Chelsea, MA Environmental Rules: Grading & Drainage (2026)

Grading and drainage regulation in Suffolk County combines the state building code, local bylaws, and common law. 780 CMR Chapter 18 (Soils and Foundations) and Section 1804 govern site grading, drainage, and retaining structures. Boston Inspectional Services (ISD) requires a building permit for excavation, fill, or grading work involving 50+ cubic yards, any work within 5 feet of a property line, or retaining walls over 4 feet tall (measured from bottom of footing). Boston Building Code amendments under Boston Code Chapter IX-9.9 add enhanced requirements for urban sites — shoring plans stamped by a P.E. for excavations over 5 feet deep near occupied structures. Chelsea Building Department applies 780 CMR directly plus Chapter 9 of the Chelsea Code. Revere §17.28.040 and Winthrop §17.06 follow 780 CMR with local fill permit requirements for 20+ cubic yards of clean fill. Drainage law follows the Massachusetts common-law 'reasonable use' rule (see DeSanctis v. Lynn Water and Sewer Commission, 423 Mass. 112, 1996) — property owners may alter drainage as long as it does not cause 'unreasonable' harm to neighbors. Redirecting concentrated roof runoff or graded water onto an adjoining lot is actionable. Retaining walls over 4 feet (measured from bottom of footing to top of wall) require a permit and structural engineering per 780 CMR 1807. Walls holding back a surcharge (vehicle load, building, slope) require engineering regardless of height.