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The Zula Plains Irrigation Project’s primary source of water is the Haddas River, which is joined by several upstream tributaries and captured by the Foro Dam. The dam was constructed in 1960 with a storage capacity of 34 million cubic meters. Water is released as required through two outlet works that supply approximately 15 cubic meters per second each to two main canals, one on each bank of the river, conveying irrigation water to the Zula Plains. At the onset, it was recognized that due to high sediment loads, the dam would be short-lived such that the engineers estimated a design life between 15 to 25 years.

By the 1990s, the reservoir storage capacity was essentially zero as it was full of sediment nearly to the crest level of the spillway. The spill from the reservoir is causing serious downstream erosion problems, jeopardizing the delivery canals. Farmers have attempted to combat the problem by constructing earthen embankments above the spillway in an effort to reduce the frequency of spills. However, the embankments raised the water surface level in the reservoir, contributing to further damage of the dam crest and increasing the threat of flooding to the village of Foro. As a consequence, planned physical developments within the Zula Irrigation Project have never been fully implemented. Controlling water within the current system requires considerable labor and animal power to irrigate a maximum of 1,500 hectares of the 6,000 hectares of arable land.

In conjunction with the Ministry of Agriculture and the local community, NRCE undertook the pre-design and design for rehabilitation and improvements to the physical works of the Zula Irrigation Project that included the Haddas River banks, Foro Dam and its outlet works, conveyance systems, and flow diversion structures. The objectives were to mitigate the sedimentation and erosion problems, provide better water control to the farm community, and to increase the water supply to the Zula Plains so that agricultural productivity could be maximized. Employing a combination of reinforced concrete, masonry, and gabion construction techniques, NRCE’s designs were portrayed on a full set of construction drawings that depicted the following:

• A cost-effective solution to the erosion problem downstream of the spillway that consisted of riverbank and embankment protection;
• Modifications to the existing dam, outlet works, and drop chutes to replace the existing outlet system, thereby increasing diversion capacity without significantly disturbing the upstream sediment;
• Rehabilitation and realignment of the main conveyance systems, utilizing both reinforced concrete and earthen canal sections; and
• Plans for major diversion boxes and drop structures within the irrigation system, including the layout of the conveyance system with the required canal geometries to deliver the design discharge.

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.

NRCE was contracted by the Libyan Arab African Investment Company (LAAICO) to conduct detailed investigations of the Zula Plain, a.k.a. Ghedem, area for the purposes of agricultural development. The ultimate goal was to develop an approximately 5,000 hectare (ha) modern agricultural project. The Zula Plain is situated in the Red Sea coastal area of Eritrea, about 45 km to the southeast of the city of Massawa. Previous studies identified the area as one of promising agricultural development (NRCE, 1996) due to the warm climate and suitable soils. Water supply concerns, however, had the potential to be a limiting factor for any developments along the semi-arid eastern slope of Eritrea.

The objective of the studies was to provide a comprehensive evaluation of the potential development. The Ghedem Agricultural Project’s primary objective is to further develop semi-detailed conceptual plans for the proposed irrigation development project evaluating all potential aspects, including water supply, crop and livestock production, and economic and financial issues. A wide variety of analyses and field investigations were performed.

The study was composed of two phases: Reconnaissance-level investigations and a subsequent semi-detailed conceptual design phase. The objectives of these investigations included:

• Characterize local climate, review suitable crops, and propose cropping patterns;
• Determine crop and irrigation water requirements, including leaching, peak delivery, and diversion requirements;
• Prepare conceptual designs and cost estimates for the proposed sprinkler irrigation systems;
• Summarize potential livestock operations, including forage requirements, suitable breeds, potential disease problems, and herd protection requirements;
• Characterize the regional and local surface water resources available for the project and evaluate potential collection, storage, and delivery schemes. In support of this analysis, a surface water hydrologic modeling study water performed;
• Investigate and describe existing groundwater resources via analysis of existing data, ground geophysical investigations, well drilling, aquifer testing, and water chemistry analyses;
• Conduct soils investigations, including field studies and laboratory analyses, to allow the classification and soil mapping of the entire 10,000 ha study area;
• Develop conceptual designs and cost estimates for the development of surface and ground water resources, including a diversion dam, supply canal, an off-channel reservoir formed by a 52m tall rockfill dam, a groundwater well field, and water transmission pipelines;
• Review and discuss potential project impacts and remediation strategies; and
• Examine the project economic feasibility.

NRCE was contracted by the Government of Eritrea (GOE) to design a dam, pumping plant and pipeline to augment the municipal water supply of the city of Asmara. The designed facilities comprised a 63-meter high dam and a pumping plant and pipeline to deliver approximately 7 million cubic meters of water per year. NRCE, as prime contractor, directed some of the efforts to Woodward-Clyde Consultants and Black & Veatch. NRCE was responsible for topographic mapping, hydrological characterization, water quality appraisal, surveying, geotechnical support, design estimates, and construction document preparation.

NRCE performed critical preliminary design tasks which facilitated the design of the structures. Tasks included: hydrologic modeling of the Toker Basin and sediment sampling (performed during the rainy season of 1995); estimation of sediment yield and distribution in the reservoir; water quality modeling of the proposed reservoir; and reservoir sizing analyses to determine the dam height and incremental cost of delivered water.

NRCE also assisted the government by preparing construction bid documents, coordinating the international competitive bidding (ICB) process, and securing funding from international funding agencies. NRCE was responsible for coordinating the Government of Eritrea and the International Contractor on this project. NRCE also provided support to the Government in meeting the requirements of the funding agency in regards to negotiating the loan agreements. Once funding was secure, NRCE provided construction management and oversight services for the project.

NRCE performed a study to assess the feasibility of the rehabilitation and expansion of the Aligidir Irrigation Project, a large cotton plantation in the western lowlands of Eritrea that is irrigated by water from the Gash River. The 12,000 hectare Project, originally developed in 1927, suffered from nearly three decades of neglect and damage during the Eritrean war of independence. The project also suffered from unreliable flows in the Gash River and very high sediment loads.

The Government of Eritrea (GOE) viewed the project as strategically important for economic recovery of the western lowlands, where many of the country’s refugees were to be resettled. For each of these alternatives, a feasibility-level design, cost estimate and operations study, and anticipated crop production were developed. In addition, NRCE directed a National sector review for cotton, and advised the GOE on matters involving the general management and privatization of the project.

As the prime contractor, NRCE directed the efforts of international sub-consultants on a land resources study, mapping, and health and environmental implications. NRCE directly undertook the hydrological analysis, assessment of groundwater resources, hydrological and sediment data collection, field survey and inventory of existing system, financial and economic analysis, and feasibility level design. In addition, NRCE completed the feasibility level design of a number of alternatives. The feasibility report, which was completed in December 1994, presented three alternatives for rehabilitation and expansion of the project.

For the feasibility study, NRCE inventoried and evaluated the entire existing physical system and developed a cost estimate for rehabilitating canal structures. In addition, NRCE assessed the feasibility of expanding the irrigation project using a new diversion facility combined with sediment traps and off-stream storage. To determine the feasibility of the proposed expansion, NRCE studied surface and groundwater resources, sedimentation, and water demand. As part of this program, sediment sampling and river-stage recording programs were implemented.

Topographic surveys were performed to locate the project facilities. Results from the hydrologic analyses and sedimentation study were used to perform an operation study. The result of the operation study was used in the feasibility level design of new canals, sediment traps, and off-stream storage. Canal enlargement and extensions were included in the design and cost estimate.

NRCE also performed an environmental reconnaissance study of the area. Various aspects of this assessment included potential impacts on human health, archeology, wildlife, and hydrology. NRCE prepared an economic and financial analysis, which resulted in a detailed construction cost estimate, farm budgets, and financial cash flow analysis. An implementation program was also formulated and presented to the GOE.

Preliminary Design

The design of the preferred alternative, which will expand the project to fully irrigate 12,500 hectares of land, was initiated in 1996 with the pre-design of the entire project, and the detailed design for the existing project area and area for expansion (minor works). The preliminary design activities undertaken for the major works included:

• Aerial photography and detailed mapping of the project area; necessary surveying and ground control for the contour mapping.
• Preliminary design of the new diversion weir; headworks, sediment removal facilities, supply canal, off-stream storage reservoir, and main canal.
• Dimension analysis and simulation of the river, diversion weir, and reservoir; dimensional hydrodynamic analysis and transport simulation of the sediment trap.
• Flood risk and dam-break analysis for the river and reservoir.
• Geo-technical investigations for the weir, sediment trap, canals, and reservoir site.

The preliminary design of the major works was completed in late 1998. The detailed design of the existing and expanded areas, including all field investigations, simulation of the modified main canal, and detailed design of all main, primary, and secondary canals and structures are also completed.

During the last few years, the GOE has been implementing the project as a result of the work performed by NRCE.

Final Design

Final Design of the Phase I improvements was completed. This work involved the rehabilitation of existing main, primary, and secondary canals and structures downstream of the existing reservoir, the drainage network, and the roads as well as system expansion facilities. The expansion includes extending the main canal and constructing new irrigation and drainage canal systems and roads in the expansion area. The key tasks completed undertaken under final design included:

• Development of rehabilitation specifications
• Design of main canal enlargement and extension
• Design of the expanded irrigation & drainage system
• Layout and design of the primary and secondary canals and structures and of the required drainage system within the expanded area

In total, 205 construction drawings were prepared for the Phase I design of the Aligidir Irrigation Project. These drawings include general layout, standard details, plans and profiles of conveyance systems, roads, and structures. As part of the final design work, tender documents suitable for implementation of the project were developed based on the FIDIC (1992) system with the specific conditions of contract developed from input from various Ministries in Eritrea including the Ministry of Agriculture and the Ministry of Public Works, and from experience on other projects in Eritrea.

NRCE has been working in Africa since the early 90s. We have an office located in Asmara, Eritrea, which is where the majority of our international work has taken place. Our experts have executed projects here in water resources, agricultural engineering, construction management, water collection and treatment systems, surface and groundwater hydrology, and watershed studies.

In response to anticipated increased water demands, combined with the limitations of the existing water system, the Ministry of Public Works of the Government of Eritrea contracted with NRCE to conduct a feasibility study and preliminary design for a water supply project for the city of Keren and its environs (Keren Water Supply Project). In this project, NRCE accomplished the following:

• Provided an analysis of the water and wastewater infrastructure needs of Keren and the organizational requirements to administer the facilities;
• Evaluated alternatives to improve the water and wastewater infrastructure and select the best options to meet the city’s needs;
• Provided a master plan-level program for water and wastewater infrastructure development for Keren for the next 50 years;
• Prepared a feasibility study for the Keren Water Supply Project;
• Prepared a preliminary design of the preferred water supply development alternative to define specific project requirements, project costs, implementation schedule, and phasing options; and
• Prepared a preliminary design report sufficient to secure funding.

In the feasibility study, the water supply, treatment, and distribution requirements for the city and surrounding villages throughout a 50-year planning period were developed. NRCE also developed the feasibility-level design and cost estimation of water supply, treatment and distribution facilities, as well as wastewater collection and treatment facilities.

Upon completion of the feasibility study, an off-stream reservoir site was recommended as the preferred alternative. Using Autodesk’s Land Desktop 2005 software, preliminary designs, and later a final design packet, was created for a diversion dam, supply canal, sediment control facilities, roller-compacted concrete embankment, raw water pipeline, hydropower generation facilities, water treatment plant, and treated water pipeline. Construction cost estimates and analysis of project financial performance were also prepared, along with an environmental impact assessment and mitigation plan.

Numerous CADD figures accompanied the development and success of this project. Here are two example construction figures of the main dam:

Natural Resources Consulting Engineers, Inc. is a water resources consulting engineering firm headquartered in Fort Collins, Colorado with additional offices in Oakland, California, and Asmara, Eritrea. Our staff includes talented engineers, hydrologists, geologists, GIS and CAD experts, and administrative personnel.

Our Fort Collins office is located within walking distance of the historic Old Town area, while our Oakland office is next door to a unique Eritrean cafe. Both offices offer a casual work environment with a strong emphasis on teamwork.

NRCE is not actively hiring at this time, but we are always looking for highly experienced water resource engineers and WASH experts. Applicants are welcome to submit cover letters and resumes electronically to careers@nrce.com.

If you would like to send a hard copy, please mail or deliver resume and cover letter to:

NRCE, Inc.
Attn: Human Resources
131 Lincoln Avenue, Suite 300
Fort Collins, CO 80524
Email: careers@nrce.com

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NRCE, Inc. is committed to providing equal employment opportunities. All qualified applicants and employees will be considered for employment and advancement without regard to sex, race, color, national origin, age, religion, disability, genetic information, sexual orientation, marital status, or any other basis protected by applicable laws. This policy applies to all employment practices and terms and conditions of employment, including but not limited to promotions, transfers, compensation, terminations and training.

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