O30 Princeton Hydro Report Dated 9 3 25

West Essex Highlands Review West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 The analysis of the existing drainage area for POA2 has yet another flaw. The drainage area for POA 2 has two clear discharge locations in the proposed condition, but it only assumes discharge location at Kuzik Road (see Figure 10). The design has two discharge locations, but the modeling assumes they are combined. The flows do eventually combine but that is approximately 600 ft into the adjacent neighborhood. The drainage area analysis must be reanalyzed as two separate drainage areas with two separate analyses to ensure the peak flow rate at both locations does not increase. It is difficult to understand at this time how this change will impact the proposed design but it could be substantial. This re-evaluation is necessary to ensure that the peak flow rate of runoff from the Site is compliant with the state and local regulations and to prevent downstream flooding. - y mae. sie ; = ND Cent SO Figure 10: These are images of DA-1 and DA-2 from the Stormwater report to demonstrate how the DA for POA 2 should be modeled as two separate DA's because there are two separate points of discharge 2.8 SEPARATION OF SANITARY INFRASTRUCTURE AND BMP The design has a sanitary pipe traveling through porous pavement system (Figure 11). While we are not aware of a specific rule against having a sanitary line traveling through a subsurface basin, it appears to be a poor design decision that is counter to the rules and common engineering design sense. The purpose of the distances is to prevent leaking sanitary pipes from entering the stormwater system and potentially causing an illicit discharge of raw wastewater. The design should be modified to relocate the sanitary pipe out of the subsurface system. This may require the project to have additional Flood Hazard and/or Wetlands Permitting depending on how the layout is impacted by this modification. Princeton Hydro, LLC Page | 21