Nashua, NH Environmental Rules: Erosion Control (2026)

Chapter 190 Article XXXI states that erosion and sedimentation controls 'must be implemented to prevent impacts during construction or post-construction or land disturbance activities, and shall be properly installed.' Typical Best Management Practices required by the Planning Board and Public Works include silt fence at down-gradient site perimeters, stabilized construction entrances with rock pads, inlet protection on the public storm drain system, concrete-washout containment, stockpile covers, and prompt stabilization of disturbed areas with seed and mulch. For common drainage areas serving 10 or more disturbed acres at one time, a temporary or permanent sediment basin must be sized to store the runoff from a 2-year, 24-hour storm. Sites disturbing more than 100,000 square feet of contiguous terrain (or more than 50,000 square feet within a protected shoreland under RSA 483-B Comprehensive Shoreland Protection Act) require an Alteration of Terrain (AoT) permit from NHDES under RSA 485-A:17 and Env-Wq 1500. New AoT rules under Env-Wq 1500 took effect on January 19, 2026, and applications submitted on or after that date must use the new forms. Federally, sites disturbing one acre or more (or part of a larger common plan of development totaling one acre or more) need coverage under EPA Region 1's Construction General Permit (CGP), with a Stormwater Pollution Prevention Plan (SWPPP) maintained on site. Construction operators discharging to Nashua's MS4 are also subject to inspection by the city under its MS4 permit obligations.