The pilot reported that he executed the ILS approach to runway 35. The runway was 6,499 feet long and 150 feet wide. He said he descended to about 550 feet above the ground on his approach and saw the runway lights. He stated that during the landing roll, he lost sight of the runway lights due to fog. According to the FAA, it was a dark night with low level fog and haze. Most of the runway had been cleared, but snow remained near the edges. The left side was covered with snow from about 6 to 14 feet from the left edge. The airplane encountered snow on the left side, where snow on and adjacent to the runway was about 12 feet wide. Approaching the intersection with runway 5/23, there was a snowbank on the left edge that obscured the runway lights. At the intersection, the snowbank rose to about 6 feet tall and extended about 12 feet onto the runway 35. The left nacelle struck the snowbank, which spun the aircraft and sheared off the landing gear.