Plainfield, NJ Environmental Rules: Flood Elevation Requirements (2026)

Section 17:9-30.102.3 of the Plainfield Municipal Code establishes the Local Design Flood Elevation (LDFE) in the City of Plainfield. It is set using the best available flood hazard data, the Flood Hazard Area Control Act minimum Statewide elevation requirements for lowest floors in A, Coastal A, and V zones, and ASCE 24 requirements for critical facilities, plus additional freeboard as specified by the chapter. The ordinance is Ord. No. MC 2023-06, adopted 4-10-2023.

The minimums depend on the watercourse. For a delineated watercourse, the LDFE is the Best Available Flood Hazard Data Area elevation plus one foot, or as described by N.J.A.C. 7:13, of freeboard. For an undelineated watercourse with a contributory drainage area of 50 acres or more, the applicant provides either an unexpired NJDEP Flood Hazard Area Verification plus one foot of freeboard and any additional freeboard required by ASCE 24, or a design flood elevation by Method 5 or Method 6 plus one foot of freeboard, sealed and submitted under § 17:9-30.105.2-3. In Zone AO areas the LDFE is the highest adjacent grade plus the depth number specified plus one foot of freeboard, and where no depth number is specified it is three feet above the highest adjacent grade.

Critical facilities carry more. A new or substantially improved Class IV critical facility must sit at the higher of the 0.2% annual chance (500-year) flood elevation or the Flood Hazard Area Design Flood Elevation with an additional two feet of freeboard. Class III facilities in coastal high hazard areas use the same comparison with one additional foot of freeboard.

Where design flood elevations are not specified, § 17:9-30.103.7 lets the Floodplain Administrator, who is the Zoning Officer, require the applicant to use Federal or State data or to determine the elevation through an analysis sealed by a licensed professional engineer.