A qualified agency proceeding with the planning of solid waste collection and disposal systems and applying for aid under this chapter shall receive state aid funds appropriated pursuant to the purposes and provisions of this chapter in an amount not to exceed 75% of the cost of the planning of the solid waste collection and disposal system. If federal funds are received, the sum of state and federal grants-in-aid shall not exceed 75% of the cost of the planning of the solid waste collection and disposal system.