California Regional Water Quality Control Board Issues Tool for Closure of Low-Risk Solvent Sites

San Francisco Bay Regional Water Quality Control Board (Water Board) staff recently completed a document titled the draft "Assessment Tool for Closure of Low-Threat Chlorinated Solvent Sites". The assessment tool is available on the Water Board’s website under "Cleanup Complete" Determinations.

There is no comment deadline and the assessment tool is available for use immediately.  Substantive comments about the document can be submitted in writing, via email, to Alec Naugle, Chair, Water Board staff Groundwater Committee.

About the assessment tool:

The assessment tool was prepared by the Water Board staff’s groundwater committee over the last three years, in consultation with selected local groundwater management agencies. It includes four main sections: introduction, recommended closure criteria (listed below), application of selected criteria, and policy discussion.

Develop a complete Conceptual Site Model (CSM)

  1. Pollutant sources are identified and evaluated
  2. The site is adequately characterized
  3. Exposure pathways, receptors, and potential risks, threats, and other environmental concerns are identified and assessed

Control sources and mitigate risks and threats

  1. Pollutant sources are remediated to the extent feasible
  2. Unacceptable risks to human health, ecological health, and sensitive receptors, considering current and future land and water uses, are mitigated
  3. Unacceptable threats to groundwater and surface water resources, considering existing and potential beneficial uses, are mitigated

Demonstrate that residual pollution in all media will not adversely affect present and anticipated land and water uses

  1. Groundwater plumes are decreasing
  2. Cleanup standards can be met within a reasonable timeframe
  3. Risk management measures are appropriate, documented, and do not require future Water Board oversight