From: Flurries and Torrents
Sidebar
One hundred years after prospector Felix Pedro first found gold in the streams on the outskirts of Fairbanks, Chris Haigh, engineer with the City of Fairbanks says, “Alaska’s gold mining culture is alive and well.“You can still see some of the old giant dredges around from the ’20s and ’30s that dug into the gravel riverbeds searching for gold.” He says prospecting persists. “In town it’s a commercial venture organized to attract tourists,” but at the other end of the spectrum, “there is a major international gold mining operation just 20 miles from the city.“Historically, the most common method used to search for gold in the Fairbanks area was placer mining,” says Haigh. In placer mining, sands and gravel are collected from alluvial deposits, placed in a vessel, and washed with large volumes of water. Agitation forces the gold to settle to the bottom of the vessel while the sand and gravel are discarded. When practiced on an industrial scale, the process can generate high yields in gold but also huge volumes of silt.
Haigh says the problems arising from mining can be seen as a sort of precursor to the stormwater issue. “Because of the difficulty they were having disposing of the silt that the mines generate, some of the major mining operations have turned to using closed-loop systems.”
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September 2007
From: Flurries and Torrents
Sidebar
One hundred years after prospector Felix Pedro first found gold in the streams on the outskirts of Fairbanks, Chris Haigh, engineer with the City of Fairbanks says, “Alaska’s gold mining culture is alive and well.“You can still see some of the old giant dredges around from the ’20s and ’30s that dug into the gravel riverbeds searching for gold.” He says prospecting persists. “In town it’s a commercial venture organized to attract tourists,” but at the other end of the spectrum, “there is a major international gold mining operation just 20 miles from the city.“Historically, the most common method used to search for gold in the Fairbanks area was placer mining,” says Haigh. In placer mining, sands and gravel are collected from alluvial deposits, placed in a vessel, and washed with large volumes of water. Agitation forces the gold to settle to the bottom of the vessel while the sand and gravel are discarded. When practiced on an industrial scale, the process can generate high yields in gold but also huge volumes of silt.
Haigh says the problems arising from mining can be seen as a sort of precursor to the stormwater issue. “Because of the difficulty they were having disposing of the silt that the mines generate, some of the major mining operations have turned to using closed-loop systems.”