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4 <br /> Workplan for Destruction of Groundwater Monitoring Wells <br /> Eggiman Hydaulic Garage <br /> Stockton,California 95205 <br /> July 29,2013 <br /> regard to the"No Further Action" request for the site and indicated all of the wells installed as part of the site <br /> investigation and remediation are to be destroyed. <br /> SCOPE OF WORK <br /> Determination of Well Destruction Method <br /> To be protective of groundwater quality, EHD has developed a policy that directs the destruction of monitoring wells <br /> by two different methods depending on the presence or absence of contamination in soil or groundwater in the <br /> vicinity of the well. <br /> Over drilling is required for wells with the following characteristics: <br /> 1. Soil samples collected during their installation indicated the presence of hydrocarbons, and <br /> 2. Where dissolved contaminants remain detected in recently collected groundwater samples. <br /> Pressure grouting is allowed for wells with the following characteristics: <br /> 1. If contamination was not detected in soil samples collected during their installation, and <br /> 2. Where recent groundwater samples collected from the wells proved to be free of contaminants. <br /> A worksheet that tabulates the well construction details and the logic used to determine the destruction method to <br /> be used on each well is included as Attachment 1. The locations of the wells to be destroyed are displayed in <br /> Figure 3. <br /> This worksheet shows that only two of the wells, MW11 and OS1s, are eligible for pressure grouting. However, it is <br /> not practical to pressure grout OS1s when OS1d requires destruction by overdrilling. Consequently, all wells will be <br /> overdrilled except MW11, which will be pressure grouted. <br /> Planning and Permits <br /> In advance of the well destruction activities, Cardno ATC will obtain an encroachment permit from the City of <br /> Stockton for the wells constructed within the public right of way, will negotiation site access agreements from <br /> private parties, as necessary, and obtain the required well destruction permits from the EHD. Cardno ATC then will <br /> notify Underground Services Alert to locate underground utilities as required, schedule field personnel and <br /> equipment, and perform other necessary field preparation and job start-up activities. The proposed work will be <br /> performed under the direction of a California Registered Professional Engineer or Geologist. <br /> Wells Abandoned by Over Drilling <br /> All the groundwater monitoring wells will be abandoned by over-drilling, except MW11 which will be pressure <br /> grouted. Overdrilling involves using an auger tool to remove the casing, sand pack, and other well components. <br /> Once the component parts of the well are removed, the boreholes will be backfilled with a neat cement grout slurry <br /> mix from the base of the annulus to the surface using a tremmie pipe. Any groundwater displaced to the surface <br /> during grout installation will be pumped out of the excavation, collected, and collected into drums for proper <br /> disposal. This water will be made available for the EHD to inspect and to verify that the well has been properly <br /> destroyed. The grout will be brought to grade and resurfaced to match the surrounding surface completion. <br /> Wells Abandoned by Pressure Grouting <br /> Groundwater monitoring well MW11 is to be destroyed via pressure grouting according to the following procedure. <br /> Prior to destruction, the well box and locking plug will be removed and a minimum 24-inch diameter hole will be <br /> excavated to a depth of approximately 36 inches around the well casing. The well casing will be cut off 30 inches <br /> below grade and will be removed. <br /> www.cardnoatc.com <br />