Nashua, NH Environmental Rules: Grading & Drainage (2026)

Chapter 190 Article XXVI (Grading and Removal of Soil) prohibits taking loam, clay, sod, sand, or gravel from any land in Nashua without an administrative permit from the Administrative Officer issued after consultation with the City Engineer; the application is processed as an administrative permit under Article XIV. The article exempts areas being excavated for buildings, farm ponds, man-made lakes, land contouring, swimming pools, streets, and driveways from the soil-removal permit. Drainage and stormwater design standards live in Article XXXI (Stormwater Management): water-quality treatment volume of 0.5 inch of runoff multiplied by impervious area (citywide) or 1.0 inch (Water Supply Protection District / Conservation Zone), 80 percent average annual TSS removal for new development, and a 20 percent impervious-area reduction goal for redevelopment. Site-grading work that triggers more than 100,000 contiguous square feet of disturbance (or more than 50,000 square feet in a protected shoreland under RSA 483-B) requires an NHDES Alteration of Terrain (AoT) permit under RSA 485-A:17 and Env-Wq 1500. Building-code drainage rules — primarily IRC R401.3 requiring positive drainage of at least 5 percent for the first 10 feet away from foundations for residential structures — are adopted under RSA 155-A through the New Hampshire State Building Code. Grading inside the FEMA Special Flood Hazard Area also triggers a floodplain development permit under Chapter 190 Article VII. Pennichuck Brook and the city's Water Supply Protection District impose additional design constraints on grading that drains toward Nashua's drinking-water source.