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7-Eleven/Stockton 13 May 1990 During drilling, soil samples were collected by a Groundwater Technology geologist at 5-foot depth intervals. Samples were obtained by driving a split-spoon sampler, lined with three, 2-inch-diameter by 6-inch-long brass tubes into the undisturbed soil at the bottom of each boring. One tube from each sampling interval was sealed, capped, labeled and placed on . ice in an insulated cooler for delivery to GTEL Environmental Laboratories, Inc. (GTEL) , a State of California-certified laboratory in Concord, California. One brass tube sample from each sampling interval was field-screened for hydrocarbon vapors using a photo-ionization detector (PID) . The PID readings are noted on the drill logs provided in Appendix F. Based on a review of the field PID readings and drill logs, samples were selected for analyses for the presence of BTEX and TPH-as- -' gasoline using modified U.S. Environmental Protection Agency (EPA) Methods 5030/8020/8015. The samples submitted for analyses from the well-cluster borings included: (1) the one which exhibited the highest PID reading; (2) the one from the top of the water table; and (3) the last sample which exhibited a PTD F reading as the hole was advanced. Laboratory results of the soil sample analyses are presented in Appendix G. Each boring for the well cluster was completed as a 2-inch- diameter polyvinyl chloride (PVC) groundwater-monitoring well. The screened intervals for the two deeper borings in the cluster M were selected to be 5-feet in length, in order to monitor discrete zones of the aquifer. The shallow well was screened from 63-feet to 28-fee;,; below grade, in order to monitor the upper zones of the aquifer. The completion depths for the well cluster wells are as follows: `�.. GROLiNMATER TECHN01.0GY,INC.