Answer to Question #317060 in Civil and Environmental Engineering for Tiara

Question

The city of a population of 161,565 has requested to evaluate its solids waste collection system.

Determine:

i) mean time per collection stop plus the mean time to reach the next stop,

ii) number of pickup locations per load

iii) minimum number of trucks the city must own.

Consider the following data:

a) Average truck capacity =18 m3

b) Average observed compaction ratio =3.28

c) Crew size = 2 persons

d) Number of pickups = 1/week (no rear-of-house service)

e) Average number of residence per stop= 2.5

f) Average uncompact density = 122 kg/m3

g) Average transport time to disposal site including delay and dumping = 1.5 h/trip

h) Average number of trips to disposal site =2/day

i) Rest breaks = 2 at 15 min

j) Average maintenance downtime = 36 min/day

k) Average work day = 8 hours

l) Average percentage of truck out of service for majority repairs = 15%

m) Average number of cans per stop = 2.5/wk at 0.0911 m3/can

Answer 1

i.) mean time per collection stop plus the mean time to reach the next stop

V_p = (Average number of cans per stop) $\times$ (Volume per can)

V_{p =} 2.95 $\times$ 0.0911

V_p = 0.2689 m³/stop

ii.) number of pickup locations per load

N_p = Number of pickups $\times$ Average number of residence per stop $\times$ Average number of trips to disposal site

N_p = 1$\times$ 2.5 $\times$ 2

N_p = 5

iii.) minimum number of trucks the city must own

N_t = Number of pickups$\times$ Average number of residence per stop

N_t = $1\times2.5$

N_t = 3 trucks