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a_ April 24,1989 File No.1705-2 APPENDIX A - SOIL .AND GROUNDWATER DRILLING, WELL INSTALLATION, SAMPLING AND SAMPLE HANDLING PROCEDURES Sampling Techniques All test borings have been generally drilled with either a CME-45 or CME-55 truck- mounted drill rigs equipped with 6-inch diameter c;�ntinuous flight augers and/or with 3 1/4 or 3 3/4 I.D. hollow stem,light augers. All test borings are logged by our field engineer, who also obtains representative soil samples for laboratory testing. Soil L samples are taken at 5 foot intervals or less as instructed by the field engineer when field conditions warrant it. Relatively undisturbed soil samples are obtained by driving a 2.0 inch Mod;fled Califor- niz Sampler or a 2.5 inch Modified Porter Sampler containing thin brass liners into the bottom of borings. The procedures used in obtaining these samples are identical to the Standard Split Spoon Sampler (ASTIM D-1586-67).When the sampler is withdrawn from the borings, the brass liners containing the samples are removed, field examined, and sealed for later laboratory testing. f ' After field examination, soil samples for hydrocarbon concentration testing are sealed with aluminum foil, capped with plastic endcaps, and wrapped in duct-tape. To further preserve the samples, the samples are then placed in a refrigerated ice chest for trans- portation and storage. All serif samples are tested in the field with a Gastech combustible gas detector for gas and vapor. Based on the field analysis, the on-site soils are prelimi- nary evaluated in the field as to the extent and amount of contamination. Readings from each sample are recorded in the field daily log and are presented in the boring logs of our final report. Groundwater sampling techniques are the same as described in the CRWQCB guide- lines. Briefly, water samples are taken after the well has been developed and stabilized the sand or gravel pack surrounding the perforated sections. See Monitoring Well In- stallation of this letter for well development techniques. eater samples are collected by using a teflon bailer that is thoroughly washed and cleansed prior to sampling other monitoring wells. A trisodium phosphate (rSP) solution is used to wash the bailer and then it is rinsed with clear,water. The 'coater samples are then collected in either one- laboratory-analysis-EPA ne- laboratory-analysis-EPA Modified 8015 -TPH;-Total-Petroleurn-Hydro- -- - ---- - --- carbons or,in VOA vials for EPA 602 and 624. In each type of sample bottle, each are sealed with a teflon-fined cap with no head space present in the sample container. The water samples are then placed in a refri, erated ice-chest for transportation and storage. A—I