Ken Foster Farm Investigation Update

Transcription

1 DEQ Staff 5/15/14 City of Sherwood Community Room Mark Pugh, Project Manager Mike Poulsen, Toxicologist DEQ Environmental Cleanup Program

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3 Presentation Outline Abbreviations/Definitions Background Information Chromium Characteristics Site History Previous Work DEQ Remedial Investigation -2013/2014 Samples Collected Results Risk Assessment Next Steps and Schedule Question and Answer Session

4 Abbreviations and Definitions CrVI-hexavalent chromium CrIII-trivalent chromium Total Cr = CrVI + CrIII (mostly CrIII) mg/kg milligrams of something per kilogram soil =part per million (ppm) ug/l micrograms per liter = part per billion(ppb) Risk-Based Concentration (RBC) Exposure to this amount over 30 year period is equal to 1 in a 1,000,000 excess cancer risk. = DEQ Acceptable Risk Level No Further Action (NFA) Determination

5 Chromium Characteristics Chromium is a common crustal element Occurs in the environmental in either trivalent form (CrIII) or hexavalent form (CrVI) CrIII is predominant form (blue/green) Very low solubility CrIII is an essential nutrient, and has a very high Risk-based Concentration (RBC) of 120,000 mg/kg

6 Chromium Characteristics (cont d) CrVI (plating, stainless steel production; tanneries) Sodium Dichromate CrVI is very soluble, more toxic than CrIII very low RBC of 0.29 mg/kg for residential exposure CrVI requires specialized analysis to ensure reliable results

7 Site History Ken Foster Farm Site Historical farm land covering approximately 40 acres, ~3/4 mile south of Frontier Leather Site Thin soil horizon and shallow basalt bedrock Tannery waste (with chromium, mercury) was placed on the ground surface between ; lime added to control odor; tilled into soil Farm land initially subdivided into 10 parcels and developed in the late 70s- mid-80s ; additional subdivision for single family residential use Approximately 3 acre wetland area

8 Background Information (cont'

9 Background Information (cont'

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13 Previous Work Ken Foster Farm DEQ (2005) Preliminary Assessment EPA (2006) Soil Results Total Chromium up to 58,900 mg/kg (ppm) Mercury up to 118 ppm Hexavalent chromium Cr(VI) results not reliable, but well below risk-based standards at the time. Groundwater Results Hexavalent chromium (CrVI) results not reliable, but reported concentrations were well below risk-based standards at the time. No Further Remedial Action under EPA Superfund Program 2007 DEQ Completes Risk Assessment

14 Previous Work Ken Foster Farm 2010-DEQ begins Settlement Negotiations with Responsible Parties (Linke Enterprises,Wells Fargo) Global settlement between parties reached in May 2011 $2,600,000 cash payment from parties for cleanup at Ken Foster Farm and Frontier Leather Site Settlement challenged by third party; Court approves settlement Court decision appealed December 2013-Court Issues Final Decision approving settlement

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16 Previous Work Completed (cont d) 2011-DEQ Adopts New Risk-Based Concentrations for Cr(VI) Residential RBC for soil changes from 38 mg/kg (ppm) to 0.29 mg/kg (factor of 130 times lower) RBC for drinking water changes from 110 ug/l (ppb) to ug/l (factor of 2500 times lower) Additional Investigation necessary to evaluate CrVI

17 Phase I August-September 2013 Phase II-November 2013 Groundwater Three on-site wells tax lots 100, 700, 1300 City of Sherwood well across Murdoch Residential well located 1 mile west of Site (background) Soil-350 samples Ken Foster Farm DEQ Remedial Investigation Off-site Soil-11 samples from three different City properties Sediment- 16 samples

18 Groundwater Results Three on-site wells tax lots 100, 700, 1300 Cr(VI) above RBC in one well Below RBC or not detected in two other wells City of Sherwood well Cr(VI) not detected Residential well (background) Cr(VI) not detected

19 Soil Sampling Collected on 75-foot grid (10 samples/acre) Additional samples collected in high use areas around existing homes Soil Results Ken Foster Farm DEQ Remedial Investigation CrVI detected in majority of on-site samples above the RBC-both shallow and deep Two background soil samples were above the RBC CrVI not correlated with total chromium

20 DEQ Remedial Investigation

21 Insert BG location map 0.76 mg/kg Ken Foster Farm 0.96 mg/kg Off-site Soil Sampling 0.29 mg/kg

22 Excess Cancer Risk for Chromium(VI) in Soil Chromium(VI) Soil Exposure Concentration Excess Cancer Risk (per million) Decision Unit Risk-Based Conc A B Local Background C D E F G H I J K L M N O

23 Next Steps Complete Draft Final RI Additional investigation Off-site properties adjacent to the south To the east of the wetland Tax Lot 1000 development Plan for three parcels DEQ will require 1-foot clean soil cap or cover with hardscape Plans have not been submitted Public Comment Period

24 DEQ Selects Remedy-Spring 2015 Public Comment EPA Status on Re-evaluating CrVI Feasibility Study Ken Foster Farm Next Steps Evaluate Remedies to address unacceptable risk o Removal o Partial Removal with capping o Treatment and capping o Priority for Current Exposure o Pilot Tests for soil treatment with EPA- Biochar o Feasibility Study Complete Winter 2014

25 Project Contact DEQ c/o Mark Pugh Northwest Region Office 2020 SW 4 th Ave., Suite 400 Portland, OR (503) pugh.mark@deq.state.or.us