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1 - ' <br /> t i <br /> May 30,2014 <br /> 7-Eleven #14117-2725 Country Club Boulevard,Stockton,California <br /> Page 2 of 3 l <br /> Reference: Work Plan for Well Destruction <br /> Well Destruction <br /> rAY Five onsite groundwater monitoring wells(MW-i,MW-3,MW-4,MW-y,and MW-8),two offsite <br /> groundwater monitoring wells(MW-5 and MW-6),and five onsite oxygen injection wells(I-3 through-1-5) <br /> `L5 will be destroyed.Based on the most recent groundwater data and the area of known or suspected <br /> remaining soil impacts,monitoring wells MW-3,MW-4,MW-8,and oxygen injection wells I-4 and I-5 will <br /> be completely overdrilled to ensure the remov o� t e contents of the well(con actor casing, ng; <br /> screen,filter pack,grout sealant). <br /> The cleared boreholes will be sealed with neat cement from the bottom upward using a tremie pipe to a <br /> depth of three feet bgs.The remaining void will be filled with native soil or engineered fill and the surface <br /> will be completed to match the existing grade. <br /> ter, The remaining wells(monitoring wells MW-i,MW-5,1VIW-6 and MW- •and oxygen injection wells I-1,I-2, <br /> and I-g)will be destroyed by pressure grouting,which consists of filling the well and filter pack with'neat <br /> nea <br /> m w cementrout through a tremie pipe from total depth to top of well casing.Grout will be allowed to settle and j <br /> ry\,W-LO then topped off before pressure is applied to the wells at 25 pounds per square inch for ten minutes. l <br /> ri'!VJ P«s"4A--su_j" i <br /> Following pressure grouting,the top 3.5 feet will be cleared with an airknife and vacuum truck,creating a <br /> hole at least one foot wider than the auger originally used to install the well.In addition,the well box, <br /> concrete apron,and well casing from three feet below ground surface to grade will be removed.After the 7 <br /> T" well box,concrete apron,and length of well casing are removed,grout sealant will be placed to spill out of <br /> the top of the well casing to form a mushroom cap seal to 2.5 feet bgs.The remaining void will be filled with <br /> native soil or engineered.fill and the surface will be completed to match the existing grade. <br /> Well construction logs are included in Attachment B. <br /> Waste Disposal <br /> Debris and displaced groundwater generated during well destruction and well box removal will be <br /> temporarily stored at the 7-Eleven site in Department of Transportation-approved 55-gallon drums(or roll- <br /> off bin),pending any necessary analytical profiling and transportation to an offsite disposal facility. M <br /> Reporting <br /> Stantec will generate a report documenting the well destruction and waste removal activities,and submit i <br /> the report to the SJCEHD. <br /> a <br /> t <br /> Design with community in mind f <br /> r <br />