Thornton Water Project

Challenges

In the 1980s, the City of Thornton (Thornton), Colorado began purchasing water rights in the Water Supply and Storage Company (WSSC) to accommodate anticipated growth. This water is diverted from the Cache la Poudre River through an irrigation canal into reservoirs owned by WSSC. The Thornton Water Project involves construction of a 70-mile-long, 42-inch-diameter pipeline that will convey water from WSSC’s reservoirs to Thornton’s reservoir system. The pipeline crosses multiple roadways, irrigation canals, and streams, requiring over 40 tunnel installations, each with unique design and construction considerations.

Solution

RJH was retained as part of the construction management team to provide specialty engineering services for tunnel and shaft construction. The pipeline was designed and installed in six phases. The tunnels ranged from approximately 100 to 800 feet long, and tunneling methods included a tunnel boring machine, microtunnel boring machine, tunnel shield, guided auger bore, and guided pipe ramming.

During the pre-construction phase, RJH reviewed the quality assurance plan, risk register, and construction schedule for the tunnels and shafts. RJH provided full-time field engineering services to observe and document the construction of the shafts and tunnels and identify compliance with contract documents. Our field engineers have developed construction management plans and quality assurance plans, delivered daily reports documenting project progress and adherence to specifications, responded to requests for information, and assisted with analysis of contractor claims.