Broadway-Tekoppel Sewer Project
American Structurepoint designed this gravity interceptor sewer consisting of approximately 6,750 lft of 36-, 42-, and 48-inch sewer pipe to replace existing 12-inch force main and provide future capacity for branch line connections in the area. Approximately 750 lft of 8-inch branch sewers were installed to provide sewer service to existing homes previously on septic systems. Design included diverting flow from three existing sewers, installing two inverted siphon creek crossings, and upgrading an existing lift station to eliminate a CSO.
The 36-inch sewer had to cross the Tekoppel levee to reach the West Side Wastewater Treatment Plant. Tekoppel Avenue is a busy road; therefore, the crossing of the gravity sewer was designed as a trenchless crossing using jack and bore method. The steel casing pipe was sized according the USACE requirements, and the sewer line was grouted in place according to the requirements. A gate well was designed on the river side of the levee to enable the sewer to be closed off in the event of a problem with the pipe. The gate well was constructed with the top of the structure above the 100-year river elevation. Due to the depth required (ranging from 10 to 27 feet) and the vast number of utility conflicts, the sewers were installed using open-cut methods, directional drilling, and micro-tunneling. This project also included wetland delineation and mitigation, USACE permitting to cross the Tekoppel levee, and coordination with IDEM to obtain the necessary construction permits. The siphon pipes were directionally drilled to avoid open cutting the streams resulting in use of the utility exemption in lieu of a 401/404 permit.