Mining Reclamation

Stewards of the Earth’s Natural Resources – HGL provides expert planning, design, and restoration services to federal and state regulatory agencies, management organizations, and enterprises engaged in mine site operations and reclamation. As the world’s demand for mineral resources grows, HGL recognizes the increasing importance of developing sustainable solutions that prevent future adverse effects and account for the complex physical, biological, and geochemical conditions that exist at mine sites. HGL and its wholly owned subsidiary, Spectrum Engineering and Environmental, LLC (Spectrum), employ best management practices and use industry-leading modeling tools and technologies to design and implement innovative, cost-effective solutions to the environmental challenges faced at active and abandoned mine sites. HGL’s expertise encompasses the following service areas:

  • Property Ownership/Claim Analysis
  • Groundwater/Surface Water Modeling and Planning
  • Subsidence Investigation and Adit Closure
  • Consumptive Use Permitting
  • Water Management, including Dewatering and Stormwater Capture
  • Hydrology and Hydraulics
  • Field Sampling and Analysis
  • Biological Treatment
  • Human Health and Ecological Risk Assessments
  • Feasibility Studies
  • Remedial Design
  • Remedial/Removal Action
  • Geomorphological Restoration
  • Habitat Restoration
  • Treatment System Design and Operation
  • Design and Construction of Passive Treatment Systems
  • Optimization of Treatment Systems and Water Handling
  • SCADA System Installation and Monitoring
  • Long-Term Operation and Monitoring
  • Ancillary Construction Services Support
  • Expert Testimony and Litigation Support

 

The following three projects demonstrate HGL’s/Spectrum’s expertise at mine sites:

 

Zortman and Landusky Mines, Phillips County, Montana

Since 1999, Spectrum has supported the Montana Department of Environmental Quality in the high-profile CERCLA reclamation of the Zortman and Landusky Mines. The 1,200-acre complex encompasses two open pit gold mines near the crest of the Little Rocky Mountains. The site received national attention in 1999 when the site operator declared bankruptcy and abandoned ongoing cleanup operations, leaving mining waste, cyanide leach pads, and mill sites to contaminate the only drinking water source for the Fort Belknap Indian Reservation. Spectrum’s work has included remedial actions, including sediment dredging; excavation/waste consolidation; reclamation actions; and long-term remedial action/operation and maintenance of four acid rock drainage water treatment plants and associated capture systems.

Project Highlights
Implemented remedy of mine waste consolidation and stabilizations and source control, reducing acid rock drainage, preventing releases, and bringing selenium and nitrate discharges into compliance.
Operated in rugged terrain with challenging geology, including multiple shear zones and surface water drainage features.
Successfully executed a reclamation project at the remote, complex hard rock mine sites under the close scrutiny of multiple stakeholders.
Optimized treatment system to reduce labor costs, and designed and implemented phased change-outs to variable frequency drive pumps, rewired systems, and dropped transformers, thereby cutting energy costs.
Treated 1.4 billion gallons of acid rock drainage.

 

 

Gilt Edge Mine Superfund Site, Lawrence County, South Dakota

HGL, with wholly owned subsidiary Spectrum, is implementing an interim remedial action, including long-term remedial action, and conducting remedial construction at the Gilt Edge Mine Superfund Site, a 360-acre former open pit and cyanide heap-leach gold mine. Mining operations produced acid rock drainage with high metals content, which is treated by a high-density sludge water treatment plant. HGL and Spectrum operate the plant, manage waste sludge, monitor and maintain the facility and grounds, maintain the water balance in multiple capture systems to prevent releases, and conduct remedial construction to support remedy implementation efforts for area surface water and groundwater.

Project Highlights
Implemented an interim remedial action for the operation and maintenance of acid rock drainage treatment system and management of capture ponds and pump backs.
Provided engineering support for and constructed automation upgrades, including a 40-foot communication tower, to allow through a SCADA (supervisory control and data acquisition) system real-time monitoring and on-demand pumping of remote capture systems to prevent releases.
Treated and discharged 180 million gallons of groundwater while operating at 99% on-stream efficiency.
Completed system automation upgrades that eliminated the need for a night shift, reducing labor costs.

 

Cherokee County Mine Superfund Site, Cherokee County, Kansas

Former mining operations at the Cherokee County Superfund Site in southeast Kansas included both underground and open pit mining. Wastes generated (bull rock, chat, and tailings) contained high concentrations of lead, zinc, and cadmium. HGL completed eight remedial designs that included excavation, consolidation, covering of mine waste, filling and covering of mine-related subsidence pits, and subaqueous disposal in mine shafts. Site operable units included 158 chat and tailings piles, 9 outwash areas, and 11 large subsidence pits spread over more than 28 square miles. HGL designed the removal and consolidation of 9 million cubic yards of mine wastes to support an areawide solution for returning impacted private properties to beneficial reuse as pasture revegetated with native plant species.

Project Highlights
Prepared planning documents, collected field data, modeled hydrologic and hydraulic conditions, and conducted an “outliers” investigation to identify previously unidentified waste.
Obtained access agreements from over 70 landowners, provided estimations on volumes of economically viable chat, and used aerial survey techniques to develop topographic data for use in the design.
Through value engineering modified haul routes, saving 55,000 gallons of fuel, and reduced the carbon footprint of remedial actions by nearly 50%

 

 

 

Point of Contact

Bob Overfelt
Vice President
E-mail: roverfelt@hgl.com