ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
REMOTE SENSING STUDY
OF
ELECTRIC GENERATING STATION THERMAL DISCHARGES
TO
BARNEGAT BAY AND GREAT EGG HARBOR
NEW JERSEY
NATIONAL FIELD INVESTIGATIONS CENTER-DENVER
DENVER, COLORADO
AND
REGION II NEW YORK, NEW YORK ^tosr^
SEPTEMBER 1973
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ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
REMOTE SENSING STUDY
OF
ELECTRIC GENERATING STATION THERMAL DISCHARGES
TO
BARNEGAT BAY AND GREAT EGG HARBOR
NEW JERSEY
NATIONAL FIELD INVESTIGATIONS CENTER-DENVER
DENVER, COLORADO .
and
REGION II
NEW YORK, NEW YORK
SEPTEMBER 1973
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TABLE OF CONTENTS
LIST OF TABLES
• Page
iii
LISTOFFIGURES .
4 4 4 4 • 4 4
iii
GLOSSARYOFTERMS .
INTRODUCTION . . . . .
S S S S S
S S S S S S S
1
II
SUMMARY AND CONCLUSIONS
BARNEGATBAY
GREAT EGG HARBOR BAY
2
2
. . . . . .• 4
Barnegat Bay . . . . .
Great Egg Harbor Bay.
DESCRIPTION OF POWER PLANTS
Oyster Creek Nuclear Generating
B. L. England Generating Station
APPLICABLE WATER QUALITY STANDARDS AND
PROPOSED EFFLUENT GUIDELINES
RESULTS AND EVALUATION OF THERMAL DATA ANALYSIS
BARNEGATBAY
Environmental Conditions at Time of Flight
Thermal Plume Characteristics.
Comparison of Observed and
Allowable Water Temperatures
GREATEGGHAR3ORBAY
Environmental Conditions at Time of Flight
Thermal Plume Characteristics
Comparison of Observed and
Allowable Water Temperatures
iv
BACKGROUND INFORMATION
DESCRIPTION OF STUDY AREAS
III
IV
V
S S S S 5 4 5 5
S S S S S S S
Station
6
6
6
8
. . . . 11
S 5 5 5 11
12
• S S S S 13
. . . . 16
16
16
• . . . 18
• . . . 19
21
STUDY TECHNIQUES FOR THERMAL DISCHA1tGES
AIRCRAFT AND FLIGHT DATA
SENSORDATA
GROUNDTRUTH
DATA INTERPRETATION AND ANALYSIS . .
ERROR ANALYSIS
23
23
23
25
30
32
32
S 33
35
REFERENCES
38
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LIST OF TABLES
Table No . , Page
V—l PREDICTED TIDE CoNDITIONS—BARNFr AT BAY’
13 JULY 1973 . ‘ 24
V—2 WEATHER CONDITIONS, 13 JULY 1973 25
V— ’3 PREDICTED TIDE CONDITIONS—GREAT EGG HARBOR BAY
13 JULY 1973. 32
LIST OF FIGURES
Follows
Figure No. Page
1 Location Map 6
2 Central Barnegat Bay 6
3 Great Egg Harbor Bay . 8
4 Aircraft Sensor ‘Locations 16,
5 IRLS Optical Collection System 17
6 Thermal Field Oyster Creek Power Plant
‘(High Altitude) ‘ ‘ ‘ 26
7 Isothermal Map of the Oyster Creek’
Thermal Field ‘ 26
8 Thermal Field Oyster Creek Power’ Plant
(Low Altitude) ‘ 28
9 Isothermal Map of the Oyster Creek
Thermal Discharge , ‘29
10 Elevation Profile of Barnegat Bay 29
11 Temperature Profile of Oyster Creek 30
12 Thermal Nap Great Egg Harbor
B. L. England Generating Station ( ow Altitude) 33
13 Isothermal Map of the B. L. England Power Plant
Thermal Field ‘
14 Thermal Map Great Egg Harbor (High Altitude) 35
15 Isothermal Map of Great Egg Harbor 35
iii
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GLOSSARY OF TEENS
cfs — Flow rate given in cubic feet per second
= 0.0283 cubic meters per. second or
28.3 liters per second
cm Length in centimeters 0.3937 in. or 0.03281 ft.
gpm — Flow rate in.gallons per minute = 0.0631 liters
per second
km — Distance in kilometers = 0.621 miles
km 2 — Area in square kilometers = 100 hectares or.
0.3861 square miles
knot — Velocity in nautical miles per hour’= 1.15 statute
miles per.hr = 1.845 kilometers per hour
1 — Volume in liters 0.2642 gallons
m — Length in meters = 3.281 feet or 1.094 yards
M — Mega, a prefix, for million i0 6
in 3 tday — Flow rate in cubic meters per day
= 0.000264 millIon gallons per.. day
m 3 /sec — F].ow rate in cubic meters per see
= 22.8 million gallons per day
= 35.3 cubic feet per see
mgd — Flow rate in million gallons per day
3,785 cubic meters per day
imn — Length in millimeters =0.1 centimeter
ppm . — Concentration given in parts per million parts
— Temperature in degrees Centigrade = 5/9 (°F—32)
OF . — Temperature in degrees Farenheit
iv
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1. INTRODUCTION
An aerial remote sensinR study of thermal discharges to New Jersey
coastal waters from two large thermal—electric generating stations was
conducted on 13 July 1973. The study was undertaken at the request of
the Surveillance arid Analysis Division, Region II, Environmental Protection
Agency, New York, New York.
The study encompassed the Great Egg Harbor Bay and the central
portion of Barnegat Bay. Thermal discharges evaluated were from the
Oyster Creek Nuclear Generating Station operated by Jersey Central
Power and Light Company on Barnegat Bay and the B. L. England Generating
Station on Great Egg Harbor Bay. Infrared imagery of the •study areas
was obtained using infrared line scanners mounted in high—performance
reconnaissance airáraft. This Imagery along with ground truth water
temperature data was used to characterize the observed thermal fields
or plumes. Water temperatures were evaluated with respect to applicable
water quality standards.
The results of this study will be used in the preparation of
Environmental Impact Statements for the two Bays and the subsequent
drafting of thermal discharge permits for the two power generating
facilities.
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II , SUMMARY AND CONCLUSIONS
Airborne thermal infrared sensors were used to record the
characteristics of thermal discharges froni the Oyster Creek Nuclear
Generating Station and the B.L. England Generating Station on 13 July
1973, a period .f peak power demand and high receiving water temper-
atures. Ground truth In the form of surface water temperatures at
various points in the thermal plumes was obtained by field crews at
the time of flight.
Isothermal maps depicting areas of equal surface water temperature
were prepared from the Infrared Imagery. Actual temperatures of the
Isotherms were determined from the ground truth data. The isothermal
maps characterized the behavior of the thermal plume under known hydro-
logic and tidal conditions. Evaluations of the observed thermal plumes
with respect to applicable water quality criteria were made and violations
defined. Results of the investigation of each study area are summarized
below.
BARNEGAT BAY
1. The Oyster Cree.k Nuclear Generating Station is a nuclear fueled,
thermal—electric power plant operated by the Jersey Central Power and
Light Company. With a generating capacity of 620 megawatts, the facility
began full—scale operation in 1970. Suimnertime cooling water use is about
29 m 3 /sec (1,020 cfs or 660 ingd). Heated cooling water is discharged to
Oyster Creek about 3.2 km (2 ml) upstream of Barnegat Bay and is conveyed
to the Bay by the Creek.
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2. Barnegat Bay is a shallow enhayment paralleling the New Jersey
coastline. At the mouth of Oyster Creek the Bay is about 7 km (4 ml)
wide. Much of the Bay is shallow (less than 1 in deep) with nid-bay
depths averaging 2 to 4 in (7 to 13 ft). The tidal range is small,
less than 0.2 in (0.6 ft).
3. The observed thermal field in Barnegat Bay extended from the
mouth of Oyster Creek to Island Beach, the full width of the Bay. Surface
water temperatures in the Bay ranged from ambient receiving water temper—
atures of 23.5°C (74.3°F) to a peak of 28.1°C (82.5°F) at the mouth of
Oyster Creek. The thermal field extending completely across the Bay
was more than 0.8°C (1.5°F) above ambient temperatures. This represents
a point of non—compliance with the proposed effluent guidelines that
limit water temperatures more than 0.8°C above ambient to less than
two—thirds of the surface area at any cross—section.
4. Oyster Creek has not been designated a a mixing zone. Surface
water temperatures in thŕ Creek ran8ed from 29 .0°C (84.0°F) to 31°C
(88°F). The surface temperature of Oyster Creek from the cooling water
discharge point downstream for about 310 i n (1,020 ft) exceeded the
29.4°C (85°F) maximum limit specified by the New Jersey Water fluality
Standards. It is probable that essentially the entire flow in Oyster
Creek was coolingwater. Therefore, the entire strearnf low had a temper-
ature far in excess of an 0.8°C rise above ambient temperature. Such a
temperature rise would be limited to less than 25 percent of the cross !
sectional area of the strein by the general effluent guidelines. Oyster
Creek was thus not in compliance with this proposed limitation.
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GREAT EGG HARBOR BAY
1. The B. L. England Generating Station is a fossil fueled,
thermal—electric power plant operated by the Atlantic City Electric
Company. With a generating capacity of 29.0 megawatts, the facility
has been in operation since 1962. Cooling.water use averages about
12.4 m 3 /sec (435 cfs or 282 mgd) with heated water discharged directly
to Great Egg Harbor Bay.
2. Great Egg Harbor Bay is an. estuary of the Great Egg Harbor
and Tuckahoe Rivers. The Bay is about 10 km (6 mi) long with an average
width of 2 to 3 km (lto 2 mi). Much of the Bay is shallow with depths
less than 1 m but channel depths as great as 11 m (35 ft) occur. The
tidal range is large, averaging l.2m (3.8 ft).
3. Under ebb tide conditions, the thermal plume in Great Egg Harbor
Bay, created by the B. L. England cooling water discharge, moved in an
easterly direction along the southshore of the Bay, and then turned in
a northeasterly direction at Golders Point near the mouth of Peck Bay.
This plume movement was influenced by ebb tide currents in both Great
Egg Harbor Bay and Peck Bay. Different plume characteristics would be
expected under flood tide conditions.
4. Surface water temperatures in the thermal plume in Great Egg
Harbor Bay ranged from 22.8°C (73°F) (ambient) to a maximum of 29.4°C
(85°F). The maximum temperature limit (29.4°C) specified by the New Jersey
Water Quality Standards was exceeded only at the discharge point. At
cross—sections across Great Egg Harbor Bay east of the Garden State
Parkway Bridge and across the entrance of Peck Bay, nore than two—thirds
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of the surface water was heated to a temperature exceeding 0.8°C above
ambient n disagreement with the proposed general guideline.
5. This study has shown that remote sensing techniques could be
implemented into a compliance monitoring program to quickly and cost
effectively ascertain the real time behavior of thermal discharges and
the resultant thermal plumes. A procedure could readily be developed
to apply the aerial thermal data to each discharge to document compliance
or noncompliance with water quality standards and to evaluate the effec—
tiveness of proposed effluent (thermal) guidelines.
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III. BACKGROUND INFORMATION
DESCRIPTION OF STUDY AREAS
This study encompassed the estuarine waters of Barnegat Bay and
Great Egg Harbor Bay on the Atlanticcoast of New Jersey (Figure 1].
Although similar in climatic conditions and general locations with
respect to the Atlantic Ocean, the two study areas have significant
differences in physical, tidal and hydrólogiŕ characteristics as
discussed in the following sections.
Barnegat
Located about 50 km (31 mi) NNE of Atlantic City, in Ocean County,
Barnegat Bay is a long, narrow embayment paralleling the New Jersey
coastline [ Figure 2]. Extending from Toms River on the north to
Manahawkin Bay on the south, a distance of about 30 km (19 mi), the
Bay has a width ranging from about 3 to 7 km (2 to 4 nd). About one—
third of the Bay is very shallow (less than 1 in depth) with depths
greater than 4 m occurring only in the narrow channels leading to
Barnegat Inlet, the narrow opening connecting the Bay with the Atlantic
Ocean. ‘Mid—Bay depths in the area of interest average 2 to 4 in
(7 to 13 ft).
Two types of topography surround the Bay. On the ocean side
narrow, sandy barrier islands separate the estuarine and ocean waters.
Island Beach is to the north of Barnegat Inlet and Long Beach to the
south. Barnegat Inlet is the only break in the barrier islands along
64 kin (40 nd) of coastline.
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Figure . Location Map
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Inland the Bay is bordered by tidal marshes, tidal streams and
lowlands. Much of the marsh land has been dredged to form marinas and
housing developments located on canals. In addition, navigation
channels have been dredged in the mouths of several of the streams.
The Intracoastal Waterway traverses the length of the flay.
Streams entering the Bay are small and freshwater inflow is minor
(less than 28 m 3 /sec or 1000 cfs) relative to tidal interchange from
the ocean. In the area of Barnegat Bay considered in this study, the
Forked River and Oyster Creek are the two streams of interest. Oyster
Creek has a drainage area of less than 34 sq km (13 sq wi) and an
average annual flow around 1.7 m 3 fsec (60 cfs). Flow is relatively
uniform throughout the year with highest runoff occuring during late
winter and low flow at mid—sumner.
The Forked River, formed by the confluence of the North and South
Branches near its t vuth, has a drainage area estimated to be about
104 sq km (40 sq ml). Flow records are not available but the average
annual flow should be in the range of 2.3 to 4.5m 3 /sec (80 to 160 cfs).
Tidal information is available for two locations in the vicinity;
Barnegat Inlet and Oyster CreekChannel off Sedge Island. The Barnegat
Inlet station reflects Open ocean conditions. Tides are semi—diurnal
with a mean range of 1.0 m (3.1 ft) and a range during spring tides of
1.2 m (3.8 It).
The effect of the narrow Barnegat Inleton tides in Barnegat Bay
is reflected by tidal conditions in the Oyster Creek Channel. Tides
at Sedge Island about 3 km inside the inlet lag about 2 hr 36 mm behind
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open ocean tides. The tidal range is reduced to only about 0.2 m
(0.6 ft). The llKUth of Oyster Creek is located almost 3 km (2 ml)
directly across the Bay from Oyster Creek Channel. Tides at the
mouth of Oyster Creek would thus be expected to have a similar range
as at Oyster Creek Channel and lag a few minutes behind.
Wind conditions affect the tides in the Bay and may add to or
reduce the normal lunar tide range.
The average annual air temperature at Toms River located about
13 km (8 mi) north of Oyster Creek 18 11°C (52°F). Average monthly
air ‘temperatures range from —1°C (31°F) in February to 24°C (75°F)
in July. Temperature extremes are moderated by proximity to both
Barnegat Bay and the Atlantic Ocean. Record temperature extremes
range from a low of —16°C (3°F) to a high of 35°C (95°F). Proximity
to marshes and open water areas results in high relative humidity
most of ‘the year.
Great Harbor
In contrast to Barnegat Bay, the Great Egg Harbor Bay is a typical
estuary with significant freshwater Inflow for its size and with a large
inlet to the ocean. These conditions produce substantially different
tidal and hydrological characteristics than at Barnegat Bay.
Great Egg Harbor Bay, the drowned mouth of the Great Egg Harbor
River, is located about 15km (10 xni) southwest of Atlantic City
[ Figure 3). The Bay extends inland from Great Egg Harbor Inlet about
10 km (6 mi) with an average width of 2 to 3 km (1 to 2 m l). At the
coastline the Inlet is about 1.6 km (1.0 ml) wide narrowing to 1 km
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inside the Bay. Peck Bay, a shallow embaymen.t with an average width
of 0.8 km (0.5 ml) extends about 3 km(2m1) off the south side of the
Bay. A series of islands divide the Bay into narrow channels about
one—third of its length inland from the Ocean.
Water depths in much of Great Egg Harbor Bay and Peck Bay are
less than 1 m (3 ft). In the submerged stream channels and channels
between islands, however, tidal currents have scoured areas as deep
as 11 m (35 ft).
Topography surrounding the Bay is similar to the Barnegat Bay area
with the exception that this area is more highly developed. Ocean City 0
with a population of 11,000, is located on a peninsula south of Great
Egg Harbor Inlet that separates Peck Bay and central Great Egg Harbor
Bay from the Atlantic Ocean.
Several natural channels connect the Bay system with other coastal
bays. The Intracoastal Waterway traverses PeckBay and the north end
of Great Egg Harbor Bay.
Freshwater inflow to the estuary is provided by Great Egg Harbor
River, Tuckahoe River, Patcong Creek, Middle River, and ntnnerous minor
tidal tributaries. The Great Egg Harbor River is the largest stream
with an estimated drainage area of about 910 sq km (347 sq ml). Average
annual streaniflow is about 14.7 m 3 /sec (520 cf s). Average monthly
discharges vary from a high in February and March to a low in July
with a high—low ratio of about 4:1.
The Tuckahoe River has an estimated drainage area of about 310 sq 1cm
(102 sq mi) and an average annual flow of about 4.0 m 3 /sec (140 cfs).
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Flow variations are similar to the Great Egg Harbor River. Patcong
Creek and Middle River provide only minor freshwater inf low.
Tidal information is available for a number of locations in
the Bay. As a result of the large inlet tO theocean, differences in
average tidal ranges between points in the Bay are small and approxi-
mate open ocean conditions. At Great Egg Harbor Inlet the mean and
spring tide range are 1.2 m (3.8 ft) and 1.4 m (4.6 ft) respectively.
Corresponding tide ranges In Great Egg Har or Bay near the confluence
of the Great Egg Harbor and Tuckahoe Rivers are 1.1 m (3.6 ft) and
l.3m (4.4ft). Lag time for tidal changes is small with high water
and low water occuring 32 and 62 minutes later, respectively, at the
Bay station in comparison to the Inlet station. Tidal effects extend
up the Tuckahoe River for several km and more than 25 km up the Great
Egg Harbor River. At Mays Landing (20 km upstream from the mouth) tides
in the Great Egg Harbor River have a mean range, of 1.2 m (4.0 ft) and
lag about 2 1/2 hr behind tide changes at Great Egg Harbor Inlet. Tides
in both rivers and upper reaches of the Bay are affected by flood flows
in the rivers.
Climatic conditions are similar to those at Barnegat Bay. At
Atlantic City, about 15 l a n (10 m l) NE of Great Egg Harbor Bay, the
average annual air ‘temperature is about 12°C (54°F) with mean monthly
temperatures ranging from, 3°C (37°F) in January to 23°C (73°F) in
July. Record temperatures’ range from —12°C (11°F) to 34°C (93°F).
Relative humidity is high much of the year.
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DESCRIPTION OF POW1 R PLANTS
Oyster Creek Nuclear Generating Station
Locatedon Barnegat Bay [ Figure 2], this thermal—electric power
plant, a nuclear fueledfacility, is operated by Jer8ey Central Power and
Light Company to provide base power generation for the Northeast energy
market. Plant operation began in late 1969 wIth intermittent trial
operations continuing through most of 1970. Full—scale operation was
initiated during the Winter of 1970—1971. Generating capacity is about
620 megawatts.
The plant has a once—through cooling water system with the water
supply obtained from the South Branch of the Forked River. Summertime
cooling water use is about 29 m 3 /sec (1,020 cfs or 660 mgd). The intake
point is located about 2.5 km (1.6 mi) upstream frol the confluence of
the North and South Branches of the Forked River and about 4 km (2.5 mi)
upstream from Barnegat Bay. South Branch is tidal at the Intake point.
Average freshwater inflow to the Forked River at its mouth Is about
7 to 17 per-cent of summer cooling water use. Durlngnorinal and low
streamf low conditions in the Forked River, the cooling water supply is
primarily saline Bay water. Only during high runoff stages does the
water supply become primarily freshwater.
Heated cooling water is discharged to Oyster Creek about 3.2 km
(2 ml) upstream from Barnegat Bay. As average freshwater flow in
Oyster Creek is about 1.7 m 3 /sec (60 cfs), except for high runoff
stages, the natural streamfiow provides little cooling or dilution
of salinity of the cooling water flow. Oyster Creek serves as a canal
•to convey the cooling water to Barnegat Bay.
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B. L. England Generating Station
This fossil fuel (coal and crude oil) burning thermal—electric
power plant, located on the south shore of Great. Egg Harbor Bay [ Figure 3],
is operated by the Atlantic City Electric Company. . Plant operation began
in 1962. The plant has two generating units with the total capacity of
about 290 megawatts.
The plant uses water from Great Egg Harbor Bay for once—through
cooling purposes, returning the heated water to the Bay near the intake
point. . A narrow (25 m) channel conveys the discharge about 80 m (260 ft)
offshore.
A Refuse Act Permit Program application (Application No. 2SD—OXO-
3—000432) was filed for the plant in June l97l. ’ The application indi-
cates that the plant has a total of 11 wastewater discharges. Nine of
the discharges, including boiler blowdown, intake screen washdown, boiler
slag sluicewater, and other miscellaneous small. wastestreams, total only
0.13 m 3 /sec (3 mgd). Cooling water use for Unit No. 1 averages 3..7 m 3 fsec
(85 mgd) with a range of 2.8 to 5.5m 3 /sec (63 to 126 mgd). .For Unit
No. 2, cooling water use averages 4.5 1n 3 /sec (102 mgd) with a maximum
of 6.7 rn 3 /sec (153 mgd). Total water use for the plant under summer
conditions reaches a maximum of 12.4 in 3 fsec. (282 mgd or 435 cfs).
Average Bay water intake temperatures range from 4°C (40°F) in the
Winter to 24°C (75°F) in the Summer)’ Under summer conditions, cooling
water discharge temperatures range from 24°C (.75°F) to a maximum of 38°C
(100°F) with an average of 29°C (85°F). Comparable winter temperatures
are a range of 12°C (53°F) to 24°C (75°F) with an average of 16°C (60°F).
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Maximum temperatures as high as 48°C (119°F) were reported for the
miscellaneous waste streams but the volume of flow is minor.
APPLICABLE WATER QUALITY STANDAIU)S AND PROPOSED EFFLUENT GUIDELINES
New Jersey adoptedwater quality standards for coastal waters under
provisions of the Water Quality Act of 1965. These standards include
criteria that limit changes In the temperature of receiving waters
induced ‘by thermal discharges. ’
Barnegat Bay and Great Egg Harbor are classified Class T —1 which
are tidal waters approved as sources of public, potable water supply.
These waters are to be suitable for shellfish harvesting where permitted.
These waters are also to be suitable for the maintenances migration and
propagation of the natural and established biota, and for primary con-
tact recreation, industrial and agricultural water supply; and any
other reasonable uses.
The existing temperature criteria for Class TW—l waters are:’
“No heat may be added except in designated mixing zones,
which would cause temperatures to exceed 85°F (29.4°C),
or which will cause the monthly mean of the maximum daily
temperature at any site, prior to the addition of any heat,
to be exceeded by more than 4°F (2.2°C) during September
through May, or more than 1.5°F (0.8°C) during June through
August. The rate of temperature change in designated ‘mixing
zones shall not cause mortality of the biota.”. -’
Mixing zones are defined as localized areas of surface waters Into
which wastewater effluents, including heat, may be discharged for the
purpose of mixing,- dispersing, or dissipating such wastewater without
creating nuisance or hazardous conditions. ‘ It is specified in the
Water Quality Criteria that ‘the mixing zones may be designated by the
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New Jersey Department of Environmental Protection. Presently, New
Jersey’s existing standards contain no written guidelines for the
designation, of mixing zones.
In early 1973, effluent guidelines were proposed that would
cause the above—quoted criteria to read as follows:
“No heat may be added, except in designated mixing zones,
which would cause temperatures to exceed ‘85°F (29.4°C),
or which would cause the monthly mean of the maximum daily
temperature at any site, prior to the addition of heat to
be increased by more than 4°F (2.2°C) during September
through May, or to be increased by more than 1.5°F (0.8°C)
during June through August. The rate of temperature change
in desi ated mixing zones shall not cause mortality of the
biota.”—’
In addition to these temperature criteria, the following
general guidelines have been ‘proposed for the establishment of
“mixing zones” and”zones-of—passage”:
“ Mixing Zones:.. . .the total area and/or volume of a body
of water assigned to mixing zones shall be limited to that
which will not interfere with biological communities or
populations of important species to a degree which is damaging
to the ecosystem nor diminish other beneficial uses dispro-
portionately.”
“ Zones of Passage:...in....estuaries and coastal waters, zones
of passage are considered to be continuous water routes of
the volume, area and quality necessary to allow passage of
free—swimming and drifing organisms with no ign1ficant
effects produced on their populations. These,zones must be
provided wherever mixing zones are allowed.”. .’
Specifically for “thermal mixing zones” the following guide-
line has been proposed:
“ Thermal Mixing Zones : As a guideline..., thermal mixing
zones shall be limited to no more than 1/4 of the cross—
sectional area and/or volume of the flow of stream or
estuary, leaving at least 3/4 free as a zone of passage,
including a minimum of 1/3 of the surface nmeasqred from
shore to shore’at any stage of tide or flow.”. !
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The numerical limits were derived from recommendations of the
National Technical Advisory Conmiittee (NTAC) report on water quality
criteria. The intent of the-NTAC recommendations was to maintain
water temperatures below maximum limits detrimental to aquatic life.
The temperature—rise limits were designed to control the allowable
heat load discharged to a given body of water while allowing normal
daily and seasonal temperature fluctuations to occur. The percentage
of the, cross—sectional area of the receiving water with elevated tem-
peratures was limited to provide for zones of passage so that migra—
ting or drifing aquatic life and organisms could pass without being
blocked or killed by a thermal. barrier. ,
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IV. STUDY TECHNIQUES FOR THERMAL DISCHARGES
AIRCRAFT AND FLIGHT DATA
This remote sensing mission was carried out by two high performance
aircraft specifically designed and equipped for aerial reconnaissance
work. The two aircraft independently flew each target area to provide
primary and backup coverage. Both aircraft carried the sensors discus—
sed below.
The flight parameter data listed below provide the specific values
of the aerial reconnaissance variables.
Date of Flight: 13 July 1973
Time of Flight: 1100 to 1300 Hours EDT
Target Areas : Central Barnegat Bay, Great Egg Harbor Bay
Air Speed of Flight: 660 to 740 km/hr (360 to 400 knots)
Aircraft Altitude Above Water Level: 915 ni (3000 ft)
and 1830 in (6000 ft)
Sensors Used: Infrared Line Scanner
SENSOR DATA
An AN/AAS —18 Infrared Line Scanner (IRLS) was the sensor used
for this study. The sensor is located on the underside of the air-
craft as shown in Figure 4. While in operation, it images an area
along the flight path of the aircraft. The width of the imaged area
is dependent upon aircraft altitude and is encompassed by a 1200
field—of—view in cross—track or perpendicular to the flight path
(shown below).
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1 KS-81 FRAMING CAMERAS
2 INFRARED LINE SCANNER
Figure 4. Aircraft Sensor Locations
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17
Field—of—View of the IRLS
An IRLS’ converts variations in infrared energy emissions from
objects of different temperatures into a thermal map. The three basic
parts of an IRLS are the scanner optics, a detector array, and a
recording unit. The scanner optics collect the infrared emissions
from ground and water areas and focus them on the detectors [ Figure 5].
‘The detectors, cryogenically cooled to 26° Kelvin, convert the
infrared energy collected by the scanner optics into an electronic
signal. This signal is processed electronically and subsequently
transformed into visible light through a cathode ray tube. This light
is then recorded on ordinary RAR black—and—white film measuring 12.6 cm
(5 in.) in width. The recorded thermal map is 10 cm (4 in,.) wide and
Its length depends upon the, length of a particular line of flight being
Imaged.,
The LRLS has a sensitivity bandwidth from 8 to 14 microns, the so
called thermal band of the electromagnetic spectrum. Applying Wien’s
— S — S — S —
AIRCRAFT
A I. T IT U 0 E
GROUND LEVEL
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Detector
Folding M irror
Folding Mirror
Incident Infrared. Energy
Folding Mirror
Folding Mirror
Figure 5. IRIS Optical Collection System
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18
Displacement Law, this represents a temperature band from —66°C to
89°C. The system has an instantaneous field—of—view of 1 miuliradian
by 1 milliradian. The total field of view is achieved by the rotating
mirror in the optical collection system, which is 120° by 1 milliradian.
The measured noise equivalent temperature (N,E.T.) of the IRLS is
0.32°C with 100 percent probability of target detection. This represents
an effective measurement of the temperature resolution of the system.
GROUND TRUTH
The Surveillance and Analysis Division, Region II, EPA., obtained
ground truth, in the form of near—surface water temperatures, simul—
taneousi.y with the time—of—flight. The water temperature data was
measured at discrete points along straight line transects. In the case
of Barnegat Bay, two transects were made extending in northeasterly
and southeasterly directions from the mouth of OysterCreek. The
northeasterly transect had three data points and the southeasterly
transect contained eleven discrete data points. Three surface water
temperatures were also obtained from within Oyster Creek..
Two linear transects were also made in Great Egg Harbor Bay. The
main transect extended in a north northeasterly direction from the éf—
fluent point of the B. L. England Generating Station. It contained
eight discrete data points at which surface water temperatures were
taken. The second transect was symetrically perpendicular to and
intersected the first about 340 rn (1100 ft) into the Harbor. It con—
tamed six discrete data points.
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19
The accuracy of the contact instrumentation used to obtain the
• 5/
surface water temperatures was ± 0.1 C.— It Is estimated that the
precise location of the -discrete water—temperature data points was
known to within ± 30 meters.
DATA INTERPRETATION AND ANALYSIS
All data interpretations and analyses ‘were carried out on the
original black and white film negative used to record the Infrared
data aboard the aircraft. Photographic prints, were not, used because
of the added errors of an additional image generation.
Each thermal plume image or map, associated with the two power
plant discharges under study, was plotted with respect to US Department
of Commerce Nautical Charts (Scale 1:40,000) to determine the infrared
image scale. To evaluate consistency this scale was compared to the
empirical scale derived from the effective focal length of the IRLS
and the altitude.of the aircraft above water level. The respective
image scale Is included on each thermal map in this report.
In the black—and—white IRLS film, temperature levels are represented
by various shades of gray in the negative format or rendition. Areas of
low density (clear film) represent cooler temperatures and as the
temperature of a particular target becomes warmer the density of gray
in the film also increases. Positive prints presented In this report
reflect the reverse of the negative film. Cool areas are dark while
the warm areas are light gray.
A Spatial Data 704 Image Analyzer was used to convert the infrared
images into isothermal maps. Isothermal maps delineate areas with the
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20
same temperature (iaotherTns). The Image Analyzer uses a technique called
density slicing to divide the density range on a given infrared image
into 12 increments. Each increment thus represents a particular density
of gray on the image and a narrow temperature range closely approxi-
mating an isotherm. The density value of each increment is accurate
to within 0.03 density units over a range of 0 to 2 (density). Each
density increment Is displayedon the Image Analyzer screen in a
particular color. Anisothermal map was prepared by tracing directly
from the color rendition on the Analyzer display screen.
The actual temperature of each isothermal, area on -the map was
determinédby first comparing it with a physical plot of the water
temperature data obtained in’the field at flight time. Each density
value or increment represents a particular water temperature. These
are derived from calibration curves obtained empirically from the gray
density, levels on the negative corresponding to the locations at which
the ground truth water temperatures were taken ‘at the time of flight.
These curves were used to interpolate temperatures for isothermsin
areas where no ground truth data points were located. They covered a
rather large temperature differential (6 to 8°C orlO to 14°F) between
the power plant effluents and the background or ambient receiving waters.
From the calibration curves the absolute temperature of each isotherm
(colored increment) delineated by the Image Analyzer was thus determined.
An Important factor must be mentioned at this point. The IRIS
will only record water surface temperatures since water is opaque in
this region of the infrared spectrum. The maximum depth penetration
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21
in either fresh or salt water is 0.01 cm. Therefore, a submerged
thermal discharge can be detected from an aircraft with an IRLS only
if the the warm wastewater reaches the surface of the receiving body
of water. The isothermal maps developed by this study thus represent
surface temperatures only and may not necessarily reflect subsurface
temperature distributions.
ERROR ANALYSIS
Limitations can be placed on the accuracy or uncertainty of the
absolute value of water temperatures represented by the isothermal
maps developed.by this study. The three significant sources of error
affecting the data are the resolution of the IRLS, the accuracy of the
Image Analyzer, and the accuracy of the instrumentation used in obtaining
ground truth. These sources have the following error values:
(1) t 1 = = +0.32°C (measured system M.E.T.)
(2) t t = t +O.10 0 C (film density accuracy)
2 Image Analyzer —
(3) t t = L t = +0.10°C (accuracy of instrument)
3 ground truth Inst. —.
By using the method of root—sum-squares, the magnitude of the total
possible error range can be estimated as follows:
1
3 2
± (At ) 2 ] V V
ii 1
= ± [ (0.32)2 +. (0.10)2 + (0.l0)2]2
= +0.35°C (+0.63°F) V
The reported temperature values are thus accurate to within
± 0.35°C (0.63°F).
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22
No atmospheric corrections were applied to these thermal data under
the assumption that the atmospheric effect was constant and would not
induce a significant effect since the film was directly calibrated by
the water temperatures measured during the time of flight. Any influence
of the air column between the aircraft and the water surface would be
taken into account by the calibration process, assuming a constancy of
the entire air column in the target area.
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V. RESULTS AND EVALUATION OF THERMAL DATA ANALYStS
This section presents the results of the analysis of the temper-
ature data obtained by aerial reconnaissance and ground surveys. Tidal
conditions, weather and streanflow conditions existing at the time of
flight are summarized and the behavior of the thermal plumes evaluated
with respect to these conditions. Observed temperature conditions are
compared to applicable water quality standards and violations of these
standards are described.
BABNEGAT BAY
The Oyster Creek Nuclear Generating Station discharges cooling
water to Oyster Creek about 3 km (2 ml) above its mouth [ Figure 2].
The Creek cânveys the heated water to Barnegat Bay where it disperses.
The resultant thermal plume extends over a significant portion of
central Barnegat Bay between the mouth of Oyster Creek and Barnegat
Inlet. The entire area affected by the thermal plume was investigated
on 13 July 1973.
Environmental. Conditions at Time of Flight
Predicted tide conditions for Barnegat Inlet and Oyster Creek
Channel are shown In Table V—1. -’ Actual tide conditions were not
measured but prevailing weather conditions and the low tide range in
Barnegat Bay would indicate that actual tide conditions were very
close to predicted levels. The Oyster Creek Channel tide station is
located about 3 km (2 ml) directly across the Bay from the mouth of
Oyster Creek. Tide levels at the mouth of Oyster Creek would be
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expected to be almost identical to the Oyster Creek Channel station
with a slight time lag..
TABLE V-i
PREDICTED TIDE CONDITIONS—BARNEGAT BAY
13 JULY 1973
Location Time EDT Tide Level Tide
Meters Feet
Barnegat Inlet 0050 .0.1 0.3 Low Low
0650 0.8 2.5 Low High
1250 0.2 0.5 High Low
1912 1.1 3.7 HIgh High
Oyster Creek Channel 0328 0.0 0.0 Low Low
(Of f Sedge Island) 0926 0.2 0.5 Low High
1528 <0.1 0.1 High Low
2148 0.7 0.7 High High
Tides at the Oyster Creek Channel lag about 2.6 hr behind tide
changes at Barnegat Inlet. At the time of flight the tide at Barnegat
Inlet was 1 to 2 hr from high—low tide in the ‘ebb phase with a water
height difference of about —0.5 m (—1.6 ft) (referenced to L I I Tide).
In.like manner, the tide at the Oyster Creek Channel was 3.5 to 4 hr
from high—low tide in the ebb phase with a water height difference of
about —0.05 m (—0.15 ft) representing a nearly static condition in
Barnegat Bay.
Weather conditions at the time of flight at selected nearby stations
are summarized in Table V—2:
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TABLE V-2
WEATHER CONDITIONS - 13 JULY 197321
Parava ter Atlantic City Newark Toins River
Air Temperature 27°C (80°F) 26°C (78°F) 24°C (75F)
Relative Humidity 46% 50% —
Wind Speed & 22—37 km/hr 17—26 kin/hr —
Direction 12—20 knots, SW) (9—14 knots, SW)
Precipitation 0 0 0
Oyster Creek and central Barnegat Bay are approximately midway between
Atlantic City and Newark and are 13 km (8 mi) south ofToms River. As
the wind was blowing from the southwest at both wind stations during the
mission with an average velocity of 20 km/hr (11 knots), it is reasonable
to assume that these weatherconditiońs prevailed in the target area at
the time of flight.
Estimates of streamfiow prepared by the U.S. Geological Survey
indicate flow in Oyster Creek exclusive of the power plant discharge
was about 1.6 m 3 /sec (55 cfs) on 13 Ju1y. ’ Streamfiow in the Forked
River near its mouth (exclusive of power plant intake flows) was estimated
at 1.1 m 3 /sec (38 cfs). In comparison to cooling water use of 28 m 3 /sec
(1,000 cfs), these flows were minor. Less than six percent of the out-
flow from Oyster Creek was freshwater streamfiow. Less than four percent.
of the water supply obtained from the Forked River was freshwater stream—
f low indicating the cooling water discharge would be essentially the same
alinity as Bay water.
Thermal Plume Characteristics
As discussed in Chapter IV, thermal maps were made of central
Barnegat Bay from two different altitudes, 915 and 1,830 m (3,000 and
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26
6,000 f.t) above water level. The higher altitude map provides the
greatest areal coverage while u re detail was obtained by the lower
altitude flight.
A thermal map showing the location of the Oyster Creek Nuclear
Generating Station, Oyster Creek, and the thermal plume in Barnegat
Bay is shown in Figure 6. This map is a positive print of infrared
imagery recorded at the 1,830 in altitude and has an approximate scale
of 1:63,000. As this is a positive image, dark areas are cool and the
very light gray or white areas are quite warm. Note that the domain
of Oyster Creek is quite warm as depicted by the light gray color.
The thermal plume resulting from the outflow from Oyster Creek extends
in an eastward direction. The thermal plume disperses very little in
the first third of the distance, across Barnegat Bay. ili the remaining
two thirds of the distance, the plume appears to disperse quite quickly.
With the aid of this thermal map and the ground”truth obtained at the
time of flight, the thermal field was analyzed for areas. of equal
temperature and an isothermal map prepared [ Figure 7]. [ Analytical
techniques are discussed in Chapter IV ).
Areas of constant temperature (isotherms) are depicted by a
particular color on the isothermal, map. The color scheme goes from
red, representing the warmest temperature to the orange, yellow,
greens, and Into the bluesthat represent the coolest temperatures.
Water temperatures corresponding to each isotherm (color) are shown In
the legend. This isothermal map has 12 temperature gradient steps
ranging from the red’ or warmest area at the.mouth of Oyster Creek
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27
(labeled No. 1) with a temperature of 28.1°C (82.5°F) to the signifi—”
cantly cooler blue ambient or background receiving water areas (labeled
No. 12) with a temperature of 23.5°C (74.3°F).
Temperature differences between most isotherms in Figure 7 are
0.4°C (0.7°F). Thi8 temperature interval is well within the resolution
capability of the infrared line scanner, recalling that -its noise equi-
valent temperature is 0.32°C with 100 percent probability of detection.
The differences in temperature between steps 3 and 4, 9 and 10, and
ii. and 12, are not 0.4°C. This could be due’to the fact that the temper-
ature of the water at the particular grou td truth sample location
(located -within 15 cm of the water surface)- was slightly different from -
that of the very thin layer of the surface water. A second possibility
is that a ‘slight temperature, change occurred during the short time -
interval between some ground truth measurements and the recording of
the infrared image as not all ground n asurements could be made simul-
taneously. The effect’ is that the particular shade of gray in the film,
representing the missing 0.4°C steps, was not present.
The observed thermal pattern [ Figure 7] is quite complex. The
warmest area is at the mouth of Oyster Creek where the power plant ef—
fluent enters the Bay. A warm plume extends from this point eastward
across Barnegat Bay. In addition there are three other areas (shown -
by yellow and green patches) where the water is considerably warmer
than ambient receiving water temperatures, the blue areas in the thermal
field. It is believed that this spotted effect may be the result of a
superposition of internal waves n the Bay and wind currents to create -
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a psuedo upwelling in these areas, thus bringing warmer near—surface
waters to the top.
On the day of the flight the prevailing wind was out of the south-
west nearly paralleling the west shoreline of Barnegat Bay. Under these
conditions, with only a slight offshore wind component, the thermal ef-
fects of the power plant effluent extended completely across the Bay to
Island Beach. An offshore wind (west or northwest) would be expected to
push the plume further offshore while an onshore wind (easterly) would
hold the heated water closer to the western shore and dispersing in a
southerly direction. Likewise, a north or south wind would tend to hold
the plume closer to the we8tern shore.
The low streamfiow present in Oyster Creek on 13 July would have
essentially no effect on th thermal plume. At high runoff stages the
creek flow would be expected to exert only minor effects on plume pat-
terns owing to the small stream size.
Tidal conditions in Barnegat Bay were nearly static for severaL
hours before the time of flight. Tidal conditions thus exerted little
influence on the observed thermal plume. Owing to the constricting ef-
fect of Barnegat Inlet and the low tide range in Barnegat Bay, little
translation of the plume location should occur between flood andebb
tide stages.
A thermal map was• also obtained by a lower altitude (915 m or
3,000 ft above water level) flight to provide greater detail in the main
thermal plume area. A positive print tFigure 8) of the infrared image
obtained at this altitude shows a thermal pattern very similar to the
higher altitude thermal map [ Figure 6]. The time lapse between the
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29,
recording of the two images was about 10 minutes. An isothermal map
(Figure 9] prepared from the low—altitude infrared Image is also com-
parable to the high—altitude isothermal map [ Figure 7]. The warm area
(yellow/green) near the top of Figure 9 has the same general shape
as the respective warm area in Figure 7 located about one—third the
distance between the mouth of Oyster Creek and Island Beach. The
warmest waters, near the mouth of Oyster Creek, occupy the same area’
in both isothermal maps.
In an attempt to determine the cause of the ‘complex thermal field
observed, •a bottom profile [ Figure 10] was plotted for a line extending
from the mouth of Oyster Creek to Island Beach (between the two arrows
on Figure 7) using water depths obtained from a nautical chart. ’
Except In the navigational channel at the mouth of ‘Oyster Creek, the
waters of Barnegat Bay are less than 2 m (6 ft) deep for a distance
of about 800 rn (2,600 ft) offshore at the Creek mouth. This shallow
water Is in contrast to Oyster Creek channel depths of more than
3 m (10 ft) and Bay areas deeper than 4 m (13 ft). The Oyster Creek
navigation channel hasa constructed. depth of 2 m (6 ft). The rise
in the bottom of the Oyster Creek channel coupled with the spreading
of water out of the channel into shallower Bay areas and the buoyancy
of the warm water would tend to deflect the outflow from Oyster Creek
to the surface as depicted in Figure 10. Internal Bay currents and
wind currents could then distribute this warm water in the general area
beyond the rise’ to form the observed thermal pattern.
The isothermal maps Indicate that the warm water within the thermal
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WATER SURFACE
7
BARNEGAT BAY
cREEK
CHAN N EL
ACROSS BARNEGAT BAY FROM SANDS PT.
*
HARBOR
1
0
1
1000
1
2000
I
3000
I
40
•
00
I
5000
I
6000
DISTANCE IN METERS
Figure 10. Elevation Profile of Barnegat Bay
Lu
Lu
C)
Lu
I-
U )
0
I L-
0
r
I-
0
—
-1 —
-
-2
—
>1
-*
r
U
IC
L u
m
0 ’
z
I C
-J
U)
-3.—
*
I -
7000
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30
plume, at the surface level, was not entering the Forked, River which
the Oyster Creek power plant uses for its source of cooling water.
The various shades of gray observed in Oyster Creek from the
power plant’s discharge to its mouth [ Figure 8] indicate that the
Creek water is very slowly cooling (by heat transfer to the atmosphere’
and dilution) as its progresses toward Barnegat Bay. Around the bend
from the discharge, a small creek (visible by the black or colder water)
is seen emptying into Oyster Creek. A temperature profile [ Figure 11]
of the ‘surface waters in Oyster Creek from the US 9 Bridge to its mouth
was prepared from the thermal map. It is quite different in comparison
to temperatures measured in the Creek by EPA in October 1970 (prior to
plant. operation) and March 1971 (during the initial phase of plant
This difference reflects the combined effects of higher
intake water temperatures in July relative to March and October and a
higher heat load and cooling water discharge under full—scale operations.
Comparison of Observed and Allowable Water Temperatures
Applicable water quality guidelines for New Jersey coastal waters
[ Section III] propose that no more than 25 percent of the vertical cross—
sectional area (a vertical plane passed through the water at a particular
point) of the Bay water may exceed 0.8°C (1.5°F) over ambient (background)
temperature in the summer months of June through August, and 2.2°C
(4.0°F) over ambient the remainder of the No heat may be added,
except in designated mixing zones, which would cause water temperatures,
to exceed 29.4°C (85°F). In addition no u re than two—thirds of the
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U
a ____
28—
— — U — • — • _ — — — a — U — U — U a a a a %tj
IJJ 13 JULY 1973
o .
4 I&l
IL l
24— C)
I-
z
ILl I i i
C) I-
U)
U) . >
ILl 0
ILl
20—
w
I
a I-
0
ILl
— — — a — — — — — — — — — —
1 MARCH .1971
4
I d
.0
Id - -
I .-
12—
‘U
I-
4 4 %
25 OCTOBER. 197Ô
8 —
-I I
0 1000 2000 3000 4000
DISTANCE iN METERS FROM U.S. 9 BRIDGE
Figure 11. Temperature Profile of Oyster Creek
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31
surface water in the vertical cross section, may be heated to the
temperature limits given above.
Recalling that the airborne infrared line scanner can image only
the surface layer of a body of water, only. that portion of the thermal
criteria relating to surface temperatures can be evaluated for Barnegat
Bay. The thermal field in Barnegat Bay extended from Oyster Creek (the
source) to Island Beach, the full width of the Bay. Isotherm No. 9
in Figure 7, with a temperature more than 0.8°C above ambient (Isotherm
No. 12), extends completely across Barnegat Bay from the mouth of Oyster
Creek and covers a surface area of more than 10 sq kin (4 sq ml). This
is not within the limit of the “two—thirds surface t ’ guideline. None of
the areas in Barnegat Bay exceeded the 29.4°C (85°F) maximum limit.
The surface temperature in Oyster Creek, which has not been desig-
nated as a “mixing zone”, exceeded the 0.8°C criterion based upon the
surface, temperature of the ambient water in Barnegat Bay. Since nearly
the entire flow in Oyster Creek was cooling water, it is quite probable
that the entire volume of water in the creek had a temperature much
greater than 0.8°C over ambient. This would not be within the “25 percent”
guideline discussed above. None of the Cre’ek water below the US Hwy 9
Bridge exceeded the ’29.5°C criterion. However upstream of this bridge
and the cool creek, Oyster Creek exceeded the allowable limit. The
surface temperature of the water near the discharge was 31°C (88°F),
dropping to 29.O°C(84°F) immediately above the US HWY 9 Bridge.
Approximately 310 m (1,020 ft) of Oyster Creek from the discharge
downstream, exceeded the 29.4°C maximum limit. This applies only to,
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32
thewater surface due to the opacity of water in the intermediate
infrared band.
GREAT EGG HARBOR BAY
The B. L. England Generating Station discharges cooling water to
the western end of Great Egg Harbor Bay ‘ [ FIgure 3]. The Bay was
Investigated with infrared sensors on 13 July 1973.
Environmental Conditions at Time of Fli _ ght. .
Weather conditions at Atlantic City (about. 15 km or 10 ml northeast)
during the survey are listed in Table V—2 in the previous section on
Barnegat Bay.
Predicted tide conditions for Great Egg Harbor Inlet and, a point
in Great Egg Harbor” Bay near the cooling water discharge location are
summarized in Table V—3. , Actual tide levels were not measured but
wind conditions and streamf low in the Tuckahoe and Great Egg Harbor
Rivers would indicate that normal tide conditions existed.
TABLE V—3
PREDICTED TIDE CONDITIONS — GREAT EGG HARBOR BAY ’
13 JULY 1973
Location Tide (EDT) Tide Level ‘ Tide
Meters Feet
Great Egg Harbor Inlet 0106 0.1 , 0.3 , Low Low
0722 1.0 3.2 Low High
1306 0.2 0 5 High Low
1944 1.3 4.4 High High
Great Egg Harbor Bay 0208 0.1 , 0.3 Low Low
0754 0.9 3.0 Low High.
1408 0.2 . 0.5 High Low
2016 1.3 4.2 High High
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33
Note that, in contrast to Barnegat Bay, tide levels in Great Egg
Harbor Bay very closely approximate tides at the Bay inlet except for
a time lag.
At the time of flight, the tide was in ebb phase at both locations
with the total water level drop (relative to the previous high tide) of
0.8 in (2.7 ft) and 0.7 in (2.5 ft) for the Inlet and Bay, respectively.
Tide currents would thus have been at near peak downstream velocities
during the previous several hours.
Freshwater inflow to the upper end of Great Egg Harbor Bay from
the Tuckahoe’ and Great Egg Harbor Rivers was estimated by the U.S. Geo-
logical Survey to total 17.6 m 3 /sec (620 cfs).!’ 1 Based on the rate of’’
change of the volume of the tidal prism in the Bay, the average flow.
rate through Great Egg Harbor Inlet was estimated to be about 850 in /sec
(30,000 cfs) for the ebb tide phase during the, time of flight. The
freshwater inflow would thus be expected -to ex er.t only minor influences
on water temperature, salinity, and tidal current velocities in the Bay.
These effects would be limited to the upper end of the Bay. During high
runoff conditions in the rivers, more significant effects on the Bay
would result.
Thermal Plume Characteristics -
A thermal map of’ Great Egg Harbor Bay, in the form of a positive
print of the infrared imagery recorded at an altitude of 915 m (3,000 ft),
is shown in Figure 12. Recalling that cool areas are dark and warm water
‘areas are light, the thermal plume resulting from the power plant cooling
water discharge is clearly visible to the west of the parallel bridges
in the left—hand portion of the image.
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Using the ImageAnalyzer, an isothermal map. [ Figure 13] was
prepared for the area covering about the central one—fourth of Figure 12,
the area encompassing most of •the thermal plume. The isothermal map
shows that the thermal plume moves along shore under the parallel bridgeč
in an easterly direction and gradually cools. As the plume reaches the
entrance to Peck Bay at G,olders Point, it deflects In a northerly or
counter clockwise direction and moves toward Great Egg Harbor Inlet. This
pattern of plume movement reflects the combined effects of tidal currents,
wind currents, and advective freshwater inflows. To the west of the
entrance to Peck Bay tidal currents during the ebb phase have a generally
easterly movement. A measurement of surface water movement made at the
time of flight showed water at a point 60 m (200 ft) east of the power
plant discharge was moving parallel to shore in an easterly direction at
a velocity of 0.3 rn/sec (1.0 fps). Freshwater inflows reinforce the
easterly movement during ebb tide. Prevailing winds ŕut of the southwest
would also aid easterly movement. In contrast, tide flows move out of
Peck Bay in a northerly direction during ebb phases. Ti4al currents
from Peck Bay were thus the probable cause of the observed northward
deflection of the plume.
As in the case of the Barnegat Bay isothermal maps, the color
scheme for Figure 13 varies from red for the warmest temperatures to blue
for the coolest. Water temperatures corresponding to each isotherm (color)
are shown in the legend. The warmest temperature observed was 29.4°C
(85°F) while background water temperatures were 22.8°C (73°F). Most of
the area of the plume was about 26.5° to 27°C (79 70 to 80.5°F) (Isotherm
Nos. 5 and 6).
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It can be noted from the legend [ Figure 13] that the temperature.
differentials between isotherms are 0.5°C except between numbers 1
and 2 and numbers 8 and 9. As discussed before for Barnegat Bay, slight
water temperature differentials between surface films and the near sur-
face measurements made on site or slight time lags between ground truth
measurements and recording of infrared imagery might have contributed
to the missing isotherms.
A high—altitude thermal map [ Figure 1.] was prepared from infrared
imagery recorded at an altitude of 1,830 m (6,000 ft). An isothermal
map [ Figure 15] was also prepared. These two high—altitude observations
defined thermal characteristics of the plume similar to the low—altitude
observations. Along shore under the parallel bridges, the thermal plume
was the same for both low and high, level maps. Thermal patterns in
Figure 15 are slightly different, however, in comparison to Figure 13
for areas in the center and right portions of Figure 14 as well as to
the east of the bridges. These differences may be attributable to two
factors: 1) the aircraft altitude was doubled with resultant effects;
on the spatial resolution (unit cell size) recording capability of the
IRLS on .board the aircraft and 2) the time lag of 10 to 12 minutes
between the recording of the low— and high—altitude thermal maps
would allow some minor changes in the plume position to occur.
Con parison of Observed and Allowable Water Temperatures
Applicable water quality standards for Great Egg Harbor Bay specify
the same’ temperature criteria as for Barnegat Bay.
The maximum’ temperature limit of 29.4°C (85°F) was exceeded at only
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36
one point, the red area at the cooling water discharge point [ Figure 13].
All other areas were éooler.
In applying the proposed “two—thirds surface” guideline, a selečtlon
of the cross—sectional area to be evaluated must be made. Three such
cross—sections were selected between Drag Island and the south shore
of Great Egg Harbor Bay. These cross—sections are defined by the pairs
of arrows numbered 1, 2 and 3 in Figure 13. The No. 1 cross section
extends from near the power plant to Drag Island. As the thermal plume
hugs the’ south shore in this area, warm water with temperatures more
than 0.8°C above ambient occupy only 21 percent of the surface distance
between the arrows.’ Although,in the plume the surface temperatures sub-
stantially exceed ambient, the “two—thirds surface” guideline is sat—U
isfied. At cross—section No.’ 2,,the thermal ‘field completely fills the
surface of the Bay from the south shore to Drag Island which is not
within the proposed guidelines. The thermal field also completely ‘fills
the distance along cross—section No. 3 but 28 percent of the distance
is in the blue area (Isotherm No. 9) that is less than 0.8°C above
ambient. The remaining 72 percent of the surface is not within the
‘two—thirds surface” guideline.
‘At slack tide the thermal plume would be ‘expected to extend further
offshore than the observed plume during an ebb tide. ,Thus, non compliance
with the proposed guideline along cross—section No. 1 might also occur.
Flood tide conditions would produce upstream movement of the plume with
unknown effects with respect to the standards.
Examining the mouth of Peck Bay between Shooting Island and
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Golders Point [ Figure 13] it is obvious that the plume completely fills
the surface of this cross—section which is not within the proposed
guideline.
Isotheruis Nos. 5, 6 and 7 [ Figure l3] are substantially above
ambient temperatures. These areas occupy more than 4 sq km (1.5 sq mi)
of central Great Egg Harbor Bay indicating that under ebb tide condi-
tions much of the thermal plume extends into this area. This large
plume may not be within the proposed guideline in this area.
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REFERENCES
1. Environmental Protection Agency, Washington, D.C., Refuse Act
Permit Program computer data files .
2. New Jersey Department of Environmental Protection,Rules and
Regulations Establishing Surface Water Quality Criteria ,
June 1971.
3. Harry L. Allen, Environmental Protection Agency, Region II,
New York, New York. Private Correspondence. New Jersey
thermal criteria applicable to Barnegat. Bay and Great Egg
Harbor. 13 December 1973.
4. Federal Water Pollution Control Administration, Water Quality
Criteria , Report of the National Technical Advisory Committee,
April 1968.
5. F. P. Nixon, Environmental Protection Agency, Region II, New York,
New York. Private Communication. Accuracy of temperature
instrumentation.
6. U. S. Department of Commerce, Tide Tables 1973 , East Coast of
North and South America, 1972.
7. National Oceanic and Atmospheric Administration, Atlantic City
and Newark, New Jersey. Private communication. Weather data
for 13 July 1973.
8. Arthur A. Vickers, U. S. Department of the Interior, Geological
Survey, Trenton, New Jersey. Private correspondence. Estimated
streamfiow for selected New Jersey rivers for 13 July 1973.
9. U. S. Department of Commerce, Nautical Chart 824—SC , Intracoastal
Waterway, Sandy Hook to Little Egg Harbor, New Jersey, Dec. 1970.
10. Environmental Protection Agency, Region II, New York, Nev.York.
Project files.
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