SITE INFORMATION AND CORRESPONDENCE

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u � Mr. Harlan Knoll 2 July 2, 1991 collected at a minimum of five foot intervals, changes in lithology, any obvious areas of contamination and at immediately above the water table using a California modified split spoon sampler lined with brass sleeves driven by a 140-pound hammer falling 30 inches . One of the central borings will be continuously cored, at Unocal Corporation' s request . In addition, one sample will be taken from near the hydraulic lift by using a hand auger. The soil samples will be retained in the brass sleeves, the ends of the brass sleeves wrapped in aluminum foil, covered with plastic end caps, labeled, and placed in ziplock baggies. The brass sleeves will then be placed in a cooler with ice pending delivery to a state-certified laboratory. _ Chain-of-custody documentation will accompany the samples to the laboratory. The soil samples will be classified lithologically in accordance with the Unified Soil Classification System. Once the borings are completed, five of the boreholes will be filled with a neat cement grout to the ground surface using a tremie pipe. The hollow stem augers will be steam cleaned prior to use in each boring. Water from the steam cleaning will be stored in drums pending appropriate disposal . All soil cuttings generated during boring operation will be stored onsite under visqueen pending appropriate disposal. Installation of Four Monitoring Wells Borings which will be converted to monitoring wells will be further drilled to approximately ten feet below the ground water surface. Should a five-foot thick clay layer be encountered, drilling will be terminated. The wells will be constructed using two-inch diameter PVC pipe with fifteen feet of screened PVC (0 . 020-inch slot) placed in the bottom of the borehole. No organic glues or solvents will be used in assembling the PVC sections. Lonestar #2/12 sand will be poured into the annular space surrounding the PVC pipe to a height of one foot above the tope of the slotted interval . A two-foot thick layer of bentonite pellets will be placed above the sand and hydrated. The remaining annular space will be filled with a neat cement grout to the ground surface. The top of the PVC will be secured with a lock and enclosed in a water-tight vault . The exposed top will be stamped with the words "Monitoring Well" . The wells will be surveyed to the top of the PVC pipe to an accuracy of 0 . 02 feet by a licensed surveyor. A diagram showing proposed well construction is attached to this Work Plan.