Texas Wastewater Class B Practice Exam

Which compound is NOT typically found in lift stations and manholes?

1. Natural gas

2. Helium

3. Gasoline fumes

4. Carbon dioxide

The correct answer is: Helium

The correct identification of helium as a compound that is not typically found in lift stations and manholes highlights the unique nature of the environments in these locations. Lift stations and manholes are generally associated with the management of wastewater and sewage systems, environments where gases like methane, carbon dioxide, and possibly traces of gasoline fumes are more commonly encountered due to the decomposition of organic matter or spills. Natural gas is primarily composed of methane, a product of anaerobic digestion that can occur in wastewater systems. Carbon dioxide is a common byproduct of aerobic processes and can also be found due to the decomposition of organic material. Gasoline fumes may occasionally be detected due to nearby fuel storage or spills, especially in urban areas where infrastructure can overlap with petroleum distribution systems. Helium, on the other hand, is a noble gas that is not produced in typical biological or chemical processes occurring in wastewater systems and is not associated with any of the activities normally found in lift stations and manholes. Its presence would be unusual and not typically anticipated in these environments.