CLARC data tables and other technical information

Cautions on 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.

The source of each toxicity value listed in CLARC's Excel and PDF files is identified using the following abbreviations:

I = IRIS = Integrated Risk Information System database from the Environmental Protection Agency (EPA)
H = HEAST = Health Effects Assessment Summary Table from EPA
C = Cal EPA = California Environmental Protection Agency
A = ATSDR = Agency for Toxic Substances and Disease Registry
P = PPRTV = Provisional Peer-Reviewed Toxicity Values from EPA
X = PPRTV Appendix from EPA
S = Other EPA sources

Consistent with Washington's Cleanup Rule, Chapter 173-340 WAC, CLARC lists inhalation cancer potency factors and inhalation reference doses. These differ numerically from the similar inhalation unit risks and reference concentrations listed by EPA in its Regional Screening Levels (RSL) tables.

You can look for a chemical in CLARC using its CAS number, which is a registry number assigned by the Chemical Abstracts Service. A chemical substance may have many different names but most have only one CAS number. Numbers in CLARC that begin with "E"" are EPA identification numbers and are used due to the lack of a CAS number. The following substances do not have CAS numbers and a temporary CAS has been assigned in CLARC. 

No.	Temporary CAS	Data Group	Chemical or Parameter
1	unavailable19	General Chemistry	pH
2	unavailable08	Petroleum	tph: gasoline range organics, no detectable benzene
3	unavailable09	Petroleum	tph, diesel range organics
4	unavailable10	Petroleum	tph, heavy oils
5	unavailable11	Petroleum	tph, mineral oils
6	unavailable25	Petroleum	tph: gasoline range organics, benzene present
7	unavailable20	Radionuclides	gross alpha particle activity
8	unavailable21	Radionuclides	gross beta particle activity
9	unavailable23	Radionuclides	radium 226 and 228
10	unavailable13	VOCs	trihalomethanes, (total) (TTHMs)

 

Sources for natural background concentrations for metals by geographic area in Washington state:

• Regulation WAC 173-340-709: Methods for defining background concentrations
• Natural background soil metals concentrations (Ecology Publication No. 94-115)
• Summary table compiled from Natural Background Soil Metals Concentrations in Washington State (1994).