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r� Monitoring Well Installation Report—Former Unocal Station#0123,Tracy,CA January 17,2001 Depth to water during this monitoring event ranged from 9 34 to 10 64 feet bgs and groundwater flow was to the north at a gradient of 0 003, which is consistent with available historical data. I FIELD ACTIVITIES To further evaluate the downgradient extent of petroleum hydrocarbons in soil and groundwater at the site, GR installed two groundwater monitoring wells Field work was performed in accordance with GR's Site Safety Plan#240073 04, dated November 9, 2000 A copy of well installation permit#0024399 from the SJCPHS-EHD and encroachment permit #00522 from the City of Tracy are included in Appendix B GR Field Methods and Procedures are included in Appendix A Underground Service Alert was notified prior to beginning site activities The wells were installed by Cascade Drilling, Inc (C57 #717510) Groundwater monitoring wells U-7 and U-8 were installed on November 13, 2000 The well borings were drilled to a depth of 21 5 feet below ground surface (bgs) using a truck-mounted drill rig equipped with 8-inch-diameter hollow-stem augers A GR geologist observed the drilling activities Soil samples were collected from the well borings at 5-foot intervals for description and preparation of a log, and for possible chemical analysis Boring logs are included in Appendix C Locations of newly installed wells are shown on Figure 2 Copies of the Well Driller's Reports are included in Appendix C Soil cuttings generated during drilling activities were placed in 55-gallon drums Composite disposal . confirmation sample SP-l(A-D) was collected from the soil cuttings Soil cuttings sampling procedures are presented in Appendix A Well Installation Groundwater monitoring wells U-7 and U-8 are constructed using 2-inch diameter Schedule 40 polyvinyl chloride (PVC) casing and 0 020-inch machine-slotted screen material The wells are screened from 5 to 20 feet bgs The annular space around the screens in each well is packed with Lonestar#3 graded sand The sandpack is followed by a seal of bentonite chips hydrated with clean water and concrete to ground surface The top of each well is protected by a vault box, locking well cap and lock The vault box is installed flush with the ground surface, and is set in concrete Well construction details are included with the boring logs in Appendix C Well Monitoring,Development and Sam Im The wells were developed and sampled on December 6, 2000 during the regularly scheduled quarterly monitoring and sampling event Depth-to-water was measured in all groundwater monitoring wells at the site and a potentiometric map was generated from the data (Figure 2) Each well was checked for the presence of separate phase hydrocarbons (SPHs) No SPHs were observed in the wells Neither of the newly installed wells dewatered during development Following development, groundwater samples were collected from each of the wells Purge water generated during development and sampling procedures was transported to Tosco's Rodeo refinery for disposal Well development procedures are included in Appendix A Copies of the well development forms are included in Appendix D Monitoring data are summarized in Table 2 24007305-1 3