Cautions about using CLARC
The requirements and procedures for establishing cleanup levels that are protective of human health and the environment are specified in Washington's Cleanup Rule, Chapter 173-340 WAC. Using data in the CLARC tables may not be sufficient to establish cleanup levels under this regulation.
Using formula values as cleanup levels
The formula values pre-calculated under standard Method B and C and provided in CLARC are not cleanup levels. For example, the formula values do not account for consideration of:
- Applicable state and federal laws (for all media)
- Surface water impacts (for groundwater)
- Ecological impacts (for surface water and soil)
- Residual saturation limit for protection of groundwater (for soil)
- Vapor pathway (for soil and groundwater)
- Lower explosive limit limitation (for air)
- Natural background concentrations (for all media)
- Practical quantitation limit (for all media)
- NAPL (non-aqueous phase liquids) limitation (for surface water and groundwater)
- Total site cancer risk and hazard index (for all media)
Ecology may also establish cleanup levels that are more stringent than those required under the applicable method when we determine, based on a site-specific evaluation, that such levels are necessary to protect human health and the environment.
Limitations of CLARC
Modified Method B and C (Site-Specific Risk Assessment)
CLARC does not provide pre-calculated formula values for modified Method B or C. The calculation of modified Method B or C values requires the use of site-specific and/or chemical-specific values instead of the default values provided in the regulation.
Soil–Direct Contact Pathway: Concurrent Exposure (Ingestion and Dermal Contact)
For petroleum mixtures, the standard Method B and C formula values are based on concurrent exposure (ingestion and dermal contact; see Equation 740-3 in WAC 173-340-740). CLARC does not provide pre-calculated standard Method B or C formula values for petroleum mixtures because it requires special analysis to determine the types of petroleum fractions present at the site. See Table 830-1 in WAC 173-340-900.
For hazardous substances other than petroleum mixtures, the standard Method B and C formula values are based on ingestion only and CLARC does provide pre-calculated values for those substances. Evaluation of concurrent exposure (ingestion and dermal contact) for hazardous substances other than petroleum mixtures is only required under modified Method B and C, and then only under certain specified circumstances. See Equations 740-4 and -5 in WAC 173-340-740. CLARC does not provide pre-calculated modified Method B or C formula values.