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destruction. AGS proposes to remove all four wells prior to excavation to reduce mobilization <br /> costs. Well destruction will be performed in accordance with California water well standards as <br /> specified in document 74-90 or subsequent revisions that are in effect at the time of well <br /> abandonment. <br /> ' Each <br /> monitoring well will be abandoned by a California state licensed drilling contractor using a <br /> pressure grout method. A neat cement grout will be installed from the surface using a tremie <br /> pipe inserted to the bottom of the well casing. The casing will be grouted from its base to the <br /> surface. The well monument or traffic box will be excavated below grade approximately 12 <br /> inches and native soil placed into the hole after the cement grout has been allowed to set. <br /> 3.3 Excavation <br /> Excavation at on of gasoline contaminated soils will commence in the vicinity of the former UST and <br /> 1 progress outward from the tank pit to the limits of contamination as determined by <br /> Photoionization Detector (PID) screening. The excavation outline may be altered by the <br /> presence of buildings or other structures which may be encountered near the excavation. Soil <br /> ' excavation will be carried out under the direction of American Geological Services. <br /> Soil samples will be collected periodically from the walls and bottom of the excavation for <br /> ' headspace analysis. This will be conducted in order to monitor the limits of contaminated soil <br /> excavation and determine what clean soil may be stockpiled for returning to the excavation as <br /> well as contaminated soil which must be isolated. Soil samples collected for headspace readings <br /> will be placed in a zipper storage bag and the fuel hydrocarbons allowed to volatilize by warming <br /> the sample in the sun. When condensation on the bag indicates that sufficient volatilization has <br /> occurred, the probe of the PID will be inserted into the headspace of the bag. A log will be kept <br /> rof the readings and the soil sample locations will be plotted on the site plan. <br /> ' The PID will be calibrated before use with a standard gas according to manufacturer's <br /> specifications. <br /> ' 3.4 Collection of Excavation Sidewall Samples <br /> Once a determination has been made to cease lateral excavation based upon PID headspace <br /> ' readings, or physical or structural limitations, soil sidewall samples will be collected. Soil <br /> samples will be collected from sidewalls at intervals determined by one or more of the following <br /> methods. 1) At intervals of 20 feet around the perimeter of the excavation, 2) as directed by <br /> representatives of the San Joaquin County PHSIEHD, 3) as determined by the site geologist. <br /> Each sample will be collected at the maximum depth possible that is above the capillary fringe. <br /> Each soil sample will be collected from the backhoe bucket by driving a clean stainless steel or <br /> I ' brass sampling sleeve into freshly exposed soil and filling completely, without headspace. The <br /> ends of the sleeve will be sealed with plastic end caps, labeled with the location, date and time, <br /> and placed into a cooler chilled to 4° Celsius for transport to the analytical laboratory. Soil <br /> a <br /> American Geological Services, Inc. <br /> CA95D&029 <br /> 6 <br />