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

3.1.4 Existing Watersheds The existing watersheds are depicted on Figure 4 – Existing Watershed Map. Watershed EX-1-DISTURBED is approximately 1.52± acres and consists of predominantly wooded areas, open space areas, and portions of the existing parking lot that are proposed to be disturbed in the post-construction condition. This watershed is conveyed via overland flow to the existing conveyance network within Laurel Avenue and Eagle Rock Avenue. From there it is conveyed to the existing manhole in Eagle Rock Avenue, Point of Analysis 1 (POA-1). Watershed EX-1-UNDISTURBED is approximately 5.00± acres and consists of portions of the existing building, parking area, driveway, Laurel Avenue, Eagle Rock Avenue, and pervious grass and wooded areas that are proposed to remain undisturbed in the post-construction condition. This watershed is conveyed via overland flow and the existing onsite conveyance network to the existing conveyance network within Laurel Avenue and Eagle Rock Avenue. From there it is conveyed to the existing manhole in Eagle Rock Avenue, Point of Analysis 1 (POA-1). Watershed EX-2-DISTURBED is approximately 2.41± acres and consists of portions of the existing parking area, driveway, and pervious wooded and grass areas that are proposed to be disturbed in the post-construction condition. This watershed is conveyed via overland flow and the existing onsite conveyance network to the existing conveyance network within Eagle Rock Avenue. From there it is conveyed to the existing catch basin in Eagle Rock Avenue, Point of Analysis 2 (POA-2). Watershed EX-2-UNDISTURBED is approximately 2.92± acres and consists of prtions of the existing parking area, buildings, Eagle Rock Avenue, and pervious wooded and grass areas that are proposed to remain undisturbed in the post-construction condition. This watershed is conveyed via overland flow and the existing onsite conveyance network to the existing conveyance network within Eagle Rock Avenue. From there it is conveyed to the existing catch basin in Eagle Rock Avenue, Point of Analysis 2 (POA-2). Refer to Appendix A for weighted curve number (CN) calculation worksheets and supporting hydrologic calculations for the determination of peak runoff rates. 3.1.5 Allowable Peak Discharges The proposed development increases the amount of impervious coverage compared to the existing condition, causing

culations for the determination of peak runoff rates. 3.1.5 Allowable Peak Discharges The proposed development increases the amount of impervious coverage compared to the existing condition, causing post-construction peak runoff rates to exceed pre-construction peak runoff rates within the watersheds with the most concentrated areas of development. Therefore, it shall be demonstrated in accordance with N.J.A.C. 7:8-5.6.(b).3 that the post-construction peak 8