Capitol Region Watershed District’s new headquarters is located in Saint Paul’s Midway neighborhood, an area where existing residential, commercial, and industrial uses intersect. Previously the site of MacQueen Equipment, the property had environmental contamination from decades of past commercial and industrial uses. To assist with redevelopment of this brownfield site, CRWD hired Barr to investigate the site and develop designs for environmental cleanup and stormwater management. Barr’s objectives were to mitigate soil gas contamination, manage petroleum-impacted soils encountered during construction, and facilitate infiltration of stormwater in an area of residual contamination.
To address vapor intrusion risk, Barr designed a sub-slab mitigation system that bridged new building construction and an adjacent existing building undergoing renovation. Areas of petroleum-impacted soils related to historical underground storage tanks were either capped on site or removed and transported to a landfill. To help with the CRWD’s goal of reusing and infiltrating as much stormwater as possible, Barr conducted an award-winning and MPCA-approved evaluation involving groundwater modeling and monitoring to demonstrate the infiltrated stormwater did not exacerbate residual petroleum impacts in the groundwater.