Empire WWTP Outfall and Rosemount Interceptor

The Rosemount Empire planning area is located in the southeastern part of Minneapolis/St. Paul metro area and includes the cities of Apple Valley, Lakeville, Farmington, Rosemount, and Empire Township. Metropolitan Council Environmental Services (MCES) provides wastewater collection and treatment for this area.

As part of a consultant team, HR Green completed the Rosemount Empire Service Area planning in two phases. Phase I (Master Planning) determined the appropriate number, size, and locations for treatment plants and recommended treated effluent discharge points for the treatment facilities. As a result of this effort, MCES decided to stop discharging to the Vermillion River. In Phase II, HR Green then led the development of a Facility Plan for an effluent outfall pipeline to convey up to 60 mgd of treated effluent to the Mississippi River. Working closely with MCES, numerous regulatory agencies, environmental groups, and landowners, HR Green developed the necessary support for the project.

MCES selected HR Green to complete the design of the outfall pipeline. The project consisted of over four miles of dual 48-inch force main, seven miles of 66-inch to 78-inch gravity line, followed by two vortex drop structures and two miles of outfall pipe to the river. Also included were provisions for allowing stormwater from the City of Rosemount to be discharged into the 78-inch portion of the effluent gravity line for the conveyance to the river and a series of 18- to 24-inch dual force mains and 36- to 48-inch diameter gravity interceptors to convey untreated wastewater from the Rosemount WWTP to the Empire WWTP.