(jSBZJ
  "< -mx*
                                              SPA
               UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                             WASHINGTON. D.C 20460
                                DEC I 5 /988
                                                            WATErt
MEMORANDUM


SUBJECT:



FROM:



TO:
                           Guidance  on Supplementary Stream
           Design Conditions  for Steady State Modeling

           Martha G. Protnro, Director
           Office of water Regulations


           Water Management Division Directors
           Regions I - X


                                                                       .^-.^

-------
Attachment
                     Dr.  Tin s.  Stuart,  Chief
                     Monitoring  Branch
                     Monitoring  and  Data Support Division (WH-553
                     Telephone:   (202) 332-7074
cc:
James R. Edler, OWEP
Michael J. Quigley, OMPC
Clyde J. Dial, RREL/ORD-Cin
Thomas Nelson, ERL-Duluth
Lea Mulkey, ERL-Athens

-------
         TECHNICAL GUIDANCE ON
      SUPPLEMENTAL STREAM DESIGN
  ONDITIONS FOR STEADY STATE  MODELING
            December 1933
           AND DATA SUPPORT DIVISION
    OF WATER REGULATIONS  AND  STANDARDS
                AND
    SEDUCTION ENGINEERING LABORATORY
    CE OF  RESEARCH AND DEVELOPMENT
      CINCINNATI, OHIO  45268
         OFFICE OF WATER
-S.  ENVIRONMENTAL PROTECTION AGENC*'
     ••VASHINGTON,  D.C.   2Q460

-------

-------
                         ACKNOWLEDGEMENTS
:n«itut..
Project Sup.rvlSion

                                                       - •••
                                     manager and provided
             •
        John caiman
         Morberc Huang
         John Maxced
         David Meieiah
         _.        Slgh
         Glenn Tucker
         Bruce zander

                            OWEP, us EPA
                            OMPC/ Q
                            OWRS( us
                                   n,  U5 EPA
                                   VI,  US EPA
                            Region ^ ^  us
                            Region xili,  US EPA

-------
                              CONTENTS
                                                             SS
 SECTION 1.   INTRODUCTION 	

         L. 1  Purpose 	
         L.2  Background 	
         l.3  Use of This Guidance 	
         L.4  Limitations and Assumptions 	 	
         1.5  Overview 	


 SECTION 2.   :-/QC EXCURSION FREQUENCIES 	  :

         2.i  Introduction 	
         2.2  Extreme Value-Based Method 	'.'.'.'.  i
         2.3  Bioloaically-Based Method 	  :


 .SECTION  3.   'JOMPt/TATIOMAL METHOD 	  :

         3.L   Tntroduction 	  ^
         3.2  Assembling  Daily Stream  Data Records  	  i
         3.3  Derivation  of Allowable  Stream  Loadings  	  2
         3.4  Determination of Critical Loads	  2
         3.5  Derivation  of Design Conditions 	.'!.'.'  2


SECTION 4.  EXAMPLE CASE STUDIES 	   3

        4.1  Quinnipiac River 	   3
        4.2  Pollutant and WQC Selection	   3
        4. 3  Retrieval of Stream Data 	   3
        4.4  Specification of Discharger Data  	: . . . .   3
        4.5  Computation of Design Conditions  	   3
        4.6  Design Conditions for Other Pollutants 	   3
        4.7  Uncompahgre River 	   4


SECTION 5.  UTILIZATION GUIDELINES 	   4

        5.1  Data Availability 	   4
        5.2  Choice of Analysis Options 	   4
        5 . 3  Interpretation of Results	   5


SECTION 6.  REFERENCES 	   5

APPENDIX A.   WATER QUALITY CRITERIA 	   5

APPENDIX 3.   HOW TO RUN THE DESCON PROGRAM 	   5
                                11

-------
,, w                           TABLES
Tabi_g
  -•l  Pollutants an* Design Conditions Considered
        3y DESCOM
  3-1   Expresses  for Allowable stream loading 'over
       specified Averaging Period
 4-1  Comparison of Design Conditions
      ene Quinnipiac River 	

 4-2  DESCON input Data for Lead and'UQD'in'the
      Quinnipiac River
 4-3  Design Conditions for
                                           andTOD  .
          guimupiac River
             :;iBUC  ;Jata for tne C/ncompanare *ver

     '"    C——  'or A-oni..  Lead,  and
         t/ncompangre River

-------
                        FIGURES
riaure
   1.1
   3.1
   3.2
  3.4

  4'. 1
  4.2
  4.3
   Occurrence of Critical Conditions  for Ultimate
   Oxygen Demand for the Sheyenne River near
   Kindred ,  :.'D ......................................
2  Typical Results From the DESCON Program  ..........
1  Illustration of Biologically-Based Method of
   Counting  WQC Excursions ..........................   ]_
   Computational  Scheme for Deriving Design
   Conditions .................                         ,
                                    *••••••••••• .....   *
   Schemes for Representing Daily Variation in
   tfater  <}ual i r.y  Parameters .........................   i_
   t.'riterior:  '.'ontinuous Concentration for
   Tc '.al  Ammon ia  ......................
   Relationsnip Betveen Critical  Load and  Number
   of Bioloaically-3ased WQC  Excursions  .............  2:
   Daily  Temperatures  in the  Quinnipiac  River  .......  3
   Daily  pH in the Ouinnipiac  River  ............ ."....  3,
   Daily  Alkalinity in  the Qui

-------
         ABBREVIATIONS

ASL   allowaila stream loading
      critarion continuous concantration
      critarion maximum concantration
      coafficiant  of variation
      dissolved oxygan
      ultimata  oxygan damand
      wasta load allocation
     vatar quality critaria

-------

-------
      Purpose

       The purpose

       to

                             SECTION 1
                           INTRODUCTION
                      this
                                            -»••   -


                             water quality  criteria.
     This document  i «  -c,,i i
raco.nnended  in the Technlc \  , C°nsistant
"A,  1S86C)  and                 "^
                                              the  approaches
                                                    -dition
1-2 BACKGROUND
                            (WQC>
                       (HlA)retactive


-------
      When a  steady  state  water  quality  model  is. used to  deter
 a WLA, the pollutant  loading  introduced into  the model under
 given set of assumed  water quality conditions  (e.g.,  streamfl
 •temperature, PH) win produce an  in-stream pollutant  concentr
 -ion chat just satisries  the WQC  concentration  limit. The val
 or -.he water quality conditions used as  input to  the  model ar.
 called design conditions. Design  conditions should be chosen
 -.hat waste Loads derived  from a WLA win also satisfy the
 applicable WQC excursion  frequency.

      To achieve -nis goal, design conditions  must somehow be
 on conditions rjiac  .-refine the critical event  in the receivina
 vater. "nder  -r.ese  c~naitlOns,  the capacity of the stream to"
 receive vasce w-.uhout  violating  the WQC  concentration has a
 frequency ot  occurrence  identical  to  that a.  .wed by  the  WQC
 -xcursion frequency. The material  presented in  this cuidance
 document shows  now r.he characteristics of this critical event
 be identified approximately and  used to  derive a  rational set
 WLA design conditions.

     Most regulatory agencies currently use the 7Qio or some
 other extreme value-based  low flow as the design  flow, and
 -he most  critical monthly  mean value for  all other design
 conditions.  :t  IS difficult to ascertain whether such desian
conditions will in fact produce WLA's that satisfy the requir
 excursion frequency.  Figure l.i shows that the values of the
condition variables  (flow  and temperature in this case) need
be at their individual critical levels to produce the critica
 loading that satisfies the WQC excursion  frequency. rn tnis f
 nhe critical allowable UOD loading occurs in August, based on
 and temperature conditions that occur in that same month.  The
not the same as the  individual critical flow and temperatur-
occur in  September and July, respectively.

-------
3GQ.
                                       \
                                                            ' "210  Law ?"law



                                                                     ro



                                                                      UCO Caoa
                                   '.    8    3    10   n    T2


-------
      Current  practice also  typically uses  the same  set of
 design  conditions for several different classes of pollutants.
 Yet critical  events  can  occur at different times of the year
 for different pollutants. For example, the critical event for
 UOD may  occur at  a  different time  (e.g., under a different
 combination of flow  and  temperature)  than the critical event
 for ammonia toxicity. The practice of using  the same design
 conditions  to  analyze   both  pollutants  can  therefore  be
 questioned.

     This guidance document addresses the calculation of design
 conditions for five categories of pollutants.  The  pollutants
 and their corresponding set of design Conditions are given in
 Table   1.1.  in  simple  single  discharger settings,   design
 conditions are produced for both the ambient upstream flow and
 the discharger  flow  streams.  Design  conditions  for other
 categories of  pollutants  may  be  addressed at  a later date,
 depending  on  the specific needs  of  regulatory agencies.  The
 concept of design  streamflow  and  WQC excursion frequency has
 recently been  discussed  in the Technical  Guidance  on Stream
 Design Flow (U.S. EPA,  1986c). The procedures described in this
 document utilize the  same two methods  of  defining excursion
 frequency  —  the  extreme  value method  (referred to  as  the
 hydrologically-based method) and the biologically-based method.
 The extreme value  method  limits the  number of  years in which
 one or  more  excursions occur. The  biologically-based method
 limits the total number of excursions that can occur.

     The design conditions discussed  in this document are only
 applicable to constant, year-round WLA policies. They do not
pertain to time-varying or seasonal allocations that assign
different  allowable discharge  loads  during different periods
of the year.

-------
Disc™*"" *
                             """» condl«t«. consist By
  •-oliutant
  General
  -oxleant

  .Ammonia
 Heavy Metais
   Cadmium
   Chromium
   Copper
   Lead
   -VicJeei
   Zinc
              _  .
              Design Condicions
           "low
                        Flow
                        Temperature
                        PH
-low
Hardness
                              Flow
                              Toxicant

                              Flow
                              Temperature
                              PH
                              Alkalinity
                              Ammonia

                              Flow
                              Hardness
                              Metal
 Pentachioropneno i
Vltimate oxygen
Demand
Motes •  i
        '
                       Flow
                       PH
         Flow
         Temperature
         Dissolved
         oxygen
                   Flow
                   PH
                   Temperature
                   Alkalinity
                   Pentachlo ropheno1

                   Flow
                   Temperature
                   Dissolved
                   oxygen
                   UOD

-------
       The data necessary to derive  design conditions using the
  procedures described  in this document  a-re as  follows:
  3.
historical daily screamf lows ;
historical data tor estimates)  of  in-stream values of the
water quality variatiles relevant to  the pollutant being
analyzed;
Historical data tor estimates)  of  flow  and  water  quality
a discharger it one is considered.
  While Lonq-r.erm.  .runt: -year streamflow records are required,
  •methodology m.itces • :ie oesr. use of whatever water quality data
  v/anable.  ::o  matter  now sparse they may be.

  1.3  USE OF  THIS CJUIDANCE

       The methodology  described in this  guidance is implemente-
  means of a  computer program called DESCON.  DESCON is  installe-
  the Agency's IBM  maintrame computer in  Research Triangle Park
  North Carolina, and can  be accessed through remote tele-
  communications services.  It is  a  menu-driven,  interactive pro.
  that  provides automatic  linkages  with the Agency's STORET dat.
  to retrieve streamtlow and water  quality data.  The basic step,
  using DESCON to calculate design  conditions can be summarized
,  follows:

  1.    Select the pollutant and  type  of WQC to use.
  2.    Retrieve historical  stream flow and water  quality  data u
  DESCON.
  3.    If the stream segment contains a single discharger, assei
  data  or estimates for discharger  flow and pertinent water  '
  quality variables.

-------
      -
«.„          .                        »• - ..... -,.,„
               stream Flow         .   34>8   ^


        Design  s.ream Temperature   =   23  9   dea   -

        Design  Sr.ream py               _     "


        Design  s-.reajn Alkalinity    =   -•/ .
                              '       ----
                                                ^s CaCO,
  LIMITATIONS AND ASSUMPTIONS
 option chough, of fixina  in  *           Analyst has the

                   fixing  in advance the design streamfic

-------
                   SUMMARY OF DESCON INPUT DATA
    LOCATION
    POLLUTANT
    COLD WATER SPECIES PRESENT
    WOC EXCURSION C-'ETHOD
    AVERAGING PERIOD, DAYS
    RETURN PERIOD.
    PERIOD OF PECORD
    FLOW ADJUSTMENT FACTOR
    DISCHARGER LOCATION
    RANGE OF "FSTREAM POLLUTANT
    RANGE OF r'FSTREAM TEMPERATURE
    RANGE OF rrpSTREAM PH
    RANGE OF UPSTREAM ALKALINITY
    RANGE. OF DISCHARGE FLOW
    RANGE OF DISCHARGE TEMPERATURE
    RANGE OF DISCHARGE PH
    RANGE OF DISCHARGE ALKALINITY
QUINNIPIAC R,  //ALLIMGFORD
AMMONIA
YES
BIOLOGICALLY-BASED
   4.0
   3.0
EPA NATIONAL JCC
ENTIRE RECORD
   1.0
BELOW FLOW GAGE
                    MG/L
                    DEG.  C

                    MG/L
                    CFS
                    DEG.  C

                    MG/L
0.0
1.2
5.5
25.0
32.0
14.2
7.0
245.0
TO
TO
TO
TO
TO
TO
TO
TO
).0
24.0
3. 2
36.0
32.0
25. 3
.'.0
245 .0
                 CRITICAL  DESIGN CONDITIONS
   CRITICAL DAY "F RECORD
   UPSTREAM FLOW, _FS
   UPSTREAM AMMONIA-M, HG/L
   UPSTREAM TEMPERATURE, DEG  C
   UPSTREAM FH
   UPSTREAM ALKALINITY, MG/L
   DISCHARGE FLOW, -JFS
   DISCHARGE AMMONIA, MG/L
   DISCHARGE TEMPERATURE, DEG C
   DISCHARGE PH
   DISCHARGE ALKALINITY, MG/L
 JULY  25
         ,  1957
           34.3
            0.0
           23.9
            7. 6
           72.2
           32.0
            1.9
           25.0
            7. 0
          245.0
FIGURE 1.2  Typical Results  From the DESCON Program

-------
                                  or
               a
     «•
D.
o .

                           conaition
                                           their
         or r,
   record. ror                               """I -'10-

             '                      ' '
         for ,acn da                        »W oxy,,
               clay of the flow record.

OVERVIEW

      •                  -•        "     ---
                                            .


-------
                             SECTION 2
                     WQC EXCURSION FREQUENCIES
   2.1 INTRODUCTION

      The term  "vater quality excursion" denotes an unfavora
 condition occurring vich respect to a specific WQC. This cou
 either be an in-stream toxicant concentration in excess of a
 upper limit, or,  as in the case of dissolved oxygen (DO),  a
 concentration i=vel below a specified lower limit.   Because
 the  many stochastic factors that influence water quality,  i-
 impractical  to  .specify a WLA that guarantees zero risk of
 •excursions.

      Most  aquatic  ••ommunities can either  tolerate or  readily
 recover  from infrequent,  non-catastrophic  environmental  stre
 It is  therefore statistically necessary and  toxicologically
 reasonable to base  a WLA on  some  acceptably  small frequency
 excursion, providing one carefully defines how excursions an
 their  frequency of  occurrence are to be determined, it is th
definition which constitutes the meaning of  the term "WQC
excursion  frequency".

     Design conditions are the connecting  link between WLA's
based on steady-state analyses and the time-varying vater qu
 responses that are  produced  in reality. Design conditions sh
be set so that the  allowable load derived  from a WLA using a
steady-state water quality model  results in  the allowed  freq
of WQC excursions wnen the loading is analyzed in a dynamic
time-varying) setting.

     In conformance with previous guidance developed for des
streamflow (us EPA, 19-860,  this document  acknowledges the u
 two alternative methods for  defining excursion frequencies.
 following sections  reviews each of these in  turn.
                                10

-------
  2.2  EXTREME VALUE-BASED METHOD


      This method (rererred to as the hydro logical-cased

           n c" Tschnicai Guid— — o«i^
            a Logxcai outgrowth of th. customary practice of  -
 r-n. «0y low fiov La ,XA studies.  (The xQy, e.g.. 7Q10
 « th. lowest annual :<-day average  flOw that occurs an
 one.  every  y  ,..„.,  ^ appUed  t
-------
 In addition, a-30-day averaging  period can be  used  at  the
 analyst's discretion, vhen considering the CCC for  ammonia
 toxicity or for any other WQC based on chronic human health
 effects.

 2.3 BIOLOGICALLY-BASED METHOD

      The extreme value method has been criticized for  its  fai
 to account for r-ne effects of multiple excursions that may oc
 vithin the years 1:1 vhich excursions are allowed. It   is also
 difficult to find any biological justification  for employing
 specific return period (e.g., 10 years)  vhen the actual numbe
 individual excursions vithin a year is not controlled.

      In response <-r> r.hese shortcomings the US EPA's Office of
 Research and Development  proposed a method that uses the
 averaging periods  and excursion frequencies  specified in the
 EPA's  national  vater quality criteria for aquatic life. The
 biological  basis  ror r.his method is the  concept of providing
 safe,  excursion-tree average recovery period  between excursio
 so that ecosystem  recovery can occur.  A  3-year  recovery peric
 was  proposed for normal stresses and a 15-year  period was  dee
 reasonable  for  major stresses associated with prolonged drouc

     The biologically-based method allows an  average of one •«
 quality excursion  every three years.  A water  quality excursic
 counted for each distinct, non-overlapping x-day period where
.average in-stream  concentration exceeds  the WQC concentration
 limit  (or falls below a DO limit),  ('x'  is the  averaging peri
 specified in the WQC).  For example, if each day in a block of
 consecutive days  belonged to a 4-day average  that was above t
 WQC limit then  the number of excursions  for  this block  would
 10/4 = 2.5.  However, vithin any period of 120 days,  no  matter
 great  is the actual number of excursions, a  maximum of  5 will
 only be counted.  This allows for the maximum  recovery period
                                 12

-------
                             n
                        . sions were counted (3 :< 5 =

                                                       ,S)

perlods fau .Ji
    „
                   P9r
counting excursions

               1
                                          Since Both
                                "" " S' This meth°<»
                         13

-------
                -csv cvg. srcwn for c=y x eovqra cay« x tnrougn x-3




                             ,excursion Pariocs
                             /               v
a
       !_

       /i
       u
                             excursion Ciuatar
                                10




                               Days
15
      2.1  Illustration  of Biologically-Based  Method  o-

            Counting WQC  Excursions
                                   14

-------
 4  days  for  CCC  normally;

 30 days  for ammonia  ccc or  fnr.   u
                  ia  ccc or  for  chrome  human  health  crite





once every  three years, on average;
120 days;
                          15

-------
                             SECTION 3
                        COMPUTATIONAL METHOD

 3.1 INTRODUCTION

      This section cescribes the computational steps utilized ;
 "he computer procrram DESCON to derive a set of situation-spec'
 •iesian conditions.  1'ESCON computes design conditions accordinc
 "he following tour  -tep procedure (see Figure 3.1):

 '..   ^ long-rerrn  record  or? daily streamflow and •••/ate. quality
 oarameter v.iiues  :.;  assembled  for the stream segment in quest

     The .iii.ovaD.-3 --ream  load  (i.e.,  the  pollutant .oad that
 leer.s  rhe WOC  --;nc
-------
         ©
    Suum flam
    i •"•••*•««•
      DAYS
       |o*«.l        p^.
-  —"!  M7" f—    J--—-
       I  v«je           i
DAYS
                   CritMM f .«M
                                                         DAYS
                                                                      C"|IC-

-------
       DESCON assumes that daily values of these supplementary c
  variables  follow a deterministic annual pattern that repeats t
  365 days.  The  DESCON user supplies  the day of the year and it<
  corresponding  water quality parameter v- :e for each relevant
  design variable.  Linear  interpolation is used to fill in value
  missing days.

      Figure  3.2  :;nows how this method can  accommodate various
  levels of data Availability. Case A  indicates  the  general  case
 vhere data are available  throughout  the  year  although no gener
 •seasonal pattern  :::  evident. In Case  3,  the historical data  ha
 ~een fit-, sd <-.o .* sinusoidal  function. This type  of  representat
 •-s most appropriate  tor stream temperature and dissolved oxyge
 <: and D are cases vhere the historical data for each month of
 year are best represented by a single value, either the mean,
 median,  or  perhaps the most critical value. In Case c, this v«
 -s placed at the midpoint of the month and DESCON uses linear
 interpolation r.o find values for the intervening days. For Cas
 the value  is placed at each endpoint of the month.  Interpolat:
 then results in a constant value throughout the month.

      DESCON contains a utility  routine that can extract what-
 ever daily  parameter measurements are available from STORET ar
Compute  their overall means for any  day or  month of the year.
'routine can also  fit a sinusoidal function  to  the daily values
 provide  the user  with a goodness  of  fit measure,  and then,  if
 instructed,  use the fitted function  to compute daily
.parameter values.  These are then stored in  a file for future
 processing.  When DESCON requires  that daily discharger flow ar
 water quality parameter data be provided for each day of  the s
 the same  representation schemes can  be applied.
                                18

-------
en;
                                  CD)
                                CO)
                                       in Water
                  19

-------
      More sophist leaned methods that generate daily  values  in
 stochastic fasnicn can also oe employed by DESCON. However,  t
 approach taJcen ::<. this guidance manual assumes  that  it  is mor
 important -.o capture the predictable seasonal variability of
 Duality variables rattier than their random fluctuations.

 3.3 DERIVATION OF ALLOWABLE STREAM LOADINGS

      The allowance  stream loading (ASL)  is defined 10 be the
 maximum amount  :  coilutant the water body can receive over a
 specified .v/eraaina  period  and still meet  the applicable WQC
 roncentration  . _.-iur..  ;:i  General the ASL  will  depend on the
 •r.reamrlow.  • emoprir.ure,  pH,  etc.,  that  occur during  the peri
 tveraaina.

     The  ASL ..; raised on  the  simple  dilution  (or mass balance
 equation  that  sads discharge  flow to upstream flow:
Ci * Ql
                                   C2  * Q2
where:     ci = upstream pollutant concentration
           C2 - -lischarger pollutant concentration
           C3 = -downstream pollutant concentration
           01 = upstream streamflow
           Q2 = 'lischarger flow
           03 = QL - Q2
The ASL is found by manipulating this expression as  follows:
   1.  solve for C3,
   2.  average each side of the resulting expression  over  the
      duration specified in the WQC,
   3.  replace the average value of C3 with the WQC concentrat
      limit,
   4.  solve the resulting expression for C2 and set  this  equa
      ASL.
                                20

-------
final result  ;s


ASL = (  r;.;nC'
«« cannot b

or analysis

   -fi^, is
 it  vhenev.r
      poSs1Bla.
                   'e '
Period of record. -,
                                           ~

                                 :n"
                                                 Si.cB.r-
                                                 c a:scn

                                                  an in-
                                   information supplied
                                                ai !
                                 2-  DESCON
                                             ''""
                                          'our  days  of
                             V L'
                            2'
     for days :
           day ln en. ^
          r..ult  in 50.3M  .  18.2      al a
                                      -era.es =omplle

-------
      The values of Ql come directly from the historical stream
 record.  Values  ror Cl and Q2 come from the daily records of
 upstream pollutant concentration and discharger flow, respect:
 -hat  are supplied by ".he user (see the discussion in Section 3
 above).  Values  or ".he woe .limit  can be functions of such
 supplementary design variables as temperature, pH, and hardnes
 For example, Figure 3.3  shows how the US EFA's CCC limit on tc
 ammonia  is  related r.o stream temperature and pH.  Sections A.l
 -.hrougn  A. 3 of  Appendix  A describe the equations  used to compu
 WQC limics  for  ammonia,  heavy metals,  and pentachlorophenol,
 respectively.

     t.'ote that  : :•.  Ra.  ;,  tne  WQC  value refers co  the  critericr
 .imit "..iat Gxintr.  in  r.ne  mixture  of  upstream and  discharge  flc
 Prior -.o usina  r.ne  woe equations  in  Appendix A, DESCON  first
computes r.he mixture  values of any supplementary  variables  sue
 temperature, pH, or Hardness. To  properly compute  a mixture pt-
knowledge of upstream and discharger alkalinity is also  requii
This is why alkalinity is also considered to  be a  supplemental
design variable. Section A.5 of Appendix  A describes the equat
that carry out the mixing computations.

     The use of Eq. I to derive ASL values for Ultimate Oxyger
Demand 
-------
•Fiona 3.3  criterion  Continuous Concentrati
                                             on -or Tatal Aaaoni

-------
      The method or averaging used vich Eq. 1 will not be valic
 '.'OD because the streeter-Phelps model used in Appendix A is or
 applicable to sceaay-state conditions. It does not take into
 iccount che effect -.".at varying times of travel over the peric
 averaging will :iave on the location and magnitude of the crit:
 DO sag .  To cope vith this problem, Eq. 1 can be used as a ste
 state approximation r.o the actual day-to-day variations that c
 over the averaging period.  As a result, the ASL equations for
 are as follows:
              "OD  *   'J3iavg  -  rci]avg  *  [QUavg
      ASL   =   ------------ - --------- - --------- -  discharger
                            CQ21avg                 present
     ASL   =   "OD  *  Qllavg                without  discharger
where LTOD  is  !-ne maximum  initial UOD  that meets  the  DO criter
under the  averaae  r'Low, temperature,  and upstream  DO conditioi

     One other exception was made to  the way Eq.  1 was used t-
compute ASL's. For the case of the extreme value WQC excursio:
criterion  applied  to a general toxicant with no discharger  da
considered, the ASL expression is

              ASL   =   [WQC)avg * CQl]avg

as opposed to Eq.  J. in this situation, the only design condi
is a design streamrlow of the xQy (e.g., 7Q10) variety.  This
'equation allows DESCON to produce xQy design flows equal to t
based on current practice (i.e., a Log Pearson Type  3 frequen
analysis of the annual minimum x-day  average flows). Table  3.
summarizes the various equations used to compute  an  ASL for e
day of  the historical  flow  record.

-------
                                                      over .
 Heavy Metals,
 Pentachloro-                 ^
 Phenol,  and      ."„'*'"? ~  C1*Q*/Q3 ]ava          -woc
 General                                                "-
                      • >ame  as                    ,
Ultimate       ,OD./Q3,                              av?-Ql Ia.
Oxygen         -?°_1?3 '^g -  CCl ]avg*[Qi

                      ""
                                                       f 01
                                                           ava

                              25

-------
 3 . 4 DETERMINATION OF CRITICAL LOADS

      DESCON defines -he critical load as the  largest  constant
 =unount of pollutant -tie water body can receive and still  satis
 -he applicable WQC excursion frequency. For a proposed critica
 load,  excursions w-iii occur during any period of the  synthesis
 ASL record where r.nis load exceeds the ASL. DESCON searches fo
 -he largest critical Load whose resulting pattern of excursion
 meets  the WQC excursion frequency.  This search is carried out
 two different v.-.iys ,  • Depending on whether the extreme value or
 niologically-based method is employed.

     "or  -tie extreme vilue method,  a  Log Pearson  Type 3  freque
 maiysis  -.s.usec -o  : ind the minimum  annual ASL with  the  requi
 return  period (Typically 10  years). This  value then  becomes  th
 critical  load.  The analysis  begins  by first identifying the  lo
 ASL  value  for each year  of  the simulated  record.  Thus  if  a 50
 record  was  beina  used,  there  would  be 50 minimum  annual
 ASL's.   Then  the  mean  (u),  standard  deviation  (s), and  skewness
 coefficient  (g) of the natural _ logarithms of these numbers are
 found.   The critical  load  (L*> is found from the following  equa
      L* = exp(u  - K(g,y)*s
where y is the return period  (years) on extreme value excursic
and K is a frequency c actor expressed as a function of skewnes
fg) and return period (y). The frequency factor, K, can be
calculated from the following equation given in Loucks , et al.
[1981]:

  KCg,y) = (2/g)((l - (g*z)/6 - g2/36)3 - 1]

where 2 is the frequency  factor for the standard normal probat
distribution at probability level l/y. The latter can be  found
•is ing [Joiner and Rosenblatt, 1971]:
                                26

-------

Procedure ,cn=,n ,., ell.
  record  ,;„  vears  -


                                         """
                                          P°'ltio"
                                      '
                                                   " is tfte
                                                            excu

                       two

                      f.hen .
tolerance of E*  rne  Drore<= =  = *
                 -ue  process  stops  with L* = rt
continues with <  L3 ED  ra ,   •
repiaclng (L2 £,"  ^  ^ ^^  '".El,  if E3



3.5 DERIVATION OF DESIGN  CONDITIONS



-------
         G)
         c
         _0

         tj]
         L.
         -t
         0
         X
         LU
      CLX.EH3
CL3.E33
                     Cr- i  t i cal   Lead  CLD
FIGURE 3.4  Relationship Between Critical Load and Number o:
            3iologically-3ased WQC Excursions

-------
  occurring durxng £.,. critical event  in tne period of record.
  -1,                                                recorc
  ne day vnose Mt ,alue co.es closest „ ^ eri           «
  -erase scream low ,nd supplen,entary uater quality Parameter"-'
 occurr.n, over ,„. «QC averagin, period  stamina on tnis day -
 -ed as cne design conditions  ,S8e pane! 4 of ruure " I,     '

     one result  or  -his procedure is tnat analyses made on dif-

      "" '                                             "
                                                    -
                 :, „ Oe expected because tne critical condi,
                .,xrm osaai
-------
                             SECTION 4
                       EXAMPLE CASE  STUDIES

      Two rivers located  in different geographic regions were <
 -.0 illustrate the calculation of design conditions using DESCt
 The Quinnipiac River in  Connecticut  is first analyzed in some
 detail  to give the reader  a step by  step guide to using the
 program.  Then results  for  a second river, the Uncompahgre in
 Colorado,  are summarized to illustrate how design conditions <
 change  under  a different hydrological  and climatological regii

 4.1  QUINNIPIAC RIVER

     The Quinnipiac  River  in Connecticut  is an example  of  a *s-
 where the  low  flow and high temperature seasons coincide.  Thu.<
 would expect  the critical design event for  most pollutants to
 i-n this period  (late summer to early fall).  The 7Qio  low  flow
 this river is approximately 32 cfs.

     DESCON was used to estimate design conditions for chronic
ammonia toxicity in this  river.  The 4-step  procedure  for usim
DESCON,  first presented in Section 1.3, was  followed  and is
 repeated here:

 1.   Select the pollutant and type of WQC to use.
2.   Retrieve historical  daily streamflow and water quality d;
using DESCON.
 3.   Assemble data or estimates for discharger  flow and perti;
water quality variables,  if possible.
4.   Run DESCON to find design streamflow and other pertinent
design conditions.

How each of these steps was applied to the  Quinnipiac River w
 be discussed  in the sections that  follow.
                                30

-------
   4.2 POLLUTANT AND WQC SELECTION
                               for
                               limit vas the
                                          r
    Averaging Period-
                                   4 days

    Excursion Frequency:
                                   once  every three years

    Length of time used to groun

    excursion periods into IfSf.r.:   120 days


    Maximum number of excursions

           counted per cluster-      5
                                         =
            excursions.


4,3 RETRIEVAL OF STREAM DATA



     The first operation performed with DESCON ir«,*



™ir::r"r:n: r/ro- — • ™-  -" -
over and over aas i n  i r,          S   LOW-°ATA and could be use
             u-sjain  i £i SLLDSS^XIgn't d@<5 i CTTI
*"    triis strsajn ""^11 c «-^«.*. •   .                    ^^-^cuxa-tiion
            ^-  -hxs oartzcular example used the flow records


                             31

-------
  QSGS gage number 01196500 Locared near Wailingford, Connectic
  Figure B.l in Appendix B depicts the dialogue used with DESCC
  perform this retrieval.

       The supplementary design condition variables for ammonia
  include temperature,  pH,  and, since discharger data was provi
  tor this example,  alkalinity and upstream ammonia (see Table
  The DESCON user must  be  prepared to provide  representative da
  values  of these quantities at various  times  of the year.  To a
  in  this cask,  DESCON  vas  asked to  retrieve selected water qua
  data from STORET.  mis data  was  automatically  saved in a  file
  ?ARAM.DATA.  Fiaure 3.2 illustrates  how this  retrieval vas ma
  ror  -his  example.  ..-ater quality  data was  taken from che same
  .station that recorded the flow data.

      The  next r;-ep vas to perform further analysis on  the
  retrieved water quality data. For each parameter, DESCON dete
 how much data there vas,  how it varied from day to day and ye
 year, and whether its  daily variation could be represented wi
 sinusoidal function or not.  Figure B.3  shows  part of the dial
 used with DESCON to perform such an analysis  for temperature
 Quinnipiac.

      As  a result ot these analyses,  the daily variation in st
 temperature was represented by the following  sinusoidal funct

      T = 12.56  - 4.3sin(0.0172 d) - 10.6cos(0.0172 d)

.where T  is temperature (degrees C)  and  d is day of the year  <
 January  l being day l).  The coefficient of determination (i.e
 squared) of the fit for this  expression was 93  percent. DESCO
 was  instructed  to compute the temperature for each day of  the
 with this formula and  save the resulting values in a file  nam
 STREAM.DATA.  These daily  temperature values are depicted in
 rigure 4.1.

                                32

-------
             a I-
FIGDRE  4.1
                               3v f*~ ^ _•  ~~
                              _nr Cr i -s Y~=S
                                          Quinni?iac  River
                          '50   200    a

                          DRY CP T>€ Ye^
30    -0
     .4.2
                     ln ~he Q^innipiac  River


                                33

-------
                             flLKflLINITY
            SCI-

            SCr
         =  33 F
                               -     ,
                                -  -   -
                                  -  ip-y n
'50   230   20
r«v CF r
                                            333
FIGURE 4.3   Daily Alkalinity in tha Quinnipiac River
        i  32 f-


        a   °*
        S  151-
        §    i
        ua  IQj-
             I
             I

           si-
             t
             i
                  50
                       IQQ    150    208    2SQ
                            CflY 0= TV
                  30D
       4.4   Daily Temperature of Discharge to the  Quinnipiac
                                  34

-------
"'=
compucations.
4-4 SPECIFICATION OF DISCHARGER
                       DAT7V
                  aata. rnererore DESC-DM T.-., •

                                   "';r"
                                ~~ - =
                                     ;  : =

          "
  OH
                        7Q1°
  Alkalinity = 245 mg/L as CaC03

                     35

-------
 4.5 "COMPUTATION OF DESIGN CONDITIONS

      At this point of the analysis the following preliminary
 nad been carried out:
 1.    Daily streamtlev data were extracted from STORET and pla
 in  the file FLOW.DATA.
 Oaily water quality parameter data were extracted from
 STORET and placed  in the file PARAM.DATA.
 3.    The water  quality  data in file PARAM.DATA were converted
 into representar. ive daily values  of stream temperature,
 pH,  and alkalinity vnich were then stored  in the  file
 STREAM.DATA.
 4.    Representative   iaily discharger  data for  flow,  -emperat
 ?H,  and alkalinity vere  specified.
 With this data  on  hand,  DESCON was  ready to  compute design
 conditions.

      Figure 4.5 below presents a summary of  the input data fe
 DESCON and the  resulting design conditions that it computed.
entire  interactive dialogue is shown in Figure B.4 of Appendi
The  critical conditions were observed to occur in July at a
critical ammonia loading of 1.9 mg/L from the discharger. The
 resulting design conditions were:

   Parameter              Upstream         Discharge
Flow, cfs
Temperature, deg c
PH
Alkalinity, mg/L
Ammonia, mg/L
34.8
23., 9
7.6
72.2
0.0
32. 0
25.0
7. 0
245 . 0
1.9
The WQC excursions produced by this loading are shown in Figu
4.6. The most severe excursion occurred during seven days in
of 1936. The most prolonged excursion occurred during the sum
of 1966.
                                36

-------
      LOCATION
      POLLUTANT
                          fL°F DESCON INPUT DATA
     FLOW ADJUSTMENT
           	.-.jv_/-vi iUN
           OF UPSTREAM  oOLrrr-mnTm
           II $ sss H™-
    ««« or


I   DISCHARGE ALKALINITY, MG/L
:  YES

-•  BIOLOGICALLY-BASED
:     4.0
     3.0
  EPA NATIONAL CCC
  ENTIRE RECORD
     1.0
 BELOW  FLOW GAGE
u
]
L

25
32.
14.
7.
245.
. u
• *-
. 5
.0
.0
,2
0
0
TO
TO
70
TO
TO
TO
TO
TO
')
"* f
— t
3
36,
32.
25.
245.
.0
.0
-»
.0
.0
3
n
\j
0
MG/L
DEC.

MG/L
CFS
DEC.
MG/L

/^

C

                                           25
          1957.
          34. 8
           0.0
          23.9
           7.6
          72.2
          32.0
           1.9
          25.0
           7.0
        245.0
                                         ln
                               37

-------
         HISTORICAL EXCURSIONS. FOR PERIOD 1931 -  1986
EXCURSION CLUSTERS
riUMBER OF !
EXCURSION PERIODS
DURATION
START DATE LXCURSIONS ,' START DATE
.TUL
UL
t/G
UL
AUG
AUG
JUL



AUG

AUG

21, 1932
2~ , 1933
Li, .936
25, 1941
-. 1955
4, 1957
11, 1966



1, 1970

16 , 1986
TOTAL
1.50 i JUL
i. oo ; JUL
.." ' AUG
-.00
I. 00
i.OO
5.00



2.25

1.00
15.50
JUL
AUG
AUG
JUL.
JUL
AUG
SEP
AUG
AUG
AUG
21,
27 ,
14,
25 ,
4,
8,
11,
30,
18,
6,
1,
13,
16,
1932
1933
1936
1941
1955
1957
1966
1966
1966
1966
1970
1970
1986
( DAYS )
6
4
-
4
4
4
18
16
18
6
4
5
4
MAGNITUDE*
t
-s
o
"> 1
1.
-1
£. .
0.
9.
16.
17.
9.
3.
5 .
3.
. 6
. 4
1.
1
5
2
2
£.
3
3
0
8
0

   * I BY WHICH CRITERION CONCENTRATION IS EXCEEDED

FIGURE 4.6  WQC Excursions Under Ammonia Design Conditions
                                38

-------

r ,™;:::r::, — r:r— r=t r - «






^•6  DESIGN CONDITIONS FOR OTHER POLLUTANTS

                39.

-------
 TABLE 4.1  Comparison of Design Conditions  for  Ammonia in t.H.»
            Quinnipiac River
                           4-Day Averages
                         Upstream  Discharge
                   30-Day Average:
                  ."pstream  Dischc
A. Biologically-Based WQC
Critical Period
Flow, cfs
Temperature, uea.
?H
Alkalinity, :ng L
Ammonia, mg/L
Excursion
July
34.8
23.9
~. 6

0.0
Method
July
32.0
25.0
~. 0

1. 9

July
54.4
23.5
n fl ^ "•
J O • J ^
3. Extreme .Value-3ased WQC Excursion Method
Critical Period
Flow, cfs
Temperature,  lea.
PH
Alkalinity, :ng/L
Ammonia, mg/L
July
35.9
23.7
 7.2
70.3
 0.0
 July
 32.0
 24.4
  7.0
245.0
  1.9
July
48. 7
23.3
 ~ . 4
;o.o
 o.o
                                40

-------
                                                ln  ,,
location

Pollutant


   Coefficient a-  -
  Averaging Period,  .-.-ays


  Return Period, y9ars


  Concentration Limit.


  Period of Recora

  flow Adjustment Factor

  Discharger Location






 Range  of  Discharae Flow
 Ra£a*  °5  Disc^rgf ~
 Range  of  Discharge
.«**•  of  Discharge Diss".  Oxygen
••  Quinnipiac R at Wall

  :  Lead
    UOD

  •'  0.23  I/days
  :  0.46  I/days
  =  0.0 mg/L/day

 •• 4 (Bio-Based Method)
    ' (Extreme Value Method)
                                 ''  in  ,^io-Based Method)
                                   10  (Extreme value Method)

                                 : EPA National c^c
                                ••  Entire Record

                                :  1.0
selow Flow Gage
0.0
l o
x • \J
39.0
4.2
32.0
14.2
250.0
5.5
1 to
to
^o
CO
to
to
to
to
o.o
24.0
'.20.0
15.0
32.0
25'. 3
250.0
5.5
mg/L
Deg.
mg/L
mg/L
- IS
Deg.
mg/L
mg/L

                             41

-------
  TABLE  4.3  Design Conditions for Ammonia, Lead, and UOD in
            the Quinnipiac River
 A. Biologically-Based  WQC  Excursion Method (4-Day Averages)
                               UPSTREAM
                           NH3  Lead    CJOD
                          DISCHARGE
                       NH3  Lead   UC
 Critical Period
 Flow, cfs
 Temperature,  cleg.  •_•
 PH
 Alkalinity, mg/L
 Hardness,  mg/L
 Diss.  Oxygen,  :r.g/L
 Pollut.  Concen., rng/L
 July August August
 34.8  17.4  37.1
 -3.9    -   23.6
  7.6
 72.2
   -   103.8
              7.0
  0.0   0.0    0.0
  July August Auc
  32.0  32.0  32.
  -5.0    -   25.
   7.0    -   '  -
 245.0
    -   250.0
                                                1.9  11.9  21.
                                                    (ug/L)
B. Extreme  Value-Based WQC Excursion Method (7-Day Averages)
Critical Period
Flow, cfs
Temperature, deg. c
PH
Alkalinity, mg/L
Hardness, mg/L
Diss. Oxygen, mg/L
Pollut.  Concen., mg/L
    UPSTREAM
 NH3  Lead   UOD
July August August
35.9  23.8  38.7
23.7    -   23.6
 7.2
70.3
      97.6
              7.3
 0.0   0.0    0.0
     DISCHARGE
  NH3  Lead   UC
 July August Auc
 32.0  32.0  32,
 24.4    -   25.
  7.0
245.0
   -  250.0
                                                1.9   12.2   22,
                                                    (ug/L)
                                42

-------
4-7
        UNCOMPAHGRE
                RIVER

                                WQC
      "o.
         ,nd
                         .
              Tne
 river resuic ln
differences

         HOC .xeur.t™
                                                         river v«

                                                       Quinnipiac

                                                  cor.si=sraoly
                                                  for
                                                           is

                                                  »-»«««„
                               43

-------
 TABLE 4.4  DESCON  Input: Data  for  the  Uncompahgre River
 Location

 Pollutant
 Kl Coefficient at 20 Deg. C
 :^2 Coefficient .jt .10 Deg. C
 Benthic Demand .it 20 Deg. C

 \veraaing Period, ir^vs
 Return  Period,  rears


 Concentration Limit



 Period of Record

 Flow Adjustment Factor

 Discharger Location
Range of
Range of
Range of
Range of
Range of
Range of

Range of
Range of
Range of
Range of
Range of
Range of
Upstream
Upstream
Upstream
Upstream
Upstream
Upstream
Pollutant
Temperature
PH
Alkalinity
Hardness
Diss. Oxygen
Discharge Flow
Discharge Temperature
Discharge PH
Discharge Alkalinity
Discharge Hardness
Discharge Diss. Oxygen
                           Uncompahgre R at  Delta,  CO

                           Ammonia
                           Lead
                           UOD

                           0.23 I/days  '
                           0.46 1/days
                           0.0 mg/L/day

                           4 (Bio-Based Method)
                           7 (Extreme Value Method)

                            3  (Bio-Based  Method)
                           10  (Extreme Value  Method)

                           EPA National CCC (Ammonia)
                           EPA National CCC (Lead)
                           5.0  mg/L          (UOD)
Entire
1.0
Below
0.0
1.3
7.1
100.0
300.0
7.4
51.0
14.2
7.0
245.0
250.0
5.5
Recc

Flow
to
to
to
to
CO
to
to
to
to
to
to
to
rd

Gage
0.0
13.2
8.7
272.0
1300.0
13.6
51.0
25. 3
7.0
245.0'
250.0
5. 5



mg/L
Deg.

mg/L
mg/L
mg/L
cfs
Deg.

mg/L
mg/L
mg/L
                                -V4

-------
   19VBF P* A.
  Critical Period
  Flow, cfs
  Temperature, ciea.  _•
  PH
  Alkalinity, .-TIQ/L
  Hardness,  :ng/L
  3iss.  Oxygen,  -a/L
  Poliut.  concen.,  :na/L

 B.
 Critical Period
 Flow,  cfs
 Temperature, deg.  c
 PH
 Alkalinity,  mg/L
 Hardness,  mg/L
 Diss.  Oxygen,  mg/L
.Poliut.  Concen., mg/L
                         ,QC
                                UPSTREAM
                                  Lead
August April
  91.8  64.6  96.8
  17.8    -   17.9
   7.6

    -   367.5
              7.7
  °-0   0.0   0.0
     UPSTREAM
  NH3   Lead   UOD
 July April  July
 89.4   56.7  97.1
 18.0
  8.1
208.8
             18-0
  -  433.6
                           0.0    0.0
              7.8
              o.O
                                                  .  "d U
                                                            in
                            DISCHARGE
                        NH3   Lead   L'O
                        51.0  51.0  51.
                        25.3    -   24.
                         7.0
                       US.O
                          -   :5o.o
                                    5 .
                        3-3  31.1  39.
                                                    OISCHARGE
                                                      Lead   CIO
 July April   Jul
 51.0  51.0   51.'
 24.7    -    24.
  ~ .0
245.0
   -  250.0
              5 .
  3.3  32.8  39.
      (ug/L)
                                45

-------
                             SECTION 5
                       UTILIZATION GUIDELINES

      This section provides some useful guidelines  for  utilizir
 DESCON. in the «LA process. It covers such topics as  input  data
 •v/ai lability, choice of analysis options, and the  interpretat:
 of the program's results.  A question and answer format  is  usec
 simplify the presentation.

 5.1 DATA AVAILABILITY

 '}: Tan DESCON he -..'ied if no streamflow data or water auaiity
 -nrameter riata •*:•:::;-.  -?r -.he site in question?

 A: DESCON cannot  ue used if streamflow data do not  exist,  if r
 on some water  'Tiialir.y  variables  (such  as  temperature) are
 unavailable,  :-  :nay ce  possible  to  substitute values  from  anot
 river which  in c i imato logically  and hydrologically  similar.

Q: Suppose a streamflow record exists but the gage  LS not  cioj
 the site being .i
A: OESCON allows the user to specify a streamflow  adjustment
ractor, r, so -hat "ite streamflow can be  related  to  recorded
streamflow as follows:

       Daily Site Streamflow  =  F *. Daily Gage  Streamflow

The factor F is usually established as the ratio of  the  upstr<
drainage area of the site to that of the gage  location.   In
addition, if the gage is Located downstream of  the discharger
DESCON win adjust the streamflow records  to account  for the
discharge flow when computing an upstream  design flow.
                                46

-------
Q: >*at minimum length of flow record is recommended?





A: Th. longer ,ne  flow record.  the  more  reliable
                                    vin b. r
                  "
          .aiue ,uaivsis  at  a  10-year return peri
                                period.
-™ =

                                     •-•»
                  the record of

                      =


                47

-------
      50 r


      50
      30 i-

                          20       30


                        YEARS CF RECORD
40
FIGURE S.I  Spread  in  90  Percent Confidence Limits on
            a 10-Year  Return  Period Quantile
                                -18

-------
       OESCON will »^
                                monthly =«a-<
         or
 «
 «   - o«n£;T58::r in tt- —- —
 . oaem c« „.
           optio  o

A: I? th« WLA
                     49

-------
  cr.at«d
            a,  .  c=n..rvativ.  zat.rial
              an.ly,.s
                                           («,  .
                                             *
                                                           "


only d.,ign
         '
                                                 -- -'=r vhich
:  Strictly  spring,  canputation



                              5C

-------

    rog.nous  coa0n.                           carbonaceous
=.
s«=arat.
                    carh!n            '  ?r°?'r  ac=— -•'-  «*
                    =arfccnac.cu, and nitrog.nous  300  =c=?or.e,
S.3 **,AJ1JU.K1^,W«» OF RESULTS


             ,                          .       -  -
          b,.«j- on a
       =,„  .nt.r „.
                                              flow)  and a

-------
 that the applicable WQC is met under  the  critical pollutant 1
 and specified design stream-low.

       DESCON. can  also be  us*d  to  compute "srand-aior.*"  das
 srraamJlows,  «irh«r axrrsaa valu«-bas«d  flows such as a  TQIC
 biologically-basad  flows,  in  ta«  saa*  aanr.ar  as  a  =r«Ci
 softvar.  pacJcag.  called  DFLOW (US  EPA,  1986C) .   To  do this
 us.r would choosa  eh.  following options from rh« program's  =ar.
 1. Pollutant to b« analyzad 	 ganeral toxicant,
 2. Mathod of  dafining WQC axcursion fraquancy 	 either axtr
   valua or biologically-basad,
3. WQC concantration limit 	 any valu« will do (a.g., i uc/l
4. Include tha effects of a discharger 	 no.

-------
                            SECTION 6


                           REFERENCES
        D.P.,  stedinger, J.R.,  and  Haith       f
   ;enig 01   • •                  «"«*  naj.cn,  u.A,  Ivater  agoi.—^.


Cliffs,  NJ,  1981.              '  Prentlce~Ha11'  Inc.,  Znglewoo

                      ality
                                    January, 1933
                                January,  l9S5(a).
                      Quallty criteru for
                      :; Mrr Tlations
                      m,  D.C., January,  i985 (d)
                                                           an
                            53

-------
  U.S.  EPA,  "Ambient  Water  Quality Criteria for Lead - 1984"
  EPA 440/5-84-027, office  of Water Regulations and Standards,
  Office of water, Washington, C.C., January,  1985(e).

  U.S. EPA, "Technical Support Document  for Water Quality-based
  Toxics Control", Office of Water, Washington,  D.C.,
  September,  1985(f).

 U.S.  EPA, "Water Quality Criteria; Ambient Aquatic Life Water
 Quality Criteria Documents",  Federal  Baqf^yj.  Vol.  51(47):
 3361,  March 11,  1986(a).

 -.S. E?A, "Water  Quality Criteria; Request For Comments"
 Federal PPCTHI-T, Vol.  51(102) :19269, May 28,  1986(b).

U.S. EPA, '"Technical Guidance  Manual  for Performing Waste  Loac
Allocation,  Book  VI,  Design  Conditions: Chapter  1, stream  Desigr
Flow for  Steady-state Modeling",  office of Water Regulations  anc
Standards, office of Water, Washington,  D.C., August, I986(c)
                               54

-------
                            APPENDIX A
                       WATER QUALITY CRITERIA







I.  Ammonia (us EPA, isssa)
                         Criterio" ***i*um Concentration (CMC>  c
where
 CMCo


   FT
                     0.52 / FT / FPH / 2.


                     10 -5.03 (20 - T*} J
                                                     20
                                                         25
              PH*
                    pH if pH

                    6-5 otherwise
                                            c,ncen««ian  (ccc
               T*
             FPH

               *
       15  if salmonids present and T >

       T°o^erwisridS n0t *«•-* «
       as  above
                   IS. otherwise
                                                      <*
CCC
                   0.322 CMCo /
                   0.822 CCCO /
 Heavy  Metals

-------
                 CMC cr CCC = exp[a LJf(H)  - b]   (ug/L)

  where  the constants "a"  and »b»  are given by:
 Metal
                      CMC
                                      CCC
                                                  Reference
1.123
.9422
.3190
1.273
.3460
.3213
-3.323
-1.464
3.638
-1.460
3.3612
.3141
.7852
.3545
.8190
1.273
.3460
.8213
-3.490
-1.465
1.561
-4.705
.5703
-.1541
US EPA,
US EPA,
US EPA,
US EPA,
US EPA,
US EPA,
1985b
1985c
1935d
1985e
1986a
1986b
 Cadmium
 Copper
 Chromium  (III)
 Lead
 .Vickel
 Zinc

 ril.  Pentachlorcphenoi (US EPA.  1986a)

      The WQC for centachlorophenol is a function of pH:
CMC = exp[1.005 PH - 4.954]
CCC = expC1.005 PH - 5.412]
                                             (ug/L)
                                             (ug/L)
IV. Ultimate Oxygen Demand
                                       °°O
                .   .                    P
to determine  he maximum Initial £ ISH  #£* m°del Ca" be  uset
results in a DO just eoual ta rho   *+ *** UOD con=entration  tha-
of the downstream DO pSJile?     critarion at the critical poin-
                                                     for COO.
 where

 and

 with
          Cs - Cc  =
Tc
                 L
                Co
                Cc
                Cs
                T
               Kl
              Klo
[S/K2][1 - exp(-K2 Tc)]

 Ln[(K2/Kl)(1 + Y/L)]

 CO/K2)  - Cs 4- Co]  [R2  - Kl]  / Kl

 initial UOD
 initial DO
 DO  criterion
 saturation DO

 -4:oo^4l°?V *  -007991 T'2
 temperature
 Klo  1.024*(T - 20)
 UOD  decay rate coefficient  at 20  deg.  c

-------
                 «  ,  K20 1.047-(T  -  20)

                                VIV*"81-'  «  20 deg. c
                                 DO  de.and (mg/t/day) ^ ^
               -
   Mixing Equations
                ^J   =  :ci  QI
••n.r.            C1   m
                C2   =
                       "=concentration (or
               Ql  -  upstream flow
               v  =  discharger flow.


                                   S : :
                                   fractions  cn
               5   :    '
             CT1  =  Al / F1

-------
                 CT2
                         A2 / F2
4. Find the downstream temperature (T3>  aiieaii«<+.,, /,.,,
total inorganic  carbon (CT3) :             aiJcalinity (A3), and
                 T3
                 A3
                CT3
T2 Q2) /  (Ql  +  Q2)
A2 Q2) /  (Ql  *  Q2)
 CT2 Q2) /  (Ql  *  Q2)
                      3   (Tl Ql -

                      =   (CT1 Ql

5. Find the  downstream ionization constant  (PKA3):

                PKA3   »  6.57 - .0113 T3 -(• .00012 T3'2

5. Find the downstream pH (PH3):

                ?H3   =  ?RA3  - LoglO(CT3/A3 - 1)

-------
                              APPENDIX B
                     HOW TO RUN THE DESCON PROGRAM

       The main DESCON menu is shown in Fiaure B l  -„„
       aUie as . roiiw                                    option?
     1- Retrieve  now data  from STORET
     -• Retrieve v.icer quality data  from  STORET
     3- Analyze retrieved water quality data
    4. Calculate design conditions  •
    5- Exit -he program
      oe  tne  fl      our  u     Be
                          reouired  i
named
runs.                          —**jr accessed on any  future  or
                               60

-------
              D  E  S' C  0  N    MAIN    MENU



    ENTER THE OTMBER  OF  THE  PROCEDURE YOU WISH TO EXECUTE;

    i - RETRIEVE STREAMFLOW  DATA
    - - RETRIEVE WATER QUALITY DATA
    3 - ANALYZE WATER QUALITY DATA
    4 - COMPUTE DESIGN CONDITIONS
    5 - EXIT THE PROGRAM

    CHOICE = = «    i



    ENTER  3-DIGIT  "SGS STATION NUMBER ===== >  01196500

    ENTER  _ -DIGIT  STORET STATE CODE  =====,  09

    SAVED
    JOB XXX(JOB01234)  SUBMITTED
    FLOW DATA WILL  BE  STORED  IN FILE FLOW.DATA
FIGURE B.l  streamrlow Retrieval With DESCON
                                61

-------
second one 'on f-

    data  are





       vai or .-;•:





third
              n
             in a
                                       ^  °"
                                    named PARAM.DATA.
                                            """
  Period of r.=ord  -.

              asona/  oa
              (or  ;
                   8 ="<=««« over my sp.ci(1.,

                              oe
                                        in.-a file
                        —
                                          can  be
.
This  data is
          iah,
            '   to DESCON
            to
      are  placed  in
                                 Cype of t»"«aj
                                      5 ic in a '
                                       case,  str«
                   62 .

-------
               DESCON    MAIN    MENU
    ==-«=-=-=«== = = « = = = «=«=„„„_„_„„„„_.,._,.__,_____

    INTER THE NUMBER OF THE  PROCEDURE YOU WISH TO EXECUTE:

    I - RETRIEVE STREAMFLOW  DATA
    2 - RETRIEVE WATER QUALITY DATA
    3 - ANALYZE WATER QUALITY DATA
    4 - COMPUTE DESIGN CONDITIONS
    5 - EXIT THE PROGRAM

    CHOICE = = = •    2


    ENTER  5 -CHARACTER  MONITORING STATION AGENCY CODE   112WRD

    INTER  S-DIG:T MONITORING STATION NUMBER ==== -    ougesoo

    STORET CODES  FOR PARAMETERS OF MOST INTEREST
     WATER  TEMPERATURE, DEC C                10
     DISSOLVED OXYGEN, MG/L                300

     ALKALINITY, MG/L CACO3                 JJo
     TOTAL  AMMONIA, MG/L N                 608
     TOTAL  HARDNESS, MG/L  CACO3             900
         ™E STORET CODES OF THE PARAMETERS YOU WISH TO
   RETRIEVE  ALL ON ONE LINE ENCLOSED  IN QUOTES WITH FORMAT-
    P =  CODE L  . P =  CODE 2> , ... ETC. '

   'P=LO ,P=300 ,P=400 ,P=410 ,P=900 '

   SAVED
   JOB XXX ( JOBOL235 )  SUBMITTED
   PARAMETER DATA WILL BE STORED IN FILE PARAM DATA
FIGURE B.z  water Quality Data Retrieval with
DESCON
                                63

-------
       THE Cr
                     THE
              STREAMFLOW DATA
   -
CHOICE ===
STATION MO. -1196500
      00400
                            . CT
                                    MG/L
                                     sir

3
4
5
6
          A HONTHLY
  PRODUCE A DAILY SUMMARY
  FIT A SEASONAL MODEL
  SET CUT-OFF LIMITS
  RETURN TO MAIN MENU
2
3
4
5
t>
1
00030
00400
00410
00900

DO
PH
T ALK
T HARD

TEMP

CACO3
CACO3

CENT
MG/L
SU
MG/L
MG/L

  B,
                of
                           64

-------
    WHAT ARE THE  "RST  i  LAST YEARS OF PERIOD ANALYZED
    'ENTER  1000,  .099 FOR ENTIRE PERIOD OF RECORD)

    L970, 1999
    SUMMARY BY YEAR OF WATER       TEMP
YEAR
L970
L971
1972
1973
iGRABS :•'
15 : 4
13 .3
12 .0
14 :;
;EAN ^COMPOSITES MEAN
.5
.3
.3
. 6
..ata
1985
1986
12 : 4
14
. 9
. 4
0
0
0
0
:or 1974 -
0
0
0
0
0
0
1984 not
0
0
OVERALL VALUES
MIN MAX MEAN
1.0
2.0
2. 0
1.0
shown
1.5
4.0
30.0
27.0
21.0
26.0

23.0
22.0
14.
13.
10 .
14.

14.
14.
5
8
3
6

9
4
   HOW SHOULD  THE  //ATER QUALITY DATA BE ANALYZED-
   1  PRODUCE  A  YEARLY SUMMARY
   2  PRODUCE  A  MONTHLY SUMMARY
   3  PRODUCE  A  DAILY  SUMMARY
   4  FIT A SEASONAL MODEL
   5  SET CUT-OFF  LIMITS
   6  RETURN TO  MAIN MENU
   WHICH PARAMETER DO  YOU WISH TO ANALYZE

   1

   WHAT ARE FIRST > LAST YEARS OF PERIOD ANALYZED
   (ENTER 1900, 1999 FOR ENTIRE PERIOD OF RECORD)

   1970, 1999
FIGURE B.3  •Jontinued  from  previous page.

                                65

-------
       INCLUDE WHICH TYPE 0F SAMPLE:

      -  COMPOSITE
      3  BOTH
 2  NO

 2


     MEAN
 35


 JO


 :s   -
     i
 20


 15  -


10  -
    I

 5   -   *
    ;   *
 o   ***+*_
                    THE DATA:
VALUES  (1970-1999)  OF WATER  T
                                                          EMP
                               *•+  *++•
                                *  *-t.
                               ••••»•+  -t-
                        s
   i
   6  RETURN TO MAIN MENU

riGUREB.3
                       from previous page.

-------
    :-/HICH PARAMETER DO YOU WISH TO ANALYZE:

    1

    WHAT  ARE FIRST i LAST YEARS OF PERIOD ANALYZED
    (ENTER 1900,  1999 FOR ENTIRE PERIOD OF RECORD)

    1970,  1999

    INCLUDE  WHICH TYPE OF SAMPLE:
    1  GRAB
    2  COMPOSITE
    3  BOTH
   LOG TRANSFORM THE  DATA:
   1  VES
   USE WHICH TYPE OF SEASONALITY MODEL
   L  NONE
   2'  MONTHLY
   3  DAILY
   4  SINUSOUDAL
          RESULTS OF SINUSOIDAL SEASONAL MODEL  FOR
          DAILY VALUES (1970-1999) OF WATER   TEMP

          FITTED PARAMETER VALUE Y ON DAY D  IS:

          Y = A * SIN(.0172*D) * B * COS(.0172*D)  -
          WHERE
                  A
                  B
                  C
         STD . ERROR
         !. R-SQUARED
     * OBSERVATIONS
   MEAN MODEL ERROR
COEFF. OF VARIATION  =  0.1706
    GOODNESS OF  FIT  =     15%
                             -4.292
                             -10.55
                              12.56
                              2.201
                              93.24
                                206
                             0.0000
FIGURE B.3  Continued  from previous  page.
                                67

-------
                 SEASONALLY MODEL  TO  SAME DATA
       HO
    :   FIT A SEASONAL MODEL
    a   SET CUT-OFF LIMITS
    o   RETURN TO  MAIN MENU
FIGURE B.3  continued from previous page.
                               68

-------
 TABLE B.I
Pollutants and Design Conditions Considered Bv
DESCON
 Pollutant
              Design Conditions
       •/o Discharger       v/ Discharger
 General
 toxicant

 Ammonia
Heavy Metals
  Cadmium
  Chromium III
  Copper
  Lead
  Nickel
  Zinc

Pentachlorophenoi
Ultimate Oxygen
Demand
           Flow
                       Flow
                       Temperature
                       pH
          Flow
          Hardness
          Flow
          PH
          Flow
          Temperature
          Dissolved
          oxygen
 Flow
 Toxicant

 Flow
 Temperature
 OH
 Alkalinity
 Ammonia

 Flow
 Hardness
 Metal
Flow
PH
Temperature
Alkalinity
Pentachlorophenol

Flow
Temperature
Dissolved
oxygen
UOD
                                69

-------
                                 «»"«Y
                     Water Quality Values"
 Pollutant
General
Toxicant
                     -„
                     -n-scream
Heavy
Pentachloro-
pnenoi
                   remperature
                   pH
                 PH
                                   Toxicant
 Temperature
 PH

 Alkalinity
 Ammonia


 Hardness
 Metal

 PH

 Temperature
 Alkalinity
 Pentachloro-
 phenol


Temperature
Oxygen
UOD
                                                   aaquired ay
                                                   to DESCON
                   Discharge



                   Flow
 Temperatur
 PH

 Alkalinity
 Flow


 Hardness
 Flow


PH
Tsmperatur
Alkalinity
Flow
                                                  Temperatur
                                                  Oxygen
                                                  Flow

-------
 rile Entry
                                      lomments
 Stream Data for Ouinnipiac River
 10
 1.
 0,0
 12
 1,15,1.8
 2,14,2.4
 3,15,4.3
 4,15,10.1
 5,15,15.4
 6,15,21.3
 7,15,23.9
 3,15,24.5
 9,15,20.0
 10,15,14.3
 -1,17,5.9
 12,15,3.2
 400

 o'.o
 12
 1,15,7.2
 2,14,7.2
 3,15,7.2
 4,15,7.1
 5,15.7.1
 6,15,7.1
 7,15,7.2
 8,15 ,6.9
 9,15,7.0
 10,15,7.2
 11,15 ,7.0
 12,15,7.1
 Tile header
 STORET parameter code
 Nominal parameter value*
 Random variability factor
 Number of seasonal factor
 Month, day, seasonal fact
Next parameter code
Nominal parameter value
Random variability factor
Number of seasonal factor
Month, day, seasonal  fact.
lThe actual parameter value for a given day of  the  year  equal
the nominal parameter value times a seasonal  factor for  that

2These factors indicate the type of random variability to  into.
 around the deterministic  -nnual cycle of parameter values  "
 -eroes indicate that no random variability is  to be 'ncluded
FIGURE B.4  Format of Files STREAM.DATA and  DISCH.DATA
                                71

-------
                          - ••«- •-
                L.  31,  2.i

                -  1. J.4

                --  -3,  J.4

                •5CC.
Using fiies STREAM. DATA and DISCH
                               DATA
                          -
.. „.„,„„
                            «""" — •
=


-------
      The results for this run are displayed  in  Figure  B.6.  Af
 the table of critical design conditions appears  the  user  is
 presented with a menu that offers the following  additional  an
 option^:

  * viewing the dates and durations of the WQC excursions  that
    would have occurred over the historical flow record under
    current design loading,
  * computing alternative design conditions and a WQC excursio
    frequency for  a  user-specified design load,
  * computing alternative design conditions for a particular
    user-defined s-reamflow,
  * repeating r.r.e  analysis for a  new division  of  the year into
    different seasons.

figure B.6 concludes with the results of selecting  the  first
these options.

     One final operational reminder; at times  the program  wii
display the  following prompt:
and pause to allow the user to read the currently displayed c
Execution win resume when the Enter Jcey is pressed.
                               73

-------
 1
 2
 3
 4
 5
       THE NUMBER OF THE PROCEDURE YOU WISH TO EXECUTE:
      RETRIEVE STREAMFLOW DATA
      RETRIEVE WATER QUALITY DATA
      ANALYZE WATER QUALITY DATA
      COMPUTE DESIGN CONDITIONS
      EXIT  THE PROGRAM
CHOICE
( QUINNIPIAC
 2
 3
 4
 5-

 2
                  FOR
                           STATION 01196500
               c        BE
  AMMONIA-N
  HEAVY METAL
  PENTACHLOROPHENOL •
  ULTIMATE OXYGEN DEMAND
  NO
             OR OTHER COLD WATER SPECIES PRESENT

2
-)
2
  BIOLOGICALLY-BASED
                                                  Conditi'
                           74  '

-------
    USE DEFAULT DEFINITION OF EXCURSION PARAMETERS
    1  YES
    2  NO
    ENTER THE STARTING AND ENDING YEARS OF THE FLOW RECORD
    (ENTER 1900, 1999 TO INCLUDE ENTIRE RECORD)

    1900, 1999

    WHAT IS THE FLOW GAGE ADJUSTMENT FACTOR
    (WHERE SITE FLOW = FACTOR * GAGE FLOW)

    1.0

    WHERE IS  THE DISCHARGER  IN RELATION TO  THE FLOW GAGE
    1  ABOVE  THE GAGE
    2  BELOW  THE GAGE
    3  THERE  IS  NO DISCHARGER
    •
   WHAT IS SIZE OF MIXING ZONE  (% OF STREAM X-SECTION)

   100

   CONSIDER DAILY VARIABILITY OF EFFLUENT AMMONIA-N
   1  YES
   2  NO
FIGURE B.5  Continued from previous page.
                                75

-------
      NOMINAL YEAR-ROUND VALUE
      o
   •   2  NO
   :   i
     1  YES
     -  MO
                                       "^ABILITY or
              ^REAM'°ATA TO DESCRIBE VARIABILITY Or
    1  YES
    2  NO
    •>
    1
                                         TOR
    NOMINAL YEAR-ROUND VALUE

    32
          OF  DAILY  SEASONALLY FACTORS
                                INCLUDE
   2  LOGNORMAL
   3  NONE
                                                  or
FIGURE B.5  continued from previous page.
                                76

-------
    ENTER THE FOLLOWING  VARIABILITY DATA FOR
    DISCHARGER TEMPERATURE,  DEG C

    "EAR-ROUND NOMINAL VALUE
    •p

    1.


    NUMBER OF DAILY SEASONALITY FACTORS

    12


    MONTH,  DAY OF MONTH,  AND FACTOR VALUE FOR EACH


    J  fJ Jf'n    2 14 14>2    3  1S 14'8    4 1S 15'8
    I  II i?'S   ,n J5 21-5    7  1S 24-9    8 1S 25-3
    9  15 23.3   LO 15 23.1   11  15 21.7   12 15 17.8

    TYPE OF  RANDOM VARIATION TO INCLUDE
    1  NORMAL
    2  LOGNORMAL
    3  NONE
   ENTER THE FOLLOWING VARIABILITY DATA  FOR
   DISCHARGE PH


   NOMINAL YEAR-ROUND VALUE

   7.0


   NUMBER OF DAILY SEASONALITY FACTORS

   0


   TYPE OF RANDOM VARIATION TO INCLUDE
   1  NORMAL
   2  LOGNORMAL
   3  NONE
   •p

   3
FIGURE B.5  Continued from previous page.
                                77

-------

  NOMINAL YEAR-ROUND VALUE

  245

  NUMBER OF DAILY SEASONALITY FACTORS
                           TO INCLUDE
 -  LOGNORMAL
 3  NONE
 LOCATION
 POLLUTANT
              ,f^fL°LDESCON INPUT DATA
AVERAGING  PERIOD,  DAYS
RETURN PERIOD,  YEARS
CLUSTERING PERIOD  DAYS
MAX. EXCURSIONS PER CLUSTER
CONCENTRATION LIMIT CLUSTER
PERIOD OF  RECORD
FLOW, ADJUSTMENT FACTOR
DISCHARGER LOCATION
SIZE OF MIXING ZONE, %
             QOIT.
YES
BIOLOGICALLY-BASED
   4.0
   3.0
 120.0
   5.0
EPA NATIONAL CCC
ENTIRE RECORD
   1.0
BELOW FLOW GAGE
  100.0

 TO CONTINUE...
    B.5
         continued from previous
                                 page.
                            78

-------
    PARAMETER
                                 NOMINAL RANGE RANDOM VARIATIC
    UPSTREAM AMMONIA-N,  MG/L       0.0 -   0.0
    UPSTREAM TEMPERATURE,  DEC C    1.2 -  24.0
    UPSTREAM PH                    5.5-8.2
    UPSTREAM ALKALINITY, MG/L     25.0 -  86.0
    DISCHARGE FLOW,  CFS            32.0 -  32.0
    DISCHARGE TEMPERATURE,  DEC C  14.2 -  25.3
    DISCHARGE PH                    7.0-7.0
    DISCHARGE ALKALINITY, MG/L   245.0 - 245.0
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
   ENTER  "Q" TO QUIT, ANYHTING  ELSE TO CONTINUE...
   10 YEARS OF FLOW RECORD PROCESSED
   20 YEARS OF FLOW RECORD PROCESSED
   30 YEARS OF FLOW RECORD PROCESSED
   40 YEARS OF FLOW RECORD PROCESSED
   50 YEARS OF FLOW RECORD PROCESSED
   SHOULD A SEASONAL ANALYSIS BE MADE
   1  YES
   2  NO
FIGURE B.5  Continued from previous page.
                                79

-------
     PARAMETER
                     CRITICAL  DESIGN CONDITIONS
 UPSTREAM  FLOW, CFS

 iS  iF™MG/l
 nZSSS.  "^uraiY,
 "•tSCHARGE  AMMONIA-N
 DISCHARGE  FLOW, CFS
 DISCHARGE  TEMPERATE
 DISCHARGE  PH
SrtS^5 ALKALINITY,
                                          SEASON
                           DEG C
 APR
 APR
 APR
 APR
 APR
 APR
 APR
 APR
 APR
 APR
APR
APR
 -MAR
 -MAR
 MAR
 MAR
 MAR
-MAR
-MAR
 MAR
 MAR
 MAR
 MAR
 MAR
                                                   7-
      ortot ijc.5ir*w f^nivrr>TmT«mv« ~.          A'"• * *
    .              ^-«wux iiOrTS OM "* —^—~~
          ^"U"i*ilEx\ DE5*T7^TT*TO1^T rtr»
    Q  O E*TTT 11'-. m*       *•* ^i» J, i ^ Wi» \J f
 VALUE

  34.8
   0.0
  23.9
   7.6
  72.2
  '1.9
  32.0
  25.0
  7.0
 245.0
  1.0
 25-57

59.38
YEARS
FIGURE B.6
            Design Conditions  computed  by DESCON
                               80

-------
HISTORICAL EXCURSIONS FOR PERIOD 1931-1986
EXCURSION
START
JUL 21
JUL 27
AUG 14
JUL 25
AUG 4
AUG 8
JUL 11
DATE
, 1932
, 1933
, 1936
, 1941
, 1955
, 1957
, 1966
AUG 1, 1970
AUG 16, 1986
TOTAL
* % BY
WHICH
CLUSTERS
EXCURSION PERIODS
NUMBER OF DURATION
EXCURSIONS START DATE (DAYS) MAGNITUDE*
1.50 JUL 21,
1.00 JUL 27,
1.75 AUG 14,
1.00 I JUL 25,
1.00
1.00
5.00
2.25
1.00
15.50
AUG 4,
AUG 8,
JUL 11,
JUL 30,
AUG 18,
SEP 6,
AUG 1,
AUG 13,
AUG 16,
1932
1933
1936
1941
1955
1957
1966
1966
1966
1966
1970
1970
1986
6
4
7
4
4
4
18
16
18
6
4
5
4
4.6
0.4
21.1
1.1
2.5
0.2
9.2
16.2
17^
9.3
3.0
6.8
3.0

CRITERION CONCENTRATION IS
EXCEEDED

FIGURE B.6  Continued from previous page.
                                81

-------