Denver County, CO Environmental Rules: Grading & Drainage (2026)

Denver's Building Code (DRMC Chapter 10, adopting the Denver Building and Fire Code based on 2021 ICC codes with local amendments) regulates grading and drainage. A Grading Permit from Denver CPD is required for excavation or fill exceeding 50 cubic yards of material or land disturbance exceeding 5,000 square feet. Applications require a grading plan stamped by a Colorado-licensed engineer for significant projects, showing existing and proposed contours, drainage swales, retaining walls, and slope stabilization. Site drainage must direct water away from structures and cannot redirect runoff onto adjacent private properties or into the public right-of-way in ways that overload capacity — violating this can create both code enforcement liability and civil water-law nuisance claims. Retaining walls over 4 feet in height require a separate structural engineering permit and often setback compliance. Compaction testing by a certified soils engineer required for structural fill. Final inspection by CPD before occupancy. Denver's expansive clay soils require careful drainage design to prevent foundation failure. Montbello, Green Valley Ranch, and Stapleton/Central Park have historically been sensitive due to soil conditions.