EXHIBIT 3.1

                            CERTIFICATE OF FORMATION

                                       OF

                                     GPP LLC

                      A DELAWARE LIMITED LIABILITY COMPANY

         The undersigned, an authorized natural person, for the purpose of
forming a limited liability company under the provisions and subject to the
requirements of the State of Delaware (particularly Chapter 18, Title 6 of the
Delaware Code and the acts amendatory thereof and supplemental thereto, and
known, identified, and referred to as the "DELAWARE LIMITED LIABILITY COMPANY
ACT"), hereby certifies that:

         FIRST: The name of the limited liability company (hereinafter called
the "LIMITED LIABILITY COMPANY") is GPP LLC.

         SECOND: The address of the registered office and the name and the
address of the registered agent of the limited liability company required to be
maintained by Section 18-104 of the Delaware Limited Liability Company Act are
Corporation Trust Company, 1209 Orange Street, Wilmington, DE 19801.

Executed on: August 2, 2002

                                          /s/ Derek O. Wallen
                                  -----------------------------------------
                                  Derek O. Wallen, Authorized Person