NC0024201_speculative limits_19930326

State of North Carolina
Department of Environment, Health, and Natural Resources
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27604
James B Hunt, Jr, Governor A. Preston Howard, Jr., P.E.
Jonathan B. Howes, Secretary Director
Asheville
704/251-6208
March 26, 1993
Ms. Francine Durso, P.E.
Piedmont Olsen Hensley
P.O. Box 31388
Raleigh, NC 27622-1388
Subject: Speculative NPDES Permit
Limits for the Roanoke Rapids Sanitary
District Wastewater Treatment Plant
NPDES Permit No. NC0024201
Halifax County
Dear Ms. Durso:
The North Carolina Division of Environmental Management (NCDEM) is in receipt of your
letter dated February 19, 1993 concerning speculative limitations for the subject facility. Per your
request, the existing wasteflow of 8.34 MGD and a proposed expanded wasteflow of 12.0 MGD were
considered. Our comments and recommendations are as follows:
Preliminary modeling analyses have indicated that the capacity of the Roanoke River to
assimilate carbonaceous BOD (CBOD) containing wastes is exhausted. As part of the Roanoke
Basinwide Management Plan to be completed by 1997, NCDEM plans to develop a field calibrated
dissolved oxygen (DO) model of the Roanoke River from Roanoke Rapids to Hamilton. This model will
provide NCDEM with a good tool to allocate wasteloads and develop management strategies in the basin.
In the meantime, according to current standard operating procedures, the existing NPDES permit effluent
limitations and conditions contained in the recently issued NPDES permit fora wasteflow of 8.34 MGD
will not change prior to its expiration date of May 31, 1997. In addition, relocation of the discharge from
Chockoyotte Creek to the Roanoke River prior to this date will not affect the current effluent limitations.
Speculative effluent limitations were developed for a proposed expansion to 12.0 MGD in the
Roanoke River mainstem. The Roanoke River at the point of discharge has an estimated drainage area of
8, 384 square miles and regulated flows of 1,500 cfs during the summer and 1,000 cfs during the winter.
Since the CBOD assimilative capacity of the river is compromised, it is recommended that the CBOD
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Ms. Francine Durso
Page Two
loading of the subject discharge remains constant at expanded flows. The following effluent limitations
are recommended at this time:
Parameter Summer Winter
Wasteflow (MGD) 12.0 12 0
CBOD (mg/I) 17D 25.0
NH3-N (mg/I) Monitor Monitor
DO (mg/I) Monitor Monitor
Fecal Coliform (mg/I) 200 203
Total Residual Chlorine (ug/I) 28 28
Cadmium (ug/l) Monitor Monitor
Chromium (ug/I) Monitor Monitor
Copper (ug/l) Monitor Monitor
Nickel (ug/l) Monitor Monitor
Lead (ug/l) Monitor Monitor
Zinc (ug/I) Monitor Monitor
Silver (ug/I) Monitor Monitor
Total Phosphorus (mg/I) Monitor Monitor
Total Nitrogen (mg/I) Monitor Monitor
pH (SU) 6-9 6-9
The total residual chlorine limitation may be waived if a wastewater disinfection alternative is
provided. In addition, a quarterly chronic Ceriodaphnia testing requirement at 1.8 % will be required.
These limitations may become more stringent in the future when basinwide management strategies are
developed and implemented. However, scheduling for compliance with more stringent limits, if
applicable, will be determined on a case -by -case basis taking into consideration the type and age of the
plant, size of its discharge, current treatment levels, cost feasibility, and significance of water quality
impacts.
Please also note that the above effluent limitations are speculative and for use in your
engineering study. Effluent limitations can only be made final upon review of an official NPDES permit
application and issuance of an NPDES permit.
If you need further clarification on this matter, please contact Mr. Juan C. Mangles or me at
[phone].
J Trevor Clements, Chief
}GVater Quality Section
JTC/ICM
cc: Tim Donnelly
Central Files

Fr,
:1
PiedmOn tOls ensle T
Offices:
Greenville, SC
Raleigh, NC
Greenville, NC
Atlanta, GA
Chattanooga, TN
Engineers/Architects/Surveyors
February 19, 1993
P.O. Box 31388, Raleigh, NC 27622-1388
2301 Rexwoods Drive, Suite 200, 27607
[phone] Fax: [phone]
Mr. Trevor Clements, Assistant Chief
Technical Support Branch, Water Quality Section
N.C. Division of Environmental Management
Post Office Box 29535
Raleigh, North Carolina 27626-0535
RE: Roanoke Rapids Sanitary District Wastewater Treatment Plant, Halifax County
NPDES Permit No. NC0024201
Piedmont Olsen Hensley Project No. 39164.00
Dear Mr. Clements:
Our firm has been retained by the Roanoke Rapids Sanitary District to assist in
preliminary planning for a possible upgrade and/or expansion to the District's
wastewater treatment plant. The plant currently operates under the referenced
NPDES permit with monthly average limits of 8.34 MGD, 25 mg/1 CBOD and 30 mg/1
TSS. The permit has just been renewed and the new expiration date is May 31,
1997.
As part of our planning, we would appreciate receiving an opinion regarding
effluent limits which may be imposed on the Roanoke Rapids Sanitary District
wastewater treatment plant in permit renewals in the foreseeable future. We
request that limits be evaluated for two flow conditions: the current permitted
capacity of 8.34 MGD and a possible future flow of 12.0 MGD. The District will
be required to relocate the effluent outfall from the existing discharge location
in Chockoyotte Creek to the Roanoke River, at the next permit renewal or sooner
if an Authorization to Construct other improvements is requested. Therefore, we
request that the limits be evaluated for a discharge into the Roanoke River.
We recognize that treatment limits which the Technical Support Branch furnishes
would be speculative; however, the information is likely to be the best available
at this time and it would short-sighted of us not to consider it as input to the
planning.
We would appreciate as prompt a response as possible so that we may proceed with
planning. Please don't hesitate to call me at 782-5511 if you should have any
questions or need more information.
Sincerely,
PIEDMONT OLSEN HENSLEY
Francine Durso, P.E.
cc: Mr. Macon Reavis Mr. Robert Vinay