2151002Princeton Hydro West Essex Stormwater Comments to Planning Board 20250310

Stormwater Management Review for Municipal Planning Board Approval West Highlands, Inc. Block No. 179, Lot No.32, West Orange Township, Essex County, New Jersey March 2025 Princeton Hydro, LLC: 2151.002 2 1.0 INTRODUCTION The application entails the proposed construction of multi-family residential development with recreational facilities and a clubhouse for residents of the facility with a limit of disturbance of 1,233,793 sf (28.32 acres). The 120-acre parcel is currently undeveloped. The project has not received any Municipal but has received DEP approval in October 2024. The purpose of this letter is to briefly summarize deficiencies that we have observed in the revised application materials related to critical aspects of the application’s compliance with the New Jersey Stormwater Management Rules at N.J.A.C. 7:8 and the Township’s local stormwater ordinance, §25-29 of the general ordinances. 2.0 STORMWATER MANAGEMENT The site plans and stormwater calculations have been reviewed to determine if the design engineer has demonstrated compliance with N.J.A.C. 7:8, the New Jersey Stormwater BMP Manual and §25-29 of the local general ordinances. We find the application fails to demonstrate it meets the requirements as it relates to the soil testing requirements (Chapter 12 of the New Jersey Department Best Management Practices Manual, BMP Manual) and the two of the three primary stormwater management performance metrics, groundwater recharge (section P of §25-29) and stormwater runoff quantity standards (section R of §25-29). The following subsections outline our specific concerns as they relate to these three areas with the application submission. It is our professional opinion that the applicant has failed to demonstrate compliance with the requirements of N.J.A.C. 7:8. 2.1 SOIL TESTING REQUIREMENTS Before discussing the issues of compliance with two of the three primary stormwater management performance metrics, this section will provide a breakdown of the soil testing requirements as stated in Chapter 12 of the BMP Manual and compare it to the soil testing provided in this application. The BMP manual was developed to provide examples of ways to meet stormwater design standards set by the state. The BMP Manual was developed by the New Jersey Department of Environmental Protection, in coordination with the New Jersey Department of Agriculture, the New Jersey

design standards set by the state. The BMP Manual was developed by the New Jersey Department of Environmental Protection, in coordination with the New Jersey Department of Agriculture, the New Jersey Department of Community Affairs, the New Jersey Department of Transportation, municipal engineers, county engineers, consulting firms, contractors, and environmental organizations. As stated in Chapter 12 of the BMP Manual, understanding the character and saturated conductivity of surface and subsurface soils at a proposed land development site is crucial to the design of stormwater best management practices (BMPs) that meet the requirements of the New Jersey Stormwater Management rules at N.J.A.C. 7:8 and §25-29 of the local general ordinances. Section 2 of Chapter 12 further clarifies that saturated soil hydraulic conductivity and depth to Seasonal-High Water Table (SHWT) are of high importance for the design of stormwater BMPs. Subsection 1d of Chapter 12 provides guidelines for determining the upper limit of the zone of saturation which is known as the SHWT. The chapter states there are two methods for determining the SHWT: 1. When mottling showing the redoximorphic features is observed at any season of the year, the SHWT shall be taken at the highest level at which mottling is observed except when the water table is observed at a higher elevation. 2. When mottling showing redoximorphic features is not observed the SHWT shall be determined by water level elevation observed in the soil pit or boring when the testing took place from January through April.