Laserfiche WebLink
AJ 9 �! <br /> 5.2 Lateral Extent of Contamination ; :''' <br /> The lateral extent of contamination will be assessed by drilling three additional borings around <br /> the perimeter of the former tank cavity. Their exact depths and locations may depend on the .,. <br /> magnitude of contamination that is evident in the first boring, but tentative locations are shown <br /> in Figure 2. The estimated depth of these borings is 30 feet, If groundwater is reached before ' <br /> two consecutive uncontaminated soil samples have been collected, two of the three borings willFk <br /> be converted to monitoring wells. The elevation of the well casings will then be surveyed <br /> relative to a temporary ;benchmark and the depth to groundwater will be measured before <br /> purging and sampling. <br /> ;1 <br /> s <br /> 6.0 PROCEDURES F`J <br /> The procedures that will be used in this investigation are listed below: <br /> 1)Notify San Joaquin EHD at least 48 hours prior to field work. ` <br /> t <br /> 2) Drill one vertical boring through the former tank cavity to an estimated depth of 30 feet <br /> below grade using a hollow-stem auger drilling rig. , <br /> 3) Collect discrete soil samples at 5-foot intervals, using a California modified split-spoon <br /> samplef loaded with three 6-inch brass sample sleeves. <br /> 4 Preserve the bottom sleeve by g coverin the ends with aluminum foil or Teflon sheets and <br /> capping with plastic end caps. Place samples in a cooled ice chest. <br /> 'I <br /> Al <br /> 5) Screen the middle sample for the presence of organic vapors using a portable <br /> photo-ionization detector(PID)and record the measurement on the boring'log. <br /> 6)Extrude the middle and upper sleeves and record the sample descriptions on the boring <br /> log in accordance with the Unified Soil Classification System. <br /> i. <br /> a <br /> 7)Decontaminate the sampling equipment between samples. F, <br /> 8) Steam clean the drilling equipment. <br /> 9)Place auger returns on!visquine. <br /> €1 <br /> i <br /> 10)Repeat steps 2-9 for three additional borings. <br /> f <br /> I�R <br /> V <br />