The URL can be used to link to this page

Home My WebLink About2021.03.26_CCO.p18_OnAndOffsiteAssessment-DEQCommentsNCDEQ PresentationNCDEQ Presentation March 26, 2021 Consent Order Paragraph 18On and Offsite AssessmentNCDEQ Comments Meeting NCDEQ Presentation Overview •Objectives •Review & Updates –Site Conceptual Model (Compounds, Releases, Geology) –Remedial Actions Completed and in Progress •Discussion of Short-Term DEQ Requests –Data Transfers & Quarterly Monitoring •Discussion of DEQ Comments –Sources –Groundwater Delineation –Soils Delineation –Offsite Soil and Human Health Screening Level Exposure Assessment (HH-SLEA) •Closing 2 NCDEQ Presentation Objectives Paragraph 18 Objectives and Outcomes –Collect data necessary to expeditiously comply with Consent Order –From late February to late September 2019 •Plan, conduct and report investigation(s) •Provide basis for remedy development in Corrective Action Plan •Provide basis for Addendum to Consent Order Paragraph 12 –Submitted Sept. 2019 with update in Oct. 2019 3 NCDEQ PresentationNCDEQ Presentation CSM Updates and Review Review (with some updates) •Table 3+ PFAS Transport Pathways •Table 3+ PFAS Sources •Table 3+ PFAS Signatures Updates •Interim Remedies •Long-Term Groundwater Remedy March 26, 2021 4 NCDEQ Presentation Location of Site –Active Remediation / Investigation 5 NCDEQ Presentation Source Area Definition 6 -Historical Release Areas identified •Air in Yellow •Process Water in Teal -Process Water Release Areas are distributed along conveyance network onsite -Aerially deposited PFAS are widely distributed on and offsite NCDEQ Presentation PFAS Signatures and Distribution (Map includes late 2019 groundwater, seep and creek data) 7 Aerial Signature PMPA &HFPO-DA as Markers Offsite and onsite Lower concentrations Controlled by Thermal Oxidizer and GAC/RO Process Water Signature PFMOAA as Marker Observed onsite and downstream river Downgradient of releases Controlled by onsite remedies F O OH F F F F F F F3C F O F O OH F F F3C F O F O OH F F F F O NCDEQ Presentation Process Water Signature in River Loading Rank Pathway Source 1 Seeps Process 2 Old Outfall Process 3 Onsite GW Process 4-5 Creeks Aerial 6-7 River (Up + Down)Aerial 8 Outfall 002 Misc. 8 •2019-2020: Seeps, Old Outfall & Onsite GW contribute ~80% of load in river •Outfall 002 source is a combination of stormwater, intake, and WWTP effluent (WWTP actions progressing –e.g. terracotta pipe grouting) NCDEQ Presentation River Concentrations •CFPUA data show HFPO-DA below 140 ng/L since 2017 in raw and finished water •Further reductions occurring and in-progress •Measured data consistent with mass loading modeling 9 0 70 140 210 280 350 420 HFPO-DA Concentration (ng/L)Modeled Concentration Kings Bluff Finished Water Detected Data Kings Bluff Raw Water Intake Detected Data Outfall 003 System Startup Seep C System Startup NCDEQ Presentation Old Outfall Remediation NCDEQ Presentation Old Outfall Remediation Quarter 4 2020: 25.4 kg removed (56 lbs) NCDEQ Presentation Seeps Remediation NCDEQ Presentation Seep C Remediation FTC –Flow Through Cell ng/L –nanograms per liter NCDEQ Presentation Groundwater Barrier Wall Remedy •COA: Operational by March 15, 2023 •60% Design Package due August 15, 2021 •Pre-Design Investigation –19 New Standard Penetration Test Locations –19 New Cone Penetrometer Test Locations –6 Surface Water Locations –7 New Monitoring Wells –5 New Extraction Wells + Aquifer Tests –17 Passive Flux Meters Locations •Refined Geology and Hydrogeology 14 NCDEQ Presentation Detailed Geological Cross Section 15 NCDEQ Presentation Detailed Geological Cross Section 16 Black Creek Aquifer Upper Cape Fear Confining Unit Black Creek Confining Unit Surficial Aquifer Near OF003 Near Willis Creek NCDEQ Presentation CSM Update and Review –Summary •P18 report identified historical release areas –Aerial (distributed PFAS, lower concentrations) –Process water (onsite, higher concentrations, mobile PFAS) •P18 facilitated remedy planning •River loads primarily from process water loading pathways •Interim and long-term remedies focus on process water sources 17 NCDEQ PresentationNCDEQ Presentation Short-Term DEQ Requests Data Transfers Quarterly Sampling March 26, 2021 18 NCDEQ Presentation Data Transfers •DEQ requested onsite and offsite groundwater data. •On February 15, 2021 Chemours submitted to DEQ: –Maps and locational data for all onsite and offsite groundwater wells –All onsite and offsite groundwater analytical data in an EQuIS format •Offsite residential analytical data has been submitted routinely in the same EQuIS format •Chemours will continue to provide all analytical data in this format 19 NCDEQ Presentation 20 125 wells onsite –59 in Perched Zone –28 in Surficial –38 in Black Creek Aquifer and Floodplain Deposits Onsite Well Network NCDEQ Presentation Quarterly Groundwater Monitoring (Note all 125 wells sampled annually) •Quarterly monitoring at 22 wells –19 wells (green) mass loading program –3 wells (blue) perched zone historical release areas •Monitors Groundwater Reaching Receptors: •Stability Trends (based on 6 to 39 monitoring events) –20 wells: decreasing, stable or no trend HFPO-DA –1 well : potentially increasing –0 wells: definitively increasing –1 well: only three data points •Mass Loading Program Wells 12 events in 12 months per COA P1 21 MW-24 NAF-03 NAF-12 -Cape Fear River -Willis Creek -Georgia Branch Creek -Old Outfall 002 NCDEQ Presentation Groundwater 1-year Travel •1 year travel distance shown for groundwater below historical release areas •Groundwater leaving historical release areas takes more than 1 year to reach receptors 22 Perched Zone NCDEQ Presentation Groundwater 1-year Travel •1 year travel distance shown for groundwater below historical release areas •Groundwater leaving historical release areas takes more than 1 year to reach receptors 23 Surficial Aquifer NCDEQ Presentation Groundwater 1-year Travel •1 year travel distance shown for groundwater below historical release areas •Groundwater leaving historical release areas takes more than 1 year to reach receptors 24 Black Creek Aquifer NCDEQ PresentationNCDEQ Presentation Discussion of DEQ Comments March 26, 2021 25 NCDEQ Presentation Discussion of DEQ Comments Topics •Sources and Signatures •Onsite Groundwater •Offsite Groundwater •Onsite Soil and Leachate •Offsite and HH-SLEA Soil Sampling 26 NCDEQ PresentationPublicNCDEQ Presentation Sources and Signatures March 26, 2021 27 NCDEQ Presentation Sources and Signatures –Knowledge 28 Aerial –Distributed Larger area -onsite + offsite Lower concentration ~20% of Load in River Mobile Table 3+ PFASProcess Water –Direct Smaller area –onsite + downstream river Higher concentration ~80% of Load in River NCDEQ PresentationPublicNCDEQ Presentation Onsite Groundwater March 26, 2021 29 NCDEQ PresentationPublicNCDEQ Presentation Offsite Groundwater March 26, 2021 30 NCDEQ Presentation Offsite Groundwater •Sampled over 5,000 offsite residences •Receiving well records with well depths from local counties •Proceeding towards completing delineation of offsite private well impacts •20 offsite wells installed as part of P18 Assessment Attachment C PFAS NCDEQ PresentationPublicNCDEQ Presentation Onsite Soil and Leachate March 26, 2021 32 NCDEQ Presentation TestAmerica Laboratories Soil Detection Limit Comparison 33 100 1,000 10,000 100,000 1,000,000 10,000,000 100,000,000 0 1 2 3 4 5 6 7 8 9Reporting Limit (ng/kg)Table 3+ PFAS Method 8260D VOCs Pesticides PCB Aroclors Diesel Range Organics Gasoline Range Organics HFPO-DAMethod 537 PFAS NCDEQ Presentation PFAS at Site •17 “Table 3+ PFAS” with reliable analytical methods •Relatively mobile compared to other compounds 34 HFPO-DA PMPA PFMOAA 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 0 1 2 3 4 5 6 7 8Log Koc (L/kg)Table 3+ PFAS Method 537 PFAS Chlorinated Solvents BTEX PCBs PAHsPesticides Can be Non-Aqueous Phase Liquids -NAPLSAqueousMany are AFFF NCDEQ Presentation 35 Soil Leachate Table 3 Compounds and HFPO-DA NCDEQ Presentation Surface Soil Leachate Analytical Data –HFPO-DA 36 Surface Soil Analyses Leachate Analyses Surface Soil 94 48 Subsurface Soil 35 6 NCDEQ Presentation Surface and Subsurface Soil Analytical Data –HFPO-DA 37 Surface Soil Analyses Leachate Analyses Surface Soil 94 48 Subsurface Soil 35 6 Sub-Surface NCDEQ PresentationPublicNCDEQ Presentation Offsite and HH-SLEA Soil Sampling March 26, 2021 38 NCDEQ Presentation 39 Offsite Surface Soils Composite Sampling Offsite Subsurface Soils Discrete Sampling NCDEQ Presentation 40 Offsite Surface Soils Composite Analytical Offsite Subsurface Soils Discrete Analytical NCDEQ Presentation EPA Acceptance •EPA in multiple publications suggests consideration of ISM guidance prepared by ITRC •ISM is appropriate for: –Large Areas –Low Spatial Correlation (i.e. aerial deposition sites) •Strategic Sampling Approaches Technical Guide (EPA ID# 542-F-18-005) https://semspub.epa.gov/work/HQ/100001800.pdf 41 NCDEQ Presentation Offsite Soil and HH-SLEA Results •Highest Soil Concentrations in EU1, EU4, EU5 [North and Northeast of Site] •Intake of T3+ PFAS from soil is 7,500x less than intake from untreated well water •Intake of HFPO-DA from soil is 2,100x less than intake from untreated well water •Hazard of HFPO-DA is 2,300x less than intake from untreated well water •Hazard Quotient of HFPO-DA in soil is 0.0003 42 NCDEQ PresentationNCDEQ Presentation Closing March 26, 2021 43 NCDEQ PresentationNCDEQ Presentation March 26, 2021 End of Content