Easy access to a parking area just off of Steese Highway. There
is a information board about the Alaskan pipeline located at the
listed coordinates.
NOTE: The Alyeska Pipeline is constantly changing with new
technology, upgrades, etc. Since Alyeska has many employees, there
will always be someone who may notice a mistake. Please feel free
to email with your concerns and let me know what information is
incorrect and I will apply that to the Earth Cache listing.
The Alyeska is one of the largest pipelines in the world. Built
in the 1970's after oil was discovered at Prudhoe Bay (1968), the
48 inch diameter, 800-mile pipeline links Prudhoe Bay on the Artic
Ocean with the terminal at Valdez, the northernmost ice-free port
in the Western Hemisphere. The flow from this pipeline accounts for
roughly 20 percent of the U.S. oil production annually.
Day trips by van or by air to Prudhoe Bay are available from
Fairbanks, or you can drive the rugged Dalton Highway 487 miles to
Deadhorse at Prudhoe Bay, but access to the Prudhoe Bay oilfield
complex is available only through commercial tour operators.
The pipeline is buried for less than half its length, where the
ground is well drained gravel or solid rock, and thawing is no
problem. Wherever the warm oil would cause thawing of the icy soil
(which could cause sinking or heaving) the pipeline, which cost
about $8 billion to build, sits on top of 78,000 above ground
supporters spaced 60 feet apart. The sections above ground are
insulated and covered. The pipe is raised high enough off the
ground in places to span rivers or allow wildlife to cross under
the pipeline.
There were originally twelve pump stations and many valves
controlling the flow of oil. Currently, two pump stations are not
operating, and two are on idle status, leaving pumps
1,2,4,5,7,9,11, and 12 operating. The entire system is operated
from the operations center located in Valdez, but can also be
operated independently at each pump station. The 48 inch diameter
pipe is made of specially coated material covered with zinc anodes
to ward off corrosion. More than 800 crossings of rivers and
streams are made between Prudhoe Bay and Valdez.
Alyeska built the 360-mile haul road, now known as the Dalton
Highway, from the Yukon River to Prudhoe Bay, for $150 million to
supply the oil facilities on the North Slope. The pipeline bridge
across the Yukon River is the only span across that river in
Alaska.
The pipeline was built above ground in areas where
thaw-sensitive permafrost exists. However, where the line must be
buried, such as highway crossings or avalanche-prone areas, the
pipe is encased in an insulated, refrigerated ditch. Nearby
refrigeration plants pump cold brine through 6 inch pipes which
absorb heat and keep the soil cooled. Other areas of burial are
either conventional covered ditches or unrefrigerated but insulated
ditches, depending on the sensitivity of the surrounding soil. Oil
emerges from the ground at 180 F and travels through the pipeline
at 120 F. In some elevated portions, heat conduction from the oil
through the Vertical Support Member (VSM) would melt the permafrost
in which the VSMs are embedded. This would cause the pipeline to
sink and possibly cause damage. To prevent this from occuring,
these portions of the pipeline include heat exchangers atop each
VSM, passively cooled by convection to the air. Each heat exchanger
is thermally coupled by a heat pipe to the base of the VTM. Running
through the VSM, the heat pipe transports heat from the VTM base to
the heat exchanger. Since ammonia, the working fluid in heat pipes,
has a boiling point lower than the permafrost, the heat pipe works
throughout the year, even during the coldest winter nights. This
relatively simple convection cooling system is thought by TAPS
engineers and maintainers to be the greatest technological
innovation.
Another innovation with the pipeline is the zig-zag
configuration aboveground. Since pipe shifts around far more easily
above ground than its does when buried, the zig-zag path of the
pipeline allows the pipe to move somewhat from side to side and
lengthwise. This movement may be caused by earthquakes or by
temperature-related expasion and contraction. The VSMs also include
special "shoes" to allow for this horizontal or lateral movement,
and crushable blocks to absorb sudden shocks from earthquakes,
avalanches, or vehicles.
To log this EarthCache, email me the following answers. Please
post picture of you with GPS in hand to get credit. Pictures not
posted within seven days will have log deleted.
1. How many mountain ranges does the pipeline cross?
2. How much of the pipeline is buried?
3. How high is the pipeline above the ground near the
coordinates?
| Cav Scout has earned GSA's highest
level |
 |
Do not log this
EC unless you have answered the questions and have a picture ready
to post! Logs with no photo of the actual cacher (human face
included) logging the find or failure to answer questions or
negative comments will result in a log deletion without notice.
Exceptions will be considered if you contact me first (I realize
sometimes we forget our cameras or the batteries die). You must
post a photo at the time of logging your find. If your picture is
not ready then wait until you have a photo.
Sources of
information for the EarthCache quoted from the Alaska Geology
Survey. I am by no means a geologist. I use books, internet, and
ask questions about geology just like 99.9 percent of the
geocachers who create these great Earth Caches. I enjoy Earth
Caches and want people to get out and see what I see every time I
go and explore this great place we live in.