J_2024 05 09_West Orange Stormwater Management Plan

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report Figure 1 - Site Location Map TRC Engineers, Inc. 3 March 2012

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PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report Figure 2 - Site Aerial TRC Engineers, Inc. 4 March 2012

©trc AS 10 j Mr PROPOSED STATION EXPANSION Source: Bing Maps, 2010, NAVTEQ 2010 Figure 2: Aerial Photograph PSE&G West Orange Switching Station Township of West Orange, NJ

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report 2. Soil Types Review of the Natural Resource Conservation Service (NRCS) Web Soil Survey data and information indicates that there are six (6) principal soil types present in the site vicinity. Table II-1 provides a tabular listing of soil types present and summarizes their hydrologic characteristics. A copy of the NRCS Soils Map and other key soil characteristics are included in Appendix A. Table II-l Table of Soil Characteristics Map Unit BogBc BogCc DuuB UdbonB URBONB USBONB Soil Name Boonton loam, 0 to 8% slopes, extremely stony Boonton loam, 8 to 15% slopes, extremely stony Dunellen - Urban land, Dunellen substratum complex, 0 to 8 % slopes Udorthents, Boonton substratum, 0 to 8 % slopes Urban Land, Boonton substratum, 0 to 8% slopes Urban Land, Boonton substratum-Boonton complex, 0 to 8% slopes Water Table (cm) >200 Depth to Restrictive Layer (cm) 76 Hydrologic Soils Group C Slope 0-8% >200 76 C 8-15% >200 >200 A 0-8% >200 >200 D 0-8% >200 >200 N/A 0-8% >200 >200 N/A 0-8% The existing West Orange Switching Station, as well as the proposed expansion area, is located within soils designated by the NRCS as Urban-Boonton substratum soils (URBONB) and Urban-Boonton substratum-Boonton complex soils (USBONB) with 08% slopes. Urban soils are described by the NRCS as soils where 80 percent of the surface is covered by asphalt, concrete, buildings, or other impervious areas. Although the NRCS does not assign a hydrologic soil group to urban soils, to be conservative and to reflect the low infiltration capacity at the site, runoff curve numbers (i.e., CN values) corresponding to hydrologic soils group “D” were assigned to the various cover types identified within the area of interest. The geotechnical report provided in Appendix A also shows a solid clay layer underlying the site which shows that there is not much infiltration capacity. Surface materials in Borings SBH-1 and 2 are underlain by clayey sand and sandy clay fill which extend to depths on the order of two and one-half feet below existing grades. At SBH-5, loose clayey silts and clayey sands were encountered to about nine feet that likely represent fill materials from past site grading activities. TRC Engineers, Inc. 5 March 2012

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report 3. Water Resources As shown on the USGS Quadrangle Map (Figure 1), on a regional basis runoff from the site drains in a southwesterly direction and ultimately discharges into an unnamed tributary to the Rahway River. The current water quality classification for the Rahway River is FW2-NT. Review of the Flood Insurance Rate Map (Figure 3) for West Orange Township (panel No. 34013C0092F), indicates that the site and proposed expansion area are not located within the 100-year floodplain. TRC Engineers, Inc. 6 March 2012

PSE&G West Orange Switching Station West Orange, NJ Stormwater Management Report Figure 3 - FEMA Map TRC Engineers, Inc. 7 March 2012

EXISTING WEST ORANGE SWITCHING STATION chAngo* Program food map* check the FEMA Flood Map 8tom at ww««.fmc.lan»ago* rdoct Federal Emcjyacy Mungr-mrat Agency ‘"WiSHfi Tlaa is an oBclal copy at a porton of tha atom rataranoad Hood map. R was extracted using F-kUT OrvLiM TN* m«p dooe not or amonamonu wrsen may howa Mao mada lutnauw to tht <mm on tha LULLiilUl ■OH E ®NAr NUUItn 34B13CKBZF NR MM PAML LAYOUT! PANEL 92 OF 209 NEW JERSEY (ALL JURISDICTIONS) ESSEX COUNTY, FIMD INSURANCE RATE HAP FIRM nnur imm* m Cav. jriui XSSSJUTLSJ jjjn icl if I rnrT M A P SCALE 1* - 500' OTHERWISE PROTECTED AREAS (OfAs) E3 Map Source: FEMA Hood Insurance Rate Map, 34013C0092F Figure 3: FEMA Map PSE&G West Orange Switching Station Township of West Orange, NJ i aad OPAs tsa ncsmsly located mrthn or Mfsoaru to Spaoht Hood Hazard Arsis COASTAL BARKER RfSOURTIS SYSTEM (CbRSj AREAS Aram drSermwed la be « wards »m 02% arentd (haaor iocM^sm OTHER AULAS Aram of 02% annurl chance flood areas td 1% annual chance Quod «Mh awcMoe depths of leas *uo 1 foot orwfch dnlrumr areas leas than 1 square mb; and eie pruts etad by hma ham 1 % • OTHER FLOOD AREAS f bflic channel of a stream plus any adpeont doodpUki arcus that must be (hat Ms 1% animal chance Rood can b FIOOOWAY AMLAS> IN ZONE Af Cnaad flood zone ewkh ealnnty hazaad (wane aalonfc no Base flood I hum 1% annual chance flood by a federal on; ao Base Flood Beeadons Spend flood Placard Area hxmoriy protected from the 1% anmid chance Bond by a Bond mntonl mms Bur eat* sheyenrty decertified Zone Alt Mom that the former Bood control msdoi is n the 1 % annual caanca or depths of 1 to 3 tost ImniBy dwH Boar on sloping icnain); a dapfa dataranlwd. For am of rfhmid fan Booting selocfaea "ana determined. flood depths of 1 to 3 feet (usually areas of ponkigl; Base flood mBow detrmdned. food HwmnJ indude Zinas AAfcAfiAO.AB, A»,V,and \T. The Baa shnation of te 1% annual chance fcwt Fooo SOM N The kuNfn* i iJuac* (tOD-ysa 2au bmn at Hta bm* is dm iLi.m< 1% diaoc* of Mm arpMlerl or aacaadad in anjr pM year. Tha Spatial i Area Is the area suhfecx to loodha by die 1% anmuicMncr flood. Areas uAgigAij JQMK VI ZOM* V XC'M A at TW 1% LEGEND SPECIAL FLOOD HAZARD AREAS <SFHfe) SUBJECT TO INUNDATION BY THE 1 % ANNUAL CHANCE FLOOO

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