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Some explosions caused
by excavator, dozer, or backhoe blades striking buried utilities
are dramatic. Some are fatal. Sometimes it’s simply a plume
of earth and little stones that fly up and the workers watching
gasp a bit, cuss a bit, and wonder where they’d be now if it
had been worse. Frequently there are costs and damages that travel
far from the site, like cracks in glass. If it’s telephone
lines that are cut, businesses stop, emergency services may be unavailable,
and repairs can take more than a few minutes. If it’s a sewer
line broken, the health hazards may be significant, the air awfully
aromatic. If it’s a main water line, people suddenly realize
how important their good water is. If it’s an electric or gas
line, somebody almost always gets hurt, even killed. The ramifications
of broken utility lines are expansive and expensive. Damage doesn’t
have to happen, but when it does, people are always looking for
somebody to blame, and pay.
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Photo:
Vermeer Ring-OMatic
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| One
person can work a vacuum excavator, and the hole is smaller
than any backhoe can dig. |
For most people, the
very word excavation seems to imply a big hole in the ground, because
work for new highways and buildings can move thousands, even millions,
of yards of soil. Big excavators do the job magnificently. If the
sites are restricted, as in urban projects between buildings or
much of our residential work, compact excavators go in and do the
job. Vacuum excavation is most useful in applications where, in
the middle of a big site, there are hidden underground utilities.
Excavators don’t take up much space, just a line of pipe and
wire, perhaps less than a yard wide. You wouldn’t try to excavate
the whole area with vacuum excavation, but you would clear the way
around pipe and conduit so that the bigger excavating machines could
do their work without fear of striking dangerous obstacles.
Find the Rules and
Follow Them
There are local regulations about excavation where utilities may
be present. They vary a little from state to state, but the central
theme is common to all: Do the job right, without endangering people
or property. The regulations/statutes/acts have names like Underground
Utility Damage Prevention Act (Virginia), Underground Utility Facilities
Damage Prevention Act (Illinois), and Underground Facility Damage
Prevention and Safety Act (Florida). They are not all lengthy pieces
of complicated prose. They are easy to read and all of us involved
in excavation should read them.
What are underground
utility facilities? Illinois says they include wires, ducts, fiber-optic
cable, conduits, pipes, sewers, and cables, and their connected
appurtenances, installed beneath the surface of the ground by a
public utility or by a municipally owned or mutually owned utility
providing a similar utility service; or by a pipeline entity transporting
gases, crude oil, petroleum products, or other hydrocarbon materials
within the state; or by a telecommunications carrier. There are
a few other definitions in the act, related to relevant legal definitions
of companies and organizations providing service, but you see the
principal idea. The definitions are all very legal-sounding and
that in itself should warn us. We shouldn’t spend too much
time trying to find out the party affiliation, family history, or
religious persuasion of the owners of the underground obstacles.
Just don’t cut or break them, regardless of who owns them or
put them there in the first place. It’s like those signs in
stores where they sell fine china: You break it, you pay for it.
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Photo:
Amerivac
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| Vacuum
excavation is a compact operation. The equipment requires little
space to use. |
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Photo:
Vacmasters
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| Two
workers use air to dif a hole and remove the spoils. |
You can tell the topics
considered relevant by the State of Virginia, because it gives careful
definitions of these words used in its act: abandoned, contract
locator, damage, demolition, designer, emergency, excavation, extraordinary
circumstances, notification center, notify, notice and notification,
operator, person (more on that one in a minute), soft digging, special
project notice, utility line, willful, and working day. In the State
of Virginia’s act, person includes any individual; operator;
firm; joint venture; partnership; corporation; association; or municipality
or other political subdivision, governmental unit, department, or
agency. It is also synonymous with trustee, receiver, assignee,
or personal representative thereof. It seems unlikely, then, that
anybody in any state is going to get away with careless digging.
Our biggest help may be vacuum excavation.
There are still many
cities that do not have their own vacuum excavation equipment. Smaller
communities cannot afford the necessary equipment and rely on their
local utilities to do the digging around the buried lines, or they
do the work manually. “One call is so helpful,” says Wilbur
Wallace, the public works engineer for our own city, Glendive, MT.
We have less than 5,000 people and the city is always low on funds
and uses a lot of outdated equipment. “We let the cable, telephone,
gas, or electric company find the buried utilities and let them
do the exposing. It means we don’t have to spend the money
on equipment or labor. And sometimes we dig around them with shovels.”
Some immediate reactions were that such a policy may delay a project
contrary to the city’s wishes or remove control of the safe
excavation out of the hands of the communities’ representatives.
Larger cities are little different. “The City of Alexandria,
Louisiana, does not do vacuum excavation and makes sure the correct
details are in the contractors’ contracts for work around buried
utilities,” notes James Branch, a professional engineer there.
It’s not just the municipalities that get others to do the
delicate work.
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Photo:
McLaughlin Boring Systems
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| With
its small footprint, vacuum extraction is ideal for use in residential
settings. |
“We get the utilities
to do that kind of work before we go in with our excavator,”
advises Mrs. Dean Fairchild, part owner of DD Excavation in Midvale,
ID. “We’re a small contracting company and could probably
not justify the investment for the small amount of that work required
in this area.” In Gladstone, MO, Bill Ballard of W.R. Ballard
Excavating says there is one company in his area that has the vacuum
excavation equipment and will contract to do the work. His own company
has not invested in the necessary machinery and he sees only rare
applications, because he does few jobs that involve utility work
or easements. Based in Sand Springs, OK, Carter Excavating Inc.
(owned by Jerry Carter) is a much larger excavation contractor.
The company has between 110 and 180 employees, depending on the
projects under way, and much of it is highway work, ground preparation
for new building complexes, and applications of that size. They
handle their own excavation around buried utilities; it’s part
of the day’s work, one of many jobs in a big company’s
portfolio. Using a shovel is still popular with many contractors
and municipalities. “We call first to see if there are buried
utilities at the job site and locate their exact position,”
explains Shirley Baughman of Baughman Trucking & Excavating
in Sheldon, WI. “If we have to dig carefully around the hidden
obstacles, we use shovels and do it manually. It has not been a
problem.”
We have the impression
that vacuum excavation could be another market into which grading
and excavation contractors could go profitably in some territories,
if they have not done so already. We are cautioned, however, by
several contractors that you can do a lot of excavation and grading
without coming anywhere near a buried utility. You should investigate
the potential for vacuum excavation work and purchase or lease accordingly.
It depends on where you live and work. In Wakefield, MA, Peter Cameron
is owner of Rental Equipment Co. “We have no demand for vacuum
excavation equipment,” says Cameron. “In these parts you
rarely see that technique. We have many rocks in the soil and I’m
not sure if vacuum excavation could handle that.”
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Photo:
PacificTek
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| Remote
control of the operation has found supporters for some applications. |
Techniques and Applications
Vacuum excavation to uncover buried and hidden utilities—some
contractors use water and air, some use only air—is similar
to vacuum cleaning the living room. The person doing the actual
excavating holds a hose that sucks up the debris. It is a non-destructive
technique. It doesn’t cut, stab, or hammer. “This method
is even safer than hand digging,” asserts Tab Siegrist of Vactor
Manufacturing. “With manual digging there is still a chance
the worker may strike a line and the costs of a strike are not only
direct, like property damage, loss time at the site, fines, medical
bills, and equipment damage. The indirect costs may be increased
insurance, administration costs, legal fees, judgments, delays in
the project, and damage to the image of your company.” Hydroexcavation
can cope with tough soil conditions like rock and clay, as well
as frozen ground (with heated water). Several contractors commented
that some incidents of line damage were caused by the fact that
as-built drawings were non-existent or inaccurate. “Under those
circumstances you don’t tell your backhoe operator to plunge
down and see if there’s anything there,” warns Todd Richards,
a contractor in Bend, OR. One of the first steps after ascertaining
that there are hidden utilities below is to call somebody to let
them know that you have work to do around their utilities. The One
Call service is invaluable. It has different names in different
states and communities. One excellent fact we learned was that everybody
we spoke with always calls that number first.
In Greenville, SC, hydroexcavation
was needed to benefit the landscape and solve runoff problems at
a residence. When the original house was built, there was only minimal
landscaping. When the second owners took occupancy, they decided
to improve everything and added a raised berm, attractive beds,
flowers, and plants in front of the circular driveway. They cut
the grass with a reel mower. It looked wonderful … until water
started collecting at the edge of the lawn and in front of the house.
Garden Vistas, a local landscape and yard maintenance company, looked
at the problem. “The existing French drain was useless because
the conduit used to filter off the water was too small,” observes
Bob Moffett of Garden Vistas.
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Photo:
Ditch Witch
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| It
is surprising how little space is needed for vacuum excavation. |
“We suggested removing
the existing drain system and installing surface drains and a 4-inch
connecting line that would handle the runoff.” To achieve this
Moffett needed a tunnel (6 inches in diameter and 13 feet long)
to go under the double entry pad of the house. He got his plan approved,
made the right call to the appropriate utilities, and used a vaXcavator
from McLaughlin Boring Systems to cut the starting trench. That
was 12 inches wide, 12 inches deep, and 7 feet long. The job took
two hours, with no damage to the landscape. The first 6 feet took
only 10 minutes, with the rest of the time spent collecting concrete,
wooden two-by-fours, insulation, and unused brick from the original
construction of the residence. After the tunnel was made, a vaXcavator
pavement sweeper cleaned up the site to the owner’s delight.
The cold, damp winters
in Woodridge, IL, west of Chicago, can damage water valve boxes.
Crews used to do the maintenance with backhoes, or manually, but
that was expensive and there was frequently a need for restoration
of damaged property for the residents. Now they use vacuum excavation.
The process takes about 15 minutes for each unit and officials say
they have reduced their costs for labor and repairs significantly.
“We have been successful
with applications as diverse as mud removal, cleaning treatment
plants for local authorities, and manhole cleanouts,” notes
Don Buckner, president of Vac-Tron. “Our equipment has also
vacuumed down retention ponds, cleaned storm drains, cleaned around
valve boxes and meter boxes, cleaned up emergency road spills, and
even vacuumed dry sand and rocks.”
Water or Air?
Vacuum excavation systems use mostly water or totally air; the manufacturers
of each style generally like one or the other. We must insert here
that neither “side” says the other doesn’t work.
Everybody who has used vacuum excavation or who makes the equipment
to do it will argue with conviction about its advantages for contractors.
Your choice of system—just like your choice for loaders, excavators,
graders, or personal vehicles—is up to you. It has become a
question of preference, not ability.
“The Vacmasters
System 4000 offers utilities and utility contractors the ability
to pothole using supersonic air in any kind of soil, no matter how
hard, wet, sunbaked, or compact—even when there’s ground
frost,” advises Roger Kirwan, vice president of marketing at
Vacmasters (a division of Barone Inc.). “This system’s
ability to let the contractor choose air rather than water when
potholing means the job gets completed more quickly, in just seven
to eight minutes in most soils. It’s more efficient because
the spoils stay dry for backfilling, and it can be more economical
because your mud hauling and disposal costs are eliminated. We also
believe that this air-based technique is safer because air will
not damage utilities and it is non-conductive.” Kirwan adds
that air-vacuum excavation is Department of Transportation–friendly
and will not damage the road base. On the technical side, a John
Deere 150-horsepower diesel engine powers all the systems (including
compressor, vacuum, and high-pressure water). It has a self-purging
filtration system, selectable water or air digging, remote operation
up to 200 feet away, a fast-acting interceptor canister, and an
enclosed powerhead.
In the Vactor HXX (engineered
with advice from excavation contractors, says the manufacturer),
pressurized water breaks apart the soil and a high-flow vacuum removes
it. “There is no damage or disruption of the lines,” notes
Siegrist for Vactor. Successful uses of the HXX have included excavation
at residential sites, slot trenching, installation of poles and
signs, potholing, directional drilling, water line repair, and location
of underground pipe and other utilities. The machine will give the
user up to seven hours of continuous operation with the onboard
water. “Lower water flow results in less operator fatigue and
a cleaner, more accurate digging process,” Siegrist adds. “Add
to that the benefit that the fan’s 8,000-cubic-foot-per-minute
airflow is more than double that of some competitors.” The
debris tank holds 12 cubic yards and the stainless steel water tank
(single cell) has a capacity of 1,300 gallons.
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Photo:
Pacific Tek
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| While
standard excavation can leave gaping holes in streets and sidewalks,
a vacuum operation has minimal impact on the job site. |
Partnering With Other
Equipment
As vacuum excavation manages underground obstacles and their safe
exposure, it is not surprising that two companies well known in
the field of underground construction should produce excavation
equipment to match their drilling machines and tools. Ditch Witch
and Vermeer are probably the best-known makers of directional drills
and associated products in the United States. Ditch Witch offers
a group of vacuum excavation products, known as the FX30 series.
There is also the FX60, the big brother in the family. The first
FX30 is a 500-gallon system and claims to be the quietest on the
market today. It has been used successfully for residential work
and Ditch Witch reports that municipalities and rental centers like
its compact operation, too. That low noise level (73 decibel-amps)
is also welcomed by the operator. The next size up in the series
is the 800-gallon model with its powerful two-lobe blower that develops
500 cfm and 15 inches of mercury for efficient suction. The FX60
is the largest of the group. Its dry weight is 11,230 pounds and,
with full tanks, it weighs 24,880 pounds. The tank has a 1,200-gallon
capacity. The vacuum system has a belt drive, the hydraulic system
works at 2,500 psi, and the maximum pressure for the water system
is 3,500 psi. It can be trailer mounted or be used in a loose configuration.
A few months ago, Vermeer
and Ring-O-Matic, two national leaders in underground construction
and vacuum excavation, announced that they were merging production
and distribution. For 2004, Ring-O-Matic introduced a handheld wireless
remote-control hydraulic boom for their hydroexcavation equipment.
With that, the operator can retract or extend the length of the
boom, and raise or lower the height of the boom. It’s an advance
that has been particularly helpful for crews working at multiple
utility locations, such as the holes for installation of streetlights
or vacuuming catch basins.
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Photo:
Vactor
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| Vacuum
excavation on residential property has become especially popular. |
The E550 and E900 Evacuator
vacuum excavation systems from Vermeer—the model numbers indicate
the capacity in gallons of the spoil tanks—can deliver 1,000
cfm. They were designed to assist contractors in horizontal directional
drilling, for companies specializing in locating utilities, and
for public works and municipal applications. In the excavation mode,
the units will expose buried utility lines (or other underground
obstacles), and in the vacuum-only mode, they will perform a good
cleanup job of non-hazardous materials at your job site. Both models
offer a patented multinozzle wand system and automatic shutdown
switches for the high-pressure pump when the level of the water
tank is low. To make removing spoil and cleaning the tank easy for
the operator, there is a full-swing door, while mounting of the
system can be on a skid or trailer, depending on the preference
of the customer.
Companies or equipment
names we should mention in this field are Keith Huber, Amerivac,
Vactor, Miller Pipeline, Vacuum Source (now merged with McLaughlin
Boring Systems), Ditch Witch, PacificTek, Vac-Tron, Vermeer and
Ring-O-Matic, MBW, VacStar, Vacmasters, Super Products, Vac-Tron,
Utilivac, GapVax, Versa-Vac, Vector, Vac-Con, Aquatech, and Hi-Vac.
Not surprisingly, there’s plenty of “vac” in that
collection. It pays to look at all the specifications of equipment.
From them you can deduce what is considered important structurally
and what you should be looking for in the equipment you purchase
or lease. The most commonly emphasized points seem to be the size
of the tanks (for water and spoils) and the actual power of the
vacuum. What is best for your applications is not necessarily the
biggest machine; it is the one that handles your work most efficiently
and cost-effectively.
The subsurface infrastructure
of North America is growing rapidly. As cities spread out and suburbs
increase, the utilities must go with them. Most of the newer lines
are underground. Unfortunately, the as-built drawings for some earlier
expansions are unavailable or inaccurate and contractors are becoming
more aware of the challenges offered by buried obstacles to their
excavation. Vacuum excavation is not a passing fancy, a solution
that will go away quickly. (It’s been around for about 50 years
already.) It seems to be gaining popularity with both private contractors
and public works professionals as a method to continue a tradition
of safe excavation in any community, whatever is hidden below the
surface.
Paul Hull writes on
construction and environmental topics for several international
magazines.
GEC
- January/February 2005
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