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Tutu Wellfield Superfund Site Proposed Cleanup Plan for Groundwater Remediation at the Curriculum Center Pre-Recorded Presentation July 14, 2021 *629926* 629926 Donette Samuel, Community Involvement Coordinator Meeting Presenters EPA PROPOSED PLAN FOR TUTU WELLFIELD | 2 Caroline Kwan, Remedial Project Manager Conclusions of the Focused Source Remedial Investigation, Risk Assessment and Feasibility Study Revisions to the 2018 Proposed Plan with updated cost- benefit analysis Proposed Plan for the cleanup of the contaminant source areas of the Tutu Wellfield site Public is encouraged to provide comments until August 13th, 2021 Presentation Objectives EPA PROPOSED PLAN FOR TUTU WELLFIELD | 3 Meeting Agenda Superfund Overview Site Background Remedial Investigation Risk Assessment Feasibility Study Preferred Remedy Questions/Comments? EPA PROPOSED PLAN FOR TUTU WELLFIELD | 4 Toxic waste disposal disasters prompted law passage by Congress in 1980 Provides Federal funds for cleanup of hazardous waste sites Allows EPA to respond to emergencies involving hazardous substances Empowers EPA to compel Potentially Responsible Parties to pay for or conduct site clean up Superfund Law EPA PROPOSED PLAN FOR TUTU WELLFIELD | 5 Superfund Cleanup Process WE ARE HERE EPA PROPOSED PLAN FOR TUTU WELLFIELD | 6 Meeting Agenda Superfund Overview Site Background Remedial Investigation Risk Assessment Feasibility Study Preferred Remedy Questions/Comments? EPA PROPOSED PLAN FOR TUTU WELLFIELD | 7 Location of Tutu Wellfield Superfund Site EPA PROPOSED PLAN FOR TUTU WELLFIELD | 8 1969: Curriculum Center property owned by LAGA Industries Ltd. (LAGA), a textile manufacturing facility 1970 – 1978: Purchased by Duplan Corporation. Begun dry cleaning operations using Tetra-chloroethene (PCE) Site History 1979 – 1981: Purchased by Panex, sold to Virgin Islands Department of Education (VIDE) 1982 – 2017: Multi-use building by VIDE EPA PROPOSED PLAN FOR TUTU WELLFIELD | 9 1982 – 1989: Multiple investigations by EPA and Potentially Responsible Parties (PRPs) 1994 – 1995: Remedial Investigation (RI) identified co- mingled plumes with chlorinated volatile organic compounds (CVOCs) and petroleum/gasoline components Site History 1995: Site listed on the National Priorities List (NPL). Studies concluded that the CVOC plume with dichloro- ethene (DCE), tetrachloroethene (PCE), trichloroethene (TCE), and vinyl chloride (VC) originated at or near the Curriculum Center EPA PROPOSED PLAN FOR TUTU WELLFIELD | 10 1996: Record of Decision (ROD) for sitewide remediation selected groundwater extraction and treatment to restore groundwater 2004-2013: Construction of the remedy completed and included two groundwater treatment systems to treat the CVOC plume. Groundwater treatment facilities operated by EPA; transferred to USVI in 2013 Site History April 2015: EPA’s Operable Unit 2 (OU2) investigates potential additional contaminant source areas EPA PROPOSED PLAN FOR TUTU WELLFIELD | 11 Status of Sitewide Remediation  Current Remedy: Groundwater extraction, ex-situ treatment, discharge to Turpentine Run, and institutional controls  Groundwater treatment systems installed at the Curriculum Center property and near O’Henry Dry Cleaners  SVE system installed at the Curriculum Center and operated from 2004 to 2006; vapor contamination was reduced significantly  Insufficient reduction of groundwater contamination at the Curriculum Center area EPA PROPOSED PLAN FOR TUTU WELLFIELD | 12 Meeting Agenda Superfund Overview Site Background Source Area Remedial Investigation Risk Assessment Remedial Alternatives Preferred Remedy Questions/Comments? EPA PROPOSED PLAN FOR TUTU WELLFIELD | 13 Source Area - Curriculum Center Property EPA PROPOSED PLAN FOR TUTU WELLFIELD | 14 Source Area Remedial Investigation Activities conducted at the Curriculum Center property April 2016 to June 2017 Surface geophysical survey Rock matrix diffusion sampling and analysis Monitoring well installation Borehole geophysical investigation Packer testing and sampling Groundwater sampling Groundwater level monitoring Dense non-aqueous phase liquid (DNAPL) monitoring EPA PROPOSED PLAN FOR TUTU WELLFIELD | 15 Source Area Groundwater Sampling Results  Characterized bedrock aquifer; defined two possible zones for contaminant migration  DNAPL is present and will act as an ongoing source  Dissolved phase CVOC contamination is present  Contaminants present in the rock matrix will continue to leach out into groundwater  The degree of natural degradation varies throughout the Curriculum Center area  The capture zone of the existing extraction system does not extend far enough in a downgradient direction EPA PROPOSED PLAN FOR TUTU WELLFIELD | 16 Monitoring Well Exceedances Summary EPA PROPOSED PLAN FOR TUTU WELLFIELD | 17 Conceptual Site Model EPA PROPOSED PLAN FOR TUTU WELLFIELD | 18 Hurricane Irma and Maria Impacts  The two sitewide groundwater (GW) treatment systems were damaged during hurricanes Irma and Maria and remained shut down due to electrical problems  Repairs were completed in 2020 and the system were placed in operation in June 2021  Contamination continue to migrate downgradient  To assess the impact of the treatment systems shutdown, supplemental GW sampling was performed in June and October 2019 and the findings are:  Analytical results confirmed the extent of chlorinated compounds in GW.  Concentrations in samples from Curriculum Center wells were generally lower than those established in the 2017 Remedial Investigation (RI).  Concentrations detected in residential wells were generally below MCLs. One sample exceeded an MCL for TCE and that well is used for irrigation purposes only.  Comparison of the 2017 & 2019 GW Sampling Data, is presented on the next figure: EPA PROPOSED PLAN FOR TUTU WELLFIELD | 19 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 20 Meeting Agenda Superfund Process Overview Site Background Remedial Investigation Risk Assessment Remedial Alternatives Preferred Remedy Questions/Comments EPA PROPOSED PLAN FOR TUTU WELLFIELD | 21 Source Area Risk Assessment Process Step 1 • Hazard Identification Step 2 • Exposure Assessment Step 3 • Toxicity Assessment Step 4 • Risk Characterization Drinking Water Use Pathway Source: Thinkstock Photos EPA PROPOSED PLAN FOR TUTU WELLFIELD | 22 Source Area Risk Assessment Summary Contaminated groundwater presents an unacceptable exposure risk VC, TCE, PCE and cis-1,2-DCE pose a lifetime cancer risk exceeding 1x10-4 Vapor intrusion from PCE and TCE are also of potential concern to workers Future use of the building is currently unknown EPA PROPOSED PLAN FOR TUTU WELLFIELD | 23 Meeting Agenda Superfund Process Overview Site Background Remedial Investigation Feasibility Study Preferred Remedy Questions/Comments? EPA PROPOSED PLAN FOR TUTU WELLFIELD | 24 Remedial Alternatives – Cleanup Options  Alternative 1 – No Action  Alternative 2 – Expand Existing Pump and Treatment System  Alternative 3 – In Situ Thermal Treatment and Pump and Treat  Alternative 4 – In Situ Steam Injection and Pump and Treat EPA PROPOSED PLAN FOR TUTU WELLFIELD | 25 Alternative 1 – No Action • No Action to remediate the contaminated groundwater • No Institutional Controls Pros – Basis for comparison with other process options Cons – Contaminants in groundwater will continue to spread. Human health and environmental risks remain Costs- • Capital Cost: $0 • Operations and maintenance (O&M) Costs: $0 • Present-Worth Cost: $0 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 26 August 2018 Alternative 2 – Expand Existing Pump and Treat System • Alternative 2A – Reinjection • Alternative 2B – Air Sparging/Soil Vapor Extraction (AS/SVE) • Alternative 2C – In Situ Chemical Oxidation (ISCO) • Alternative 2D – Surfactant Flushing Alternative 2 – Expand Existing Pump and Treat System • Expand existing system, add two new extraction wells downgradient • Upgrade current system capacity • Replace existing equipment • Alternate pumping from source area wells • Dual-phase extraction (DPE) / enhanced fluid recovery (EFR) from source area wells Pros - containment of plume; removal of DNAPL Cons - remedial timeframes are long Timeframe- • Estimated to be in excess of 30 years; • Pump and treat (P&T) and long term monitoring (LTM) costs estimated for 30 years. Costs- • Capital Cost: $4,802,538 • Operations and maintenance (O&M) Costs: $8,481,677 • Present-Worth Cost: $13,340,565 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 28 Alternative 2A – Reinjection Enhancement of Alternative 2 with reinjection of treated water downgradient through two new injection wells Pros- better hydraulic control and maintaining water balance Cons - additional hydrogeological analysis needed; reinjection wells will need maintenance; long remedial timeframes Timeframe - • Estimated to be in excess of 30 years; • P&T and LTM costs estimated for 30 years. Costs- • Capital Cost: $437,053 • O&M Costs: $51,364 plus Alt 2 • Present-Worth Cost: $488,417 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 29 Alternative 2B – AS/SVE Enhancement of Alternative 2 with air sparging and soil vapor extraction (AS/SVE) in source areas; add 25 SVE and 30 AS wells Pros- mobilize residual DNAPL within the zone influenced by air sparging; may increase the mass removal rate reducing the timeframe of the P&T system Cons- air flow may not be uniform, depends on how well the injected air permeates from injection point, connectivity of fractures and groundwater mounding Timeframe- • The AS/SVE system at source area for 5 years; • Based on calculations, downgradient area will reach drinking water standards in 25 years; • LTM costs estimated for 30 years Costs - • Capital Cost: $1,739,745 • O&M Costs: $205,461 plus Alt 2 • Present-Worth Cost: $1,945,206 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 30 Alternative 2C – ISCO Enhancement of Alternative 2 with in situ chemical oxidation (ISCO) cylinders in select source area wells; 64 cylinders in 12 monitoring wells; replaced yearly Pros- passive treatment for source area concentrations; less expensive Cons - will affect the bioactivity in the aquifer Timeframe - • ISCO at source area for 5 years; • Based on calculations, downgradient from treated source area will reach drinking water standards in 25 years; • LTM estimated for 30 years Costs- • Capital Cost: $99,364 • O&M Costs: $117,110 plus Alt 2 • Present-Worth Cost: $216,474 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 31 Alternative 2D – Surfactant Flushing Enhancement of Alternative 2 with surfactant flushing in source areas; two deep injection wells, five shallow injection wells Pros - removal of source area concentrations and DNAPL Cons- effective only if there is contact; ability of the formation to accept a sufficient volume of surfactant solution is unknown Timeframe - • Surfactant flushing at source area for 1 year; • Based on calculations, downgradient from treated source area will reach drinking water standards in 25 years; • LTM estimated for 26 years. Costs - • Capital Cost: $1,265,756 • O&M Costs: Same as Alt 2 • Present-Worth Cost: $1,265,756 EPA PROPOSED PLAN FOR TUTU WELLFIELD | 32 Alternative 3 – In Situ Thermal Treatment and Pump and Treat System • In situ thermal treatment to target DNAPL in source areas and pump and treat for hydraulic control; 260 to 270 heater wells, co-located with 260 to 270 vacuum extraction points • Add two downgradient extraction wells and upgrade the current treatment system capacity and equipment Pros - ability to penetrate fractured rock matrix and to treat DNAPL and CVOCs Cons - high capital costs Timeframe - • Thermal at source area for 2 years; • Based on calculations, downgradient from treated source area will reach perimeter P&T wells in 10 years; • LTM estimated for 12 years. Costs- • Capital Cost: $89,628,605 • O&M Costs: $4,569,283 • Present-Worth Cost: $94,309,778 Alternative 4 – In Situ Steam Injection and Pump and Treat • In situ steam injection in source areas to release DNAPL with pump and treat for hydraulic control, 60 steam injection wells and 30 multi-phase extraction wells • Add two downgradient extraction wells and upgrade the current treatment system capacity and equipment Pros - mobilize DNAPL which will be captured by the extraction wells Cons - effectiveness of steam injection relies on its ability to contact, heat, and physically displace contaminants; high capital costs Timeframe- • Steam treatment at source area for 2 years; • Based on calculations, downgradient from treated source area will reach drinking water standards in 25 years; • LTM estimated for 27 years Costs- • Capital Cost: $25,568,569 • O&M Costs: $8,539,451 • Present-Worth Cost: $34,171,200 Remedial Alternatives – Common Elements for Alternatives 2, 3 and 4  Pre-Design Investigation (PDI)  Institutional Controls  Upgrade the current system  Long-term monitoring until clean up levels are achieved  Site Management Plan  Five Year Reviews EPA PROPOSED PLAN FOR TUTU WELLFIELD | 35 EPA’s Nine Criteria for Selecting Cleanup Plans EPA uses nine criteria to evaluate remedial alternatives presented in the Feasibility Study and choose which to implement. The nine criteria are organized into 3 groups: 1. Threshold Criteria 2. Balancing Criteria 3. Modifying Criteria EPA PROPOSED PLAN FOR TUTU WELLFIELD | 36 Threshold Criteria 1. Overall Protection of Human Health and the Environment: Will the plan protect people and the plant and animal life on and near the site? EPA cannot and will not choose a plan that does not meet this basic criterion. 2. Compliance with Applicable or Relevant and Appropriate Requirements: Does the alternative meet all federal and state environmental statutes, regulations and requirements? The chosen cleanup plan must meet this criterion. EPA PROPOSED PLAN FOR TUTU WELLFIELD | 37 Balancing Criteria 3. Long-Term Effectiveness and Permanence: Will the effects of the cleanup last or could it be ineffective and cause future risks? 4. Reduction in Toxicity, Mobility or Volume through Treatment: Does the alternative reduce the harmful effects, spread of, and amount of the contaminated material? 5. Short Term Effectiveness: How soon will site risks be reduced? Could the cleanup cause short-term hazards to workers, residents or the environment? 6. Implementability: Is the alternative technically feasible? Are the right goods and services (i.e. treatment machinery, space at an approved disposal facility) available to complete the plan? 7. Cost: What is the total cost of an alternative over time? EPA must choose a plan that gives necessary protection at reasonable cost. EPA PROPOSED PLAN FOR TUTU WELLFIELD | 38 Modifying Criteria 8. State/Territory Acceptance: Do state/territory environmental agencies agree with EPA’s proposal? 9. Community Acceptance: Acceptance of preferred alternative by the impacted community will be assessed following the public comment period. Provide your comments. EPA PROPOSED PLAN FOR TUTU WELLFIELD | 39 Meeting Agenda Superfund Overview Site Background Remedial Investigation Remedial Alternatives Preferred Remedy Questions/Comments EPA PROPOSED PLAN FOR TUTU WELLFIELD | 40 Preferred Remedy - Alternative 2 , Expand Existing Groundwater Extraction and Ex-Situ Treatment (Pump and Treat) with Alternative 2A, Reinjection Expand existing pump and treat system to include downgradient extraction wells; Upgrade pump and treat system to higher flow rate; Upgrade all treatment equipment to accommodate additional flow and improve efficiency; Reinject treated water; Alternate pumping from existing monitoring wells with high contaminant concentrations; Dual phase extraction from source area wells; and, Long-term groundwater monitoring. EPA PROPOSED PLAN FOR TUTU WELLFIELD | 41 Contingency Remedy - Alternative 2 , Expand Existing Groundwater Extraction and Ex-Situ Treatment (Pump and Treat) with Alternative 2B, AS/SVE Expand existing pump and treat system to include downgradient extraction wells; Upgrade pump and treat system to higher flow rate; Upgrade all treatment equipment to accommodate additional flow and improve efficiency; Air Sparging/SVE at source areas; and, Long-term groundwater monitoring. EPA PROPOSED PLAN FOR TUTU WELLFIELD | 42 Questions and Comments? To request a copy of the Proposed Plan or subscribe to the Tutu Wellfield Superfund site’s email list for the latest updates, contact: Donette Samuel Community Involvement Coordinator E-mail: samuel.donette@epa.gov EPA PROPOSED PLAN FOR TUTU WELLFIELD | 43 Questions and Comments? Please address written comments no later than August 13, 2021, to: Caroline Kwan Remedial Project Manager U.S. Environmental Protection Agency 290 Broadway, 18th Floor New York, NY 10007-1866 E-mail: kwan.caroline@epa.gov EPA PROPOSED PLAN FOR TUTU WELLFIELD | 44 Thank You! Thank you for watching the Tutu Wellfield Superfund site Pre-Recorded Presentation. For more information about the site, visit: https://www.epa.gov/superfund/tutu-wellfield EPA PROPOSED PLAN FOR TUTU WELLFIELD | 45