NC0023884_Staff Comments_19920828

DIVISION OF ENVIRONMENTAL MANAGEMENT
August 28, 1992 7-7
MEMORANDUM TO: Steve Tedder ram. tt
FROM: D. Rex Gleason SEP 3
PREPARED BY: Richard Bridgemanw �: ATER 'Q, L. T Y
SUBJECT: SOC Request
City of Salisbury/Grant Creek WWTP
NPDES Permit No. NCO023884
EMC WQ No. 92-10
Rowan County
On 27 ..August MRO staff met with City of Salisbury
representatives, including the Mayor and City Manager, to begin
negotiations on an SOC. This memorandum is to advise you and
Dennis Ramsey of difficulties in the negotiations, and to ask your
help in expediting activities in Raleigh.
Although the City was recently assessed a civil penalty for
effluent limits (Chronic Toxicity, TSS, Fecal Coliform, pH, and
Mercury) violations, continuing noncompliance is related to
effluent mercury concentrations only. The SOC addresses mercury
only.
The City is undertaking a minor construction project, which
when completed, will facilitate both return activated sludge and
waste activated sludge operations. Concurrent with the above
construction project, the City will take the aeration basin out of
service to remove excess solids. During this time the facility
will be operated using primary clarification, high -rate trickling
filters, "and secondary clarification, which will necessitate an
interim BOD_ limit. Currently, solids in the chlorine contact
basin are removed manually; the City also proposes to install
pump/piping to simplify solids removal from the basin.
The City believes that mercury is entrained in the solids and
supernatants being recycled through the system. All of the above
activities will enhance removal of solids and mercury from the
cr's system. These activities, plus operational changes and
,y c46Ai pretreatment program activities, may result in compliance; there is
a�`�k of enough data to suggest that they will result in compliance. ��
a17 The City, therefore, has requested approval to relo t the
outfall to the Yadkin River. In fac , re oca ion o the outfall is
the City's solution to e mercury and intermittent effluent
toxicity problems. They will probably not enter into an SOC if
they have to commit to 'Less than that to achieve compliance.

Mr. Steve Tedder
Page -Two
August 28, 1992
.This Office proposes, with the agreement of the City, to
postpone SOC negotiations until the Division - ompletes, a .ion on ,
the City
outfall relocation re uest. Correspon ence dated March
3, rom Trevor Clements to Michael Aquesta of Peirson &
Whitman, in response to a request. for speculative limits; indicates
that the Division is not recommending a direct discharge to. the
Yadkin Rive r.,'..Unless there is a potential for approval, of, the
..-outfal,l relocation, there is little point in drafting an SOC
document with that as the main activity.. This Office recommends
that action on this matter be -expedited.
Staff also discussed with.the City their request to use for
,other governmental public purposes revenues received from the '
levied -one-half percent sales tax. The exemption would cover the
period from July 1, 1992 through June 30, -1994. It has'been-
determined-that,proposed major projects, such as construction of
the relocated outf all line from the. Grant Creek WWTP to the Yadkin
River, construction of a force main from the Town Creek WWTP to the
Grant Creek outfall line to combine. the. discharges, and
'construction of a new treatment plant, would all occur after July
1, 1994. Sufficient monies have been set aside to fund.the minor
construction projects scheduled prior to July 1, 1994. This
Office, therefore, recommends approval of the City's petition.
Please advise if you have questions.
cc: Mr. -Dennis Ramsey
i7'iu ..7

J
DIVISION OF ENVIRONMENTAL MANAGEMENT
June 19, 1992
Memorandum
To: Don Safrit
From: Carla Sanderson
Through: Ruth Swanek
Trevor Clements
it
Subject: Comments on letter from the Town Salisbury (Grants Creek WWTP)
Requesting Modification of NPDES Permit Limit for Mercury
Technical Support would like to comment on the subject letter dated April 20,
1992 from Mr. John Vest, Utilities Director for the Town of Salisbury. The
issues raised in I.A. and II. refer to development of the mercury standard and
should be addressed by the Planning Branch. Technical Support (TS) will present
the following response to the issues raised in I. and II.B.:
In reference to Mr. Vest's calculation for determining NPDES limits (I.), TS
would like to clarify the extent of an evaluation when determining an NPDES
permit limit. The attached procedure for calculation of toxics limits are TS's
Standard Operating Procedure (SOP) approved by EPA and performed for all
facilities with toxic components in the discharge. Pretreatment information is
also evaluated for municipalities with a developed pretreatment program. Data
obtained from a pretreatment headworks analysis is input into a spreadsheet
which evaluates the allowable concentrations and compares these values with
predicted or actual effluent concentrations.
In reference to Mr. Vest's comments in II.B. requesting use of the mean annual
instream flow for calculation of the limit for mercury, I would like to refer to
15A NCAC 2B .0200 which lists mercury as a standard to protect aquatic life and
per 2B. 0200 (a) (2)), the 7Q10 is used to develop the NPDES limit. If the
mercury stream standard was meant to protect human health, the 7Q10 will also be
used to calculate the limit (per 2B.0200 (a) (3) (A)). Mercury is a
noncarcinogen, therefore the 7Q10 is used in evaluation of an allowable
concentration and the limit should remain the same (0.018 ug/1).
In II.B. Mr. Vest also requested that the average annual effluent flow be used
to calculate a limit. The total design wasteflow is used to calculate the
allowable effluent limits for all parameters. Since compliance for toxics
limits is based using a daily maximum value, the average annual effluent flow
would not be appropriate in determining the allowable concentration for mercury.
Please let me know if you have any questions concerning this matter.
Attachment
cc: Kent Wiggins

C4, a
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II. WASTELOAD ALLOCATION PROCEDURES
C.3.b. Mass.Balance Approach to Calculating Toxic Limits
The theory of "Conservation of Mass" (i.e. mass balance) should be used in
most cases to develop effluent limits for specific pollutants, whether they are
chemically conservative or non -conservative. Using a mass balance approach,
the effluent limit for a given toxicant is set to protect the stream standard at
the mixpoint below the outfall under design flow conditions:
Cw [ (Qd * Cd) - (Qu * Cu) ] / Qw
where: Cw Allowable Effluent Pollutant Concentration
Qw Wasteflow (i.e. Permit Design Flow)
Cd Allowable Downstream Pollutant Conc. (i.e. standard)
Qd Downstream flow (i.e. Qw + Qa)'
Cu Upstream Pollutant Concentration (i.e. background)
Qu = Upstream flow (i.e. 7Q10 or minimum daily release)
Background concentrations should be determined by review°of ambient or self -
monitoring data. The choice of background concentrations should reflect, where
possible, what is observed during flows at or near the critical design condition
(i.e. 7Q10 or minimum daily flow). Where data are listed below analytical
detection levels or where no data are available, the background concentration
should be assumed to be zero.unless a substantive reason can be provided for an
alternative assumption.
NOTE: See SOP Manual Section II.C.3.e. for cases where interaction of toxics
discharges occurs.

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Ms. Roseanne Barona
Acting Supervisor of NPDES Unit
Division of Environmental Management
P. O. Box 29535
,Raleigh, North Carolina 27626-0535
Subject: Modification of NPDES Permit
Dear Ms. Barona:
April 20, 1992
S4L 4 4,)J� i 1&AJ1_P
No NC 0023884
We hereby request that the Division of Environmental Management
(DEM) review and modify the mercury discharge limit in NPDES Permit
Wo. NC 0023884 for Grants Creek Wastewater Treatment Plant. Our
research indicates that the permit limitation is unreasonably
stringent and that the methods for determining compliance with the
limitation overstate mercury concentrations in the effluent from
the plant. We request an opportunity to discuss our findings and
select a set of amendments that will make compliance possible while
continuing to protect the environment and human health.
THE NPDES PERMIT LIMITATION IS UNREASONABLY STRINGENT
We understand that NPDES permit limitation was calculated as
follows: (maximum in -stream concentration) x (dilution factor).
We understand that the maximum permissible in -stream concentration
is 0.012 pg/l and that the dilution factor was calculated as
follows:
(maximum POTW permitted discharge) + (Grants Creek 7010)
maximum POTW permitted discharge
Our research indicates that both the in -stream concentration an
the dilution factor are unreasonably stringent.
I.A. Maximum In stream Concentration Of 0.012 uaa
Is Unreasonably Stringen
The stated purpose of the North Carolina maximum in -stream mercury
concentration is to protect "aquatic life" from excessive mercury.
15A NCAC 213.0211(b) (3) (L). However, the 0.012 jug/1 numerical
value was generated by the EPA as a non -enforceable human health
CITY OF SALISBURY
P.O. BOX 479, SALISBURY, NORTH CAROLINA 28145-0479

criterion based on methylmercury. Therefore, the 0.012 pg/1
concentration is not a mercury standard, is not a standard to
protect aquatic life, and should not be enforced as either.
The EPA explained in Ambient Water Quality Criteria for Mercury -
1984 that the extremely low concentration is intended to protect
-human *'consumers of fish and is much lower than necessary to
".protect aqua%: c life." The numerical value is therefore not a
reasonable concentration to achieve the purpose of the North
Carolina standard.
The 0.012 jug/1 value is not even appropriate for protecting human
health in our situation because EPA assumed that all of the mercury
in receiving waters is methylmercury. Methylmercury is "the most
chronically toxic of all tested mercury compounds," See EPA
document at p. 23, and unlike other mercury compounds, tends to
bioaccumulate. The 0.012 jug/1 value therefore incorporates an
unreasonably high bioconcentration factor (the multiplier for
probe,,=irg mercury concentration in aquatic animals) of 61,700.
We are unaware of any evidence of methylmercury in our situation.
There is therefore apparently no justification based on human
health or aquatic life for imposing what is, in effect, a
Methylmercury standard.
North Carolina's human -health -'based standards for mercury allow for
direct human consumption of 100 times higher concentrations. The
North Carolina Rules governing Public Water Supplies set the MCL
for mercury -at 2.0 pg/1. 15A NCAC 18C .1509. This same value is
found in the Federal Safe Water Drinking Act ("SWDA") Regulations
which set the Maximum Contaminant Level (MCL) and Maximum
Contaminant Level Goal (MCLG) for Mercury at 2.0 ug/1. MCLG's are
"set at concentration levels at which no known or anticipated4,L602���
adverse health effects would occur, allowing for an adequate margin d �5 rtiO �s
of safety. " 56 FR 3531, January 30, 1991. This is the most p�e�l��
recently set MCL of all the federal and state regulations limiting
mercury in water and is based on the most recent research.
Similarly, the North Carolina Groundwater regulations limit the
concentration of mercury to 1.1 jig/1 in Class GA groundwaters. 15A
NCAC 2L .0202 (g) (45). Class GA groundwaters, the most
stringently regulated groundwaters, are protected for existing or
potential sources of drinking water supply for humans. 15A NCAC
2L .0202(g) (45).
In summary, achieving the 0.012 pg/1 concentration assuming that
it is possible, would no doubt impose tremendous costs on our
taxpayers with no benefit to the public or the environment. We
therefore request that DEM apply an in -stream concentration in
calculating the discharge limitation for mercury that is at least
as high as the groundwater standard. As you know, groundwater
discharges into Grants Creek throughout the course of the stream.'
OA

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We believe this in -stream concentration, which is one-half of that
allowed for public drinking water supplies, would protect human
health while setting a more 'realistic and logically consistent
standard for Salisbury's treatment plant.
The North. Carolina water quality standards provide for the use of
mean annual flow for calculating water, quality based effluent
limitations to protect human -health from carcinogenic substances
through the consumption of fish. 15A NCAC 2B.0206(a) (3) (B). The
dilution factor for Salisbury's mercury discharge into Grants
Creek, however, is presently calculated using 7Q10 flows instead,
which unjustifiably reduces the dilution factor. The 7Q10 flow is
only appropriate for the calculation if the stream is a water
supply or the in -stream standard is designed "to protect aquatic
life from chronic toxicity." 15A NCAC 2B.0206(a) (2). The use of
7Q10 to calculate the dilution factor is incorrect when used with
the human -health -based 0.012 pg/1 concentration. Even if mercury
were found to be (it is not) a carcinogen, mean annual flow would,
be used to protect human health from mercury through the
consumption of fish.. We therefore request that mean annual flow,
,be used in place of 7Q10 to calculate the dilution factor.
The dilution factor is also biased downward by the use of the
maximum permitted effluent flow rather than the actual effluent
flow. We therefore request that the average annual effluent flow
be used to calculate the dilution factor instead of the permitted
maximum.
II. REQUIRED MERCURY ANALYSIS IS INAPPROPRIATE
The test required to analyze our samples is -a manual or automated
cold vapor test which tests for total mercury. 15A NCAC
02B.0505(e) (4) incorporating 40 CFR 136.3(a). However, even EPA's
0.012 pg/1 criterion for mercury was based on an "acid -soluble"
measurement because EPA recognized that measure to be more
"scientifically correct," as stated at p. 24 of the 1984 EPA
document. In order to properly apply this "acid -soluble" criterion
it is necessary to either use an acid -soluble test or to convert
the results of a total recoverable test using a biological or
chemical translator formula. Using the total recoverable method
without a translator results in an overstatement of the relevant
mercury concentrations. See EPA document at p.24. We therefore
request that our permit incorporate either an acid -soluble test or
a translator formula.
1 We are still uncertain how the DEM or USGS has calculated
our 7.Q10 flow.
3

CONCLUSION
Salisbury believes the permit should be modified to restrict in -
stream mercury concentrations to the same level required by the.
groundwater standard and should calculate the dilution factor using
the mean annual flow of the creek and the mean annual flow of our
effiuenz. 5aiisbury further believes that the testing of our
samples should incorporate an appropriate translator or should use.
an acid -soluble test. Salisbury is convinced that these
modifications will not adversely affect human health.
We appreciate your consideration of our request and look forward
to working with you on.this matter.
Sincerely,
John C. Vest, P. E.
Utilities,Director
JCV:sph
cc: Margaret.H..Kluttz,,Mayor
City Council Members
David W. Treme, City Manager
Rivers Lawther, City Attorney
Troy Doby, President, Peirson & Whitman
4

DMSION OF ENVIRONMENTAL MANAGEMENT
February 18, 1993
TO: Richard Bridgeman
Winston-Salem Regional Office
_FROM: Betsy Johnson 9PP
Technical Su Branch
THROUGH: Mike Scoville MPS
Ruth Swanek r20
SUBJECT: Speculative limits for the proposed City of Salisbury WWTP
Rowan County
- NPDES No. NCO082279
The City of Salisbury has applied for a new permit number for the
relocation of its two discharge points (Grants Creek and Town Creek WWTPs)
and eventual construction of a new WWTP. The Division would prefer not to
issue a new permit number. Rather, the Grants Creek and Town Creek permits
should be modified as relocations with existing limits for oxygen consuming
wastes. Each facility should continue effluent monitoring at its own monitoring
site. In addition, there should be a monitoring site below the confluence of the
two outfall lines. The region and the City of Salisbury should decide which
permit should contain the end -of -pipe monitoring requirement. Upon
construction of a new WWTP, there will be one effluent monitoring location.
One of the Town's two permits will then be rescinded.
A draft wasteload allocation for the City of Salisbury's proposed
relocation to the Yadkin River is unavailable at this time. However, the limits
for oxygen consuming wastes will be:
summer winter
BOD5 (mg/1) 5 10
NH3-N (mg/1) 2 4
DO (mg/1) 6 6, * dechlorination or alternate disinfection
will be required
.. As I mentioned in our phone conversation, nutrient limits will be
required due to documented eutrophication in High Rock Lake. These required
limits will be determined based on the results of a Walker Lake Model for High
Rock Lake. Final allocation runs are pending the completion of a nutrient
budget for High Rock Lake.

Metals limits and toxicity testing requirements are usually based on the instream
waste concentration under design wastef.ow and summer 7QIO conditions
(11.1% to 2.9% depending on the design flew of the prowsed plant). However,
this assumes complete mixing with the entire river and the allowable limits
based on the high dilution exceed the acute criteria for individual metals. Due
to the width of the river and the proximity of other discharges with metals
limits, plume modeling may be done to determine the near -field mixing. A
submerged outfall with a diffuser may be required to improve mixing.
Preliminary designs of the outfall would be extremely helpful in conducting our
modeling work.
Please call me if you have any questions regarding the development of
the wasteload allocation.
cc: Coleen Sullins

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DIVISION OF ENVIRONMENTAL MANAGEMENT
November 26, 1990
Memorandum
To: Trevor Clements
From: Carla Sanderson
Through: Ruth Swanek s�`>
Subject: Ground Remediation Project
Salisbury -Grants Creek WWTP
Limit for 1,2-dichloroethane
I am writing in response to your inquiries of the memo dated October 25, 1990 to
Steve Tedder from Greg Thorpe. During our recent analysis concerning the permit
renewal for the Salisbury -Grants Creek WWTP, information regarding the ground
water remediation projects was not available. Therefore, no analyses were per-
formed on the constituents that may be present from the remediation projects.
Since the National Starch & Chemical Company is planning to send ground water
remediation waters to the Salisbury -Grants Creek WWTP, I performed a quick ana-
lysis using the Federal criteria (98.6 ug/1) for 1,2-dichloroethane. Using the
Grants Creek average stream flow of 79 cfs and the Salisbury WWTP design flow of
7.5 MGD, the analysis produced an allowable limit of 789 ug/l
1,2-dichloroethane.
The OCPSF guidelines were also reviewed and compared to the water quality based
limit. With the end of pipe biological treatment, the 1,2-dichloroethane limit
would be 211 ug/l daily maximum and 68 ug/l monthly average using the OCPSF
guidelines.
Since the OCPSF Guideline is more stringent than the water quality based limit,
the guideline limit of 211 ug/l daily maximum and 68 ug/1 monthly average should
be given to the facility.

DIVISION OF ENVIRONMENTAL MANAGEMENT
October 25, 1990
MEMO TO: Steve Tedder
FROM: Greg Thorpe
THROUGH: Alan Klimek
o---
SUBJECT: Surface Water Remediation for
Chemical Company (Salisbury)
OCT 2 9 1990
Na�ional Starch &
and CGIA Maps
I received a telephone call from Bruce Nicholson of the
Superfund Branch of Solid Waste Management. He had questions
regarding our ability to develop a water quality based limit
("standard") for 1,2-dichloroethane to be applied to a stream on
the property of National Starch & Chemical Company. Groundwater
and soil remediation are ongoing at the site, but for reasons
unknown EPA has been reluctant to force surface water remediation
upon the facility. Data has been collected to show that surface
water remediation is necessary. (I'm not sure who collected the
data, but the Superfund Branch is supposed to send it to us).
The Superfund Branch intends to make a formal request that we
provide them with a number to use as a water quality "standard"
for 1,2-dichloroethane. Lee Crosby, Superfund Section Chief, is
supposed to send a memo to you transmitting their data and
officially making the request for a standard. I'm not sure who
in the Region is involved with this. I intend to inform the
Region concerning our response to the Superfund Branch. Please
advise if there is anything else I need to communicate to the
Region regarding this matter.
On another subject, Tom Tribble called to say that 12 water
supply maps are being finalized and the remaining maps should be
completed within a matter of weeks. The time frame for receiving
all of the final maps still seems very uncertain, however. I
tried to communicate the need to get these maps to local
governments, but I'm not sure Tom understands our growing sense
of urgency that these maps be completed within a short time
frame. Any assistance you can provide in getting that message to
CGIA will be greatly appreciated.
GT/kls
starch.mem/Vol.15
cc: Julia Storm
Trevor Clements
Ken Eagleson
Dennis Ramsey
Brenda Smith
Rex Gleason

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SALISBURY
WA TER
RESOURCES
Mr. Donald L. Safrit, PIE.
Permits and Engineering
Division of Environmental Management_
post office Box 27687
Raleigh, North Carolina 27611-7687 October ZI, 1990
Dear Mx. Safri t:
Thank you for the o,pportuill E.y to oommont on tht Drag
Permit for our Grant Creek Plant (# 14C0023884) and for
meeting with us on Friday, October 19 to discuss the permit,
We do have several comments and concerns about the problems priprsed
permit and look forward to resolving any
to
the permit issuance. Specific comments follow.
it is noted that the new permit will expire after three
years. Is this to allow for basin -vide permitting as
previously discussed?
The anaerobic digestors noted on the Supplement on to
Permit Cover Sheet are currently undergoing
aerobic operation.
Coli.f
The lowered fecal orm limit will be very difficult
non -
if not impossible to meet while maintaining effluent non --
limit will require increased
toxicity. Meeting the proposed
use of both disinfectant and de -chlorination reagent. This
is most likely to increase effluent toxicity.
The change in dilution percentage foz Chronic Toxicity
is noted. How was this change calculated?
The need to gather data to evaluate the impact of the
is
Grant creek stream °rethecut d,�k but Riverin and
aadditzonR of theack D2
understood and appreciated, to serious
sampling requirements will subject the city
liability problems. The D2 Sampling location will onlbe
ed to
accessible by boat, The city is not staffed ar equipp
perform intensive stream sampling utilising boats. Activity
such as this is particularly hazardous during Winter weather
conditions. Will the state consider
ecit inf pe g this
forming
monitoring requirement oz assisting y
it?
How was the need for a Flouride limit determine
How was the need for a Toluene monitoring requirement
determined?
Demonstrating compliance with the limit on effluent
Mercury will be very difficult, if not impossible, due to
the .limitations of analytical procedures currently used for
405 North Jackson Street 9 Sallsbury, N,C. 28144

DEC!07 ' 9a 09 : 51 _
P . /3
this pollutant. No laboratorles' that we know of, including
the state lab. Is. capable, .*of analyzing `Mercury below
l
detection level of '0.200 micrograms per liter.
demonstrating that effluent concentrations do not exceed
this detection level be satisfactory?
The percentage_ 04 wastewater which is Industrial is
incorrect as shown in the Fact Sheet. The correct numbers
are 94.1% Domestic and 5.9% Industrial.
we are looking forward. to meeting with you on October
19th to discuss- this permit. Thank you. again. for your
assistance in this matter. Please call me if you have any
questions about these comments/concerns.
cc:" ohn Vast
Phil Dearman
Roy Miller
I-
Sincerely,
lee
o. Kelly Fatton', Manager
Water Resources .division
City of Salisbury

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