SPREADSHEET FOR GENERALIZED CALCULATION OF ANNUAL PUMPING AND AMORTIZATION COSTS
Dr. William M. Turner
http://www.agwconsultants.com senatorbil@aol.com
Download this spreadsheet in MS Excel '97 for Windows format. The spreadsheet is available in English or Metric units. Be sure to use consistent decimal currency units. You can also view a graph of this table (35 kb). The headings marked in Bold are variables. The headings in regular text are constants. Use the downloaded spreadsheets to examine your situation, and see how much difference the transmissivity will make in cost.
Please contact us with your results:
| Hydraulic Conductivity | ft/d | 67 | 134 | 201 | 267 | 334 | 401 | 668 | 1337 |
| Aquifer Transmissivity | USgpd/ft | 50000 | 100000 | 150000 | 200000 | 250000 | 300000 | 500000 | 1000000 |
| Final Aquifer Transmissivity | USgpd/ft | 18370 | 66195 | 115498 | 165003 | 214620 | 264306 | 463428 | 962237 |
| Storage Coefficient | fraction | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Static Water Level | ft | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Well Diameter | ft | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| Length of Original Water Column | ft | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 |
| Length of Final Water Column | ft | 37 | 66 | 77 | 83 | 86 | 88 | 93 | 96 |
| Drawdown | ft | 63.26 | 33.81 | 23.00 | 17.50 | 14.15 | 11.90 | 7.31 | 3.78 |
| Total Lift | ft | 163 | 134 | 123 | 117 | 114 | 112 | 107 | 104 |
| Pumping Period | yrs | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Design Pumping Rate | USgpm | 1500 | 1500 | 1500 | 1500 | 1500 | 1500 | 1500 | 1500 |
| Total Water Requirement | af/yr | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 |
| Total Water Requirement | USgpm | 6190 | 6190 | 6190 | 6190 | 6190 | 6190 | 6190 | 6190 |
| Electric Power Cost | Local/kwh | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| Diesel Fuel Cost | Local/USgal | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Gasoline Fuel Cost | Local/USgal | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Overall Pump Efficiency | fraction | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 |
| Motor Efficiency | fraction | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 |
| Pump Horsepower | BHP | 88 | 72 | 67 | 64 | 62 | 61 | 58 | 56 |
| Interest Rate | % | 7.5 | 7.5 | 7.5 | 7.5 | 7.5 | 7.5 | 7.5 | 7.5 |
| Period of Amortization | yrs | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 |
| u | none | 5.729E-09 | 2.880E-09 | 1.920E-09 | 1.440E-09 | 1.152E-09 | 9.600E-10 | 5.760E-10 | 2.880E-10 |
| W(u) | none | 18.40 | 19.67 | 20.07 | 20.36 | 20.58 | 20.76 | 21.27 | 21.97 |
| Drawdown | ft | 63.26 | 33.81 | 23.00 | 17.50 | 14.15 | 11.90 | 7.31 | 3.78 |
| Hourly Pumping Cost Per Well | Local | 9.42 | 7.72 | 7.09 | 6.78 | 6.58 | 6.45 | 6.19 | 5.98 |
| Minimum Annual Pumping Cost Per Well | Local | 82,476 | 67,595 | 62,137 | 59,357 | 57,667 | 56,528 | 54,213 | 52,425 |
| Minimum Annual Total Pumping Cost | Local | 618,567 | 337,976 | 310,687 | 296,787 | 288,335 | 282,641 | 271,063 | 262,127 |
| New Well Costs Per Foot | Local | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 |
| Minimum New Well Cost | Local | 21,307 | 21,042 | 20,070 | 19,575 | 19,274 | 19,071 | 18,658 | 18,340 |
| Wells Required Because of Excessive Drawdown | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
| Wells Required to Meet Demand | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | |
| Number of Required Wells | 8 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | |
| Annual Amortization Cost | Local | 39,950 | 26,303 | 25,088 | 24,469 | 24,092 | 23,839 | 23,323 | 22,925 |
| Annual Operation & Amortization | Local | 618,567 | 337,976 | 310,687 | 296,787 | 288,335 | 282,641 | 271,063 | 262,127 |
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