(1) Each county and city required to prepare a strategy under RCW 43.19A.030 shall adopt specifications for compost products to be used in road projects. The specifications developed by the department of transportation under RCW 47.28.220 may be adopted by the city or county in lieu of developing specifications.

(2) After July 1, 1992, any contract awarded in whole or in part for applying soils, soil covers, or soil amendments to road rights-of-way shall specify that compost materials be purchased in accordance with the following schedule:

(a) For the period July 1, 1992, through June 30, 1994, at least twenty-five percent of the total dollar amount of purchases by the city or county;

(b) On and after July 1, 1994, at least fifty percent of the annual total dollar amount of purchases by the city or county.

(3) The city or county may depart from the schedule in subsection (2) of this section where it determines that no suitable product is available at a reasonable price.