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1 <br /> <br /> <br /> <br />1 <br />1 <br /> <br /> <br />r <br /> <br /> <br />~' <br /> <br />1 <br /> <br /> <br /> <br />I <br />Addendum to CDH Soil Plutonium"9+240 Surveys 1970-1991, Love, June, 1994 <br />a. Dose: Released and Risk <br />Task 4: 13valuation of Historical Environmental Data, Progress Report, December 1993, Phase II <br />Toxicity Assessment acrd Risk Choracterizarion, of The Rocky Flats Dose Reconstruction <br />Project provides details and summaries of DOE contractor, CDH and other air sampling results. <br />Their question is , "Were concentrations onsite generally greater than concentrations measured <br />offsite?" I CDHd; ChemRiskb) This report provides some initial presentations of the data and <br />starts to Explore the subtleties in the data. Figures are provided that show consistently higher air <br />concentrations onsite, both DOE contractor and CDH data. The data support a trend of reducing <br />air concenntrations over time at offsite locations. <br />The Projf:ct Task 8, Draft Report, Dose Assessment for Hrstorica! Co~rlaminan! Releases from <br />Rocky FGTIs, estimates exposure to the public at large from plutonium23+2/0 due to releases form <br />the 903 Pad from 1965-1969. (ChemRiskb) Exposures are estimated in Sectors radiating from <br />the present Rocky Flats boundary. There is substantial reduction of exposure both as a function <br />of distant:e and direction from Rocky Flats however all exposures were considered to be low <br />(ChemRi:;kb). <br />5. Unpublished Data and Reports, Ecology <br />The Colorado Department of Health Air Pollution Control Division started monitoring ambient air <br />around th.e Rocky Flats Plants in 1992. Their unpublished data supports the very low <br />concentrations of plutonium2"+240 at the present boundary of Rocky Flats (Fox et al; in review). <br />Operable Unit 3 reservoir sediment for Standley Lake are not now available to confirm Hardy's <br />findings (USDOEa). <br />Soil solute transport studies and infiltration data in and around the 903 Pad do not support the <br />existance of plutonium transport mechanisms to groundwater (Litaor 1993, USDOEb) The <br />study doers hypothesis a biological mechanism of transport within the soil horizon containing <br />biological) activity. Earthworms are under further study as a mechanism of transporting plutonium <br />from the original surface through the present overburden placed during cleanup of the 903 Pad <br />area. Channels created by cracked clay, burrowing and roots do appear to exist but do not now <br />represent a significant mode of transport as tested. (USDOEb) This study and follow up research <br />presently continuing suggest that the transport of plutonium "9210 is limited to the upper 30 cm of <br />soil. (USDOEb). <br />1 <br />