Construction of Deep Tunnel Along Kansas River to Reduce Overflows

Construction began on an underground tunnel and pipeline designed by Black & Veatch to carry by gravity as much as 180 million gpd of treated wastewater from Johnson County Wastewater’s Mill Creek Wastewater Treatment Plant in Shawnee, Kan., to a discharge point downstream of a water intake on the Kansas River.

An average of 10 million gpd of plant effluent is currently pumped to the same discharge location, but the existing pumping station and force main do not have the capacity to pump extreme wet-weather flows. The construction is part of an effort to eliminate the risk of untreated wastewater flows into the river and into nearby Mill Creek during heavy rain periods. When completed in late 2013, the tunnel will also reduce Johnson County’s carbon footprint and operating costs by eliminating the current need for electricity to pump the effluent.

The pumping station and force main will be taken out of service after completion of the project, which includes construction of new plant piping to convey treated wastewater from the plant’s final treatment processes to the tunnel as well as piping within the tunnel. Black & Veatch is also providing construction services for the project.

S.J. Louis Construction of Texas leads construction of the 110- to 180-ft-deep tunnel, in which a 96-in.-diameter fiberglass-reinforced pipe will be grouted into place. Design and construction challenges include tunneling adjacent to the Kansas River through methane-containing shale and the potential for high groundwater inflows in the shaft excavations.

Source: Black & Veatch