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Feasibility Study Cost Estimates
©2002 Dr. Bradley C Paul
Feasibility Study Processes are actually worked out and
planned– checked for technical flaws– checked for permit flaws
Format– Pre-feasibility may give you a lot of factored cost
estimates– Start Shifting big ones to itemized cost estimates– Itemized estimates become more detailed
Feasibility Study Overviews
Major Cost Items are Identified– Quotes are secured on major cost items– Minor items tend to be listed with general
comparison cost estimates attached. Important error avoid - missing and double
counting.
Pre-Feasibility/ Feasibility Contrast
Major Cost Items from Pre-Feasibility move either to Itemized Cost format or are expanded
Example - Our Mine Shaft could easily be a big cost– Advance rate likely to be 8 feet per day using 3 eight
hour shifts in solid– Only get 2 feet day through first 200 feet of
unconsolidated– Lets Detail the crew
Shafting Crew
Typical Sinking Crew would be 5 people– 4 laborers – 1 supervisor– doing rounds, support ect. (from SERPA)– wages $15.46/hr (1997 base from WMCS)– 4*24*$15.46 = $1,484/day– Time 100 days for first 200 ft
69 days more for next 550 ft through solid rock
– 169 days at $1,484/day = $250,823– I’ll deal with supervisor later
Support People
Engineering/Technical Crew– 1 person (some would use 2) (3 for 3 shifts) SERPA– $16.15/hr 1997 cost WMCS– $388/day * 169 days = $65,504
Mechanical Crew– 2 people (6 for 3 shifts) SERPA– $20.98/hr 1997 cost WMCS– $1007/day*169 days = $170,190
Surface Crews
Surface and Yard Workers 2 Rate $11.89/hr
– 2*$11.89*24*169 = $96,452 Sinking Hoist Operator
– $16.50/hr*24*169 = $66,924
Supervisory Crews
1 supervisor/shift $23.94/hr– $23.94*24*169 = $97,101
Total Labor Cost– $746,994 say $747,000
Indexing Labor– $747,000* 17.89/16.15 = $827,500
The Burden of Burden
Workers get fringe benefits– health, vacation time etc.– government mandated programs
social security / medicare / unemployment / workers compensation
Often Expressed as a percentage of wage– Quarries around 30%– Metals commonly around 40%– Some coal may be 60%– WMCS estimates 36% for Shaft Sinking
Dropping the Burden on the Project
$827,500 * 1.36 = $1,125,000 Explosives Cost
– Rounds at 4 lbs/ton– Need to know concrete thickness
have about 15 inch thick (some squeeze for horizontal stress)
for 20 ft finished diameter - need 22.5 feet– with some over-excavation 23 feet
– Rock density about 170 lb/ft^3 35.3 tons per foot of Advance
Having a Blast
35.3 tons/ft * 4 lbs/ton = 141 lbs of explosive per foot of advance– 106,000 lbs @ $1.54/lb = $163,000
At about 1 round shot/day– 110 caps/day * 169 days = 18,590 caps– @$1.81 each = $33,650
Chord and Supplies about 50% of caps (no boosters here)– $16,824
Breaking Cost
$213,500 for explosives Drilling Consumables at about 25% of
explosives– $53,400
Breaking Cost (less labor counted elsewhere)– $267,000
Index to end 2002– $267,000 * 149.7/149.1 = $268,000
Non-Labor Mucking Costs
At $2.50/ton (include disposal)– 35.3 tons/ft * $2.5 = $88.30/ft– for 750 ft $66,216 (current cost)
Concrete Cost– 23 ft outside diam - 20 ft inside– 3.75 cubic yard per foot of advance– Concrete at $80/cubic yard delivered to site– $225,000 for concrete
Other Supplies
Steel cost at about 1.5 times concrete– $337,500– includes materials to advance utilities down shaft and
put in guides for skips Concrete and Steel
– $562,500 10% for misc supplies
– $56,250 total Supplies Subtotal $618,750
Direct Cost of Shaft
Labor $1,125,400 + Breaking $268,000 + Mucking $66,200 + Supplies $618,750
$2,078,350 10% contingency $2,286,200 15% contractor mark-up and mobilization
– $2,629,000 Note that we did consider some site specific problems with
large amounts unconsolidated Overburden and ground stresses
Pre-Feasibility / Feasibility Contrast At Order of Magnitude just scaled off of someone elses
approximate cost Pre-Feasibility was either a factored cost estimate or a
simple itemized cost estimate (ie cost per foot of shaft) At Feasibility stage it became a much more carefully
itemized exercise– we were still flakey on cost of service lines pipes
As move to Budget Authorization likely bring in contractors to bid specifically on the job