Vapor of the Lead Scavenger of the 1,2 Dichlorothane (EDC ... · Method 8260 analyses

Vapor Intrusion of theLead Scavenger

1,2‐Dichloroethane at LUFT Sites

Paul McCaw and Thomas Rejzek, PGSanta Barbara County Environmental

Health Services, LOP

Vapor Intrusion of the Lead Scavenger

1,2‐Dichlorothane (EDC) at LUFT Sites

Thomas Rejzek, P.G. and Paul McCawSanta Barbara County Public Health Department

Environmental Health ServicesLocal Oversight Program

EDC Chemical Structure & Properties

• C2H4Cl2• Elemental Composition

Carbon 24.27%, Hydrogen 4.07%, Chlorine 71.66%

• Flash Pt = 12.9‐18 oC• BP = 83.44 oC• H2O SOL = up to 9200 mg/L• Henry’s Law = 0.04• VP = 12 mm Hg @ 25oC• Log Koc = 1.58

Environmental Fate & Transport

• Chemical Properties of EDC indicate it is highly mobile in the environment.

– The solubility shows that it can dissolve in water at concentrations 10,000 X the MCL

– The low log Koc indicates it is highly mobile in soil and available for transport into groundwater

– The VP & Henry’s Law Constant indicate EDC can readily partition from water or soil to air

MCLs, Soil and Vapor Screening Criteria, Analytical Methods & MDLs

MCLs & Screening LevelsWATER• Federal MCL = 5 µg/L• California MCL = 0.5 µg/L

SOIL• RSL Soil = 0.46 mg/kg• ESL Soil = 0.0045 mg/kg

SOIL VAPOR & INDOOR AIR• RSL Air = 0.11 µg/m3

• ESL Soil Vapor = 58 µg/m3

• ESL Air = 0.12 µg/m3

Analytical Methods & MDLsWATER• 8260B MDL = 0.5 µg/L• 8011 MDL = 0.01 µg/L

SOIL• 8260B MDL = 0.005 mg/kg

SOIL VAPOR & AIR• 8260B MDL = 100 µg/m3

• TO‐15 MDL = 0.4 µg/m3

• Lower w/TO‐15 SIM

Introduction – History of Lead Scavengers in Motor Fuel

• 1925 ‐ Ethylene dibromide (EDB) 1st added to Gasoline as a Lead Scavenger

• 1940s ‐ 1,2‐dichloroethane (a.k.a. ethylene dichloride or EDC) used due to lower cost

• 1996 ‐ Addition of EDC & EDB to gasoline phased out concurrent with the phase‐out of leaded gasoline

• EDC & EDB still used as lead scavenger in Aviation gas & racing fuels

Introduction – EDC at LUFT Sites• U.S. EPA Office of Underground Storage Tanks forms Lead

Scavengers Team publishes three documents

– 2006: Lead Scavengers Compendium: Overview of Properties, Occurrence, and Remedial Technologies (EPA, May, 2006). Among others cited data from Santa Barbara County LUFT sites.

– 2008: Natural Attenuation of the Lead Scavengers 1,2‐Dibromoethane (EDB) and 1,2‐Dichloroethane (1,2‐DCA) at Motor Fuel Release Sites and Implications for Risk Management (EPA, September 2008).

– 2010: Memo – Recommendations for States, Tribes and EPA Regions to Investigate and Clean Up Lead Scavengers When Present at LUST Sites (EPA, May 2010)

Introduction – EDC at LUFT Sites (cont.)

• U.S. EPA’s Lead Scavenger Team documents primary focus is on groundwater impacts and risks.

• 2010 Memo ‐ “…OUST has become aware that certain, sometimes significant, risks at LUFT sites may not be adequately addressed under current practice.”

• The California SWRCB LTCP does not include screening for EDC or EDB

Summary of 2010 EPA Recommendations for On‐Road Gasoline Sites

Recommendation to Sample & analyze for

EDB & EDC

Recommendation to sample & analyze for

EDB and EDC Dependent Upon:

Recommendation to sample & analyze for EDB and EDC only at sites where leaded fuels are stored (off‐road racing fuel, aviation gas)

‐ UST's Storage History

‐ Threat to Drinking Water Resources

<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐1986<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐>1996‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐>Years of Storage

EDC at California LUFT Sites

• Per Geotracker EDC has been detected in groundwater > Cal‐MCL at 2,994 LUFT sites in California

• The Number of California LUFT sites that have NOT been assessed for EDC & EDB but should be per EPA recommendations is unknown and includes closed cases

• Soil Vapor or Indoor Air data has only been collected at 148 California LUFT sites

EDC at Santa Barbara County LUFT Sites

• 632 LUFT Sites in Santa Barbara County

• Historically both Central Coast Analytical and ZYMAX Labs included EDC & EDB in EPA Method 8260 analyses

• EDC has been detected at 131 sites (excludes historic sites w/out EDFs in Geotracker)

• EDC Concentrations in groundwater range from 0.13J – 5,880 µg/L

EDC Toxicity

• U.S EPA and California Potential Human Carcinogen

• Non‐Cancer effects include liver and kidney toxicity, central nervous system effects & others

• Cancer Slope Factor = 9.1E‐02 (mg/kg‐day)‐1

• Non‐Cancer Reference Dose = 6E‐03 mg/kg‐day

Case Study #1

• 101 E. Victoria, Santa Barbara

• Global ID #T0608344098

• VI threat to redevelopment

History/Overview

• Operated as a service station from 1925 to ~1955• Groundwater depths ranged from ~50 to ~65 feet bgs

• Lithology consists of alluvium, with interbedded clays, silts, sands, gravels, and cobbles.

• Gasoline related soil impacts detected from 25 to 80 feet bgs. Contamination observed in fine and coarse grained lithology.

• Site remediation by Soil Vapor Extraction

Groundwater/Soil Data

• EDC in Groundwater: Historically ranged from 2 to 41 ug/L; tested from 1993 to 2012.

• EDC in soil: 238 samples analyzed for EDC with only 1 detection at 0.0021 mg/kg. However, elevated reporting limits in some samples (up to <0.11 mg/kg) likely masked detections.

Groundwater Flow Direction

EDC in Groundwater

Soil Vapor• 3 Multi‐depth probes installed, with probes at 5, 20, & 48 feet bgs.

• 29 soil gas samples collected– Highest EDC seen in 48 foot probes at concentrations up to 3,000 ug/m3; reporting limits range from <5 to <300 ug/m3; Coarser grained lithology at this depth.

– In 20 foot probes, EDC up to 160 ug/m3; Reporting limits range from <5 to <100 ug/m3.

– In 5 foot probes, EDC up to 16 ug/m3; Reporting limits range from <5 to <100 ug/m3.

– EDC below reporting limits in post‐remediation vapor samples (<15 ‐ <100 ug/m3).

Soil Vapor Sample Locations

Observations/Conclusions

• EDC generally not seen in soil data; this may be related to elevated reporting limits.

• EDC in groundwater was <50 ug/L• Potential for vapor intrusion risk if DTW was within 40 vertical feet of surface.

• Observed a vertical attenuation with decreasing depth in pre‐remediation vapor samples.

• Remediation (SVE) appears to have also reduced EDC in groundwater and soil vapor.

Case Study #2

• 803 N. Milpas St.Santa Barbara

• Global ID #T0608300233

• VI threat to redevelopment

Overview/History• Operated as a Service Station from pre‐1970's to 2004• Groundwater depth ranged from surface to ~11 feet bgs. Perched zone to ~16 feet bgs, aquiclude from ~16 to ~20 feet bgs, and shallow aquifer under artesian conditions at depths >~20 bgs.

• Lithology consists of alluvium, with interbedded clays, silts, and sands.

• Gasoline related soil impacts detected from ~10 to 30 feet bgs. Contamination observed in fine and coarse grained lithology.

• Site remediation by over‐excavation, groundwater pump and treat, and oxygenation of aquifer.


• EDC in Groundwater: 0.5J ‐ 1,410 ug/L, tested from 1995 to 2012, EDC mainly located in offsite wells

• EDC in soil: 278 samples analyzed for EDC. 36 detections, ranging from 0.001J to 0.032 mg/kg. However, elevated reporting limits (up to <2.5 mg/kg) may have masked lower concentrations. About half of the EDC detections were J‐Flagged results, indicating very low concentrations.


EDC Plume

Soil Gas

• Soil gas: 13 vapor probes installed at the site at 5 feet bgs. 22 soil gas samples

• Soil vapor: 8 samples <5 ug/m3 (TO‐15), 17 samples <100 ug/m3 (8260)

• Also collected 2 ambient air samples, with EDC <2.3 ug/m3



• EDC detected at very low concentrations in soil. About half were J‐Flagged results, indicating very low concentrations. Elevated reporting limits may mask EDC in soil.

• EDC was detected in groundwater at low concentrations (<10 ug/L) across most of the site. The highest EDC concentrations were in offsite wells due to either offsite sources or onsite remediation. Onsite remediation appears to have also reduced EDC in groundwater on site.

• EDC was not detected in soil vapor samples. Acceptable reporting limits were obtained using using TO‐15, not with 8260.

• Ambient air reporting limits for EDC were ~20x over its ESL• Site okay for mixed use redevelopment

Case Study #3

• 6930 Hollister, Goleta

• Global ID#s T0608300075T0608300604

• VI threat to offsiteDevelopment

Overview/History• Operated as a Service Station from the mid‐1960s to 2007

• Groundwater depth ranged from ~24 to ~51 feet bgs• Lithology consists of alluvium, with interbedded silts and clays overlying coarser sandy materials.

• Gasoline related soil impacts detected from 3 ‐ 30 feet bgs. Contamination observed in fine and coarse grained lithology.

• Site remediation by over‐excavation, soil vapor extraction, and ozone sparging.

• Original LUFT case (1991 – 1995) did not test for EDC


• EDC in Groundwater: 0.21J ‐ 820 ug/L, tested from 1999 to 2014 (not tested in original LUFT site)

• EDC in soil: 115 samples analyzed for EDC. 9 detections up to 0.43 mg/kg. However, elevated reporting limits (up to <12 mg/kg) may have masked lower concentrations.


EDC Plume

Soil Gas

• Soil gas: 1 Multi‐depth probe installed offsite at 5 & 10 feet bgs. 2 soil gas samples collected in 2014 to evaluate vapor intrusion potential for site redevelopment.

• EDC in both samples <3 ug/m3, used TO‐15.• Depth to water was ~30 feet bgs.• Soil vapor probe placed near the plume hotspot.

Soil Vapor Sample Location


• EDC Not tested in original LUFT Site. • EDC seen in a limited number of soil samples at concentrations less than 0.5 mg/kg. Lack of detections may be related to elevated reporting limits.

• EDC in groundwater reduced on site by remediation, highest concentrations of EDC now offsite in downgradient direction.

• EDC not detected in soil vapor in the vicinity of the offsite plume.

• Redevelopment of offsite area okay

Case Study #4

• 4699 Hollister AvenueGoleta

• Global ID#T0608300400

• VI threat to Off‐Site Residences

Overview/History

• Public utility maintenance yard with multiple USTs in service from 1960 to 1988

• Groundwater depth ranged from ~5 to ~28 feet bgs

• Lithology consists of alluvium, primarily with interbedded clays and silts.

• Gasoline related soil impacts detected at depths of up to 25 feet bgs.

• Site remediation by over‐excavation, soil vapor extraction, groundwater pump and treat, and aquifer oxygenation.


• EDC in Groundwater: EDC historically ranged from 0.285J ‐ 760 ug/L, tested from 1988 to 2013. EDC plume has migrated offsite under residences.

• EDC in soil: 100 samples analyzed for EDC. 21 detections at concentrations up to 3 mg/kg. However, elevated reporting limits may have masked lower concentrations.


EDC Plume

Soil Gas

• Soil gas: The J&E model evaluation suggested that there may be a vapor intrusion risk to the residences. A soil vapor survey was performed near the residences. Vapor samples were collected at 2 and 8 feet bgs. EDC was detected in groundwater at concentrations up to 112 ug/L in the area of the vapor samples. 7 soil gas samples were collected

• EDC was not detected, <8 ug/m3 (8260B)



• With the exception of 2 soil samples, EDC was detected at concentrations of less than 1 mg/kg. Lack of EDC detections may be related to elevated reporting limits.

• EDC in groundwater migrated offsite. Remediation reduced the concentrations of EDC in groundwater onsite.

• EDC was ~100 ug/L in offsite wells with the depth to water of ~12 feet bgs. EDC was not detected in soil vapor samples from this area.

• Vapor Intrusion not a concern to the residences.

Case Study #5

• 100 S. La Cumbre, Santa Barbara• Global ID# T0608300588

• VI Threat to Redevelopment

Overview/History

• Service station from 1930’s (?) to 2005• Groundwater depth ranged from ~15 to 47 feet bgs

• Lithology consists of alluvium, with interbedded clays, silts, and sands.

• Gasoline related soil impacts detected at depths of up to 40 feet bgs

• Site remediation by over‐excavation, soil vapor extraction, and groundwater pump and treat.


• EDC In Groundwater: EDC historically ranged from 0.13J ‐ 78.4 ug/L, tested from 2002 to 2014. EDC plume to the south of the site near the former dispenser island. Historical LNAPL on Northwest corner of the site

• EDC In Soil: 64 samples analyzed for EDC. No detections in soil, with reporting limits ranging from 0.005 to 0.13 mg/kg.


EDC Plume Map

Soil Gas

• 10 Soil vapor samples collected in 2006 at 8 locations

• EDC was <0.05 ug/m3 in 5 locations and detected at 12 ‐ 1,200 ug/m3 in 3 locations. Depth to groundwater ~12 during this sampling event.



• EDC not seen in soil samples• EDC not seen in soil vapor samples collected from areas of tank excavation. EDC seen in areas with historical free product (MW‐4,. 110 ug/m3) and EDC plume hotspot with residual soil contamination (MW‐5, 1,200 ug/m3).

• Due to redevelopment, vapor samples will be collected in 2015. A soil vapor mitigation system will be installed with the new building.

Presentation Conclusions

• Assess sites for EDC & EDB if:– Tanks were in use prior to 1996 & especially prior to 1986

– Tanks were used to store aviation or racing fuels– If groundwater samples have not been analyzed with EDC reporting limits <0.5 ug/L

– Evaluate VI pathway at sites with EDC in shallow groundwater or soil

Presentation Conclusions (Cont.)

• EDC, when detected in soil, was generally at concentrations of less than 1 mg/kg. Elevated reporting limits may mask EDC in soil.

• EDC can remain in groundwater without significant reductions for decades without treatment (i.e. natural attenuation is very slow)

• EDC in groundwater does respond to remediation such as pump and treat and oxidation. However, detached plumes may be created if the ROI of the treatment does not encompass a majority of the plume.

Presentation Conclusions (cont.)• For Soil Vapor samples, ensure your lab can meet the target reporting limits. EPA Method 8260 may not achieve acceptable reporting limits. TO‐15 will achieve acceptable reporting limits but may need to be run w/selected ion monitoring (SIMs).

• If using soil vapor extraction at sites with EDC, analyze influent vapor samples for EDC, especially if using thermal or catalytic destruction.

Presentation Conclusions (cont.)

• EDC was not detected in soil vapor at 3 of the 5 sites. These sites had EDC in the groundwater, but did not have soil contamination in the area of the vapor samples.

• EDC was detected in soil vapor at 2 of the 5 sites. These sites had EDC in the groundwater along with soil contamination in the area of the vapor samples.

Presentation Conclusions (Cont.)

• One site had EDC in soil vapor despite it not being detected in vicinity soil and groundwater samples.

Conclusions (Cont.)

• Generalizations regarding EDC vapor intrusion risks should NOT be made based on these sites:– Due to small population size of only 5 sites and– EDC was detected in soil vapor at sites with varied soil types and depths to groundwater.

References

• Lead Scavengers Compendium: Overview of Properties, Occurrence, and Remedial Technologies (EPA, 2006). http://www.epa.gov/oust/cat/PBCOMPND.HTM

• Natural Attenuation of the Lead Scavengers 1,2‐Dibromoethane (EDB) and 1,2‐Dichloroethane (1,2‐DCA) at Motor Fuel Release Sites and Implications for Risk Management (EPA/600/R‐08/107, September 2008) http://www.epa.gov/ada/download/reports/600R08107/600r08107.pdf

• Memorandum – Recommendation for States, Tribes and EPA Regions to Investigate and Clean Up Lead Scavengers When Present at Leaking Underground Storage Tank (LUST) Sites. (EPA, May 21, 2010) http://www.epa.gov/oust/cat/lead_scavengers_memo_05212010.pdf

References (cont.)

• U.S. EPA Regional Screening Level Table, November 2014. http://www.epa.gov/region9/superfund/prg/

• Environmental Screening Levels, Interim Final, December 2014. http://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/esl.shtml

• California Human Health Screening Levels (CHHSLs), January 2005 http://www.lacba.org/Files/Main%20Folder/Sections/Environmental/Files/Use%20of%20CHHSLs%20in%20Evaluation%20of%20Contaminated%20Properties.pdf

• State Water Resources Control Board Low‐Threat Closure Policy. http://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2012/rs2012_0016atta.pdf

AcknowledgementsThanks to:

my co‐author Paul McCawAnd Power Point Wiz Sienna Parsons

Documents

Vapor of the Lead Scavenger of the 1,2 Dichlorothane (EDC ... · Method 8260 analyses