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West Essex Highlands Review 4 West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 verification, and authorization under a general permit, an individual permit, or an emergency authorization. As part of the municipal review process Princeton Hydro had the chance to review the proposed stormwater management plan for the Project as well as site plans and other documents such as those identified below. Documents central to the contents of this letter include but are not limited to the following: * Subsurface Investigation Report Subsurface Stormwater Management System West Orange, New Jersey for Garden Homes Short Hills, New Jersey Prepared by Sor Consulting Engineers, Inc. 98 Sand Park Road, Cedar Grove, NJ 07009, Report Number 23-C-17 May 23, 2023, Job No. 23-C-16 Subsurface Investigation Report Subsurface Stormwater Management System West Orange, New Jersey for Garden Homes Short Hills, New Jersey Prepared by Sor Consulting Engineers, Inc. 98 Sand Park Road, Cedar Grove, NJ 07009, Report Number 21-C-21 April 19, 2021, Job No. 21-C-01 Subsurface Investigation Report Subsurface Stormwater Management System West Orange, New Jersey for Garden Homes Short Hills, New Jersey Prepared by Sor Consulting Engineers, Inc. 98 Sand Park Road, Cedar Grove, NJ 07009, Report Number 24-C-11 April 4, 2024, Job No. 24-C-02 Subsurface Investigation Report Subsurface Stormwater Management System West Orange, New Jersey for Garden Homes Short Hills, New Jersey Prepared by Sor Consulting Engineers, Inc. 98 Sand Park Road, Cedar Grove, NJ 07009, Report Number 24-C-02 February 12, 2024, Job No. 24-C-02 Plan titled, “Preliminary and Final Site Plans West Essex Highlands Block 179 Lot 32, Block 179.17 Lots 8 and 9 Township of West Orange Essex County, New Jersey, Overall Drainage Area Map” prepared by Paul W. Anderson, PE of Anderson Consulting Services LLC., dated September 23, 2022, last revised October 28, 2024. Drainage Report, “Stormwater Management Report (formerly Drainage Report) West Essex Highlands Block 179, Lot 32, Township of West Orange, Essex County, New Jersey,” prepared for West Essex Highlands Inc., prepared by Anderson Consulting Services LLC., dated March 12, 2023, last revised October 28, 2024. It is our professional opinion that the application contains critical deficiencies and errors related to stormwater management that are inconsistent with

arch 12, 2023, last revised October 28, 2024. It is our professional opinion that the application contains critical deficiencies and errors related to stormwater management that are inconsistent with N.J.A.C. 7:8 and the New Jersey BMP Manual. Specific plan deficiencies identified in this letter illustrate that the application fails to demonstrate full compliance with the regulations. These deficiencies warrant the suspension of Permit No. 722-04-0001.1 LUP230001 in accordance with the provisions of N.J.A.C. 7:13-22.7. Key elements of the failure to fully comply are related to the following. e Soil testing requirements e« Groundwater mounding analysis Princeton Hydro, LLC Page | 2

West Essex Highlands Review West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 ¢ Peak flow calculations « Impacts to onsite wetlands 1.0 INTRODUCTION West Essex Highlands is a proposed multi-family residential development with recreational facilities and a clubhouse with a limit of disturbance of 1,233,793 sf (28.35 acres). The 120.4 acre parcel is located in the headwaters of Canoe Brook and is currently undeveloped. The steeply sloping site is almost completely forested. The West Essex Highlands development project is currently being reviewed by the Township of West Orange Municipal for Planning Board approval and the proposed project will necessitate the removal of approximately 28.35 acres of relatively mature forest. The purpose of this letter is to briefly summarize the various deficiencies identified during our review of 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, the BMP Manual and the Township's local stormwater ordinance, § 25-29 of the general ordinances. 2.0 STORMWATER MANAGEMENT It is our professional opinion that the applicant failed to demonstrate compliance with the requirements of N.J.A.C. 7:8.The site plans and stormwater calculations have been reviewed to determine if the design engineer, Anderson Consulting Services LLC (ACS), has demonstrated compliance with N.J.A.C. 7:8, the New Jersey BMP Manual and §25-29 of the Township of West Orange's local stormwater ordinance. We find that both the application to the Township as well as the information submitted to the NJDEP fail to demonstrate that the soil testing requirements of Chapter 12 of the New Jersey BMP Manual have been satisfied for 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. 2.1 SOIL TESTING REQUIREMENTS Before discussing the issues of compliance with two of the three primary stormwater management performance metrics, this section will discuss the soil testing requirements as set forth in Chapter 12 of the New Jersey BMP Manual and compare it to the soil testing documentation provided in this

t performance metrics, this section will discuss the soil testing requirements as set forth in Chapter 12 of the New Jersey BMP Manual and compare it to the soil testing documentation provided in this application. The New Jersey BMP manual was developed to provide examples of ways to meet stormwater design standards set by the state. The New Jersey BMP Manual was developed by the NJDEP, 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 New Jersey BMP Manual, understanding the character and saturated hydraulic 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 ordinance. Section 2 of Chapter 12 further clarifies that saturated hydraulic conductivity and depth to SeasonalHigh Water Table (SHWT) are of high importance for the design of stormwater BMPs. Subsection 1d of Chapter 12 Princeton Hydro, LLC Page | 3

West Essex Highlands Review West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 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. Where mottling showing 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. Although the identification of redoximorphic features should be a key element of any soil investigation focused on the identification of a SHWT, an understanding of the soils or soil series mapped by the United States Department of Agriculture is an important initial step as it describes the various soil characteristics that may be encountered during an investigation. Copies of the USDA Official Soil Series Descriptions for the Boonton, Haledon and Hasbrouck Soils series are provided as an attachment to this letter. There are two soil series that are mapped over the mdjority of the Site, Boonton and Haledon. The Boonton soil Series is described as being “very deep moderately well and well drained soils formed in till on uplands.? One of the distinctive features of this soil series is the presence of a fragipan at an average depth of approximately thirty inches. The fragipan is a restrictive horizon that is a firm soil layer that has low to very low hydraulic conductivity. The Soil Profile Description for this soil describes the presence of “a perched water table at a depth of 46-91 centimeters (18-36 inches) from November to May of most years.” The Boonton Soils are classified as a Hydrologic Soils Group (HSG) C due to the presence of the fragipan which serves to impede the downward movement of water. The other common soil series on the Site is the Haledon series. The Haledon series “consists of very deep, somewhat poorly drained soils in low positions on undulating uplands.” This soil series also possesses a fragipan in which the hydraulic conductivity is very slow or slow. The Official soil series description indicates that there is “a perched water table within

plands.” This soil series also possesses a fragipan in which the hydraulic conductivity is very slow or slow. The Official soil series description indicates that there is “a perched water table within 30 centimeters (12 inches) of the soils surface from late winter to early spring of most years and following periods of extended rainfall."3 Redoximorphic features are present in the B horizon which begins at approximately eight inches below the ground surface. In addition, the only hydric soil identified on the Site is the Hasbrouck series. This soil “consists of deep, poorly drained soils in depressions on uplands.” These soils also have a fragipan that occurs from 40-76 centimeters (approximately 16 to 30 inches). The depth to the water table is indicated to be 0-6 inches.* Although all three soils described above possess fragipans and both the Haledon and Hasbrouck series possess redoximorphic features within the upper eight inches of the ground surface it is important to note that none of the multiple subsurface investigations identified either a fragipan or any redoximorphic features in any single soil profile across the entire site. That is not only very ' New Jersey Stormwater Best Management Practices Manual Chapter 12: Soil Testing Criteria. March 2024. Page 12 https://dep.nj.gov/wp-content/uploads/stormwater/bmp/nj_swmp_|2.pdf 2 USDA Official Soil Series Description: Boonton Series. 3 USDA Official Series Description- Haledon Series. “USDA Official Series Description- Hasbrouck Series Princeton Hydro, LLC Page | 4

West Essex Highlands Review 2 West Orange, NJ Permit No. 722-04-0001.1 LUP230001 April 2025 unusual, but as emphasized in the New Jersey BMP Manual, soil mottling/redoximorphic features should be used to establish the SHWT. The New Jersey BMP Manual also requires the identification of any “soil restrictions including, but not limited to, abrupt textural boundaries likely to restrict the movement of water, e.g., fragipans, dense materials, bedrock and ortstein horizons.”5 Importantly, soil logs must also be specific in their identification of various colors and textures throughout a profile, as is consistent with the Field Indicators of Hydric Soils in the United States referenced by the New Jersey BMP Manual. Color identification is key in correctly identifying mottling by recording the value and chroma of the observed colors which can then be used to properly describe (calculate) the contrast of the mottles. When applying the methods set forth in the New Jersey BMP Manual it is difficult to believe that redoximorphic features would not be present in the surface soils as three of the more extensive soil series on the Site are expected to possess a fragipan and perched water tables. To determine if the soils on the Site possessed redoximorphic features as described in the USDA's Official Soil Series Descriptions (Attachment A) Princeton Hydro collected soils data at four locations on the adjacent property to the south (Attachment B). The four borings were in Booton and Haledon Soils. All of the borings taken by Princeton Hydro showed that the soils possessed redoximorphic features. The soils data collected by Princeton Hydro support our concern that the perched water table described in the USDA's official soil descriptions was missed and that the SHWT is much higher than indicated. An accurate understanding of the soils as well as onsite hydrology is essential to a stormwater design that meets the NJDEP’s minimum requirements. The original soil investigation on the Site was performed by Sor Consulting Engineers. Soil investigations were done on four separate occasions. Based on the review of the soils data provided in the four Sor Consulting Engineers reports, it is apparent that the SHWT was only established using the elevation of the observed water found in the test pits or borings. It is also important to point out that it does not appear that the

ports, it is apparent that the SHWT was only established using the elevation of the observed water found in the test pits or borings. It is also important to point out that it does not appear that the analysis of the surface soils was done with a sufficient level of detailed analysis that could have documented the presence of mottling or other evidence of a SHWT. For example, in the Sor Consulting Engineers report dated May, 23, 2023, the report described the soils in TP-C1 and TP-C2 as “[t]ne topsoil was underlain by clayey soil and extended to a depth of 3.5 to 4 feet below the surface.”* Based on the Official Series Description for a Boonton or Haledon Soil one should expect to observe five distinct soil layers within 48 inches of the surface not two. It should also be noted that neither “topsoil” nor “clayey soil” are soil textures according to the NRCS classification. As noted in the New Jersey BMP Manual, there are instances where mottling can be absent from a soil profile, but it is highly unusual that mottling was not found in any of the soil test pits provided by the applicant, especially since these soil series possess a SHWT related to the presence of perched water above a fragipan. Since soil mottling is a natural and common process in saturated soil conditions it would seem reasonable that some evidence of soil mottling should have been observed in at least some of the soil profiles. The concern regarding the accurate identification of a SHWT is directly related to how well the proposed BMP will function. It is also important to acknowledge * New Jersey Stormwater Best Management Practices Manual Chapter 12: Soil Testing Criteria. March 2024. Page 23. https://dep.nj.gov/wp-content/uploads/stormwater/bmp/nj_swmp_12.pdf 6 Subsurface Investigation Report Subsurface Stormwater Management System West Orange, New Jersey for Garden Homes Short Hills, New Jersey Prepared by Sor Consulting Engineers, Inc. 98 Sand Park Road, Cedar Grove, NJ 07009, Report Number 23-C-17 May 23, 2023, Job No. 23-C-16. Page 5. Princeton Hydro, LLC Page | 5

West Essex Highlands Review 4 West Orange, NJ Permit No. 722-04-0001.1 LUP230001 ‘April 2025 that the groundwater level found in a test pit can fluctuate based on recent precipitation. Using soil mottling to determine the SHWT is recommended because it estimates the highest (most conservative) elevation that does not vary with time. It is the position of Princeton Hydro that reliance on observed groundwater elevation has underestimated the elevation of the SHWT. The New Jersey BMP Manual requires that BMPs maintain a minimum vertical difference of two feet from the bottom of the BMP to the SHWT elevation for BMPs without underdrains. The BMPs in this project do not have underdrains. Although, BMPs 2, 6 and 7 appear to maintain that minimum separation, the method used to establish the SHWT is not compliant with the NJDEP BMP manual as discussed above. If the SHWT elevations are higher than what was recorded in this plan, then there is a risk these designs will not function as envisioned and will not fully comply with the New Jersey BMP Manual. If the groundwater mounding encroaches on the storage area, it will increase the stormwater runoff from the BMP and decrease the amount of groundwater recharge the BMP can provide. N.J.A.C. 7:8 5.4 (§25-29.4 P) sets the groundwater recharge requirements and 7:8 5.6 (§25-29.4 R) sets the minimum reductions in the peak flow rates for runoff exiting a site. If the SHWT is higher in BMPs 2, 6 or 7 that would impact the Site’s compliance with both of those standards. It is also important to point out that the depth to the SHWT more offen than not follows a topographic gradient in which the SHWT is deeper in higher landscape positions and becomes increasingly shallower while moving downslope. For this Site this gradient typically ends in the wetlands present at the base of a slope and adjacent to a headwater stream. Based on the landscape position of the wetlands on the Site, in general at the base of slopes, the primary source of hydrology for the wetlands is related to groundwater and groundwater discharge. For an area to be defined as a wetland in New Jersey the SHWT in the wetland must be at a depth of twelve inches or less. A general understanding of this flow path from higher landscape positions to the wetlands is not just important as it relates to wetland impact but also to understanding groundwater on the Site and

s. A general understanding of this flow path from higher landscape positions to the wetlands is not just important as it relates to wetland impact but also to understanding groundwater on the Site and how well the proposed stormwater BMPs will function. There are at least two examples, Basin 2 and 7, where the proposed basin bottom will be excavated to an elevation below that of the closest wetland and stream. In these cases, the proposed BMP would result in the disruption of the current hydrologic gradient toward the wetland to one that redirects the hydrologic gradient toward the BMPs from the stream or wetland. This will not only impact the wetland but will add an additional source of water to the BMPs that has not been identified by the applicant. This will be discussed again in Section 2.5. 2.2 BMP DESIGN STANDARDS AND SHWT Princeton Hydro reviewed the SHWT elevations documented in the subsurface investigations against the proposed BMP designs to confirm that each of the proposed BMP's met the minimum two vertical feet of separate from the bottom of the basin to the SHWT. Despite the issue identified in the previous section with respect to the SHWT being underestimated by only observing seepage, Princeton Hydro found that the following BMP’s did not meet that minimum standard: © BMP 6 (Porous Pavement) Princeton Hydro, LLC Page | 6