The Northeast Ohio Regional Sewer District’s (NEORSD) London Road Relief Sewers project is designed to control combined sewer overflows (CSOs) and provide additional conveyance capacity to help alleviate sewer surcharging in the cities of Cleveland and East Cleveland. To comply with the NEORSD’s Consent Decree with the USEPA, the $51.5-million project will reduce the frequency of CSOs to less than 2 events in a typical year and decrease the annual CSO volume from 190 million gallons to less than 5 million gallons by diverting storm flows to the Ivanhoe-Holmes Branch Interceptor.

Working as a subconsultant to Mott MacDonald, Wade Trim was responsible for the hydraulic, near surface structure, and site civil design components. The project features 10,700 linear feet of new 24- to 72-inch-diameter relief sewers installed by tunneling methods, 870 linear feet of new 12- to 72-inch-diameter sewers installed by open-cut methods, 6 hydraulic drop shafts, 8 large diversion structures, junction structures and manholes, and modifications to 6 regulator structures.

The design balances hydraulic performance with construction-based risks. The older, urban project area is congested with active and abandoned underground infrastructure. A targeted Subsurface Utility Engineering (SUE) program was used to better define the horizontal and vertical locations of existing infrastructure. Armed with this knowledge, new project components were located and sized to minimize interferences and improve constructability. Hydraulic design encompassed drop structures, relief sewers, computational fluid dynamics modeling, surge modeling and collection system modeling. The placement of diversion structures, junction structures and manholes was determined based on hydraulic analysis, anticipated construction methods, geotechnical conditions, existing underground utility impacts, and community impacts. Extensive collaboration with existing utility owners was critical for placing proposed hydraulic structures and relief sewers within congested rights-of-way.

Construction is underway with completion anticipated in November 2020.