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® SOLUBLE DESIGNATED LEVEL FOR SOIL cleanup levels must: AT A CONTAMINATED SITE ❑ be the lowest concentrations for the individual pollutants which are technologically and eco- DOMESTIC nomically achievable; WATER WELL CONTAMINATED SITE ❑ not pose a hazard to health or to the environ- ment;and o. lu ...X n mg soluble As/kg soil ❑ not exceed the maximum concentrations allow- ` 0 oos X n mg % Iter of exlr0ct able under applicable statutes and regulations from the WET � for individual pollutants,including applicable mg Arsenic , water quality standards. (o.00s X n) liter of While conventional risk assessment can be used to leachate satisfy the second of these requirements,this technique will not satisfy the third requirement. Designated Lev- ATTENUATION Cl —FOLD els for contaminated soil constituents,calculated by using the Designated Level Methodology,may be used to determine compliance with this last requirement,i.e., that remaining contaminants do not threaten to exceed Water California's water quality standards. Table CONCLUSION AND STATUS 0.005 mg Arsenic/liter of water GROUND (Proposition 65 regulatory level) ,� WATER When combined with the waste classification,site FLOW assessment,and cleanup level setting processes of ® DTSC and the State Water Board's Chapter 15 regula- Figure 8 tions,The Designated Level Methodology can provide a complimentary set of procedures to ensure the protec- for conditions that exist at the site. The standard WET tion of both public health and California's water re- uses an buffered acidic extraction solution designed to sources. Comments received during public review of account for the acidic conditions often encountered in an early draft of The Designated Level Methodology staff sanitary landfills. If soils at the site being investigated report were used to produce the October 1986 edition. will only exist under neutral or basic conditions,deion- In June 1989,an updated edition of the report was pro- ized water or another more suitable extraction solution duced to bring the document in line with then-existing may be substituted for the standard WET buffer solu- statutes,regulations,and waste testing methods. Fur- tion. ther updating of this nature is needed,and will be made as Regional Board staff resources are made avail- able for the effort. If contaminated soils are found to threaten benefi- Staff of the Central Valley Regional Water Quality tial uses of ground or surface water resources,cleanup Control Board has shared this report with the State levels must be chosen. To satisfy the antidegradation Water Board and the other Regional Water Boards,and policy,and recently readopted State Water Board Reso- has been working with staff of the State Water Board to lution No.92-49,Policies and Procedures for Investigation develop statewide policy in this area. and Cleanup and Abatement of Discharges Under Water Copies of The Designated Level Methodology staff re- Code Section 13304,background concentrations of con- port my be obtained from the reception desk at the Sacra- taminants must be chosen as cleanup levels,unless mento Office of the Regional Water Board. background levels are technologically or economically infeasible to achieve. If background levels are determined to be infea- sible,cleanup levels greater than background may be selected. As detailed in§2550.4 of Title 23 of CCR,such Page 8 Summary of The Designated Level Methodology