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

3 defines Irvington's local design flood elevation (LDFE), the actual minimum elevation standard applicants must meet, as the best-available flood hazard data plus the state Flood Hazard Area Control Act's statewide minimum elevation requirements for A, Coastal A and V Zones, ASCE 24 requirements for critical facilities, and additional freeboard the chapter itself adds on top. For a delineated watercourse, the standard is the best-available flood elevation plus one foot of freeboard, or the freeboard the state's flood hazard rules require. Where a watercourse is not delineated but drains 50 acres or more, applicants must use an unexpired NJDEP flood hazard area verification, or an engineered Method 5 or Method 6 determination, each plus one foot of freeboard and any additional ASCE 24 freeboard.

Zone AO areas add one foot of freeboard to the FIRM's stated flood depth, or default to three feet above the highest adjacent grade if no depth is shown. Critical facilities get more protection: Class IV facilities, such as emergency operations centers, need the higher of the 500-year flood elevation or the flood hazard design elevation plus two feet of freeboard, while Class III facilities in coastal high hazard areas need one additional foot. 3 before, during and after construction.