APRIL 1970
GENERAL SITE CHARACTERISTICS
and
BASIC DATA NEEDS
for
THERMAL POWER PLANT SITE EVALUATION
United States Department of the Interior
Federal Water Pollution Control Administration
Northwest Region
Portland, Oregon
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GENERAL SITE CHARACTERISTICS AND
BASIC DATA NEEDS FOR
THERMAL POWER PLANT SITE EVALUATION
INTRODUCTION
Thermal power plant siting in the Northwest to date has lacked
adequate consideration of aquatic environmental aspects. Typically,
site safety and economics have been primary considerations. The
Federal Water Pollution Control Administration (FWPCA) considers that
aquatic environmental aspects are equally important and that the
absence of adequate and definitive guidelines has been largely re-
sponsible for this lack of consideration. Therefore, early coordina-
tion of power plant siting studies with State and Federal regulatory
agencies is an urgent necessity.
This document describes those data which are necessary for sat-
isfactory evaluation of selected power plant sites, relative to
applicable Water Quality Standards and FWPCA policy statements on
thermal power plant siting. It is presumed that the needed data
will be provided and evaluated by the power company(ies) with re-
spect to effects on the aquatic environment in their site selection
report. Associated field studies will include at least two years
of measurements acceptable to FWPCA.
Where available data and/or techniques are inadequate to de-
fine the impact of power plant operation upon the aquatic environ-
ment, it is presumed that waste discharge permit decisions will
favor protection of the environment.
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Development of these guidelines Is based upon the following
general site characteristics which are prerequisite to the protection
of the aquatic environment and water resource users:
1. Marine sites considered by the power company(ies) must be
separated from major shellfish areas and fish migration routes by a
sufficient distance to avoid adverse effects.
2. Applicable Water Quality Standards must be complied with.
Outfall dilution zones, beyond which temperatures are less than 0.5° F,
above ambient, must not adversely influence confined fish migration
routes.
3. Adequate depth must be available so that power plant in-
takes do not adversely endanger aquatic organisms near the water
surface.
4. The area of concern referred to in the following outline
is defined as an area of at least a five-mile radius from the power
plant intake/outfall.
PRELIMINARY SITE EVALUATION DATA NEEDS
1. Marine Power Plant Sites
The following data will be necessary for evaluation of
coastal and estuary sites:
A. Power Plant Data
(1) Specific location of the site.
(2) Description of other important water uses within
the area of concern; but at least within five miles of the power
plant site.
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(3) Generating capacity (initial and ultimate); pro-
jected power generation schedules for representative years over the
expected life of the project.
(4) Fuel and thermal efficiency.
(5) Cooling water requirements for alternate modes of
waste heat treatment.
(6) Recommendations on specific power plant intake/
outfall design and location; also, recommendations on screening and
fish by-pass facilities, cooling water pump types and sizes, and
condenser cooling line sizes.
(7) Mode of waste heat treatment. Information should
be presented to show that potential avenues for waste heat utiliza-
tion have been seriously considered.
(8) Mode of fouling control in the intake/outfall con-
duits and the condenser cooling water lines.
(9) Characteristics and methods of handling and dis-
posal for general plant wastes other than condenser cooling water.
B. Physical Oceanographic Data
The utilities are expected to calculate the mixing
characteristics of discharges from the power plant outfall(s) and
present the data, methods of calculation, and results in their pre-
liminary site selection report.
(1) Determinations of surface area and total volume
of water affected by outfall discharge, within which temperatures
are at least 0.5° F. higher than ambient water temperatures. Also,
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determinations of the mass transport of the warm water field with
time (viz., flushing characteristics).
These calculations will be made for critical conditions
of tides, slack current conditions, weather, and possible influence
of fresh water flows.
(2) Bottom contours (depth below MLLW) within five miles
of the probable power plant intake/outfall locations.
(3) Tidal characteristics, daily and seasonally (i.e.,
ranges of depth with time).
(4) Ambient currents within the area of concern:
(a) direction and strength of the current as functions of time, tides,
offshore currents, wind conditions, and possible influence of fresh
water flows; (b) occurrence and duration of periods of minimum current
speed; (c) occurrence and duration of periods of upwelling.
(5) Ambient water temperatures within five miles of
the power plant intake/outfall. In developing these data, it is
important to note that the Water Quality Standards for coastal waters
apply at least to the three-mile limit and to the entire water column.
The dispersion, or dilution zone is excepted, from the numerical
criteria, but only after the waste has received adequate treatment
and has been provided with satisfactory initial dispersion.
Specifically, surface isotherm maps, accurate to at
least 1° F., are needed and should define temperature changes diurnally
and seasonally. Temperature profiles are needed at one-half mile
grid intervals within the five-mile study area, and should define
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variations with time. Finally, a continuous record of temperature is
needed for one profile near the proposed power plant outfall. It is
expected that these continuous records will show the influence of
nearshore current movement, upwelling, and other phenomena of mass
water transport on water temperatures at a point.
(6) Salinity profiles are also needed at one-half mile
intervals to complete evaluation of receiving water density character-
istics with time.
C. Meteorological Data
The following continuous records will be required at
the plant site for correlation with long term regional data: wind
speed and direction, air temperature, dewpoint, and solar radiation.
D. Biological Data
Since the Water Quality Standards for coastal waters
were developed largely upon the need for preservation of marine
organisms, careful documentation of the receiving water biota is
essential.
(1) An inventory of pelagic and benthic organisms
identified at least to genera is required within five miles of the
nuclear thermal power plant intake/outfall. Emphasis should be
placed on pelagic organisms and results presented in terms of esti-
mated percent distribution and relative abundance of the important
genera. These data should be taken to describe vertical and horizon-
tal distribution and should coincide with general location of planned
intake and outfall structures.
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(2) The distribution and time of residency of migratory
or transient species and forms (age of development—clam larvae)
should be identified as a distinct part of the inventory.
(3) Survey periods will be required to coincide with
the four main quarters of the biologic year in order to ascertain and
assess the free-swimming periods of the more important organisms.
Sampling conditions shall include the various represen-
tative physical, chemical, and biological conditions which are known
to exist during each quarter.
(4) After species determination has been accomplished,
demonstrate that the installation and operation of the proposed plant
will have no adverse effects on the described aquatic biota.
2. Fresh Water Sites
It is presumed that complete offstream cooling will be
provided at all fresh water thermal power plant sites. However, it
is recognized that other treated plant wastes may be discharged and
that certain operation modes may result in short-term heat discharges;
therefore, the following data will be necessary for evaluation of
thermal power plant sites on fresh water streams and impoundments.
A. Power Plant Data
(1) Specific location of the site.
(2) Description of other important water uses within
the area of concern.
(3) Initial and ultimate generating capacity and pro-
posed plan of power generation.
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(4) Fuel and thermal efficiency.
(5) Cooling water requirements and mode of waste heat
treatment.
(6) Power plant intake and outfall locations with
recommendations for design of intake screening facility.
(7) Treatment requirements for plant make-up water and
modes of treatment and disposal for plant waste waters.
(8) Mode of fouling control in the intake conduit and
the waste heat treatment facility.
B. Physical Data
(1) Meteorological data for the plant site. The following
continuous records will be required at the plant site over a period of
two years, for correlation with long-term regional data: wind speed,
and direction, air temperature, dewpoint, and solar radiation.
(2) Stream cross-sections, at one-mile intervals, from
five miles upstream to fifteen miles downstream of the power plant
site. Impoundment contours, where applicable, at five-foot vertical
intervals.
(3) Hydrographs of daily stream flows for median and
ten-year recurring low-flow years; also representative patterns of
diurnal variation where the stream flow is subjected to regulation
and/or tidal effects. These flows should be estimated for probable
future flow regulation conditions in the years 1980 and 2000.
(4) Continuous water temperature records over a period
of two years at the power plant site, five miles upstream, and fifteen
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8
miles downstream. Special temperature surveys should be conducted to
determine the presence and extent of temperature gradients affected
by flow regulation, tides, or other causes. Thermographs in impound-
ments should be placed at the plant site, mouths of major tributaries,
and other selected points to establish the general temperature pattern
for a period of two years.
C. Chemical Data
Chemical water quality surveys should be conducted every
three months with cross-sectional samples taken at the plant site,
five miles upstream and fifteen miles downstream. Samples should be
collected at the surface and at ten-foot intervals over the water
column in impoundments at stations located at one-half mile intervals
within the study area. Analyses included should define: (1) needs
for plant makeup water treatment requirements; (2) impact, relative to
Water Quality Standards, of radioactive, chemical, thermal, sanitary,
and miscellaneous plant waste discharges.
D. Biological Data
Again, careful documentation of the receiving water
biota is essential, since the Water Quality Standards were developed
to protect this resource.
(1) Description of the proximity of the power plant
site to major fish migration routes.
(2) Inventory and seasonal occurrence of resident and
migratory fish within five miles upstream and downstream of the intake/
outfall lines.
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(3) Inventory and seasonal occurrence of the principal
plankters present at the power plant site.
PRE-CONSTRUCTION AND OPERATIONAL MONITORING STUDIES
The above site selection information will be used as the basis
for a decision on site approval. This approval represents the opinion
that the site characteristics are amenable to protection of the aquatic
environment and compliance with Water Quality Standards. The purpose
of the pre-construction and operational monitoring studies is to
facilitate final waste treatment, intake and outfall design, and to
document aquatic environmental effects of the operating plant. The
general format of these studies will be similar to the preliminary
studies, but will emphasize specific data needed for plant design
decisions.
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