2011-05-13_HYDROLOGY - M1977439

• Permit No: M1977439
• IBM Index Class Name: HYDROLOGY
• Doc Date: 5/13/2011
• Doc Name: Combined Substitute Water Supply Plan
• From: OSE
• To: Applegate Group, Inc.
• Permit Index Doc Type: Hydrology Report
• Email Name: ECS
• Media Type: D
• Archive: No

Mr. Jared Dains Page 2
May 11, 2011
The exposed surface area at all three sites has been updated based on the current
conditions for each site. For the Home Office Pit the surface area exposed after December 31,
1980 increased from 77.7 to 140.9. The 13 acres previously identified as being exposed at the
North Taft Hill Expansion Site have never been fully exposed, therefore according to the
information provided the current exposed surface area at this site is only 2.3 acres. The exposed
surface area at the Overland Ponds is from the dewatering trenches around the pit which total to
11.3 acres based on estimated width of 10 feet.
During the term of this plan, the only consumptive use at the North Taft Hill Expansion Site
and the Overland Ponds Site is the evaporation from exposed ground water. The consumptive
use at the Home Office site will be from evaporation of exposed ground water and water used for
dust control.
Depletions
The total losses for the sites are shown in the following table:
TABLE B - LOSSFS
Total
Evaporation Lost in Dust Lagged

Site Name
Losses
Product
Control Total
Stream New Permit
(ac-ft) (ac-ft) (ac-ft) (ac-ft) Depletions Required?
ac-ft
Home Office Pit 300.33 0.0 2.14 302.47 300.43 Yes
Overland Ponds

Site 24.09 0.0 0.0
24.09 23.69 Yes
North Taft Hill

Expansion Site 4.90 0.0 0.0
4.90 5.27 No
Total 329.32 0.0 2.14 331.46 329.39
The estimate of evaporative losses under this combined plan was reduced during the ice
covered period. You have assumed the ice covered period occurs from December through
February, based on the average temperatures of 29°F for December, 27°F for January and 31 °F
for February; taken from the Fort Collins weather station (053005) using available data through
2005. The ice covered periods may be used to reduce the amount of evaporative losses that need
to be replaced; however, for the purpose of this SWSP, the Applicant shall replace the net
evaporation depletions from the exposed ground water surface area that may occur during the
assumed ice covered period (December through February) for any time that the pits are not
completely covered by ice.
Computation of the net evaporation during any time that the pits are not completely
covered by ice shall be determined as the pro-rata amount of the monthly gross evaporation rate