Carta Exploration Ltd

Importance of This Case Study
This Case Study outlines some of the uses of air photo interpretation during the feasibility stage of mining projects or other large capital projects.

Feasibility and Permitting
On the path to project feasibility, air photos are useful for geotechnical design, baseline studies, environmental impact assessments, and monitoring commitments.

Location
The Morrison Property is located in the Babine Porphyry Copper Belt in northern central British Columbia.

Background
Pacific Booker Minerals Inc. is a publicly traded company with the mineral rights to the Morrison deposit. The company proposes a 30,000 tonnes per day copper/gold/molybdenum mine consisitng an open pit, plant site, ore stockpiles, waste rock pile, tailings storage facility, overburden stockpiles and associated pipelines and access roads. The Morrison Copper/Gold Project has ready access to infrastructure including highways, shipping routes and power transmission lines.

Objective
To support the mine development plan, the company must complete a number of studies including geotechnical engineering design, engineering feasibility, the environmental assessment and numerous permit applications.

Custom Aerial Survey
For companies with large capital projects such as mines, one of the first items to be commissioned is a custom aerial survey to produce current, high-resolution, large-scale air photo coverage of the property and environs. As part of this work, benchmarks placed throughout the study area allow the creation of detailed topography with 1 to 2 m contour elevation, which far exceeds the detail available in maps from government surveys. The aerial survey produces a complete set of overlapping air photos for stereoscopic coverage of the site. From the air photos, an orthophoto map is made that serves as an anchor layer in the project Geographic Information System (GIS).

Detailed topography derived from the custom aerial survey is used in the feasibility stage to calculate the volume and extent of planned cuts, excavations, fills and aggregate resources, all of which become inputs into the Capital Cost Estimate for feasibility-level financial analysis.

Detailed topography derived from the custom aerial survey can also be used in the pre-construction and construction phases of mine development.

Air Photo Interpretation for Engineering and Feasibility Studies
Air photo interpretation is an important part of studies supporting the geotechnical design and feasibility of a mine. Air photo interpretation is used to:

• Map the location and extent of engineering soils, including sand, gravel, silt and clay deposits;
• Characterize the stratigraphic and geologic history of the area, which is important to forecast problematic rock and soil conditions, for example bedrock faults, location of permeable fluvial deposits in the tailings dam footprint, or the location of glacial lake silt deposits that are susceptible to piping erosion;
• Examine stream crossings, watersheds and areas of stream erosion;
• Guide the planning and execution of field programs involving drilling, sampling, trenching, test-pitting and the installation of instrumentation such a piezometers, thermistors, slope deformation indicators and meteorological stations;
• Identify recent or inactive landslides, areas of erosion and other geologic hazards in the study area;
• Generate an overburden isopach map showing the thickness and extent of engineering soils throughout the mine area. The overburden isopach map is used to calculate the bedrock surface in the open pit area, the volume of overburden requiring stripping during mining, and the required size of the overburden soil stockpile for use during reclamation;
• Calculate the available on-site borrow sources of sand and gravel for road building and construction, and clay-rich deposits such as glacial till used for the impermeable liner in the tailings dam;
• Plan routes for roads, pipelines and power transmission lines.

Air Photo Interpretation for Baseline Studies
The application process for obtaining the environmental assessment certificate and permits is long and rigorous requiring the initiation of baseline studies one to a few years before the expected initiation of mine construction.

Baseline studies document the physical, biologic, social, aboriginal and economic status of the area before the project begins. Baseline studies establish monitoring procedures to assess the potential impacts of the project on valued physical, biologic and socioeconomic components. In this context, air photo interpretation is used to:

• Establish the Environmental Footprint, which is the extent of the affected area of the project and is usually larger than the project area;
• Complete Ecosystem Mapping to determine soil, stream, lake and ecosystem components and habitats;
• Assess sites for Archaeological Potential and plan archaeological ground investigations;
• Construct a key layer in the project GIS used to organize and archive all baseline information, and which serves as an important project database throughout the life of the mine.