1. Brownfield Corrective Action with Revised RRS
GBA WORKSHOP
April 23, 2019
R. Jessica Turner, PG and
Shanna Alexander, MS, MPH, DABT

2. CASE STUDY TIMELINE
Early 1970s – 2017: Commercial automotive and heavy equipment repair facility
Spring 2013: Four USTs removed that had contained diesel fuel and gasoline
Fall 2017: Phase II identified VOCs in soil and groundwater
December 2017: Site entered into Georgia Brownfield program
Need new photos

3. Site LAYOUT GPR Survey Located subsurface features Samples
Blue – Soil and GW
Green – Soil (Surf and Subsurface)
Yellow – Surface Soil
Blue locations – soil and groundwater
Yellow locations – surface soil samples only
Green locations – surface and subsurface soil samples

4. TWO AREAS ABOVE TYPE I RRS
Spring Brownfield site investigation identified VOCs, SVOCs, and metals in soil and groundwater
Identified two areas with metals impacts above former Type 1/2 RRS

5. DELINEATION SAMPLING
PPCAP Addendum requested that delineation sampling be used to define extent of excavation rather than confirmation sampling
Reduced excavation field time and eliminated need for quick-turn laboratory sampling

6. EXCAVATION DELINEATION

7. Corrective Action Summary
AF-20 – Arsenic impacted area
Excavation of approximately 16 by 20 feet, with a measured excavation depth of 4 feet
~22 tons of impacted soil
AF-25 – Mercury impacted area
Excavation was approximately 10 by 10 feet with a measured excavation depth of 4 feet
~12 tons of impacted soil

8. ANALYTICAL DATA COMPARISON

9. Previous vs current HSRA rrs approach
Previous (before Sept. 2018)
No provision for soil area averaging
“Point-by-point” compliance only
No provision for site-specific in vitro bioaccessibility (IVBA)
Empirical data not allowed as line of evidence to support substance not leaching
No provision for anthropogenic background
Current (after Sept. 2018)
Provision for soil area averaging
Type 2 & 4 only; not for groundwater
No provision for site-specific in vitro bioaccessibility (IVBA)
Allows use of empirical groundwater data to support leaching is not occurring
Provision for the use of anthropogenic background
Provision to include soil area averaging
Applies to soil only
Provision for the use of site-specific IVBA for arsenic in soil
Allows use of empirical groundwater data to support elimination of leaching pathway
Provision for anthropogenic background

10. Benefit #1: soil area averaging approach
Compliance with the Current Type 1 & 2 Soil RRS
Parameter (mg/kg)
PCE
TCE
Xylenes
Benzo(a)pyrene
Max. Result
0.34
0.3
264
1.57
Soil Averaging (Type 2)
0.13
0.12
190
Current Type 1
0.18
198
1.2
Bottom line: Not a “one-size-fits-all” approach
Statistical averaging may or may not help with achieving compliance with the Type 2 RRS

11. Benefit #2: Arsenic Site-specific RELATIVE Bioavailability (RBA)
Soil ingestion pathway drives risk
Use of site-specific IVBA tests to predict bioavailability reduces uncertainty in the risk assessment
USEPA’s recommended default RBA for Arsenic = 0.6 (2012)
Arsenic speciation (Electron Microprobe analysis) for source determination
May result in more rational use of resources while still remaining health-protective
Image courtesy of ITRC

12. Arsenic BIOAVAILABILITY OVERVIEW
Bioavailability ≠ Bioaccessibility
In Vivo In Vitro Correlation (IVIVC) of a site-specific IVBA method is required prior to use in risk assessment
High affinity of arsenic to iron oxides in iron rich soils
Guidance available from USEPA and Interstate Technology & Regulatory Council (ITRC 2017)
USEPA sampling guidance for soil RBA assessments available (2018)
Good
x Bad

13. Application of arsenic site-specific rba on Type 2 (direct contact) soil rrs
Cancer Risk
Non-Cancer Hazard
RBA = 0.14 (for purposes of this exercise, it is assumed RBA is the average RBA from sites previously evaluated in GA)
Future Resident risk estimates were below GA EPD’s risk thresholds of 1E-05 and THQ of 1.
Soil average concentration was below the RBA-adjusted Type 1 & 2 Soil RRS of 21 mg/kg (vs non-adjusted Type 2 RRS of 6.8 mg/kg)
Avoids removal of 34 tons of soil = $$$ (cost-benefit analysis)

14. Benefit #3: use of empirical data to evaluate leaching potential
Current provisions for the use of empirical groundwater data to support leaching is not occurring
Low Mobility – historic data has been non-detect or below residential standards for a significant amount of years
Deep Aquifer – depth to groundwater useful as a line of evidence
Image courtesy of Shanna Alexander

15. TAKE home message
More flexible options available to support brownfield cleanup under current HSRA regulatory framework
Soil averaging, site-specific bioavailability, use of empirical groundwater data, anthropogenic background, and others
Not a “one-size-fits-all”
General trend indicates stricter standards for volatiles, but typically less stringent standards for metals and PAHs
Soil averaging could possibly offset the lowering of the RRS for VOCs
Possible reduction in delineation, O&M and/or cleanup costs
Early “buy-in” and frequent communication with GA EPD Brownfield Program recommended

16. Questions?