EXHIBIT 4.17(b) Supplemental Pass Through Trust Agreement B between Mirant Mid-Atlantic, LLC and State Street Bank and Trust Company of Connecticut, National Association, as Pass Through Trustee, dated June 29, 2001 Supplemental Pass Through Trust Agreement C between Mirant Mid-Atlantic, LLC and State Street Bank and Trust Company of Connecticut, National Association, as Pass Through Trustee, dated June 29, 2001