A new, integrated water system in the Badulla, Haliela, and Ella areas of Sri Lanka provides safe drinking water for the first time for thousands of local residents. Tetra Tech is providing design, construction management, project financing facilitation, and oversight for the $74-million project, which includes a new dam, new and upgraded water treatment plants, storage tanks, pumping stations, and transmission and distribution pipelines. The Export-Import Bank of the United States (EXIM) approved $65 million in U.S. financing for the project, and Tetra Tech facilitated the loan development and agreement between Sri Lanka Government and EXIM.

“Not only does this transaction stimulate U.S. job creation, but it also contributes directly to the quality of life in Sri Lanka. This project will bring potable water to thousands of those who need it.”

Fred Hochberg, Export-Import Bank Chairman

The water system originates at the new Demodara Dam, located on the Badulu Oya (Badulla River) about 12 kilometers (km) upstream of the city of Badulla. The dam will create a reservoir to store raw water for the system. Tetra Tech’s design included the construction of a concrete dam, which is most suitable for the site conditions. It allows a spillway to be built into the structure so that high floodwater discharges can overtop the dam without destroying it. Tetra Tech also designed the dam to maintain minimum stream flows downstream, to ensure ongoing water for irrigation and aquatic life. This is the first dam that the National Water Supply and Drainage Board is building in almost 40 years. A new pump station constructed downstream of the dam transfers raw water to the next major component of the system: the Demodara Water Treatment Plant.

The new water treatment plant can treat up to 4 million gallons per day using four high-solids packaged treatment units. Treatment includes conventional pre-sedimentation, sedimentation with tube settlers, clarification in adsorption clarifiers, mixed-media filtration, and disinfection. Tetra Tech’s plant design also incorporates a system for treating and recycling backwash waste, along with solids handling and disposal equipment. To comply with EXIM funding requirements, the packaged treatment units, other process equipment, and electrical and instrumentation equipment were all manufactured in the United States. Numerous components from the United States also were used to upgrade existing treatment plants included in the system. The packaged treatment unit was chosen due to the ease of getting equipment shipped to Sri Lanka that meets the project’s functional requirements. The smaller footprint of the package treatment system provides an additional benefit in the mountainous region where suitable land for construction is limited. The package treatment plant was built on 1.5 acres, instead of the 4 to 5 acres typically required for conventional systems commonly built in Sri Lanka.

Storage and distribution facilities in the integrated water system of the treatment plants include eight bolted steel tanks and skid-mounted booster pump stations at multiple remote sites. The pipeline system includes 46 km of transmission, trunk, and rider mains and 111 km of distribution system lines. Selected piping materials are a combination of high-density polyethylene and ductile iron piping, depending upon pipe diameter and pressure requirements.

Approximately 110,000 Sri Lankans will have access to the new, integrated system and can rely on a steady supply of safe drinking water, a direct improvement in quality of life for the entire coverage area.