Document ojRj5dD1zYYmnw0kEQ5aqjQw

Relevance of Soil Sampling in Site Screening Level Assessments for PFOA October 22,2003 AR226-2347 I Discussion Topics Review soil sampling key learning's Present site screening level assessment conceptual model g O to 0> Ul H EXP015812 Messages For Today | Soil sampling is not critical to site screening level assessments designed to evaluate | overall human and environmental exposure at a PFOA use facility. * Water monitoring should focus on site boundaries, key discharge points, or where wg potential exposure is occurring. 0 tO a<01\ to EXP015813 PFOA P/C Characteristics PFOA displays high water solubility - 1000 mg/L (Kissa, 1994) - >10% (3M, 2001) PFOA displays low adsorption capacity in all soil types (3M & APME Studies) - Similar to other highly mobile chemicals (see Koc chart) s SB oNJ m 'j w u EXP015814 Koc Comparison Comparison of Koc's for PFOA and Other Chemicals Napthalene --------------- C ap e F ear (A P M E , 2003) Drum m er (A P M E , 2003) -- 4 Hidalgo (A P M E , 2 0 0 3 ) 4 -------4 Keyport (A P M E , 2 00 3) 4--,4 Wilmington Sludge (A P M E , 2003) S Methylene Chloride O IO A Brill Sandy Loam (3M , 1978) _________ , _______ ,-------------------------- - c\ si I 0 200 400 600 800 1000 1200 Koc (mL/g) EXP015815 Soil Sampling Key Learning's I Our extensive soil sampling database from Washington Works shows: --Overall low concentrations, won't build-up --Air deposited PFOA readily dissolves and migrates via water movement (sw/gw) Most surface soils <50 ug/kg --All results significantly below CATT screening level of 240,000 ug/kg o N at -d Ul U1 EXP015816 Site Screening Level Assessment Conceptual Model Ba 0 to 0) U1 01 EXP015817 PFOA Site Screening Level Assessment Conceptual Model - Compiled using extensive modeling and monitoring conducted at Washington Works - Considers realistic potential exposure points to focus screening level assessment monitoring Facility water discharges Groundwater at site or discharge boundaries I - Soil is not a key monitoring point o N Ul sj EXP015818 SCREENING LEVEL ASSESSMENT MODEL AIR EMISSIONS t= > <==5, % AQUEOUS DISCHARGE ^-r /~ * S W M U \ ttl UNSATURATED SOIL AQUEOUS DISCHARGE -- MX RIVER / l UNSATURATED SOIL yt y tv GROUNDWATER o POTENTIAL SCREENING LEVEL ASSESSMENT MONITORING POINTS M cn 0 FACILITY AQUEOUS DISCHARGE (OUTFALLS) ui oo (2 ) SURFACE WATER (RIVERS, PONDS, STREAMS ETC.) *SW M U = SOLID WASTE MANAGEMENT UNIT GROUNDWATER (MONITORING WELLS, PRODUCTION WELLS ETC.) EXP015819