All structures are inspected 3 times yearly. All repairs are prioritized and work is assigned accordingly. Structures that are shaded or stay moist are washed approximately 2 times per year. Other structures that are in full sun or that for the most part stay dry may only be washed 1 time every 2 years. It needs to be noted that when we wash structures that we can only use water (no chemicals) because of the environmentally sensitive nature of the Greenway system. With that said when we do wash (with water only) the mold, mildew and other things that may grow on the wood comes back quickly. There really is not a viable cost-effective tread material for treated wood.