You are an estimator for a site contractor.
• You are bidding a project that includes the blasting of approximately 50,000 BCY of
• You are planning on setting up a crushing plant on site.
• The plant will make the structural fill required to be placed under the proposed parking
lots and buildings.
• The ideal location of the crushing plant will be 2,000 feet from the location of the
• The rock must be drilled, blasted, loaded, hauled, and crushed.
• Off road end dump trucks ($80/hr) will be used to haul the material from the blast area
to the crushing plant, their capacity is 45,000 lbs.
• Your firm will construct the haul road to your specifications.
• A large excavator will load the trucks ($200/hr)
• The rock averages 15 feet depth.
• Your blasting costs are: Blaster $58/hr
The powder factor is 0.75 lb/BCY
• The hole must be drilled to 16.5 feet for an effective depth of 15 feet.
• A ten foot square drill pattern will be used.
• The average drilling rate is 100 ft/hr.
• The crushing plant has a primary jaw crusher and a secondary cone crusher.
• The crusher production is 100 tons/hr.
• Another large excavator feeds the crusher.
• The crushing plant cost is $500/hr
• The cost of the operator is included in each cost.
• Determine the unit cost of the material produced by the crusher.
• An alternative is to purchase structural fill from an offsite supplier for a cost of
$19/LCY delivered. The supplier of the structural fill will pick up the blast rock for no
charge. You will have to load his trucks. Is this alternative worth taking advantage
of? Would you impose any conditions on the supplier?