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i� <br /> 7 <br /> '1 <br /> Harding Lawson Associates <br /> ,- V been very difficult to obtain a permit fox- incineration within <br /> } <br /> California. Thus, we anticipate long delays and will not con- <br /> - sider this option further. <br /> In-situ--s il venting - soil venting removes volatile <br /> o-, <br /> hydrocarbons from soil by applying a vacuum below the surface. <br /> Air that has been in contact with soil containing volatile com- <br /> pounds includes vapors in proportion to the saturation vapor <br /> If pressure :of hydrocarbons in gasoline. Applying a vacuum below <br /> x <br /> L. a, <br /> ground extracts these vapors, which are then sent through an <br /> r emission control system to meet air emission criteria. A.permit <br /> - _ . <br /> would be required from the SJAPCD. <br /> > � 3 <br /> L�r In-situ vapor extraction technology is well estab- <br /> lished. Thin <br /> � �� process has been demonstrated on similar sites and <br /> `" is considered reliable. Its afffectiveness, however, is closely <br /> related to permeabilityof the soils in` the extraction none. The <br /> `I <br /> soils must be.permeable enough to permit air flow, and the vapor <br /> pressure of individual compounds must be sufficiently high to <br /> , � . promote volatilization. An advantage to this alternative is that <br /> L massive excavation is not required.:: <br /> Because of the shallow,,.depth- to.graund 'water",.':and :the; <br /> i <br /> Y corresponding thinness he .vadose zone a� ,_this s1te,;' a series <br /> { s <br /> ! �.. of harizontai vaporxtraction;::wells would be_.lnstaXled,; .-The se <br /> e <br /> would be xnstailed in trenches, 3 to 4 feet below grade. The <br /> & _ r E <br /> hydrocarbon '.va ors "eattraoted -from`the'vadose` zoneo�ld.be routed <br /> througr a carbon.:treatment`, system prior to discharge into_the "$ <br /> air.'- The rate of operation would'be -determined during the <br /> L <br /> 18 <br /> 1 <br />