NC0047597_Correspondence_19890913

State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental N4lanagement
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor R. Paul Wilms
William W. Cobey, Jr., Secretary Director
September 13, 1989
A. T. Rolan, Director
City of Durham
Water Resources Department
101 City Hall Plaza
Durham, NC 27701
Subject: NPDES Draft Permit Comments
No. NC0026336 for the Eno WWTP
No. NC0047597 for the Farrington Road WWTP
City of Durham
Dear Mr. Rolan,
I have reviewed your most recent comments regarding the above NPDES per-
mits (July 24, 1989). As you are aware from the revised Draft permit, the
Farrington Road WWTP metals limits have been modified to include an increased
daily maximum limit, a weekly average limit, and a daily monitoring require-
ment. Similar changes will be made in the Eno WWTP NPDES permit. After this
regime has been followed for twelve months, Durham may request a permit modi-
fication to delete any limits or monitoring requirements that the monitoring
data might indicate are not necessary. The only guarantee I can offer is that
we will review the data at that time and any modifications would be based on
that evaluation.
The cyanide monitoring requirement for the Eno WWTP will be dropped based
on the information presented in your letter. However, if in the future the
facility should take on any wastewater contributors in which cyanide is pre-
sent, the appropriate limits or monitoring requirements will be reinstated.
The permit wording will not be changed in either permit with regard to the
use of multiple laboratory analyses for whole -effluent toxicity. Durham is
welcome to submit toxicity test results from more than one laboratory if you
believe that one may not adequately represent the quality of the effluent.
Both results will be carefully reviewed and, in the event of two conflicting
results, compliance will be based on the quality of the tests, and not on the
better results of the two.
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

If you have any questions or comments regarding this matter, please con-
tact either Dale Overcash or Trevor Clements of my staff at [phone].
Sincerely,
7-1
1U1)
,
R. Paul Wilms
cc: Arthur Mouberry, Raleigh Regional Office, DEM
Dale Overcash
Trevor Clements
Central Files
Farrington Road WWTP WLA file
Eno WWTP WLA file

L
State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor R. Paul Wilms
William W. Cobey, Jr., Secretary August 21, 1989 Director
A. T. Rolan, Director
City of Durham
Water Resources Department
101 City Hall Plaza
Durham, NC 27701
Subject: NPDES Draft Permit Comments
No. NC0047597 for the Farrington Road WWTP
No. NC0023841 for the Northside WWTP
Dear Mr. Rolan,
I have reviewed your comments regarding the above NPDES permits (June 27,
1989), and offer the following responses. Attached are the final Drafts for
your reference and review.
Stream Sampling Locations:
Northside WWTP - The upstream monitoring site was incorrectly listed in
the Draft permit as SR 1709 (Midland Terrace). The correct upstream sampling
location is the existing site at East Club Boulevard (SR 1669). None of the
downstream monitoring requirements for the Northside WWTP will be changed at
this time. The required sites are shown on the attached map.
Farrington Road WWTP - The upstream site contained in the Draft permit is
correct. The upstream samples should be taken 50 feet upstream of where the
effluent channel meets New Hope Creek to give the best indication of upstream
water quality. Due to the location and effects of the subimpoundment and the
fluctuating water level (seasonally), sampling at Interstate 40 will not give
representative data reflective of the true receiving waters.
The downstream monitoring site contained in the Draft permit was initially
recommended so that the data would capture the dissolved oxygen (DO) sag and
reflect the water quality that enters Jordan Lake. Since access may be diffi-
cult when the lake levels are high, downstream monitoring in the winter will
not be required at this location. After re-evaluation of the situation, the
downstream monitoring requirements will be as follows:
1) At DN2 of last summers sampling program; above the channelized
section behind the subimpoundment. June through September.
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

2) At SR 1107. All year.
3) At DN5, approximately 5.0 miles downstream of the discharge. June
through September.
These sites are labeled on the attached map. The parameters to be moni-
tored at these sights remain the same as those in the Draft permit.
Chlorophyll a:
The instream monitoring requirements for the Northside WWTP include the
monitoring of chlorophyll a and not chlorophyll o, as was mistakenly printed
in the Draft permit.
Residual Solids Storage:
Mention of the sludge storage facilities at the WWTP will be included in
the final permit. The Construction Grants Section, with the DEM Raleigh
Regional Office, provided the appropriate language based upon the approved 201
Facility Plan for the Farrington Road plant.
Metals Analysis:
The pretreatment headworks analysis performed by the City of Durham for
the Northside plant indicated the presence of cyanide in great enough quanti-
ties to warrant an effluent cyanide limit. Although your effluent monitoring
reports include the concentrations of other metals and toxicants, no cyanide
data is on record for this facility. Therefore, as was the case for the Far-
rington Road WWTP, DEM will not delete or modify the cyanide limit at this
time. After twelve months of data has been collected, Durham may request a
reevaluation of this parameter and apply for the appropriate permit modifica-
tion.
Your letter indicates that Durham would like to have the metal limitations
changed from a daily maximum to a weekly average for the Northside plant as
was recently allowed for the Farrington Road facility. A weekly average limit
that is determined through daily monitoring and protects to the chronic level
(i.e., current limits) would be acceptable, but a daily maximum limit would
still be necessary to protect against acute effects in the mixing zone. Per-
mit" limits based upon these criteria will be the same as those for the Far-
rington Road WWTP (with the addition of a cyanide limit), and are as follows:
Weekly Daily
Average Maximum
Cadmium 2 ug/1 4.5 ug/1
Chromium 50 ug/1 75 ug/1
Nickel 50 ug/1 75 ug/1
Lead 25 ug/1 34.5 ug/1
Cyanide 5 ug/1 15 ug/1
It is important to remember that these limits will require daily sampling
(i.e., Monday - Friday) for these five parameters, and that the weekly average
will be the arithmetic mean of the five daily samples.

Phosphorus Limit:
The winter phosphorus limit for the Farrington Road WWTP is 2.0 mg/1. The
phosphorus limits for the Farrington Road and Northside WWTPs are quarterly
with weekly monitoring requirements. Quarterly averages are the arithmetic
means of the weekly values for standard quarters (i.e., January - March, April
- June, etc.). The NPDES permits require that you only report the weekly
monitoring results; the quarterly averages and compliance will be calculated
by DEM's compliance system.
Expiration Dates:
Neither of these permits will be issued for a five year period. Because
the applications for permit modification were received when each of the exist-
ing permits had more than a year before expiration, the existing permit was
modified rather than renewed. Since the permits are not being reissued, the
existing expiration dates correctly stated in your letter remain in effect.
Toxicity:
The wording of the permits will not be revised such that toxicity non-
compliance can be defined as failure of bioassays in two consecutive quarters.
All facilities that are required to test for effluent toxicity have non-
compliance uniformly defined as the failure of two consecutive monthly tests.
As soon as a failure is reported, a second test must be performed within 30
days, continuing until the effluent passes. Therefore, the failure of two
consecutive quarterly tests is not adequate to determine toxicity non-
compliance, especially given the size and impact of these two Durham facili-
ties.
The permit wording also will not be changed with regard to the use of mul-
tiple laboratory analyses. Durham is welcome to submit toxicity test results
from more than one laboratory if you believe that one may not adequately rep-
resent the quality of the effluent. Both results will be carefully reviewed
and in the event of two conflicting results compliance will be based on the
quality of the tests, and not on the better results of the two.
Adjudication:
I am aware of Durham's pending Adjudicatory hearing on other aspects of
this permit and take this opportunity to inform you that the issuance of the
NPDES permits regarding the expansion of the Farrington Road and Northside
WWTPs will be put on hold until the adjudicatory proceedings are resolved.
Finally, it has come to the attention of my staff at the public hearings
for the Farrington Road and Northside facilities that the current discharge
limits were applied to the existing wasteflows. According to field studies
and modeling analyses performed by the Technical Support Branch, water quality
of the receiving waters is not expected to be adequately protected by the cur-
rent limits contained in either permit. The intention of the new limits is to
provide protection for the instream dissolved oxygen concentration and for
toxic impacts at both the existing and expanded flows. Therefore, per the
reopener/modification clauses in Parts II and III of the permits, you will
note in the attached Draft permits that the recommended final effluent limits
for the expanded flows will also apply to the existing wasteflows upon permit

reissuance. The Consent Order drafted jointly by DEM and the City of Durham
has adequate provisions to provide interim relief from these final limitations
while plant renovations and additions are in progress.
If these revised Draft permits are unacceptable to the City, you have the
right to an adjudicatory hearing upon written request within thirty (30) days
following receipt of the issued permit. This request must be in the form of a
written petition, conforming to Chapter 150B of the North Carolina General
Statutes, and filed with the Office of Administrative Hearings, Post Office
Drawer 11666, Raleigh, North Carolina 27604. If we do not receive any
response to the changes proposed above, the attached Draft permits will become
final and binding.
If you have any questions or comments regarding this matter, please con-
tact either Dale Overcash or Trevor Clements of my staff at [phone].
-14)4 z,,149 Ccci
R. Paul Wilms
cc: Arthur Mouberry, Raleigh Regional Office, DEM
Dale Overcash
Trevor Clements
Central Files
P %flA file
Northside WW`I'P WLA file

1
N o t-kit 610 e• W O T"'P
Movn Lo cam` 'L�►s
•
•
• ,* H.
j
r•
x
a
.1
•
�- `��Q•'`�� .. .\ •
t�
'i0 • 1. • _.,-.---'.:�
4
, ?.i ??4,
-•• • -ems -4.2?. /- 'i\e'‘'/'..-2 -..."': . -... • -
i r. ram)
5254 1rt SW
(NORTHWEST DURHAM)
•V
•
•t•+! I'l
F.
•
\(1
�.. -
•
N
W
O
•
•
:
NORfgL n
•
•

NC 54
Farrington Rood
WWTP
DN2
Mile 1.7
DN3•
USGS Gage _#
Mile 2.03
i -v ,41.
ON5 Mile 5.09
Jordan
Lake
Third Fork Creek
SR 1 107