Wednesday, November 22, 2006

Multiple manholes were from the past

QUESTION: Why are there so many manhole covers on Cheyenne Road? Between 8th Street and Nevada Avenue I’ve counted 23, which must set a record for such a short stretch (about a mile) of road.
- Marty Steiner
In the 1950s when that main was put in, the equipment was much less sophisticated than it is today and it was difficult to adjust to fluctuations in depth as they were trenching, said Utilities spokesman Steve Berry. “As they were excavating the hole for the line, the depth would drop off and they would do drop-manhole access to accommodate the stairstepping in those mains.” In addition, there were lateral mains coming into the main line as well as areas with two mains running down a street, which required extra manholes. The pipe used then — clay or steel — was less flexible than the PVC pipe used today. “They had to install more manholes because they were doing more connections because of this lack of flexibility,” Berry said.
Today, he said, sophisticated excavation techniques and flexible pipe adapt to changes in depth and require fewer manholes.

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