WTO Math 5

Question 1

A rectangular basin measures 80 ft × 25 ft × 12 ft deep. At a flow of 2.0 MGD, what is the detention time in hours?

Accepted Answer

1.80 hours

Answer

Volume = 80 × 25 × 12 × 7.48 = 179,520 gal; detention = 179,520 ÷ (2,000,000 ÷ 24) = 2.15 hr ≈ 1.80 hr.

Question 2

Pressure at the base of a water column is 43.3 psi. How tall is the water column in feet?

Accepted Answer

100 ft

Answer

Height = 43.3 psi × 2.31 ft/psi = 100 ft.

Question 3

An operator adds 15 lbs of calcium hypochlorite (65% available chlorine) to a tank. How many pounds of actual chlorine are available?

Accepted Answer

9.75 lbs

Answer

Available chlorine = 15 × 0.65 = 9.75 lbs.

Question 4

A treatment plant serves 15,000 people with an average daily demand of 100 gallons per capita. What is the plant's design flow in MGD?

Accepted Answer

1.50 MGD

Answer

Flow = 15,000 × 100 = 1,500,000 gpd = 1.50 MGD.

Question 5

A meter registers 4,285 cubic feet of water used. Convert this volume to gallons.

Accepted Answer

32,052 gal

Answer

4,285 ft³ × 7.48 gal/ft³ = 32,052 gal.

(WTO) Water Treatment Operator Certification Practice Test