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r <br /> 3 4 ' <br /> i <br /> • 29 December 1999' <br /> ' AGE-NC Project No 97-0312 <br /> Page 3 of 9 , - <br /> 2 4 ADDITIONAL INVESTIGATION ; <br /> In June 1999, soil bonngs B 14 through B 17 and monitoring well UST-6 were installed at the site and <br />' soil and grab water samples were collected Petroleum hydrocarbons were detected'in seven of the <br /> 24 soil samples analyzed These borings were advanced as the first phase of the December 1998 Site <br /> Assessment Work Plan The second phase of drilling is outlined in sections 3 3 through 3 5 below <br /> 3.0. PROCEDURES <br />' Five ground water momtonng'wells were purged and sampled on 23 September 1999 Twelve soil <br /> borings were advanced at the site between 27 and 29 September 1999 i Field work was performed <br />' in accordance with San Joaquin County Public Health Services - Environmental Health Division <br /> (PHS-EHD) and Central Valley Regional Water Quality Control Board(CVRWQCB) guidelines for <br /> the investigation of underground storage tank (UST) sites Field procedures for the collection of soil <br />' samples and performance of ground water monitoring and sampling are described below <br /> lie3 1 MONITORING WELL PURGE PROCEDURES <br /> On 23 September 1999, a Solinst water level meter was used to measure the depth to ground water <br /> relative to the tops of the well casings in six monitoring wells in the area of the former UST <br /> locations, three wells for a separate investigation on the subject property and one well at 3400 <br />' Newton Road The ground water elevation in each well and hydraulic gradient for the site were <br /> determined from these data(Table 1) f <br />' After measuring ground water depths, monitoring wells UST-2 through UST-6 were purged using <br /> a Grundfos submersible purge pump and PVC bailers Approximately 10 to 14 gallons of water <br /> (minimum of three well volumes) was removed from each of these wells Ground water was purged <br />' from near the top of the water column to remove water trapped within the unscreened interval of the, <br /> well casings Temperature, pH and conductivity-of purged water were measured at two-gallon <br /> intervals during purging using an Hydac water analyzer The. recorded field data and logs are <br />' included in Appendix A Purged water was stored on-site in 55-gallon DOT-approved drums <br /> pending laboratory analyses <br /> , r <br /> I - <br /> i 3 2' COLLECTION OF GROUND WATER SAMPLES <br /> 1 Water samples were retrieved from each purged well using new disposable bailers Each sample was <br /> . transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml of 18% hydrochloric acid as a <br /> I <br /> ti <br /> Advanced GeoEnvironmental,Inc <br /> Y' <br /> F <br /> y f [ <br /> ' <br /> } <br /> t s <br />