GLA’s industry-recognized experts provide mine consulting services for worldwide projects in a variety of climates and terrains from high rainfall, tropical sites to arid, mountainous areas.

From initial feasibility studies, permitting, and design through closure, our team’s mining services include:

  • Construction management and infrastructure support (CQA)
  • Data management
  • Enhanced metals recovery
  • Environmental services/risk assessments
  • Facility closure, reclamation, and remediation
  • Feasibility studies
  • Geotechnical, geological, and civil engineering
  • Heap leach pads/ponds and tailings dams
  • Hydrology, hydrogeology, and water supply management
  • Planning and permitting

GLA’s experts have demonstrated sound engineering to resolve geotechnical conditions and environmental restrictions facing many of the mines around the world. GLA has provided engineering services for mines in the following countries:

  • Argentina
  • Brazil
  • Canada
  • Chile
  • Colombia
  • Ghana
  • Guatemala
  • Guinea
  • Indonesia
  • Mexico
  • Peru
  • Philippines
  • Turkey
  • United States
  • West Africa

Construction Management and Infrastructure Support (CQA)

GLA provides a complete range of project-specific, on-site construction observation and testing services to ensure that each project is built to design specifications. We assist our clients during bidding and construction and ensure that projects are adequately staffed and supported throughout their design, bidding and contracting, construction, and regulatory approval phases.

Our professionals are experienced in providing:

  • Engineer’s cost estimate
  • Value engineering
  • Bid package preparation/bid administration
  • CQA plans and preparation
  • Construction quality control/assurance (QA/QC)
  • Electronic leak location surveys
  • Geotechnical laboratory support

Construction QA/QC materials expertise includes:

  • Soil and rock
  • Geosynthetic clay liner (GCL)
  • High-density polyethylene (HDPE)
  • Linear low-density polyethylene (LLDPE)
  • Polyvinyl chloride (PVC)
  • Chlorosulfonated polyethylene (CSPE/Hypalon)
  • Low hydraulic conductivity soil liner
  • Liner cover material property verification
  • Liner cover placement observation and documentation

Mine Infrastructure Design and Support

GLA is highly experienced in providing daily observation, testing, and documentation for mining projects. Upon completion of construction, we provide documentation, certifications, and as-built reporting for regulatory approval. We routinely provide these services for mine infrastructure facilities, including:

  • Waste rock facilities
  • Diversion channels
  • Haul and access roads
  • Water supply structures
  • Headframes
  • Mills and crushers
  • Retaining walls
  • Trucks shops and admin buildings

Soil Testing and Research

GLA has specialized geotechnical laboratory testing capabilities to assist in facility design through construction of the heap leach facility. Specific laboratory testing capabilities include:

  • Load versus hydraulic conductivity for determining changes in hydraulic conductivity of ore and solution collection material under overlying heap loads
    • 8-inch and 12-inch diameter fixed wall molds
    • Load capability exceeding the equivalent of 300 feet of overlying ore
  • Ore durability
  • Agglomeration ore durability
  • Soil water characteristics curves
  • Grain size distribution with hydrometer
  • Atterberg limits
  • Consolidation
  • In situ moisture content and dry density
  • Laboratory compaction
    • Maximum dry density/optimum moisture content
  • Flexible wall hydraulic conductivity
  • Direct shear testing
  • Triaxial shear testing
  • Liner interface shear
    • Residual and peak strength
heap leach injection services; enhanced metal recovery (EMR) for Gold, Silver and Copper Mines

Enhanced Metal Recovery

Heap leach injection services, also known as Enhanced Metal Recovery (EMR), is a process that GLA uses to help mining clients access previously unrecoverable gold, silver, and copper, that has added millions of dollars to their bottom lines by recovering thousands of additional ounces of ore.

Key Benefits:

  • Tailored injection plan and solution management to meet client- and site-specific needs
  • Permitting and financing assistance available
  • Short-term return on investment, providing cash flow for costly operating expenses, mine reclamation, and closure costs
  • Wells can be reinjected to further enhance recovery
  • Implementation by a highly experienced team of engineers and field professionals
  • Continuous interface between client management and technical team to ensures client involvement

Read more about this heap leach injection process and GLA’s Enhanced Metal Recovery expertise.

Environmental Services / Risk Assessments

Environmental scientists at GLA regularly work with federal agencies and subcontractors to prepare and manage mine environmental assessments. Our environmental scientists have experience in performing:

  • Seepage and contaminant studies
  • Mine closure, decommissioning, and reclamation
  • Post-closure monitoring
  • Stormwater management plan development
  • Runon and runoff controls
  • Channel energy dissipation
  • Flow structure (weir design)
  • Runoff channels and sediment pond design
  • Air permits and reporting
  • Groundwater monitoring
  • Compliance assessment of facility and monitoring programs
  • Expert witness and litigation support
  • Risk assessments
  • Environmental management plans

Facility Closure, Reclamation, and Remediation

GLA has written numerous tentative plans for permanent closure, final permanent closure plans, and final closure reports. Our team has helped mining facilities optimize closure bonding cost estimates. We work with clients to gain an understanding of reclamation intentions and develop successful stabilization and revegetation programs. We have experience preparing all of the documents necessary to close mining operations pursuant to current regulations. We can assist with closure and post-closure design and monitoring, including determining goals and detailed methodology of activities necessary to achieve a level of stabilization of all known and potential contaminants.

GLA develops reclamation programs consistent with intended post-closure land use. Our cover design methods include evaporation cells, evapotranspirative (ET) covers, and resistive barrier covers. To develop successful revegetation programs, we provide germination and plant uptake studies that assess the ability for native plant species to establish in the proposed growth medium (e.g., ore, waste rock, or alluvium) in conjunction with reclamation drainage design and erosion control.

Closure and reclamation services include:

  • Closure plan preparation
  • Closure bond cost estimates
  • Design, implementation, and monitoring of closure systems
  • Third-party reclamation oversight
  • Reclamation drainage design
    • Heap leach pad (HLP) draindown
      • Recirculation, active evaporation, and passive evaporation in designed evaporation cells (E-Cell)
    • Erosion control
    • Riprap design
    • Wattles
    • Gabions
  • Evaluation of chemical data for stabilization of all applicable mine components for closure
  • Detailed description of all proposed monitoring that will be conducted to demonstrate how the closure goals are being met, including vegetation and erosion control, and monitoring well water quality samples
  • Development of post-closure period reclamation activities, such as seeding, ripping, and fertilizing; or future activities, such as plugging monitoring wells, removing fencing, or access road removal and reclamation

Evapotranspirative (ET) Soil Cover Closure Caps

GLA’s ET Soil cover closure cap services include:

  • Evaporation cell (E-Cell) design, ET cover design, and resistive barrier cover design
    • Climate data set development
    • UNSAT-H modeling
    • Soil testing to determine soil water characteristic curve (SWCC)
  • Cover soil design using measured, site-specific hydrogeologic parameters

Facility Closure Design/Site Stabilization

GLA has written numerous tentative plans for permanent closure, final permanent closure plans, and final closure reports. We can assist with closure and post-closure design and monitoring, including determining goals and detailed methodology of activities necessary to achieve a level of stabilization of all known and potential contaminants.

We are knowledgeable of closure and stabilization requirements pertaining to process and non-process components (e.g., solid and liquid process mine wastes), heap leach pads, tailings impoundments, pits, waste rock storage facilities, ore stockpiles, and other associated components that could potentially lead to degradation of waters of the state.

Closure components and major elements of site stabilization may include reshaping and regrading, covering, placing of growth medium, and applying soil amendments. We perform germination studies to assess the ability for native plant species to establish in the proposed growth medium (e.g., ore, waste rock, or alluvium), develop revegetation plans, and study plant uptake.

GLA’s facility closure design services include:

  • Reshaping and regrading
  • Covers and soil amendments
  • Native plant studies
  • Revegetation plans
  • Growth medium recommendations using ore, waste rock, or alluvium

Site Visualization and Analysis

Our illustrations, 3D models, and animations range from conceptual renderings to data-driven visual interpretations. Using geographic information system (GIS) and 3D geological modeling software, we create coherent and comprehensive interpretations of surface and subsurface conditions, including visualizations of ore bodies, contaminant plumes, water levels, wells, borings, and block models.

ESRI’s ArcMap and ArcView software and its various extensions (e.g., 3D Analyst, Spatial Analyst, Image Analysis, and Tracking Analyst) are used for visualization and analysis of project data. For one mining client, we developed a custom coordinate transformation package to plug into the mine’s GIS, which allows efficient conversion between local mine coordinates and any other real-world coordinate system.

Feasibility Studies

Feasibility studies are required throughout the pre-production stage of every mining project. Through analysis, assessment, and cost evaluation, we develop comprehensive solutions, including development of alternatives throughout the Preliminary Economic Assessment (PEA), Pre-Feasibility Study (PFS), and Feasibility Study (FS) feasibility stages. GLA will give you the highest confidence in the underlying value of your mining project. GLA is able to work directly with the mining client, or as technical subconsultants through many Process Engineering and engineering, procurement, and construction management (EPCM) companies.

Over the past 25 years, GLA has worked in many of the world’s mining districts and have the experience and expertise to help with conceptual studies in varied environmental, geologic, and economic climates.

  • Argentina
  • Brazil
  • Canada
  • Chile
  • Colombia
  • Ghana
  • Guatemala
  • Guinea
  • Indonesia
  • Mexico
  • Peru
  • Philippines
  • Turkey
  • US
  • West Africa

From early conceptual PEA level studies, through alternative based PFS, and more detailed FS efforts, GLA provides cost-effective alternative designs for the following mine process and infrastructure projects:

  • 3rd party review of prior published PEA, PFS, and FS studies
  • Permitting plans or country agency liaison for water resources, exploration plan, evaluation for mining needs, recommendations
  • Surface water management plans
  • Tailings and heap leach site selections, volumetrics, and cost comparisons
  • Geotechnical and civil engineering considerations and recommendations
  • Mine infrastructure, waste dumps, haul roads, and conceptual studies
  • Cost evaluations for construction depending on level of study
  • Plan for permitting and development success

Heap Leach Pads/Ponds and Tailings Dams

GLA’s geotechnical engineers have prepared designs, performed life of mine studies, and conducted due diligence and third-party reviews for mine heap leach pads and ponds and tailings dams in some of the most highly seismic regions of the world as well as in areas with complex soil conditions. Our experience spans a variety of heap leach pad designs, including:

  • Valley fill facilities
  • Typical sloping pads in steep topography incorporating buttress fills for stability
  • Re-usable pads
  • Asphalt cement lined pads
  • Associated process solution ponds, storm ponds, and solution conveyance systems

Heap Leach Engineering

GLA provides geologic investigations, geohydrologic investigations, construction material source identification, seismic hazard studies, geo-hazards studies, preliminary and final design, permitting assistance, report preparation, development to technical specifications and CQA. Related services include:

  • Pre-feasibility/feasibility studies
  • Site selection
  • Geotechnical stability, seismic risk analysis, and liquefaction assessment
  • Earthworks and grading optimization
  • Borrow source investigations to identify locally available construction materials
  • Field engineering during construction
  • Hydrology and Hydraulics including challenging surface water run-on and runoff controls and associated storm containment ponds
  • Cold weather leach operations design and evaluation
  • Permitting and regulatory compliance
  • Regulatory liaison

Pond Design

GLA has experience designing single and double-lined ponds for various heap leaching applications, including:

  • Evaporation ponds
  • Pregnant ponds
  • Barren ponds
  • Emergency storage ponds
  • Stormwater ponds

Tailings Impoundments

GLA provides planning, site assistance, conceptual, feasibility, through detail design for a variety of tailings storage facilities, constructed in difficult terrain, with challenging climatic and environmental conditions. Our engineers are leaders in the development of alternative tailings technologies for both surface and underground storage applications. GLA applies these technologies to a wide range of projects in response to unique challenges presented by climatic, topographic, geochemical, or material properties.

GLA is experienced with evaluating, designing, and optimizing the following types of tailings storage facilities:

  • Precious metals, copper, base metals, coal ash, uranium, aggregate/cement
  • Conventional tailings
  • Dry Stack, dewatered tailings, including conveyor transport systems
  • Thickened tailings
  • Cyclone tailings
  • Sub-aqueous, sub aerial
  • Underground disposal
  • Sand, earth and rock fill dams

Our extensive tailings services include:

  • Feasibility studies, financial analysis, 3rd party design review and recommendations
  • Site selection, permitting and compliance, volumetrics and size optimization
  • Geotechnical foundation drilling, evaluations, recommendations
  • Material testing, rockfill, earthen, sand, technical specs
  • Civil engineering design, seismic analysis, stability instrumentation
  • Water balance, surface hydrology, water management
  • Risk assessment, dam breach assessment
  • CQA, construction management
  • Re-development designs to improve stability, water return, improve capacity, reduce operating costs
  • Decommissioning, closure, reclamation
  • Closure cap design

Geotechnical, Geological, and Civil Engineering

Since the late 1980s, GLA’s professionals have provided geotechnical and earthquake engineering services for a wide range of projects across the United States and overseas. GLA’s geotechnical engineers have designed facilities in some of the most highly seismic regions of the world as well as areas with complex soil conditions.

  • Geologic and geotechnical engineering investigations, drilling, recommendations
  • Development of seismic design criteria,
  • Evaluation of regional and site seismicity,
  • Designs to withstand seismic loading (including dams and appurtenant structures, and foundations for buildings, bridges, and other structures)
  • Seismic deformation analyses,
  • Soil liquefaction analyses, and ground improvement solutions.
  • Life-of-mine studies, due diligence, and third party review.
  • Waste dumps design
  • Rapid Infiltration basin system (RIBS) evaluation, design and construction
  • Surface water management design, ponds, conveyance, collection ditches, weirs, check dams
  • 100-500 year event design analyses

Hydrology, Hydrogeology, and Water Supply Management

Understanding a site’s ground and surface water is an essential component of all mining projects and operations that require a reliable water supply for mineral processing and other mining operations, dewatering and depressurization of mine workings and pit slopes, management of water use to achieve a more neutral water balance, diversion of surface water around mine facilities and control of extreme precipitation events, and design of environmental controls.

Our hydrogeologic and hydrologic services for mining projects and operations include:

Mine water supply

  • groundwater exploration and development
  • characterization and quantification of surface water supplies
  • design of water storage
  • water treatment, distribution systems
  • water use permitting

Mine dewatering and depressurization

  • field investigations and testing,
  • technical and economic analysis of alternatives,
  • system design and performance evaluation

Mine water balances and management

  • entire mine site as well as from individual components
  • heap leach facilities and tailings facilities
  • waste rock storage facilities
  • open pits, and underground workings

Hydrogeologic site investigations

  • Design and installation of wells, drilling oversight
  • aquifer pump and borehole permeability testing,
  • piezometer and well installations
  • water chemistry sampling

Numerical modeling

  • geographic information system (GIS) and Mining Visualization SystemTM tools groundwater flow and solute transport
  • vadose zone flow and solute transport
  • surface water flow and management
  • open pit and underground models
  • RIBS rapid infiltration basin design and construction
  • dam breach analyses for tailings
  • thermodynamic modeling of sulfide and oxide heap leaches under cold weather conditions

Environmental impact assessment support

  • baseline monitoring,
  • geochemical sampling and testing, and
  • quantification of water seepage quantities and quality from mine facilities
  • vadose zone monitoring
  • contaminant transport studies

Geochemical and water chemistry characterization and modeling,

  • determination of acid rock drainage (ARD) potential
  • predictions of seepage water chemistry,
  • pit lake studies,
  • solute fate and transport evaluations, and
  • natural isotope studies

Planning and Permitting

GLA has experience navigating complex regulatory processes related to Water Pollution Control Permits, including minor and major modifications, Engineered Design Changes (EDC), reclamation permits and plan modifications, bonding, Standardized Reclamation Cost Estimator (SRCE), Heap Leach Draindown Estimator (HLDE), Process Fluids Cost Estimator (PFCE), Plans of Operations, baseline study management, environmental assessments, and geochemical evaluations.

We work with regulators to help clients navigate the process for the following permits:

  • Plans of Operation
    • New plans
    • Amendments
  • Water Pollution Control Permits
  • Reclamation Plans and Permits
  • Federal Land Management: US Bureau of Land Management / US Forest service
  • Dam Permits: Division of Water Resources / Dam Safety Divisions
  • Air Permits
  • Stormwater Pollution Prevention Plans
  • Stormwater Permits
  • 404 Permits: Army Corps of Engineers