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GOK /UNICEF PROGRAMME OF COOPERATION 2008 - 2013

KENYA WASH PROGRAMME

MANUAL FOR WATER FACILITIES

August 2008

The United Nations Children’s Fund Kenya Country Office,

Water and Environmental Sanitation P. O. Box 44145, 00100,

Nairobi, Kenya.Tel: 254 207622192,Fax: 254 20622764

Email: [email protected]

mailto:[email protected]

GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme TABLE OF CONTENTS

ABBREVIATIONS.......................................................................................51.0 INTRODUCTION...................................................................................6

Deliverables......................................................................................................................................62.0 GENERAL DESCPRIPTION APPLICABLE TO ALL STANDARD PROCEDURES. 6

2.1 Procurement of Contractors .......................................................................................................62.1.1 General Terms........................................................................................................................................62.1.2 Preamble to Bills of Quantities .............................................................................................................62.1.3 Contents of the Bills of Quantities ........................................................................................................72.14 Drawings ................................................................................................................................................7DESCRIPTION OF WATER FACILITIES .........................................................7

Water Facilities.................................................................................................................................73.1.1 Borehole.................................................................................................................................................73.1.2 Shallow Well..........................................................................................................................................73.1.3 Sub-surface/Sand Storage Dam..............................................................................................................73.1.4 Water Pans.............................................................................................................................................83.1.5 Roof Catchment ....................................................................................................................................83.1.7 Rock Catchment ....................................................................................................................................83.1.8 Summary of Water Facilities .................................................................................................................84.0 STANDARD PROCEDURES FOR WATER FACILITIES.................................9

4.1 Technical Procedures for Boreholes ..........................................................................................94.1.1 Drilling Technique.................................................................................................................................94.1.2 Well Design...........................................................................................................................................94.1.3 Casing and Screens................................................................................................................................94.1.4 Gravel Pack............................................................................................................................................94.1.5 Well Construction..................................................................................................................................94.1.6 Well Development ................................................................................................................................94.1.7 Well Testing...........................................................................................................................................9

4.2 Bills of Quantities for Boreholes................................................................................................94.2.1 Boreholes with Electric Pump and Various Depths................................................................................9

Drawings for Boreholes .................................................................................................................105.0 TECHNICAL PROCEDURE FOR SHALLOW WELLS...................................10

5.1 Description of Shallow Wells...................................................................................................105.1.1 Dug Wells ...........................................................................................................................................105.1.2 Hand-Drilled Wells .............................................................................................................................105.1.3 Mechanical Well Drilling ...................................................................................................................10

5.2 Dimensions of Shallow wells...................................................................................................105.3 Various Procedures for Hand Dug Wells.................................................................................105.2 Bills of Quantities for Shallow wells .....................................................................................115.3 Drawings for Shallow Wells ...................................................................................................11

6.0 TECHNICAL PROCEDURE FOR SUB-SURFACE/SAND STORAGE DAM........126.1 Bills of Quantities for Sub surface/sand Dams........................................................................126.2 Rubble Masonry Sand Dam with Tap/Gate Valve ..................................................................13 156.3 Rubble Masonry Sand Dam with Storage tank .......................................................................166.4 Gabion Sand Dam with Storage tank .....................................................................................196.5 Drawings for Subsurface/Sand Dams.......................................................................................20

7.0 TECHNICAL PROCEDURES FOR WATER PANS.......................................21 217.1 Bills of Quantities for Water Pans............................................................................................217.2 Drawings for Water Pans.........................................................................................................218.1 Parameters................................................................................................................................22

8.1.1 Runoff Coefficients..............................................................................................................................22

Technical Manual for Water Facilities 3

GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 8.1.2 Roof Catchments..................................................................................................................................228.1.4 Selection of Tank Size ........................................................................................................................22

8.2. Rainwater Harvesting..............................................................................................................228.3 Tank Design ............................................................................................................................228.4 Bills of Quantities for Storage Tanks ......................................................................................238.5 Drawings for Roof Catchments................................................................................................25

9.0 ROCK CATCHMENT ............................................................................269.1 Bills of Quantities for Rock Catchment...................................................................................269.2 Drawings for Rock Catchment.................................................................................................27

10. SPRING PROTECTION.......................................................................2710.1 Methods of Spring Protection.................................................................................................2710.2 Typical Spring Flow Rates.....................................................................................................2710.3 Stages in Spring Protection ...................................................................................................2710.4 Spring Protection Drawings...................................................................................................2711.1 Introduction............................................................................................................................2811.2 Sources...................................................................................................................................2811.3 Main pipeline..........................................................................................................................2811.4 Storage and Break-Pressure Tanks.........................................................................................2811.5 Distribution Pipelines and Tap Stands...................................................................................2812.1 Hand Pumps...........................................................................................................................29

12.1.1 Main Principle of Hand Pumps..........................................................................................................2912.1.2 Range of lift.......................................................................................................................................2912.1.3 Choice of Pumps................................................................................................................................2912.1.4 Performances of Hand Pumps............................................................................................................2912.1.5 Hand Pumps Installation Details.......................................................................................................3012.1.6 Siting of the Well...............................................................................................................................3012.1.7 Fencing of Water Source....................................................................................................................30

12.3 Solar Pumps............................................................................................................................3112.3.1 Comparison of Solar Pumps with Generator Pumps..........................................................................31

12.4 Pumps for Boreholes with Electricity................................................................................3112.4.1 Example of Submersible Pumps for Boreholes with Electricity.........................................................31

12.5 Play Pumps.............................................................................................................................3212.5.1 Operation of the Play Pump...............................................................................................................3212.5.2 Availability of Play Pumps................................................................................................................32

12.6 Wind Pumps...........................................................................................................................3212.6.1 Technical Information........................................................................................................................3212.6.2 Factors Affection Sustainability of Wind pump Technology:............................................................32

WATER FILTRATION ................................................................................................................33Introduction ...................................................................................................................................33Sand Filters.....................................................................................................................................33Boiling of Drinking Water ...........................................................................................................33 Activated Carbon (AC) Water Filters...........................................................................................33Ultraviolet (UV) Light ...................................................................................................................34Water Distillation (Water Distillers)..............................................................................................34How Distillers Works.....................................................................................................................34Disadvantages of distillers..............................................................................................................35 Reverse Osmosis...........................................................................................................................35How Reverse Osmosis Works .......................................................................................................35Advantages of reverse osmosis method ........................................................................................35What does an RO System cost?......................................................................................................36Summary........................................................................................................................................36

REFERENCES..........................................................................................36 ............................................37


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme

ABBREVIATIONS

The following abbreviations and acronyms have been used in this report:-

UNICEF - United Nations Children FundTOR - Terms of ReferenceGOK - Government of KenyaMWI - Ministry of Water and Irrigation BoQ - Bill of Quantities


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 1.0 INTRODUCTION This manual is prepared for the purposes of complementing the already existing guidelines/ know- how and gives detailed information and technical procedures of implementation of the water projects for GoK/UNICEF programme of cooperation.

Subject to the GoK/UNICEF procurement procedures the content will form an integral part of documents for inviting bids for construction of the facilities. It is important to note these are standard details that are formulated following international codes of design together with some innovations to attempt to suit specific cases. The standards can be localised depending on the location of the water project, geological conditions, terrain, human population, livestock population, level of development of the area, capital etc. At the point of implementation, there would be need for professional guidance especially to modify the where necessary and to supervise works during construction.

The standard documents contained in this report are for; boreholes, shallows wells, water pans, sub surface dams, sand storage dams, roof and rock catchments. The details for each of the options are presented in the following sequence;

Standard technical description: - Technical information that may be useful for decision making during implementation.

Bills of Quantities: - To guide pricing while biddingDrawings: - Presentation of technical details for various water facilities.

Deliverables

The report is presented in two bound hard copies of, a soft copy and a power point presentation of the outputs that will be made to Ministry of Water and Irrigation, Ministry of Health, Ministry of Education, UNICEF, other stakeholders and Government of Netherlands representatives at the end of assignment.

The outputs are specified in the ToR and are expected to be submitted within the time frames proposed. There will be need however for the client to comment on the draft before the final report is submitted.

2.0 GENERAL DESCPRIPTION APPLICABLE TO ALL STANDARD PROCEDURES

2.1 Procurement of Contractors

2.1.1 General Terms

Selection of contractors shall be made in accordance with the Kenya Public Procurement and Disposal Act 2005 or as will be outlined in the Programme documents for the GoK/UNICEF Programme of cooperation. Contractors will be evaluated on the basis of their bid prices and their technical capacity. They should be invited for the tender opening and be informed on the outcome of the tenders by writing.

Conditions of contract shall be based on provisions of the contract signed by both contractor and the or as per other procedures as it may advised at the time of execution of these works. Where applicable the implementation may be by the Community Based Organisation through the facilitation of the programme’s technical staff. Measurement of all works executed by contractors will comply with the Civil Engineering Standard Methods of Measurements and the Bills of Quantities and will always be verified by the responsible engineer on site

2.1.2 Preamble to Bills of Quantities

1. The Bill of Quantities shall be read in conjunction with the Instructions to Bidders, General and Special Conditions of Contract, Technical Specifications, and Drawings.

2. The quantities given in the Bill of Quantities are estimated and provisional, and are given to provide a common basis for bidding. The basis of payment will be the actual quantities of work ordered and carried out, as measured by the Contractor and verified by the Engineer and valued at the rates and prices bid in the priced Bill of Quantities, where applicable, and otherwise at such rates and prices as the Engineer may fix within the terms of the Contract.

3. The rates and prices bid in the priced Bill of Quantities shall, except insofar as it is otherwise provided under the Contract, include all Constructional Plant, labour, supervision, materials, erection, maintenance, insurance, profit, taxes, and duties, together with all general risks, liabilities, and obligations set out or implied in the Contract.

4. A rate or price shall be entered against each item in the priced Bill of Quantities, whether quantities are stated or not. The cost of Items against which the Contractor has failed to enter a rate or price shall be deemed to be covered by other rates and prices entered in the Bill of Quantities.

5. The whole cost of complying with the provisions of the Contract shall be included in the Items provided in the priced Bill of Quantities, and where no Items are provided, the cost shall be deemed to be distributed among the rates and prices entered for the related Items of Work.

6. General directions and descriptions of work and materials are not necessarily repeated nor summarized in the Bill of Quantities. References to the relevant sections of the contract documentation shall be made before entering prices against each item in the priced Bill of Quantities.

7. Provisional Sums included and so designated in the Bill of Quantities shall be expended in whole or in part at the direction and discretion of the Engineer in accordance with Sub-Clause 52.4 and Clause 58 of Part I of the Conditions of Contract.

8. The method of measurement of completed work for payment shall be in accordance with [insert the name of a standard reference guide, or full details of the methods to be used].

9. Errors will be corrected by the Employer for any arithmetic errors in computation or summation as follows:

(a) where there is a discrepancy between amounts in figures and in words, the amount in words will govern; and

(b) where there is a discrepancy between the unit rate and the total amount derived from the multiplication of the unit price and the quantity, the unit rate as quoted will govern, unless in the opinion of the Employer, there is an obviously gross misplacement of the decimal point in the unit price, in which event the total amount as quoted will govern and the unit rate will be corrected.

10. Rock is defined as all materials which, in the opinion of the Engineer, require blasting, or the use of metal wedges and sledgehammers, or the use of compressed air drilling for their removal, and which cannot be extracted by ripping with a tractor of at least 150 brake hp with a single, rear-mounted, heavy-duty ripper.


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 2.1.3 Contents of the Bills of Quantities

The Bills of Quantities will consist of the following;

• General • Proposed works• Provisional sums• Contingencies• Taxes• Total Cost

2.14 Drawings

2.14.1 Scale

The scales used are provided below and they conform to ISO 5455 – 1979 (E).

1: 2 1: 5 1: 10 1: 20 1: 50 1: 100 1: 200 1: 500 1: 1000

2.1.4.2 Standard and Type of Drawings

The drawings will be presented in A3 (450 x 297mm). However, if a drawing is being used during construction it should be printed in paper size A1 (840 x 594mm). The title block used is attached in the appendix 3. The following conditions must be fulfilled for a drawing to be classified as standard. These includes:-

a) Design shall be possible to use for several different projects.b) Design shall be of high professional standardc) Design shall comply with recommendations of Kenya Bureau of Standards or with the standards used by the

Ministry. SI – units shall be used exclusively. The description of SI system is given below:-d) Design shall be sufficiently detailed to allow construction work to be carried out without additional design work.

DESCRIPTION OF WATER FACILITIES

Water Facilities

The technological options for development of the water points for rural communities and livestock consumption includes of; boreholes, shallow wells, water pans, sub surface dams, sand storage dams, roof and rock catchments. The choice of technological options depends on various factors as follows;

• Suitability of site: - The suitability of site depends on space occupied by the development, ease of development, ability to abstract water and water quality.

• Reliability of option: - Permanence of water supply and potential of the source of water to meet demand across the year.

• Quality of water: - The cleanliness, salinity levels, against the uses for the water need to be checked.• Quality of yield:-The ability of water source to yield comparatively more water needs to be considered. • Cost of development: - The cost of construction of water facilities also determines the type of technological

options used. For example, a borehole will be developed where the beneficial community will be able to cater for cost of operation and maintenance.

A detailed unit cost model for various technological options has been developed by the Ministry of Water and Irrigation and is available for use at the planning, and monitoring and evaluation stages of implementation cycle to determine the investment and operational costs for different water supply technologies.

3.1.1 Borehole

The groundwater is exploited by use of borehole and its suitability is determined by the groundwater in the underlying rocks. This defines the existence of shallow, medium or deep groundwater in the sub-surface.

According to water act, it is a requirement that a borehole is drilled not less than 0.8 km radius from an existing one. The borehole yield varies from 0.641 - 26.776 m3/hr. Depending on the yield of the borehole, they are classified as shown in the table 3.1 below:-

3.1.2 Shallow Well

In area where shallow aquifers are encountered at depths less than 30 metres, shallow wells are recommended. In areas where there are shallow riverbeds saturated with sands, especially where there is a perennial sub-surface flow, shallow wells are the best technological options.

3.1.3 Sub-surface/Sand Storage Dam

The sub-surface/Sand Storage Dams are constructed in the arid and semi-arid areas. The suitable areas are dry river-bed, seasonal stream or lagga, which receives some flow during the rainy season. The sand retains the water for relatively long periods after the surface flow in the river has ceased. The volume of water stored varies depending on the grading of the sand and gravel. In most cases, the available water is about 20% to 30 % of the total volume of sand. The water is retained behind the dam structure. The dam structure is built on an impermeable layer of rock or clay.

Pumping wells or any other suitable outlet structure is located upstream for drawing water and delivering it to the community to avoid damage caused by direct access to the dam. The water quality in sub-surface dams is usually much better than water from open surface reservoirs, since it is protected from direct contact with animals and humans.

Technical Manual for Water Facilities

Table 3.1 Borehole Yield Class

Yield Class Yield (m3/hr)

1 0 – 2.52 2.5 – 3.53 3.5 – 4.54 4.5 – 5.55 5.5 – 6.56 6.5 – 7.57 7.5

7


3.1.4 Water Pans

Water pans are shallow natural or man-made depressions on the ground surface, where water can be collected from surface flow or direct from a nearby seasonal stream (lagga). Water pans are constructed in the arid and semi-arid areas for livestock watering. Springs and surface flow are the source of water to water pans.

Water is stored in the form of a pond with an open water surface. This results to evaporation losses. The capacity of water pans ranges from few hundred cubic metres for natural depressions and small man-made pans, to 20,000 m3 for the Ministry of Water and Irrigation Standard large capacity design. There are two types of water pans/earth dam construction. These are simple excavation pit in flat areas or in existing depressions and embankment ponds where water is retained within an earth embankment comprising impervious soils.

For domestic use, a hand-dug well positioned adjacent to the pan will provide better quality water, particularly if a graded sand and gravel filters links the well to the pan or earth dam. 3.1.5 Roof Catchment

Roof catchment is the most common type of rainwater catchment system, and offers the greatest potential for development in the future. It provides the cleanest and most convenient of all rainwater supplies. However, it is highly dependent on the amount of rainfall. Proper design and construction of the system is a prerequisite to the efficient functioning of the system. To prevent water contamination, care should be take in selecting the roof catchments e.g. avoid roofs near rubbish disposal area, industrial emissions and hospital rubbish pit/incinerators.

3.1.6 Surface Runoff

Surface runoff occurs when the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground. The excess water flows on the ground surface and can be collected for domestic, livestock or irrigation use. Underground tanks and reservoirs (surface dams, water pans, earth dams etc.) are conveniently used to collect and store surface run off water. This technology is highly depends on high amount of rainfall and rain water can easily be contaminated especially where communities dispose human excreta in the cathcment area.

3.1.7 Rock Catchment

Rock catchment is a catchment area formed by a bare rock surface and a pond normally formed by a concrete weir. The catchment area may be extended using cement guttering. The rock catchment depends on geology. The rock catchment depends on availability of existing quality rock surfaces, and density of rock outcrops in an area.

The storage capacity of rock catchment varies from 20 m3 to 10,000 m3 depending on the size of the rock outcrop, and its area extent, elevation and gradient.

3.1.8 Summary of Water Facilities

Water Source Capital Cost Running Cost Recommended Regions

Comments/Requirements

Rainwater harvesting (Roof catchment and surface run off)

Medium, storage tanks needed

Low North eastern, Eastern, Central, Rift Valley, Western, Nyanza provinces

Needs two wet seasons a year, preferably. Water quality is good for roof catchment and poor for surface run off.

Boreholes Medium ,Well drilling equipment needed

Medium, Mechanical Pumping

North eastern, Eastern, Rift Valley,

Suits deep underground aquifer. Needs maintenance of mechanical pumps. Requires acquisition of license from NEMA and Authorization permit from WRMA.

Water Source Capital Cost Running Cost Recommended Regions

Comments/Requirements

Spring Protection Low; Medium if piped to community

Low Nation wide provided there exists reliable spring eye

Needs a reliable spring flow throughout the year. Requires acquisition of license from NEMA and Authorization permit from WRMA.

Gravity Supply High pipeline and local storage

Low Nation wide provided there exists reliable water source from lake, river, borehole, spring etc

Needs a stream or spring source at a higher elevation. Major advantage is that the taps stands can be near houses. Requires acquisition of license from NEMA and Authorization permit from WRMA.

Hand Dug Wells Low (local labour) Hand Pump Needed

Low North eastern, Eastern provinces

Abstraction can be by hand pumps. Buckets do contaminate drinking water, thus not preferred. Requires acquisition of license from NEMA and Authorization permit from WRMA.

Sand Dam/Subsurface dams

Low; Medium if building stones are not readily available.

Low North eastern, Eastern provinces

Required high accumulation of sand soil. Can be used to recharge shallow wells and springs. Needs acquisition of license from NEMA and Authorization permit from WRMA.

Water Pans Low Low North eastern, Eastern provinces

Suitable for areas clay soils else polythene or concrete lining would be needed to prevent water losses through seepage.

River/Lake Abstraction

High Design and construction of intake

High Treatment and pumping usually needed

Nyanza, Western, Central and Rift valley provinces

Last resort. Filtration essential. Maintenance required for filtration and dosing plant. Requires acquisition of license from NEMA and Authorization permit from WRMA.

NB: Detailed site investigations should be carried out at each particular site to determine the suitability of each technological option prior to project implementation.

3.1.9 Monitoring of Water Facilities

Once a water facility has been commissioned, a routine monitoring and evaluation programme should be established so that its performance can be verified and the actual output of the facility established. The exercise can be conducted on monthly, quarterly, semi-annual or annual basis depending on the nature and size of the project. More sensitive technologies require frequent monitoring e.g. borehole while simple technologies like water pan would adequately be monitored before and after a rainy season.

Routine monitoring of the functionality of facility permits a regular assessment to be made of whether it is serving the intended purpose and that the water quality complies with the water standards. In addition, timely project monitoring and evaluation enables the required repair actions to be taken on time.

Monitoring of selected performance parameters should provide sufficient information to measure performance in meeting project objectives. If monitoring results indicate that the system is not working according to the objectives, corrective measures must be applied. Improvement of water quality and quantity may be assessed by conducting laboratory tests and analysing the changes in service levels.


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 4.0 STANDARD PROCEDURES FOR WATER FACILITIES

4.1 Technical Procedures for Boreholes

The borehole is supposed to be drilled not less than 0.8 km radius from an existing one as a water act requirement. To determine suitable spacing for economical and sustainable borehole system, test pumping, modelling and property boundaries are used. The criterion for successful rate of borehole is borehole yield: 330 l/hr or more and water quality. 4.1.1 Drilling Technique

Drilling should be carried out with an appropriate tool – either percussion, piling or rotary piling machines will be suitable, though the latter are considerably faster. Geological rock samples should be collected at 2-metre intervals. Struck and rest water levels and if possible, estimates of the yield of individual aquifers encountered should also be noted. Monitoring of the electrical conductivity of each aquifer encountered should be done.

4.1.2 Well Design

The design of the well should ensure that screens are placed against the optimum aquifer zones. The final design should be made by an experienced driller or hydro geologist. The well head should be water tight, lockable by threading and constructed from material that is not easily corroded. The electrical cables for the power supply should be buried below ground level.

4.1.3 Casing and Screens

The well should be cased and screened with good quality material. Owing to the depth of the borehole, the high salinity coupled with incidence of corrosion in the area, it is recommended to use high quality uPVC casing and screens with high effective open surface area. Alternatively galvanized steel casings and Johnson’s screens of high open surface area may be used.

We strongly advise against the use of torch-cut steel well-casing as screen. In general, its use will reduce well efficiency (which leads to lower yields), increase pumping costs through greater draw down, increase maintenance costs, and eventually reduction of the potential effective life of the well. In addition, the slot size of these screens is too large and will enhance siltation of the wells due to presence of silts in the formation.

4.1.4 Gravel Pack

The use of a gravel pack is recommended within the aquifer zone, because the aquifer could contain sands or silts which are finer than the screen slot size. A 1 meter diameter borehole screened at 40cm will leave an annular space of approximately 30cm, which should be sufficient. Should the slot size chosen be too large, the well will pump sand, thus damaging the pumping plant, and leading to gradual ‘siltation’ of the well. The slot size should be in the order of 0.5 – 1mm. The grain size of the gravel pack should be an average 1 – 2 mm, although this should be determined after drilling and execution of on-site sieve analysis of the samples.

4.1.5 Well Construction

Once the design has been agreed, construction can proceed. In installing screen and casing, centralizers at 6 metre intervals should be used to ensure centrality within the borehole. This is particularly important so as to insert the artificial gravel pack all around the screen. If installed, gravel packed sections should be sealed off top and bottom with clay (2m).

The remaining annular space should be backfilled with an inert material, and the top three metres grouted with cement to ensure that no surface water at the wellhead can enter the well bore and thus prevent contamination.

4.1.6 Well Development

Once screen, pack, seals and backfill have been installed, the well should be developed. Development aims at repairing the damage done to the aquifer during the course of drilling by removing clays and other additives from the borehole walls. Secondly, it alters the physical characteristics of the aquifer around the screen and removes fine particles.

We do not advocate the use of over pumping as a means of development since it only increases permeability in zones, which are already permeable. Instead, we would recommend the use of air or water jetting, or the use of the mechanical plunger, which physically agitates the gravel pack and adjacent aquifer material. This is an extremely efficient method of developing and cleaning wells.

Well development is an expensive element in the completion of a well, but is usually justified in longer well-life, greater efficiencies, lower operational and maintenance costs and a more constant yield. Within this frame, the pump should be installed at least 2m above the screen, certainly not at the same depth as the screen.

4.1.7 Well Testing

After development and preliminary test, a long-duration well test should be carried out. Well tests have to be carried out on all newly-completed wells, because aside from giving an indication of the quality of drilling, design and development, it also yields information on aquifer parameters which are vital to the hydro geologist.

A well test consists of pumping a well from a measured start level (Water Rest Level – (WRL) at a known or measured yield, and simultaneously recording the discharge rate and the resulting draw downs as a function of time. Once a dynamic water level (DWL) is reached, the rate of inflow to the well equals the rate of pumping. Usually the rate of pumping is increased step wise during the test each time equilibrium has been reached (Step Draw-Down Test). Towards the end of the test, a water sample of 2 litres should be collected for chemical analysis.

The duration of the test should be 24 hours, followed by a recovery test for a further 24 hours, or alternatively until the initial WRL has been reached (during which the rate of recovery to WRL is recorded). The results of the test will enable a hydro geologist to calculate the optimum pumping rate, the installation depth, and the draw down for a given discharge rate.

4.2 Bills of Quantities for Boreholes

4.2.1 Boreholes with Electric Pump and Various Depths

4.2.1.1 BILL OF QUANTITIES FOR BOREHOLE 80 – 250 m DEPTH

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Boring

1 Boring m Various (80 -250) B. Pump Station

2 E. Pump Unit 1 3 Concrete (1:2:4) m3 1.21

4 Reinforcement kg 10 5 Gravel bedding m3 0.7

6 Formworks m2 4.59

C. Drain 7 Concrete (1:2:4) m3 1.8

8 Reinforcement kg 0.02 9 Gravel bedding m3 0.8

10 Formworks m2 18

D. Livestock Trough 11 Concrete (1:2:4) m3 0.71



GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 4.2.1.1 BILL OF QUANTITIES FOR BOREHOLE 80 – 250 m DEPTH

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs)14 Formworks m2 4.8

Total

4.2.1.2 BOQ for Wind Pump in 80m BH 3.7 m Diameter Rotor, 10 m Head and 80 m Borehole

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Wind pump Machine including Standard Tower each 1 10 ft. Tower extension each 1 Shallow well crossbeam each 1 Pump rods each 1 Stifling box each 1 Transport (100 km) each 1 2" Pipe fittings, air bottle and shroud each 1 2 2/4 Deep well pump cylinder each 1

3 3/4 Deep well pump cylinder each 1

Installation day 5 B. Borehole m 80 C. Storage tank (Capacity:28 m3) Concrete (1:2:4) m3 13.98

Reinforcement kg 0.7 Excavation, common m3 86.64

Backfilling m3 54.9

Formworks m2 72.16

C. Tap Station Concrete m3 0.86

Reinforcement kg 0.9 Excavation, common m3 15.2

Backfilling m3 11.1

Sub-Total

Drawings for Boreholes

i. Water Facilities Drawings\Boreholes\Bore hole and Wind Pump.pdf

5.0 TECHNICAL PROCEDURE FOR SHALLOW WELLS

5.1 Description of Shallow Wells

Shallow wells are classified according to the manner of construction as; dug wells, hand drilled and mechanical drilled wells

5.1.1 Dug Wells

These have depths less than 30 metres. The diameter should be at least 1.2 m to allow two men to work together during the digging. The well should be dug at least 3m below the expected lowest water level. The well need to be lined with materials such as bricks, stone masonry, concrete rings cast insitu or precise concrete rings. The shallow well is excavated from inside but in loose soil hand-drilling should be used. If the area is rock, the well may stand unlined but the upper part should always have a lining.

The section of the well penetrating the aquifer requires a lining with openings or perforations to allow the groundwater to enter. Any backfill at the same level as the aquifer should be made with gravel.

The fine sand aquifers have lining without perforations and the groundwater should enter only through the bottom of the well. The bottom should be covered with graded gravel e.g. three layers each 150 mm thick with grain sizes 102 mm for the deepest layer, then 4 – 8 mm and 20 – 30 mm effective size at the top.

As protection measure, the wall lining should be extended 0.5 m above the ground to form a wall round the well. In addition, the well top should be sealed with a watertight slab. In areas where there are shallow riverbeds saturated with sands, especially where there is a perennial sub-surface flow, shallow wells are the best technological options.

5.1.2 Hand-Drilled Wells

Hand drilling of 150 – 300 mm diameter wells down to a depth of 15 – 20 m is particularly feasible in clay and sand soils. A filter pipe of 6m length and 100 – 150 m diameter and a sand filter should be put in the well.

5.1.3 Mechanical Well Drilling

Mechanical well drilling has to be used in layers with big stones and boulders and in heavily cemented soils. The protection is as that of dug wells.

5.2 Dimensions of Shallow wells

Depths of hand-dug wells range from shallow wells, about 5 metres deep, to deep wells over 0 metres deep. Wells with depths of over 30 metres are sometimes constructed to exploit a known aquifer. It is impractical to excavate a well which is less than a metre in diameter; an excavation of about 1.5 metres in diameter provides adequate working space for the diggers and will allow a fnal internal diameter of about 1. metres after the well has been lined.

5.3 Various Procedures for Hand Dug Wells

(a) Digging with the sides of the excavation supported

There are several methods of supporting the sides of the excavation while digging proceeds:1 The safest method is to excavate within pre-cast concrete rings which later become the permanent lining to the

sides of the well. The frst ring has a cutting edge, and additional rings are placed on it as excavation proceeds. As material is excavated within the ring, it sinks progressively under its own weight and that of the rings on top of it. This method should always be used in unstable ground. When construction has fnished, the joints between the rings which are above the water table should be sealed with cement mortar.

2 In suitable ground, excavation may proceed for a short distance without support to the sides; these are then supported by means of concrete poured in situ from the top, between the sides of the excavation and temporary formwork, which becomes the permanent lining to the well. This process is repeated until the water table is reached.

3 In suitably stable ground, excavation may proceed within the protection of vertical close-ftting timber boards, supported by horizontal steel rings. The timbers are hammered down as excavation proceeds and additional timbers are added progressively at ground level. The steel rings must be hinged, or in two parts bolted together,



so that lower ones can be added as the excavation progresses. The vertical spacing between the rings will depend on the instability of the ground. The well is lined with bricks, or concrete blocks, from the water table upwards, within the timbers as they are withdrawn.

(b) Digging with the sides of the excavation unsupported

In stable ground, wells are often excavated down to water level without a lining, and are lined with in situ concrete, or with pre-cast concrete rings, from this level upwards. Wells safely dug during the dry season may become unstable when the water level rises in the wet season and therefore must be lined before this occurs to prevent a collapse.Although in firm stable ground unlined wells may be safely excavated and may give long service in operation, it is prudent, and in most cases essential, to provide a permanent supporting lining which will support the sides of the excavation and prevent them from collapsing; suitable lining materials are concrete, reinforced concrete, ferrocement, masonry, brickwork, etc.

(c) Excavation below the water level

Regardless of which method has been used to excavate the well to the water table, excavation below this level should never be attempted until the sides of the excavation have received the support of their permanent lining, from water table to ground level. Excavation below the water table should be carried out within pre-cast concrete caisson rings of a smaller diameter than the rest of the well. The initial caisson ring is provided with a cutting edge and additional rings are placed on top of it; as the material within is excavated, the rings sink progressively under their own weight. To facilitate the ingress of water, these lower rings are often constructed with porous, or no-fines, concrete and their joints are left un-pointed

(d) Completion

After construction of the well shaft has been completed, the bottom is plugged with gravel. This helps to prevent silty material from clay soils, or fines from sandy materials, being drawn into the well. Any annular space between the pre-cast caisson well rings and the side of the excavation should also be filed with gravel; such filling behind the rings which are below the water helps to increase water storage and to prevent the passage of fine silts and sands into the well.

The space behind the top three metres, or so, of the well rings should be backfilled to ground level with puddled clay, or concrete, and the well rings should project about one metre above a concrete apron. This apron provides a sanitary seal to prevent polluted surface water seeping into the well and should slope away from it and drains into a channel which discharges into a soak away.

(e) Abstraction

It is desirable for the well to have a concrete cover slab to reduce the possibility of contamination. Water is safely abstracted by means of a rope and washer pump above an access hole, or a hand pump, depending upon the yield of water available and the ability of the benefiting community to pay for ongoing maintenance for the hand pump, spare parts, etc. A hand-dug well fitted with a hand pump can serve the needs of about 300 people.

5.2 Bills of Quantities for Shallow wells

5..2.1 BOQ for Shallow well and hand pump 10 m depthITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Boring

1 Boring m 10 B. Hand pump Station

2 Hand pump Unit 1 3 Concrete (1:2:4) m3 1.21


6 Formworks m2 4.59

5..2.1 BOQ for Shallow well and hand pump 10 m depthITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) C. Drain

7 Concrete (1:2:4) m3 1.8


10 Formworks m2 18



14 Formworks m2 4.8

Total

5..2.2 BOQ for Shallow well and hand pump 20 m depthITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Boring

1 Boring m 20 B. Hand pump Station

2 Hand pump Unit 1 3 Concrete (1:2:4) m3 1.21


6 Formworks m2 4.59

C. Drain 7 Concrete (1:2:4) m3 1.8


10 Formworks m2 18



14 Formworks m2 4.8

Total

5.3 Drawings for Shallow Wells

Water Facilities Drawings\Shallow Wells\Shallow Well with Hand Pump.pdf

Technical Manual for Water Facilities

14

11


6.0 TECHNICAL PROCEDURE FOR SUB-SURFACE/SAND STORAGE DAM

The sub-surface/Sand Storage Dams are built in the riverbeds and have dam walls built of soil that stretch across the riverbed in seasonal water courses with sand, also called sand rivers, dry riverbeds, laggas, wadis etc. The sub-surface dams blocks floodwater that has infiltrated into the voids between the sand particles. They store up to 35% water in the voids in course sand.

Weirs, built of stone masonry or concrete function as subsurface dams, but can store more water because they can be built to 50 cm above the surface of the surrounding sand.

Sand dams are structures larger than weirs, which can be raised to several metres above the sand surface of seasonal water courses and gullies. The dam across the river should done in stages to ensure that mainly sand and gravel are deposited. The first stage is 2 m high. Later the wall should be raised as the sand and gravel builds up until the full height, often 6 – 12 m is reached. Pumping wells or any other suitable outlet structure is located upstream for drawing water and delivering it to the community to avoid damage caused by direct access to the dam.

6.1 Bills of Quantities for Sub surface/sand Dams

6.1.1 Bill of Quantities for Rubble Masonry Sub-surface Dam with well2 m high and 10 meter long

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Sand Dam Site Clearing m2 80

Excavation, common m3 125

Excavation, rock m3 42.88

Backfilling m3 128.5

Rubble masonry m3 35

B. Water Abstraction Stone/Gravel filter Unit 5.94 Concrete Pipe (1.0 m diameter) m3 4

Common excavation kg 28.57 Backfill m3 17.81

Total



Excavation, common m3 312.5


Backfilling m3 286

Rubble masonry m3 87.5




Total









Total





Backfilling m3 231




Total











Total





Backfilling m3 1021


B. Water Avstraction Stone/Gravel filter Unit 7.42 Concrete Pipe (1.0 m diameter) m3 5


Total









Total









Total









Total

6.2 Rubble Masonry Sand Dam with Tap/Gate Valve

6.2.1 Bill of Quantities for Rubble Masonry Sand Dam with Tap/Gate Valve3 m high and 10 meter long

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs)1 Sand Dam (Capacity 2,180 m3)

Site Clearing m2 90



Backfilling m3 135


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 6.2.1 Bill of Quantities for Rubble Masonry Sand Dam with Tap/Gate Valve

3 m high and 10 meter long Rubble masonry m3 132.5

Concrete m3 8.75

Reinforcing Bars kg 40 Formworks m2 30

2 Water Abstraction (Tap Station)

PVC pipe 280 mm Diameter m 10 PVC pipe 50 mm Diameter m 10 Gate Valve/Tap each 2 Stone/Gravel filter m3 30

Total



Site Clearing m2 225





Concrete m3 8.75


2 Water Abstraction (Tap Station) PVC pipe 280 mm Diameter m 25 PVC pipe 50 mm Diameter m 12 Gate Valve/Tap each 2 Stone/Gravel filter m3 75

Total






Backfilling m3 675


Concrete m3 8.75


2 Water Abstraction (Tap Station) PVC pipe 280 mm Diameter m 70 PVC pipe 50 mm Diameter m 15

Gate Valve/Tap each 2 Stone/Gravel filter m3 75

Total 6.2.4 Bill of Quantities for Rubble Masonry Sand Dam with Tap/Gate Valve

4 m high and 10 meter longITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs)

1 Sand Dam (Capacity 3,876 m3)




Backfilling m3 240


Concrete m3 9.95




Total


ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs)Sand Dam (Capacity 9,690 m3)




Backfilling m3 600


Concrete m3 9.95




Total








Backfilling m3 1200


Concrete m3 9.95




Total






Backfilling m3 375


Concrete m3 11.15




Total








Concrete m3 11.15




Total






Backfilling m3 1875


Concrete m3 11.15




Total



6.3 Rubble Masonry Sand Dam with Storage tank

6.3.1 BOQ for Rubble Masonry Sand Dam with storage tank3 m high and 10 meter long


Site Clearing m2 90



Backfilling m3 135

Stone masonry m3 132.5

Concrete m3 8.75


2 Storage (Capacity:1000 m3)



Excavation rock m3 76.8

Concrete, structure m3 179.2

Reinforcing Bars kg 7170 Formworks m2 590.4



Concrete m3 0.86


Total








Concrete m3 8.75










Concrete m3 0.86


Total








Backfilling m3 675


Concrete m3 8.75










Concrete m3 0.86


Total






Backfilling m3 240


Concrete m3 9.945

Reinforcing Bars kg 0.1 Formworks m2 40


Site Clearing m2 702.25




Reinforcing Bars kg 13.73 Formworks m2 831.6



Concrete m3 0.86


Total








Backfilling m3 600


Concrete m3 9.95






Concrete, structure m3 704




Concrete m3 0.86


Total






Backfilling m3 1200


Concrete m3 9.95





Excavation rock m2 504



3 Water Abstraction (Tap Station) PVC pipe 280 mm Diameter m 70 PVC pipe 50 mm Diameter m 15 Gate Valve/Tap each 3 Stone/Gravel filter m3 75

Concrete m3 0.86


Total






Backfilling m3 375


Concrete m3 11.15

Reinforcing Bars kg 0.11 Formworks m2 50

2 Storage (Capacity: 3000 m3)

Site Clearing m2 992.25




GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 6.3.7 BOQ for Rubble Masonry Sand Dam with storage tank

5 m high and 10 meter longITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) Concrete, structure m3 510.13




Concrete m3 0.86


Total








Concrete m3 11.15










Concrete m3 0.86


Total






Backfilling m3 1875


Concrete m3 11.15





Excavation rock m2 750

Concrete, structure m3 1610




Concrete m3 0.86


Total

6.4 Gabion Sand Dam with Storage tank

6.4.1 Bill of Quantities for Gabion Sand Dam with Storage Tank 3 m high and 10 meter long

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs)1 Sand Dam



Excavation, rock m3 140

Fill and Backfilling m3 210

Gabion m3 700

Concrete (1:2:4) m3 18.3

2 Storage Tank





GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 6.4.1 Bill of Quantities for Gabion Sand Dam with Storage Tank

3 m high and 10 meter long Concrete, structure m3 38.4

Reinforcing Bars kg 3.46 Formworks, structure m2 989.28

3 Water Abstraction

PVC pipe m 20 GI pipe m 15 Gate valve/Tap each 3 Stone/Gravel filter m3 30

Concrete Pipe (tap station) m3 0.86

Reinforcement kg 8.6 Formwork, structure m3 9.36

Total







Gabion m3 625

Concrete (1:2:4) m3 27.3

2 Storage Tank






3 Water Abstraction PVC pipe m 45 GI pipe m 15 Gate valve/Tap each 3 Stone/Gravel filter m3 75



Total







Gabion m3 1700

Concrete (1:2:4) m3 42.3

2 Storage Tank






3 Water Abstraction

PVC pipe m 80 GI pipe m 15 Gate valve/Tap each 3 Stone/Gravel filter m3 150



Total

6.5 Drawings for Subsurface/Sand Dams

i. Water Facilities Drawings\Sand-Sub surface Dams\Gabion Sand Dam with RC Tank.pdfii. Water Facilities Drawings\Sand-Sub surface Dams\Rubble masonry Sand Dam.pdf

iii. Water Facilities Drawings\Sand-Sub surface Dams\Rubble Masonry Sand dam with RC Tank.pdfiv. Water Facilities Drawings\Sand-Sub surface Dams\Rubble Masonry Sand Dam with Well.pdf



7.0 TECHNICAL PROCEDURES FOR WATER PANS

Water pans are shallow natural or man-made depressions on the ground surface, where water can be collected from surface flow or direct from a nearby seasonal stream (lagga). The capacity of water pans ranges from few hundred cubic metres for natural depressions and small man-made pans, to 20,000 m3 for the Ministry of Water and Irrigation Standard large capacity design.

The design of water pan consists of a semi-circular dam wall shaped like a new moon. The wall is made of compacted earth and each end, which is strengthened with rocks, is designed to act as a spillway. To improve on the quality of water for domestic use, hand pumps, sand filters and cattle troughs should be incorporated into the system. Details on hand pumps and sand filters are shown in Section 12 and 13.2 respectively. Cattle troughs are meant to prevent contamination of water by livestock drinking water directly from the water pan. Good practice is to provide a sufficient watering area for young and mature livestock separately for ease of use and this should be located about 100m downstream of the pan. 7.1 Bills of Quantities for Water Pans

7.1.1 Bill of Quantities for Water pan20,000 m3

Location: Ground is level to the dike's bermITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) Water pan Site Clearing m2 10,393.71

Excavation, common m3 20,615.34

Clay blanket m3 1,417.38

Sandy Clay m3 393.3

Riprap m3 394.62

Concrete pipe 0.6 m Diam m 21 Concrete pipe 1.0 m Diam m 6 Concrete m3 2.43

Reinforcing Bars m3 0.05

Formworks m2 8.4

Total


Location: DepressionITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) Water pan Site Clearing m2 10,393.71

Excavation, common m3 31,633.95

Clay blanket m3 1,417.38

Sandy Clay m3 393.3

Riprap m3 394.62

Concrete pipe 0.6 m Diam m 21 Concrete pipe 1.0 m Diam m 6 Concrete m3 2.43


Formworks m2 8.4

Total


Location: Ground is level to the base of the pan

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) Water pan Site Clearing m2 10,393.71


Embankment m3 35,857.67

Clay blanket m3 1417.38

Sandy Clay m3 393.3

Riprap m 394.62 Concrete pipe 0.6 m Diam m 21 Concrete pipe 1.0 m Diam m3 6

Concrete m3 2.43


Formworks m2 8.4

Total


Location: Along the waterway (One side is open)

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) Water pan Site Clearing m2 8,548.82



Clay blanket m3 1417.38

Sandy Clay m 393.3 Riprap m 322.38 Concrete pipe 0.6 m Diam m3 21

Concrete pipe 1.0 m Diam m3 6

Concrete (1:2:4) m3 2.43


Formworks 8.4 Total

7.2 Drawings for Water Pans

i. Water Facilities Drawings\Water Pans\Water Pan Capacity 10,000 cu.pdfii. Water Facilities Drawings\Water Pans\Water Pan in Natural Water.pdf



8.0 TECHNICAL PROCEDURES RAIN WATER HARVESTING

8.1 Parameters

The parameters outlined below are considered in the design of roof catchments and rain water harvesting tanks.

8.1.1 Runoff Coefficients

The following run-off coefficients should be used for calculating the fraction of the rainfall which can be harvested. The 90 % probability annual rainfall should be regarded as the dependable rainfall for the purpose of rainwater harvesting for domestic use.

Table 4.1 Run-off CoefficientSurface Type Run-off CoefficientRoof tiles, corrugated sheets, concreted bitumen, plastic sheetsBrick pavementCompacted soilUncovered surface, flat terrainUncovered surface, slope 0 – 5 %Uncovered surface, slope 5 – 10 %Uncovered surface, slope > 10 %

0.8

0.60.50.30.40.5

>0.5

8.1.2 Roof Catchments

A rough estimate of the required minimum roof area can be calculated as follows:-

A = 450 x DR

Where;A = Minimum roof area in m2

D = Total water demand in litres/dayR = The 90 % probability annual rainfall in mm.

8.1.3 Surface Runoff Catchment

Surface runoff can be generated either by rainfall or by the melting of snow or glaciers. In Kenya, surface run off comes mainly from heavy rainfall. Water from light showers is easily absorbed by soil storage and surface run off occurs only when the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground, and any depression storage has already been filled.

Surface run off can harvested using underground catchments and can be stored in reservoirs such as water pans, and underground tanks depending on water usage, available development funds and existing ground conditions.

Surface runoff from a hillside

Before building a runoff harvesting system, the following factors need to be considered:-a) If the system is to be on communal lands, the community must get together and agree on ownership, operation

and maintenance of the system

b) Assess whether the system will cause any problems for people in the area. Are there buildings, roads or paths along the runoff flow path that may be affected or cause water pollution?

c) Depending on the size of the proposed reservoir or tank, consider the availability of human labour or earth moving machinery for excavation and construction works.

Rain may fall on roads, fields, bushes or rock outcrops. If there is any possibility of contamination of the water by human or animal waste, it is vital to treat the water before use if it is used for domestic purposes. Risk of contamination with industrial or agricultural chemicals should be addressed prior to the construction of the system.

8.1.4 Selection of Tank Size

The required capacity of the collection tank should be calculated using available meteorological data showing the rainfall pattern of the area. But for rough calculations the tank capacity may be calculated by the formula:

C = 0.03 x D x (T 2),

Where:-C = Tank Capacity in m3D = Total water demand in litres/dayT = Longest dry spell in months, average year. The dry spell is the period when the average monthly rainfall is less than 50 mm.

8.2. Rainwater Harvesting

Rainfall records representative of the catchment are essential as the basis for reliable design of such a system. For a catchment of area A m2 receiving rainfall run in a month, the yield Y is calculated as follows:-

Y = f x A x R m 3 /month 1000

Where; f = catchment run off coefficient typical values as given in table 4.1.

If in an area, P is the population supplied by drinking water entirely from rainwater system, the quantity of water to be supplied per month, Q will be:-

Q = P x 30 x C m 3 /month 1000

Where C = daily consumption per person l/p/d.

With a large variation in rainfall distribution, the more critical parameter is the minimum storage volume required. Selecting the critical or design draught period, T months, from rainfall records, the minimum storage volume, V mm is given by:-

Vmin = N x 30 x C x T m3 1000

Hence a family of 6 will require a storage volume of 10.8 m3 to span a four month drought period.

8.3 Tank Design

The standard capacities of the ministry should be used. They are 10, 25, 50, 100, 150, 200, 300, 500, 800 and 1200 m3. Larger tanks may have capacities as required. The tank should:-

a) Be equipped with internal and external ladder or steps.



b) have a level indicator which can be read from outsidec) have inlet pipe which ends not more than 0.5 m above the floor to prevent air entrainmentd) Have outlet at a level at least 0.2 m above the floor.e) Have a scour pipe which allows complete emptying.f) have an overflow placed at least 50 mm above the normal top water level which allows the overflowing water to

be seen when in operation.g) be designed so that the ball valve (if any) is above the highest water level and is easily accessible from the

manhole.h) have ventilation pipes covered with nylon nets.i) have outside walkway and handrail (only elevated steel tanks)j) not usually have any portioning k) not have a ball valve on the inlet pipe when a pumping main feeds it.l) be covered and have a lockable manhole cover, universal type

8.4 Bills of Quantities for Storage Tanks

Roof rainwater harvesting Technology Specific Variables

Parameters: 1

Max size Plastic tank m3 23 Max size Ferrocement tank m3 300 Max size Masonry tank

Area of Roof Catchment m2 15 Length of gutters m 4 Volume of storage tank m3 2 Average capacity m3/day 0.031

Design 1: Plastic Tanks Litre 23,000

Volume of Tank 1

Number of Storage tanks m 2.04

Size of Platform = Diameter of Tank + 20% of platform size 10%

Bills of Quantities ITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1.1 Excavate oversite to remove topsoil m2 4.2 1.6 Compacted hardcore bed m3 0.6 2.1 Provide and place 75mm thick mass concrete blinding

class 1:3:6 m3 0.2

2.2 Provide, place and compact structural concrete C20; 1:2:4

m3 0.6

2.5 Supply, cut, bend and place high tensile steel bars Kg 15 3.3 225 mm natural stone walling m2 1.7 3.4 Plastering m3 0.03 3.5 Cement screeding 32 mm thick m2 4 4.1 Plastic Tank 2300Litre Item 1 4.2 Aluzinc Gutters incl fittings & pipes (+50%) m 4 4.3 Pipe and fittings (20mm bibcock and fittings) Item 1 4.4 Misc. paving, finishing work etc Item 1

Total

Technology Specific Variables Parameters: 2Area of Roof Catchment 100

Length of gutters 20 m

Volume of storage tank 12 m3

Average capacity 0.204 m3/day

Design 1: Plastic Tanks

Volume of Tank 15,000 Litre

Number of Storage tanks 1

Size of Platform = Diameter of Tank + 20% 3.10 m

Thickness of platform 10% of platform sizeBills of Quantities

ITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1.1 Excavate over site to remove topsoil m2 9.6

1.6 Compacted hardcore bed m3 1.4 2.1 Provide and place 75mm thick mass

concrete blinding class 1:3:6 m3 0.5


m3 2.5

2.5 Supply, cut, bend and place high tensile steel bars

Kg 63

3.3 225 mm natural stone walling m2 3.8 3.4 Plastering m3 0.08 3.5 Cement screed 32 mm thick m2 10 4.1 Plastic Tank 15000Litre Item 1 4.2 Aluzinc Gutters incl fittings & pipes

(+50%)m 20

4.3 Pipe and fittings (20mm bibcock and fittings)

Item 1

4.4 Misc. paving, finishing work etc Item 1 Total



Technology Specific Variables Parameter: 3

Area of Roof Catchment 300 m2








Thickness of platform 10% of platform sizeITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1.1 Excavate oversite to remove topsoil m2 25.9 1.6 Compacted hardcore bed m3 3.9 2.1 Provide and place 75mm thick mass concrete

blinding class 1:3:6 m3 1.3


m3 8.0

2.5 Supply, cut, bend and place high tensile steel bars

Kg 200

3.3 225 mm natural stone walling m2 10.4 3.4 Plastering m3 0.21 3.5 Cement screeding 32 mm thick m2 26 4.1 Plastic Tank 23000Litre Item 2 4.2 Aluzinc Gutters incl fittings & pipes (+50%) m 40 4.3 Pipe and fittings (20mm bibcock and fittings) Item 1 4.4 Misc. paving, finishing work etc Item 1

Total

Technology Specific Variables Parameter: 4

Area of Roof Catchment 1,000 m2








Thickness of platform 10% of platform sizeITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1.1 Excavate oversite to remove topsoil m2 64.8

1.6 Compacted hardcore bed m3 9.7 2.1 Provide and place 75mm thick mass concrete blinding

class 1:3:6 m3 3.2


m3 20.1

2.5 Supply, cut, bend and place high tensile steel bars Kg 502 3.3 225 mm natural stone walling m2 25.9 3.4 Plastering m3 0.52

3.5 Cement screeding 32 mm thick m2 65 4.1 Plastic Tank 23000Litre Item 5 4.2 Aluzinc Gutters incl fittings & pipes (+50%) m 100 4.3 Pipe and fittings (20mm bibcock and fittings) Item 1 4.4 Misc. paving, finishing work etc Item 1 Total



Bills of Quantities for a 15 m3 brick tank ITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1 Cement Kg 12502 Lime Kg 1003 River Sand Tonnes 64 Crushed stones Tonnes 4 5 Hardcore 4”x6” Tonnes 16 Blocks/Bricks Units 5557 Water Litres 10008 Weld mesh 8”x4’ No. 8 Sheets 109 Barbed wire gauge 12.5, 20kg Rolls 210 Twisted Bars Y12 M 1511 Binding wire gauge 8 Kg 112 uPVC 4” pipe m 313 G.I. Pipe ¾” m 314 G.I. tap, elbow, socket nipple ¾” Units 114 Galvanised coffee mesh m2 115 Mosquito mesh m2 0.516 Timber 6”x1” m 9017 Poles m 818 Nail 3” Kg 4

Total

Bills of Quantities of Quantities for a 50m3 Masonry R.C tankITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1 Foundation 1 1.1 Removal of top soil up to 50 mm depth m2 19.61.2 Excavation for foundation m3 11.81.3 Laying of 300mm hardcore for

foundationm2 19.6

1.4 50 mm 1.2.4 concrete blinding m2 19.61.5 Finished floor concrete m3 11.81.6 Reinforcement for foundation

Y 8 bars Kg 26Y12 250

2 Walls2.1 Masonry wall m2 47.12.2 Y 8 reinforcement rings for the wall in

between coursesNo 28

4.2 Aluzinc Gutters incl fittings & pipes (+50%)

m 12

4.3 Pipe and fittings (20mm bibcock and fittings)

Item 1

4.4 Misc. paving, finishing work etc Item 1 Total

Bills of Quantities for a 46 m3 ferrocement tankITEM ITEM DECRIPTION UNIT QTY RATE AMOUNT (Ksh)1 Cement Kg 25002 Lime Kg 503 River Sand Tonnes 104 Crushed stones Tonnes 45 Hardcore 4”x6” Tonnes 16 BRC Mesh No 65 m 337 Water Litres 35008 Chicken mesh 25mm, 0.9m m 809 G.I wire, 3mm Kg 2510 Twisted Bars Y12 M 311 Binding wire gauge 8 Kg 112 uPVC 4” pipe m 313 uPVC 2” pipe m 314 G.I. Pipe ¾” m 3.415 G.I. tap, elbow, socket nipple ¾” Units 116 Galvanised coffee mesh m2 117 Mosquito mesh m2 0.518 Timber 6”x1” m 3619 Timber 2”x 3” m 4620 Poles m 821 Bolts 6 x 120 mm No 1222 Plastic bag No 5023 Sisal twine Kg 524 Nail 3” Kg 4

Total

8.5 Drawings for Roof Catchments

i. Water Facilities Drawings\Roof Catchment\Plastic Tanks.pdf ii. Water Facilities Drawings\Roof Catchment\15cu.m Tank Built of Soil Compressed Bricks.pdf iii. Water Facilities Drawings\Roof Catchment\Bricks Tank.pdf iv. Water Facilities Drawings\Roof Catchment\Ferrocement Tank.pdf v. Water Facilities Drawings\Roof Catchment\25 and 50 RC Tank Details.pdf vi. Water Facilities Drawings\Roof Catchment\RC Tank.pdf vii. Water Facilities Drawings\Roof Catchment\RC Tank.pdf



9.0 ROCK CATCHMENT

Rock catchments system consists of two components, a catchment area formed by a bore rock surface and a pond normally formed by concrete weir. The rock catchment is an extremely low cost method of community water supply, which lends itself well to community participation. The storage capacity of the reservoir may vary from 20 m3 to 10,000 m3 depending on the size of the rock outcrop, and its area extent, elevation and gradient. The storage capacity can be estimated using equation below:-

S = S (I) + I – D

Where:-S = storage at the end of the monthS (I) = the amount stored at the end of previous monthI = product of monthly rainfall x rock area x loss factorD = amount of water used by a family in a given period

9.1 Bills of Quantities for Rock Catchment

9.1.1 Bill of Quantities for Rock Catchment 2m High and 10 m Length Dam

ITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Dam Site Clearance m2 65.00

Rock excavation m3 65.00

Rubble Masonry m3 50.00

GI pipe 110 mm m 50 B. Tap Station Concrete m3 1.21

Reinforcement bars kg 10 Gravel bedding m3 0.7

Formworks m2 4.59

C. Drain Concrete m3 1.8

Reinforcing Bars kg 20 Gravel bedding m3 0.8

Formworks m2 18

D. Livestock Trough Concrete m3 0.71


Formworks m2 4.8

Total

9.1.2 Bill of Quantities for Rock Catchment 2m High and 15 m Length Dam






Formworks m2 4.59



Formworks m2 18



Formworks m2 4.8

Total

9.1.3 Bill of Quantities for Rock Catchment2m High and 20 m Length Dam






Formworks m2 4.59



Formworks m2 18



9.1.3 Bill of Quantities for Rock Catchment2m High and 20 m Length Dam



Formworks m2 4.8

Total

9.1.4 Bill of Quantities for Rock Catchment2m High and 30 m Length DamITEM DESCRIPTION UNIT QUANTITY RATE AMOUNT(Kshs) A. Dam Site Clearance m2 195.00





Formworks m2 4.59



Formworks m2 18



Formworks m2 4.8

Total

9.2 Drawings for Rock Catchment

Water Facilities Drawings\Rock Catchment\Rock Catchment.pdf

10. SPRING PROTECTION

Surface springs occur where groundwater emerges at the surface because an impervious layer of ground prevents further seepage downwards. The rate of flow of water from the spring will vary with the seasons. It is necessary to measure the spring’s flow at the end of the dry season to determine its potential reliable yield.

An inspection of the ground upstream of the spring is essential to ascertain that there is no danger of pollution or, if there is, that measures can be taken to prevent it. A spring source can be used either to supply a gravity scheme or just to provide a single outlet, running continuously, which is set at a sufficient height to allow a bucket or container to be placed below it. To prevent waste, any flow which is surplus to that required for domestic use can be used to irrigate gardens.

If the flow from the spring is not sufficient to meet peak demands during the day, a storage tank can be incorporated into the structure of the spring protection. This enables the flow from the spring over the full 4 hours to be stored, then used throughout the day to meet intermittent demands by means of a tap in the structure.

10.1 Methods of Spring Protection

Many different methods of getting the clear spring water from its source into the bucket or pipeline are described in the textbooks. The essential matters are to protect the spring water from pollution, and to arrange for it to be delivered at a suitable level so that it falls directly into a container. The following points should be considered when investigating a potential spring source:

• Making sure that the spring is not really a stream which has gone underground and is re-emerging• Making sure that the source and the collecting area are not likely to be polluted by surface runoff• Checking that there are no latrines within 30 metres upstream of the spring• Fencing the area around the spring tank to prevent pollution by children or livestock• Making sure that if the spring is to be connected to a piped water system it is on higher ground than the area to

be supplied• Taking care that the spring tank is not built on swampy ground or on land which is subject to erosion or flooding

and that the flow from the protected spring itself will not cause erosion or damage

10.2 Typical Spring Flow Rates

A flow in excess of 0.1 litres per second is sufficient to fill a 20 litre container in just over 3 minutes, which is an acceptable waiting time. From such a spring a daily useful yield of about 3000 litres can be expected, which is enough water for about 150 people. If the flow were to be only 0.05 litres per second it could still can be made to supply the same population by incorporating a storage tank of 1 cubic metre capacity. If the flow were to be 0.5 litres per second or more the source would be suitable to supply multiple outlets or a piped gravity scheme.

10.3 Stages in Spring Protection

The stages in a typical spring protection are shown in the drawing;Water Facilities Drawings\Springs\Spring protection.pdf

10.4 Spring Protection Drawings

Water Facilities Drawings\Springs\Protected Spring Details.pdf



11. GRAVITY SCHEMES

11.1 Introduction

In considering the sustainability of a water supply project in the developing world, the choice of technology to be used should favour the use of unpolluted sources; this eliminates the need for treatment which may require chemicals, energy or skilled manpower. A gravity-fed supply from a small upland river, stream or spring, impounded within a protected catchment, is an example of such a choice. An additional benefit is that, using the force of gravity, water can be transported by pipe work to tap stands placed near to homes, thus reducing the drudgery involved in carrying water a long way.

The capital costs of gravity schemes are, on average, higher than the costs of schemes which obtain water from underground sources. This is due mainly to the cost of long pipelines from the upland sources down to the villages and partly to the cost of providing storage tanks. Running costs are usually low, with regular maintenance needed only for replacing tap washers, cleaning screens, etc. Reliability is usually high and consequently the level of service provided is good. The usual components of a gravity scheme are the source (stream, spring, catchment, dam or intake), main pipeline, storage and break-pressure tanks, and distribution pipelines and tap stands. The communities which benefit from the scheme are usually involved in large commitments of time and effort in the construction work associated with these components. Considering the components in turn:

11.2 Sources

A source may have several elements:

(a) Spring/stream

If a spring or stream is to be the source, it must be unpolluted and must be one which flows throughout the year; the flow must be measured in the dry season in order to know what yield can safely be relied upon. When a spring is used, the springhead must be protected as detailed in the drawing. The water must be piped directly from the eye of the spring to prevent any pollution affecting the supply.

(b) Catchment:The catchment area of a spring or stream must be free of animals and cultivation; if only a small area is involved it may be fenced off completely. Communities often enforce bylaws to exclude people and animals from the area.

(c) Dams and intakes:Dams in streams are generally small; their purpose is to provide a small pond so that a controllable draw-off pipe can be built into the wall of the dam at a level higher than the bed of the stream. Unlike larger dams, which impound water to provide storage over a dry season, these small dams overflow for most of the time. The crest of the dam acts as an overflow weir, except at the sides, where it is raised to prevent scouring of the banks.

A dam is usually constructed of concrete, block work or masonry, preferably founded on rock. Rock, or some other impermeable material, should also form the basin of the impoundment. Twin intake pipes (one in use, one in reserve) are built into the wall of the dam; on the upstream side of the dam they have strainers or screens; on the downstream side they are fitted with control valves. A scour pipe is also built into the dam, at low level, with a stop valve on the downstream side, and is used periodically to drain the pond and to clear accumulated silt etc.

11.3 Main pipeline

The route of the pipeline from the intake to the storage tank must be surveyed and a drawing made of the optimum hydraulic gradient line, in order to determine the pipe size needed to deliver the design flow. In rocky areas the pipeline will probably be laid above ground and will be galvanised mild steel tubing, anchored on saddles. Elsewhere, the pipeline will be laid in trenches, to protect it from damage, and will usually be plastic pipe (MDPE – medium density polyethylene). Close supervision of laying and connection of water pipes must be done by a professional including pressure testing of the system. This prevents any possibility of water leakages along the pipeline which would otherwise lead to large water losses and contamination by micro-organisms from soil.

11.4 Storage and Break-Pressure Tanks

To reduce operating pressures, it is sometime necessary to introduce break-pressure tanks, which are usually made of concrete or ferrocement. If such tanks are used, the hydraulic gradient starts again at tank water level. If suitably sized, these tanks can be used within the system as storage tanks to meet peak demand.Storage tanks are usually constructed within the system to provide a total volume of storage equivalent to one day’s consumption. The tanks may also be sited so as either to limit the maximum pressure in distribution pipelines or to sustain a pressure of at least 3 metres head at each tap stand whilst meeting the peak demands in the morning and evening.

Capacities of tanks range from 10 to 100 cubic metres, depending upon the size of the population to be served. Various materials have been used to construct them: masonry, reinforced concrete, concrete block work, ferrocement, galvanised mild steel and GRP panels. In fat areas, tanks may have to be elevated on block work support structures. Tanks are roofed and, typically, are provided with a float controlled inlet valve, twin outlet pipes with stop valves, a scour pipe at low level for emptying and cleaning out, and an overflow pipe led well away from the tank. The roof of the tank should have a sealed access manhole, and ventilators, covered in mesh fly screen, to allow air to be exhausted or admitted air when raising or lowering the water level in the tank.

11.5 Distribution Pipelines and Tap Stands

A distribution system of small diameter MPDE pipes, laid in trenches, feeds tap stands around the village. Each tap stand should serve about 150 people and should be positioned so as to reduce uniformly the maximum distance people have to carry water. Tap stands have several components: a concrete post supporting a 15mm mild steel riser pipe from the pipeline up to a bib-cock which should discharge at least 0.1 litres per second; a concrete stand on which to place a bucket; a concrete apron to collect spillage; and a gutter and drainage to a soak away, in order to prevent the breeding of mosquitoes and the development of a muddy mess.

Tap stands should have a fence around them to keep animals away and each one should have a nominated person, or caretaker, to keep the area clean and tidy.



12. PUMPS

12.1 Hand Pumps

12.1.1 Main Principle of Hand Pumps

There are many different types of hand pump. However, most of them are positive displacement pumps and have reciprocating pistons or plungers. In a piston pump, the piston is fitted with a non-return valve (the piston valve) and slides vertically up and down within a cylinder which is also fitted with a non-return valve (the foot valve). Raising and lowering the handle of the pump causes vertical movement of pump rods which are connected to the piston.When the piston moves upwards, the piston valve closes and a vacuum is created below it which causes water to be drawn into the cylinder through the foot valve, which opens. Simultaneously, water above the piston, held up by the closed piston valve, is displaced upwards; in a simple suction pump it emerges through the delivery outlet; in a pump with a submerged cylinder it is forced up the rising main. When the piston moves downwards, the foot valve closes, preventing backflow, and the piston valve opens, allowing the piston to move down through the water in the cylinder.

12.1.2 Range of lift

The ranges over which water can be lifted are grouped in the following categories:

Suction pumps 0 – 7 metresLow lift pumps 0 – 15 metresDirect action pumps 0 – 15 metresIntermediate lift pumps 0 – 5 metresHigh lift pumps 0 – 45 metres, or more

(a) Suction Pumps

At shallow lifts the cylinder and piston operate by suction and can be housed in the pump stand above ground. In practice, the maximum suction lift is about seven metres (i.e atmospheric pressure less about 30% system losses due to the ineffectiveness of seals, friction etc) and defines the working range of the suction pump. Suction pumps have to be primed where seals have dried out or have been replaced; therefore they can be contaminated by dirty priming water. They have a limited range of application, but are the most numerous hand pumps in the world, mainly because they are relatively cheap and are suitable for use as a household pump.

(b) Low Lift Pumps

These operate in the range 0–15 metres. With lifts above seven metres, the cylinder and piston have to be located down the well, or borehole, and preferably below water level in order to provide a positive suction head. Theoretically, the lift could be achieved by operating with the cylinder seven metres above the water table but it is usually better to provide a positive suction head, as this assists pumping.

(c) Direct Action Pumps

In the low lift range some piston hand pumps are designed to operate as simple direct action pumps, ie ones which operate without the help of leverage, linkages and bearings. Direct action pumps depend upon the strength of the operator to lift the column of water.

(d) Intermediate and high lift (deep well) hand pumps

An intermediate lift pump operates in the range 0 – 5 metres and a high lift one in the range 0 – 45 metres. Some of the high lift hand pumps can operate at lifts of 60 metres or more, albeit with reduced output.Intermediate and high lift piston hand pumps are designed so as to reduce, by means of cranks or levers, the physical effort required when pumping. They have to be more robust and are provided with bearings and components capable of handling the larger stresses which are imparted by the pumping efforts required.Examples of high lift hand pumps i.e. Afri Dev and India Mark IV pumps are shown in the drawings

12.1.3 Choice of Pumps

The term VLOM (Village Level Operation and Maintenance) was coined during the World Bank/UNDP Rural Water Supply Hand pumps Project which, from 1981– 91, considered the availability around the world at that time of hand pump technologies and maintenance systems. A series of performance tests was undertaken: laboratory testing of 40 types of hand pump and field performance monitoring of 700 hand pumps. It was concluded that centralised maintenance systems were the cause of many problems and that village level maintenance was desirable, but only feasible if the design of the pump made it possibleInitially the VLOM concept was applied to the hardware, with the aim being to develop pumps which were designed to be:

• Easily maintained by a village caretaker, requiring minimal skills and few tools• Manufactured in-country, primarily to ensure the availability of spare parts• Robust and reliable under field conditions• Cost effective

Subsequently, the VLOM concept was extended into software and organisational matters. Thus the “M” in “VLOM” has become “management of maintenance”, for the success of a project was generally seen to be dependent on a strong emphasis on village management. Therefore the following elements were added:

• Choice by the community of when to service pumps• Choice by the community of who will service pumps• Direct payment by the community to the caretakers

The application of VLOM principles, when considering pump selection, often involves compromising one principle to take advantage of another. A hand pump with a low rate of breakdown might be thought preferable to another with a higher rate. However, a hand pump that breaks down monthly, but can be repaired in a few hours by a local caretaker, is preferable to one that breaks down once a year but requires a month for repairs to be completed and needs replacement parts to be imported and skilled technicians to be available.

12.1.4 Performances of Hand Pumps

Name Type Lift Range (m)Discharge Litres/min VLOM Origin

Afri Dev Deep well 7 25 22 15 Yes Kenya e.t.cAfri Dev Direct action 7 15 26 22 Yes Kenya e.t.c

Bucket pump Improved bucket and rope 6 15 5 10 Yes ZimbabweConsallen Deep well 7 25 45 14 14 14 UKIndia MK II Deep well 7 25 14 12 12 12 No IndiaIndia MK III Deep well 7 25 45 India

MonoliftDeep well progressing cavity 25 45 60 16 16 9 No UK, South Africa

Nira AF 76 Deep well 7 25 25 26 No FinlandNira AF 84 Deep well 7 52 45 23 22 21 No FinlandNira AF 85 Direct action 7 15 26 24 Yes FinlandNew No. 6 Suction pump 7 36 BangladeshTara Direct action 7 45 24 23 Yes BangladeshVergnet Deep well diaphragm 0 45 24 25 No France Wind Lass 15 Universal


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 12.1.5 Hand Pumps Installation Details

12.1.5.1 Platform Design

If the area around a well is allowed to become dirty, and waste and stagnant water is allowed to accumulate, it will become a source of infection for the users. Standing in bare feet in stagnant water or mud is a serious health risk in the tropics since the open water provides an ideal breeding ground for many types of parasite and/or disease carrier. Awareness of the direct links between hygiene and water must start at the collection point, otherwise the possible benefits from an improved water supply will be lost. The construction of a platform (or slab) at the wellhead is an important contribution to the general hygiene in a community. In addition to discouraging the accumulation of stagnant water at the surface, the slab will help to prevent the contamination of the well through the infiltration of dirty water back into the aquifer

The following points are important:

a) The slab surrounding the water point should be made as wide as possible from properly made reinforced concrete of good quality. The water outlet (spout should be placed in the centre of the slab, so that it collects the spill water, which then can run away thorough the drainage channel.

b) All surfaces should slope towards the drainage channel and the edges of the slab should be raised.c) The slab should be well reinforced with steel wire, to prevent cracking. Dirty water can pass through cracks in a

poorly constructed slab and contaminate the well beneath.

d) The shape of the slab is not as important as its capacity to drain water away from the well as quickly as possible and to ensure wastewater dispersal in a hygienic manner.

e) Where possible, the drain can lead to an area of vegetation, such as banana plants or a vegetable garden. If this is not an option, a soak-pit can be built or a trough for watering livestock can be provided.

f) It is important that construction of the slab does not commence until the soil around the well, which was disturbed by the construction activities, has had an opportunity to settle properly

Consultation with the community is a must before a decision is taken on the platform layout. In the following three pages you will find typical platform designs for handpumps installed on boreholes or on dug-wells. These are indicative layouts and can be modified to suit communities’ needs, which may include the following:

a) Facilities for washing clothes,b) Facility for bathing,c) Trough for cattle watering,d) Collection of water for small scale irrigation etc.

12.1.5.2 Platform Construction

(a) General Comments

Sustained safe drinking water supply and sanitation facilities are essential to improve the living conditions of the rural population. The provision of safe water helps to combat water borne diseases and improves community health in general. Benefits of a safe water supply can reach far beyond considerations of public health and have a positive influence on the general well being, economic status and quality of life in a community.

(b) Protection of Water Source

If a well site is chosen and the well drilled (or dug) into the ground at a site which is elevated and away from water logged areas during the rainy season, the water which percolates from an underground aquifer into the well should be pure enough to drink. However, a water point obviously attracts a great deal of human contact. This is a potential source of contamination and should be protected against.

12.1.6 Siting of the Well

The safety measures are as follows;

• The well should be in an elevated place, so that during the rainy season• the water will run away from it, rather than into it.• It should be at least 30 meters away from a latrine and uphill of the latrine.• It should be at least 30 meters away from a cattle kraal, and uphill of the kraal.• It should be well away from any depressed area in the ground, such as hollows that are used for rubbish tipping,

hollows that are used for brick making or any other areas where water might collect;

Fig 12.1 Locating a well with hand pump

12.1.7 Fencing of Water Source

In addition to constructing a slab, it is important to erect a good fence around the water point. This can be done immediately after the construction of the well is finished, and should give enough space to operate the handpump. The advantages of fencing are that it serves to define quite clearly, for the whole community, the area of the well and it keeps animals away from the wellhead. In some cases, it may be necessary to have a gateway to keep out smaller animals such as pigs and goats.

The fencing can be made of suitable local materials like wood or stones. Problems of replacement and repair can be avoided altogether, by using a living hedge as fencing. Whatever type of fencing is used, it is important that access by the well users is guaranteed


Life Cycle Cost

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

4,500,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Years

Cu

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Generator system

Sqflex System


12.2 Rope Washer Pumps

The rope washer pump consists of a rope with knots or rubber washers, whose diameters are slightly less that the diameter of the pipe, placed at intervals along it. This assembly is drawn up inside as rising pipe and is capable of drawing relatively large volumes of water to the height of the pump. During operation, the pipe is inserted in the water and the rope drawn upwards through the pipe by mean of winding drum with a crank. Water is also drawn up and discharged at the top. The rope and washer pass round the winding wheel and return to the bottom of the pipe thus completing the circuit. The design can be modified to avoid slippage of the rope o the pulley by using old tyre casings to make the pulley wheel. To prevent the washer getting caught and to support the bottom of the pipe above the bottom of the well of the river bed, a suitable pipe stand and rope guide is necessary. Friction should be kept low by allowing leakage between the washers and the pipe stem. A demonstration of a rope and washer pump is presented in drawing Water Facilities Drawings\Pumps\MANUAL PUMPS.pdf

This type of technology is suitable for abstraction of shallow wells of put to 10m depth or from rivers and streams. In Kenya the pumps are being locally manufactured in the Jua Kali sector and its cost is relatively low. In addition, it has no valves and does not require complicated resources. However it has limited lift and poor pumping efficiency, as water is allowed to leak through the valves.

12.3 Solar Pumps

Solar pumps are becoming increasing useful for both wells and boreholes especially in rural arid areas where electricity supply is not available. Manufactures of such pumps can specify submersible pumps of various ranges of lifts up to 100m. Compared to generator pumps that were previously in use for such regions, solar pumps prove to present a reasonable saving on cost in the long term. An example of such type of a pump is the SQ Flex Grundfos solar pump.

12.3.1 Comparison of Solar Pumps with Generator Pumps

(a) Table 12.3 Water Cost ComparisonWater Cost Comparison

Generator

Pump SQ FlexSystem Output Per Hour m3/h 2.3 1.8Operation Hours Per day 5.5 7.0System Output (m3/day) m3/day 12.7 12.6Annual System Output (m3/yr) 300 days m3/yr 3,795.0 3,780.0

Cost for 1m3 (1000Litres) KShs 55 4

(b) Fig 12.3 Cumulative life cycle running cost

12.3.2 Installation of Solar Pumps

With little training and following of instructions on the manufacturers manual, it is easy for local artisan to install solar pumps for wells and boreholes. A system of the pump and elevated tank may be obtained as showing in the drawing; Water Facilities Drawings\Pumps\SQFLEX SOLAR.pdf

12.4 Pumps for Boreholes with Electricity

There exist from different manufacturers a wide range of submersible pumps that can be used for pumping water for deep boreholes where electricity is installed. Several factors should be considered while selecting pumps;

• Pump efficiency: Does the pump cause high power consumption in comparison to its discharge?• Pump material: - Is the material wear resistant for water with high chemical composition• Installation costs:

12.4.1 Example of Submersible Pumps for Boreholes with Electricity

Grundfos provides submersible pumps with the following parameters

• ISO certified rating curves• Flow rate Q of 0.1 – 280 m3/h• Pumping Head; up to 670m• Stainless steel DIN W Nr 1.4301 (AISI 304) material for pumps to use in aggressive liquids



12.5 Play Pumps

The play pump is a specifically designed playground roundabout that pumps ground water from bore holes into sealed holding tanks. It is powered by the energy of the children turning the roundabout, keeping costs and maintenance to an absolute minimum, while entertaining the children. The low maintenance merry-go-round turns as easily as a standard playground fixture.

12.5.1 Operation of the Play Pump

The play pump operates on basic windmill equipment which is accessible in co-operative stores throughout Africa and can be found in most other parts of the world as well. Below the ground is a positive displacement cylinder on rising rods and pipes. The equipment inside the unit converts the rotational movement into a vertical movement by a driving mechanism consisting of only two working parts. This makes the pump highly effective, easy to operate and very economical. Depending on the cylinder, it pumps up to about 4 litres per revolution which is much more efficient than the traditional hand pump. The figure 12.5 demonstrates the operation of a play pump.

Fig 12.5 Operation of a Play Pump1

While children have fun spinning on the PlayPump merry-go-round (1), clean water is pumped (2) from underground (3) into a 2,500-liter tank (4), standing seven meters above the ground.A simple tap (5) makes it easy for adults and children to draw water. Excess water is diverted from the storage tank back down into the borehole (6).The water storage tank (7) provides a rare opportunity to advertise in outlaying communities. All four sides of the tank are leased as billboards, with two sides for consumer advertising and the other two sides for health and educational messages. The revenue generated by this unique model pays for pump maintenance.

The design of the PlayPump water system makes it highly effective, easy to operate and very economical, keeping costs and maintenance to an absolute minimum. Capable of producing up to 1,400 liters of water per hour at 16 rpm from a depth of 40 meters, it is effective up to a depth of 100 meters

12.5.2 Availability of Play Pumps

The play pump has not yet found its use in Kenya. At the moment Roundabout Water Solutions of South Africa in Association with Play Pumps International (US) are the main manufacturers and implementers of play pumps in the world. The option of play pumps can be one of the best for school water supply.

12.6 Wind Pumps

With wind pumps, moving air turns a "rotor" , and the rotational motion of the blades is transferred to harmonic motion of the shaft, which is used to pump water or drive other mechanical devices such as grain mills. Depending on the terrain, some types of modern wind pumps generate electrical energy to drive pumps. Water from wells as deep as 200m can be pumped to the surface by wind pumps.

1 Play pumps International; http://www.playpumps.org

In off-grid areas where there is sufficient wind (3-5 m/s) and ground water supply, wind pumps often offer a cost-effective method for domestic and community water supply, small-scale irrigation and livestock watering.

12.6.1 Technical Information

To select a suitable wind pump, the following information is needed:Mean wind speed - Extractable power in the wind varies as the third power of the wind speed , thus a good wind regime is essential.

• Total pumping head • Daily water requirement • Well draw down • Water quality • Storage requirements

Using these and manufacturer's data, a wind pump can then be chosen. Below is a sample performance table for the Kijito Wind pumps.

Daily delivery (m3/day)Model 3.7 m 4.9 m 6.1 m 7.4m

Wind speed (m/s)

2-3 3-4 4-5 2-3 3-4 4-5 2-3 3-4 4-5 2-3 3-4 4-5

Head (m) 10 10 28 59 21 71 150 39 107 227 61 167 35420 5 14 29 10 35 75 19 53 113 30 83 17740 7 15 5 18 37 10 27 57 15 42 8980 3 7 3 9 19 5 13 28 8 21 44

120 5 6 12 3 9 19 14 29160 4 4 9 7 14 5 10 22200 3 7 5 11 4 8 17240 6 9 7 14

12.6.2 Factors Affection Sustainability of Wind pump Technology:

a) Investment Cost: Although the lifetime cost of wind is often less than diesel or petrol-powered pumps, the investment cost of purchasing a wind pump is usually higher than that of diesel pumps. Groups purchasing water supplies often have limited funds and cannot take a long-term view toward the technology.

b) Maintenance and Service: Technicians and buyers are often unfamiliar with wind pump technology, and pumps in remote locations often break down because of a lack of servicing, spare parts, or trained manpower to administer them. In reality, wind pumps are less maintenance intensive than diesel pumps. However, the wind pump technology is "strange" to many people and there is a need to train maintenance staff where pumps are installed.

c) Need for water storage: Because wind pumps only supply water when the wind is blowing, there is almost always a need to build storage tanks to avail water when the wind is not blowing.

d) Low output: With wind speeds between 2.5-5 m/s, average sized wind pumps will deliver between 100 to 500 m4 (i.e. 10 to 50 m3 at 10m depth or 2 to 20 m3 at 50m depth, see table below). Such outputs may be too low for large communities or irrigation requirements

12.7 Other Drawings: - Community Water Point

Water Facilities Drawings\Community Water Point\Water Kiosk Plan,.pdf


http://www.playpumps.org/


WATER FILTRATION

Introduction

Water sources can be easily contaminated due to unhygienic waster disposal, unscientific water extraction methods, and poor water collection methods.

Contamination of water sources takes place in 3 main forms namely:-• Physical contamination: It is defined by the characteristics of water with respect to sense of sight, touch,,

taste or smell and includes characteristics such as PH, turbidity, colour, odour and temperature.• Chemical contamination: It is concerned with capacity of water to dissolve various salts. Some of the ions

dissolved in water include calcium, magnesium, sodium, nitrate, phosphate etc.• Biological contamination: It is due to bacterias, fungi, viruses, protozoa and other organisms

Regular water testing is recommended to reduce the risk of consuming contaminated water since many contaminants are not easily detected by the senses. Even if contamination can be detected by colour, smell, or taste, only a laboratory test can tell you the quantity of contaminant actually present. Testing should always be done by a reputable or certified laboratory

There are a number of methods of water filtration, each with varying degrees of effectiveness and varying costs. The common methods are

• Sand filters• Boiling • Activated carbon water filters • Ultra violet water filters • Water distillation • Reverse osmosis method

The general purpose of filtering water is to improve the water's hygiene and aesthetic qualities. Over the years sand filters have is the most affordable and effective water filtrations at community levels.

A brief description of the above filtration methods is included below:-

Sand Filters

There are two commonly used types of sand filters, namelya) Slow sand filters- treats 2 to 6m3/m2/dayb) Rapid sand filters- treat 100 to 150 6m3/m2/day

Although there are many other ways of treating water, no single process has been to be as effective in simultaneously improving microbiological and physio-chemical qualities of water as slow sand filtration. Therefore, slow filters are highly preferred in rural areas where skilled labour is scarce, land and sand is plenty as the system is easy to operate and maintain.

A simple slow sand filtration system can be made of 1000 litre plastic water tank containing filters made of pebbles and sand of different sizes can be used to filter 2500-3000 litres of water per day which is enough to serve 50 people.

Other construction materials for construction of the tank include concrete, ferro cement, brick, blocks depending on locally available materials.

Advanced systems can be provided with a synthetic fabric filter to improve effectiveness. The fabric filter prevents most organic matter, silt and mud particles from passing through. This system can be fed by gravity flow or through solar or fuel pumps and is replicable at community or household level.

A slow sand filter system with filter and control tanks (on left) and storage tank (on right).

Advantages of Sand filters

a) It enhances physical filtration: The fabric filter prevents most organic matter, silt and mud particles from passing through.

b) It enhances biological filtration: Biological community builds up on fabric filter and sand bed, scavenging and breaking down pathogens and organic matter in raw water.

The system is capable of removing faecal coliform and streptococci with an efficiency of 99%. It also removes pathogenic bacteria which cause Cholera, Typhoid, Dysentry, Amoebic dysentery, Diarrhea, Giardia enteritis, Hepatitis etc.

Boiling of Drinking Water

Boiling is one of the surest methods to make water safe to drink and kill disease-causing microorganisms at household level. It is recommended that water is boiled vigorously for one to three minutes to kill water contaminate. In order to improve the flat taste of boiled water, it may be aerated by pouring it back and forth from one container to another and allowing it to stand for a few hours, or add a pinch of salt for each liter of water boiled.

This technology requires a lot of energy from firewood, coal, fuel gas, solar, biogas etc depending of the type of energy available and cost implications. It does not require specialised skills and maintenance cost is quite low. It is not suitable for use large scale due to high energy requirement. It is not appropriate for water that is heavily polluted or subject to chemical contamination.

Activated Carbon (AC) Water Filters

Activated Carbon Filtration is an established technology that works through absorption of the water contaminating compounds, primarily to remove taste and odour and some harmful contaminants. Activated Carbon (AC) is a highly porous material with a very large surface area and can be obtained from coal or peanut shells which are slowly heated in the absence of air to produce a high carbon material. Chemical pollutants are attracted to and held by the activated AC's surface. The carbon is activated by passing oxidizing gases through the material at extremely high temperatures. The activation process produces the pores that result in such high adsorptive properties.

These water filters are best suited for the removal of organic compounds whose basic elements are carbon and hydrogen and are often responsible for taste, odour and colour problems. AC filtration also removes chlorine, pesticides, industrial solvents (halogenated hydrocarbons), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs).

However, AC filtration does not remove microbes, sodium, nitrates, fluoride, and hardness. Lead and other heavy metals are removed only by a very specific type of AC filter.


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme Activated Carbon Filtration Equipment

AC filters can be placed in the three following categories as shown along side: 1) pour-through; 2) faucet-mounted; and 3) high-volume.

a) Pour-through AC filters are the simplest container. Water is poured in the top into the container and filters by gravity through the filter (activated carbon) to the bottom. They are quite slow and handle only small volumes of water thus suitable for household use.

b) Faucet-mounted AC filters are small units attached on the end of a standard kitchen table. They are convenient to use, but because of their size require frequent change. Some units have bypass valves, so that just water for cooking and drinking is filtered.

c) High-volume AC filters contain much more AC than either the pour-through or faucet-mounted models. High-volume units are designed to be installed in-line, generally under the sink. They are installed on the cold water line, and some units are installed with a bypass to separate cooking and drinking water from other uses. Under exceptional circumstances all water may need to be treated by AC filtration. A high-volume unit may be installed at the point of entry to the house if all water needs to be treated.

Ultraviolet (UV) Light

The use of ultraviolet light is an attempt to imitate nature. Sunlight destroys some bacteria in the natural purification of water. Exposing water to ultraviolet light destroys pathogens. To assure thorough treatment, the water must be free of turbidity and color. Otherwise some bacteria will be protected from the germ-killing ultraviolet rays. Since ultraviolet light adds nothing to the water, there is little possibility of its creating taste or odor problems. On the other hand, ultraviolet light treatment has no residual effect. Further, it must be closely checked to assure that sufficient ultraviolet energy is reaching the point of application at all times.

Most ultraviolet purification systems are combined with various forms of filtration, as UV light is only capable of killing microorganisms such as bacteria, viruses, molds, algae, yeast, and oocysts like cryptosporidium and giardia

Advantage of Ultraviolet filter system• It does not introduce any chemicals to the water• It produces no bi-products• It does not alter the taste, pH, or other properties of the water• It produces safe drinking water• It is easy and cost-effective to install and maintain without any special training.

Disadvantages of ultraviolet light: • May have llow penetration power,• It is shielded by turbidity • A slime layer develops on tube thus gradually loses power

Water Distillation (Water Distillers)

Water distillation involves heating the water to boiling point and condensing the steam. This technology removes most of water pollutants including those with a boiling point near that of water. The major drawback to this method is that it requires a large amount of energy. Some people will also complain that the distilled water tastes flat (this is due to less dissolved oxygen).

How Distillers Works

The distillation process removes almost all impurities from water. Distillers are commonly used for removing nitrate, bacteria, sodium, hardness, dissolved solids, most organic compounds, heavy metals, and radio nucleides from water. It removes about 99.5 percent of the impurities from the original water.

Distillers use heat to boil water into steam which is condensed back into water and collected in a purer form. When water boils, it leaves impurities behind in the boiling chamber. The rising steam passes into a cooling section and condenses back into a liquid. The condensed liquid (water) then flows into a storage container as shown alongside. The water left behind in the boiling chamber is discarded and the process is started over.

Distilled water has a bland taste, because the dissolved minerals that give water a pleasing taste have been removed. The distilled water should be stored and covered in a container to prevent contamination.

Household distillers are designed for providing water for drinking and cooking and locally available boiling containers can be used. It is not economical to distill water for other uses like flushing toilets, bathing, washing clothes, and cleaning.

A simple distiller is shown below.

Advantages of distillers

Distillers remove almost all of the impurities found in water, produce sodium free water, and are relatively easy to maintain. Most distillers are mechanically simple.


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme Disadvantages of distillers

Distillers have small capacities and use considerable energy to process water. Because of the small capacities, distillers are limited to point-of-use systems. Distillers without gas vents, fractional columns, or ACF units will not remove volatile organic contaminants, certain pesticides and volatile solvents. Heat generated by a distiller must be dissipated into the surrounding environment.

Although bacteria are removed by distillation, they may recolonize on the cooling coils during inactive periods.

Reverse Osmosis

In water filter terms, reverse osmosis (or hyper-filtration) is the process of filtering water under pressure through a semi-permeable membrane, allowing water to pass through but rejecting other particles such as bacteria, toxins, salts, and anything bigger than around 150 Daltons.

Effectiveness of RO units depends on initial levels of contamination and water pressure. RO treatment may be used to reduce the levels of:

• Naturally occurring substances that cause water supplies to be unhealthy or unappealing (foul tastes, smells or colors).

• Substances that have contaminated the water supply resulting in possible adverse health effects or decreased desirability.

The systems are typically used to reduce the levels of total dissolved solids and suspended matter. They are normally used to treat only drinking and cooking water supplies so may not be preferred where larger supplies are being treated

How Reverse Osmosis Works

Reverse osmosis is sometimes referred to as ultra filtration because it involves the movement of water through a membrane. The membrane has microscopic openings that allow water molecules, but not larger compounds, to pass through. Some membranes also have an electrical charge that helps in rejecting some chemicals at the membrane surface. Proper maintenance is essential to retain effectiveness over time. Some units are equipped with automatic membrane flushing systems to clean the membrane.

Cross-Section of a Reverse Osmosis Unit

Disadvantages of reverse osmosis method

RO units use a lot of water. They recover only 5 to 15 percent of the water entering the system. The remainder is discharged as waste water. Because waste water carries with it the rejected contaminants, methods to re-cover this water are not practical for household systems. Waste water is typically connected to the kitchen gardens. Therefore this method is unsuitable for ASAL regions where water is scarce. They require regular maintenance and monitoring to perform satisfactorily over an extended period of time

Advantages of reverse osmosis method

Figure 2. A Typical Home RO System Includes: (1) particle filter, (2) reverse osmosis membrane unit, (3) pressurized treated-water storage container, (4) carbon adsorption post-filter, and (5) separate treated-water tap.

The water supply entering the RO unit should be bacteriologically safe. RO units will remove virtually all microorganisms but they are not recommended for that use because of the possibility of contamination through pinhole leaks or deterioration due to bacterial growth. Water softeners are commonly used in Minnesota and the Dakotas in advance of the RO system.

1. Prefilter: The prefilter is sometimes referred to as a sediment filter. It removes small suspended particles to extend the life of the membrane. Some membrane units are damaged by chlorine and others by bacterial growth. Where chlorine is present, a carbon prefilter may also be recommended.

2. RO Membrane: Several kinds of reverse osmosis membranes are available. The most common materials are cellulose acetate or polyamide resins. Mixtures or variations of these materials are also used. Each product has certain advantages and limitations and these need to be considered carefully.

Some of the factors that should be investigated are:

• The contaminant(s) involved and their initial concentration(s). • The water supply rate, or whether the system will deliver enough water to meet normal daily drinking and

cooking requirements. • The rejection rate, or the percentage of contaminants to be removed by the membrane. • The water pressure required to meet the supply and rejection rates. That is, can this unit be operated on the

normal operating pressure of a home water system or will a booster pump be required? • How can the system's performance be monitored? That is, how can leaks or other problems be detected or how is

the time for servicing or replacement determined? Some systems have built-in monitors, but many do not. Conductivity meters, pressure gauges and other devices can be used to detect problems where monitors are not included. Where coliform bacteria or other special contaminants are a known or suspected problem, periodic testing is recommended.

3. Storage Tank: Most RO units supply treated water at very low rates so a storage tank of 2 to 5 gallons is used to provide a suitable supply. These units are pressurized to produce an adequate flow when the tap is open. Under sink storage requires minimum pressure to deliver water. Other locations may require increased delivery pressure which may reduce membrane performance.

4. Post-Filter: The main reason for postfiltration is to remove any undesirable taste and any residual organics from the treated water. Usually a carbon filter is used for this purpose. Where a carbon filter is used as a part of the prefiltration step, postfiltration is normally eliminated.

5. Delivery Tap: A separate delivery tap for the treated water is used so that both treated and untreated water are available.


GoK/UNICEF Programme of Cooperation 2008 – 2013 GoK UNICEF Kenya WASH Programme 6. Other: No special controls are required on most systems since they operate by the use of pressure-sensitive switches, check valves, or flexible bladders. Shut-off valves are important to conserve water during low use periods. Monitoring gauges or servicing lights are becoming increasingly common and assist greatly in knowing whether the system is or isn't working.

What does an RO System cost?

When deciding on a water treatment system be sure to investigate all options and all costs. To compare purchase to lease or rent options consider the following:

1. Initial Costs of the System: Be sure that all parts are included, especially when comparisons are being made. RO units range in cost from $300 to $3000 and vary in quality and effectiveness. Replacement membranes cost $100 to $200 and filter cartridges around $50.

2. Installation Costs: These costs are generally the responsibility of the purchaser, but who pays installation fees when renting or leasing? Is there enough space to accommodate the system being considered or will some modifications of space be needed?

3. Operating and Maintenance Costs: Electricity to pump the water is the only significant operating cost. Filter cleaning and/or replacement (both pre and post-filters) and RO membrane replacement need to be estimated. Whether routine maintenance can be done by the owner or requires special service is important information when purchasing a system. When renting or leasing, how and when servicing is to be done and who pays for the supplies and service needs to be clearly stated. For example, is the service done on a schedule or an "as needed" basis?

Summary

Reverse osmosis is a proven technology that has been used successfully in countries like India on a commercial basis to remove salts from salty water from lakes or seas. The removal effectiveness depends on the contaminant and its concentration, the membrane selected, the water pressure and proper installation

14. Capacity Building

As a prerequisite for the success of implementation of water supply facilities, community awareness plays an integral part of enhancing projects ownership and responsibilities. Cultural belief related to water resources and water catchment need to be addressed early enough in project cycle. Effective approaches to change the negative cultural behaviours need to be established in a participatory manner. Continuous back up is necessary in sustaining knowledge and practice proper operation and maintenance of water facilities.

Community participation is a prerequisite for the success and sustainability of community water and sanitation projects. Benefiting communities should be adequately involved in the entire water and sanitation projects cycle including community needs assessment, selection of appropriate technological options, financial and in kind contribution, construction monitoring, operation and maintenance and, monitoring and evaluation of water and sanitation facilities. Gender equality should be supported by involving women in decision-making related to water supply and sanitation projects to ensure that the technological options selected are sensitive to the needs of women and children who are mainly involved in fetching of water

REFERENCES

1. The Water Act 2002.2. Draft Water Sector Investment Plan.3. Design Manual for Water Supply in Kenya, 2005. 4. National Water Policy.5. The National Water Master Plan 1992 and the aftercare study of 1998. 6. Strategy papers on Water Resources Management and Water Services.7. Draft Water Sector Investment Plan.8. Rural Water Resource Development and management Project, July 2002.9. Erik Nissen – Petersen DANIDA 2007.Water from Roofs; A hand book of technicians and builders on survey,

design and construction and maintenance of roof catchments10. IETC 1998. Source book of alternative Technologies for Fresh water Augmentation in Africa11. Ministry of Education (2007), Kenya Education Support Programme, School Infrastructure Technical Hand book

Ver 112. Water Aid, Technology Notes13. Kazi Mohammed (Phd) et al 25th WEDC Conference Addis Ababa 1999; Integrated Development of Water and

Sanitation for Flood Prone Areas 14. Ground Water Development, Participant manual, 1985, Economic Development Institute



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