2020-11-24_HYDROLOGY - M2008082

• Permit No: M2008082
• IBM Index Class Name: Hydrology
• Doc Date: 11/24/2020
• 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 Page 2 of 9
November 24, 2020
Mining at Stage 1 was completed in July 2016. Water was delivered from Stage 1 to the river for
maintenance of Stage 1 in February 2020, decreasing the exposed groundwater surface to 2 acres.
n March and April of 2020 the pond was refilled using water delivered from Stage 2, resulting in a
current exposed groundwater surface area of 11 acres.
Mining at Stage 2 was completed by the end of 2016. RMCC performed maintenance on Stage 2
beginning in March of 2020 which reduced the surface area of Stage 2 from 12.5 to 5 acres, which
is the current exposed groundwater surface area. The pond will be refilled to a depth of 15 feet and
a surface area of 10 acres in January 2021.
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. No remaining lagged depletions
are associated with this stage.
RMCC estimates that mining at Stage 4 will be complete by the end of 2020. A slurry wall was
constructed around the Stage 4 and a 90-day leak test was approved on May 23, 2018. Once mining
is complete, RMCC plans for the construction of reservoir storage at Stage 4. Stage 4 currently
exposes 0.2 acres of groundwater which is not expected to change for this SWSP period. Additional
water will be used for dust suppression and compaction to convert Stage 4 to reservoir storage,
which construction is proposed to begin in November 2020.
A slurry wall was constructed in July 2020 for Stage 5. In October 2020, 0.2 acres of groundwater
was exposed and in November 2020 the exposed surface area is expected to increase to 1 acre which
is not expected to change for the remainder of the SWSP period.
Mining at Stage 6A was completed mid-2017. Stage 6A currently exposes a groundwater surface area
of 0.1 acres and is not expected to change for this SWSP period.
Mining at Stage 6B was completed in March of 2018. Stage 6B currently exposes 0.5 acres of
groundwater which is expected to decrease to 0.2 acres starting in January 2021 and is not expected
to change for the remainder of the 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 groundwater and is not expected to change for this SWSP period.
Mining is expected to begin again in November 2021. Stage 6C will not be lined therefore gravel
production will result in 4% by weight of water lost through mined product.
n 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 prevent the exposure of
groundwater. The current bond amount for the new Morton-Holton Lakes site is $4,150,000.00.