20120900 Ver 1_ External Falls Flow Monitoring_20180509

Strickland, Bev
From: Jody Smet <[e-mail]>
Sent: Wednesday, May 09, 2018 7:46 PM
To: Tarver, Fred; Mcdaniel, Chonticha; Jerald Robinson; Styer, Tami; Neal Simmons;
Brandon Beres; Eli Hopson
Subject: [External] RE: Yadkin Project (FERC No. 2197) - Falls Flow Monitoring
Attachments: Flow Monitoring Proposal_5-9-2018.docx; flow out of narrows_5-9-2018.docx
All,
I apologize for the delay. When we last spoke on March 20, Cube Yadkin committed to drafting a flow monitoring
proposal that addressed the concerns you expressed during our call. I have attached a proposal for your review and
comment. Additionally, both NCDEQ and Duke have asked for information to support the claim that the flow out of
Narrows = the flow out of Falls. I have also attached a short discussion and some supporting data that address this
question. Please review both documents and send us your feedback. I'm also happy to schedule a call to discuss further,
if necessary.
Thanks,
Jody J. Smet, AICP
Cube Hydro Carolinas
(0) 804-739-0654
(C) 804-382-1764
CUBEHYDRO
CAROLINAS
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-----Original Appointment -----
From: Jody Smet
Sent: Tuesday, March 20, 2018 1:18 PM
To: Jody Smet; Tarver, Fred; Mcdaniel, Chonticha; Jerald Robinson; Styer, Tami; Neal Simmons; Brandon Beres; Eli
Hopson
Subject: Yadkin Project (FERC No. 2197) - Falls Flow Monitoring
When: Thursday, March 22, 2018 3:30 PM -4:30 PM (UTC -05:00) Eastern Time (US & Canada).
Where: Dial 1-515-604-9768 Enter 989008#
To discuss permanent flow monitoring device below Falls Dam.

High Rock
Cube plans to install a side looking doppler current meter (SLDCM) on the upstream side of the Denton
Water Intake structure below the High Rock Dam (Figure 1). The river at this point, is approximately
650ft wide and ranges in depth from approximately 12ft on the Denton side, to 6ft on the opposite bank
(see Figure 2 and Figure 3). The SLDCM instrument selected for flow measurement is a SonTek-SL500
which a vertical beam width of 3.8°, a resolution of 0.001m/s and an accuracy of ±1% measured velocity.
The Denton structure was chosen for two reasons; first, approx. 60% of the water flow is seen in the first
third of the transect on the Denton side of the river. Measuring in this higher flow area will allow the
SLDCM to accurately measure the stream flow. Second, installing the system on the upstream side of
the structure will provide some protection from debris that get sent downstream during discharge
events while still being able to give reliable live data during these events.
The SLDCM will be mounted on a rail system that will allow the sensor to be easily removed from the
water for maintenance and placed back at the same elevation prior to the maintenance. This will ensure
that the SL -500 is always placed at the same elevation. Additionally, a staff gauge will also be installed
next to the SL -500 To further ensure that the sensor is placed back at the same elevation and to also
verify that the depth readings are accurate.
River discharge, bathymetry, velocity, and elevation will be characterized by measurements taken with a
SonTek M9 Doppler River Surveyor unit [1] [2]. The characterized measurements will be used with to the
SL -500 measurements to develop a discharge curve. This curve will be characterized over a variety of
flows and its accuracy is expected to grow with time.
The SL -500s will report the measured velocity data to a solar powered telemetry system on shore that
will transmit the data via cell signal to a Cube Hydro server for display on the website. Cube plans on
having these devices installed, operational, and transmitting data no later than 9/28/2018.
Both, the SonTek SL meter and the M9 Doppler Surveyor are used by USGS to determine real time
Water Velocities [3] [4] [2].
Narrows
Cube plans to discontinue flow monitoring below the Falls dam in favor of the more accurate monitoring
of flow through the Narrows penstocks. The flow through the Narrows Dam is equal to the flow out of
the Falls Dam.
Cube plans to install Ultrasonic Time Transit (Figure 4) RISONIC Type C transducers in a multipath (Figure
5) configuration at the base of each of the Narrows penstocks. These flow meters will be mounted near
the base of the penstocks outside of the scroll case and provide continuous accurate flow monitoring
measurements. The diameter of the penstock at this point is 15ft and the RISONIC Type C Transducer
has a measuring distance of 4.6-32.8ft with an estimated flow accuracy of 1-2%.
The transducers use the Ultrasonic Transit Time method (Figure 4) to measure the water velocity. The
Transit Time method measures the difference between the transit time upstream to downstream to
calculate the mean path velocity. In some cases, USGS also uses this method to determine water velocity
[4].

The RISON IC Transducers will report the measured data back to a RISON IC Ultrasonic Transit Time
Module, which will in turn feed data back to our operations sever for display on the website. Cube plans
on having these devices installed, operational, and transmitting data no later than 9/28/2018.
Any water that does not go through the penstock, such as during a bypass, will be characterized by the
existing weir tables and automatically added to measured turbine discharge so the flow that is recorded
and displayed on the site webpage is reflective of the total discharge.
Figure 1: SLDCM Flow Monitoring Proposed Location

Figure 2: High Rock Transect Location
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Ultrasonic Transit Time Method
•
Difference between transit time
Upstream and downstream
This transit time difference is directly
proport€onaE to the mean path velocity
velocity muitiplied with cross sectional
area of pipe or channel results in [1I9,y&
1 --
Figure 4: Ultrasonic Time Transit Time Method
Info on multiple paths and multiple planes...
E _ # planes (1 or 2)
P = TOTAL # paths in all planes
With respect to a horizontal place in the middle of the
cross-section, the transducers are placed at the following
angles
1E1P / 1E2P zero (i.e. on the horizontal plane)
1E2P / 2E4P +/- 30 degrees
1E4P / 2E8P +/- 18 deg. and +/- 54 deg.
Figure 5: Flow Meter Configuration Information

Bibliography
[1] U.S. Geological Survey, Discharge Measurements at Gaging Stations, Reston Virginia: U.S.
Department of the Interior, 2010.
[2] J. A. B. K. A. O. (USGS), "Validation of Streamflow Measurements Made with M9 and," [Online].
Available: https://hydroacoustics.usgs.gov/publications/Validation-RRay-M9-Boldt0berg-sm.pdf.
[3] USGS, "Velocity Meter Deployments," [Online]. Available:
https://hydroacoustics.usgs.gov/indexvelocity/deployments.shtml.
[4] USGS, "Index -velocity and Other Fixed -deployment Instruments," [Online]. Available:
https://hydroacoustics.usgs.gov/indexvelocity/instruments.shtml#advm.

On January 191h 2018, Normandeau Associates was contracted to measure the discharge flow below the
Falls dam. Normandeau used a SonTek Doppler River Surveyor Sensor in conjunction with a NAVD88 GPS
to take the measurements. Over the course of 30 minutes (12:30pm-1pm), Normandeau took a total of
4 transect measurements. These 4 measurements, were then averaged to get an estimated discharge of
5,041cfs below the Falls Dam. Our calculated estimates of the discharge flow out of the Narrows Dam at
that time was 5109cfs. The difference between the two flows is %1.35, which is well within the
tolerance of error for both the calculated estimates and the Normandeau discharge measurements.
There are no significant stream inflows, discharges or withdraws between the dams and the water that
exits Narrows must exit Falls shortly after. The measurements described above support this equivalence
in flow out of the Narrows and Falls.
River bank convention is that "Right" bank is to the person's right Average 5040.64
when looking downstream from on the transect.
Mean River
Total
Transect
River Width
Transect
Velocity
Discharge
Transect
Start Banki
(ft)
Area (ftz)
(ft/s)
(ft3/s)
1
R
856.30
6585.90
0.75
4958.53
2
L
807.74
6320.78
0.82
5084.96
3
R
797.57
6220.25
0.82
5164.06
4
L
828.41
6340.59
0.79
4955.00
River bank convention is that "Right" bank is to the person's right Average 5040.64
when looking downstream from on the transect.