By Alex Galbreath, AWS Fall Stewardship Intern
AWS is in the process of constructing a bioretention area and installing permeable pavement at its headquarters, the George Washington House. The project is part of the Sustainable Sites Initiative, an interdisciplinary effort by the American Society of Landscape Architects, the Lady Bird Johnson Wildflower Center at The University of Texas at Austin, and the United States Botanic Garden to create voluntary national guidelines and performance benchmarks for sustainable land design, construction and maintenance practices. The aim of the project here at the GW house is to reduce runoff and erosion while capturing rainwater for irrigation purposes.
The Rainstore3 system we are installing is a cistern with 700-gallon water storage capacity. It will collect the stormwater from the rooftop of the GW House.
Bioretention areas, or rain gardens, are shallow depressed landscaping features designed to retain stormwater runoff from rooftops or other impervious surfaces. The surface runoff is directed into the pond, where the water infiltrates into the ground. It acts as a natural filter, removing pollutants such as sediment, trash, etc. In this case a cistern will collect the rainwater, which will hold water for future plant irrigation. The overflow from the cistern can drain into a nearby rain garden where the water can then infiltrate the soil. Both the rain garden and the cistern will be landscaped with native plants, which will hold soil in place and provide habitat for wildlife.
Permeable pavement is the other aspect of the project. Asphalt and concrete are entirely impervious so 100 percent of the water runs off into the river. This water picks up trash, sediment, and whatever else is in its path. By creating permeable pavement, we allow the water to soak into the soil. As a result, runoff and erosion are reduced. The surface is sturdy but still allows the rainwater to penetrate the soil thanks to layers of different sized crushed stone along with special mats to hold them in place. A path with permeable pavement will be installed from the parking lot to the front entrance of the house.
AWS staff has been working hard on the project for several weeks. Many volunteers have also played a large role in the installation. Volunteers dedicated a recent Saturday morning to prepare the area, lay out the mats, and shovel stone. The project is nearing completion and will hopefully be finished before this winter.
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