Abstract

The Dempster Lateral, a proposed gas pipeline which would extend approximately 850 km from the Tuktoyaktuk Peninsula, N.W.T. to the Klondike Highway, 40 km southeast of Dawson City, Y.T., is assumed to follow the Dempster Highway. It would connect with a main pipeline along the Alaska Highway either at Tetlin Junction in southeastern Alaska or at Whitehorse, in southern Yukon Territory.

Between Tuktoyaktuk and the Richardson Mountains, a distance of about 140 km, the pipeline would cross essentially flat-lying Upper Devonian, Lower and Upper Cretaceous and lower Tertiary shales and sandstones of the northern Interior Plains. From the Richardson Mountains to the Tintina Trench where it terminates at the Klondike Highway, the pipeline would cross a large segment of the Cordilleran Orogen. There, clastics, carbonates and igneous intrusions, collectively ranging in age from Pre-cambrian to Mesozoic, are folded and faulted along generally north- and east-trending lines so that the pipeline would parallel these structures in some places and intersect them in others.

Important considerations for such a route include enhancement of hydrocarbon exploration in known or prospective oil and gas fields, the earthquake hazard and the risk of interfering with the migration pattern of the Porcupine caribou herd. The route of the Dempster Lateral lies entirely within Zone 3 of the Seismic Zoning Map for Canada so that there may be a significant risk to whatever structures are built along it. Moreover, increased traffic along the Dempster Highway, in addition to the construction and presence of a pipeline could reduce substantially the winter range of the caribou. A major detour down the east flank of the Richardson Mountains and southwest across the Wernecke Mountains may have to be considered.