Background. NCP Early or Interim Actions 5/3/2017. Current Ohio EPA Response Action Levels and Time Frames for TCE at Vapor Intrusion Sites in Ohio

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1 Current Ohio EPA Response Action Levels and Time Frames for TCE at Vapor Intrusion Sites in Ohio Carrie Rasik, Risk Assessor Ohio EPA MSECA, May 2017 Background U.S. EPA IRIS 2011 TCE Toxicity Update - Short-term RfC (inhalation) - Non-Cancer Hazard (fetal heart malformation) Statewide Consistency Justification/Direction Stakeholders: director s office, Ohio EPA staff, consultants, RPs, volunteers, local health departments NCP Early or Interim Actions National Contingency Plan preamble (55 FR 8704) Early action where appropriate Eliminate, reduce or control hazards Removal Management Levels (HQ 3; ELCR 1E-04) Case-specific conditions Ohio EPA guidance construction Removal Management Levels (RMLs) Massachusetts DEP U.S. EPA Region 9 1

2 Framework of Ohio EPA Guidance TCE Response Action Levels and Timeframes Media: ground water, soil gas, indoor air Receptors: Residential and Commercial Accelerated (HQ 1) Urgent (HQ 3) Imminent Hazard* (*Indoor Air Only; Mass. DEP) Response actions: sampling, mitigation and/or activities to reduce exposure ^^When Receptors Are Present^^ TCE Exposure Assessment 1. Is TCE present? 2. Are receptors present? 3. Is there a potentially complete pathway? 4. Does indoor air (measured or modeled) exceed an HQ of one, or does sub-slab soil vapor or ground water exceed a response action level? If the answer is yes to all of these questions, then assessment and/or response actions may be necessary RALs for TCE in Indoor Air Accelerated RAL HQ=1 Urgent RAL HQ=3 Imminent Hazard RAL Residential 24 hours >2.1 µg/m³ (>0.39 ppbv) >6.3 µg/m³ ( >1.2 ppbv) >20 µg/m³ ( >3.7 ppbv) Commercial Eight hour workday >8.8 µg/m³ (>1.6 ppbv) >26 µg/m³ (>4.8 ppbv) >60 µg/m³ (>11 ppbv) 2

3 Timeframes for TCE in Indoor Air Accelerated >2.1 or 8.8 µg/m³ Urgent >6.3 or 26 µg/m³ Imminent Haz >20 or 60 µg/m³ Timeframe Response Within a few weeks Increase building pressure and/or ventilation Seal potential conduits Install indoor air purification systems Install depressurization systems Within a few days Same interim or early response measures as for accelerated Temporary receptor relocation may be necessary if mitigation measures not available or effective ASAP to within a few days Relocate receptors until indoor air samples are below the accelerated RALs During the Indoor Air Investigation Notify receptors Coordination with appropriate state, local and health authorities Vent the lower level until interim measures employed Evaluation of subsurface VI for long-term exposure will continue until clean up goals reached Resample ^^Pre-Emptive Mitigation Can Be Conducted At Any Time in the Process^^ RALs for TCE in Sub-Slab Soil Gas Exposure Scenario Residential 24 hours Commercial Eight hour workday Accelerated RAL HQ = 1 >70 µg/m³ (>13 ppbv) >290 µg/m³ (>54 ppbv) Urgent RAL HQ=3 >210 µg/m³ (>39 ppbv) >880 µg/m³ (>160 ppbv) 3

4 Timeframes for TCE in Sub-Slab Timeframe Response Accelerated >70 or 290 µg/m³ to two weeks Sample indoor air and collect concurrent sub-slab soil gas Urgent RAL >210 or 880 µg/m³ Sample indoor air and collect concurrent sub-slab soil gas RALs for TCE in Ground Water Exposure Scenario Residential 24 Hours Commercial Eight Hour Workday Accelerated RAL HQ=1 Coarse- Grained or Unknown Soils Fine- Grained Soils* Urgent RAL HQ=3 Coarse- Grained or Unknown Soils Fine- Grained Soils* >11 µg/l >21 µg/l >32 µg/l >63 µg/l >44 µg/l >89 µg/l >130 µg/l >270 µg/l *Fine-grained soils using AF of when laterally extensive layers are present Timeframes for TCE in Ground Water Accelerated RAL HQ=1 Urgent RAL HQ=3 Timeframe Response to two weeks Sample sub-slab soil gas, if feasible; or Sample soil gas near ground water interface, if capillary fringe is greater than five feet bgs Sample sub-slab and indoor air concurrently 4

5 Response Action Decisions: What If.? Ground Water Exceeds (soil vapor or paired?) Source strength Distance to receptors Geology, Hydrogeology Sub-Slab is slightly over/under Confirmation Indoor Air Samples to Verify Protection of Receptors Sub-Slab Exceeds Mitigation system, lack time for robust IA investigation, ensures protection of receptor Indoor air detected below Accelerated RAL first round, exceeds second confirmation round Employ mitigation measures Response Action Examples in Ohio Relocation: Option to Work From Home or Other Buildings Exposure Prevention: Prohibiting Building Access Ventilation: Opening or Creating Windows Mitigation: SSDS or passive system Purifiers or Filters: Indoor air purifiers or carbon filters Challenges of Implementation Increased Expenses (lab, shipping, labor) Suma canister shortages Limited work force/hours in a day Access issues Practicality of mitigation system construction Long-term remedial goal achievement Economical loss 5

6 Lessons Learned Motivation Consistency issues with timeframes Receptors vs Sensitive Receptors Added expense Workload shift Balancing Act: Protection of Human Health and Practicality of Timeframes Update Under Consideration Ohio EPA TCE VI Guidance Ohio EPA s Recommendations Regarding Response Action Levels and Timeframes for Common Contaminates of Concern at Vapor Intrusion Sites in Ohio August 2016 epa.ohio.gov Divisions and Offices Environmental Response and Revitalization Guidance Risk Assessment Tab Response Action Levels for VOCs Other Chemical RALs and Timeframes (IA, SS GW) Chronic (HQ 1 or 1E-05) Accelerated (HQ 3 or 1E-04) 6