Sewer

Sewers transport wastewater from buildings to treatment facilities. Sewers are pipelines that connect buildings to horizontal 'mains'. The sewer mains often connect to larger mains, and then to the wastewater treatment site. Vertical pipes, called manholes, connect the mains to the surface. Sewers are generally gravity powered, though pumps may be used if necessary.

Accidents

A sewer main in Guadalajara, Mexico had to be diverted down through a siphon to allow space for a metro railway to be built. The siphon allowed water and waste to pass, but not fumes. Petrol which spilled or leaked into the sewer on one side of the siphon was not able to easily escape to the safe exit on the other side, leading eventually to a build-up of fumes and an explosion killing hundreds. These explosions occurred in 1983 and most seriously on April 22, 1992.

Related Topics:
Guadalajara - Mexico - Siphon - 1983 - April 22 - 1992

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A trap is a U-shaped bend in a water conduit, as found on toilets, and wash basin outlets. Most of the time, traps are used to block the fumes, but not the waste and water.

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Lessons learned

The sewer siphon should have had a second siphon over the metro tunnel to allow fumes to get from one side to the other, as if the Metro tunnel were not there.

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