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GROUNDWATER SAMPLING PROTOCOL <br /> The static water level and separate-phase product level, if present, in each well that contained water and/or <br /> separate-phase product are measured with a ORS Interface Probe, which is accurate to the nearest 0.01 foot. <br /> To calculate groundwater elevations and evaluate groundwater gradient, depth to water (DTW) levels are <br /> subtracted from top of casing elevations. <br /> Groundwater samples collected for subjective evaluation are collected by gently lowering approximately half the <br /> length of a clean Teflon® or polypropylene bailer past the air-water interface (if possible) and collecting a <br /> sample from near the surface of the water in the well. The samples are checked for measurable free-phase <br /> hydrocarbons or sheen. If appropriate, free-phase hydrocarbons are removed from the well. <br /> Before water samples are collected from the groundwater monitoring wells, the wells are purged until a <br /> minimum of three well casing volumes is purged and stabilization of the temperature, pH, and conductivity is <br /> obtained. Water samples from the wells that do not obtain stability of the temperature, pH, and conductivity are <br /> considered to be"grab samples." The quantity of water purged from each well is calculated as follows: <br /> 1 well casing volume =Tcr2h(7.48)where: <br /> r = radius of the well casing in feet <br /> h = column of water in the well in feet <br /> (depth to bottom -depth to water) <br /> 7.48 = conversion constant from cubic feet to gallons <br /> TE = ratio of the circumference of a circle to its diameter <br /> Gallons of water purged/gallons in 1 well casing volume =well casing volumes removed. <br /> The wells are purged using a submersible pump. Prior to use at the site and between wells the pump is <br /> cleaned. <br /> Five gallons of water are placed in three 15-gallon tubs. Liquinox detergent is added to the first tub of water. <br /> The pump and tubing are submerged in the first tub and the water is pumped through the pump. The process is <br /> repeated in the second and third tub. <br /> After purging, each well is allowed to recharge to at least 80% of the initial water level. Water samples from <br /> wells that do not recover at least 80% (due to slow recharging of the well) between purging and sampling are <br /> considered to be"grab samples." Water samples are collected with a new, disposable Teflon®or polypropylene <br /> bailer. The groundwater is carefully poured into selected sample containers (40-milliliter [ml] glass vials, 1,000- <br /> ml glass amber bottles, etc.), which are filled so as to produce a positive meniscus. <br /> Depending on the required analysis, each sample container is preserved with hydrochloric acid, nitric acid, etc., <br /> or it is preservative free. The type of preservative used for each sample is specified on the Chain-of-Custody <br /> record. <br /> Each vial and glass amber bottle is sealed with a cap containing a Teflon®septum, and subsequently examined <br /> for air bubbles to avoid headspace, which would allow volatilization to occur. The samples <br /> are promptly transported in iced storage in a thermally-insulated ice chest, accompanied by a <br /> Chain-of-Custody record, to a California state-certified laboratory. <br /> Water generated during purging and cleaning is contained and transported off site for treatment and disposal. <br />