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New Jersey’s Inland Flood Protection Rule is one step closer to adoption.
The NJDEP filed the rule with the Office of Administrative Law on June 2, 2023. This means the rule will be in the July 17 New Jersey Register for final adoption and become effective as of the adoption date.
This filing includes several noteworthy updates to the proposed rule, which will impact all proposed land development projects in the state of New Jersey with a few exceptions.
Here is what Bohler’s New Jersey team knows about the rule as of this article’s published date, including the latest changes.
All Federal Emergency Management Agency (FEMA)-established non-tidal flood elevations will increase as follows:
When calculating flood elevations, the new rules will require the use of projected precipitation volumes for the calculations. Projected volumes are typically greater than current volumes, and therefore will likely increase the flood elevations.
June 2023 Update: To establish flood hazard area delineation, NJDEP will permit the use of the Delmarva unit hydrograph within the coastal plain of New Jersey, provided the selection of this hydrograph is in accordance with guidance provided by USDA’s Natural Resource Conservation Service for the watershed in question. Please see the Flood Hazard Area Technical Manual for an in-depth discussion as to where the Delmarva unit hydrograph is appropriately utilized for flood hazard area delineations.
With the new elevations, a property that currently sits outside a floodplain could now fall into a floodplain zone or FHA and be subject to all associated NJDEP permitting requirements.
June 2023 Update: In cases where the Delmarva unit hydrograph is permitted to delineate the floodplain, this method typically results in lower volumes than the standard 484 unit hydrograph, and could reduce the chances of a property falling into a floodplain zone.
If a site is in a floodplain, its yield, density, and overall developability may also be limited, depending upon how much of the site falls within the floodplain under the new rule.
Under the Control Act Rule, the design of all stormwater management facilities for all new proposed land development projects in the state of New Jersey will be required to account for a higher intensity rainfall. Additionally, the NJDEP is amending the Groundwater Recharge Standards, which will require infiltration areas to also be calculated using the new higher intensity rainfall.
Though more specific details will vary by county, the higher rainfall intensities will result in an approximate 20%–50% increase in stormwater basin size. Incorporating larger basins can impact a site’s yield, overall layout, and construction and maintenance costs.
If your project is not subject to RSIS, consult your site civil engineering consultant for assistance in evaluating your options. Inquire about the design team’s ability to either obtain stormwater management permits prior to the municipality adopting the new regulations or to reconfigure the design to accommodate the latest regulations.
This information is fluid and continues to evolve as the state works through this process. Bohler is in frequent communication with state agencies, attorneys, and industry professionals to keep our teams and our clients apprised of the latest information.
If you are concerned that your project may be affected by these changes, please contact our team today.
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