DEDICATED
TO STRATEGIC BUSINESS
ISSUES FACING OWNERS, DEVELOPERS,
& THE Project
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DEDICATED
TO STRATEGIC BUSINESS
ISSUES FACING OWNERS, DEVELOPERS,
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Home | 2004 Edition |
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From the Editor-in-Chief COLUMNS
Finance Order
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Pallet Barrier System by John G. Everett Floods have plagued mankind since the dawn of civilization. Countless lives have been lost. Millions of buildings have been damaged or destroyed. Entire cities have been wiped out. According to one widely quoted source, a great flood once covered the entire Earth, and only a single boat with two of each type of animal was spared.
In locations where floods are rare or have never happened, residents are less well prepared. Residents are often required to evacuate their homes and businesses, leaving every-thing they own at the mercy of the rising water. There are a variety of temporary flood protection products on the market: sandbags, sand gabion barriers, rigid steel and concrete systems, plastic tubes filled with air or water, and other plastic membrane systems. Each has its own advantages and disadvantages, but generally, the most effective barriers are very expensive and/or require heavy construction equipment, and in some cases significant construction experience to build. By far, the most common method of building temporary flood barriers is the sandbag. Success is dependent on the availability of an adequate supply of bags, sand, shovels, transportation equipment, manpower with sufficient training and experience to do the job properly, and time. Pallet Barrier System A simple but effective innovation is now available for protection against flood water up to 1.80 meters (6 ft) deep. There are three main components to the Pallet Barrier system: the metal support, the pallet, and the geomembrane. The heart of the Pallet Barrier system is the folding metal support. It is fabricated from sheet steel (1.5 mm = 0.06 in thick). The Pallet Support EUR 95 model is intended to be used when the water depth is up to 95 cm (3.1 ft). Each support weighs 8.3 kg (18 lb) and can easily be handled by one person. It is anchored through friction between the bottom of the support and the ground surface for silt, sand, gravel, and asphalt. Additional anchor pins may be necessary for grass, clay, and muddy ground. The Pallet Support EUR 180 model is an extension set to be used with the EUR 95 model described above. This model is for use for water depth up to 1.8 meters (6 feet) with use of two EUR-pallets. The pallet is a standard wooden EUR-pallet used throughout Europe for transportation and storage. The inexpensive pallets are designed to withstand heavy loads and are available in large quantities on short notice. Dimensions are: 1200 mm x 800 mm x 150 mm (47 in x 32 in x 6 in) (length x width x height). Each pallet weighs approximately 20 kg (44 lb). In some countries, such as Australia and the United States, the standard pallet size is different, so the support configuration must be modified. The geomembrane is a waterproof sheet material made of reinforced high density polyethylene coated with light density polyethylene plastic. The width is 2.7 meters (9 ft). It is supp-lied in rolls of 50 meters (160 ft). There are also a few miscellaneous components used to connect the supports to each other, hold the geomembrane on the pallet, seal between pallets, and anchor to the ground if necessary. The whole system can be seen in the figure on the preceding page. The major advantage of the system is its simplicity. Assembly and
disassembly are quick and easy. No heavy machines are required for
erecting All components are reusable. After the flood subsides, the barrier can be taken down and stored in preparation for the inevitable next flood. The Pallet Barrier system is assembled by inclining each pallet against its supports so they form a line in the desired direction. The barrier can follow ground contours vertically and horizontally. For 90 degree turns, a triangular module is available which is assembled at the outer or inner corner. One person can easily assemble 200 to 300 meters (650 to 1,000 ft) in a day. The next step is to unroll the geomembrane and lay it against the inclined pallets and the ground surface. Some leakage may occur between the membrane and the ground. This can be reduced by placing small amounts of soil or sand along the bottom edge of the membrane. The edge of the membrane can also be pushed into the ground to obtain better sealing. Leaking water is pumped away by conventional means. Ideally, the Pallet Barrier will be installed before the flood arrives. However, if the flood is unexpected, the barrier can be installed in standing water. Once the barrier is complete, the water can be pumped from the protected side back to the river or lake side. Pallet supports and membrane are intended to be stored locally. Pallets can be purchased or rented when there is warning of rising water. In the case of summer flooding due to heavy rain, contracts with local companies supplying pallets may be sufficient to insure their availability. One of three support and pallet configurations can be selected
de-pending on the expected height of the water. For expected water depth For expected water depth up to 95 cm (3.1 ft), the pallet is installed so the shorter dimension (800 mm = 2.6 ft) is parallel to the ground. Support spacing is closer, so more material will be required (one pallet and one EUR 95 support for each 0.8 meters (2.6 ft) of barrier). For expected water depth up to 1.8 meters (6 ft), the EUR 180 support is used in conjunction with the EUR 95 support. Two pallets are placed end-to-end on the combined supports. This will require one of each type of support and two pallets for each 0.8 meters (2.6 ft) of barrier. The Pallet Barrier was developed by Mr. Sten-Magnus Kullberg, a civil engineer from Linkoping, Sweden. The idea for the Pallet Barrier originated in 1995 when Mr. Kullberg tried to find a solution to severe floods in Sweden and Norway. After testing and small scale trials, the Pallet Barrier has proven itself in several large scale, high profile applications in Sweden, Holland, Germany, France, England, Italy and Australia. Mr. Kullberg and the Pallet Barrier have won several awards in Europe and the United States. For further information and dramatic images, visit: www.geodesign.se. John G. Everett is an Assistant Professor of Civil and Environmental
Engineering at the University
© Copyright 2004. All rights reserved.
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In
locations where floods are common, permanent barriers are sometimes
built to hold back the flood. Examples include berms, levees,
embankments, dikes, dams and seawalls. These barriers are expensive, a
nuisance except during an actual flood, and frequently not high enough
to serve their intended function when the flood is higher than usual.
In many
locations, residents build temporary barriers to hold back the water.
The height and length of the required barrier is a function of the local
topography and the ultimate height of the flood water. Residents and
emergency crews are limited in how fast they can erect the barrier by
how quickly they can get the required materials to the right place, and
by their own skill and endurance. This is usually a race against the
clock in miserable weather.