Comparison of WinSLAMM Modeled Results with Monitored Bioinfiltration Data during Kansas City Green Infrastructure Demonstration Project

The US EPA's Green Infrastructure Demonstration project in Kansas City, MO, incorporates small-scale individual biofiltration device monitoring along with large-scale watershed monitoring. The test watershed (40 ha, 100 acres) is saturated with green infrastructure components (including curb-cut biofilters with extra subsurface storage, rain gardens, cascading biofilters, and porous concrete sidewalks). An adjacent 35 ha (87 acre) control watershed is also being monitored for comparison and to track effects of different rains affecting the watershed response. The monitoring results at the small and large scales were used to verify the WinSLAMM stormwater quality model to enable evaluations of specific design options of these stormwater controls and for analyses of green infrastructure alternatives at other areas of the city. WinSLAMM is a unique model in that it evaluates stormwater controls based on unit operation processes and actual design values and incorporates complete hydraulic, particulate, and pollutant routing between and within the stormwater controls in an area. WinSLAMM was used to evaluate the biofilter designs for the test area and was calibrated using the early test and control watershed flow and rainfall data after sewer re-lining in the test watershed, but before the construction of the stormwater controls in the test area. The green infrastructure infiltration and storage elements have now been constructed and the monitoring is continuing. This paper describes the results of the model calibrations, along with the verification of the model reflecting the effects of the stormwater controls during the first season of both small- and large-scale monitoring after their construction. Monitoring and evaluation of the test area is continuing into the 2013 rain season to obtain additional data.