Analysis of gases discharging from inspection wells of urban drainage system and its impacts on the surrounding air quality

A community drainage system in arid area of northwest China was investigated, of which A# representing inspection well with catchment and without water drop, B# representing inspection well without catchment and water drop and C# representing inspection well with catchment and water drop. Through monitoring the pollutants concentration of different heights from water surface in inspection wells, from the blowhole of inspection wells and the pollutants concentration in the air near inspection wells, the impacts of gases emission from urban drainage system on the surrounding air quality was evaluated. The results showed that the level of hydrogen sulfide(H2S) and carbon dioxide (CO2) was much higher than that of ammonia(NH3)and methane(CH4) in inspection wells. Inspection well type and rainwater catchment also had a great influence on pollutants concentration. Through analyzing the air pollutants concentration near inspection wells, we found that the waste gases generated from urban drainage systems had a neglectable contribution to urban environmental air pollution.