Pit burning is something I never did before I got an excavator. Why do logs and brush seem to burn so much better in a pit?
I recently burned about 10 dump trailer loads of brush and logs, each about 14x7x6'. I burned in a 20x8x8' pit I dug out in the middle of a field. I like the way the pit confines the fire and minimizes spreading sparks if the wind comes up and the ease of covering the pit with dirt to make sure every ember is out. Far easier to manage than an open brush pile.
I wasn't prepared for how quickly logs turned to ash. I was afraid the pit would limit getting oxygen to the bottom but that didn't happen. The fire even at the bottom of the pit burned with high intensity. I dump the trailer loads near the pit and use the new excavator to load the piles into the pit, a little at a time until the fire gets going then push in piles at a time, using the bucket as needed to distribute the fuel.
The pit fire seems to burn much hotter and far quicker than a brush pile in the open which is what I did for years. With a brush pile I was constantly pushing and turning the pile with the tractor and pushing unburned logs into the hottest places. The entire pit appears to turn into a uniformly raging inferno.
We do have some coal in Indiana, but just off to the west side of Rte 41 in the northern part of the state there is an underground peat fire that has been burning for many years.
It was started way before my time and I am 78. Kind of interesting in the winter when snow is on the ground as the area is hot enough to melt any surface snow.
I remember in the 50's that there was an effort to extinguish it, they tried several things - nothing worked at all. Don't know how much fuel there is but I'm sure it will be burning long after I am gone.
It is fortunate it is not near any towns or (as far as I know) buildings.
There was a fire in an underground mine in Jerome AZ that burned for years - the deposit there was mostly sulfide ore of a type that is very densely packed in seams a bit like a coal deposit. Sulfides form in oxygen deprived environments, and both the metals and the sulfur will oxidize readily if they get hot enough in the presence of oxygen.
The town that I live in in Connecticut requires a burn permit, $10, to burn brush. Even with a permit, permit holders must call to get permission to burn. Only 3 burnings per day are allowed. Burning is not allowed on windy days, dry days or overcast visability days. Burning is not allowed in July or August. That requirement really bothered me so I asked why. I was told that it was a carryover from when washed clothing was drying outside. Disallowing burning prevented theh clothing from picking up a smoky odor. I've rarely seen a house in my town with an outdoor clothes line. So Now I do not burn at all. I pick up the brush and sticks and break them into pieces about 6" long and flip them into the woods. The short pieces make good contact with the ground and deteriorate quickly.
A commercial sized chipper like those arborists use would be quicker, cleaner, and produce a useful and likely salable product.
Someone might think so until they saw what I am collecting and burning.
I looked into a wood chipper at one time - very expensive for a commercial quality chipper. I'd love to have one and it might be a good idea if I operated a tree service and/or regularly had a quantity of wood useful for chips. At my place useful wood gets turned into boards or woodturning blanks.
I am cleaning up underbrush and downed trees in the woods between two large farm fields. Several problems with chipping what I'm getting:
1- There is no good wood. None is from trees I cut or even from trimmed branches. All the logs are from downed trees, some laying on the ground for years, some partially rotted, some very rotted. Plenty of powder post beetles and grubs. Many trees are pines with the outer sections rotted but with some perhaps useful for chips at the core if you cut away the rot. There are some cedar logs in good shape but I haul them to my sawmill behind the barn.
2- Most of the bulk is small brush, mostly invasive bush honeysuckle and privet. (I carefully leave the holly, maple, poplar, sassafras, and such.) Some plants are less than 1/2" diameter, some perhaps an inch or so. A good portion of the weight is in roots balls loaded with dirt. I try to shake excess dirt off with the excavator as I grab and pull each plant out of the ground. There are a number of big wild grape and poison ivy vines I pulled down from large trees. Very few useful chips in any of this.
3. There is a lot of dirt and rocks mixed in with the brush and the roots. Some rocks are fairly large and should not be fed into a chipper.
Bottom line is separating for chipping would take a huge manual effort and probably result in a large gooey mess and just a few bags of chips from the tons of debris I've collected.
If I was unable to burn I could haul the debris to the county landfill but that can get expensive in fuel and dumping fees.
The biomass would be good for composting if shredded. I do have a separate area where I dump stumps and roots and rotted logs and brush, a steep hillside. I periodically use the bobcat to push down and level the mass as it rots and add soil on top when I have extra. After some years that hillside will be effectively covered with good soil.
BTW, free burn permits are required in this county from Oct 15 through May 15. The rest of the year no burn permits are needed or issued. At certain times, such as during a severe drought, burning is prohibited. Many towns and cities in the area have their own, much stricter rules. The type and size of the material to be burned is restricted. There are safety requirements such as constant supervision and having access to water or heavy equipment to contain the fire.
There are severe fines not having a burn permit when required and far more for letting a fire get out of control! A neighbor down the hill did that once by going in for lunch and taking a nap while burning a brush pile during a dry period. Flying embers set the woods on fire and the big guns were called in to contain and put it out. I'm guessing with fines and fees that nap probably cost him thousands.
I think burning in a pit in the middle of a big field just after a rain and with two watchers and big equipment and water hose on hand is about as safe as you can get without using a furnace.
