NC0023868_Staff Comments_19930401

North Carolina Division of Environmental Management
Water Quality Section/Rapid Assessment Group
April 1, 1993
MEMORANDUM
TO: Coleen Sullins
THROUGH: Trevor ClementSY&
Ruth Swanek t2G5
Carla Sanderson
FROM: Dave Goodricgl
SUBJECT: Request for Modifications of NPDES Permits
South Burlington WWTP - NPDES No. NC0023876
East Burlington WWTP - NPDES No. NC0023868
Alamance County
030602
This is in response to the City of Burlington's request to modify the draft NPDES
permits referenced above. Since these comments are four pages long, they have been
attached to this memorandum which then refers back to each comment by number.
Comments from Technical Support on Attachment A• Comments on Draft NPDES Permit
No. NC0023876 - South Burlington WWTP, Alamance County
1. defer to Permits & Engineering Unit
2. Total residual chlorine is limited as a daily maximum because the difference between the
chronic effect level (17 µg/i) and the acute effect level (28 µg/1) is small, making
differentiations between weekly and daily averages statistically insignificant. As a result,
the 19 µg/l limit for total residual chlorine as such is correct. The argument that this will
cost more money than meeting a monthly average limit of 19 µg/l is questionable, since it is
doubtful that reducing total residual chlorine by another 9.5 µg/l will cause additional
expenditure of resources. This is especially improbable given the standard error of
measurement for total residual chlorine is well in excess of 9.5 µg/l. .
3. defer to Permits & Engineering Unit
4. Agree. Upstream Site #2 may be deleted from the South Burlington permit, but the
downstream sampling location for East Burlington (SR 2158) should remain.#
5. Agree. Downstream Site #1 should be the SR 2116 bridge on Alamance Creek.#

6. Agree. Permit should include a clause such as, "Samples routinely collected from a
boat do not have to be gathered on days the boat operator deems too dangerous to collect
such samples."
7. Again, metals and other toxicants are normally limited as daily maximums not monthly
averages. The limits for metals should remain the same, unless the City of Burlington
would agree to receiving both a daily maximum and a weekly average. Outlined below are
the two choices the facility. has - Choice #1 is to keep the limits for metals as daily
maximums, and the Choice #2 is to have less stringent limits for daily maximum limits with
the addition of a weekly limit.
Choice #1 - Daily maximum limits only (units are µg/1)
Parameter
Daily Maximum
Cadmium
2.0
Chromium
58.0
Nickel
102.0
Mercury
0.014
Cyanide
5.0
Lead 29.0
Choice #2 - Daily maximum and weekly limits (units are µg/l)*
Parameter
Daily Maximum
Weekly Average
G
Cadmium
�G �e
5.4
2.0
C l
Chromium
232.0
58.0
t
Nickel
�a�.
408.0
102.0
Mercury
�,�,ti�
0.06
0.014
Cyanide
20.0
5.0
Lead
41.0
29.0
*NOTE: If the permittee chooses #2, the permittee may choose to collect multiple samples
for the week (for substances where holding of samples for this amount of time is allowed)
and determine the number of analyses to be run that week on the result of the first sample.
For example, if the first sample is below the weekly average, then no more analyses need
to be run for that week.
Another issue discussed in this comment is laboratory accuracy. Although present
laboratory techniques may not detect levels as low as the limits given in the South
Burlington WWTP permit, measurement methods may improve during the term of this
permit. Moreover, effluent limits were based on water quality standards which are below
detection limits. Basically, no mercury or cyanide should be detected in the effluent. If
laboratory errors are suspected, then methods of analysis should be reviewed. Some
permittees use duplicate sampling when laboratory error is suspected. That is, a sample

may be split and half may be stored. If a problem in the analysis of the first sample is
suspected, then the stored duplicate sample may be analyzed to recheck the result.
8. Agree. Toluene may be dropped from weekly sampling requirements. Priority
pollutant analyses will be checked for the presence of toluene in the future.
9. Agree. Tetrachloroethylene may be dropped from weekly sampling requirements.
Priority pollutant analyses will be checked for the presence of tetrachloroethylene in the
future.
10. Disagree. Requirements for long-term BOD monitoring have been approved by the
Director (see attached memorandum dated March 4, 1993). The approved method for this
test has been attached to be sent to staff at Burlington. It is likely that this test will not be
required after this permit cycle (1996), but this depends on additional information needs.
11. Disagree. Mass limits are not given for municipal discharges which have been given
limits to protect water quality standards (as opposed to technology -based limits). Mass
limits are calculated assuming the discharger will have an actual wasteflow at the permitted
level. This is not usually the case, so mass limits may actually allow concentrations to be
excessively high where effluents dominate flow in the receiving water under 7Q10
conditions.
#In order to clarify what are the correct instream monitoring locations for the South
Burlington WWTP permit, I have provided a copy of a letter describing these sites. Please
note that they differ from the locations requested in the WLA. This was an oversight on
my part. Please call me (extension 508) if you have any questions.
Comments from Technical Support on Attachment B: Comments on Draft NPDES Permit
No. NC0023868 - East Burlington WWTP, Alamance County
1. defer to Permits & Engineering Unit
2. defer to Permits & Engineering Unit
3. defer to Permits & Engineering Unit
4. Agree to change upstream sampling location to SR 1712.
5. Daily maximum limits for toxicants have been given correctly. Metals and other
toxicants are normally limited as daily maximums not monthly averages. The limits for
metals should remain the same, unless the City of Burlington would agree to meet both a
daily maximum and a weekly average. Outlined below are the two choices the facility has -
Choice #1 is to keep the limits for metals as daily maximums, and the Choice #2 is to have
less stringent limits for daily maximum limits with the addition of a weekly limit.

. L ,
Choice #1 Daily maximum limits only (units are µg/1)
Parameter Daily Maximum
Cadmium 5.6
Chromium 140.0
Nickel 2 4 7.0 * *
Mercury . ' 0.034
Lead 65.0'
Choice #2 . - Daily maximum and weekly limits (units are µg/1)*
Parameter Weekly Average Daily. Maximum
Cadmium 5.6 12.6
.Chromium 140.0 560.0
Nickel 2 4 7.0 * * 988.0
Mercury 0.034 0.136
Lead 65.0 95.0
_ *NOTE: If the pernuttee chooses ##2, the permittee may choose to collect multiple samples
for the week -(for substances where holding of samples for this amount of time is allowed)
and determine the number of analyses to be run that week on the result of the first sample.
**ALSO, PLEASE NOTE THE FINALIZED WLA HAD AN INCORRECT VALUE
FOR NICKEL. THIS LIMIT SHOULD BE CHANGED FROM 140 TO 247 µg/l.
6. Agree. Monitoring for bis(2-ethylhexyl)phthalate may be dropped.
7. Copper has been found at high levels in the effluent of this facility. It is recommended
that monitoring be given at twice per month which would be consistent with the other
metals for which monitoring only is required 9
8. Disagree. Mass limits are not given for municipal discharges which have been given
,limits to protect water quality standards (as opposed to technology -based limits).
The City of Burlington discharges to a section of the Haw River which has limited
assimilative capacity remaining for toxicants as well as oxygen -consuming wastes. As a
result, it is likely that both discharges from the City of.Burlington, the City of Graham
WWTP, and other interacting discharges may have limits for parameters contained in their
NPDES permits reduced. This will be determined after the promulgation of the Cape Fear
River Basin management strategy scheduled for 1996.

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City of Burlington
TELEPHONE ,919' 222-5022 • Box 1358
\ORTH CAROLINA 27216
February 15, 1993
Mr. Steve W. Tedder, Chief
Water Quality Section
NCDEHNR/DEM
P. 0. Box 27687
Raleigh, NC 27611-7687
SUBJECT: Comments on Draft NPDES Permit No. NCO023876
Comments on Draft NPDES Permit No. NCO023868
City of Burlington; Alamance County
Dear Mr. Tedder:
WILLIAM R. BUDDY.. BAKEP..
C1 Y
The City of Burlington respectfully submits comments on the above
referenced draft NPDES discharge permits as attachments A and B to this
letter. Please incorporate these comments into the official records of these
permits. We hope that you will give favorable consideration to our concerns
and objections.
If you have further questions, please contact Mr. Randall Kornegay
[phone] or Mr. Stephen Shoaf [phone] for additional clarification.
Sincerely,
W. R. Baker
City Manager
WRB /vh -a
PC: Randall Kornegay
Stephen Shoaf
Coleen Sullins�t'`�'t``J L="i Y�
Larry Coble
TECHNICAL ��,OVPORT BRANCH

6
i
ATTACHMENT A
Comments on Draft NPDES Permit No. NC0023876
South Burlington WWTP, Alamance County
1. The Notification of Intent to Issue a State NPDES Permit, the draft
permit cover sheet, and the Supplement to Permit cover sheet all refer to
the South Burlington WWTP on Boy Wood Road as being in Burlington. In
fact, this treatment facility is located in Alamance County outside the
limits of incorporation of surrounding cities or towns.
2. The proposed effluent limit for residual chlorine in summer and winter -is
a daily maximum of 19 pg/1. Our previous permit included a monthly
average limit of 19 pg/1 residual chlorine and a weekly average limit of
28.5 jug/l. We feel that the daily maximum limit of 19 pg/1 is -too
strict. Given the variable characteristics of the wastewater, the
reliance on multiple feedback signals to control chlorine and sulfur
dioxide dosages, and the instantaneous flow variability due to filter - —
�,l// backwashes it is conceivable that daily results could exceed 19 Pg/l. To
overcome the lag in feed equipment response time and the percent error
inherent in the equipment, a daily maximum limit would require a gross Y
overfeeding of sulfur dioxide. This will increase operation costs
because sulfur dioxide is expensive, and may adversely affect the
effluent toxicity. We request revision back to the conditions of the
previous permit.
3. The proposed effluent limit for total phosphorus in summer is a monthly
average of 2.0 mg/l. Our previous agreement with the permitting
authority, as reflected in our previous discharge permit was a quarterly_
�average limit o g/1 with weekly sampling. Both the City of Durham
PI) anrange Water and Sewer Authority have had permits issued within the D last 12 months that contain a quarterly total phosphorus limit. In the
�QQ interest of consistency with past permit conditions and the constraints
I placed on neighboring municipalities, we request that the phosphorus
limit be maintained at 2.0 mg/l as a quarterly average with weekly
(� sampling.
4. Sample location "Upstream Site 2" should be eliminated. It is a few
hundred yards downstream of the East Burlington WWTP downstream sampling
site on the bridge at SR 2158. Both plants collect instream samples on
the same day,, therefore "Upstream Site 2" is redundant. Also, there is
If
oaccess point at "Upstream Site 2" to collect a representative sample.
was dropped from the previous permit based on an August 8, 1990 letter
rom Steve Tedder.
5. The "Downstream Site 1" location should remain at the SR 2116 bridge on
Alamance Creek. The proposed Haw River location does not allow access
for a representative sample. It was dropped from the previous permit.
6. "Downstream Site 2" requires the use of a boat to gain access to a
representative sampling point. The permit should include a clause
exempting sampling if the river flow is too high (dangerous) as was
agreed upon in the above referenced letter of August 8, 1990. The letter

ATTACHMENT A (Continued)
Comments on Draft NPDES Permit No. NCO023876
South Burlington WWTP, Alamance County
states that flow at USGS gauge 02096500 at Haw River must be less than or
equal to 350 cfs. This was not an issue under the previous permit, but
should be included for personal safety.
7. All summer and winter effluent metals limits are proposed as daily
maximum limits. This is inconsistent with the monthly average limits in
the previous permit. Given the potential for sample contamination,
analytical errors and interferences, and the percent errors inherent in
the analyses as you approach the method detection limits, several of
these limits appear too strict, and to make these a daily maximum limit
is potentially more damaging. Based on 1992 data, the following
parameters would have been violated:
a. Lead, one value exceeded 29 pg/l.
b. Mercury, our detection limit is 0.2 fag/l. We reported several 0.2
)ig/l values, possibly as a result of proximity to the detection
limit of the method.
c. Cyanide, more than 7 samples exceeded 5.0 )ig/l. The source of the
cyanide has not been determined, and may be the result of breakdown
of organic matrix interferences present in the influent.
d. Cadmium, 2.0 µg/1 was not exceeded in 1992, but several 2.0,ug/1
values were reported.
The City requests that the effluent limits for lead, chromium, cadmium,
nickel, mercury, fluoride, and cyanide be changed to monthly average
limits. We also request that limits for mercury and cyanide be revised
to a higher limit to reflect the actual plant treatment and lab analysis
capabilities.
8. The proposed effluent limit for toluene as a daily maximum with weekly
sampling does not seem reasonable. Toluene was not detected in the 1990
or 1991 annual pollutant analysis, and in 1992 only 2 jug/1 was detected.
The analysis, according to Burlington Research costs $70.00 per sample.
Weekly sampling would cost $3640.00 per year, a financial burden. The
City requests that toluene be dropped from the list of parameters on the
NPDES permit, and remain as part of the annual pollutant analysis.
9. Monitoring for tetrachloroethylene will cost $110.00 per sample according
to Burlington Research. It was not detected in the 1990 or 1991 annual
pollutant analysis. In 1992, 12 µg/1 was detected. The City does not
agree that tetrachloroethylene should be monitored as frequently as
monthly. The City requests that the frequency be revised to remain as
part of the annual analysis.
10. The long-term BOD requirement found in Part III of this draft permit
should be removed. There is no approved method at this time and the
value of data generated from such a test has not been demonstrated. The
City requests that this requirement be removed, recognizing that a clause

t
ATTACHMENT A (Continued)
Comments on Draft NPDES Permit No. NC0023876
South Burlington WWTP, Alamance County
in the permit allows it to be reopened at a later time to insert
additional requirements.
11. Once again the City requests consideration for applying mass/day limits
rather than concentration limits. The South Burlington WWTP receives a
large industrial contribution and current discharge flows are well below
the permitted 12 MGD. Mass/day limits would be appropriate in this
situation.

V
ATTACHMENT B
Comments on Draft NPDES Permit No. NC0023868
East Burlington WWTP, Alamance County
1. The Notification of Intent to Issue a State NPDES Permit, the draft
/ permit cover Sheet, and the Supplement to Permit Cover Sheet all refer to
l/ the East Burlington WWTP on Quarry Road as being in Graham. In fact,
this treatment facility is located in Alamance County outside the limits
of incorporation of surrounding cities or towns.
j 2. The description of facilities on the Supplement to Cover Sheet omits the
flow equalization basin following the grit chamber and ahead of the
primary clarifiers. The flow equalization basin needs to be inserted.
3. The proposed summer and winter effluent limit for total phosphorus is a
monthly average of 2.0 mg/l. Our previous agreement with the permitting
authority, as reflected in our previous discharge permit was a quarterly
L average limit of 2.0 mg/1 with weekly sampling. Both the City of Durham
and Orange Water and Sewer Authority have had permits issued within the
last 12 months that contain a quarterly total phosphorus limit.
Greensboro's phosphorus limit is also based on a quarterly average. In
the interest of consistency with past permit conditions and the
constraints placed on neighboring municipalities, we request that the
phosphorus limit be maintained at 2.0 mg/l as a quarterly average with
weekly sampling.
4. The description of the upstream sampling point states "50 feet from
discharge." There is no sampling access available to guarantee a
representative sample. We have been sampling off of the Hopedale Road
(SR 1712) bridge. Please review this sample location.
5. All summer and winter effluent metals limits are proposed as daily
maximum limits. This is inconsistent with the monthly average limits in
the previous permit. Given the potential for sample contamination,
analytical errors and interferences, and the percent errors inherent in
the analyses as you approach the method detection limits, the proposed
limit for mercury is too low for our analytical method. We routinely
report <0.2 jug/l, however because we are at the method detection limit we
have also reported several 0.2 pg/1 values in 1992. Changing several of
the metals from monthly to weekly sampling frequency represents a steep
increase in our analytical workload.
The City requests that the effluent limits for lead, chromium, cadmium,
nickel, mercury, and fluoride be changed to monthly average limits. The
City further requests that the limit for mercury be revised to a higher
limit to reflect the actual plant treatment and lab analyses
capabilities.
6. Bis (2-ethylhexyl) phthalate was reported in the 1990 and 1991 annual
pollutant analyses at concentrations of 27.8 pg/1 and 99,ug/l. It was
not detected in the 1992 APA. Burlington Research has given us a price
of $150.00 to report all peaks that come out of the chromatograph during

N
s
ATTACHMENT B (continued)
Comments on Draft NPDES Permit No. NC0023868
East Burlington WWTP, Alamance County
the expected detention time window of bis (2-ethylhexyl) phthalate. This
would be an unconfirmed valve. To get a confirmation with standards and
a library match will cost $300.00. This translates to $15,600.00 per
year for weekly sampling. This is a compound found in plastics and
polymers and is frequently found as a sample contaminent from tubing and
containers. Because it has not been detected in concentrations
approaching the proposed limit, the City feels that a daily maximum limit
with weekly sampling is unreasonable. We request that this compound be
dropped from the NPDES permit, and remain as part of the annual pollutant
analysis.
7. The City requests that summer and winter monitoring for copper be revised
to a monthly sampling frequency as it was in the previous permit.
8. Once again the City requests consideration for applying mass/day limits
rather than concentration limits. The East Burlington WWTP receives a
large industrial contribution and current discharge flows are well below
the permitted 12 MGD. Mass/day limits would be appropriate in this
situation.