The adjacent cities of Tempe and Mesa, Arizona, rely on a combined wastewater collection system comprising 434 miles of sanitary sewer lines and more than 6,000 manholes. The 40-mgd system serves a total metropolitan population of nearly 450,000. Turbulent flows at the force main discharges and other areas of the sewer system cause considerable hydrogen sulfide off-gassing and resultant odor emissions through nearby manhole covers. In addition, low sewage volume, typically a problem in newly developing suburban communities, causes the liquid waste stream to become stagnant and highly odorous.
How Tempe Controls Manhole Odors