20120900 Ver 2_Salisbury_Feasibility_Analysis_8-30-2018_20180904

Strickland, Bev
From: Jody Smet <[e-mail]>
Sent: Tuesday, September 04, 2018 3:43 PM
To: Jim Behmer; [e-mail]; Eli Hopson - CHP; Mark Gross;
[e-mail]; Lane Bailey; Mcdaniel, Chonticha; Cook, Clinton;
Higgins, Karen; Bill Remington; Griffin, III, Thomas N.; John Collins - CHP; Goudreau,
Chris J.; Jeff Jones
Cc: Graham Corriher
Subject: [External] Yadkin Project (FERC No. 2197) - Salisbury Sedimentation and Flood
Protection Plan Feasibility Analysis
Attachments: Salisbury_Feasibility_Analysis_8-30-2018.pdf
All,
When we met on July 16, 2018 we discussed conducting a preliminary feasibility analysis of Cube Yadkin's
recommended alternative. We followed-up the July 16 meeting with a site visit on August 8. As a result of the site visit, I
have attached a draft of Cube Yadkin's feasibility analysis of the recommended alternative.
The recommended alternative in the draft plan is a proposed solution and is at the conceptual level. The draft plan
proposes that the preliminary and detailed designs occur in 2019, as part of the plan implementation. If the City of
Salisbury prefers that detailed engineering and design occur prior to plan submittal to FERC, we will need to Request an
Extension of Time (EOT) from FERC with Salisbury's support. Absent an EOT request, Cube Yadkin will file a revised
draft plan with FERC on or before September 18, as is required.
Thank you,
Jody J. Smet, AICP
Cube Hydro Carolinas
(0)804-739-0654
(C) 804-382-1764
CUBEHYDRO
CAROLINAS
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Yadkin Hydroelectric Project (FERC No. 2197)
Salisbury Sedimentation and Flood Protection Plan
A Preliminary Analysis of the Feasibility of the Recommended Alternative
The Yadkin Project license (Article 401 and 401 Water Quality Certificate Condition No. 9)
requires Cube Yadkin Generation LLC (Cube Yadkin) to develop a sedimentation and flood
protection plan in consultation with the City of Salisbury (Salisbury), Rowan County, and the
North Carolina Division of Water Resources (NCDWR) (401 & Buffer Permitting Unit and the
Public Water Supply Section of the Mooresville Regional Office). Cube Yadkin distributed a
draft of the Salisbury Sedimentation and Flood Protection Plan (Plan)' for review and comment
on May 14, 2018. The recommended alternative specific to flooding at the Salisbury pump
station is to modify the existing pump station to raise critical equipment above the flood stage, so
water at elevation 652.3 -feet (NGVD) does not impact station operations.
Salisbury and NCDWR provided comments on the draft Plan. Cube Yadkin met with Salisbury
and NCDWR on July 16, 2018 to further consult with them about the recommended alternative.
At the meeting, Salisbury identified conditions or events that could cause an unanticipated
problem or prevent the project from reaching its goals (i.e., "fatal flaws"). Subsequent to this
meeting, Cube Yadkin met with Salisbury on August 8, 2018, on-site at the pump station, to
evaluate, preliminary, the identified potential fatal flaws. The following is a preliminary
screening and analysis of these factors.
Personnel Safety: The Plan must provide and ensure safe working conditions for staff. Staff
must be able to access safely the pump station under extreme conditions, such as flood events.
Personnel safety is extremely important, and the draft Plan does not include final engineered
design information; worker safety will be addressed in the design plan and intended operational
procedures. The design plan will include improvements for redundancy and remote operation,
especially suited for extreme flood events. Provisions will be made for safe access during more
frequent minor flooding events. The station pumps will have isolated operation and be designed
to operate reliably and safely up to 652.3 feet (NGVD 29), which is more than 3 feet above the
100 year storm event. All essential equipment will have remote operation and monitoring ability.
As a backup, there will be a contingency plan and procedures for providing raw water even if all
the pump station equipment completely fails, which is highly unlikely. This can be accomplished
using portable diesel pump(s) at designed and installed temporary intake points in safely
accessible locations above the flood waters. Currently, a diesel pump is the backup in case of
pump failures.
Station Access: Access to the pump station is difficult 3 to 5 times a year when high water
(about 20,000 cfs at the Yadkin College gage) on Hannah Ferry Road prevents vehicle access but
' The draft Plan includes recommended alternatives to address both sedimentation and flood
protection. The engineering of the recommended alternatives is preliminary and at the "solutions
analysis phase"; detailed engineering and construction will occur during implementation of the
Plan.

is not deep enough for boat access. Additionally, access is required to all building levels that
have operational equipment.
Safe access to the pump station during the 20, 000 cubic feet per second (cfs) flood events will be
accommodated with appropriate amphibious equipment, which could be stored at the
transformer or other SRUsecure locations. The design effort will include plans for
recommended safe access or remote operation. A Contingency Plan and procedure will include
temporary intake points in safely accessible locations above the flood waters case of total station
equipment failure during major flooding events to avoid the need for station access. The design
will include access to all levels of the pump building that are essential for operations.
Constructability: The Plan must be supported by proof that all its elements are constructible
based on reliable confirmation by contractors.
Constructability is typically part of the design quality assurance and quality control effort, and it
will be completed for this Project. A preliminary analysis suggests the proposed solution is
constructible.
Structural Integrity. The Plan must be supported by proof that the pump station facilities will
be structurally sound during flooding events, while supporting proposed new roofs, equipment,
and structural modifications. There is a concern with the ability of the brick walls to withstand
storm event water flow/pressures.
There are several options to protect the structure, pumps, and electrical equipment from flood
damage up to elevation 652.3 feet (NGVD 29). These options could range from an elevated
mezzanine to partial reconstruction of the walls and roof. The best option will be determined
during the design effort. Currently the design is at concept level; the next step toward
preliminary design is to complete a structure design calculation of the current structure. The
final design would be completed once the questions and concerns with the preliminary design
are addressed. Calculations will be completed to determine the flood impacts on the pump
station structure.
Soil/subsurface Suitability: The Plan must be supported by proof that soil/subsurface
conditions will be suitable for the proposed modifications.
A geotechnical site evaluation and calculations will be performed if necessary because of
increased soil loading and would take place as part of or after the preliminary design is
completed.
Electrical System Integrity: The Plan must identify and plan the relocation, or provision of new
equipment, the electrical, I&C and SCADA systems of the pump station to ensure everything is
above flood elevations or capable of continuous operation during submergence.
All electrical and Supervisory Control and Data Acquisition (SCADA) equipment will either be
made submersible or raised above elevation 652.3 feet (NGVD 29). It may be possible to
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relocate the electrical switchgear and equipment to a location near the transformers, but that
will be evaluated further during the design process.
Mechanical Integrity: The Plan must be supported by proof that extending pump shafts and
elevating motors (and electrical equipment) for three raw water pumps and other mechanical
modifications will produce a sound, reliable system of delivering raw water to Salisbury's
reservoirs with no decrease in service life or increase in operational cost.
The pump manufacturer and representatives have already indicated that 5 -foot shaft extensions
are possible. Cube Yadkin will continue to consult with the pump manufacturer during the
design process. It is Cube Yadkin's understanding that one pump has been rebuilt, and a second
pump is currently being rebuilt. The third and final pump rebuild is planned for 2019. All
mechanical equipment will be submersible rated or be raised above elevation 652.3 feet (NGVD
29).
Permit Ability: The Plan must consider all local, state, and federal requirements, and all aspects
of the recommended alternatives must be "permittable".
Permitting will be completed as part of the detailed engineering, and consulting with permitting
agencies is typically started during the preliminary design phase of the Project.
Flood Damage Prevention and Recovery: The Plan must provide flood protection of the
existing intakes (actuators, etc.) and the pump station and provide for minimization of post -flood
maintenance and repairs.
Flood damage prevention and recovery are considered as part of the concept design but will be
detailed further as the design progresses forward. The need to consider flood damage protection
on the intake structure is understood and will be addressed in the design phase.
Post Flooding Cleanup: Clean up after building flooding is a concern for staff.
The design will include identification of possible flooding areas, and if necessary, a cleanup plan
for minimizing the cleanup efforts.
Elevation of Operating Floor: The Plan would need to raise the operating floor of the pump
station above flood elevations so that discharge piping and electrical equipment would all be on
the same level and above flood waters.
Cube Yadkin understands the operating floor concerns and these concerns will be part of the
design, as addressed above. Equipment will be located 3 -feet above the 100 year flood level or
be rated for submersible service.
Water Supply Operations: The Plan must guarantee that water supply operations will continue
during construction. The Plan needs to identify and describe procedures that guarantee the
maintenance of continuous operation of the existing intakes and pump station during

construction of modifications. A Contingency Plan that immediately re-establishes raw water
supply to the water supply system in the event of failure must also be included.
Construction planning will include a minimum of two contingency layers to significantly reduce
the risk of unplanned operational shutdowns.
Operations and Maintenance (O&M) Costs: The Plan must identify and account for
additional O&M costs associated with operating the facilities, as modified pursuant to the plan.
The operation and maintenance (O&M) costs will be part of the Sedimentation and Flood
Protection Plan. However, completion of the final design is required before the final (O&M) cost
impact can be determined. It is possible that operational costs could be the same or reduced with
the planned improvements.
Proof of Effectiveness and Reliability: The Plan must be supported by proof of effectiveness
and reliability of submersible control/operation, which is atypical for this type of public water
system.
All submersible mechanical, SCADA, and electrical equipment will be National Electrical
Manufacturers Association (NEMA) and Ingress Protection Rating (IP) submersible rated for
the appropriate level of protection.
Pump Station Dependability: This intake and pump station facility is the sole source of water
for the utility. Pump station dependability is very important.
The station reliability is of upmost importance, which will be addressed in the design of
improvements and contingency planning.
Pump Operations: One pump typically runs about full time in non -peak electrical usage hours.
These non -peak hours are weekday nights and all day on weekends. Salisbury has not run on two
or three pumps at once, but it is electrically possible, and the discharge pipe is large enough.
There is common main feed for pump service, and an isolated panel for each pump. It is likely
that a new main feed panel and two pump panels will be required, but the third pump has a panel
that could be relocated. Pump modifications should be modeled to confirm vibration will net
become an issue. It is possible to support the column about 12' below the floor if necessary.
Typical pump operations will be considered as part of design, construction, and contingency
planning. The design will include main feed panel and isolated pump panels. The design will
include improvements as necessary to both rebuilt pumps and incorporate desired improvements
to the third pump (that has not been rebuilt yet). At the end of the Project, it is desired to have all
three pumps in a rebuilt condition to improve dependability. A vibration analysis will be part of
the design, using an appropriate pump consultant or manufacturer.
External Station Equipment: The aluminum tank for pump seal water is within the 100 -year
flood stage. There are submersible pumps and electric in the tank, but the electric to the tank is
not submersible rated. During the most recent flood event the system stayed operational, but
A9

operators had to manually adjust float position. Electrical wiring to wells also need to be rated
for submersible conditions. Surge valves in in the station yard are manually operated and need to
be operational during a 100 -year flood event (access and remain manual or automatic with
remote access).
The design will include improvements to allow the pump seal water to remain operational and to
avoid flood damage. Automatic CLAYsurge valves will be installed to avoid the need for
manual operation. These valves are submersible and reliable. Manual override can be included
if desired.
Water System Storage Capacity: Current storage capacity in the water system is just less than
one day (worst case scenario) and about 1.5 days (best case scenario).
The storage capacity will be considered during the contingency planning of both the
construction period and during flood events.
Periodic Dredging: The Plan must provide for periodic dredging to prevent sedimentation above
the low river flow depth to ensure that water reaches the intakes and to allow for post -dredging
accumulation of sediment without reaching the flow -blocking depth before the next dredging
event. The area to be dredged should include the entire area from the western shore where the
intakes are located to the eastern shore of the Yadkin River. The length of river channel included
in the area would have to be determined based on appropriate factors, including for example
sediment accumulation rates and frequency of dredging.
Implementation of the Plan includes topographic/bathymetric surveys in 2019 to establish
current conditions, and an engineering evaluation to define the geographic area (depth, width,
length) to be dredged. These surveys are necessary prior to the development of detailed
sediment removal plans. Sediment removal may begin in 2020, if required. Cube Yadkin will
manage the accumulation of sand to maintain the operability of the intakes, regardless of the
market value of the sand, or the associated cost. Sediment removal will be in accordance with
all applicable local, state, and federal regulations and issued permits. Additionally, Cube Yadkin
will monitor sediment elevations annually, and dredging will occur at a frequency necessary to
maintain the operability of the intakes.
Wet Well Condition: Currently there is about 10 or 12 feet of sand in the wet well, causing
excessive pump wear.
The level of sand in the wet well will be surveyed as part of the sedimentation survey and
analysis. The required sedimentation removal in Yadkin River, and the avoidance of
sedimentation buildup in the wet well will be included in the analysis and design plans.
Sand Backwash: The impacts to the sand backwash system, if operated, are uncertain.
The operational intent and possible effectiveness of the sand backwash system will be considered
during the preliminary design effort. The backwash system could be returned to service if
beneficial to station operation and if maintainable.
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In conclusion, the analysis of these factors suggests that modification of the existing pump
station to raise critical equipment above elevation 652.3 -feet is a feasible alternative.
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