Which technique involves forcing fresh air into a manhole using a blower?

• A. Testing
• B. Installing at Pipe Alignment Changes
• C. Manhole Cover Size
• D. Manhole Ventilation

Answer: (D)

The technique being tested is providing air flow to a confined space by actively moving air with equipment. Forcing fresh air into a manhole using a blower is a ventilation method: it pushes clean air into the space, creating a flow that replaces stale or hazardous air and helps dilute gases like hydrogen sulfide, methane, and carbon dioxide. This keeps oxygen levels safer for workers during sewer inspection, cleaning, or repair tasks and reduces the risk of toxic exposure.

Other options don’t fit because testing refers to checking the integrity or condition of something, not introducing air; installing at pipe alignment changes deals with adjusting pipes or joints rather than air movement; and manhole cover size concerns the physical dimensions of the cover, not ventilation.