O30 Princeton Hydro Report Dated 9 3 25

West Essex Highlands Review West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 Princeton Hydro compared the number of test pits for each BMP to the number required by the New Jersey BMP Manual to confirm if the applicant performed the required minimum number of soil tests for each BMP as is shown below in Table 2. Due to the discrepancy outlined above with respect to the BMP areas, Princeton Hydro used the area shown on the plan for the completion of the table below. Table 2: Number of Soil Tests Performed for each BMP against the Minimum Number Required. BMP ID Infiltration Area (SF) Plan | Number of Tests Number of Test Compliant Provided Required Plan (Y/N) 1 45,490 5 8 Y 2 25,830 4 Y 3 5,558 2 2 Y 4 12,369 3 3 Y 5 14,611 2 3 N 6 37,473 4 5 N 7 13,405 1 3 N 8 15,900 2 3 N 9 17,981 3 2 * 10 9,467 1 2 N in 22,826 4 4 Y 12 1,004 2 2 ha Based on a review of the site plan alone, it will appear that there were more soil tests performed than are shown in Table 2 for BMP 7. However, the applicant did several soil tests at the wrong time of the year (for example G1 and G2 were taken in May). While you can use mottling to establish the SHWT at any time of the year, water elevation can be used to determine SHWT only if the work was done between January and through April according to the New Jersey BMP Manual. The estimated SHWT provided by the applicant for G1 and G2 is the bottom of the test pit. All the test pits labeled with letters (not TP) and numbers were performed after April and cannot be counted towards compliance. Adequate testing for BMP 7 is essential since the basin bottom is proposed at an elevation of 531.5, approximately 16.5 feet lower than the delineated wetland located a little over fifty feet to the north of the basin. BMPs 5, 6, 8, and 10 are short one soil test and BMP 7 is short two test pits. This non-compliance is important, especially considering the example of BMP 6 where the elevation of the groundwater was shown to vary greatly due to the natural topography of the site. This is a vulnerability in the design that shows how the project is potentially not conforming to N.J.A.C. 7:8 5.4 (Local Ordinance 25-29.4 P) 7:8 5.6 (Local Ordinance 25-29.4 R) for groundwater recharge and stormwater quantity control standards. 2.4 GROUNDWATER MOUNDING CALCULATIONS The soil testing showed relatively low hydraulic conductivity for

Local Ordinance 25-29.4 R) for groundwater recharge and stormwater quantity control standards. 2.4 GROUNDWATER MOUNDING CALCULATIONS The soil testing showed relatively low hydraulic conductivity for most of the Site. The applicant proposes to replace the existing soil from the bottom of the BMPs to the SHWT with a sandy soil that has much higher hydraulic conductivity in an effort to meet the requirement that all basins Princeton Hydro, LLC Page | 12