Tamerlane will utilize ground freezing to create a freeze perimeter to control groundwater for the Pine Point Project (PPP). Artificial ground freezing is an effective method of stabilizing wet, unconsolidated ground and controlling groundwater inflows. The original technology was developed by F.H. Poetsch in 1883 and has been used in mining and underground construction for over 100 years. Freezing was utilized at the historic Pine Point Mine in 1985 to develop a ventilation shaft. The successful earlier application of freezing in the Pine Point rock strata provides confidence that a similar technique can be successfully employed at the PPP’s R190 site.
A typical ground freezing system consists of a series of freeze pipes that are installed around the perimeter of the proposed excavation and extend into the subsurface strata. Within each of the freeze pipes a larger diameter feed pipe is installed that allows the downward circulation of the cooling medium which then flows back to the surface through the annulus of the smaller pipe.
A water-based calcium chloride solution (brine) is chilled by a series of electrically-powered refrigeration plants. A cylindrical column of soil and ground freeze around each pipe as the brine circulates through the closed-loop pipe system. The size of the frozen soil columns increase with time and form an extremely strong, virtually watertight and impermeable barrier.
Tamerlane has retained Thyssen Mining Construction of Canada (TMCC) to conduct engineering and design of the freeze perimeter for the Pine Point Project.
Freeze Perimeter Advantages
- Environmentally noninvasive
- Twice as strong as concrete
- Creates an impervious layer
- Works in all types of soil and groundwater conditions
- Controls water flow
- Eliminates the need to discharge massive volumes of water on the surface
- Less affected by power outages than dewatering
- Lower operating costs than dewatering or grouting
- Can be completely removed after construction, if needed