West St. Paul Robert Street Stormwater Management

West Saint Paul, Minnesota

SRF completed the preliminary and final design for a 2.5-mile stretch of the Robert Street corridor. Robert Street is a highly urbanized and significant commercial commuter route. Subsurface utilities supporting more than a century of development and expansion congest the underground right-of-way envelope. The Robert Street corridor, like many major roadway systems, provides trunk sewer connectivity for the City of West St. Paul’s drainage system. Approximately 400 acres of regional (off site) drainage area is conveyed through the various Robert Street systems. The reconstruction area is approximately 24 acres.

Preliminary design included a Stormwater Management Plan (SWMP) identifying potential BMP location and types, along with impacts to existing storm sewer infrastructure with the goal of identifying portions of the existing system that could be incorporated into the proposed design. SWMP production required the development of an extensive and detailed XP-SWMM model, which incorporated both existing storm sewer and water quality features. The modeling results aided in identifying boundary conditions for the storm sewer retrofit design and improvements, and the appropriate BMP design and locations.

Along with the approximately 440 new catch basins and 3.9 miles of new storm sewer, the project incorporates bio-swale, pervious pavers, and tree trenches that provide water quality treatment. The bio-swales intercept off site parking lot drainage prior to it entering the roadway, providing treatment and reducing the number of catch basins required to meet spread criteria. Approximately 7900 linear feet of pervious pavers, located between the sidewalk and curb, capture sidewalk runoff, directing it to 151 trees via tree trenches.

Client:

City of West Saint Paul