NC0050342_Plan of Action_19980503

NPDES DOCUMENT SCANNING COVER SHEET
NC0050342
Muddy Creek WWTP
NPDES Permit:
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
1144 6r( 04/ ‘
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
May 3, 1998
Thies document is printed on reume paper - ignore arty
content on the reiirerese'side

Summary of Winston-Salem's Request for a Water Intake
Structure on the Yadkin River
5/98
AHM
Anticipating an increased demand for drinking water, the City of Winston-Salem
wants to build a second water intake on the Yadkin River to be located approx. 1 mile
upstream of the Enon gage. Initially the intake will be design to withdraw 25 MGD and
ultimately 50 MGD. The City is concerned that the existing intake nr Idols is too small to
meet future needs. In addition, the existing intake is located downstream of I-40 and there
is a percieved risk that chemical contamination of the water supply could occur as a result
of a highway accident. The City is proposing to build a run -of -river dam across the
Yadkin River in order to increase the depth of the river. The river is shallow (-3 ft.) at
the proposed site and the additional depth is needed to accomidate a water intake
structure. The impoundment will be contained within the natural banks.
The Division (Modeling Unit) in the past has stated that we want the 7Q10 flow
immediately above the Muddy Creek discharge to be maintained at 554 cfs (`89 USGS
estimate) after any withdraws are taken. Since the City owns storage in Kerr Scott Res in
Wilkes County the Division has proposed that the COE release additional water to
maintain the 7Q10 flow. There are several problems with requiring that the 7Q10 flow at
Muddy Ck be maintained. First, there are operational difficulties for the Corps in
monitoring the stream flow approx. 80 river miles downstream of the reservoir. If at all
possible the COE would like to keep their control point at Wilkesboro. This way if the
satellite telemetry goes down the operator can simply drive a relatively short distance to a
staff gauge in order to assess the stream flow. Second, requiring that a 7Q10 flow be met
that far from the reservoir will mean, for all practical purposes, that W-S will be using
their pool storage to augment other withdrawers between the city and the reservoir.
Therefore, the COE has proposed a the following operational plan, similar to the
plan used for Jordan Lake, I have been told. First, a baseline condition will be
established that assumes that the existing operation of the reservoir and the AVERAGE
daily withdrawal from Idols (50 MGD) is a satisfactory permitting condition for WLAs.
When the flows at Wilksboro, the control point for reservoir operation, drop to or near the
7Q10 flow (125cfs), a low flow operational procedures will be instituted at the reservoir.
Note that 125 cfs is the minimum release from Kerr Scott Res. As part of these
procedures W-S will average its withdrawal for the past week, as an indication of the
demand for the following week and notify the COE. The COE will release a flow in 10
MGD increments equal to, or one increment greater than, the city's withdrawal.
Increments of less than 10 MGD are operationally difficult to achieve, according to the
COE.
A potential problem with this operational procedure is that a weekly average may
be an underestimate of future demand. The base line condition of a 125 cfs minimum
release and average withdrawal may not be approximately equal to the 7Q10 flow.

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SOUTFORK CREEK OUTFALL
MUDDY CREEK WWTP
DISCHARGE NC0050342-002
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LOCATION MAP
MUDDY CREEK WWTP
NPDES # NC0050342
FORSYTH ANDRDAVEY VIDSON COUNTY, N.C. �C
WINSTON-SALEM WEST QUADRANT
WELCOME QUADRANT
SCALE 1:24000
NOTE: 1/4 MILE AREA AROUND PLANT IS HIGHLIGHTED IN YELLOW
WATER BODIES WITHIN 'A MILE OF PLANT ARE HIGHLIGHTED IN BLUE
LOCATIONS OF WELL WITHIN V, MILE OF PLANT ARE DENOTED BY RED DOTS
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ROUTES OF INFLUENT OUTFALLS FEEDING THE PLANT ARE NOTED BY ORANGE LINES 'HI
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