provided for areas currently served with piped water and those with the potential of being served with piped water soon, as identified. The following trunk sewers have been identified in the project area using the natural drainage patterns; i. Mugutha River Trunk Sewer: This sewer follows the Mugutha River and will drain parts of Mugutha and Theta sub-locations in Ruiru. This sewer will empty in to the Theta River Trunk Sewer. ii. Theta River Trunk Sewer: This follows the Theta River and is proposed to drain parts of Theta sub-location in Ruiru and Milimani sub-location in Juja as well as flows conveyed by the Mugutha River Trunk Sewer. This sewer will empty into the Thiririka River Trunk Sewer. Figure 1 Mugutha, Thiririka and Interceptor Trunk sewers iii. Thiririka River Trunk Sewer: This will follow the Thiririka River and will serve Milimani and Kalimoni sub-location. It will empty to the Interceptor Trunk Sewer and eventually to the Treatment plant. iv. Kamuguti River Trunk Sewer: This sewer will follow the Kamuguti stream and empty into the Komu River Trunk Sewer. The sewer will serve Witeithie sub- location. vii. Komu River Trunk Sewer: This will follow the Komu River draining the Karimenu (Ngoingwa), Komu, Weteithie, Kianjau and Komo sub-locations of Thika. It will eventually empty into the Treatment Plant at Thika. Figure 2 Komo and Kamuguti Trunk Provision of a sewerage system will require the construction of a reticulation system to serve areas that are either already developed or are in the process of development. The secondary sewers have been proposed as collectors for the laterals and are planned such that they discharge the flows at appropriate points to the proposed trunk sewers. Tertiary sewers have been located on the residential/estates road network so as to facilitate ease of property connection. 2.3 ALTERNATIVE SITES FOR SEWAGE TREATMENT WORKS An initial consideration in the selection of a site for sewage treatment is whether treatment should be carried out at one central location or whether a number of different sites would be more appropriate. Factors affecting this consideration include; Pattern and rate of development Shape and size of the catchment area Topography of the area
in hot climates Generally sub-divided into anaerobic ponds, facultative ponds and maturation ponds requirements No mechanical installations Very simple method of treatment particularly from the anaerobic ponds Sensitive to temperature variations Constructed wetlands Are an artificia created for Used in conjunction with waste stabilisation systems for refining the quality of effluent Have substantial capacity for wastewater treatment High land requirement Requires relatively flat or gentle slopes Requires specific aquatic plants Appropriate for small institutions Aerated lagoons A more intensive system of treatment resulting in greater removal of organics per unit volume of treated wastewater than in WSPs. Oxygen is supplied to wastewater by aerators floating or fixed in the lagoons. Detention time less than in stabilization ponds Less land requirement as compared to WSP High O&M requirements Oxidation ditches An extended aeration plant best suited to small communities. The aeration tank is in the form of a long continuous channel, oval in plan and with rotor suspended over the channel for aeration, mixed liquor propulsion and prevention of suspended particles from settling out. Relatively low land requirement and suitable where land is at a premium price. High O&M requirements Not effective in removing Faecal Coli Form. Percolating/Trickling filters Sewage is evenly distributed on the surface and effluent collected through under drains that also help in aeration. The units are preceded by settling tanks to collect the settle able organic solids delivered from the filters. Durability in all weather conditions and in the presence of corrosive effluents Does not upset for variation of hydraulic or organic loading Limitation in volumetric loading Significant loss of head Nuisance due to flies Medium O&M cost Activated sludge process Involves aeration of settled sewage mixed with return sludge within an aeration tank during which time the micro-organisms in the sewage multiply through assimilation of the organics in the influent wastewater. Any degree of treatment is possible Final effluent is clear and odourless Low land requirement Freedom from odour nuisance Sensitive to organic loading particularly for industrial wastes which result in bulking of sludge High O&M
The project shall enforce all measures to ensure conservation of biological resources both in situ and ex situ to ensure species threatened with extinction are protected. General Maintenance Maintenance programme, including preventive maintenance where appropriate, shall be established at the proposed irrigation and domestic water supply project to maintain facilities in a condition that does not impair the safety, regularity or efficiency of workers or vehicles at the proposed irrigation and domestic water supply project. Section 78 – Air quality The proponent shall enforce air quality standards and be maintained as per NEMA’s Standard and Enforcement Review Committee requirements. Section 87 – Handling and Disposal of Wastes The proponent shall adhere to the disposal of wastes requirement in such a manner as not to cause pollution to the environment or ill health. Section 102 – Excess Noise Noise during operation of the project especially from the water pumps is prohibited and shall be maintained to the desirable levels as is also pointed out in Cap 394. 5.2.2 The Environmental Impact Assessment and Audit Regulations 2003(Legal Notice No. 101) Regulation 24 – EIA licence: - Environmental Impact License shall be issued after the authority approves the study report under regulations 23, and shall be issued in form and accompanied by the prescribed fee of 0.1% of the total cost of the project. Regulation 28 – false or incorrect information: -Substantial change or modification and when project poses an environmental threat or revelation that information or data given by the license were false, incorrect or intended to mislead. Regulation 24 – Annual Environmental Audit:- Annual environmental auditing after presentation of an EIA study report shall be undertaken by the licensee to ensure the implementation of environmental management plan is audited on regular basis, an audit report submitted to NEMA annually and ensuring that the criteria to audit is based on environmental management plan developed during the EIA process or after the initial audit. Regulation 40 - Monitoring changes after project implementation
15. Displacement of people Avoid displacement as much as possible. Prompt and fair compensation of all the PAPs in full prior to beginning of construction works at the site.. Pre and post resettlement counseling‘s support. Financial education for the recipients of compensation funds. Identification and full resettlement assistance for vulnerable PAPs. Contractor and Project Manager Throughout construction phase Operational phase ESMP POTENTIAL IMPACT MITIGATION MEASURES TIME FRAME COST ESTIMATE Water and soil pollution from leaks and sewage overflow and leaks Consider the installation of Separate sewer systems for domestic wastewater and storm water runoff in the overall planning and design of new sewerage systems; When on-site sanitation systems where excreta are mixed with water predominate, consider use of small-diameter sewerage system to collect water effluent from septic systems or interceptor tanks; Limit the sewer depth where possible (e.g., by avoiding routes under streets with heavy traffic). For shallower sewers, small inspection chambers can be used in lieu of manholes; Use appropriate locally available materials for sewer construction. Spun concrete pipes can be appropriate in some circumstances but and Throughout the operation phase O&M Budget