PERMFILE134556

• Permit No: M2000110
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2000
• Doc Name: CONSTRUCTION MATERIALS REGULAR 112 OPERATION RECLAMATION PERMIT APPLICATION FORM
• Media Type: D
• Archive: No

2. Proposed Post December 1980 Groundwater Evaporation Depletions
Gross free water surface evaporation has been calculated based upon the evaporation
atlases in NOAA Technical Report N~VS 33 for Monte Vista, Colorado. The town of Monte
Vista lies two miles south of the proposed mining site. The average elevation for the mining site
is 7,645. The total gross evaporation estimate from the NOAH 33 estimate has been distributed
to all months in the proportions specified by the General Guidelines for Substitute Supply Plans
for Sand and Gravel Pits including periods when ice cover occurs. This analysis is shown in Table
1 below. The net pond evaporation was calculated as the gross pond evaporation less effective
precipitation. Effective precipitation was estimated as 70% of the total average annual
precipitation for Monte Vista, Colorado. A consumptive use credit from imgated pasture on the
land that is to be replaced by the gravel pits has not been subtracted from the net pond
evaporation as it shall be treated separately in the following section as land to be dried up.
- - From the NOAA 33 guidelines it is estimated that average annual net pond evaporation_is --
43.88 inches per acre or 3.66 acre-fl per acre of pond surface area. It should be note~_that
because of the inclusion of evaporation during the winter months when the ponds are frozen over,
this evaporation rate is 17% higher than the estimate that was approved in 96CW3 for the
Mathias gravel pit immediately adjacent to this proposed location.

Month Gross Evap
Distribution
Factor NOAH
Gross Pond
Evap
in/acre
Total
Precip
inlacre
Effective
Precip
in/acre NOAH
Net Pond
Evap
in/acre
Janua 1.0% 0.49 0.22 0.15 0.34
Februa 3.0% 1.47 0.25 0.18 1.30
March 6.0% 2.94 0.41 0.29 2.65
ril 9.0% 4.41 0.40 0.28 4.13
Ma 12.5% 6.13 0.52 0.36 5.77
June 15.5°ib 7.60 0.53 0.37 7.23
Jul 16.0% 7.84 1.30 0.91 6.93
u ust 13.0% 6.37 1.29 0.90 5.47
Se tember 11.0°.'0 5.39 1.00 0.70 4.69
October 7.5% 3.68 0.59 0.41 3.27
November 4.0% 1.96 0.42 0.29 1.67
December 1.5% 0.74 0.41 0.29 0.45
OTAL 100.0% 49.02 7.34 5.14 43.88
Table I . Estimate of Pond Evaporation