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Artesian Environmental Consultants Standard Operating Procedures MQNITORING WELL SAMPLING Prior to groundwater sampling, initial water level and floating liquid hydiocarbon measurements are recorded for each well Each well is sounded for depth to ascertain if silting has occurred and to verify the actual depth below ground surface These measurements are used to calculate the volume for each well At this time, all non -dedicated pumping and sampling supplies are washed with an Alconox solution, rinsed with clean water, and final rinsed with either distilled or deionized water to prevent any cross contamination from other sampling events Each well is purged by evacuating a minimum of three well -casing volumes of groundwater from the well The well water may be evacuated either by bailing, or pumping Any of the following may be used for bailing a dedicated pvc bailer, sterile disposable polyethylene bailer, or a stainless steel bailer For pumping the groundwater out of the well, a downhole impeller type pump (dedicated or removable with PVC tubing), a downhole dedicated bladder pump, or a surface peristaltic pump is used ' After three to four well volumes are pumped, each well is permitted to recharge to at least 80% of original capacity or for two hours, whichever occurs first The water is then measured to verify whether the well has stabilized Stabilization is determined by measuring the parameters of pH, ' temperature, and electrical conductivity Stabilized measurements indicate that formation water has entered the well When two subsequent measurements of these three parameters are within 10% of each other, the well is considered stabilized and is ready to be sampled The samples are collected using a new polyethylene bailer with a bottom siphon and nylon cord. The bailers are disposable, and therefore, never reused. The groundwater sample is visually ' inspected for the presence of free product in the sampling bailer Agitation is minmuzed during sample retrieval to prevent aeration during the transfer from the well to the laboratory prepared sample containers Duplicate water samples are collected from the well and siphoned into three, 40 ml, VOA, septum top vials, with additional 950 ml samples collected in an amber glass bottles or polyethylene bottles depending on the analyses to be performed. The VOA vials are filled completely, leaving no headspace, and are sealed with Teflon -lined lids All samples are labeled, chilled to 0° C in an ice chest, and sent to a California State Certified hazardous materials testing i laboratory under chain -of -custody documentation All groundwater samples are collected in accordance with California Regional Water Quality Control Board (RWQCB) procedures described in the Leakang Underground Fuel Tank (LUFT) Field Manual, the Tri -Regional Board Staff Recommendanons for Preliminary Evaluation and Investigation of Underground Tank Sites, and local regulatory guidelines Standard Environmental Protection Agency (EPA), San Francisco Bay Regional Water Quality Control Board (SFBRWQCB), and Department of Health Services (DHS) methodologies for sampling and analyses are routinely utilized ' Chain of Custody documentation accompanies all samples to the laboratory A copy of the Chain of Custody documentation is attached to the Certificate of Analysis Monitor well purge water is properly stored and labeled on site in DOT 17-H containers pending Off site disposal