Review Zone Application for D&R Canal Commission Decision

Transcription

1 Review Zone Application for D&R Canal Commission Decision MEETING DATE: July 20, 2016 DRCC #: Latest Submission Received: June 13, 2016 Applicant: Robert McCarthy, PE PSE&G 4000 Hadley Road, 2 nd Floor South Plainfield, NJ Engineer: Steven Hansen, PE Burns & McDonnell 9400 Ward Parkway Kansas City, MO Project Location: Road Municipality County Block(s) Lot(s) Prospect Street Ewing Twp Mercer , 50 Jurisdictional Determination: Zone B Major Nongovernmental Subject to Review for: Drainage Visual Subdivision Stream Corridors X X THIS STAFF REPORT IS ISSUED AS A GUIDE TO APPLICANTS IN COMPLYING WITH DRCC REGULATIONS. IT IS NOT AN APPROVAL. NO CONSTRUCTION SHALL BEGIN UNTIL A CERTIFICATE OF APPROVAL HAS BEEN ISSUED. Documents Received: Letters from Robert McCarthy, PE (3 pages) dated March 17, 2016, and (5 pages) dated June 13, 2016; Existing Conditions Survey (1 sheet) dated February 19, 2016; DRCC Stream Corridor Exhibit (1 sheet) dated March 15, 2016, revised May 27, 2016; DRCC Existing Conditions Exhibit dated June 1, 2016; and Site Plan (1 sheet) dated February 19, 2016, last revised May 17, 2016; prepared by PSE&G Services Corporation; Acoustical Study dated December 30, 2015, prepared by Ostergaard Acoustical Associates; Site Plans (18 sheets) and Stormwater Management Plan dated December 31, 2015 (Sheets 6, 7, and 8 last revised May 3, 2016) prepared by Burns & McDonnell; Application Report dated March 2016, Landscaping Plan (1 sheet) dated February 19, 2016, revised May 17, 2016, and Application Amendment- Alternatives Analysis dated June 2016, prepared by DW Smith Associates. Mercer County Soil Conservation District Soil Erosion and Sediment Control Plan Certification dated May 5, 2016; Stormwater Management Measures Manual prepared by Steve Hansen, PE, dated May 17, PO BOX 539 STOCKTON, NJ FAX

2 2 The application is complete and shall be presented to the Commission for their action with a staff recommendation of approval at the July 20, 2016 meeting, based upon the following analysis: Existing Conditions: The project site is 2.20 acres in size and consists of two lots, Lot 50 and Lot 43, located on the west side of Prospect Street (CR 627) between North Olden Avenue and the West Branch of the Shabakunk Creek. The lots are located in Ewing Township, Mercer County, within Commission Review Zone B. Lot 50 is 0.68 acres in size and contains the PSE&G Ewing Substation which was constructed in It includes an existing 26 kilovolt (kv) substation that is fully enclosed by a seven-feet-high chain-linked barbed-wire security fence. The existing substation is located on a gravel lot with grassy areas on each side of the 14-feet-wide access drive, with a few mature trees along the frontage of Prospect Street. The station yard also includes a 36-inch to 42-inch high concrete flood wall, a small one-story masonry control house, as well as several concrete pads and footings. The substation equipment is near the end of its useful life and is prone to periodic flooding, causing power outages and other complications during flood events. The Ewing Substation provides electrical service to about 4,475 customers in Ewing Township and the City of Trenton. Adjacent Lot 43 is 1.52 acres in size and contains a two-story masonry building with an asphalt parking lot, sidewalks, overgrown vegetation, and wooded areas. The lot is bounded by Prospect Street to the east, a golf range to the south, undeveloped green space to the west and commercial properties to the north. Proposed Project: The applicant is proposing to disturb a majority of the site for a project including the conversion and expansion of an existing 26kV substation to a 69kV substation. The upgrade to the Ewing Substation is part of a larger regional effort known as the Fernwood Area 69kV Network Project to improve the overall capabilities and reliability of transmission systems throughout the area. More specifically, the proposed improvements will include the following: The demolition and removal of the existing gravel substation yard, including the 16,357-square-feet industrial use building and 162-square-feet control house, the approximate 46,900 square feet of impervious asphalt and concrete parking lots, a portion of the existing loose gravel substation yard, as well as a number of concrete footings and sidewalks, The installation of four new 69kV circuit breakers with associated disconnects, bus support structures, and open-air three phase aluminum buswork, The installation of two 69/4kV transformers on concrete pads, new 4kV sheltered aisle switchgear on an elevated platform, a 1,024-square-feet control house, and new underground cables, The construction of 140 concrete spread footings for the steel supports of the proposed process equipment, and

3 3 A decorative fence with a cantilever entrance gate, chain link fence along the rear of the property, about 38,250 square feet of new gravel access driveway and yard gravel surfacing, 150 square feet of concrete driveway apron. The project will result in a 0.23-acre net decrease in the amount of impervious surface area onsite after construction. The proposed project shall result in an area of disturbance of about 2.10 acres. Stream Corridor: The project site is located entirely within the 100-year floodplain of the West Branch of the Shabakunk Creek. The 100-year floodplain has been delineated by both FEMA and NJDEP. In consideration of the extent of the 100-year floodplain of the West Branch of the Shabakunk Creek, the entire project site is situated within the Commission stream corridor. Therefore, this project is subject to a stream corridor impact review. The applicant will be demolishing a building, creating new structures, creating internal drive areas, creating parking, removing plantings, landscaping, mowing and regrading within the stream corridor. These are prohibited uses within the stream corridor, N.J.A.C. 7: The applicant seeks a waiver of the stream corridor impact standards pursuant to N.J.A.C. 7: (a)1. N.J.A.C. 7: (a)1 states that a project may be waived from strict adherence to stream corridor impact standards if the applicant establishes that the project will not have an adverse impact upon the stream corridor s ability to function as a buffer for the water course s ecological health and as a natural area. First, staff notes that the applicant conducted an alternatives analysis to examine relocating the facility to a different site but was unable to relocate the facility. Second, the existing substation was built in 1953 and the neighboring building and parking were also built in the 1950s, prior to the Commission s jurisdiction and the stream corridor regulations. The project will reduce the existing impervious by approximately 0.23 acres. Third, the applicant notes other environmental benefits of the project at this site. The applicant will remove existing structures from inside the floodway and flood fringe areas. Systems will be upgraded and equipment will be raised above the highest flood elevation to ensure continued reliable operation in the future and the project has received approval from the DEP Flood Hazard program. Also, the project will eliminate vehicular traffic and the outside storage of vehicles. Specifically, Lot 43 contains a building which was used for cleaning cars, and parking which was used for the driving and storage of cars outside. With the new project, the travel surfaces between both lots will be reduced, with 0.53 acres of asphalt and concrete areas being eliminated. The substation will not be staffed and there will be approximately one visit per week for equipment and property maintenance. Lastly, stormwater treatment will be provided for the site where no treatment is presently provided.

4 4 The pervious area on the site will be approximately 42,793 square feet. PSEG will place the 42,793 square feet of pervious area on the project site in a Commission stream corridor conservation easement. PSEG has requested that the easement include permitted uses in the corridor including maintenance of the vegetated filter strip, planting with native plants along Prospect Street and a lawn area adjacent to the substation. The lawn area is for a zone of safety around the substation in keeping with policies at all substations and the planting beds and lawn in the front of the property, along Prospect Street, are required by the township for their designated redevelopment area. PSEG notes that the native plants in the front will replace lawn and that the overall lawn area will be reduced by 16,618 square feet and the naturally vegetated areas, which will not be maintained, will increase from 8,225 square feet to 20,292 square feet. The beds will contain native plantings consistent with the DEP and Commission native planting lists. The stream corridor easement will preserve the pervious areas on the site. The Commission s standard easement form allows for the listing of permitted uses, and similar uses and conditions have been allowed in past agreements. It is staff s opinion that the project meets the stream corridor waiver standards of N.J.A.C. 7: (a)1. Stormwater Runoff Quantity: The majority of the site drains to the south and east and enters the existing storm sewer collection system located in Prospect Street, which ultimately drains to the West Branch of the Shabakunk Creek. The applicant has evaluated changes in land use and the pre- and post-construction stormwater conditions at the project site at Point of Analysis #1, located at the westerly corner of the property. The submitted hydrologic and hydraulic calculations demonstrate that, for stormwater leaving the site off the eastern drainage area, post-construction runoff hydrographs for the two, 10, and 100-year storm events do not exceed, at any point in time, the preconstruction runoff hydrographs for the same storm events. As a note, because of the proposed project, impervious coverage areas onsite will be reduced from the existing condition. The submitted calculations utilized the Natural Resource Conservation Service (NRCS) Technical Release No. 55 (TR-55) hydrologic methodology, Standard unit hydrograph rainfall distribution and current New Jersey 24-hour rainfall frequency data for Mercer County to compute peak runoff flow rates and volumes. Based upon a review of the modeling results, the proposed project will result in a reduction in both the quantity of runoff flow and volume. Therefore, the proposed project will meet the specific runoff quantity standards of N.J.A.C. 7:45-8.6(a)2. Water Quality: The Commission requires that all proposed travel gravel surfaces and full depth pavement, including newly and reconstructed parking and access drives that are being renewed, must meet water quality standards in accordance with Commission regulations (N.J.A.C. 7:45-8.7). This includes reduction of the post-construction load of total suspended solids (TSS) in stormwater runoff generated from the water quality design storm by a rate of 80% of the anticipated load from the developed site, expressed as an annual average. Based upon the submitted application, new gravel access drives and a concrete driveway apron are being proposed onsite. The submitted stormwater report notes that the design proposes to treat for water quality by incorporating a combination of best management practice (BMP) measures in series, including a vegetative filter strip followed by a linear inflow grass swale. The proposed vegetative

5 5 filter strip will be planted with turf grass cover at an 85% minimum density of vegetation to achieve a 60% TSS removal rate. The linear inflow grass swale will exceed 200 linear feet and achieve a 50% TSS removal rate. In series as a treatment train, these BMP measures will achieve an 80% TSS removal rate for the project. It should also be noted that the proposed substation is expected to be a low pollutant area due to the minimal activity on the site during operation, with vehicular traffic at the substation consisting of intermittent maintenance vehicles with no full-time employee onsite. As such, stormwater quality measures have been designed in accordance with the requirements of N.J.A.C. 7: Groundwater Recharge: The Commission regulations require that stormwater management measures maintain 100% of the average annual preconstruction groundwater recharge volume for the site; or that any increase of stormwater runoff volume from preconstruction to post-construction for the 2-year storm is infiltrated. Based upon a review of the results of the stormwater calculations, there will not be any increase of stormwater runoff volume from preconstruction to post-construction for the 2- year storm. The main reason for this is that the impervious coverage areas onsite will be reduced from the existing conditions. Therefore, the groundwater recharge requirements of N.J.A.C. 7: have been addressed. Nonstructural Methods: To assist in determining that sufficient nonstructural stormwater management strategies have been incorporated into the project site design to the maximum extent practical, the Nonstructural Strategies Point System (NSPS) spreadsheet has been completed for this project. The results indicate that the ratio of proposed to existing site points (251%) is greater than the required site points ratio (69%). The project is therefore designed in accordance with N.J.A.C. 7: Stormwater Management Maintenance Plan: A stormwater management operation and maintenance plan document has been prepared and submitted for the best management practice (BMP) elements proposed for the PSEG Ewing Substation project. The plan includes maintenance details for the proposed vegetative filter strip and linear inflow grass swale. The plan has been prepared in accordance with the requirements of N.J.A.C. 7: Staff Recommendation: Staff recommends approval. Sincerely, Marlene Dooley Executive Director c: Ewing Township Planning Board Mercer County Planning Board