NC0023884_Staff Report_19941028

/2/6/1-60)
To: Permits and Engineering Unit
Water Quality Section
Review Engineer: Jay Lucas
SOC Priority Project: Yes
Date: October 28, 1994
NPDES STAFF REPORT AND RECOMMENDATIONS
County: Rowan
NPDES Permit No.: NC0023884 (Modification)
MRO No.: 94-216
PART I - GENERAL INFORMATION
1. Facility and Address: Grant Creek WWTP
City of Salisbury
Post Office Box 479
Salisbury, N.C. 28145
2. Date of Investigation: October 27, 1994
3. Report Prepared By: Michael L. Parker, Environ. Engr. II
4. Person Contacted and Telephone Number: Mr. Barrett Lasater,
[phone].
5. Directions to Site: From the junction of SR 1915 (Hollywood
Drive) and SR 1820 (Grubb Ferry Road) in the Town of
Spencer, travel east on SR 1820 approx. 0.2 mile. The WWTP
is located on the right side of SR 1820.
6. Discharge Point(s), List for all discharge Points: -
Latitude: 35° 44' 07"
Longitude: 80° 26' 50"
Attach a USGS Map Extract and indicate treatment plant site
and discharge point on map.
USGS Quad No.: E 17 NW
7. Size (land available for expansion and upgrading): There is
limited area available at the existing WWTP site for
expansion, if necessary, however, none is projected in this
modification request.
8. Topography (relationship to flood plain included): The WWTP
is located at or near the flood plain elevation of Grant
Creek, however, the WWT units are partially elevated and
receive some protection from flooding.
9. Location of Nearest Dwelling: None within 500 feet of the
WWTP.

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Page Two
10. Receiving Stream or Affected Surface Waters: Yadkin River
a. Classification: WS-V
b. River Basin and Subbasin No.: Yadkin 030704
c. Describe receiving stream features and pertinent
downstream uses: The receiving stream is the main
segment of the Yadkin River, which is used for primary
and secondary recreation. The Town of Spencer
(NC0025593) discharges approx. 500+ yards below this
outfall.
PART II - DESCRIPTION OF DISCHARGE AND TREATMENT WORKS
1. Volume of Wastewater: 7.5 MGD (initial), 12.5 MGD (upon the
addition of Town Creek WWTP effluent).
a. Current permitted capacity: 7.5 MGD
b. Actual treatment capacity: 7.5 MGD
c. Description of existing or substantially constructed
WWT facilities: Instrumented flow measurement followed
by a parshall flume, mechanical bar screen with grit
chamber, two primary clarifiers, two trickling filters,
one aeration basin with mechanical aeration, three
secondary clarifiers with polymer addition, a screw
pump station, gaseous disinfection with contact basin,
post aeration basin (diffused), two aerobic digesters,
a sludge thickener, sludge DAF unit, dechlorination and
stand-by power.
d. Possible toxic impacts to surface waters: This
facility has passed recent toxicity tests.
e. Pretreatment Program: Approved.
2. Residual handling and utilization/disposal scheme:
a. If residuals are being land applied specify DEM Permit
No. WQ0001956.
b. Residuals Contractor: AMSCO, Inc.
c. Telephone No. [phone]
d. Residual Stabilization: PSRP
3. Treatment Plant Classification: Less than 5 points; no
rating (include rating sheet). Class IV (This modification
will not create any change from the present classification)
4. SIC Code(s): 4952 2099 2261
Wastewater Code(s):
Primary: 01
Secondary: 81 55 58
5. MTU Code(s): 04003

Page Three
PART III - OTHER PERTINENT INFORMATION
1. Is this facility being constructed with Construction Grants
Funds (municipals only)? Public monies will be used in the
construction of the proposed outfall extension.
2. Special monitoring requests: None at this time.
3. Additional effluent limits requests: Consideration should
be given to requiring this facility to monitor color through
an administrative letter or through the Permit.
PART IV - EVALUATION AND RECOMMENDATIONS
As part of a planned WWT system upgrade, Salisbury has
submitted an application to modify the existing Grant Creek NPDES
Permit to relocate the discharge point from Grant Creek to the
main segment of the Yadkin River. This modification is part of a
master plan that will ultimately end with the construction of a
new WWT facility and the elimination of both the Grant Creek and
Town Creek WWTPs. The timetable for all of the proposed
construction activities has been accelerated due to the impending
results of the Division's management plan for High Rock Lake,
which is expected to recommend nutrient limits on all major point
source dischargers. An EA has been performed on the proposed WWTP
site and outfall line and a FONSI issued.
The first phase of the WWT system upgrade will involve
extension of the outfall at Grant Creek to the Yadkin River. .In
the second phase, a force main from the Town Creek WWTP will be
constructed to transport the effluent from the Town Creek plant
to the Grant Creek WWTP's outfall. The final phase will involve
the construction of.a new WWTP (currently permitted under NPDES
Permit No. NC0082279) and the subsequent elimination of both the
Grant Creek and Town Creek WWT plants. Such being the case, the
modified Permit should contain effluent limitation pages for each
phase of construction planned by the City as listed below:
1. Limitations for the current discharge location into
Grant Creek (7.5 MGD).
2. Limitations for the Grant Creek WWTP with
• discharge to the Yadkin River (7.5 MGD).
3. Limitations fora combined discharge from
Grant Creek and Town Creek WWTPs directly
Yadkin River (a total of 12.5 MGD).
a direct
both the
into the

Page Four ,
The City has also raised some questions concerning the use
of a diffuser on the outfall and its design. According to the
City's engineer, the diffuser design and installation will be
underneath 3-4 feet of sand/sediment, if constructed as
recommended by the TSB. This observation is based on borings
conducted of the river bottom at point of discharge. If thisis
true, a reevaluation of the specific type of diffuser to be used
will be necessary prior to the submittal of an ATC request.
Pending receipt and approval of the WLA, it is recommended
that the Permit be modified as requested. Speculative limits have
been previously sent to the City by. the Division for the proposed
Yadkin River discharge.
Signature of "Report Preparer
Water Quality
pc\dsr\dsr94\grantcrk.sr
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