Ore Knob Mine Ashe County, NC
Ore Knob Mine Ashe County, NC
Ore Knob Mine Ashe County, NC
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<strong>Ore</strong> <strong>Knob</strong> <strong>Mine</strong><strong>Ashe</strong> <strong>County</strong>, <strong>NC</strong>RPM /OSC Panel DiscussionLoften Carr, RPM Terrence Byrd, OSCJune 2009
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Located in Laurel Springs, nearJefferson, <strong>Ashe</strong> <strong>County</strong>,North Carolina<strong>Ore</strong> <strong>Knob</strong> <strong>Mine</strong> Site HistoryFormer Copper <strong>Mine</strong> located in <strong>Ashe</strong><strong>County</strong>, <strong>NC</strong><strong>Mine</strong> operated intermittently from 1855until 1962Largest Copper Producer in <strong>NC</strong>Massive Sulfide Deposit produced:31,000 tons of Copper9,400 ounces of Gold145,000 ounces of SilverFrom 1,500,000 tons of <strong>Ore</strong>
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>3 Site Areas:1957 – 1962 Mill Site19 th Century Operations AreaTailings Impoundment4 Impacted Sub-Watersheds:<strong>Ore</strong> <strong>Knob</strong> BranchPeak CreekLittle Peak CreekSouth Fork New River
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Site Areas
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Site AreasTailings Impoundment~ 700 ft.~22 acres / ~720,000 CY
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Site Areas1957 Photo from Mining World
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Site Areas<strong>Ore</strong> <strong>Knob</strong> 1957-1962 Mill Site, conveyor and flotation mill foundations looking North.<strong>Ore</strong> <strong>Knob</strong> 1957-1962 Mill Site: <strong>Ore</strong> Bins in background left, Sawmill in foreground
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Surface waters<strong>Ore</strong> <strong>Knob</strong> Branch downstream of tailings pond, near confluence with Peak Creek
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Surface waters<strong>Ore</strong> <strong>Knob</strong> Branch confluence with Peak Creek
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Surface watersLittle Peak Creek at Freshwater Pond downstream of 1957-1962 Mill Site
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Surface watersSouth Fork New River confluence with Peak Creek
Human And Ecological Risks• <strong>Ore</strong> <strong>Knob</strong> Branch, Little Peak Creek and Peak Creek aretributaries to the South Fork of the New River• Peak Creek and Little Peak Creek are classified as trout waters• New River is classified as an outstanding resource water andwas the first river in the U.S. to receive a National Wild andScenic designation, is an American Heritage River and a StateScenic River
Impacts to <strong>Ore</strong> <strong>Knob</strong> Branch, LittlePeak Creek and Peak Creek• Biological Assessment has concluded that life can not be supported in<strong>Ore</strong> <strong>Knob</strong> Branch due to high metals content and low pH.• Copper and aluminum concentrations in Peak Creek and Little PeakCreek results in acute toxicity• pH levels in <strong>Ore</strong> <strong>Knob</strong> Branch are approximately 3.0 std units• All three water ways are impaired and 303(d) listed as not meetingdesignated uses
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Time Critical Removal ActionTailings Impoundment:
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Tailings Impoundment:- Surface slopes Southward- Surface Water ponds in 3 - 4 areas- Southern Pond drained via 24 inchconcrete pipe in unknown condition- Severe tailings erosion problems- Severe Acid <strong>Mine</strong> Drainage via Seeps- Damn subject to catastrophic failurefrom pipe blockage, major rain event, orseismic event
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Time Critical Removal ActionTailings ImpoundmentProposed Actions (Phase 1):- Perform a geotech investigation / stability analysis of tailings dam- Construct diversion channels to eliminate surface water run-on- Obtain freeboard in the downstream sediment pond- Capping and abandoning the decant pipe
Stability Analysis Findings• Phreatic surface is at or above the top of the starter dam.• Phreatic surface must be lowered to achieve stability duringconstruction.• Tailings Dam is critically unstable (FS = 1.01) (<strong>NC</strong>DENR/USBRrequire FS > 1.50)• Construction model has been identified to achieve FS = 1.71
EXPECTED CHANGE IN THE SITUATION SHOULDACTION BE DELAYED OR NOT TAKENSlope Failure and Massive Release ofTailings to Downstream Environment
Removal Actions To Date• Obtained freeboard in the sediment pond by removing over 15,000 cubicyards of tailings.• Excavated/blasted approximately 30,000 CY of mountainside(approximately 40% of diversion channel).• Held public meetings and outreach presentations in the <strong>Ashe</strong> Co. <strong>NC</strong>area.
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Current Revised Diversion Channel Alignment
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Completed Sediment Pond Excavation 2008Drainage / Diversion Channel Excavation
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>- Drilling and Blasting ofDrainage / Diversion ChannelSeismometers used during test blasts
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Excavation of TailingsNote: Orange oxidized tailing near surface andBlack un-oxidizided tailings at depth
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>Current progress of backfill operation on pond #3.
<strong>Ore</strong> <strong>Knob</strong>, <strong>NC</strong>QUESTIONS ?DISCUSSION ?
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