Exam 1 (1)

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CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Name: ___________________________________ 
 
 
Page 1 of 8 
 
Directions: 
 
This is a 3 hour maximum, take home mid-term exam. This exam is worth 25% of your 
grade. You are on the honor system to take only 3 consecutive hours to complete the 
exam (including breaks) and to use only the materials available to you from class or 
your book. You are not allowed to discuss or consult on the questions with other 
students from the class or any other individuals prior to handing in the exam. You are 
not allowed to use the internet. Note the time you began the exam and the time you quit 
working as indicated below: 
 
 Exam started: __________________ on _____________ 
 
 Exam stopped at: _______________________________ 
 
STATE ALL ASSUMPTIONS. YOU WILL NEED TO MAKE SOME. If you cannot solve 
one problem, and the results of the first problem are needed for the next problem, state 
the value you will use to start the second problem (even if you know it is not correct). 
You can obtain full credit on the second problem even without having solved the first 
problem correctly. Feel free to use a spreadsheet or other computational aid. 
 
 
Turn in to Dr. Weidhaas before 5 PM on Friday October 16th in ESB 647 
If I am not in my office please slide the exam under my door. 
 
 
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 2 of 8 
 
Problem #1 (5 points): Name the following chemical using the rules presented in class 
and in the textbook. 
 
Chemical structure Chemical name __________________________ 
 
 
 
 
Problem #2 (10 points): The chemical in problem #1 has the following properties 
 
H = 2.5*10-8 atm-m3/mol 
S = 20 mg/L 
Log Koc = 3.5 
Log Kow = 5.1 
Log BCF = 5.7 (human 
liver) 
 
Based on the values given in class for the parameters listed above, draw on the 
diagram below with arrows (as shown in the legend to the right) to indicate the likely 
exposure pathways, the possible exposure pathways and the unlikely human exposure 
pathways. Draw an outline of your assumed source area (as shown in the legend). 
Assume the foc for the soil is 0.001. Assume the well serves as a source of drinking 
water and irrigation water for the garden. 
 
 
 
 
 
 
 
 
Problem #3 (5 points): Based on the Kow above is the compound likely to be lipophillic 
or hydrophilic (circle one). 
 
 
 
x
Likely exposure pathway
Possible exposure pathway
Unlikely exposure pathway
Spill area or source area
Use the following symbols
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 3 of 8 
 
Problem #4 (5 points): For problem #2 above, circle the environmental media that is 
likely contaminated a long time after the drums leaked the chemical. Also circle the 
likely human exposure routes to this chemical. 
 
Environmental media Exposure routes 
1. Air 
2. Soil gas 
3. Indoor air 
4. Surface soil 
5. Vadose zone soil 
6. Groundwater 
7. Surface water 
8. Food chain 
1. Inhalation of vapors outdoor air 
2. Inhalation of vapors indoor air 
3. Inhalation of soil particles 
4. Dermal adsorption from soil particles 
5. Ingestion of soil particles 
6. Ingestion of groundwater 
7. Ingestion of surface water 
8. Dermal adsorption from groundwater 
9. Dermal adsorption from surface water 
10. Ingestion of food 
 
Problem #5 (5 points): You suspect a 50 acre property contains a 2 acre former 
hazardous materials dump. There is no surface evidence of the bounds of the former 
dump. It is suspected that both drums of waste containing volatile organic compounds 
(VOCs) and potentially ordnance were put in the landfill. Assume you can only drill at 
most 2 feet into the ground to avoid the ordnance. Suggest two possible non-destructive 
characterization methods to locate the 2 acre dump on the 50 acre property. 
 
Method #1 __________________________________________________ 
 
Method #2 __________________________________________________ 
 
 
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 4 of 8 
 
Problem #6 (10 points): Given the following data determine the hydraulic gradient and 
direction of the groundwater flow system (you are not allowed to use the internet!). 
Show all steps used to determine the solution. Note that not all wells are required for the 
solution. 
 
Well 
number 
X,Y 
coordinate (ft) 
Water depth 
(ft above mean sea level) 
1 450, 350 110 
2 100, 200 120 
3 500, 100 109 
A 100, 400 119 
B 550, 200 100 
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 5 of 8 
 
Problem #7 (5 points): Assume for the groundwater and well system shown in problem 
#6 that benzene is injected into Well #2. Assume K = 1*10-2 cm/s. Determine: 
 
(A) Which well will become contaminated with benzene, Well A or Well B? 
(B) Assuming Darcy flow governs the system, how long until the benzene reaches either 
well A or well B. 
 
 
 
 
 
 
 
 
 
 
 
Problem #8 (5 points): Assume for the groundwater system shown in Problem #6 that 
benzene is injected into Well #2. Diagram the theoretical concentration of benzene at 
the downgradient well (whichever you selected in Problem #7) over time by filling in the 
plots below. 
 
Time
Cdowngradient
(mg/L)
Cwell 2
1. Benzene is transported by advection 
only (no decay or dispersion occurs during 
transport)
Time
Cdowngradient
(mg/L)
Cwell 2
2. Benzene is transported by advection 
and undergoes dispersion and sorption 
but no degradation occurs
3. Benzene is transported by advection 
and undergoes dispersion, sorption 
and degradation 
Time
Cdowngradient
(mg/L)
Cwell 2
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 6 of 8 
 
Problem #9 (20 points): A pump and treat groundwater system brings water 
contaminated with 100 mg/L of Dalekanium to the surface for treatment with a granular 
activated carbon (GAC) bed. Dalekanium needs to be treated to 1 mg/L before 
reinjection of the cleaned water in an onsite well. You have the data in the table below 
regarding laboratory generated bed-depth service time curves. The laboratory study 
columns were 7.5 ft (L) X 2 in (W) and operated at a flow rate of 0.25 L/min. Assume the 
groundwater flow rate for the full scale system is 10,000 gal/day and the unit weight of 
carbon is 30 lb/ft3. 
 
Determine: 
 
A) The height of the adsorption 
 zone (ft) 
B) Number and diameter of columns 
 required (ft) for the full scale 
 system 
C) Carbon usage rate (lb/day) 
 
 
26
46.4
60.2
10.4
25
40.4
-10
0
10
20
30
40
50
60
70
0 5 10 15 20 25
Se
rv
ic
e
 t
im
e
, d
ay
s
Bed Depth, ft
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 7 of 8 
 
Problem #10 (20 points): You are considering replacing the GAC bed treating the 
wastewater described in problem #9 with an complete mix, suspended growth with 
recycle bioreactor. Assume 0.5 mg of cells are produced for every mg of dalekanium 
degraded in the bioreactor, you can sustain a biomass concentration of 3500 mg/L in 
your system and the biomass decay rate is 0.05 day-1. Further assume your sludge age 
is 30 days and the flow rate is 10,000 gal/day. 
 
Determine: 
A) What hydraulic detention time is required to reduce the dalekanium in the influent 
from 100 mg/L to 0.01 mg/L? 
B) What is the final volume of the reactor? 
 
 
 CE-549493A Solid and Hazardous Waste Engineering 
Exam #1, Fall 2015 
Page 8 of 8 
 
Problem #11 (10 points): Based on the CERCLA Remedy Selection Criteria, which 
system in problem #9 and #10 do you recommend for treatment of the wastewater from 
this pump and treat system? Describe why you recommend your selected system. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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