On February 7, 2004, at 1252 central standard time, a Cessna 172N, N738EJ, piloted by a student pilot and certified flight instructor, was substantially damaged during landing at the St. Louis Downtown Airport, Cahokia, Illinois. The airplane's right main landing gear struck an approximately 1-1/2 foot high snowbank at the approach end of runway 30L (6997 feet by 100 feet, asphalt), and the airplane subsequently went off of the right side of the runway. The 14 CFR Part 91 instructional flight was operating in visual meteorological conditions without a flight plan. The student pilot and flight instructor were not injured. The local flight originated about 1230. In a written report, the instructor pilot stated that the student pilot was attempting to land as close to the runway threshold as possible to avoid possible wake turbulence from a jet that had previously taken off. She stated that during the landing flare, the airplane struck the snowbank and veered right into the grass adjacent to the runway. The report listed no mechanical problems with the airplane. The student pilot reported that he planned to land close to the runway threshold to avoid possible wake turbulence from a jet that had previously taken off. He stated that as they approached the runway, he heard a "thud" and the airplane shook. He stated that the airplane subsequently skidded off of the runway to the right.