DES Waste Management Division 29 Hazen Drive; PO Box 95 Concord, NH 03302-0095 Work Plan for 2018 Stormwater and Surface Water Investigation Saint-Gobain Performance Plastics 701 Daniel Webster Highway Merrimack, New Hampshire 03054 NHDES Site No.: 199712055 Project Number: 36430 Prepared For: Saint-Gobain Performance Plastics Corp. 14 McCaffrey Street Hoosick Falls, New York 12090 Phone Number (518) 686-6268 RP Contact Name: Chris Angier RP Contact Email: [email protected] Prepared By: Golder Associates Inc. 670 North Commercial Street Manchester, New Hampshire 03101 Phone Number: (603) 688-0880 Contact Name: Ross Bennett Contact Email: [email protected] Date of Report: March 30, 2018 Cover Sheet for Reports Template - Revised January 2011 WORK PLAN FOR 2018 STORMWATER AND SURFACE WATER INVESTIGATION SAINT-GOBAIN PERFORMANCE PLASTICS MERRIMACK, NEW HAMPSHIRE Submitted To: New Hampshire Department of Environmental Services Hazardous Waste Remediation Bureau 29 Hazen Drive, PO Box 95 Concord, New Hampshire 03302 Submitted By: Saint-Gobain Performance Plastics Corp. 14 McCaffrey Street Hoosick Falls, New York 12090 WORK PLAN WORK Prepared By: Golder Associates Inc. 670 North Commercial Street, Suite 103 Manchester, NH 03101 USA March 30, 2018 Project No.: 166-8623 A world of capabilities delivered locally Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation March 2018 i Project No.: 166-8623 Table of Contents 1.0 INTRODUCTION .............................................................................................................................. 1 2.0 BACKGROUND ............................................................................................................................... 2 2.1 Overview of Facility and Stormwater Conveyance System ......................................................... 2 2.2 NHDES Outfall Sample Collection and Request for Work Plan ................................................... 3 2.2.1 Outfall Sample Collection and Request for Work Plan ............................................................ 3 2.2.2 Stormwater and Surface Water Investigation and Summary Report ....................................... 3 2.2.3 NHDES Comments on the StW-SW ISR ................................................................................. 4 2.2.4 Preliminary Conceptual Model ................................................................................................. 4 3.0 INVESTIGATION OBJECTIVES AND SCOPE OF WORK ............................................................. 7 3.1 Investigation Objectives ............................................................................................................... 7 3.2 Stormwater Conveyance System - Wet-Weather Flow ............................................................... 7 3.2.1 Wet-Weather Flow Source Evaluation ..................................................................................... 7 3.2.2 Triannual Wet-Weather Sampling ............................................................................................ 8 3.2.3 Stormwater Flow Rate and Rain Gauge Monitoring ................................................................ 9 3.2.4 Dye Testing .............................................................................................................................. 9 3.3 Dumpling Brook .......................................................................................................................... 10 3.3.1 Weir and Data Logger Installation.......................................................................................... 10 3.3.2 Triannual Wet-Weather and Dry-Weather Sampling ............................................................. 10 3.3.3 Sediment Sampling ................................................................................................................ 11 3.4 Unnamed Brook North of the Plant ............................................................................................ 12 4.0 STORMWATER CONVEYANCE SYSTEM - DRY-WEATHER FLOW ......................................... 13 4.1.1 Stormwater Conveyance System Maintenance ..................................................................... 13 4.1.2 Post Stormwater Conveyance System Maintenance Monitoring ........................................... 13 4.1.3 Post-maintenance Dry-Weather Flow Sampling .................................................................... 14 4.2 Additional Maintenance Activities .............................................................................................. 14 5.0 STORMWATER AND SURFACE WATER SAMPLING PROCEDURES ...................................... 16 6.0 NEXT STEPS AND SCHEDULE ................................................................................................... 17 7.0 CLOSING ....................................................................................................................................... 18 8.0 REFERENCES ............................................................................................................................... 19 List of Tables Table 1 Stormwater Conveyance System Source Evaluation Sample Locations Table 2 PFAS Analyte List Table 3 Stormwater Conveyance System and Merrimack River Wet-Weather Sample Locations Table 4 Dumpling Brook Dry- And Wet-Weather Sample Locations Table 5 Unnamed Brook Dry- And Wet-Weather Sample Locations Table 6 Stormwater Conveyance System Observation Locations Table 7 Stormwater Conveyance System Dry-Weather Flow Sample Locations \\man1-v-fs1\confidential\1668623 sgpp merrimack\700 reports-deliv\8 - stw-sw inv wp march 2018\final\final stw-sw work plan.docx March 2018 ii Project No.: 166-8623 List of Figures Figure 1 Facility Location Map Figure 2 Facility Plan and Stormwater Conveyance System Layout Figure 3 Stormwater Conveyance System Sampling Locations Figure 4 Facility, Merrimack River, Dumpling Brook, and Unnamed Brook Sampling Locations Figure 5 Location of Upstream Sediment Sample Figure 6 Locations of Proposed Stormwater Conveyance System Spot Lining and Grouting List of Appendices Appendix A A-1 NHDES Comments dated March 14, 2018 A-2 SGPP Response to NHDES Comments dated March 14, 2018 Appendix B SOP-1: General Field Methods for PFAS Sampling Programs Appendix C SOP-2: PFAS Program Sampling Protocols Appendix D SOP-3: QA/QC Sampling Program Protocols Appendix E SOP-4: PFAS Sediment Sampling Protocols \\man1-v-fs1\confidential\1668623 sgpp merrimack\700 reports-deliv\8 - stw-sw inv wp march 2018\final\final stw-sw work plan.docx March 2018 1 Project No.: 166-8623 1.0 INTRODUCTION Golder Associates Inc. (Golder), on behalf of Saint-Gobain Performance Plastics (SGPP), submitted a Stormwater and Surface Water Investigation Summary Report (StW-SW ISR; Golder, 2018) for the Merrimack, New Hampshire SGPP facility (the facility, see Figure 1) to the New Hampshire Department of Environmental Services (NHDES) on January 30, 2018. Representatives of SGPP, Golder and NHDES met on February 22, 2018 to discuss the findings of the StW-SW ISR and the scope of proposed additional stormwater and surface water investigation activities. NHDES issued written comments on the StW-SW ISR on March 14, 2018 (NHDES, 2018). A copy of NHDES comments and SGPP’s responses are proved in Appendices A-1 and A-2, respectively. This work plan outlines the objectives and proposed scope of work for additional investigation of stormwater at the facility as well as surface water in the Merrimack River located east and south of the facility, Dumpling Brook located south of the facility, and an unnamed brook located north of the facility. The 2018 StW/SW investigation objectives do not include objectives to address the data gaps identified for dry-weather flow in the StW-SW ISR. SGPP will implement stormwater conveyance system maintenance (spot lining and grouting) of targeted potions of the stormwater conveyance system to reduce or eliminate dry weather flow. Additional dry-weather flow sampling will be implemented as part of performance monitoring if dry-weather flow is observed after implementation of stormwater conveyance system maintenance activities. Stormwater conveyance system maintenance activities, and post-maintenance monitoring relative to dry-weather flow are presented in Section 4. This work plan includes the following: Background information on the facility, the facility’s stormwater conveyance system, past stormwater and surface water investigations, and communications between SGPP and the NHDES Objectives and scope of work for investigation of stormwater and surface water Stormwater conveyance system maintenance activities to address dry-weather flow and post-maintenance monitoring activities A discussion of next-steps and schedule \\man1-v-fs1\confidential\1668623 sgpp merrimack\700 reports-deliv\8 - stw-sw inv wp march 2018\final\final stw-sw work plan.docx March 2018 2 Project No.: 166-8623 2.0 BACKGROUND This section describes the facility, its stormwater conveyance system, and past stormwater/surface water investigation activities. It also summarizes communications between SGPP and the NHDES regarding the StW-SW ISR’s findings, and a preliminary conceptual model to inform data gaps, which provide the basis for the scope of work presented in this work plan. 2.1 Overview of Facility and Stormwater Conveyance System The following description of the facility’s stormwater conveyance system is based on a review of readily available