At the opposite end of the pipeline, just north of Valdez, engineers coped with the difficulties posed by Keystone Canyon. The canyon was the only route to Valdez, but it was occupied by the Richardson Highway and the Lowe River; no room was available for the pipeline. The only solution was to avoid the canyon by building the pipeline through the Chugach Mountains and at the rim of the canyon. Winter work was made impossible by the more than of snow that fell in the winter of 1975-1976, and when the snow melted, construction workers had to figure out how to travel up a 60 percent grade, then lay the pipeline on it. A rock-crushing plant was built at the canyon's rim to avoid the need to carry gravel up the steep grade, but problems still persisted. Not even bulldozers could traverse the grade without a team of two helping each up the grade in turn. A bulldozer had to be modified to carry 80-foot (20.4-meter) sections of pipe up the grade, but even then, most of the sections and equipment had to be lifted by helicopter to the canyon rim. Similar techniques had to be used at nearby Thomson Pass, and both sections required the entire 1976 construction season to complete.