2022 08 Drainage Report

the project and the post development peak discharge rate and volume. Of particular concern are hydraulic control points, (culverts, bridges, etc.), bends in streams and sudden changes in channel cross sections downstream of the discharge point. The following may be utilized to assess stability: The proposed design utilizes approach 2 as described below. 2. In lieu of performing a comprehensive watershed analysis, design a detention facility that reduces peak flows to the following levels. Infiltration may be used to meet these criteria: 2-year storm — 50% of the predevelopment peak 10-year storm — 75% of the predevelopment peak Reductions in peak flows are to be compared to pre-developed drainage area points of discharge in the event that drainage is re-directed in the post developed condition. Reductions are only required of the developed or modified portions of the project site. As documented in the subsections above, the proposed peak flows meet the above reductions, thereby achieving off-site stability. XI. CONCLUSION The proposed development has been designed with provisions for the safe and efficient control of stormwater runoff in a manner that will not adversely impact the existing drainage patterns, adjacent roadways, or adjacent parcels. In addition, the proposed development satisfies the runoff quantity, quality and groundwater recharge requirements set forth by the Township of West Orange Land Use Ordinance and NJAC 7:8 through the use of the proposed aboveground small-scale bioretention basins with underdrains. With this stated, it is evident that the proposed development will not have a negative impact on the existing drainage conditions, water quality or groundwater recharge on-site or within the vicinity of the subject site. SHI Builders August 2022 DEC# 4266-99-001 -ll-