Investigating the cost-effectiveness of nutrient credit use as an option for stormwater permitting requirements.

PDFTech ReportFHWA/VCTIR 15-R9105218RunoffWater quality managementPhosphorusCost effectivenessFeasibility analysisCase studiesBest practicesDrainage structuresSavingsVirginiaVirginia Center for Transportation Innovation and ResearchNobles, Alicia L.Goldstein, Hillary D.Goodall, Jonathan L.Michael, G.Fitch,Virginia Center for Transportation Innovation and ResearchUnited States. Federal Highway AdministrationVirginia. Dept. of TransportationUS Transportation CollectionThe purpose of this study was to determine the feasibility of the Virginia Department of Transportation (VDOT)participating in water quality trading (WQT) in lieu of constructing onsite structural best management practices (BMPs) toachieve compliance with Virginia water quality standards for stormwater runoff for linear development projects. The objectivesof the study were (1) to assess the potential credit demand for VDOT projects, focusing on the James River watershed as a casestudy; and (2) to compare the costs to VDOT of constructing BMPs and participating in WQT.Data, including a database of existing BMPs, construction plans, and detailed cost estimates, were provided by VDOT.To assess the potential credit demand, details of existing BMPs were reviewed for eligibility to participate in WQT. For the costcomparison, a cost estimate for select linear development projects with BMPs was calculated and then compared to credit costs.Based on 19 years of historical data, VDOT could have used between 1 and 63 pounds of phosphorous credits per yearand a median of 11 pounds of phosphorous credits per year for the James River watershed if current WQT guidelines had been inplace over this period of time. In the hypothetical scenario where VDOT\ue2\u20ac\u2122s participation in the WQT program was allowed in lieuof VDOT\ue2\u20ac\u2122s construction of nine BMPs, VDOT would have realized a cost savings of 5% to 75%, with an average cost savings of51%. These results suggest that participating in WQT at current market rates in lieu of constructing onsite structural BMPs is aneconomically feasible solution for VDOT to manage stormwater quality. It should be noted that market rates for phosphoruscredits may change in the future.VDOT\ue2\u20ac\u2122s Location and Design Division should continue purchasing stormwater credits for those projects that are eligiblefor WQT