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DRAKENSTEIN MUNICIPALITY
WASTE WATER RISK ABATEMENT PLAN (W2RAP)
REVISION B
FEBRUARY 2013 Prepared by : Prepared for : LYNERS CONSULTING ENGINEERS
DRAKENSTEIN MUNICIPALITY
AND PROJECT MANAGERS P O BOX 1 P O BOX 79 MAIN STREET PAARL MAIN STREET PAARL 7622 7622 TEL : (021) 872 3564 TEL : (021) 807 4500 FAX : (021) 872 0619 FAX : (021) 872 8054
Revision History
Revision No.
Prepared by Description Date
Draft A Lyners Draft of W2RAP 7 October 2011
Draft B Lyners Draft of W2RAP 1 February 2013
Document Acceptance
Action Name Signed Date
Prepared by Lyners
Reviewed by R Brown
Approved by R Brown
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Table of Contents
1 INTRODUCTION .................................................................................................................................. 1
2 DESCRIPTION OF W2RAP TEAM ....................................................................................................... 1
2.1 Duties of team and commitment ........................................................................................................... 1
3 DESCRIPTION OF VARIOUS WORKS ............................................................................................... 3
3.1 Paarl WWTW ........................................................................................................................................ 3
3.1.1 Catchment ............................................................................................................................................. 3
3.1.2 Collection .............................................................................................................................................. 3
3.1.3 Treatment .............................................................................................................................................. 3
3.2 Wellington WWTW ................................................................................................................................ 4
3.2.1 Catchment ............................................................................................................................................. 4
3.2.2 Collection .............................................................................................................................................. 4
3.2.3 Treatment .............................................................................................................................................. 5
3.3 Pearl Valley WWTW ............................................................................................................................. 5
3.3.1 Catchment ............................................................................................................................................. 5
3.3.2 Collection .............................................................................................................................................. 5
3.3.3 Treatment .............................................................................................................................................. 6
3.4 Saron WWTW ....................................................................................................................................... 6
3.4.1 Catchment ............................................................................................................................................. 6
3.4.2 Collection .............................................................................................................................................. 7
3.4.3 Treatment .............................................................................................................................................. 7
3.5 Hermon WWTW .................................................................................................................................... 7
3.5.1 Catchment ............................................................................................................................................. 7
3.5.2 Collection .............................................................................................................................................. 8
3.5.3 Treatment .............................................................................................................................................. 8
3.6 Gouda WWTW ...................................................................................................................................... 8
3.6.1 Catchment ............................................................................................................................................. 8
3.6.2 Collection .............................................................................................................................................. 8
3.6.3 Treatment .............................................................................................................................................. 8
4 HAZARD ASSESSMENT...................................................................................................................... 9
4.1 Risk Matrix used ................................................................................................................................... 9
4.2 Hazard Analysis of works ................................................................................................................... 11
4.3 Paarl WWTW ...................................................................................................................................... 11
4.4 Pearl Valley WWTW ........................................................................................................................... 15
4.5 Wellington WWTW .............................................................................................................................. 17
4.6 Hermon WWTW .................................................................................................................................. 21
4.7 Saron WWTW ..................................................................................................................................... 22
4.8 Gouda WWTW .................................................................................................................................... 26
5 CONTROL MEASUREMENTS ........................................................................................................... 29
6 MONITORING OF CONTROL MEASURES AND RESPONSE PROTOCOL ................................... 31
6.1 Operational Alert Levels...................................................................................................................... 32
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6.2 Verification of functioning of W2RAP .................................................................................................. 32
7 SUPPORT PROGRAMMES ............................................................................................................... 33
7.1 Process Controller Training Provided ................................................................................................. 33
7.2 Supervisors Forum .............................................................................................................................. 33
7.3 Career Pathing .................................................................................................................................... 33
7.4 Consultant Advisors ............................................................................................................................ 33
8 INCIDENT MANAGEMENT PLAN ...................................................................................................... 33
9 CONCLUSIONS .................................................................................................................................. 36
10 RECOMMENDATIONS....................................................................................................................... 36
10.1 Risks to be addressed ........................................................................................................................ 36
10.2 Way forward ........................................................................................................................................ 36
ANNEXURES : ANNEXURE A : CATCHMENTS
ANNEXURE B : FLOW DIAGRAMMES
ANNEXURE C : DRAKENSTEIN MUNICIPALITY : WWTW RISK ASSESSMENT
ANNEXURE D : DRAKENSTEIN MUNICIPALITY : WASTE WATER INCIDENT MANAGEMENT PROTOCOL
ANNEXURE E : HIGH AND MEDIUM RISK ITEMS FOR WWTW WITH MITIGATION MEASURES
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1 INTRODUCTION
Drakenstein Municipality currently (year 2013) provides Waste Water Treatment to six (6) communities within it’s municipal boundaries amounting to approximately 240 000 residents. Of the six Waste Water Treatment Works (WWTW), four are activated sludge works and two are evaporation pond systems. Drakenstein Municipality currently experiences challenges with regards to WWTW operation and maintenance which include :
Aging Infrastructure (Sections of Paarl WWTW were upgraded in the 1960’s)
Relatively low Operational & Maintenance Budgets for WWTW’s
Large funding shortfalls for upgrading of existing infrastructure and construction of new infrastructure or technologies.
Skill shortages in WWTW management and operations
Large increases in flow volumes due to increasing housing developments; and
Erratic power supply from national providers.
Given these challenges, it is imperative to follow a risk based management method to risks in the treatment process and identify priority risk areas for inclusion in limited Operational & Maintenance- and Capital upgrading budgets. To this end Drakenstein Municipality has developed a Waste Water Risk Abatement Plan (W
2RAP)
to identify potential risks and mitigation measures for each risk. This document is a living document which will be reviewed and amended constantly as and when the risk situation changes. This document provides an overview of the risks faced by the Drakenstein Municipality and must be considered in conjunction with the other reference documents such as the Green Wastewater Performance Audit Report (November 2012) and the Sewer Master Plan (December 2012).
2 DESCRIPTION OF W
2RAP TEAM
2.1 Duties of team and commitment
The W2RAP team is a multi disciplinary team consisting of team members with intimate knowledge
of the Waste Water Treatment system and the receiving environment. A diagramme showing the composition of this team is shown in figure 2.1 below.
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Figure 2.1 : Diagramme of W
2RAP Team
As the W2RAP is a living document, it is expected that the members of the team provide continual
feedback on the implementation of the system as well as potential improvement. The W
2RAP is a management tool designed to assist policy makers in decision making with regards
to Waste Water Treatment. Drakenstein Municipality owns and manages a total of six (6) WWTW’s and collection systems, namely:
Paarl Wastewater Treatment and Collection System
Wellington Wastewater Treatment and Collection System
Pearl Valley/Val de Vie Wastewater Treatment and Collection System (also known as the Kliprug Wastewater Treatment Plant)
Saron Wastewater Treatment and Collection System
Gouda Wastewater Treatment and Collection System
Hermon Wastewater Treatment and Collection System
Team Leader
Mr R Brown Head of Waste Services Drakenstein Municipality
Compilers
Mr H Mulder (Civil Engineer) and Mr M Filippi (Prof. Civil Engineer and Project Manager)
Private Entities
Berg River Irrigation Board
Information Sources
Mr C Morkel (Supervisor on all Drakenstein WWTW’s)
Various Process controllers for each WWTW
Department of Water Affairs (DWA)
Legislative Bodies
Consultants including WorleyParsons (Green Wastewater Performance Audit), Aurecon and Lyners (Various WWTW’s) AL Abbott Laboratories (Process Auditing) Virtual Consulting Engineers (Saron WWTW) Integral Laboratories (All WWTW’s)
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3 DESCRIPTION OF VARIOUS WORKS 3.1 Paarl WWTW 3.1.1 Catchment
The Paarl WWTW Services a vast section of the Paarl area, from the Bo-Dal Josafat Area to the Paarl South Area, including the areas of Mbekweni and Silvertown to the north. The WWTW is situated next to the Berg River, into which final effluent is discharged. The WWTW is a Class C WWTW under the DWA classifications and currently (2013) has a capacity of 27Mℓ/d, receives and Average Daily Dry Weather Flow (ADDWF) of approximately 22Mℓ/d and is licensed by a water usage permit (No 1222B). A layout of the Paarl WWTW catchment is shown in drawing no 0828/C/002 in Annexure A. The receiving environment is the Berg River. The final effluent must comply with the requirements of the Water Act and for Paarl WWTW these are General Standard. In the near future however the WWTW may need to comply with the Special Standards.
3.1.2 Collection
Influent is conveyed to the Paarl WWTW through various gravity bulk sewers mainly along the Berg River from South to North. The main sewers include the domestic outfall sewer and the industrial outfall sewer. The Bulk Sewer to Southern Paarl currently under construction will serve as a further domestic bulk sewer addressing capacity shortfalls in the existing domestic bulk sewer and providing for future developments in the south of Paarl. Furthermore there are several sewage pumping stations in the catchment that convey sewage via rising mains to the Paarl WWTW which include the following pumping stations shown in table 3.1 below.
Table 3.1 : Sewage Pumping Stations within Paarl
Name of Pumping Station Pumping station to/into
Paarl South Pumping Station No 1 & 2
Existing Domestic Outfall Sewer
Boschenmeer Existing Domestic Outfall Sewer
Roodeberg Existing Domestic Outfall Sewer
Carletta Collector Sewer draining to the Existing Domestic Outfall Sewer
Kaplan Street Collector Sewer draining to the Existing Domestic Outfall Sewer
Dal Josafat Directly to the inlet works of the WWTW
Mbekweni Directly to the inlet works of the WWTW
Silvertown Collection Sewer draining to Mbekweni Pumping Station
Most of the reticulation infrastructure is relatively old, but in good condition. The Asset Management Register of Drakenstein Municipality estimates that approximately 47,6% of the value (useful life) of the sewage network has been consumed. Not withstanding this, the network is continually refurbished/upgraded to replace old infrastructure.
3.1.3 Treatment
The Paarl WWTW comprises a combination of trickling filters (biofilters) and activated sludge processes, with maturation ponds for tertiary treatment. Normally all flow passes through the trickling filter works, after which it is further treated in the activated sludge works. During periods of high flow,
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excess flow that cannot be accommodated hydraulically in the trickling filter works, then bypasses this section and flows directly to the activated sludge works. In 2003, Drakenstein Municipality appointed Ninham Shand (now Aurecon) in association with Lyners to investigate and report on options for upgrading the existing WWTW to provide for nutrient removal, and in particular for phosphate removal (for a maximum ortho-phosphate level of 1 mg/L as PO4). Subsequent to this investigation, Drakenstein Municipality appointed Africon (now Aurecon) to compile a master plan which identified the preferred locations for future WWTW’s in the area. This investigation recommended that the existing Paarl WWTW be developed to a capacity of 35 Mℓ/d. The consulting engineers recommended the treatment of a blend of industrial humus tank effluent and settled and raw domestic sewage in a biological nutrient removal (BNR) activated sludge process. The process was achieved by converting the existing aerated lagoon to a BNR activated sludge system. Upgrading of the aerated lagoon was completed in March 2012.
A flow diagramme of the works is included in Annexure B.
3.2 Wellington WWTW 3.2.1 Catchment
The Wellington WWTW services the entire Wellington area, from the Newton- and Erf 8000 areas in the south to the Pentz Domestic area in the north as well as the Industrial Park Area in the west of Wellington. The WWTW is a Class C WWTW under the DWA classifications and currently has a capacity of 6Mℓ/d with a ADDWF of approximately 5.5Mℓ/d. Upgrading of this WWTW to a capacity of 16 Mℓ/d is currently underway. The WWTW is licensed by a water usage permit (No 918B). A layout of the Wellington WWTW catchment area is shown on drawing no 0828/C/003 in Annexure A. As with the Paarl WWTW, the receiving environment for the effluent from the Wellington WWTW is also the Berg River and the Wellington WWTW most also comply with the General Standard. In future the WWTW may also need to comply with the Special Standard.
3.2.2 Collection
Influent to the Wellington WWTW is from various Sewage Pumping Stations conveying sewage to the WWTW via rising mains. The various pumping stations in the Wellington area are shown in table 3.2 below.
Table 3.2 : Sewage Pumping Station within Wellington
Name of Pumping Station Pumping station to/into
Erf 8000 Newton Sewage Pumping Station
Newton Directly to the WWTW Inlet
Wellington Industries Directly to the WWTW Inlet *(1)
Pentz Street Industrial and Domestic Pumping Stations
Directly to the WWTW Inlet *(1)
Nywerheids Park Directly to the WWTW Inlet *(2)
Kromrivier Collector Sewers draining towards the Pentz Street Domestic Pumping Station
*(1)
These two pumping stations will be consolidated into one large pumping station (Pentz Street Sewage Pumping Station). Construction is estimated to be completed by June 2013.
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*(2)
This pumping station was recently upgraded.
Currently the influent to the WWTW is not separately treated with respect to industrial- and domestic influent.
Some of the pumping stations and rising mains such as the Pentz Street Domestic- and Industrial Pumping Stations are old or at capacity and require replacement or upgrading. However for the most part of the reticulation network is in good condition and have a remaining useful life similar to that of the Paarl. Some re-use of effluent is already implemented with the Wellington Golf Club receiving irrigation water from the works. This is on a relatively small scale and amount. Similarly to Paarl WWTW, it is envisioned that further re-use of effluent for irrigation or large industrial use must occur in future. This process is in the Planning Phase in conjunction with the Paarl WWTW.
3.2.3 Treatment
The Wellington WWTW combines the biological wastewater treatment systems of trickling filters and activated sludge. Raw wastewater (consisting of domestic sewage and industrial effluent) flows through an inlet works to two primary settling tanks and then to five trickling filters (biofilters) of which two are large biofilters supplemented by three smaller biofilters. The effluent from the biofilters is settled in two humus tanks and the settled water is then pumped to the activated sludge bioreactor and a secondary settling tank. The final effluent is chlorinated before receiving tertiary treatment in five maturation ponds in series. The effluent from the last maturation pond discharges to a natural stream which flows to the Berg River. Waste sludge is either treated in two anaerobic digesters and then in sludge drying beds, or in two sludge lagoons. The WWTW is in need of upgrading and extension of the treatment capacity. Aurecon in association with Lyners was appointed in 2010 to investigate options for the required upgrading and extensions. The project is currently (2013) in the in the Planning and Environmental Impact assessment Phase.
A flow diagramme of the works is included in Annexure B.
3.3 Pearl Valley WWTW 3.3.1 Catchment
The Pearl Valley WWTW services the Pearl Valley Golf Estate and the Val-de-Vie Developments to the south of Paarl. The WWTW is a Class D works under the DWA classifications and currently has a capacity of 1Mℓ/d with a ADDWF of approximately 0.2Mℓ/d. This WWTW is licensed under a General Authorization (Ref 16/2/7/G100/A/8). A layout of the Pearl Valley WWTW catchment area is included in Annexure A drawing no 0828/C/001. Again the receiving environment for final effluent is the Berg River and the WWTW must also currently comply with the General Standard. It may also have to comply with the Special Standard in future.
3.3.2 Collection
Influent to this WWTW is domestic in nature and is conveyed to the WWTW via various Sewage Pumping Stations and Rising mains which are shown below in table 3.3.
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Table 3.3 : Sewage Pumping Stations in the Pearl Valley WWTW Catchment
Name of Pumping Station Pumping station to/into
Pearl Valley Directly to the WWTW Inlet
Val-de-Vie 3 Directly to the WWTW Inlet
Val-de-Vie 1,2,5 and 6- and the Guardhouse Pumping Stations
Collector sewers ultimately draining to Val-de-Vie 3 Pumping Station
These pumping stations and reticulation networks are relatively new and in good condition. 3.3.3 Treatment
The Pearl Valley WWTW’s consists of two nearly identical activated sludge modules. The first module (“old section”) was provided to treat the wastewater from the Pearl Valley Golf Estate, while the second module (“new section”) was added later to treat wastewater from the more recently established Val-de-Vie Development. Raw domestic sewage from the two private developments both enter the WWTWs in an inflow sump at the head of the works, from where it flows through a communal inlet works (hand raked screen; grit channels) to two activated sludge reactors. The reactors have been designed for biological nutrient removal and therefore include anoxic zones for denitrification. After the removal of the biomass (sludge) in the secondary settling tanks, the settled water is chlorinated and then polished in large maturation ponds before discharging to a natural water course leading to the Berg River. Waste sludge is disposed of in sludge drying beds. However, the system currently operates on a low MLSS, resulting in low waste sludge volumes to be disposed of. A mechanical sludge dewatering facility has also been provided at the WWTW, but to date this has not been used. A flow diagramme of the works is included in Annexure B.
3.4 Saron WWTW 3.4.1 Catchment
The Saron WWTW services the rural town of Saron north of Gouda. The WWTW is a Class E works under the DWA classification and currently has a capacity of 1Mℓ/d with a ADDWF of approximately 0.8Mℓ/d. The WWTW is licensed by a General Authorization. A conditional assessment of the works was undertaken which recommended upgrading of various structures at the works which include construction of a new activated sludge reactor. The first phase of the upgrading project is currently in the construction phase with a second phase currently (2013) in the planning and EIA phase. A layout of the Saron WWTW catchment is included in drawing no 0828/C/006 in Annexure A.
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The receiving environment for this works is the Klein Berg River which ultimately drains to the Berg River. This works is also subject to the General Standard for effluent and may in future be subject to the Special Standard.
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3.4.2 Collection
Influent to this WWTW is domestic in nature and is conveyed to the WWTW from a Sewage Pumping Station which was recently upgraded. There are only two Sewage Pumping Stations in Saron which operate as shown in the table 3.4 below.
Tabel 3.4 : Sewage pumping station in Saron.
Name of Pumping Station Pumping station to/into
Saron 1 Collector sewer draining towards Pumping Station
Saron 2 Directly into the Saron WWTW inlet works*
* Recently upgraded
Although most of the reticulation network is old it is still in good condition. As stated above the Saron 2 Sewage Pumping Station and Rising main was recently upgraded. The conditional assessment of the works found that the structures in the WWTW with the exception of the Secondary Settling tank (Clarifier) and the chlorination channel were not in a good condition. Therefore refurbishment and upgrading of the works was proposed.
3.4.3 Treatment
The Saron WWTW is also an activated sludge treatment works, but unlike the Paarl and Wellington WWTW, it is a relatively small plant with open ponds converted to an activated sludge reactor, with an aerobic zone and an anoxic zone. Raw sewage from Saron enters the works via the inlet works (hand raked screen followed by grit channels) to the anoxic zone of the activated sludge reactor. It overflows to the aeration section (with floating aerators) and then to a secondary settling tank. Return activated sludge is recycled to the anoxic zone, and waste activated sludge discharged to the sludge drying beds from time to time (daily sludge wasting is recommended). The settled wastewater from the secondary settling tank is firstly disinfected through chlorination and then normally flows to a series of maturation ponds, located some distance from the works. These ponds have become redundant and are in the process of being upgraded. As stated above this WWTW must be upgraded and refurbished. A flow diagramme of the works is included in Annexure B.
3.5 Hermon WWTW 3.5.1 Catchment
The Hermon WWTW services the small rural town of Hermon which is only partly serviced by gravity sewers with a Sewage Pumping Station. The other section of Hermon has conservancy tanks which are emptied by tanker trucks at regular intervals and the sewage from the tankers is then taken to the WWTW. The WWTW is a Class E works, under the DWA classification and currently has a capacity of 0.3Mℓ/d and a ADDWF of approximately 0.1Mℓ/d. This plant operates under a General Authorization from DWA (Ref 16/2/7/G/10F). A layout of the Hermon WWTW catchment is shown on drawing no 0828/C/004 in Annexure A. As the works is and evaporation pond system there is no effluent outflow.
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3.5.2 Collection
As stated above Hermon is only partially serviced with gravity sewers draining to the Hermon Sewage Pumping Station which conveys sewage to the WWTW. The other section of Hermon has conservancy tanks which are emptied by tanker truck at regular intervals and taken to the WWTW.
It is envisioned that in future the conservancy tanks will be made redundant by the installation of gravity sewers and a new Sewage Pumping Station.
The existing reticulation system is relatively old but still in good condition.
3.5.3 Treatment
The treatment system for Hermon is an evaporation pond system, consisting of two large, unlined evaporation ponds. Provision has been made for using the pond overflow for irrigation purposes (an irrigation pump has been installed for this purpose), but currently both the ponds are empty due to evaporation and possible seepage.
A flow diagramme of the works is included in Annexure A.
3.6 Gouda WWTW 3.6.1 Catchment
The Gouda WWTW services the rural town of Gouda to the north of Hermon. The WWTW is a Class E works under the DWA classification currently having a capacity of 0.64Mℓ/d and a ADDWF of approximately 0.4Mℓ/d. The works is currently licensed by a water use permit (No 1331B). As this works is also an evaporation pond system there is no effluent outflow. A layout of the Gouda WWTW catchment is included in Annexure A drawing no 0828/C/005.
3.6.2 Collection
In the past Gouda was divided into two sections Gouda north (north of the R45) was serviced by gravity sewers draining towards the Gouda Sewage Pumping Station which conveyed sewage to the WWTW. The Gouda South section was serviced by conservancy tanks with tanker trucks removing sewage to the WWTW regularly. Construction of a gravity sewer reticulation network for the Gouda South section is currently underway. This new reticulation network will drain to the Gouda North network, onto the Gouda Sewage Pumping Station and ultimately the Gouda WWTW. The Gouda North reticulation network is relatively old but still in good condition. A new Gouda Sewage Pumping Station and reticulation network for Gouda South was recently completed and are at the start of their service life.
3.6.3 Treatment
The Gouda WWTW is a waste stabilisation pond system (evaporation ponds) consisting of two primary ponds, followed by four secondary oxidation ponds. The final effluent overflowing from the last pond is used as irrigation water on the rugby field in town. Upgrading and rehabilitation of the pond system was recently completed, which included upgrading of the pump station in the town. A flow diagramme of the works is included in Annexure B.
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4 HAZARD ASSESSMENT
In 2011 DWA promoted the use of a W2RAP to identify risks at WWTW’s in detail and to this end all
of Drakenstein Municipality’s WWTW were analysed and a W2RAP drafted.
The W
2RAP is based on a risk factor which is obtained as a product of the perceived probability of
occurrence and the significance or consequence. A risk matrix must be set up to classify risks as low, medium or high.
4.1 Risk Matrix used
As stated above the risk factor is calculated as follows :
Risk factor = Probability of occurrence X significance or consequence
Based on this equation the following risk matrix and factors were used as shown in Figure 4.1 below.
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Figure 4.1 : Risk Matrix used for Hazard Assessment
Min Risk
2 7 8 13 14 19 20 24 25 26 30
Max Risk
Low Risk 2 to 13 Medium Risk 14 to 25 High Risk 25 to 30
Probability Score (Probability of Occurrence)
Severity Score
(Consequence of failure)
1 Rare
(1 in 5 years)
2 Insignificant (No Impact)
2 Unlikely
(once per annum)
3 Minor
(Minor Impact to a large population)
3 Moderately Likely (once per month)
4 Moderate
(Moderate Impact to a large population)
4 Likely
(once per week)
5 Major
(Population exposed to significant illness)
5 Almost Certain
(Once a day or permanent feature)
6 Catastrophic
(Death expected from exposure)
Risk Matrix
Severity
Risk Matrix
Severity
2 3 4 5 6
2 3 4 5 6
Probability
1 2 3 4 5 6
Probability
1 2 3 4 5 6
2 4 6 8 10 12
2 4 6 8 10 12
3 6 9 12 15 18
3 6 9 12 15 18
4 8 12 16 20 24
4 8 12 16 20 24
5 10 15 20 25 30
5 10 15 20 25 30
Based on this risk matrix all risks are classified on their probability (score between 2 and 5) and severity (score between 2 and 6) and ranked as Low, Medium or High.
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This formed the basis for the Hazard Assessment undertaken for each WWTW below.
4.2 Hazard Analysis of works
A Hazard Assessment was undertaken for each WWTW taking into account, among others, the following.
The catchment Surface water Ground water Collector systems Treatment Other factors
The risk analysis further also differentiated between four district risk categories for each section of the works namely :
Electrical failure (including motor failure, power failure, etc.)
Mechanical failure (eg gearboxes, sluices, gate valves, pumps, etc.)
Structural failure (eg structures needing replacement/refurbishment or upgrading)
Process failure (non-compliance with DWA Standards, Operational monitoring etc.)
Risk scores were allocated based mostly on the effect on the receiving environment and the end user. The risk assessment is also only a high level risk assessment and may be elaborated on in future revisions of this document.
4.3 Paarl WWTW The full risk matrix for the Paarl WWTW is included in Annexure C. The risk classified as Medium or High Risks are shown in table 4.1 below.
Table 4.1 : Paarl WWTW : Medium to High Risk Items Item no
System Hazard/Risk Description
Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Process Failure
11 Domestic Pumping
Station Influent compliance Y 4 5 20 Medium
12 Domestic Pumping
Station Design Capacity Y 4 5 20 Medium
Mechanical Failure
20 Industrial Inlet
Works Hand Raked Screens Y 5 3 15 Medium
Process Failure
21 Industrial Inlet
Works Influent compliance Y 4 5 20 Medium
Process Failure
27 Flocculator Operational Monitoring
Y 4 4 16 Medium
Electrical Failure
28 Flocculator Power failure to
bridge Y 3 5 15 Medium
Structural Failure
30 Domestic
splitterbox Tower Y 3 5 15 Medium
Process Failure
33 Domestic PST's Operational Monitoring
Y 4 4 16 Medium
Structural Failure
38 Biofilters Old Biofilter walls Y 5 5 25 High
Process Failure
39 Biofilters Operational Monitoring
Y 4 4 16 Medium
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Item no
System Hazard/Risk Description
Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Process Failure
43 Humus Tanks Operational Monitoring
Y 4 4 16 Medium
Process Failure
60 Aerobic Zone Operational Monitoring
Y 4 5 20 Medium
Process Failure
66 Clarifier Operational Monitoring
Y 4 5 20 Medium
Structural Failure
67 New Clarifier Clarifier Structure too
low Y 4 4 16 Medium
Structural Failure
77 Tanks Dome structure on
Tanks Y 5 5 25 High
Structural Failure
78 Digester Structure of digester Y 5 5 25 High
General
80 Digester Deep Structure Y 5 5 25 High
General
81 Incinerators Incinerators very old Y 4 4 16 Medium
Process Failure
84 Maturation Ponds Operational Monitoring
Y 4 5 20 Medium
Electrical Failure
85 Chlorination Store
Room Warning Lights outside building
Y 4 6 24 Medium
86 Chlorination Store
Room Dosing Electronics Y 4 6 24 Medium
Process Failure
89 Chlorination
Channel Compliance Monitoring
Y 5 5 25 High
Electrical Failure
91 Transformer Transformers on site
(4 No) Y 5 5 25 High
92 Genset Switch Over Board Y 4 5 20 Medium
General
94 General Site Lighting Y 3 5 15 Medium
95 General Telemetry at works Y 5 4 20 Medium
The risks mainly include operational- and compliance monitoring, replacement or upgrading of structures and dangerous installations such as chlorination storage. These risk are or can be mitigated by employing risk mitigation measures which are shown in table 4.2 below.
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Table 4.2 : Paarl WWTW : Risk Mitigation Measures for Medium to High Risks
Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls) Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment Recommended mitigation/
improvement plan
Process Failure
11 Domestic Pumping
Station Influent
compliance 20 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 4 Low Operational monitoring is to occur to
operational monitoring alert level Ensure monitoring occurs as
scheduled
12 Domestic Pumping
Station Design Capacity 20 Medium - 0 20 Medium
The existing Pumping Station has a lower capacity than newly
constructed sewer
Investigate New pumping station with higher capacity
Mechanical
Failure
20 Industrial Inlet
Works Hand Raked
Screens 15 Medium
Permanent Cleaning of Screen throughout the day
70 4.5 Low Permanently posted staff clean hand
raked screen Investigate installation of
mechanical screens in future
Process Failure
21 Industrial Inlet
Works Influent
compliance 20 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 4 Low Operational monitoring is to occur to
operational monitoring alert level Ensure monitoring occurs as
scheduled
Process Failure
27 Flocculator Operational Monitoring
16 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 3.2 Low Operational monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Electrical Failure
28 Flocculator Power failure to
bridge 15 Medium - 0 15 Medium
No power to the bridge at present and process is being affected
Power to be provided to bridge immediately
Structural
Failure
30 Domestic
splitterbox Tower 15 Medium - 0 15 Medium Tower must be investigated
Investigate structure of tower and gratings
Process Failure
33 Domestic PST's Operational Monitoring
16 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 3.2 Low Operational monitoring needed with
Actions as per Alert Level Follow Alert Level actions
Structural
Failure
38 Biofilters Old Biofilter
walls 25 High Structure strapping 10 22.5 Medium
currently strapping is used to reinforce broken brickwork outer
walls
Refurbish walls as part of future upgrade
Process Failure
39 Biofilters Operational Monitoring
16 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 3.2 Low Operational monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Process Failure
43 Humus Tanks Operational Monitoring
16 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 3.2 Low Operational monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Process Failure
60 Aerobic Zone Operational Monitoring
20 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 4 Low Operational Monitoring to determine
sludge wasting
Operational Monitoring as scheduled with process
adjustments at alert levels as necessary
Process Failure
66 Clarifier Operational Monitoring
20 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 4 Low Operational monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Structural
Failure
67 New Clarifier Clarifier
Structure too low
16 Medium - 0 16 Medium
The clarifier structure was constructed low in the ground and
the possibility exists for someone to fall into the clarifier as there is no
handrail around the clarifier
Construct handrail around clarifier with apron
Structural
Failure
77 Tanks Dome structure
on Tanks 25 High
Signage, Gas traps and 24h monitoring
80 5 Low
Inspection of the dome must occur at regular interval as determined by a structural
Engineer
Structural
Failure
78 Digester Structure of
digester 25 High
Signage, Gas traps and 24h monitoring
80 5 Low
Inspection of the dome must occur at regular interval as determined by a structural
Engineer
General
80 Digester Deep Structure 25 High - 0 25 High No life buoy or safety ropes in a very
deep structure Provide life buoys and safety
ropes for structure
General
81 Incinerators Incinerators
very old 16 Medium - 0 16 Medium
The incinerators are very old and parts have become hard to source
Upgrade of the incinerators must be investigated as part of future
upgrade
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls) Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment Recommended mitigation/
improvement plan
Process Failure
84 Maturation Ponds Operational Monitoring
20 Medium
Operational Monitoring through on site Mini Lab.,
weekly verification at Paarl WWTW lab. and Monthly Audit by Independent Lab.
(A.L. Abbott)
80 4 Low Operational monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Electrical Failure
85 Chlorination Store
Room Warning Lights outside building
24 Medium
Warning lights checked daily, with Reactive Maintenance and Standby Generator on
Site
100 0 None Weekly inspection of
Component
86 Chlorination Store
Room Dosing
Electronics 24 Medium
Reactive Maintenance and Standby Generator on Site
80 4.8 Low Weekly inspection of
Component
Process Failure
89 Chlorination
Channel Compliance Monitoring
25 High 24h Compliance Monitoring
with on site lab. Newly refurbished
90 2.5 Low Compliance Monitoring to occur to
alert levels with corrective actions as per Alert Level
Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Electrical Failure
91 Transformer Transformers on
site (4 No) 25 High
Operation and Maintenance from Drakenstein Electrical
Department 0 25 High
Drakenstein Electrical Department is laboring under capacity constraints and maintenance cannot always be
effected in time
Maintenance schedule for all transformers which MUST be
adhered to and additional staffing in the Electrical
Department
92 Genset Switch Over
Board 20 Medium - 0 20 Medium
The existing switch board is old and is in need of upgrading with new
switchgear, etc.
Investigate upgrading of switch board as part of future upgrade
of works
General
94 General Site Lighting 15 Medium Existing high mast lighting 50 7.5 Low Investigate additional high mast
lighting when required
95 General Telemetry at
works 20 Medium 0 20 Medium
Contractor appointed to upgrade entire telemetry network
Monitor contractor performance and telemetry performance after
commissioning
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If these mitigation measures are implemented the overall risk classification of the works may be regarded as low. 4.4 Pearl Valley WWTW
The full risk matrix for the Pearl Valley WWTW is included in Annexure C. The risk classified as Medium or High Risks are shown in table 4.3 below.
Table 4.3 : Pearl Valley WWTW : Medium to High Risk Items Item no
System Hazard/Risk Description
Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Electrical Failure
33 Chlorination Store
Room Warning Lights outside building
Y 4 6 24 Medium
34 Chlorination Store
Room Dosing Electronics Y 4 6 24 Medium
Process Failure
38 Maturation Ponds Compliance Monitoring
Y 5 5 25 High
Electrical Failure
42 Pumping Station Power failure Y 5 4 20 Medium
43 Pumping Station Telemetry Y 4 5 20 Medium
Mechanical Failure
44 Sludge Drying
Beds Drainage Pump Y 4 4 16 Medium
General
45 General Security at works Y 4 6 24 Medium
46 General Office Facilities Y 5 6 30 High
The risks mainly include operational- and compliance monitoring, upgrading of structures and dangerous installations such as chlorination storage.
These risk are or can be mitigated by employing risk mitigation measures which are shown in table
4.4 below. Table 4.4 : Pearl Valley WWTW : Risk Mitigation Measures for Medium to High Risks
Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
Electrical Failure
33 Chlorination Store Room
Warning Lights
outside building
24 Medium
Reactive Maintenance and Standby Generator on
Site
80 4.8 Low
An audit has been
performed and corrective
measures have been
identified.
Weekly inspection of Component
34 Chlorination Store Room
Dosing Electronics
24 Medium
Reactive Maintenance and Standby Generator on
Site
80 4.8 Low
An audit has been
performed and corrective
measures have been
identified.
Weekly inspection of Component
Process Failure
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
38 Maturation
Ponds Compliance Monitoring
25 High
Compliance Monitoring
through on site Mini Lab.,
weekly verification at Paarl WWTW
lab. and Monthly Audit
by Independent Lab. (A.L.
Abbott) and Maturation
Pond Maintenance
80 5 Low
Compliance monitoring to occur to alert
levels with corrective
actions as per Alert Level,
Algal problems occurred in
retention pond and retention
time was reduced, however sediment transport remains
problematic
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed
Electrical Failure
42 Pumping Station
Power failure
20 Medium
Standby generator on
site & Overflow pond
90 2 Low -
Pro-Active Maintenance Required & servicing of
standby generator required
43 Pumping Station
Telemetry 20 Medium - 0 20 Medium
Contractor appointed to
upgrade entire telemetry network
Monitor contractor
performance and telemetry performance
after commissioning
Mechanical
Failure
44 Sludge
Drying Beds Drainage
Pump 16 Medium
Reactive Maintenance
100 0 None New Pump Currently sourced
Monitor supplier
performance and pump
performance after
commissioning
General
45 General Security at
works 24 Medium - 0 24 Medium
No Security on site
Provide security guard and
facilities as part of the future
upgrade
46 General Office
Facilities 30 High - 0 30 High
No office on site. Non-
Compliance with OSH Act
Provide office facilities as part
of the future upgrade
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If these mitigation measures are implemented the overall risk classification of the works may be regarded as low 4.5 Wellington WWTW The full risk matrix for the Wellington WWTW is included in Annexure C. The risk classified as Medium or High Risks are shown in table 4.5 below.
Table 4.5 : Wellington WWTW : Medium to High Risk Items Item no
System Hazard/Risk Description Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Electrical Failure
1 Pumping Station Power failure Y 5 5 25 High
Process Failure
2 Pumping Station Flow meter Y 3 5 15 Medium
Mechanical Failure
3 Pumping Station Screening of Sewage Y 4 5 20 Medium
General
6 Pumping Station No permanent
supervision Y 5 5 25 High
General
11 Pumping Station Security Y 5 5 25 High
General
12 Pumping Station Design Capacity
Exceedance Y 3 5 15 Medium
Mechanical Failure
14 Pumping Station Screening of Sewage Y 3 5 15 Medium
General
17 Pumping Station Security Y 5 5 25 High
18 Pumping Station Telemetry at pumping
Station Y 3 5 15 Medium
General
21 General Plant Design Capacity
Exceedance Y 5 5 25 High
Electrical Failure
22 Inlet Works Power failure Y 5 5 25 High
Process Failure
26 Inlet Works Influent compliance Y 4 5 20 Medium
Process Failure
31 PST's Operational Monitoring Y 4 4 16 Medium
Process Failure
37 Biofilters Operational Monitoring Y 4 4 16 Medium
Process Failure
43 Humus Tanks Operational Monitoring Y 4 4 16 Medium
Process Failure
55 Aerobic Zone Operational Monitoring Y 4 5 20 Medium
Process Failure
59 Clarifier Operational Monitoring Y 4 5 20 Medium
Electrical Failure
66 Chlorination Store
Room Warning Lights outside
building Y 5 5 25 High
67 Chlorination Store
Room Dosing Electronics Y 5 5 25 High
Process Failure
70 Maturation Ponds Compliance Monitoring Y 5 5 25 High
General
71 Sludge Drying
Beds Design Capacity
Exceedance Y 5 5 25 High
General
72 Digester No Gas Tank Y 4 5 20 Medium
General
73 Incinerator No incinerator on site
for screenings Y 4 5 20 Medium
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Item no
System Hazard/Risk Description Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
General
74 Personnel Facilities
Offices Y 4 5 20 Medium
75 General Telemetry at works Y 5 4 20 Medium
76 General Site Lighting Y 5 4 20 Medium
77 General Security Y 5 5 25 High
78 General Signage Y 5 5 25 High
The risks mainly include operational- and compliance monitoring, upgrading of structures, inadequate capacity, no standby electricity generation and dangerous installations such as chlorination storage. These risk are or can be mitigated by employing risk mitigation measures which are shown in table
4.6 below.
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Table 4.6 : Wellington WWTW : Risk Mitigation Measures for Medium to High Risks
Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration of any controls)
Existing controls Control
Effectiveness (%) Residual Risk
Score Comment Recommended mitigation/ improvement plan
Electrical Failure
1 Pumping Station Power failure 25 High - 0 25 High No Standby Generator on site, Urgently required as this is the closest
pumping station to the Berg River
Process Failure
2 Pumping Station Flow meter 15 Medium - 0 15 Medium Flow meter has not been commissioned
Mechanical Failure
3 Pumping Station Screening of Sewage 20 Medium Basket screen, inspected daily according to pumping station checklist 90 2 Low -
General
6 Pumping Station No permanent
supervision 25 High Daily inspections only 0 25 High Supervision required as pumping station is closest to Berg River
General
11 Pumping Station Security 25 High 3m high wall with barbed wire, fencing, security lights and Armed response 80 5 Low High vandalism rate at this pumping station forced extreme security
measures
General
12 Pumping Station Design Capacity
Exceedance 15 Medium - 0 15 Medium Capacity problems observed in past
Mechanical Failure
14 Pumping Station Screening of Sewage 15 Medium - 0 15 Medium Contract has been issued for provision of a mechanical screen
General
17 Pumping Station Security 25 High Broken fencing and Armed response 25 18.75 Medium High vandalism rate at this pumping station requires security measures
18 Pumping Station Telemetry at pumping
Station 15 Medium - 0 15 Medium
Telemetry required as pumping station is closest to Berg River, Contractor appointed to upgrade entire telemetry network
General
21 General Plant Design Capacity
Exceedance 25 High 0 25 High
Upgrading of Plant Required, All flows pumped to WWTW therefor also may need a balancing dam
Electrical Failure
22 Inlet Works Power failure 25 High No Standby Generator on site - 0 25 High No Standby Generator on Site
Process Failure
26 Inlet Works Influent compliance 20 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) - 80 4 Low Operational monitoring is to occur to operational monitoring alert level
Process Failure
31 PST's Operational Monitoring 16 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) - 80 3.2 Low Operational monitoring needed with Actions as per Alert Level
Process Failure
37 Biofilters Operational Monitoring 16 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) 80 3.2 Low
Operational monitoring to occur to alert levels with corrective actions as per Alert Level
Process Failure
43 Humus Tanks Operational Monitoring 16 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) 80 3.2 Low
Operational monitoring to occur to alert levels with corrective actions as per Alert Level
Process Failure
55 Aerobic Zone Operational Monitoring 20 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) 80 4 Low Operational Monitoring to determine sludge wasting
Process Failure
59 Clarifier Operational Monitoring 20 Medium Operational Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) 80 4 Low
Operational monitoring to occur to alert levels with corrective actions as per Alert Level
Electrical Failure
66 Chlorination Store
Room Warning Lights outside
building 25 High
Reactive Maintenance and No Standby Generator on Site, Inspection completed and Certificate for compliance obtained
90 2.5 Low A Standby Generator on site is imperative
67 Chlorination Store
Room Dosing Electronics 25 High
Reactive Maintenance and No Standby Generator on Site, Inspection completed and Certificate for compliance obtained
90 2.5 Low A Standby Generator on site is imperative
Process Failure
70 Maturation Ponds Compliance Monitoring 25 High Compliance Monitoring through on site Mini Lab., weekly verification at Paarl
WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott) 80 5 Low
Compliance monitoring to occur to alert levels with corrective actions as per Alert Level
General
71 Sludge Drying
Beds Design Capacity
Exceedance 25 High - 0 25 High 2 Waste ponds, Large Sludge Volume coming into works.
General
72 Digester No Gas Tank 20 Medium - 0 20 Medium The plant has Gas Digesters but no gas tank. A waste to energy project
has been initiated which could utilize the gas
General
73 Incinerator No incinerator on site for
screenings 20 Medium Screenings conveyed to Paarl WWTW for Incineration 50 10 Low -
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration of any controls)
Existing controls Control
Effectiveness (%) Residual Risk
Score Comment Recommended mitigation/ improvement plan
General
74 Personnel Facilities
Offices 20 Medium Some office space provided with limited ablution facilities 10 18 Medium Existing facilities do not comply with OSH Act
75 General Telemetry at works 20 Medium 0 20 Medium Contractor appointed to upgrade entire telemetry network
76 General Site Lighting 20 Medium Existing Lighting on site 50 10 Low Site lighting may be insufficient
77 General Security 25 High Existing Fence 25 18.75 Medium Contract for a new security fence has been issued and is underway
78 General Signage 25 High - 0 25 High Signage is required on site to comply with various statutory regulations
including the OSH Act
If these mitigation measures are implemented the overall risk classification of the works may be regarded as low
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4.6 Hermon WWTW
The full risk matrix for the Hermon WWTW is included in Annexure C.
The risk classified as Medium or High Risks are shown in table 4.7 below
Table 4.7 : Hermon WWTW : Medium to High Risk Items
Item no
System Hazard/Risk Description Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Process Failure
1 Inlet Influent compliance Y 4 5 20 Medium
Process Failure
6 Evaporation
pond 3 Operational Monitoring
Y 4 5 20 Medium
7 Evaporation
Ponds Ground Water
Monitoring Wells Y 4 5 20 Medium
Structural Failure
8 Sump Structure Sump Structure Size Y 3 5 15 Medium
Mechanical Failure
9 Pumps Pump Failure Y 3 5 15 Medium
Electrical Failure
10 Pumps No Standby Power Y 5 5 25 High
General
11 General Telemetry at Pumping
Station Y 5 4 20 Medium
The risks mainly consist only of operational- and compliance monitoring as the ponds are oxidation ponds and do not have any mechanical equipment. These risk are or can be mitigated by employing risk mitigation measures which are shown in table
4.8 below. Table 4.8 : Hermon WWTW : Risk Mitigation Measures for Medium to High Risks
Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
Process Failure
1 Inlet Influent
compliance 20 Medium
Operational monitoring
i.e. Laboratory
testing
80 4 Low
Operational monitoring is
to occur to operational monitoring alert level
Ensure monitoring occurs as scheduled
Process Failure
6 Evaporation
pond 3 Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
Investigate need for Mini Lab. On
site
7 Evaporation
Ponds
Ground Water
Monitoring Wells
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
Structural
Failure
8 Sump
Structure
Sump Structure
Size 15 Medium
Daily inspection of
sump according to
Pumping Station
checklist
25 11.25 Low
Current sump structure to
large and has overflow
walls and no Mechanical
screen. Screenings
accumulate in first chamber and must be
manually removed
Investigate upgrade of
pumping station and installation of Mechanical
Screen
Mechanical
Failure
9 Pumps Pump Failure
15 Medium
Reactive maintenance with 24h turn around time
50 7.5 Low
Pumps may experience
problems due to screenings clogging the
pumps
In the interm continue daily
inspections and Investigate upgrade of
pumping station and installation of Mechanical
Screen in future
Electrical Failure
10 Pumps No Standby
Power 25 High - 0 25 High
At the moment no
Standby Power at the
pumping station
Investigate supply of
standby power generator at
pumping station
General
11 General Telemetry
at Pumping Station
20 Medium 0 20 Medium
Contractor appointed to
upgrade entire
telemetry network
Monitor contractor
performance and telemetry performance
after commissioning
If these mitigation measures are implemented the overall risk classification of the works may be regarded as low
4.7 Saron WWTW The full risk matrix for the Saron WWTW is included in Annexure C.
The risk classified as Medium or High Risks are shown in table 4.9 below
Table 4.9 : Saron WWTW : Medium to High Risk Items
Item no
System Hazard/Risk Description
Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Electrical Failure
1 Inlet Works Power failure Y 5 5 25 High
Mechanical Failure
4 Inlet Works Hand Raked Screens Y 5 3 15 Medium
Process Failure
6 Inlet Works Influent compliance Y 4 5 20 Medium
7 Inlet Works Design Capacity N 4 5 20 Medium
Structural Failure
8 Inlet Works Inlet Works Structure Y 3 5 15 Medium
Electrical Failure
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Item no
System Hazard/Risk Description
Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
9 Anaerobic Zone Mixer Motors Y 4 4 16 Medium
Mechanical Failure
10 Anaerobic Zone Mixer Gearbox Y 4 4 16 Medium
Structural Failure
11 Anaerobic Zone Zone Structure Y 4 4 16 Medium
Electrical Failure
12 Aerobic Zone Aerator Motors Y 4 4 16 Medium
Mechanical Failure
13 Aerobic Zone Aerator Gearbox Y 4 4 16 Medium
Process Failure
14 Aerobic Zone Operational Monitoring
Y 4 5 20 Medium
Structural Failure
17 Clarifier Clarifier Structure Y 3 5 15 Medium
Process Failure
18 Clarifier Operational Monitoring
Y 4 5 20 Medium
Mechanical Failure
20 Pumping Station Pumps Y 5 5 25 High
Electrical Failure
22 Chlorination Store
Room Warning Lights outside building
Y 5 5 25 High
23 Chlorination Store
Room Dosing Electronics Y 5 5 25 High
Structural Failure
24 Chlorination Store
Room Store Room Structure Y 5 5 25 High
Structural Failure
25 Maturation Ponds Structures across river Y 4 4 16 Medium
Process Failure
26 Maturation Ponds Compliance Monitoring
Y 4 5 20 Medium
Structural Failure
27 Sludge Drying
Beds Bed Structures Y 4 6 24 Medium
Process Failure
28 Sludge Drying
Beds Filter Medium Y 5 3 15 Medium
General
29 General Telemetry at works Y 5 4 20 Medium
30 General Security Guard at
works Y 5 4 20 Medium
31 General Site Lighting Y 5 4 20 Medium
The risks mainly include operational- and compliance monitoring, upgrading of structures, inadequate capacity, no standby electricity generation and dangerous installations such as chlorination storage. As stated earlier in the document Saron WWTW required upgrading and it is therefore expected to identify so many risks These risks however, can be mitigated by employing risk mitigation measures which are shown in table 4.10 below.
25
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Table 4.10 : Saron WWTW : Risk Mitigation Measures for Medium to High Risks Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration of any controls)
Existing controls Control
Effectiveness (%) Residual Risk
Score Comment Recommended mitigation/ improvement plan
Electrical Failure
1 Inlet Works Power failure 25 High No Standby generator on site 0 25 High No Standby Generator on site Install Standby Generator as part of WWTW upgrade.
Contractor appointed and supply of generator imminent
Mechanical Failure
4 Inlet Works Hand Raked
Screens 15 Medium Permanent Cleaning of Screen throughout the day 70 4.5 Low
Permanently posted staff clean hand raked screen and a new Mechanical screen will be provided at the Saron Sewage pumping
station in new contract
Monitor screenings amount after commissioning of mechanical screen at Saron Sewage pumping station
Process Failure
6 Inlet Works Influent
compliance 20 Medium
Operational Monitoring through on site Mini Lab., weekly verification at Paarl WWTW lab. and Monthly Audit by
Independent Lab. (A.L. Abbott) 90 2 Low
Operational monitoring is to occur to operational monitoring alert level
Ensure monitoring occurs as scheduled
7 Inlet Works Design Capacity 20 Medium 0 20 Medium Upgrade needed of inlet works Upgrade inlet Works as part of WWTW upgrade
Structural Failure
8 Inlet Works Inlet Works Structure
15 Medium Inspection of Structure 0 15 Medium Upgrade needed of inlet works Upgrade inlet Works as part of WWTW upgrade
Electrical Failure
9 Anaerobic Zone Mixer Motors 16 Medium Reactive Maintenance 90 1.6 None Reactive maintenance at the present with 24h turn around time Replaced Mixer and now Pro-Active Maintenance and
Servicing
Mechanical Failure
10 Anaerobic Zone Mixer Gearbox 16 Medium Reactive Maintenance 90 1.6 None Reactive maintenance at the present with 24h turn around time Replaced Mixer and now Pro-Active Maintenance and
Servicing
Structural Failure
11 Anaerobic Zone Zone Structure 16 Medium 0 16 Medium New Reactor must be constructed as part of WWTW upgrade Construct new Reactor as part of WWTW upgrade
Electrical Failure
12 Aerobic Zone Aerator Motors 16 Medium Reactive Maintenance 90 1.6 None Reactive maintenance at the present with 24h turn around time Hour Logging, Pro-Active Maintenance and Servicing or possible standby Aerator. Also investigate timer for low
flow periods
Mechanical Failure
13 Aerobic Zone Aerator Gearbox 16 Medium Reactive Maintenance 90 1.6 None Reactive maintenance at the present with 24h turn around time Hour Logging, Pro-Active Maintenance and Servicing or possible standby Aerator. Also investigate timer for low
flow periods
Process Failure
14 Aerobic Zone Operational Monitoring
20 Medium Operational Monitoring through on site Mini Lab., weekly
verification at Paarl WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott)
90 2 Low Operational Monitoring to determine sludge wasting Operational Monitoring as scheduled with process
adjustments at alert levels as necessary
Structural Failure
17 Clarifier Clarifier Structure 15 Medium Inspection of Structure 0 15 Medium Inspection must occur during cleaning, Cracks observed on outside. Inspect structure during cleaning, perform structural
investigation with report
Process Failure
18 Clarifier Operational Monitoring
20 Medium Operational Monitoring through on site Mini Lab., weekly
verification at Paarl WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott)
90 2 Low Operational monitoring to occur to alert levels with corrective
actions as per Alert Level Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Mechanical Failure
20 Pumping Station Pumps 25 High Standby Pump Available but not in sump 25 18.75 Medium Standby pump on site but not installed in sump Investigate installation of standby pump in sum as part of
future upgrade
Electrical Failure
22 Chlorination Store Room
Warning Lights outside building
25 High Reactive Maintenance and No Standby Generator on Site 50 12.5 Low Entire system will be replaced with Chlorine tablet system until
future upgrade is completed Coordinate a new disinfection system with future upgrade
of works
23 Chlorination Store Room
Dosing Electronics 25 High Reactive Maintenance and No Standby Generator on Site 50 12.5 Low Entire system will be replaced with Chlorine tablet system until
future upgrade is completed Coordinate a new disinfection system with future upgrade
of works
Structural Failure
24 Chlorination Store Room
Store Room Structure
25 High Inspection of Structure 50 12.5 Low Entire system will be replaced with Chlorine tablet system until
future upgrade is completed Coordinate a new disinfection system with future upgrade
of works
Structural Failure
25 Maturation
Ponds Structures across
river 16 Medium 0 16 Medium
Structure across river may have leakages in crossing, relining of 1st pond currently (2012) underway
Construct new Maturation ponds closer to the WWTW as part of upgrading of WWTW
Process Failure
26 Maturation
Ponds Compliance Monitoring
20 Medium Operational Monitoring through on site Mini Lab., weekly
verification at Paarl WWTW lab. and Monthly Audit by Independent Lab. (A.L. Abbott)
90 2 Low Compliance monitoring to occur to alert levels with corrective
actions as per Alert Level Ensure Monitoring occurs as scheduled and incident
management protocol is followed
Structural Failure
27 Sludge Drying
Beds Bed Structures 24 Medium 0 24 Medium Contractor appointed to refurbish the beds All beds to be refurbished
Process Failure
28 Sludge Drying
Beds Filter Medium 15 Medium 0 15 Medium
Water does not filter through quick enough, Contractor appointed to refurbish the beds
All beds to be refurbished, monitor speed of water filtration after refurbishments are complete
General
29 General Telemetry at works 20 Medium 0 20 Medium Contractor appointed to upgrade entire telemetry network Monitor contractor performance and telemetry
performance after commissioning
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration of any controls)
Existing controls Control
Effectiveness (%) Residual Risk
Score Comment Recommended mitigation/ improvement plan
30 General Security Guard at
works 20 Medium 0 20 Medium No security guard at the works.
Provide security guard and facilities as part of the future upgrade
31 General Site Lighting 20 Medium 0 20 Medium Minimal site lighting Additional site lighting must be provided as part of future
upgrade
If these mitigation measures are implemented the overall risk classification of the works may be regarded as Medium and therefore motivates the upgrades currently in progress.
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4.8 Gouda WWTW
The full risk matrix for the Gouda WWTW is included in Annexure C. The risk classified as Medium or High Risks are shown in table 4.11 below
Table 4.11 : Gouda WWTW : Medium to High Risk Items Item no
System Hazard/Risk Description Could this issue result in a risk?
Likelihood Consequence Inherent Risk Score (before
consideration of any controls)
Electrical Failure
2 Pumping Station
Standby power Y 5 5 25 High
Process Failure
4 Inlet Influent compliance Y 4 5 20 Medium
Mechanical Failure
5 Inlet Hand Raked Screens Y 5 3 15 Medium
Process Failure
1 Inlet Spetic tank influent
compliance Y 4 5 20 Medium
Process Failure
10 Primary Pond 1 Operational Monitoring
Y 4 5 20 Medium
11 Primary Pond 2 Operational Monitoring
Y 4 5 20 Medium
12 Secondary
Pond 3 Operational Monitoring
Y 4 5 20 Medium
13 Secondary
Pond 4 Operational Monitoring
Y 4 5 20 Medium
14 Secondary
Pond 5 Operational Monitoring
Y 4 5 20 Medium
15 Secondary
Pond 6 Compliance Monitoring Y 5 5 25 High
16 Evaporation
Ponds Ground Water
Monitoring Wells Y 4 5 20 Medium
General
17 General Telemetry at works Y 5 4 20 Medium
18 General Security Guard at
works Y 5 4 20 Medium
19 General Site Lighting Y 5 4 20 Medium
The risks mainly consist only of operational- and compliance monitoring as the ponds are oxidation ponds and do not have much mechanical equipment.
These risks however, can be mitigated by employing risk mitigation measures which are shown in table 4.12 below.
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Table 4.12 : Gouda WWTW : Risk Mitigation Measures for Medium to High Risks
Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
Electrical Failure
2 Pumping Station
Standby power
25 High - 0 25 High
No Standby Power
generator available on
site
A standby power generator must be provided for
the pumping station
Process Failure
4 Inlet Influent
compliance 20 Medium
Operational monitoring
through weekly testing as there is no
effluent outflow from
this evaporation pond system
90 2 Low
Operational monitoring is
to occur to operational monitoring alert level
Ensure monitoring occurs as scheduled
Mechanical
Failure
5 Inlet Hand Raked
Screens 15 Medium
Permanent Cleaning of
Screen throughout
the day
90 1.5 None
Permanently posted staff clean hand
raked screen, however low
screenings volume due to
mechnical screen at
Gouda Sewage Pumping Station
Clean Screen Daily
Process Failure
1 Inlet Spetic tank
influent compliance
20 Medium - 0 20 Medium
No monitoring of farms septic tank loadings
(e.g. COD, etc.)
Sampling of farm septic tanks
inffluent must be performed to
gauge impact on process
Process Failure
10 Primary Pond 1
Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
11 Primary Pond 2
Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
12 Secondary
Pond 3 Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
13 Secondary
Pond 4 Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
14 Secondary
Pond 5 Operational Monitoring
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
15 Secondary
Pond 6 Compliance Monitoring
25 High
Compliance Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2.5 Low
Compliance monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
16 Evaporation
Ponds
Ground Water
Monitoring Wells
20 Medium
Operational Monitoring
weekly sampling with
monthly audits by
independent lab. (A.L. Abbott)
90 2 Low
Operational monitoring to occur to alert
levels with corrective
actions as per Alert Level
Ensure Monitoring occurs as
scheduled and incident
management protocol is followed,
investigate feasibility of Mini
lab. On site
General
17 General Telemetry at works
20 Medium 0 20 Medium
Contractor appointed to
upgrade entire telemetry network
Monitor contractor
performance and telemetry
performance after
commissioning
18 General Security Guard at
works 20 Medium 0 20 Medium
No security guard at the
works.
Provide security guard and
facilities as part of the future
upgrade
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Item no
System Hazard/Risk Description
Inherent Risk Score (before consideration
of any controls)
Existing controls
Control Effectiveness
(%)
Residual Risk Score
Comment
Recommended mitigation/
improvement plan
19 General Site Lighting 20 Medium 0 20 Medium Minimal site
lighting
Additional site lighting must be provided as part
of future upgrade
If these mitigation measures are implemented the overall risk classification of the works may be regarded as low
5 CONTROL MEASUREMENTS
The municipality conducts operational control of the WWTW’s according to a comprehensive operational monitoring program, which meets the minimum requirement of DWA as stipulated in the Green Drop certification criteria. Sampling is done on a frequent basis by the treatment plant personnel at the various WWTW’s, and analysed in a well-equipped laboratory situated at the Paarl WWTW. The operational monitoring programme of Drakenstein Municipality is summarised in the table 5.1 below:
Table 5.1 : Drakenstein Municipality’s Operational Monitoring Programme
Industries (Monitoring Intervals) WWTWs (Monitoring Intervals)
Paarl Weekly Paarl Weekly, 24 hrs Tuesday to Wednesday. Final
effluent weekly
Wellington Two Weekly Wellington
Two Weekly, 24 hrs Wednesday to Thursday. Final effluent weekly
Smaller WWTW’s Final effluent twice per week
Industries (Analysis) WWTW’s (Analysis)
pH, Electrical Conductivity, COD, Phosphates See Table 5.2
WWTW’s Sampling Points
Paarl
Industrial raw inlet, Industrial raw settled, Domestic raw inlet, Domestic raw settled, Biofilters (5 sets) inlet and outlet, Humus settling tanks (5) outlet, Combined humus tank effluent (to activated sludge), Clarifiers (2) outlet, Maturation (aeration) pond, Final effluent to the Berg River (chlorinated), Activated sludge MLSS
Wellington Raw inlet, Raw inlet settled (3 Primary settling tanks), Biofilters (5 sets) inlet and outlet, Humus settling tanks (2) outlet, Clarifiers (2) outlet, Retention pond, Final effluent to the Berg River (chlorinated), Activated sludge MLSS
Pearl Valley Raw inlet, Clarifier, Final effluent, Activated sludge MLSS
Saron Raw inlet, Clarifier, Final effluent, Activated sludge MLSS
Gouda Oxidation ponds outlets (7)
Hermon Raw inlet, Final effluent
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Table 5.2: Drakenstein Municipality’s Sample Analysis Details
WWTW Sampling point Frequency of
sampling Analyses performed on the samples
Paarl
Industrial raw inlet Weekly COD, pH, EC, tot.alk., settleable solids, ammonia, phosphate, Cd, Cr, Cu, Ni, Zn K, Na, Pb
Industrial raw settled Weekly COD, pH, EC, ammonia, phosphate
Domestic raw inlet Weekly COD, pH, EC, tot.alk., settleable solids, ammonia, phosphate, Cd, Cr, Cu, Ni, Zn K, Na, Pb
Domestic raw settled Weekly COD, pH, EC, ammonia, phosphate
Biofilters (5 sets) inlet and outlet)
Weekly COD, pH, EC
Humus settling tanks (5) outlet Weekly COD, pH, EC
Combined humus tank effluent (to activated sludge)
Weekly COD, pH, EC
Clarifiers (2) outlet Weekly COD, pH, EC
Maturation (aeration) pond Weekly COD, pH, EC, dissolved oxygen, temp, ammonia, phosphate
Final effluent to Berg river (chlorinated)
Daily COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp, Cl
-,
Cd, Cr, Cu, Ni, Zn K, Na, Pb, tot.Cl2
Activated sludge MLSS Daily suspended solids
Wellington
Raw inlet Daily COD, pH, EC, tot.alk., settleable solids, ammonia, phosphate, Cd, Cr, Cu, Ni, Zn K, Na, Pb
Raw inlet settled
(3 primary settling tanks) Weekly COD, pH, EC, tot.alk., ammonia, phosphate
Biofilters (5 sets) inlet and outlet
Weekly COD, pH, EC
Humus Settling tanks (2) outlet Weekly COD, pH, EC
Clarifiers (2) outlet Daily COD, pH, EC
Retention pond Weekly COD, pH, EC
Final effluent to Berg river (chlorinated)
Daily COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp, Cl
-,
Cd, Cr, Cu, Ni, Zn K, Na, Pb, tot.Cl2
Activated sludge MLSS Daily suspended solids
Pearl Valley
Raw inlet 2/week COD, pH, EC, ammonia, phosphate, Cd, Cr, Cu, Ni, Zn K, Na, Pb
Clarifier 2/week COD, pH, EC
Final effluent 2/week COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp, Cl
-,
Cd, Cr, Cu, Ni, Zn K, Na, Pb, tot.Cl2
Activated sludge MLSS 2/week suspended solids
Saron
Raw inlet 2/week COD, pH, EC, tot.alk., ammonia, phosphate
Clarifier 2/week COD, pH, EC
Final effluent 2/week COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp, Cl-,
Cd, Cr, Cu, Ni, Zn K, Na, Pb, tot.Cl2
Activated sludge MLSS 2/week suspended solids
Gouda
Oxidation pond 1 raw 2/week COD, pH, EC, ammonia, phosphate, tot.alk
Oxidation pond 2 raw Weekly COD, pH, EC, ammonia, phosphate, tot.alk
Oxidation pond 3 outlet Weekly COD, pH, EC
Oxidation pond 4 outlet Weekly COD, pH, EC
Oxidation pond 5 outlet Weekly COD, pH, EC
Oxidation pond 6 outlet Weekly COD, pH, EC
Oxidation pond 7 outlet 2/week COD, pH, EC
Oxidation pond 8 (final effluent) COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp.
Hermon Raw inlet 2/week COD, pH, EC, ammonia, phosphate
Final effluent 2/week COD, pH, EC, ammonia, tot.alk., dissolved oxygen, temp.
The sampling (location; frequency) performed at the various treatment plants is in accordance with
the minimum requirements of the Green Drop programme of DWA.
The critical monitoring points for all the Activated Sludge WWTW’s is the discharge points from where problems in the process can be identified through the other monitoring points.
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6 MONITORING OF CONTROL MEASURES AND RESPONSE PROTOCOL
The Drakenstein Municipality Wastewater Section has implemented an incident response protocol, in which certain reactive procedures are followed when an incident occurs (normally when a malfunction of the treatment processes occur due to power failures, faulty equipment, adverse weather conditions, human error, etc). There are two levels of incident management, firstly when a final effluent is discharged that does not meet the requirements of the Water Act, and secondly when an event takes place causing a major pollution event for which emergency response is required. Currently, these requirements are the General Standard for the Paarl, Wellington-, Pearl Valley- and Saron WWTW, and Irrigation Standards for the Gouda and Hermon Pond Systems. After the recent upgrading of the Paarl WWTW and upgrading of the Wellington WWTW in the near future, both of these plants will have to comply with the Special Standard for discharging into the Berg River. The Pearl Valley WWTW will also be required to meet the Special Standard requirements. A set of Compliance Alert Levels, corresponding to the requirements of the General Standard (at present), has been drawn up as part of a Wastewater Incident Management Protocol for Drakenstein Municipality, and is shown in the table 6.1 below. Table 6.1 : Compliance Alert Levels
Table 6.1: WWTW’s Compliance Alert Levels
Compliance Monitoring Sample
Alert Levels requiring action Response Protocol
Paarl WWTW
Final Effluent
COD > 75 mg/L
TSS > 25 mg/L
5.5 > pH > 9.5
EC > 150 mS/m
Ammonia > 6 mg/L as N
Nitrate > 15 mg/L as N
Ortho- P > 10 mg/L as P
Total Cl2 < 0.3 mg/L
E. Coli > 100 #/100 mL
Temp > 300 C
Cd > 0.005 mg/L
Cr > 0.05 mg/L
Cu > 0.01 mg/L
Zn > 0.1 mg/L
Pb > 0.01mg/L
Laboratory personnel to notify:
- Mr. Frans van Rooyen
- Mr. Cecil Paulse
- Mr. Cedric Morkel
Mr. Morkel to notify Mr. Brown, and then Response Protocol to be followed
Wellington WWTW
Final Effluent
COD > 75 mg/L
TSS > 25 mg/L
5.5 > pH > 9.5
EC > 150 mS/m
Ammonia > 6 mg/L as N
Nitrate > 15 mg/L as N
Ortho- P > 10 mg/L as P
Total Cl2 < 0.3 mg/L
E. Coli > 100 #/100 mL
Temp > 300 C
Cd > 0.005 mg/L
Cr > 0.05 mg/L
Cu > 0.01 mg/L
Zn > 0.1 mg/L
Pb > 0.01mg/L
Laboratory personnel to notify:
- Mr. Adam van Wyk
- Mr. Cecil Paulse
- Mr. Cedric Morkel
Mr. Morkel to notify Mr. Brown, and then Response Protocol to be followed
Pearl Valley WWTW
Final Effluent
COD > 75 mg/L
TSS > 25 mg/L
5.5 > pH > 9.5
EC > 150 mS/m
Ammonia > 6 mg/L as N
Nitrate > 15 mg/L as N
Ortho- P > 10 mg/L as
Total Cl2 < 0.3 mg/L
E. Coli > 100 #/100 mL
Temp > 300 C
Cd > 0.005 mg/L
Cr > 0.05 mg/L
Cu > 0.01 mg/L
Zn > 0.1 mg/L
Pb > 0.01mg/L
Laboratory personnel to notify:
- Mr. Shane Gardner
- Mr. Cecil Paulse
- Mr. Cedric Morkel
Mr. Morkel to notify Mr. Brown, and then Response Protocol to be followed
Saron WWTW
Final Effluent
COD > 75 mg/L
TSS > 25 mg/L
5.5 > pH > 9.5
EC > 150 mS/m
Ammonia > 6 mg/L as N
Nitrate > 15 mg/L as N
Ortho- P > 10 mg/L as
Total Cl2 < 0.3 mg/L
E. Coli > 100 #/100 mL
Temp > 300 C
Cd > 0.005 mg/L
Cr > 0.05 mg/L
Cu > 0.01 mg/L
Zn > 0.1 mg/L
Pb > 0.01mg/L
Laboratory personnel to notify:
- Ms. Tanya Simons
- Mr. Cecil Paulse
- Mr. Cedric Morkel
Mr. Morkel to notify Mr. Brown, and then Response Protocol to be followed
When the Compliance Alert Levels are exceeded, the actions stipulated in the Wastewater Incident Management Protocol of the municipality are followed. The Protocol is included in Annexure D.
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For serious incidents or emergency situations, additional actions and notifications are required, including notification of DWA and the media/public. The protocol to be followed in these situations is included in the Wastewater Incident Management Protocol.
6.1 Operational Alert Levels
For continuously improving the performance of the various WWTW’s, a set of operational alert levels has also been drawn up and followed by the operating personnel. The Operational Alert Levels are tabled below.
Table 6.2.1: WWTW’s Operational Alert Levels
ALL ACTIVATED SLUDGE WASTEWATER TREATMENT WORKS
(Paarl / Wellington / Pearl Valley / Saron)
Operational Samples Alert Levels Actions to be taken
Raw inlet
COD > 1000 mg/L
Ammonia > 100 mg/L as N
5.5 > pH > 9.5
EC > 150 mS/m
Settl. solids > 20 mL/L
Cd > 0.005 mg/L
Cr > 0.05 mg/L
Cu > 0.01 mg/L
Zn > 0.1 mg/L
Pb > 0.01 mg/L
Check for possible illegal industrial effluent discharge
Do more frequent measurements of DO levels, pH and MLSS in the activated sludge reactor
Raw inlet settled COD > 400 mg/L
Check operation of PST (faulty scrapers; blockages)
Check for oils and fats on the water surface
Activated sludge reactor
DO < 0.5 mg/L Increase aeration capacity or cycles
MLSS < 2000 mg/L Reduce discharge of WAS and allow MLSS –
levels to increase to 4000 mg/L
MLSS > 6000 mg/L Gradually waste more sludge on a daily basis
to reduce the MLSS to 4000 mg/L
pH < 7.0
Add lime to the inlet works to maintain the pH in the reactor at 7.0 or slightly above
Secondary settling tanks
COD > 75 mg/L
Check for sludge carry – over from secondary settling tanks
Check RAS recycle rates
Check for bulking sludge
Check for rising sludge
Take actions to rectify as appropriate
6.2 Verification of functioning of W2RAP
It is imperative that the functioning of the W2RAP can be monitored. If the W
2RAP is functioning
correctly there should be a decrease in risk and consequently better Wastewater treatment. There are various legislative requirements which will monitor the functioning of the W
2RAP indirectly,
such as the Green Drop Certification process and the RPMS system implemented by DWA. A well functioning W
2RAP will show improved scores in these processes.
Internal monitoring will also show improvement from well functioning W
2RAP. Comparisons of
internal monitoring results such as final effluent compliance over time will provide an indication of W
2RAP effectiveness.
Furthermore the W
2RAP is to be used inter alia with other Municipal Systems such as the Asset
Management Plan and the Operational and Maintenance Plans and the risk mitigation measures employed or identified in the W
2RAP must be aligned with these plans.
As stated above the W
2RAP must be reviewed at least once a year. A well functioning W
2RAP will
show a reduction in risk, year on year, due to implementation of mitigation measures.
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7 SUPPORT PROGRAMMES
Drakenstein Municipality provides various training projects and supporting programmes to educate their staff.
7.1 Process Controller Training Provided
On request of the Engineer: Waste Services (Mr R Brown), an on-site short course in wastewater treatment was presented to the process controllers and plant managers of the Drakenstein Municipality Wastewater Section by Water Training Africa in association with Seboka Manyabolo Management Solutions. The three-day course was presented on 3-5 May 2010 at the Training Centre of the Drakenstein Municipality and included practical training on site at the Paarl, Wellington, Pearl Valley and Saron wastewater treatment plants.
The course covered all aspects of municipal wastewater treatment, with an emphasis on practical aspects, and monitoring requirements. Evaluation of the candidates was done by means of a written-test, and certificates were presented to the course attendees on completion of the course.
7.2 Supervisors Forum
Drakenstein Municipality in conjunction with the University of Stellenbosch have partnered with other Municipalities within the Western Cape to be part of a WWTW Supervisors forum, where supervisors come together for training events and knowledge sharing.
Through this initiative valuable knowledge and problems solving skills are imparted on WWTW Supervisors. This type of support will provide valuable knowledge for incident situations. 7.3 Career Pathing
Professor Lagardien of the Cape Peninsula University of Technology has been approached to perform a Human Capital Development Audit which will inform the Municipality on career pathing and training priorities for its staff. Through this initiative risks associated with staffing problems can be addressed.
7.4 Consultant Advisors
The Municipality currently also employs several consultants, such as AL Abbott Laboratories and Integral Laboratories, to assist the Municipality with process audits.
These consultants form an integral part of the monitoring and verification processes which unfortunately, the Municipality does not always have the capacity to perform at the moment. 8 INCIDENT MANAGEMENT PLAN
Drakenstein Municipality has implemented an Incident Management Protocol (Annexure D) for all of their WWTW. The protocol differentiates between three alert levels based on the severity of the incident. These alert levels are shown in figure 8.1 below.
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Figure 8.1 Alert Levels and Reporting Implementation of these alert levels and the actions will occur as shown in the flowchart in figure 8.2 below.
Alert Level III:
Definite risk to health
or possible death
Inform : All stated for alert level two and Disaster and Emergency Management, Head of Department : Civil Engineering Services, Executive Director : Infrastructure and Planning, Municipal Manager, DWA, General Public Action : As per protocol
Alert Level II:
Potential risk to health
Inform : Senior Laboratory Chemist, Process Controllers, Plant Supervisor, District Supervisor, Head of Waste Services
Action : As per protocol
Alert Level I :
No significant risk to health
Inform : Senior Laboratory Chemist, Process Controllers, Plant Supervisor
Action : As per protocol
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Figure 8.2 Flow Chart of Incident Protocol
Incident
Senior Chemist or Process Controller : Report incident to Plant Supervisor
Plant Supervisor : Can Problem be Solved ?
Yes
Plant Supervisor to implement corrective action and report to District Supervisor
No
District Supervisor : Can Problem be Solved ?
Yes
District Supervisor to implement Incident Management Protocol and report to Head of Waste Services
No
Head of Waste Services: Can Problem be Solved ?
Yes
Head of Waste Services to implement Incident Management Protocol and report to Head of Department : Civil Engineering Services
No
Head of Waste Services to report and provide ongoing updates to :
Implement Incident Management Protocol
Disaster Management and Environmental Management
Head of Department : Civil Engineering Services
Executive Director : Infrastructure and Planning
Municipal Manager
Press, Public and DWA
Alert Level I
Alert Level II
Alert Level III
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9 CONCLUSIONS
The Hazard- or Risk Assessments of the various works show that Drakenstein Municipality have or are implementing various methods which mitigate their risks in terms of wastewater treatment. Saron WWTW is the highest risk and is therefore currently upgraded. The next phase of the upgrade also needs to be implemented as a matter of urgency. Initiatives include various training programmes for staff as well as cooperative governance. Furthermore the municipality also has implemented various management plans which include Incident Management Protocols, Asset Management and Operation and Maintenance Plans. Various risks have been identified for each works and mitigation measures have been proposed.
10 RECOMMENDATIONS 10.1 Risks to be addressed
The various high to medium risk items which must be addressed are shown in Annexure E along with the proposed mitigation measures. The most urgent risks are those associated with the Saron- and Wellington WWTW’s of which emergency funding for Saron WWTW is being applied for and the Wellington WWTW upgrading is in the planning and EIA phase.
10.2 Way forward
Priority must be given to the high risk items at each WWTW and allocations must be made through either staffing, operation and maintenance- or capital project budgets. An internal W²RAP workshop with all WWTW staff must be conducted to familiarize them with the W²RAP and the principle of risk management A yearly review of the W²RAP must be scheduled. It is proposed that the W²RAP must be updated in February every year.
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ANNEXURE A :
CATCHMENTS
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ANNEXURE B :
FLOW DIAGRAMMES
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ANNEXURE C :
DRAKENSTEIN MUNICIPALITY : WWTW RISK ASSESSMENT
C:\Users\Bradley.DRAKENSTEIN\Desktop\IDP\Lyners Waste Water Risk Abatement Plan\2013-02-19 - W2RAP on CD submitted\0828 W2RAP Report Rev B Feb 2013.docx
ANNEXURE D :
DRAKENSTEIN MUNICIPALITY : WASTE WATER INCIDENT MANAGEMENT PROTOCOL