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' Well Installation Report 5606 Pac�flc Avenue Stpckton Calafom�a(CAO No_5-QQ7Q7) ,_._, EAI Project No 1232 20 FIELD WORK • ' 2.1 Drilling and Sampling Between February 20 and 23, 2001, ground water monitoring wells MW-181), MW-23S, MW- 23D, MW-24S, MW-24D, MW-25S, and MW-25D were installed in five well boxes Wells MW-23S and MW-23D (a k a MW-23 S/D) and MW-24S and MW-24D (a k a MW-24S/D) are dual completion wells with two well casings installed in each well box for a total of seven ' wells (see Figure 2) Appendix A contains a copy of the City of Stockton Revocable Permit No 01-01 and Encroachment Permit No 66355 for installation of the wells San Joaquin County Public Health Services (County Health) issued three well permits (SR#0025294, SR#0025295, and SR#0025296) to install the seven wells One well permit was issued for each assessors parcel number associated with the wells The County Health permits are also contained in Appendix A ' The wells were drilled by V&W Drilling of Isleton Californiais (License No 720904, C-57 Water Well DrilIing), under the supervision of an EAI California registered geologist The wells were drilled using either 8 or 10-inch outside diameter continuous flight hollow stem augers to depths ranging between approximately 45 and 105 feet below grade surface (bgs) All borings were logged in accordance with the Unified Soil Classification System (see ' Appendix B) Soil samples were collected at approximately 5 feet bgs and at 5-foot intervals thereafter until termination with the exception of borings MW-23 S/D and MW-24 S/D These wells were drilled to a total depth of approximately 105 feet bgs To the extent practical, these borings were sampled continuously between 85 and 105 feet bgs The purpose of the continuous sampling was to attempt to identify a 5-foot thick aquitard layer between the 85 foot and 105 foot depths Due to heaving sands and the difficulty in obtaining samples at these depths and drilling conditions, minor intervals were not sampled (see Appendix B) Mr Marty Hartzell of the RWQCB was present during sampling of well MW-23 S/D The drilling conditions and difficulty in obtaining samples were discussed and compared with the need to identify a 5-foot thick aquitard It was determined the sampling technique, although not perfect, was sufficient to adequately identify a 5-foot thick aquitard, if present Soil samples were collected using three 2-inch diameter by six-inch long brass tubes mounted within a 2-inch inside diameter split-spoon drive sampler employed in advance of the augers After sample recovery, the ends of the lowermost six-inch Iong tube were covered with Teflon tape and plastic caps taped over the ends Prior to use, all tubes were washed in a solution of Alconox detergent and tap water, and rinsed with tap water The samples were labeled with the sample point identification, depth interval, time and date, and EAI project number Each sample was individually sealed in a "Ziploc" plastic bag, and immediately placed into an ice chest chilled using ice The samples were kept chilled until delivered to the laboratory for analytical testing All samples were logged on chain-of-custody record forms (see Appendix BUM 12128612] 2 tENVIRONMENTAL AUDIT, INC