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iThis section describes the routine procedures followed by HETI while collecting groundwater samples for chemical analysis. These procedures include decontamination, water level measurements, well purging, physical parameter measurements, sample collection, sample preservation, and sample handling. Critical sampling ob)ecbves for HETI are to- 1 Collect groundwater samples which are representative of the sampled matrix 2. Maintain sample integrity from the time of sample collection to delivery to the analytical laboratory Sample analyses, methods, containers, preservation, and holding tunes are presented in Table A-1 All physical parameter measuring and sampling equipment shall be decontarxunated prior to measurement and sample collection using a tnsodium phosphate or Alconox solution wash, followed by two separate rinses in tap water, followed by one rinse in steam-distilled water Any sampling equipment surfaces or parts that might absorb specific contaminants, such as plastic pump valves,impellers,etc,are to be cleaned in the same manner. Sample bottles,bottle caps, and septa used for sampling volatile organics are thoroughly pre- cleaned in either the laboratory or the factory All appropriate measures shall be taken to assure continued sterility of the containers issued by the contract laboratory prior to usage at the pro,ect site. During field sampling,equipment which has been placed in a well shall be decontanunated by washing with a tnsodrum-phosphate or Alconox solution followed by two rinses in tap water and one rinse in steam-distilled water Water Level Measurements Prior to purging and sampling any wells, the stat2c-water level shall be measured by use of an electronic sounder and/or calibrated portable oil-water interface probe Both static water level and separate phase product thickness shall be measured and noted to the nearest±O 01 foot Interface probe results shall be confirmed by sampling the top of the water column with a clear bailer and measuring any floating product thickness to the nearest f0 01 foot with an engineers scale tape In all cases a clear bailer sample will be taken from each well to check for color,sheen and undetected floating product. If floating product of any measureable thickness is observed, no sampling will be performed for that well. If visible product sheen is observed, sampling shall proceed under normal protocols. The lire used to lower the bailer shall be discarded after each use to preclude the possibility of cross contamination Field observations (e g, well rntegnty, product odor, turbidity, water color, odors, etc) shall be recorded on the HETI Purge/Sample Sheet (Plate A-2). Before and after the use of the electric sounder, interface probe, non-dedicated bailer, or any other down well equipment,each will be decontaminated by washing ii a trisodrum phosphate or,Alconox solution, followed by a double rinse with tap water, followed by a rinse with steam-distilled water I I " I ! i II I I 9I I 'I 1 i kk i 11