Landfill Managers Notebook: Tree Mortality: California’s Wood Waste Explosion

Photos: Neal Bolton
Sierra Nevada mountain range

The Western slope of California’s Sierra Nevada mountain range is known worldwide—famous for the 49er Gold Rush, Yosemite National Park, the world’s largest trees (Giant Sequoias), and Mount Whitney, the tallest mountain in the continental United States. But it is also—perhaps less famously—home to California’s fastest-growing wastestream.

No, we’re not talking about C&D or yresidential food waste—it’s wood waste. The Western Sierra’s are experiencing the most severe die-off of Ponderosa Pine trees in the Golden State’s history.

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Chipper operations

The US Forest Service estimated in 2016, that there were 102 million dead trees . . . up from the previous year’s estimate of 26 million. Time will tell how much this year’s drought-busting rains will slow the rate of die-off . . . if at all.

This tree mortality disaster is a perfect storm where trees—weakened by several years of drought—have become especially susceptible to an exploding population of pine beetles. But the story really began many decades before the current drought.

For more than half a century, Smokey Bear has been telling us that wildfire is bad . . . and, “Only you can prevent wildfires.” And so we did—very effectively. And as a result, millions of acres of forestland have become overgrown with brush that would normally have been removed every few years by the natural process of wildfire. Excessive vegetation, several years of drought, and a bumper crop of pine beetles created a lethal chain of events that resulted in a massive die-off of Ponderosa Pine trees.best
use often comes at the highest price.

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Now, many of those trees—those that pose a threat to human safety and vital infrastructure (such as roads and utility lines) are being felled (That’s a logger’s term that means “cut down”). This has created perhaps the biggest spike in waste generation that California has ever seen.

Historically, the State’s landfills have processed something around 5 million tons per year of urban, commercial, and forest wood. But many more million tons of tree mortality wood is entering the wastestream . . . as we speak. No, we won’t be removing 102 million trees. Most of them are in the forest where they pose little threat (other than wildfire). But there are hundreds of thousands of trees that will be felled to protect tens of thousands of miles of roads and utility lines. Currently, many of those trees are being chipped and transported down the hill as biomass fuel. Some are also being cut into lumber or sent to shaving plants to create livestock bedding material.

Anecdotally, it’s easy for an arm chair quarterback to say simply, “Ah let’s just cut the trees and haul them off.” Such a statement sounds so incredibly simple and practical that it defies argument. What could be easier than cutting the trees and hauling them off? But unfortunately, it misses the tremendous complexity and hidden costs associated with such an approach.

The best approach is always one that is based on a realistic application of basic process improvement tools. In order to show how an experienced, practical assessment can help us see what we are getting into when we decide to simply cut the trees and haul them off, we will take a closer look at what this really means.

One of the more popular options current is to chip the trees and transport the chips to a biomass facility where they can be burned to generate electricity. While appearing initially to be the most economical and environmentally friendly option, our initial assessment shows that it’s actually the most expensive option . . . and the one that will produce the greatest amount of CO2.

To give a perspective, an individual tree may be touched a dozen times before it finally arrives at a biomass plant, and every time it’s touched, there is a cost.

Of course the economics will depend on where the trees are located in relation to a potential end use, but for many communities, the options truly are limited by available funding.

These processes are very much in line with goals of finding the highest and best use. But the future is uncertain. If the die-off rate continues, the sheer volume of dead trees could eclipse the capacity of what can be processed—at least in some localized regions. Many local communities are also finding that achieving the highest and best use often comes at the highest price.

So in some cases—due to budget and/or processing limitations, trees are being felled . . . and left on the ground. This is certainly the least cost option in situations where the downed logs will not block a road or create some other safety hazard.

In other cases, they may be transported a relatively short distance and processed by what’s known as an Air Curtain Burner. These units—imagine a fireplace the size of a 30-yard roll-off bin—offer a disposal alternative that requires much less processing time and money than the biomass option.

Because of the very nature of wood processing operations, they offer tremendous potential in regard to streamlining the process and reducing overall cost.


Process Improvement: Leverage Operational Efficiencies

The cost of removing these trees—if not ­astronomical—is certainly approaching a low orbit. The average cost of getting a single tree to a Biomass plant is around $1,200. That’s $1,200 per tree! Multiply that by a few hundred thousand trees that will be processed—and you begin to get a feel for the magnitude of this disaster.

Yes, even with dead trees, the ideals of recycling must be balanced against the cost. This is a common story in the waste and wood waste industry: where some-times the cost of recycling exceeds the economic benefit. And as we look at this project, it clearly is much more than just a tree mortality issue, it is in fact, a Massive Wood Waste Management Project. It is so massive in fact, that California’s Governor issued an emergency waiver to allow local Solid Waste Facilities (i.e., landfills) and Transfer Processing Operations (Transfer Stations) to accept, store, and process additional wood waste, beyond their current permit allowance.

But because tree mortality is a relatively slow moving disaster—it doesn’t make headlines. And even more importantly, it appears that FEMA support (i.e., disaster funding) will not be part of the solution.

Mitigation responsibilities are shared by a number of public and private stakeholders, with each trying to determine where their obligations stop—and ­others begin.

Mitigating the hazards of the tree mortality disaster is a team effort, one that will likely continue for several years.

California is certainly not the first to face a widespread tree mortality issue, but for a state that has pushed very hard to make diversion work—it is certainly a new challenge. MSW_bug_web

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