Hi All,

Just a thought. Cold weather could be an explanation for some of the groups of water main breaks, but it's unlikely for most, IMO. I doubt that there's any Y2k connection, either.

But another possibility exists. A year or two ago, geologists (seismologists) described a type of earthquake that hadn't previously been recognized -- the slow earthquake. These quakes don't last seconds or minutes, they last days and weeks.

The amount of ground displacement can be as great as the normal "fast" quakes. Just about the only way to notice these quakes is through sensitive instruments -- or through breaks in underground pipes or misalignment of railroad tracks or roads.

Since the major effects of most quakes is in a relatively localized area, that would fit the pattern of the water main breaks.

We might watch for pipeline breaks near these areas (but ... they could be caused by overpressurization).

-- Dean -- from (almost) Duh Moyn (dtmiller@midiowa.net), February 06, 2000

Answers

Dean,

It's not just cold weather, but main breaks always increase during heavy cold snaps. Water mains are typically 3-5 feet below grade. They are typically made of either ductile iron or pvc pipe. In many cities, water systems are 50 years old or older. Age, pipe corrosion, and adjacent construction all play their part. Quality control during construction is often lacking.

Lets say you're joe developer and you've got to place utilities in your new subdivision. You hire a contractor to install the water mains and services, who may or may not be of good reputation. He lays the pipe fast and dirty, not properly backfilling and compacting the soil around the trench. Several years down the road, the main cracks due to lack of supporting soil at a joint. Some subdivisions are plauged by water main breaks from either poor construction or poor materials.

Things break as they get older. These breaks will increase as the system age increases. Tip your hat to the men who work on broken lines in sub-zero temps. It is not an easy or appreciated job.

-- trafficjam (road@construction.ahead), February 06, 2000.