Project Description:
The Pond Hydraulic Mine sluice tunnel is approximately 3,000 feet in length and is located on both unpatented BLM administered land and adjoining patented hydraulic placer gold mines. The sluice tunnel outlet is located on BLM administered land. Water, sediment, and biota sampling has been performed at the sluice tunnel inlet and outlet portals during the 2004-2009 period. The tunnel sediments are known to contain elevated concentrations of elemental mercury. The sluice tunnel portals are currently gated, since it represents a potential physical safety concern.
Previous/Existing Assessments:
The Pond Tunnel outlet site has been subjected to water, sediment, and biota sampling by the USGS technical team and is known to contain elevated concentrations of elemental mercury in the tunnel sediment and methyl mercury in some of the biota species.
Reclamation/Recommendations:
- Sluice Tunnel Characterization: Collect data on the geological, hydrological and biological resources inside the sluice tunnel. Sampling was initiated in FY 2000. The geological and hydrological information will be used in determining the best and most cost efficient method for controlling or eliminating the production of methyl mercury.
- Some hydraulic mine sluice tunnel sites also pose a high risk to the general public. A mine portal gate, using bat friendly gate designs, have been erected at this site to deter public access into the underground tunnel areas.
- Land Status: The site is located on both unpatented BLM administered land and adjoining patented hydraulic placer gold mines.
- No restoration methods are being considered at this time.
Risks: Water Quality, Physical Safety, Mercury
Location: N39 12 02, W120 52 05
Field Office: Mother Lode
Congressional District: 02
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