Which type of sewer carries wastewater to the ultimate point of disposal?

• A. Storm overflow sewer
• B. Outfall sewer
• C. Depressed sewer
• D. Relief sewer

Answer: (B)

The key idea is understanding the role of each sewer type in moving wastewater to the disposal point. An outfall sewer is the main conduit that takes sanitary wastewater from the city’s network and conveys it toward the final disposal point, which is typically the treatment plant or the discharge into a receiving water after treatment. It represents the final leg of conveyance for sewage to be disposed of or treated.

Storm overflow sewers are designed to carry stormwater (and sometimes a portion of combined flows during heavy rain) and are not meant for the regular wastewater destined for disposal. Depressed sewers are simply deepened or lower-graded sections used to maintain gravity flow in difficult terrain, not for directing ultimate disposal. Relief sewers provide additional capacity to relieve peak flows in overloaded sections, but again they’re about flow management within the network, not the final disposal route.

So, the sewer that carries wastewater to the ultimate point of disposal is the outfall sewer.