Cleanup Levels and Risk Calculation (CLARC)
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Please read the information contained in 'Cautions and Limitations' before navigating this site.

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Table of Contents

Cautions and Limitations

History of Changes

CLARC Release Notes

Welcome to CLARC

Welcome to the Cleanup Levels and Risk Calculation (CLARC) web site. Here you’ll find information to help establish cleanup levels for hazardous waste sites to comply with the Model Toxics Control Act (MTCA) Cleanup Regulation, chapter 173-340 WAC. This site is developed and maintained by the Washington State Department of Ecology (Ecology).

All information can be accessed from the Table of Contents  or from the drop-down menus above. A few of the more important links are available to the left.

May 2014 Changes: We have made significant changes to this web site, with more planned for the future.

The searchable chemical substance database has been disabled.

To find information:

  • Cleanup level information is now contained in an Excel spreadsheet and pdf files. These are accessed here or from the “CLARC Data Tables” link on the left side of the page. The files contain Methods A, B, and C cleanup levels, Applicable or Relevant and Appropriate Requirements (ARARs), toxicity values, and physical parameters.
  • The drop-down menus at the top of the page provide access to information about MTCA, guidance for determining cleanup levels, and tools to help set cleanup standards. There are no significant changes from the previous version of CLARC.
  • Future plans include the addition of simplified cleanup level calculations for the soil-to-groundwater pathway, the vapor intrusion pathway, and terrestrial ecological evaluation.

We have:

  • Updated many toxicity values to be consistent with EPA’s November 2013 Regional Screening Level (RSL) tables. See the “History of Changes” for a summary. The list of hazardous substances in CLARC is unchanged.
  • Expanded the sources of toxicity values to include those from the California Environmental Protection Agency (Cal-EPA) and the Agency for Toxic Substances and Disease Registry (ATSDR). However, the New Jersey Department of Environmental protection oral slope factor for chromium (VI) and the Cal-EPA oral and inhalation cancer potency factors for ethylbenzene are not included pending further evaluation.
  • Added Inhalation Correction Factors for chemicals that did not previously have them. This allows the calculation of Method B and Method C groundwater cleanup levels for additional chemicals.

Caution: The use of CLARC alone is not sufficient to establish cleanup levels under the MTCA Cleanup Regulation, chapter 173-340 WAC. Please refer to 'Cautions and Limitations' before using CLARC to develop cleanup levels. The “Guidance” dropdown menu (above) contains links to information about selecting cleanup levels. It also links to important information about toxicity and cleanup levels for 3 chemicals: tetrachloroethylene, trichloroethylene and vinyl chloride.

If you have questions or need assistance please contact Jim White.