Please see the "Colorado Pile Construction Guide
" for lots of great information on how to build slash piles.
Before building any slash piles, check with local law enforcement, local county/city officials and the local fire department.
If the slash piles are in Boulder County, you will need a burn permit
. The slash piles may also need a smoke permit.
If the plan is to burn slash piles, (the tree branches put into piles) it is best to know who is going to burn the piles. The expectation of anyone burning a slash piles is 100% success, all the time. Any fire escaping from a slash burn is not acceptable. Prevention of a fire escaping a slash pile burn starts with the location and construction of a slash pile. Here are some things that prevent piles from being burned successfully. The items listed here should not be considered a complete list of slash pile issues. The link to the guide above has the information on how to build slash piles correctly. We strongly recommend that who ever builds a slash pile be the one to burn it as well.
This image is of a tree stump that was under a burned slash pile. The stump
has already been dug out and you can still see 2 roots that are burning.
These burning tree roots must be dug up and fully extinguished during mop
up to prevent fire escape.
Before putting the slash
into a pile, the location of the pile needs to be thoroughly checked. Look
for overhead concerns; such as the tree canopy, power lines, phone lines,
or anything that could be combustible. There must be enough overhead clearance
for the slash pile to burn without threatening overhead utilities or combustibles.
How much clearance comes with pile size and experience. When in doubt, have
more clearance. Look around the slash pile location in a 360 degree circle.
Make sure that there are no nearby structures, roads, or combustibles of any
kind. Even if the heat and flames do not reach a structure/road, smoke can
drift a long way and smoke impacting infrastructure is not good. The ground
needs to be clear of stumps for the size of the pile that is planned plus
an additional 4 feet. Avoid rocks under the slash pile: they may heat up and
explode if they contain moisture. If the slope is steep, the slash pile could
slide down the slope. Make sure all the logs in the burn area have their branches
cut off flat on the log's surface. The burn area needs to be safe for anyone
who will be walking through the area with snow on the ground. Sticks/branches
sticking up on logs or from the ground create a Punji Stick, which no one
wants to slip and fall on.
In the lower right corner of this image you can see a log against the slash pile and another sticking out from under the pile.
We burn only piles with smaller diameter material that will consume on the same day it is ignited. Stumps, either in the ground or above the ground cannot be in the pile. Branches need to be 8" or less in diameter. Larger diameter material, 8 inches or more, needs to be at least 4 feet from the slash piles. The only thing in the slash pile should be tree branches. In Boulder County, the pile size is limited to 6 feet cubed or less. Please note that live tree branches will often compress over time to half their original size. A pile that is only 3 feet high is hard to find in the snow and may not have enough material to burn on its own. There needs to be enough dried branches in the pile to support combustion. When piles are first built, the finished size needs to take in compression of the pile.
Here in the foreground you can see branches that will not burn unless put into the pile.
Piles need to be tight to keep out snow. If snow can get inside of the pile, there will not be any dry fuel to ignite. Piles need to have fine fuels that are dry to ignite, such as tree branch needles. If the slash piles are comprised of burned branches, these piles can be very difficult to ignite. Burned branches have a layer of carbon on the outside that adds to the problem of igniting them. Slash piles built solely from burned branches take extra work to build and to burn. The branches need to be cut into a 2 dimensional/flat branches before being put into a pile. These piles need to be built tighter and with more material than piles constructed with live/green branches that have needles. Check with the person who is burning the slash pile. Professional companies may be allowed to burn larger piles. We have permission to burn larger piles, which is much more efficient and allows the consumption of all the material in a pile. The link above for pile construction has additional information.
By the end of your burn day, you want only coals left where the slash pile used to be. On day 2 the pile should be cold to the touch.
It is best if the same person/company who built the piles completes the burning of the piles. Slash pile construction may seem easy, but there is an art to doing it correctly that allows for the pile to be burned safely and successfully.
The best practice is to have professionals both build and burn slash piles. Let us take care of this for you.