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February 10, 2014
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<br /> Reference: Well Destruction Work Plan ARCO No. 2130
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<br /> their underground facilities located within the area of drilling. The area will be cleared if no underground ') :
<br /> facilities are found. In conjunction with USA North and 811, a private utility locator will be utilized for
<br /> Clearing proposed well boring locations for underground utilities. vt'
<br /> Well Destruction Activities
<br /> A C-57-licensed drilling company will complete the well destruction activities following all relevant d ctl
<br /> sections in the California Well Standards, Bulletin 74-go and the San Joaquin County Well Standards. y i
<br /> Per the SJCEHD Letter dated August 23, 2013 wells containing detections of contaminants of concern in
<br /> groundwater during the last sampling event must be over-drilled and wells with non-detectable
<br /> concentrations of contaminants of concern in groundwater can be pressure grouted (Attachment A). /�, 5-
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<br /> Based on review of most recent groundwater data, all of the monit��o,r�i`ng and remediation wells will be 31, 51 -
<br /> over-drilled with the exception of MW➢7j MW-i4, MW 19 and MW- 1. The four wells listed will be d' eat
<br /> pressure grouted since they have non-detections and are away from the source area and in the right-of-
<br /> ways. Fifteen additional wells (MW-5, MW-6, MW-13, MW-16, MW-2o, AS-2, AS-3, VW-3, VW-6, VW-8
<br /> through VW-12, AB=z-A-9-t and MS-3A/B) will require a variance from the SJCEHD as part of this Work
<br /> Plan to be pressure grouted. Below is the safety evaluation that was determined: M ha� -Ao o o }
<br /> Wells AS-2, AS-3, VW-3, VW-6, VW-n, and MS-3A/B are located in the current UST backfill or
<br /> immediately adjacent. Over-drilling these locations runs the risks of encountering the USTs
<br /> directly and potentially causing a new product release or encountering pea gravel that would
<br /> make their removal challenging and would require a much larger advancement of an outer casing.
<br /> Both of these conditions would shut down the business operating at the Site and is not
<br /> recommended. Based on these circumstances, Stantec requested that MW-6, AS-2, AS-3, VW, 3,
<br /> VW-6, VW-n, and MS-3A/B be approved for pressure grouting. Given the close distance to the
<br /> USTs and pea gravel, Stantec recommends placing the mushroom cap at 1 foot below surface for
<br /> these well locations. If not possible, a field variance will be sought with the County grout
<br /> inspector.
<br /> • Wells MW-5, MW-13, MW-20, VW-8, and VW-10 are located between 7-28 inches from operating
<br /> product lines. over-drilling these locations runs the risks of encountering the product lines
<br /> directly and potentially causing a new product release. This condition would shut down the
<br /> business operating at the Site and is not recommended. Based on these circumstances, Stantec
<br /> requested that MW-5, MW-13, MW-20, VW-8, and VW-10 be approved for pressure grouting.
<br /> Given the close distance to the product lines, Stantec recommends placing the mushroom cap at 1
<br /> foot below surface for these well locations.
<br /> •
<br /> VW-9 and VW-12 are located within 14-15" of live electrical lines that provide service to the site.
<br /> Stantec is prepared to perform lock out tag out of the lines, but given the close proximity to
<br /> spinning augers, Stantec is recommending that that these wells be pressure grouted and a
<br /> mushroom cap be placed at 3 feet (ft) below ground surface,
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<br /> Design with community in mind
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