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Despite advances in technology,
or in ever-more stringent federal clean-water regulations that place
greater pressure on the contractor to eliminate erosion and prevent
sediment loss (all under budget), no one is able to control Mother
Nature. But knowing what's coming, as well as preparing for the
worst, helps contractors and their suppliers remain focused on avoiding
or solving a problem rather than becoming part of the problem.
One example involves
a 2-mi. road-widening project in Charlotte, NC. This project involved
a number of inlets that, by federal and state decree, had to remain
free of any soil intrusion and prevent sediment loss. At a cost
of more than $400 per inlet, a crew of four laborers and two equipment
operators spent 45 minutes at each inlet excavating a small sediment
basin and installing a 10- x 10- x 2-ft. wire and filter stone barrier
to prevent sediment loss, yet they achieved only somewhat satisfactory
results despite high-maintenance care.
Silt-Saver Inc. in Conyers,
GA, supplied the contractor with a sample of the Silt-Saver Frame
and Filter Assembly. Again the workers excavated a small sediment
basin around the inlet structure, but instead of using the time-consuming
wire and gravel barrier, they simply installed the lightweight,
reusable frame over the open inlet. They then placed the nonwoven
fabric filter over the frame and filled the soil pockets at the
bottom of the filter, and the inlet was protected in a scant five
minutes. This reduction in installation time and subsequent maintenance
minimized the overall cost, as well as fears about failures from
rainfall events.
Roger Singleton, owner
of Silt-Saver, points out that National Pollutant Discharge Elimination
System (NPDES) regulations require that all best management practices
be designed, installed, and maintained to meet a 25-year, 24-hour
rainfall event. New techniques such as the Silt-Saver Frame and
Filter Assembly save time and meet clean-water regulations by reducing
turbidity and sediment loss, but most can also add an element of
safety by removing hazardous stakes and covering open holes. This
additional safety precaution provides peace of mind to the contractor
when the equipment shuts down for the night or weekend and children
or other trespassers might be in areas with open inlets, Singleton
says.
Stabilizing the Soil
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| Ground-stabilization
geotextiles separate soft soils from an aggregate layer. |
The increasing use of
building sites in marginal or poor soil areas means contractors
need to do more to stabilize the site to avoid getting stuck in
the soil–and do it affordably. "This has led to the widespread
use of ground stabilization fabrics," says Dave Snyder, marketing
manager for Webtec Inc. in Charlotte. Also known as ground-stabilization
geotextiles, the fabrics provide valuable separation and stabilization
functions. "They give quick protection at the time of need,
whether in the staging area, road, or construction entrance. They
help the contractor to proceed with his project rather than wait
for the area to dry. Ground-stabilization fabrics can be very valuable
tools when rain and spring thaw make construction sites especially
soft."
Geotextiles keep the
existing soil separate from the aggregate used to help stabilize
the high-traffic spot. Snyder adds, "Laying the fabric takes
about as much time as unrolling a roll of carpeting. It's that
simple." He recommends that fabrics be overlapped 18-36 in.,
with 24 in. being typical.
"These fabrics help
contractors meet the new NPDES regs because they help keep the soil
particles in the native soil from pumping up through the stone to
be carried away by construction traffic or water," adds Snyder.
When choosing fabric,
contractors need to know estimated soil strength, the load that
will be placed atop the stone or aggregate, the aggregate thickness,
and the final design. "For example, if you're building
a parking lot and you have to have a construction entrance to that
lot that will become a permanent entrance, then you'll be thinking
not only short term but long term. That's when you'll
go ahead and lay down 12 inches of aggregate instead of just 6 to
8 inches for construction. The extra thickness during construction
ensures that the entrance will remain stable despite any foul weather."
Yard and Stockpile
Stabilization
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| A typical
inlet protection device can be costly and ineffective and create
hazardous job-site conditions when it fails under the forces
of a normal rainfall event. |
Even as contractors work
to stabilize work sites, there's ever the need to ensure that the
equipment yard doesn't become part of the problem, no matter how
strong the storm event. But not every contractor can afford to hardtop
his yard. Tom Carpenter, owner of Carpenter Erosion Control in Ankeny,
IA, notes that leaving equipment out in the weather is not a typical
concern because his seeding and mulching work is focused within
a 20-mi. radius of Des Moines. Equipment is driven to and from the
site rather than left overnight. "We'll have two to three tractors
on-site for seeding and mulching, including one to pull the silt
fence machine, and a skid loader for cleanup and other tasks, so
most jobs are done in a single day.
"At company headquarters
we keep the equipment out of the mud because we laid down a geotextile
material eight years ago on these 4 acres and topped it with 5 inches
of limestone and gravel. Our trucks and machines have a firm, clean
yard regardless of the weather." As an erosion and sediment
control contractor, Carpenter is often called to button up a site
before a forecasted rain event. "Because erosion control is
difficult or impossible to do during the earthmoving phase, sediment
control with silt fencing is one of the best and most effective
practices. We use the ‘tommy' silt fence machine to properly
install silt fencing around stockpiles and staging areas to prevent
sediment loss. Mechanical installation means we get consistent,
effective silt fences every time. Our customers don't have
to worry about the bottom blowing out and contamination to nearby
streams."
The machine also allows
Carpenter to button up many sites in a short time because of its
high productivity. "We can install 100 to 150 linear feet per
man-hour, so we can get in and out of most sites very quickly."
Fiber-Matrix Solution
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| The
'tommy' silt fence machine installs silt fence around a staging
before a storm event. |
While instant weather
can be a problem, there's still the challenge of dealing with the
climate, especially as freezing weather encroaches. One of the challenges
is getting the work accomplished more quickly so the contractor
can wrap up the project rather than wait out the winter. EcoAegis
Bonded Fiber Matrix, manufactured by Canadian Forest Products Ltd.
in New Westminster, BC, is used on the site as well as around areas
where the machines are temporarily parked. Joe Hargitt, product
manager, comments, "This product makes a hydraulically applied
blanket using conventional hydroseeding equipment. It can be applied
where the terrain is too steep for labor crews or where surfaces
are too rough to lay down blankets. It is also sprayed on as an
insurance measure to stabilize soil where machines and related equipment
are stored during the project."
Hargitt explains that
a typical application is done in two passes, at a rate of 3,500
lb./ac., to make about a 1/8-in. mat that is water-porous but doesn't
break down or wash out. "A large hydromulching machine can
cover an acre in less than 30 minutes." An application of EcoAegis,
combined with good vegetation, will ensure the equipment will be
accessible when the contractor returns to the site. He reminds users
to flush and blow out tanks nightly when overnight temperatures
will be below freezing. This is to ensure that the machine is not
iced up and unavailable for immediate use the next morning.
"We recommend our
excavation clients do something so the temporary base of operations
doesn't become a trouble spot," reports Keith Porter,
general manager of Mid-Canada Hydroseeding Inc. in Winnipeg, MB.
He adds that his company takes on projects in Manitoba, Saskatchewan,
and Ontario, doing some $500,000 a year in erosion control services,
chiefly for those in heavy construction and grading and excavation.
In Canada, the Department
of Fisheries and Oceans oversees legislation that applies to sediment
control. "And that includes our temporary parking lots,"
Porter points out. "We strive to keep officials happy so the
work can continue. Our weather challenges include a short period
to work in, with about a six-month working season. There's
always the need to button up for the fall."
He reports that contractors
utilize onsite generators to keep the coolant generating throughout
the machine during off-hours. "The block heater is plugged
into electricity to keep the coolant circulating so in the morning
the engine isn't frozen up. They still need warm-up time before
operating, but block heaters shorten that time, plus initial startup
is a lot easier." Contractors also park on hard ground so machines
don't get frozen to the landscape.
His Finn T170 and T60
HydroSeeders have heat tape on all the piping and the bottom of
the tank. "Installing heat tapes may take five to six hours,
but savings in broken parts alone can be phenomenal. In the fall,
all water has to be drained out of the lines and antifreeze poured
in to avoid crystallization of any remaining water. In one case
we were on our last working day, but the pump had broken overnight,
so we couldn't finish the job until spring."
Here and Now
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| Brubacher
Excavating's two full-time paving crews depend heavily on up-to-the-minute
weather forecasting. |
While it's not always
easy to anticipate standard climate changes and prepare for them,
an even more complex matter is determining whether an impending
storm is reality or merely a threat. Fortunately, the technology
is here (see the sidebar) to help keep the equipment moving as long
as possible–yet not get caught in a storm. More and more companies
of different sizes and in different locales, such as Brubacher Excavating
in Bowmansville, PA, and Larkin Excavating of Lansing, KS, are using
localized weather services to help plan the workweek and the workday.
"Thunderstorms in
summer and nor'easters in winter are two of our weather challenges,"
reports Roger Sauder, dispatch manager for Brubacher. "We have
300 employees, work in a 100-mile radius in the southeast quadrant
of Pennsylvania, and are able to work year-round, depending on the
weather."
He comments that if there's
going to be a thundershower in the middle of the day, the need is
to determine whether it's better to wrap up and go home or
find a way to wait it out for a half-hour or so and go to work again.
"If it's a large storm, we'll usually tell them to
come on in. With our weather service from Meteorlogix, we're
able to plan on which four days offer the best chance to keep on
working so we can get the land cleared, do all the rough cutting,
put the basins in for the ponds, and [do] other major earthwork,
piping, and storm sewer installation. We rough-in those courses,
and they do their own final landscaping."
Speaking from 17 years
of experience with the company, Sauder adds that the other benefits
to a localized weather service include notifying the concrete division
of overnight temperatures if there's a need to blanket its
work to keep it from freezing. "The primary benefit to us is
knowing whether the moisture will be at the level where we have
to shut down. We need to know whether we'll be getting one-tenth
of an inch in a short shower or a major wetting."
It also helps to know
when it's going to remain dry. "The major things for us
in excavating are the amount of rain and the speed of winds. We
have four water trucks for dust control. If we know that site is
going to have lots of winds and be hot and dry, we know we're
going to need more trucks on-site. As this country continues to
get more and more built up, dust control will be more and more needed
to keep the neighbors happy, to help us keep our reputation for
quality construction."
After a storm, Brubacher
uses its watering trucks to clean up any mud that has spilled out
in the street. "We use silt fencing to control runoff and encroachment
of areas adjacent to the site. Knowing the weather in greater detail
helps us better care for the job site and make more efficient use
of our equipment."
During winter, the contractor
will have 30-35 machines handling snow-removal projects. "During
a busy year, as much as 40% of winter activity is related to snow
removal, and the weather service helps us know how many machines
we'll need in the morning."
Though a smaller operation,
with some 40-50 employees, Larkin Excavating finds snow-removal
contracts an important element to its winter activity. Keith Knickerbocker,
assistant to operations, reports that their part of Kansas will
get four to five snowfalls in a given winter. "The snow work
is mainly in January and February, and it gives our equipment operators
work during an otherwise slow time. They're ready to plow anytime
a storm drops more than 2 inches of snow. The weather service helps
us decide when we need to get equipment ready to push snow, when
we need to yard the equipment, and how to maximize production during
the more active times of the year."
Cell-phone communication
likewise helps Larkin's field managers and equipment operators
be more quickly aware of changing local conditions and know when
there has been a change or a sudden need developed on the general
contractor's part. "We do a lot of one-to-one communication
with the general contractor. Things which can't be handled
from the office can be taken care of quickly and efficiently on
the site."
When Mother Nature
Needs a Pumping
Another challenge facing
many contractors is dealing with existing surface or underground
water or with all the new water from the storm. "Contractors
don't want their site filling up too much with water, but they
have to have somewhere to pump it to," observes Brad Fine,
director of marketing for Thompson Pump of Port Orange, FL. "One
reason for pumping is to control unwanted water because of what
gets washed around. With EPA, OSHA, and others watching the job
site, you don't want any hazardous material floating around.
"Here in Florida,
any road construction requires the entire site be dewatered. Then,
if laying pipe is part of that roadwork, continuous pumping has
to be done. Contractors need long-lived equipment to help keep their
crews working and the site open for work." Fine counsels operators
to be sure their pump of choice meets the flow requirements and
that it can handle any solids in the water being pumped. "If
the pump isn't large enough, solids, whether rocks, sticks,
or sewage, can jam up in the suction line or in the pump itself
and cause damage.
"Another concern,
especially in remote or continuous applications, is that the pump
have adequate fuel capacity for a long run." He also cautions,
"Pump users don't want to keep refueling, especially to
hard-to-reach locations."
Fine adds that the learning
curve with today's pumps is short, thanks to the gauges and
indicators that come with them. "Once the suction and discharge
system is set up correctly, and all check valves are opened or closed
as they should be, then the operation is mostly a matter of turning
the key. Visual maintenance checks, done at refueling or on a weekly
basis, take just a few minutes."
Fine points out that
recently developed is a compressor-assisted dry priming system that
is totally enclosed so there is no blow-by of any pumped material.
"This makes the pump perfect in terms of keeping the environment
and job site free of any hazardous material, including sewage. This
will help make it easier to abide by the NPDES Phase II regulations
coming next spring."
Getting Dry Ditches
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| Contractor
pumps are designed to operate in severe weather conditions.
These 6-in. pumps used for dewatering keep a job site dry for
surface work. |
Thompson Pump user Dan
Johnson, a salesman for Northern Dewatering Inc. in Rogers, MN,
reports that his firm's primary business is underground dewatering,
with bypassing–as in sewer system renovation–a close second.
"We're certified in six states and do about $5 million a year
in Texas, Minnesota, South Dakota, North Dakota, Iowa, and Wisconsin.
Our goal is to provide the excavation contractor with a dry ditch
so he can work below ground level."
Johnson has been in the
business for 35 years and notes that winters are particularly challenging.
"We recently participated in a $4 million project for the City
of Minneapolis, which consisted of a number of sewer repairs in
varying soil conditions, from dry, easy digging to swamps. Our job
was to dewater as needed for the general contractor. We moved all
over the place, drilling 40-foot wells and dewatering to 25 feet
below surface level. This enabled the contractor to dig to 25 feet
in midwinter with subzero temperatures and not let the job get stopped
by an unexpected flow."
Northern Dewatering's
main winter objective is to keep the water moving. "At no time
can we have water stop in a pipeline, else it freezes over. One
of the ways we do that is with rapid response. If something goes
wrong, we respond within a few minutes." He recalls the time
a well pump generator went down at 10 p.m., 20 mi. away in the northwest
quadrant of the city. "We had someone there within an hour.
He swapped generators and brought the failed one to the shop, where
we had it ready for service the next day."
Onsite replacement is
the fastest way to get the site running again. "Then the failed
item can be turned over to any of the 10 full-time mechanics working
in the relative comfort of the shop instead of enduring adverse
conditions in an attempt to make a field repair." As a rule,
if the repair is greater than 50% of the replacement cost, the company
selects replacement. "We have 400 Flygt, Prosser, Crown, and
submersible pumps, with over 100 Thompson engine-driven pumps. We
also have 50 generators of all brands and descriptions and all the
associated materials to build a complete pumping system."
Chill Factors Affect
Equipment
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| Ground
Heaters thaw ground and provide heat for curing concrete in
cold weather. |
But what about cold weather?
"Keeping the liquid moving becomes more important as it gets
colder," Johnson emphasizes. "We've had pumps working
at 40-below, with wind chills 60- to 70-below. Contrary to scientific
belief, wind chill does affect equipment. When it's windy, the heat
from the operating machine is dissipated more quickly. At times
we'll build a barricade of some kind. It's more for the workers
than for the machine, but both benefit."
Snow and blizzard conditions
stop operations. When they have to shut down, Northern Dewatering
immediately drains the equipment of all water. "This takes
10 to 15 minutes at shut down and another 10 to 15 minutes to get
it back in operation. But without that care, startup delay could
possibly be days because you're usually talking about ruptured cast-iron
parts, which take awhile to replace."
Bringing in Barges
Waterway dredging, whether
in Florida or Michigan, is a major excavation activity for some.
And in case of a storm or freeze-up, the question is how fast can
you get to shore. Ryan Horton, marketing manager for IMS Dredge
of Olathe, KS, explains, "A contractor on Lake Michigan owned
a competitor's barge that used anchor spuds instead of our
patented Starwheel Drive self-propulsion system. It takes a long
time to get to the shore when using spuds, unless you have a boat
to tug the dredge in. The contractor using the spud dredge almost
lost it when he could not get it into shore. He now owns one of
our Model 7012 Versi-Dredges. With our dredge you can easily disconnect
the discharge hose and paddle into shore before the weather gets
out of control."
Turning Up the Heat
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| If
severe weather hits, the Versi-Dredge can propel itself to shore
quickly and be removed with a single crane. |
Cold weather continues
to be particularly frustrating for contractors in northern climes,
but Jennifer Thompson, marketing manager for Ground Heaters Inc.
in Spring Lake, MI, has a simple solution: heat the project. "Our
Ground Heaters evenly deliver large amounts of BTUs over large areas,
so the entire concrete slab cures at a uniform temperature. The
equipment allows contractors to control the concrete curing process
rather than the process controlling them. It saves them a lot of
time and money."
She cites the example
of Nova Scotia contractor B.D. Stevens, who won contracts to built
two tilt-up concrete-wall schools. Working through the winter to
meet the August deadline was a necessity. The firm rented two E3000
Ground Heaters, and each one was set up to handle about 5,000 ft.2
of slab. Don Grant, B.D. Stevens construction manager, recalls,
"The first slab was a big success. We poured the 10,000—square
foot slab in the middle of January with temperatures dropping down
to -10º Celsius [15º Fahrenheit] that night, and it was
no problem. It was a perfect slab. With the Ground Heaters, the
slab was ready in 12 to 14 hours." For the two schools, 200
concrete panels were poured and cured.
Thompson adds, "The
contractor maintained control of his project. He stayed on schedule
and met his deadline." The Canadian contractor stood up to
the forces of nature and came away a winner.
So although Mother Nature
can't be controlled, those who pay attention to possible weather
problems, and make sure they prepare and care for their equipment,
help minimize the effect of even her worst temper tantrums–and
keep regulators happy.
Joseph Lynn Tilton
specializes in land and building issues.
GEC
- September/October 2002
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