ARCHIVED REPORTS_2005_3 - Laserfiche WebLink

Home Browse Search

SOLUBLE DESIGNATED LEVEL FOR SOIL AT A CONTAMINATED SITE DOMESTIC WATER WELL CONTAMINATED SITE 0.005 x in mg soluble As / kg soil ).005 x n liter of extract in:a-*J..,.,..from the WET T Arsenic (o.005 x n) liter of leachate n— FOLD ATTENUATION 0.005 mg Arsenic / liter of water GROUND ( Proposition 65 regulatory level I WATER FLOW Figure 8 for conditions that exist at the site. The standard WET uses an buffered acidic extraction solution designed to account for the acidic conditions often encountered in sanitary landfills. If soils at the site being investigated will only exist under neutral or basic conditions, deion- ized water or another more suitable extraction solution may be substituted for the standard WET buffer solu- tion. SOIL CLEANUP LEVELS If contaminated soils are found to threaten benefi- cial uses of ground or surface water resources, cleanup levels must be chosen. To satisfy the antidegradation policy, and recently readopted State Water Board Reso- lution No. 92-49, Policies and Procedures for Investigation and Cleanup and Abatement of Discharges Under Water Code Section 13304, background concentrations of con- taminants must be chosen as cleanup levels, unless 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, suct :leanup levels must: ❑ be the lowest concentrations for the individual pollutants which are technologically and eco- nomically achievable; ❑ not pose a hazard to health or to the environ- ment; and ❑ not exceed the maximum concentrations allow- able under applicable statutes and regulations for individual pollutants, including applicable water quality standards. While conventional risk assessment can be used to satisfy the second of these requirements, this technique will not satisfy the third requirement. Designated Lev- 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 California's water quality standards. CONCLUSION AND STATUS When combined with the waste classification, site assessment, and cleanup level setting processes of DTSC and the State Water Board's Chapter 15 regula- tions, The Designated Level Methodology can provide a complimentary set of procedures to ensure the protec- tion of both public health and California's water re- sources. Comments received during public review of an early draft of The Designated Level Methodology staff report were used to produce the October 1986 edition. In June 1989, an updated edition of the report was pro- duced to'bring the document in line with then -existing statutes, regulations, and waste testing methods. Fur- ther updating of this nature is needed, and will be made as Regional Board staff resources are made avail- able for the effort. Staff of the Central Valley Regional Water Quality Control Board has shared this report with the State Water Board and the other Regional Water Boards, and has been working with staff of the State Water Board to develop statewide policy in this area. Copies of The Designated Level Methodology staff re- port my be obtained from the reception desk at the Sacra- mento Office of the Regional Water Board. Page 8 Summary of The Designated Level Methodology