Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region

étiquettes: physical sciences, contaminants, permafrost, hydrology, waste sump, waste disposal

Objectif(s): Abandoned drilling mud sumps in the Mackenzie Delta area give an opportunity to examine how well permafrost contains industrial wastes. The sumps offer a unique opportunity to determine the effectiveness of permafrost as a containment for waste fluids containing water-soluble salts. Waste disposal practice has tended to treat permafrost as impermeable but appreciable amount of unfrozen water, thawing ice fabric, or climate warming may render this assumption invalid. The objective of this field work is to complete the evaluation of sumps that was begun in 1997. Work at this time showed that potassium chloride, a freezing point depressant often used in muds and a useful tracer, has migrated through the active layer at least several metres beyond the edge of the original pit at both sites studied. Migration into permafrost has also occurred. These are indications that dissolved salts can migrate distances by diffusion alone, because the sumps are located on level terrain. Downhill flow is not a factor. Thawed ice fabric, which constitutes a network of large pores, is probably fundamental in promoting the movement of dissolved constituents through the ground. Processes associated with ice fabric formation, such as concentration of dissolved salts by repeated freeze-thaw cycles, are also probably important in promoting movement and will be included in laboratory simulations in the near future. Field work this year will be devoted to 1) determining the maximum extent of potassium chloride migration from sumps examined in 1997, 2) examine the Mallik L-38 sump constructed in 1972 as one of the oldest sumps in the Delta, 3) examine the sumps in Parsons Lake area where topographic relief has added the potential for salt migration due to groundwater flow.

Description du projet: Field work this year will be devoted to 1) determining the maximum extent of potassium chloride migration from sumps examined in 1997, 2) examine the Mallik L-38 sump constructed in 1972 as one of the oldest sumps in the Delta, 3) examine the sumps in Parsons Lake area where topographic relief has added the potential for salt migration due to groundwater flow. Sumps along Kumak Channel, near the mouth of Harry Channel, and near Parsons Lake will be examined, working from camps nearby. Surveys of ground electrical conductivity will complement similar winter surveys and help to define the extend of salt spread around the sumps. These surveys will also help to locate soil sampling locations. Samples from the thawed active layer will be taken from hand-dug pits. Samples from frozen ground will be taken by means of a frozen ground core barrel mounted on a light earth auger. All samples will be used to determine the salt content of the soil. Sampling sites will be extended further away from sups than in 1997 and to greater depth so that the extent of salt migration can be defined. All samples will be analysed for salt and ice content in Inuvik. Approximately two weeks will be spent at sumps on the Mackenzie Delta and one week at sumps near Parsons Lake.