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<br />aecom.com <br />Our Reference 60632236 <br />3/6 <br />top of the well casing for any hanging lines, shining a flashlight into the open hole, and lowering a <br />measuring tool to the total depth of the well. If obstructions are seen and/or felt while lowering the <br />measuring tool, they will be removed by either removing the hanging lines or fishing the obstruction out <br />with a three-pronged hook or similar tool. <br />Each well will be over-drilled to the total depth of the original boring to remove the well casing and annular <br />material using a Hollow Stem Auger (8 inch outside diameter). After all casing has been removed, the <br />auger will be rotated at the bottom of the boring to remove all well construction debris to create a <br />satisfactory seal between the new grout and the boring wall. <br />Each boring will then be backfilled with neat cement grout, (i.e., Portland Cement-Type I/II 3-5% bentonite) <br />emplaced via tremie pipe. As the grout is pumped, the tremie pipe will be positioned so it is below the top <br />of the grout rising in the boring. The bottom of the auger stem will always be positioned below the top of <br />the grout seal to prevent possible caving of the sides of the boring. The volume of neat cement grout <br />added to the well will, at minimum, be equal to the calculated amount shown for each well in Table 2. <br />Any monitoring well water rising to the surface during grout placement will be contained and placed in <br />Department of Transportation (DOT) approved 55-gallon drums <br />Each well head box will be removed, and the former well vault cavity will be filled with a continuation of grout <br />to form a “mushroom” cap at the top of the drilled out well. The uppermost few inches will be topped off with <br />native soil to match the surrounding surface. <br />All well destruction locations will be recorded using a hand-held Trimble-brand (or equivalent) global <br />positioning system unit. <br />In accordance with California Water Code Section 13751, the licensed C-57 water-well drilling <br />subcontractor will file a Well Completion Report (Well Destruction) with DWR within 60 days of the <br />completion of the work. <br />Investigation-Derived Waste <br />Investigation-derived waste (IDW) will be generated during well destruction activities and will include the <br />boring soil, well casing and annular material removed from each boring, possible monitoring well water <br />and decontamination water. <br />The soil will be placed in a 20-yard roll-off bin, and the water will be contained in DOT-approved 55-gallon <br />drums. The IDW will be covered and temporarily stored at the Site pending sampling and analysis for <br />waste profiling purposes. It is anticipated that both the soil and water will be classified as non-hazardous. <br />Four IDW profile samples (two soil and two water) will be composited from the bin and drums and sent to <br />Eurofins Test America Laboratory, a State of California-certified analytical laboratory in Sacramento, <br />California, for waste profiling purposes. The IDW samples will be labeled with site-specific labels and <br />placed under chain-of-custody in a cooler chilled with ice and shipped to the laboratory for analysis. The <br />samples will be analyzed on a standard 10-day-turnaround time. <br />Each soil sample will be analyzed for: <br />TPH-g, TPH-d, and TPH as motor oil by United States Environmental Protection Agency (EPA) <br />Modified Method SW8015; <br />Volatile organic compounds (VOC) by EPA Method SW8260B; and <br />California Title 22 Metals by EPA Method SW6010B. <br />Each water sample will be analyzed for TPH-g and TPH-d by EPA Modified Method SW8015, and VOC’s <br />by EPA Method SW8260B.