Exhibit 10.15 Schedule of Management Stability Agreements Employee Date of Agreement Keith D. Booke August 1, 1997 Jay D. Browning August 1, 1997 Michael S. Ciskowski August 1, 1997 John D. Gibbons August 1, 1997 James A. Greenwood August 1, 1997 Gregory C. King August 1, 1997 John H. Krueger August 1, 1997 William N. Latham August 1, 1997 Robert R. Taylor August 1, 1997 T. Wyatt Stripling August 1, 1997