LDEQ RECAP Miscellaneous Topics

Exposure Assessment n Site-specific under MO-3 only n Construction worker scenario n Greatly reduced ET, EF, and/or ED n Site-specific data should be documented

Exposure Assessment n Absence of site-specific data  Default values n Permanent vs non-permanent structures n Enclosed structures

Exposure Assessment Additional exposure considerations when the site- specific GW2 or GW3 DAF is large: n Construction worker exposure n Volatile emissions to ambient air (GW air ) n Cross-media transfer - migration to deeper zones

Toxicity Assessment n Unavailability of toxicity values  Develop a toxicity value(s)  Identify a surrogate toxicity value based on structure/activity and/or targets  Route-to-route extrapolation  Qualitative evaluation

Toxicity Assessment nNo speciation data ex) Cr +3 vs Cr +6 nNew slope factor ranges in IRIS nDermal toxicity values  If GI absorption efficiency < 50%  adjust oral tox value  If GI absorption efficiency > 50%  do not adjust  RAGS HHEM Supplemental Guidance Dermal Risk Assessment Interim Guidance (EPA 1998)

Background Data n Where should samples be collected? n How many samples??? n How should the data be used?  Calculate arithmetic average  Obtain Department approval  Compare to arithmetic average for AOI n What if there are high anthropogenic bg levels???

TPH Issues nTPH-G, TPH-D, and TPH-O  Physical/chemical properties presented  Soil sat and Water sol not applicable  Target organs/critical effects identified

Wet Weight vs Dry Weight nData is routinely reported on wet-weight basis nWet weight used for exposure concentrations nDry weight used for EF&T calculations nWet weight  Dry weight

Soil to Groundwater Pathway SPLP Data nWhere should SPLP samples be collected? nHow is the SPLP data used to evaluate the soil to gw pathway?  Soil GW1 : Compare SPLP to GW 1 x DF Summers  Soil GW2 : Compare SPLP to GW 2 x DF Summers x DF2  Soil GW3 : Compare SPLP to GW 3 x DF Summers x DF3

Soil to Groundwater Pathway SPLP Data  If SPLP <, then screen out soil to gw pathway  If SPLP >, then delineate area of concern  SPLP vs TCLP  SPLP vs LRS

Estimation of S d S d = Thickness of impacted groundwater within permeable zone Un-impacted groundwater 10’ 15’ Impacted groundwater 5’ S d = 5’

Estimation of S d S d = Thickness of permeable zone if thickness is not known or if the zone is not impacted Un-impacted groundwater 10’ 15’ S d = 15’

Alternate RS nMO-3 only nTechnically impracticable and/or economically infeasible ONLY nCorrective Action Study nRequires Department Approval

Workplans nRequired for MO-3 nRecommended for some MO-2 nThe more detailed, the better  Id of AOI/COCs  CSM  Id of approaches/methods  Id of assumptions/site-specific and default inputs

Fractional Organic Carbon Fractional Organic Carbon (foc) -Estimated by dividing the percent organic matter (POM) by a conversion factor of 174 -POM determined using ASTM D2974 -Samples should be collected from a non- impacted area at a depth consistent with the depth of impact - Default foc = 0.006