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AM <br /> July 21, 1993 Working To Restore Nature <br /> Fire Engine Company No 2, Stockton, California <br /> of stagnant water and a sample was collected for laboratory analysis See the section on <br /> groundwater sampling <br /> Subjective Analysis of Groundwater Samples <br /> Groundwater samples will be collected for subjective analysis from ,lust below the air-fluid <br /> interface in a monitoring well by lowering approximately half the length of a clean Teflon <br /> bailer through the interface The bailer will be retrieved and the water sample examined <br /> for floating product, sheen, or other subjective evidence of hydrocarbons <br /> Depth to Groundwater Measurements <br /> The depth of the groundwater surface in a monitoring well will be measured from the top <br /> of the well casing to the nearest 0 01 foot with a Solinst or similar electric water-level <br /> indicator The well will be vented to the atmosphere before obtaining depth-to-water <br /> measurements. Venting is conducted to allow the groundwater to equilibrate to barometric <br /> pressure These measurements will be combined to evaluate the elevation of the <br /> groundwater surface in each well and the slope of the groundwater surface across the site <br /> . Groundwater Sampling, <br /> The static water level in each well will be measured to the nearest 0.01 foot with a Solinst <br /> or similar electric water-level indicator cleaned with a laboratory-grade detergent and <br /> deionized water before use in each well. A clean bailer will be used to obtain a sample <br /> from the surface of the water in the well for subjective analysis of hydrocarbons The <br /> sample will be retrieved and examined for floating product, sheen, color, and clarity <br /> Approximately 3 to 5 well volumes will be purged from each well with a stainless-steel <br /> electrical submersible pump to allow sampling of representative formation water The <br /> pump, cables, and hoses will be cleaned with a laboratory-grade non-phosphatic detergent <br /> and water before use in each well The wells will be purged until pH, temperature, and <br /> electrical conductivity of the water stabilized, as measured by portable meters calibrated to <br /> a standard buffer and conductivity standard The water level is allowed to recover to at <br /> least 80 percent of the initial water level. <br /> A sample of the formation water will then be collected from the surface of the water in each <br /> of the wells with a Teflon bailer and slowly transferred to laboratory-cleaned sample <br /> containers. The recovered fluids from sampling in each well will be directed into type 17-E, <br /> steel, 55-gallon liquid waste drums approved for this use by the Department of <br /> Transportation until suitable disposal options are selected based on analytical results <br /> 0 38009_9w A-3 <br />