Review Zone Application for D&R Canal Commission Decision

Transcription

1 Review Zone Application for D&R Canal Commission Decision MEETING DATE: December 21, 2016 DRCC #: Latest Submission Received: December 7, 2016 Applicant: Robert McCarthy, PE PSE&G 4000 Hadley Road, 2 nd Floor Mail Code 430 South Plainfield, NJ Engineer: Jared Augustine, PE Burns & McDonnell 9400 Ward Parkway Kansas City, MO Project Location: Road Municipality County Block(s) Lot(s) 60 Bunker Hill Road Lawrence Twp Mercer , 40 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: Revised Stream Corridor Map sent via from Robert McCarthy (1 page) dated December 7, 2016; Letters from Robert McCarthy, PE, (6 pages) dated November 18, 2016, (2 pages) dated September 26, 2016, and (3 pages) dated July 22, 2016; Project and Site Description Report, dated July 2016, and Landscape Plan and Details dated December 10, 2015, revised July 19, 2016, prepared by DW Smith Associates, LLC; Existing Conditions Survey (1 sheet) dated January 7, 2016, Site Plan (1 sheet) dated December 10, 2015, DRCC Stream Corridor Exhibit (1 sheet) dated July 13, 2016, last revised November 17, 2016, DRCC Stream Corridor Easement Exhibit (1 sheet) dated July 13, 2016, revised November 17, 2016, DRCC Gravel Area Exhibit (1 sheet) dated July 20, 2016, prepared by PSEG Services Corporation; Drawings dated September 10, 2015, signed July 19, 2016 (10 sheets), Stormwater Management Plan, last revised September 7, 2016, and Stormwater Maintenance Plan & Field Manuals, last revised July 8, 2016, prepared by Burns & McDonnell; Aerial Map (1 page) dated 1979; PSEG Location of Easements Map (1 page) dated December 31, 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 December 21, 2016 meeting, based upon the following analysis: Existing Conditions: This existing acre property is located along Bunker Hill Road between Anthony Lane and Stewarts Crossing Way within the Township of Lawrence, Mercer County, and within the Commission Review Zone B. The project site is bounded by single-family residential developments to the northeast, south and west and undeveloped wooded wetland areas to the northeast and east. The property site is developed as part of the existing Public Service Electric and Gas Company (PSE&G) Lawrence Switching Station. The existing property is a combination of woods, brush, grass, wetlands and gravel and asphalt paved surfacing where the current station infrastructure is located. A comparison of 2012 and 2013 historic aerials confirm a placement of gravel areas throughout the site including within the defined Commission stream corridor buffer area. These areas were previously developed without providing stormwater management. These include a total of 1.37 acres of impervious area, or more specifically 0.19 acres for a 230kV voltage regulatory project, 0.52 acres for a capacitor bank project, 0.25 acres for a gravel area for parking temporary construction trailers, and 0.41 acres for a second gravel area for parking temporary construction trailers. The Lawrence Switching Station provides electrical service to customers in Lawrence Township and surrounding municipalities in Mercer County. Proposed Project: The applicant is proposing to upgrade the Lawrence Switching Station as 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. The upgrades will involve the expansion of the existing station footprint and the installation of twelve 69kV circuit breakers, eight 69kV line positions, new bus support structures, disconnects, lightning protection, a 22-feet by 49-feet control house, a monopole, site lighting, new paved and compacted gravel access roads, gravel yard cover, security fencing, a storm water management basin and extensive landscaping. The proposed project will result in a net increase in impervious surface area coverage of approximately 1.54 acres. The proposed project shall result in an area of disturbance of approximately 5.13 acres. The applicant will also provide stormwater management for the 1.37 acres of impervious area previously placed for the capacitor bank project, parking and trailers referenced above. Stream Corridor: The project site is located within the Assunpink Creek watershed area. A tributary to Little Shabakunk Creek is located directly on the project site. Although the currently proposed expansion project and stormwater management basin are not located within the stream corridor of the tributary of the Little Shabakunk Creek, prior projects without prior Commission approval have resulted in the placement of gravel within the stream corridor. As such, the current project is subject to a stream corridor impact review. A 100-year floodplain and 100-foot buffer have been provided on the submitted plans. As part of a prior NJDEP land use regulation approval for a capacitor bank, PSE&G received verification of the 100-year flood limit line of the Little Shabakunk Creek

3 3 tributary. The Commission stream corridor buffer, or 100-foot offset of the 100-year floodplain, has been delineated properly. The stream corridor is approximately 6.5 acres. The stream corridor contains electrical equipment, concrete pads, utility poles, fences, overhead lines, and gravel. 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. Of the approximately 6.5- acre stream corridor, approximately 4.4 acres have existing intrusions that occurred prior to the Commission s jurisdiction and the establishment of the stream corridor regulations. Specifically, approximately 0.8 acres is a portion of the substation containing a gravel yard, electrical equipment, concrete pads, control structures and overhead electrical wires which were placed prior to In addition, there is an approximately 3.6-acre area which is the subject of a 1961 easement with JCP&L and contains overhead transmission lines with transmission towers and an adjacent mowed right-of-way (R.O.W.). Lastly, the area contains an overhead and underground distribution line with 15 feet of clearance on either side and a security fence with an 8-foot adjacent mowed area. It is staff s opinion that these intrusions are grandfathered and the project will not adversely affect the buffer and that the requirements of N.J.A.C. 7: (a)1 have been met. The remaining approximately 2-acre area will be preserved and allowed to revert to a natural state. In addition, there is approximately 6,410 square feet of gravel from an expansion of the facility within the past five years. The applicant notes that gravel was not regulated as an impervious surface prior to 2009 and that this gravel was placed in error. As noted below, the proposed stormwater basin will address stormwater runoff for this area. The applicant will remove approximately 800 square feet of this existing gravel. However, due to existing overhead lines and pipes, the applicant seeks to periodically mow the area in keeping with PSE&G safety and BPU requirements. In addition, the remaining square footage is part of the capacitor bank and cannot be removed. Therefore, the applicant is seeking a waiver pursuant to N.J.A.C. 7: (a)2. Specifically, the applicant will preserve an additional 19,658 square foot area adjacent to the stream corridor. It is staff s opinion that preserving this similar area at a ratio of greater than 1:1 meets the standard. The applicant will preserve a total of 2.45 acres of stream corridor and place monuments to ensure that the area is not mowed and is allowed to revert to its natural state. Stormwater Runoff Quantity: The applicant is proposing an increase of impervious area that will increase runoff as compared to the existing conditions. In addition, in order to compensate for 1.37 acres of previously developed land onsite, the current project will provide stormwater management measures for an additional 1.69 acres of impervious area. In order to mitigate for current and previous impervious areas, the applicant proposes to control stormwater runoff flow and volume through the construction of a new wet pond/retention basin. The proposed wet pond, which will be excavated earth and

4 4 vegetated with a grass bottom underlain by a PVC liner, will be located along the southern portion of the site. The stormwater management measures have been designed so that the post-construction peak runoff rates for the two, 10 and 100-year storm events will be no greater than 50%, 75% and 80%, respectively, of the preconstruction peak runoff rates. The submitted calculations utilized the Natural Resource Conservation Service (NRCS) Technical Release No. 55 (TR-55) hydrologic methodology, Standard unit hydrograph rainfall distribution (Type III) and current New Jersey 24-hour rainfall frequency data for Mercer County to compute peak runoff flow rates and volumes. Therefore, the proposed stormwater management measures will provide enough peak flow attenuation to meet the specific runoff quantity standards of N.J.A.C. 7:45-8.6(a)1. 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. New asphalt pavement and gravel access drive surfaces are being proposed onsite. The applicant notes that the design proposes to treat for water quality by incorporating an aboveground wet pond/retention basin. The proposed wet pond has been designed in accordance with the design criteria within the NJ Stormwater Best Management Practices (BMP) Manual, to reduce the post construction TSS loading by 80%. In addition, the proposed substation will be a low pollutant load area due to the minimally expected activity on the site as regular operation. 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 two-year storm is infiltrated. Subsurface geotechnical investigations of the project site have revealed that the existing soils onsite are highly resistant to recharge, exhibiting the characteristics of Hydrologic Group D type soils. Therefore, since the existing soils do not currently provide recharge, the groundwater recharge requirements of N.J.A.C. 7: can be considered to be addressed. Nonstructural Methods: The Commission requires that nonstructural stormwater management strategies be incorporated into the stormwater design of a development project. To assist in determining that sufficient nonstructural stormwater management strategies have been incorporated into the project site design to the maximum extent practical, a Nonstructural Strategies Point System (NSPS) spreadsheet has been completed for this project. The results indicate that the ratio of proposed to existing site points (97%) is greater than the required site points ratio (87%). Therefore, the project is 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

5 5 management practice (BMP) elements proposed for the PSE&G Lawrence Switching Station 69kV Expansion project. The plan includes maintenance details for the proposed aboveground stormwater wet pond/retention basin and 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: Lawrence Township Planning Board Mercer County Planning Board