Often it is the little things that matter.

I was at a public meeting where someone complained that the street drains for the sewer system smelled horribly. He said that he could never remember it being so bad and asked what had happened. Of course the city officials had no idea.

Although I am not sure of the exact reason in his particular case, often smelly sewer drains are the result of a particular method of street repair meeting up with an antiquated sewer system. In Rochester our sewers combine rain and snow runoff with waste water from the buildings.  This is an outdated model which many older cities still have.

Recently we have been using a street repair method called mill and fill.  It involves applying oil to the street surface, and then spreading a layer of loose stones.  As cars drive over the stones, some are pushed down into the street making a new surface. Others are pushed to the edge of the road. Unfortunately, the city roads have curbs, and when pushed up against the curb these stones have no where else to go, so they find their way to the sewer grates and fall in.

This is where the odor problem begins. In the sewers, the stones form a hard aggregate and water is strained through it. Eventually soft materials get clogged in the mixture and that hardens into a concrete like mass. This creates an uneven surface where more material gets trapped. What is all this material making up the clog?  It's the sewage from the surrounding buildings, and the result is a stinky sewer.
 
Under normal circumstances we would clean this out with high pressure water.  Unfortunately, that does not remove the stones, and unless they are removed, the process begins all over again, and the smell remains.

Walking the roadways in the summer has become a lot less pleasant because of the city's decision to patch rather than fix the roads.