CASE STUDY: Double Tree Ranch Park
FocalPoint Overcomes the Clay Soil Challenges of North Texas
The new park in Highland Village, just north of Dallas, features walking trails, a splash pad, a large pavilion, open areas for recreation and sustainable stormwater management. The focal point of the integrative landscape consists of bioswales to detain, convey, and treat stormwater runoff, while providing an aesthetic and imaginative landscape for the park goers. The unpredictable and frequent storms, combined with clay soils, forced the design team at Schrickel, Rollins I Parkhill, Smith & Cooper to create a solution that would perform under extreme conditions while keeping the long-term maintenance costs low.
One challenge that North Texas presents to designers are the hard pan clay soils, which typically aren’t conducive to infiltration. Rather than install engineered soil within the entire footprint of the bioswale, the design team selected a High Performance Modular Biofiltration System (FocalPoint) to manage stormwater runoff within the swales. This high flow rate biofiltration system solved three critical issues to managing stormwater. First, it filters the first flush of pollutants through the clog proof filter, trapping nutrients and solids, vastly improving downstream stormwater quality. Second, it serves as a low flow restrictor in the bioswale creating surface storage for detention and additional infiltration. Third, it drastically reduced the footprint of each bioswale's filtration system from 3,000 square feet down to just 100 square feet. The remaining area in each bioswale consists of topsoil, mulch and native plants, which provide additional water quality benefits.
Once construction of the park was complete, a final hydraulic conductivity test was performed that demonstrated that the FocalPoint system was infiltrating at 100 in/hr, which exceeded the performance criteria of the specification. Two years later the plant community within the bioswale is fully matured, erosion is none issue, and the system continues to far exceed all expectations. FocalPoint continues to prove its value to the design community and land owners in North Texas.
Landscapes In North Texas are difficult enough to maintain but can be more of a challenge when they manage stormwater runoff. The most common issue is erosion, that can clog engineered soils and stop them from draining properly. The resilience of high flow biofiltration ensures that the entire system performs after construction and if it does become clogged, can be fixed by the simple maintenance of removal and replacement of the mulch layer. To help ensure FocalPoint systems are installed and performing as expected, all FocalPoint installations are guaranteed for 1-year and free maintenance is also provided during that year.