QUESTION FOUR $[10$ MARKS$]$

A city needs increasing its rubbish disposal facilities. There is a choice of two rubbish disposal areas, as follows:

Area A: A gravel pit with a capacity of $16$ million cubic meters. Owing to the possibility of high groundwater, however, the Regional Water Pollution Control Board has restricted the lower $2$ million cubic meters of fill to inert material only $($earth$,$ concrete, bricks, etc.$).$ The inert material, principally clean earth, must be purchased and hauled to this area for the bottom fill.

Area B: Capacity is $14$ million cubic meters. The entire capacity may be used for general rubbish disposal. This area will require an average increase in travel distance by $60\%,$ which is three$-$quarters of the round$-$trip distance, and a decreased return by $20\%$ on the remaining round$-$trip distance.

$3$

Assume the following conditions:

Cost of inert material placed in Area A will be $$\frac{1\mathrm{.}35}{m^3}.$

The truck can travel three times the round$-$trip distance in an hour.

The rubbish truck and two$-$man crew will cost $$25$ per hour.

Truck capacity is $4\mathrm{.}5$ tons per load or $20m^3.$

Sufficient cover material is available at all areas; however, inert material for the bottom fill is Area A must be hauled in$.$

Use the information provided to answer the following questions:

a$)$ Which Engineering Economics Principle should be utilized in the formulation of the solution to this problem to avoid redundant computations?

$[2\mathrm{.}5$ Marks$]$

b$)$ Which site do you recommend? Provide calculations to support your recommendation.

$[7\mathrm{.}5$ Marks$]$