Unit II QUESTION Advanced Solid Waste Management

I

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Municipal Government &

Transfer Station

Problem: A municipal government has agreed to provide once per week waste collection services to a

new residential community of 25,000 people. The city council has hired you to make a preliminary assessment to determine if they should build and operate a transfer station to support the collection. For the initial analysis, assume that the community does not have a recycling program. Here is some

of the initial data that the municipal engineer has collected.

* The round trip distance from the residential community to the landfill is 40 miles. * The size of the residential garbage truck that collects waste from the community is 30 cubic yards.

* The round trip distance from the proposed site of the transfer station will be 45 miles. * The garbage truck is capable to compact the refuse to 700 lbs./yd3. * A long haul truck is capable to transport 25 tons of compacted waste per trip.

* The transfer station has a fixed operating cost of $15/ton. * The cost to operate the garbage truck is $1.50/mile.

* The cost to operate the long haul truck is $0.75/mile. (a) Would you recommend to the city council that a transfer station should be built and operated? Show all work on how you came to your answer.

* The United Nations estimates waste generation rate is 4.8 lbs. per person per day. (See page 39 of the textbook)

(b) If the community operated a recycling program, would this change or support your

recommendation to the city council? Show all work on how you came to your answer. * Total recycled municipal waste is 33.2% of generation.

Solution:

(a) We will use the estimated waste generation rate of 4.8 lbs. per person per day in this calculation.

Step 1 Residential waste generated = 25,000 people x 4.8 lbs. x 7 days = 840,000 lbs. or 420 tons

person/day 1 week each week

Step 2 Calculate the waste collected in each truck:

30 yd3 x 700 lbs. = 21,000 lbs. of waste collected per truck truck yd3

Step 3 Calculate the number of trucks needed:

840,000 lbs. = 40 trucks (round up) 21,000 lbs./truck

Step 4

Determine the cost to travel to landfill by garbage trucks:

40 trucks x $1.50 x 40 miles = $2,400 per week week mile

Step 5 Calculate the number of long haul trucks based on residential waste generated:

420 tons = 17 trucks (round up) 25 tons per truck

Step 6 Determine cost to travel to transfer station by long haul trucks:

17 trucks x $0.75 x 45 miles = $573.75 mile per truck

Step 7 Calculate cost of transfer station:

420 tons x $15 = $6,300

ton

Step 8 Calculate cost by long haul truck:

$573.75 + $6,300 = $6,873.75

Therefore, the community should not build and operate a transfer station. Doing so will increase costs by : $6,873.75 x 100 = 286% or 186%* higher cost

$2,400.00

* 286%  100% = 186%

(b) We will use the total recycled municipal waste generation of 33.2%. This also means that 66.8% of waste goes to the landfill per total waste that is generated. We will also use the estimated

waste generation rate of 4.8 lbs. per person per day in this calculation.

Step 1 Calculate residential waste generated:

25,000 people x 4.8 lbs. x 7 days x 0.668 = 561,120 lbs. or 281 tons

person/day week (round up)

Step 2 Calculate the waste collected in each truck:

30 yd3 x 700 lbs. = 21,000 lbs. of waste collected per truck

truck yd3

Step 3 Calculate the number of trucks needed:

561,120 lbs. = 27 trucks (round up) 21,000 lbs./truck

Step 4 Determine the cost to travel to landfill by garbage trucks:

27 trucks x $1.50 x 40 miles = $1,620 per week week mile

Step 5 Calculate the number of long haul trucks based on residential waste generated:

281 tons = 12 trucks (round up) 25 tons per truck

Step 6 Determine cost to travel to transfer station by long haul trucks:

12 trucks x $0.75 x 45 miles = $405.00 mile per truck

Step 7 Calculate cost of transfer station:

281 tons x $15 = $4,215

ton

Step 8 Calculate cost by long haul truck:

$405 + $4,215 = $4,620

No, implementing recycle programs still leads to the collusion that the community should not build and operate a transfer station. Doing so will increase costs by:

$4,620 x 100 = 285% or 185%* higher cost $1,620

* 285%  100% = 185%