DeMaree, D., C. Monohan, S. Riggins, and D. Brown. Subsurface Waters at Malakoff Diggins Pit, Northbloom Field Tunnel and Hiller Tunnel. California State University, Chico. Summer 2013.
Abstract
Malakoff Diggins, a historic hydraulic mine, has the potential to degrade habitat in the Humbug Creek and South Yuba River watershed with discharges of sediment, copper, mercury, nickel and zinc. Subsurface waters in three areas of Malakoff Diggins, (1) North Bloomfield Tunnel, including eight airshafts, six contained standing water, (2) Hiller Tunnel, and (3) borings in the Pit near Hiller Tunnel, were studied to identify potential sources of metals. Water chemistry (pH, electrical conductivity, total metals and common ions) similarities and physical characteristics (water level) between mine features were used to determine the connections between mine features and subsurface water flow. The metal concentrations were variable in areas studied at Malakoff Diggins. All portals and shafts of the North Bloomfield Tunnel were at least partially blocked, however the downstream portal of the tunnel and Shaft 5, had continuous surface water discharge to Humbug Creek. The degree to which the standing water between the shafts are connected, through fractured rock or otherwise, was difficult to determine, however some shafts, specifically Shaft 5 (had the highest metal concentrations) and 6, had similar water chemistries. Two borings of four shallow groundwater borings in the Pit, P-1 and P-2, had similar water chemistry. The borings in the Pit had higher concentrations of metals than the surface waters in the Pit and Hiller Tunnel. The concentrations of metals in the waters at Malakoff Diggins are likely related to concentrations of suspended sediment and represent an ongoing source of heavy metals to surface waters.
Student Bio
David graduated from UC Santa Cruz 2007 with a Chemistry B.S. He then when to work for Environmental Testing Labs, and mainly tested for metals and common ions, in a variety of media ranging from water and soil to Chinese Herbal Medicines. David went back to school in 2011 at CSU Chico and graduated in 2013 with an M.S. in Environmental Science. At CSU Chico David worked under Dr. Carrie Monohan, and studied surface and subsurface water contamination and connectivity in man made features such as pits, adits and tunnels at Malakoff Diggins. David is currently in the Environmental Science PhD program at Oregon State University, and his dissertation project is on vadose zone nitrogen transport and stakeholder outreach and engagement in La Pine OR, in relation to the controversial issue of nitrate contamination in well water in the La Pine Area.
