5223

                                                         001R77105

                         NEEDS  FOR PLUME ANALYSIS
                           FOR THERF4AL AND TOXIC
                         POINT  SOURCE DISCHARGES*
                                     By

                            Mostafa A. Shirazi
                       Research Mechanical Engineer
                   U.S.  Environmental Protection Agency
             Pacific  Northwest Environmental Research Laboratory
                         Corvallis, Oregon 97330
     ABSTRACT


     In order  to satisfy  a variety of regulatory needs related to monitoring,
     enforcement and setting effluent standards for point source thermal

     and  toxic discharges, EPA has compiled a series of comprehensive nomograms
     describing the physical behavior of thermal plumes that are particularly
                           )C1G; il>i- LiGCi" IfiVCiVCu "111 uiicoc ciCCivlulci
     present  paper discusses these needs and summarizes the two workbook

     volumes  containing these nomograms.
     *For presentation at the U.S. - Japan Cooperative Science Program
     Seminar on Engineering and Environmental Aspects of Waste Heat
     Disposal, April 15-19, 1974, Tokyo, Japan.

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/-TiCH AGENCY

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          NEEDS FOR PLUME ANALYSIS FOR THERMAL AND TOXIC
                     POINT SOURCE DISCHARGES

INTRODUCTION1

 In  the United  States the  Environmental  Protection  Agency  (EPA)  is  responsible
for conducting research,  for  establishing  and  enforcing standards,  and  for
monitoring pollution in the environment.  An important responsibility
of  EPA is to assist the states and local governments in their own
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C I I  Ul 1,0 IU V.UII LI U I pu I  IUUIUII.

EPA's  functional and program  responsibilities lie in the areas of
air, water, pesticides, solid waste and radiation.  In the specific
program area of water, the legal tools necessary to attack the problems
of  pollution control are provided in the 1972 Amendments to the
Federal Water  Pollution Control Act.

The objective  of the Act is to restore and maintain the chemical,
physical and biological integrity of the Nation's waters.   The 1972
Amendments changed the thrust of enforcement from water quality
standards, regulating the amount of pollutants in a given body of
water, to effluent limitations, regulating the amount of pollutant
being discharged from a particular point source.  Ambient water quality
requirements can still  dictate the amount of pollutants permitted
for each discharge.

EPA is directed to establish guidelines for effluent limitations,
identifying the best practicable  control technology available for
various discharge categories.  These requirements must be met by
appropriate dischargers by 1977.  In addition, EPA must identify the best
 Regulatory and policy related matters are obtained directly from
Reference 1.

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 available technology for preventing and reducing pollution.  These
 requirements must be met by all dischargers by 1983.  The goal (not
 necessarily the  requirement) of the act is to eliminate all discharges
 by  1985.

 It  is  recognized that application of the best practicable or best
 available waste  treatment technology may not always provide an effluent
 of  receiving water quality.  In order to  accommodate  the  discharge of
 water  which, at  the end of the pipe, will viol ate receiving  water
 quality sldriudrdb, an area of mixing is specified.  The size of this
 "mixing zone" is  limited to an area which will not cause unacceptable
 biological stress.  Thus, a "mixing zone" is an area where receiving
 water  quality standards do not apply and its size is limited by
 biological considerations.  "Mixing zones" apply to all pollutants
 including waste  heat.

With respect to  thermal discharaes, the 1972  Amendments state  that
 if  the thermal discharger can demonstrate that an EPA limitation is more
 stringent than that necessary to protect the propagation of fish, shell
 fish and wildlife, then EPA may permit less stringent control, on a case
 by  case basfs.

 Therefore, in all levels of federal and regional EPA activities related
 to  establishing  and enforcing laws, issuing permits or monitoring
 point  source related discharges, the need for comprehensive understanding
 of  jet and plume behavior exists in order to determine if "mixing zone"
 limitations are being met.  Furthermore, the need for such understanding
 exists within the state and local government regulatory agencies as
 well as by participating private citizens.

 The majority of those having the need for understanding the physical
 behavior of plumes lack sufficient mathematical and thermodynamic
 backgrounds required for direct use of plume models.  This necessitates
 that the material be presented to them in a non-technical  language
                                    3

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 and yet  in  a  concise manner so that the applicability as well as the
 limitations of the  solutions are clearly understood by such users.
 Fortunately this task  is facilitated in part by the fact that the
 needs do not  require exact plume calculations.  The ultimate goal
 is the protection of water quality based on available biological
 criteria with an adequate margin of safety.-  Results based on current
 methods  of  analysis for predicting the physical behavior of the
 plume can well satisfy the accuracy achievable in the biological prediction
 of possible effects in the environment.

PLUME EXAMPLES

 Only a few  problems of general interest can be readily analyzed
 and presented in a  comprehensive manner so that a non-specialist
 user can feel at ease with.  The problem of a deeply submerged
 bouyant  jet is one  such example that is relatively well understood
 and ufuviueb  dn excellent opportunity for demonstrating certain general
 features of a real  plume, including the interaction of jet bouyancy
 and inertia!  forces with the ambient water.

Reference 2,  prepared by EPA, presents a comprehensive treatment of
 the subject.  It is titled "Workbook of Thermal Plume Prediction Volume
 I, Submerged  Discharges."  The workbook contains numerous nomograms
 showing  plume characteristics such as trajectory, temperature and
width.   Data  and analyses from numerous sources are presented in
 a unified format that is sufficiently simple for a non-specialist user.
 Basic assumptions are carefully stated, and the user is reasonably
well guided against misapplication of the information.

 Table 1 shows the type of problems addressed in the workbook for
 various flow  conditions and diffusers.  All computed trajectories and

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plume widths(W)  are  presented in dimension!ess forms using the
jet diameter  (D)  as  a reference.  The jet and ambient temperatures are
used to  calculate the local  center!ine excess temperature ratios.

Corresponding  to  each entry  in Table 1 there are given a group of
nomograms  describing the jet behavior for several Froude numbers (F),
angles of  discharge  (0), stratification numbers ($t), and velocity
ratios.  Figure  numbers  for  the nomograms in each group are cross
referenced with  the  jet  characteristics and tabulated for easy use.
For example, Table 2 lists  the figure numbers for 35 nomograms for
a discharge into  stagnant water at various angles of discharge with
the horizontal and for several  specific diffuser configurations.
The nomograms  are presented  in pairs.  For example, Figures 1 and 2
corresponding  to  Figures A-l  and A-2 are presented as one pair in
the workbook.  The first Figure contains temperature-trajectory information
and the  second, width-trajectory  information.  The pages containing
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The user is given a  physical  explanation of the solutions given by
the nomograms.   For  example, with regards to plume dilution as a
function of Froude number,  Figure 1  shows that as Froude number decreases
the plume  dilution increases rapidly as indicated by the  converging
temperature lines near the  vertical  axis.  This is explained by the
fact that  for  two identical  jet velocities and diameters, the jet
with a low Froude number has a greater total momentum due to bouyancy,
thus causing greater mixing.

Presenting the nomograms for the discharge into a stratified body
of water in a  general  form was  particularly difficult because of

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dependence on the inital discharge level as well as other parameters.
The workbook assumes discharges to take place at various depths  z  below
the thermocline as shown in Figure 3.  An example of the nomograms is
given in Figure 4.  It is explained in the workbook that for a very
large stratification number approaching infinity the plume rises
indefinitely.  In an environment with a finite stratification the plume
initially entrains cool water and carries it into warmer layers of
water above it.  The plume temperature continues to drop while the
temperature of the surrounding water continues to increase with
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bouyancy but continues rising because of its excess momentum even when
its centerline temperature at a point along its trajectory equals
the local ambient temperature.  This excess momentum carries the plume
from this point to its terminal height.

Other nomograms for conditions of discharge into an ambient current
and for shallow discharges are also provided in the workbook.  Practical
example problems are worked out, not only to show the mechanics of
using the nomograms, but also to direct the attention of the user
to possible pitfalls of misusing the nomograms for problems they
are not intended for.

The second volume of the workbook is devoted to surface discharges (3).
In the preface, the reader is introduced to the subject in this
manner.  "The nomograms provide qualitative results describing the
surface plume trajectory, width, temperature, depth, surface area
and time of travel along the plume centerline.  The nomograms are
not intended to be used as exclusive design tools for the surface
discharge problem nor for use in a precise prediction of specific
plume conditions. "

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The nomograms are referenced the same way as in the first volume
by providing tables, with figure numbers corresponding to specific
discharge conditions.  Tables 3 and 4 show this information as well
as the range of values for which working nomograms are presented.

In addition to what is referred to as "working nomograms" a set of
supplementary nomograms are also provided in the workbook. The working
nomograms are distinguished from the supplementary nomograms in that
the user is not required to specify the program coefficients, such
as the turbulent exchange coefficient, drag coefficient, shear and
entrainment coefficients.  The workbook has made this decision for
the user by fitting the program to the mean of a reasonably wide
range of data.  The supplementary nomograms are intended for special
applications where the stated coefficients are known to deviate substantially
from those recommended in the workbook.

Figure 5 is an example of a typical temperature, trajectory, width
and depth nomogram showing the effects of ambient current on all
plume characteristics.  The plots are presented for constant jet
densimetric Froude number F, channel total width to depth aspect ratio
A, dimensionless heat exchange coefficient K, and angle of discharge TH.
The dashed lines along the trajectories are made proportional to
the local plume depth.

As in the first volume, considerable effort is devoted to familiarize
the user with the physics of the problem so that the user gains an
intuitive understanding of the nomograms.  For example, temperature,
trajectory, width and depth plots similar to Figure 5 for variable
ambient current are presented to show the effects of variable jet Froude
number (see Figure 6), jet aspect ratio (see Figure 7) and initial
discharge angle (see Figure 8) on the plume characteristics.

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These  figures  show  that  plume  penetration  across an ambient current is
enhanced  by  (1)  small  ambient  current,  (2) small densimetric Froude
number F, (3)  large jet  aspect ratio A,  and  (4) a large angle of
discharge.   Furthermore,  generally hot  and wide plumes are found
under  the same four discharge  conditions.  Neither the ambient
current nor  the  discharge  angle seem to  influence the plume depth
greatly.   A  small discharge  Froude number  causes a thin plume due to its
tendency  to  stratification.

The workbook contains  nomograms for the  surface plume areas influenced
by given  isotherms.  An  example of this  type is given in Figure 9.
Additional plume  information directly useful for ecological studies
is the time  of travel  along  the plume centerline.  An example of this
type of information is given in Figure  10.

CLOSURE

The foregoing examples of  plume analysis demonstrate the way EPA has
attempted to present a very  complex technical problem to benefit those
within government agencies in  their decision making processes as
well as to invite a wider  participation  of non-government groups to
understand and to mount  an integrated attack on pollution.  It is an
attempt to narrow the  gap  between "what  the scientist knows and what
the citizen  understands."  A gap which must be narrowed to
enable the "citizen...to make  intelligent, effective decisions about
the patterns and problems  of growth...1

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 REFERENCES

 1.    Ruckelshaus,  William  D.  "The  Challenge of the  Environment: A
      Primer  on  EPA's  Statutory Authority"  U.S. Environmental Protection
      Agency,  Dec.  1972.

2.    Shirazi, M. A. and  Davis, L.  R.   "Workbook of  Thermal Plume
      Prediction, Volume  I  Submerged Discharges."  Environmental Protection
      Technology Series EPA-R2-005a, August 1972.

 3.    Shirazi, M. A. and  Davis, L.  R.   "Workbook of  Thermal Plume Prediction
      Volume  II, Surface  Discharges"  Environmental  Protection Agency,
      March 1974.

4.    Russell E. Train, From an address to the American Association for the
      Advancement of Science in San Francisco, Feb.  25, 1974.

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                             TABLE 1**

             Summary of Subjects for Submerged Heated
                   Jet Discharge Presented
                         in Reference (2)
Diffuser
Configuration
Single
Round
Port
A Row of
Multiple
Round Ports
Condition of Ambient Water
Non-Stratified
No Current
RNN
MNN
Moving
RCN
MCN*
Stratified
No Current
RNS
MNS
Moving
RCS
MCS*
*Nomograms not presented for these  cases.

**A three-letter code is used for convenient  reference.   First  letter
designates type of diffuser; second letter, the  type  of  current;  third
letter, the degree of stratification.
                                   10

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                   TABLE 2

Figure Numbers Corresponding to Plume Behavior
   From Submerged Diffusers Discharging into
        Stagnant, Non-Stratified Water
               from Reference (2)
Diffuser
RNN
C -i vt n 1 f\
*j" i ny i >-
Jet



O)
OJ i.
i CL)
D. to
r~ 13
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S.

IT)
II
Q
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O
II
Q
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O
CM
II
Q
	 1
CD
CO
II
Q
Discharge Angle
0
A-l ,2

A-8,9

A-l 5, 16


A-22,23


A-29,30
30
A- 3 4

A-10,11

A-17,18


A-24,25


A-31,32
60
A- 5, 6

A-12,13

A-19,20


A-26,27


A-33,34
90
A-7

A-14

A-21


A-28


A-35
                        11

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             TABLE 3

.Figure Numbers for (TTWD) Working
Nomograms for 0-  = 90 and K = lO"5
         from Reference (3)
F+
M
1
5
10
15
2
Al
A5
A9
A13
4
A2
A6
A10
A14
6
A3
A7
All
A15
10
A4
A8
A12
A16
               TABLE 4

 Summary cf Figure Numbers for (TTWD)
          Working Nomograms
            from Reference (3)
V
4- 1C
io-5
io-4
io-6
90
Al -Al 6
A49-A64 *
A97-A112
60
A17-A32
A65-A80
A113-A128
120
A33-A48
A81 -A96
A128-A144
              12

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    20   40  60   80  100  120  140  160  180  200
          LONGITUDINAL DISTANCE X/H0

FIG( 5 ) TEMPERATURE,TRAJECTORY,WIDTH, AND DEPTH
       (TTWD)-PLOTS FOR SURFACE JET DISCHARGE
       SHOWING  EFFECTS OF  AMBIENT  CURRENT

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  300



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  180



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          20  40   60   80  100  120  140  160  180  200



                LONGITUDINAL DISTANCE X/H0



      FIG(  6 ) TEMPERATURE,TRAJECTORY,WIDTH,AND DEPTH

             (TTWD)-PLOTS FOR SURFACE JET DISCHARGE

           SHOWING  EFFECTS  OF   OENSIMETRIC  FROUDE

           NUMBER

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    20   40  60   80  100  120  140  160  180   200
          LONGITUDINAL DISTANCE X/H0

FIG(  7 ) TEMPERATURE,TRAJECTORY, WIDTH, AND DEPTH
       (TTWD)-PLOTS FOR SURFACE JET DISCHARGE
      SHOWING   EFFECTS  OF JET  ASPECT  RATIO

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             (TTWD)-PLOTS FOR SURFACE JET DISCHARGE

            SHOWING   EFFECTS  OF   DISCHARGE  ANGLE

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