Water Resources and Environmental Engineering — Quiz 2

Questions in this quiz (10)

1. A Parshall flume with a throat width of $$0.6\ \mathrm{m}$$ measures an upstream head of $$0.42\ \mathrm{m}$$. Using the discharge equation $$Q=K\times W\times H_a^{1.55}$$ with $$K=1.428$$, calculate the flow rate.

   • $$0.310\ \mathrm{m^3/s}$$
   • $$0.275\ \mathrm{m^3/s}$$
   • $$0.198\ \mathrm{m^3/s}$$
   • $$0.245\ \mathrm{m^3/s}$$

2. An anaerobic digester destroys $$2200\ \mathrm{kg/day}$$ of volatile solids. The gas production rate is $$0.85\ \mathrm{m^3}$$ per kg of volatile solids destroyed. Calculate the total daily gas production.

   • $$1870\ \mathrm{m^3/day}$$
   • $$1650\ \mathrm{m^3/day}$$
   • $$2050\ \mathrm{m^3/day}$$
   • $$2420\ \mathrm{m^3/day}$$

3. A wastewater treatment plant has an NPDES permit limiting effluent BOD to $$25\ \mathrm{mg/L}$$. The plant discharges $$6500\ \mathrm{m^3/day}$$. Calculate the maximum allowable BOD mass discharge.

   • $$162.5\ \mathrm{kg/day}$$
   • $$125.0\ \mathrm{kg/day}$$
   • $$200.0\ \mathrm{kg/day}$$
   • $$145.5\ \mathrm{kg/day}$$

4. A water utility installs a turbine to recover energy from excess pressure in a transmission main. The flow is $$0.65\ \mathrm{m^3/s}$$ with an available head of $$28\ \mathrm{m}$$. The turbine efficiency is $$80\%$$. Using $$P=\eta\times\gamma\times Q\times H$$ with $$\gamma=9.81\ \mathrm{kN/m^3}$$, calculate the power output.

   • $$165.4\ \mathrm{kW}$$
   • $$142.8\ \mathrm{kW}$$
   • $$178.6\ \mathrm{kW}$$
   • $$128.3\ \mathrm{kW}$$

5. A septic system drain field is designed for a daily flow of $$1800\ \mathrm{L/day}$$. The soil percolation test indicates an application rate of $$24\ \mathrm{L/(m^2\cdot day)}$$. Calculate the required absorption field area.

   • $$75\ \mathrm{m^2}$$
   • $$68\ \mathrm{m^2}$$
   • $$90\ \mathrm{m^2}$$
   • $$60\ \mathrm{m^2}$$

6. Based on Darcy's experiments on flow of water through sand filters, which statement is INCORRECT about groundwater movement?

   • $$\text{The flow rate is proportional to the cross-sectional area.}$$
   • $$\text{The flow rate is proportional to the length of the sand filter.}$$
   • $$\text{The flow rate is proportional to the head drop.}$$
   • $$\text{The flow rate is proportional to the hydraulic conductivity.}$$

7. A $$100$$-ft wide and $$10$$-ft deep unconfined aquifer with hydraulic conductivity of $$0.2\ \mathrm{ft/hr}$$ connects two water channels. The water level is $$500\ \mathrm{ft}$$ in one channel and $$450\ \mathrm{ft}$$ in the other. The clear distance between the channels is $$3000\ \mathrm{ft}$$. Determine the rate of seepage in $$\mathrm{ft^3/hr}$$.

   • $$0.2\ \mathrm{ft^3/hr}$$
   • $$2.0\ \mathrm{ft^3/hr}$$
   • $$3.3\ \mathrm{ft^3/hr}$$
   • $$6.7\ \mathrm{ft^3/hr}$$

8. A $$10$$-cm diameter hydraulically smooth pipe carries water at a velocity of $$2\ \mathrm{m/s}$$. The pipe is $$100\ \mathrm{m}$$ long. Water temperature is $$90^\circ\mathrm{C}$$. Determine the head loss due to friction.

   • $$0\ \mathrm{m}$$
   • $$1\ \mathrm{m}$$
   • $$2.6\ \mathrm{m}$$
   • $$9\ \mathrm{m}$$

9. A $$1200$$-ft long galvanized steel pipe of $$1$$-ft outside diameter and $$1$$-inch wall thickness connects two reservoirs. The pipe discharge rate is $$2\ \mathrm{ft^3/s}$$. Assume the pipe has a round entrance and a sharp exit for the fittings. Determine the fitting loss.

   • $$2\ \mathrm{ft}$$
   • $$0.22\ \mathrm{ft}$$
   • $$0.02\ \mathrm{ft}$$
   • $$0\ \mathrm{ft}$$

10. For the pipe connecting two reservoirs, assume the following losses: Pipe entry loss = $$2\ \mathrm{ft}$$ Pipe exit loss = $$3\ \mathrm{ft}$$ Friction loss = $$30\ \mathrm{ft}$$ Other fitting losses = $$5\ \mathrm{ft}$$ If the elevation of the water table in Reservoir A is $$100\ \mathrm{ft}$$, determine the elevation of Reservoir B.

    • $$40\ \mathrm{ft}$$
    • $$60\ \mathrm{ft}$$
    • $$70\ \mathrm{ft}$$
    • $$95\ \mathrm{ft}$$