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United States
Environmental Protection
Agency
EPA 831-R92001
October 1992
Office of Wastewater Enforcement and Compliance EN-338
Review of Water Quality
Standards, Permit Limitations,
and Variances for Thermal
Discharges at Power Plants
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ACKNOWLEDGEMENTS
Several U.S. Environmental Protection Agency (EPA) personnel were critical to the
collection and analysis of information on the operation of power plants and the effect of thermal
effluent on the environment: Ted Landry, Region I; Charles Kaplan, Region IV; and Peter Howe,
Region V.
In addition, EPA Headquarters would like to thank the staff at several facilities who
provided insight into their specific plants' operations and results of environmental studies. We
would especially like to thank Bob Domermuth and the staff at Brunner Island for hosting two site
visits.
The EPA Project Coordinator for this study was Mary Reiley, (202) 260-9456.
NOTICE
This document has been reviewed by the concerned offices and programs within the
Office of Water: Statements of policy and opinion were prepared and incorporated by the Office.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY ES-1
1.0 INTRODUCTION TO THE REPORT 1
2.0 STUDY METHODOLOGY 3
2.1 Compendium of State Water Quality Standards 3
2.2 Matrix of NPDES Permit Limits and State Water Quality Standards 3
2.3 Facilities Reviewed In Depth 4
2.4 Data Reviews and Site Visits 5
3.0 STUDY FINDINGS 6
3.1 Establishing Thermal Permit and Variance Limitations 6
3.2 Impact of Thermal Effluent 7
3.2.1 Impact of Cold Shock 8
3.2.2 Impact of Excessive Temperatures 9
3.2.3 Changes in Population of Certain Fish Species 10
3.2.4 Entrainment and Impingement 10
3.3 Shutdown and Load Reduction Procedures and Control Mechanisms at
Facilities 11
3.3.1 Shutdown Procedures to Prevent Cold Shock 11
3.3.2 Control Mechanisms to Prevent Damage from Thermal Discharge . . 12
3.3.3 Control Mechanisms that Keep Fish Out of the Discharge
Channel 13
3.4 Environmental Studies Performed to Support Section 316(a) Variances ... 14
3.4.1 Initial Section 316(a) Variance Studies 14
3.4.2 Studies to Support Reissuance of Section 316(a) Variance 15
3.4.3 Environmental Monitoring 15
3.5 EPA Procedures for Issuing and Reissuing Permits 16
3.5.1 Advisory Committees 16
3.5.2 Lack of Institutional Knowledge 16
4.0 CONCLUSIONS AND RECOMMENDATIONS 18
BIBLIOGRAPHY 20
ATTACHMENTS
Compendium of State Water Quality Limits for Thermal Discharges and Mixing
Zones.
Matrix of NPDES Permit Limits and State Water Quality Standards for Thermal
Discharges from Major Power Plants.
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REVIEW OF WATER QUALITY STANDARDS, PERMIT LIMITATIONS, AND VARIANCES
FOR THERMAL DISCHARGES AT POWER PLANTS
EXECUTIVE SUMMARY
This report provides an overview of issues relating to thermal effluent discharges,
limitations, and variances. The report also highlights the environmental impacts of thermal
effluents, methods to mitigate the impacts, and recommended EPA actions to address thermal
issues.
Thermal discharges are defined as pollutants by the Clean Water Act (CWA) and are
subject to effluent limitations. If the discharger can show that effluent limitations derived from
applicable State water quality standards (WQS) are more stringent than necessary to ensure
protection and propagation of a balanced, indigenous population of shellfish, fish, and wildlife in
and on the body of water to which the discharge occurs (i.e., meets the variance criteria), EPA
or State may adjust the permit limitations to a less stringent level.
This adjustment is called a "Section 316(a) variance" and is included in the National
Pollutant Discharge Elimination System (NPDES) permit (or State equivalent) that the facility
receives from the permitting authority. EPA draft guidance for issuing these variances is provided
in the 1977 Section 316(a) Technical Guidance Manual; however, this guidance has never been
finalized by EPA. Some EPA Regions, however, have developed their own guidance.
The actual thermal limitations and monitoring requirements with which the facility must
comply are specified in the permit. Permit limitations for thermal discharges may be established
as a maximum temperature at the point of discharge (POD), maximum rate of temperature
increase at the POD, and temperature difference between a sample taken at the POD and a
sample taken upstream of the POD (i.e., ambient water temperature). Discharge temperature
limitations in the permit are calculated by considering a specified mixing zone in which the thermal
effluent is expected to be assimilated by the receiving water. In many cases, heat load is
commonly limited, but discharge temperature, although monitored, may not be limited.
WQS requirements for thermal discharges and the related mixing zone requirements vary
widely from State to State. Preliminary reviews by EPA indicated that approximately one third of
the 580 power plants in the U.S. have been granted a Section 316(a) variance from WQS EPA's
review also revealed that the EPA has little information readily available on the thermal limitations
that have been granted.
Based on these findings, EPA determined that further evaluation was needed. In August
1989, EPA's Office of Wastewater Enforcement and Compliance (OWEC) initiated this study of
the CWA Section 316(a) variances for thermal limitations for power plants discharging thermal
effluent. This study was conducted in the following four stages:
Prepared a compendium of State WQS
Compiled a matrix of NPDES permit limitations and State WQS
Developed a list of facilities recommended for review in depth
ES-1
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Conducted data reviews and site visits, including site visits to, and a file review of,
Brunner Island Power Plant; a review of facility operation and discharge data at
selected facilities; and interviews with selected State, EPA Regional, and facility
staff.
The first two stages resulted in separate reports, which are summarized here. The information
gathered and findings for the remaining stages are included in this report.
I. Impact of Thermal Effluent
Information provided by the EPA Regions and permitted facilities did not reveal
widespread environmental problems resulting from the discharge of thermal effluent from power
plants.1 Isolated cases where substantial degradation occurred were most often the result of
administrative error on the part of the permitting agency (e.g., inappropriate permit limitations)
rather than facility noncompliance with permit limitations. Fish kills caused by "cold shock"
(sudden drop in temperature in the thermal plume during winter months) and excessive
temperatures are two acute impacts that were identified at some facilities in this study. In some
of these cases, facilities with Section 316(a) variances had high temperature discharges, which
caused fish kills. It has been documented that certain thermal discharges have a chronic effect
on the populations of different aquatic species in certain water bodies (e.g., reduced diversity,
change in species mix, health effects) as well as adverse impacts on surrounding flora and fauna.
To support variance requests and permit reissuance, facilities conduct environmental
studies of varying scope and depth. In some cases, these studies are required in the permit. In
addition, facilities may employ a variety of procedures to reduce the impact of thermal discharges.
Many of these procedures also may be required in permits. These are discussed in Section II
below.
II- Shutdown Procedures and Control Mechanisms to Reduce Impact on the
Environment
Power plants shut down under a variety of circumstances, including decreased power
needs, periodic maintenance, and emergencies. Shutdown procedures are generally designed
to protect equipment and address health and safety concerns. Although not the primary purpose,
many of these procedures protect fish from cold shock by preventing sudden drops in discharge
water temperature. This study identified few facilities that have procedures for a controlled
shutdown specifically designed to reduce the potential for cold shock. One facility that does have
such procedures is Brunner Island, which uses a "fish comfort system" designed to ensure
temperature drops of no greater than 10° F per hour in the discharge channel during unit
shutdown.
A wide variety of control mechanisms are used, other than controlled shutdowns, to reduce
the impact of thermal effluents on the environment. These mechanisms range from cooling
towers that cool the effluent to physical barriers that keep fish out of discharge channels where
the fish are at greatest risk from exposure to temperature fluctuations and maximum
temperatures. Control mechanisms that are designed to prevent environmental degradation due
Note: Regions may not be apprised of problems because violation evaluation in the Permit
Compliance System and on the Quarterly Non-Compliance Reports (QNCRs) may not necessarily meet
the thresholds for reporting and/or enforcement action.
ES-2
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to thermal effluent may vary to accommodate seasonal temperature changes. These control
mechanisms either reduce the water temperature at discharge and/or help reduce water
temperatures outside the mixing zone. Mechanisms include: cooling towers, cooling ponds,
submerged pipes, and multiport diffusers. Control mechanisms that are used to keep fish out of
discharge channels include: screens, nets, barriers, water jets, and vertical bars. These
mechanisms vary in effectiveness.
IN. Environmental Studies Performed to Support Variances
Studies to support initial Section 316(a) variances may be quite extensive and involve
collection of facility operating data, environmental data, and biological data, as well as
mathematical or physical modelling. However, at the time of permit reissuance, the amount of
data required to support a variance is usually less unless a change has occurred in: facility
operating conditions, the discharges that interact with the thermal discharge, or in the biotic
community of the receiving water.
Biosampling and environmental monitoring help ensure that the environmental integrity of
a water body is maintained. Some permits require monitoring on a periodic basis, others have
no requirements for monitoring or biosampling. In cases where the permit does not specify
monitoring requirements, changes in water quality (most typically improvements) may go
undetected unless the facility personnel perform monitoring on their own or a State or federal
agency monitors that part of the waterway. Improvements in water quality may change the
parameters under which a variance may be considered for reissuance.
IV. Key Findings
Key findings from this study to date are: 1) For the majority of facilities (some with
variances, others without), impacts from thermal effluent have not been found to be large and/or
permanent, although additional studies at some facilities are needed; 2) Most thermal issues are
not related to intentional noncompliance on the part of the facility, but rather are administrative
in nature on the part of EPA (e.g., there may be no permit provisions that ensure that variance
criteria are met, no monitoring provisions are specified in the permit, and/or no permit
requirements that protect fish at facilities where cold shock is likely to occur); 3) The lack of final
guidance on Section 316(a) variances from EPA Headquarters has contributed to inconsistencies
in permit requirements and the process by which variances are issued; 4) EPA is losing its
institutional knowledge on thermal issues, thereby decreasing the EPA's ability to review permits.
The following recommendations reflect consideration of these findings and discussions
with EPA staff from the Regions and Headquarters:
Update the previously developed listing/summary of Section 316(a) and Section
316(b) status for power plants.
Issue final guidance, formalize EPA policy, and develop permit language and
enforcement checklists to ensure that Section 316(a) variances meet variance
criteria.
Provide training for EPA Regional and State permit writers.
ES-3
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Identify States and EPA Regions that have established processes by which
variances can effectively be issued and reissued (e.g., the Technical Advisory
Committees in Region I) and share this information among the other States and
EPA Regions through a national thermal guidance panel.
Evaluate ways to increase the reporting to EPA and the public of thermal effluent
violations from the States, including modifying the reporting protocols for the
Permit Compliance System.
Reconsider the establishment of technology-based new point source performance
standards governing thermal discharges, for steam electric plants over the long-
term.
In summary, OWEC believes that the Section 316(a) variance is a useful tool when
appropriately and consistently applied. To promote consistency, OWEC is developing a training
course for power plant permit writers and others involved in thermal effluent management. The
pilot workshop is to be held in Region II in the second quarter of FY 1993. A guidance document
also is under development and will be available in draft form by October 1993. The workshops
and guidance document will address the first five recommendations made above. The sixth has
been placed on the selection list for guidelines review, update, and reissuance.
ES-4
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REVIEW OF WATER QUALITY STANDARDS, PERMIT LIMITATIONS, AND VARIANCES
FOR THERMAL DISCHARGES AT POWER PLANTS
1.0 INTRODUCTION TO THE REPORT
This report provides an overview of issues relating to thermal effluent discharges,
limitations, and variances. The report also highlights environmental impacts of thermal effluent!
methods to mitigate the impacts, and recommends EPA actions to address thermal issues.
The thermal component of any discharge is defined as a pollutant by the Clean Water Act
(CWA) and is subject to technology-based or water quality-based effluent limitations, whichever
is more stringent. Thermal discharges are of concern because they occasionally cause fish kills
and have been known to cause other detrimental effects such as increased levels of parasitic
and/or bacteriological infection and poor body condition in aquatic life, as well as reducing
population size and species diversity. Thermal discharges may also have a detrimental impact
on benthic flora and fauna in estuarine and marine areas. If the discharger can show that the
effluent limitations calculated from State water quality standards (WQS) are more stringent than
necessary to ensure protection and propagation of a balanced, indigenous population of shellfish,
fish, and wildlife in and on the body of water where the discharge is to occur, EPA or the State
may adjust the effluent limitation to a less stringent level that still ensures such protection and
propagation.
This adjustment is called a "Section 316(a) variance" and is included in the effluent
discharge permit the facility receives from the State or EPA Region. Section 316(a) of the CWA
allows dischargers such as power plants to apply for a variance from WQS to provide flexibility
to ensure that thermal discharge limits are protective of a "balanced indigenous population" of
aquatic life in and on our nation's waters, while balancing other environmental, social, and
economic factors. These factors may include costs such as cooling towers, retention ponds, and
protocols for facility operations for minimizing effluent temperatures and fluctuations. Other
factors include: losses of electricity production capacity due to retrofitting of cooling towers;
evaporative water losses caused by cooling towers; land use restrictions; energy requirements-
solid waste disposal; clean air act compliance; and aesthetics. This variance provision for thermal
effluent is particularly important to power plants because thermal effluent is such a significant part
of their discharge. EPA draft guidance for issuing these variances was provided in the 1977
Section 316(a) Technical Guidance Manual; however, this guidance has never been finalized by
EPA. Some EPA Regions, however, have developed their own guidance.
WQS for thermal limitations and the related mixing zone requirements vary from State to
State. Preliminary reviews indicated that approximately one third of the 580 major power plants
in the U.S. had been granted a Section 316(a) variance from those standards. Major facilities are
defined by EPA to include NPDES permittees with an industrial rating of 80 or greater under the
NPDES permit rating procedures. EPA selected facilities from this universe because permit
violation, and enforcement data are more likely to be reported by the States in EPA's Permit
Compliance System (PCS) data base. The review also revealed that EPA had little information
readily available on thermal limitations.
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Based on these findings, EPA determined that further study was needed. In August 1989,
EPA's Office of Wastewater Enforcement and Compliance (OWEC) initiated a review (this study)
of the CWA Section 316 variances for thermal limitations for major electric power plants
discharging thermal effluent. The goals of the review are to:
Compile information on State thermal loading guidelines, standards, and limitations
Compile NPDES permit information on all power plants having active discharges
Prepare a listing of facilities with Section 316(a) variances that warrant in depth
review based on certain criteria
Conduct an in-depth analysis of selected facilities above
• Compare and analyze permit limitations, discharges, and standards of similar
facilities.
EPA initiated a second study in April 1991 to examine in further detail issues identified during the
initial data collection phase. In this second study, EPA conducted additional interviews with EPA
Regional staff and facility staff. This report details the information collected to date from both
studies, as well as further research and analysis of thermal limitations, study methodology,
findings, and conclusions/recommendations. Future work may include site visits to other facilities,
review of State files on specific facilities, and further research to respond to issues identified in
this report.
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2.0 STUDY METHODOLOGY
EPA's review of WQS, permit limitations, and thermal variances occurred in four stages
The first two stages resulted in separate reports, the Compendium of State Water Quality Limits
for Thermal Discharges and Mixing Zones and the Matrix of NPDES Permit Limits and State
Water Quality Standards for Thermal Discharges from Major Power Plants, which are summarized
in Sections 2.1 and 2.2 . The remaining stages are included in their entirety in this report The
information collected from the site visits to Brunner Island is contained in Attachments A and B
and summarized in the findings section of this report.
2.1 Compendium of State Water Quality Standards
r^A _,As a first Stage in comP'Iin9 and analyzing information on thermal discharge limitations
EPA developed a compendium of State-approved WQS relating to thermal discharges and
corresponding mixing zones. The compendium contains a summary of each State's WQS for
thermal discharges and mixing zones, the issuance date of the thermal discharge WQS and the
State regulatory citation for the WQS. '
To develop this compendium, EPA collected information on State WQS from the
Environment Reporter - State Water Laws issued by the Bureau of National Affairs. In addition
EPA conducted interviews with personnel from State water resources departments and EPA's
Criteria and Standards Division to ensure compilation of the most current regulations EPA
compiled this information into a document entitled Compendium of State Water Quality Limits for
Thermal Discharges and Mixing Zones.
It should be noted that WQS in many States are not based on the extensive data and
modern scientific theories that have become available since the standards originally were issued
Largely because of the availability of Section 316(a) of the CWA, which enables permittees to
perform site-specrfic evaluations in lieu of applying WQS, many States have not chosen to update
their thermal WQS with the new data and procedures that have become available since that time.
2-2 Matrix of NPDES Permit Limits and State Water Quality Standards
In the second stage, EPA prepared a report containing matrices of National Pollutant
Discharge Elimination System (NPDES) permit limitations and State WQS for the 580 S
power plants with active thermal discharges. The State WQS included in the matrices were
summarized from the compendium to facilitate comparison with the NPDES permit limitations in
the matrix. (Note: Comparing WQS and permit limitations does not indicate whethe a variance
is warranted or whether the permit limitations have been exceeded. Permit limitationsan^ State
m^hT ™a*ured drffef ^ «* as a re^' Cannot be compared directly. Instead the WQS
must be put into a formula that takes into account the amount of heat discharged size of me
thermal plume, amount of water discharged, and other variables. In addition, some
Z^noTih "f °,^ thf a"°W for me dischar9e of heated effluent i. „_„ ul ulalo
(because those facilities have been "grandfathered" from complyinq with certain State
requirements)^ EPA obtained a majority of the information on the N^ES pe'mttZiJttons from
EPA s Permit Compliance System (PCS). The Utility Data Institute, EPA Headquarters'files EPA
maSs ' and State Wat6f qUa'ity auth°rities provided additional information tome
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The information collected on NPDES permit limitations and State WQS included:
Facility permit number
• Facility name
• Receiving water
Permit expiration date
• Design discharge flow
Pipe schedule number
• Thermal parameter measured at the discharge point
Minimum limitation for the associated thermal parameter
Average limitation for the associated thermal parameter
Maximum limitation for the associated thermal parameter
• Months limitation applies
• State water quality class
Maximum increase above the ambient temperature
• Maximum temperature of receiving water
Status of Section 316(a) variance
• Enforcement actions for thermal violations.
Not all of this information was available for each facility. From this facility-specific information,
EPA selected facilities for further review, as discussed below.
2.3 Facilities Reviewed In Depth
EPA selected from a list of the 580 major facilities 33 that met at least one of the following
criteria for more detailed review:
Variance application or approval, but no thermal discharge limitations (accordina
to PCS) y
High thermal discharge limitations
History of noncompliance or citizen complaints.
In some cases, EPA also used as selection criteria evidence of fish kills and location of facilities
on water bodies designated by the State as having high resource value or containing endangered
species. For the 33 selected facilities, EPA then compiled the following information:
Permit number
• Facility name
• Receiving water
Name of contact
Telephone number of contact
Variance approval status
Thermal discharge limitations
• High discharge limitations
• Enforcement actions.
This information is contained in Attachment C of this report. The next section presents the
methodology used in collecting the information; the findings are summarized in Chapter 3.0.
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2.4 Data Reviews and Site Visits
Discussions with EPA Regional, State, and facility staff provided the core of data on facility
operations and discharges. In addition, EPA reviewed PCS and facility records to compare the
actual discharges, permit limitations, State standards, and variances of several facilities including
Brunner Island.
EPA contacted several of the selected facilities from Section 2.3 to discuss operational
data, facility type, compliance rate, and discharge information. EPA also researched and
analyzed the permit limitations, discharges, and enforcement history of the six facilities
discharging thermal effluent into the Susquehanna River. The Susquehanna River was selected
because of its proximity to a facility that had a history of fish kill incidents. Moreover, some of
these facilities are located in Pennsylvania, which has a different method for assessing mixina
zones than other States.
In all, EPA gathered information about 39 major facilities relating to facility operations
discharges, permit limitations, State WQS, and variances. For specific facilities, EPA collected
information on facility procedures for unit shutdown, the process by which the facility obtained its
initial variance, studies to support renewal of the variance, environmental monitoring conducted
by the facility, and the presence of any environmental problems. EPA also interviewed Regional
and State staff on how variances are issued and reviewed by the States and Regions (in
particular the Technical Advisory Committee in Region I). Other interviews, particularly in Region
V, focused on facilities experiencing difficulty complying with State thermal WQS, while other
discussions focused on issues relating to the Section 316(a) program and the CWA
reauthorization.
In addition, EPA made two site visits to Pennsylvania Power and Light's (PP&L) Brunner
Island facility in York County, Pennsylvania. The purpose of the site visits was to make
preliminary determinations of the type of information to be collected during site visits to other
facilities. These site visits consisted of a review of State files, a tour of the facility, discussions
with facility environmental staff, and observation of biosampiing at the facility. This information
supplemented the review of State files on the enforcement history of the facility. The information
compiled on the Brunner Island facility is integrated with the findings from discussions with staff
at other facilities and the State.
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3.0 STUDY FINDINGS
The results of the research and analysis of data on permits, State WQS, and variances,
the impacts of thermal effluent, as well as information on specific facilities, are contained in this
section.
3.1 Establishing Thermal Permit and Variance Limitations
The goal of the CWA as stated in Section 101 is to "restore and maintain the chemical,
physical, and biological integrity of the nation's waters." A key objective is the eventual
elimination of pollutants discharged into the waters of the U.S. A principal means to achieve that
objective is a system to impose effluent limitations on, or to otherwise prevent, discharges of
pollutants into any waters of the United States from any point source. The CWA's primary
mechanism for imposing effluent limitations on pollutant discharges is a nationwide permit
program established under Section 402 of the Act, NPDES. Each effluent limitation imposed on
an NPDES permittee is generally developed using technology-based or water-quality-based
standard methodology. Generally, technology-based limitations define a floor or minimum level
of control and are applicable at the point of discharge. Technology-based limitations are
established through either: 1) national effluent limitation guidelines developed by EPA, or 2) the
permit writer's best professional judgement.
In addition to technology-based limitations, each permittee must comply with limitations
derived from additional or more stringent WQS established by the State (and approved by EPA)
to achieve or maintain the beneficial uses of a particular waterway. State WQS take precedence
over any less stringent technology-based controls. These standards do not apply directly at the
discharge pipe, but rather, are converted to discharge pipe limitations by the permit writer by
determining the assimilative capacity of the stream and dividing it among the discharger's waste
load allocation (WLA) to the stream.
In the case of the thermal component of a discharge, no national technology-based
effluent limitation guidelines currently exist. As a result, thermal limitations must be developed
based on WQS. WQS applicable to thermal discharges are generally set as a maximum
temperature or maximum incremental temperature increase at a point outside of the mixing zone.
(NB: the first effluent guidelines for the steam electric power industry did place technology-based
controls on heat. EPA was quickly sued by the power industry and the courts remanded that
provision to EPA. Since that time, no additional technology-based limits have been proposed or
adopted for the thermal component of discharges.)
The actual thermal limitations and monitoring requirements with which the facility must
comply are specified in the NPDES permit. The State or EPA permit writer may consult various
guidance manuals to determine the validity of the proposed permit limitations. One of those
manuals is the Quality Criteria for Water 1986 (The Gold Book). The manual outlines
methodologies for determining appropriate water quality criteria for all States. This manual is an
attachment to the report entitled Compendium of State Water Quality Standards.
The concept of Section 316(a) varies significantly between States and between Regions
A State can write both WQS and mixing zone dimensions for thermal pollutants in such a way
that virtually no power plant will need to apply for a Section 316(a) variance. In some States
plants in operation before a certain time have been grandfathered and are excused from
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performing a Section 316(a) demonstration. In other States, the requirements are more rigorous
and even extend to industries other than steam electric power.
Permit limitations for thermal discharges may be established as a maximum temperature
at the point of discharge (POD), a maximum incremental temperature increase at the POD, and/or
the temperature difference between a sample taken at the POD and a sample taken at the plant
intake or upstream of the POD. In most cases, heat load is commonly limited, but discharge
temperature, though monitored, may not be limited. Compliance with mixing zone requirements
is determined by in-stream thermal monitors or with mathematical models used to back calculate
from the temperature at the POD to the expected temperature in the mixing zone as a result of
the thermal discharge. The in-stream monitors that determine compliance with mixing zone
requirements may be located as much as several miles downstream depending on the size of the
mixing zone. The mathematical models consider such characteristics as the size of the waterway,
the volume of the discharge, the stream bank configuration, mixing velocities, dilution ratio, and
other hydrologic or physiographic characteristics. While each State has a specified mixing zone,
each defines that mixing zone differently.
An exception to the mixing zone approach is that used by the Commonwealth of
Pennsylvania. Pennsylvania does not specify or consider mixing zones in setting thermal
discharge limitations. Instead, an instantaneous complete mix of the thermal discharge with the
receiving stream is assumed. Therefore, the "mixing zone" actually is the entire stream, allowing
for a greater dilution of the discharged thermal effluent. According to the Pennsylvania
Department of Environmental Resources (PA DER), thermal discharge limitations established in
individual facility permits are often more stringent to offset the benefits of whole stream dilution
(this study did not attempt to verify this assertion). Generally, the effluent thermal limitations in
Pennsylvania are based upon an allowable heat rejection rate and are expressed in terms of
BTU's (British Thermal Units) per hour. The basic theory underlying this principle is that the heat
gained by the stream is equivalent to the heat lost by the discharge. The maximum allowable or
actual discharge temperature then is calculated based upon the equation of the heat rejection
rate. Variations in the equation account for cases where stream flow is augmented, or where
the stream and intake temperatures differ. Pennsylvania has determined temperature variations
and limitations on a site-specific basis for every body of water in the Commonwealth. Detailed
calculations, equations, and examples are outlined in the PA DER's Staff Guidance for
Implementation of Temperature Criteria, dated October 3,1989. This document is an attachment
to the EPA report entitled Matrix of NPDES Permit Limits and State Water Quality Standards.
3.2 Impact of Thermal Effluent
Thermal discharges can impact aquatic life in several ways. Either cold shock (a sudden
decrease in water temperature) or high temperature discharges may cause high fish mortality
rates due to the inability of different cold-blooded species to adapt to certain changes in
temperature. In addition, increases in ambient temperatures may lead to changes in the
population of certain aquatic species. Higher temperatures may also adversely affect plants and
benthic organisms that are exposed to the thermal plume. The majority of facilities contacted did
, J Td-.~ !Ql l Q<^ ^2 ~ TI* + TI> where Td is the maximum allowable or actual discharge temperature Q
is the design stream flow, Qd is the anticipated or actual discharge flow, T2 is the maximum allowable
downstream temperature, and T, is the intake temperature. The design stream flow and temperature are
estab ished to represent a worst-case scenario and are based on low flow and median temperature
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not report any significant environmental problems as a result of thermal effluent. Discussions with
State staff and a review of PCS data revealed some problems relating to fish kills and permit
violations, however.
Several facility staff mentioned recreational benefits enjoyed by fishermen who take
advantage of the higher concentrations of fish found in thermal plumes in fall, winter, and early
spring. Any adverse effects to the fish, they believe, would be reported by the fishermen. Only
one of the facilities contacted has received citizen complaints regarding thermal effluent. In
addition, temperate waters are well suited for commercial fish operations; some State and/or
federal agencies utilize waters near power plants for fish stocks or hatcheries.
The following section documents some of the problems that were identified in this study
from conversations with staff in the EPA Regions and at facilities, and from site visits. However,
the absence of adverse impacts at most of the selected plants in this study provides the basis
for a conclusion that there is only a small likelihood of significant thermal impacts occurring at the
nation's power plants operating under Section 316(a) variances.
3.2.1 Impact of Cold Shock
One of the most acute forms of environmental impacts from thermal effluent is "cold
shock," which results in fish kills. Cold shock to fish results from sudden drops in temperature
in a thermal plume, usually during winter months. Typically, cold shock occurs during a unit or
facility shutdown when the thermal effluent is replaced by a rapid discharge of unheated water.
Certain species of fish less than 1 year old are especially susceptible to a sudden drop in
temperature over 5° F. The fish kills appear to occur only in winter due to the physiology and
location offish during these months. During the coldest water periods, sudden temperature drops
are more likely to cause death in most fish species than during warmer ambient temperatures
(spring and fall) when higher temperature drops can be tolerated. Furthermore, the comfort range
of the fish is such that in the warmest months, fish congregate in the deeper, cooler waters, and
during the winter they are attracted to and stay within the thermal plume. Accordingly, fish are
more likely to be present in the plume and therefore affected by thermal fluctuations during the
winter months.
Cold shock is most likely to occur at facilities that:
Are located in cold climates (northeast and northwest) or mountainous regions.
Have "once through cooling" and do not have any form of supplemental heat
dissipation or rapid effluent mixing device (i.e., cooling ponds or multiport diffusers)
to reduce the change in temperature (AT). These facilities are more likely to have
a thermal plume with a significantly higher temperature than that of the ambient
water.
Have one or two operating units, where shutdown of one unit has a significant
effect on the total discharge.
Have older units, which are more likely than newer units to be used only
intermittently during peak loading, and are shutdown on weekends, holidays, and
during periods of lessened demand. The more shutdowns a facility has, the
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greater the number of occasions where cold shock may occur as a result of
temperature fluctuations in the thermal plume.
Only one facility in the study reported fish kills attributable to cold shock in the last 2
years. This facility experienced fish kills due to "cold shock" in December 1985, January 1988,
January 1990, and January 1991. The 1991 fish kill occurred during a controlled shutdown of the
largest of three units. At the time of the controlled shutdown, one of the remaining two units was
already out of service. As a result of both unit shutdowns, the amount of heated discharge
entering the channel was significantly reduced. The drop in water temperature killed 500 fish.
In January 1990, one unit was brought out of service in a controlled shutdown to 1/3 of the unit's
output. The "fish comfort system" activated and reduced the flow from the facility to avoid a
sudden pass through of unheated river water. However, at 1/3 load, the temperature differential
across the unit was too great to continue with a controlled shutdown without critical damage to
the facility, and the staff removed the comfort control system from operation. The shutdown of
the unit resulted in a 30° F increase in the discharge channel over an hour as flows from the
other two units overran the first unit's decreased discharge. A sudden drop in temperature (15°
F in approximately 10 minutes) occurred in the channel when the comfort system was removed.
Subsequently, unheated river water passed through the facility and into the discharge channel
The facility staff interviewed believe the fish kill was a result of the sudden decrease in
temperature and not the initial increase.
A January 1988 fish kill due to a "cold shock" resulted from decreased flow from the facility
during shutdown of one unit and the undertow of the river water back up the discharge channel.
This resulted in a 29° F drop over 10 minutes in the channel, killing 180 fish. At this facility, there
are no controls preventing fish from entering the discharge channel, thus exposing the fish to the
potential variations of temperature.
The facility staff attributed the December 1985 fish kill to a drop in power load; the staff
attempted to maintain a 5 megawatt per minute drop in load, but ended with a 6 megawatt per
minute drop. The target drop rate was based on the staff's experience that a 5 megawatt per
minute drop rate maintains less than a 10° F drop per hour. The facility staff believes it is
possible that the ambient river temperature being lower than expected (in addition to the greater
drop) was a factor in the large decrease in temperature. Adjustments in procedures were to
include a check of ambient river temperature and adjust the rate drop accordingly.
The staff reported that controlled shutdowns are preferred over a "trip" (i.e., an automatic
emergency shutdown of the unit) for safety and environmental reasons. On a "trip," the
temperature in the discharge channel actually increases because of the influence of the
discharges from the two other units.
3.2.2 Impact of Excessive Temperatures
High temperature thermal discharges can cause fish kills and other detrimental impacts
to the aquatic environment. Some facilities reported that they have experienced heat-related fish
kills. Many of these fish kills were isolated incidents and not indicative of a chronic problem
Facilities with once through cooling and no supplemental heat dissipation facilities are more likely
to discharge high temperature thermal effluent than are those facilities that employ cooling ponds
cooling towers, diffusers, or recycle the water back through the facility after cooling
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EPA Regions have identified facilities where ongoing problems exist or existed and where
fish kills have been reported in great numbers due to excessive temperatures. According to
Region V files, one station in Indiana heated the West Fork of the White River to 108° F, resulting
in an extensive fish and mollusk kill downstream. Four Ohio facilities heated their respective
streams to higher than 100° F several miles downstream. Files show one of the four facilities
increased river temperatures to 110° F in the summer of 1988, resulting in a major fish kill of
approximately 2 million fish. At the time of these fish kills, all four facilities were in compliance
with their permits; none of the permits had maximum temperature limitations. Rather, limitations
were based on the maximum heat rejection rate for the facility.3 In effect, these facilities can
heat the river to facility capacity. In practice, as river flow rates reach summer minimum or
drought condition minimum flows, power plants generally must reduce their operations, because
the volume of cooling water available in the river and/or high intake water temperatures make
operating the plant at full capacity impossible. EPA has since imposed thermal limitations that
require the facility to meet maximum State WQS on a fully mixed basis. There are ongoing
permit limitation negotiations with several Region V facilities.
In addition to fish kills, high temperature discharges can adversely impact the aquatic
environment in several ways including: 1) damage to benthic grasses and fauna; 2) loss of
spawning areas; 3) bank-to-bank thermal plumes preventing fish migration; and 4) loss of eggs,
larvae, and planktonic organisms in riverine thermal plumes. For example, the thermal plume
from a Region IV facility adversely affected approximately 3000 acres of the receiving bay area.
Within this 3000 acres, at least 1100 acres of seagrass and attached macroalgal communities
were destroyed because of excessive temperatures. In addition, major components of locally
indigenous fish and invertebrate species are excluded from the thermally-impacted area.
3.2.3 Changes in Population of Certain Fish Species
More commonly, high temperature discharges cause chronic, health related problems to
aquatic life. For example, thermal discharge at certain power plants may affect indigenous fish
populations by reducing the presence and number of cold-water species, while increasing the
abundance of warm-water species. A report entitled Changes in the Fish Community of the
Wabash River Following Power Plant Start Up: Projected and Observed and studies by Region
V in Indiana suggest that changes in fish population are occurring in some water bodies where
there are variances to the WQS in the permit. These variances allow facilities to exceed the
maximum 5° AT criteria included in most State WQS. More studies may be needed to identify
the long-term effects of exceeding the WQS at specific sites.
3.2.4 Entrainment and Impingement
Many facilities have installed mechanisms to reduce environmental damage caused from
entrainment and impingement. Entrainment refers to smaller organisms (e.g., phytoplankton, fish
eggs, larvae) that are passed through the facility with the cooling water and are subjected to
pumps, antifouling agents, condensers, and other physical, chemical, or thermal related causes
of damage. Impingement refers to larger organisms such as fish that enter the cooling water
intake system and then are trapped on screens. Although this study does not address
environmental damage caused by entrainment and impingement, it is important to note that at
some facilities a trade off exists between discharge temperature and impingement. Often, the
3 These variances are appropriate for many other facilities since the facility may discharge into an
ocean, a Great Lake, or a large river with a strong current thereby minimizing any effect on water quality.
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more water that is drawn from the water source through the condensers to lower effluent
temperatures, the more aquatic organisms die from entrainment and impingement.
3.3 Shutdown and Load Reduction Procedures and Control Mechanisms at Facilities
Facility or unit shutdowns or load reductions often occur for facility or unit maintenance,
reduction in energy demand, or exceedance of discharge temperatures. "Shutdown" refers to
bringing a unit(s) offline (i.e., ceasing energy production). "Load reduction" refers to decreasing
energy production.
An EPA review in August 1989 found that many facilities are not required by permit to
have facility or unit shutdown procedures to eliminate or reduce risk of cold shock to aquatic life.
However, a wide variety of control mechanisms to reduce the impact of thermal effluent on the
environment are used, from cooling towers and cooling ponds that cool the effluent to physical
barriers that keep fish out of discharge channels (where the fish are at greatest risk from
temperature fluctuations). Control mechanisms that are designed to prevent environmental
degradation due to thermal effluent may vary to accommodate for seasonal temperature changes.
These control mechanisms reduce the water temperature at discharge and/or help reduce water
temperatures within and outside of the mixing zone. Mechanisms include: cooling towers,
cooling ponds, discharge pipes, and multiport diffusers. Control mechanisms that are used to
keep fish out of discharge channels include: screens, nets, barriers, water jets, and vertical bars.
These mechanisms vary in effectiveness.
3.3.1 Shutdown Procedures to Prevent Cold Shock
Most facilities have some type of shutdown procedures in which operating units gradually
are brought offline as the power level is reduced. These procedures, however, normally reflect
health and safety concerns related to protecting facility equipment, rather than preventing cold
shock to fish. Efforts to reduce the risk of cold shock may be hampered, in some instances, by
load reduction procedures that are required to meet air quality standards.
Some power plants operate only part time in order to supplement regional energy
production during periodic high energy demand, resulting in occasional shutdowns. Fish that
congregate in the facility's thermal plume during winter months may be susceptible to cold shock
during these shutdowns. At this time, there are no national permit requirements or guidance on
shutdown procedures to address the potential problem of cold shock. To help assess the impact
of facilities operating part time, Region V has proposed special conditions in the permit of a facility
that is prone to cold shock. The Region has suggested that the permit contain a "Special
Condition" requiring the permittee to conduct an evaluation of the potential for cold shock to fish
in the thermal plume. The evaluation would include winter fish sampling and a summary of winter
operating conditions for the past 4 years. The summary would include daily average and
maximum AT and discharge temperatures. After two years, a minimum discharge temperature
of 36° F would be required when intake temperatures are below 36° F unless the evaluation
documents the absence of cold shock potential. At one Region I nuclear facility, the permit
requires gradual temperature decreases to protect marine life from cold shock. As characteristic
of most nuclear plants, these controlled temperature decreases are not used in the event of a
reactor emergency shutdown, because in those situations, the objective is to avoid core damage
Loss of adequate cooling water, such as would be caused by failure of cooling water condenser
pumps or clogging of intake screens, might require an emergency reactor shutdown Region IV
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requires all Section 316(a) demonstrations to address potential "cold kills" and assure adequate
procedural controls.
In 1983, Brunner Island installed a fish comfort system in response to frequent fish kills.
The comfort system allows for controlled temperature decreases of 10° F per hour during unit
shutdown. Since then, fish kills have occurred less frequently and with less severity, but a
problem still exists. The problem of cold shock at Brunner Island may be related to the
disproportionate amount of water discharged from one unit relative to the combined discharges
of two other units. In response to this problem, Brunner Island prepared a report examining each
of the seven fish kills between 1983 and 1991 attributable to cold shock. Recommendations from
the study include: 1) install a control modification to the discharge channel valve system on units
one and two to achieve more control over discharge temperature; 2) conduct an annual check
of the fish comfort system on unit three; 3) revise unit three control shutdown procedures so that
the facility can better ensure a 10° F drop per hour; and 4) install temperature monitoring
equipment on two units.
For most facilities, shutdown procedures related to cold shock are not needed.
Procedures are not needed at facilities that discharge directly into a lake or large waterway where
a rapid mixing of effluent occurs. For example, at a Lake Michigan facility, a year-long study
performed in conjunction with the State determined that wind and current affected water
temperature more than the thermal discharge. In the case of internally driven shutdowns, the risk
of cold shock also is low for a facility that has three or more units, because a single unit shutdown
will only result in a moderate and endurable drop in temperature in the thermal discharge.
However, grid-affected unit trips likely will impact all the units at a given site, causing a larger
impact in thermal discharge. The risk of cold shock and the related need for facility procedures
is also low for facilities that operate in climates that are warm year-round. The risks of cold shock
are also likely to be minimal at facilities with a history of winter outages that have not caused fish
kills. Because cold shock appears to be very site-specific, such actual historic data offers the
best evidence possible that the likelihood of cold shock is minimal.
Cold shock may, however, become more of an issue as facilities age and are used only
intermittently to supplement peak power demands, or retooling extends their useful life. An
important consideration, however, is that fish populations (and certainly less mobile species) are
less likely to congregate in a thermal plume that is intermittent, as opposed to a plume that is
continuous. Moreover, older plants generally are smaller than newer plants, and thus they
produce a smaller plume. All of these factors must be considered in evaluating cold shock
potential.
3.3.2 Control Mechanisms to Prevent Damage from Thermal Discharge
Power plants employ a variety of techniques that use water to cool their condensers.
Many facilities have installed heat dissipation systems to minimize the impact of thermal discharge
on the environment; others use operating procedures (such as the shutdown procedures
described previously) to reduce the impact on the environment.
Typically a once through cooling process does not cool the water prior to discharge, rather
it involves drawing in water, running it once through the facility, and directly discharging the water
in one uninterrupted flow. Power plants prefer using once through cooling because it costs less
than mechanisms that cool the water prior to discharge. Once through cooling is appropriate for
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certain facilities, but when used alone, it poses the greatest threat to aquatic life for both cold
shock and thermal shock.
Cooling towers and cooling ponds are effective in lowering the temperature of the water
after it is has passed through the condensers, prior to discharge. Depending on the facility, the
cooled water is either recycled through the facility to be used again or periodically discharged to
the receiving body. Cooling towers generally require the use of antifouling agents, which may
have their own water quality issues. Salt water complicates any circulating water system, whether
it is once-through or closed cycle, but this added complexity does not preclude the use of cooling
towers. In addition, cooling towers may cause significant water loss due to evaporation.
Cooling or retention ponds are large reservoirs where water is stored after passing through
the facility, allowing time for the water to cool prior to being recycled or discharged. Cooling
ponds require approximately one acre per megawatt and may not be feasible for high megawatt
facilities with a small plant site area. The acreage required for cooling ponds or reservoirs varies
according to geographic location. Facilities located in arid climates may require more acreage
per megawatt.
Some facilities locate their discharge pipes or multiport diffusers offshore or in the center
and/or at the bottom of a river or lake to minimize the impact of the thermal discharge. The risk
of fish kills from cold shock or excessive temperature is minimized when diffusers are used, as
a function of water velocity and diffusion. Diffusers are equipped with nozzles or small diameter
ports that blast water at a high velocity. The velocity is great enough that fish cannot swim
against it; fish are unable to enter or rest in the high velocity zone. By the time velocities are
reduced, diffusion has eliminated large temperature differentials, and there is little risk of cold
shock or thermal shock to fish and other aquatic organisms.
The use of these control mechanisms may vary to accommodate for seasonal temperature
changes. For example, some facilities only utilize their cooling towers or cooling ponds during
summer months to reduce the discharge temperature and flow during critical ambient temperature
periods. In addition, during very hot periods, some facilities reduce the amount of electricity
generated which results in reduced temperature of the thermal effluent (as long as the same
amount of water is run through the plant).
3.3.3 Control Mechanisms that Keep Fish Out of the Discharge Channel
Several facilities supplied information on control mechanisms used to keep fish out of the
discharge channel. Mechanisms include: screens, barriers, water jets, and vertical bars. The
appropriateness and effectiveness of the control mechanisms vary, and little data were available
from the facilities to evaluate these methods. Screens vary in size and are used to physically
keep fish out of the channel. Vertical bars keep larger, adult fish out of the channel. High
velocity water jets keep fish out of the channel because the fish cannot swim against a rapid
water flow. Discharge channels differ in terms of length (from a few yards to over 3 miles), depth,
width, construction, and the temperature of water being discharged into them. Some facilities also
stated that there were no mechanisms used to keep fish out of discharge channels, and that
these channels are subsequently used for fishing by sportsmen during cold ambient temperature
periods. Fish can make their way into the discharge channel by swimming through pipes, over
fences, and a variety of other means. Subsequent heated effluent or change in discharge
temperature can cause fish kills in the discharge channel.
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For example, during the spring of 1991, a nuclear facility had an incident where 4,000 fish
were killed in the discharge channel despite control mechanisms. Normally a wall blocks fish
from entering the channel and discharge pipes maintain a water velocity that restricts access
through the pipes. There are, however, occasions when the water velocity through the discharge
pipes is reduced, and fish can swim up the pipes into the channel. In addition, during periods of
high river flow, fish may be able to swim over the wall.
3.4 Environmental Studies Performed to Support Section 316(a) Variances
Environmental monitoring and studies provide data to both the facility and the permitting
agency on the health and numbers of aquatic life near the facility. This data may be used to
demonstrate that the facility meets Section 316(a) variance criteria under its current permit, that
permit requirements need to be modified, or that a variance would not protect the environment.
This section describes some of the parameters that some initial studies for Section 316(a)
variances monitored and discusses the extent to which facilities continue to monitor the biotic
community. This section also discusses the environmental studies and monitoring that facilities
seeking to renew their variances may be required to conduct.
3.4.1 Initial Section 316(a) Variance Studies
Facilities that have applied for Section 316(a) variances are often required to engage in
extensive studies and data collection to demonstrate that facility operations under the requested
variance will assure the protection and propagation of a balanced, indigenous population of
shellfish, fish, and wildlife in and on the body of water into which the facility discharges.
Guidance for conducting and evaluating these studies is provided by the permitting agency.
Several EPA documents exist to assist a facility in preparing its Section 316 demonstration,
including the draft Interagency Section 316(a) Technical Guidance Manual. EPA, however, has
not finalized this draft guidance. In absence of national guidance, some EPA Regions have
developed their own informal guides to Section 316 demonstrations, which describe the types of
information an applicant will need to submit to be considered for a variance.
Typically, information must be gathered on physical, thermal, and biological characteristics
of the receiving water, including information on plankton, plants, macroinvertebrates, and fish.
The specific types of information and sampling methodologies are determined on a case-by-case
basis. For example, general requirements for a Section 316(a) demonstration for facilities that
will use "once-through" cooling water systems differ from the requirements for "recycling" cooling
water systems (cooling towers, spray ponds, or cooling ponds) because of varying impacts on the
environment.
An applicant is entitled to a variance so long as the overall existence of balanced,
indigenous population of aquatic organisms results from operation of the facility in its existing
configuration. The permitting agency will establish permit limitations that are protective of the
water and its inhabitants and consistent with the conditions of the Section 316(a) demonstration.
Each permit is unique, based on the particular circumstances of that facility and the receiving
water body. For example, the Brunner Island discharge results in the loss of spawning habitat
for some fish. According to the facility staff, Brunner Island maintains a variance because the
water body is still able to sustain a very large amount of spawning habitat for affected species
along other parts of the waterway.
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3.4.2 Studies to Support Reissuance of Section 316(a) Variance
The Section 316(a) variance terminates when the permit expires. Although facilities
engage in a great deal of research and data collection to initially acquire a variance, the amount
of data required by the permitting authority to support reissuance of the variance at the time of
permit reissuance usually is minimal. The permittee only needs to provide a basis for that
reissuance. The basis could be as simple as: 1) there have been (and will be) no changes to
thermal discharges from the facility or to plant operating conditions; 2) there are no changes to
facility discharges that could interact with the permittee's thermal discharges; and 3) there are no
changes (to permittee's knowledge) to the biotic community of the receiving water body. For
many facilities, there is no need to perform additional reissuance studies, because no changes
have occurred, and a reissuance is reasonable.
For certain facilities, however, continued reissuance studies may be warranted. For
example, if the waterway to which the facility discharges undergoes an improvement in water
quality or a return of anadromous fish, additional studies may be needed. As the water quality
improves along many of the nation's waters (e.g., the Ohio River), the process for Section 316(a)
variances may need to include studies on facility impact to the waterway. Several questions
would need to be addressed by the permit writer prior to reissuance: 1) How do facilities or EPA
Regions gather data on improved water quality? 2) What criteria need to be met to determine
if additional testing is required for variance renewal? 3) Does the current biological data of a
water body get compared to baseline data such as dissolved oxygen? 4) How should changes
in water quality affect a facility's permit?
In addition, many variances initially were granted, and permit limitations established, based
on modelling data. Actual field data from environmental studies may later indicate that the: 1)
actual plant operation results in discharges that do not meet the permit limitations that were based
on the modelled Section 316(a) demonstration; and/or 2) permit limitations are inadequate to
ensure the protection and propagation of a balanced, indigenous population. Moreover, studies
may be needed to support the reissuance of a variance where significant environmental
degradation has occurred, as in the case of two of the four Ohio facilities mentioned in Section
3.2.2 of this report.
3.4.3 Environmental Monitoring
Some permits require a facility to engage in environmental monitoring, other permits have
no such requirements. Moreover, sampling protocols currently are determined on a case-by-case
basis, with little formal guidance from Headquarters or some EPA Regions.
Region I Technical Advisory Committees (TAG) develop and review site specific sampling
and monitoring requirements for permitted facilities. One nuclear facility participates in an
Environmental Surveillance and Monitoring Program, the purpose of which is to determine
whether the operation of the facility results in measurable effects on the marine ecology and to
evaluate the significance of any observed effects. If significant effects are detected, the facility
must take steps to correct the situation. Similar programs were required in other EPA Regions
for virtually all nuclear power plants.
In cases where permits do not require the facility to engage in environmental monitoring
changes in water quality may go undetected unless facility personnel perform monitoring on their
own initiative or a State or federal agency monitors that part of the waterway. In these cases,
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some facilities will monitor more extensively than others. For example, one Maryland facility is
completing a 10-year quantitative study of Its effect on fin fish population and other biota. This
extensive study is contrasted by the studies performed at a facility in Region III where
biosampling procedures for fish could have been more rigorous.
Region V is considering recommending that future Ohio permits contain a special condition
requiring in-stream biological monitoring for facilities with Section 316(a) variances that do not
require compliance with all State thermal WQS criteria. Ohio EPA also has established fish
sampling protocols including suggested procedures for electro-netting fish.
3.5 EPA Procedures for Issuing and Reissuing Permits
Each EPA Region differs in the level of expertise, guidance, and institutionalized
procedures that are used in the permitting process. Region I has established the most formalized
system to issue and renew variances through the TACs. Region IV also has a TAG in place for
a Florida nuclear facility. One issue that all of the Regions share is that as a result of retirement,
attrition, and transfer, EPA is losing its institutional knowledge on thermal issues and
consequently the ability to adequately review permits. One way to ensure consistency and
preserve institutional knowledge is through Headquarters guidance.
3.5.1 Advisory Committees
Some Regions and States report using TACs when developing permits. As mentioned
above, Region I forms TACs to oversee the process by which variances are issued to facilities.
The Committees were established to augment expertise within EPA and to shepherd utilities
through the Section 316(a) process. Committee members represent key biological regulatory
agencies (e.g., U.S. Fish and Wildlife Service, the State fish and game agencies, marine fisheries
agencies, and outside experts). Power plants also are represented on the Committee. This
review process, described below, has been well received by industry and regulators. To date,
no variance decisions in Region I have been challenged by the permittees.
When a facility requests a variance, the EPA Region and the respective State convene
an advisory committee, which remains in place until the facility undergoes verification testing. The
facility provides the committee with a broad overview of facility operations and details of any
problems that may arise as a result of the facility's operations. Baseline biological data are
collected for 1 to 3 years before the facility goes on line so that any potential problems can be
addressed at an early stage.
There appear to be no other arrangements that are as institutionalized as the TAG,
although other advisory groups exist. For example, the Maryland Department of Natural
Resources has a power plant research program that makes technical recommendations regarding
the environmental effects of a facility's operations. While this program was not specifically
established to deal with thermal issues, that has been one of its primary functions for at least the
past 15 years.
3.5.2 Lack of Institutional Knowledge
EPA personnel familiar with permitting and compliance issues relating to thermal effluent
and power plants, including national technical experts are retiring or otherwise leaving EPA. As
a result, EPA may need to take actions to ensure continued expertise on power plants, thermal
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effluent, mathematical models, and other thermal issues. In one instance, Region V had objected
to the original Section 316(a) request made by a facility, but after the Region's power plant expert
left EPA, the Region lacked the expertise to support its permit objection, and the State granted
the Section 316(a) variance. The facility in question later caused a large fish kill due to the high
temperature discharge. Since that time, the permit limitations have been changed.
Currently, there is little guidance on permit preparation or conducting environmental
studies and monitoring to support variance reissuance at the federal level. This potentially could
result in poorly written permits, or lack of compliance oversight for thermal discharges. The loss
of expertise on thermal effluent impacts will be mitigated somewhat in the future by the almost
exclusive use of closed cycle cooling for new plants in certain EPA Regions; however, permit
reissuance of older plants will still require some expertise on thermal discharges.
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4.0 CONCLUSIONS AND RECOMMENDATIONS
Key findings from this study to date are: 1) For the majority of facilities, impacts from
thermal effluent have not been found to be large and/or permanent, although additional studies
at some facilities are needed; 2) Most thermal issues are not related to noncompliance on the part
of the facility, but rather are administrative in nature on the part of EPA (e.g., there are no permit
provisions that ensure that variance criteria are met, no monitoring provisions are specified in the
permit, and/or no permit requirements that protect fish at facilities where cold shock is likely to
occur); 3) The lack of final guidance on Section 316(a) variances from EPA Headquarters has
contributed to inconsistencies in permit requirements and the process by which variances are
issued; and 4) EPA is losing its institutional knowledge on thermal issues, impacting EPA's ability
to adequately review and prepare permits.
The following recommendations reflect consideration of these findings and discussions
with EPA staff from the Regions and Headquarters:
Update the previously developed listing/summary of Sections 316(a) and 316(b)
status for NPDES permittees.
issue final guidance, formalize EPA policy, and develop generic permit language
and enforcement checklists to ensure that 316(a) variances fully meet variance
criteria.
Provide training on thermal variances for EPA Regions and authorized States.
Identify States and EPA Regions that have established processes by which
variances can effectively be issued and reissued (e.g., the TACs in Region I) and
share this information among the other States and EPA Regions.
Evaluate ways to increase the reporting to EPA and the public of thermal effluent
violations from the States, including modifying the reporting protocols for the
Permit Compliance System.
Reconsider the long-term establishment of technology-based new point source
performance standards governing thermal discharges, for steam electric plants.
EPA guidance should address the need for maximum discharge temperature limitations
for some permits, maximum AT in discharge temperatures over time, and ongoing biosampling
and environmental studies. In addition, permit guidance should address the need for and
feasibility of temperature monitoring requirements at various points in the waterway and/or
requirements for periodic thermal surveys to ensure accuracy of thermal plume models.
Guidance also needs to be developed on cold shock, especially for older peak power facilities,
which operate part time. Cold shock guidance may include parameters for controlled temperature
decreases during unit shutdown and control mechanisms to restrict fish from the discharge
channel.
In summary, OWEC believes that the Section 316(a) variance is a useful tool when
appropriately and consistently applied. To promote consistency, OWEC is developing a training
course for power plant permit writers and others involved in thermal effluent management. The
pilot workshop is to be held in Region II in the second quarter of FY 1993. A guidance document
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also is under development and will be available in draft form by October 1993. The workshops
and guidance document will address the first five recommendations made above. The sixth has
been placed on selection list for guidelines review, update, and reissuance.
Additional recommendations for EPA guidance relate to clarifying EPA's interpretation of
the CWA. Specifically whether and how Section 316(a) variances should consider impingement
and entrainment factors. Permits Division staff also believe that a clearer interpretation of what
"cost reasonableness" level is intended for Section 316(b) would be helpful.
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BIBLIOGRAPHY
Division of Water Quality, Bureau of Water Quality Management, Commonwealth of
Pennsylvania Department of Environmental Resources, "Staff Guidance for Implementation of
Temperature Criteria," October 1989.
Gammon, J.R., "Changes in the Fish Community in the Wabash River Following Power
Plant Start Up: Projected and Observed." Aquatic Toxicology and Hazard Assessment: Sixth
Symposium. ASTM STP 802, W.E. Bishop, R.D. Cardwell, and B.B. Heidolph, Eds., American
Society for Testing and Materials, Philadelphia, 1983, pp. 350-366.
Office of Water Regulations and Standards, U.S. Environmental Protection Agency,
"Quality Criteria for Water 1986," EPA 440/5-86-001, May 1, 1986.
U.S. Environmental Protection Agency, Office of Water Enforcement, Permits Division,
Industrial Permits Branch, Washington, D.C., "Interagency 316(a) Technical Guidance Manual and
Guide for Thermal Effects Sections of Nuclear Facilities Environmental Impact Statements," May
1, 1977.
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Attachment A
BRUNNER ISLAND REVIEW
Description of the Plant and its Operations
Brunner Island Power Plant is a coal fired steam electric station located at Brunner Island,
York County, Pennsylvania. It is operated by Pennsylvania Power and Light (PP&L). The
Brunner Island facility takes in approximately 744 million gallons per day of water from the
Susquehanna River. The river water is pumped to the condenser through tubing to cool steam
coming out of the turbines. The water is chlorinated prior to use to remove contaminants (e.g.,
algae, dissolved solids) and to reduce fouling of the facility mechanisms by algae and deposits.
The condensed steam is recirculated; the heated water is returned to the Susquehanna. The
schematic on the following page details the processes at a coal fired electric plant.
The facility consists of three units, Units 1, 2, and 3, built in 1958, 1961, and 1969,
respectively. The Brunner Island facility is typical of many older facilities in that it uses "once
through cooling," which means the river water is pumped in to the condenser cool the turbines,
then pumped out as soon as cooling is completed. The facility returns the water to its source,
unlike other facilities that discharge water after cooling into a water body different from the source.
By discharging to the source, the facility avoids many of the problems that could occur otherwise
(e.g., augmented flow, introduction of non-indigenous species, draw down of source water body).
During shutdowns the amount of water entering and leaving the condenser is restricted.
The residence time of the water in the condenser is thus longer to ensure the cooling water will
remain at a more constant temperature even though the plant is generating less heat. This is the
Thermal Shock Prevention System, or "fish comfort system," used to avoid sudden or large
fluctuations of temperature in the discharge channel.
If the temperature differential across the condenser becomes too great, plant equipment
can be damaged. Under these circumstances, the fish comfort system is removed resulting in
increased draw of river water into the condenser and discharge of unheated water into the
channel. The unheated water may serve to greatly decrease the temperature of the water in the
channel/river interface. The discharge channel at Brunner Island, unlike other facilities in the
review, does not have controls to prevent fish from entering or amassing at the channel/river
junction (where the fish are at greater risk to temperature fluctuations and high temperatures).
Units 1, 2, and 3 share a common discharge channel. Because Unit 3 produces as much
discharge as Units 1 and 2 combined, the reduced flow from Unit 3 during shutdown allows the
flows from Units 1 and 2 to fill the entire channel. The cross over causes the remaining flow on
the Unit 3 side of the channel to equilibrate to the temperature of the crossover flow. The
equilibration could be either an increase or decrease in temperature on the Unit 3 side of the
channel depending on the direction of the temperature differentials between the two discharges.
Thus, a shutdown of Unit 3 can have a significantly higher impact on the receiving stream than
the removal of either Units 1 or 2 alone.
A-1
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A-2
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Facility File Review
The Brunner Island facility file review consisted of examining PP&L's facility history file
kept by the PA DER in Harrisburg, Pennsylvania, and documents on file at EPA. Documents
reviewed included Discharge Monitoring Reports (DMRs), violation reports, enforcement action
files, and inspection reports. There have been citizen complaints about river water temperatures
downstream from the Brunner Island plant, Including one in August 1989. Reportedly, the water
a great distance from the power plant had at times been hot enough to prevent wading, and
several dead fish had been observed.
The file review revealed that Brunner Island Power Plant had no DMR violations of its
thermal limitations in the last 2 years. Further review of permit and discharge information has
shown the plant to be in compliance with the thermal limitation, which is expressed as a heat
rejection rate in the facility's permit. The current rejection heat permit limitation was established
as part of a Section 316(a) thermal variance In 1977. It is unclear whether PP&L was required
to submit operating data to support continuation of the variance at the time of permit reissuance;
the permit expires September 30,1990, but has been extended to 1992. The permit for Brunner
Island facility sets a limit on the BTU per hour the plant may discharge. The permit also requires
the facility to monitor its discharge temperatures. There are no limitations per se on the maximum
and minimum temperatures that may be discharged, or the deviation in temperature from the
ambient water temperature. (There also is no requirement that the facility conduct biosampling,
although it has since 1981.)
The permit limitation of 6,960 x 106 BTU per hour for the facility is more than double the
rate that EPA calculated (2,690 x 106 BTU/hour) based on the Pennsylvania WQS. The
commonwealth's WQS equates to not more than a 5° F rise above ambient temperature
measured above the intake pump on the lowest 7 days (continuous) flow in 10 years. For the
Susquehanna River, this is 2,400 cubic feet per second (i.e., 7Q10 of 2400 CFS). The heat
rejection rates reported at the facility for April and May 1989 were 6,290 x 106 BTU per hour and
6,225 x 106 BTU per hour respectively. While these rates are within the permit limitation, they
far exceed those that the Pennsylvania WQS have dictated.
The commonwealth files contained reports of two fish kills, one each in January 1990 and
January 1988. (There were reports of other incidents unrelated to thermal loadings (i.e., sulfuric
acid spill, oil spills)). On file were the inspection reports detailing the follow-up inspections due
to the fish kills as well as the recommended and performed enforcement activity. As a result of
the January 1990 fish kill in which several hundred fish died, the commonwealth imposed a fine
of $1,000. (The fish that died included a few hundred gizzard shad, numerous sunfish, and a few
carp, catfish, crappie, and fall fish). In the January 1988 fish kill, approximately 180 fish died.
At that time, the commonwealth issued a letter of agreement without penalty to the facility.
Commonwealth files also indicate that there were two fish kills in 1985. During the first,
in November 1985, two to three thousand gizzard shad died. The facility agreed to a $100
voluntary civil settlement. PA DER made no assessment against the facility. The second fish
kill occurred in December 1985. The facility staff attributed the second fish kill to a controlled shut
down of the plant initiated due to a tube leak.
A-3
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Fish Kills
The Brunner Island facility staff provided additional information on the fish kills. The
January 1990 fish kill was due to a boiler tube failure in Unit 3. Unit 3 was brought out of service
in a controlled shutdown to one-third of the unit's output. The "fish comfort system" kicked-in and
reduced the flow from the plant to avoid a sudden pass through of unheated river water.
However, at one-third load, the temperature differential across Unit 3 was too great to continue
with a controlled shutdown without critical damage to the plant, and the staff removed the comfort
control system from operation. Subsequently, unheated river water passed through the plant and
into the discharge channel.
The shutdown of Unit 3 resulted in a 30° F increase over an hour in the discharge channel
as flows from Units 1 and 2 overran the Unit 3 decreased discharge,, A sudden drop in
temperature (15°F in approximately 10 minutes) occurred in the channel when the comfort system
was removed. The facility staff interviewed suspected the fish kill to be from the sudden decrease
in temperature, and not the initial increase.
According to facility staff, the January 1988 fish kill was due to a "cold shock" as a result
of decreased flow from the plant during shutdown of Unit 3 and the undertow of the river water
back up the discharge channel. This resulted in a 29° F drop over 10 minutes in the channel
A total of 180 fish were counted as dead, including several carp, bass, red horse suckers, and
blue gills. One researcher noted an increase in the diversity of fish species, and an increase in
carp, and attributed this in part to the elimination of Talapia (an introduced species of fish that had
been intentionally removed). As noted earlier, there are no controls preventing fish from entering
the discharge channel, thus exposing the fish to the potential variations of temperature.
The staff attributed the December 1985 fish kill to a tube leak in the reheater section on
Unit 3. They attempted to maintain a 5 megawatt per minute drop in load, but ended with a 6
megawatt per minute drop. The target drop rate was based on their experience that a 5
megawatt per minute drop rate maintains less than a 10° F drop. The facility staff reported that
the ambient river temperature being lower than expected (in addition to the greater drop) possibly
was a factor in the large decrease in temperature. Adjustments in procedures were to include
a check of ambient river temperature and adjust the rate drop accordingly,, (It is not clear how
this was factored into the 1988 and 1990 fish kills).
The staff said controlled shutdowns are preferred over a "trip" (i.e., an automatic
emergency shutdown of the unit) for safety and environmental reasons. On a "trip" the
temperature in the discharge channel actually increases because of the influence of the
discharges from Units 1 and 2. The facility has had an average shutdown rate of 13 per year
There were six shutdowns in November and December of 1985 due to tube leaks.
When EPA asked why fish kills appear to occur only in winter, the facility staff explained
that the fish are not present at the outfall in the warm months. The comfort range of the fish is
such that in the spring, summer, and fall months, they congregate in the deeper, cooler waters
of the river and during the winter stay within the thermal plume. Accordingly, there are no fish
present to be affected by thermal fluctuations in the warmer months.
In addition, there appears to be a correlation between fish kills and Unit 3 problems
Because Unit 3 discharges as much effluent as Units 1 and 2 combined, a problem with Unit 3
causes a greater impact than a shutdown of either of the other two units
A-4
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At the time of this site visit, there had been no recent fish kills, and there were no signs
of problems. A second site visit, later in August, allowed EPA to take a closer look at the
environmental impacts. These are discussed in the next sections.
Biosampling (see schematic, page A-6)
Every August, in coordination with PA DER staff, the Brunner Island facility environmental
staff samples for aquatic life impacts. Late August is selected because it is assumed to be the
worst case scenario (i.e., lowest water level and the hottest water). The staff sampled at eight
locations, including above the intake, at the POD, and 2 1/2 miles below the POD. Sampling is
conducted for fish, macroinvertebrate larval and nymph stages, and water quality (dissolved
oxygen, temperature, conductivity, and pH). The sampling has occurred every year since 1981.
The study results and data are available from the plant.
The biosampling is important because, in addition to fish kills, thermal discharges have
been known to cause other detrimental effects to fish such as: increased levels of infections and
poor body condition, reduced population size, and reduced species diversity. Without
biosampling, nonlethal effects of thermal discharges cannot be adequately assessed.
EPA participated in the August 1990 biosampling of two of the eight sampling locations.
The first was on the Susquehanna River about 5 Vz miles downstream from the thermal discharge
on the east side of the river opposite the thermal plume (Station 6). The second was at the
junction of the thermal discharge channel with the Susquehanna River (Station 3). Results of the
sampling are described below.
Station 6 Biosamplinq
The flow of the river on August 28, the day of the sampling, was about two feet above the
normal August flow. This resulted in lower than normal numbers of fish caught in that part of the
river. (Sampling conducted later in the week was closer to the expected numbers for August).
The staff collected fish via electro-shock and netting procedures. The vast majority of the fish
were two-inch long shiners, though the staff also caught a few channel catfish, carp, bass, and
sunfish. The fish all appeared to be in good health with no obvious signs of disease or infection
(i.e., no sores or lesions). For fish over two inches, the staff identified, measured, and weighed
them in the field and returned them to the river (The weight and length of the fish are used to
calculate body condition). The staff bottled and preserved the smaller fish for later identification.
Macroinvertebrates were collected by disturbing the substrate and collecting the wash in
a small mesh seine. The macroinvertebrates collected were typically species found in past
sampling (i.e., mayflies, caddisflies, mosquito larvae, hymenoptera). These samples were bottled
and preserved for later identification and enumeration. The water temperature at Station 6 was
75° F.
Station 3 Biosampling
The fish collection at Station 3 was significantly different from that of Station 6. According
to facility staff, Station 3 routinely demonstrates the lowest diversity and numbers of fish and
macroinvertebrates as it is the most highly impacted by the thermal discharge of the eight
sampling stations. The fish that were collected were almost exclusively shiners and mosquitofish,
as well as a few small sunfish and bass. The staff did not catch any catfish or cod. Some of the
fish were dead, though it could not be determined if they had died due to the thermal effluent or
A-5
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Brunner Is.
Steam Electric Station
LANCASTER
COUNTY
YORK
COUNTY
Location of sampling stations relative
to Brunner Is. SES and its discharges
A-6
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from entrainment through the plant's cooling water system. The large fish were identified,
measured, weighed, and returned to the river. The smaller fish were bottled and preserved for
later identification.
The macroinvertebrate sampling at Station 3 uncovered only two insects, both mayflies,
one of which was dead. The samples were bottled and preserved for later identification and more
thorough examination. The water temperature at Station 3 was 96° F. The rocks and sediments
at this station were covered by a thick (0.5 cm) spongy and slick growth of algae. There also was
some discolored foam near the shoreline. (The water in this area is fairly turbulent and foam
would be expected.)
Conclusions on Biosamplina
The sampling methods and locations are appropriate to meet the company's goals: Year-
to-year comparison of river flows, locations of thermal plume, numbers and diversity of fish and
macroinvertebrates, and fitness of fish. The sampling is not necessarily rigorous enough,
however, to demonstrate "no adverse effects" or "irreparable harm" as no sampling of aquatic
vegetation takes place, and fish and macroinvertebrate sampling is only performed once a year.
The fish from Station 6 were robust and in good health. Those from Station 3 did not
appear as well off nor were there as many or in as great diversity. The difference in numbers is
to be expected, given the hotter water temperatures; in the summer months, most fish seek the
cooler, deeper regions of the river. The fish that were dead (Station 3) were not kept to
determine the possible cause of death.
The macroinvertebrate population at Station 6 was significantly greater and more diverse
than at Station 3. Station 3 has high turbulence, hotter temperatures, and algae growths that
interfere with the development of macroinvertebrate populations.
Miscellaneous Observations
Facility staff was not aware of "hot pockets" in the receiving waters, but acknowledged the
thermal plume extended downstream at least 6 miles, hugging the right bank (although it
occasionally moved depending on flow and weather conditions). The staff members were not
aware of thermal stress on the fish, although they indicated that other PP&L plants had thermal
stress problems.
The staff members were questioned on how they believe the plant impacts the local and
downstream environment and if they believe the York Haven Hydrological Plant and the Three
.Mile Island Nuclear Power Facility (both just up the river) may be causing impacts for which PP&L
was or could be held accountable. The staff responded that the original impact analysis
(performed in 1979 and 1980) of the variance required no impact more than 5 miles downstream
and believe that depending on the river flow for the year, little or no impact was observed at 2 1/2
miles downstream from the discharge point. They noted no visible drawdown of the river due to
the plant's use of the water.
None of the staff believed the upstream facilities mentioned caused problems for which
PP&L was or could be held responsible. They did mention that the York Hydrological Plant
occasionally had an impact on PP&L's ability to draw from the river. When York restocks its
reservoir, a drawdown is apparent. This impact is not severe and is temporary, as the reservoir
capacity is very limited.
A-7
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Attachment B
TRIP REPORT FOR MARY REILEY
BIOSAMPLING
PENNSYLVANIA POWER AND LIGHT
BRUNNER ISLAND STEAM ELECTRIC
AUGUST 12-16, 1991
Background: In response to a citizens complaint in the fall of 1989 that the heated effluent from the
Pennsylvania Power and Light Co.'s (PP&L) Brunner Island Steam Electric Plant was too
hot to wade in for fishing and that cooked crayfish could be found, OWEC launched an
investigation into the thermal limits, variances, and mixing zones placed upon steam
electric plants. One result of the investigation was a review of the Brunner Island
compliance file at the Pennsylvania DER and an informational meeting with the plant's
management.
During the meeting, Ed Davis and Bob Domermouth (of Brunner Island and PP&L
respectively) spoke of the company's annual biosampling on the Susquehanna River to
asses the effects of the thermal effluent on the river. Bob Domermouth invited me to join
the sampling team last year and called this past spring to ask if I would like to participate
again.
Lav of the Land: (see attached schematic in Appendix A, page A-6)
The Brunner Island facility is located about 10 miles north of York, PA. The segment of the river
it discharges to is two miles wide and divided down the center by a chain of islands approximately
five miles long. The chain separates the deeper channel on the east side of the river from the
shallower on the west and effectively creates a barrier between the thermal plume and cool east
waters should the plume extend towards the river's center. The river bottom is almost entirely
bedrock, either outcroppings or covered in stones and heavy gravel; some slower moving areas
are silty.
The river's water level was extremely low (not much over the 7Q10 which is 2400 cfs) providing
a prime opportunity to investigate the effects of the thermal discharge under the low flow conditions
anticipated at permit issuance. The plume extended across approximately two-thirds of the west
side of the river for atleast four miles. Previous studies at extremely low flows found impact similar
to those at station seven as much as five and one-half miles downstream.
Sampling Methods: (see attached schematic in Appendix A, page A-6)
There are eight sampling stations in the annual study: one is a reference station above the thermal
discharge at Conewago Creek; two is also a reference station above the thermal discharge on the
west bank of the river at the discharge from the facilities sanitary waste treatment pond; station
three has the highest impact as it is located at the end of the thermal discharge channel; station
six is the outfall of ashbasin six; stations 5A and 5B are on the west side of the river downstream
from the thermal discharge, under normal flows this is an impacted area; station seven is between
two islands located one-third of the way across the river, downstream from the thermal discharge
and is mildly impacted; and station eight is on the east bank of the river, downstream from the
thermal discharge but not impacted by the thermal dischage.
Water Quality
Water quality parameters were sampled for all stations: DO (range 6-10), pH (approx 8)
Temperature (range 26° - 42°C), Conductivity, metal and non-metal contaminants.
B-1
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Vertebrates
Fish were collected at all sampling stations except station 6 (the outfall of ashbasin six not a
natural stream). Fish were captured using electroshock and nets. Collection started downstream
of the sampling area and worked upstream. «""«>weam
Recreational species and those more than four centimeters in length were weighed measured
examined or external peculiarities, and released. Those fish less than four centirnSers were
preserved for later identification and examination (primarily shiners). ^numeiers were
Examples of fish caught and environment (not all inclusive):
Cooler Waters Warmer Waters
Quill-Back Shiners
ne!L°^ ^ Sunfish (Redbreast, Green)
Catfish (Yellow, Brown, Channel) Catfish (Yellow, Brown)
Bass (Rock, Large/Smallmouth) Smallmouth Bass
Sunfish (Redbreast, Green) Common Carp
Gizzard Shad
Minnows
Shiners
Suckers
Pumpkinseed
S£nlflS!nt ^erence between the co°'er and warmer water was the numbers of fish
rt h^H f3" ' f6 tyPf , C°'der WaterS had si9nificant|V more fish than warmer waters
th Hh f 6W 'f any fiSh Present Station 5B and 7 also had significantly lower number
than did the reference stations and station 5A which received reverse flow. numoers
Invertebrates
!^L7^ra^ (insehct ,la'vae' P"Pae- worms. chironomids, bivalves, snails, beatles, etc.) were
collected at all stations but station six. The macroinvertebrates were captured in the riffle areas
by tacking up the substrate and collecting the loose substrate and organisms i^a fine mesh dtonet
placed ^mediately downstream of the disturbed area. All invertebrates were preserved for late
ud cation- Depth and flow for the riffle areas « — «»id .5
Examples of macroinvertebrates collected and environment (not all inclusive):
Cooler Waters Warmer Waters
KRjffl® B,eatles Dominated by Chironomids
Mayfly Larvae Riff|e Beat(es
Bivalves Water Pennies
Snails
Chironomids
Water Pennies
anden^
nothing was collected. The most significant difference between impact and reference £ tons was
*™*™
rerence ns was
° ^ S™ *™*™
B-2
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Field Evaluation:
The final report of this years sampling will not be available for several months. Reid observations
lead me to believe that the impact of Brunner Island Steam Electric's thermal discharge on the
Susquehanna River is local and not irreparable. If the plant were to shut down today, the lateral
and upstream migration of organisms into the previously impacted area would be relatively quick.
This is exemplified in stations 5A and 5B.
During normal flow years stations 5A and 5B are thermally impacted. This year the river flow was
extremely low allowing a split flow of cold water from ash basin six; half of the flow traveled back
upstream through station 5A and hugging the west side of station 5B. The fish and
macroinvertebrate populations in these areas were very different from last year. Though the
invertebrate population was still dominated by chironomids, a strong showing of less tolerant
species was present. The areas also supported the cooler fish species.
There is little to nothing present at station three, the end of the thermal discharge channel, all life
has vacated for the summer to cooler climates (sounds like August in D.C.).
Potential Concerns not Investigated:
There is a possibility that some species, i.e. bass, are spawning just upstream from the PP&L plant
and below the York Haven Hydroelectric plant (there is a dam at this point with no passage for
fish). The eggs may float downstream and be caught either in the cool water intake or in the plants
thermal plume. The effect of this (if there is any) on potential recruitment of these species is
unknown.
Other:
Brunner Island had a cold shock kill this past January 1991. It was not a large kill, approx. 200
fish, but it has prompted the facility to take further procedural and potentially technological steps
to eliminated the cold shock kills. The facility recently completed a study of all fish kills that have
occurred at the plant since 1977. The results demonstrate that since the fish comfort system was
put in place on Unit 3 the number, frequency, and severity of fish kills has dropped significantly.
The facility has since adopted some additional protective procedures and is considering installing
a comfort system for both Units 1 and 2 as well. The station anticipates these measures will
eliminate all future kills excepting those that result from severe emergency shutdowns. Bob
Domermouth will send me a copy of their study and new procedures.
B-3
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