N.J. Admin. Code § 7:45-8.6

Current through Register Vol. 56, No. 19, October 7, 2024

Section 7:45-8.6 - Specific stormwater runoff quantity standards

(a) In order to control stormwater runoff quantity impacts, the design engineer shall, using the assumptions and factors for stormwater runoff, at 7:8-5.6, Calculation of stormwater runoff, complete one of the following:

1. Design stormwater management measures so that the post-construction peak runoff rates for the two-, 10- and 100-year storm events are 50, 75 and 80 percent, respectively, of the pre-construction peak runoff rates.

i. The percentages apply only to the post-construction stormwater runoff that is attributable to the portion of the site on which the proposed development or project is to be constructed;

2. Demonstrate through hydrologic and hydraulic analyses that for stormwater leaving the site, post-construction runoff hydrographs for the two-, 10- and 100-year storm events do not exceed, at any point in time, the pre-construction runoff hydrographs for the same storm events; or

3. Demonstrate through hydrologic and hydraulic analysis that there is no increase, as compared to the pre-construction condition, in the peak runoff rates of stormwater leaving the site for the two-, 10- and 100-year storm events and that the increased volume or change in timing of stormwater runoff will not increase flood damage at or downstream of the site. This analysis shall include the analysis of impacts of existing land uses and projected land uses assuming full development under existing zoning and land use ordinances in the drainage area.

N.J. Admin. Code § 7:45-8.6