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Harding Lawson Associates <br /> A. Remedial Alternatives - Ground Water <br /> As discussed in the Problem Assessment Report, recommended <br /> clean-up levels corresponding to the State Drinking Water Action <br /> Levels (DWAL) are as follows: <br /> Benzene. . . . . . . . . . . . . . . . . . . . . . . . . . .0.7 ppb <br /> Toluene. . . . . . . . . . . . . . . . . . . . . . . . .].0o ppb <br /> Ethylbenzene. . . . . . . . . . . . . . . . . . > <br /> .680 ppb <br /> Total xylenes. . . . . . . . . . . . . . . . . . .620 opb <br /> r <br /> 1> Extraction lternatives <br /> a R. vertical extraction wells - Vertical extraction wells, <br /> located strategically across the site, would be actively pumped. <br /> Their size,: number, and locations, as well as pumping rates, <br /> would be determined by in <br /> aquifer tests. This methodology <br /> r -- ieldin water-bearing formations in <br /> is best suited to high.y' g. <br /> which large radii of influence can be developed. <br /> This method of ground-water extraction is well estab- <br /> lrai <br /> fished and has been used for many nears, and effectively <br /> N , <br /> at <br /> sites with petrc;leum -'hydrocarbons in the. ground water. Extrac- <br /> tion .-,ails are .frequently used as part of an overall ground-water <br /> remediation plan. The installation of any.type of well requires <br /> a permit from the San Joaquin Local Health District (SJLHD) . <br /> At...._this._site, <br /> tre primary drawback to this method of <br /> round water _extraction:xs.:thatrthe,-shallow sandy formation xs'' <br /> aFparentgy �e3ow=yiQ]cling formation-. It �s unlikely that: larg <br /> " radii of fnglusnce can he davelopecl, therefore, a gxeater'number£-; <br /> of::extracti.s�n ;walls wound oe:required This alternative is only <br /> 3. <br />