Authorizing and approving the City to amend the payments due under an Alternative Funding Mechanism for a portion of the unfunded actuarial accrued liability of the City of Philadelphia Retirement System pursuant to the Municipal Pension Plan Funding Standard and Recovery Act, through the execution and delivery of a supplement to a Service Agreement between the City of Philadelphia and the Authority, such amendment of payments to be effected through the issuance of the Authority's bonds to provide funds to purchase outstanding bonds of the Authority previously issued to finance such Alternativ — Open Common Ground