Analysis of three years of complete-field temperature data from different sites of heated surface discharges into Lake Michigan Page: 6 of 58
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charging from two outfalls, each at a 60* angle to the Lake Michigan shore-
line. In total, for the 1971 and 1972 surveys, there are 22 plumes from
Point Beach Plant Unit 1, 12 from the Palisades Plant, two from the Waukegan
Plant, and one from the State Line Plant. The 1973 field-year data dis-
cussed in this paper consists of six Point Beach plumes in which both units
were operating at nearly full power.
The sites chosen represent a significant diversity in discharge de-
signs. Point Beach and Palisades have nearly the same power level with very
similar low densimetric Froude Numbers (Fo = 2.4), yet with significantly
different aspect ratios (outfall width divided by its depth). The Point
Beach outfall has a width-to-depth ratio of 2.5, while at Palisades the
same ratio is 13.5. Consequently, the Palisades plume is discharged as a
longer and more slender sheet of heated water at the surface of the Lake.
The State Line Plant has an even larger aspect ratio of 30.9, with an ex-
tremely low densimetric Froude Number (z 1). This low-velocity discharge
is in contrast to the high-velocity Waukegan discharge, Fo = 9.7; State Line
and Waukegan both have rather large aspect ratios, the Waukegan Plant having
a value of 20.1. The effect on the plume of initial densimetric Froude Num-
ber, aspect ratio, and plant power level will be described in are detail
in the sections analyzing the data from the above sites.
Figures 2-4 illustrate sample surface isotherms from each of the power
plants studied. Examples of plumes from Point Beach with Unit 1 operational
and then both units operational are given in Fig. 2.
The three-dimensional .temperature data obtained in 1972 and 1973 were
acquired using a 5.5-m cathedral-hull fiberglass boat traveling in a serpen-
tine path from the outfall to the far expanses of the plume. A submerged
boom was attached to the boat's gunwhale to which six thermistors were
fastened at 0.5-m intervals to 3 m. A surface float with a similar thermis-
tor attached was used to measure surface temperature.
Analog information proportional to temperature from these seven Yellow
Springs Instruments Type 709 linearized thermistors was sampled at time in-
tervals determined by a solid-state clock and selected by the operator.
The signals from the thermistors were digitized and displayed on light emit-
ting diodes, printed on paper tape, and recorded on magnetic tape. Each
time the thermistors were sampled, information from the clock, the depth-
finder, and the positioning equipment was also displayed and recorded. It
was possible to measure temperature as a function of depth from the moving
boat at about 1800 known locations in about 1 hour, typically covering about
8 linear kilometers. The positioning system that made this possible is the
Motorola Mini-Ranger which consists of two shore-based transponders and a
receiver/transmitter unit and range console on board the boat.
The plume data were transcribed from the original cassette and read on-
to magnetic tape. With additional calibration data, the magnetic tape was
used in a computer program that was developed to plot the data. Seven hori-
zontal plots representing data taken at seven depths were plotted by a Cal-
comp Digital Incremental Plotter. The isotherms and centerlines were drawn
by hand on this output. The surface isotherms in Figs. 2-4 were obtained
by this process. During the 1972 field year alone, these automated data-
collection and -reduction techniques have allowed the acquisition and re-
duction of about 30 plumes, consisting of about 200 horizontal (as well as
200 vertical) sections.
Ambient conditions were routinely measured in conjunction with the
plume mapp ;. Ambient lake current was measured with a Bendix Q-15 geo-
magnetic doced-impeller current meter. Wind speed and direction were mea-
sured with a hand-held anemometer on the boat and by a shore-based Meteor-
ology Research, Inc. (MIe) portable meteorological station. Air temperature,
humidity, lake conditions, etc., were also measured for each plume. Table
II lists the instrument specifications for the 1972 and 1973 field year data.
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Kyser, J.M.; Paddock, R.A. & Policastro, A.J. Analysis of three years of complete-field temperature data from different sites of heated surface discharges into Lake Michigan, article, January 1, 1974; Illinois. (https://digital.library.unt.edu/ark:/67531/metadc1023368/m1/6/: accessed March 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.