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