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Delays, environmental
concerns, historic site preservation, equipment scheduling, manpower,
future projects, cost overruns, and public safety issues are just
a few of the characters in the nightmare of inaccurate site maps
and surveys.
The importance of survey
accuracy can't be stressed enough, remarks A. Ryan Pollard,
vice president of R.E. Cupp Construction in Fort Worth, TX. "Topographical
accuracy is very important. We verify all of our topographies before
breaking ground on a site and find, on average, that approximately
30% of the sites are not correct," Pollard
says. "And this percentage is even greater when aerial topographies
are used."
Other contractors agree
with Pollard on the problems of site inaccuracies and the importance
of survey accuracy. "The first things I look at are available
documents, plans, surveys—those kinds of things," says
Reuben M. Cansler, president of Cansler Construction Services Inc.
in Tampa, FL. Cansler thinks the site generally determines the project,
which includes zoning, size, location, road access, and availability
of utilities. Because site surveys form the basis of most bids,
it is imperative that the information be current and accurate. "Site
surveys are only as good as their accuracy," he says. "You
must rely on site-survey accuracy for boundary information, elevation
for grading, drainage, utilities, flood certification, and tree
locations."
Because surveys are usually
part of the contract specifications, one would think they provide
all the information needed to make an accurate bid. Most contractors,
however, say they could not depend on the accuracy of surveys and
maps when bidding on projects. So what should contractors do to
ensure accuracy? Dress in camouflage and sneak around in the dark
of night? Look over the shoulder of the civil engineer while he
works? Visit the archives at the county seat to find the historic
use of the property?
Take A Hike: Walking
the Site Adds Info and Gives Insight
Taking the time to visit and walk the site can provide additional
valuable insight for the project. It also gets you out of the office
for a couple of hours.
In addition to the studying
the survey, Cansler believes in the importance of walking the site.
"The survey will only show the site in question—not the
surrounding sites," he says. "The surrounding sites may
have a great influence on the proposed project." By walking
the site, you can note things that have changed since the original
survey was done and update your file on the project.
Also by walking the site,
you might encounter an "old-timer" who can fill you in
on the history of the neighborhood—how it has changed over
the years, what was on the lot years ago, where the riverbed was—and
even about the 100-year flood.
Hugh H. Willocks, president
of Willocks Construction Corporation in Hilo, HI, agrees with Cansler
about walking the property. "By observing the grass, the tree
line, the natural water runoff, the past uses for the land, that
kind of stuff, you can get a pretty good idea of the makeup of the
land." Grass and meadowland indicate soil, for example, while
shrubs indicate rockier land. Not only does walking the site allow
you to verify the accuracy of your information, but it also might
uncover problems that can be addressed before they slow down the
project.
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| The
bike system in action. You can see your site on-screen and deal
with any issues or problems in real time. |
With caverns, underground
lava tubes, ancient burial grounds, and hydroheads just waiting
to be "discovered," knowing the land and its previous
uses might well dictate the type of project developed and how it
is constructed. Willocks, who has been on the Big Island of Hawaii
for 30 years, still gets surprises. Recently his crew encountered
underground caverns during a public works project for a Hawaiian
Homes subdivision. "We cracked into caves in about four places,"
Willocks says. "We had to stop, cordon off the area, notify
the owner, and get an archaeologist."
Hawaii's underground
network of lava tubes is laced with remains and artifacts of ancient
Hawaiians. And sometimes—because of the cultural significance
of a discovery—the project has to stop until an archaeologist
can determine if there are ancestral remains or artifacts. "Even
before ‘grubbing,' you [must] have the historic officer
come out, and there is only one on the entire island," says
Willocks. Finding something—anything—can stop the project,
and stopping the project affects both the owner and the contractor.
"We had to reengineer
the project," says Willocks. "We used concrete fill, incorporated
a concrete cover, and lifted the roadway." They worked in this
case, but tons of concrete fill don't always fix the problem.
"In another area where we hit a cavern," he says, "we
couldn't seal it because of endangered species [living in the
cavern], so we designed a metal grate to secure entry yet allow
access for environmentalists."
"Excavation is one of the most costly divisions within the
entire building process," says Pollard. "If the land requires
a certain amount of cost to develop it, then that facility has to
pay for and absorb the cost. Therefore the site cost determines
which facilities can produce that kind of money."
Sometimes the project
has to fit the site. "For example, if a developer has sold
home sites based on the fact that a golf course is going to be built
in a specific area, then the golf course developer's challenge
is to find a way to make a golf course fit and work in the area
provided," explains Mindy Bieging, sales and marketing manager
for 3D Nature LLC in Arvada, CO. 3D develops software for landscaping.
Boring Logs Aren't
Always Boring; It Matters Where Borings Are Taken
After you have checked the survey, walked the site, visualized the
project, talked with the old timers, and reengineered the project
to fit the site, how else can you avoid delays due to mapping or
survey problems? Willocks says his company depends on the professionalism
of the engineers. "On large projects we really look at the
design civil engineers. We depend on input from the design engineers
and on the boring log to give us enough information to make an accurate
bid." He adds that it is crucial to compare the boring logs
to the plans and specifications. "It is important to see where
the borings were taken. I need to know how far apart [the borings
were and if] the samples [are] reflective of the total area of the
project." Generally the borings are the responsibility of the
property owner, but for site work done in advance of building, Willocks
notes, "it is important [that] the borings [be] taken right
underneath the heaviest part of the project." And the borings
must be representative of the lay of the project.
Willocks tells of a recent
street project where workers encountered a huge deposit of ash.
Because ash is unstable to build on, the project was stopped. This
is not only important from a weight standard but also for water
runoff. "It can be that there were borings taken, but they
missed the ash deposit," Willocks says. "Then the company
has to go back to the order." Had more bore samples been taken,
Willocks Construction might have made a more comprehensive bid.
Ash deposits presented
another problem for the street project, involving dry wells. For
this roadway, the dry wells were designed to be 6 ft. wide and 20
ft. deep. The design idea was to drain away water yet trap dirt
and sediment above the drain holes. "We ran into ash about
6 to 7 feet down," says Willocks. "After we sank our dry
wells, we got rain. More water came in through the ash than drained
away. The pressure from the water rushing into the dry wells caused
the covers to shoot up into the air!"
Willocks fixed the problem
by designing a concrete liner with drain holes. Where the dry well
encounters the ash area (from about the 7-ft. level to the 20-ft.
level), the liner is solid concrete, which is intended to prevent
incoming water. A 50-ft. plastic drain extends below the concrete
to suck off the water, leaving the dirt and rock to settle inside
a lip in the concrete.
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| A typical
bike package setup |
Willocks says this particular
project has 38 dry wells. "It cost a lot to redesign the project
when we hit the ash. The additional cost per dry well was between
$10,000 and $15,000." Those numbers would impact the bottom
line on any project. "You can control surface runoff with ditches
for diversion," says Willocks. "But underground streams
and hydroheads surface where they want."
Cansler also depends
on soil-boring reports, which provide information on the type of
soil below the grade, indicate the presence of any rock, and help
determine what type of building foundation may be used. "I
also depend on environmental reports to determine if any types of
pollution are present," he says.
With public works projects,
Willocks points out that the contract defines the specifications
for cutting, fill, pipe size, and so on. Although one would like
to think the information is inclusive, it is "not so,"
says Willocks. Problems still develop during the course of the projects.
Lasers Improve Mapping
Accuracy; New Technology Nips at Lasers' Heels
"Laser surveying has impacted excavation in a positive direction,"
says Pollard. "It allows you to be extremely accurate in almost
every given scenario. GPS [global positioning system] surveying
has had even a larger positive impact than laser surveying. We utilize
the [Trimble] SiteVision GPS devices, which give our operators real-time
grades."
Cansler agrees, "Laser
instruments have greatly impacted the surveying industry as well
as the whole construction industry. But I think GPS has had a greater
impact on surveying than the laser [has]."
Even the latest laser
technology, however, is losing out to advanced computer programming.
"Laser surveying is fairly obsolete compared to modern [real-time
kinetic] GPS and even robotic total stations," says Alan Williams,
vice president and head of software development at GeoLogic Computer
Systems (GCS). "However, we have a way to work with rotating
lasers in combination with GPS to still do 3D construction [with
vertical curves]." GCS software is compatible with a variety
of machinery and equipment.
When the contractor wants
to buy equipment to make his operation more efficient, he comes
to GCS, notes Williams. The company works with project engineers,
obtains data, and develops solutions. Using computers and software
is one way to ensure accuracy and maintain control of mapping.
"Many of our customers
will make their own topography maps of a site before or after bidding
on the project," says Williams. "They can then easily
compare that surface with the design surface to get an accurate
volume and picture of the dirt to be moved. It is very cheap and
quick today to just ‘re-topo' the site, which probably
is much more accurate than [what is] provided to the contractor."
Williams thinks surveyors
are often responsible for today's map errors. "On almost
every demo we do, we find some problem in the surveyors' stakes,
the string line, or the plans," he reports. "Once we found
an error in the hubs that a surveyor put in for a new airport. The
hubs had an error increasing from zero to 0.2-foot vertical error
and then back to zero again [probably because the surveyor moved
his total station]. The contractor says he was going with the hubs
anyway.
"We mentioned the
error several times more, but the contractor only called the surveyor
back when we said we needed a ‘Hold Harmless' agreement
or we would leave. The risk of a plane crash seemed too high if
the airport didn't demand that the job be done over. The surveyor
corrected the hubs, thus saving himself from a huge lawsuit if the
airport had been paved badly," says Williams.
Avoid Horror Stories
by Investing in Better Software for Site Maps
Horror stories develop because most engineers do not produce 3D
data in their electronic data files, suggests Pollard. "If
they do claim to produce it, it is usually not accurate."
3D Nature's Web
site brags, "We are terrain fanatics with varied backgrounds
in geology, object oriented programming and production animation
who have come together to create an insanely great program."
"3D Nature is a
software design company," says Bieging. It develops software
that can model, visualize, render, and animate terrain. "Many
of the people who use our products have sites that they have to
make a specific project work on," she points out. "We
feel site-map accuracy is vital. That is why many of our customers
use our line of products. We provide World Construction Set [WCS]
and Visual Nature Studio [VNS]. These are tools that allow companies
to visualize their projects prior to actual groundbreaking and earthmoving.
Both WCS and VNS can create very photorealistic and accurate site
maps."
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| Automated
data capture screen: The boxes show your NEZ location, and the
real-time display shows locations and the points already collected.
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Our products are directly
impacted [by laser surveying] because with greater data detail and
accuracy, our software products are able to produce much more accurate
maps and plans," Bieging says, stressing that it is very important
for the industry to understand that new tools and technologies are
available. "And although they may require a bit of investment
up front [both financial and in time to learn to use the new tools],
these new opportunities can pay for themselves many times over in
a very short period of time." And what kind of cost are we
talking about? 3D's WCS 6 is less than $1,000; VNS lists for $2,475.
Williams agrees with
Bieging about software being an investment rather than a cost. "When
the contractor wants to buy equipment to make his operation more
efficient," says Williams, "that's when we get involved.
GCS sells software and hardware for running construction equipment,
such as graders, dozers, trimmers, et cetera. We also sell equipment
to put on an all-terrain vehicle [or pickup] for rapid surveying.
We do not do the work ourselves anymore; we just sell and support
the equipment."
The GCS: Topo program is a rapid surveying system. With it, you
can survey up to 200 ac. and collect as many as 20,000 points in
one day. The system can even collect points as you drive. Think
of the time and money you can save with software that accurately
surveys in a fraction of the time required by conventional methods.
Even Experience Can't
Help Avoid Pitfalls
Experience doesn't always save a contractor from cost overruns.
Even having worked a project in the same area doesn't guarantee
accurate bids. In fact, all of the contractors interviewed had a
horror story to tell.
"We got burned on
a project in the home lots [the Hawaiian Homelands development],"
says Willocks. "We made an assumption based on other work we'd
done in the area. We assumed 50% of the structural base course.
The problem was that it didn't ‘screen out' to the
grade I needed."
Because the job was a
county project, Willocks Construction couldn't use it. "The
county wouldn't let us use it," says Willocks, "so
we had to go out and buy fill. There wasn't a lot we could
do; we can't afford to do test borings. We depend on accurate
information to help us make the right bid." These things become
another cost overrun to take to the accountant.
Training, Experience,
and Obeying the Law: Keys for Success
Accurate surveys, walking the site, laser technology, global positioning,
specialized software, and years of experience in the field all can
help avoid pitfalls on a project. Cansler adds one more: the importance
of the engineer. "I have worked with a number of different
civil engineers," he says. "You select the one that has
experience in the area and [with the] type of proposed project."
Pollard agrees with Cansler
about the importance of the engineer in the equation. "We have
working relationships with certain engineering firms. We rely very
heavily on boring reports."
The accuracy of the site
survey depends on the data available for the project area and the
tools for creating maps, according to Bieging. The engineer also
must help interpret the data and the information. "3D products
are used by engineers all over the world," Bieging says.
Even with the best maps;
the most accurate survey; and all of the experience, new computer
technology, and luck in the world, there's one more thing to
consider for successful completion of a project.
"We always do our
projects in accordance with the law," says Willocks. "We
follow all federal, state, and local laws. And that includes OSHA
[the Occupational Safety & Health Administration]. OSHA considers
all rock in Hawaii to be fractured rock. Because OSHA believes fractured
rock to be unstable, we must provide shoring and work at certain
angles." Only a contractor or an engineer familiar with the
area would understand what Willocks means.
"After all is said
and done," he maintains, "it still comes down to being
responsible, resourceful, and ready to do your homework." And
perhaps good luck helps too.
Maybe next time Willocks cracks an underground cavern, he'll
uncover pirate treasure.
Marsha DeClue, based
in St. Louis, MO, is a correspondent for several business journals.
GEC
- January/February 2004
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