The Use of Temperature as a Proxy for Nutrient Reduction: a Low-Cost Inspection Tool for Stormwater Control Measures

Abstract

New regulations require the implementation of stormwater control measures (SCMs) in towns and cities. Often, the task of inspecting these systems is left up to the owner. However, testing SCMs for water quality performance can be onerous and expensive. In an attempt to reduce these burdens, temperature reduction through a SCM was investigated as a proxy to estimate nutrient removal in the forms of nitrogen and phosphorus. Using a pervious concrete parking lot that was constructed on Villanova University’s campus as a basis for design, two polyvinyl chloride (PVC) columns were constructed to test this concept. One column consisted of a traditional pervious concrete system with an aggregate bed, while the other simulated a sand bed underneath a SCM.In general, this method offers a lower cost alternative to estimate water quality performance of a non-vegetative SCM. This procedure can be coupled with existing low-level monitoring techniques to gain an understanding of how an SCM is functioning post construction. Background Urbanization continues to place stressors on natural hydrologic systems and environments. The increase in impervious areas in urban locations often causes a disruption in the hydraulics of a watershed, leading to a decline in the health of the surrounding ecosystems. In the United States, the conversion of agricultural land to urban and suburban areas is proceeding at an unprecedented rate, with the majority of the population now living in these developed areas (NRC 2008). An estimated 41,000 water bodies are currently impaired across the country because of the urbanization of watersheds (USEPA 2012). Stormwater control measures offer a way to decrease the effect of urbanization on the surrounding watershed through physical and chemical mechanisms. A variety of SCMs have been developed to serve specific or several stormwater control functions. By using these tools as an effective means for stormwater control management, one can protect water quality, enhance water availability, and reduce flooding potential (PADEP 2006). To ensure the continued effectiveness of these control measures, post construction maintenance and inspection must be conducted. These tasks often times become the responsibility of the property owner in which the control measures reside, and may prove to be onerous and expensive. Low-level monitoring plans have been developed in the form of user-friendly visual inspection checklists. Higher level monitoring systems involve soil analysis such as infiltration testing with a greater investment in time and money (Greising