What is the maximum allowable velocity in public water mains?

3 ft/sec

8 ft/sec

10 ft/sec

12 ft/sec

Correct Answer : 8 ft/sec

Explanation : The velocity of 3 ft/sec is considered to be minimum to keep the foreign particles moving in sewers. The Washington State Department of Health (DOH) recommends a maximum velocity of 8 ft/sec but permits greater velocities during fire flow conditions.

Recently Updated in Waste Water Engineering Questions

What is the growth of huge amounts of algae and other aquatic plants leading to the deterioration of the water quality called?

Algae growth

Eutrophication

Denitrification

Nitrification

Correct Answer : Option (B) : Eutrophication

Explanation : Eutrophication is the growth of huge amounts of algae and other aquatic plants leading to the deterioration of water quality. The untreated wastewater is rich in organic matter which demands oxygen.

5 days-biochemical oxygen demand (BOD₅) is taken at a temperature of

0°C

15°C

20°C

25°C

Correct Answer : Option (C) : 20°C

Sewer pipes are designed for maximum discharge with 25% to 33% vacant cross-sectional area for

unexpected increase in the population

under estimates of maximum and average flows

unexpected large scale infiltration of stream water

All of the above

Correct Answer : Option (D) : All of the above