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Ms. Turkatte <br /> July 24, 2015 <br /> Page 2 <br /> extraction wells and soil vapor monitoring probes. The general basis for this query was that <br /> because the source of the contamination has been removed from the vadose zone to the <br /> satisfaction of the Central Valley Regional Water Quality Control Board (RWQCB), these areas <br /> do not present a threat to groundwater and the shallow SVE wells and soil vapor monitoring <br /> probes do not represent a potential conduit for migration. <br /> More recently, the following response and criteria were proposed by SJCEHD regarding well <br /> abandonment(in an email from Zoey Merrill to Joe Salazar dated July 9, 2015): <br /> "EHD does not need to review all of the technical data, but instead are asking that your geo <br /> tech staff review the data and then, based on their review of the data,propose the wells they <br /> think are candidates for pressure grouting (instead of the over-drill method) based on the <br /> analysis shown below,for each well: <br /> Over-Drill Method Candidate - If the well is constructed through an area of impact and <br /> extends into an area of no impact. The area of no impact is the area we would like to protect <br /> by over-drilling the entire well and grouting. <br /> Pressure Grout Method Candidate -If the well extends into and is completed into an area of <br /> impact, then the impact is already there and the well would not act as a conduit to an un- <br /> impacted area. This well would be a candidate for pressure grouting. <br /> After they do this analysis, an addendum to their already submitted well destruction work <br /> plan should be submitted that identifies those wells that have been determined to be <br /> candidates for pressure grouting. The addendum should show the data for each well that <br /> demonstrates the well meets the above criteria and would not have the capacity to act as a <br /> future conduit to an un-impacted area. " <br /> This Addendum addresses the above criteria provided by SJCEHD. <br /> Abandonment Approach <br /> Based on the above criteria, in conjunction with the extensive remediation conducted, data <br /> collected and approvals obtained from the RWQCB to-date, Geosyntec is proposing to abandon <br /> the 36 SVE extraction wells and 22 soil vapor monitoring probes by the pressure grout method. <br /> The air sparge wells are still proposed to be abandoned using the over-drill method because these <br /> wells extend into the groundwater table. Provided below are the data demonstrating that the <br /> addendumtoabandonmentwp.doc <br /> engineers I scientists I innovators <br />