Wednesday, July 22, 2015

Notes on Wood Waste

Wood by itself is just part of the environment; however, large quantities of wood waste piled up along the shore or accumulated within water way sediments can lead to anoxic conditions as the wood decays. The anoxic conditions in areas where anoxic conditions would otherwise not be present can have an obvious impact on the biotic environment. Once the pile of decaying material goes anaerobic, the chemistry of the water and soils in the vicinity is going to be significantly altered. Oxidized metals in the soil have the oxygen stripped off and become mobile. 

The decay process in landfills that leads to anaerobic conditions cause landfills to generate methane gas, hydrogen sulfide gas and production of leachate (leachate-iron-stains-in-ditch)

While piles of wood and organic matter leading to leachate and methane off gassing can and does occur naturally, wood waste is a legacy issue in many Washington waterways. Lots of wood material piled up around saw mills, paper mills and log storage areas. Due to the potential for this old wood waste to cause harm, the Washington State Department of Ecology has developed a guidance for wood waste assessment and cleanup (Ecology 2013) 

There is some difficulty in determining the difference between wood waste and natural wood or figuring out where the source of the wood waste came from (who to blame). For some sites such as the former Scott Paper Mill in Anacortes the answer is fairly straight forward. 

Former Scott Paper Mill, Anacortes

Wood waste in tidal zone (Ecology)  

Leachate seep in tidal zone (Ecology)

The north shore of Bellingham Bay poses a bit of a different problem. Large swaths of fine woody debris cover the upper beach - and it has a history of being moved around as the shoreline in this area is dynamic with the interaction of the Nooksack River. Where did all this material come from? 

Drifts of fine woody debris, Bellingham Bay shore

Compact mat of woody material along eroding shore.
Willow trees on this shore reach are holding some of the wood in place 

Fine grained woody material

I have no answers to this problem. I have a vague understanding that others have had a go at trying to solve the question of where the woody material came from. Perhaps a case of multiple working hypothesis. There is also a question as to what harm the material may be causing. Bellingham Bay has some health issues which have been a bit perplexing and wood may be a part of the problem.

Oblique shore pictures may provide some clues but nothing definitive.

2005 shore view (Ecology)
Note dark woody debris on the right along shore is same as pictures above.
Nooksack River on left is playing a role in the erosion rate at the shore.
Note dirt road to shore.

1977 view of same shore reach only a broader view (Ecology)

There is a bit of wood waste history in the image above and the one below. Within the near acute angle intersection at the airport note the trees in the above 1977 image. In the next image from 2000, the trees are gone. Georgia Pacific operated a wood waste landfill at the site from the late 1970s to the early 1990s.   

2000 view of shore reach and Bellingham Airport (Ecology)

The wood waste landfill at the airport points to a change in how mill handled wood waste. Initially burning the wood was a common practice. But with the Clean Air Act starting in the 1970s another solution was needed for the wood waste. Some could still be burned in better designed, cleaner boiler furnaces, but these were limited to the types of wood that could be fed into the furnace. Another solution was to land fill the wood waste such as Georgia Pacific did in the Bellingham area. GP had two wood waste landfills with some rumors about other smaller sites and even a rumor that some of the material was hauled out into the bay and dumped. The window of time when the mill was transitioning from burning waste to landfilling is one of those potential sources of uncertainty. 

Of course the other issues is that there were prior to GP other mills on Bellingham Bay and currents and wave movement could also float material in from elsewhere.  And then there is also the river itself. Wood waste from up river may have been a contributor. And there is certainly a large volume of natural wood coming down the river.   

Nooksack delta with channel filled with wood

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