On February 27, 1998, about 1215 eastern standard time, a Cessna 320F, N6189Q, was substantially damaged while landing at the Lincoln Regional Airport (LRG), Lincoln, Maine. The certificated commercial pilot was not injured. An instrument flight rules flight plan had been filed for the flight that departed Portland, Maine, about 1130. Visual meteorological conditions prevailed for the personal flight conducted under 14 CFR Part 91. In a telephone interview, the pilot stated that during the final approach to runway 35, about 10 feet above the ground, the airplane's left main landing gear contacted a snow/ice bank, which caused the airplane to swerve to the left. The pilot continued the landing, and added power to stabilize the airplane and to realigned it with the runway center line. During touchdown he noticed the airplane's left wing was dropping lower then normal. As the airplane slowed, it began to drift left despite the use of full right rudder and brake. The airplane then departed the left side of the runway, and it's left wing struck another snow bank. A pilot/witness on the ground stated: "...Snow banks were 1 to 4 feet, and largely clear of all paved [runway] surfaces....The aircraft speed and alignment seemed normal for the terrain and conditions. I could not observe from my vantage point when the left main gear struck the dry snow bank at the threshold of [runway] 35, nor the flare before final touchdown. I did observe the rapid left turn at mid field after the aircraft had veered off the left side of the runway...." According to a Federal Aviation Administration Inspector, the snowbank the airplane struck was 2.5 feet high and was located 21 feet prior to the runway 35 threshold. The pilot did not report any mechanical malfunctions with the airplane.