Stormwater Project: What is Green Infrastructure for Stormwater:
Green infrastructure for stormwater or low impact development (LID) refers to practices that manage stormwater in an urbanized setting in a way that minimizes impact to the environment, while increasing cost effectiveness and sustainability. Under this approach, best management practices such as bio-retention, green roofs, rainwater harvesting, and permeable pavements, are incorporated into new or existing infrastructure. These help reduce the volume and pollutant load carried by surface storm water runoff into rivers and lakes.
Background and Rationale
Nonpoint Source (NPS) stormwater runoff is the leading cause of water quality impairment in the United States (USEPA, 2005). Recent rapid urbanization and population growth have exacerbated this problem. Traditional urban development increases the imperviousness of land. This in turn results in increased total runoff volume, increased peak runoff flow, decreased time to concentration, and deteriorated water quality (Dietz et al., 2007). Urban runoff contaminants typically include sediments, oil, grease, pesticides and nutrients from yards, roads, and parking lots. In the Upper Trinity River watershed, legacy pollutants (chemicals no longer in active use) including chlordane and PCBs continue to find their way into the river and reservoirs as part of the sediment load, where they continue to accumulate in fish tissue and contribute to public health concerns.
While recent studies have evaluated the effectiveness of LID practices in various regions in the United States, there is still a great need to evaluate these practices in the field and to collect quantitative data on the performance of LID practices, especially in the Southern part of the United States. There is also very little data on the potential impact of the adoption of LID practices at a watershed level.
The goal of this project is to improve the quality and reduce the total and peak flows of stormwater from a site typical of commercial development in the Upper Trinity and White Rock Lake watersheds. The project aims to design, construct and evaluate several LID practices at the Texas AgriLife Research and Extension Center in Dallas. These Best Management Practices (BMPs) will provide examples of how LID can be integrated in new buildings and developments or retrofitted to existing developments that aim at reducing sediments (and sediment bound pesticides), and nutrients loadings into urban runoff. The five LID BMPs targeted in this study are permeable pavements, bio-retention area, rainwater harvesting, green roofs, and detention ponds. These technologies will be assessed for their ability to treat the legacy pollutant chlordane that is a concern in the White Rock and Upper Trinity River watersheds. Nitrogen, phosphorus, chlordane and total suspended solids will be analyzed. In the case of the green roofs, rainwater harvesting and permeable pavement, a controlled experimental setup will be constructed to collect performance data. These three BMPs will also be installed on larger areas on the USC campus the total load of pollutants removed from these areas will be estimated using the performance results of the experimental setup.
Funding for the project is provided by the CWA 319 (h) NPS grant programs Prepared in cooperation with the Texas Commission on Environmental Quality (TCEQ) and the U.S. Environmental Protection Agency (USEPA) with match provided by Texas AgriLife Research. Data collected as a result of the project will be used to demonstrate the effectiveness of construction of the LID BMPs, in terms of reduction of pollutant loads mentioned above. This demonstration will be further used to promote knowledge, awareness and implementation of the demonstrated BMPs among individuals, businesses and government entities.