In Washington State, may a county government vary its roadway construction and maintenance standards for themselves and others

A large county refuses to allow certain asphalt repair practices to utilities, and other local gov'ts because they claim the products and practices are not "proven and reliable" for their long term goals. They are also much less expensive than the current county requirements. Yet, for their own roadway maintenance and repair crews, they use these "unproven and unreliable" practices on a very regular basis. Do their actions alter the code to the point that other utilities may legitimately follow suit and demand the less expensive practices and standards? - Is this your question? Add additional information