2015-07-09_HYDROLOGY - M1977439

• Permit No: M1977439
• IBM Index Class Name: HYDROLOGY
• Doc Date: 7/9/2015
• Doc Name: Combined Substitute Water Supply Plan
• From: Div of Water Resources
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

Upper Poudre Combined SWSP Page 2 of 11
June 26, 2015
the Partners Combined SWSP, they are within MMM's DRMS mining permit for the Home Office Pit and
thus final reclamation liability remains with MMM as the Home Office Pit permit holder.
The Overland Pond Site is currently active. The site is made up of five individual cells. The
liner for cell 1 was approved on October 5, 2011, the liner for cell 2 was approved on December 16,
2013 and re -approved (after intentional breaching) on May 13, 2015, the liner for cell 3 was approved
on December 10, 2014, and the liner for cell 4 was approved on March 6, 2015. Cell 5 was lined prior
to any mining and therefore will not expose any ground water prior to or during the mining process;
however the liner has not been approved by this office. Since all five cells have been lined, there is
no longer any ground water exposed at the Overland Ponds Site. Please note that until the liner for
cell 5 is approved by this office, any water exposed within the lined perimeter must be treated
as ground water with evaporation losses assessed.
The North Taft Hill Expansion Site is proposed to be mined during this plan period. In
December 2014 the site was dewatered in preparation of mining. As a result, the 5.07 -acre pond was
dried up and ground water is currently only exposed in the 2.45 -acre pond and a dewatering trench
approximately 5 feet wide and 5,250 feet long (0.60 acres).
See Figure 1 for the location and boundaries of the subject mining sites.
Depletions
During the term of this plan, consumptive use at the Home Office Pit will consist of
evaporative depletions from exposed ground water and water pumped for dust control; consumptive
use at the Overland Ponds Site will be limited to water lost with the mined product; and consumptive
use at the North Taft Hill Expansion Site will consist of evaporative depletions from exposed ground
water and water lost with the mined product. The total depletions for the subject sites are shown in
Table B below.
Table B - Depletions
Pursuant to S 37-90-137(11)(b), C.R.S. and 2009CW49, a gravel pit operator or property owner
does not need to replace depletions that occur due to evaporation from ground water exposed prior
to January 1, 1981 as a result of open mining of sand and gravel ("pre -81 areas"), regardless of
whether mining continued after December 31, 1980. This SWSP recognizes a total of 100.0 acres at
the Home Office Pit as being pre -81 exposure. Of the 100 acres, 22.1 acres are within Lamb Lake A
as reflected in the Partners Combined SWSP for their portion of the Home Office Pit. Therefore, for
MMM's SWSP, 77.9 acres are recognized as being pre -81. Per our "General Guidelines for Substitute
Water Supply Plans for Sand and Gravel Pits" updated April 1, 2011, pre -81 areas are tied to the
physical location at which the groundwater was exposed prior to January 1, 1981 with the exception
for areas whose reallocation was approved by the State Engineer prior to January 1, 2011. Previous
Evaporation
Lost in Mined
Dust
Total
Total Lagged
Site Name
Losses
Product
Control
(ac -ft)
Stream Depletions
(ac -ft)
(ac -ft)
(ac -ft)
(ac -ft)
Home Office Pit
32.40
0.00
29.46
61.86
61.57
Overland Ponds Site
0
6.06
0.00
6.06
8.33
North Taft Hill
6.29
14.89
0.00
21.19
19.83
Expansion Site
Total
38.69
20.95
29.46
89.11
89.74
Pursuant to S 37-90-137(11)(b), C.R.S. and 2009CW49, a gravel pit operator or property owner
does not need to replace depletions that occur due to evaporation from ground water exposed prior
to January 1, 1981 as a result of open mining of sand and gravel ("pre -81 areas"), regardless of
whether mining continued after December 31, 1980. This SWSP recognizes a total of 100.0 acres at
the Home Office Pit as being pre -81 exposure. Of the 100 acres, 22.1 acres are within Lamb Lake A
as reflected in the Partners Combined SWSP for their portion of the Home Office Pit. Therefore, for
MMM's SWSP, 77.9 acres are recognized as being pre -81. Per our "General Guidelines for Substitute
Water Supply Plans for Sand and Gravel Pits" updated April 1, 2011, pre -81 areas are tied to the
physical location at which the groundwater was exposed prior to January 1, 1981 with the exception
for areas whose reallocation was approved by the State Engineer prior to January 1, 2011. Previous