USEPA Region 2 Vapor Intrusion Study

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USEPA Region 2Vapor Intrusion Study

• Cayuga Groundwater Contamination Site
• March 4, 2009

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Site Background

• 2001 to Present EPA Field Study
• Installed 23 Multi-level monitoring wells
• Seven Rounds of groundwater sampling (gt500
  groundwater samples)
• Quarterly water level measurement and geophysics
  support from USGS
• Surface water/sediment samples (Owasco Outlet,
  Crane Brook, Union Springs)

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Site Background (contd)

• Cayuga County DOH 1999-2008 - Multiple rounds of
  residential well sampling (gt600 samples)
• Remedial report and risk evaluations in progress

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Monitoring Wells
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Site Overview
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Ongoing Field Study Efforts

• Additional field work under NYSDEC/EPA
• Additional monitoring wells
• Additional groundwater sampling
• Geophysical survey
• Hydraulic testing

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Vapor Intrusion Study

• EPA field study indicates that chlorinated
  volatile organic compounds (CVOCs) are present in
  groundwater
• CVOC-contaminated groundwater extends from West
  Genesee St. to Union Springs
• CVOCs in groundwater can form vapors that migrate
  in the subsurface
• Potential exists for vapors to enter buildings
• Vapor sampling is being conducted to determine if
  vapors are present in buildings

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Vapor Sampling Locations

• Selection of locations based on existing data
• Location of CVOCs in groundwater
• Location of CVOCs in surface water
• Residential well data
• Human health risk evaluation
• Geologic/Hydrogeologic factors
• Depth to contaminated groundwater (lt100 feet)
• Degree of bedrock fracturing
• Presence of clean groundwater above contaminated
  zones

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Vapor Sampling Locations (contd)

• Three areas identified that meet initial
  criteria
• South of West Genesee Street
• Pinckney Road/Overbrook Drive Area
• Union Springs

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South of West Genesee Street

• Insert Figure 1

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Pinckney/Overbrook Area (east)

• Insert Figure 2

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Pinckney Road (West)
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Union Springs Area (south)

• Insert Figure 3

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Union Springs Area (north)
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Residential Vapor Intrusion Sampling Procedures

• Presented by
• Gary Newhart EPA

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Ventilation
Ventilation
Interior space
Ambient air
Ambient air
Vadose Zone
Subslab soil gas intruding into interior space
Groundwater Contamination
Vapor Pathway into Buildings
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Key Questions for Vapor Intrusion Impacts

• Does groundwater or soil contamination exist?
• Yes, in this case, so we move to the next step
• Does subsurface gas contamination exist above
  guidelines?
• Answered through collection of subslab soil gas
• 3. If subsurface gas does exist above guidelines,
  is it entering the interior space?
• Answered through collection of indoor air samples
• 4. If gas contamination exists in the residence,
  are the concentrations elevated and related to
  contamination
• - Answered by comparing results to health-based
  guidelines and conducting lifestyle and
  ambient investigation

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Monitoring and Sampling Strategy

• Initial Sampling
• - Subslab Location Ambient (outdoor)
• 2. Subsequent SUMMA Canister Sampling
• - Subslab Location
• - Basement Location
• - First Floor Location

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Indoor Air and Sub-Slab Soil Gas Activities
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Drilling
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Placement and Cementing of the Probe
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Connection of the 3-Way Valve
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Vapor Sampling Apparatus
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(No Transcript)
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Vapor Mitigation System
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What is a VI Matrix and how is it developed?

• Chemical-specific
• Considers potential health effects from long-term
  exposures for residents including children and
  adults
• Exposure Frequency of 24 hours/day and 350
  days/year
• Exposure Duration is 30 years
• Has comparison values for subslab soil gas and
  indoor air

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Step 1. Does the subslab concentration exceed x
ug/m3? No Vapor intrusion investigation is
over for this building Yes Consider indoor air
sampling
Vapor Intrusion Matrix for a Carcinogenic Chemical
Step 2. Evaluate subslab and indoor air
concentrations.
Sub-slab Soil Gas Concentration Indoor Air Concentration (ug/m3) Indoor Air Concentration (ug/m3) Indoor Air Concentration (ug/m3)
Sub-slab Soil Gas Concentration
(1) No Action (2) Investigate (3) Investigate
(4) Monitor (5) Monitor or Pursue Remediation (6) Investigate or Pursue Remediation
(7) Monitor or Pursue Remediation (8) Pursue_ Remediation or Monitor (9) Pursue Remediation
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Vapor Intrusion Matrix for a Non-Carcinogenic
Chemical
Step 1. Does the subslab concentration exceed x
ug/m3? No Vapor intrusion investigation is
over for this building Yes Consider indoor air
sampling
Step 2. Evaluate subslab and indoor air
concentrations.
Sub-slab Soil Gas Concentration Indoor Air Concentration (ug/m3) Indoor Air Concentration (ug/m3)
Sub-slab Soil Gas Concentration
(1) No Action (2) Investigate
(3) Monitor/ Remediate (4) Remediate
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VI Decisions

• VI Profile
• Subslab
• Indoor/Basement
• Indoor/First Floor Living Space
• Ambient Concentrations
• Confounding Internal Sources
• Confounding External Sources

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Key Points in VI Decisions

• Decision to remediate is not based on one piece
  of information
• Complexity and uncertainty is associated with the
  fate and transport mechanism of vapors
• Multiple lines of evidence are used in the
  decision making
• Rely on VI Team to ensure consistency in
  decisions within EPA Region 2

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Contact Information

• USEPA Remedial Project Manager - Isabel Rodrigues
  [phone]
• USEPA Community Involvement Coordinator Mike
  Basile - [phone]
• New York State DOH Krista Anders (518)
  402-7860
• New York State DEC Kevin Kelley (315)
  426-7421
• Cayuga County DOH Eileen OConner (315)
  253-1405