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• O Mr. Ron Rowe <br /> Page 3 of 4 <br /> � x \v <br /> custody for analysis of total petroleum hydrocarbons as gasoline (TPHg) using EPA Method <br /> 8015; and for benzene, toluene, ethylbenzene, and total xylenes (BTEJ ), and methyl tertiary <br /> butyl ether(MTBE)using EPA method 8020. <br /> Soil samples selected for analysis will be from intervals previously determined to have been <br /> impacted by hydrocarbons, from intervals exhibiting field evidence of significant contamination <br /> 7,Q and, in the deep boring, at least two consecutive depths beneath the termination of field <br /> ,ll evidence of contamination. <br /> All field work will be performed in accordance with Ground Zero's Quality <br /> Assurance/Quality Control Plan and the site-specific Health and Safety Plan on file with <br /> PHS/EHD. A drilling permit applic ' nd appropriate fees will be submitted following <br /> approval of this workplan. .fG �1 .,h( <br /> �`W *\kN do M <br /> �tJ <br /> 14\ <br /> TASK 3 FATE AND TRANSPORT MODEL AND RISK BASED CORRECTIVE <br /> ACTION EVALUATION <br /> Ground Zero will estimate the current mass and distribution of contaminants in the <br /> subsur <br /> face. We will also model and evaluate the fate and transport of both sorbed and dissolved contaminants and the action of natural attenuation. The evaluation will include <br /> estimates of cleanup time by natural attenuation alone and conjunction with continued <br /> "I active remediation. A Risk Based Corrective Action (RBCA) evaluation will be prepared <br /> v l which will identify exposure pathways and potential sensitive receptors and quantify health <br /> risks due to contamination at present concentrations. The RBCA will be used to establish <br /> site-specific soil and groundwater cleanup goals which are protective of human health and <br /> the environment. <br /> Q� <br /> TASK 4 EVALUATION OF ADDITIONAL REMEDIAL ALTERNATIVES <br /> Ground Zero has evaluated the potential effectiveness of air sparging at the site. We have \0 <br /> con ude hat the interbedded low and high permeability soils would make control and <br /> capture of the injected air ineffective for remedial purposes and may present a risk of <br /> further dispersion of gasoline hydrocarbons migrating under the site from offsite sources. <br /> This evaluation will be described in detail in the technical report. <br /> We will also evaluate the cost effectiveness of continued or nhance soil vapor extraction <br /> based upon the analytical results of the confirmation`1orings, the operational <br /> characteristics of the system and the results of fate/transport modeling and risk <br /> quantification. <br /> rmkklosureklos pAm <br />