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Monitoring Well Installation and VET Report,and IRAP--Former Unocal Station#0187,Stockton,CA
<br /> December 22,2000
<br /> 10-Inch-diameter hollow-stem augers A GR geologist observed the dniling activities For wells U-15,
<br /> U-16, U-19, U-21, U-23, and U-25, soil samples were collected at five-foot intervals for description and
<br /> Preparation of a log, and for possible chemical analysts For well U-17, which was installed within 5 feet
<br /> of well U-16, soil samples were collected at five-foot Intervals below 80 feet bgs for description and
<br /> possible analysts For wells SP-1A, SP-2A, SP-3A, and SP-4A, soil samples were collected at ten-foot
<br /> Intervals for description and preparation of a log, but not for chemical analysis Bonng logs are included
<br /> In Appendix C Locations of newly installed wells are shown on Figure 3 Copies of the Well Driller's
<br /> Reports are Included in Appendix B
<br /> Soil cuttings generated during dniling activities were placed on and covered with plastic Composite
<br /> disposal confirmation sample SP-1(A-D) was collected from the stockpiled soil cuttings (Table 1)
<br /> Stockpile sampling procedures are presented in Appendix A The stockpiled soil cuttings remain at the
<br /> site, but have been approved for disposal at Forward Landfill in Manteca, California
<br /> Well Installation
<br /> Groundwater monitoring wells U-14 through U-25 were constructed using 2-tach diameter Schedule 40
<br /> polyvinyl chloride (PVC) casing and screen material, and vapor extraction wells UV-2 and UV-3 were
<br /> constructed using 4-Inch diameter Schedule 40 PVC casing and screen matenal Wells U-14, U-16, U-20,
<br /> U-22, and U-24 are screened from 65 to 75 feet bgs, wells U-15, U-17, U-19, U-21, U-23, and U-25 are
<br /> screened from 110 to 120 feet bgs, well U-18 is screened from 70 to 80 feet bgs, and wells UV-2 and
<br /> UV-3 are screened from 15 to 25 feet bgs The annular space around the screens in each well is packed
<br /> with Lonestar#3 graded sand The sandpack is followed by a seal of bentonite chips, then neat cement to
<br /> approximately 1-foot bgs The top of each well is protected by a vault box, locking well cap, and lock
<br /> The vault box is Installed flush with the ground surface, and is set in concrete
<br /> Sparge wells SP-2A and SP-3A are screened from 117 5 to 120 feet bgs, well SP-4A is screened from
<br /> 116 5 to 119 feet bgs, wells SP-213 and SP-313 are screened from 72 5 to 75 feet bgs, and well SP-413 is
<br /> screened from 69 5 to 72 feet bgs The annular space around the Spargepomt screens in each sparge well
<br /> is packed with Lonestar#60 graded sand Above the sandpack,the sparge wells are constructed similar to
<br /> the monitoring wells Sparge well SP-IA/SP-IB is a nested well with screened intervals from 72 5 to 75
<br /> feet bgs (SP-IB), and 117 5 to 120 feet bgs (SP-IA) The annular space around each screen interval is
<br /> packed with #60 sand The interval between sandpacks is filled with bentonite chips, and a seal of
<br /> bentonite chips is above the upper sandpack The remainder of the well is constructed as specified above
<br /> Well construction details are included with the boring logs in Appendix C
<br /> Well Monitoring, Development and Sam lin
<br /> The newly installed groundwater monitoring wells were developed on November 13 to 15, 2000, by
<br /> V&W Drilling,Inc (C57#720904) On November 20, 2000, all wells(existing and new)were monitored
<br /> and sampled by GR as part of the scheduled 4'h Quarter monitoring and sampling event Potentiometnc
<br /> and concentration maps were generated from this data(Figures 4 through 9) Each well was checked for
<br /> the presence of separate phase hydrocarbons (SPHs) No SPHs were observed in the wells Purge water
<br /> generated during development and sampling procedures remain at the site, but has been approved for
<br /> disposal at Tosco's Rodeo refinery A copy of the monitoring well observation summary sheet is
<br /> included in Appendix D Monitoring data are summarized in Table 2
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