2018-10-19_REVISION - M1980244

• Permit No: M1980244
• IBM Index Class Name: Revision
• Doc Date: 10/19/2018
• Doc Name: Adequacy Review Response
• From: CC&V
• To: DRMS
• Type & Sequence: TR101
• Email Name: TC1
• Media Type: D
• Archive: No

Knight Piesold Knight Piesold and Co.
C O N S U L T I N Cs 1999 Broadway, Suite 600
Denver, Colorado 80202-5706 USA
Telephone: [phone]
Facsimile: [phone]
October 8, 2018
Cripple Creek and Victor Gold Mining Co. (Newmont) KP Project No.: DV1 01-00408/03
100 North 31d Street KP Doc. No.: DV-18-1131
PO Box 191
Victor, Colorado 80860
Attn: Environmental Department, Meg Burt, Senior Manager
Subject: Cripple Creek and Victor Mine
Stormwater Management Plan Evaluation — Review Findings, EMP 22 and ECOSA Facility
Toe Berm Design Upgrades
Revision 4
Dear Meg:
This letter presents the findings of the Stormwater Management Plan (SWMP) infrastructure review
performed by Knight Piesold and Co. (Knight Piesold) for Cripple Creek and Victor Gold Mining Co.
(CC&V), a subsidiary of Newmont Mining Corporation (Newmont). Specifically, this revision addresses the
comments received from the Colorado Division of Reclamation, Mining and Safety (DRMS) on July 26,
2018, which are included as Attachment 1 of this document.
The review was performed based on observations made during the site visit on February 20, 2018,
information provided by CC&V, and analyses performed by Knight Piesold. The emphasis of the review
was focused on the enhanced management practices (EMPs), or engineered stormwater management
ponds, and the associated spillways and contributing diversion channels (DC). Specifically, the following
aspects of the SWMP infrastructure were evaluated:
• Facility layouts: Locations, alignments, profiles, and cross-section dimensions.
• Design criteria: Recurrence interval storm events for conveyance and storage.
• Hydrologic analyses: Stormwater peak flow rates and volumes.
• Hydraulic analyses: As-built capacities and erosion protection measures.
The analyses performed by Knight Piesold were used to evaluate if the existing SWMP infrastructure
adheres to the design criteria. This evaluation compared the peak flows and runoff volumes estimated by
Knight Piesold (based on the established design criteria) to the as-built hydraulic capacities. Where it was
found that a structure is undersized (i.e., identified design gap), Knight Piesold provided an updated
feasibility study (FS) level design to CC&V that adheres to the design criteria.
The required design upgrades were largely presented to CC&V in a separate design report. However, this
document presents the required design upgrades for the following structures for the stated reasons:
• East Cresson/\/Vild Horse Overburden Storage Area (ECOSA) facility toe berm: Included in response to
the DRMS comments received on July 26, 2018.
• EMP 22, also known as the Chicago Tunnel Site Detention Pond: Included because CC&V committed
to these upgrades as part of the Permit No. M-1980-244 Amendment 11 process with the DRMS.
Management system cedr%d by
BSI -
ISO 9001-FS 5SW61
ISO 14001-EMS 585862
OHSAS 18001-OHS 58503