ARCHIVED REPORTS XR0000847 - Laserfiche WebLink

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WELL INSTALLATION On October 30, 1997, a California-licensed drilling contractor conducted drilling and well installation activities under the supervision of a California-registered geologist. The borehole was drilled using 10-inch diameter hollow stem auger drilling equipment. Soil samples were collected at five foot intervals using a modified California split spoon sampler fitted with brass liners. The lowest liner from each sample was preserved for laboratory analysis by sealing the ends with Teflon® tape and plastic end caps and placing the sample in an ice chest. Drilling terminated at a depth of 75 feet bgs. An EMCON geologist prepared exploratory boring logs (included in this appendix) from soil samples and auger return materials. Soils were logged in accordance with the Unified Soil Classification System Soil from each sample interval was sealed in plastic bags to allow volatilization of petroleum hydrocarbon vapors. Headspace readings were measured using a flame ionization detector (FID) to assess potential hydrocarbon impacts and assist in selecting samples for laboratory analysis. The FID did not record measurable volatile organic compounds and there were no petroleum hydrocarbon odors or staining. Exploratory boring log and well detail documentation are included in this Appendix. The borehole was converted to a four-inch diameter monitoring well MW-4 by installing schedule 40 PVC well casing. The approved well permit application and workplan proposed the installation of 40 feet of well screen; however, during the well inspection, the San Joaquin County Public Health Services inspector stated the agency limitation of 20 feet of screen. Thus, well MW-4 was constructed with a 20-foot screen interval extending from 45 to 65 feet bgs. Well MW-4 was developed on November 19, 1997, using a surge block and PVC bailer. The well was sampled concurrent with the quarterly monitoring event on November 20, 1997. A licensed well surveyor surveyed well MW-4 on January 8, 1998. LABORATORY ANALYSIS Soil samples from 41 and 51 feet bgs, were submitted and analyzed for TPHG, BTEX, and MTBE using EPA Methods 801518020. Petroleum hydrocarbon constituents for these samples were below laboratory detection limits. Copies of the certified analytical reports and chain of custody documentation are included in this appendix. SOIL AND DECONTAMINATION WATER DISPOSAL EMCON coordinated disposal of soil and water generated during the activities with ARCO's waste disposal contractors Dillard Trucking and 1WM. • SAC�N�PJ"80SD805(470.3 DS-98\pzusmer.2 A-1 Rev.0,2120/98