Residential Vapor Intrusion due to a Neighborhood Dry Cleaner

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November 2, 2006 Presentation by Theresa Evanson Wisconsin

1 Residential Vapor Intrusion due to a Neighborhood Dry Cleaner State Coalition for Remediation of Drycleaners October 30 November 2, 2006 Presentation by Theresa Evanson Wisconsin Department of Natural Resources Bureau for Remediation and Redevelopment 1

2 Co-author: Henry Nehls-Lowe Bureau of Environmental and Occupational Health, Division of Public Health, Department of Health & Family Services Reference report: Agency for Toxic Substance & Disease Registry (ATSDR), July 6, Health Consultation Exposure Investigation: Redi-Quik Dry Cleaners Vapor Intrusion in a Private Residence, West Allis, Milwaukee County, Wisconsin. Atlanta, GA: U.S. Department of Health & Human Services. 2

3 Wisconsin Dry Cleaner Environmental Response Fund (DERF) Created 1997 to aid cleanup of contamination at dry cleaners Funded with 1.8% fee on gross receipts from dry cleaning Generates ~$1 million/year Program reimburses DC site investigation & remediation costs 130+ dry cleaning sites currently registered in program 3

4 Redi-Quik Dry Cleaner, located at 9508 West Greenfield Ave., West Allis, Milwaukee County, WI. Stand alone DC operates in a mixed commercial/residential neighborhood. 4

Redi-Quik Dry Cleaner Operating history: -1940 s Car dealership -1950 s Retail gasoline station -1960 s Coin operated dry cleaner; converted to standard dry cleaner sometime in 1970 s?

5 Redi-Quik Dry Cleaner Operating history: s Car dealership s Retail gasoline station s Coin operated dry cleaner; converted to standard dry cleaner sometime in 1970 s? petroleum USTs removed Dry cleaner contamination discovered during UST investigation Initial DC site investigation completed Vapor intrusion investigation of neighboring home by Wisconsin Division of Public Health 5

6 Hudson Dealership in 1940 s cars displayed in semi-circular part of building Former gas station area in front of building 6

7 Neighboring home build in 1950 s. Cinder block basement with poured concrete floor. 7

8 Note monitoring well in front yard Vents along DC building Broken concrete/driveway 8

9 Site Geology & Hydrogeology 130 of silty clay glacial tills overlying dolomite Municipal water supplied from deep bedrock aquifers Depth to groundwater 3 6 feet, with seasonal fluctuation Groundwater flow primarily north, but influenced by utilities, UST excavation. 9

10 Note location of buried PCE tank. 10

11 Tetrachloroethylene (PCE) Concentrations Sub-Surface Soils (µg/kg) Groundwater (µg/l) On-Site 3,090 45,000 Off-Site 230, Site Investigation Results High soil concentrations on the neighboring property prompted WI Dept. of Heath & Family Services to test indoor and outdoor air at the home. 11

12 Soil contamination map from 2001 Site Investigation extent of soil contamination is likely greater than shown. Soil contamination appears to be worst to the southeast of the home & our vapor investigation tended to concentrate in this area. 12

13 Extent of groundwater contamination from 2001 Site Investigation. Groundwater contamination not fully defined. 13

14 Backdoor entry to home. Monitoring well in driveway. Feb As a quick screening method, DHFS hung Organic Vapor Passive Diffusion Monitor (OVM) under soffit and in basement. 14

15 January 2006, staff from Wis. Division of Public Health (DPH) were requested to assess vapor migration at this home. February, 2006, DPH met with the homeowner, discussed the potential for VI, and hung 2 OVMs (3M organic vapor passive diffusion monitors). One on the outside backdoor soffit & one in the basement. 15

16 Feb OVM in basement 16

17 PCE Levels at West Allis Home Date Sample Period Outdoor Air Indoor Air Location 2/9/06 8 days 34 Roof Soffit ײ ײ 503 Basement Concentrations in micrograms per cubic meter (µg/m 3 ) DHFS target risk value for PCE in residences is 0.31 µg/m 3. Issues for OVMs: Benefits: -Less expensive to buy & analyze -Easy to use can ship to a homeowner & can be mailed back Disadvantages: -Less sensitive (higher detection level) than SUMMA Canisters -Less accurate than SUMMA Canisters -Reliability to identify a public health risk? -Because these levels indicated the existence of a public health risk, follow-up testing with SUMMA canisters was conducted in March

18 Before collecting SUMMA canister samples, a survey of PCE sources was done. No PCE sources were found, but the homeowner did move paint and other materials to the garage. 18

19 March SUMMA canister in southeast corner of basement (nearest the dry cleaner source). 19

20 March Living room location of SUMMA canister. 20

21 March Bedroom location of SUMMA canister. 21

22 March Front door location of SUMMA canister. 22

23 April In addition to the air samples at the home, a SUMMA canister grab sample was collected from the dryer vent immediately adjacent to the driveway of the home. PCE odor was easily detectable and the PID meter pegged out when monitoring this vent. 23

24 PCE Levels at West Allis Home Date Sample Period Outdoor Air Indoor Air Excess Lifetime Cancer Risk Location 2/9/06 8 days 34 1-in-10,000 Roof Soffit 2/9/06 8 days in-1,000 Basement 3/8/06 24 hr 5 2-in-100,000 Front Porch 3/8/06 24 hr in-10,000 Basement 3/8/06 24 hr in-10,000 Kitchen 3/8/06 24 hr in-10,000 Bedroom 4/10/06 Grab 186,634 6-in-10 Concentrations in micrograms per cubic meter (µg/m3) Dryer Vent DPH determined that PCE presented a public health hazard for the residents living in the building. Grab sample from dryer vent surprised us the dry cleaner uses a 4 th generation dry-to-dry machine that recaptures PCE. 24

25 Background Levels of PCE Indoor Air Outdoor Air Median 90 th Pct Median 90 th Pct Shah & Singh * * Sexton, et al Kurtz & Folkes n/a n/a Zhu, et al * 75 th percentile Concentrations in micrograms per cubic meter (µg/m 3 ) DPH did a survey of expected background PCE levels in indoor & outdoor air. All the levels found at the West Allis home, indoor & outdoor, exceeded the expected background level of PCE by 1 order of magnitude or more. Outdoor air 5 ug/m3 at the home Indoor air ~ 200 ug/m3 25

26 Findings All indoor air PCE levels are >600 times above comparison value of 0.31 µg/m 3, poses an unacceptable increased cancer risk. not likely to cause non-cancer health effects. PCE in indoor air is a public health hazard. PCE in outdoor air is a public health hazard. Division of Public Health issued a memo with these findings. 26

27 May Visited with the dry cleaner & discussed his operations. The dry-to-dry machine is in the background. The plywood on the floor in the foreground covers the former PCE tank used for the coin operated dry cleaning machines in the 1960 s. 27

28 April A hole has been cut in the tank top. PCE was removed in the mid s, but the tank is still in place. Engineering reports say this is a 1000 gal tank, but by our observation, it appears to be smaller. We believe this tank is the major source of soil and groundwater contamination at the site. We don t know how the tank was connected or how PCE was disposed in the 1960 s. 28

29 April The owner told us that water levels in the tank fluctuate. Oily, floating material can be seen in this photo. No one has sampled water in the tank. Some PCE is likely off-gassing into the dry cleaner from this tank. The larger source of the PCE from the dryer vent, however, comes from current dry cleaner operations. 29

April 2006. DPH installed vapor sample ports manufactured by Entech Instruments in the basement of the home. A 1 in. countersink hole was drilled, followed by a 3/8 hole for the sampler.

30 April DPH installed vapor sample ports manufactured by Entech Instruments in the basement of the home. A 1 in. countersink hole was drilled, followed by a 3/8 hole for the sampler. The stainless steel sample port was inserted flush with the floor & sealed with a waterbased non-acrylic cement grout. Ports were closed with a stainless steel bolt and the recessed head was sealed with a rubber stopper. Tube dimensions: 3/8 inch diameter, 2 ½ inches long with a ½ inch diameter collar. 30

31 Port A southeast corner, where OVM was hung. Expected the highest concentrations here because it s the closest point to the buried PCE tank. Port B installed to determine how far vapors have migrated beneath the home. Soils very wet at this probe. Port C stairwell port. 31

32 32

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April 2006. 24 hours later, SUMMA canister samples were taken at the 3 ports.

34 April hours later, SUMMA canister samples were taken at the 3 ports. Vapors were purged from the port into a sample bag until the PID meter stabilized, then a 15 minute vapor sample was collected using a SUMMA canister. 34

35 PCE Levels in Soil Vapors Beneath West Allis Home Date Sample Period Sub-Slab Soil Vapor Basement Location 4/11/06 15 min 63,328 SE Corner ײ ײ 15 N. Rm ײ ײ 2,030,160 S. Central Concentrations in micrograms per cubic meter (µg/m 3 ) April There is a 5 order of magnitude variation in PCE concentration beneath the slab. The value of 2,000,000 µg/m 3 is the highest subslab concentrations we have observed in WI. 35

36 Additional Findings Vapor intrusion is a completed pathway in the home and coming from the dry cleaner. PCE levels in soil vapors beneath basement floor exceeded the IDLH poses a future urgent public health hazard. Sources of PCE to the home: -Subsurface vapor intrusion through the basement -Outdoor air PCE from current dry cleaner operations -Possible off-gassing of PCE from soils & groundwater 36

37 Recommendations Homeowner should As an interim measure, ventilate basement with fans. As a precautionary measure, visit family physician for medical checkup. Excavations in basement need to protect worker and resident health. 37

38 Recommendations (cont) Dry cleaner must: Shut down all venting on north side of building. Mitigate vapor intrusion impacts in home. Investigate for vapor intrusion in other nearby homes. Investigate unnecessary PCE exposures to their employee s workspace. The dry cleaner has undertaken all of these steps. 38

39 May 2006 Radon Abatement Contractors installed a sub-slab depressurization system in the West Allis home. 39

40 Installer was able to drill into the line of drain tile that lies beneath & surrounds the foundation of the home so that the depressurization system will draw vapors from the entire outer foundation. The installer s experience is that it takes about 7 months to dry out the soils beneath the slab & achieve full efficiency of the system. 40

41 Soil Sample beneath basement slab PCE = 3,000 µg/kg Indicates that PCE may have migrated to the home s foundation While the system was being installed, we took a grab sample of soil beneath the slab & had the sample analyzed for PCE. PCE in the soil was 3,000 µg/kg. 41

42 Effectiveness of Mitigation SUMMA canister results 1 month post-ssds installation PCE = 23 µg/m 3 Have not reached target level (0.31 µg/m 3 ), but concentrations have decreased 1 order of magnitude. Additional monitoring scheduled for this month and January The sub-soils beneath the slab are quite wet. The SSDS is expected to dry these soils & become more effective with time. 42

43 Conclusions The vapor migration pathway can pose a significant risk to residences and non-industrial businesses located next to dry cleaners. The VI pathway should be assessed at every property contaminated with volatile chemicals where potential receptors exist or may exist. In WI we are only beginning to assess the VI pathway. A survey of our staff showed that environmental consultants rarely include assessment of VI as part of a site investigation. In addition, few people (DNR staff & consultants) know how to conduct vapor investigations, how to interpret results, and are fearful collecting samples from within homes and businesses. 43

44 Conclusions Vapor intrusion is a concern in tight clay soils where chemical solvents can move through preferential pathways and by diffusion to nearby receptors. Measures to divert vapor intrusion into a home basement have addressed immediate risk but have not yet achieved target risk levels. People sometimes dismiss the possibility of vapor intrusion in clay soils. Standard Site Conceptual model (vapors emanate from groundwater to home) doesn t fit clay soils with shallow groundwater. At this site, the source area extends to the home. PCE has likely been in the soils for 2 to 4 decades, more than enough time to diffuse through clay soils and move through preferential pathways. It appears that PCE contaminated soil is in contact with the foundation of the home, so it is difficult to know how effective the SSDS will be. Usually the SSDS is relied upon to interrupt vapor migration emanating from groundwater, but this does not appear to be the main pathway for vapor intrusion at this site. 44

45 Conclusions Further cleanup of soil will be necessary to address the long-term risks posed to the home residents by the PCE release. Vertical and horizontal extent of soil contamination in the source area needs to be defined. Future investigation will determine whether PCE solvent has migrated to the foundation of the residence. 45

FACTS ABOUT: Vapor Intrusion

Maryland Department of the Environment FACTS ABOUT: Vapor Intrusion The Land Restoration Program (LRP) is charged with assessing and cleaning up uncontrolled hazardous waste sites throughout Maryland to