Air, water and soil remedial objectives

We use the direct exposure levels listed in the EPA Regional Screening Levels (RSL) table for residential and industrial exposure scenarios as screening levels to determine whether levels of soil contamination at a site warrant further investigation or cleanup.
    • Please use one of the links to the Summary Table in the top row of links.
      • The calculator can be used to adjust the input parameters to come up with site-specific screening levels.
      • The background document and user's guide identify the toxicity values, equations and exposure assumptions used to calculate Regional Screening Levels.
    • Screening values presented in the Regional Screening Levels table are based on human health risk from the combined exposure of direct soil ingestion, dermal contact with soil and inhalation of vapors or particulates associated with soil.
      • Other pathways, such as indoor air or food chain effects, may need to be considered on a site-specific basis.
      • Users should also be aware that some sites in sensitive ecological settings may need to be evaluated for potential ecological risk.
      • In addition, please continue to take into consideration:
        • Our specific toxicity values, such as an inhalation Reference Concentration (RfC) of 7.0 ug/m3 for 1,1-dichloroethylene (1,1-DCE) and an oral Reference Dose (RfD) of 0.0011 mg/kg/day for diisopropyl methylphosphonate (DIMP).
        • For facilities where multiple non-carcinogenic chemicals are present, HQ values should be divided by a factor of 10 to account for additivity. If adjusted tables values are exceeded, consultation with a toxicologist is recommended to assess likely impact on specific target organs.
        • For lead, consideration of site-specific inputs to the IEUBK or ALM lead models and consultation with a toxicologist is strongly recommended for facilities with lead levels in soil that exceed the residential or worker table values.
    • For workers at facilities where soil-intensive use is anticipated, more analysis and consultation with a toxicologist will be required to determine appropriate site-specific inputs to the risk equations.
Screening levels protective of groundwater quality
We use the groundwater protection level and leachate reference concentration columns in the Groundwater Protection Values (GPV) soil cleanup table.
  • The last column identifies the water standard used in the calculations, which are based on standards and methods established and employed by the Water Quality Control Commission.
  • These two columns should be consulted when reviewing site data because decisions on whether further evaluation or remediation are needed may be based on the mobility of constituents and their potential to reach and degrade groundwater quality.
Air screening concentrations

CDPHE Air screening concentration table

EPA Regional Screening Levels

Although the method by which we calculate air exposure screening numbers is identical to the EPA's, we recommend you continue to use our table because there are a few differences between our air screening concentration table and air columns listed in the Regional Screening Levels.
  • Target indoor air concentrations for those chemicals not included on our list can be found in the EPA Regional Screening Levels.