Water Resources and Environmental Engineering — Quiz 4

Questions in this quiz (10)

1. A flow test is performed at a fire hydrant to determine the flow rating at a pressure of $$20$$ psi. The static pressure at the hydrant is $$70$$ psi. The test uses a hydrant with a $$2.5$$-inch orifice with a square outlet projecting into the barrel of the hydrant. A pitot pressure of $$45$$ psi is observed during the test. Determine the maximum flow rate that this system can provide at $$20$$ psi.

   • $$875\ \mathrm{gpm}$$
   • $$1270\ \mathrm{gpm}$$
   • $$1638\ \mathrm{gpm}$$
   • $$3500\ \mathrm{gpm}$$

2. The pitot tube shown below is placed at a point where the velocity is $$2.0\ \mathrm{m/s}$$. The specific gravity of the fluid is $$2.0$$, and the upper portion of the manometer contains air. Determine the manometer reading $$h$$.

   • $$20.0\ \mathrm{m}$$
   • $$10.0\ \mathrm{m}$$
   • $$0.40\ \mathrm{m}$$
   • $$0.20\ \mathrm{m}$$

3. The purpose of an emergency spillway is most closely:

   • $$\text{To lower reservoir levels in anticipation of a significant rainfall event that could cause flooding.}$$
   • $$\text{To divert flows from a reservoir, if a dam safety inspection indicates a dam's principal is in an unsafe condition.}$$
   • $$\text{To divert reservoir flows so that emergency responders can safely access a water body in the event of a drowning or other serious injury.}$$
   • $$\text{To allow flow to pass that exceeds the capacity of the principal spillway and protect the dam in the event of a flood.}$$

4. A $$12$$ inch diameter concrete sanitary sewer with $$n=0.013$$ flows half full and is constructed on a grade of $$0.5\%$$. Determine the flow velocity.

   • $$1.6\ \mathrm{ft/s}$$
   • $$2.0\ \mathrm{ft/s}$$
   • $$3.2\ \mathrm{ft/s}$$
   • $$32.4\ \mathrm{ft/s}$$

5. A weir must be sized at a pond to pass flow into an emergency spillway for flood control. Given a weir width of $$10$$ ft, which is smaller than the width of the channel, determine the approximate depth of flow required to pass $$125$$ cfs.

   • $$1^\prime-6^{\prime\prime}$$
   • $$2^\prime-0^{\prime\prime}$$
   • $$2^\prime-6^{\prime\prime}$$
   • $$3^\prime-0^{\prime\prime}$$

6. A water treatment plant with a flow of $$30,000\ \mathrm{m^3/day}$$ uses polymer at a dose of $$1.5\ \mathrm{mg/L}$$. The polymer solution has a concentration of $$0.5\%$$. Calculate the required volume of polymer solution per day.

   • $$45\ \mathrm{m^3/day}$$
   • $$9\ \mathrm{m^3/day}$$
   • $$18\ \mathrm{m^3/day}$$
   • $$4.5\ \mathrm{m^3/day}$$

7. A storm event generates $$15,000\ \mathrm{m^3}$$ of runoff with an average TSS concentration of $$180\ \mathrm{mg/L}$$. Calculate the total mass of suspended solids transported.

   • $$27\ \mathrm{kg}$$
   • $$270\ \mathrm{kg}$$
   • $$2,700\ \mathrm{kg}$$
   • $$27,000\ \mathrm{kg}$$

8. A pumping test on a well shows discharge of $$0.035\ \mathrm{m^3/s}$$ with drawdown of $$4.2\ \mathrm{m}$$. Calculate the specific capacity.

   • $$12.0\ \mathrm{L/s/m}$$
   • $$8.33\ \mathrm{L/s/m}$$
   • $$4.17\ \mathrm{L/s/m}$$
   • $$14.7\ \mathrm{L/s/m}$$

9. Which statement about a combined sewer line is correct?

   • $$\text{Storm water and sewage share the same pipe}$$
   • $$\text{Imaginary gradient line}$$
   • $$\text{Residential and commercial sewage share pipe}$$
   • $$\text{Activated sludge transport line}$$

10. Characteristics that lead to eutrophication of a water body include all the following except:

    • $$\text{Nitrogen runoff}$$
    • $$\text{Sediment deposition}$$
    • $$\text{High dissolved oxygen}$$
    • $$\text{Excess plants}$$