Adi Nefas Water Treatment Plant and Treated Water Pipeline, Eritrea
Client: Ministry of Land, Water & Environment, Eritrea
Project: Adi Nefas Water Treatment Plant and Treated Water Pipeline, Eritrea
To alleviate the critical water supply shortage and meet the future needs of the City of Asmara (population 500,000), the Government of Eritrea (GOE), on behalf of the City of Asmara, instituted the Asmara Water Supply Program. This program included the development of the Toker River Water Supply Project. Designed by NRCE, the Toker River Dam and reservoir, raw water pipeline, and pumping plant have been constructed. The raw water supply will be delivered to Adi Nefas, north of Asmara. Completion of the project requires a new water treatment plant at Adi Nefas and a pipeline to convey treated water to the existing distribution system in Asmara. On behalf of the GOE, NRCE, acting as Project Manager in conjunction with General Development, Engineering and Construction Company and Black & Veatch, undertook the pre-design and supervision of the bidding, design, and construction of the project.
The pre-design phase addressed a number of unknowns associated with the project, particularly concerning the type of water treatment system to use, the requirements for the connection of the pipeline to the existing distribution system in Asmara, and absence of detailed maps. During this phase, a preliminary layout and specifications were developed. Surveying and mapping tasks were completed, followed by geotechnical investigations and water quality assessments. Treatment system alternatives were evaluated with respect to water source characteristics, availability of technologies, and life cycle costs. Technologies considered include slow sand filter, rapid-sand filter, and membrane type systems. Major components of the selected alternative include pretreatment, filtration, disinfection, high service pumping, washwater recovery, and finished water pipeline.
A design-build bid package format was implemented, following international competitive bidding procedures. The bid package produced by NRCE outlined all the project requirements, specifications, and bidding information. The package was accompanied by a set of drawings equivalent to about 30 percent of the detailed final design.
NRCE directed the bidding and award phases of the project. A pre-qualification process was done to ensure a list of suitable qualified consortia. As part of the tendering process, NRCE provided the pre-qualified consortia with the documents described above, conducted site visits, and coordinated the answers to the consortia questions in the form of addenda to the tender documents. Following the review of tenders and approval from the Project Management Unit, NRCE supervised the award of the contract.
The NRCE team oversaw the design process and ensured that it complied with the specifications and requirements of the project documentation developed in earlier phases. In addition to input from NRCE’s Asmara-based staff, the overview included support from the North America staff, including midterm and comprehensive final design submittal review of the treatment plant and pipeline design. NRCE evaluated all contractor proposed layout alterations and verified that review comments had been incorporated into the project.
During construction, NRCE was responsible for on-site quality control, ensuring that the contractor was implementing the project as specified, both in terms of quality and schedule. Specific tasks involved the review of lab tests, review and approval of shop drawings, review and approval of change orders, contractual issues, and so forth. After the final completion of the project, a handover evaluation will be performed. Site visits will be conducted and a detailed assessment of the project operation will be made based on data collected over the first 6 and 12 months of plant operation.
Upon completion, the conventional high-rate filtration water treatment facility will have a finished water production capacity of 20,000 cubic meters per day. The treated water distribution pipeline will include several connections to the city’s existing distribution system, and will provide a significant increase in the quantity and quality of the drinking water supply.