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to that posed by wastes in an unlined landfill. There- Soluble Designated Levels. For this type of site assess- <br /> fore, the Designated Level Methodology can be used to ment,the WET procedure is often modified to account <br /> calculate Designated Levels for site contaminants for conditions that exist at the site. The standard WET <br /> which,if exceeded,indicate a threat to the beneficial uses an buffered acidic extraction solution designed to <br /> uses of nearby ground or surface waters. California's account for the acidic conditions often encountered in <br /> water quality standards(from the applicable Water sanitary landfills. If soils at the site being investigated <br /> Quality Control Plans)are used to select water quality will only exist under neutral or basic conditions, <br /> goals which protect the beneficial uses of waters which deionized water or another more suitable extraction <br /> could be adversely impacted by site contaminants. solution may be substituted for the standard WET <br /> Attenuation factors are estimated based upon site buffer solution. <br /> hydrogeologic data and information on the contami- <br /> nants themselves. Soluble Designated Levels are then <br /> calculated by multiplying the water quality goals by SOIL CLEANup LEvELB <br /> the attenuation factors and dividing by the ten-fold <br /> dilution of the WET or the 20-fold dilution of the TCLP If contaminated soils are found to threaten beneficial <br /> (for volatile contaminants). The results are expressed uses of ground or surface water resources,cleanup <br /> as milligrams of soluble constituent per liter of extract. levels must be chosen. To satisfy the antidegradation <br /> policy,and recently adopted State Water Board Resolu- <br /> Soil samples from the site are subjected to the WET tion No.92-49,Policies and Procedures for Investigation <br /> and/or TCLP procedure and results are compared with and Cleanup and Abatement of Discharges Under Water <br /> these site-and constituent-specific Soluble Designated Code Section 13304,background concentrations of <br /> Levels. Cleanup or mitigation would be required for contaminants must be chosen as cleanup levels,unless <br /> soils having extractable concentrations which exceed background levels are technologically or economically <br /> infeasible to achieve. <br /> SOLUBLE DESIGNATED LEVEL FOR SOIL <br /> AT A CONTANCENATED SITE If background levels are determined to be infeasible, <br /> cleanup levels greater than background may be se- <br /> DOMESTIC lected. As detailed in§2550.4 of Title 23 of CCR,such <br /> WATER <br /> WELL CONTAMINATED STfE cleanup levels must <br /> .; •••' • �Ht{tjl(N�lti{lltill:hCtSllt{t t141ry ❑ be the lowest Concentrations for the individual <br /> " pollutants which are technologically and economi- <br /> <I•l+fvwl lNaNxuWXI• <br /> r t NMd�b�RaK F <br /> cally achievable; <br /> ❑ not pose a hazard to health or to the environment; <br /> (o.00s.n) s and <br /> 4.drs <br /> ❑ not exceed the maximum concentrations allowable <br /> under applicable statutes and regulations for <br /> i <br /> individual pollutants,including applicable water <br /> quality standards. <br /> - ! While conventional risk assessment can be used to <br /> satisfy the second of these requirements, this technique <br /> will not satisfy the third requirement. Designated <br /> Levels for contaminated soil constituents,calculated by <br /> OMS AnMrt Mw of water c�No using the Designated Level Methodology, may be used to <br /> t PropoYsow as raquh"k.el) a wow determine compliance with this last requirement,i.e., <br /> that remaining contaminants do not threaten to exceed <br /> Figure 8 California's water quality standards. <br /> Jon B.Marshack,D.Env. Page 15 <br />