NC0024201_Instream Assessment_19840604

NPDES DOCUMENT !I CANNINO COVER SHEET
NC0024201
Roanoke River 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
Plan of Action
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
June 4, 1984
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DIVISION OF ENVIRONMENTAL MANAGEMENT
June 4, 1984
MEMORANDUM
TO: R.W. VanTilburg, Supervisor
Raleigh Regional Office
FROM:
THROUGH:
SUBJECT:
Summary
J. Trevor Clements, EE e'l
`
Technical Services Unit
Randy Williams
Steve Tedder
In -Stream Assessment
Roanoke Rapids Sanitary District
Halifax County
The Roanoke Rapids Sanitary District requested permission to add
4,400 gpd of domestic wastewater to their effluent in September of 1983.
The Special Order by Consent was approved in November. However, the
projected additional wastewater flow was underestimated by 7,600 gpd. The
Roanoke Rapids Sanitary district has requested that the subject permit
be amended to allow an additional 12,000 gpd of domestic wastewater rather
than 4,400 gpd.
An in -stream assessment was completed recognizing this change. The
results are identical to those shown in the last assessment (see attached).
Therefore, no significant impact is predicted to occur from the increased
wasteflow.
JTC:cs
cc: L. Page Benton, Jr.
Dean Cunningham

DIVISION OF ENVIRONMENTAL MANAGEMENT
September 12, 1983
MEMORANDUM
TO: R. W. Van Tilburg, Raleigh Regional Office
FROM:
THROUGH:
SUBJECT:
J. Trevor Clements, EE
Technical Services
Randy Willi
Steve Tedder
In -Stream Assessment
Roanoke Rapids Sanitary District
Summary
Roanoke Rapids Sanitary District is seeking permission to add
4,400 gpd of domestic sewage to its present wastewater flow of 4.68 MGD.
Their WWTP discharges to the Roanoke River 2.0 miles below Champion
International and 3.5 miles above the Weldon WWTP. The wasteflow from
Roanoke. Rapids WWTP interacts with both of these dischargers' wasteflows.
Roanoke Rapids WWTP is permitted with SOC limitations of 75 mg/1
BOD5 and 50 mg/1 TSS for a wasteflow of 8.375 MGD. Their final limitations
are 30 mg/1 BOD5, 30 mg/1 TSS, and 6-9 S.U. pH for a wasteflow of 8.360
MGD. These limits apply until May 1986. O rrent self -monitoring records
indicate annual compliance with SOC limits, although the limit for BOD5
has been violated on a monthly basis six times during the past year.
Flow for the Roanoke River is controlled by the amount of dam
discharge. A minimum instantaneous flow of 1800 cfs was used in this
analysis. A level B-HORN model analysis resulted in a prediction of no
significant impact from the increase in wasteflow. The analysis predicted
an interaction with the effluent from other dischargers, p
of Champion International and Weldon, causing the river D.O. to sag to
5.7 mg/1 at 28 miles below the outfall for both wasteflows.
Analysis and Results
The Roanoke Rapids Sanitary District has requested an SOC to add
approximately 4400 gpd of domestic wastewater to their treatment facility.
At present, an average 4.68 MGD is being discharged into the Roanoke River,

•.i
a class "C" river in the Roanoke River Basin. Current self -monitoring
data (7/82-7/83) indicate that this effluent has the following
characteristics:
Parameter Average
Flow 4.68 MGD
BODS 70.85 mg/1
TSS 31.68 mg/1
NH3-N 4.08 mg/1
COD 454.7 mg/1
A level B-HORN model analysis was performed using these wastewater
characteristics. Since D.O. was not monitored, the D.O. was assumed to
be 0 mg/l. BOD-ultimate was calculated as: BODS + (4 x NH3-N) = 87 mg/1.
Model runs were completed for wastewater flows of 4.68 MGD and
4.6844 MGD. Both runs indicated a D.O. minimum of 5.7 mg/1 located 28
miles downstream of the outfall. The D.O. sag is located far downstream
because of its interaction with other dischargers, including Champion
International and Weldon WWTP' s .
Please call if you have any questions.
JTC:cs
cc: L. P. Benton, Jr.
Dean Cunningham