Design of a Decision Support Tool for Nutrient Credit Exchange Feasibility in Stormwater Regulatory Compliance
Stuart Scheffield (UVA) – Graduate Student
Transportation infrastructure projects require mitigation of water quantity and quality impacts under the Clean Water Act. The traditional approach for accomplishing this mitigation need has been to construct on-site Best Management Practices (BMPs), typically in the form of stormwater detention basins, or increasing through Low Impact Development (LID) tools to collect, store, and treat runoff from roads and bridges. These BMP and LID approaches have the same ultimate goal of onsite reduction of runoff caused by increased impervious surface.
Water Quality Trading (WQT) offers a different approach for mitigating the impacts of transportation infrastructure where the mitigation needs are addressed offsite, potentially miles away, rather than onsite. WQT is just beginning to be explored and has not yet been widely adopted by DOTs. While the concept of markets and trading of pollution credits is not new, it has been primarily applied for atmospheric rather than water pollutants. Recent legislation in Virginia allows VDOT to use WQT as a means for offsetting the impact of transportation infrastructure projects on water quality and quantity. Given this, there are important questions that must be addressed as to the sustainability of WQT compared to onsite treatment options.
Sustainability is often considered as three pillars: economic, environmental, and societal. Current work at UVA is exploring the economic aspects of WQT vs. on-site BMP construction, but there has been insufficient work to understand the environmental and social impacts of WQT. One of the key environmental impacts of WQT, distinguishing it from other pollutant trading applications, is the need to track the location of loadings and load reductions along river networks. Therefore, the goal of this study will be to create a Geographic Information System (GIS)-based approach for locating BMPs and WQT banks both within the context of existing transportation infrastructure but also within the context of key water and environmental resources.
Potential implementation of project outcomes
The GIS-based framework could be implemented in collaboration with the VDOT Information Technology Division (ITD). ITD maintains extensive GIS resources for VDOT including both data and tools that are accessed by the public and across VDOT.
Expected benefits and impacts
The expected benefits of this work are the ability to geolocate and track estimated loadings from transportation infrastructure to water bodies and explicitly track important upstream/downstream relationships along pollutant sources and nutrient credit banks (pollutant reductions). Using such a framework, it will be possible to better understand the net environmental impact of the decision to either use on-site or off-site approaches to mitigate water quality impacts.
June 2015 Report Submitted to VCTIR: