The pilot of the amphibious, float-equipped airplane reported that, two days before a repositioning flight, he inspected the destination airport. He had planned to land on an alternate grass landing area, adjacent to an asphalt runway, and stop prior to a gravel driveway. He further reported that he noticed in the airport facility directory that the intended landing area was closed due to soft, wet conditions. The pilot reported that, during landing, he was "high and fast". He further reported that he landed "too far along to stop before the gravel drive". The airplane encountered the gravel driveway, bounced, and landed hard, resulting in a nose over. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The airport facility directory for the accident airport, in part stated: "[Alternate Grass Landing Area (AGLA)]: AGLA clsd 1 NOV-1 June. Gnd soft when wet. [Daylight] hrs only. Use of AGLA prohibited when Rwy 04-22 in use." It further stated: "Pilots use at own risk."