A key component of any solution
involves trenchless technologies:
when, where and which method
The project team consulted
contractors and considered
three trenchless approaches:
auger boring; horizontal
directional drilling (HDD); and
microtunneling. Here’s a closer
look at the tunneling options
and how they compared:
• Auger boring was deemed
infeasible for two main reasons:
spatial requirements made it
impossible to avoid entering
safety areas or otherwise
disrupting airport operations.
The soft soil raised accuracy
concerns and would have
limited runs to no more than
• HDD was determined to be
feasible only for shorter runs.
On the plus side, the method
generally is the least expensive
for trenchless installations and
would not intrude into safety
areas and other potential
trouble spots. But several
negatives could not be overcome, including those
related to constant grade requirements and an
inability to move accurately through the soft soils.
Such complications could result in dips in the fuel
lines when passing under runways.
• Microtunneling, the most expensive of the three
options, proved to be the only feasible alternative
for the project’s longer runs. While its spatial needs
were significant, tunneling activities could be moved
outside safety areas to prevent disrupting airport
operations. Also advantageous: Fuel lines and
electrical conduit could be carried in a single,
large casing; and pipes could follow a precise,
laser-guided path through the soft soils, even
spanning long distances.
DAN EEKHOFF, email@example.com, is a
project manager in the Aviation Group at
Burns & McDonnell.
A smart approach informed the final project layout for replacing pipelines.
© Herrenknecht AG
Microtunneling provided a feasible solution to challenges posed by operations and soil.