SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Emit G GeoStrategies ,LT;i c- 2: 26 June 3, 1996 Mr. Dave Camille Unocal Corporation P.O. Box 5155 San Ramon, California 94583 Subject: Letter Report for Well Abandonment at Unocal Service Station No. 6981, 4707 Pacific Avenue, Stockton, California Mr. Camille: At the request of Unocal Corporation(Unocal), GeoStrategies (GSI)abandoned four groundwater monitoring wells at the subject site (Figure 1). Well abandonment was necessary to facilitate reconstruction of March Lane and Pacific Avenue. In a letter dated February 16, 1996, the City of Stockton, Department of Public Works notified Unocal concerning the proposed reconstruction and requested that the wells be abandoned prior to May 17, 1996. On May 3, 1996, GSI observed Mitchell Drilling Environmental Inc. (C57-672617) abandon groundwater monitoring wells MW-3, MW-10, MW-12, and MW-13. Locations of the former wells are shown on the attached Site Plan (Figure 2). A copy of the well abandonment permits issued by San Joaquin County Public Health Services (SJCPHS) are attached. One 4-inch diameter well (MW-3) and three 2-inch diameter wells (MW-10, MW-12, and MW- 13) were backfilled to the top of casing with neat cement using a tremie pipe, and pressure grouted. The wellhead box was removed from MW-3 and the upper 2 feet of casing was drilled out. The wellhead box for well MW-10 was not removed and the upper 2 feet of casing was not drilled out since the wellhead box will be removed during reconstruction. In addition, the wellhead boxes for wells MW-12 and MW-13 were not removed and the upper 2 feet of casing was not drilled out due to the proximity to a marked underground utility. MW-12 and MW-13 wellhead boxes will also be destroyed during reconstruction. All borings were backfilled to surface grade with neat cement. Ms. Mary Meays of the SJCPHS was onsite to observe the well abandonment activities. 4855.05 3164 Gold Camp Drive, Suite 240 • Rancho Cordova, CA 95670 (916) 631-1314 • Fax (916) 631-1317