DUFRESNE GROUP | Consulting Engineers

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Stormwater and Erosion Control

Stormwater regulations differ by State. In Vermont, the Stormwater Section under the Department of Environmental Conservation Water Qualify Division of the Agency of Natural Resources manages the stormwater permit program. They have developed two permit processes to regulate development of new impervious area greater than one acre. There are two permits required for such projects including:

The cost of compliance for these permits varies by project size and site but the construction cost can be significant. Our task is to minimize the cost using innovative compliance strategies and engineering common sense. The typical strategy for compliance is to utilize cut offs and swales to maximize treatment to eliminate or reduce stormwater retention pond size. However, for most projects not discharging to a very large river, a retention basin will be required to provide retention and treatment to insure the runoff from the new project will not exceed the pre-project conditions for the ten year storm.

Dufresne Group has planned and designed stormwater systems for many large development projects in Vermont including projects on steep slopes near ski areas and 90 unit development projects with new roads and drives. In several projects, designers were able to design infiltration systems to discharge stormwater into the groundwater to eliminate retention basins.

In New Hampshire, stormwater regulations are managed on both the state and federal level. The State of New Hampshire requires an Alteration of Terrain permit whenever a project will disturb more than 100,000 square feet. The Alteration of Terrain permit regulates erosion and sediment control. New Hampshire does not have a dedicated stormwater division. They have instead chosen to allow the EPA to manage the stormwater permit program. The EPA requires a Construction General Permit if the project will disturb one or more acres. This permit requires a Stormwater Pollution Prevention Plan (SWPPP). A SWPPP is a detailed plan outlining sediment and erosion control practices and stormwater “best management practices” for a specific site. The SWPPP is an operational document that requires ongoing inspections and maintenance as well as record-keeping.

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St. Johnsbury, VT - Airport Hill Tank Stormwater

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