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<br />William J. Carter March 12, 1998
<br />Re: Response [o Susan Burgmaier's comments on the 1996 Annual Hydrologic Report
<br />mine. The readings are part of reports prepazed quarterly, and when the discrepancy was noticed, it
<br />was obviously too late to correct the error.
<br />The total gallons pumped are used to calculate an average flow rate for the week. In actual practice,
<br />the pump is controlled by a float system in the sump. When the water level in the sump reaches a
<br />certain level, the float contacts an upper limit switch, and the pump toms on. When the water level
<br />falls in the sump as a result of the pumping, the float contacts a lower limit switch, and the pump
<br />turns off. Ac[ual pumping rate to the mine water pond is over 300 gpm.
<br />The water level in the mine water pond rises and falls as the pump is fumed on and off. The flow
<br />rate at the discharge pipes from the mine water pond to Sanborn Creek varies in response to the
<br />rising and falling head in the mine water pond. The weekly field-measurement flow rate is
<br />recorded as an instantaneous flow rate at the discharge point for Outfall O1 I, in accordance with the
<br />requirements of Colorado Wastewater Discharge Permit System, Permit Number CO-0000132.
<br />The data presented in Table 2, 011 Weekly Monitoring Data for 1996, indicates an instantaneous
<br />flow rate at the time of the field-measurement monitoring on February 5, 1996 as 150 gpm, and on
<br />February 12, 1996 as 30 gpm.
<br />Sanborn Creek Mine most probably did not discharge an average of 470 gpm in one week, and [hen
<br />only discharge an average of 54 gpm in the next. The increase in flow recorded being pumped to
<br />Outfall 011 was due to this change over in pumps, not an increase in water being pumped out of the
<br />mine. Sanborn Creek Mine's policy is to present all data in its original form, rather than
<br />speculating what it should have been, and we apologize for any misunderstanding this may have
<br />caused. As can be seen by the rest of the data, the Fire Boss usually does an excellent job of
<br />recording the meter readings.
<br />Table 1. 011 Meter Readings for 1996
<br /> Meter Meter
<br /> Reading Reading Discharged Time Flow Flow
<br />Date Hour Gallons Gallons Gallons Minutes GPM MGD
<br />02-Jan-96 28,188,900 95,560,000 1,869,200 10080 185 0.267
<br />08-Jan-96 29,723,300 95,560,000 1,534,400 8640 178 0.256
<br />15-Jan-96 31,697,000 95,560,000 1,973,700 10080 196 0.282
<br />22-Jan-96 33,571,300 95,560,000 1,874,300 10080 186 0.268
<br />29-Jan-96 35,422,200 95,560,000 1,850,900 10080 184 0.264
<br />OS-Feb-96 36,337,000 99,379,800 4,734,600 10080 470 0.676
<br />12-Feb-96 36,337,000 99,927,000 547,200 10080 54 0.078
<br />19-Feb-96 36,337,000 1,783,700 1,856,700 10080 184 0.265
<br />26-Feb-96 36,337,000 3,531,700 1,748,000 10080 173 0.250
<br />04-Mar-96 36,337,000 5,420,200 1,888,500 10080 187 0.270
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<br />MINING
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