2016-01-20_HYDROLOGY - M2001085

• Permit No: M2001085
• IBM Index Class Name: Hydrology
• Doc Date: 1/20/2016
• Doc Name: Substitute Water Supply Plan
• From: DWR
• To: DRMS
• Email Name: TOD
• Media Type: D
• Archive: No

Mr. Craig Lis Page 2 of 5
GSL Sand and Gravel SWSP
January 20, 2016
the exposed ground water surface area from 26.7 acres to 16.05 acres. It is assumed the 16.05-acre
pond has existed since that time. Net evaporative depletions were calculated using a gross annual
evaporation of 45 inches from the exposed water surface, with a credit of 10.8 inches for effective
precipitation. The net depletion of ground water due to evaporation of ground water exposed at the
site has been calculated to be 45.91 acre-feet for each year of the approval period for this SWSP.
The mining depletion from January 2009 through October 31, 2018 are shown in attached Table 2.
The Alluvial Water Accounting System ("AWAS") model was used with the alluvial aquifer boundary
condition option to lag depletions to the South Platte River. The following parameters were used in
the model:
Location X - Dist to river W - Boundary Harmonic Specific yield
(feet) Dist (feet) Transmissivity
(gpd/ft)
Gravel Mine (mining and 2,295 3,836 63,000 0.2
dewatering depletions)
Henderson Water Ski Lake 1,808 5,300 61,600 0.2
(recharge)
Evaporative and operational losses were considered back to January 1, 2009 because depletions
during this time period may still be impacting the river. Lagged evaporative and operational
depletions are 46.95 acre-feet for November 2015 through October 2016 and 45.98 acre-feet for
November 2016 through October 2017, as shown on the attached Table 4.
Dewatering depletions and accretions were also considered back to January 1, 2009. The net
dewatering credit to the stream (lagged dewatering accretions minus lagged dewatering depletions)
are 0.31 acre-feet for November 2015 through October 2016 and 0.07 acre-feet for November 2016
through October 2017 as shown on the attached Table 4.
Replacements
The replacement source for this plan period is fully consumable water leased from the City of Aurora
("Aurora"). The fully consumable water will be released to the South Platte River at the outfall of
the Metro Wastewater Reclamation District's Robert W. Hite treatment facility ("Metro Sewer,"
WDID 0207000). Metro Sewer is located approximately 10.78 miles upstream of the site. As such an
irrigation season transit loss of 5.39% (0.5% per mile) and a non-irrigation season transit loss of 2.7%
(0.25% per mile) will be assessed on all releases. These transit losses are subject to change by the
water commissioner or division engineer. The proposed replacement schedule is provided in Table 6.
A copy of the signed lease agreement dated April 29, 2013 is attached.
Long-term Depletions
The final reclamation plan for DRMS Mining Permit No. M-2001-085 once had been to create a water
storage reservoir through the installation of a slurry wall. The slurry wall was constructed but did not
receive its liner approval from DWR. Based on the Applicant's statements, the slurry wall leaked in
multiple locations and the pit filled completely with ground water. This was not in accordance with
their DRMS permit reclamation requirements. At this time the Applicant has decided to abandon
earlier considerations for both (1) repairing the liner and selling the pit as a water storage reservoir
(per their original DRMS permit) and (2) pursuing an augmentation plan to cover the long-term
depletion requirements, and now plans simply to backfill the pit.