For situations where durability is essential, consider plastic lumber products instead. If you need treated wood, choose from this list of wood preservative alternatives for arsenic. That list is also on page 43-45 of the San Francisco Guide to Selecting Treated Wood.
City agencies are prohibited from using arsenic treated wood except for certain applications that involve saltwater immersion. Details can be found in the list of Approved Alternatives to Arsenic Treated Wood. Exemption requests must be submitted to SF Environment.