1. of Massachusetts Department ENVIRONMENTAL PROTECTION Soil Vapor Intrusion... A Decade of Regulatory Requirements & Experiences Paul W. Locke MA DEP Bureau of Waste Site Cleanup One Winter Street Boston, MA 02108 617-556-1160 Paul.Locke@state.ma.us

2. of Massachusetts Department ENVIRONMENTAL PROTECTION Late 1980s… Hillside School, Needham Mass… Wow…that can happen?

3. of Massachusetts Department ENVIRONMENTAL PROTECTION

4. of Massachusetts Department ENVIRONMENTAL PROTECTION MADEP Regulatory Response: 1.Place concern on radar screen 2.Incorporate into cleanup standards 3.Obtain “real world” data to gauge scope/parameters of problem 4.Provide tools/toolbox to regulated community

5. of Massachusetts Department ENVIRONMENTAL PROTECTION #1: On the Radar Screen… Training/awareness: agency staff and regulated community Regulatory requirement to notify MADEP if pathway likely or confirmed

6. of Massachusetts Department ENVIRONMENTAL PROTECTION #2: Incorporate into Cleanup Standards Transport Model Calc Source Conc in GW Ceiling Conc 50% Solubility Lowest of 3 or GW background or PQL, whatever higher GW Standard Air Groundwater Lowest of 3 or IAQ Background, whatever is higher Non-Cancer Risk Based Indoor Air Conc Cancer Risk Based Indoor Air Conc 50% Odor Threshold

7. of Massachusetts Department ENVIRONMENTAL PROTECTION 1993 Standards Transport Model Johnson & Ettinger Assumed 10% Henry’s Law Equilibrium Condition GW to Soil Gas: Soil Gas to Indoor Air:  = 5 x 10 -4 “crude and limited application of J&E”

8. of Massachusetts Department ENVIRONMENTAL PROTECTION Calculated GW Standards (1993) Compound Standard (  g/L) TCE300 1,1,1-TCA4000 PCE3000

9. of Massachusetts Department ENVIRONMENTAL PROTECTION 1996 Evaluation  Are these Standards Really Protective?  Let’s take a Look at our Files… GW Conc Soil Gas Conc Indoor Air Conc

10. of Massachusetts Department ENVIRONMENTAL PROTECTION MADEP Records Review Database Search DEP Files 6000 Potential Sites Evaluated 177 Adequate Data 59 sites Chlorinated 36 (61%) BTEX 23 (39%)

11. of Massachusetts Department ENVIRONMENTAL PROTECTION Petroleum Sites? Chlorinated Solvent Sites? Findings: Were the 1993 Standards Generally Conservative & Protective?  ☺

12. of Massachusetts Department ENVIRONMENTAL PROTECTION Proposed Revisions (2004) Chemical-Specific Evaluations Conservative Pathway Scenario Conservative Site/Soil Properties

13. of Massachusetts Department ENVIRONMENTAL PROTECTION Key J&E Inputs (MADEP 2004) Groundwater 7 feet below grade; 1 foot below basement floor Sand, total porosity n = 0.43 Building Depressurization  P= 4 Pa (40 g/cm-s 2 ); 0.45 air exchanges/hour Vadose Zone Moisture Content [  w ] = ????

14. of Massachusetts Department ENVIRONMENTAL PROTECTION Moisture Level Below Buildings Dry Soils?

15. of Massachusetts Department ENVIRONMENTAL PROTECTION Vadose Zone Soil Moisture What is a realistic, conservative value….. beneath buildings? Little study data available, but …. Fair amount of chemical analytical data from soil samples beneath buildings!

16. of Massachusetts Department ENVIRONMENTAL PROTECTION * Moisture (w/w) to Soil Moisture(v/v) 0.06

17. of Massachusetts Department ENVIRONMENTAL PROTECTION Proposed Revisions to Current MADEP Groundwater Standards (Soil Vapor Pathway) Up to an order of magnitude lower for some chlorinated solvents Public Comment Period Ended December 10, 2004 Stay Tuned…..

18. of Massachusetts Department ENVIRONMENTAL PROTECTION #4: Provide Tools & Toolboxes Site-Specific Evaluations Guidance Documents Rules of Thumb

19. of Massachusetts Department ENVIRONMENTAL PROTECTION

20. of Massachusetts Department ENVIRONMENTAL PROTECTION Site-Specific Pathway Evaluation (Mandatory when > Generic GW Standard) Key Tools: Soil Gas Assessment Indoor Air Analysis Vertical Profiling

21. of Massachusetts Department ENVIRONMENTAL PROTECTION MADEP Recommended Approach

22. of Massachusetts Department ENVIRONMENTAL PROTECTION MADEP Guidelines for Soil Gas Evaluation : Compound Screen out levels ppmV PID (eV) FID <1010-11.4>11.4 Toluene 1112 10 Ethylbenzene 4443 Xylenes 25262422

23. of Massachusetts Department ENVIRONMENTAL PROTECTION MADEP Guidelines for Obtaining Soil Gas Samples depth to groundwater building foundation foundation cracks enclosed space vadose zone diffusing vapors capillary zone dissolved chemical in groundwater Infiltration displaces/ solubilizes soil gases Negative bias grass pavement place probe below bldg/pavement for representative samples

24. of Massachusetts Department ENVIRONMENTAL PROTECTION Real World Example of Negative Bias: TCE Soil Gas Data from 2 Homes DateInteriorExterior 9/96 397 / 281 24 / <1 12/96 16 / 80 <1 / <1 3/97 6 / 64 <1 / <1 6/97 19 / 226 <1 / <1 8/97157 / 594 4 / <1 All data ppb v/v TCE

25. of Massachusetts Department ENVIRONMENTAL PROTECTION Obtaining Indoor Air Samples Winter months usually “worst case” - Other times may not rule out pathway frost layer Furnace combustion Stack Effects Vapors windows closed

26. of Massachusetts Department ENVIRONMENTAL PROTECTION Groundwater/Vertical Profiling Infiltration VOC plume fresh water lens well groundwater flow

27. of Massachusetts Department ENVIRONMENTAL PROTECTION For More Information….. BWSC.Information@state.ma.us or BWSC.Regulation@state.ma.us Characterizing Risks Posed by Petroleum Contaminated Sites: Implementation of the MADEP VPH/EPH Approach www.mass.gov/dep/bwsc/files/02-411.pdf Indoor Air Sampling and Evaluation Guide www.mass.gov/dep/ors/files/indair.pdf MCP Numerical Standards: GW-2 www.mass.gov/dep/bwsc/files/standard /gw2/gw2.htm