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Can epa Is Car Wash 248 E Park Street, Stockton, California January 24, 1994 IInterim Status Report on Phase II Investigation Page. 3 3.2 Well Construction All materials used in well construction were thoroughly cleaned prior to mtroduction into the boring A bentonite or eement/bentonrte grout was placed at the bottom of the borings as necessary. After the seal was allowed to set long enough to support the weight of the casmg, a 2-mch diameter PVC well casing with end cap and factory perforations for placement in the saturated zone (taking into account seasonal var=on) was placed in the boring The screen and filter pack sizes are as noted in the Bonng/Well Completion Logs The casing and end caps were threaded or,joined by stainless steel screws, no PVC cement was used The filter pack extends two feet above the perforated zone A bentonite seal two to three feet thick was placed in the annular space above the filter pack followed by a cement/bentorute grout to the Isurface ' 3.3 Well Development and Sampling The wells were developed until the well water appeared clear of sediment, or until an appmprc ite number of well volumes (based upon the Judgment of the responsible professional) had been evacuated The water produced during well development was contammued and left on-site in 55-gallon drums, or other suitable containers for disposal as hazardous waste of deemed necessary upon receipt of laboratory results Disposal will be the responsibility of the client unless other arrangements have been made The wells were allowed to stabilize for twenty-four hours pnor to sampling All soil and groundwater samples were properly labeled with date collected, project number, sample coordinator, and sample identification Field records documented the above Iinformation and other significant data, such as names of on-site personnel, sampling methods, date and time of sampling, the number of well volumes removed before sampling, preservatives added (if any), and any filtration performed on samples The samples were refrigerated immediatelyfor delivery to the laboratory and were under no �}' rY circumstances opened by anyone other than laboratory personnel Chain of Custody records were maintained at all times (Appendix A & B) 3.4 Soil Sampling All soil sampling equipment was thoroughly steam-cleaned before and between sampling to Prevent cross-contamination. Relatively undisturbed soil samples were taken at fifteen feet and every five foot interval thereafter in order to evaluate the subsurface materials The soil samples were taken using a California Modified Split Spoon sampler with brass liners The sampler was driven continuously by a 140 pound wire-line hammer repeatedly falling 30 inches The blow counts necessary to drive the sampler were recorded on the boring log for Ieach 6 inch interval to help evaluate the consistencies of the materials