Sewer gas Sewer gas Sewer gas is a complex mixture of toxic and nontoxic gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes, typical components of sewage. Sewer gases may include hydrogen sulfide, ammonia, methane, esters, carbon monoxide, sulfur dioxide and nitrogen oxides. Improper disposal of petroleum products such as gasoline and mineral spirits contribute to sewer gas hazards. Sewer gases are of concern due to their odor, health effects, and potential for creating fire or explosions. Sewer gas is typically restricted from entering buildings through plumbing traps that create a water seal at potential
Merrimack Valley gas explosions was shut off; electricity to portions of the three communities was also interrupted to avoid igniting any lingering gas. Thousands of people were told to shut off their gas service and evacuate their homes. In Lawrence, Mayor Dan Rivera urged residents in the city to move north of the Merrimack River. Schools and senior citizen centers were opened up in all three areas to take in the evacuees, and hotels offered shelter as well. The number of people evacuating by vehicle soon caused gridlock on streets that were already experiencing congestion by the afternoon rush hour commute. Merrimack College evacuated