J_2024 05 09_West Orange Stormwater Management Plan

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report Section III: Stormwater Management 1. Non-Structural Controls The Township of West Orange requires a stormwater management plan be submitted for all land development projects. Further, that flood control, groundwater recharge and pollutant reduction aspects of the plan consider non-structural or low-impact techniques before relying on structural Best Management Practices (BMPs). In accordance with Section 25-29.4 e(2), the following non-structural stormwater management strategies have been incorporated into the stormwater management plan for the site. [1] Protect areas that provide water quality benefits or areas particularly susceptible to erosion and sediment loss. The proposed expansion is located within the existing property boundary. Due to the extent of grading that will take place during construction, silt fencing and straw bale barriers, and other temporary erosion and sediment control measures will be used. In addition, retaining walls will be constructed in a few areas of the site. These areas include the north side of the switching station pad expansion, west of the new transformer containment area just north of the existing control building, and a parcel of land surrounding the existing microwave building in the northeast comer of the site. [2] Minimize impervious surfaces and break up or disconnect the flow of runoff over impervious surfaces. The net change in impervious surface coverage (i.e., the net change in surfaces covered by gravel access roads, gravel parking areas and other structures) will be a decrease of 15,833 square feet, or approximately 0.36 acres. To the maximum extent practicable, new structures located on the existing switching station pad will be disconnected from adjacent impervious surfaces, as most existing and proposed impervious surfaces drain to the yard stone surface of the switching station pad. The yard stone surface will consist of a 4-inch layer of loose 3/4” crushed stone and will not be subject to routine vehicular traffic. When placed on nearly level surfaces, voids within the 4-inch crushed stone layer must fill prior to the start of surface runoff. Therefore, unlike gravel drives and parking areas, the available storage capacity of the yard stone cover modifies the runoff characteristics for this land cover type. [3] Maximize

of surface runoff. Therefore, unlike gravel drives and parking areas, the available storage capacity of the yard stone cover modifies the runoff characteristics for this land cover type. [3] Maximize the protection of natural drainage features and vegetation. As indicated above, the expansion project will fall within the boundaries of the existing switching station. Drainage from the existing switching station discharges through a culvert under Mount Pleasant Avenue. The grass area used for temporary laydown during construction will be revegetated (i.e., returned to grass conditions). However, because of grading activities to allow for the expansion of the switching station pad, trees at the southern end of the existing pad will be cleared. This area will be replaced by a meadow surface. Noting that the new transformer secondary containment structures will TRC Engineers, Inc. 8 March 2012