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APPENDIX B--ITEM I <br /> GROUNDWATER SAMPLING PROCEDURES <br /> Groundwater samples were collected following water level measurements and subsequent <br /> purging of the wells selected for sampling Groundwater samples were analyzed by a laboratory <br /> that is certified by the California Department of Health Services to perform the specified <br /> analyses <br /> ' The following protocol was used in obtaining groundwater samples <br /> ❑ Before purging, water levels were measured with an electronic interface tape capable of <br /> ' measuring the static water level and hydrocarbon product/water interface in one <br /> immersion Purging proceeded sampling to maximize the collection of non-stagnant <br /> water Each well was purged with an 12-volt submersible pump until a minimum of three <br /> casing-volumes of groundwater had been removed or until the well had been pumped dry <br /> Temperature, pH, and conductivity were monitored throughout purging until these <br /> ' parameters had stabilized within acceptable limits The wells were sampled after 80 <br /> percent or greater recovery of static water level was achieved or until recharge produced <br /> sufficient volume of water to perform the required analysis <br /> ❑ To prevent potential cross-contamination between wells, all measuring, purging, and <br /> sampling equipment was washed in a non-phosphate detergent solution, rinsed with tap <br /> ' water, and then rinsed with distilled water prior to sampling each well <br /> ' ❑ Groundwater was collected from each well with a clean disposable bailer attached to a clean <br /> nylon cord Samples were decanted into 40-milliliter glass vials with TeflonTm-lined <br /> septa, and preserved with hydrochloric acid to a pH of 2 0 Samples were labeled and <br /> ' placed in a refrigerated cooler accompanied by the chain-of-custody Samples <br /> transported to the laboratory were analyzed within the specified holding time If samples <br /> were retained overnight at RMA, they were maintained at a temperature not exceeding 4° <br /> ' Celsius <br /> ' Samples were analyzed for TPHg using either EPA Test Method 8015M or a State approved <br /> GC/MS method BTEX and the gasoline oxygenatesladdrtives (including 1,2 DCA and EDB <br /> using EPA Test Method 8260B <br />