2020-08-28_HYDROLOGY - M2000041

• Permit No: M2000041
• IBM Index Class Name: Hydrology
• Doc Date: 8/28/2020
• Doc Name: Substitute Water Supply Plan
• From: DWR
• To: DRMS
• Email Name: JPL
• Media Type: D
• Archive: No

Dan Mathes
August 28, 2020
Page 2 of 5
In accordance with the letter dated April 30, 2010 from the Colorado Division of
Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators must
comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and
Regulations for the protection of water resources. The April 30, 2010 letter from DRMS
requires that you provide information to DRMS to demonstrate you can replace long term
injurious stream depletions that result from mining related exposure of groundwater. A
reservoir liner, constructed to prevent the infiltration of tributary groundwater, was most
recently inspected by our staff on July 10, 2019. The testing plan and leak test were
found to be adequate. All water inflows and outflows for this site must be accounted for
on at least a monthly basis, by the 10th of the month following the accounting. According
to the Acceptance of Financial Warranty letter written by DRMS on November 25, 2019
(available from the DRMS website at the following link:
https://dnrweblink.state.co.us/drms/o/doc/1292174/Pagel.aspx?searchid=Oea88c20-a655
-4cd5-a308-608d23fc0a65), Fremont Paving currently holds a bond in the amount of
$1,955,780 for reclamation at the site.
DEPLETIONS
Well permit no. 54064-F (WDID 1406561) was obtained to expose water in this pit.
Depletions under this plan consist of evaporation from 2.43 acres of exposed groundwater
within Phase I-Parcel 4 of the mine site. The total of 2.43 acres of exposed groundwater
will result in evaporative losses of 8.38 acre-feet (see attached Table 1) under this SWSP.
A Glover analysis was used to create unit response function ("URF") in order to determine
the lagged depletions to the Arkansas River using the following parameters:
• Transmissivity - 100,000 gallons/day/foot
• Storage Coefficient - 0.20
• Distance to the Stream - 2,090 feet
• Distance to No-Flow Boundary - 5,460 feet
The resulting URF shown below was calculated by wrapping the last 5% of depletions into
the first 16 months.
Month 1 2 3 4 5 6 7 8 9 10 11 12
Fraction of 0.15 0.25 0.13 0.08 0.06 0.05 0.04 0.04 0.03 0.02 0.02 0.02
Pumping 0 2 8 6 9 5 8 1 3 9 4 1
Month 13 14 15 16 17 18 19 20 21 22 23 24
Fraction of 0.01 0.01 0.01 0.01
Pumping 7 4 2 1
Based on the lagging described above and as shown in Tables 1-4, attached, lagged stream
depletions occurring during this SWSP plan year were determined to total 8.39 acre-feet.