Bonnanza Mine Planning and Reclamation

Wenck was retained by Bonnanza Mining, Inc. to assist with the design and construction of a mining hydrologic control and reclamation plan for their placer gold mine in northeastern Oregon. The mine site is adjacent to the Eagle Cap Wilderness Area in the Wallowa Mountains near Halfway, Oregon. The area is an environmentally-sensitive district and public concern in the area for environmental controls was foremost in mine and reclamation planning. Both the proposed and active mining included open pit mining of a glacio-fluvial placer deposit. Although their principal responsibility was environmental permitting, Wenck participated in the placer exploration effort including reflection seismometry, exploration test pits and sampling, and the review of the environments of heavy mineral deposition and enrichment on the proximal portion of an alluvial fan.

Bonnanza’s mining effort took place within the Pine Creek Valley. Local environmental opposition was concerned with potential impacts to critical wetland habitat. Local concerns included disturbance to the area through increased sediment discharge, adverse impacts to the geomorphic stability of the river, impact to seasonal water discharges, impact to riparian and paludal habitat, and impacts to wildlife usage of the area.

Wenck prepared the mining and reclamation plans, assisted with geological exploration, prepared sediment pond and diversion ditch designs, and prepared and coordinated permits for National Pollutant Discharge Elimination System. Our mine plan addressed material handling issues, highwall design and benching dewatering, and material processing. Water treatment ponds were a critical element in this environmentally sensitive area.

The permitting efforts included the Environmental Protection Agency, US Fish and Wildlife Service, Oregon Department of Fish and Wildlife, State of Oregon Department of Environmental Quality (Mine Water Control), and Oregon Department of Geology and Mineral Industries (Mine and Reclamation Plan).

Major Project Features:

  • Hydrologic Control Plan
  • Mine Plan
  • Reclamation Plan
  • Environmental Permitting
  • Placer Exploration
  • Ore Geochemistry
  • Expert Witness Testimony
  • US Army Corps of Engineers 404 Permit
  • Hydrologic Analyses
  • Hydraulic Structures Design

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