The county solid waste facility capacity component shall include, but is not limitied to, a projection of the amount of disposal capacity which will be needed to accommodate the solid waste generated within the unincorporated area of the county preparing the element for a 15-year period, reduced by all of the following:
(a) Implementation of source reduction, recycling, and composting programs required by this part or through implementation of other waste diversion programs.
(b) Any permitted disposal or transformation capacity which will be available during the 15-year planning period.
(c) All disposal or transformation capacity which has been secured through an agreement with another city, county, or through an agreement with a solid waste enterprise.