Gracemore Relief Sewer Design

The Water Services Department of the City of Kansas City, Mo., is responsible for collection and treatment of wastewater flows for the city and provides contract conveyance and treatment for several adjoining municipalities in the metropolitan area. The city-owned system contains both separate sanitary sewers and combined sewers transporting stormwater runoff in addition to sanitary wastes.

In November 1995, Burns & McDonnell was contracted by Kansas City to conduct an infiltration and inflow study of the Shoal Creek drainage basin, encompassing more than 450,000 feet of 8- through 54-inch sewer and recommend improvements to reduce wet weather deficiencies. Flow monitoring and physical inspection of the drainage basin, coupled with computer modeling, identified specific line segments that were inadequate to convey wet weather flow and would remain inadequate following cost-effective correction of identified infiltration/inflow sources.

The recommended solution for the Gracemore area included design and phased construction of relief sewers to divert flow from the overloaded line segments and convey them directly to the interceptor on the opposite side of Shoal Creek. Burns & McDonnell was authorized by the city to proceed with design of approximately 4,600 lineal feet of 15- and 24-inch relief sewer as the first phase of implementing the recommended relief measures. This phase includes partial replacement of some existing collector sewer lines in a residential subdivision and installation of the new relief sewer by both open cut and microtunneling methods. Microtunneling construction methods were used for both a multi-track railroad crossing and a Shoal Creek crossing.

• Evaluate topography, utilities and subsurface conditions
• Alignment field trip with staff
• Preliminary drawings and cost estimate
• Microtunneling
• Final design