In August 2005, the Louisville and Jefferson County Metropolitan Sewer District (MSD) entered into a Consent Decree with the Environmental Protection Agency (EPA) to reduce sanitary and combined sewer overflows. As a result, Louisville MSD identified a list of projects, including the Northern Ditch Interceptor, necessary to reduce overflows, including what were termed the “Big Four” projects. The Northern Ditch Interceptor was one of the “Big Four” projects.
GRW designed 12,050 linear feet of 84-inch reinforced concrete pipe (RCP) interceptor sewer, including 7 cast-in-place junction manhole structures and a 120-inch diameter liner plate tunnel under a state highway. Construction challenges included installing the interceptor near the following utilities: a 60-inch water main; a jet fuel pipeline that runs parallel to and crosses the interceptor sewer at three locations; and a major fiber optic cable installation. In addition, a 120-inch diameter liner plate tunnel was installed to facilitate the installation of the interceptor under the National Turnpike bridge at Northern Ditch.
The Northern Ditch Interceptor now transfers up to 88 MGD of sewage from the Morris Forman Wastewater Treatment Plant (WWTP) collection system to the West County WWTP collection system during wet weather events in order to eliminate the four largest SSOs in the Louisville MSD collection system.
GRW received an Engineering Excellence Grand Award from the American Council of Engineering Companies of Kentucky for our work on this project.