NC0003433_Acceptance of Request to Delay-Scope 3 State Dam ID CHATH-05_20170503

ROY COOPER
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MICHAEL S. REGAN
Energy, Mineral Secteta,y
and Land Resources
ENVIRONMENTAL QUALITY TRACY DAVIS
Du ectot
May 3, 2017
Mr. George T. Hamrick
Senior Vice President
Duke Energy
400 S. Tryon Street, ST06A
Charlotte, NC 28202
RECEIVED, I'JCDEQlDWR
RE- Acceptance of Request to Delay— Scope 3 MAY 0 7 1017
Cape Fear 1956 Ash Pond (Inactive)
Chatham County %Nater Quality
State Dam ID: CHATH-075 Permitting Section
Dear Mr. Hamrick:
This is in response to your letter dated September 27, 2016, received by this office on September
27, 2016 via e-mail transmittal of an engineering evaluation document requesting to delay
vegetation removal from the subject dam. This dam is of high hazard classification.
As background, completion of the vegetation removal was to be completed and as -built drawings
submitted by December 31, 2016, under Dam Safety Order DS 16-01, issued by this Division on
August 22, 2016. The Certificate of Approval for the proposed Scope 3 Vegetation Removal
was issued September 10, 2015, with several stipulations including periodic monitoring
requirements. Subsequently, Duke Energy submitted to DEMLR a request to delay vegetation
removal until such time as full removal of vegetation from the dam and basin areas may be
accomplished as part of an approved decommissioning and closure plan stated in your letter
dated June 27, 2016. The engineering certification dated September 23, 2016 asserts that this
approach would allow for better efficiency in the tree removal process and will lessen the risk
posed by operation of large scale tree removal equipment along the banks of the adjacent Cape
Fear River. It further asserts that removal of vegetation after the dewatering process is
appropriate and can be accomplished more efficiently as part of the facility's closure plan.
This letter constitutes acceptance of the request to delay the implementation of tree removal,
designated as Scope 3, for the subject dam received by this Division on September 27, 2016 with
the following stipulations:
State of North Carolina I Environmental Quality I Energy, Mineral, and Land Resources
1612 Mail Service Center I Raleigh, North Carolina 27699
919 707 9220 T

Mr. George T. Hamrick Cape Fear 1956 Ash Pond (Inactive)
Acceptance of Request — Scope 3 CHATH-075
May 3, 2017
Page 2 of 3
1. Duke Energy employees will be required to inspect the dam on a weekly basis for signs of
new seepage, new subsidence, depressions, etc.
2. Annual inspections will be required to evaluate trees for any signs of degradation, significant
stress, and any type of condition that poses an identifiable immediate or near-term threat to
the integrity of the dam. This inspec-Lion also will be required to monitor -the condition of the
stumps and the dam for signs of root decay Root balls that have shown to have significantly
degraded in the opinion of the engineering team will be identified, removed and repaired in
accordance with the previously provided excavation and backfill standards. As this will
require an excavation into the dam in many cases, an approval from our Dam Safety Program
will be required.
3. Trees marked in the field during the September 14, 2016 inspection by Mr. Sharat
Gollamudi, PE will be removed with the stumps cut no higher than 6 inches above the
existing ground surface and shall be treated with a protective coating to retard root decay per
the engineering certification dated September 23, 2016
4. This acceptance letter is granted for one year. After that time, Duke will need to reevaluate
the necessity of leaving the trees in place until the coal ash has been removed. If leaving the
trees and/or root -balls in place until the coal ash has been removed is still a necessity at that
time, then an extension of this acceptance will be required Leaving trees or root -balls in
dams is not a common engineering practice because falling trees can potentially cause the
instability of the dam, and decaying roots can create seepage path and internal erosion
problems
This approval allows the trees and root -balls to remain, with the prescribed inspections, until
dewatering and closure only because removing them while coal ash is in the impoundment
could also cause stability concerns for the embankment. Once a decommissioning and
closure plan is approved by DEMLR, full removal of vegetation from the dam and basin
areas must be implemented and must be fully addressed in the closure plan. If the coal ash is
not removed from the impoundment, then a plan and design must be submitted to dam safety
for approval to remove trees from the dam.
Please be aware that all other stipulations of the Certificate of Approval for Scope 3,
Vegetation Removal, dated Septeamber 10, 2015 remain in effect.
For assistance you may contact the Raleigh Regional Office at [phone] or a staff member
of the Dam Safety Program in the Raleigh Central Office at telephone number [phone].
►0
Davis, PE, CPM
State of North Carolina I Environmental Quality I Energy, Mineral, and Land Resources
1612 Mail Service Center I Raleigh, North Carolina 27699
919 707 9220 T

is
Mr. George T. Hamrick
Acceptance of Request — Scope 3
May 3, 2017
Page 3 of 3
TED/bsc/md/cd/dk
Cape Fear 1956 Ash Pond (Inactive)
CHATH-075
cc: Mr. Bill Denton, PE, DEMLR Regional Supervisor - RRO
Mr. Jeff Poupart, Division of Water Resources
Mr. Randy Hart, Duke Energy
Mr Sharat Gollamudi, PE, Duke Energy
Filename CHATH-075-20170503 AppRequest_Cape Fear 1956 Ash Pond (Inactive) —Scope 3
State of North Carolina I Environmental Quality I Energy, Mineral, and Land Resources
1612 Mail Service Center I Raleigh, North Carolina 27699
919 707 9220 T