The department is authorized to review and approve grants and loans from the federal government and other sources to counties, cities, towns, municipalities, or any combination thereof, to assist them in designing, acquiring, constructing, altering, or operating solid waste processing facilities and disposal facilities or sites. The department is authorized further to accept and consider only those applications for grants from counties, cities, towns and municipalities which have officially adopted a plan for a solid waste disposal system or which are included in an officially adopted plan for a solid waste disposal system which covers two (2) or more such jurisdictions. The department is authorized to approve or disapprove such plans in accordance with the purposes of this part.