ARCHIVED REPORTS XR0010036 - Laserfiche WebLink

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The results of the survey showed that some metal debris and utilities were detected however, no geophysical data indicative of a UST was located. A possible fill port was noted in front of the large building (former garage), however that screw cap did not appear to have been a fill port and no vent pipes were traced to that location, no hard evidence of a UST was noted (see Norcal report, page 2). GPR ,data indicated small metallic debris near the welding building but it did not represent an object such as a drum or UST. The suspected vent line was traced to the east (toward the former tank pit) with a termination about 55 feet east of the building. A suspected water line was also noted, and the large irrigation line was not observed, possibly indicative of a clay pipe, non- reinforced concrete pipe or nonmetallic pipe construction. EXploratory Borings Twelve exploratory borings were drilled at the site(Figure 1) on April 25, 2000 and April 19, 2001. These borings were performed in consultation with and under the approval of PHS-EHD. Drilling permits were secured from PHS-EHD, and all utilities were cleared prior to doing the fieldwork. Representatives of the Westside Irrigation District and City of Tracy met Wright in the field and directed where boreholes should be placed. On the day of drilling, the City of Tracy requested that due to the presence of two Iarge sewer lines, not to drill any borings tentatively scheduled in that vicinity. The direct push borings were advanced at the available locations in the unpaved areas shown on Figure 1. The borings were drilled into the uppermost aquifer strata to the contact of, and into the underlying confining strata field working aquitard (referred to as the aquitard strata in previous reports, those strata which are used to terminate borings as a conservative measure to prevent puncturing possible clayey beds and allowing vertical leakage; the term aquitard implies a relatively impermeable strata which may leak). Moderate to severe flowing conditions were encountered in some boreholes, which required drilling methods to be alternated between push and auger drilling depending upon the severity of the flowing conditions. Severe flowing borehole conditions were encountered locally, some soil and groundwater samples could not be collected. The boreholes were drilled with truck mounted direct push drilling equipment. All drilling equipment and sampling tools were cleaned prior to arriving, between driving samples and before leaving the site. The push sampler and rods, and augers were advanced to the desired sampling depth interval, and a drive split spoon sampler were driven ahead of the drill bit. The sampler was then retrieved and dissembled, and the soil filled brass or acetate liners retained for chemical analysis, were sealed with Teflon® paper and plastic end caps, labeled, logged onto chain-of-custody forms and place in a chilled ice chest on crushed ice. Drill cuttings were drummed and left on-site. Paw 5