ARCHIVED REPORTS XR0001426 - Laserfiche WebLink

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' tremie pipe or through the center of the hollow-stem augers in one continuous operation from the bottom of the interval to the top Emplacement of the Portland cement grout was not accomplished by"free fall" from the ground surface The boring logs show well construction details The groundwater monitoring wells were developed more than 24 hours after completion and were sampled at least 24 hours after development as required by the San Joaquin County Environmental Health Department The development procedure for each ' well consisted of pumping or bailing water from the well until the water was visibly clear, the well went dry, or until a maximum of ten casing volumes had been removed ' Organic Vapor Procedures Soil samples collected at 5-foot depth intervals during drilling were analyzed in the field for ' ionizable organic compounds using a photo-ionization detector (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 clean clear ziplock type bag 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 using a 100-ppm isobutylene standard (in air) and a sensitivity factor of 55 which relates the photo-ionization potential of benzene to that of isobutylene at 100 ppm The results of the field testing was noted on the boring logs PID readings are useful for indicating relative levels of contamination, but cannot be used to evaluate hydrocarbon levels with the confidence of laboratory analyses Laboratory Procedures ' Selected soil vapor, soil samples collected from the soil borings and groundwater samples collected from the wells were analyzed for the presence of total petroleum hydrocarbons ' calculated as gasoline, benzene, toluene, ethylbenzene, and xylenes, and methyl tertiary butyl ether(MtBE) using modified EPA Methods 8015 and 8020 ' Physical Soil Data Selected soil samples collected from the soil boring were analyzed for determination of ' organic carbon content, moisture content, total porosity, bulk density, and grain density Moisture contents were determined using standards ASTM D-2216 methods Total organic carbon content was determined by EPA 9060 modified methods Grain and pore volumes ' were determined using Boyle's Law double-cell methods with helium as the gaseous medium Porosity's and densities were then calculated as described in API RP-40, API Recommended Practice for Core-Analysis Procedure, 1960 Water saturation was also determined by API RP-40 methods 910-017 1A/SOIGWRPT A - 2 December 2, 1998