Preliminary Engineering Report: Dakawa Pump Station

The existing pump station was constructed in 1981 and includes six horizontal centrifugal pumps and motors, a piping system, electric switchgear, and transformers. However, the pump house structure is in poor condition, with severely cracked and damaged walls due to soil settlement. The pump room, which is below-grade, floods periodically from river water leaking into the room, damaging the existing pumps. The pump station delivers an estimated 1.0 to 1.4 m3/sec of water, but this has not been verified due to the lack of flow measurement equipment at the station. The existing 700+/- meter long dirt access road connecting the village of Dakawa to the pump station site is in poor condition and covered with deep potholes. The road traverses a low, flat area that is flooded during the rainy season. The existing site perimeter security fence is also in poor condition. The irrigation supply infrastructure comprises a pump station and a 7.3-km main canal that provides water to six secondary canals. Water for irrigating the Dakawa rice scheme is currently supplied by the Wami River, with a water abstraction permit issued by the Ministry of Water to the cooperative union, UWAWAKUDA, limiting the extraction of water to 432,000,000 liters/day. The Wami River currently has sufficient supply to serve the Dakawa pump station from approximately March to July each year, depending on rainfall within the catchment area. There are four options available for upgrading the pumping system at the Dakawa pump station to meet the flow requirements: Option 1 – Rehabilitate Existing Pumps, Option 2 – Install New Replacement Pumps in Kind, Option 3 – Install New Axial Flow Pumps and Electrical Switchgear, and Option 4 – Construct a New Gravity Canal from the Wami River. The recommended option is to completely replace the existing end suction centrifugal pumps and motors with axial flow pumps with integral submersible motors, installed directly into the intake well, and with new electrical switchgear, electrical transformers, and power cabling (Option 3). This option would entail complete removal of the existing pumps, motors, suction piping and valves, electrical switchgear, and transformers. The new axial flow pumps would be designed to deliver the required flow rate of 1.0 to 1.4 m3/sec, and would be installed directly into the intake well to minimize the risk of flooding. The new electrical switchgear, electrical transformers, and power cabling would be designed to meet the electrical requirements of the new pumps and would be installed to ensure reliable and efficient operation. The construction of the new pump station would involve several stages, including the removal of the existing pumps and equipment, the installation of the new axial flow pumps and electrical switchgear, and the testing and commissioning of the new system. The project would be managed by CDM International Inc., with the assistance of local contractors and consultants. The estimated construction costs for the project would be approximately $1.5 million, with a proposed schedule for completion within 12 months.