Pile Burning

Pile burns are a type of prescribed fire where firefighters pile and burn forest debris to reduce an area’s wildfire risk.

• These piles are made from the debris left after fuel reduction projects that involve thinning or cutting of trees in the forest.
• Piles are only ignited under certain conditions, including favorable smoke dispersal and adequate snow cover, which helps contain the piles. These conditions direct firefighters on where within project areas burning can occur due to the localized nature of conditions.

Prescribed fire is an important tool for decreasing long-term fire risk to communities and to restore our forests so they are more resilient to natural fire in the future. Public and firefighter safety is always the number one priority in burning operations.

Wind is needed for smoke dispersal, and firefighters can safely burn piles in windy conditions. We monitor the forecast for favorable weather conditions and analyze the short term and extended forecast every time we ignite. If winds are forecast that could potentially create fire behavior that would put communities or residences at risk, firefighters don’t ignite piles.

If conditions do allow firefighters to burn piles, it isn’t unusual for wind to cause more smoke and flames to be visible in the days after ignitions begin. Open flame and flare ups can occur and be visible to surrounding communities, especially during wind events and patchy snow conditions. Areas in between piles within the prescribed fire unit are sometimes allowed to burn. This can reduce more hazardous fuels, therefore further reducing the overall wildfire risk. It’s important to note that even with the most thorough planning and preparation, the use of prescribed fire carries an inherent level of risk that cannot be eliminated entirely. At the same time, prescribed fire is one of the most efficient and effective ways to reduce wildfire risk.

Smoke, flames, and glowing embers are often visible and are a normal part of pile burning operations, and they can be visible throughout the night. Over time the heat and flames from the piles becomes less intense as the fuel is consumed. Mild fire behavior between piles is expected and is beneficial for future wildfire risk reduction. This includes forest litter and debris between piles and lower limbs of trees. This mild type of burning helps reduce available flammable fuels.

Pile burn areas can remain active and smolder for days to weeks after they are ignited. In most cases the piles go out naturally, but on rare occasions firefighters will suppress burning debris that have not gone out on their own.

Patrolling and Monitoring: We patrol and monitor our previous pile burns until they can be declared “out,” or cold. When a change in weather occurs, we adjust the monitoring and patrolling schedule appropriately. It is not unusual for smoke and flame to be present for up to a week after burning a small slash pile, and longer for larger piles.

Public and firefighter safety are our top priority. That said, we can’t remove all risk associated with prescribed burning: We make decisions based on the best available science. We insure we have adequate resources and staffing available. High winds are a regular event along Colorado’s Front Range, and we analyze the short term and extended forecast every time we ignite. Piles can burn for a longer duration than our forecast is reliable. With the amount of forest management work that we need to do across the Front Range to address the wildfire crisis over the next decade, we must be prepared for strong wind events to occur between pile burning ignitions. Being prepared includes making sure we have the sufficient staffing, resources, and coordination with partners, including local fire departments.

When site-specific conditions dictate it is safe to do so, firefighters may leave burning piles overnight. When an unfavorable change in weather occurs, they adjust the monitoring and patrolling schedule to accommodate.

Burning piles produces smoke and breathing too much smoke may affect your health. Pile burning often produces far less smoke than a large wildfire. Often, smoke from pile burning does not impact the public. Firefighters look for conditions with favorable wind to aid smoke dispersal, lifting smoke up and away to keep the impact low for local communities. For more information see https://www.colorado.gov/pacific/cdphe/wood-smoke-and-health

We obtain smoke permits from the State of Colorado and these permits will have limitations on the number of piles we can burn in one day to minimize smoke effects. When conditions are favorable, it is not uncommon to burn more than 500 piles a day within a project area.

Standing live trees may be affected by pile burning. It is common and acceptable to have “scorched” trees within project areas. Many, if not most, of these trees will not die. Approximately 2/3 of a tree crown can be scorched without killing the tree. That said, if the top of the tree is scorched or burned, the tree will most likely die. We take precautions when lighting piles to avoid this, but it is within our planning specifications to accept minimal tree mortality.

Pile burning is the most efficient option to reduce forest debris at the scale and speed needed to meet our goals and reduce wildfire risk.

One alternative would be to leave piles, but it is unclear how that would affect the forest, it creates a visual problem, and it would not reduce hazardous forest fuels which is the intent.

Other options for utilizing forest debris are slowly gaining traction in the Rockies. Forest debris and other wood waste are being used to generate heat and electricity, biofuels, and products such as biochar and activated carbon. Learn more about one regional project, the Bioenergy Alliance Network of the Rockies. Still, there will always be piles that are too inaccessible to be transported, and so continued work for mitigating pile burn effects will remain relevant, especially for sensitive and inaccessible areas.