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GROUNDWATER TECHNOLOGY GROUNDWATER MONITORING AND SAMPLE COLLECTION PROTOCOL Groundwater Monitoring Groundwater monitoring Is accomplished using a INTERFACE PROBE" Well Monitoring System. The INTERFACE PROBE" Well Monitoring System is a hand held, battery operated device for measuring the depth to separate-phase hydrocarbons and depth to water. The INTERFACE PROBE" Well Monitoring System consists of a dual-sensing probe which utilizes an optical liquid sensor and electrical conductivity to distinguish between water and petroleum products. Monitoring Is accomplished by measuring from the surveyed top of well casing or grade to groundwater and separate-phase hydrocarbons if present. The static water elevation is then calculated for each well and a potentlometric surface map is constructed. If separate-phase hydrocarbons are detected the water elevation is adjusted by the following calculation: (Product thickness) x (0.8) + (Water elevation) = Corrected water elevation Groundwater monitoring wells are monitored in order of wells with lowest concentrations of volatile organic compounds to wells with the highest concentrations, based upon historical concentrations. If separate-phase hydrocarbons are encountered in a well, the product is visually inspected to confirm and nate color, amount, and viscosity. Monitoring equipment Is washed with laboratory grade detergent and rinsed with distilled or delonized water before monitoring each well. Groundwater Sampling Before groundwater samples are collected, sufficient water Is purged from each well to ensure . representative formation water Is entering the well. Wells are purged and sampled in the same order as monitoring, from wells with the lowest concentrations of volatile organic compounds to wells with the highest concentrations. Wells are purged using either a polyvinyl chloride (PVC) bailer fitted with a check valve or with a stainless steel submersible Grundfos pump. The purge equipment is decontaminated before use In each well by washing with laboratory grade detergent and tripled rinsing with deionized or distilled water. A minimum of 3 well-casing volumes of water are removed from each well while pH, electrical conductivity, and temperature are recorded to verify that "fresh" formation water is being sampled and the parameters have stabilized. If the well is low yielding, it may be purged dry ' and sampled before 3 casing volumes are purged. The wells are then allowed to recharge to approximately So percent of the initial water level before a sample is collected. Groundwater samples are collected from each well using a new, prepackaged disposable bailer and string. The water sample is decanted from the bailer Into laboratory-provided containers (appropriate for the analyses required) so that there is no headspace In the containers. Samples collected for benzene, toluene, ethylbenzene, xylene, and total petroleum hydrocarbons (rPH)-as-gasoline analyses are collected in 40-miilititer vials fitted with Tefion® septum lids. Samples are preserved with hydrochloric acid (HCL) to a pH of less than 2. Dissolved metals samples are filtered through a 0.45-micron paper filter in the field and preserved as required before submitting to the laboratory for analyses. All samples are labeled Immediately upon collection and logged on the chain-of-custody record. Sample label and chain-of-custody recorded Information includes the project name and number, sample identification, date and time of collection, analyses requested, and the sampler's name. Sample bottles are placed in plastic bags (to protect the bottles and labels) and on ice (frozen water) in an insulated cooler and are shipped under chain-of-custody protocol to the laboratory. The chain-of-custody record documents who has possession of the samples until the analyses is performed. Other pertinent information Is also noted for the laboratory use on the chain-of-custody record. Trip blanks (TBLBs) are used for each project as a quality assurance/quality control measure. The TBLSs are prepared by the laboratory and are placed in the insulated cooler and accompany the field samples throughout the sampling event.