The deadly waters came in the middle of the night, in winter. On February 16 and 17, 1962, Hamburg was hit by its worst post-war disaster. The city-state’s outmoded
network of narrow, hand-built earthen dikes failed to hold back a storm surge, resulting in the deaths of 315 people and the flooding of much of the proud Hanseatic town,
including the entire central neighborhood of Wilhelmsburg.
Today, a flood of the same magnitude would not cause such devastation. A whole range of improvements has been implemented to ensure that the city is much better
protected from the possibility of flooding by the River Elbe, or even another storm surge coming up the river from the North Sea. The piecemeal arrangement of handmade
dikes, constructed by various organizations, has been replaced by a system of professionally designed and constructed dikes
– stretching 78 kilometers, plus 25 kilometers of protective walls – maintained by the city administration.
The dikes themselves have risen from an average height of 5.7 meters above sea level to a height of 8 to 8.5 meters, with a corresponding increase in width, and of distance
from trees and houses. Along with a modern earlywarning system, city officials have set up a system of special streets along the dikes, in which Trelleborg plays a part.
Since 1991, Trelleborg has supplied about 266,000 square meters of synthetic rubber membranes used to help protect the roads that run along the inner embankments of
some dikes. Most of the surface of these dikes is protected by a thick layer of clay, which prevents erosion of the dikes by floodwaters. But where streets have been built
into the side of a dike, about halfway between the top and the base, the layer of clay in a one-to-two-meter strip running parallel to the street is very thin.
The EPDM and Butyl membranes produced by Trelleborg’s Rubber Membranes Division are laid down along this strip to keep water from seeping in and undermining the
dike.
“The membranes are a building block in the overall construction of the dike,” says a Hamburg city official. “They contribute to the protection of the street.”
In one of the latest in a series of measures being taken to improve the security of the dike system, Trelleborg has supplied membranes for use along a runway for the Airbus
A-380 aircraft, scheduled to be built at the Airbus facility in the Hamburg neighborhood of Finkenwerder. “This will help ensure that the A-380 doesn’t get its feet wet,” says
Michael Hesse, Trelleborg’s marketing manager for Germany.
Hesse says he thinks the membranes could be useful in other cities where flooding is a problem, from German cities along the Elbe to New Orleans, where a storm surge
and floodwaters from hurricane Katrina in August, 2005, undermined dikes (locally called “levees”) and caused the flooding of 75 percent of the city. Given general
expectations that global warming will increase the frequency of severe storms and cause sea levels to rise, Hesse says that taking protective measures is more important
than ever. “In some places people wait too long, until something happens,” says Hesse.
HOW MEMBRANES WORK: They form a barrier between moisture or water and structures that could be harmed by the moisture, preventing any transfer of moisture to the
structures.
ORIGIN: Butyl membranes were developed in the USA in the late 1950s, and laid down during home construction to prevent moisture from entering the basement.
DURABILITY: Membranes used in Sweden have lasted for 50 years.
ENVIRONMENTAL COMPATIBILITY: Butyl membranes do not leach any chemicals into the soil.
EXTERNAL USE OF EARTHEN CONSTRUCTIONS: The membranes are used on flat roofs.
