Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem4-1:
For your own community, calculate how many years it would take to fill a football field 20ft deep.
Include the necessary earth cover.
After extensive online searching for average quantities of refuse for the town of Rocky Hill, I was unable
to collect actuals. Therefore, the following are assumptions: Miscellaneous Paper 50% by weight
(Compacted bulk density 3.81 lb/ft3), Plastic 20% by weight (Compacted bulk density 35 lb/ft3), Garden
waste 10% by weight (Compacted bulk density 4.45 lb/ft3), Glass 10% by weight (Compacted bulk
density 18.45 lb/ft3) and metal 10% by weight (Compacted bulk density 50 lb/ft3).
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-2
Estimate the life of a landfill for a user population of 10,000. The available area for the area-type landfill
is 10 acres. The water table is estimated at 20ft below the ground surface. The pit must have a side
slope of 1:3, and the final surface must have a slope of 1:4. Assume that the soil occupies 20% of the
compacted volume.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-3
Assume the following fraction, by weight, of material in a refuse:
(A) Estimate the in-place density of this refuse, using the bulk density values listed in Table 4-1.
(B) If the following materials are recovered in a materials recovery operation, estimate the bulk
density of the remaining refuse going into the landfill.
(C) If the life of the landfill for this community was originally calculated as 10 years, what is the
expected life if the materials listed in part (b) are recovered?
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-4
You are the engineer hired by a community trying to side a modern landfill. At the public hearing, one
of the neighbors of the proposed landfill asks you if her well water might become contaminated by
the landfill leachate.
(A) How would you answer her? Take your time and give a full answer.
(B) The town hired you to site the landfill. Is the town your client, or do you have a higher
professional responsibility?
I would answer her by saying there is always potential, although we are going to take the corrective
actions to prevent any water contamination. Yes, the town is your client although you do have high
professional responsibility.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-5
A landfill initially receives 1000 tons/day of waste. This receipt rate increases 10% per year. The
landfill is closed at the end of the fourth year. Using the EPA exponential model, calculate the yearly
gas production for 20 years after opening. What is the peak gas production in m3/yr?
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-6
You are a municipal engineer who had just received a request from the city director of planning to
comment on a proposed large multistory shopping center. You note that it is to be built on a site that
you vaguely remember as having been a landfill many years ago. Nobody in the office remembers for
sure when this was and what it was used for, when it closed, or how long it was been used. You do
know that is has been closed for 25 years. Write a letter to the planning director expressing your
concerns and recommendations.
Dear Planning Commissioner, today I was briefed with your plan to build a shopping center on grounds
to an old dump. From my understanding and with the limited knowledge of current details, I
recommend cancelling this project and attempting to find a new location. If you insist this is the only
location then I highly recommend extensive examination of the soils before. There potentially are a
number of hazardous and toxic chemical concerns which could arise from us breaking ground.
Furthermore, I recommend if the town has extra budget if the shopping center is not built to investigate
the possibility of contamination to the surrounding homes.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-7
How does a modern (Subtitle D) landfill differ from the older existing landfills? List and explain all items
that need to be considered in the Subtitle D landfills that were not important in older landfills before the
passage of RCRA legislation.
Xxx
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-8
A community of 100,000 people decides to construct a landfill that is to have a volume 2,000,000
cubic yards. How long can this landfill be expected to last?
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-9
Determine the required spacing between pipes in a leachate-collection system using a geonet and the
following properties. Assume the most conservative design and that all storm water from a 25-year,
24-hour storm enters the leachate-collection system.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-10
Repeat Example 4-6 assuming that the highest flow rate in each collection leg is 750 cubic feet per
minute at 115°C.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-11
A landfill is proposed for the area shown on the map in Figure 4-23. Why might this not be a good
location? Where might be a better place? What are the advantages and disadvantages of the new
location? Some relevant facts: Groundwater at the proposed landfill site is 5ft below the surface; the
soil is sand from -30 feet to +20 feet, and sandy loam above 20 feet.
The location may not be the best location because the waste from the landfill will seep into water. This
location based on the given information seems to be located in an area with a high water table level. A
better location could be to the west where the landfill will be located at a higher elevation and future
away from the community.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-12
A town of 100,000 people wants to construct on the site shown in Firgure 4-24. Design such a landfill.
Estimate the life of the landfill, and specify the equipment to be used, the method of operation, and
other considerations necessary for acceptable operation. Draw in road and any permanent
installations on the map.
The operations would require the standard construction equipment, bulldozer, front end loader, dump
trucks etc.
Sean Edward Paquette
Homework Number 4
Problem 4-13
Describe, from a microbiological perspective, what goes inside a sanitary landfill?
Below are the 5 phases of a sanitary landfill. The phases are referenced from:
March 6, 2014
Sean Edward Paquette
Homework Number 4
March 6, 2014
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-14
A town has hired a consulting firm to find a new landfill site. After they find the idea site, which is
located 500 miles from the town, Megafill Inc. offers to transport and dispose of the waste for only
$20 per ton more than the expected tipping fee at the new landfill.
A. What are some of the arguments in favor of, and against the town signing up with Megafill?
B. To better understand the site, Megafill offers to fly you, the city’s public works director, and
the city council to the site in their corporate jet. Do you accept the offer?
A. One can argue is the price point seems to be significantly low for the required transportation
needs. This could be a result of back charging or illegally dumping waste.
B. Being a city official it is unacceptable to receive C-suit amenities using tax payers dollars and
time.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-15
What is the USEPA minimum design criteria for the two components that are in a composite landfill
liner?
The design needs to include bottom clay and top geomembrane layer as well as pipes for leachate.
Sean Edward Paquette
Homework Number 4
March 6, 2014
Problem 4-16
Which of the following are the landfill design standards and which are landfill performance standards?
A.
B.
C.
D.
An operator must cover garbage with 6in. of dirt each day – performance
There can be no off-site gas migrations from the landfill – performance
No landfill odors can be detected at the boundary of the landfills – performance
A landfill must have gas collection wells every 40 feet – design