On June 16, 2001, at 1700 central daylight time, a Schleicher ASW-20, N76SP, sustained substantial damage during landing on runway 18 (2,660 feet by 200 feet, dry/turf) at Highland-Winet Airport, Highland, Illinois. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 and was not on a flight plan. The pilot, the sole occupant, did not sustain any injuries. The local flight departed the Highland-Winet Airport at 1615 and was landing at the time of the accident. According to the pilot, he unintentionally performed a no-spoiler approach to runway 18, and crossed the threshold at a higher than normal airspeed. The pilot reported that he performed an intentional ground loop to avoid overrunning the end of the runway. While the pilot was performing the ground loop the right wing tip impacted the terrain causing substantial damage to the glider. According to the pilot's written statement, he believes that he may have mistaken the landing gear lever for the spoiler deploying lever. The pilot reported that, "I firmly believe if I would have used a landing check list this situation probably would not have happened."