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You might not be
able to burn or bury debris cleared from your construction site,
but that doesn't mean you can't add value to it and maybe even cut
construction costs.
By Greg Northcutt
When Michael Holbrook
began clearing construction sites in the Atlanta, GA, area back
in the mid-1980s, disposing of brush and other woodwaste was a pretty
simple process. "We piled it up and burned it,"he recalls.
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| Feeding Megabyte,
Bandit's large stump and log shear attachment |
Today, reflecting increasing
concerns with protecting the environment and conserving landfill
space, things are more complicated. Burning in this area is banned
from May through September, Holbrook notes. The rest of the year,
it's legal to set fire to cleared woody debris but only if weather
conditions are right and only between 10 a.m. and 6 p.m. "If
you're burning and smoke drifts into residential and other developed
areas, county officials can shut you down, even if it is legal to
burn," he remarks. "You just don't know from day to day if you can
burn. In many cases, it's a lot easier not to fool with it."
Digging a hole and burying
the wood debris isn't permitted either. At the same time, hauling
the cleared material to a landfill can be expensive in terms of
hauling and tipping charges, as well as time. So whatever the loggers
leave behind, Holbrook runs through his grinding machines, converting
the waste into 6-in. and shorter pieces. The grading contractor
either spreads the material on-site to decompose naturally and enrich
the soil or places it on cut-and-fill slopes as a mulch to control
erosion.
Holbrook's
company, Flat Creek Clearing, based in Talking Rock, GA, is hired
by grading contractors to clean up new or redeveloped sites ranging
in size from a few acres to a hundred or more. Once the site is
logged, he and his crew recycle the leftovers: tree limbs, saplings,
logs, and tree stumps. A dozer and a blade equipped with a point
rips out stumps, and a shear, mounted on a Caterpillar 225 excavator,
cuts the stump and root balls into smaller pieces for grinding.
The excavator also is used to rake up the wood debris and feed it
into a self-propelled 3680 Track Beast Recycler made by Bandit Industries.
The remote-controlled, 56,000-lb. horizontal grinder has a cuttermill
with a 30-in.-high and 60-in.-wide feed opening and an electronic
governor designed to keep material flowing through the unit without
causing the 475-hp diesel engine to stall.
The
amount of debris Holbrook recycles from a cleared site can be considerable.
"Some days we do nothing but feed material into those grinders,"
he observes.
Producing
Organic Byproducts
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| The TG800 tub
grinder makes fast work of stumps and logs. |
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| Ashley Construction's
operation uses a Morbark Model 5600 Track Wood Hog. |
The demand for services,
such as those that Holbrook provides, has increased significantly
in the past five to 10 years as communities have banned burning
and burying of brush, stumps, logs, and other materials removed
in preparing sites for grading and excavating work. The ability
to add value to material that once was waste is another big reason
for the growth in recycling of debris removed during site preparation
activities.
"When
you burn woodwaste at a construction site, any profit goes up in
smoke," states Mark Rieckhoff, a products specialist with
Vermeer Manufacturing Company's Environmental Division. "But
by chipping or grinding it, you end up with material that can be
used on-site or sold."
The
uses of recycled wood debris range from controlling erosion and
covering landfills to mulching landscapes, fueling boilers at co-generation
power plants, and providing bedding for livestock. Colored landscaping
mulch—primarily black, red, and brown—is another outlet
for recycled woody debris. According to Tim Griffing with Continental
Biomass Industries (CBI), a manufacturer of wood-recycling equipment,
it's a relatively new and fast-growing market. "Many
mulch producers in the East can't get enough of the material,"
he reports. "Over the past several years the price has increased
from about $5 to $10 per cubic yard to $20 to $25."
These
developments have transformed operations to prepare land for grading
and excavating projects. The idea of bulldozing slash and scrubby
material, pushing it into a pile, dousing it with kerosene, and
lighting a match has given way to more sophisticated techniques
and equipment. They include both wheeled and tracked machines, such
as chippers, which use knives to chop brush and whole trees—some
as large as 20 in. in diameter—into small chips, as well as
massive hammer-mill grinders weighing 100,000 lb. or more, which
can produce in excess of 400 yd.3 of wood byproduct an
hour. Screens with diamond, round, or square holes allow operators
to vary the texture of the materials and the size from about 0.75
to 6 in. long. Similar to Holbrook, who sits in the cab of his excavator
as he feeds his grinder, some contractors have turned large wood-recycling
projects into one-person operations using wireless remote controls
to operate the grinders or chippers.
Other
equipment choices include shears, such as one pivot-type model for
use on 50,000- to 75,000-lb. excavators, which reduces stumps and
logs to smaller pieces using 140,000 lb. of crushing force; log
splitters, such as one unit that can quarter logs nearly 9 ft. long
by applying 100 tons of pushing force against a wedge; and compact
stump grinders that attach to skid-steer loaders for working in
tight areas, as well as large self-propelled, rubber-track units
with a grinding width of 92 in.
Depending
on the type and size of equipment, terrain, and density of cleared
material, one person often can chip or grind-process 3 or 4 ac.
of cleared woody debris a day. If things go well, a skilled operator
might even double that. For example, one manufacturer claims that
its track chipper, with the ability to handle trees up 19 in. in
diameter, can process the trees from 1 mi. of 50-ft. right of way
in a day. Another rates daily production of its horizontal grinder,
which can handle 30-in.-diameter logs of any length, at 75 tons.
This equipment also can be used to recycle railroad ties, telephone
poles, pallets—all of which is removed from the nation's
wastestream. In areas where the tipping fee for dumping debris may
reach $100/ton, that's another big plus for recycling woody
rubbish.
Recycling
Rock
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| There's work
in the wood-debris recycling field for small equipment too. |
Other site-preparation
construction debris–disposal problems also are being addressed.
For example, asphalt shingles from construction and demolition projects
are being recycled to pave parking lots and highways. Even rocks,
once hauled away from construction sites, are being processed for
reuse on the job.
"It's
getting harder to find places to dump big, jagged rock because of
difficulties in getting the required permits to establish new sites,"
states Harold Chapman, president of H.L. Chapman Pipeline Construction,
a trenching and excavating company based in Leander, TX. "Also,
more and more people don't want rock crushers in their neighborhoods.
As a result, getting rid of rock in a timely manner can be a problem."
For
that reason, he uses a rock milling machine when excavating for
streets, highways, and building sites. Called a Road Miner, it mills
through rock with a swath up to 19 ft. wide and 5 ft. deep in one
pass, depending on the model. It offers an alternative to blasting
and ripping, and it produces material ranging in size from tiny
particles up to a diameter of about 5 in. "Instead of a rock
disposal problem, you end up with material that can be used for
fill," points out Bobby Cook, sales administrative manager
for Trencor Inc., which manufactures the machine.
Chapman's crews use two
different Road Miner models - a 250,000-lb. machine and a 500,000-lb.
unit on excavating projects as large as about 250,000 yd.3
He reports they will mill limestone, sandstone, and volcanic rock,
but not granite. The machines are used to cut as deep as needed
to produce the final grade, usually milling about an 18- to 24-in.
depth of rock with each pass.
Ripping
or blasting rock usually produces 1- to 3-ft. chunks, Chapman notes.
By contrast, the material milled coming off the conveyor of the
Road Miner resembles crushed rock. It usually is processed to about
a 1- to 3-in.-diameter size for road-base use and a 3- to 5-in.-diameter
size if it is used as fill. He adds that the machine produces a
usable material while reducing excavating and compaction costs.
Controlling
Erosion
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| The Log Buster
can draw and quarter an entire tree at a time. |
Recycling organic materials
cleared from construction sites also offers new techniques for controlling
erosion and for complying with new federal stormwater management
regulations that will impact construction activities in many areas
of the country, beginning in March 2003.
That's one avenue being
explored by Pro-Bark Inc. of Georgetown, MA. While the company does
some site clearing, its main business is operating a yard that processes
materials brought in by land-clearing contractors and reselling
the end products.
In addition to grinding
logs, stumps, and brush from construction sites, which is sold as
fuel or mulch, the company also processes and composts residential
yardwaste and bark from saw mills. The company uses a CBI shear,
mounted on a Komatsu PC 220LC excavator, to cut the stumps that
it feeds into a CBI Magnum 4000 horizontal grinder. This 74,000-lb.
triaxle machine, operated by radio control, has a 16-ft.-long, 60-in.-wide
feed conveyor. McLaughlin reports that the hourly production rate
of the grinder in the recycling yard ranges from about 200 to 600
yd.3 of end product, depending on the type of material
being processed (e.g., stumps, logs, or bark) and moisture content.
Some
of the aged and composted ground-up stump material is added to locally
purchased nutrient compost to improve the compost's ability
to control erosion when applied as a vegetated ground-cover finish.
Last year, the company began using a blend of coarser compost in
a new sediment control practice. The coarse compost is blown into
a long, porous, synthetic mesh tube called a Filtrexx FilterSock.
The 150-ft.-long product is available in diameters of 8, 12, 18,
and 24 in.
The
filled socks are placed on contours to slow stormwater runoff, trapping
sediment on disturbed slopes at construction sites. The diameter
selected for a particular job is based on the degree of slope and
expected volume of stormwater flow, McLaughlin states, adding that
the 18-in.-diameter size also can be used for the same purpose in
ditches.
Pro-Bark crews fill the
socks with an Express Blower truck by placing the sock over the
end of the blower hose. "We pull the sock over the hose and then
work backward as we blow material into the sock," McLaughlin continues.
Other uses of Filtrexx
FilterSocks include inlet protection (8 in. diameter) on hard surfaces;
streambank stabilization, which includes a backfill media; and a
living-wall design that replaces brick or block with vegetation.
"Future research includes
FilterSocks that reduce or eliminate E. coli bacteria, hydrocarbons,
and perhaps even heavy metals from contaminated water as it passes
through," reports Rod Tyler, chief executive officer of Filtrexx.
"Most importantly, however, the 12-inch-diameter FilterSock's best
use is to replace silt fence. Using compost in this application
with filter berms has been shown to reduce sediment ten- to twentyfold
more effectively than silt fence."
Pro-Bark
also uses compost blankets to replace traditional fiber mats or
rolled netting products for steep, erodible slopes. "Together
with FilterSocks, the compost blankets have shown a nondetect for
sediment in field tests when installed properly," Tyler states.
"Vegetation establishment using compost on slopes is enhanced,
and call-backs or reseeding normally is not required."
Equipment
Choices
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| The 3680 Track
Beast can easily process entire trees. |
Some of the larger land-clearing
contractors, along with grading and excavating firms, own their
own recycling equipment. In areas where land development activity
is strong, contractors who specialize in recycling wood and other
land-clearing debris have set up shop. Either way, both offer a
variety of equipment for producing usable byproducts. Chippers generally
do the job faster and more efficiently than grinders. Disk-type
chippers are generally more cost-efficient to own and operate, but
drum-style chippers, which burn about 20-30% more fuel, are better
for chipping the larger trees with more crotches and limbs. Maintenance
costs of chippers tend to be higher, however, because their knives
can't tolerate rocks, metal, and other contaminants the way that
the hammer-mill grinders can. That gives grinders the advantage
in processing tree stumps, which usually include rocks and dirt
that can cling to the root balls.
The
first wood-recycling grinders evolved from tub grinders developed
originally to grind hay and other feed for livestock. The wood material
is placed into the tub and feeds by gravity into the hammer mill.
Since the tubs measure as wide as 15 ft. at the top, they can handle
larger material, such as tree stumps, that won't fit the opening
of a horizontal grinder.
The
choice of stationary or the new self-propelled units affects setup
of the processing operation. When chippers and grinders are parked
at a landing area, skidders, excavators, or loaders with grapples
or rakes bring the wood material to the processing machine, where
the end product is piled up for later use. This use lends to projects
where the byproducts are hauled off-site. The self-propelled machines,
on the other hand, can go wherever the wood material lies, eliminating
the need for support equipment. They also can negotiate rough terrain,
a big advantage in off-road applications where it might not be possible
to tow a wheeled machine.
In
addition to cutting up cleared logs and stumps, shears can replace
bulldozers for removing stumps in the ground, points out CBI's
Griffing. "When you dig out a stump with a bulldozer, you
take a lot of dirt with it. You can use a shear to remove stumps
up to about 6 feet in diameter by first cutting the stump into several
large pieces and then yanking them out of the ground. It's
faster, and you get cleaner wood. Maintenance costs of a shear,
mainly replacing pins, is much less than a bulldozer too."
Putting
the Machines to Work
Scott Pihl who, with
his wife Renee, operates Ashley Construction in Acworth, GA, has
extensive experience with various types of grinding equipment. When
he and a former partner entered the wood-recycling business in 1994
with a tub grinder, they were among the first such contractors in
Georgia. Today, as the company's sole operator, Pihl runs two 5600
Morbark horizontal grinders: one a 74,000-lb. triaxle wheel unit,
the other Morbark's very first self-propelled model, which he bought
last year. Both grinders feature remote-controlled operation, with
a 56-in.-high x 48-in.-wide infeed opening and a 40-in.-wide conveyor
for stacking material to a height of 18 ft. He uses excavators to
feed the grinders, drawing from material piled up or raked into
windrows by the land-clearing contractor.
Pihl works with clearing
and grubbing contractors on projects as small as a single residential
lot to 200-ac., 6-mi. power-line right-of-way jobs. As he points
out, limiting damage from undesirable material is a key factor in
keeping production up and costs down.
Pihl
also runs two Hitachi excavators: an X270 equipped with a single-cylinder
Rockland shear and an EX230 outfitted with a two-cylinder CBI shear.
"I won't grind any land-clearing debris without shearing
it first," he says. "Cutting the material into smaller
pieces allows the grinder to work much more efficiently. The machine
hums right through the material without fighting it.
Processing
as much as 2.5 tons of wood per minute, he grinds it down to 4-in.-long
material, which is typically spread about 6 in. thick on-site to
control erosion. "It provides an immediate cover for exposed,
disturbed ground, and it's placed at critical areas in ditches
to make check dams, which slow runoff, also helping to control erosion,"
Pihl continues. "It also provides a temporary base for construction
contractors to work on. Once the work is done, the mulch can be
plowed in and grass can be planted."
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| Ground-up stump
material added to nutrient compost is blown into FilterSocks
for sediment control on construction sites. |
Pihl reserves the 68,000-lb.
trailer-mounted grinder for smaller, easy-to-access sites. The other
work is assigned to the self-propelled model. "It saves a tremendous
amount of money for the project developer by simplifying the recycling
process. It eliminates the need for a skidder or tractor to push
debris to a stationary unit all day, and I don't have to travel
far to spread the mulch evenly over the ground."
The
self-propelling ability also eliminates the wear and tear on equipment
when trying to trailer machines into rough and roadless areas. "With
the self-propelled grinder, I just unload and go to work,"
he remarks.
Another
wood-recycling contractor with plenty of experience operating a
variety of grinding equipment is Consolidated Resource Recovery
in Sarasota, FL. Company Vice President Steve Lubbers has been in
the business of recycling organic materials, including debris left
by site-clearing operations, since 1989. The company operates in
Florida and Georgia, using Morbark horizontal grinders and track
chippers and Vermeer tub grinders. It produces and markets a wide
range of end products used for landscaping, organic farming, and
fuel. Processing organic materials at landfills and recycling yards
represents about 70% of the company's business. The rest involves
mostly land clearing, site preparation, and custom grinding.
One
job involved processing several piles of large pieces of oak, some
nearly 4.5 ft. across. Consolidated was the only contractor in the
area with a grinder large enough to handle the work efficiently—a
96,000-lb., 800-hp Vermeer TG800 tub grinder with an inside tub
diameter of 11 ft., which flares to 13.6 ft. wide at the top. "That
machine helped us get the job done profitably and ahead of schedule,"
Lubbers states.
Mulch
from land-clearing debris often is spread on slopes to control erosion
and mixed with onsite soil to cover landfills. "We also mix
the wood mulch with dirt as a degradable soil amendment for use
on green areas where roads, building pads, and other structures
won't be built," he adds.
A Role for Compact
Equipment
There's
work in the wood-debris recycling field for small equipment too,
relates Jon Moffet, president of Environmental Forestry Inc. in
Hayden, ID. He's taken technology used to build rotary disk
attachments for large excavators and adapted it to develop a similar
tool for certain models of Caterpillar and ASV compact track loaders.
As Moffet describes it,
the hydraulically powered attachment features a rotating disk with
carbide teeth on a boom that swings up, down, and sideways to cut
a swath 8-10 ft. wide. It can be used to cut down trees up to about
10 in. in diameter and process them, as well as brush, into a wood
mulch, with pieces measuring about 6 in. or smaller in length. The
mulch is left on-site to control erosion until it degrades and helps
nourish the soil, eliminating any hauling costs.
The
rotary disk and compact loader also can be used to clean up an area
before coming in with equipment to remove stumps, he notes. And
unlike bigger machinery, the unit can be used to selectively remove
trees without damaging the remaining, more desirable ones.
Moffet
points out another benefit: "This tool leaves a cleared site
looking like a park."
Author Greg Northcutt
is a frequent contributor to Forester Communications publications.
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