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Hookston Station Area Baseline Risk Assessment Community Meeting June 20, 2005 Cal/EPA -

Hookston Station Area Baseline Risk Assessment Community Meeting June 20, 2005 Cal/EPA - SF Bay Regional Water Quality Control Board. 1. Water Board Department of Health Services, Environmental Health Inv. Branch (DHS/EHIB) Union Pacific Railroad Mr. Dan Helix

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Hookston Station Area Baseline Risk Assessment Community Meeting June 20, 2005 Cal/EPA -

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  1. Hookston Station Area Baseline Risk Assessment Community Meeting June 20, 2005 Cal/EPA - SF Bay Regional Water Quality Control Board 1

  2. Water Board Department of Health Services, Environmental Health Inv. Branch (DHS/EHIB) Union Pacific Railroad Mr. Dan Helix Contra Costa County Redevelopment Agency Environmental Resources Management (ERM)* Center for Toxicology & Environmental Health (CTEH)* * consultants to responsible parties Introductions 2

  3. Meeting Agenda • Open Forum • Introduction (Water Board) • Status of Hookston Station Area Project (Water Board) • Baseline Risk Assessment (CTEH) • Next Steps (Water Board) 3

  4. Chronology • Investigations conducted 1989 and 1996 • Water Board notified of potential release in 2001 • Water Board order (SCR) adopted April 2003 • Water Board staff requiring investigation of other potential contaminant sources 4

  5. Primary Chemicals of Concern • Tetrachloroethylene (PCE) • Trichloroethylene (TCE) • Dichloroethylene (DCE) 5

  6. Hookston Station I-680 Walnut Creek channel 6

  7. Documents Available • RI – Remedial Investigation • QMR – Quarterly Monitoring Reports • Soil Vapor Sampling – in QMRs • Environmental Risk Assessment • Off-Site Investigation Reports 7

  8. Review Reports • Pleasant Hill Library – paper copy • Geotracker – electronic copy www.geotracker.waterboards.ca.gov • Choose ‘Case Finder’ • Case #07S0156 • Choose ‘Report’ then ‘Site Documents’ 8

  9. Progress Since Last Meeting • 35 monitoring wells installed • Private well surveys resulted in abandonment of 5 out 12 wells reported • Initial round of indoor air sampling completed • 17 homes tested • Additional soil gas sampling performed 9

  10. Vapor Intrusion Basics Indoor air circulation Intrusion into buildings Crawl Space Soil Vapors Plume Groundwater 10

  11. Indoor Air Sampling • 17 homes sampled Jan-April 2004 (winter season) • 6 homes contained TCE in indoor-air above Water Board screening level of 1.2 ug/m3 (range from 2 to 5 ug/m3 ) • Summer season sampling to begin July or August 2005 11

  12. Next Steps • Finalize Baseline Risk Assessment • Submit Feasibility Study (FS / RAP) • Public review and comment • Issue final enforcement order to approve FS / RAP and set cleanup standards • Implement approved FS / RAP including additional sampling / monitoring

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