Stormwater Mitigation
The proposed quarry and residential development incorporate multiple structures and roadways, increasing impervious surfaces on the site. As a result, stormwater runoff will also increase, requiring stormwater management. To address this, three retention ponds were designed in the quarry, totaling over four acres. Each pond maintains a permanent water depth of five feet at its center, with a gradual upward slope toward the edges to provide additional temporary runoff storage. Each retention pond will also serve as an aesthetic water feature, with a large decorative fountain in the center.
The racetrack includes several low points where runoff naturally collects during storm events. To efficiently manage this runoff, stormwater inlets and drainage pipes were strategically placed to convey excess water directly to the retention ponds. The minimum required pipe diameter for each drainage system was determined using Manning’s equation, based on the contributing drainage area for each inlet. Each pond is equipped with a 12-inch standpipe, set at an elevation of 47 feet, to maintain the permanent water level at five feet. Excess runoff is directed into the standpipe, which connects to a 12-inch reinforced concrete pipe (RCP) that transports stormwater to a central pumping station within the quarry. This station collects runoff from all three ponds and transfers it to the existing pump house at the southernmost point of the property, where it is ultimately relocated to a natural waterway.
In addition to the quarry ponds, three retention ponds were designed to manage stormwater runoff from the adjacent residential neighborhood. These ponds collectively cover 0.75 acres and feature a maximum depth of six feet. They share the same outer slope design as the quarry ponds but are equipped with smaller, 3-horsepower fountains, each with a spray radius of 30 feet and a spray height between 15 and 30 feet.