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The truck above is pulling a high power pressure washer/ steamer that is used to cut and melt ice in blocked culverts, catch basins and storm sewers.

2004 Spring Thaw

What were the city crews up to?

Because of deeper than average frost depths in Duluth, city crews have spent many hours this spring clearing out storm sewers blocked by ice. You may have seen something like this along your street:


This water isn't ending up on the street because the storm sewers are full but because they are blocked. 2003 frost depths in Duluth were at least 60" deep (see map) because of a lack of snow cover. Trickles of thawing water freeze in underground pipes causing the blockages.

Another cause for water on the roadways this spring has been broken water lines, again due to the deep frost causing pipes to shift and crack. In these cases, crews need to identify where the break is so the water can be shut down and the pipe repaired.

The frost is also resposible for a larger than average number of frozen water pipes to individual residences. Sanitary sewer lines, buried deeper than water pipes with warm water flowing through them, have seen few freezing problems.

If pressure and steam aren't enough to clear the obstruction, the Vactor truck is used.This truck is both used for vacuuming debris from catch basins and also for dislodging debris from inside pipes. To dislodge ice and debris, several jets of water are used to propel a nozzle forward, with one jet of water on the end for blasting out debris. The water used in this operation is not heated (although the trucks are often filled with hot water from the steam plant), so it isn't always as effective as the pressure washer
.