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Workplan Addendum <br /> ARCO Facility No.5469 <br /> Stockton,California <br /> Page 2 <br /> in a resealable plastic bag, and stored in an ice-chilled cooler. The samples will remain chilled until <br /> relinquished to a State-certified analytical laboratory. Strict chain-of-custody procedures will be <br /> followed from the time the samples are collected until the time the samples are relinquished to the <br /> laboratory. Soil contained in the remaining brass tubes will be screened for volatile organic compounds <br /> using field instrumentation equipped with a photoionization detector (PID). Delta will record PID <br /> readings, soil types, and other pertinent geologic data on the borehole log. Three soil samples will be <br /> submitted for chemical analysis from each boring, the sample exhibiting the highest PID response, the <br /> sample from just above first-encountered groundwater, and the sample collected from the bottom of the <br /> boring. <br /> Development of the monitoring well will consist of surging with a surge block and pumping. <br /> Development will continue, to the extent practical, until the development water runs clean and pH and <br /> conductivity measurements stabilize. After well development and stabilization of the water levels, <br /> water levels and the quantity of well volumes removed from the well will be recorded. The elevation of <br /> the top of each well casing will be surveyed by a California licensed surveyor. <br /> A minimum of 48 hours after the groundwater monitoring wells are installed, the wells will be purged <br /> and groundwater samples will be collected. The samples will be collected using a disposable bailer, <br /> transferred to laboratory-supplied glass vials, and placed in an ice-chilled cooler. The samples will <br /> remain chilled until relinquished to a State-certified analytical laboratory. Strict chain-of-custody <br /> procedures will be followed from the time the sample is collected until the time it is relinquished to the <br /> laboratory. <br /> Additional Laboratory Analysis <br /> In addition to the laboratory analyses specified in the February 28,2000 workplan, soil and groundwater <br /> samples will be analyzed for Methanol,Ethanol,EDB,and 1,2-DCA using EPA Method 8260. Samples <br /> will be submitted on a regular-turn-around basis. <br /> Schedule <br /> Upon receiving approval of this workplan addendum, the proposed work will be scheduled and a well <br /> permit application package will be submitted to PHS/EHD. We anticipate that it will require a <br /> minimum of three weeks after receiving the well permit for a drilling contractor to become available. <br /> Fieldwork, including well development and sampling, should be completed within three weeks of <br /> initiation. The assessment report will be submitted to the regulatory agencies within six weeks of <br /> receipt of all analytical reports. <br />