POST CONSTRUCTION STORMWATER MANAGEMENT REPORT Adelphia Gateway Project Tilghman Lateral Phase 2B
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POST CONSTRUCTION STORMWATER MANAGEMENT REPORT Adelphia Gateway Project Tilghman Lateral Phase 2B Submitted to: September 2020 Pennsylvania Department of Environmental Protection (PADEP) POST CONSTRUCTION STORMWATER MANAGEMENT REPORT TABLE OF CONTENTS I. PLAN PREPARER CREDENTIALS..............................................................................................2 II. PCSM PLANNING AND DESIGN ................................................................................................2 III. SOIL CHARACTERISTICS ...........................................................................................................3 IV. EXISTING TOPOGRAPHIC FEATURES OF THE PROJECT SITE AND THE IMMEDIATE SURROUNDING AREA.................................................................................................................3 V. SURFACE WATER CLASSIFICATIONS .....................................................................................4 VI. NARRATIVE DESCRIPTION OF THE LOCATION AND TYPE OF ON-SITE BMPS ............4 VII. VOLUME REDUCTION AND WATER QUALITY REQUIREMENTS .....................................5 VIII. RATE REQUIREMENTS ...............................................................................................................7 IX. GEOLOGIC FORMATIONS OR SOIL CONDITIONS ................................................................7 X. POTENTIAL THERMAL IMPACTS TO SURFACE WATERS ..................................................8 XI. EXISTING/PROPOSED RIPARIAN FOREST BUFFERS ...........................................................8 XII. ANTIDEGRADATION REQUIREMENTS ...................................................................................8 XIII. CONSTRUCTION SEQUENCE .....................................................................................................8 XIV. LONG-TERM MAINTENANCE SCHEDULE ............................................................................11 XV. OFF-SITE DRAINAGE ANALYSIS ............................................................................................11 APPENDICES A. LOCATION MAP B. SOIL DATA 1. SOIL MAP 2. SOIL MAP UNIT DESCRIPTION 3. SOIL USE LIMITATIONS AND RESOLUTIONS C. CHAPTER 102 COMPLIANCE D. STORMWATER MANAGEMENT CALCULATIONS 1. BMP WORKSHEETS 2. BMP COMPUTATIONS - EXISTING CONDITIONS 3. BMP COMPUTATIONS – PROPOSED CONDITIONS E. DRAINAGE AREAS PLANS F. INFILTRATION TESTING REPORTS 1 I. PLAN PREPARER CREDENTIALS The PCSM plan was prepared by Shiny Mathew, P.E. She is a Professional Engineer and a graduate of Widener University with a Bachelor of Science in Civil Engineering. Mrs. Mathew has been designing project of similar size and scale for 14 years throughout Southeastern PA. She has delivered projects for several public and private clients. Her project experience includes American Street Improvement Project (Philadelphia), Bakers Centre Development (Philadelphia), SEPTA Jenkintown Stream Restoration (Montgomery Co), and Radnor High School Bus Loop Improvements (Delaware Co.). II. PCSM PLANNING AND DESIGN Johnson, Mirmiran & Thompson (JMT), on behalf of Adelphia Gateway, has prepared this Post Construction Stormwater Management (PCSM) Plan for the Adelphia Gateway Pipeline. The PCSM Plan has been designed in accordance with the criteria stated in the Pennsylvania Department of Environmental Protection (PADEP) Stormwater Best Management Practices Manual, dated December 2006; Pennsylvania Department of Environmental Protection (PADEP), Bureau of Waterways Engineering and Wetlands Erosion and Sediment Pollution Control Program Manual, dated March 2012, thus satisfying requirements for PADEP General Permit (ESCGP-3) for Earth Disturbance Associated with Oil and Gas Exploration, Production, Processing, or Treatment Operations or Transmission Facilities contained under Pa. Code Title 25 Chapter 102. The Adelphia Gateway Pipeline is an 84-mile pipeline that runs from Martins Creek to Marcus Hook. Facility upgrades will occur to thirteen (13) sites along the pipeline: Quakertown Compressor Station, East Perkiomen Blowdown, Skippack Pike Valve Site, Perkiomen Creek Blowdown, Schuylkill River Blowdown, Cromby Blowdown, French Creek Blowdown, Mainline Valve 2, Paoli Pike Blowdown, Chester Creek Blowdown, Mainline Valve 1, Transco Meter Station, and Marcus Hook Compressor and Meter Station. The total limit of disturbance is 13.9 acres. The Tilghman and Parkway lateral, known as Phase 2A consists of 1,925 LF of proposed pipeline between the Delaware State Line/Marcus Hook Compressor and Meter Station and Transco Meter Station. It is to be installed through traditional open cut installation and horizontal direction drill (HDD) installation methods. The limit of disturbance within Phase 2A is 0.15 acres. The Tilghman lateral pipeline, known as Phase 2B, consists of approximately 4.4 miles of proposed 16-inch O.D. pipeline. The installation consists of open cut for approximately 0.6 miles and horizontal directional drill (HDD) for approximately 3.8 miles. The total limit of disturbance is 24.76 acres. However, only 1.3 acres is open cut trench. The remaining pipe installation is to be completed using HDD, minimizing surface disturbance. The remaining area included in the LOD is temporary workspace intended for parking, staging materials and equipment, and stockpiling. Mechanical piping and two buildings are proposed at the PECO Meter Station where the Tilghman Lateral ends. 2 The entire limit of disturbance for the Tilghman Lateral section will be restored to existing conditions and site restoration and PCSM devices (two dry wells) are proposed at the PECO Meter Station. This narrative describes the PCSM measures of Adelphia Gateway Pipeline Phase 2B and related site work. This narrative applies to the PCSM activities for Phase 2B only. Phase 1 and 2A were submitted to DEP under a separate application. III. SOIL CHARACTERISTICS Table III-1 below detail the types of soils, as contained within the Stormwater Management areas, for each of the thirteen sites, as defined by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Web Soil Survey. Table III-1: Soil Types within LOD Symbol Map Unit Name Brief Map Unit Description ByB2 Butlertown silt loam, 3 to 8 Soil Rating C, slow infiltration rate when thoroughly wet. percent slopes Mainly soils with layer that impedes downward movement of water or soils of fine texture. Slow rate of water transmission. Ma Made land, gravelly Soil Rating A, high infiltration rate when thoroughly wet. materials Mainly deep, well drained sands or gravelly sands. High rate of water transmission. OtA Othello silt loams, 0 to 2 Soil Rating C/D, very slow infiltration rate when thoroughly percent slopes wet. Mainly clays, high water table soils, claypan or clay layer at or near surface, and shallow soils over nearly impervious material. Very slow rate of water transmission. We Wehadkee silt loam Soil Rating D, very slow infiltration rate when thoroughly wet. Mainly clays, high water table soils, claypan or clay later at or near surface, and shallow soils over nearly impervious material. Very slow rate of water transmission. The Hydrologic Soil Group Rating Report from USDA NRCS Web Soil Survey, which includes a soil map, the physical properties of the soils, and the soil use limitations and resolutions is provided for each site in Appendix B. IV. EXISTING TOPOGRAPHIC FEATURES OF THE PROJECT SITE AND THE IMMEDIATE SURROUNDING AREA USGS quadrangle location maps are provided in Appendix A, which shows the location of the project site and the surrounding area. 3 The limit of disturbance is primarily roadway (SR 3006, SR 291, Flower Street and Delaware Ave), which was constructed well over 5 years ago. The remaining section of disturbance is land adjacent and through industrial sites. Soil infiltration testing at PECO Meter Station was performed on July 24, 2020 using the Double Ring Infiltration Test method. Two (2) test infiltration tests were performed at the dry well bottom elevation. The infiltration testing resulted in infiltration rates of 1.00 and 1.25 in/hr, respectively. Both infiltration test pits demonstrated sandy silt at the testing depth with no limiting layers, such as impervious clay, bedrock, or groundwater. Based on the findings, infiltration was recommended at this site. V. SURFACE WATER CLASSIFICATIONS Table V-1 below details the three (3) watersheds in which the project site is located within, as well as the receiving surface waters classification, as defined by the Pennsylvania Department of Environmental Protection (PADEP) Title 25, Chapter 93: Water Quality Standards. Note the following acronyms: WWF (Warm Water Fishes), and MF (Migratory Fishes). Table V-1: Receiving Surface waters Classification Watershed Chapter 93 Classification Marcus Hook Creek WWF, MF, siltation-impaired Stoney Creek WWF, MF Delaware River WWF, MF VI. NARRATIVE DESCRIPTION OF THE LOCATION AND TYPE OF ON-SITE BMPS The following Best Management Practices (BMP), in accordance with Pennsylvania Stormwater BMP Manual, dated December 2006, have been integrated into the design to reduce runoff volume, reduce peak rates and improve water quality. These structural BMPs will result in the prevention or minimization of increased stormwater runoff rate, volume and/or changes in stormwater runoff. Implementing these controls will preserve the integrity of stream channels and maintain and protect the physical, biological and chemical qualities of the receiving stream. The limit of disturbance