2020-02-13_HYDROLOGY - M2008082

• Permit No: M2008082
• IBM Index Class Name: Hydrology
• Doc Date: 2/13/2020
• Doc Name: Substitute Water Supply Plan
• From: DWR
• To: DRMS
• Email Name: ECS
• Media Type: D
• Archive: No

Ready Mix Concrete Substitute Water Supply Plan
February 13, 2020
Page 2 of 10
Mining of the Morton-Holton Lakes site is presently expected to last up to fifteen years.
The current mining plan for the site is shown in attached Figure 1. The replacement of
depletions for Morton-Holton site is fully consumable water leased from the City of
Aurora.
Mining at Stage 1 was completed in July 2016. The exposed groundwater surface area
within Stage 1 is currently 11 acres. Water will be delivered from Stage 1 to the river for
maintenance of Stage 1 in February 2020, which will decrease the exposed groundwater
surface area to 2 acres. It is expected that in March 2020 the pond will refill again
resulting in 11 acres of exposed groundwater.
Mining at Stage 2 was completed by the end of 2016. The exposed groundwater surface
area within Stage 1 is currently 12.5 acres and is filled to a depth of 20 feet. RMCC plans
to perform maintenance on Stage 2 and reduce the surface area of Stage 2 by 5.5 acres by
March 2020 and then further reduce the surface area by another 2 acres in April 2020.
Mining at Stage 6A was completed mid-2017. Stage 6A currently exposes a groundwater
surface area of 0.1 acre and is expected to remain at 0.1 acre.
Mining at Stage 6B was completed in March of 2018. Stage 6B currently exposes a ground
water surface area of 2 acres and is expected to decrease slightly to a groundwater
surface area of 1 acres in by July 2020.
Mining at Stage 3 began in June 2017 and was completed in early 2018. Stage 3 was
completely backfilled in the spring of 2019 with overburden from other stages.
RMCC estimates that mining at Stage 4 will continue through the middle of 2020. A slurry
wall was constructed around the Stage 4 and a 90-day leak test was approved on May 23,
2018. Stage 4 currently exposes 0.5 acre of ground water and is not expected to change
for this SWSP period.
Mining at Stage 6C/6D began in 2019 following the installation of the slurry wall. Stage
6C/6D currently exposes 0.5 acre of ground water and is expected to remain the same
through this SWSP period
A slurry was will be constructed for Stage 5 during this SWSP period.
In accordance with the letter dated April 30, 2010 (copy attached) 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.
The DRMS letter identified four approaches to satisfy this requirement.
In accordance with approach nos. 1 and 3, you have indicated that a bond has been
obtained for the new Morton-Holton Lakes site that can cover the cost of lining, to