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i <br /> The jars were allowed to sit for thirty (30) minutes before insertion of an OVA probe <br /> through the aluminum foil into the headspace of the soil sample. The sample depth with <br /> ` the highest OVA readings was the basis for choosing which sample to submit for <br /> laboratory analysis. If all OVA readings in a well were zero, then the sample nearest to <br /> { and above the water table was analyzed. The soil boring logs in Appendix B show the <br /> t <br /> OVA readings and sample depths. <br /> All soil samples submitted to the laboratory were analyzed for BTEX per EPA <br /> Method 8020, and for TPH per EPA Method 418.1. Analytical results are discussed in <br /> Section 4. The samples were placed immediately owice in a cooler and later transported <br /> to the laboratory under standard chain-of-custody procedures. Chain-of-custody forms <br /> n used in this process are in Appendix C. <br /> sem" Hollow-stem augers used in boring operations were < :- ..irr-,nated by steam- <br /> cleaning methods between each boring. Also, the split-spoon sampler was <br /> decontaminated between each sampling point. <br /> MONITORING WELL CONSTRUCTION <br /> -All,three: 3 :soil borin s were converted.to monitoring wells. Construction details are <br /> shown in Appendix B. Wells were constructed using 4-inch diameter Schedule 40 PVC <br /> casing designed with screw-type, flush joints. No solvent, cement, glue, screws, nor <br /> mechanical adaptors were used at the casing joints. <br /> Each monitoring well was constructed with a single screened interval of 15 feet, with <br /> ter, five feet of screen above and 10 feet of screen below the water table. The screen slot size <br /> for each well was 0.010-in. A PVC cap was affixed to the bottom of the screened <br /> interval. <br /> A filter pack was placed to enclose the entire length of the screened section with an <br /> additional two feet of filter pack above the screened section. Filter pack material and size <br /> .-» used in each well was Monterey Sand plumber 3. <br /> Directly on top of the filter pact was constructed a 2-foot bentonite plug designed to <br /> prevent vertical migration of possible contaminants th-rough the annulus. The bentonite <br /> pellets were emplaced slowly and evenly by free-falling from surface. <br /> Y <br /> ,dry <br /> i 'tt <br /> a <br /> 3-2 <br /> 175-07.R5 4/241'41 <br />