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R <br /> Quarterly Monitoring Report July 12, 1996 <br /> Chapin Brothers Automobile Repair Facility Stockton, California <br /> 2.1 Subjective Inspection <br /> Prior to purging or sampling, the wellheads were inspected and found to be in good <br /> condition A disposable plastic bailer was lowered to the groundwater surface, retrieved, and <br /> inspected for floating product or other subjective evidence of contamination No floating product <br /> was present An electronic water level indicator was used to measure the depth to groundwater <br /> and the total depth of each well relative to a surveyed mark on the wellhead The thickness of <br /> the water column was then used to calculate the volume of water in the well and thus to arrive at <br /> a calculated minimum purge volume <br /> 22 Well Purging <br /> Prior to sample collection, each well was purged of 30 to 50 gals of groundwater using a <br /> i 1 5-in diameter decontaminated submersible electric pump The volumes purged correspond to a <br /> ■ minimum of three well volumes (casing and gravel pack volume) Table 1 lists the date of <br /> sampling, depth to water, and field measurements of pH, temperature and electrical conductivity <br /> 23 Groundwater Sampling <br /> Following purging, each monitoring well was allowed to recover to greater than 90% of <br /> the original well volume Each monitoring well was sampled using a 1 5-in diameter disposable <br /> polyethylene bailer lowered approximately halfway through the groundwater surface in the well <br /> Groundwater samples were then transferred into two sterile 40-m1 glass vials equipped with <br /> Teflon septa Each vial was checked to ensure that no air bubbles were entrapped, and then each <br /> sample container was labeled, logged on a chain-of-custody form, and placed into an ice chest <br /> ikept at 4°C using ice The samples were transferred the following day into the custody of <br /> Sparger Technology Analytical Laboratory <br /> No free product was found in the wells Water purged from the wells was sealed in 55- <br /> gal drums and temporarily stored onsite <br /> i <br /> 3.0 GROUNDWATER SAMPLE ANALYSIS <br /> Groundwater samples were analyzed for TPHg using EPA Method 8015 (modified) and <br /> Ipurgeable aromatic hydrocarbons (BTEX) using EPA Method 8020 All analyses were <br /> conducted by Sparger Technology Analytical Laboratory of Sacramento, California, which is <br /> certified by the State of California for the requested analyses <br /> 530-001 - 3 - LuSH GEOSCIENCES <br />