This paper discusses the City of Calgary, Alberta, Canada's experience with a 1200 mm concrete water feedermain rupture in January 2004. This
feedermain services a large pressure zone in the northeast sector of Calgary,
servicing approximately 100,000 people. Within a few hours, pressure problems
were reported throughout the pressure zone, and a major hospital was also
reporting severe pressure problems. Fortunately, the water pressure was
restored to the area within a few hours of the break. When the break was located, the extent
of the damage was discovered and it was obvious that the concrete
had severely deteriorated, and the pre-tensioned steel had virtually corroded
away. An
electromagnetic survey of the steel was done to determine if there were additional steel
wire breaks in the feedermain and three additional locations were discovered to need repairs. Several engineering investigations were undertaken to determine the cause of
the failure, including soil testing that indicated extremely high sulphate levels, which combined
with the groundwater conditions led to the deterioration of the concrete, and the
eventual corrosion of the steel. A
hydrophone device was installed in the feedermain to "listen" for additional wires
breaking. To the end of December 2004, 36 individual wire breaks have been
heard. Test pits combined with soil results will be used to determine the limits
of the replacement. Polyurethane-coated steel is being considered for the
replacement at an estimated cost of $2.5 million. Includes 8 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 620 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 06/17/2005 |
