2021-08-02_PERMIT FILE - M2020058 ‎(6)‎

• Permit No: M2020058
• IBM Index Class Name: Permit File
• Doc Date: 8/2/2021
• Doc Name: Completeness Response
• From: Aggregate Industries - WCR, Inc.
• To: DRMS
• Email Name: DC1
• Media Type: D
• Archive: No

Mr. Daniel Cunningham
RE.•Baurer Pit M-2020-058
July 27, 2021
3. Dewatering pumps from the Baurer Pit will discharge into the Stillwater Ski Lake. The
discharges have been illustrated on the revised Exhibit C-5, Pre-Mining/Mining Plan Map.
4. The Stillwater Ski Lake will receive all discharge from the Baurer Pit dewatering. Since the
slurry wall is expected to be installed prior to mining, it is anticipated that dewatering
discharge will be minimal and temporary. The ski lake has more than sufficient capacity to
receive the dewatering discharge. The lake also has a natural overflow into the Huett
Seepage Ditch which runs north out of the lake and the ditch also has capacity to handle all
dewatering flows.
If, however, the Stillwater Ski Lake and/or Huett Seepage Ditch are suspected to be
over-capacity due to the dewatering flows, the dewatering discharge can be routed directly to
the South Platte River through the Wattenberg Lakes site (M-2004-051). These discharge
locations are/will be included in the Aggregate Industries — WRC, Inc. Colorado Department
of Public Health and Environment discharge permit.
5. The conveyor corridor that will receive material from the Baurer Pit is included in the
Aggregate Industries—WCR, Inc. Wattenberg Lakes site, M-2004-051.
6. The 1,500 feet specified on page 7 includes 500 feet of mining face highwall plus 500 feet of
mining cell side walls on each side of the mine face; for a total of 1,500 feet near vertical
highwalls. This is also explained in Exhibit L, Reclamation Costs.
6.4.5 Exhibit E— Reclamation Plan
7. On-site access following reclamation shall primarily include an un-improved access road
following the slurry wall around the outside of the reservoir. This access road has been
illustrated on the revised Exhibit F, Reclamation Plan Map.
8. The existing topsoil on-site is limited to the undisturbed east half of the affected area. All
topsoil recovered during mining of the Baurer Pit will be stockpiled and used for
reclamation. However, with the average and/or total quantity of topsoil on-site unknown, the
conservative estimate of 6 inches has been proposed.
9. Aggregate Industries —WCR, Inc. will submit a technical revision prior to importing inert fill
onto the site in accordance with Rule 3.1.5(9).
6.4.7 Exhibit G—Water Information
10. Aggregate Industries —WCR, Inc. shall submit quarterly groundwater elevation data with the
associated annual report. If groundwater elevations change significantly (rise or fall more
than 2 feet) from seasonal norms during the year, evaluations of the data and potential
causes/mitigations shall also be included with the annual report.
11. Baseline groundwater elevation data is provided in the attached table and corresponding
chart, Baurer Pit Groundwater Monitoring Data. At this time, five (5) to six (6) piezometers
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