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ARCADIS GERAGHTY&MILLER <br /> concentrations are observed. A schematic piezometer construction diagram is <br /> provided as Figure 2. A summary of field methodologies is provided in Attachment A. <br /> Preparation of a Corrective Action Plan(CAP) <br /> Upon completion of the focused subsurface investigation, UNOCAL will <br /> prepare and submit a CAP. The CAP will propose a course of action designed to <br /> result in cleanup of the impacts and that has been determined to be the most cost- <br /> effective. The CAP will be designed such that its implementation will restore or <br /> protect beneficial uses of the aquifer. <br /> The CAP submitted to SJCPHS will include: <br /> • An assessment of the vertical and lateral extent of impacts based on the <br /> previous site investigations and the focused subsurface investigation <br /> proposed herein. <br /> • A feasibility study. <br /> • Applicable cleanup levels based on the numerical objectives designated <br /> in the Basin Plan of the Central Valley Regional Water Quality Control <br /> Board. <br /> The assessment component of the CAP, in addition to that referred to above, <br /> will address the physiochemical characteristic of the constituents of concern, <br /> toxicity, persistence and potential for migration in groundwater. The CAP will also <br /> discuss the hydrogeology of the site and the surrounding area where the <br /> unauthorized release has migrated or may migrate. The current and potential <br /> beneficial uses of the waters beneath the site and vicinity will also be presented <br /> along with the associated background quality of groundwater in the vicinity of the <br /> site. Lastly, the assessment will address the potential effect of residual impacts on <br /> groundwater in the site vicinity. <br /> A feasibility study will be included in the CAP and will evaluate alternatives <br /> for remedying or mitigating adverse effects of the release. As indicated in Title 23, <br /> each alternative will also be evaluated for cost-effectiveness. At least two <br /> alternatives will be identified and evaluated as methods to restore or protect the <br /> beneficial uses of groundwater in the site vicinity. It is the opinion of ARCADIS <br /> Geraghty and Miller that sufficient data is available, from scientific literature <br /> sources and site-specific data at similar sites in California and in the local vicinity <br /> of this site, to conduct the methodology evaluation without further implementation <br /> of site pilot testing. The most cost-effective corrective action will be selected and <br /> submitted to S]CPHS as the action to implement. <br /> Our ref.: Page: <br /> 11GM_SANTA BARBARAMATAtiAPRO_SBOIVNOCALIC_VALLEYtiWPS_REVIPACWKP2A.DOC 7/11 <br />