Saturday, September 25, 2010

Manhole cleanup continues on Seventh Street

Crews are still working after today's manhole "problem" on Seventh Street between Avenue A and First Avenue...


Bob Arihood said...

Grieve , this all happened in the same location ,with the same multiple manhole covers launched , a few years ago .Back then gas leaked from a leaky gas main and an overheating , corroded electrical connection sparked and ignited the gas creating a low grade explosion on this stretch of 7th street .

Last time Con Ed pulled some new cable and repaired the electrical connections and some of the gas piping . But the gas piping has likely moved ever so slightly since because of all the traffic , freezing and thawing and the fact that the earth under the street is moving ever so slightly because leaking sewer mains are likely washing away soil.All of this movement stresses the gas piping and causes joints to open up and cracks to form and thus producing a gas leak .

Usually there are no hot electrical connections in the street and the areas around the connections are well enough ventilated that what gas does leak from the pipe escapes to the atmosphere never reaching an expolsive concentration in the air in the underground cavities around the electrical connections .

Occasionally though just the right concentration of gas in air in the underground electrical conduits is achieved and there is a hot connection or a spark also to ignite the gas : EXPLOSION . electrical

Anonymous said...

"today's manhole problem" sounds like something that would require a trip to the urologist.