Preserved Wood in Aquatic Environments


Environmental Assessment Model released!
See more below.

Wood’s structural, economic, environmental and aesthetic benefits make it the preferred building product in a wide variety of construction applications – including bridges, boardwalks, piers and structures in or near waterways and wetlands.

Starting in the 1990s, the potential impacts of preserved wood used in our most sensitive ecosystems – aquatic environments – was the focus of close scientific study. Various governmental agencies, universities and the preserved wood industry have undertaken extensive efforts to understand the potential effects of preserved wood in aquatic environments.

This continuing work has produced a substantive base of scientific knowledge about the behavior of preservative-treated wood and the level of risk it represents when used in aquatic environments. A worldwide review failed to find a single case where appropriately produced and installed preserved wood products resulted in a significant adverse environmental impact. Studies of preserved wood in the most sensitive aquatic environments have shown that the risks associated with preserved wood are small and easily manageable.

The full benefits of using preserved wood products can best be achieved when site-specific project risks are properly evaluated; applicable mitigating measures are utilized to minimize and manage potential risk; the appropriate preservative is selected for the intended application; and the material is properly installed and maintained.

When these measures are properly considered on a project basis, there is a high probability the preserved material will have a long service life and the potential risks will be minimal and manageable for environmentally safe use.

WWPI and others in the preserved wood industry have prepared a number of materials to guide the safe use of preserved wood in aquatic environments. The Treated Wood in Aquatic Environments guide provides guidance in selecting, installing and managing wood preservation systems in aquatic and wetland environments.

The new online Environmental Assessment Model evaluates structures above and below water built with wood treated with one of 11 of the most commonly used preservatives. Instructions on how to use the model are outlined in the Help section of the model and in the publication Screening Level Assessment Process and Worksheets.

Online Environmental Assessment Model

Screening Level Assessment

Improvements in technology, combined with advances in scientific knowledge, have allowed researchers to develop sophisticated models that can predict actual activities. Such models are used widely today, from weather forecasting to identifying financial trends in the stock market.

In the early 1990s, pioneering preserved wood researcher Dr. Kenneth Brooks developed the first models to estimate the potential migration of preservatives and metals from preserved wood immersed in water and exposed to weather.

This work led to the development of the new online Environmental Assessment Model. The new model offers a user-friendly interface and simplifies the process of estimating the potential migration of preservatives used in or over water and in sensitive environments. The model is also available in a Microsoft® Excel-based version available for download.

This model has been peer-reviewed, repeatedly field-tested and proven to protect the environment. It is used by the National Oceanic and Atmospheric Administration, U.S. Forest Service, Bureau of Land Management, U.S. Park Service, Environment Canada and Canadian Department of Fisheries & Oceans as well as a host of local and state regulatory bodies.

Predicting Impacts

Nearly all materials, man-made or natural, placed in an aquatic environment will introduce chemicals which, if present in large enough concentration, can either immediately or over time pose a potential threat to plant and animal life forms dependent upon that environment. A certain quantity of the chemicals used to preserved wood will migrate from treated wood structures built in aquatic and wetland areas into the water column and surrounding sediments. The question is how much and when will the preservatives move into the environment and under what circumstances might they represent a significant risk.

The online Environmental Assessment Model is a flexible tool that can estimate potential migration of chemicals from preserved wood in water for 11 of the most commonly used preservatives. These include CCA, ACZA, ACQ, CA-C, Copper Naphthenate, Creosote and Pentachlorophenol.

Click here to review the online model or go to the Technical Library for the Excel version and other materials. Details on how to use the model are outlined in the publication Screening Level Assessment Process and Worksheets.