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r I ' S E C O R M v1 APPENDIX D iJ 'A n FIELD AND LABORATORY PROCEDURES ' , Exploratory Drilling and Soil Sampling „rel The sod borings for the groundwater monitoring wells were drilled using Air-Rotary (MW-15) � and Sonic (MW-16 and MW-17) drilling equipment Each boring was logged by SECOR field staff under the direction of a California Registered Geologist using the Unified Soil Classifica- tion System and standard geologic techniques Sod samples for logging and possible - laboratory analysis were collected at ten-foot depth intervals from 80 feet bgs to 120 feet bgs from the borehole for MW-17 Samples were collected directly from the 6-inch diameter sonic drill bit and then placed in a 6-inch long brass or stainless steel sleeve and capped with Mr+ a Teflon sheet followed by a tight fitting plastic cap The samples were labeled with site ' identification, sample identification number, sampling depth, sample collection date/time, and borehole number The sample was then annotated on a chain-of-custody form and placed in an ice-filled cooler for transportation to the laboratory ' The remaining soil samples were used for soil classification and field evaluation of headspace volatile organic vapors, where applicable, using a photoionization detector (PID) calibrated to isobutylene gas VOC vapor concentrations were recorded on the boring logs A physical description of the encountered soil characteristics (i a moisture content, �,• consistency, odor, color, etc ) and soil type as a function of depth were indicated on the boring logs In addition, the sample recovery and sampler penetration were also noted on the boring logs All down-hole drilling and sampling equipment was steam-cleaned prior to and following the completion of each soil borings Down-hole sampling equipment was washed in a trisodium phosphate or alconox solution between samples ' Organic Vapor Procedures Soil samples were collected at ten-foot depth intervals from 80 feet bgs to 120 feet bgs in MW-17 for analysis in the field for ionizable organic compounds using a PID with a 10 2 eV lamp The test procedure involved measuring approximately 30 grams from an undisturbed ' soil sample, placing this subsample in a ZiplockTM-type bag or in a clean glass tar, and seating the far with aluminum foil secured under a ring-type threaded lid The container was warmed for approximately 20 minutes (in the sun), then the head-space within the container was tested for total organic vapor, measured in parts per million as benzene (ppm, ' volume/volume) The instrument was calibrated prior to drilling The results of the field- testing were noted on the boring logs PID readings are useful for indicating relative levels of contamination, but cannot be used to evaluate petroleum hydrocarbon levels with the ' confidence of laboratory analyses ' Well Installations and Groundwater Monitoring Well Development ` Groundwater monitoring wells were constructed by inserting or tremming well materials through the annulus of the outer casing (for both air-rotary and sonic) In general, ' groundwater monitoring wells are constructed with 10 feet of screen below groundwater and 10 feet above groundwater, for a total screen length of 20 feet Where shallow groundwater ; rt , � ei