usepa region 2 vapor intrusion study
DESCRIPTION
USEPA Region 2 Vapor Intrusion Study. Cayuga Groundwater Contamination Site March 4, 2009. Site Background. 2001 to Present – EPA Field Study Installed 23 Multi-level monitoring wells Seven Rounds of groundwater sampling (>500 groundwater samples) - PowerPoint PPT PresentationTRANSCRIPT
USEPA Region 2USEPA Region 2Vapor Intrusion StudyVapor Intrusion StudyCayuga Groundwater Contamination SiteMarch 4, 2009
Site BackgroundSite Background
2001 to Present – EPA Field Study
– Installed 23 Multi-level monitoring wells
– Seven Rounds of groundwater sampling (>500 groundwater samples)
– Quarterly water level measurement and geophysics support from USGS
– Surface water/sediment samples (Owasco Outlet, Crane Brook, Union Springs)
Site Background (cont’d)Site Background (cont’d)
Cayuga County DOH –1999-2008 - Multiple rounds of residential well sampling (>600 samples)
Remedial report and risk evaluations in progress
Monitoring WellsMonitoring Wells
Site OverviewSite Overview
Ongoing Field Study EffortsOngoing Field Study Efforts
Additional field work under NYSDEC/EPA:
– Additional monitoring wells
– Additional groundwater sampling
– Geophysical survey
– Hydraulic testing
Vapor Intrusion StudyVapor 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
Vapor Sampling LocationsVapor 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 (<100 feet) Degree of bedrock fracturing Presence of clean groundwater above
contaminated zones
Vapor Sampling Locations (cont’d)Vapor Sampling Locations (cont’d)
Three areas identified that meet initial criteria:
– South of West Genesee Street
– Pinckney Road/Overbrook Drive Area
– Union Springs
South of West Genesee StreetSouth of West Genesee Street
Insert Figure 1
Pinckney/Overbrook Area (east)Pinckney/Overbrook Area (east)
Insert Figure 2
Pinckney Road (West)Pinckney Road (West)
Union Springs Area (south)Union Springs Area (south)
Insert Figure 3
Union Springs Area (north)Union Springs Area (north)
Residential Vapor Intrusion Sampling Residential Vapor Intrusion Sampling ProceduresProcedures
Presented by:
Gary Newhart – EPA
Vapor Pathway into BuildingsVapor Pathway into Buildings
Vadose Zone
Groundwater Contamination
Interior space
Subslab soil gasSubslab soil gasintruding intointruding intointerior spaceinterior space
Ambient air Ambient air
VentilationVentilation
Key Questions for Vapor Intrusion Key Questions for Vapor Intrusion ImpactsImpacts
1. Does groundwater or soil contamination exist?- Yes, in this case, so we move to the next step
2. 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
Monitoring and Sampling StrategyMonitoring and Sampling Strategy
1. Initial Sampling- Subslab Location + Ambient (outdoor)
2. Subsequent SUMMA Canister Sampling- Subslab Location- Basement Location- First Floor Location
Indoor Air and Sub-Slab Soil Gas Indoor Air and Sub-Slab Soil Gas ActivitiesActivities
Drilling
Placement and Cementing of the Probe
Connection of the 3-Way Valve
Vapor Sampling ApparatusVapor Sampling Apparatus
Vapor Mitigation SystemVapor Mitigation System
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
Sub-slab Soil Gas
Concentration
Indoor Air Concentration (ug/m3)
(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
Vapor Intrusion Matrix for a Carcinogenic Chemical
Step 1. Does the subslab concentration exceed x ug/m3?No = Vapor intrusion investigation is over for this buildingYes = Consider indoor air sampling
Step 2. Evaluate subslab and indoor air concentrations.
Sub-slab Soil Gas
Concentration
Indoor Air Concentration (ug/m3)
(1) No Action (2) Investigate
(3) Monitor/ Remediate (4) Remediate
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 buildingYes = Consider indoor air sampling
Step 2. Evaluate subslab and indoor air concentrations.
VI Decisions
VI Profile
– Subslab
– Indoor/Basement
– Indoor/First Floor Living Space
– Ambient Concentrations
Confounding Internal Sources
Confounding External Sources
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
Contact Information
USEPA Remedial Project Manager - Isabel Rodrigues – (212) 637-4248
USEPA Community Involvement Coordinator– Mike Basile - (716) 551-4410
New York State DOH – Krista Anders – (518) 402-7860
New York State DEC – Kevin Kelley – (315) 426-7421
Cayuga County DOH – Eileen O’Conner (315) 253-1405