2026 02 12 Crestmont CC and Eagle Rock Ave Stormwater Management Report

den soil layer. A generalized description of the subsurface conditions is provided below. Surficial Material Surficial materials consisted of grass and topsoil. An approximately 0.5-ft to 3-ft-thick layer of fill material, generally consisting of gravel, sand, or silt was encountered in the majority of the test pits beneath the surficial materials. In test pit TP-17, a 10-ft thick layer of fill material consisting of silty sand was encountered beneath the surficial materials. A buried topsoil layer approximately 1.25 ft thick was encountered in test pit TP-18 at approximately 3 ft below surface grade. Natural Soils Natural soils generally consisting of intermixed layers of sand and silt with varying amounts of gravel, clay, cobbles and boulders were encountered below the surficial and fill materials. The thickness of this natural overburden soil layer generally ranged from approximately 1 ft to 10 ft. = = =

Stormwater Management Field Testing Results MEMO Eagle Rock Ave and Oval Road Improvements 750 Eagle Rock Avenue, West Orange, New Jersey Langan Project No. - 101049802 25 August 2025 - Page 3 of 4 Bedrock The top of bedrock was encountered below the natural soils ranging from approximately 1 ft to 9 ft below surface grade in test pits TP-1, TP-7, TP-14, TP-15, TP-16, TP-18, TP-19, TP-20 and TP- 21. The remaining test pits were terminated prior to reaching the top of bedrock. Signs of Seasonal High Water Table The signs of Seasonal High Water Table (SHWT) as identified in the New Jersey Stormwater Best Practices Manual include visual observation of groundwater seepage and soil mottling. The location, depth and elevation of observed soil mottling and/or water seepage encountered in the profile test pits are summarized below. The determination of the SHWT elevation is provided in Table 1 – Summary of Profile Test Pits and Infiltration Testing Results. Soil Mottling Approximate Depth of Approximate Elevation Test Pit Observed Mottling of Observed Mottling TP-8 7 ft el 537 TP-10 2 ft el 535 TP-20 2 ft el 564.5 TP-21 6 ft el 533.5 Water Seepage Approximate Depth of Approximate Elevation Test Pit Observed Water of Observed Water Seepage Seepage TP-2 8 ft el 529 TP-8 6 ft el 538 TP-10 7.7 ft el 529.3 TP-13 3 ft el 548 TP-21 1 ft el

7.7 ft el 529.3 TP-13 3 ft el 548 TP-21 1 ft el 538.5 PERMEABILITY TESTING RESULTS AND HSG RECLASSIFICATION The hydraulic conductivity rates ranging from approximately 0.000417 to 0.0484 inches per hour were determined in the 20 samples taken as part of this subsurface investigation. = = =

Stormwater Management Field Testing Results MEMO Eagle Rock Ave and Oval Road Improvements 750 Eagle Rock Avenue, West Orange, New Jersey Langan Project No. - 101049802 25 August 2025 - Page 4 of 4 In accordance with the New Jersey Stormwater Best Practices Manual and the NRCS National Engineering Handbook, Part 630 – Hydrology, Chapter 7 Hydrologic Soil Groups, Table 7-1: Criteria for Assignment of Hydrologic Soil Group, the Hydrologic Soil Group (HSG) has been evaluated at select test pit locations based on the depth to observed groundwater level, observations of soil mottling (an indicator of SHGW), soil gradation, and laboratory tube permeameter testing of select soil samples. Based on this evaluation, the site is classified as Hydrologic Soil Group D. The laboratory testing results are provided in Appendix C and are summarized in Table 1. CLOSURE Our Stormwater Management Investigation was performed to assist our Site/Civil Engineers with the design of the proposed stormwater management system associated with the proposed Eagle Rock Avenue and Oval Road Improvement in West Orange, New Jersey. \\langan.com\data\PAR\data8\101049801\Project Data\_Discipline\Site Civil\Reports\Stormwater\2026-02-12 SWM Report\Appendix F\2025-08-25- Geotech SWM Result Memo.docx = = =

TABLES Table 1 Summary of Profile Test Pits and Laboratory Testing Results = = =

101049802 8/23/2025 Eagle Rock Ave Widening Project West Orange, New Jersey TABLE 1 - SUMMARY OF PROFILE TEST PITS AND INFILTRATION TESTING RESULTS Infiltration Test Determined Type of Percent Fine Determined Profile Pit ApproximateExisti Top of Weathered or Approximate Observed Top of Approximate Bottom of Observed Groundwater Level or Depth Measured Hydraulic Profile Test ID Approximate Profile Pit Bottom Seasonal High Infiltration Test material Passing Hydrologic Soil Remarks Completed Date ng Surface Grade Competent Bedrock Soil Mottling Layer Observed Soil Mottling Layer Water

Completed Date ng Surface Grade Competent Bedrock Soil Mottling Layer Observed Soil Mottling Layer Water Seepage (most restrictive Conductivity Groundwater Type the #200 Sieve Group (HSG) layer) (inches below surface (el) (ft) (el) (ft) (el) (ft) (el) (ft) (el) (ft) (el) (el) (inch/hour) % grade) TP-1 4/25/2024 538 4 534 4 534 - NE - NE - NE NE Tube 24 0.00202 50.9 D TP-2

- NE NE Tube 24 0.00202 50.9 D TP-2 4/25/2024 537 9 528 9 528 - NE - NE 8 529 529.0 - - - - - TP-3 4/26/2024 542 8 534 8 534 - NE - NE - NE NE Tube 12 0.00449 51.7 D TP-4 4/25/2024 541 8 533 8 533 - NE - NE - NE NE - - - - - TP-5 4/26/2024 550 7.5 542.5 7.5 542.5 - NE - NE - NE NE Tube 12 0.0484 46.6 D TP-6 4/26/2024 2 5.5 -3.5 5.5 -3.5 - NE - NE - NE NE Tube 18 0.000417 93.0 D TP-7 4/26/2024 548 3 545 3 545 - NE - NE - NE NE Tube 8 0.0253 56.2 D TP-8

- NE NE Tube 8 0.0253 56.2 D TP-8 4/26/2024 544 7 537 7 537 4 540 7 537 6 538 540.0 Tube 20 0.00182 57.6 D TP-9 4/26/2024 553 8 545 8 545 - NE - NE - NE NE Tube 24 0.00517 47.1 D TP-10 4/25/2024 537 11 526 11 526 1 536 2 535 7.7 529.3 536.0 Tube 16 0.000858 65.4 D TP-11 4/15/2025 543 7 536 7 536 - NE - NE - NE NE Tube 21 0.0048 60.0 D TP-12 4/15/2025 548.5 8 540.5 8 540.5 - NE - NE - NE NE Tube 12 0.015 46.1 D TP-13 4/15/2025 551 8.5 542.5 8.5 542.5 - NE - NE 3 548 548.0 Tube 30 0.0434 39.0 D TP-14

NE 3 548 548.0 Tube 30 0.0434 39.0 D TP-14 4/15/2025 559 1.75 557.25 1.75 557.25 - NE - NE - NE NE Tube 15 0.0126 40.1 D TP-15 4/15/2025 551 3 548 3 548 - NE - NE - NE NE Tube 16 0.00747 52.4 D TP-16 4/14/2025 562.5 10.5 552 9 553.5 - NE - NE - NE NE Tube 30 0.0118 41.4 D Tube A 6 0.00494 37.8 D TP-17 7/15/2025 566 12 554 12 554 - NE - NE - NE NE Tube B 6 0.00137 45.0 D TP-18 4/14/2025 567 4 563