5 county-level rules, plus city-specific rules for 1 city in New Castle County, Delaware.
Verified from official government sources
New Castle County enforces stormwater management under Delaware's Sediment and Stormwater Program (7 Del.C. Chapter 40 and DNREC Delegation) administered by the New Castle Conservation District (NCCD). Projects disturbing 5,000+ sq ft or adding 5,000+ sq ft of impervious surface require an approved sediment and stormwater plan. Post-construction BMPs (bioswales, rain gardens, infiltration) are mandatory. NCC holds MS4 permit under Clean Water Act.
Erosion and sediment control is mandatory on all land-disturbing activities in New Castle County under the Delaware Sediment and Stormwater Program (7 Del.C. Chapter 40). Plans administered through the New Castle Conservation District (NCCD). Standard BMPs include silt fence, stabilized construction entrance, inlet protection, sediment traps, and rapid stabilization. Violations can halt construction and incur significant fines.
New Castle County contains Delaware Coastal Zone Act (CZA) regulated areas along the Delaware River and Bay (7 Del.C. Chapter 70). Heavy industry is banned in the coastal zone; most other development requires DNREC approval. Wetlands are protected under 7 Del.C. Chapter 66 (Wetlands Act). Port of Wilmington operates under special CZA provisions. Subaqueous Lands Act (7 Del.C. Chapter 72) regulates tidal and river bottoms.
Significant portions of New Castle County lie within FEMA-designated flood zones along the Christina River, Brandywine Creek, Red Clay Creek, and Delaware River. Floodplain permits are required for development in these areas.
Grading and drainage in New Castle County are regulated through NCC Code building permits (IRC/IBC grading provisions) and the Delaware Sediment and Stormwater Program (7 Del.C. Chapter 40). Grading exceeding 100 cubic yards or creating significant cuts or fills requires permit. Drainage cannot be redirected onto neighboring property. Retaining walls over 4 feet require engineered design.
1 cities in New Castle County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
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