Point of Analysis #2 (Study Area Road)

The post-construction runoff hydrographs for the current and projected 2-, 10-, and 100-year storm events do not exceed, at any point in time, the pre-construction runoff hydrographs for the same storm events. Refer to appendix for hydrograph comparisons of this point of analysis.

In accordance with NJAC 7:8-5.5, stormwater quality standards are applicable when a major development results in an increase of one-quarter acre or more of regulated motor vehicle surface. The proposed development utilizes the following BMP in order to meet the required 80% TSS removal rate as annual average:

The project has been designed to satisfy the groundwater recharge requirements set forth in NJAC 7:50-56.84(a)6.iv(1) by infiltrating the total runoff generated from the net increase in impervious surfaces by a 10-year, 24-hour storm. HydroCAD Stormwater Modeling Software has been utilized to verify satisfaction of the recharge requirement. Groundwater Recharge Calculations are included within the appendix of this report.

The proposed underground infiltration basin has been designed to retain and infiltrate the total runoff volume generated from the net increase in impervious surfaces by the 10-year, 24-hour storm, per NJAC 7:50 requirements. The total volume that is required to be retained and infiltrated is 13,939 cubic feet. The volume requirement is met by modeling exfiltration within HydroCAD for the proposed underground infiltration basin. This provides approximately 17,075 cubic feet of water to be infiltrated during the 10-year projected rainfall event. When utilizing the infiltrated volume the maximum mound during the 10-year storm is 8.664 feet. Seasonal High Groundwater was not encountered during the field tests, therefore the termination elevation for SPP-1 (105.8) was used to determine the approximate height of the mound during the 10-year storm. The mound during the 10-year storm could reach a maximum elevation of 114.46 which is 3.04 feet below the