Sean Edward Paquette
Homework Number 3
February 24, 2014
Problem 3-1:
Determine the time required to complete a filling and emptying cycle for a refuse collection vehicle
serving a residential area if the following conditions pertain: Truck volume = 20 yds 3 Each location
has on average two containers of 80 gallons each at 75% full. Refuse is picked up twice per week.
Truck has a compaction ratio of 1:2.
Problem 3-5:
The haul distance is 15 miles as the crow flies, and the anticipated average truck speed is 35 mph.
Estimate the one-way haul time.
Problem 3-7:
Estimate the time to collect recyclable in green roll-out containers from a 1000-foot-long street if the
homes are 50 feet apart, on both side of the road and a two-person crew is doing the collecting.
Estimate that it takes 30 seconds to empty the contents of each green container into the truck and a
set-out amount of 12 kgs.
Sean Edward Paquette
Homework Number 3
February 24, 2014
Problem 3-12:
Two small communities, Alpha and Beta, each have a small landfill. They are considering building a joint
landfill to serve both communities. Write an objective function that can be used to minimize the total
cost of disposal where the towns would have the option of taking the refuse to their own landfill or to
the common facility. The will not be able, however, to take the refuse to each other’s landfill. Use the
following variables and state all constraints:
Solve the objective function for two conditions: (1) when the towns use their own landfills exclusively
and (2) when only the central shared facility is used by both towns. Use an optimization software
package to find the optimum (least-cost) solution.
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Sean Edward Paquette
Homework Number 3
February 24, 2014
Problem 3-13:
Your client is a small community of 5000 people. They want to begin a municipally operated refuse
collection and disposal program and ask your advice on the purchase of collection vehicles. They
want to collect refuse once a week. What would you recommend?
I would recommend first developing a collection program which picks up at least twice a week. One day
needs to be focused on recyclables the other day solely needs to be standard refuse. Furthermore, for
5,000 people I am assuming 4,000 homes. To stop at each home to collect recyclables it would take on
average 34 hours. Therefore, I would recommend 5 automatic drop garbage and 4 recycle trucks. This
allows for 8 hour shifts and time for transporting to dump location.
Problem 3-15
A community has two landfills. The cost per ton of disposing of refuse in the landfills is exactly the same.
There are three collection routes in town. Write an objective function and constraint equations for
minimizing the transportation cost (only) from the three collection routes to the two disposal sites.
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Problem 3-16
Write an objective function and constraint equations for minimizing the transportation cost (only) for
the community shown in Figure 3-27. Assume that the cost of disposal is the same at both disposal
sites, and therefore, the disposal cost can be ignored.
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Problem 3-18
A community of 25,000 people wants to initiate public garbage collection. If the collection is to be once
a week, what size truck would they need? (Note: Available truck sizes are 10, 14, 16 and 20 cubic yards.)
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Problem 3-19:
Sean Edward Paquette
Homework Number 3
February 24, 2014
The Mayor of Recycleville has asked you to develop an integrated waste management program.
Residents currently pay $10 per month and can put out up to five 32-gallon cans per week. You offer the
Mayor an automated system with two price options:
In addition you will provide the residents a 64-gallon commingled recycling container and a 96-gallon
green waste container. (A) What are the advantages of using the program developed for you? (B) Are
residents opting for the 96-gallon container paying more for this service? (C) Which price option would
likely have the higher recycling rate, and why? Look at the RPA web site for some case studies to
support your reasoning. (D) What impact would collecting recyclables one week and collecting green
waste the next have on the recycling rate?
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Problem 3-20:
Estimate the number of commercial locations that can be serviced in one day by the collecting vehicle
described below: Truck volume = 20 yd3 Compaction ratio = 2 Container volume = 6 yd3 on average,
containers are 80% full drive between locations = 8 minutes, at site time = 15 minutes, haul time one
way = 20 minutes, to and from garage = 15 minutes, workday = 8 hours, off route factor 0.25. Assume
all vehicles making the trip to transfer or disposals are full.
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