Development of Draft MTCA Model Remedy for Abandoned Mine Sites

Washington State Department of Ecology

Washington State

Model Mine Saddle Rock

Hart Crowser assisted the Washington State Department of Ecology by preparing a draft guidance document for cleaning up abandoned/inactive metal mine sites using a streamlined, model-remedy approach. Under the Model Toxics Control Act (MTCA), the state’s cleanup regulation, model remedies may be developed and implemented at certain well-defined sites without the need for conducting a site-specific feasibility study or disproportionate cost analysis. Hart Crowser evaluated regulatory constraints applicable to upland abandoned/inactive metal mine sites where waste rock and/or tailings are the main contaminant sources and direct contact/soil ingestion are the main exposure routes to humans and terrestrial organisms. As part of this project, Hart Crowser:

  • Outlined decision points needed for two model remedies, including excavating/disposing of mine wastes off-site and consolidating/capping mine wastes on site.
  • Identified data requirements and site characteristics for which of these model remedies would be appropriate, or whether both would be appropriate.
  • Identified Applicable or Relevant and Appropriate Requirements (ARARs) and substantive permit requirements that would likely need to be met in order to implement a model remedy.
  • Conducted a generic Feasibility Study and Disproportionate Cost Analysis to compare the conditions under which one or both of the model remedies could be selected as a cleanup action under MTCA.
  • Outlined a streamlined approach to conducting a Terrestrial Ecological Evaluation under MTCA that would be used to determine if one or both of the model remedies could be selected as a cleanup action under MTCA.
  • Presented a framework for conducting a Net Environmental Benefit Analysis that could be used to support a “no action” cleanup decision at sites where cleanup activities could result in more environmental harm than benefit.