The use of snow fences to reduce ice-wedge cracking, Garry Island, Northwest Territories

1978 ◽  
Author(s):  
J R Mackay
Keyword(s):  
Northwest Territories ◽  
Ice Wedge ◽  
Snow Fences

Ice-Wedge Cracks, Garry Island, Northwest Territories

1974 ◽  
Vol 11 (10) ◽  
pp. 1366-1383 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Northwest Territories ◽  
Snow Depth ◽  
Ground Surface ◽  
Ice Wedge

Observations made on winter ice-wedge cracks at Garry Island, N.W.T., for the 1967–73 period show that cracking tends to occur between mid-January and mid-March. On the average, nearly 40% of the ice wedges crack in any given year. The crack frequency varies inversely with snow depth. Medium sized ice wedges, about 1 m wide, crack more often than smaller or larger wedges, ice wedges crack preferentially near the center and often year after year at nearly the same place. The cracks average about 1 cm wide at the surface and taper downwards to depths which may exceed 5 m. The cracks partially close in spring before a new ice veinlet forms in them. Evidence provided by multiple wedges suggests that cracking may be initiated at times within the wedge rather than at the ground surface, and thus the cracks propagate both upwards and downwards.

The Closing of Ice-wedge Cracks in Permafrost, Garry Island, Northwest Territories

1975 ◽  
Vol 12 (9) ◽  
pp. 1668-1674 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Northwest Territories ◽  
Crack Width ◽  
Crack Spacing ◽  
Elastic Model ◽  
Thermal Contraction ◽  
Underground Cables ◽  
Ice Wedge ◽  
The Mean

The closing of thermal contraction (ice-wedge) cracks at Garry Island, N.W.T., 150 km northwest of Inuvik, N.W.T., has been measured by means of gauge probes inserted into the cracks and by precise taping between bench marks across ice-wedge troughs. The results show that a simple elastic model fails to explain the time of cracking, the depth of cracking, the crack spacing, and the time of closing. The mean annual ice vein increment, at Garry Island, is probably less than 20% of the mean winter crack width. Thermal contraction cracks are of potential engineering interest, because they may affect underground cables, reservoirs, and other man-made structures.

Pleistocene ice and sand wedges, Hooper Island, Northwest Territories

1983 ◽  
Vol 20 (7) ◽  
pp. 1087-1097 ◽  
Author(s):  
J. Ross Mackay ◽  
J. V. Matthews Jr.
Keyword(s):  
Oxygen Isotope ◽  
Northwest Territories ◽  
Environmental Conditions ◽  
Isotope Ratios ◽  
Winter Ground ◽  
Vertical Extent ◽  
Oxygen Isotope Ratios ◽  
Ice Wedge ◽  
Collapse Structures

Buried ice and sand wedges have been found in glacially deformed sediments that can be no younger than the early Wisconsinan. The environmental conditions at the time of ice-wedge cracking have been inferred from the number of elementary ice veinlets, the vertical extent of the wedges, collapse structures, oxygen isotope ratios, and macrofossils of plants and insects. The winter ground and summer climates were probably as warm or warmer than the present. The preservation of the ice in the ice wedges shows that permafrost has been present at Hooper Island since at least the early Wisconsinan.

Yellowknife, Northwest Territories

Blue Jay ◽  
1980 ◽  
Vol 38 (1) ◽  
Author(s):  
Saskatchewan Natural History Society
Keyword(s):  
Northwest Territories

Continuing the Development of Municipal Effluent Guidelines for the Northwest Territories

1986 ◽  
Vol 18 (2) ◽  
pp. 179-184
Author(s):  
R. J. Kent
Keyword(s):  
Northwest Territories ◽  
Removal Efficiency ◽  
Municipal Wastewater ◽  
Coliform Bacteria ◽  
Flow Ratio ◽  
Dilution Ratio ◽  
Effluent Quality ◽  
Municipal Effluent

The background to and the rationale for the Guidelines for Municipal Type Wastewater Discharges in the Northwest Territories is discussed. Particu1ar attention is given to the development of Table 2.1, Effluent Quality of Municipal Wastewater Discharges, which was based upon expected lagoon performance. Also included is a discussion of the flow ratio and dilution ratio concepts. The viability of these concepts was assessed against the available data. It appears that the guidelines misjudged both the number of coliform bacteria in northern raw sewage and the removal efficiency for these organisms in lagoons. It appears unlikely that lagoons can consistently meet the guideline requirements. More information and research is necessary before a complete assessment can be performed.

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