Laserfiche WebLink
FIELD PROCEDURE <br /> The following section describes procedures used by Ultramar field <br /> personnel in the performance of ground-water sampling <br /> Ground-Water Level and Total Depth Determination <br /> A water-level indicator is lowered down the well and a measurement of the <br /> depth to water from an established reference point on the casing is <br /> taken The indicatortplo�edthsofsthetwelluns takebottBothfthethe <br /> water-level <br /> measurement of the to p <br /> and total depth measruements are taken to the nearest 0 01-foot <br /> Visual Analys�s of Ground_Water <br /> Prior to purging and sampling ground water monitoring wells, a water <br /> sample 7s collected from each well for subjective analysis The visual <br /> analysis involves gently lowering a clean, disposable, polyethylene bailer <br /> to approximately one-half the bailer length past the water table <br /> interface. The bailer is then retrieved, andctheosample container the d within <br /> the battler is examined for floating pr <br /> ce of a <br /> petroleum product sheen If measurable free product tis noted in the <br /> bailer, a water/product interface probe is used to determine the thickness <br /> of the free product to b nearest <br /> depthot The to product} fromstheffree <br /> depth <br /> product is determined y subtracting <br /> to water. <br /> Monitoring_Well _Purging, and Sam lin <br /> Monitoring wells are purged by removing approximately four casing volumes <br />• of water from the well using a clean disposable bailer or electrical <br /> submersible purge pump. Purge volumes are calculated prior to purging <br /> During purging the temperature, pH, and electric conductivity are <br /> monitored. The well tis sufficiently purged when. the four casing volumes <br /> have been removed, the temperature, <br /> pH, and conductivity have stabilized <br /> to within 10% of the initial readings, and the ground water being removed <br /> is relatively free of suspended solids After purging, ground water <br /> levels are allowed to stabilize to within 80% of the initial water level <br /> reading A water sample is then collected from each well with alean, <br /> disposable polyethylene bailer If the well is bailed dry pr <br /> ior to <br /> removing the minimum volume of water, the ground water is allowed to <br /> recharge. If the well has recharged to within 80% of the initial reading <br /> within two hours, the well will continue to be purged until the minimum <br /> volume of water has been removed If the well has <br /> not <br /> wellechargedlto at <br /> least 80% of the initial reading within two hours, <br /> the to contain formational <br /> water <br /> theand <br /> is stored wate55er samploned <br /> ldrumslattthe <br /> le <br /> Ground water removed from <br /> site and labelled pending disposal <br /> In wells where free product is detected, <br /> the wells will be bailed to <br /> remove the free product An estimate of the volume of product and water <br /> will be recorded If the free product thickness is reduced <br /> tho thelpoint <br /> where a measurable thickness is no longer present <br /> ground-water sample will becollected <br /> thickness measuif free �ementrwpllsbettakenuandua <br /> bailing, a final free product <br /> ground-water sample will not be collected <br />