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GROUNDWATER SAMPLE COLLECTION <br /> This section describes the routine procedures followed by HETI while collecting groundwater <br /> samples for cherrucal analysis. These procedures include decontanunatnon, water level <br /> measurements, well purging, physical parameter measurements, sample collection, sample <br /> preservation, and sample handling Critical sampling objectives for HETI are to: <br /> I. Collect groundwater samples which are representative of the sampled matrix. <br /> 2. Maintain sample integrity from the time of sample collection to delivery to the analytical <br /> laboratory <br /> Sample analyses, methods, containers, preservation, and holding times are presented in Table <br /> A-1 <br /> All physical parameter measuring and sampling equipment shall be decontaminated prior to <br /> measurement and sample collection using a tnsodium phosphate or Alconox solution wash, <br /> followed by two separate rinses in tap water, followed by one nese in steam-distilled water. <br /> Any sampling equipment surfaces or parts that night absorb specific contaminants, such as <br /> plastic pump valves,impellers,etc, are to be cleaned in the same manner <br /> Sample bottles, bottle caps, and septa used for sampling volatile organics are thoroughly pre- <br /> cleaned in either the laboratory or the factory All appropriate measures shall be taken to <br /> assure continued stenhty of the containers issued by the contract laboratory prior to usage at <br /> the project site <br /> During field samphng, equipment wluch has been placed in a well shall be decontaminated by <br /> washing with a tnsodium-phosphate or Alconox solution followed by two rinses in tap water <br /> and one nnse in steam-distilled water. <br /> Water Level Measurements <br /> Prior to purging and sampling any wells, the static-water level shall be measured by use of an <br /> electronic sounder and/or calibrated portable oil-water interface probe Both static water <br /> level and separate phase product thickness shall be measured and noted to the nearest ±0 Ol <br /> foot Interface probe results shall be confirmed by sampling the top of the water column with a <br /> clear bailer and measuring any floating product thickness to the nearest +L0 01 foot with an <br /> engineers scale tape In all cases a clear bailer sample will be taken from each well to check for <br /> color,sheen and undetected floating product. If floating product of any measureable thickness is <br /> observed, no sampling will be performed for that well If visible product sheen is observed, <br /> sampling shall proceed under normal protocols <br /> The lune used to lower the bailer shall be discarded after each use to preclude the possibility of <br /> cross contamination Field observations (e g, well mntegnty, product odor, turbidity, water <br /> color, odors, etc) shall be recorded on the HETI Purge/Sample Sheet (Plate A-2) Before and <br /> after the use of the electric sounder, interface probe, non-dedicated bailer, or any other down <br /> well equipment, each will be decontaminated by washing in a trisodium phosphate or Alconox <br /> solution, followed by a double nnse with tap water, followed by a rinse with steam-distdied <br /> water <br /> I <br /> 9 <br />