Site Narrative
The Grizzly Hill Hydraulic Mine - Sluicebox Tunnels are located on unpatented BLM land. This +60 acre mine site has now been converted into a campground area and contains a principal sluicebox tunnel of roughly 300 linear feet. A smaller tunnel in the southwest part of the campground is approximately 200 linear feet. The inlet portion of this sluice tunnel represents a collapsed shaft which presents a physical hazard to small children and families using the campground. These tunnels probably contain significant concentrations of elemental mercury in residual sediments that have accumulated on the floor of each tunnel. The sluice tunnel inlet and outlet portal areas represent a physical safety concern in a high-level campground and recreational use area. Skin contact with mine discharge water represents a human health concern, where recreational miners access and stir up sediments within the sluice tunnel to extract small amounts of placer gold.
Previous/Existing Assessments
Discharge water from sluicebox tunnels is derived from both surface sources in the main hydraulic pit area during the winter and spring rainy seasons. Detailed water sampling, biota analysis, and mine site characterization is pending.
Estimated Costs
Estimated Costs: Bat-Gate Installation on tunnel portals (Phase 1), $60,000. Physical removal of mercury contaminated sediments from sluice tunnels and site reclamation costs (Phase 1) $200,000.
Risks: Water Quality, Physical Safety
AMLIS #: CA021800009
Location: N39 20 16, W120 14
Field Office: Folsom
Congressional District: Wally Herger
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