The Roxborough Water and Sanitation District (RWSD) Wastewater Regionalization Project involved a large metropolitan sanitary sewer line system installed near the South Platte River that traveled through multiple parks, golf courses and street crossings.
RWSD encountered wastewater treatment challenges with its older facility and decided to partner with Littleton/Englewood Wastewater Treatment Plant (WWTP) – the State’s third largest publicly owned wastewater treatment facility – to provide regionalization of the District’s wastewater treatment.
TST Infrastructure LLC, an Englewoodbased consulting engineering company, designed a 14.2 mile sanitary sewer pipeline that would bring flows from the two systems - Roxborough and one at Lockheed Martin Space Systems Co. - together and transmit them to Littleton/Englewood WWTP. The design included 8.3 miles of forcemain and 5.9 miles of interceptor.
TST Infrastructure designed two lift stations in order to accomplish this. One was constructed on Lockheed Martin property and was designed to receive gravity flows from the domestic wastewater collection system and transfer the wastewater to the second lift station, located on Roxborough’s existing WWTP site. The wastewater would then travel up and over the spillway at Chatfield Reservoir, crossing under State Highway C-470 and run along the South Platte River. Gravity would then keep the flow moving towards a connection with Littleton/Englewood’s interceptor at Santa Fe Blvd and Belleview Ave.
With only a 110-ft. drop over the gravity main’s almost six miles, construction required setting the pipe at a very flat 0.3 percent average grade with minimum slopes as low as 0.09 percent.
“The design and construction of the interceptor portion of the project was critical due to the numerous utility crossings and the minimal vertical drop across the pipeline,” said Chris Manning, Civil Engineer with TST Infrastructure.