CE 310 Sample Second Midterm
Spring 20XX
Closed Book/Closed Note Portion
B.A. DeVantier
Matching. (2 points each) Put the letter of the description on the right which best describes one of the terms
on the left. No letter may be used more than once.
_K__ Carbonaceous BOD
A. Saturated soil region above GWT.
_C__ Nitrogenous BOD
B. Theoretical surface of peizometrically pooled water.
_A__ Capillary fringe
C. Water pollutant measurement of biologically oxidizeable organic nitrogen
or ammonia.
D. Sum of organic nitrogen and ammonia measured as N.
_J__ Vadose zone
_N__ Nonvolatile Dissolved
Solids
_G__ Volatile Suspended
Solids
_H__ Volatile Dissolved
Solids
_E__ Nonvolatile Suspended
Solids
_B__ GWT
E. Solids in a water sample due to grit and soil particles.
_O__ Aquifer
J. Unsaturated soil region above the level of capillary rise of water.
_D__ TKN
_I__ NOAEL
K. Water pollutant measurement of biologically oxidizeable organics with
nitrification suppressed.
L. Toxicity dose well below the threshold by a safety factor.
_F__ LOAEL
M. Cumulative sum of toxicity dose ratios relative to established standards.
_L__ RfD
N. Solids in a water sample due to salts in solution.
_M__ HI
O. Underground body of water.
F. Detectable toxicity dose.
G. Solids in a water sample due to bacterial cells.
H. Solids in a water sample due to dissolved organic solvents.
I. Toxicity dose just below the threshold dose
Multiple Choice. (2 points each) Circle the letter of the phrase which best completes each sentence below.
1. The sun is related to trophic levels because
A. it is a producer.
B. it represents the highest trophic level.
C. it drives all of the cycling of materials important to life.
D. all life is destroyed as it nears the sun.
2. A chemical which inactivates ammonia is added in a standard five-day BOD test to
A. add DO to be sure there is enough.
B. block production of ammonia that is a product of aerobic microbial metabolism.
C. suppress nitrification consumption of oxygen.
D. kill bacteria in the sample.
3. A bioaccumulated (or bioconcentrated) substance moves
A. from the lowest trophic levels to the highest in the food chain.
B. downstream in a river ecosystem.
C. from the largest organisms to the smallest in an ecosystem.
D. from the highest trophic levels to the lowest in the food chain.
4. Deoxygenation in an oxygen sag curve is due to
A. turbulent eddies in a river constantly bringing water to the air at the river’s surface.
B. chemicals from agricultural pesticide use in runoff to a river.
C. a lack of oxygen on a river bottom.
D. aerobic organisms consuming biodegradable organics discharged to the river.
5. The time of concentration of a watershed is
A. the time it takes to remove a contaminant in a watershed to the DWEL.
B. the focal point in time of storm precipitation intensity falling onto the watershed.
C. the time it takes precipitation runoff to travel from the most remote watershed point.
D. all of the cumulative runoff flowing out of a watershed area.
6. Oxygen sag occurs in a river due to an oxygen depleting discharge, because
A. oxygen is added by aeration faster than it is depleted.
B. no oxygen is added by reaeration.
C. dissolved oxygen is depleted faster than aeration adds it.
D. saturation dissolved oxygen decreases.
7. The worst case condition for oxygen sag with regard to temperature is high temperature, because
A. deoxygenation rates decrease.
B. reaeration rates increase.
C. saturation dissolved oxygen is decreased.
D. all of the above.
8. A water sample’s ultimate BOD
A. is equal to its nitrogenous BOD.
B. is less than its five-day BOD.
C. is greater than its five-day BOD.
D. can be a negative value.
9. Producer organisms
A. heat up the atmosphere.
B. tend to convert matter from biotic form to abiotic forms.
C. tend to convert matter from abiotic form to biotic forms.
D. create dead ends in natural cycles.
10. E. coli are used as indicator organisms, because
A. they have an indicative color.
B. they are so rare that their presence indicates a problem.
C. they exist in large numbers in the intestines of humans& might mean fecal contamination.
D. they can cause terrible disease when present in undercooked meats.
Spring 20XX
CE 310 Sample Second Midterm
Open Book/Open Note Portion
B.A. DeVantier
Problem 1 The USEPA drinking water standard for arsenic is 10 ppb. Estimate the additional risk for
females consuming water at this limit for a lifetime exposure of 75 years, and translate that risk into the
number of additional cancers per million women.
Problem 2 (15 points)
A lab technician is surprised by higher than usual BOD5 results for the effluent of a sewage treatment plant at
a level of 26 mg/L. After some investigation the technician finds that the thermostat in the BOD incubator
has malfunctioned, and the temperature of the test had been held at a higher level than the standard of 20C.
If the technician was expecting a BOD5 of 20 mg/L, and he knows that the first order BOD rate constant at
20C is 0.23 day-1 for this water, use the first order BOD model and the  temperature correction factor to
estimate the temperature that the incubator had improperly held.
Problem 3 (20 points)
A river flowing at 4 mi/day and 25 ft3/s receives a flow of 0.1 ft3/s leaking from a syrup storage tank at a
factory next to the river. The ultimate BOD of the of the syrup is 3000 mg/L. The stream temperature of
25◦ C is not affected by the small flow of the leak nor is the dissolved oxygen level of the stream of 7
mg/L. What is the dissolved oxygen in the stream 6 miles downstream of the leaking flow if we know that
the river before the leak point has an ultimate BOD of 1 mg/L and the deoxygenation rate constant is 0.3
day-1 and the reaeration rate constant is 0.25 day-1 at the river temperature?