O30 Princeton Hydro Report Dated 9 3 25

West Essex Highlands Review West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 POROUS PAVEMENT #3 SECTION ‘SORE NTS Figure 4: Cross Section of BMP 3. 2.5 IMPACTS TO WETLANDS In the existing conditions, the stormwater runoff generated from the existing topography travels over the surface and reaches the upgradient wetlands providing valuable water to the wetland ecosystem. In the proposed condition, the discharge locations for each of the drainage areas are at the bottom of the project area. This is illustrated in Figure 5. The blue arrows show the existing flow paths and the fuchsia arrows represent the proposed flow paths. The proposed stormwater system intends to route the stormwater runoff through a pipe network to basins where all the surface runoff will discharge much further downstream. The drainage area to the wetlands uphill of the discharge locations will have a smaller drainage area and collect less stormwater runoff. Princeton Hydro included two attachments that show the existing drainage areas for eastern and western wetlands. The western wetlands have a drainage area of approximately 32 acres. The proposed improvements to DA for the western wetlands will reduce the drainage area by nine acres or 28% of the total existing drainage area. The eastern wetlands have a drainage area of 48 acres. The proposed improvements to the DA for the eastern wetland will reduce the drainage area by 16 acres or 33% of the total existing drainage area. In addition, to the modified drainage areas to the wetlands there are at least two instances where the proposed design will result in the hydrologic gradient of groundwater to the wetlands being modified and redirected toward two of the proposed infiltration basins, BMP 2 and BMP 7. For example, the bottom of BMP 2 is at elevation 544 (this is incorrectly identified as being 544.5 on plan sheet SP-55 as the bottom of the basin should be the base of the 6-inch sand layer). Figure 6 shows a cross section of BMP 2 with the elevations of the adjacent wetland. In this case, the basin bottom is situated as much as six feet below the elevation of the wetland which is less than 75 feet from the wetland to the east (see Figures 6 and 7). More importantly, the groundwater data indicates that the SHWT for boring six is approximately ten feet lower than that of the surface of the nearby wetland. In addition,

e east (see Figures 6 and 7). More importantly, the groundwater data indicates that the SHWT for boring six is approximately ten feet lower than that of the surface of the nearby wetland. In addition, TP22 is located approximately fifty to the Princeton Hydro, LLC Page | 15