Replacing a Deck or Pier Over Water?
Avoid Chemically Treated Wood and Get a Shoreline Exemption
Two of the most commonly observed shoreline violations are the use of pressure-treated wood for replacement of planking over water and repair of residential and commercial piers without authorization through the shoreline exemption process.
While many property owners would prefer to use chemically treated wood for outdoor use because of its low cost and resistance to decay, such wood is treated with chemicals that are toxic to both humans and aquatic life. Due to the potential adverse aquatic impacts, DPD has prohibited the use of CCA- and ACZA- preserved lumber for pier decking and bulkheads in residential and commercial zones, while allowing use for immersed and partially immersed structural components of piers and other over-water structures.
Preserved or “pressure-treated” wood is most commonly treated with a mixture of either chromated copper arsenate (CCA) or ammoniacal copper zinc arsenate (ACZA) and can usually be identified by score marks on the surface. Since December 2003, the U.S. Environmental Protection Agency has banned wood preserved with CCA from production for use in most residential settings because of adverse impacts to human health. The chemicals in CCA—chromium, copper and arsenic—have been related to nerve damage, anemia and diarrhea, as well as bladder, liver and lung cancer. Additionally, the copper that leaches from treated wood is toxic to fish and does not degrade, but accumulates in the environment over time.
Further, normal maintenance and repair over water requires DPD authorization through a Shoreline Exemption. For more information on shoreline exemptions, see Client Assistance Memo (CAM) 209A, Shoreline Substantial Development Exemptions Application Instructions.
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