O30 Princeton Hydro Report Dated 9 3 25

West Essex Highlands Review West Orange, NJ Permit No, 722-04-0001.1 LUP230001 April 2025 BMP 6 shows a SHWT of 598 using the 2024 soil testing data but the 2021 testing data shows a different story. In 2021, TP 4 shows seepage at 608 which is 10 feet higher than what the plans show. Based on this finding, the porous pavement design is not compliant. The SHWT (which in this case was direct seepage) is within the storage volume of the basin see Figure 1. BMP 4 shows a SHWT of 567 (Figure 2) on the plans but that is only using data from the soil tests taken in 2024 (Test Pit 28). In 2021, soil tests were also taken, and TP 10 (Figure 5) is very close to BMP4. TP 10 shows a SHWT of 573 (Figure 2) six feet higher than TP 28 which would result in the groundwater level being within the storage bed of the BMP, which clearly does not comply with the two-foot minimum separation and would result in a non-functional BMP. There is also an error on the TP- 10 soil profile. On the right-hand side of the document, there is an entry for the water level found; however it is left blank. Elsewhere on the same test pit log it states that seepage was found at 3 feet below grade which is an elevation of 573 (576-3 = 573). Groundwater seepage is water leaking through the side walls of the soil profile, the seepage is an indicator of the SHWT and it should have been marked that way. ° BMP 4 (Porous Pavement) e BMP 9 (Aboveground basin) Finally, there is an error with BMP 9. The construction detail states that TP 46 has a SHWT at 548 but the soil profile states the ground surface elevation is 574 and the depth to SHWT is 8 feet which results in an elevation of SHWT at 566. Elevation 566 is much higher than 548 and would require the design to be significantly altered if the design were to comply with the stormwater regulations. See Figure 3 below for the necessary references to the plans and soil profiles. These findings show that BMPs 4, 6 and 9 are not compliant with NJDEP. The SHWT is too high and would occupy a portion of the storage volume of each of the BMPs. This would result in less groundwater recharge than calculated in the stormwater report and higher peak flow rates from each BMP. The BMPs need to be revised. These revisions could require the BMPs to be widened, shortened or relocated in general. The bottom of the BMPs need to be maintained at the minimum of two feet

each BMP. The BMPs need to be revised. These revisions could require the BMPs to be widened, shortened or relocated in general. The bottom of the BMPs need to be maintained at the minimum of two feet above the SHWT to meet the requirements. This is another way that the design is not demonstrating compliance with N.J.A.C. 7:8 5.4 (Local Ordinance 25-29.4 P) 7:8 5.6 (Local Ordinance 25-29.4 R). Princeton Hydro, LLC Page | 7