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Equipment Cleaning <br /> Before the sampling event was started, equipment that was used to sample groundwater <br /> was disassembled and cleaned with detergent water and then rinsed with deionized water <br /> During field sampling, equipment surfaces that were placed in the well or came into <br /> contact with groundwater during field sampling were steam cleaned with deionized water <br /> before the next well was purged or sampled <br /> Water Leel, Floating Hydrocarbon, and Total Well Depth <br /> Measurements <br /> Before purging and sampling occurred, the depth to water, floating hydrocarbon <br /> thickness, and the total well depth were measured using an oil/water interface measuring <br /> system The oil/water interface measuring system consists of a probe that emits a <br /> continuous audible tone when immersed in a nonconductive fluid, such as oil or gasoline, <br /> and an intermittent tone when immersed in a conductive fluid, such as water The floating <br /> hydrocarbon thickness and water level were measured by lowering the probe into the well <br /> Liquid levels were recorded relative to the tone emitted at the groundwater surface The <br /> sonic probe was decontaminated by being rinsed with deionized water or Steam cleaned <br /> after each use A bottom-filling, clear Teflon" bailer was used to verify floating <br /> hydrocarbon thickness measurements of less than 0 02 foot Alternatively, an electric <br /> sounder and a bottom-filling Teflon bailer may have been used to record floating <br /> hydrocarbon thickness and depth to water <br /> The electric sounder is a transistorized instrument that uses a reel-mounted, two- <br /> conductor, coaxial cable that connects the control panel to the sensor Cable markings are <br /> stamped at 1-foot intervals The water level was measured by lowering the sensor into the <br /> monitoring well A low-current circuit was completed when the sensor contacted the <br /> water, which served as an electrolyte The current was amplified and fed into an indicator <br /> light and audible buzzer, signaling when water had been contacted A sensitivity control <br /> compensated for highly saline or conductive water The electric sounder was <br /> decontanunated by being rinsed with deionized water after each use The bailer was <br /> lowered to a point dust below the liquid level, retrieved, and observed for floating <br /> hydrocarbon <br /> Liquid measurements were recorded to the nearest 0 01 foot on the depth to <br /> water/floating product survey form The groundwater elevation at each monitoring well <br /> was calculated by subtracting the measured depth to water from the surveyed elevation of <br /> the top of the well easing (Every attempt was made to measure depth to water for all <br /> wells on the same day ) Total well depth was then measured by lowering the sensor to the <br /> bottom of the well Total well depth, used to calculate purge volumes and to determine <br /> whether the well screen was partially obstructed by silt, was recorded to the nearest <br /> 0 1 foot on the depth to water/floating product survey form <br /> SACW\PJM805\D805]510 2AS-96Ncjb 1 A-2 Rev 0 September 24 1996 <br />