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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 = 7ur2h(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 />7 = 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 />