2012-02-03_HYDROLOGY - M1983090

• Permit No: M1983090
• IBM Index Class Name: HYDROLOGY
• Doc Date: 2/3/2012
• Doc Name: SWSP
• From: OSE
• To: Civil Resources, LLC
• Permit Index Doc Type: Hydrology Report
• Email Name: ECS
• Media Type: D
• Archive: No

Mine Site / Parcel
X
Distance from centroid
to the river (ft)
S
Specific Yield
T
Transmissivity
(gpd /ft)
Firestein
1,035
0.20
120,000
Tigges
3,600
0.20
120,000
Roberts
3,435
0.20
120,000
La Poudre
1,500
0.20
50,000
North La Poudre
2,500
0.20
50,000
Mr. Andy Rodriguez Page 6
Poudre Pits Aggregate Mine SWSP
January 26, 2012
Based on the information provided, there are 31.66 acres of groundwater exposed at the La
Poudre site and 13.79 acres at the North La Poudre site. All aggregate within the La Poudre and North
La Poudre Pits have been previously mined. In 2011, the only operations at the La Poudre /North La
Poudre site that consumed ground water was dust control using 1.66 acre -feet and concrete batching
which used 5.83 acre -feet. It is anticipated that operations at the La Poudre /North La Poudre site during
2012 will consume 1.66 acre -feet of water for dust control and 5.90 acre -feet of water with the
production of 47,500 cubic yards of concrete. Dewatering operations at the La Poudre and North La
Poudre sites ceased in 2003 and have a combined estimated lagged impact of 10.18 acre -feet during
2012.
The IDS AWAS stream depletion model was used to determine the lagged depletions from
evaporation, operational losses, and post dewatering operations to the Cache La Poudre River. The
aquifer characteristics used in the model are shown in the following Table.
TABLE C — AQUIFER CHARACTERISTICS
The lagged combined evaporative and operational depletions for the three sites that impacted
the river in 2011 are 185.60 acre -feet and in 2012 will be 232.54 acre -feet. The lagged combined post
dewatering operation depletions for the three sites that impacted the river in 2011 was 53.84 acre -feet
and in 2012 will be 45 acre -feet
Dewatering of the Tigges parcel commenced in June 2005 and has been continuously dewatered
since then at a rate of 500 gallons per minute. This dewatering operation has not yet reached a steady
state condition and for 2011 and 2012, dewatering accretions are projected to exceed its lagged
dewatering depletions by 120.28 and 111.61 acre -feet, respectively. These accretion credits are applied
to this plan against depletions due to post dewatering operations at the La Poudre /North La Poudre mine
sites, in addition to the Firestein and Roberts parcels. The total lagged losses to the Cache la Poudre
River attributable to this plan for 2011 and 2012 is 119.14 and 165.93 acre -feet, respectively.
Replacement
The proposed source of replacement water for this combined plan is historical consumptive use
credits available from 11 shares of the Whitney Ditch comprising 4 shares used at the Tigges farm, and
7 shares used at the Firestein farm. Historically 10 Whitney Ditch share were used on the Tigges farm
to irrigate 120 acres. Firestein farmed 134 acres with ten Whitney Ditch shares. This plan projects a
farm headgate delivery of 31.17 acre -feet per share for a total of 342 acre -feet (See Tables 8, 9 & 10).
The total consumptive use available for the 11 shares of Whitney Ditch averaged 176.65 acre -feet.
In addition to the eleven shares of Whitney Ditch water, a lease with the Town of Windsor
( "Windsor ") will be used as a replacement source during the months when there is a deficit in 2011. For
2012 a lease with the Platte River Power Authority ( "PRPA ") will be used as a replacement source during
the months when there is a deficit. Releases totaling 54.58 acre -feet were made from Kern Reservoir
(WDID 0303770 aka Windsor Lake) in 2011 as reflected in the attached Table 10. Releases totaling
97.2 will be made from the PRPA in 2012. The PRPA water will be released from Fossil Creek