The pilot stated that he was landing his tailwheel-equipped airplane on a gravel surfaced runway that had recently been graded on both sides, with excess dirt and gravel being deposited in the center of the runway. Upon touchdown the airplane veered sharply to the left, and the right wing impacted the runway's surface. The airplane continued to the left, exited the runway, and the right main tire gripped the paved surface of the adjacent runway causing the airplane to snap back to the right. The airplane sustained substantial damage to the right wing and right aileron. The pilot stated that there were no preaccident mechanical anomalies that would have precluded normal operation.