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EPA’s Summary Report of the Collaborative Green Infrastructure Pilot Project for the Middle Blue River in Kansas City, MO
Simon, M. EPA’s Summary Report of the Collaborative Green Infrastructure Pilot Project for the Middle Blue River in Kansas City, MO. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-16/085, 2017.
The United States Environmental Protection Agency collaborated with Kansas City and installed pilot green-gray infrastructure to determine whether the installed stormwater control measures (SCMs) reduced water quantity and improved water quality in combined sewer overflows. Kansas City installed 135 vegetated SCMs, 24,290 square feet of porous or permeable pavement, and 292,000 gallons of underground storage space. A key finding from this study was that the installed green gray infrastructure reduced runoff to the sewershed by approximately 30%. Also, concentration reductions were seen in multiple water quality parameters, indicating an improvement in the stormwater runoff water quality. Communities, planners, engineers and regulators interested in installing stormwater control measures could apply these results.
The United States Environmental Protection Agency evaluated the performance of a hybrid green-gray infrastructure pilot project installed into the Marlborough Neighborhood by the Kansas City Water Services Department. Kansas City installed 135 vegetated SCMs, 24,290 square feet of porous or permeable pavement, and 292,000 gallons of underground storage space in the residential neighborhood which drained 54% of the total 100 areas studied. Independently, both the Environmental Protection Agency and Kansas City determined that the green-gray combined infrastructure reduced the sewer flow runoff volume by approximately 30% in the combined sewer when the after test conditions were compared to before test conditions. It was also determined that the average drop in concentrations was 52% +/-34% for total suspended solids, 51% +/-33% suspended solid concentration, 37% +/-22% national turbidity units, and 50% average diameter particle size was 21% +/-59% when the outlet from one bioretention measure was compared to the inlet. There was only one storm in which nitrate and phosphate could be compared. The nitrate concentration was reduced by 52% and phosphate reduced by 57%. All analyzed influent samples were non-detect for lead and zinc (< 50 ug/L). Greater than 50% of the total copper concentrations were in the dissolved form. Fecal coliform concentrations were unexpectedly high, with concentrations often above the upper detection limit of 6 million most probable number 100mL.