2018-08-08_HYDROLOGY - M1986015

• Permit No: M1986015
• IBM Index Class Name: Hydrology
• Doc Date: 8/8/2018
• From: DWR
• To: DRMS
• Email Name: ERR
• Media Type: D
• Archive: No

Mr. Paul Bruss, P.E.
August 8, 2018
Page 3 of 7
Annual site depletions during the second plan year (August 1, 2019 through July 31, 2020)
consist of 296.07 acre-feet of gross evaporative losses, 11.0 acre-feet of pumping for dust
control, and 7.38 acre-feet of water removed in the mining product, for a total depletion of
314.45 acre-feet. The monthly distribution of the values and the lagged effects on the
Arkansas River, are detailed on your Tables 1-4, which are attached. The lagged depletions
were calculated individually for each Phase of the operation based on the characteristics
below.
Location
T(d/ft)
S
X (ft)
W (ft)
Phase 1
97,100
0.15
1,032
2,647
Phase 1 (initial till)
97,100
0.15
180
2,334
Phase 2
97,100
0.15
964
21206
Phase 7
97,100
0.15
420
2,250
T = Transmissivity of the aquifer (gallons per day per foot).
S = Specific yield of the aquifer,
X Distance between the centroid of the mining area and the Arkansas River (feet).
W = Distance between the Arkansas River and the alluvial boundary (feet). Z
We note that the W distance value for the Phase 1 and Phase 1 (initial fill) lagging inputs are different due
to do the different locations for the point of depletion and the variability of the alluvial boundary in the
location of the Pueblo East Pit.
Lagging factors for each of the Phases were calculated using the Glover Method, normalized
to the number of months required for 95% of depletions to affect the river, and are provided
in the following table.
Month
Phase 1
Phase 1
Phase 2
Phase 7
1
49.15%
91.20%
54.46%
76.62%
2
34.43%
8.80%
36.62%
19.16%
3
11.76%
-
8.92%
4.22%
4
4.65%
-
-
-
Total
100.00%
100.00%
100.00%
1.00.00° O
Note: Lagging factors a.re normalized to the number of months required
for 95% of depletions to affect the river.
Historical phreatophyte and effective precipitation were determined to partially offset gross
evaporation at the site. The credit from historical phreatophyte consumptive use was
calculated to be 19.5 acre-feet per year from 5.6 acres of equivalent 100% canopy cover
native vegetation in Phase 1, and 17.5 acre-feet per year from 5 acres of 100% canopy cover
native vegetation in Phase 7. Effective precipitation was claimed on the remaining 60.4 acres
of exposed surface area, and was calculated as 70% of precipitation.
REPLACEMENT
The replacement water is proposed to be from three sources. The first is excess credits from