Construction of water projects

Introduction

It is important to obtain the required permits, as described in the data sheet on Surveys, designs and permits for water projects, before starting any construction of water supply systems. Structures built without these legal requirements are illegal and might have to be destroyed without any compensation. In Kenya, the Water Services Boards (WSBs) are forming their policy on construction of small water projects for individuals and community groups. Abstraction of shallow and deep ground water by means of hand-dug wells and boreholes, as well as abstracting water from streams, must be approved by the WSBs and an annual fee paid for the extraction permit.   The Water Resource Management Authority published a document on 25/02/09 entitled "Guidelines for Determination of Permit Classification for Water Storage Structures" which :says: "First, small pans, where the water is held below ground level, do not require a permit provided the capacity is less than 10,000 m3. If the capacity will be greater than this the community, or the farmer should apply to the Regional office of the Water Resource Management Authority (WRMA) for permission to construct."   Also permits from WSB and the National Environmental Management Authority (NEMA) must be obtained before wells, intakes, boreholes, subsurface dams, weirs and sand dams are built in seasonal riverbeds as well as other types of water supply systems. Collection of rainwater from roofs of private buildings does not require any approvals.

Seasonal Work Plan

Financial capacity

Preferably, all the money required for the construction work should be available if the structure is expected to be completed within a short period. Alternatively, the structure can be built in stages according to the availability of funds. 

Evaluating builders' qualifications

One of the best methods to sort out doubtful builders is to ask them technical questions, e.g.:

1. What is the correct mixture and thickness of cement to sand and ballast for concreting the foundation and floor of water tanks?  

• The answer is 15 cm of 1:3:4 followed by a 2 cm coat of 1:3 mortar onto which NIL (cement slurry) is applied the same day for water proofing. 

2. Which type sand should be used for concrete? 

• The answer is coarse textured river sand

3. Which type of sand can be used for final plastering?  

• The answer is fine textured river sand, not sand collected from dirt roads.

4. What happens if cement is mixed with sand and water that is not applied within one hour?  

• The answer is that the strength of cement will be reduced to half.

5. For how long should concrete and plaster work be cured, that is to be keep moist under shade? 

• The answer is 28 days. If cured less, the cement loses its strength. 

6. What does this technical design drawing show?

Employment of builders

Artisans are paid a daily salary for an unknown number of days as agreed verbally between the client and the artisan before the work starts. This is the most popular method of undertaking construction works in rural areas because both the client and the artisan can cancel the agreement any time provided the client pays the artisan for the number of days that he has worked. This type of flexible agreement is excellent where clients can supervise the artisans but is often abused by artisans if they are not supervised on a daily basis. 

A contract with a contractor  on building a hand-dug well

© E. Nissen-Petersen, Kenya

Contractors quote a fixed price for a certain construction work that is described in details either in a survey and design report or verbally by the client. In both cases, the contractor and the client will haggle about the quoted price while discussing whether food, accommodation, transport and unskilled labourers are included.  

While this kind of verbal contract is accepted for small private construction works, it should be formulated and signed in a contract for larger private and community building projects. Such contracts should have clauses on the rates of payments, retention fee, health and accident insurance, tax payments and other financial issues as shown below. 

Although such non-flexible contracts usually increase the cost of the construction works, they require less supervision by the clients and reduce the overall cost of the project. However, in case of disagreements between the client and the contractor that may lead to cancellation of the contract, they have to make a financial settlement which may require one or two impartial persons to arbitrate.

 In negotiations with artisans and contractors it is useful to know the average number of working days it will take to built various types of structures. The following data is based on more than three decades of actual construction works of the types of water projects listed below. As a rule of thumb, a contractor earns a fee being double of an artisan`s salary and an artisan earns a salary being double of an unskilled labourer`s salary. 

Average working days on various types of water projects 

A contract with another contractor on making 200 latrine slabs

© E. Nissen-Petersen, Kenya

Quotations, procurements and delivery of building materials

Quotations and procurements of building materials 

.As mentioned under the entrepreneurial approach, great cost reductions can be achieved on the implementation schedule by paying, to the communities, 50% cash of procurement cost of locally available materials, delivered to the construction sites, while the other 50% is accounted, but not paid, as their contribution. (See data sheet on "Community Management of Water Sources".

Bill of quantities and cost of a 90 cu.m. tank built of ferro-cement 

Be aware that the items measured in tonnes, such as sand and crushed stones (ballast), are difficult to measure without a weighing station and some suppliers are therefore tempted to cheat. Such suppliers can, however, be controlled by converting the volume of sand and ballast into tonnes using the following method: 

1) Measure in metres the length, width and depth of sand in a loaded lorry. Multiply these three figures to get the volume of cubic metres, e.g. length 3.0 m x width 2.0 m x depth 0.5 m = 3 cubic metres load.

2) The handbook "Field Engineering" by F. Longland gives the following data: Dry sand weights on average 2.2 tonnes per cu.m.. Therefore 3 cu.m. sand weights 6.6 tonnes. Crushed granite stones weight 2.7 tonnes per cu.m. Therefore 3 cu.m. stones weights 8.1 tonnes.

Preparation of construction sites

The committee will enter their members' names in a Muster Roll and group them into work gangs according to their ages and capacities as follows:

For further information on community training click here.

Training local builders

Rural builders know how to build small houses of burnt bricks and roofed with corrugated iron sheets but often lack proper training and experience to work with cement, mortar and concrete. For example, in the mornings they may mix all the mortar or concrete they need for several hours without knowing that cement loses up to 50% of its strength one hour after it has been mixed, if it has not been applied. 

 

Also rural builders often do not know that if mortar and concrete works are not cured by keeping them moist under cover for 28 days, the cement will lose even more strength. This neglect of proper handling of cement works does not matter for small rural houses but when this lack of skills is applied to water reservoirs, the results can be observed in the country-wide graveyards of failed water tanks and other structures.

 

Whenever a water programme is being planned for rehabilitation of old water projects or construction of new water projects, it should include a training course for community members identified by the development committee. The training can be implemented for a reasonable cost by using the hands-on methodology of learning-by-doing by which the trainees assist trained builders in the construction works.

 

A training course should deal with the types of water structures having the most potential for the people living in a certain environment. In the driest parts of the world the most potentially useful types of rainwater harvesting projects depend on the catchment areas and not the rainfall because where there is less rain it can be compensated for by larger catchments. The table below prioritizes various types of catchment areas with the most viable structures for harvesting rainwater for domestic and agricultural use.

 

	Catchment areas	Viable structures	Domestic or agricultural
1	Seasonal sandy water courses, dry riverbeds, luggah, wadi and ephemeral streambeds	Wells, shallow boreholes, subsurface dams, weirs and sand dams	Both
2	Roads, tarmac, murram and dirt surfaces	Ponds, earth dams, ground tanks, macro irrigation	Agricultural
3	Rock surfaces above and below ground level	Masonry walls, water tanks and hillside earth dams	Both
4	Roofs, except thatched	Water tanks	Domestic
5	Valleys	Valley earth dams with wells	Both
6	Flat land	Charco earth dams with wells	Both
7	Rolling land	Hillside earth dams with wells	Both
8	Hills	Gravity flow from springs	Domestic

 

 

Training courses 

This section is based on the experience gained from implementing half a dozen training courses on water supply in arid and semi-aid zones of Africa and Asia. 

After some meetings, the consultant presented a project proposal to a client who wanted to assist hundreds of communities with construction of small water projects. The methodology had to be implemented through the Water Services Boards by self-employed engineers trained as consultants and local builders trained as contractors. The engineers and builders had to be identified from the communities concerned.

 

A contract was signed when a detailed training programme and its budget was agreed upon. The training course was announced at relevant government offices and at places visited frequently. While applicants for the training course were preparing their documentation for the interviews, the training venues were identified, and designed with bills of quantities by some of the trainers, who also obtained the required approvals from the relevant authorities. Other trainers obtained Implementation Agreements with the communities living near the selected riverbeds. Implementation Agreements describe the conditions and services to be delivered by the Manager of the implementing agency and the community concerned, such as: 

1) Survey and design report.

2) Legal requirements.

3) Selection of construction site

4) Training of the community.

5) Land Agreement.

6) Registration.

7) Delivery of local labour and materials in return for the ownership of the structures built during the training course.

 8) Training of men and women during the construction period in the construction, operation, maintenance and repair of their water projects. 

 

Training

© E. Nissen-Petersen, Kenya

While the activities listed above were implemented by some of the trainers, other trainers assisted the Manager with interviewing the, often, hundreds of applicants who arrived on the days allocated for interviews. Since some applicants have clever and lengthy ways of explaining lack of, or even false, documentation, the applicants should line up and present their documentation to a team of trainers, who sort out the disqualified applicants. 

Photocopies of the applications' documentation were filed while they responded to technical and personal questions. Every applicant was informed that after short-listing; the selected persons would be informed before a certain date. If they do not receive any information, they were not selected for the training. 

 

Engineers and technicians having diplomas and certificates were called "engineer participants", while the term "builder" covered skilled and unskilled artisans of all trades. For every identified construction site a Survey and Design Report with a Bill of Quantities and estimated construction costs was produced. The engineer participants obtained the required approval and permits from the relevant ministries using these reports. The engineer participants also supervised the builders being trained and communities building the structures and provided Supervision Reports to the Manager.

 

 

 

 A training course on Water from Dry Riverbeds takes usually takes 12 weeks to implement as follows:

 

Weeks	Activities	Actors
1	Training programme, budget, funds and advertise for participants	Manager
2	Contract 12 Assistant Trainers. Survey and Design reports	Manager and the Assistant Trainers
3	Survey and Design reports	Manager and the Assistant Trainers
4	Survey and Design reports. Implementation of agreements with communities
5	Implementation of agreements with communities Obtain required approvals and permits	Manager and the Assistant Trainers
6	Engineer participants start Survey and Design reports	Manager and the Assistant Trainers
7	Builder participants and communities start construction works	Manager, the Assistant Trainers and Engineer participants
8	Survey and construction works continues	Manager, the Assistant Trainers and Engineer participants
9	Survey and construction works continues	Manager, the Assistant Trainers and Engineer participants
10	Survey and construction works continues	Manager, the Assistant Trainers and Engineer participants
11	Survey and construction works are completed. Participants receive certificates and the training course is completed	Manager and the Assistant Trainers
12	Accounts and Final Report	Manager

 

Information Source Links

• Lindquist, A. K. (Ed) (2005). Water from ponds, pans and dams. A manual on planning, design, construction and maintenance. RELMA Technical handbook No.32. Nairobi, Kenya. I SBN 9966-896-67-8
• Longland, F. (1936). Field Engineering: A Handbook on simple construction. Tanganyika Government Printer Dar es Salaam, Tanzania. (Reprinted by ITDG in 1990, under the title "Field Engineering") 
• Nissen-Petersen, E. (2000). Water from Sand Rivers. A manual on site survey, design, construction and maintenance of seven types of water structures in riverbeds. RELMA Technical Handbook No.23. Sida Regional Land Management Unit, Nairobi, Kenya. ISBN 9966-896-53-8
• Nissen-Petersen, E., Madsen, B. and Katui-Katua, M. (2006). Water for Rural Communities. How Kenyan rural communities can create their own water supplies with assistance from the Water Services Trust Fund. Danish International Development Agency (DANIDA)