Loading...
HomeMy WebLinkAbout2020.09.30_CCOA.p4b_StormwaterSamplingPlan STORMWATER TREATMENT SYSTEM SAMPLING PLAN Chemours Fayetteville Works Prepared for The Chemours Company FC, LLC 22828 NC Highway 87 Fayetteville, NC 28306 Prepared by Geosyntec Consultants of NC, P.C. 2501 Blue Ridge Road, Suite 430 Raleigh, NC 27607 Project Number TR0795 September 2020 DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC 9/30/2020 SW Sampling Plan_20200930 ii September 2020 TABLE OF CONTENTS 1 INTRODUCTION ................................................................................................ 1 2 TREATMENT SYSTEM DESCRIPTION .......................................................... 1 3 SCOPE OF WORK............................................................................................... 2 3.1 Sampling Schedule ...................................................................................... 2 3.2 Sample Types and Locations ....................................................................... 3 3.3 Flow Measurement Scope ........................................................................... 3 3.4 Associated Data Recording Scope ............................................................... 3 4 METHODS ........................................................................................................... 3 4.1 Sample Collection........................................................................................ 3 4.2 Equipment Decontamination ....................................................................... 4 4.3 Flow Measurement Methods ....................................................................... 4 4.4 Field QA/QC Samples ................................................................................. 4 4.5 Sample Packing and Shipping ..................................................................... 5 5 CALCULATIONS ................................................................................................ 6 6 REPORTING ........................................................................................................ 7 7 POTENTIAL ADJUSTMENTS ........................................................................... 8 8 REFERENCES ..................................................................................................... 9 DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 iii September 2020 LIST OF TABLES Table 1: Sampling and Analysis LIST OF FIGURES Figure 1: Proposed Stormwater Treatment System Location DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 v September 2020 LIST OF ABBREVIATIONS CO Consent Order EQ equalization GAC granular activated carbon gpm gallons per minute HFPO-DA hexafluoropropylene oxide dimer acid IX ion exchange ng/L nanograms per liter NCCW non-contact cooling water NCDEQ North Carolina Department of Environmental Quality NPDES National Pollutant Discharge Elimination System O&M operation and maintenance PFAS per- and polyfluoroalkyl substances PFMOAA 2,2-difluoro-2-(trifluoromethoxy) acetic acid PMPA perfluoromethoxypropyl carboxylic acid QAPP Quality Assurance Project Plan QA/QC quality assurance/quality control SOP standard operating procedure TSS total suspended solids USGS United States Geological Survey DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 1 September 2020 1 INTRODUCTION Geosyntec Consultants of NC, PC (Geosyntec) has prepared this Stormwater Treatment System Sampling Plan (“Sampling Plan”) on behalf of The Chemours Company FC, LLC (Chemours) pursuant to the requirements of Paragraph 4(b) of the Addendum to Consent Order Paragraph 12 (CO Addendum). This paragraph requires that Chemours submit a stormwater sampling plan to quantify the effectiveness of the stormwater capture and treatment system (Treatment System), as measured by concentrations of indicator parameters hexafluoropropylene oxide dimer acid (HFPO-DA), perfluoromethoxypropyl carboxylic acid (PMPA), and 2,2-difluoro-2-(trifluoromethoxy) acetic acid (PFMOAA). The CO Addendum specifies that Chemours shall install and operate a system that captures and treats stormwater from the area (by June 30, 2021, as noted in Paragraph 4[a]). Implementation of this Sampling Plan is intended to achieve the following objectives: • Characterize the stormwater influent to the Treatment System (flow and concentration); • Characterize the stormwater effluent from the Treatment System (concentration); and • Assess the Treatment System PFAS removal efficiency for comparison to the CO Addendum requirement of 99% removal. 2 TREATMENT SYSTEM DESCRIPTION The Treatment System will treat stormwater runoff from 11.8 acres within the area shown on Attachment 6 of the CO Addendum for per- and polyfluoroalkyl substances (PFAS) and is planned to be installed adjacent to the cooling water channel. As of September 2020, the Treatment System design and vendor selection are ongoing. Stormwater will be captured, collected, and transferred to an equalization (EQ) Tank. The diversion system, pump, EQ Tank, and Treatment System will be collectively sized to capture stormwater runoff from the North Carolina Department of Environmental Quality (NCDEQ) 1-inch, 24-hour design storm (as reflected in NCDEQ stormwater permits and as implemented in NCDEQ’s statewide Stormwater Design Manual) from the drainage area shown in Figure 1. A design storm is a hypothetical discrete rainstorm (in this case, characterized by a specific rainfall depth of 1 inch and 24 hours of duration) that is used in the design of a stormwater control measure. Sizing a stormwater control measure involves calculating the volume of runoff resulting from the specified design storm, that will drain to the control measure. Therefore, the Treatment System will be sized to capture and treat runoff DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 2 September 2020 equivalent to the design storm volume. The Treatment System will not necessarily capture and treat all runoff from larger storms or a series of storm events that occur in close proximity to each other, including successive 1 inch in 24-hour storm events. The Treatment System will treat the collected stormwater in the EQ Tank, up to the design flowrate, to achieve the effluent targets for the indicator parameters HFPO-DA, PMPA, and PFMOAA. The Treatment System will use granular activated carbon (GAC) to remove PFAS but may include features for other treatment also. For storm events larger than the design storm, stormwater flows that bypass the in-line diversion structure to the Treatment System will combine (untreated) stormwater with non-contact cooling water (NCCW) in the cooling water channel that flows to Outfall 002. The Treatment System will also potentially include the following: (i) prefiltration to remove total suspended solids (TSS), turbidity, and other constituents that clog and potentially reduce PFAS removal by downstream unit operations; (ii) settling tanks and solids handling system for the backwash waste from the prefiltration system (including chemical dosing skids); and (iii) a post-filtration system to remove GAC fines. 3 SCOPE OF WORK This Sampling Plan addresses the need to characterize stormwater influent to and effluent from the Treatment System and assess its effectiveness in removing indicator PFAS. This scope of work involves collecting influent and effluent samples from the Treatment System during rain events when the Treatment System is treating stormwater. The sampling scope and schedule presented herein may be modified based on changes in Site conditions, adjustments in understanding of Site conditions, or potential sampling requirements in future permits such as a National Pollutant Discharge Elimination System (NPDES) permit. 3.1 Sampling Schedule Sampling will be performed during wet weather, when the Treatment System is discharging treated stormwater from the drainage area. For the first two months after the Treatment System begins operating, sampling will be conducted up to four times per month. Following the first two months of operation, sampling will be conducted up to twice per month. The ability to collect samples will depend on the occurrence of rainfall events of sufficient volume to enable sampling. Sampling events in a given month are intended to occur at least three days apart. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 3 September 2020 3.2 Sample Types and Locations Time-weighted composite samples will be collected from the influent and the effluent to the Treatment System and each will be analyzed for HFPO-DA, PMPA, and PFMOAA. This is summarized in Table 1. 3.3 Flow Measurement Scope Continuous flow measurements at appropriate time intervals (e.g., 5 or 15 minute) will be taken from the influent (discharge from the EQ Tank) and water levels will be measured in the EQ Tank during every sampling event. This is summarized in Table 1. Flow measurements will also be taken to measure any stormwater flow that bypasses the Treatment System. 3.4 Associated Data Recording Scope The following types of data will be recorded during Treatment System operation: • Precipitation during a given evaluation period will be monitored by using either the existing United States Geological Survey (USGS) weather monitoring station at the W.O. Huske Dam (gage 02105500) or the onsite meteorological station; • Total stormwater volume treated by the stormwater Treatment System; • Total stormwater volume bypassing the system; • Capacity of EQ Tank throughout the evaluation period; and • Other recorded field data or observations. 4 METHODS This section describes the field methods and specific procedures for collecting samples and field measurements. 4.1 Sample Collection Influent and effluent samples will be collected as time-weighted composite samples using autosamplers. Samples will be collected from subsamples collected every two hours. Collection will continue for a total of three subsamples or the duration of a storm, whichever occurs first. For all samples, care will be taken to avoid collecting settled/bed sediment or other materials which may be potentially present in the sample. Other relevant sampling procedure information can be found in the Poly and Perfluoroalkyl Substance Quality Assurance Project Plan (AECOM, 2018). DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 4 September 2020 4.2 Equipment Decontamination All non-dedicated or non-disposable sampling equipment will be decontaminated immediately before sample collection in the following manner: • De-ionized water rinse; • Scrub with de-ionized water containing non-phosphate detergent (i.e., Alconox®); • De-ionized water rinse; and • Disposable equipment (e.g. gloves, tubing, etc.) will not be reused. 4.3 Flow Measurement Methods The Treatment System will include instrumentation to collect flow and water level measurements. The flow meter will be installed at the Treatment System influent (discharge from the EQ Tank) and will represent both influent and effluent flows for the Treatment System. Additionally, flow measurements will be collected of any stormwater flow that bypasses the Treatment System. This flow will potentially be measured at the overflow weir from the diversion sump/lift station. Alternatively, flow may be measured both in the channel just downstream of the diversion sump/lift station and in the pipe conveying NCCW, just upstream of discharge into the channel, where the difference in these two flows represents stormwater flow bypassing the Treatment System, or some other method that can measure this flow. Water level will also be measured within the EQ Tank. Both readings will be recorded during every sampling event. 4.4 Field QA/QC Samples Quality assurance/quality control (QA/QC) samples will be collected at an overall frequency of at minimum twenty percent (20%) for the program. QA/QC samples may not be collected during each sampling event. The following types of QA/QC samples will be collected: • Equipment Blanks: At the sample location, laboratory-supplied, analyte-free water will be poured over or through the clean, non-dedicated sampling equipment, and collected in a sample container. The equipment blank samples will then be shipped, stored, and handled with the other samples and will be analyzed for the same parameters as other samples collected using the same device. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 5 September 2020 • Field Blanks: The field blank will be collected by transferring laboratory- supplied, analyte-free water into a sample container in the vicinity of a sample location without contacting any other sampling equipment. • Field Duplicates: The duplicate will be collected in the same manner as the other samples and the duplicate sample will be analyzed for the same parameters as the co-located samples. Duplicates will be numbered sequentially with the other samples, so they are not identifiable by the analytical laboratory (i.e., “blind” duplicates). • Matrix Spike/Matrix Spike Duplicate: The matrix spike and matrix spike duplicate sample will be collected in the same manner as the other samples. At the laboratory an appropriate spike of PFAS will be added to the sample and the sample analyzed for the same parameters as the other co-located samples. 4.5 Sample Packing and Shipping Upon sample collection, each containerized sample will be labeled and placed as soon as possible into an insulated sample cooler. The cooler will serve as a shipping container and will be provided by the laboratory along with the appropriate sample containers. Wet ice will be placed around the sample containers within heavy-duty plastic bags within the sample cooler. Samples will be maintained at a cool temperature (optimum 4°Celsius ± 2°Celsius) from the time of collection until the coolers arrive at the laboratory (if required). Plastic “bubble wrap” and/or polystyrene foam may also be used to protect the samples during shipping. Prior to shipment of the samples to the laboratory, a chain-of-custody form will be completed by the field sample custodian. Sample locations, sample identification numbers, description of samples, number of samples collected, and specific laboratory analyses to be run on each sample will be recorded on the chain-of-custody form. Samples for the first two months of sampling will be shipped to either TestAmerica Sacramento, TestAmerica Denver, or Lancaster Laboratories depending on laboratory availability at the time of sampling. After the first two months, samples will be sent to the onsite laboratory for analysis provided the detection limits at the onsite laboratory have been demonstrated to be sufficiently sensitive to demonstrate a 99% reduction in the concentration of the three indicator parameters by the Treatment System.1 Samples will be analyzed using the methods shown in Table 1. 1 As of September 2020, the Fayetteville Works Onsite laboratory had a detection limit of 100 nanograms per liter (ng/L) i.e. parts per trillion for most Table 3+ compounds. The ability to demonstrate a 99% reduction will therefore be contingent upon the concentration of influent samples being above 10,000 ng/L. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 6 September 2020 5 CALCULATIONS The Treatment System PFAS removal efficiency will be calculated using information collected as part of this sampling program. Treatment System PFAS removal effectiveness will be defined by the percentage removal of the combined concentrations of the three indicator parameters (HFPO-DA, PFMOAA and PMPA). Removal effectiveness will be determined on a quarterly average basis using composite influent and effluent samples. The system PFAS removal efficiency calculation uses volume weighted concentrations of the influent and effluent samples to calculate the percentage of mass removal. Volume weighted concentrations were developed in the event that either the influent and effluent autosamplers have different compositing durations or that the composite sampling periods in the quarter have different durations (e.g. 12 hours and 32 hours). Both circumstances could arise due to a potential equipment malfunction or severe weather event. Weighting by volume provides a representative assessment of mass present in both the influent and effluent over time; samples corresponding to greater flow volumes will have a proportionately higher weight. The Treatment System PFAS removal efficiency will be calculated using Equation 1 below. Equation 1: System Removal Effectiveness for Indicator Parameters 𝐸𝐸𝑇𝑇𝑇𝑇−𝐼𝐼𝐼𝐼𝐼𝐼−𝐼𝐼𝐼𝐼𝐼𝐼= �1 −𝑐𝑐𝑒𝑒𝑒𝑒𝑒𝑒𝑐𝑐𝑖𝑖𝐼𝐼𝑒𝑒�× 100% = �1 −∑∑𝑐𝑐𝑒𝑒𝑒𝑒𝑒𝑒,𝑚𝑚,𝑖𝑖× 𝑤𝑤𝑚𝑚i=3𝑖𝑖=1𝐼𝐼𝑚𝑚=1∑∑𝑐𝑐𝑖𝑖𝐼𝐼𝑒𝑒,𝐼𝐼,𝑖𝑖× 𝑤𝑤𝐼𝐼i=3𝑖𝑖=1𝑁𝑁𝐼𝐼=1 �× 100% = �1 −∑∑𝑐𝑐𝑒𝑒𝑒𝑒𝑒𝑒,m,𝑖𝑖× 𝑉𝑉𝑚𝑚∑𝑉𝑉𝑚𝑚𝐼𝐼𝑚𝑚=1i=3𝑖𝑖=1𝐼𝐼𝑚𝑚=1∑∑𝑐𝑐𝑖𝑖𝐼𝐼𝑒𝑒,𝐼𝐼,𝑖𝑖× 𝑉𝑉𝐼𝐼∑𝑉𝑉𝐼𝐼𝑁𝑁𝐼𝐼=1i=3𝑖𝑖=1𝑁𝑁𝐼𝐼=1 �× 100% where, 𝐸𝐸𝑇𝑇𝑇𝑇−𝐼𝐼𝐼𝐼𝐼𝐼−𝐼𝐼𝐼𝐼𝐼𝐼 = is the Treatment System PFAS removal efficiency for the three indicator parameters HFPO-DA, PMPA, and PFMOAA; 𝑐𝑐𝑒𝑒𝑒𝑒𝑒𝑒= is the volume weighted effluent concentration for a given evaluation period; 𝑐𝑐𝑖𝑖𝐼𝐼𝑒𝑒 = is the volume weighted influent concentration for a given evaluation period; DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 7 September 2020 𝑚𝑚 = represents an individual effluent composite sample time interval during a given evaluation period; 𝑀𝑀 = is the total number of effluent composite sample time intervals during a given evaluation period; 𝑛𝑛 = represents an individual influent composite sample time interval during a given evaluation period; 𝑁𝑁 = is the total number of influent composite sample time intervals during a given evaluation period; i = represents the three indicator parameters HFPO-DA, PMPA, and PFMOAA; 𝑐𝑐𝑒𝑒𝑒𝑒𝑒𝑒,𝑚𝑚,𝑖𝑖 = is the measured concentration of the three indicator parameters for each effluent composite samples2; 𝑐𝑐𝑖𝑖𝐼𝐼𝑒𝑒,𝐼𝐼,𝑖𝑖 = is the measured concentration of the three indicator parameters for each influent composite samples2; 𝑤𝑤𝑚𝑚 = is the effluent concentration volumetric weighting factor calculated for and applied individually to each effluent composite sample concentration; 𝑉𝑉𝑚𝑚 = is the volume of water entering (and exiting) the Treatment System during the effluent composite sample collection period; 𝑤𝑤𝐼𝐼 = is the influent concentration volumetric weighting factor calculated for and applied individually to each influent composite sample concentration; and 𝑉𝑉𝐼𝐼 = is the volume of water entering (and exiting) the Treatment System during the influent composite sample collection period. 6 REPORTING By September 30, 2021 Chemours will submit to DEQ a report evaluating the Treatment System’s capture of stormwater from the drainage area for rain events up to the 1-inch, 24-hour design storm and removal of PFAS compounds as measured by concentrations of indicator parameters HFPO-DA, PMPA, and PFMOAA. 2 Non-detect influent and effluent sample results will be assigned a value of zero for the calculation and the values from duplicate samples will be averaged together. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 8 September 2020 7 POTENTIAL ADJUSTMENTS The sampling and calculation methodologies described in this report have been outlined based on the present understanding of Site conditions. If conditions or methods change, modifications may need to be made to this plan. Any modifications made will be described in future submitted reports. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC SW Sampling Plan_20200930 9 September 2020 8 REFERENCES AECOM, 2018. Poly and Perfluoroalkyl Substance Quality Assurance Project Plan for the Chemours Corporate Remediation Group. Geosyntec, 2020. Site Conveyance Network and Outfall 002 PFAS Mass Loading Calculation Protocol. 31 August 2020. DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC TABLES DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC TABLE 1 SAMPLING AND ANALYSIS Chemours Fayetteville Works, North Carolina Geosyntec Consultants of NC P.C. Bypassc EQ Tank Influent Effluent HFPO-DA, PMPA, PFMOAA Time-weighted composite Lab Analysis Table 3+ Lab SOP X X Flow X X Water Level X Notes: b Continuous measurements will be collected at appropriate intervals (e.g., 5 or 15 minutes). c Bypass flow will be measured at the overflow weir from the diversion sump/lift station, or both in the channel just downstream of the diversion sump/lift station and in the pipe conveying NCCW, just upstream of discharge into the channel, where the difference represents stormwater flow bypassing the Treatment System, or some other method. -- a Sampling will be performed during wet weather, when the Treatment System is discharging treated stormwater. Samples will be collected up to four times per month during the first two months. Following the first two months of operation, sampling will be conducted up to twice per month. Parameter/Measurement Sample Type Measurement Type Analytical Method Sample Collectiona Continuousb Field Parameter TR0795 September 2020 DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC FIGURES DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC Proposed Stormwater Treatment System Location Chemours Fayetteville Works, North Carolina Figure 1Raleigh 125 0 12562.5 Feet ³Path: P:\GIS\Chemours\MXDs\TreatmentSystem_SamplingPlan_Fig1.mxd Last Revised: 8/12/2020 Author: TReederSeptember 2020 Projection: NAD 1983 StatePlane North Carolina FIPS 3200 Feet; Units in Foot US Legend Proposed Stormwater Treatment System Location Drainage area to the Stormwater Treatment System Cooling Water Channel DocuSign Envelope ID: CE09CE50-91DD-4BFB-82E0-B876714C45BC