The city of Greenville is about to start city-wide curbside garbage pick-up for its residents.The city will have to buy some garbage trucks.The city can't decide if will becheapest to buy small, medium, or large garbage trucks.Small trucks are the cheapest to buy,but they fill up fast and have to make frequent trips to the landfill to off-load the solid waste.Large trucks are the most expensive, but they can go longer between off-loading at the landfill,which cuts down on labor costs.Your job is to determine the best size of truck for the city tobuy, and how many people must be hired to drive the trucks.Suppose it takes 20 minutes to drive from the city garage to the beginning of the garbage pick-up route.It takes 25 minutes to drive between the route and the landfill (one-way).It takes 20minutes to drive from the landfill back to the city garage.It takes 15 minutes to off-load a truckat the landfill.The truck is operated by a two-person team.The team gets two 15-minutebreaks during the work day.One hour per day is allocated for unforeseen events (traffic jams,re-fueling, truck maintenance, equipment malfunction, etc.).The total shift length is 8 hours.
a. If the truck has to make three runs to the landfill during the day for off-loading, thenhow much time is left in the day for actual garbage collection?How much time is availablefor garbage collection if the truck has to make only two runs to the landfill each day?Howmuch time is available for collection if the truck has to make only one run to the landfill each day?
A garbage truck can drive about 5 miles per hour between houses, which is about 2 m/sec. On average, house are about 80 m apart. It takes about 10 sec to empty one garbage can into the truck, and each house has two garbage cans.
b. How many houses can one truck serve in one day, assuming that the truck makes 3 runs to the landfill during the day? What if the truck has to make only 2 runs to the landfill?
c. The city of Greenville has a total of 10,000 houses. Each house will have garbage pick-up once per week. Garbage trucks operate 5 days per week. How many trucks must the city buy and operate, assuming that each truck makes 3 runs to the landfill each day. How many if the truck make only one run to the landfill per day. How many trucks must the city buy assuming that each truck makes only 2 runs to the landfill?
d. How many sanitation workers must the city hire under the 3 different scenarios?
On average, each house puts 0.25 m3 of refuse at the curb each week. The density of solid waste (uncompacted) is 120 kg/m3 . The trucks can compact the refuse by a factor of 3.5.
e. How big must the truck be (in m3 of capacity) for the 3 scenarios under consideration?
The annualized cost of purchasing, fueling and maintaining a truck is given by:
Cost ($) = 10,000 + 4,200 V (V is truck volume in m3 .)
The labor cost is $22 per person per hour and each truck requires a 2 person team. The sanitation workers work 8 hours per day, 5 days per week, 52 weeks per year.
f. What is the cost for solid waste pick-up under the 3 different scenarios. Which of the 3 scenarios is the most economical?
g. For the scenario that you recommand, what is the annual cost per household? What is the monthly cost per household?