(1) The evaluation of the solid waste stream required in RCW 70A.205.240 shall include the following elements:

(a) The department shall determine which management method for each category of solid waste will have the least environmental impact; and

(b) The department shall evaluate the costs of various management options for each category of solid waste, including a review of market availability, and shall take into consideration the economic impact on affected parties;

(c) Based on the results of (a) and (b) of this subsection, the department shall determine the best management for each category of solid waste. Different management methods for the same categories of waste may be developed for different parts of the state.

(2) The department shall give priority to evaluating categories of solid waste that, in relation to other categories of solid waste, comprise a large volume of the solid waste stream or present a high potential of harm to human health. At a minimum the following categories of waste shall be evaluated:

(a) By January 1, 1989, yard waste and other biodegradable materials, paper products, disposable diapers, and batteries; and

(b) By January 1, 1990, metals, glass, plastics, styrofoam or rigid lightweight cellular polystyrene, and tires.