Loudoun County, VA Environmental Rules: Grading & Drainage (2026)

Loudoun County grading and drainage is regulated through several overlapping systems: (1) Building Code grading permits (Virginia USBC) for excavation and fill associated with structures; (2) Erosion & Sediment Control permit (Ord. Ch. 1244) for land disturbance 10,000 sq ft+ (2,500 in RPA); (3) Stormwater Management permit (Ord. Ch. 1096) for same thresholds; (4) Facilities Standards Manual (FSM) Chapter 2 (Design Standards) for engineering details. Volume thresholds: excavation/fill over 50 cubic yards requires land grading plan review with Loudoun Building & Development. Over 500 cubic yards triggers additional engineering review. Compaction: structural fill must meet 95% Modified Proctor density (ASTM D1557) with testing; non-structural fill 90%. Retaining walls: walls over 3 feet in height require Loudoun Building permit; over 4 feet require licensed Virginia Professional Engineer design. Drainage: Virginia common-law rule (reasonable use doctrine) — property owners may not unreasonably alter drainage to the detriment of neighboring properties. Loudoun FSM Chapter 5 requires positive drainage away from structures (minimum 2% slope for 10 feet per IRC R401.3), drainage directed to streets, swales, or approved stormwater facilities — not to adjacent properties. VDOT coordination: any grading within VDOT right-of-way or affecting VDOT drainage requires Land Use Permit (24VAC30-151). Loudoun soils (heavy clay in the east, shallow to bedrock in the west) make drainage engineering particularly important. Neighbor disputes over drainage are common and may require civil litigation.