California Code, Streets and Highways Code - SHC § 9070

In the event that the holders of one or more of the outstanding bonds do not enter any contract to refund the same, nevertheless, if the holders of 75 percent or more of the outstanding bonds do contract for the refunding of the bonds owned or held by them the city shall have authority to refund all of the outstanding bonds of said issue under the provisions of this division, but in such event prior to recording the reassessment levied under this division sufficient money to adequately provide for the retirement or payment of the bonds of the nonconsenting holders must be provided and set aside in the proper fund for that purpose.