Is Gas Detection in Sewers Important?
Homestead, PA — During low-flow, dry-weather periods, sanitary wastewater solids deposited in combined sewers become a major pollutant of our water system. They have significant adverse impacts on the integrity of the sewage system and receiving-water quality. Even sewers that are supposedly designed to be ‘self-cleansing’ will have transient sediment deposits, and part of the load in transport will move near the sewer invert. These solids contain high concentrations of sulfates, and the conditions of a sewer are ideal for transforming them to hydrogen sulfide. The hydrogen sulfide is then oxidized to sulfuric acid, a highly toxic and corrosive gas, by biochemical transformation. Gas monitoring and gas detection inspections are conducted prior to and during any task involving a sewer because of the potential for the presence of sewer gases, especially in large diameter pipes where flow rates tend to be less and the area above the flow level is greater than smaller diameter pipes. The
