤𝑟𝑎𝑡𝑒 × 𝑐𝑜𝑛𝑡𝑎𝑐𝑡 𝑡𝑖𝑚𝑒

𝐶𝑇 𝑣𝑜𝑙𝑢𝑚𝑒 = 84 × 30

𝐶𝑇 𝑣𝑜𝑙𝑢𝑚𝑒 = 2520 𝑚3

Taking oversize into account CT volume = 2520 x 1.5 = 2898 m3

Vol = CT volume in 000 m3 = 2.898

Civil cost (£000s) = 176.56 ∗ 2.8980.5402

Civil cost (£000s) = 313.702418

Civil cost = £313702.42

For sizing the chlorination contact tank, it was assumed the tank was a cube, thus length= width = height = √𝑣𝑜𝑙3 = √28983 = 14.3 𝑚

For the chemicals:

Chlorine: 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £160/𝑡𝑜𝑛𝑛𝑒 (𝑔𝑎𝑠)

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £160 × (241.92 ∗ 365)/1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £14128.13

Sulphuric acid (cost formulas assumed to be the same as lime)

Sulphuric acid dose assumed to be 3 mg/l = 3 kg/ML

Cap = Installed Sulphuric acid capacity in 000 kg/day = Sulphuric acid dose required x water flowrate at disinfection stage

Cap = 3 x 120.96 = 362.88 kg/day

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 201.85 ∗ 𝐶𝑎𝑝0.5315

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 201.85 ∗ (362.881000

)0.5315

134

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 117.7722

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £117772.20

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £55/𝑡𝑜𝑛𝑛𝑒

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £55 × (362.88 × 365)/1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £7284.82

Lime for after chlorination:

Cap = Installed Lime capacity in 000 kg/day = Lime dose required x water flowrate at disinfection stage

Lime dose required = 30 mg/l = 30 kg/ML

Cap = 30 x 120.96 = 3628.8 kg/day

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 201.85 ∗ 𝐶𝑎𝑝0.5315

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 201.85 ∗ (3628.8/1000)0.5315

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 400.4449

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £400444.90

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £55/𝑡𝑜𝑛𝑛𝑒

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £55 ×3628.8 × 365

1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £72848.16

Total cost:

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = 𝑀&𝐸 𝐶𝑜𝑠𝑡 + 𝐶𝑖𝑣𝑖𝑙 𝐶𝑜𝑠𝑡 + 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡𝑠 + 𝑀&𝐸 𝐶𝑜𝑠𝑡 𝑓𝑜𝑟 𝐿𝑖𝑚𝑒+ 𝑀&𝐸 𝐶𝑜𝑠𝑡 𝑓𝑜𝑟 𝑠𝑢𝑙𝑝ℎ𝑢𝑟𝑖𝑐 𝑎𝑐𝑖𝑑

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £111881.36 + £313702.42 + £14128.13 + £7284.82 + £72848.16+ £400444.90 + £117772.20

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £920379.79

17.5 Waste treatment-general 17.5.1 Assumptions made

(i) All the polyelectrolyte being added to the sludge stream will leave the waste treatment section in the stream being sent to landfill

(ii) The 5% and 20% dry solids concentration figures refer to the percentage of sludge solids in the streams which will consist of the coagulant and the solids present at the start of the process. These figures do not include the lime or polyelectrolyte added as they will dissolve.

(iii) The amount of solids was calculated based on the max turbidity and the corresponding colour and the units sized for this with a 15% overdesign for safety margins.

135

(iv) All tanks in this section were assumed to be made of stainless steel 17.6 Waste treatment-Thickening 17.6.1 Assumptions made: (i) For costing the Gravity Thickener it was assumed the equations provided for the Picket Fence Thickener were valid as the designs are very similar. These equations were also for the options report but no further equations were given, so these were assumed to be accurate enough with the exception of the polyelectrolyte where additional cost info was provided

(ii) The maximum raw water concentrations of Iron and manganese were assumed for every calculation of the sludge solids in order to deal with the worst case scenario

(iii) The polyelectrolyte was dosed to thickener at 5 kg per tonne of dry solids

(iv) The storage and holding tanks did not need to be costed as no costing data was provided

17.6.2 Sizing and costing calculations Sludge solids produced:

𝑆𝑙𝑢𝑑𝑔𝑒 𝑠𝑜𝑙𝑖𝑑𝑠 (𝑘𝑔𝑑

) = 𝑇ℎ𝑟𝑢 × (2 × 𝑇𝑢𝑟𝑏 + 0.2 × 𝐶𝑜𝑙 + 1.9 × 𝐹𝑒 + 2.9 × 𝐴𝑙 + 1.6 × 𝑀𝑛)

Where Thru = works throughput in ML/day

Turb = Raw water turbidity in NTU

Col = Raw water colour in oHazen = PtCo

Fe = Raw water iron + iron dose in mg/l

Al = Raw water aluminium + aluminium dose in mg/l

Mn = Raw water manganese in mg/l.

So for maximum turbidity and colour with Aluminium sulphate as the coagulant. The sludge solids produced can be calculated as follows:

Thru = 121.1372008 ML/day

Turb = 200 NTU

Col = 21 PtCo

Fe = 10.8 + 0 = 10.8 mg/l

Al = 0 + 5.97 = 5.97 mg/l

Mn = 0.419 mg/l

𝑆𝑙𝑢𝑑𝑔𝑒 𝑠𝑜𝑙𝑖𝑑𝑠 (𝑘𝑔𝑑

)

= 121.1372008 × (2 × 200 + 0.2 × 21 + 1.9 × 10.8 + 2.9 × 5.97+ 1.6 × 0.419)

136

𝑆𝑙𝑢𝑑𝑔𝑒 𝑠𝑜𝑙𝑖𝑑𝑠 (𝑘𝑔𝑑

) = 53627.60

Sludge balancing tank

Total amount of sludge to be stored = 8887424 kg (obtained from mass balance) = 8887. 424 m3 (assuming 1 kg = 1 l as the sludge is mostly water). This also assumed the tank is to be designed to store a days’ worth of sludge

Depths of sludge tanks can be up to 6 m and can be rectangular or circular. Assuming a rectangular tank and the maximum depth, and that tank area is width x length and tank volume is area x depth (as for a standard rectangular vessel). By varying the length and width, it was found that a length of 50 m with a width of 35 m yields an area of 50 x 35 = 1750 m2 and a volume of 1750 x 6 = 10500 m^3 which is 15% greater than the total flowrate of sludge to be stored which takes the overdesign into account.

Sludge Thickener:

Chemical costs:

𝑀𝑎𝑠𝑠 𝑜𝑓 𝑃𝑜𝑙𝑦𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑡𝑒 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 5 𝑘𝑔 × 𝑑𝑟𝑦 𝑠𝑜𝑙𝑖𝑑𝑠 𝑖𝑛 𝑡𝑜𝑛𝑛𝑒𝑠

𝑀𝑎𝑠𝑠 𝑜𝑓 𝑃𝑜𝑙𝑦𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑡𝑒 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 5 𝑘𝑔 × 53627.60

1000

𝑀𝑎𝑠𝑠 𝑜𝑓 𝑃𝑜𝑙𝑦𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑡𝑒 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 268.138 … 𝑘𝑔

𝑀𝑎𝑠𝑠 𝑜𝑓 𝑃𝑜𝑙𝑦𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑙𝑦𝑡𝑒 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 = 268.14 𝑘𝑔

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £1450/𝑡𝑜𝑛𝑛𝑒

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £1450 ∗ (268.14 ∗ 365)/1000

𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡 = £141912.04

The Solids load of the thickener was assumed to be 4 kg/m2/h and the hydraulic upflow rate to be 1.5 m3/m2/h.

Sludge solids = 53627.60 kg/day = 2234. 483333kg/h

Thus area based on the solids load was determined

𝐴𝑟𝑒𝑎 = 𝑆𝑙𝑢𝑑𝑔𝑒 𝑠𝑜𝑙𝑖𝑑𝑠𝑆𝑜𝑙𝑖𝑑𝑠 𝑙𝑜𝑎𝑑

𝐴𝑟𝑒𝑎 = 2234.483333

4

𝐴𝑟𝑒𝑎 = 558.620 …

𝐴𝑟𝑒𝑎 = 559 𝑚2

And based on the hydraulic upflow rate:

137

𝐴𝑟𝑒𝑎 = 𝑆𝑙𝑢𝑑𝑔𝑒 𝑓𝑙𝑜𝑤𝑟𝑎𝑡𝑒

ℎ𝑦𝑑𝑟𝑎𝑢𝑙𝑖𝑐 𝑢𝑝𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒

𝐴𝑟𝑒𝑎 = 370.320502

1.5

𝐴𝑟𝑒𝑎 = 246.880 …

𝐴𝑟𝑒𝑎 = 247 𝑚2

The area based on the solids load is larger, so the thickener was sized for that area, taking oversize into account (so area = 1.15 x 558.620… = 642.413… = 642.4 m2)

The thickener will be a cylinder, thus the following equation holds:

𝐴𝑟𝑒𝑎 = 𝜋4

𝐷2

With D being the diameter of the thickener, thus

𝐷 = √4 × 𝐴𝑟𝑒𝑎𝜋

𝐷 = √4 × 642.413 …𝜋

𝐷 = 28.559 … 𝑚

The diameter was too large for a single thickener, which have typical diameters of 1.5 to 15 m. Multiple thickeners were thus considered with the area divided by the number of thickeners and substituted back into the equation for D to obtain the diameter of a single thickener. Using 4 thickeners gave a diameter for each thickener of 14.3 m with corresponding areas of 160.6 m2.

A backup thickener is required, so total thickener area = 5 x 160.6 m2 = 803 m2

Assuming the thickeners would be of maximum depth of 3 m

𝑇𝑜𝑡𝑎𝑙 𝑇ℎ𝑖𝑐𝑘𝑒𝑛𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒 = 𝑇𝑜𝑡𝑎𝑙 𝑇ℎ𝑖𝑐𝑘𝑒𝑛𝑒𝑟 𝐴𝑟𝑒𝑎 × 𝑑𝑒𝑝𝑡ℎ

𝑇𝑜𝑡𝑎𝑙 𝑇ℎ𝑖𝑐𝑘𝑒𝑛𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒 = (5 × 160.6) × 3

𝑇𝑜𝑡𝑎𝑙 𝑇ℎ𝑖𝑐𝑘𝑒𝑛𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒 = 2409.052

𝑇𝑜𝑡𝑎𝑙 𝑇ℎ𝑖𝑐𝑘𝑒𝑛𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒 = 2409 𝑚3

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡 (£000𝑠) = 45.849 ∗ 𝑉𝑜𝑙0.392

Vol = Thickener volume in 000 m3

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𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡 (£000𝑠) = 45.849 ∗ (2409.052

1000)0.392

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡 (£000𝑠) = 64.716 …

𝐶𝑖𝑣𝑖𝑙 𝑐𝑜𝑠𝑡 = £64716.29

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 14.366 + 3.5228 ∗ 𝐷𝑖𝑎

Dia = Total thickener diameter = 5 x 14.3 m = 71.5 m

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 14.366 + 3.5228 ∗ (5 × 14.3 )

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 266.244 …

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £266244.18

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = 𝑀&𝐸 𝐶𝑜𝑠𝑡 + 𝐶𝑖𝑣𝑖𝑙 𝐶𝑜𝑠𝑡 + 𝐶ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑐𝑜𝑠𝑡

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £266244.18 + £64716.29 + £141912.04

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = £472872.51

Sludge storage tank:

The tank needs to be sized for 3 days. Total amount of sludge to be stored thus = 1072552.06 kg/day (obtained from mass balance) x 3 days=3217656.181 kg = 3217. 656 m3 (assuming 1 kg = 1 l as the sludge is mostly water).

Depths of sludge tanks can be up to 6 m and can be rectangular or circular. Assuming a circular tank and a typical depth of 4.5 m, and that tank area is the same of that as a circle and tank volume is area x depth (as for a standard circular vessel). By varying the diameter, it was found that a diameter of 32.7 yields an area of 840 m2 and a volume of 840 x 4.5 = 3780 m^3 which is 15% greater than the total flowrate of sludge to be stored which takes the overdesign into account.

Polyelectrolyte storage tank:

Tank needs to be sized to store the polyelectrolyte required for both the thickener and for the FBC. So for a tank of a week’s storage:

Mass of polyelectrolyte for a week = (mass required for thickener for a day+ mass required for FBC for a day) x 7

Mass of polyelectrolyte for a week = (268.14 + 30.28) x 7 = 2088.96 kg

Dividing by the bulk density of 1 tonne per m3 = 1000 kg/m3, volume to be stored = 2.09 m3

Assuming a height to diameter ratio of approximately 1.2 and a circular vessel with a 15% overdesign, the height and diameter required are 1.67 m and 1.37 m respectively with an area of 1.47 m2 (obtained from the standard area formula for a circle) band a volume of 2.46 m3(obtained by multiplying the height by the area)

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17.6.3 Operation in non-ideal conditions As stated before, the full WTP was designed to treat water of the highest turbidity according to water quality data provided by the client. It was again necessary to take into account the climatic effect on the water quality to ensure the thickening system could be effective in conditions which were non-ideal. The situations that were considered are as follows:

x Highly turbid water during monsoon season x Sudden increase/decrease in throughput due to upstream failure t x Gravity Thickener unit failure

Highly turbid water during monsoon season:

As previously stated the Gravity thickeners and the sludge tanks have been designed to cope with the maximum turbidity possible. This will occur during monsoon season. When there is less turbidity, less sludge is produced and so the thickeners and tanks are well designed to cope with this situation

Sudden increase/decrease in flow due to upstream failure:

If in the unlikely event of the flowrate entering the thickening section increasing beyond that of the maximum turbidity conditions, the system will be able to cope up to a point. The Thickeners and sludge handling tank have been overdesigned by 15%, so they can handle an increase in the flowrate up to this point. More flow than this threshold would be problematic for the tanks as they would not be large enough to store volumes of sludge greater than this and the plant would need to be shut down.

If the flowrate entering the thickener is smaller than the maximum turbidity conditions which will occur based on the time of the year, the system will be able to cope perfectly fine as the units have been sized to deal with the larger flowrates. The system will operate as normal

Gravity Thickener unit failure:

In the event of one gravity thickener failing, the thickening section will be able to cope as a backup thickener has also been designed. In normal operation, sludge will only go to 4 of the designed thickeners (the ones in operation), with the backup one left empty. In the event of one thickener failing, flow to this thickener would be shut off and the sludge normally entering this thickener would flow into the backup thickener instead. Operation would continue as normal while the faulty thickener was either fixed or replaced. In the event of more than one thickener failing with the same flow of sludge as normal, the system will not be able to cope and will have to be shut down until the thickeners were either repaired or replaced.

17.7 Waste treatment-Dewatering 17.7.1 Assumptions made:

(i) The filter presses available for the design will be up to date equipment and not one of the older models

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(ii) The water entering the press from the sludge storage tank will contain 5% dry solids

(iii) The filter press can produce a sludge stream containing 20% dry solids (iv) The recycle stream leaving the filter presses can indeed be recycled as

the small amount of solids present in the stream will not be a problem (v) The sludge stream produced by the filter press will contain 95% of the

sludge solids due the presses not being a 100% effective with the remaining 5% being recycled back through the process in the recycle stream

(vi) The cost formulas provided for the filter press for the options report were deemed accurate enough to cost the filter presses in this design

17.7.2 Sizing and costing calculations Filter Press:

It was assumed for this plant:

• 4 pressings per press per day

• Cake thickness = 40 mm

• Plate size = 1500 mm

• Number of chambers per press ≤100

• S = the fractional solids concentration of the cake = 0.2 (20% solids concentration)

Thus:

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑤𝑖𝑑𝑡ℎ = 1.35 × 𝑝𝑙𝑎𝑡𝑒 𝑠𝑖𝑧𝑒 + 200

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑤𝑖𝑑𝑡ℎ = 1.35 × 1500 + 200

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑤𝑖𝑑𝑡ℎ = 2225 𝑚𝑚

Dry solids load = 53627.60301 kg/day*7/1000 = 375.393… = 375.39 tonne/week

Starting with 1 press.

No. pressings per week = 4 x 7 = 28

𝐶𝑎𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚3) = (1 − 0.6𝑆) × 𝐷𝑟𝑦 𝑠𝑜𝑙𝑖𝑑𝑠 𝑙𝑜𝑎𝑑 (𝑡𝑜𝑛𝑛𝑒

𝑤𝑒𝑒𝑘 )𝑆 × 𝑁𝑜. 𝑝𝑟𝑒𝑠𝑠𝑖𝑛𝑔𝑠 𝑝𝑒𝑟 𝑤𝑒𝑒𝑘

𝐶𝑎𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚3) = (1 − 0.6 × 0.2) × 375.39

0.2 × 28

𝐶𝑎𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚3) = 58.990 …

𝐶𝑎𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚3) = 59

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 = 24 × 𝑐𝑎𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 – 13

141

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 = 24 × 59 – 13

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 = 1402.76872

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 𝑝𝑒𝑟 𝑝𝑟𝑒𝑠𝑠 = 𝑇ℎ𝑒 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠

𝑁𝑜. 𝑜𝑓 𝑝𝑟𝑒𝑠𝑠𝑒𝑠

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 𝑝𝑒𝑟 𝑝𝑟𝑒𝑠𝑠 = 1402.76872

1

𝑇ℎ𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 𝑝𝑒𝑟 𝑝𝑟𝑒𝑠𝑠 = 1402.76872 The number of chambers per press needed to equal less than 100, so the number of presses was increased until this was the case with the cake volume and number of chambers calculations repeated. 4 presses = 16 pressings per week met the appropriate criteria: Thus Cake volume = 14.75 m3, number of chambers =340.942… ≈ 341 , number of chambers per press = 85.23554 ≈ 86 (Note the number of chambers were rounded up to the next whole number as 85 chambers would not be an acceptable value to represent 85.23554 chambers) The overall press length, area and costs could then be calculated (1.15 for overdesign)

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑙𝑒𝑛𝑔𝑡ℎ(𝑚𝑚) = 4000 + (𝑁𝑜. 𝑜𝑓 𝑐ℎ𝑎𝑚𝑏𝑒𝑟𝑠 ×(𝑐𝑎𝑘𝑒 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠(𝑚𝑚) + 30)) × 1.15

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑙𝑒𝑛𝑔𝑡ℎ(𝑚𝑚) = 4000 + (340.942 … × (40 + 30))

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑙𝑒𝑛𝑔𝑡ℎ(𝑚𝑚) = 31445.84548𝑚𝑚

𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑙𝑒𝑛𝑔𝑡ℎ(𝑚𝑚) = 31445.85 𝑚𝑚

This area is for 4 presses however, so to include a 5th press. The overall press length = 31445.85 + 31445.85/4 = 39307.31 mm. With 427 chambers total.

It was assumed the total press area was equal to the overall length multiplied by the overall width:

𝑇𝑜𝑡𝑎𝑙 𝑝𝑟𝑒𝑠𝑠 𝑎𝑟𝑒𝑎 = 𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑙𝑒𝑛𝑔𝑡ℎ × 𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝑝𝑟𝑒𝑠𝑠 𝑤𝑖𝑑𝑡ℎ

𝑇𝑜𝑡𝑎𝑙 𝑝𝑟𝑒𝑠𝑠 𝑎𝑟𝑒𝑎 = 39307.31

1000×

22251000

𝑚2

𝑇𝑜𝑡𝑎𝑙 𝑝𝑟𝑒𝑠𝑠 𝑎𝑟𝑒𝑎 = 87.458 … 𝑚2

𝑇𝑜𝑡𝑎𝑙 𝑝𝑟𝑒𝑠𝑠 𝑎𝑟𝑒𝑎 = 87.5 𝑚2

Finally the press could be costed:

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 19.68 ∗ 𝑇𝐷𝑆0.3154

TDS = Total dry solids in kg/yr = 53627.60301 kg/day x 365 = 19574075.1 kg/yr

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 19.68 ∗ 19574075.10.3154

𝑀&𝐸 𝑐𝑜𝑠𝑡 (£000𝑠) = 444.243 …

142

𝑀&𝐸 𝑐𝑜𝑠𝑡 = £444243.79

𝑇𝑜𝑡𝑎𝑙 𝑐𝑜𝑠𝑡 = 𝑀&𝐸 𝑐𝑜𝑠𝑡 = £444243.79

17.7.3 Operation in non-ideal conditions As before it was necessary to take into account the climatic effect on the water quality to ensure the dewatering system could be effective in conditions which were non-ideal. The situations that were considered are as follows:

x Highly turbid water during monsoon season x Sudden increase/decrease in throughput due to upstream failure x Filter press unit failure

Highly turbid water during monsoon season:

As previously stated the filter presses have been designed to cope with the maximum turbidity possible. This will occur during monsoon season. When there is less turbidity, less sludge is produced and so the filter presses are well designed to cope with this situation

Sudden increase/decrease in flow due to upstream failure:

If in the unlikely event of the flowrate entering the dewatering section increasing, the system will be able to cope up to a point. The filter presses have been overdesigned by 15%, so they can handle an increase in the flowrate up to this point. More flow than this threshold would be problematic for the filter press as they would not be large enough to cope with volumes of sludge greater than this and the plant would need to be shut down. The plant would likely be shut down before this level of sludge reached the press anyhow due to the tanks upstream in the thickening section also not being able to cope with said situation.

If the flowrate entering the filter presses is smaller than the maximum turbidity conditions which will occur based on the time of the year, the system will be able to cope perfectly fine as the units have been sized to deal with the larger flowrates. The system will operate as normal

Filter press unit failure:

In the event of one filter press failing, the dewatering section will be able to cope as a backup filter press has also been designed for. In normal operation, sludge will only go to 4 of the designed filter presses (the ones in operation), with the backup one left empty. In the event of one press failing, flow to this press would be shut off and the sludge normally entering this press would flow to the backup press instead. Operation would continue as normal while the faulty press was either fixed or replaced if the failing press is the first one in series. If the failing press is not the first one in the series, due to the presses being connected together, operation would need to temporarily stop while the new press to be used was switched with the faulty one. After which operation can resume as normal. The sludge storage tank just upstream of the press being designed to

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store three days’ worth of sludge will allow for the units upstream to still operate as normal, while this is occurring due to the size of the tank, provided the changeover does not take more than three days. In the event of more than one press failing with the same flow of sludge as normal, the system will not be able to cope and will have to be shut down until the presses were either repaired or replaced, however as before the rest of the plant can still operate as normal due to the large sludge storage tank provided maintenance can be carried out within 3 days, otherwise the entire plant would need to be shut down.

17.8 Plant Layout To calculate the hydraulic gradient it is required to make an assumption of a constant fluid level at each process. As shown in the plant layout in figure 108 for the process such as the clarification the flow can be disputed to any of the five floc blanket clarifier. Therefore the mean, horizontal displacement along gradient was used to find the height of process. The table below shows the data used to create the hydraulic gradient.

Fig. 108 – Hydraulic Gradient for Process; in order of process numbers Clarification, Rapid Gravity filter 1, Rapid Gravity Filter 2 and Chlorine contact tank

Table 46 – Plant layout calculation

Process Horizontal Displacement

Height at start Height at end

Height of Process

Clarification 27.88 9.16 6.25 7.705 Filtration 1 71.38 4.87 3.21 4.04 Filtration 2 102.58 2.21 0.71 1.46 Chlorination 108.39 1.46 0.6 1.03

0

1

2

3

4

5

6

7

8

9

1 2 3 4

Heig

ht (m

)

Process Stage

Hydraulic Gradient through the water treatment plant

144

18. Sludge Storage and Management Once the sludge leaves the WTP it will consist of 20% solids and will be pumped to a storage silo designed to hold a week’s worth of sludge. A week was chosen to account for instances when sludge removal trucks are not permitted to use the access roads due to unsafe conditions, for example during monsoon conditions. A second silo will be in place in the event of failure of the main silo . This secondary silo has the same capacity as this will simplify construction and save costs on ordering material. It also means that there is a maximum of 2 weeks storage. Additionally, an extra pipeline and sludge pump should be constructed for the emergency silo. Finally, a non-return valve will be placed on each pipe to control flow.

18.1 Silo Capacity The mass flow rate of the sludge is 255tonnes/day. The density of the solids is estimated to be 1400m3/kg giving a sludge density of 1080m3/kg; the densities of lime, polymer and chlorine can be neglected as the sludge contains such a minimal amount of each (3%, 0.1% and 0.05% respectively). This results in the main silo having a volume requirement of 1653m3 with the weight of the sludge as 17.5MN. Including a factor of safety of 1.5 the total weight that the silo should hold is 26.3MN. In the case of sludge being produced faster than the figure given above a factor of safety was discussed but was decided to not be used because the silos can already handle 1 week’s worth of sludge and should be emptied daily so a faster production rate should not overfill the silo.

18.2 Sludge Pump The transfer of the sludge to the silo will made by using sludge pumps; the Wangen Hopper Feed pump has been chosen (DMB Mena Water, n.d.), shown in Figure. 109. The large screw enables more sludge to be carried with high efficiency (DMB Mena Water, n.d.). The pump can work up to under 12 bar pressure with the maximum capacity of 50m3/h (DMB Mena Water, n.d.). De-watered sewage sludge up to 45% solids content can be pumped which is more than required for the sludge coming from the WTP process which is roughly 20% (DMB Mena Water, n.d.). Two Sludge pumps will be installed for sludge conveyance, one of them will be an emergency back-up pump.

. Figure 109. Sludge Pump (DMB Mena Water, n.d.)

145

18.3 Overflow If the main silo reaches a critically high volume level of sludge then an automatic control system will open the valve leading to the emergency silo and will start filling whilst the main silo is shut off until it has been emptied to a safe working level. This control system is explained in control section.

18.4 Construction The silos will be fabricated offsite and will include 2 openings on the top: one to allow the incoming pipe to discharge the sludge and the other as a manhole for workers to access for maintenance. There will also be an opening on the bottom which can be opened or closed to allow emptying of the silo into the removal trucks. The silo will be placed and secured into a support structure for stability and will allow trucks to drive underneath so that they have access to the sludge exit at the bottom of the silo; the structure will also have a ladder so that workers can reach the top of the silo.

18.5 Waste Management of Sludge At Tamil Water Solutions we aim to find the most environment and sustainable solution to the disposal of sludge. Firstly, it is important to understand the composition of the Sludge. The sludge is 80% water and 20% solids, of this solid is mostly the chalky substance Alum (C KAl(SO4)2·12H2O). It is understood that Alum can be used as a component to make pavement slabs, such as an example seen in Taiwan (Bob Hyde, 2015). Following consultation with stake holders and a public hearing it will decided if building the necessary infrastructure to available to turn sludge solid into pavement slab something which would beneficial to the community and region. However, in the circumstance that it is not possible, sludge will be transported to the closest landfill using trucks. The silo must be emptied every day by disposal trucks – this is to prevent the sludge filling the silo. Shandong Sanxing Group Co. Ltd. offer 10,000 gallon capacity steel trucks meaning that 6 of these will be required daily to remove the sludge and dispose it to landfill; this company have been known to sell their products in India in the past (Shandong Sanxing Group Co. Ltd.). A short path would need to be constructed for the trucks to access the silo from the nearby road north of the WTP and sludge storage site.

18.6 Amenities The sludge storage site is next to the WTP therefore there is little need for many amenities however, there must also be cleaning stations for the workers to wash their hands and receive protective gloves. In addition, a PPE store will allow access to protective equipment including helmets and fluorescent jackets, full body suits and masks; there will also be first aid facilities to treat any injuries.

146

18.7 Sludge Tank Structure Design

British Standards: BS EN 14015: 2004, Section 9.2.2 w

as used to design the sludge tank wall and roof thicknesses.

18.7.1 Wall Thickness

The tank is split into 8 courses to determine the w

all thickness. The tank will be 20m

high with a diam

eter of 12m to ensure it has

adequate capacity to store the sludge. Table 47 summ

arises the calculations of the wall thickness for each course.

Table 47 – Table show

ing the tank wall thickness

C

ou

rse 1

C

ou

rse 2

C

ou

rse 3

C

ou

rse 4

C

ou

rse 5

C

ou

rse 6

C

ou

rse 7

D

Tank Diameter

(m)

12 12

12 12

12 12

12 S

Allowable Design Stress

(N/mm

2) 230

230 230

230 230

230 230

W

Max Design Density of contained liquid

(kg/l) 1

1 1

1 1

1 1

Hc

Height of tank wall (bottom

of course to top of shell)

(m)

20 17

14 11

8 5

2

p

Design Pressure (m

bar) 0

0 0

0 0

0 0

c Corrossion Allow

ance (m

m)

- -

- -

- -

-

ec

Design Shell Thickness (m

m)

5.0 4.3

3.5 2.7

2.0 1.2

0.4 e

cr Recom

mended Shell Thickness

(mm

) 10

5 5

5 5

5 5

147

Assumptions: - The tank is filled to the top of the 20m shell (BS EN-14015-2004, Section 9.2.1) - Yield strength of steel = 345N/mm2 - Allowable Design Stress, S = 2/3 of Yield Strength = 230N/mm2 (BS EN-14015-

2004, Section 9.1.1) - Design Pressure is negligible for tanks with a design pressure < 10mbar (BS

EN-14015-2004, Section 9.2.2)

18.7.2 Stiffening Ring Design Stiffening rings (also known as wind girders) support the reservoir tank walls when subject to wind loading or negative pressures in the tank. A primary stiffening ring is not required, due to the tank having a fixed roof. However, a top corner ring will be used instead. However, a secondary ring will be needed, to ensure the roundness of the entire shell is preserved and that local buckling is prevented in the event of wind loading or negative pressure.

18.7.2.1 Secondary Stiffening Ring Design Table 48 summaries the calculation of the location and size of the secondary stiffening required. The following equations were used to calculate this:

148

120mm

120mm 10m

m

TANK WALL

Fillet weld

Fillet weld

Table 48 – Calculation of the number of stiffening rings required

C

ou

rse

1

Co

urse

2

C

ou

rse

3

Co

urse

4

C

ou

rse

5

Co

urse

6

C

ou

rse

7

D

Tank Diameter

(m)

12 12

12 12

12 12

12 e

(mi

n)

Thickness of Top Course (m

m)

5 5

5 5

5 5

5

e

Thickness of each course in turn (m

m)

10 5

5 5

5 5

5 h

Height of each course in turn

(m)

3 3

3 3

3 3

2 H

e

Equivalent Stable height of each course (m

) 0.53

3.00 3.00

3.00 3.00

3.00 2.00

HE

Equivalent stable full shell height (m

) 1.92

1.92 1.92

1.92 1.92

1.92 1.92

pv

Design internal negative pressure (m

bar)

5 5

5 5

5 5

5

vw

Wind gust velocity

(m/s)

45 45

45 45

45 45

45 K

Factor

- 9.39

9.39 9.39

9.39 9.39

9.39 9.39

Hp

M

ax permitted spacing of secondary stiffening rings

(m)

12.63 12.63

12.63 12.63

12.63 12.63

12.63

n

Number of Stiffening Rings needed

0.151639854

1

Therefore only 1 secondary stiffening ring will be needed. This w

ill be located 10m above the bottom

of the tank.

Fig. 110 – Detail of the secondary stiffening ring

149

The size of the secondary stiffening ring in Figure 110 is assumed according to British Standards.

18.7.2.2 Top Corner Stiffening Ring Design A top corner ring is required for additional strength. This will be located at the top of the tank wall. The top corner ring has the same dimensions as the secondary stiffening ring, detailed in Figure 110.

18.7.2 Roof Design The roof has been designed according to British Standards: BS EN 14015: 2004, Section 10.4. Assumption:

- There is no need to design for internal design pressure, as this is 0mbar.

18.7.2.1 Design for buckling The equation below was used to calculate the roof thickness. The results are summarised in Table 49. Table 49 – Summary of roof thickness calculations

R Diameter of Service Reservoir 12 m

R1 Radius 12 (m) pe Design internal negative pressure 0.50 (kN/m2) E Youngs Modulus 205000 (N/mm2)

ep Roof Plate Thickness 2 (mm) The minimum thickness calculated is 2mm. For safety a thickness of 5mm is used.

18.7.3 Bottom plate thickness The bottom plate thickness was designed according to British Standards: BS EN 14015: 2004, Annex H - H.1.4. The equation below was used to calculate the roof thickness. The results are summarised in Table 50

150

Table 50 – Summary of bottom plate thickness calculations

L Distance between centre lines of supports 6 m H Max Height of liquid in tank 18 m W Density of contained liquid 1 kg/l p Design Pressure 0 mbar S Allowable Design Stress for Steel bottom plate 230 N/mm2 c Corrosion Allowance - mm

eb Allowable Bottom Plate Thickness 121.2996319 mm ebr Recommended Bottom Plate Thickness 125 mm

A thickness of 125mm is therefore used.

151

19. Water Conveyance This section describes the processes used to design the pumped pipe system. Many of the following sections are dependent upon each other and therefore it is important to design the system as a whole.

19.1 Water Demand Analysis into population and water demand forecasts provided us with a potable water demand of 1.15m3/s for the 2030 population of Sandalwood. As this is a pressurised system, leakages are inevitable therefore the design assumes 20% leakages in the pipe system (Purcell, 2013). Demographic projections have been used to predict Sandalwood’s population after 10 years to ensure that the project has the capacity for a population over the 500,000 stated in the brief for 2020. Considering India’s urban population growth rate between the years 2006 and 2014 in Fig. 111, the population has been estimated by linear growth at 600,000 people by 2030 and therefore this is our design value.

Fig.111 – India’s Urban Population Growth

Fig. 112 – Expected Sandalwood population

y = 9.4362x - 18586

050

100150200250300350400450

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Popu

latio

n (x

106 )

Year

India's Urban Population 2006-2014

y = 9929.7x - 2E+07

480000

500000

520000

540000

560000

580000

600000

620000

2018 2020 2022 2024 2026 2028 2030 2032

Popu

latio

n

Year

Sandalwood population 2020-2030

152

Sandalwood 2030 population: 600,000 Daily human water consumption: 150L/d (CC WATER, n.d.) Sandalwood water consumption 2030 (including a factor of safety of 10%): 1.15m3/s Total Water Demand including leakages: 1.38m3/s As this is a pressurised system, leakages are inevitable. The design assumes 20% leakages in the pipe system (Purcell, 2013).

19.2 System Characteristics

19.2.1 Pipe Characteristic Curve

19.2.1.1 Introduction To perform an accurate analysis of the pipe characteristic the pipe was split into 11 sections along its 120km length. Over these lengths the vertical height is also measured and a rough gradient can be either by calculation or from Fig. 113. The gradients are so small that it has been assumed that the horizontal length is equal to the true length of pipe.

Fig. 113 – Profile of recommended pipe route The pipe route as specified in Section 6 is split into three phases: Phase A, B and C as shown below. A characteristic curve for each Phase has been constructed as opposed to one curve for the whole pipeline, this will improve efficiency in the design due to varying gradients. Each phase contains a number of smaller sections as shown in Table 51.

0200400600800

10001200

0 20 40 60 80 100 120

Elev

atio

n /m

Horizontal Distance /km

153

Fig. 114 – Map detailing the route split into three phases Four different diameter pipes have been analysed and compared; this is to give an economic comparison of size of pipe against change in pumping requirements. The four different sized diameters were chosen as DIP is commonly manufactured up to these sizes (DIPRA,2001) and they give acceptable head and flow for our required demand as is shown when constructing the system characteristic curves. The four different nominal diameters are:

- 900mm - 1000mm - 1100mm - 1200mm

Table 51 – Example table for a general head profile depending on diameter chosen for the demand required

1000mm Diameter

Friction Head (m) Static Head (m)

Total Head (m)

Horizontal Distance Along Route (m)

Start of Phase A 70.6 70 140.6 8400 End of Phase A 141.2 -100 41.2 16800

Start of Phase B 14.1 20 34.1 1680

105.9 0 105.9 12600

21.2 50 71.2 2520

28.2 50 78.2 3360

63.6 100 163.6 7560

End of Phase B 148.3 100 248.3 17640 Start of Phase C 77.7 100 177.7 9240

218.9 100 318.9 26040

End of Phase C 113.0 20 133.0 13440 Total: 1003 510 1513 119280

154

To calculate Table 51 using an assumed diameter of 1m the following example calculation is provided below. This calculation can be repeated for any assumed diameter.

19.2.1.2 Area of Pipe

𝐴 =𝜋𝐷2

4=

𝜋 ∗ 14

= 0.79𝑚

19.2.1.3 Flow Velocity

𝑢 =𝑄𝐴

=1.4

0.79= 1.78𝑚/𝑠

Note: Velocity must be above 0.75m/s to achieve self cleaning.

19.2.1.4 Reynolds Number

𝑅𝑒 =𝜌𝑢𝐷

𝜇=

1000 ∗ 1.78 ∗ 10.001

= 1782535

𝜇 = 𝐷𝑦𝑛𝑎𝑚𝑖𝑐 𝑉𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦 𝑜𝑓 𝑊𝑎𝑡𝑒𝑟 𝑎𝑡 20°𝐶 = 0.001

19.2.1.5 Friction Factor

𝜆 = 0.0055 (1 + (20000𝑘𝑠

𝐷+

106

𝑅𝑒)

13

) = 0.052

The recommended DIP has a concrete spun lining along it’s whole length. This gives a value of 0.03 for 𝑘𝑠 (Twort et al, 2000).

19.2.1.6 Head Losses due to Friction

ℎ𝑓 =𝜆𝐿𝑢2

2𝑔𝐷=

0.052 ∗ 𝐿 ∗ 1.782

2 ∗ 9.81 ∗ 1

L depends on the length of pipe under consideration and is determined by how many sections the total length has been split into.

155

19.2.1.7 Construction of Pipe Characteristic Curves As four diameters are being compared then four pipe characteristic curves should be produced; one for each diameter. All the characteristics for phase A are below as examples however this has been repeated for every phase but omitted from the report for length. To construct the characteristic curves the above equations were used. This time a constant diameter was input with a varying flow and the corresponding total head was recorded for each flow. The results are shown in Figures 115-118.

156

Fig. 115 – Pipe Characteristic curve for the 900mm diameter pipe

Fig. 116 – Pipe characteristic curve for the 1000mm diameter pipe

Fig. 117 – Pipe characteristic curve for the 1100mm diameter pipe

Fig. 118 – Pipe characteristic curve for the 1200mm diameter pipe

-200

0

200

400

600

800

1000

0 1000 2000 3000 4000 5000 6000 7000 8000

Hea

d (m

)

Discharge (m3/h)

-1000

100200300400500600

0 1000 2000 3000 4000 5000 6000 7000 8000

Hea

d /m

Discharge m3/h

-100

0

100

200

300

400

0 1000 2000 3000 4000 5000 6000 7000 8000

Hea

d /m

Discharge m3/h

-50

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000 7000 8000

Hea

d (m

)

Discharge (m3/h)

157

19.2.2 Pump Characteristic Curves The pump selection chart shown in Figure 119 shows pumps with flowrate in the range of 5 – 1680m3/h. The chart details the operation range for a Horizontal split case single stage centrifugal pump. For each phase the best fitting pump was selected according to head required to operate at the maximum available efficiency. The pump selection chart provided by Grundfos searches all the horizontal split case pumps in the available international range (Grundfos 2015). India National Grid runs at a frequency of 50 Hz, therefore only pumps with a motor that operates at 50Hz are suitable for connection to the grid (Power Grid Corp 2015). Each pump has it’s own characteristic curve and once a pump was selected it’s pump characteristic was then analyses and compared in Section 19.2.3.

Fig. 119 – Operation range for a horizontal split case single stage centrifugal pump

19.2.3 System Characteristic Curves Once both pipe and pump characteristic curves have been calculated and plotted it is then possible to superimpose them onto the same graphs. A pumped pipe system acts as a whole and the point where these two lines cross is the Operating Point and represents the flow rate and head that the system will operate at. It is therefore important that the operating point is at the flow rate that is required to meet the demand for Sandalwood. This value is 5004m3/h.

158

Both curves can be manipulated, the pipe characteristic curve can be changed by dividing the total head by number of stations the phase is split into and the pumps characteristic curve can be manipulated by adding pumps in series or parallel. The equations for the effects on head and flow rate by adding pumps in this way are given below (Chadwick et al, 1998). For series operation (of n pumps),

𝐻𝑛𝑝 = 𝑛𝐻𝑝 𝑄𝑛𝑝 = 𝑄𝑝 For parallel operation (of n pumps),

𝐻𝑛𝑝 = 𝐻𝑝 𝑄𝑛𝑝 = 𝑛𝑄𝑝 As is it undesirable to continue to increase the head any more than necessary because it would mean an increase in the number of pumping stations (and there are 3 pumps per station) then it more cost effective to add pumps in parallel. An example manipulation of these system characteristics is shown below in Figure 120.

Fig. 120 – Pump characteristic curve manipulation for a 1200mm diameter DIP in Phase A In this example it can be seen that to meet the required demand with this pump it would require three pumps in parallel per station and there would be one station along the length of the phase. This would give a total of 3 normal working pumps and 6 pumps in total. Another example of calculating the operating point is to divide the phase into sections and calculate the required specifications of pump to achieve the head required per station. An example graph of this is given below and Figure 121.

-50

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000 7000 8000

Hea

d (m

)

Discharge (m3/h)

1200mm Diameter - Phase A - Pump Manipulation

Pipe Characteristic 3 Pumps in Parallel Single Pump 2 Pumps in Parallel

159

Fig. 121 – System Characteristic curve manipulation for a 1200mm diameter DIP in Phase B This has been done for every diameter and shown in Table 52 so that in the next section it is possible to make an economic comparison so that the client is getting the most cost effective solution. Table 52 – Table displaying the different heads produced by the selected pump associated with a particular diameter and how many of those pumps would be needed to produce the required flow for normal service while staying within the pressure rating of the pipe

Phase Total

Head per Station (m)

Number of Stations (m)

Q added per Pump (m3/h)

Diameter (mm)

Total # of Normal Pumps

A 112 3 1680 900 9 A 89 2 1680 1000 6 A 97 1 1680 1100 3 A 50 1 1680 1200 3 B 130 8 1680 900 24 B 116 6 1680 1000 18 B 110 5 1680 1100 15 B 116 4 1680 1200 12 C 103 9 1680 900 27 C 104 6 1680 1000 18 C 95 5 1680 1100 15 C 125 3 1680 1200 9

0100200300400500600700800

0 2000 4000 6000 8000 10000

Hea

d (m

)

Discharge (m3/h)

1200mm Diameter - Phase B - System Characteristic Manipulation

Phase Pipe CharacteristicCurve

Total Phase PumpCharacteristic

Per Station PipeCharacteristic Curve

Total Station PumpCharacteristic"

160

19.3 Economic Comparison The economic comparison compares the following criteria for each design:

x Capital cost of pipes and the associated pumps for various pipe diameters. x The estimated annual power charges.

19.3.1 Capital Cost of Pipe Material Table 53 – Table showing the total cost of the pipeline material depending on the diameter of pipe used

Nominal Diameter of Pipe

(m)

Total Mass (tons)

Installation Cost (M£)

Material Cost (M£)

Total Cost (M£)

0.9 59357.1 4.86 1.70 6.56 1 65781.0 5.40 1.88 7.45

1.1 72205.0 5.94 2.07 8.01 1.2 78628.9 6.48 2.25 8.73

Density of Iron was taken as: 7100kg/m3

19.3.1.1 Total Mass The total mass in Table 53 was calculated using the following equations.

𝜌 =𝑚𝑣

𝑣 = [(𝑜𝑢𝑡𝑒𝑟 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟)2 − (𝑖𝑛𝑛𝑒𝑟 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟)2]𝜋4

𝐿

19.3.1.2 Installation Costs Capital costs of pipeline in rural conditions = £0.45 per mm diameter per m laid (Twort et al, 2009)

19.3.1.3 Material Costs

𝐶𝑜𝑠𝑡 (£) = 𝑡𝑜𝑡𝑎𝑙 𝑚𝑎𝑠𝑠 ∗ 43.4 ∗ 0.66 $43.4/tonne taken from QUANDL, 2015.

161

19.3.2 Annual Pump Operating Costs Table 54 – Operating cost of every pump/diameter combination for each phase

Power

Operating Cost

Phase

Head per

Station (m)

Q per Pump

(m3/h)

Diameter (mm) η

# of Normal Pumps

kW 1 year

(million £)

A 112 1680 900 0.82 9 5628 3.45 A 89 1680 1000 0.82 6 2981 1.83 A 97 1680 1100 0.82 3 1625 1.00 A 50 1680 1200 0.82 3 837 0.51 B 130 1680 900 0.82 24 17419 10.68 B 116 1680 1000 0.82 18 11657 7.15 B 110 1680 1100 0.82 15 9212 5.65 B 116 1680 1200 0.82 12 7771 4.77 C 103 1680 900 0.82 27 15526 9.52 C 104 1680 1000 0.82 18 10451 6.41 C 95 1680 1100 0.82 15 7956 4.88 C 125 1680 1200 0.82 9 6281 3.85

Pump power consumption is calculated by;

𝑃 =𝑄𝐻𝜌𝑔

𝜂

Where,

𝑃 = 𝑃𝑜𝑤𝑒𝑟(𝑊) 𝑄 = 𝐹𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 (𝑚3

𝑠⁄ ) 𝐻 = 𝐻𝑒𝑎𝑑 (𝑚)

𝜌 = 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 (𝑘𝑔𝑚3⁄ )

𝑔 = 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑑𝑢𝑒 𝑡𝑜 𝐺𝑟𝑎𝑣𝑖𝑡𝑦(𝑚𝑠2⁄ )

Cost of operating is calculated by;

𝑃(𝑘𝑊ℎ) = 𝑃(𝑘𝑊)ℎ ℎ = 𝑤𝑜𝑟𝑘𝑖𝑛𝑔 ℎ𝑜𝑢𝑟

The cost of electricity is given in costing sheet supplied by the University of Edinburgh in which it is given as,

𝑃𝑟𝑖𝑐𝑒 𝑓𝑜𝑟 𝑘𝑊ℎ = £0.07

162

19.3.3 Capital Cost of Pumps Table 55 – Pump capital cost of each selected combination per phase

Phase Impeller Size (mm)

Head per pump (m)

Pump Purchase Price

(£)

Total Number of Pumps

Total Cost (£)

A 436 17 4693 6 28000 B 603 10 6223 24 149000 C 618 14 6457 18 116000

Formula taken from University of Edinburgh Costing Sheet, 2015.

Pump purchase price = £(10 x diameter in mm + 20 x head in m)

19.3.4 Discussion Comparing these tables shows that the difference in capital cost of pipeline for a 100mm change in diameter is greatly insignificant compared to the operation cost of the system over it’s design life. The operating cost of the pump should be the design driver and for this reason a 1200mm diameter pipe for each phase is recommended and designed to be used in conjunction with the Pumps specified in Table 56. The final system characteristic graphs for each phase are shown in Figures 112 - 124; showing the working head in each phase. Table 56 – Selected pump name for each Phase

Phase Pump Stations

# of Pumps in Parallel

Total # of pumps Pump Name

A 1 3 6 HS 350-250-498/435.6 5/1-F-A-BBVP

B 4 3 24 HS 350-250-630/602.5 5/1-F-A-BBVP

C 3 3 18 HS 350-250-630/602.5 5/1-F-A-BBVP

Fig. 122 – System characteristics for Phase A final selection

-50

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Hea

d (m

)

Discharge (m3/h)

1200mm Diameter - Phase A

163

Fig. 123 – System characteristics for Phase B final selection

Fig. 124 – System characteristics for Phase C final selection

0

100

200

300

400

500

600

700

800

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Hea

d (m

)

Discharge (m3/h)

1200mm Diameter - Phase B

0

100

200

300

400

500

600

700

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Hea

d (m

)

Discharge (m3/h)

1200mm Diameter - Phase C

164

19.4 Pump Locations The decision to design the pumped pipeline in three phase reflects the change from phase B to C from an underground to over ground pipe. The decision also incorporates the change in gradient ensuring the most efficient pump solutions is used. Figure 125 shows the locations of pump station along the length of the pipeline.

Fig. 125 – Preliminary pump locations along pipe route Table 57 – Average gradient of each phase

Phase Average Gradient (Degrees) A -0.07 B 0.41 C 0.25

Fig. 126 – Location of pump stations along the elevation of the pipeline.

165

Determining final pump locations should take into account factors such as:

x Proximity to residential buildings x Accessibly from roads x Prominence on the landscape x Susceptibility to flooding x Possible expansion of the city of Kanakapura in the future

For the pump stations located close to the town of Kanakapura, care will need be taken to ensure pump stations a located far enough away from homes as to not cause any noise pollution to residents. Consulting with stake holders and sound engineers to find the best location should be considered.

19.5 Pump Station Design Each stations have two pump houses containing three pumps in parallel. Feedback from the options report suggests that a 3rd ‘assisting’ pump is not required therefore this has been discarded and now each station contains three primary normal working pumps and three secondary pumps that will be used in an emergency or maintenance. The primary pump house and secondary pump house will be separate buildings spaced at least 10m apart, this is to reduce the risk of complete shutdown of pumping. Further discussion of risk is detailed in Section 27.

Fig. 127 – General sketch of one of the pumping houses The major design considerations for the pump design are as follows:

- Housing material - Drainage - Storage for equipment and safety. - Material choice

166

Material choice should reflect the amount the fuel load e.g. the amount of burnable material present should be minimised (Jones, 2006). For this reason the housing will be made of Concrete bricks with a water tight roof. The building will be designed with a stable steel frame structure able to withstand the possibly of earthquakes in the region.

19.5.1 Dimensions - The floor area taken up by each pump is 2.83m3 therefore a total of

8.49m2 is require to hold the pumps shown in CAD drawing in the Appendix.

- It is recommended that a minimum gap of 4 feet (1.21m) between adjacent pumps and 3 feet (0.91m) to closest wall should be left to allow access for operations and maintenance (Department of the Army and Air force, USA, 1985).

- Figure 128 shows the dimensions of the pump station are 7.42 x 4.83m, giving a total Floor Area of 36m2. This gives enough space for inspection and maintenance.

Fig. 128 – Dimensions of a general pump house

Pump 1

Pump 3

Pump 2

167

19.5.2 Pump Station Layout Non-return valve are mounted on the discharge line to prevent backflow through the pump during surge scenarios. (Grundfos R&T, 2015). This also ensures pumps are primed when shut off. It is recommended that to operate at the optimal point one of the parallel connected pumps should have variable speed control (GRUNDFOS R&T, 2015). A variable speed drive connected to one of the pumps in each station offers greater control over flowrate. It is beneficial to increase flowrate if losses in the pipeline exceed expected values or reduce flowrate when loses are less than expected. It also gives greater control to if flowrate may need to be increased in future but in doing this comes adversely reduces the efficiency to which the pumps operate at. Fig. 129 – Flow diagram of pump station layout

168

19.6 Intake Pump Intake of the pump will be located at NBR close the to the water edge on stable ground. Water will be delivered using horizontal split case pumps this is because they can be used for pumping raw water and operate at high efficiencies (Grundfos, 2015). Using same type of pump means less time spent in the construction, planning and maintenance.

19.6.1 Suction Piping Suction piping is a specially designed system which ensures the smooth flow of water into the pump reducing the amount of trapped air. The suction bell (Figure 130), which is chamfered to provide smooth and undisturbed flow (Whitesides, 2012) to the pump in which the loss coefficient is 𝜁 = 0.05 (KSB, 2005). Chamfered entrance reduces the vortex formation up to 80% (Whitesides, 2012).

Fig. 130. Chamfered Suction Bell (Whitesides, 2012) (KSB, 2005)

A suction bell is installed with a strainer to prevent big particles from entering the water stream which can block the flow and damage the pumps. Cleaning of the mesh used for the strainer will be carried out regularly. Foot valves will be vital for preventing flow travelling backward by the gravitational effect, excessive back pressure and reverse rotation. Furthermore it is vital for the priming of the pump (SPP Pumps, 2012).

Fig. 131. Strainer, Foot Valve (Non-return Valve) and Long radius elbow (Towsley, 2009)

169

19.6.2 Suction Pipe The pipe is designed to be the shortest length possible as well as having a gradual gradient, this ultimately reduces the friction head loss (KSB, 2005) (SPP Pumps, 2012). The minimum straight length of suction pipe going into the pump is given as: 𝐿𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑝𝑢𝑚𝑝 ≥ 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑢𝑐𝑡𝑖𝑜𝑛 𝑝𝑖𝑝𝑒 (KSB, 2005) General causes of formation of air pockets include:

x Using longer pipes with many elbows x Sharp edges x Lack of complete priming

In order to prevent air pockets in the piping suction pipe, a pipe equipped with a long radius elbow toward the suction end of the pump should be installed (Towsley, 2009). An eccentric reducer is fitted which does not allow the formation of the air pockets as shown in Figure 132 (SPP Pumps, 2012).

Fig. 132. Eccentric Reducer (SPP Pumps, 2012)

19.6.3 Intake Pump For the horizontal split case pump the discharge assembly is shown as below:

Fig. 133 Discharge (SPP Pumps, 2012)

170

Various equipment is used to ensure the flow is stable for the remaining section to WTP.

x Increasers are installed to prevent turbulent flow. x Discharge valves are fitted to be used for the isolation of the system for

maintenance. (SPP Pumps, 2012). x The check valve gives maintenance staff access to view the flow and take

samples of the water if necessary. x Discharge piping must be supported independently to ensure that no

forces are acting on the piping (SPP Pumps, 2012). x Additionally, a short venturi tube to measure the flow rate in the pipeline

show in Figure 134 (KSB, 2005).

Fig. 134 Venturi tube (KSB, 2005)

19.6.4 Suction Bell Depth If the suction bell is placed too close to the surface; the suction effect creates an air entraining vortex to develop (KSB, 2005). The will result in pump running unsteadily and output to decrease (KSB, 2005). The minimum required submergence (𝑆𝑚𝑖𝑛 ) is calculated by the formula given by Hydraulics Institute (KSB, 2005);

𝑄 = 𝑣𝑠 ∙ 𝐴

𝑆𝑚𝑖𝑛 = 𝑑𝐸 + 2.3 ∙ 𝑣𝑠 ∙ √𝑑𝐸

𝑔

𝑆𝑚𝑖𝑛 = 1.64 𝑚

In order to operate in safer conditions safety factor of 20% is added making suction depth.

𝑆𝑚𝑖𝑛 = 2 𝑚 Explanation of variables used are as below:

𝑆𝑚𝑖𝑛 = 𝑑𝐸 + 2.3 ∙ 𝑣𝑠 ∙ √𝑑𝐸

𝑔

𝑄 = 𝑣𝑠 ∙ 𝐴

Where:

171

𝑆𝑚𝑖𝑛 = 𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝑆𝑢𝑏𝑚𝑒𝑟𝑔𝑒𝑑 𝐷𝑒𝑝𝑡ℎ (𝑚) 𝑑𝐸 = 𝐼𝑛𝑙𝑒𝑡 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑠𝑢𝑐𝑡𝑖𝑜𝑛 𝑝𝑖𝑝𝑒 𝑤𝑖𝑡ℎ 𝑠𝑢𝑐𝑡𝑖𝑜𝑛 𝑏𝑒𝑙𝑙 (𝑚)

𝑔 = 𝐺𝑟𝑎𝑣𝑖𝑡𝑎𝑡𝑖𝑜𝑛𝑎𝑙 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 (𝑚/𝑠2) 𝑄 = 𝑉𝑜𝑙𝑢𝑚𝑒 𝐹𝑙𝑜𝑤𝑟𝑎𝑡𝑒 (𝑚3/𝑠)

𝐴 = 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑢𝑐𝑡𝑖𝑜𝑛 𝑝𝑖𝑝𝑒 (𝑚2) 𝑣𝑠 = 𝐹𝑙𝑜𝑤 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦(𝑚/𝑠) 𝑑 = 𝑃𝑖𝑝𝑒 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟(𝑚)

Finding Values:

𝐴 =𝜋𝑑2

4

𝐴 =𝜋 × 1.22

4= 1.13𝑚2

𝑄 =1.43

= 0.47𝑚3/𝑠 From,

𝑄 = 𝑣𝑠 ∙ 𝐴

𝑣𝑠 =0.471.13

= 0.41 𝑚/𝑠

𝑑𝐸 = 1.3 𝑚 𝑔 = 9.81 𝑚/𝑠2

𝑆𝑚𝑖𝑛 = 1.3 + (2.3 × 0.41 × √ 1.39.81

) = 1.64 𝑚

172

19.7 Pump Efficiency Curve The efficiency of pump is the relationship between the supplied power and the utilised amount of power. Efficiency is effectively a measure of how well the pump converts electrical energy supplied to the motor into fluid motion exiting the pump (Grundfos Pump Handbook, 2004).

𝜂 = 𝑃𝑜𝑤𝑒𝑟 𝑑𝑒𝑙𝑖𝑣𝑒𝑟𝑒𝑑 𝑡𝑜 𝑤𝑎𝑡𝑒𝑟

𝑆𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑃𝑜𝑤𝑒𝑟=

𝜌𝑔𝑄𝐻𝑃𝑠

Where:

𝜌 is the density of fluid (kg/m3) g is the acceleration of gravity (m/s2)

Q is the flow (m3/h) and H is Head (m)

Pump efficiency data is obtained though running tests on the pump operating under controlled conditions. The Figure 135 shows the head against flow curve of the pump specified at Phase A.

Fig. 135 - Head against flow for the specified pump at Phase A (Grundfos, 2015) Small improvements in pump efficiency yields significant reductions in the energy consumption by the pumps (Bunn, S.M, 2009). More efficient running reduces carbon emissions to the atmosphere yielding a more sustainable design.

Performance Curve

Efficiency Curve

Duty Point

173

19.8 Energy Demand and Supply The most important cost for pumps are the running costs (Flowserve, 2014). Within running cost electricity takes approximately 44% of the total life-cycle cost. Assuming pumps are being used 24 hours, 7 days a week and for 365 days result in the following operating costs for the selected pump and head.

Fig. 136 – General Pump Life Cycle Costs (Flowserve, 2014) It is assumed that it is possible to get the energy required from the main grid used in the area. The cables will mainly be placed underground and will be laid alongside the pipeline, possibly in the same excavation. The demanded energy will be drawn from the closest supply to ensure that pumps will run non-stop and any issues with the energy line can be repaired as soon as possible. Each pumping station will have a back-up diesel generator and will supply the system with energy enough to meet the demand during maintenance or in the event of failure of the normal energy supply. Table 58 Operating Costs for each Phase adapted from Table 54

Phase Head(m) kWh # of Pumps

1 year(M£)

A 50 837.4 3 0.5 B 116 7771.4 12 4.8 C 125 6280.8 9 3.9

TOTAL 9.1

174

19.9 Priming Horizontal split case pumps require priming before use. Priming can be achieved by fitting an external vacuum pump to the system and suck the air out of the system to ensure there are no air pockets left (SPP Pumps, 2012). In order for the air to escape all vents should be placed on the highest point (Goulds Pumps, 1999). Furthermore, all drains must be closed (Goulds Pumps, 1999). The filling should be made slowly in order not to damage the impeller and not cause any rotation by excessive velocities (Goulds Pumps, 1999). To prime intake pumps requires a special method. If the pump operates on a suction lift and a foot valve is included in the system, fill the pump allowed and the suction line with the liquid from an outside source. Trapped air should be allowed to escape through the vent valve filling (Patterson, n.d.).

19.10 Pump Design 3 Horizontal Split case pumps are used, these will be purchased from Grundfos. Table 59 – Pump Specifications

Pump Specifications Pump Name HS 350-250-498 HS 350-250-630 HS 350-250-630

Phase A B C Impeller Size

(mm) 435.6 602.5 617.6

Operating Flowrate (m3/h) 1680 1680 1680

Resulting head of a station (m) 50.03 116.1 125.2

Power rating (kW) 500 900 900

Duty Point Efficiency 84.5% 84.3%

84.7 %

175

Fig. 137 – Phase A pump detailed draw

ing

176

Fig. 138 – Phase B pump detailed draw

ing

177

Fig. 139 – Phase C pump detailed draw

ing

178

19.11 Control Technology Gould Pumps are leader in their field offering several systems to monitor the pumps,

x ProSmart Predictive Condition Monitoring (Goulds Pumps, 2015) - Minimizes Downtime by early warning and advanced diagnostics

enabling planned maintenance (Goulds Pumps, 2015) - Automatic Notification of Machinery issues to maximize the

productivity(Goulds Pumps, 2015) - Continuous monitoring of the machine health by analysing the

system in every 5 seconds (Goulds Pumps, 2015) x i-Alert 2- Equipment Health Monitor (Goulds Pumps, 2015)

- Information will be visible in smart phones via an application (Goulds Pumps, 2015)

- Monitor- “vibration, temperature and run time hours 24/7/365 (Goulds Pumps, 2015)”

- Alarm- If equipment operates outside its stated parameters the user will be alerted due to routine checks done each 5 minutes

- Trend- availability of trend graph for collected data - Analyse- machine faults

x PumpSmart Control Solutions (Goulds Pumps, 2015) - Smart flow- accurately measure process flow without a flow meter - Pump protection- under low flow - Flow Economy- “calculates process efficiency (Goulds Pumps,

2015)” - Multi-pump Control- “control for up to four pumps in parallel

automatic lead/lag changeover, redundancy back-up and synchronized torque control (Goulds Pumps, 2015)”

x Pump Integrated Memory- “Measures, records and presents temperature, pump current/ current variation, running time, number of starts, part counters, service log and application notes (Xylem, 2015)”

x Pump starter and level controllers- Protects against overloading the system (Xylem, 2015).

x The DeltaSpanTM LD34 Small Bore Pressure Level Transmitter can continuously measure water levels up to 30.4m with an accuracy of ±0.25% and one will be used for each service reservoir.

179

19.12 Over-ground Pipe Dimension Design The following calculations are performed to determine the pressure class of the pipe. A reduced pressure class saves costs on materials, transport and manufacturing.

x A general arrangement of ove-rground pipe support design includes having one pipe support per length of pipe, this is due to the flexible nature of the push on pipe. (DIPRA, 2001).

x The support location should be immediately behind the pipe bells as the bell contributes a significant amount of ring stiffness and reduces the load on the support (DIPRA, 2001).

x The support should cradle the pipe with a saddle angle of up to 120o, this reduces stress concentrations in the pipe wall (DIPRA, 2001).

x General pipe lengths are 18 or 20ft (DIPRA, 2001).

Fig. 140 – Pipe support schematic diagram (DIPRA, 2001)

19.12.1 Initial Calculation of Saddle Width Assume a pressure class of 150 and 48-inch pipe.

𝑏 = √2𝐷𝑡𝑒 = √2 ∗ 48.66 ∗ 0.46 = 6.69𝑖𝑛𝑐ℎ𝑒𝑠 = 0.170𝑚

𝑏 = 𝑚𝑖𝑛𝑖𝑚𝑢𝑚 𝑠𝑎𝑑𝑑𝑙𝑒 𝑤𝑖𝑑𝑡ℎ (𝑖𝑛𝑐ℎ𝑒𝑠) 𝐷 = 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑝𝑖𝑝𝑒 (𝑖𝑛𝑐ℎ𝑒𝑠)

𝑡𝑒 = 𝑛𝑜𝑚𝑖𝑛𝑎𝑙 𝑝𝑖𝑝𝑒 𝑤𝑎𝑙𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 (𝑖𝑛𝑐ℎ𝑒𝑠) = 0.46𝑖𝑛𝑐ℎ𝑒𝑠 𝑡𝑒 taken from Table 1 in DIPRA for a 48-inch pipe with pressure rating 150 aboveground (DIPRA,2001).

180

19.12.2 Pressure Class due to Localised Stress at Supports Assume a pressure class of 150 and a 48-inch pipe.

𝑓𝑟 = 𝐾 (𝑤𝐿𝑡𝑛

2) ∗ ln (𝐷

2𝑡𝑛) = 0.0249 (

1099 ∗ 200.32 ) ∗ ln (

48.762 ∗ 0.3

) = 26743𝑝𝑠𝑖

= 184𝑀𝑃𝑎

𝐿 = 𝑠𝑝𝑎𝑛 𝑙𝑒𝑛𝑔𝑡ℎ (𝑓𝑒𝑒𝑡) 𝐷 = 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑝𝑖𝑝𝑒 (𝑖𝑛𝑐ℎ𝑒𝑠)

𝑤 = 𝑢𝑛𝑖𝑡 𝑙𝑜𝑎𝑑 𝑝𝑒𝑟 𝑙𝑖𝑛𝑒𝑎𝑟 𝑓𝑜𝑜𝑡 (𝑙𝑏𝑓𝑡

)

𝐾 = 𝑠𝑎𝑑𝑑𝑙𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑡𝑛 = 𝑑𝑒𝑠𝑖𝑔𝑛 𝑤𝑎𝑙𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑜𝑓 𝑝𝑖𝑝𝑒 (𝑛𝑜𝑚𝑖𝑛𝑎𝑙 𝑝𝑖𝑝𝑒 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠

− 𝑐𝑎𝑠𝑡𝑖𝑛𝑔 𝑡𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒) (𝑖𝑛𝑐ℎ𝑒𝑠)

19.12.2.1 Unit Load

𝑤 = 𝑙𝑜𝑎𝑑 𝑓𝑟𝑜𝑚 𝑝𝑖𝑝𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 + 𝑙𝑜𝑎𝑑 𝑓𝑟𝑜𝑚 𝑤𝑎𝑡𝑒𝑟 𝑤𝑒𝑖𝑔ℎ𝑡 = 1099𝑙𝑏/𝑓𝑡 Taken from Table 3 in DIPRA,2001.

19.12.2.2 Saddle Coefficient Recent research has established that (DIPRA, 2001);

𝐾 = 0.03 − 0.00017 ∗ (𝛽 − 90°) = 0.0249 and it in this case 𝛽 = 120°.

19.12.2.3 Design Wall Thickness of Pipe

𝑡𝑛 = 0.38 − 0.08 = 0.3 Table 60 – Allowances for casting tolerances

Size (inch) Casting Tolerance (inch) 3 - 8 0.05

10 - 12 0.06 14 - 42 0.07

48 0.08 54 - 64 0.09

The maximum allowed localised stress should be 331MPa. This value is equal to the minimum yield strength in bending for DIP divided by a safety factor of 1.5. It is the same value given in ANSI/AWWA C150/A21.50. (DIPRA, 2001). Our value of 𝑓 gives our value at 184MPa and therefore within the bounds.

181

19.12.3 Pressure Class due to Hoop Stress Due to Internal Pressure Assume a pressure class of 150 and a 48-inch pipe.

𝑡 =𝑃𝑖𝐷2𝑆

𝑡 = 𝑁𝑒𝑡 𝑝𝑖𝑝𝑒 𝑤𝑎𝑙𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 (𝑖𝑛𝑐ℎ𝑒𝑠) 𝑃𝑖 = 𝐷𝑒𝑠𝑖𝑔𝑛 𝑖𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 (𝑝𝑠𝑖)

= 2 ∗ (𝑊𝑜𝑟𝑘𝑖𝑛𝑔 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 + 𝑆𝑢𝑟𝑔𝑒 𝐴𝑙𝑙𝑜𝑤𝑎𝑛𝑐𝑒) 𝐷 = 𝑂𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑝𝑖𝑝𝑒 (𝑖𝑛𝑐ℎ𝑒𝑠)

𝑆 = 42,000𝑝𝑠𝑖

𝑇 = 𝑡 + 𝑐𝑎𝑠𝑡𝑖𝑛𝑔 𝑡𝑜𝑙𝑒𝑟𝑎𝑛𝑐𝑒 + 0.08 = 𝑡 + 0.08 + 0.08 A minimum surge allowance of 100psi should be taken as recommended in DIPRA, 2001. 𝑃𝑖 differs per phase and is taken from Table 54 and adapted below into Table 61 Table 61 – Calculation of 𝑃𝑖 and t

Phase Head Per Station

(m)

Head per Station

(ft)

Working Pressure

(psi)

𝑷𝒊 (psi)

t (inches)

T (inches)

T (mm)

A 50 164 71.0 342 0.198 0.358 9.1 B 116 381 164.8 529.6 0.307 0.467 11.9 C 125 410 177.6 555.2 0.322 0.48 12.2

Using Table 3 in (DIPRA, 2001) the values for wall thickness all lie beneath pressure class 250 for a 48inch pipe aboveground but Phase B will be constructed below ground and therefore requires the pipe to have a pressure class of 300.

19.12.4 Pressure Class due to Flexural Stress at Centre of Span Assume a pressure class of 250 and a 48-inch pipe

𝑓𝑏 =15.28𝐷𝑤𝐿2

𝐷4 − 𝑑4 =15.28 ∗ 49 ∗ 1099 ∗ 202

494 − 48.164 = 854𝑝𝑠𝑖 = 5.89𝑀𝑃𝑎

𝐷 = 𝑃𝑖𝑝𝑒 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 (𝑖𝑛𝑐ℎ𝑒𝑠)

𝑤 = 𝑈𝑛𝑖𝑡 𝑙𝑜𝑎𝑑 𝑝𝑒𝑟 𝑓𝑜𝑜𝑡 (𝑙𝑏𝑓𝑡

)

𝐿 = 𝐿𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑠𝑝𝑎𝑛 (𝑓𝑒𝑒𝑡) 𝑑 = 𝐷 − 2𝑡𝑛 = 48.66 − (2 ∗ 0.3) = 48.06𝑖𝑛𝑐ℎ𝑒𝑠

𝑓𝑏 < 331𝑀𝑃𝑎 therefore this pressure class is sufficient.

182

19.12.5 Deflection at Midspan Assume a pressure class of 250 and 48-inch pipe The maximum allowable deflection at midspan to prevent damage to the DIP lining is calculated with:

𝑦𝑟 =𝐿

10=

2010

= 2𝑖𝑛𝑐ℎ𝑒𝑠 = 50.8𝑚𝑚 The calculated flexural deflection at midspan however is:

𝑦 =458.4𝑤𝐿4

𝐸(𝐷4 − 𝑑4) =458.4 ∗ 1148 ∗ 204

𝐸(494 − 48.164)= 0.00911𝑖𝑛𝑐ℎ = 0.231𝑚𝑚

𝐸 = 24𝑥106𝑝𝑠𝑖 0.231𝑚𝑚 < 50.8𝑚𝑚 therefore, pressure class is sufficient.

19.12.6 Recalculated Saddle Width Assume a pressure class of 250 for a 48-inch diameter pipe.

𝑏 = √2𝐷𝑡𝑒 = √2 ∗ 49 ∗ 0.58 = 7.54𝑖𝑛𝑐ℎ𝑒𝑠 = 0.192𝑚

𝑏 = 𝑚𝑖𝑛𝑖𝑚𝑢𝑚 𝑠𝑎𝑑𝑑𝑙𝑒 𝑤𝑖𝑑𝑡ℎ (𝑖𝑛𝑐ℎ𝑒𝑠) 𝐷 = 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟 𝑜𝑓 𝑝𝑖𝑝𝑒 (𝑖𝑛𝑐ℎ𝑒𝑠)

𝑡𝑒 = 𝑛𝑜𝑚𝑖𝑛𝑎𝑙 𝑝𝑖𝑝𝑒 𝑤𝑎𝑙𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 (𝑖𝑛𝑐ℎ𝑒𝑠) = 0.58𝑖𝑛𝑐ℎ𝑒𝑠 𝑡𝑒 taken from Table 1 for a 48-inch pipe with pressure rating 250 aboveground (DIPRA,2001).

19.12.7 Conclusion The leading design condition is “Pressure Class Due to Internal Hoop Stress” as this condition requires the highest pressure class. Saddle width has therefore been designed for the pressure class required by this design condition. “Pressure Class due to Localised Stress at the Supports” could be repeated with this new pressure class but it is clear that it will not exceed the maximum value of 48,000psi. Phase A & C require a pressure class of 250 according to (Table 3 in DIPRA, 2001) and a corresponding thickness of 13mm

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19.13 Underground Pipe Dimension Design The only underground phase of the route is the length of Phase B. Underground pipe design follows the same procedure as above except disregarding the sections about supports as it assumed the pipe is supported along it’s whole length by fill. Internal hoop stress remains the same for Phase B as calculated in Table 62. Table 62 – Calculation of 𝑃𝑖 and t

Phase Head Per Station

(m)

Head per Station

(ft)

Working Pressure

(psi)

𝑷𝒊 (psi)

t (inches)

T (inches)

T (mm)

A 50 164 71.0 342 0.198 0.358 9.1 B 116 381 164.8 529.6 0.307 0.467 11.9 C 125 410 177.6 555.2 0.322 0.48 12.2

Phase B requires a pressure class of 300 according to (Table 3 in DIPRA, 2001) and a corresponding thickness of 12mm

19.14 Valves

19.14.1 Wash Out Valves Wash out valves principle use are for emptying stagnant or dirty water (Twort et al, 2009). The diameter of the washout valve is based upon the diameter of the main pipeline as displayed in Table 63 Table 63 – Washout branch diameter based on main pipeline diameter. (Twort et al, 2009)

Main Pipeline Diameter (mm) Washout Branch Diameter (mm) Up to 300 80 400 - 600 100

700 - 1000 150 1100 - 1400 200 1500 - 1800 250

A wash out valve should be installed at every low point in every 10km section between the butterfly valves and each wash out valve should discharge by gravity to the nearest watercourse. The discharge should be to a concrete pit with an open overflow to prevent scour from any high velocity discharge (Twort et al, 2009).

19.14.2 Air Valves While a pipeline is in operation air can be introduced either from operational activities in the WTP or poorly designed fittings within the main trunk of the pipeline. Air can collect at high points along a pipeline and interrupt normal flow of water by increasing hydraulic losses (Twort et al, 2009).

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Fig. 141 – Diagram showing how air can collect at high points within a pipeline (Twort et al, 2009) Upon receiving a more detailed map of the area and in particular each phase it is recommend detailed design should begin on limiting the accumulation of air by adding air breaks at the general conditions described in Figure 141.

19.14.3 Stop Valves In the event of pipe failure, the pipe shall be split into segments of 10km. This is to mitigate any losses associated with potential pipe failure. The pipe shall be split by means of butterfly valves. Butterfly valves are commonly specified for pipelines up to 4m in diameter and produce low head loss when fully open (Twort et al, 2009). These valves will operate either fully open or fully closed and therefore minimising the risk of cavitation during normal service.

19.14.4 Surge Protection by Limiting Valve Closure In Section 19.12.3, a 100psi or 70m allowance was given to take into account surge protection. This is the minimum value described by standards as detailed in the calculation. The decided method of surge protection is by mechanical means and therefore the time of closure (Tc) of any valve in the event of an emergency should be controlled.

∆𝐻 = −𝑐∆𝑉

𝑔

∆𝐻 = 𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 ℎ𝑒𝑎𝑑 𝑐 = 𝐶𝑒𝑙𝑒𝑟𝑖𝑡𝑦 𝑖𝑛 𝐷𝐼𝑃 ≈ 900𝑚/𝑠

∆𝑉 = 𝐶ℎ𝑎𝑛𝑔𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑖𝑛 𝑡ℎ𝑒 𝑝𝑖𝑝𝑒𝑙𝑖𝑛𝑒 = 1.4𝑚/𝑠 If immediate valve closure occured then ∆𝐻 =128.4m. This is larger than the 70m allowance made in the wall thickness calculations and therefore Tc must be increased.

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The relationship of ∆𝐻 to Tc is roughly proportional to ( 1𝑇𝑐

)1.5

(Twort et al, 2009) and therefore using this and the value of 128.4m a sufficient Tc can be calculated.

70 = 128.4 ∗ (1𝑇𝑐

)1.5

𝑇𝑐 = (√ 70128.4

3)

−2

= 1.498 = 1.5𝑠𝑒𝑐𝑜𝑛𝑑𝑠

However, to increase safety it is recommended a safety factor of 2 is used and the final Tc should be 3seconds.

19.15 Pipe Material and Encasement

19.15.1 Pipe Material After carrying out initial research into the feasibility of four pipe material options, it is decided that a ductile iron pipe would be the most suitable material option. Due to the remote nature of the project, a compromise must be struck between robustness, ease of construction and weight. Due to its strength, standard fittings, relative (compared to concrete) lightness and ability to be constructed easily by the local workforce using push on joints DIP is the most advantageous.

19.15.2 Pipe Encasement

19.15.2.1 Overground Pipe should be painted in light coloured protective paint to help keep the pipe cooled during warm weather.

19.15.2.2 Underground x Polyethylene Encasement

- The two main products are: Liner, low-density polyethylene film and high-density, cross-laminated polyethylene film (National Research Council, 2009).

- According to the ANSI/AWWA standard, PE should be fitted to the pipe in a snug, but not tight, encasement with limited space between the pipe and the encasement (National Research Council, 2009).

- In wet conditions the PE should be taped every 2 feet around the pipe (National Research Council, 2009).

- Tube form of PE encasement is favoured because it speeds up installation whilst minimising the chance that accidental contamination may occur by something being trapped between the PE and pipe (National Research Council, 2009).

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- PE can degrade over time although through experiments done by The Bureau of Reclamation this degradation has been proven to be minimal and in fact showed that PE is highly resistant to bacteriological deterioration (National Research Council, 2009).

19.15.3 Pipe Lining It is important to consider the effect of corrosion over the lifespan of the pipeline. Corrosion will increase the internal friction and in return reduce the efficiency of the system therefore a lining has been designed to extend the pipelines life. There are two main choices for lining of DIP and both require a slight increase in diameter to maintain the nominal diameter used in flow calculations. This has been accounted for in all calculations throughout the report. x Spun-Concrete or Cement-Mortar Internal Lining

- Spun-concrete generates a high pH environment which passivates and prevents corrosion (Twort et al, 2000).

- Spun-concrete is slightly thicker – usually 25mm over 12mm thus producing a more robust and durable surface (Twort et al, 2000).

- Concrete lining should be sealed with a thin layer of epoxy paint for diameters less than DN 800 (Twort et al, 2000).

- The layer of concrete requires a slight increase in pipe diameter to maintain designed values (Twort et al, 2000).

- Tends to have a greater roughness value than epoxy therefore can be a more expensive solution if energy costs are taken into account (Twort et al, 2000).

- The approval process for material in contact with water is time consuming and often costly involving continued controlled assessment of the production process (Twort et al, 2000).

- For DIP a spun-concrete internal lining is the most easily applied in remote locations with a labour force of unknown skill. It also offers increased robustness over cement mortar lined pipes whilst maintaining cleanliness of the water.

Fig. 142 – Recommended thickness of cement-mortar linings in DIP (TWORT et al, 2000) Pipe Lining: 19mm thickness, Spun Concrete

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20. Over-ground Pipeline Crossing Crossings required = 210 Concrete volume needed per crossing = (4×3.9×0.3)+(2×8×3.9) ≈ 70m3 ∴ Total concrete required = (70×210) = 14,700m3 Volume of earth to be excavated per crossing = (2×2×8) = 32m3 Volume of earth required for ramp per crossing = (8×12×2) = 192m3 ∴ Extra earth required per crossing = (192−32) = 160m3 ∴ Total extra earth required = (160×210) = 33,600m3 Volume of earth excavated for 45km underground pipe:

𝑉 =𝜋𝐷𝑝𝑖𝑝𝑒

2

4𝐿𝑝𝑖𝑝𝑒

∴ Volume of earth excavated for underground pipe ≈ 60,000m3 Excess earth = (60,000−33,600) = 26,400m3 This extra earth will be used for landscaping around the over-ground pipeline to naturally guide wildlife towards the crossing points.

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21. Bridge loading

21.1 Pipe self-weight Ductile Iron pipe Iron density, ρ = 7850kg/m3 (The Engineering Toolbox, 2015) Pipe internal diameter, Di = 1200mm Pipe thickness, t = 13mm Pipe loading per meter, wpipe:

𝑤𝑝𝑖𝑝𝑒 = 𝜌𝑔 ((𝜋(2𝑡 + 𝐷𝑖)2

4) − (

𝜋𝐷𝑖2

4))

∴ wpipe ≈ 4kN/m

21.2 Water loading Pipe internal diameter, Di = 1200mm Density of water, ρw = 1000kg/m3 Water loading per meter, wwater:

𝑤𝑤𝑎𝑡𝑒𝑟 = 𝜌𝑤𝑔 (𝜋𝐷𝑖

2

4)

∴ wwater ≈ 11kN/m

21.3 Bridge deck self-weight The bridge deck will have 1-meter width walkways on either side of the pipeline to provide access for maintenance. The material used for this will be ‘Safegrid’ steel grating. This is a lightweight and strong option and has become the industry standard for steel open mesh flooring (Lionweld Kennedy, 2015). Being a grate reduces the wind loading on the walkway – wind loading on the deck is therefore deemed negligible. While the deck will not receive regular footfall, the grating chosen is category B (general duty) meaning the grating is suitable for workers and heavier maintenance equipment to be used (Lionweld Kennedy, 2015). Mesh chosen:

- Safegrid mesh - Mesh size = NX (50mm/20mm) - 30mm depth - General duty

Total width of steel grate flooring = 2m Mass of steel grate flooring per area = 30kg/m2

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∴ Mass of steel grate flooring per meter length = 60kg/m (Lionweld Kennedy, 2015).

∴ Steel grate floor loading per meter, wflooring ≈ 0.6kN/m

21.4 Railing self-weight Railings will be fixed to either side of the deck to protect maintenance workers from falling from the bridge. The railing chosen is an ‘offshore barrier rail’. This is a strong, durable and safe option. Railing height = 1100mm (Lionweld Kennedy, 2015). Railing mass per meter = 10kg/m (Lionweld Kennedy, 2015). ∴ Railing loading per meter, wrailing ≈ 0.1kN/m

21.5 Wind loading Design wind speed = 100mph ≈ 160km/hr Minimum lateral loading, per meter, for an open bridge system (as is the case for the cable stayed and truss bridges, wwind:

𝑤𝑤𝑖𝑛𝑑 = 75𝐷𝑒

Where De = External pipe diameter =1226mm ≈1.3m ∴ wwind ≈ 1kN/m

21.6 Other loading Thrust forces in the pipe will be limited, as the pipeline will not change direction or have bends while crossing the bridges. This is deemed negligible and will be covered by a safety factor on the design load. Water hammer forces result from sudden changes in pressure in the pipe. Sudden pressure changes will be limited by the control systems. This is therefore deemed negligible and will be covered by a safety factor on the design load. Earthquakes can induce lateral forces in the bridge and pipeline. The pipe will be adequately secured to ensure it does not slip off its supports during earthquakes. Pipeline should be able to resist 0.5g in any direction (Gugino et al., 1996). This will be ensured.

190

Thermal expansion forces will induce longitudinal forces in the pipeline and will affect the pipe supports and hangers. These will be adequately designed to account for thermal expansion changes in the pipeline. The self weight of the pipe hangers is deemed negligible, due to their infrequency on the bridge – their weight will be covered by the safety factor. A safety factor will be applied to account for all other loading and to add ensure the bridge is adequately resilient to any applied loading combinations. Safety factor, K= 2.5

21.7 Total distributed loading wT = K(wpipe + wwater + wfloor + wrailing + wwind) = 2.5(4+11+0.6+0.1+1) ∴ wT ≈ 40kN/m The self weight of the actual bridge structure will be considered during the detailed design of each bridge.

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22. Bhima River Crossing – Truss Bridge Design The bridge loading calculated in appendix 21 was used to initially calculate the forces in the truss members and find appropriate sizes for the members. wT = 40kN/m The truss form chosen is a ‘deck truss’ where the pipeline will cross on top of the truss structure, as opposed to through it – this minimises the obstruction of truss members to construction and maintenance workers. Two truss spans will be connected by cross members. Therefore the distributed load will be divided in two and distributed to each truss span. ∴ w = 20kN/m on each truss span The total truss span will be 27m, with nodes every 3 m. The depth of the truss will be 1.5m. The angle between truss members will be 45°. Therefore the number of truss members per span will be 35. Connecting members will connect the truss spans at each node, meaning 19 truss members will be used (of length 3.4m). Using the 20kN/m distributed load, the initial required size of the members was determined by finding the maximum force in the members. The same cross section of steel will be used for all members, despite the members closer to the supports having a smaller load. Once the initial size of the members was determined, a self-weight of the bridge was calculated and added to the distributed load. Number of short (2.12m) members per truss = 18 Number of long (3m) members per truss = 17 Number of truss spans = 2 ∴ Total length of truss members = [((2.12*18)+(3*17))*2] ≈ 178m Number of connecting members = 19 Length of connecting members = 3.4m ∴ Total length of connecting members ≈ 65m ∴ Total length of members = 243m Cross sectional area of members = 0.01m2 ∴ Total volume of steel = 2.43m3 Density of steel = 7850kg/m3 ∴ Weight of steel = 187kN ∴ Distributed self-weight of steel = 7kN/m

192

This was added to the distributed load on the truss and the forces were recalculated and the member size checked. The strength of the original 0.1m×0.1m section was still strong enough for the additional weight. Table 64 shows the forces in each member and their required area of steel. Table 64 – Forces in each truss member

Member Force (kN) Tension or Compression

Area required

(m2)

Required thickness

of member (m)

Length of member

(m)

F1 407 T 0.0020 0.045 2.12 F2 -288 C 0.0014 0.037 3.00 F3 -407 C 0.0020 0.045 2.12 F4 576 T 0.0028 0.053 3.00 F5 305 T 0.0015 0.039 2.12 F6 -792 C 0.0039 0.062 3.00 F7 -305 C 0.0015 0.039 2.12 F8 1008 T 0.0049 0.070 3.00 F9 204 T 0.0010 0.032 2.12

F10 -1152 C 0.0056 0.075 3.00 F11 -204 C 0.0010 0.032 2.12 F12 1296 T 0.0063 0.080 3.00 F13 102 T 0.0005 0.022 2.12 F14 -1368 C 0.0067 0.082 3.00 F15 -102 C 0.0005 0.022 2.12 F16 1440 T 0.0070 0.084 3.00 F17 0 T 0.0000 0.000 2.12 F18 -1440 C 0.0070 0.084 3.00 F19 0 T 0.0000 0.000 2.12 F20 1440 T 0.0070 0.084 3.00 F21 -102 C 0.0005 0.022 2.12 F22 -1368 C 0.0067 0.082 3.00 F23 102 T 0.0005 0.022 2.12 F24 1296 T 0.0063 0.080 3.00 F25 -204 C 0.0010 0.032 2.12 F26 -1152 C 0.0056 0.075 3.00 F27 204 T 0.0010 0.032 2.12 F28 1008 T 0.0049 0.070 3.00 F29 -305 C 0.0015 0.039 2.12 F30 -792 C 0.0039 0.062 3.00 F31 305 T 0.0015 0.039 2.12 F32 576 T 0.0028 0.053 3.00 F33 -407 C 0.0020 0.045 2.12 F34 -288 C 0.0014 0.037 3.00 F35 407 T 0.0020 0.045 2.12

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Fig. 143 – Truss member labels From table 64 as the maximum thickness of steel required is 0.084m, a square steel section of 0.1m×0.1m has been chosen for each truss member. ∴ Total volume of steel required = 2.43m3 A 1m-wide walkway on either side of the pipeline will be built to allow access for construction and maintenance of the pipeline. This will be made of steel grating. To protect maintenance workers, a 1100mm high railing will be added to either side of the bridge deck. This will be fixed to the top horizontal truss members. Steel pipeline supports will be attached to the connecting truss members every 6m. These will be the same size as the over-ground pipeline supports, but will be made of hollow steel to make attaching them to the truss structure easier than a concrete support. A 2.5m high fence and gate at either end of the bridge will prevent unauthorised people from accessing the bridge. Concrete abutments will be constructed on either side of the river to support the truss bridge. Pin and roller supports will be used on either side of the bridge. The earth near the river is exposed hard granite bedrock and is assumed to be strong enough to adequately support the truss bridge.

194

23. Arkavathi River Crossing – Cable-Stayed Bridge Design 23.1 Initial Design Proposal Figures 144 and 145 show sketches of the initial proposed design of the cable-stayed bridge. The 250m-span bridge will have two towers at either end of the river, with two columns for each tower – meaning half of the bridge loading will be split evenly between each side and each tower column.

Fig. 144 – Initial perspective sketch of bridge form

Fig. 145 – Initial side elevation sketch of bridge form The cables will be spaced evenly along the deck and tower and will be set at the same angle.

23.2 Bridge loading The bridge loading calculated in appendix 21 was used to initially calculate the forces in the truss members and find appropriate sizes for the members. wT = 40kN/m

195

The total distributed load will be split between each side of the bridge and carried by the respective set of cables and tower columns. ∴ w = (wT ÷ 2) = 20kN/m A factor of 1.5 was applied to account for the additional self-weight loading. ∴ w = (20×1.5) = 30kN/m

23.3 Bridge form Assumed tower height, Ht = 50m Cables per tower column, c = 16 ∴ Total cables used = 64 ∴ Cable spacing on deck, sd = 14.7m ∴ Cable spacing on tower, st = 6.25m Cable angle, θ = 23°

23.4 Reactions in members Deck sagging moment,

𝑀𝑠𝑎𝑔 =𝑤𝑇𝑠𝑑

2

8

∴ Msag = 1620kNm Tension in cables,

𝑇 =𝑤𝑠𝑑

𝑆𝑖𝑛𝜃

∴ T = 1130kN Axial force in deck,

𝐷 =𝑐𝑇𝐶𝑜𝑠𝜃

2

∴ D = 8300kN Force in Tower, N

𝑁 = 𝑐𝑇𝑆𝑖𝑛𝜃 ∴ N =7060kN

23.5 Size of steel cables From the tension force in the cables, the required cable cross-sectional area can be calculated. Steel, with a tensile strength of fy=205MPa will be used. (The Engineering Toolbox, 2015)

196

𝐴𝑠 =𝑇𝑓𝑦

∴ As = 0.0055m2 A cable of a diameter in excess of the required will be chosen. ∴ Diameter of steel cable, Ds= 90mm

23.6 Size of Bridge Deck Steel beams will be used to support the bridge deck between the cables. To calculate the number of steel beams and their size, an iterative design process was performed. The final iteration is outlined below. The self-weight of the beams were added to the applied distributed loading, after an initial calculation. Number of beams in deck = 3 Beam section: 914x305x224 Area of section = 13107.96mm2 Total beam area = 0.039m2 Density of steel = 7850kg/m3 (The Engineering Toolbox, 2015) ∴ Self-weight distributed load = 3kN/m (Must be divided to each side of the bridge) ∴ New distributed load per side of the bridge ≈ 32kN/m ∴ New deck sagging moment, Msag = 1620kNm ∴ Axial force in deck, D = 8300kN Beam Section: 914x305x224

D = 910.4mm B = 304.1mm d = 824.4mm t = 15.9mm T = 23.9mm b = 152mm

Fig. 146 – Drawing of beam section chosen

197

Sagging moment in each beam = 570kNm Section moment capacity = 1900kNm The deck is therefore adequately resilient to any applied loading combinations.

23.7 Size of Tower The tower will be constructed of square reinforced concrete columns. The design of the tower was an iterative process and the final chosen section is detailed below. The self-weight of the concrete tower was added to the applied load, N, on the tower. Height of tower = 50m Width of concrete section = 0.8m Area of concrete column = 0.64m2 Volume of concrete used in each column = 32m3 Density of concrete = 2240kg/m3 ∴ Self-weight of concrete = 72kN ∴ Total force on column = (72+7060) = 7132kN Number of steel reinforcement bars used = 8 Diameter of steel reinforcement bars = 40mm Area of steel reinforcement = 320mm Concrete section capacity, P:

𝑃 = 0.4𝐹𝑐𝐴𝑐 + 0.67𝐹𝑦𝐴𝑠 ∴ P = 10374kN Induced load = 7132kN The tower is therefore adequately resilient to any applied loading combinations.

198

24. Under-road Pipeline Tunnelling Fig. 147 MictoTunelling Microtunneling is a trenchless technology, which has significant benefits which include: Economic

- The Volume of earth moving work lessened by around 80%, resulting in reduced costs in: machine hire, fuel and labour.

- There are none of the costs involved in a traditional road crossing operation, which involves the construction of a temporary road so that an open excavation can be carried out through the existing road. Thus there are no costs from: paying compensation from paying a local authority for access to the existing road; digging up and restoring the existing road; or construction of a temporary road.

- The volume of excavated soil that needs to be transported is significantly less, saving time and costs. Moreover, there is no need for bedding material, also saving time and money.

Social - Microtunneling has minimal disturbance to the surface meaning that

lesser impact on flow of traffic on the existing road. Construction

- The minimal impact on the overlying road is also of particular importance to the project as a whole due to the fact that the construction of the city of Sandalwood coincides with the installation of the water pipeline. Therefore, it will be vital that there are minimal disturbances to traffic on the road so not to delay deliveries, workers etc.

- Excavating in an area such as this would be difficult due to the high water table (specially in the Monsoon season). However, this is not an issue for the Microtunneling technique.

199

24.0.1 Soil Testing Due to little being known about the type and quality of the soil, the worst case scenario for Micro-tunnelling should be assumed. The soil is therefore assumed to be non-cohesive and unstable due to high water content (probable in the monsoon season). This instability is likely to be the result of micro-tunnelling/ pipe jacking causing excessive water movement in the soil. Therefore dewatering, stabilisation and face support facilities will be required when micro-tunnelling. Additionally the most appropriate shield (tunnel machine) for such circumstances is a Tunnel Boring Machine (TBM).

24.0.2 Set-up: An initial survey will need to be conducted by independent surveyors. However, survey stations will also be checked regularly during tunnelling to ensure that the jacking frame does not settle under weight of pipes and shield – as this could offset the TBM when the hydraulic jack is operational. Furthermore, the thrust wall, hydraulic jacks and shield alignment will also be regularly checked to ensure the TBM is correctly aligned prior to excavation starting. Other important checks that will be carried out include: ensuring the laser (alignment control system) is firmly fixed to the shield (this is used to guide the TBM to the receiving shaft, thus correct alignment of such a device is vital) Accurate set-up is also necessary to ensuring that the line and level of the pipe are correct (particularly due to the fact that there is little margin for error, as there is a road above and granite below). Shield entry will also need to be slow and carefully controlled, with regular checks conducted to ensure pipe is on the correct course. However, the TBM shield does have a steerable head – enabling the direction of the tunnel to be adjusted if it is knocked off course by a boulder or the granite bedrock – regular small corrections prevent large angular deflections of the pipe joints.

24.1 Additional Checks:

24.1.1 Surface Checks Ensure the condition of the road and haunching is not compromised at regular intervals.

200

24.1.2 Shield and Jacking load checks This will reduce the probability of the shield stalling due to excessive friction loads.

24.1.3 Manufacturer Ensure the manufacturer of steel pipe casing (pipejack) has sufficient stock prior to micro-tunnelling commencing

24.1.4 Micro-tunnelling Subcontractor Ensure that the micro-tunnelling sub-contractor has availability of equipment to conduct the works and sticks to the agreed time schedule

24.2 Working Shaft: The Working Shaft will be excavated prior to Micro-tunnelling works starting. This will initially be a vertical sided shaft, supported by sheet piles on the 3 sides other than that facing the direction of the soon to be tunnel. However, once the micro-tunnelling procedure has been completed, the rear wall will be excavated back to an open/ battered wide excavation to improve health and safety for maintenance workers, and also to create a gentle slope for the pipeline to meet the micro-tunnelled section. The working shaft must be large enough to hold:

- Shield (Tunnel Boring Machine) - Jacking equipment - Thrust wall - Pipe jack eye – allow safe entry and exit of the shield - Facility for removing soil (Slurry machine) - Space for lowering section of pipe - Space for jointing the pipes

24.3 Thrust Wall In accordance with the pipe jacking design guide, the Thrust Wall is to be a temporary structure constructed out of reinforced concrete at the bottom of the working shaft. This is to minimise the risk of punching shear. It is used to provide a reaction force for the hydraulic jack when driving the TBM and pipes. The thrust wall should be equipped with an adequate back spreader to distribute the load between the thrust wall and the thrust jacks. The strength of the thrust wall must be adequate to ensuring that the micro-tunnelling procedure is conducted properly and without delays

24.4 Hydraulic Jack: The Hydraulic Jack sits on a rail system at the bottom of the working shaft.

201

The Thrust load is produced by the Hydraulic Jack to drive the shield and the pipe casing (pipe jack) through the soil

Thrust force is transferred to the temporary thrust wall via distributor plates. The Hydraulic Jacks will have a control system to ensure that the speed and load being applied is restricted and carefully applied to prevent the pipes from being damaged. The Load will be transferred from the Hydraulic Jacks to both the Pipe Casing and the DIP via a Thrust ring to further ensure even pressure distribution so that the pipes are not damaged.

24.5 Shield (Tunnel Machine) Selection

24.5.1 Tunnel Boring Machine (TBM) As previously mentioned, the most appropriate shield, given the lack of knowledge on the soil conditions, is the Tunnel Boring Machine (TBM) The purpose of the tunnel-boring machine is to create the tunnel for which the pipe casing, and water pipe can then be driven through. The Hydraulic Jack drives the tunnel-boring machine through the soil. This is the most common type of shield mechanical face for Micro-tunnelling, and will need to be used in conjunction with a ‘Slurry machine’ Fig. 148 Tunnel Boring Machine

24.6 Slurry Machine In accordance with the pipe jacking design guide, a slurry machine is required at the face of the tunnel. The slurry machine is has two main purposes: to balance the ground water pressure at the face and to transport the soil excavated at the face of the tunnel to the surface (by means of mixing it with slurry). The slurry should also be used in conjunction with a non-aqueous lubricant, in order to minimise friction on the TMB and pipes from the surrounding soil when being pushed through by the Hydraulic Jacks.

202

24.7 Pipes

24.7.1 Pipe Casing The Pipe Casing will be made of steel, and will be strong enough to be used as both a jacking pipe (driven through the soil, behind the TBM, by the hydraulic jack; and strong enough to protect the water pipeline from forces exerted through the existing road by vehicles passing above. Internal Diameter = 1234mm Thickness = 25mm

24.7.2 Internal Ductile Iron Water Pipe Once the Pipe Casing has been fully installed; the Internal DIP will be gently pushed through the Steel Pipe Casing until reaching the receiving shaft. Internal Diameter = 1200mm Thickness = 12mm

24.7.3 Support facilities required on site: - Crane for lifting the following:

o Shield o Pipes o Ancillary equipment

- Storage facility:

o Pipes o Other materials/ equipment

- Muck Handling facilities

o Skips o Slurry disposal o Temporary storage for: displaced soil from tunnel/ wide excavation

- Lubrication

o Mixing o Injection plant

- Services

o Electricity � Welfare facilities � Equipment � Lighting at night (if work is to be conducted overnight)

o Water supply � Welfare facilities � Equipment

- Control Station

o Where shield can be remotely controlled from

203

- General store

o Tools o Fuel

- Welfare Facility

o Site Office o Canteen o Drying Room o Toilets

204

25. Service Reservoir Design 25.1 To determine the Service Reservoir Capacity Water demand = 1.15m3s-1 Client condition:

- The service reservoirs must have the capacity to store 24 hours worth of demand, to allow for maintenance and repairs of the water treatment and conveyance infrastructure.

∴ Total required capacity = (1.15×3600×24) ≈ 100,000m3 Chosen number of tanks = 4 tanks (As per options report) ∴ Capacity per tank = 100,000 ÷ 4 = 25,000m3 As per BS EN-14015-2004 section 9.1.3, each tank must be able to store an additional 10% of the required water volume. ∴ Recommended Tank capacity, C = (25,000×1.1) = 27,500m3

25.2 To determine the Service Reservoir Tank Dimensions Chosen tank form = Cylindrical

∴ 𝐶 = 𝐻𝑐 ×𝜋𝐷2

4

Tank capacity, C = 27,500m3 Let tank diameter, D = 60m Rearranging the equation to find height of tank, Hc

𝐻𝑐 =4𝐶

𝜋𝐷2 ∴ Hc = 9.7m ∴ Let Hc = 10m However, a 1m clearance (freeboard) will be allowed above the ideal water level, making the recommended internal tank height 11m in total. This will prevent the contained water touching the top of the tank and inducing additional stresses on the tank roof. A control system will be used to ensure the water level remains at approximately 10m. ∴ Normal volume of water stored (at 10m depth) = 28,274m3

205

∴ Actual capacity of whole tank (at 11m depth) = 31,102m3 However, internal baffle blocks will take up additional capacity.

25.3 Designing the Tank Structure NOTE:

- After consultation with Dr Ahmad Mejbas Al-Remal, the tank material has been altered from pre-stressed concrete (as per the options report) to steel. A steel design is more economical and improves ease of construction.

25.3.1 Determining the wall thickness of the tank The design of the wall thickness is done according to BS EN-14015-2004 section 9.2.2. Wall thickness, ec:

𝑒𝑐 =𝐷

20𝑆{98𝑊(𝐻𝑐 − 0.3) + 𝑝} + 𝑐

Fig. 149 – Service Reservoir Tank sketch The tank is split into four sections – the upper course (made of 2x2m square steel sheets) and three lower courses (made of 3x3m square steel sheets). The depth of the upper and lower courses is 2m and 9m respectively. The equation above was used to calculate the wall thickness for the upper and lower course of the tank. This calculation is presented in Table 65.

Diameter = 60m

Tota

l hei

ght =

11m

Upper course = 2m (2x2m square sheets)

Lower courses = 9m (3x3m square sheets)

206

Table 65 – Calculation of wall thickness for lower and upper course of tank

Lower Course Upper Course

Course 1 Course 2 Course 3 Course 4 D Tank Diameter (m) 60 60 60 60 S Allowable Design Stress (N/mm2) 230 230 230 230

W Max Design Density of contained liquid (kg/l) 1 1 1 1

Hc Height of tank wall

(bottom of course to top of shell)

(m) 11 11 5 2

p Design Pressure (mbar) - - - - c Corrosion Allowance (mm) - - - -

ec Design Shell Thickness (mm) 13.7 13.7 6.0 2.2

ecr Recommended Shell Thickness (mm) 15 15 10 5

Assumptions: - The tank is filled to the top of the 11m shell (BS EN-14015-2004, Section 9.2.1) - Yield strength of steel = 345N/mm2 - Allowable Design Stress, S = 2/3 of Yield Strength = 230N/mm2 (BS EN-14015-

2004, Section 9.1.1) - Design Pressure is negligible for tanks with a design pressure < 10mbar (BS

EN-14015-2004, Section 9.2.2)

Fig. 150 – Cross section of tank wall showing thickness

2m

3m

3m

3m

Thickness = 5mm

Thickness = 10mm

Thickness = 15mm

Thickness = 15mm

207

25.3.2 Shell Plate Arrangement Fig. 151 shows the recommended steel plate arrangement for the tanks.

Fig. 151 – Steel plate arrangement guidance (BS EN-14015-2004 section 9.1.8) According to BS EN-14015-2004 section 9.1.8, the minimum distance between vertical joints in adjacent courses (amin) for a wall thickness greater than 5mm must be at least 300mm. According to BS EN-14015-2004 section 9.1.8, the minimum circumferential plate dimension (b) must be at least 1m. Fig. 152 shows the designed steel plate arrangement for the tanks.

Fig. 152 – Steel plate arrangement

3m 3m 3m

3m

3m

3m

2m

2m

1.5m 1.5m 1.5m

2.5m

0.5m

208

25.4.2.1 Connections between wall plates In accordance with BS EN 14015-2004 Section 8, Table 14: The Tank Wall Plates in courses 1,2 and 3 of the Tank wall must be connected to each other with Fillet Welds with a throat thinness of 6mm. This is due to the Tank Wall Plate thicknesses of these courses being greater than 5mm. The Tank Wall Plates in course 4 of the Tank wall must be connected to each other with Fillet Welds with a throat thinness of 4.5mm. This is due to the Tank Wall Plate thicknesses of these courses being equal to 5mm. Fig. 153 Fillet weld throat thickness

25.3.3 Stiffening Ring Design Stiffening rings (also known as wind girders) support the reservoir tank walls when subject to wind loading or negative pressures in the tank. A primary stiffening ring is not required, due to the tank having a fixed roof. However, a top corner ring will be used instead. However, a secondary ring will be needed, to ensure the roundness of the entire shell is preserved and that local buckling is prevented in the event of wind loading or negative pressure.

25.4.4.1 Secondary Stiffening ring

Location The secondary stiffening ring will be located 1m from the top of the tank shell wall.

Stiffening ring size The minimum size of an angle (bar), with its sole use as a stiffening ring, will be 200mm x 100mm x 12mm, as the diameter of the tank is greater than 48m (BS-EN 14015-2004, Section 9.3, Table 17). However, the stiffness ring will have dimensions 200mm x 150mm x 15mm, due to the larger 60m diameter.

209

Fig. 153 – Side elevation detail of stiffening ring on tank

25.4.4.2 Top Corner Stiffening ring

Location The top corner-stiffening ring will be located on top of the tank wall.

Stiffening ring size In accordance with BS EN 14015-2004, Section 10.5.6, for a tank with a diameter of greater than 48m, the minimum size of Top Corner Ring is: 150mm x 150mm x 12mm Therefore, for the tank with a 60m diameter, the recommended size of Top Corner Ring is: 180mm x 180mm x 15mm

25.4.4.3 Connections End to end joints between adjacent parts of the stiffening ring will have a full penetration butt weld connection. However, it is important that the connection only occurs between adjacent parts of the stiffening ring and not the tank wall (BS EN 14015-2004, Section 16.7.6). In accordance with BS EN 14015-2004, Section 9.3, the stiffening ring will be fixed to the tank wall with a continuous fillet weld.

200mm

150m

m

15mm

TAN

K W

ALL

Fillet weld

Fillet weld

210

Fig. 154. Dome Design

25.4.4.3 Roof (In accordance with BS EN 14015-2004, Section 10)

25.4.4.3.1 Roof type Self-supporting spherical dome structure, comprising of lapped thin steel plates supported by an arrangement of primary beams (ribs) and secondary beams (purlins).

25.4.4.3.2 Radius of curvature of the spherical dome The radius of curvature must be a product of 1.5 times the diameter of the tank to conform with BS EN 14015-2004 Section 10. Therefore, the Radius of Curvature = 60m*1.5 = 90m

25.4.4.3.3 Height of spherical dome Use equation of circle: (x-a)2 + (y-b)2 = R2 [1]

Sub into [1]:

Centre of Circle = (a,b) = (30,b)

Radius of Curvature = 1.5*Diameter of Service Reservoir = 1.5*60 = 90m

(x-30)2 + (y-b)2 = 902 [2]

Solve for ‘b’: Sub Point (0,0) into [2] b = 84.84m Height of Dome Roof: h = Radius of Curvature – 84.85 = 5.15m

211

25.4.4.3.4 Slope Due to the height of the spherical dome being 5.15m, the slope of the roof (at the ‘roof – tank wall’ connection) is equal to 9.74 °

25.4.4.3.5 Loading

Internal Pressure Loading The Internal Pressure can be deemed to be equal to 0mbar in accordance with BS EN 14015-2004, Section 9.3, Table 3.

Temperature Loading It is assumed that the tank will not be subject to temperatures greater than 100°C, therefore loading thermal loads can be neglected.

Dead Load The loading due to the self weight of the roof. This will be calculated in detail when determining the size of the Primary and Secondary Beams.

25.4.4.4 Roof Plates

25.4.4.4.1 Span Due to the roof having spherical dome design, the minimum span of a steel roof plate is 3.25m in accordance with BS EN 14015-2004 Section 10. However, due to the potential for maintenance works to be conducted at a later date (inducing live loading), the recommended minimum span for steel roof plates in the final design is 2m.

25.4.4.4.2 Connections In accordance with BS EN 14015-2004 Section 10:

o The ‘Roof Plate-Top Corner Ring’ connection will be continuously fillet welded.

o The connection between lapped roof plates will also be continuously

fillet welded on both sides to ensure leak tightness. Furthermore, this style of connection ensures a joint efficiency factor, J = 0.5.

25.4.4.4.3 Thickness The minimum thickness of steel roof plates is 5mm according to BS EN 14015-2004 Section 10 However to ensure to ensure that the roof plates are an appropriate thickness in relation to the design of the tank the following must be adhere to:

212

Design for Internal Pressure: In conjunction with BS EN 14015-2004 Section 10:

𝑒𝑝 =𝑝𝑅1

20𝑆𝐽

Where: 𝑅1 = 𝑅𝑎𝑑𝑖𝑢𝑠 = 30𝑚 𝑝𝑒 = 𝐷𝑒𝑠𝑖𝑔𝑛 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 = 0.5𝑘𝑁/𝑚2 𝐸 = 𝑌𝑜𝑢𝑛𝑔𝑠 𝑀𝑜𝑑𝑢𝑙𝑢𝑠 = 2050005𝑁/𝑚𝑚2 𝑒𝑝 = 𝑅𝑜𝑜𝑓 𝑃𝑙𝑎𝑡𝑒 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 (for spherical dome roofs) However, the Internal Pressure can be deemed to be equal to 0mbar in accordance with BS EN 14015-2004, Section 9.3, Table 3. Therefore, the minimum thickness remains equal to 5mm

Design for Buckling: In conjunction with BS EN 14015-2004 Section 10:

𝑒𝑝 = 40𝑅1√10𝑝𝑒

𝐸

Where, 𝑅1 = 𝑅𝑎𝑑𝑖𝑢𝑠 = 30𝑚 𝑝𝑒 = 𝐷𝑒𝑠𝑖𝑔𝑛 𝐼𝑛𝑡𝑒𝑟𝑛𝑎𝑙 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 = 0.5𝑘𝑁/𝑚2 𝐸 = 𝑌𝑜𝑢𝑛𝑔𝑠 𝑀𝑜𝑑𝑢𝑙𝑢𝑠 = 2050005𝑁/𝑚𝑚2 𝑒𝑝 = 𝑅𝑜𝑜𝑓 𝑃𝑙𝑎𝑡𝑒 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 (for spherical dome roofs) Therefore, the roof plate thickness is equal to 6mm

25.4.4.4.4 Arrangement The steel plates will be lapped.

Lapping o Minimum lap = 25mm

Note: Design Stress = 2/3 Plate material yield Stress = 2/3*(345) = 230N/mm2

213

Fig. 155 Roof Plates

Number of Courses of Roof Plates Number of courses of Roof Plates = Span/(Width of roof plates – Minimum lap) = 25.5/ (2 – 0.025) =12.9 =13

25.4.4.5 Secondary Roof Beams (Purlins)

25.4.4.5.1 Arrangement Number of secondary roof beams in one gap = 13 Number of Gaps between Primary roof beams = 23 Total number of secondary roof beams = 23 x 13 = 299

25.4.4.5.2 Loading

Roof Plates (Loading) Thickness of Steel Roof Plates = 6mm Volume of Steel Roof Plating (for entire roof):

V = [𝜋6

× (3𝑅2 + 𝐻2)𝐻] − [𝜋6

× (3𝑟2 + ℎ2)ℎ] Ref: http://mathforum.org/dr.math/faq/formulas/faq.sphere.html Volume of Steel Roof Plating (for entire roof) = 39.99𝑚3 Density of Steel (Grade 50) = 7860kg/𝑚3

H= Height (to outer edge of Dome Roof Plate) h = Height to inner edge of Dome Roof Plate R= Radius (to outer edge of Dome Roof Plate) r = Radius (to inner edge of Dome Roof Plate)

h H

R r

214

Self Weight = 314321.4kg Self Weight = 3083.5kN Area of Dome = 2827.43𝑚2 Number of Secondary Beams = 299 Area of Roof plates acting on 1 secondary beam = 9.46𝑚2 Self Weight/m2 = 1.1kN/𝑚2 Force acting on 1 beam = 10.3kN Max Span of Secondary Beam = 8m Distributed Loading, w(roof plates) = 1.29kN/m

Self Weight of Secondary Beams (Loading) Cross sectional Area of 1 beam = 0.002306m2 Density of Steel (Grade 50) = 7860kg/𝑚3 Self Weight of beam/m = 18.13kg/m Distributed Loading, w(secondary beam self weight) = 0.18kN/m

Total Loading Distributed Loading (Total), w(total) = ∑ 𝑤(𝑟𝑜𝑜𝑓 𝑝𝑙𝑎𝑡𝑒𝑠) + w(secondary beam self weight) = 1.47kN/m Factor of Safety = 2 Distributed Loading, 𝑤𝑇 = 2.93kN/m

Reactions in members Deck sagging moment,

𝑀𝑠𝑎𝑔 =𝑤𝑇𝑠𝑑

2

8

∴ Msag = 46.9kNm

215

Maximum Shear Force Steel beams will be used to support the steel Roof plates. To calculate the number of steel beams and their size, an iterative design process was performed. The final iteration is outlined below. The maximum shear occurs at the mid-span. Design Shear, V

𝑉 =𝑤𝑇𝑠𝑑

2

∴ VEd = 23kN Picking a steel section: Section 178 x 102 x 19

Fig. 156 – Chosen beam section

Shear check Shear area, Av = Web area (=146.8×4.8) = 704.64mm2

𝑉𝑃𝑙,𝑉𝑑 =𝐴𝑣

𝑓𝑦√3

𝛾𝑀0

∴ Shear resistance, VPl,Vd = 140kN > VEd = 23kN ∴ Section is ok for shear

Bending check Shear-moment interaction: VEd ÷ VPl,Vd (=23÷140) = 0.167 <0.5

B=101.2mm

d=146.8mm

r=7.6

D=177.8mm t=4.8mm

T=7.9mm

b=50.6mm

216

∴ Shear-moment interaction is insignificant Design moment, MEd = Msag ÷ Number of beams ∴ MEd = 47kNm Section Class check:

𝜀 =√235

𝑓𝑦

∴ ε = 0.825 For Flange: b/T = 6.41 b/T < 9ε ∴ Class 1 section For Web: d/t = 30.6 d/t < 72ε∴ Class 1 section ∴ Section class is 1 Plastic section modulus, wPl = 171cm3 (From UB sections chart) Moment Resistance, MC,Rd

𝑀𝐶,𝑅𝑑 =𝑤𝑃𝑙𝑓𝑦

𝛾𝑀0

∴ MC,Rd = 59kNm > MEd = 47kNm ∴ Section is ok for moment

Lateral Torsional Buckling As the beams are fully restrained in the compression (top) flange, there is no lateral torsional buckling.

25.4.4.6 Primary Roof Beams (Ribs)

25.4.4.6.1 Arrangement Number of secondary roof beams = 24

25.4.4.6.2 Loading

Roof Plates (Loading) Self Weight = 3083.5kN Area of Dome = 2827.43𝑚2

217

Number of Primary Beams = 24 Area of Roof plates acting on 1 secondary beam = 117.8𝑚2 Self Weight/m2 = 1.1kN/𝑚2 Force acting on 1 beam = 128.48kN Span of Primary beam = 25.5m Distributed Loading, w(roof plates) = 5.04kN/m

Self Weight of Secondary Beams (Loading) Cross sectional Area of 1 beam = 0.002306m2 Average Span = 4m Volume of 1 Secondary Beam = 0.00922𝑚3 Density of Steel (Grade 50) = 7860kg/𝑚3 Self Weight of 1 secondary beam = 72.5kg Self Weight of 1 secondary beam = 0.71kN Number of Secondary beams acting on 1 primary beam = 13 Loading from 13 secondary beams = 9.25kN Span of Primary Beam = 25.5m Distributed Loading), w(secondary beam) = 0.36kN/m

Self Weight of Primary Beams (Loading) Cross sectional Area of 1 beam = 0.0125m2 Density of Steel (Grade 50) = 7860kg/𝑚3 Self Weight of beam/m = 98.25kg/m Distributed Loading, w(primary beam self weight) = 0.96kN/m

Total Loading Distributed Loading (Total), w(total) = ∑ 𝑤(𝑟𝑜𝑜𝑓 𝑝𝑙𝑎𝑡𝑒𝑠) + w(secondary beam) + w(primary beam self weight) = 6.36kN/m

218

Factor of Safety = 2 Distributed Loading, 𝑤𝑇 = 12kN/m

Reactions in members Deck sagging moment,

𝑀𝑠𝑎𝑔 =𝑤𝑇𝑠𝑑

2

8

∴ Msag = 1034.7kNm

Maximum Shear Force Steel beams will be used to support the steel Roof plates. To calculate the number of steel beams and their size, an iterative design process was performed. The final iteration is outlined below. The maximum shear occurs at the mid-span. Design Shear, V

𝑉 =𝑤𝑇𝑠𝑑

2

∴ VEd = 162kN Picking a steel section: Section 610 x 305 x 149

Fig. 157 – Chosen beam section

B=304.8mm

d=540mm

r=16.5

D=612.4mm t=11.8mm

T=19.7mm

b=152.4mm

219

Shear check Shear area, Av = Web area (=540×11.8) = 6372mm2

𝑉𝑃𝑙,𝑉𝑑 =𝐴𝑣

𝑓𝑦√3

𝛾𝑀0

∴ Shear resistance, VPl,Vd = 1269kN > VEd = 162kN ∴ Section is ok for shear

Bending check Shear-moment interaction: VEd ÷ VPl,Vd (=162÷1269) = 0.1279 <0.5 ∴ Shear-moment interaction is insignificant Design moment, MEd = Msag ÷ Number of beams ∴ MEd = 1035kNm Section Class check:

𝜀 =√235

𝑓𝑦

∴ ε = 0.825 For Flange: b/T = 7.736 b/T < 9ε ∴ Class 1 section For Web: d/t = 45.763 d/t < 72ε∴ Class 1 section ∴ Section class is 1 Plastic section modulus, wPl = 4590cm3 (From UB sections chart) Moment Resistance, MC,Rd

𝑀𝐶,𝑅𝑑 =𝑤𝑃𝑙𝑓𝑦

𝛾𝑀0

∴ MC,Rd = 1584kNm > MEd = 1035kNm ∴ Section is ok for moment

Lateral Torsional Buckling As the beams are fully restrained in the compression (top) flange, there is no lateral torsional buckling.

220

25.4 Access (For Maintenance)

25.4.1 Access to the Top Corner Ring Access to the Top Corner Ring will be via an enclosed stairway, to ensure safety.

25.4.2 Top Corner Ring The Top Corner ring will have a wide opening for the stairway to penetrate through, which is possible according to BS EN 14015-2004, Section 9.3, Figure 7. The width of the Top Corner Ring at the top of the enclosed stairway will increase will increase to 1000mm to adhere to design standards. Therefore the Top Corner Ring at this point will be wide enough for maintenance workers to walk on. The outside edge of the Top Corner Ring will have a 1100mm high guardrail in accordance with Approved Document K, to help protect maintenance workers from falling.

25.4.3 Roof Opening Maintenance access to the inside of the Service Reservoir Tank will be via a 700mm diameter circular manhole in a reinforced Steel Roof Plate. The loss of strength in the Steel Roof Plate is compensated by the increase in the cross-sectional area of the plate in which the manhole is cut. This Steel Roof Plate with the manhole cut will therefore be 10mm thick, instead of 6mm thick.

25.5 Foundations Ref: http://www.fgg.uni-lj.si/~/pmoze/ESDEP/master/wg15c/l0100.htm

25.5.1 Location The Service Reservoir Tanks will be constructed on a dry, level site that is easily accessible from the existing road for construction and maintenance machinery.

25.5.2 Requirements Foundation must have adequate strength and stability to ensure that foundation sagging and soil settlement do not occur when subject to the load of the tank structure the contents. The foundation resistance to settlement will be aided by the granite baserock. Therefore, shallow foundations can be considered to be an appropriate option, due to the granite baserock having sufficient bearing capacity.

221

Fig. 158 Foundation Design

25.5.3 Design The foundation design will be a square (75m x 75m) Shallow, Slab Foundation that comprises of a series of layers, as can be seen in the following diagram:

25.5.3.1 Layer 1: A well compacted, chemically inert 200mm thick layer of granular material on top of the granite baserock. This will provide a level surface, that has low compressibility, meaning that there will be negligible settlement from this layer.

25.5.3.2 Layer 2: A stable 150mm thick layer of compacted, permeable, granular material. This will enable drainage through to a pipe – that will ensure there is no build up of water beneath the tank. Thus minimising the risk of failure of the foundations due to excessive rain in the Monsoon season.

25.5.3.3 Layer 3: A 50mm thick layer of lightly compacted, sand-bitumen mix. This will be provide a level surface that is well suited to laying Concrete Slabs.

25.5.3.4 Layer 4 This final layer will comprise of 1m thick un-reinforced concrete slabs. The slab foundation design is possible due to the foundations sitting on granite baserock- that is deemed to have sufficient bearing capacity for the Steel Tanks to be constructed atop. The concrete mix will include ‘Retardant Admixures’ to slow the rate of curing of the concrete due to the high temperatures in this region. Therefore, the concrete will harden at the desired rate, so that the slabs are of adequate strength without cracks.

222

A Ring-Slab style of foundations was initially considered. However, the Tank Bottom has been designed with an Annular Ring (outlined in the next section), meaning there is no need for anchor bolts and thus no need for the Ring-Slab design. The Slab design is also un-reinforced, as mentioned before, in order to minimise shrinkage and cracking. Moreover, the Shallow Slab Foundation is also deemed to be advantageous due to the economic savings and ease of construction.

25.5.4 Excavation of Soil around foundations The slope of the excavation surrounding the Service Reservoir tanks will have a slope of at least 3:1, in accordance with the OSHA Excavation Standards for permanent excavations.

25.5.5 Drainage System Layer 2 of the foundations will have an exit pipe for water inside the permeable foundations to escape from. This will be connected up to a larger drainage system. The Drainage system will be equipped with a series of sump pumps to minimise surface water around the tanks (especially in the Monsoon season). Such a drainage system will be necessary to minimise the risk of corrosion of the steel Service Reservoir Tanks, and will also reduce difficulties and delays in the construction of the tanks in the Monsoon season.

25.5.6 Tolerances:

25.5.6.1 Peripheral Tolerance In accordance with to BS EN 14015-2004 Section 16, around the outer edge (periphery) of the foundations: no two points should have a height difference greater than 24mm; and no two points (5m apart or less) should have a height difference greater than 5mm.

25.5.6.2 Surface Tolerance In accordance with to BS EN 14015-2004 Section 16, as the tank has a diameter greater than 50m, the difference between the design level and the as-built level should not exceed 50mm.

25.6 Tank Bottom (In accordance with BS EN 14015-2004 Section 8)

223

Fig. 159 Tank Bottom

25.6.1 Foundations Support According to BS EN 14015-2004 Section 8.1, it can be assumed that the tank bottom is fully supported by the prepared foundations.

25.6.2 Tank Bottom The tank bottom will comprise of a combination of ‘Steel Bottom Plates’ and a ring of ‘Annular Plates’ that will be laid on the prepared foundation in the following arrangement:

25.7 Steel Bottom Plates

25.7.1 Plate Arrangement The Steel Bottom Plates arrangement conforms to BS EN 14015-2004 Section 8 and will overlap.

25.7.2 Plate Connections Steel Bottom Plates will be lap welded on the upper side only – using a continuous fillet weld

25.7.3 Thickness: The Steel Bottom Plate thickness was designed in conjunction with Table 13 from BS EN 14015-2004 Section 8 Table 66-Minimum nominal bottom plate thickness

224

Fig. 160 Plate Overlap

Therefore, the Steel Bottom Plates will be 6mm thick. The thickness of the plates is considered to be sufficient at resisting uplift from negative internal pressure (5mbar).

25.7.4 Plate Overlap In accordance with BS EN 14015-2004 Section 8, the length of the Bottom Plate overlap must be greater than a product of 5 plate thicknesses. Therefore the Bottom Plate overlap (𝑒𝑏) is equal to 30mm.

25.8 Ring of Annular Plates

25.8.1 Requirement Steel tanks with a diameter greater than 12.5m must have a ring of Annular Plates. The reason behind this is that the ring of Annular Plates increases the tank wall uplift resistance, thus eradicating the need for tank anchorage.

25.8.2 Sizing The dimensions of an individual Annular Plate is: 30mm

25.8.3 Arrangement The minimum inside projection of Annular Plates is 600m, meaning that 600mm of annular plate must be on the inside of the tank. http://accessengineeringlibrary.com.ezproxy.is.ed.ac.uk/browse/steel-water-storage-tanks-design-construction-maintenance-and-repair/p2001aec19970227001

25.8.4 Thickness of Annular plates The thickness of the Annular Plates must adhere to the BS EN 14015-2004 Section 8 requirement that:

𝑒𝑎 = 3 + 𝑒1

3

Where: 𝑒𝑎 = Thickness of an Annular Plate 𝑒1 = Thickness of course 1 of the tank wall Therefore, the Annular Plates will be 8mm thick.

225

Fig. 161 Bottom Plates

25.8.5 Connection (Annular Plate – Annular Plate) The end-to-end connections between annular plates will be ‘Full Penetration Butt Welds’ in conjunction with BS EN 14015-2004 Section 8.

25.8.6 Connection (Annular Plate – Tank Wall Plate) The connection between Annular Plates and the Tank Wall Plats will be a ‘Continuous Fillet Weld’ on both sides of the tank wall plates in conjunction with BS EN 14015-2004 Section 8. These must be tested for water-tightness using dye penetrant prior to the tank being filled with water. If there is no indication of any dye from the outside, then the tank can be considered to be watertight.

25.8.7 Connection (Bottom Plates - Annular Plates) The Bottom Plates must be lapped over the Annular Plates – using a continuous fillet weld on the upper side only in conjunction with BS EN 14015-2004 Section 8 The Bottom plates must have a minimum overlap distance of 60mm over the Annular Plates.

25.9 Inlet and Outlet design

25.9.1 Inlet The main pipe leading to the service reservoirs will split into four – one for each reservoir. Internal diameter of pipe = 300mm (a quarter of the inner diameter of the main pipe) Splitting the volume flow rate of the water into the flow rate for each reservoir gives 0.29m3/s ∴ Water velocity at reservoir inlet = 4.1m/s If the water in the reservoir reaches a critically high level then to help prevent backflow of water in the pipe a rubber duckbill non return valve will be inserted at the end of the pipe as well as having a flow control valve to shut off the incoming flow.

226

25.9.2 Outlet Each service reservoir will have 2 outlet pipes: one for primary use and one in case of emergency where the main outlet fails or if the reservoir needs to be drained at a faster rate. The outlet pipes will have the same internal diameter as the inlet. Once the water leaves the outlet the pipe then splits into 2, each path having a valve preventing flow unless it has been opened. One path will lead to Sandalwood for use as potable water whereas the other path will be used if the water has been contaminated and is not suitable for human consumption. The outlets will be placed on the other end of the service reservoir to the inlet but displaced slightly to allow room for the baffle walls.

25.9.3 Connections The inlet and outlet pipes must have a suitable means of fixing in place to the reservoir, the suggested solution is a hubbed slip-on flange in which the pipe can be fillet welded onto the flange and the flange bolted to the service reservoir wall (Costal Flange, 2015). The hubbed slip-on flange for welding can handle pressures up to 100bar and will be designed according to EN 1092-1 on flanges (Wellgrow Industries Corp., 2015).

Fig. 162 – Side elevation detail of stiffening ring on tank The dimensions relating to figure 162 are as follows: D = 585mm K = 500mm L = 42mm B1 = 327.5mm R = 12mm N2 = 355.9mm C2 = 68mm H1 = 80mm This flange will use 16 size M39 bolts each with 3 flanges on each reservoir: 1 for inlet and 1 for each outlet (Wellgrow Industries Corp., 2015). The flange is displayed in Figure 163.

227

Fig. 163 – Flange connection for inlet/outlet pipe to service reservoir.

25.10 Ventilation It is a requirement of service reservoirs to have adequate ventilation to help relieve pressure and prevent vacuum conditions whilst preventing drafts, debris, rain, insects and other pollutants entering the water supply (Meier, 2010). It is also a standard of AWWA D100 that a vent is placed near the centre of the reservoir roof (Meier, 2010). Due to the large size of each service reservoir there will be one vent near the roof centre and 4 extra ones placed near the walls separated by 90° to promote cross flow ventilation.

25.11 Overflow All service reservoirs must have a method of preventing the water from overflowing. In this scheme a pressure level sensor will indicate when the water has reached a critically high level, which will then shut off the inlet valve and open the emergency outlet to prevent inflow and also to double the rate at which water is removed from the reservoir bringing the water back to a safe working level.

25.12 Baffles As mentioned in the Options Report, baffle walls will be installed in the service reservoir to promote plug flow. Research was carried out on a number of circular reservoir projects with Computational Fluid Dynamics (CFD) to simulate fluid flow through a reservoir studying the effect of baffle walls. Figures 164 and 165 show the velocity of fluid particles at the surface of the water of a circular reservoir with no baffles and then with baffles respectively, taken from a study on Hartshead Moor service reservoir in England (Glynn & Shilton). It must be noted that this case study is a qualitative analysis and that the numbers will not reflect the Sandalwood reservoirs figures.

228

Fig. 164 – Velocity vectors at surface with no baffles (Glynn & Shilton)

Fig. 165 – Velocity vectors at surface with baffles (Glynn & Shilton)

From Figure 164 it can be seen that the water follows an almost circular path around the reservoir ie. no plug flow. Figure 165 however shows the fluid vector arrows pointing around the baffle walls making their way to the exit – this ‘start

229

to finish’ path is plug flow. Note that on average the velocities are smaller in the case where there are baffles, but as long as the water keeps flowing it should not promote stagnation.

Fig. 166 – Residence times at surface with no baffles (Glynn & Shilton)

Fig. 167 – Residence times at surface with baffles (Glynn & Shilton)

230

Figures 166 and 167 show how long the particles of water remains in a specific area in the cases with no baffles and baffles respectively. With no baffles it can be seen that the residence time is fairly uniform with a time roughly of 7 E+4s. With baffles, at the entrance the water has a relatively low residence time of roughly 1 to 2 E+4s, a high residence time of 1 E+5s in the middle and then a lower time of 6 E+4s. The low residence time at the start in Figure 167 is because all the water has been guided towards the same direction by the wall boundary whereas in Figure 166 the water disperses in all directions once it leaves the inlet because there is no boundary. Circulation occurs as the particles of water separate from the baffle wall causing the high residence time region in the centre of the reservoir in Figure 166 the particles in this middle region then interact with the incoming particles at the beginning and so cause the intermediate (green) residence time region towards the end. From the above case study it can be seen that this project should incorporate baffle wall for promoting plug flow. Areas of higher residence times are present in the baffle wall arrangement but these are small concentrations and overall this time is smaller than the baffle-less arrangement; surface water velocities are negligibly smaller in the case of the baffles and so the plug flow benefit outweighs the other factors. It is advised to have the inlet and outlet at opposite ends of the reservoir to distribute the water as much as possible [164] and so 2 baffle walls are the most suitable option without overcrowding the inside of the reservoir and displacing too much water – 1 wall in a shape like this would not be practical as it would cause areas of trapped water due the water only passing by one wall and so would be diverted away from the outlet. Figure 165 shows a 2 baffle wall arrangement where the water will pass by the walls twice which would tend to send the water back in its original direction; sharp corners have been filled in to prevent stagnation in these areas which will allow a smoother flow of water. The inlet and outlet should be as parallel as possible to the baffle walls to prevent the water slowing down when it collides with the walls.

25.13 Access Access to the service reservoir is prohibited when full but once it has been emptied it can be checked for maintenance and repairs. There will be 2 doors for access 180° apart with their base 2.5m from the top of the reservoirs (Twort, 2000), these doors must be completely sealed and securely locked when the reservoir is in use. A stairway will lead from the ground to 90° between each door to minimise the distance from door to stairway in the case of an emergency. A platform will be fitted circling 180° to allow the user to walk between access doors and stairway. A platform will also be fitted around the inside of the reservoir level with the doors for interior access; retractable ladders will also be fitted on the interior so that workers can access the floor/bottom portion of the reservoir – these will be retracted when the reservoir is filled with water.

231

25.14 Stairways To reach the access doors at the top of the reservoir a stairway needs to be constructed. BS EN 14015:2004 states that the stairway should not exceed a vertical angle of 45°, should have a 200mm rise, have a minimum walking space of 600mm and have an immediate landing every 6m vertically (BS EN 14015:2004). In the case of an emergency there should be a ladder at each platform to provide a quicker route to the ground than the stairs (BS EN 14015:2004). Because of the curvature of the reservoir walls there only has to be a handrail on one side of the stairway seeing as the other side is supported by the walls, this stairway will spiral around the reservoir walls to the top. The stairwell will be constructed from galvanised steel for strength and also to protect against corrosion from the outside environment.

25.15 Amenities On site, workers shall have access to 2 toilets, a cleaning station and a cloakroom for safety equipment and protective clothing like fluorescent vests, helmets and facemasks. There will also be first aid facilities to treat any injuries.

232

26. Lighting 26.1 Lighting layouts for each room

Fig. 168: Lighting plan of the control centre.

Fig. 169: Lighting plan of the kitchen.

Figure 170: Lighting plan of the WC.

233

26.2 Lighting results for each room

Fig. 171: DIALux lighting results for the kitchen.

Fig. 172 DIALux lighting results for the control centre. Fig.172: DIALux lighting results for the control centre. Fig.172: DIALux lighting results for the control centre. Fig.172: DIALux lighting results for the control centre.

234

Fig. 172: DIALux lighting results for the control centre.

235

Figure 173: DIALux lighting results for the WC.

236

27. Risk Assessment

Tables 67-74 detail the hazards and mitigation m

ethods for each section. Hazards are assigned a severity score out of 5 (5 being the

most severe) and a frequency score (5 being the m

ost frequent). The product of the two scores provides an overall risk rating – a total

score of less than 5 is deemed ‘low

risk’, a total score of 5-15 is deemed ‘m

edium risk’ and a score greater than 15 is deem

ed ‘high risk’. 27.1 Social Risk Assessm

ent Table 67 – Risk Assessm

ent for Social Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

General Strike action

Cooperate with w

orkers and treat them

fairly. Ensure health and safety is a number

one priority during construction. 3

1 3

Low risk

General Fraud and corruption

Create a 'Fraud and Corruption App' that allow

s all stakeholders in the project to report instances of corruption

2 3

6 M

edium

Risk

General

Conflict between the State

of Tamil N

adu and the State of Karnataka over use of shared w

ater resources

Work w

ith peacebuilding NGO International

Alert and Cauvery Water Disputes Tribunal

to mediate betw

een the two states and

ensure no further conflict occurs

3 1

3 Low

risk

General

Conflict occuring between

the project and the disturbed local

comm

unities opposed to the w

ork

Establish a stakeholder engagement team

to engage w

ith the local comm

unity and other stakeholders to ensure m

inimum

disruption 2

2 4

Low risk

237

27.2 Economic Risk Assessm

ent Table 68 – Risk Assessm

ent for Economic Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

General Drop in exchange rate of Indian Rupee

This is an accepted risk, the tendering price should have been adjusted to m

itigate this. 5

1 5

Medium

Risk

General Failure/delays of m

aterial delivery

Liaise with suppliers and ensure there are sufficient late

delivery penalties in the contracts. 2

3 6

Medium

Risk

General Faulty or ineffective m

aterial

Quality checks should be carried out periodically on delivered goods. Sufficient com

pensation should be agreed in any supplier contracts.

2 3

6 M

edium

Risk

General Low

quality sub-contractors

Only the highest standard of subcontractor should be employed

where possible.

2 3

6 M

edium

Risk General

Unforseen geotechnical problem

s

Extensive ground investigations should be conducted and appropriate designs should be developed upon encountering an issue

2 2

4 Low

risk

Pipeline Loss of pipe due to flooding

DIP has been chosen over lighter, more bouyant m

aterials 1

1 1

Low risk

Service Reservoir

Leaks The w

elded connections between steel plates have been

tailored to the type connection in order to minim

ise risk of leaks. Checks of w

elding conducted as construction goes on. Once the floor and w

alls are completed, they are tested to

ensure there are no leaks prior to the tanks being operational

3 2

6 M

edium

Risk

Service Reservoir

Local Buckling of tank due to w

ind/ negative pressure

The tanks have been designed against local buckling, with

features sucha as 2 secondary stiffening rings and the top corner ring providing resistance against such an issue

5 1

5 M

edium

Risk

238

Service Reservoir

Collapse of tank due to overturning m

oment

The tank floor has been designed with thickened annular ring

plates with provide sufficient resisitance against such an issue

5 1

5 M

edium

Risk

General Theft of building m

aterials

Construct fencing around all construction sites 2

2 4

Low risk

27.3 Construction Risk Assessment

Table 69 – Risk Assessment for Construction Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

Pipeline Lim

ited skilled labour causing accidents or delays

A simple m

ethod of joints has been chosen to limit

any on-site welding or specialist construction

techniques

2 1

2 Low

risk

Pipeline Trench w

alls fail A trench box should be used w

henever workers are

working w

ithin the trenches 4

2 8

Medium

Risk

Pipeline M

oving plant H

i vis must be w

orn by all on site and banksmen

should be used whilst any plant is reversing

4 2

8 M

edium

Risk Pipeline

Working near deep

water

Supervisors should enforce strict rules regarding behaviour near w

ater and protective fencing and railings should be tem

porarily constructed

2 1

2 Low

risk

Pipeline W

orking in isolated, rural locations

Amm

enities should be provided for the workforce,

with sufficient first aid and m

eans on contacting supervisors

3 2

6 M

edium

Risk

Pipeline Lifting pipe sections

Strong slings should be used and properly attached to the lifting plant

3 2

6 M

edium

Risk General

Lack of local know

ledge leading Collaborate w

ith local engineering companies to get

a local insight into specific regional issues 2

2 4

Low risk

239

to unexpected delays in construction

Service Reservoir

Worker/engineer

on foot being hit by plant

Compulsory for all w

orkers to wear hi-vis. Prom

ote site aw

areness and comm

unication between plant

operators and workers on foot. Construct a

dedicated channel surrounded by stop blocks to m

inimise risk.

4 1

4 Low

risk

Service Reservoir

Electrocution from

welding

Plan works so that there is m

inimal w

elding during the M

onsoon Season. If welding does need to take

place when it is raining, construct a tem

porary tented cover over area w

here works is being

conducted.

5 2

10 M

edium

Risk

Service Reservoir

Tinnitus due to operation of m

achinery (vibratoy rollers, excavators, dum

per trucks, cranes)

Issue ear protection to all machinery operators.

Enclose operator in an insulated cab. Conduct routine m

aintenance minim

ise loose/ unbalanced m

achine parts (which create unnecessary noise)

2 2

4 Low

risk

Service Reservoir

Workers falling

from height

Ensure high safety standards on construction of scaffolding. M

aintain regular checks on the scissor lifts to m

inimise risk of som

ething going wrong.

Ensure that no steel workers or w

elders are on guide lines on the roof if it is raining

5 1

5 M

edium

Risk

Service Reservoir

Plant driven into excavation

Once excavation has been completed, have stop

blocks positioned 4m from

the edge of the excavation. M

obile Warning sysytem

in plant to w

arn operator when m

achine is close to the edge

3 1

3 Low

risk

Road Crossing

Tunnel Boring M

achine hits Granite Baserock

Ensure correct allignment of the Jacking Fram

e, H

ydraulic Jack, TBM, Laser and Thrust W

all 3

1 3

Low risk

240

Road Crossing

Tunnel Boring M

achine stalls Control system

to ensure the TBM has the correct

loading applied from the H

ydraulic Jack 2

2 4

Low risk

Road Crossing

Tunnel Boring M

achine hits rock and m

isaligned

Thorough soil testing prior to microtunneling

comm

encing. Regular checks of TBM position, so

that any misdirection is spotted early on.

3 2

6 M

edium

Risk

Road Crossing

Damage to Steel

Pipe Casing/ Ductile Iron W

ater Pipe

Use of thrust ring on the end of hydraulic jackend of the pipe in order to ensure an even pressure distribution, and careful m

onitoring/ control system

to ensure hydraulic jack does not exert excessive pressure on either of the pipes.

3 1

3 Low

risk

Pipeline Lone w

orking Due to the nature of the isolated construction area it is recom

mended that precautions be taken to lim

it the am

ount of lone working taking place during

construction.

2 3

6 M

edium

Risk

General Falling parts

All personnel must w

ear helmets on site.

5 3

15 M

edium

Risk 27.4 O

peration Risk Assessment

Table 70 – Risk Assessment for Operation Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

Service Reservoir

Overflow of w

ater Install control system

to shut off inlet and open em

ergency outlet to drain reservoir to a safe level. 4

1 4

Low risk

Service Reservoir

Employee falling from

a height

Construct handrails on stairwells and railings on

the inside and outside of the reservoir where

elevated platforms are present.

5 1

5 M

edium

Risk

General Inability to see during night tim

e Install light fixtures around site including w

alkways and w

orking components.

3 1

3 Low

risk

241

Sludge Storage

Overfill of sludge Create silo large enough to hold 1 w

eeks’ worth of

sludge whilst using trucks to drain it daily. Install

emergency silo.

3 1

3 Low

risk

Sludge Storage

Exposure to toxic chem

icals in sludge H

ave access to a cloakroom w

ith protective clothing, helm

ets, masks and gloves to prevent

inhalation and contact with skin. Produce w

arning signage to alert w

orkers of health hazards.

4 1

4 Low

risk

Sludge Storage

Silo falling over Build infrastructure to securely support w

aste silos.

5 1

5 M

edium

Risk Pipeline

Damage to pipeline by

animals

Animal crossing w

ill be designed approx. every 350m

4

1 4

Low risk

Bridges M

aintenance workers

falling from the bridge

when inspecting pipeline

A steel railing will be built on either side of the

bridge 5

1 5

Medium

Risk

Water

supply Dem

and increasing to beyond the capacity of the system

The system has designed for future dem

and (with

safety factors) and will have the potential for

expansion. The stakeholder engagement team

will

work w

ith the customers to prom

ote the efficient use of w

ater and will aim

to reduce demand

3 1

3 Low

risk

Service Reservoir

Flooding damage to

tanks The tank foundations have been designed in a m

anner that promotes reduces likelihood of

foundations being damaged due to flooding.

Efficient drainage system w

ill ensure water levels

never endanger tank of being susptible to corrossion from

surface water.

2 2

4 Low

risk

Service Reservoir

Leaks The w

elded connections between steel plates have

been tailored to the type connection in order to m

inimise risk of leaks. Checks of w

elding conducted as construction goes on. Once the floor and w

alls are completed, they are tested to ensure

there are no leaks prior to the tanks being

4 2

8 M

edium

Risk

242

operational Pipeline

Failure of pipeline support

Regular inspections of supporting structures and the pipeline itself should be carried out over its lifetim

e.

3 1

3 Low

risk

Pipeline Explosion or large im

pact causing pipe to fail

Pipeline has been built 14m aw

ay from the road

and the pipeline itself will be m

ade of DIP for increased resistance to im

pact

4 1

4 Low

risk

General Dam

age to hearing from

loud noises Ear protection m

ust be worn w

hen working in

loud areas. Signage must be placed to alert

workers of these loud zones.

4 2

8 M

edium

Risk

Water

Treatment

plant

Combination of alum

and sodium

chlorite can result in an explosive form

ation of sulphur oxides and chlorine

Avoid the use of sodium chlorite

5 1

5 M

edium

Risk

Water

Treatment

plant

Alum is som

ewhat acidic

and can burn the skin quite severely

Workers are provided w

ith protective googles, gloves and m

ask and laundry and changing facilities are provided on site

3 1

3 Low

risk

Water

Treatment

plant

Contact with lim

e can cause irritation to eyes, skin, resperiratory system

and gastrointestinal tract

Workers are provided w

ith protective googles, gloves and m

ask and laundry and changing facilities are provided on site

3 1

3 Low

risk

Water

Treatment

plant

Lime reacts vigorously

with acids. Such

reactions can rapture containers

Storing the lime in tightly closed plastic or non-

aluminium

metal container in a cool dry and w

ell-ventilated locations aw

ay from acids and other

incompatible m

aterials

3 1

3 Low

risk

Water

Treatment

plant

Sulphuric acid is very hazardous in the case of skin contact, eye contact, ingestion and inhalation.

Workers are provided w

ith protective googles, gloves and m

ask and laundry and changing facilities are provided on site

5 1

5 M

edium

Risk

243

Severe overexposure can result in death

Water

Treatment

plant

Sulphuric acid may

corrode metalic surfaces

The sulphuric is stored in a carbon steel vessel w

hich it will not corrode

3 1

3 Low

risk

Water

Treatment

plant

Chlorine is very hazardous in the case of skin contact, eye contact, ingestion and inhalation. Can result in death, blindness, frostbite and perm

enant scaring

Workers are provided w

ith protective googles, gloves and m

ask and laundry and changing facilities are provided on site

5 1

5 M

edium

Risk

Water

Treatment

plant

Chlorine is very reactive. Reacts w

ith many

chemicals explosively

including alcohols, m

etals and hydrocarbons

Store the chlorine in a pressurised vessel. Injectors are used to dose the chlorine under vacuum

thus m

inimising release

5 2

10 M

edium

Risk

Water

Treatment

plant

Chlorine can form DH

Ms

if it reacts with organics

Store the chlorine away from

organics 5

1 5

Medium

Risk

Water

Treatment

plant

Contact with

polyelectrolyte can cause irritation to skin and eyes

Workers are provided w

ith protective googles, gloves and m

ask and laundry and changing facilities are provided on site

3 1

3 Low

risk

Water

Treatment

plant

Polyelectrolyte can spill and cause a the w

ork surface to becom

e slippy

Clean up all spills appropriately and quickly and use w

arning signs 3

1 3

Low risk

244

27.5 System Condition Risk Assessm

ent Table 71 – Risk Assessm

ent for System Condition Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

Service Reservoir

Corrosion of m

etallic parts Regular m

aintenance checks on all parts. 4

2 8

Medium

Risk

Service Reservoir

Leakages/cracks on service reservoir

Shut off inlet and drain reservoir then carry out repairs. Extra reservoirs to supply w

ater during this tim

e.

5 1

5 M

edium

Risk

Service Reservoir

Leakages/cracks on inlet pipe

Shut off inlet then carry out repairs. Extra reservoirs to supply w

ater during this time.

4 2

8 M

edium

Risk Service

Reservoir Leakages/cracks on outlet pipe

Shut off outlet and open emergency outlet.

2 2

4 Low

risk

Sludge Storage

Leakages/cracks in the silo

Redirect sludge to emergency silo, drain m

ain silo and conduct repairs.

4 1

4 Low

risk

Pipeline Increased friction due to corrosion over tim

e

A spun concrete lining has been included in the design to lim

it corrosion inside the DIP 2

1 2

Low risk

Pipeline Corrosion of the outside surface of the pipe

Overground pipe is coated in protective paint and underground pipe is w

rapped in polyethylene 4

1 4

Low risk

Sludge Storage

Failure of sludge pum

p Incorporate a second sludge pum

p in parallel with

the main pum

p as an emergency back up and send it

to the emergency silo. Com

mence w

ork on damaged

pump.

2 1

2 Low

risk

Sludge Storage

Failure of sludge pipe to silo

Incorporate a second pipe in parallel to the main

pipe fitted to the emergency sludge pum

p as an em

ergency back up and send it to the emergency

silo. Comm

ence works on dam

aged pipe.

2 1

2 Low

risk

245

Bridges Steel truss m

embers

corroding and failing

Protective paint will be used and applied

periodically to prevent corrosion. The bridge is over-designed to allow

workers to take off m

embers and

replace them w

ithout comprom

ising the structure's integrity

2 2

4 Low

risk

Bridges Steel cables corroding and failing

The steel cables are treated to prevent corrosion and can be replaced w

ithout comprom

ising the structure's integrity

2 2

4 Low

risk

Bridges Pipeline on bridge getting dam

aged and w

orkers not being able to access it

A 1m w

alkway w

ill be built on either side of the pipeline on the bridge to allow

maintenance w

orkers to safely access the pipe

2 1

2 Low

risk

Bridges The bridges collapsing

The bridges have been designed with appropriate

safety and partial factors to ensure no loading com

binations can cause ultimate failure of the

structures

5 1

5 M

edium

Risk

Pump

Corrosion of m

etallic parts Regular m

aintenance checks on all parts. 4

2 8

Medium

Risk

Pump

Formation of

cavitation erosion on the im

peller

Regular maintenance checks on all parts.

4 2

8 M

edium

Risk

Pump

Using pump for

outside its application lim

its

Pumps should be used in their specified lim

its and applications only. Regular checks on the installed control system

s for an abnormalities

5 1

5 M

edium

Risk

Pump

Failure to support suction

Have control system

in place to check the abnorm

alities in pump w

ork 5

1 5

Medium

Risk

Pump

Pump Runs Dry

Pump should be prim

ed according to the regulations 4

1 4

Low risk

Water

Cold Conditions It should be m

ade sure that pump is w

ith not frozen liquid, liquid should be checked before prim

ing 3

1 3

Low risk

246

Pump

Leakages/cracks on pum

p Shut dow

n the pumps and carried out inspection

5 1

5 M

edium

Risk Pum

p Pum

p bearing tem

perature Pum

p bearings temperature w

ill be controlled by a system

4

1 4

Low risk

Pump

Exceeding the pum

p pressure Pum

p pressure is controlled by gauges 4

1 4

Low risk

Pump

Air in the pump

Inspect all joints, plugs and be sure all priming is

done correctly and all valves are closed 4

2 8

Medium

Risk

General Access road to stations blocked during m

onsoon season

Control systems are placed to control the every

action from a m

ain frame in the m

ain control room

4 2

8 M

edium

Risk

27.6 Public Risk Assessment

Table 72 – Risk Assessment for Public Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

Bridges Unauthorised personnel clim

bing onto the bridge and falling or jum

ping off and dying

Fencing and locked gates will be built on

either side of the bridges to prevent unauthorised access

5 2

10 M

edium

Risk

Water

Treatment

plant

Public mem

bers being harm

ed by any of the chem

icals in the water

treatment plant

Keep all chemicals locked up securely and

only allow public access to the plant in a

controlled manner

5 1

5 M

edium

Risk

General General public falling into excavations

Construct fencing around all excavations and ensure no unauthorised people enter the construcion site

3 2

6 M

edium

Risk

247

Pump

Noise lim

it can be exceeded depending on the perform

ance

Employees should w

ear specified ear defender equipm

ent 3

2 6

Medium

Risk

Pump

Wearing loose clothing

and jewellery around

rotating parts

Appropriate clothing should be warn

5 2

10 M

edium

Risk

Pump

Placing limbs in rotating

parts Rotating parts m

ust not be touched. Protection covers and guards shouldn’t be rem

oved. For maintenance rem

ove guards, but place them

back

5 2

10 M

edium

Risk

Pump

Hot Surfaces

Hot surface w

arnings are placed 3

1 3

Low risk

General Excessive N

oise Levels Check the bearings and alignm

ent of the rotor regularly

4 2

8 M

edium

Risk Pum

p Electric hazards

Motor should not be touched sw

itch off and isolate m

ains supply before work

being carried out

5 1

5 M

edium

Risk

General Slipping due to w

ater spillage

Non-slip safety shoes m

ust be warn

3 3

9 M

edium

Risk General

Inability to see during night

Install light fixtures around each pump

station including walkw

ays and working

components.

3 1

3 Low

risk

WTP

THM

formation as a

result of chlorine reacting w

ith organics

Chlorine addition only used later in the treatm

ent process once most organic

matter has been rem

oved.

5 1

5 M

edium

Risk

WTP

Pathogens in water

distribution lines resulting in sickness to final consum

er

Disinfection residual provided by controlling the chlorine dosage to the w

ater

4 1

4 Low

risk

248

27.7 Environmental Risk Assessm

ent Table 73 – Risk Assessm

ent for Environmental Risks

System

Hazard

Mitigation

SOI

FOI

TOTAL

(SOI x

FOI)

Level of Risk

Sludge Storage

Roads in unusable condition by trucks due to m

onsoon

Create silos large enough to hold 1 weeks’ w

orth of sludge in each silo for a fortnight’s supply.

5 2

10 M

edium

Risk

Pipeline Anim

als being unable to cross due to the pipeline obstruction

The over-ground pipeline will be 35cm

from the ground to

allow sm

aller animals to cross underneath and crossing points

will be constructed every 350m

to allow larger anim

als to cross undistrubed. The crossings have been designed w

ith a gradual slope to allow

animals to cross and landscaping w

ill be done to naturally guide anim

als to crossing points

1 3

3 Low

risk

Bridges Flooding dam

aging the bridge abutm

ents

The abutments have been adequately designed to resit loading

from flooding. The abutm

ents have been designed away from

the norm

al flow of the river and additional flow

barriers can be constructed to prevent any errosion of the abutm

ents

2 1

2 Low

risk

Bridges Extrem

e w

ind loading dam

aging the bridge

The bridge structures have been designed with m

inimum

surface area to m

inimise w

ind loading 3

1 3

Low risk

Pipeline Flooding dam

aging the over-ground pipeline

The over-ground pipeline will be 35cm

from the ground to

prevent damage from

frequent low flooding

2 2

4 Low

risk

249

27.8 Other Risk Assessm

ent Table 74 – Risk Assessm

ent for Other Risks System

H

azard M

itigation SO

I FO

I TO

TAL (SO

I x FO

I)

Level of Risk

Pipeline Inconsistant or a low

quality of concrete delivery

Cubes should be taken of every delivery and a reliable supplier should be found before com

mencing w

ork.

1 3

3 Low

risk

General Tripping over obstacles

Keep all workplaces clean and tidy. Do not

run on site. 3

2 6

Medium

Risk

250

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257

Academic Appendix Harry Dickie: Contribution

x Service Reservoir o Foundations Design o Tank Bottom Design o Tank Walls Design o Tank Roof Design o Maintenance Access Design o Stiffening Ring/ Top Corner Ring Design o Construction Sequence o Layout o Risk Assessment o Costing

x Road Crossing o Construction Sequence o Design o Risk Assessment o Costing

x Sludge Tank o Tank Design o Costing

x Bridges o Research

Skills

x Excel skills x Word skills x Research skills x Communication x Teamwork x Steel Tank design x Foundation design x Microtunneling x Problem solving

Thomas Findlay Contribution

x Water Demand x Stakeholder Engagement x Truss Bridge

258

x Cable-stayed Bridge x Over-ground pipeline crossings x Risk assessment summary x Formatting

Skills

x Drawing skills x Excel skills x Word skills x Visio skills x Communication x Teamwork x Interdisciplinary collaboration x Problem solving x Structural design and water treatment

Stuart Fraser

Sections:

Water Treatment Process

x Background-Introduction and mass balance x Process Flow Diagram(PFD) x Chemical treatment design-Sludge Thickening and Sludge

dewatering(entire sections) x Chemical treatment design-Disinfection costing and sizing x All chemical costs and doses and respective M+E costs x Risk assessment-water treatment plant section x Compiling of water treatment appendices

What I learned

During this project I developed my abilities to work as part of a team and I gained a greater understanding of water treatment processes and the roles various engineering disciplines play in designing a water treatment plant. I also developed a greater understanding of other engineering disciplines and learned how to select and design appropriate processes, units and chemicals for a water treatment plant. Development of my abilities to design pfds and p&ids and to solve mass balances was achieved as well alongside useful time management skills

Elliot Hunter

Sections:

259

x Water Conveyance in WTP - Hydraulic Gradient

x Sludge Management x Design of Water Conveyance system

- Pumping from NBR to WTP - Pumping from WTP to Sandalwood - Pump Selection – (Pump House Layout , Pump House Locations, CAD

drawing) - Efficiency calculations - 3D Sketch-up model of Pump House

x Formatting of Intake, Electricity and Total Costing What I learned

This project helped me greatly appreciate and understand better the role of an engineer in the world. Working as an interdisciplinary offer the chance to learn invaluable team working skills, which are essential for a working in the real world. This project made an impact by significantly improving my problem solving, time management, project management and formal writing skills. Additionally working my soft skills of communication, flexibility, team and creativity. Research skills, Excel skills and Microsoft Visio skills have been strength through various uses throughout the project. On the broader scheme, this project taught me the challenges faced in engineerin, that are required across the world in water conveyance and most importantly how these problems can be solved.

Andrew MacDonald

Sections:

Clarification system – design, sizing, process control, chemical dosing, report write-up

Filtration system - design, sizing, process control, chemical dosing, report write-up

Disinfection system – choice of oxidising agent, process control, report write-up

Drawing of all WTP P&ID’s (except the waste treatment P&ID)

Compiling of water treatment section write-up

What I learned

This is the first inter-disciplinary project I have worked on and I learned a lot during the project. Having subgroups working on different areas of the design, it was clear that regular group meetings and communication were required from the beginning to make sure everyone was on the same page.

260

Having only worked alongside chemical engineering students in previous projects, it was interesting to hear about different aspects of engineering design other than the process engineering side, and learn how they are all inter-related.

I feel my planning and organisational skills have benefited from this project as it was necessary to regularly set goals for the team as a whole and also for each sub-group. This is something I will definitely continue to apply in the future.

Prior to this project I didn’t consider water treatment to have a lot of chemical engineering application in it, but now appreciate the role which not only chemical engineers, but civil and mechanical, have in providing clean drinking water. Water treatment is definitely an area I am now interested in and intend on pursuing a career in.

Arif Efe Madranefe

x Intake- Intake design, calculations an pump set-up layout, x Pumps- Selection of the pump type, valves x Pipe Selection- calculator showing change in operations cost with

diameter for x pump locations and number of pump stations x Electricity consumption- Operating cost related to each given diameter

and their long term cost effects to the pump life-cycle. How electricity will be delivered and what are the safety factors placed

x Control Systems- Specific products for control technologies and pump control measurement devices, Goulds Control Systems, sensors and sensors locations on the pumps

x AutoCAD- 2D Technical Drawing of Service reservoir x Costing- Costing calculator of the given process costings, electricity

costings. x Sludge Pump- selection and justification of the sludge pump x Risk Assessment- Pumps and Pumping Stations x Reference Compiling- Compiling for the Final Report x Executive Summary- Selecting relevant information from the report

Things I’ve learned;

I’ve found it really valuable to work in an interdisciplinary project team. In the team I learned how diversity can affect the brainstorming process of the team. The overall group dynamic was extraordinary and every member wanted to do more and more. This is due to the fact that we did not choose a project manager making everyone, including me, feel more involved in the project and more willing to take responsibility. This project helped me to enhance my Excel skills

261

as well as report writing and research skills. By the completion of the project I feel that I have a greater appreciation for the water treatment industry.

Paul Taylor Sections: Service Reservoir - design (excluding construction), maintenance, risk assessments Sludge Storage - design (excluding construction), maintenance, risk assessments

Control Systems - descriptions and processes for sludge storage, pump, pipe, service reservoir (all P&ID’s excluding WTP) Main Control Centre - Layout/sizing, amenities Lighting 3D CAD models Company logo and website

What I learned This project has helped me to understand the various roles involved in an engineering project with regards to other disciplines and the different responsibilities expected of each. My team working skills have greatly improved as well as time and project management skills and also innovative and creative thinking. Aside from personal improvements I have also learned a great amount about how society receives clean water which we take for granted and the various processes and controls required to meet acceptable standards. Marcus Wright: Sections:

x Water conveyance design o Pipe design o System design o Pipe material o Pipe support o Pipe encasement o Valve design o Pipeline control system o Construction Sequence

x WTP o Construction Sequence

x Risk assessment x Formatting

Skills

x Excel skills x Word skills x Visio skills x Communication x Teamwork

262

x Water conveyance design x Problem solving