Kansas City, Missouri
When the 4-acre parking lot at downtown Kansas City’s national headquarters of the Veterans of Foreign Wars required a wholesale renovation, WRS was tasked with creating a design that could reduce the cost of water quality measures while still maintaining compliance with Kansas City’s American Public Works Association-based stormwater runoff requirements. Using a creative combination of pervious concrete and a permeable articulating concrete block system that absorbs and stores up to 1.5 inches of rain over the entire site until it can infiltrate, WRS managed to reduce the impervious area on the parking lot from 97% to 82% — a fivefold increase in pervious area.
The renovation no longer fell under the definition of development according to city regulation and therefore did not require costly additional BMPs.
WRS hydrologic and hydraulic engineers used the Natural Resources Conservation Service’s Curve Number Method to calculate the depth of direct runoff and peak flowrate from the property both pre- and post-development. Water quality protection recommendations were based on the Level of Service Method for BMP selection described in the Mid-America Regional Council/APWA BMP manual. Stormwater runoff recommendations followed administrative policy within the Kansas City Land Development Division. The design site storage plan illustrated the locations of the proposed storage locations and type.