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

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

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

TWO AREAS ABOVE TYPE I RRS Spring 2018 - Brownfield site investigation identified VOCs, SVOCs, and metals in soil and groundwater Identified two areas with metals impacts above former Type 1/2 RRS

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

EXCAVATION DELINEATION

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

ANALYTICAL DATA COMPARISON

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

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

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

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

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)

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

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

Questions?