NC0038377_Comments on the Draft Permit_20170221 (3)

DUKE
V ENERGY.
February 21, 2017
Sergei Chernikov, PhD.
Division of Water Resources
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject: Comments on the DRAFT NPDES Permit for Mayo Steam Electric Plant
Permit No.: NC0038377
Person County
Dear Dr. Chernikov:
Richard E. BakerJr., P.E. , P.M.F
Director of Environmental Programs
Coal Combustion Products
526 & Church Streei
Mail Code:EC131C
Charlotte, NC 28202
(704)-382-7955
RECEIVEDINCDEQ M
FEB 21 2017
WaterQuality
Permitting Section
Duke Energy Progress, LLC (Duke Energy) submits the following comments on the draft National
Pollutant Discharge Elimination System Permit for Mayo Steam Electric Plant, issued for public comment
by the North Carolina Department of Environmental Quality ("NCDEQ") on January 22, 2017. Duke
Energy appreciates NCDEQ's efforts to develop the Draft Permit, which addresses novel issues
associated with surface impoundment modifications required to allow for continued operations while
complying with various Federal and State mandates. Finalizing this wastewater permit is a critical step
to advance that process by authorizing decanting and dewatering of the ash basin and permitting
replacement treatment options. In addition to these general comments, Duke Energy again offers the
following comments and requests for modification and/or clarification on specific provisions of the Draft
Permit:
1. On pages 13 through 19 of 37, Duke Energy notes that the channels between the ash basin dam
and the point represented at "AOW S-3" are identified as effluent channel as referenced in the
DEQ field office staff report. On page 19 of the permit, DEQ requires Duke Energy to install a
fish migration barrier at the point identified as "S-3" "to minimize fish migration into the effluent
channels that are combining of 5-3." Because of this and the designation of all of these flows as
effluent channels, the points flowing to S-3 consisting of releases from points identified in the
permit as outfall 101, 102, 101A, 102A, 102B, 108 and 110 should not be subject to WQBEL's
and should be removed and listed as contributing flows to the final compliance sampling point
at S-3 (which could be identified as outfall 103).
2. On page 6 of 37, Section A.(3), Duke Energy requests the following clarifications and
modifications:

Page 12
Duke Energy requests that the limits for Thallium be removed from the permit as there is no numeric
water quality criterion for Thallium in North Carolina. With no adopted criteria, the State has not
provided any opportunity for public involvement or comment on recommended constituent levels used
in determining permit requirements. Unlike the defined opportunity to comment on proposed criteria
during the triennial review, the only means for public involvement in this case is through commenting
on specific permitting actions. The Division's management has previously indicated no limits for metals
would be included in permits for constituents without numeric criteria and the Division recently
acknowledged this in issuance of the company's Sutton permit in which NC DWR proposed to include an
effluent limit for Aluminum but withdrew that limit in the final permit "because ...North Carolina does
not have fan) Al standard...".
The State of North Carolina just completed an update to its standards through the triennial review
process but did not propose any criteria for Thallium. Additionally, there is no record of a determination
that any limit on Thallium is necessary to protect narrative criteria. To the contrary, the record indicates
that the receiving water currently meets narrative criteria, despite a long history of similar discharges,
indicating that effluent limits are not necessary to protect narrative criteria or designated uses. During
the last permit cycle, Duke Energy has completely eliminated inputs of Fly ash, Bottom ash and FGD
wastewater to outfall 002. The Division has not provided any documentation that the factors required
for consideration in developing a BPJ limit for Thallium have been considered. Additionally, Duke
Energy requests that the limit for Thallium at outfall 002 be removed from the permit for the
following reasons:
a) The conclusion reached in the IRIS Toxicological Review (USEPA, 2009), which DEQ seeks
to base the limit on, was the available toxicity database for Thallium contains studies that
are generally of poor quality. Please see Attachment 1 - Evaluation of Toxicological
Information of Thallium prepared by Haley and Aldrich for DEC. This information is included
in the attachment to these comments and should be considered part of our comments on
the DRAFT permit. In the USEPA Integrated Risk Information System (IRIS) Chemical
Assessment Summary for Thallium, it was stated "The available toxicity database for
thallium contains studies that are generally of poor quality" (USEPA, 2012a). In addition,
there is not currently an oral chronic reference dose (RfD) toxicity value for Thallium
established by the USEPA IRIS or from an USEPA Provisional Peer -Reviewed Toxicity Value
(PPRTV) assessment, which would be used to establish water quality criteria. Due to the
significant uncertainty surrounding the study selection used to establish the values for the
2002 water quality criteria and uncertainty to the relevance of adverse effects of Thallium ,
the values used for the derivation of the 2002 Federal Water Quality Criteria for Thallium
are questionable and greatly overestimates potential risks associated with Thallium
exposure. This is supported by other regulatory and authoritative agencies concluding that
the dataset is currently insufficient for derivation of a non -cancer value for Thallium. In
addition, current intakes of Thallium for a substantial part of the population exceed the
provision screening value with no reported adverse effects reported, which also suggests
that the current value is unrealistic for purposes of regulatory decision making.
3. On page 1 of 37, Duke Energy requests the addition of Crutchfield Branch and Mayo Creek to
the designated receiving waters.
4. On page 2 of 37, Duke Energy requests the following:

Page 13
a. Removal of the language involving ash sluice water mixing with cooling tower blowdown
prior to discharge. Ash sluice water is not discharged at outfall 008.
b. Removal of FGD wastewater as a contributing flow to Outfall 002. Location "C" depicted
in our August 2016 application update was chosen for the construction of a new FGD
basin. In the August 2016 submittal, Duke Energy requested an overflow discharge
point to Mayo Creek be permitted for location "C. This is similar to the requests that
was made and included in the permit related to a new treatment basins emergency
overflow for the Roxboro Steam Electric Plant. Duke does not envision the release of
water from the future FGD basin, however we have requested permit coverage in case
such a discharge were to occur at some point in the future.
5. On page 3 of 37, Duke Energy requests the following changes be made to the final permit:
a. Outfalls 101A, 102A, 1028, 108, and 110 be removed and listed as contributing flows to
the final compliance sampling point at S-3 via the designated effluent channel. This
sampling point could be identified as outfall 103.
b. Outfall 006b be removed from the NPDES wastewater coverage as it does not constitute
a point source discharge or receive any cooling tower drift flows.
6. On page 4 of 37, Duke Energy requests the removal of the daily temperature monitoring
requirement for outfall 001. The current permit contains no requirement for temperature
monitoring. "Daily" temperature monitoring is not necessary and is overly burdensome. Duke
is amenable to "weekly" testing of temperature at this outfall. Cooling tower blowdown flows
are sent to the ash basin where heat dissipates prior to release to Mayo Reservoir.
7. On page 5 of 37, Duke Energy requests removal of the pH limit from internal outfall 008.
Internal outfalls do not constitute a "point source" discharges as described in 40 CFR
423.12(b)(1). Additional reference information related to pH for internal outfalls is provided in
Attachment 3.
a. Duke Energy requests that method 245.1 be allowed for Mercury analysis at outfall 002,
instead of method 1631E. Compliance with the permit limit imposed can be easily
demonstrated using method 245.1.
b. Duke requests that the sampling for Chlorides associated with the mixing zone be
removed. The chloride wastestream that led to the inclusion of this requirement in the
previous permit (FGD wastewater) has not been discharged in over two years because
of the processing of this flow through the vapor compression evaporator.

Page 14
c. Duke Energy requests that during normal operations and decanting that the Acute
Toxicity testing frequency remain at Quarterly as in the current permit. Duke Energy
has never failed a toxicity test at the Mayo plant and monthly testing during normal
operations is not supported.
8. On page 7 of 37, Duke Energy requests parameters with footnote #8 be removed from the limits
page. The footnote currently states that the limits are not enforced when there is no overflow
from the FGD basin. As discussed in our August 2016 NPDES permit application update, Duke
Energy was still evaluating the location of the FGD settling basin. Since that time the location
has been finalized and any overflow from the basin would not be directed to outfall 002.
Location "C" depicted in our August 2016 application update was chosen for the construction of
a new FGD basin. In the August 2016 submittal, Duke Energy requested an overflow discharge
point to Mayo Creek be permitted for location "C. Duke Energy requests that this location be
permitted as previously requested.
9. On page 8 of 37, Duke Energy requests clarification that the flow limit associated with
dewatering applies only to the water removed from interstitial pore space and not the entire
flow through outfall 002. The station will be operating during the time of ash basin closure and
operational flows will be discharged through outfall 002 at the same time dewatering is
underway. Again, Duke Energy requests the removal of Thallium limits as there is no numeric
water quality criterion for Thallium in North Carolina.
10. On page 10 of 37, Duke Energy requests that the limits for BOD and fecal coliform be removed
from outfall 002A. These constituents are proposed to be monitored at outfall 002 further
down in the treatment process. BOD and Fecal should only be monitored at one point and Duke
requests that it be at the final compliance point outfall 002.
11. On page 23 of 37, Duke Energy requests removal of outfall 006b. This point consists of a
stormwater drain that is approximately 750 feet from Mayo reservoir with no defined channel
leading to the reservoir. Upon further evaluation and site visit with NC DEQ DEMLR staff, Duke
Energy has determined that this point does not constitute a point source discharge. There is no
wastewater component to this particular point.
12. On page 26 of 37, Duke Energy requests that Toxicity testing remain a quarterly requirement
until dewatering commences. Duke Energy has never failed a toxicity test at the Mayo plant and
monthly testing during normal operations is not supported.
13. On page 27 of 37, Duke Energy requests the removal of the weekly testing for chlorides found in
Condition A. (23). There has been no discharge from the FGD wastewater system in over two
years and while Duke wants to maintain the flexibility to treat and discharge this flow in the

Page (5
future, there is no current plan to discharge FGD wastewater. Weekly testing for chlorides is not
necessary. Duke Energy requests that, at a minimum, this sampling change to quarterly or be
eliminated for as long as there remains no discharge from FGD wastewater.
14. On page 30 of 37 in Condition A.(30.), Duke Energy requests modification of the proposed
sampling location for instream monitoring from "1000 feet from Outfall 002" to the pre-existing
Mayo Reservoir sampling station identified as "131". Sampling location "131" is the closest
exisiting monitoring station to the discharge from outfall 002 and its location is shown in the
figure provided in Attachment 2 for reference.
15. On page 31 of 37, Duke Energy requests modification of condition A. (31) to align the wording
with the request found in comment # 1.
Duke Energy welcomes any further discussion on our comments or the Draft Permit. Duke Energy
requests the opportunity to discuss the specific comments and concerns outlined in this letter in person
prior to the subject permit being finalized. If you have any questions, please contact Shannon Langley at
919.546.2439 or at [e-mail].
Sincerely,
Richard E. Bakerk, P.E., P.M.P
Director of Environmental Programs - CCP
Duke Energy
Attachment
Cc: Mr. John Hennessey—Mayo Public Hearing officer
1617 Mail Service Center
Raleigh, NC 27699-1617

Attachment 1
17
WaterOW'r
Permitting se%n
Evaluation of Toxicological Information of
Thallium prepared by Haley and Aldrick for DEC

Thollium Toxicity Value Review
EVALUATION OF THE TOXICITY VALUE FOR THALLIUM
1. Current Screening Provisional Toxicity Value
There is not currently an oral chronic reference dose (RfD) toxicity value for thallium established by the
United States Environmental Protection Agency (USEPA) Integrated Risk Information System (IRIS) or
from an USEPA Provisional Peer -Reviewed Toxicity Value (PPRTV) assessment. The USEPA PPRTV
document for thallium (TI) concluded that it is inappropriate to derive a provisional subchronic or
chronic provisional RfD (p-RfD) for thallium; however, USEPA states that information is available which,
although insufficient to support derivation of a provisional toxicity value under current guidelines, may
be of limited use to risk assessors (USEPA, 2012). The PPRTV document contains a separate Appendix A
that provides rationale for the derivation of a subchronic and chronic "screening provisional oral
reference dose" for thallium compounds of 0.00004 mg TI/kg-day and 0.00001 mg TI/kg-day,
respectively. Appendix A of the PPRTV document also notes that, "Users of screening toxicity values in
an appendix to a PPRTV assessment should understand that there is considerably more uncertainty
associated with the derivation of a supplemental screening toxicity value than for a value presented in
the body of the assessment (USEPA, 2012a)." The screening p-RfD is expressed in units of milligrams of
thallium per kilogram of body weight per day (mg TI/kg-day).
Due to limitations in the toxicology database and general poor quality of available studies, the USEPA
IRIS Toxicological Review of Thallium and Compounds (USEPA, 2009) also concluded that reference
doses or reference concentrations could not be derived for human health following thallium exposures.
2. Information on Human Exposure to Thallium
The conservative nature of the p-RfD can be illustrated by considering the amount of thallium ingested
daily by Americans in their diet. It is estimated by the World Health Organization (WHO) and the U.S.
Agency for Toxic Substances for and Disease Registry (ATSDR) that a 70 kilogram adult ingests
approximately 0.005 mg thallium per day in the diet, especially from consumption of home-grown fruits
and green vegetables (WHO, 1996; ATSDR, 1992). This is equivalent to a daily dose of 0.00007 mg TI/kg-
day. The USEPA supplemental p-RfD for thallium is 1E-05 mg/kg -day (0.00001 mg/kg -day). This is seven
times lower than the estimated dietary intake. In other words, use of this dose -response value to
evaluate natural dietary exposure to thallium would indicate a hazard that is unlikely to exist.
Stated another way, assuming that an average adult weighs 70 kg, and using the screening level p-RfD of
0.00001 mg/kg bw-day, it could be concluded that an adult should not consume more than 0.0007 mg
TI/day, which is well below the estimated dietary intake of 0.005 mg thallium per day in the diet.
Currently, there have not been substantial reports of toxicological effects associated with typical dietary
ingestion of TI in the general population, suggesting that the use of the "screening provisional oral
reference dose" greatly overestimates the potential risks associated with oral exposure to TI
compounds.
The 90`' percentile adult urinary thallium elimination from the National Health and Nutrition
Examination Survey (NHANES) (CDC, 2016) is 0.380-0.390 micrograms per liter (ug/L) which is about
0.760-0.780 ug/day in the urine alone. This suggests that greater than 10% of Americans, and probably
November 2016 1 �M1�

Thallium Toxicity Value Review
closer to 50% of Americans, ingest more than the screening level p-RfD. From the IRIS assessment
conducted in 2009, a reviewer stated that there is no evidence that thallium in the current U.S. diet
poses any threat, and the adoption of this screening level p-RfD would produce unnecessary concern if
the above calculation is correct. This indicates the poor quality of the existing data, and brings into
question the validity of the analysis using the available data on thallium used by USEPA (USEPA, 2009).
3. Derivation of the Current Screening Provisional Toxicity Value
Below is a summary of the data and assessment that was used by USEPA in the derivation of the oral
chronic screening level p-RfD for thallium.
Note: Human or animal studies examining the carcinogenicity of thallium following oral exposure are
not available. The cancer weight -of -evidence (WOE) provided in the IRIS review (USEPA, 2009) is listed
as "Inadequate Information to Assess Carcinogenic Potential (both oral and inhalation)."
Human Studies
Most information on thallium toxicity in humans comes from poisonings, suicide attempts, or accidental
exposures. Symptoms observed after acute exposures to high doses of thallium in humans include
alopecia (hair loss), gastrointestinal disturbances, and neurological symptoms such as paresthesia and
neuropathy. Epidemiologic studies of either the general population or occupationally exposed groups
are limited by inadequate study design, undefined exposure parameters, and inconclusive associations
between thallium exposure and specific health effects. Therefore, USEPA (2012a) concluded in the
PPRTV document that "available human studies do not support oral RfD derivation."
Animal studies
Studies in animals show that oral exposure to thallium produces effects similar to those observed in
humans, most notably, alopecia. Other findings observed in animal studies include biochemical
changes, lipid peroxidation, liver and kidney damage, and histopathologic changes in the brain and
nerves. The doses at which these systemic effects were observed range from 0.2 —1.8 mg TI/kg-day
(ATSDR, 1992). Reproductive and developmental studies in animals show some evidence of adverse
effects upon oral exposure to thallium at doses of 0.08 mg TI/kg-day —1.6 mg TI/kg-day; however,
available studies have significant limitations and the same effects have not been observed in humans
(ATSDR, 1992).
Only four repeat -dose oral toxicity studies with more than one dose level are available in animals. Of
these four studies, three were not considered adequate for RfD derivation (USEPA, 2009).
3.1.3 Conclusion
The conclusion reached in the IRIS Toxicological Review (USEPA, 2009) was that the available toxicity
database for thallium contains studies that are generally of poor quality. One animal subchronic study
conducted by the Midwest Research Institute (MRI, 1988) was selected as a candidate principal study for
November 2016 2
AL,CH

Thollium Toxicity Value Review
RfD derivation but was found to include critical limitations such as high background incidence of
alopecia, lack of histopathological examination of skin tissue in low -and mid -dose groups, and
inadequate examination of objective measures of neurotoxicity, thus making it difficult to select
appropriate endpoints. On this basis, a RfD for thallium salts was not derived by IRIS (USEPA, 2012a).
? =95 FOR PRO ISIM t s ' ,'ONG O RAI CHRONIC. P—RI
As indicated above, the PPRTV assessment (USEPA, 2012a) does not derive a typical provisional toxicity
value for thallium but rather uses the limited toxicological information to develop a screening level
value.
8.2.1 Sel ctio
A 90 -day Good Laboratory Practice (GLP) oral gavage study in male and female rats conducted with
thallium sulfate by MRI (1988) was selected as the principal study for the screening level p-RfD. Doses
were approximately 0, 0.008, 0.04, and 0.2 mg TI/kg-day.
Several critical endpoints were considered, but ultimately USEPA (2009) considered only two endpoints
to be appropriate for a screening level p-RfD development:
Hair follicle atrophy in female rats that also had alopecia; and
Clinical observations related to animal coat, eyes, and behavior.
The clinical observation endpoint was discounted because the underlying basis for the observations is
unknown. Hair follicle atrophy was determined to be most consistent with the atrophic changes
observed in cases of human thallium poisoning and may be best indication for human response to
thallium exposure.
MRI (1998) concluded that the minor dose-related changes in the study did not affect the health status
of the treated animals and were not toxicologically significant. MRI considered the highest dose (0.2 mg
TI/kg-day) as the no -observed -effect level (NOEL). However, USEPA conducted its own analyses of the
raw data from the study to come up with different conclusions. Of the 12 high -dose females with
alopecia, 5 instances were not totally attributed to barbering behavior. Histopathologic examinations
revealed atrophy of the hair follicles in two high -dose female rats that also had alopecia. It was noted
that there were no discernable differences in either the severity or distribution pattern of alopecia
across control and treated groups (USEPA, 2009).
The high dose (0.2 mg TI/kg-day) was identified by USEPA as the LOAEL. Because histopathology of skin
tissue from the low -and mid -dose groups was not conducted, the NOAEL for this endpoint cannot be
determined with certainty. Given the low incidence of hair follicle atrophy in females in the high dose
group and absence of cases of hair follicle atrophy in male rats, USEPA (2012a) assumed that the mid -
dose could be used to approximate a NOAEL for skin histopathology.
November 2016 3 H��,CH

Thallium Toxicity Value Review
Therefore, the estimated NOAEL of 0.04 mg TI/kg-day was used as the point of departure (POD) for hair
follicle atrophy (USEPA, 2012a).
Using the NOAEL of 0.04 mg TI/kg-day for hair follicle atrophy and using an uncertainty factor (UF) of
3000, the screening level p-RfD was calculated to be 0.00001 mg TI/kg-day. Justification for the applied
OF is summarized in table below.
Table 1: Uncertainty Factors Applied by USEPA in Screening Level p-RfD Derivation
Uncertainty Factor
Justification
10
Extrapolation from laboratory animals to humans since no information is
available to characterize the toxicokinetic differences between experimental
animals and humans.
10
Variation in human susceptibility in the absence of information on the
—
-_variability of response to thallium in the human population.
10
Lack of adequate developmental toxicity studies and a two -generation
reproductive study, and additional uncertainty associated with the limited
data available on neurotoxicity._
3
Extrapolation from subchronic to chronic exposure duration. Effects on the
coat/skin as well as other clinical observations occur within weeks of exposure
to thallium (does not required chronic exposure in order to manifest).
Composite OF = 3000
— —
Note that there are considerable and critical limitations with the principal study selected by USEPA
(2009) including:
High background of incidence of alopecia (POD selected)
Lack of histopathological examination of skin tissue in low -and mid -dose groups
Inadequate examination of objective measures of neurotoxicity
4. Other Available Sources for Derivation of Toxicity Values for Thallium
The following sections describe sources consulted for information on the toxicology of thallium.
The World Health Organization (WHO) (1996) concluded that in the general population, environmental
exposure to thallium does not pose a health threat. The total intake has been estimated to be less than
5 ug/day with the vast majority coming from foodstuffs; drinking -water and air generally contribute very
small amounts of thallium. Concentrations of thallium in urine may be considered a relatively reliable
indicator of exposure. Exposure to thallium resulting in urine concentrations below 5 ug/liter is unlikely
to cause adverse human health effects. The estimated daily oral intake corresponding to a urinary
thallium concentration of 5 ug/liter in urine is approximately 10 ug thallium in the form of a soluble
compound. Assuming an average adult body weight of 80 kg (USEPA, 2014), this would be equivalent
to 0.000125 mg/kg -day which is a 10 -fold factor above the USEPA screening level p-RfD. The WHO
November 2016
4
,on W : 9
arki 9!-M

Thallium Toxicity value Review
Task Group thus concluded that "in view of the considerable uncertainties in the evaluation, it was not
possible to recommend a health -based exposure limit. Until better information on the dose -response
relationship becomes available, it seems prudent to keep human exposures at levels that lead to urinary
concentrations of less than 5 ug/liter." In reviewing the animal studies, the WHO Task Group also noted
that, "it appears that an intake of 0.01 mg/kg -day may be associated with adverse effects. No doses
lower than this have been tested."
ATSDR (1992) notes, "Data on effects of intermediate duration oral exposure in animals do not reliably
identify the most sensitive target organ or the threshold for adverse effects. No data on effects of
chronic -duration oral exposure to thallium were located. Therefore, intermediate -duration and chronic -
duration oral minimum risk levels (MRLs) were not derived for thallium." Note that review of the MRI
1988 study (originally Stoltz 1986) was conducted by ASTDR but not used in the derivation of the MRI.
USEPA's Maximum Contaminant Level (MCL) (USEPA, 2012b) for drinking water is 2.0 ug/L or 0.002
mg/L. The USEPA Human Health Water Quality Criteria (HHWQC) (USEPA, 2015) for thallium is 0.24 ug/L
or 0.00024 mg/L for the consumption of water and organisms from a surface water body, and is 0.47
ug/L or 0.00047 mg/L for the consumption of organisms only. These levels were derived based on the
90 -day subchronic study in rats (MRI, 1988).
4.4
In California, the MCL and Public Health Goal (PHG) for thallium in drinking water are currently set at 2.0
and 0.1 ug/L, respectively (CaIEPA,1999, 2004). The Office of Environmental Health Hazard Assessment
(OEHHA) prepared the PHG for thallium in drinking water also using the MRI (1988) study in which
alopecia was observed in both male and female rats and consistent with other reports of toxicity of
thallium in both experimental animals and in humans. OEHHA determined that the incidence of
alopecia in female rats at the highest dose of 0.25 mg/kg -day represented a biologically significant
effect. Therefore, the no -observed -effect -level (NOEL) was identified to be the administered mid -dose
level of 0.04 mg TI/kg-day. For the calculation of the PHG, a cumulative uncertainty factor of 3,000 was
incorporated to account for the use of a subchronic study, uncertainty in inter -and intra -species
extrapolation and the steep dose -response curve. Based on these uncertainty factors, OEHHA derived a
PHG for thallium in drinking water of 0.0001 mg/L (0.1 ug/L). OEHHA notes that USEPA chose to
consider the dose that resulted in alopecia and increased serum enzymes indicated of liver damage as a
NOAEL, which is why the federal values are higher than those estimated by OEHHA.
4.5
The Canadian Council of Ministers of the Environment (1999) also adopted the USEPA screening level p-
RfD based on the MRI (1988) study as a provisional tolerable daily intake (TDI) for derivation of health -
based soil quality guidelines for thallium at contaminated sites in Canada.
November 2016 5

Thallium Toxicity Value Review
4.6 EUROPEAN UNION
No data were available on thallium or thallium compounds on the European Chemical Agency (ECHA)
Portal where the Registration, Evaluation, Authorization and Restriction of Chemical Substances (REACH)
Registration Dossiers are posted (ECHA, 2016). Thus, no derived no effect level (DNEL) is available for
thallium from this source.
43
No other relevant data were located with respect to thallium toxicity since the publication of the USEPA
PPRTV assessment that could better inform the dose -response assessment and toxicity value derivation
for thallium.
S. Critique of Toxicity Value for Thallium
The current screening level p-RfD currently being used by USEPA as a toxicity value is a highly
conservative and inappropriate value for use in evaluating human health risks from oral chronic
exposure to thallium on the basis of: 1) the lack of appropriate toxicological studies on subchronic and
chronic exposures to thallium that provide relevant data and endpoints to be used in a dose -response
assessments; 2) the fact that other regulatory authorities (ATSDR, WHO) have concluded that sufficient
data on thallium does not exist and have not generated toxicity values for thallium and have placed a
low priority on development of additional toxicology data for thallium; 3) the study and POD using
alopecia as the endpoint as selected for the derivation of the screening level p-RfD by USEPA (2012a)
results in significant uncertainty to the applicability of the effects to human exposure to thallium; and 4)
the screening level p-RfD greatly overestimates the risk associated with human exposures as compared
to the typical ingestion of thallium in foods.
TOXICOLOGY DATABASE ON
The toxicity database for thallium in consideration of a dose -response assessment and derivation of a
toxicity value is limited. Low confidence in the screening level p-RfD is attributed to the limited
database including the lack of studies addressing the known toxic effects of thallium including
neurotoxicity, developmental toxicity, and endocrine effects, and failure of the MRI (1988) study to
identify a NOAEL of all relevant endpoints are considered. It is questionable as to whether a screening
level p-RfD should have been derived and if such an analysis is even valid knowing the database
limitations resulting in the application of such high uncertainty factors, given USEPA's own discussion of
the limitations in the PPRTV document (USEPA, 2012a).
Most regulatory sources acknowledge the paucity of data for thallium and have not derived toxicity
values. USEPA IRS, WHO, and ATSDR have not generated oral chronic RfDs for thallium. For those that
have, the MRI (1988) study has been identified as the principal study despite the fact that it has not
been published in a peer-reviewed journal, did not provide statistical analyses, and the study did not
show a statistically significant dose -response effect for alopecia in male rats.
November 2016 6 WARICH

Thallium Toxicity Value Review
On the Priority List of Hazardous Substances established by ATSDR last updated February 12, 2016,
thallium is listed as #275 out of 275 compounds indicating its low priority and concern for review
). In addition, the National Toxicology Program (NTP) (2016a) has
reviewed petitions and proposals for conducting additional toxicology studies on thallium to decrease
the limitations and uncertainty with the current toxicology database but in a recent meeting on June 15,
2016, the NTP scientific board placed low priority on moving forward with these efforts.
One could infer that the low priority established by regulatory authorities on continued development
and review of the toxicology data for thallium indicates a low concern of the potential for human health
risk effects of oral exposures to thallium as compared to other compounds.
It has been questioned as to whether alopecia is considered an adverse event and should have been
used as the POD for the screening level p-RfD. USEPA has stated: "Whether alopecia is itself an adverse
effect merits consideration. In humans, alopecia is generally reversible upon cessation of thallium
exposure. Alopecia, however, appears to be a part of a continuum of dermal changes observed
following thallium exposure, as well as one of a spectrum of effects on target organs that include the
nervous and gastrointestinal systems. For these reasons, alopecia supported by two cases of hair follicle
atrophy is considered an adverse effect (USEPA, 2009)." USEPA (2009) acknowledged that other factors
such as caging and husbandry can cause alopecia in laboratory rodents; however, the incidence was
clearly elevated in both male and female rats over controls. Further, to the extent that alopecia was due
to barbering, research has shown that barbering in rodents can reflect a stress -evoked behavioral
response. For these reasons, some IRIS reviewers thought it was reasonable to use the alopecia as a
"biomarker" for adverse effects until additional studies are conducted to better identify adverse effects
of thallium exposures in animals and/or humans.
NTP (2016b) has also noted that the dose selection for the subchronic study was deemed inappropriate
for evaluation of alopecia since the 14 -day range -finding study performed prior to the 90 -day study
indicated hair follicle alterations together with decreases in body weight at a dose of 2.5 mg/kg -day of
thallium sulfate; however, a dose of ten times lower than that which effects were noted, 0.25 mg/kg -day
thallium sulfate was chosen as the high dose in the subchronic study. Further, review of the results also
show that there were challenges in distinguishing between normal hair cycling, self -barbering, and
incidences of true alopecia.
Since hair follicle histopathology and self -barbering is not a standard assessment in subchronic studies, it
is difficult to know whether what was observed in the MRI study (1988) is within the range of normal or
truly adverse. Therefore, the use of this endpoint as the POD brings considerable uncertainty to the
screening level p-RfD derived using these data.
No other studies have been identified by reviewers that could bring more certainty and validity to the
current screening level p-RfD proposed by USEPA (2012a).
November 2016 7
ISICH

Thallium Toxicity Volue Review
6. Final Assessment
Due to the significant uncertainty surrounding the study selection and uncertainty to the relevance of
adverse effects in the selected study and POD, the screening level p-RfD value as provided in Appendix A
of the USEPA PPRTV document for thallium (USEPA, 2012a) greatly overestimates potential risks
associated with exposure to TI. This is supported by other regulatory and authoritative agencies
concluding that the dataset is currently insufficient for derivation of a non -cancer value for TI. In
addition, current intakes of Tl for a substantial part of the population exceed the provision screening
value with no reported adverse effects reported, which also suggests that the current value is unrealistic
for purposes of regulatory decision making.
Therefore, it seems most appropriate to establish a screening level based on the level of thallium in the
diet; clearly exposure to thallium at this level are without adverse effects. Using the information from
WHO (1996) that the estimated daily oral intake corresponding to a urinary thallium concentration of
5 ug/liter in urine is approximately 10 ug thallium in the form of a soluble compound, and assuming
an average adult body weight of g0 kg (USEPA, 2014), a RfD of 0.000125 mg/kg -day can be calculated,
which is a 10 -fold factor above the USEPA screening level p-RfD. This value is still a conservative
derivation, considering that it is well below the intake of 0.01 mg/kg -day that WHO indicated was the
lowest associated with adverse effects.
7. References
I. ATSDR. 2004. Toxicological Profile for Cobalt. U.S. Department of Health and Human Services,
Public Health Service, Agency for Toxic Substances and Disease Registry. Available at:
2. CDC. 2016. National Health and Nutrition Examination Survey. U.S. Center for Disease Control and
Prevention. Available at: htt d�vvW__C_d'.RQY`richs nhanes'
3. CaIEPA. 1999. Public Health Goal for Thallium in Drinking Water. Office of Environmental Health
Hazard Assessment (OEHHA). Available at:
4. CaIEPA. 2004. Update of Public Health Goal (PHG)-Thallium. Office of Environmental Health Hazard
Assessment (OEHHA). Available at:
5. Canadian Council of Ministers of the Environment. 1999. Canadian soil quality guidelines for the
protection of environmental and human health: Thallium (1999). In: Canadian environmental quality
guidelines, 1999, Canadian Council of Ministers of the Environment, Winnipeg. Available at:
6. ECHA. 2016. ECHA Portal for Registration, Evaluation and Authorisation of Chemicals (REACH)
Registered Substances. European Chemicals Agency (ECHA). Available from:
-substances,
November 2016 8

Thallium Toxicity Value Review
7. OEHHA. 1999. Public Health Goal for thallium in drinking water. Office of Environmental Health
Hazard Assessment, Berkeley and Sacramento, CA. Accessible at
8. NTP. 2016a. NTP Board of Scientific Counselors Meeting. Webinar presentation. Thallium
Compounds. June 15. See: :)wa. l ,u).n;ehs.,.i; c,��rt�, ftp t
f: ;__ t?Y�i 7si_Iii.t'�'Lit 91s5�1k$t,�S%C%eX.ittitil
9. NTP. 2016b. Draft NTP Board of Scientific Counselors Meeting. NTP Research Concept: Thallium
Compounds. June 15-16. Available at:
', -Esc,%iu1_E,dune_jnt >iL102/ .serials/t,Ta lium
CM!Tipo nd 5C, pcif
10. USEPA. 2009. Toxicological Review of Thallium and Compounds -In Support of Summary
Information on the Integrated Risk Information System (IRIS). September. Available at:
11. USEPA. 2012a. Final Provisional Peer Reviewed Toxicity Values for Thallium and Compounds.
Superfund Health Risk Technical Support Center, National Center for Environmental Assessment,
Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH.
Available at. ii*t -gra i. r.,, __ __ _.
12. USEPA. 2012b. USEPA 2012 Edition of the Drinking Water Standards and Health Advisories, Spring
2012. U.S. Environmental Protection Agency. Available at:
13. USEPA. 2014. Human Health Evaluation Manual, Supplemental Guidance: Update of Standard
Default Exposure Factors. OSWER 9200.1-120. February 6, 2011. U.S. Environmental Protection
Agency. Available at: 1tinvr;is.evvJF:rfp�_il'1�"�I0A.F)' LCQ^ z N
14. USEPA. 2015. Human Health Ambient Water Quality Criteria. U.S. Environmental Protection
Agency. Available at:i{G ,, .' �,f , ,,. r
_ ...�,_
15. WHO. 1996. Thallium. Environmental Health Criteria 182. World Health Organization. Available
at:
November 2016
HAL

Attachment 2
Mayo Reservoir Sampling Locations

Mayo Reservoir Sampling Locations
N
Mayo Creek
i
,
^!
r
,
r
r Ash
' Pond
r
—
!
r
i
'
1 B `
f
2 3
r ' " Plant
`
Site
!
`
2
3
r
r
,
r
Kilometers
r
1
2 ,
r
Miles
,
i
9R�512 '
E
'
Public
-1 — boat
`
r
ramp ,
'
r
us 501 '
i
r
IF
�
r
'
H -"- -
' Ii
f Mayo Steam Ylli
Electric Plant wn_!
NORTH CAROLINA ��!

Attachment 3
Reference document on internal pH limits
related to ELG's

ho
UNITED FTATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 204$0
OCT 18 am
Mr. Louis Canziarii
New York State
Department of Environmental
Conservation
Room 61'26
Two World Trade Center
New York, NY 14047
Deer Mr. Conzi ani
This is tp c0mfitm our recent conversation regarding
effluent limitations guidelines for the steam electric power
industry (40 GFR Part 423).
In my letter of June 22, 1984 to Ms. Ursula Basch of
your office, I summarized the applicability of the steam
electric regulation pH limitation as applicable to low volume
waste streams when such wastewaters are commingled with
(once -through) cooling waters. The interpretation that I
provided was not in accord with prior information and instruc-
tions provided to EPA and State permitting authoritties on
this subject.
The pH limitation per Part 423 applies at tho "end -of -
pipe" discharge to surface waters when the wastewater discharge
contains low volume wastewater that is commingled'with once -
through coaling water. However, the intent of Part 423 is
also that the total suspended solids end oil and grease
limitationsaPplicable..t.o low valUme waste streams be applied
'
to the lowvotvme Waste component of such a combined discharge
prior to commingling of the individual waste streams.
1 apologize for any confusion in permit development or
delays fn permit issuance that any have occurred in this
matter. If you have any further questions, please contact me
at [phone].
Sincerely,
Dennis Ruddy'
Project Dfficer
Industrial Technology Division

Ms. Ursula Basch
Nein York stats'
Llepartrnent of Environmental
Conservation
Room 6126
2 World Trade- Crntor
New York, New York 10047
Dear Ms. Basch:
This is in response to- your astestionrt �?uring our
discussion on June 2.1 regarding the eff)uent limitations
guidelines for the steam electric industry (40 CFR Part 423).
Tee PH limitation applicable to low volume waste streams
is int ded t_o requir-e "that low volume waste streams be
treated, as necessary, to comply with the pH limitation prior
to discharge. Furthermore, the basis for compliance with the
PH limitation is not buffering or dilution provided by cooling
Waters or other waste streams which are commingled with low
volume wastes.
I trust that this information is responsive to your
questions. Please call me if You have any further questions.
(202--382-7165)
sincerely,
Dennis Ruddy
Project Officer
Effluent Guidelines Di.•i-4.0n
x

I
r,
op
'
'%c70011
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION III
OTT ANO WALNUT STREETS
PHILADELPHIA. PENUSYLVANIA 19106
In reply rafor to
3EN21
March 14, 1976 ''F"�'�a LONG
Mr. .lames Long
Power Plant Services Section
Philadelphia. Electric Company
2301 Karket Street ~
Philadolphia, Pennsylvania ?9101
Dear Mr. Long:
This is in response to your sacond progreso report subaitt*d February 10,
1976 for tha ChorItasr Generating Station (PA 001.1614), in which 'you propoaa to d:
charge boiler blowdown, zeolit4 softener regenerates, and evaporator b1artdown u
the receiving stream without pH neutralization. Please be advi3*d that
40CrR Part 423.32(b)(1) requires the pH of all dischArges from power plants
(except once -through cooling water) to be in, the. range of 6 - 9. Econonie8
were considered prior to tha development of the fizl guideline limitations,
therefore the expense you have cited as being associated with neutralizing chest
effluent strut, is not a valid argument against. treatment.
A policy decision was made during the -EPA -PEA meeting in Washington, D.C.
that may influence your situation with respect to neutralizing these effluent
streams. It waz decided that waste- streams could be combined with cooling water
for the so a a - a as on as e n was
the nH ran a of 6 - 9. Thin o c esti inconsi with uf,deliae re re-
Ment,. Itt s„�ou a not ever, that pollutant parameters other, than pH wil:
Ve unitedand moa`ritor r-'i"o"r to TEC c=--bCnnat3oa-6f 8 part eu ar waste source
category with c cling liter.
I trust thin will enabla you to complete your treatment plans. If there
are any questions, plerse doutt hesitate to contact me at 215 597-3689.
Sincerely yours r
Bruce P.Smith
Delmarva -D.C. Section

Consolidated Edison Company of New York, Inc.
4 frying Place, Mew York, N.Y. 10003
September 21, 1984
Mr. Dennis Ruddy (WH -552)
Project Offices
Effluent Guidelines Division
U.S. Environmental Protection Agency
401 M Street S.W..
Washington D.C. 20460
Re: pH Limits on Power Plant
Internal Waste Streams
Dear Mr, Ruddy:
Enclosed"..for' y -our -:information`: is -a ':copy- of. Con..' Edison'•s
comments to-NYSDEC concerning proposed pH -limits' and monitoring
requirements specified in the draft renewal permit for Con
Edison's Waterside Station. These comments expand upon Con
Edison's position concerning pH limits on internal waste streams,
as expressed during our August 10 meeting and detailed in previ-
ous correspondence. (In particular, see p.5, paragraph 2,
section 3(a)(5), section 3(b) and section 3(c) for new/expanded
arguments).
If you have any questions, please contact me at (212)
460-2522. We look forward to further discussions with you
concerning this issue.
Very truly yours,
Harry H. Cohen
Senior Environmental Engineer
Water & Waste Management
/9P
Attachment
cc: Mr. J. William Jordan (EN --336)
Chief
NPDES Technical Support Branch
U.S. Environmental Protection Agency
401 M Street S.W.
Washington D.C. 20460
1

IR Requirements (See
S
Eff uert ;imitations and Monitoring
DEC proposes r -r ma.ir_tair the current r,1' limiteticr, (range of
6.09.0) for Discharge 002 and MPte the current 6.0-9.0 pF
limitation for Discharge 001. DEC also proposes to add pH
limitations (6.0-9.0) for internal wage streams OOla
(boiler blowcown) , COIb (Waterside No. 1 defiineraliter
regenexaticn wastes) , 001c (floor and equipment Iraina.ge)
and 002a (Waterside Fo.2 demireralizex regeneration wastes).
Ir addition, DEC has proposed to delete Q monitoring
requirements at QscheTge 001, revise the pF monitoring
frequency for Discharge 002 from twice weekly to weekly and
add pH monitoring requirements Ar waste streams 001a
(week17 grab), 001b and 002a (arab before each batc?,
2ischarge) and 001c (twice month],). PEC pr -poses that all
new/revised effluent limitations and monitoring requirements
take effect imrediately upon, the effective date of the
renewal permit.
3

Cor. Edison's position with regard to DEC's proposed pH
requiremerts is suuna.rized below:
o Efflzert 1:mitaticr.s and/or ronitorirg requirements for pF
ir. internal waste streams 001a, 001b, 001c, 002a or ary
other internal waste stream cannot legally be imposed in
the final permit.
o There is no ervirormental justificati-an for a PH limit on
internal waste streams. Effluent limits on internal waste
streams are redundant and unnecessary since the current pu
14MIt of 6.0-9.0 at the point of discharge to the public
receiving water provides ac.equate protection of water
cuaiity. Furthermore, a PP limit of 6.0.9.0 has been
deemed acceptable bit DEC at the point of discharge.
o The costs to achieve a pH limit of 6.0-9.0 or. internal
caste streams would be wholly disproportionate to any
limited effluent reducticr. and environmental ber:ef'its to
be derived.
o Even if it were eventually determired that pH 14mits mF„
legally be imposed for waste streems.-001a, 001b, 001c and
002a (which for the reasons set' forth in thes-a- cements
cannot IaWfull+, be the case) , in order to achieve
ccrsisterc- wi.tl the limit of 6.0-9.0 at Discharge 001,
such llmitat'.ors must be less stringent than a rarge of
6.0-9.0 (applied at the point of d-scharge), in order to
take fully ir_to account p adjust'Tert within the
discharge turnels, and
c A compliance schedule to meet pts, limits on internal waste
streams reed not be prcv-dedif such limi is are r_ct
ultiaatel:- imposed, Even if it were evertualiv
determi..ed that pF 1`_mits cr. irr=__nal 'Vante st_rea.ms mal•
legal!- be irpesed, a reascr.•able compliance schedule must
be provided to install equ;Fment necessary to achieve
suc" 1* itations before they beco a effective.
The support_ for this pcsiticn is as follows:
(a) E -f --F'. u en t Limitaticr.s and/or .cr.itorin PRpcuiremertts for pf?
ir_ Ir:terra 'r'£.ste Strest+s L.;���'
�'i _C, i8 Or Any
Lther Integra:!l!sle Stream Canr_ct LeZ 11-� be Isoosec
(1) The Clear. "ater Act_ ?._mics the authority under Section
402 to cor.t.rolli^.g the a.dditior ofpollutants to
na,,igable waters through pe'_nt source discharges
(Sections 301 and 402 a,r.d definitions specified in
Secticr 5021,Paragraphs (1),(7),(11),(12) ard`(16)).
Based cr, ti-ose sections, efflue^t 1_m;..tsticr.s car.
be applied applied at the poirt the effluent enters the
receiving waters, except by the crr.ser_t of the
permittee. Therefore, the point of discharge into
G
s

navigable -waters fcr Discharges 001 and 002 (ard 003)
at the Station is at the confluence of the end of the
discharge tunnels and the East River.
(2) EPA's NPDES (Deccrsolid'ated) Fegulatiar_s (40 CFR 122)
essentially track the authority specified under Section.
402 and require effluent limita-r-icns to be set at the
poir_t of discharge to navigable waters. Section
122.45(a) states that all permit effluent limitations
shall be established for "each outfall or discharge
po.nt of the permitted facil'it,," except as otherwise
provided in Section 112-2.45(1). Section_ 122.45(i)(1)
states that Limits on internal waste streems ma; be
imposed in e_:cepticr.al cases and only if limitations at
the c-:tfall are impractical. or z.nfeasible. Secti.or.
122.45(i)(2) states that l -tits on ir.terna7 waste
streams tray be imposed only when the Fact Sheet under
Section 4C• CFP_ 124.56 sets `orth the e:.cepticr.al
circumstarces which make such limitations necessar,T,
such as when the final discharge point is inaccessible,
the wastes are so diluted as to make monitoxir.g
impracticable or the interference of pollutants at the
Point of discharge culd make detection or aral,*sis
impracticable. Both Sections 122.45-, and 124.56 are
applicable to State prog.ers.
Based on these regulations, there car, be no exceptional
circumstance Justification for impesitiorn, cf pH limits
ar_d/or monitoring requirements on internal waste
streams unless the final. discharge point is
inaccessible for sampling,. Yonitoring (detection are.
analysis) for pF. (unlike pol utants measured ir te.=.s
of rcass or concer.tration, such as heavy metals) is ;xt
impractical at the point of cischarge due to dilutien
or interference. Based cn the dist ncticr. bet7ween the
ratuxe'and monitoring of pP and other pollutants, Con
Edison has accepted irternal limits or_ other pel'_utants
ir. some crises (even though ve bPl'_eve that such lir.its
ca;:not 1P..ze.11be _filocsed based cr. the Clean Water Act
ar_d State E -n irormer.tel Cons er-yz ti on. Law) s`_rce in
these cases we recognize the it,practicalit,7 cf
deterr.4r.irg compliance with effluent limitations _`cr
such pcl3.utants at the xi'_al discharge (see Section 2.
of these co i marts) . Such iinpracti cal its , however, doe's
not app'- to pF .
1:1—tb regard to rhe cuest:_er of samplirg points, pu
sat:ples for Disct-.arges 001 are OC^ are curre::t!7 taker
ir_ the discharge plume oft the deck rather than
cirectly ir_ the discharge tunnels, since g"ht,s-cal
access to the Cur.rels is cLrrontlr unavailable i.e. the
disc'iarge turnei s terminate under the FDR Drive, about
60 feet from the end of the dock. However, Cern Edison
will create sampling access points ir_ the Discharge 001

and 002 -discharge tunnels by jure 1, 1985, or by the
beginnirrg of the 1985 chlorination seasar, at Waterside,
whichever is later, a.s part of our ch'_erine coirpliance
program (see ccu.ents ecr.cerr..ing proposed chlorine
reauiremer.ts, Section_ 4(c)). Therefore, there is no
,ustificati.cr_ for internal waste stream pF limits based
or. Section. 122.45.
(3) Title 8, Article 17 of the New York State Envirormertal
Corservaticr. Law (ECL) requires permits for the
discharge of pollutants from ary cutlet or point source
to the wat_prs of the state (vection 17-0803). The ECL
clear?; limits DEC's authori.t- to controlling
pollutants at the point such e�f?uents enter the
receivirg weters (Sections 17-0803, 17-0609 and the
definitions specified ir. 17-0105, Paragraphs
(2),(11),(15) and (16)). This limitation is rei forced
by the SPDES regulations implementing the. ECL (6 P?YCRP
Parts 750-757), Although we believe that the ECL
limits DEC's authority to impose effluent limits at the
final discharge, Ccn Edison has accepted and will
contirue to accept internal waste stream limits for
pollutants other than pH where we believe caricl_4r.ce
monitoring at the final discharge point is impractical,
the limitaticns are reasonable and rot more stringe:^t
than required by appropriate regulations. This is
clearl; not the case nor pH.
(4) EPA Best Practicable Technology (EPT) regulations limit
the pF of all discharges frog. steam electric power
plants, e::cept once through cooling u;ater, to a range
of 6.0-9.0 (40 CFR 423.12(b)(1)i emphasis ndded').
EPP.'s currer•t Effluent Limitation ruidelir_es fcr pH (47
FR 52303, P'ovember 19, 1982) are=dentical to tizose
contained in the ir.it; e7 le Dromulgatpet Guuellnes
published ir. the Federal register cn October 0, 1974
(39 FP. 36186) . ir, beth the ori€i.r_al and revisee
Guidelines, no py limitaticns are explicitly placed cr.
an! internal west a streams. Eased on the cFFinitions
specified in the Clear. Water Act, the E A limitation of
6.0-9.0 would apply or..1-- at the outlets c the
discharge runnels to the East Diver and not to an-'
L:terral waste stream.
1'.v lettPY fisted May 3, 1044 (at_t.achrrent to E.xhi?lit 1),
Ccr, 'Edison icrmall" reauesta_d that the V. S.
'Ervircr:mental Protection. Atgency (EPA) clarify its RPT
ar_� internal waste streams reaulatlCnS 2C they apply to
pH. At a meeting held on August 10, 1984 between'Con
Edison and EPA., the Aeenc•r states that it would tal_w_
Z. -bout one �or,th to re -a; ew the rulerxkirg zecore and
infcru Con Edison and DEC of its determination.
"' '-'-- - choar r=orpd December 13, 1982, DEC states

that internal waste stream monitoring is proposed for
specific low volume wastewaters since compliar_cp with
applicairle limitations cannot be determined at the
final c14-scharge. For the fellowing reasons, this
explaratior. rices not satisfy Federal (40 CFR 124.56)
and State (6 N11CR9 753.3) regulations, which require
that Fact Sheets set forth trQ _legal and technical
basis of proposed limitations:
(a) The Fact Sheet does not specifically address the
rationale for the proposed PH lima is . Ir. fact, it
cannot be determined from the Fact Sheet to which
waste streams and pollutants the ezp oration
pro-vided in the Fact Sheet applies;
(b) The Fact Sheet Coes not specify whether the
proposed pH limits are based cn EPA's Guidelines
for Steam Electric Power Plants or DEC's Best
Professional Judgement (BPJ) determination of Best
Practicable Technolog., (BPT) or Best Converntional
Technology (BCT), or any other basis;
1. if the proposed limit is based on EPA's
Guidelines, it does rot specify whether DEC
interprets the 6.0-9.0 BPT pF. limit to apply to
internal waste streams (ard iF so, the reasons
for that intepretacior.) or to final discharges;
2. If the nrovosed limit is based or. BPS, it does
not address the factors specified in Section. 304
oJ-
P the Clean. Water Act or 40 CP. 125.: (See
aragraph 3.(d) of these comments);
(c) The Fact Sheet does not specify which sections of
the Clear. Water Act and State Environmental
Conservation Law. provide DEC with the authority to
impose ir.terr_al waste stream limits for pP. Y?Cr
does it specif-y the sections of EPA end DEC
regulatiors which authc:rize such '._n its ; and
(d) The Fact Sheet Ices not speci£,T which of the
e:.ceptienal eircumstar.ceG specified in 40 CFP,
122.45(1), if an-, it relied cr. to ree.ch the stated
ccrclusior. that compliance with the 6.0-9.0 pH
3_°citation cannot be de?:ere:in ec by monitoring at
the final discharge.
(b) There is Vo Envircrmer.tal ?usti`icatien for p -' _14— i.ts on
Internal Later Streams
The current pH limitation of 6.0-9.0 at P scharges 001 and
002 affords adequate prctectior_ of public receiv^rz water
cual it-. A FH limit of 6.0-9.0 at the vcint of discharge
W17 c.eezed acceptable by F:'F Region 11 (and DEC by its

Section 401 Certification) in the initial discharge permit
issued by F,egion'II on November 30, 1974, as well as by DEC
(and Region II in its o-rerview capacity) in the rerewal
Permit issued b- DEC on ?'u?,, 1, 1980, Beth the initial and
renewal permits were based on EPA's Ef-fluent Guidelines
promulgated cn October 8, 1974 and were to have included ary
more stringent water cua?ity-based'— requirements. Since
applicable Effluent Guidelines fqr pH have not charged sir_ce
initial permit issuance and DEC has not shown that a final
discharge PP within the range of 6.0-9.0 has caused or wi"'_
cause any, adverse environmental impacts, there is no basis
for imposition of more stringent PH limitations in the
renewal permit. In addition, by proposing to maintain the
current 6.0-9.0 p?. limitation for Discharge 002, DEC has
deemed that range acceptable at the point of discharge.
Furthermore, irstallaticr. of a waste neutralination sys em,
which would be required to meet the proposed limits, would
result in the addition of significart amounts Cf
neutralizing chemicals (acid/caustic), thereby increasing
the amount of pollutants discharged. J
(c) The Cost To Achieve Interna? taste Stream PY Limits Is
Ulb-e- r Dis ro crtiorate To The Er, luert P_eduction Bene its
To Be Derive
The Waterside Staticr_ 'has two demineraliza.tior_ systems,
which are housed in separate buildings. In oreer to achieve
the proposed pH limits fcr demineralizer regeneration waste
streams (001b and 002a),. installation of tfao waste
neutralization systems would be required due to the physical
layout of the facility and the relatively large number of
regenerations performed (See SPDES Application Update for
more detailed information ccr_cerrirg reger_eratior. waste
streams). Each s -,stem would consist_ o-' 1-2 large
reutrc.l'_,:.atior tanks, pumps, acid and caustic in;ect4on
s^stems, Inst=utr.entati0-n and controls and an elaborate
Piping system. Con Edison. ccnservar�vel-z 'estimates the
total capital cost of these s- stems to be' $3-1 millicr., a
reasonable estir+ate taking into account the nature of the
facility (Primarily steer. sendout), age of the facility, its
physical layout and space limitations, and Lhe re'_ativeJ
large rumber of regenerations (due to steam sendout). ?'hese
costs would increase substantially if a pig limit o:. 6.0-9.0
is imposed fcr boiler blcwdo-,.-r. (001a; and 0022 it current
Permit) , H:hicr ty-pically has a PH of 10-10.5. Ir. .=dditicr,
substartizl operating costs (labor and chemicals) would, be
incurred. Tbese capital and operating costs- would
ultiwla~ely be borne. by Con E'dison's steam and electric
ratepayers.
As stated abo-tre, Con Edson believes that there is no
environmental justification for a pN limit of 6.0-9.0 or.
internal waste streams. Such limits wculd result in little,
w£ ar.v, environmental benefits, which are wholly

disproportionate to the costs that would be borne by Con
Edison and' its ratepa•Ters . As specified above, such
requirements *r,ould, in fact, result in the discharge of
increased amount of pollutants.
(d) If It Were Eventuall- To Be Determined That pR L_nits :fav
Le ally Be Imposed For In -Waste Streams, Such
Limitations Must :-,e Less Stringent t gar. -9.0
The existing pV limits of 6.0-9.0 for Discharges 001 and 002
reflect Best Practicable Control Technology Currently
P_7�railable (EPT) as defir_ed by EPA (40 CFR 423.12(b)(1)). by
limiting the pH of internal waste streams to that same
range, DEC is, in effect, proposing a limit more stn .rger..t
than BPT. Section 301(b)(2)(E) of the Clean Water Act
provides for gore stringent limits than BPT for pH and other
conventional pollutants by application_ of the Lest
Conventional Pollutant Control Technclog_,, (ECT). EPA has
deferred promulgation of ECT limitations for power plants
pending promulgation of a revised BCT methodology.
Therefore, any BCT limits imposed in a power plant permit
must be developed on a case-by-case basis, pursuant to
Sectcr. 402(a)(1) of the Clean Trlat_er Act and Article 17,
Title 8 of the State Envirormental Conservation_ Lakw.
The proposed internal waste stream limitatior of 6.0-9.0
must accordingly be based on a case-bv-case determination c:
FCT by DEC. EPA regulations (40 CFR 125.3(c)) allow the
itpositior. of techr_ology based limitations to the e:ctent
EPA -promulgated effluent guidelines are inapplicable. Ir
these cases, the permit issuing authority (DEC) is required
tc apply the appropriate factors specified ir. Sectio.•. 304(b)
of the , Clear. Water Act. Fcr dei:e?c-omer.t os ECT
limitations, the factors specif_ed in Section 304(b)(4)(11)
must be applied. These factors include "the reasonabler_ees
of the relationship between the costs of attaining a
reduction in effluent and the effluent reductier. benefits
derived, a.rd the comparison of the cost and level of
reductior, of such pollutant from publicly ou-nec treatment
works to the cost and le -el of reduction of such pollutants
`-rcm a class of category of indust_:.al source" are "the age
of equipment and facilities involved., the process employed,
the engineering aspects of the application of -various t^pes
of control techniques, process changes, non -water quality
environmental impacts (including energ-r requirements).,
Case-by-case limits oust also cor_sider, the apgrcpriate
techrclog,r for tI:e applicant's industrial categor;- and any
uriaue factors relating tc the facilir- (40 CFR
125.3(c)(2)). These factors must be considered regardless
of the permit issuing authorit- (40 CFR 125.3 (c)).
On ►'ove=ber 13, 1982, EPA proposed to revise 40 CFE 124.56
and 40 CFP, 125.3 to evpliclt'_s* specify- the statutory and
-+-tor �arrnrs that rrust be considered in setting

case-by-case, Pest Professional Judgement (BPJ) limits and
the information that must be included in the Fact Sheet (47
FR 52072) .-. The preamble to the proposed regulations states
that "Section 125.3(c)(2) already requires permit writers 60
consider -"statutory factors" in issuing EPJ permits, E'O
these changes simply clarify 2n e,cistir_g requirement." (47
FR 52080). The proposed regulaticnsr therefore, would make
explicit what is already reouired, namely the application of
the statutory factors and any other factors considered in.
the determination of BPJ limits and the inclusion-_ ir_ the
Fact Sheet of any analysis or the appl=cation cf these
factors and identification of any guidance cr other
documents relied upon in setting the limits.
DEC has not provided Con Edison with ar.y documentation of
its consideration of the factors specified in Secticn
304(b)(4)(B) and 40 CFR 125.3(c)(2) In its development of
the proposed BCT limits for PH. Therefore, DEC czr.r_ot at
this time impose BCT limitatiors more stringent than EFT.
Even if it should ultimately be determined that DEC may
impose pF. limits on internal waste streams, which for the
reasons set forth hereiii. we submit it carrot lawfully eo,
then such 14mitatiop-s must be less stringgent than 6.0-d.0 sc
as not to be in conflict with a 6.0-9.0 limitation at the
point of discharge. Otherwise, the internal limitations
would be more stringent that PPT and must be iustifiee,
taking into account the factors specified above. V
(e) Even If it Were Eventuall• To Be -DetermirPd That pli Limits
?.eeall" 3e �u Osed FCr 'r.terni:
G_ 4u `e Stre's—T P
P.easonable Compliance Schedule Must be Provided
if it were to eventually be detezr:i.red that PH limits may
i?gally be ;mposed or_' internal waste streams and such
limitations were imposed, a reasonable schedule of
compliance would need to be provided in order to permit
procuremer.•t and installation cf r._ecessar equipment before
such limits become effective.
DEC's proposed compliance deadline (efrectIve date of the
rereval permit) is both arbitrary and impossible to achieve.
Although DEC has nct provided its rationale fcr the proposed
compliance deadline, we presume that ;_t was based er_ the BCT
deadl=re cf Jul,7 1, 19004 specifies'. in Sect-cr.301(b)(.21(r) (
cf the C1w��r. ITater Act. Fcwe�:er, s'r.
_ce DEC's prcposed
limits carr_cr legally be imposed urd;er PCT as discussed
Yre-siously, the July 1, 1984 deadline eces nct apply.
rl the proposed urreascreble and izrpracticable ccmpliance
deadlire were to be eventually imposed, Cor_ Edison would
unfairly be put in the untenable Pas= tion of immediately
s►ialatirg the permit. For purposes of frar.ing the issues
=or, ccrsi deration in a hearing, any permit issued b -r EHEC

containing pH limits on internal waste streams should
contain a realistic compliance schedule, to be subsequently
agreed uperr, which would encompass time periods recessary
for the procurement and installation of necessary equipment.
(f) Mor.itorinc Peouiremerts
Monitoring requirements for pH carrot legally be imposed for
ir_terral waste steams for the reasons stated herein. If it
were ever..tuall- to be determined that pE monitoring
requirements may legally be imposed on internal wastes
streaks, moni-cring reauirements for these waste streams
should not be required pr:.cr to a realistic compl.:ar.ce
eeadl ine el entuall- agreed uper ( see paragraph ( e) abo,re) ,
since the limitations would not be effective until that
time. We cannot currently comely with the proposed
requirement of taking gra.b sar.ples before each batch
discharge of demineralizer regeneration wastes (001b and
002x), since there is no prevision for holding up these
wastes prior to discharge. Even if neutralization systems
are installed, this proposed requirement may be
impracticable, if the systems are designed for
semi -continuous operation_ in which, when rine e" -fluent is
within the set pH range, discharge may occur m9n7 times over
a regeneraticr cycle.
In summary, effluent limitaticr_s and monitoring requirements
nor ph should not be imposed for internal waste streams for the
rea.sons specified above. The only pH limits that may be imposed
are the current EPT permit limitations of 5.0-9.0 ai Discharges
001 and 002 (and 003) . This approach would be co-,sisterwith
that recoamended br DEC in its Divisior_ of Water Guidance
memorzrdum No. ON -W-33. ("EPd Yethodologies - Guidance for the
Anplicatior. of Fest Professional Judgement (3P.i) in Determirirg
S'DES Ccr.c'itiors," dated April 1983), which states (Section
VIII.E.):
"T-.ith rA-ard to conventional pollutants, the Department
will generally cors ider RPT ars acceptable level of
control, unless eFfluent guidelines or water quality
r_ecesc:tate more stringent control."
Since effluent gL 2elines mandate a pF limit of 6.0-9.0 at the
point cf discharge and water cuclitt7 has riot been showr. to
*necessitate ar_•' mcre stringent limits, the current limits are
apprcpr;ate and shculd by mair.tained. DEC mai- not impose a
Particular techroingy =cr meeting SPIES limitF. Therefe;�e, Ccr
Edison should be free to meet thcse limitations by the method of
ou~ choice.
Ever. if DEC could legally impose pH limitzt ors for internal
„aste streams at this facility, c compliance schedule wculd be
required to achieve such limitatior_s. In addition,
notwithstardir.e the legal arigurments against imposition of pH

requirements for interrr-1 waste streams, DEC must provide the
legal and technical basis, including any supporting
dccumer-taticn, -_for any such reeuiremerts prier to their
establishment it a final perr„i t. Ir -such rationale is e,7entua'_?..
prcvided, Cor. Edson must to given a rea.sorable oprc_tunit;7 for
e%,aluaticn and sub=issien of ce=ments.
1ti
.i.
It
L�