Parameters to Calculate the Cost of Pumping Borehole Water

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What parameters are required to accurately calculate the cost of pumping borehole water?

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12 Answers

  1. Isn't everyone over complicating the answer? The cost of pumping water has nothing to do with anything except flow rate, power consumption, and electricity rate structure. The end result to answer the question is cost per unit volume or am I missing something here? 

  2. Cost Parameters to drill a bore hole include; (1) accommodation and travel of drilling crew, (2) contract rates for drilling contractor, (3) drilling method and type of equipment, (4) diameter of bore hole, depth of bore hole, (5) type and size of pump, (6) power source (electricity or diesel), (7) hours on site, (8) Materials.

  4. Basic Requirement  according to your required Flow rate and depth of water water table.

    Soil stata .

    		       

    1

    Boring for tubewell in all types of soil except shingle and rock, from ground level to 100 ft. (30 1000m) depth, including sinking and withdrawing of casing pipe, complete:-
    d)    Pipe size                                            

    2

    Boring for tubewell in all types of soil except shingle gravel & rock, from a depth of 100.1 ft. to 1000 ft. (30 to 200 m) below ground level, including sinking and withdrawing of casing pipe, complete:-
    a)      pipe size                             

    3

    Providing strong substantially built box of deodar wood 4' x 2.5' x 9" with compartments, lock and locking arrangements, for preserving  samples of strata.
    4" i/d (100 mm)  

    4

    Providing and installing, P.V.C./ Brass/GRP strainer B.S.S. Class 'B', in tubewell bore hole, including sockets and solvents, etc
    complete:-
    b) Size according to requirement

    5

    Providing and installing P.V.C./MS/GI blind pipe, B.S.S. Class `B', in tubewell bore hole, including sockets and solvents and jointing with strainer, etc. complete.
    b) 4" i/d (100 mm)

    6

    Providing and installing P.V.C. blind pipe (house), B.S.S. Class `B', in tubewell bore hole, including sockets and solvents and jointing with strainer, etc. complete.
    d) 6" i/d (150 mm)

    7

    Providing and installing P.V.C. Bail/End plug, in tubewell bore hole:-
    i) B.S.S. Class `B'
    b) 4" i/d (100 mm)

    8

    Testing and developing of tubewell of size 6" (150 mm) i/d and above continuously.
    i) upto 1.5 cs. Discharge

    9

    Providing and laying of plain cement concrete 1:2:4 with 3/4" and down size gravel including placing, compacting, finishing, curing etc  for pump foundation as per given design i/c cost of form work complete in all respects.

    )

     

    10

    Taking soil samples after every 10 feet depth or from each strata change, testing and submission of complete results of strata analysis.

    11

    Providing and installation of PVC 6"x 4" size reducer complete i/c its jointing with housing and blind pipe.

    12

    Providing and fixing of PVC cap to cover the pump housing.

    13

    Providing and fixing on the pump housing pipe of 6" dia at the location in pump foundation, as shown in the Drawing MS, Suspension Clamp of 5ft length made of 8"wide and 1/2" thick MS Flat complete with 4 No. 5/8 " dia nuts and bolts complete in all respects.

    14

    Chemical and becteriological testing of water samples. 3 Nos

    		        
             

  5. The basic items needed are flow rate, energy consumption, and cost of energy. That's all you need if you are trying to determine the cost to pump water. This will give you the cost per unit volume

    1 ) Calculate the hourly flow in Gallons, Cubic Meters, etc. per hour

    2 ) Divide the hourly power consumption in KWH by the total hourly flow, which gives KWH/Gal

    3 ) Multiply KWH/Gal * Cost of electricity in $/KWH which gives $/Gallon (or whatever unit of volume)

    This results in the wire-to-water cost including all efficiency losses.

  6. You should know the following:

    1. Static Head i.e. depth of well + height of point of delivery
    2. Yield of the bore well. With number of pumping hours possible, you can arrive at a discharge rate
    3. Delivery pipe dia / material / to calculate frictional losses to be interpreted in meters

    From this data you can arrive at the system total head.

    Calculate HP, calculate wattage and multiply it by  rate per watt-hr; or if diesel power ( generator) cost of fuel etc.

  8. 1. Static Head in metres water press= Ordinance Datum Height (ODH) of the Pipe Invert at the point of discharge minus the ODH of Water level in borehole (The Height Difference)

    2. System Head in metres of water = Calculate diameter of pipe to achieve a desired flow velocity from the desired flow rate (1m/s is reasonable), then From tables, calculation spreadsheet or software calculate the flow friction head loss equivalent for the distance of the pipeline.

    3. Total Head in metres = 1 + 2

    4. Select a borehole pump to deliver the desired flow at the Total Head, this is called The Duty Point

    5. From the manufacturers pump curves look for the Duty Point on the flow / head curve and note the corresponding absorbed power (electrical kW)

    6. Estimate the annual hours run for the pump (to achieve volume of water required) and multiply that by the Duty Point kW rating to find kWh.

    7. Find the unit price per kWh from the energy supplier and multiply by the annual kWh calculated to arrive at the cost of electricity per year. Add any standing charge costs for the electrical supply and metering.

    8. Add in some costs for pump maintenance each year to 7. to arrive at your total cost.

     

  9. The cost calculation in discharging 1 Cumec water through a pump from a borehole shall require the following;

    1. capacity of pump i.e. HP or KW
    2. duration for pumping out 1 Cumec water by pump
    3. cost per metre length of placing the casing in the borehole
    4. cost of pump and its accessories 
    5. consumption of power per second or per minute

    There are standard curves available for calculating the approximate cost of pumping from the borehole supplied by the manufacturer of the pump. 

  10. Pumping Costs

    Pumping costs for water can be computed based on the following equation:

    CAF = (K *L * PKwh)/E where:

    CAF = cost per acre-foot ($) K = number of kilowatt hours needed to lift one acre-foot of water one foot at 100 percent pump efficiency

     L = lift of water (feet) E = overall pumping efficiency

    PKwh = price per kilowatt hour of electricity ($)

  11. You could use an online calculator, such as from pump supplier Grundfos, or speak to them. I've included details below should you wish too determine / understand yourself.

    As an example a 5Ml/d flowrate (208m3/hr), with a total lift of 100m and a typical total efficiency of 0.65, has a electrical input power of 87.2kW. Used 24/7/365 (8760 hours) at £0.1/kWh, would cost £76,370 per year.

    The costs are proportional to flowrate, total lift, hours run and tariff cost. The costs will however increase ( and could double ) as efficiency reduces, which can easily happen if the pumpset is not well selected for the required flow / lift. A good engineer is required here, as a poor / simple design can also easily lead to pumpset failure.

     

    Calculations Explained in detail:

    Total Cost = Energy Cost £/kWh * Energy usage (kWh) per year.

    You will need to know:

     

    Energy usage (kWh) per year = hourly kW usage * hours of operation.

    Hourly kW usage depends upon Flowrate, Pumping Lift and total efficiency...

    Hourly kW usage (kW) = flowrate(m3/hr)*998.2/3600/1000*9.81*Total Lift(m)/System Efficiency(e.g. 0.65)

    Total Pump Lift (m) (Pumping Water Level (measured from the discharge pressure gauge) + losses in motor cooling shroud+rising main losses + discharge pressure gauge reading (static lift to discharge point + losses in the discharge pipeline)

    Total Efficiency (pump, motor, all other electrical efficiencies).

     

    This covers most items.