Abandoned Gold Mines

Amador County
Client
City of Sutter Creek, Fornine Development, Various Private Landowners

Services

Environmental Services

Geocon Leaders

Jim Brake



Geocon has investigated and remediated several abandoned mines in Amador County within the historic Motherlode mining district of California to support redevelopment of these properties for commercial, recreational, and residential uses. Site investigations have included Preliminary Endangerment Assessments to characterize the nature and extent of contaminants of concern (primarily arsenic, lead, chromium, mercury, cyanide, and petroleum hydrocarbons) in soil, waste rock fills, and tailings. Detailed evaluations of naturally occurring arsenic in native soil and rock were also performed to distinguish arsenic in its natural geologic state from arsenic concentrated in waste rock and tailings by mining-related processes. Human health and ecological risk assessments were also performed to estimate the health risk to future site users and ecological receptors, and to develop appropriate cleanup levels. Removal Action Workplans were prepared for each mine presenting the results of investigation and risk assessment and evaluating and selecting appropriate remediation approaches. The selected remediation approach for commercial and recreational land use was typically capping of mine waste with clean fill and the new development itself. The remediation approach for residential land use was to plan residential use for areas on the properties where mine waste did not exist or relocation of mining-related waste materials to areas of the Site where it could be capped and covered by commercial development.

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