PERMFILE43247

• Permit No: M2001077
• IBM Index Class Name: Permit File
• Doc Name: PICEANCE PIT WATER USE CALCULATIONS
• Media Type: D
• Archive: No

• III IIIIIIIIIIIII III •
999
Piceance Pit Water Use Calculations
1) Case 1 -While Mining Operation is Active (2 years)
Water will initially be pumped at the rate of approximately 5000 gallons per minute for
a period of 30 days. Pumping will [hen be reduced for the next 11 months to a rate of
500 gallons per minute.
This rate is 662 acre-feet for the first month and 66 acre feet for each of the remaining
11 months of the year. The total amount pumped annually is therefore 1390 acre-feet.
Almost all of this amount will be pumped into a wetland which is located immediately
north of the permit area. Water from the wetland will overflow directly into the White
River, which is immediately north of the wetland, as shown on the enclosed mine map.
The following table shows the uses for the amount pumped from the pit lake. it should
be noted that these amounts are worst case.
All consumptive uses are shown below:
1) The permanent lake will be approximately 4.2 acres in size, which may fluctuate
between 3.8 acres and 4.6 acres, depending upon the river level. Since the lake bottom
and sides are always saturated due to the level of alluvial water, no losses will occur
due to infiltration. Losses will occur due to evaporation at the water surface. Based
upon evaporation data for this location from the State Engineers office and
precipitation data for this area, this pond will evaporate 2.23 acre-feet of water per acre
of water surface. This results in a consumptive use of 9.365 acre-feet annually using an
area of 4.2 acres.
2) Additional evaporation will occur as a result of mining the gravel and exposing it to
air before it is run through the crushing/screening operation and trucked off site. This
evaporation use is estimated at 4% of the annual excavated tonnage, which will be
based on a higher annual tonnage than that shown for this permit (69,500 tons per
year). The tonnage used will be 90,000 tons per year. Therefore, this consumptive use
will be 4800 tons of water per year or 2.64 acre-feet annually. It is estimated that the
gravel will contain 20% moisture when it is excavated below water level but 16%
moisture will seep back into the ground at the location, leaving 4% of the aggregate
weight mined to exit the property with the end product as a consumptive use. Since full
tonnage evaporation cannot take place at the same time that the lake is at full size, a
highest consumptive use scenario is based on the lake being at full size while the
operation is winding down in the second year, therefore, a discount of 50% is applied
to the evaporation losses associated with the gravel mined. This results in 50% of 2.64
acre-feet or 1.32 acre-feet per year.
3) Evaporation will occur as a result of pumping water into the wetland and exposing