1. Data collection (potential sedimentation of the proposed dam will be checked, availability of construction material, the topography of the dam site, the reservoir permeability and the spillway location).
2. Laboratory tests of the existing water quality data on Athi River Basin Water Resources Development Study for minimum criteria on bacteriological and chemical quality.
3. Field investigations: Identification of the borrow area and assessment of its suitability of in-situ material for dam construction. The soil samples from the dam axis will be subjected to particle size analysis tests, atterburg limits and proctor compaction test to determine the optimum moisture content and maximum dry density for particular capacitive efforts. The borrow pit samples shall be tested for dispersivit.
4. Valuation of the property within the catchment will also be undertaken and ownership of property and land within the reservoir area confirmed.
5. Socio economic survey will be carried out within the project area.
6. Collection of the existing rainfall data from records of the rainfall gauging stations within the catchment and use the data to construct isohyetal map from which the mean annual rainfall of the catchment will be obtained. The rainfall data will also be used to forecast the runoff within the basin for planning purposes.
7. Using the existing river gauging station records to estimate the flood flow for the design of the spillway, inflow for the design of reservoir capacity and outflow for the intake works.
8. Assessment of the existing water facilities (condition, age, of the main components such as intake, pumping station, rising main, storage tanks and the reticulation network).
9. Environment impact assessment and mitigation measures: Assemble, evaluate and present baseline data on the relevant environmental characteristics of the study area, including water shed, site of the dam and reservoir and downstream areas, especially flood plain and biological environment.
10. Preliminary design using the network analysis to determine the adequacy of the existing water distribution system facilities. Using a survey total station, traverse a cross section of the river valley at the location of the proposed dam axis at intervals not exceeding 5m. A longitudinal profile of the river to cover the proposed dam height.
11. Final design: A comprehensive and updated extract of the results from the preliminary design investigations, the final recommendations, the recommended designs, and justifications of any amendment to the preliminary design. Final design drawings which include plans and longitudinal sections of the dam site, embankment, spillway, intake tower, pipelines, treatment works improvements, intake works improvements etc.
12. Tender documents: Cost estimates of the dam, which will include the distribution to the existing supplies.