Stormwater Retrofit Design

Stormwater retrofits can improve water quality and freshwater habitats by filtering, slowing down, or sinking in runoff from existing rooftops, parking lots, and roads. Retrofits are an important restoration practice since they can remove pollutants, promote healthy hydrology, and reduce erosion. Managing stormwater from impervious surfaces is an important component of clean-up efforts in Lake Champlain, Lake Memphremagog, and in stormwater-impaired waters. Vermont’s Stormwater General Permit 3-9050, for instance, requires municipal, institutional, and private property owners to conduct feasibility assessments for hundreds of properties with three acres or more of existing impervious cover but limited or no modern stormwater treatment. “Three-Acre” sites in the Lake Champlain and Lake Memphremagog watersheds must file initial Notices of Intent to Discharge by January 1, 2023 - and complete design and construction of retrofits to remove pollutants within the next five years.

Stone’s professionals identify, design, and provide construction management support for stormwater retrofits. We understand the requirements and actions property owners need to take to comply with this regulation and help clients obtain all necessary permits. Our planning and design engineering approach evaluates existing conditions, site constraints, and treatment options that emphasize principles of low-impact development and green stormwater infrastructure.