Center for Watershed Protection. 2019. Constructing Stormwater Retrofits in Maryland: Challenges & Recommendations for Cost Estimation. Prepared for the Chesapeake Bay Trust. Center for Watershed Protection, Ellicott City, MD. 44 pages

Stormwater, retrofit, cost, TMDL

Maryland communities are poised to spend millions on stormwater retrofit implementation to meet stormwater permit and Chesapeake Bay total maximum daily load (TMDL) requirements. The available information on retrofit costs is highly variable and does not reflect the enormous amount of implementation that has occurred over the past five years. Reliable information is needed on the true costs of implementing stormwater retrofits, so that communities can better plan and budget for them and funders can direct their limited funds towards the most cost-effective practices. The goal of this study was to compile and analyze recent data on actual construction costs for stormwater retrofits across the state to develop a white paper that helps to fill the gaps in knowledge on stormwater retrofit costs. The following research questions were identified for this study: • What are the design and construction costs of stormwater retrofits? • How do these costs vary with BMP type, location, site conditions, or design features? • Which BMPs are most cost-effective for nutrient and sediment removal? • How do the final construction costs compare with the initial estimated project costs? • What are some lessons learned and challenges associated with these projects that affected the cost, timeline, and ultimate success of the project?