(a) The Siting Element shall demonstrate that there is a countywide or regionwide minimum of 15 years of combined permitted disposal capacity through existing or planned solid waste disposal and transformation facilities or through additional strategies.

(b) The Siting Element shall describe and identify the areas, numbers and types of new solid waste disposal and transformation facilities, as well as the expansion of existing solid waste disposal and transformation facilities necessary to provide a minimum of 15 years of combined permitted disposal capacity.

(c) If the requirements of subdivision (b) of this section cannot be demonstrated, then strategies shall be discussed for the transformation, disposal, or diversion of excess waste.

(d) The Siting Element shall include the items identified in sections 18755.1 through 18756.7 of this article.

(e) A “Siting Element” may be prepared by a regional agency when the regional agency is composed of two or more counties and all incorporated cities of those counties.

(f) For the purposes of this article, “countywide” shall be defined as including the incorporated cities within the county and the unincorporated areas of the county. For purposes of this article, “county” shall include the Board of Supervisors as the legislative and executive body of county government, and any designated agency responsible for solid waste management.

(g) For the purposes of this article, “regionwide” shall be defined as including the member agencies of the regional agency. For the purposes of this article, a “regional agency” shall be the governing entity created by a voluntary agreement between cities and counties for the purpose of complying with Part 2 of Division 30 of the Public Resources Code. A city or county which is a party to such an agreement shall be considered a “member agency” of the regional agency. A regional agency may authorize one district, as defined in subdivision (a) of Section 41821.2 of the Public Resources Code, to be included as a member of the regional agency.