United States         Effluent Guidelines Division     EPA-440/1-84/019-b3
Environmental Protection     WH-552           July 1984
Agency           Washington, D.C. 20460
Water and Waste Management
Development          Proposed
Document for
Effluent Limitations
Guidelines and
Standards for the

Nonferrous Metals

Point Source Category
Phase II
Supplemental Development
Document For:

Primary Precious Metals and Mercury

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                 DEVELOPMENT  DOCUMENT

                          for

    EFFLUENT LIMITATIONS  GUIDELINES  AND STANDARDS

                       for  the

NONFERROUS METALS MANUFACTURING  POINT SOURCE CATEGORY

                       PHASE  II

    Primary Precious Metals and  Mercury Supplement
                    Jack E.  Ravan
          Assistant Administrator  for  Water
                   Edwin L.  Johnson
                       Director
      Office of Water Regulations  and  Standards
                                                 protcction
                                               ;^' Srreet
                                               60604
              Jeffery D. Denit,  Director
             Effluent Guidelines  Division
              Ernst P. Hall, P.E.,  Chief
             Metals and Machinery  Branch
                James R. Berlow,  P.E.
              Technical Project Officer
                      July 1984
         U.S. Environmental Protection Agency
                   Office of Water
      Office of Water Regulations and Standards
             Effluent Guidelines Division
               Washington, D.C.  20460

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U,S- EnviKjreftsnto! Prot3o:!cn Agency

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                        TABLE OF CONTENTS


Section                                                     Page

I         SUMMARY AND CONCLUSIONS	      1

II        RECOMMENDATIONS	      5

          BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY 	      5
          BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY 	     11
          NSPS FOR THE PRIMARY PRECIOUS METALS AND
          MERCURY SUBCATEGORY	     15
          PSNS FOR THE PRIMARY PRECIOUS METALS AND
          MERCURY SUBCATEGORY	     20

III       INDUSTRY PROFILE 	     25

          DESCRIPTION OF PRIMARY PRECIOUS METALS
          PRODUCTION	     25
          RAW MATERIALS	     25
          SMELTING	-	     25
          GOLD-SILVER SEPARATION 	     26
          FURTHER PURIFICATION 	     26
          PROCESS WASTEWATER SOURCES 	     27
          DESCRIPTION OF PRIMARY MERCURY PRODUCTION. ...     27
          RAW MATERIALS	     27
          ROASTING	     27
          PROCESS WASTEWATER SOURCES 	     28
          OTHER WASTEWATER SOURCES	     28
          AGE, PRODUCTION,  AND PROCESS PROFILE 	     28

IV        SUBCATEGORIZATION	     37

          FACTORS CONSIDERED IN SUBCATEGORIZATION	     37
          FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY
          PRECIOUS METALS AND MERCURY SUBCATEGORY	     38
          OTHER FACTORS	     39
          PRODUCTION NORMALIZING PARAMETERS	     39

V         WATER USE AND WASTEWATER CHARACTERISTICS  ....     41 .

          WASTEWATER FLOW RATES	     42
          WASTEWATER CHARACTERISTICS DATA	     43
          DATA COLLECTION PORTFOLIOS 	     43
          FIELD SAMPLING DATA	     44

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                  TABLE OF CONTENTS (Continued)
Section
VI
VII
VIII
WASTEWATER CHARACTERISTICS AND FLOWS BY
SUBDIVISION	    45
SMELTER WET AIR POLLUTION CONTROL	    45
SILVER CHLORIDE REDUCTION SPENT SOLUTION ....    46
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL .  .    46
ELECTROLYTE PREPARATION WET AIR POLLUTION
CONTROL	    46
SILVER CRYSTAL WASH WATER	    46
GOLD SLIMES ACID WASH AND WATER RINSE	    47
CALCINER WET AIR POLLUTION CONTROL	    47
CALCINE QUENCH WATER 	    47
CALCINER STACK GAS CONTACT COOLING WATER ....    47
CONDENSER SLOWDOWN 	    48
MERCURY CLEANING BATH WATER	    48

SELECTION OF POLLUTANT PARAMETERS	    77

CONVENTIONAL POLLUTANT PARAMETERS	    77
TOXIC POLLUTANTS	    78
TOXIC POLLUTANTS NEVER DETECTED	    78
TOXIC POLLUTANTS NEVER FOUND ABOVE THEIR
ANALYTICAL QUANTIFICATION CONCENTRATION	    81
TOXIC POLLUTANTS PRESENT BELOW CONCENTRATIONS
ACHIEVABLE BY TREATMENT	    81
TOXIC POLLUTANTS DETECTED IN A SMALL NUMBER
OF SOURCES	    82
TOXIC POLLUTANTS SELECTED FOR FURTHER
CONSIDERATION IN ESTABLISHING LIMITATIONS
AND STANDARDS	    83

CONTROL AND TREATMENT TECHNOLOGIES 	    89

CURRENT CONTROL AND TREATMENT PRACTICES	    89
CONTROL AND TREATMENT OPTIONS	    90
OPTION A	    90
OPTION B	    90
OPTION C	    90

COSTS, ENERGY, AND NONWATER QUALITY ASPECTS. .  .    93

TREATMENT OPTIONS FOR EXISTING SOURCES 	    93
OPTION A	    93
OPTION B	    93
OPTION C	    93
                              LL

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Section
         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                  TABLE OF CONTENTS (Continued)
          COST METHODOLOGY	    94
          NONWATER QUALITY ASPECTS 	    94
          ENERGY REQUIREMENTS	    94
          SOLID WASTE	    94
          AIR POLLUTION	    94

IX        BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY
          AVAILABLE	    99

          TECHNICAL APPROACH TO BPT	    99
          INDUSTRY COST AND POLLUTANT REMOVAL ESTIMATES.  .   101
          BPT OPTION SELECTION 	   102
          WASTEWATER DISCHARGE RATES 	   102
          SMELTER WET AIR POLLUTION CONTROL	   102
          SILVER CHLORIDE REDUCTION SPENT SOLUTION ....   103
          ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL .  .   103
          ELECTROLYTE PREPARATION WET AIR POLLUTION
          CONTROL	   103
          SILVER CRYSTAL WASH WATER	   103
          GOLD SLIMES ACID WASH AND WATER RINSE	   103
          CALCINER WET AIR POLLUTION CONTROL 	   104
          CALCINE QUENCH WATER 	   104
          CALCINER STACK GAS CONTACT COOLING WATER ....   104
          CONDENSER SLOWDOWN 	   104
          MERCURY CLEANING BATH WATER	   104
          REGULATED POLLUTANT PARAMETERS 	   104
          EFFLUENT LIMITATIONS 	   105

X         BEST AVAILABLE TECHNOLOGY ECONOMICALLY
          ACHIEVABLE	   115

          TECHNICAL APPROACH TO BAT	   115
          OPTION A	   116
          OPTION B	   116

          Recycle of Water Used in Wet Air Pollution
          Control	   117

          OPTION C	   118
          INDUSTRY COST AND ENVIRONMENTAL BENEFITS ....   118
          POLLUTANT REMOVAL ESTIMATES	    118
          COMPLIANCE COSTS	   119
          BAT OPTION SELECTION 	    119
                              ill

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                  TABLE OF CONTENTS (Continued)
Section
XI
XII
WASTEWATER DISCHARGE RATES 	   120
SMELTER WET AIR POLLUTION CONTROL	   120
ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL .  .   120
CALCINER WET AIR POLLUTION CONTROL 	   121
REGULATED POLLUTANT PARAMETERS 	   121
EFFLUENT LIMITATIONS 	   122

NEW SOURCE PERFORMANCE STANDARDS 	   135

TECHNICAL APPROACH TO NSPS	   135
OPTION A	   135
OPTION B	   136
OPTION C	   136
NSPS OPTION SELECTION	   136
REGULATED POLLUTANT PARAMETERS 	   136
NEW SOURCE PERFORMANCE STANDARDS 	   136

PRETREATMENT STANDARDS 	   145

TECHNICAL APPROACH TO PRETREATMENT 	   145
PRETREATMENT STANDARDS FOR NEW SOURCES 	   146
OPTION A	   146
OPTION B	   146
OPTION C	   147
PSNS OPTION SELECTION	   147
REGULATED POLLUTANT PARAMETERS 	   147
PRETREATMENT STANDARDS 	   147
XIII
BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
153
                              IV

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY



                          LIST OF TABLES






Number                                                       Page
III-1
III-2
III-3
III-4
III-5
V-1
V-2
V-3
V-4
V-5
V-6
V-7
V-8
V-9
INITIAL OPERATION YEAR (RANGE) SUMMARY OF
PLANTS IN THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY BY DISCHARGE TYPE 	
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 	
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 	
PRODUCTION RANGES FOR THE PRIMARY PRECIOUS
METALS AND MERCURY SUBCATEGORY 	
SUMMARY OF PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY PROCESSES AND ASSOCIATED
WASTE STREAMS 	
WATER USE AND DISCHARGE RATES FOR
SMELTER WET AIR POLLUTION CONTROL. .......
WATER USE AND DISCHARGE RATES FOR
SILVER CHLORIDE REDUCTION SPENT SOLUTION ....
WATER USE AND DISCHARGE RATES FOR ELECTROLYTIC
CELLS WET AIR POLLUTION CONTROL 	
WATER USE AND DISCHARGE RATES FOR ELECTROLYTE
PREPARATION WET AIR POLLUTION CONTROL 	
WATER USE AND DISCHARGE RATES FOR
SILVER CRYSTAL WASH WATER 	
WATER USE AND DISCHARGE RATES FOR
GOLD SLIMES ACID WASH AND WATER RINSE 	 ;
WATER USE AND DISCHARGE RATES FOR
CALCINER WET AIR POLLUTION CONTROL 	
WATER USE AND DISCHARGE RATES FOR
CALCINE QUENCH WATER 	
WATER USE AND DISCHARGE RATES FOR
CALCINER STACK GAS CONTACT COOLING WATER ....
29
30
31
32
33
49
50
51
52
53
54
55
56
57

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                    LIST OF TABLES  (Continued)


Number                                                      Page

V-10      WATER USE AND DISCHARGE RATES FOR
          CONDENSER SLOWDOWN 	     58

V-11      WATER USE AND DISCHARGE RATES FOR
          MERCURY CLEANING BATH-WATER	     59

V-12      PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
          SAMPLING DATA CALCINER WET AIR POLLUTION CONTROL
          RAW WASTEWATER	     60

V-13      PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
          SAMPLING DATA CALCINE QUENCH WATER
          RAW WASTEWATER	     66

V-14      PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
          SAMPLING DATA CALCINER STACK GAS CONTACT
          COOLING DATA RAW WASTEWATER	     69

V-15      PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
          SAMPLING DATA MERCURY CLEANING BATH WATER
          RAW WASTEWATER	     72

VI-1      FREQUENCY OF OCCURRENCE OF TOXIC POLLUTANTS
          PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
          RAW WASTEWATER	     85

VI1-1     SUMMARY OF WASTE STREAMS AND TREATMENT
          PRACTICES IN PRIMARY PRECIOUS METALS AND
          MERCURY PLANTS 	     91

VIII-1    COST OF COMPLIANCE FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY DIRECT
          DISCHARGERS	     97

IX-1      BPT WASTEWATER DISCHARGE RATES FOR THE PRIMARY
          PRECIOUS METALS AND MERCURY SUBCATEGORY	    106

IX-2      BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY 	    107

X-1       CURRENT RECYCLE PRACTICES WITHIN THE PRIMARY
          PRECIOUS METALS AND MERCURY SUBCATEGORY	    123
                              vi

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                    LIST OF TABLES (Continued)


Number                                                      Page

X-2       POLLUTANT REMOVAL ESTIMATES FOR DIRECT
          DISCHARGERS IN THE PRIMARY PRECIOUS METALS
          AND MERCURY SUBCATEGORY	    124

X-3       COST OF COMPLIANCE FOR DIRECT DISCHARGERS IN
          THE PRIMARY PRECIOUS METALS AND MERCURY
          SUBCATEGORY	    125

X-4       BAT WASTEWATER DISCHARGE RATES FOR THE PRIMARY
          PRECIOUS METALS AND MERCURY SUBCATEGORY	    126

X-5       BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY 	    127

XI-1      NSPS WASTEWATER DISCHARGE RATES FOR THE
          PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY.    137

XI-2      NSPS FOR THE PRIMARY PRECIOUS METALS AND
          MERCURY SUBCATEGORY	    138

XII-1     PSNS WASTEWATER DISCHARGE RATES FOR THE PRIMARY
          PRECIOUS METALS AND MERCURY SUBCATEGORY	    148

XI1-2     PSNS FOR THE PRIMARY PRECIOUS METALS AND
          MERCURY SUBCATEGORY	    149
                              vii

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                         LIST OF FIGURES


Number                                                       Page

II1-1     PRIMARY PRECIOUS METALS PRODUCTION PROCESSES  .  .    34

III-2     PRIMARY MERCURY PRODUCTION PROCESSES 	    35

III-3     GEOGRAPHIC LOCATIONS OF THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY PLANTS	    36

V-1       SAMPLE LOCATIONS AT PRIMARY PRECIOUS METALS
          AND MERCURY PLANT A	    75

IX-1      BPT TREATMENT SCHEME FOR THE PRIMARY PRECIOUS
          METALS AND MERCURY SUBCATEGORY 	    113

X-1       BAT TREATMENT SCHEME FOR OPTION A	    131

X-2       BAT TREATMENT SCHEME FOR OPTION B	    132

X-3       BAT TREATMENT SCHEME FOR OPTION C	    133
                              IX

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                            SECTION I

                     SUMMARY AND CONCLUSIONS


Pursuant to Sections 301, 304, 306, 307, and 501 of the Clean
Water Act and the provisions of the Settlement Agreement  in
Natural Resources Defense Council v. Train, 8 ERG 2120 (D.D.C.
1976) modified. 12 ERG 1833 (D.D.C. 1979), EPA has collected and
analyzed data for plants in the primary precious metals and mer-
cury subcategory.  EPA has never proposed or promulgated  effluent
limitations or standards for this subcategory.  This document and
the administrative record provide the technical basis for propos-
ing effluent limitations based on best practicable technology
(BPT) and best available technology (BAT) for existing direct
dischargers, pretreatment standards for new indirect dischargers
(PSNS),  and standards of performance for new source direct
dischargers (NSPS).

The primary precious metals and mercury subcategory is comprised
of eight plants.  Of the eight plants, one discharges directly  to
rivers,  lakes, or streams; none discharge to publicly owned
treatment works (POTW);  and seven achieve zero discharge  of
process  wastewater.

EPA first studied the primary precious metals and mercury sub-
category to determine whether differences in raw materials, final
products, manufacturing  processes,  equipment, age and size of
plants,  and water usage, required the development of separate
effluent limitations and standards for different segments of the
subcategory.  This involved a detailed analysis of wastewater
discharge and treated effluent characteristics, including (1) the
sources  and volume of water used, the processes used, and the
sources  of pollutants and wastewaters in the plant; and (2) the
constituents of wastewaters, including toxic pollutants.  As a
result,  11  subdivisions  have been identified for this subcategory
that warrant separate effluent limitations.  These include:

        Smelter wet air pollution control,
        Silver chloride  reduction spent solution,
        Electrolytic cells wet air pollution control,
        Electrolyte preparation wet air pollution control,
        Silver crystal wash water,
        Gold slimes acid wash and water rinse,
        Calciner wet air pollution control,
        Calcine quench water,
        Calciner stack gas contact cooling water,
        Condenser blowdown,  and
        Mercury cleaning bath water.

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EPA also identified several distinct  control  and  treatment
technologies  (both in-plant and end-of-pipe)  applicable  to  the
primary precious metals and mercury subcategory.   The  Agency
analyzed both historical and newly generated  data on the
performance of these technologies, including  their nonwater
quality environmental impacts and air quality,  solid waste
 feneration, and energy requirements.  EPA also  studied various
 low reduction techniques reported in the data  collection
portfolios (dcp) and plant visits.

Engineering costs were prepared for each of the control  and
treatment options considered for the  subcategory.  These costs
were then used by the Agency to estimate the  impact of imple-
menting the various options on the subcategory.   For each control
and treatment option that the Agency  found to be  most  effective
and technically feasible in controlling the discharge  of pollu-
tants, we estimated the number of potential closures,  number of
employees affected, and impact on price.  These results  are
reported in a separate document entitled "The Economic Impact
Analysis of Proposed Effluent Limitations Guidelines and
Standards for the Nonferrous Smelting and Refining Industry."

After examining the various treatment technologies, the  Agency
has identified BPT to represent the average of  the best  existing
technology in the nonferrous metals manufacturing industry.
Metals removal based on chemical precipitation  and sedimentation
technology is the basis for the BPT limitations.   Oil  skimming
was selected as the technology basis  for oil  and  grease  limita-
tions.  To meet the BPT effluent limitations  based on  this
technology, the primary precious metals and mercury subcategory
is expected to incur a capital cost of $27,500  and an  annual cost
of $9,000.

For BAT, the Agency has built upon the BPT technology  basis by
adding, in-process control technologies which  include recycle of
process water from air pollution control waste  streams.  Filtra-
tion is added as an effluent polishing step to  the end-of-pipe
treatment scheme.  To meet the BAT effluent limitations  based on
this technology, the primary precious metals  and  mercury subcate-
gory is estimated to incur a capital  cost of  $30,000 and an
annual cost of $10,000.

NSPS are equivalent to BAT.  In selecting NSPS, EPA recognizes
that new plants have the opportunity  to implement the  best  and
most efficient manufacturing processes and treatment technology.
As such, the technology basis of BAT has been determined as the
best demonstrated technology.

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EPA is not proposing PSES for the primary precious metals and
mercury subcategory because there are no indirect dischargers.
For PSNS, the Agency selected end-of-pipe treatment and
in-process flow reduction control techniques equivalent to NSPS,

The best conventional technology (BCT) replaces BAT for the
control of conventional pollutants.  BCT is not being proposed
because the methodology for BCT has not yet been finalized.

The mass limitations and standards for BPT, BAT, NSPS, and PSNS
are presented in Section II.

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    PRIMARY  PRECIOUS METALS AND MERCURY  SUBCATEGORY

                       SECTION II

                    RECOMMENDATIONS
 1.  EPA has divided the primary precious metals  and
    mercury subcategory into  11 subdivisions  for the
    purpose of effluent limitations and standards.
    These subdivisions are:

      (a)  Smelter wet air pollution control,
      (b)  Silver chloride reduction spent  solution,
      (c)  Electrolytic cells  wet air pollution control,
      (d)  Electrolyte preparation wet air  pollution
          control,
      (e)  Silver crystal wash water,
      (f)  Gold slimes acid wash and water  rinse,
      (g)  Calciner wet air pollution control,
      (h)  Calcine quench water,
      (i)  Calciner stack gas  contact cooling  water,
      (j)  Condenser blowdown,  and
      (k)  Mercury cleaning bath water.

 2.  BPT is proposed based on  the performance  achievable
    by the application of chemical precipitation and
    sedimentation (lime and settle) technology,  along
    with preliminary treatment consisting  of  oil skim-
    ming for selected waste streams.  The  following BPT
    effluent limitations are  proposed:
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(a)  Smelter Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of gold and silver smelted

Arsenic                  27.590            12.280
Lead                      5.544             2.640
Mercury                   3.300             1.320
Silver                    5.412             2.244
Zinc                     19.270             8.052
Oil and grease          264.000           158.400
Total suspended         541.200           257.400
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times

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BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(b)  Silver Chloride Reduction Spent Solution

   Pollutant or        Maximum for       Maximum for
Pollutant Property _ Any One Day _ Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
solids
PH
of silver reduced
0.836
0.168
0.100
0.164
0.584
8.000
16.400

Within the rang
in solution
0.372
0.080
0.040
0.068
0.244
4.800
7.800

je of 7.5 to 1 0. 0
                                 at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                 413.800           184.100
Lead                     83.160            39.600
Mercury                  49.500            19.800
Silver                   81.180            33.660
Zinc                    289.100           120.800
Oil and grease        3,960.000         2,376.000
Total suspended       8,118.000         3,861.000
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times

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BPT MASS LIMITATIONS  FOR  THE  PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(d)  Electrolyte Preparation  Wet Air Pollution Control
                                       i
   Pollutant or        Maximum  for-       Maximum for
Pollutant Property	Any One  Day	Monthly Average

    mg/troy ounce of  silver in  electrolyte  produced

Arsenic                   0.105             0.047
Lead                      0.021              0.010
Mercury                   0.013             0.005
Silver                    0.021              0.009
Zinc                      0.073             0.031
Oil and grease            1.000             0.600
Total suspended           2.050             0.975
  solids
pH                     Within the  range  of  7.5 to 10.0
                                 at  all  times
BPT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS  METALS
AND MERCURY SUBCATEGORY

(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver crystals washed

Arsenic                   0.606              0.270
Lead                      0.122              0.058
Mercury                   0.073              0.029
Silver                    0.119              0.049
Zinc                      0.423              0.177
Oil and grease            5.800              3.480
Total suspended          11.890              5.655
  solids
pH                     Within the range of  7.5 to 10.0
                                 at all times

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BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

          ing/troy ounce of gold slimes washed

Arsenic                   8.360              3.720
Lead                      1.680              0.800
Mercury                   1.000              0.400
Silver                    1.640.              0.680
Zinc                      5.840              2.440
Oil and grease           80.000            48.000
Total suspended         164.000            78.000
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(g)  Calciner Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      rag/kg (Ib/million Ibs) of mercury condensed

Arsenic                 388.800            173.000
Lead                     78.120            37.200
Mercury                  46.500            18.600
Silver                   76.260            31.620
Zinc                    271.600            113.500
Oil and grease        3,720.000         2,232.000
Total suspended       7,626.000         3,627.000
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
                                8

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BPT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS  METALS
AND MERCURY SUBCATEGORY

(h)  Calcine Quench Water

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average

      mg/kg (Ib/million Ibs)  of mercury  condensed

Arsenic                  36.790            16.370
Lead                      7.392             3.520
Mercury                   4.400             1.760
Silver                    7.216             2.992
Zinc                     25.700            10.740
Oil and grease          352.000    •       211.200
Total suspended         721.600           343.200
  solids
pH                     Within the range  of 7.5 to 1 0. 0
                                 at all  times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/miliion Ibs) of mercury condensed

Arsenic                   8.674              3.860
Lead                      1.743              0.830
Mercury                   1.038              0.415
Silver                    1.702              0.706
Zinc                      6.059              2.532
Oil and grease           83.000            49.800
Total suspended         170.200            80.930
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times

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BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  28.840            12.830
Lead                      5.796             2.760
Mercury                   3.450             1.380
Silver                    5.658             2.346
Zinc                     20.150   .          8.418
Oil and grease          276.000           165.600
Total suspended         565.800           269.100
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   2.926             1.302
Lead                      0.588             0.280
Mercury                   0.350             0.140
Silver                    0.574             0.238
Zinc                      2.044             0.854
Oil and grease           28.000            16.800
Total suspended          57.400            27.300
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
    BAT is proposed based on the performance achievable
    by the application of chemical precipitation, sedi-
    mentation, and multimedia filtration  (lime, settle,
    and filter) technology and in-process flow reduc-
    tion methods, along with preliminary  treatment con-
    sisting of oil skimming for selected waste streams.
    The following BAT effluent limitations are
    proposed:
                               10

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BAT MASS LIMITATIONS FOR THE  PRIMARY PRECIOUS  METALS
AND MERCURY SUBCATEGORY

(a)  Smelter Wet Air Pollution  Control

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average

        mg/troy ounce of gold and silver smelted

Arsenic                   1.807             0.806
Lead                      0.364             0.169
Mercury                   0.195             0.078
Silver                    0.377             0.156
Zinc                      1.326             0.546
BAT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS METALS
AND MERCURY SUBCATEGORY

(b)  Silver Chloride Reduction  Spent  Solution

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average

      mg/troy ounce of silver reduced  in solution

Arsenic                   0.556              0.248
Lead                      0.112              0.052
Mercury                   0.060              0.024
Silver                    0.116              0.048
Zinc                      0.408              0.168
BAT MASS LIMITATIONS FOR THE PRIMARY  PRECIOUS METALS
AND MERCURY SUBCATEGORY

(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                  27.520             12.280
Lead                      5.544              2.574
Mercury                   2.970              1.188
Silver                    5.742              2.376
Zinc                     20.200              8.316
                               11

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BAT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS METALS
AND MERCURY SUBCATEGORY

(d)  Electrolyte Preparation  Wet Air  Pollution  Control

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly  Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver
0.
0.
0.
0.
0.
in electrolyte
070
014
008
015
051
produced
0.031
0.007
0.003
0.006
0.021
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver crystals
0.403
0.081
0.044
0.084
0.296
washed
0.180
0.038
0.017
0.035
0.122
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum for
Pollutant PropertyAny One DayMonthly Average

Arsenic
Lead
Mercury
Silver
Zinc
mg/troy ounce of gold
5.560
1.120
0.600
1.160
4.080
slimes washed
2.480
0.520
0.240
0.480
1.680
                               12

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BAT MASS  LIMITATIONS  FOR  THE  PRIMARY PRECIOUS  METALS
AND MERCURY SUBCATEGORY

(g)  Calciner Wet Air Pollution  Control

   Pollutant or        Maximum for        Maximum for
Pollutant Property	Any One Day	Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million

Ibs) of mercury
30.580
6.160
3.300
6.380 .
22.440
condensed
13.640
2.860
1.320
2.640
9.240
BAT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS METALS
AND MERCURY SUBCATEGORY

(h)  Calcine Quench Water

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average

      mg/kg (Ib/million Ibs)  of mercury  condensed

Arsenic                  24.470             10.910
Lead                      4.928              2.288
Mercury                   2.640              1.056
Silver                    5.104              2.112
Zinc                     17.950              7.392
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   5.769             2.573
Lead                      1.162             0.540
Mercury                   0.623             0.249
Silver                    1.204             0.498
Zinc                      4.233             1.743
                               13

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BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  19.180             8.556
Lead                      3.864             1.794
Mercury                   2.070             0.828
Silver                    4.002             1.656
Zinc                     14.080             5.796
BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS METALS
AND MERCURY SUBCATEGORY

(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406             0.168
Zinc                      1.428             0.588
4.  NSPS are proposed based on the performance achiev-
    able by the application of chemical precipitation,
    sedimentation, and multimedia filtration  (lime,
    settle, and filter) technology, and in-process flow
    reduction control methods, along with preliminary
    treatment consisting of oil skimming for  selected
    waste streams.  The following effluent standards
    are proposed for new sources:
                               14

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NSPS FOR THE PRIMARY  PRECIOUS METALS  AND MERCURY
SUBCATEGORY

(a)  Smelter Wet Air  Pollution  Control

   Pollutant or        Maximum  for        Maximum for
Pollutant Property	Any One  Day	Monthly Average

        mg/troy ounce of gold and silver smelted

Arsenic                   1.807             0.806
Lead                      0.364             0.169
Mercury                   0.195             0.078
Silver                    0.377             0.156
Zinc                      1.326             0.546
Oil and grease           13.000            13.000
Total suspended          19.500            15.600
  solids
pH                     Within the range  of  7.5 to 10.0
                                 at all  times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(b)  Silver Chloride Reduction Spent Solution

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/troy ounce of silver reduced in solution

Arsenic                   0.556             0.248
Lead                      0.112             0.052
Mercury                   0.060             0.024
Silver                    0.116             0.048
Zinc                      0.408             0.168
Oil and grease            4.000             4.000
Total suspended           6.000             4.800
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                              15

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NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                  27.520             12.280
Lead                      5.544              2.574
Mercury                   2.970              1.188
Silver                    5.742             .2.376
Zinc                     20.200              8.316
Oil and grease          198.000           198.000
Total suspended         297.000           237.600
  solids
pH                     Within the range of  7.5 to  10.0
                                 at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(d)  Electrolyte Preparation Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

    mg/troy ounce of silver in electrolyte produced

Arsenic                   0.070             0.031
Lead                      0.014             0.007
Mercury                   0.008             0.003
Silver                    0.015             0.006
Zinc                      0.051             0.021
Oil and grease            0.500             0.500
Total suspended           0.750             0.600
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
                               16

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NSPS FOR THE  PRIMARY PRECIOUS  METALS  AND MERCURY
SUBCATEGORY

(e)  Silver Crystals  Wash  Water

   Pollutant  or        Maximum for        Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver  crystals washed

Arsenic                    0.403              0.180
Lead                       0.081              0.038
Mercury                    0.044              0.017
Silver                     0.084,             0.035
Zinc                       0.296              0.122
Oil and grease             2.900              2.900
Total suspended            4.350              3.480
  solids
pH                     Within  the range of  7.5 to 10.0
                                 at all times
NSPS FOR THE PRIMARY PRECIOUS METALS  AND  MERCURY
SUBCATEGORY

(f)  Gold Slimes Acid Wash and Water  Rinse

   Pollutant or        Maximum for        Maximum for
Pollutant Property	Any One Day	Monthly Average

          mg/troy ounce of gold  slimes washed

Arsenic                   5.560              2.480
Lead                      1.120              0.520
Mercury                   0.600              0.240
Silver                    1.160              0.480
Zinc                      4.080              1.680
Oil and grease           40.000            40.000
Total suspended          60.000            48.000
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               17

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NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(g)  Calciner Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  30.580             13.640
Lead                      6.160             2.860
Mercury                   3.300             1.320
Silver                    6.380             2.640
Zinc                     22.440             9.240
Oil and grease          220.000           220.000
Total suspended         330.000           264.000
  solids
pH                     Within the range of  7.5 to 10.0
                                 at all times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(h)  Calcine Quench Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      rag/kg (Ib/million Ibs) of mercury condensed

Arsenic                  24.470             10.910
Lead                      4.928             2.288
Mercury                   2.640             1.056
Silver                    5.104             2.112
Zinc                     17.950             7.392
Oil and grease          176.000           176.000
Total suspended         264.000           211.200
  solids
pH                     Within the range of  7.5 to 10.0
                                 at all times
                               18

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NSPS FOR THE PRIMARY  PRECIOUS METALS  AND MERCURY
SUBCATEGORY

(i)  Calciner Stack Gas  Contact  Cooling  Water

   Pollutant or        Maximum for        Maximum for
Pollutant Property	Any One Day	Monthly Average

      nig/kg (Ib/million  Ibs) of  mercury  condensed

Arsenic                   5.769              2.573
Lead                      1.162              0.540
Mercury                   0.623              0.249
Silver                    1.204              0.498
Zinc                      4.233              1.743
Oil and grease            41.500             41.500
Total suspended           62.250             49.800
  solids
pH                     Within the range  of  7.5 to 10.0
                                 at all  times
NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(j)  Condenser Blowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   19.180              8.556
Lead                      3.864              1.794
Mercury                   2.070              0.828
Silver                    4.002              1.656
Zinc                      14.080              5.796
Oil and grease          138.000            138.000
Total suspended         207.000            165.600
  solids
pH                     Within the range of 7. 5 to  10.0
                                 at all times
                               19

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NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406             0.168
Zinc                      1.428             0.588
Oil and grease           14.000            14.000
Total suspended          21.000            16.800
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
5.  EPA is not proposing PSES for the primary precious
    metals and mercury subcategory because there are no
    indirect dischargers.

6.  PSNS are proposed based on the performance achiev-
    able by the application of chemical precipitation,
    sedimentation, and multimedia filtration (lime,
    settle, and filter) technology, and in-process flow
    reduction control methods, along with preliminary
    treatment consisting of oil skimming for selected
    waste streams.  The following pretreatment
    standards are proposed for new sources:
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(a)  Smelter Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of gold and silver smelted

Arsenic                   1.807             0.806
Lead                      0.364             0.169
Mercury                   0.195             0.078
Silver                    0.377             0.156
Zinc                      1.326             0.546
                               20

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 PSNS  FOR  THE  PRIMARY PRECIOUS  METALS AND MERCURY
 SUBCATEGORY

 (b)   Silver Chloride Reduction Spent Solution

    Pollutant  or         Maximum for        Maximum for
 Pollutant Property	Any  One Day	Monthly Average

      mg/troy ounce  of  silver  reduced in solution

 Arsenic                   0.556             0.248
 Lead                      0.112             0.052
 Mercury                   0.060             0.024
 Silver                    0.116             0.048
 Zinc                      0.408             0.168
 PSNS FOR THE  PRIMARY  PRECIOUS METALS  AND MERCURY
 SUBCATEGORY

 (c)  Electrolytic  Cells  Wet  Air  Pollution Control

   Pollutant  or        Maximum for        Maximum for
 Pollutant Property	Any One Day	Monthly Average

     mg/troy  ounce of gold refined  electrolytically

 Arsenic                   27.520             12.280
 Lead                      5.544              2.574
 Mercury                   2.970      .        1.188
 Silver                    5.742              2.376
 Zinc                      20.200              8.316
PSNS FOR THE PRIMARY  PRECIOUS METALS AND MERCURY
SUBCATEGORY

(d)  Electrolyte Preparation Wet Air Pollution  Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly  Average

    mg/troy ounce of  silver in electrolyte produced

Arsenic                   0.070              0.031
Lead                      0.014              0.007
Mercury                   0.008              0.003
Silver                    0.015              0.006
Zinc                      0.051              0.021
                               21

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PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver crystals washed

Arsenic                   0.403              0.180
Lead                      0.081              0.038
Mercury                   0.044              0.017
Silver                    0.084              0.035
Zinc                      0.296              0.122
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

          mg/troy ounce of gold slimes washed

Arsenic                   5.560              2.480
Lead                      1.120              0.520
Mercury                   0.600              0.240
Silver                    1.160              0.480
Zinc                      4.080              1.680
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(g)  Calciner Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  30.580             13.640
Lead                      6.160              2.860
Mercury                   3.300              1.320
Silver                    6.380              2.640
Zinc                     22.440              9.240
                               22

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PSNS FOR THE PRIMARY  PRECIOUS METALS AND  MERCURY
SUB CATEGORY

(h)  Calcine Quench Water

   Pollutant or        Maximum for        Maximum for
Pollutant Property	Any One Day	Monthly Average

      ing/kg (Ib/million  Ibs) of mercury condensed

Arsenic                  24.470             10.910
Lead                      4.928              2.288
Mercury                   2.640              1.056
Silver                    5.104              2.112
Zinc                     17.950              7.392
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million

Ibs) of mercury
5.769
1.162
0.623
1.204
4.233
condensed
2.573
0.540
0.249
0.498
1.743
PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million




Ibs) of mercury
19.180
3. -864
2. U/0
4.002
14.080
condensed
8.556
1.794
0.828
1.656
5.796
                               23

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PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
SUBCATEGORY

(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406     ,        0.168
Zinc                      1.428             0.588
7.  EPA is not proposing BCT for the primary precious
    metals and mercury subcategory at this time.
                              24

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          PRIMARY  PRECIOUS METALS  AND MERCURY SUBCATEGORY

                            SECTION  III

                          INDUSTRY PROFILE


This section of the primary precious metals  and  mercury supple-
ment describes the raw materials  and processes used in producing
primary precious  metals and mercury  and  presents a  profile of the
primary precious  metals and mercury  plants  identified in this
study.  For a discussion of the purpose, authority,  and methodol-
ogy for this study, and a general description of the nonferrous
metals manufacturing category, refer to  Section  III of the
General Development Document.

DESCRIPTION OF PRIMARY PRECIOUS METALS PRODUCTION

The production of primary precious metals can be divided into
three distinct stages - smelting  to  produce  Dore metal,  separa-
tion of gold and  silver, and gold and silver purification.   The
processes used in each stage vary with the type  and purity of raw
material  used.  The primary precious metals  production process is
presented schematically in  Figure III-1  and  described below.

RAW MATERIALS

Primary precious  metals are produced from gold and  silver bearing
concentrates produced from  precious  metal ores and  as a by-prod-
uct from  the beneficiation  of base metal ores.   A small amount is
also produced from placer mining  operations.  Precious metal  ores
are mined at various locations in the western United States.

Mining and beneficiation processes for precious  metal-bearing
ores,  including  cyanidation, amalgamation,  flotation,  and
gravity concentration are outside the scope  of this  subcategory.
Both the  mining and beneficiation operations  are regulated as
part of the Ore Mining and  Dressing  Point Source Category.

Primary precious  metals produced  as  a by-product of  primary
copper refining operations  are regulated under nonferrous metals
manufacturing phase I as part of  the  primary  copper  refining
subcategory.

SMELTING

The gold  and silver manufacturing process begins when the
precious metals bearing concentrate  is sent  through  a Dore fur-
nace (smelter).   In the Dore furnace, the gold,  silver,  and other
precious metals are smelted in the presence  of a fluxing agent
                              25

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(commonly soda ash, borax, or  silica).   This  smelting operation
produces a slag containing impurities  such  as  copper  and zinc,
and a gold base alloy known as  Dore, which  may also  contain
silver.

The Dore gold may be cast and  sold as  a  product or further
refined.

GOLD-SILVER SEPARATION

The separation of gold and silver from Dore bars is  accomplished
through electrolytic refining  or by the  Miller process.   In the
electrolytic method, the Dore  metal is cast into anodes  and
placed into a solution of silver nitrate (AgNO^)  electrolyte.
When a current is applied fine  silver  is deposited upon  the
cathode.  This silver is removed, washed, and  cast into  bars of
fine silver for sale.  Gold remains as slimes  in the  canvas anode
bags.  Gold slimes are washed  with acid  and rinsed with  water
before being cast as a product.  This  gold  is  about  99 percent
pure.  Silver is recovered in  a cementation step from the silver
crystals wash water and from the gold  slimes  acid wash and rinse
water.  In the cementation process, copper  is  added  to the solu-
tion and replaces the silver,  causing  the silver to  precipitate
out of the solution.  The recovered silver  is  returned to the
anode casting stage.

Gold and silver can also be separated  from  the Dore  metal while
it is still molten.  This purification step is known  as  the
Miller process and consists of  bubbling  chlorine gas  through the
molten Dore metal in a parting  furnace.   This  process converts
the silver into silver chloride salt and volatilizes  base metal
impurities.  The silver chloride salt  rises to the surface and  is
skimmed off for further processing.  The gold  produced by the
Miller process can be further  purified by electrolytic refining
or immediately cast as a product.  The silver  chloride salt which
is skimmed off is remelted and  cast into slabs.   These slabs are
reduced to silver metal in an  acid solution.   The resulting
silver metal is remelted in the presence of borax flux and molten
silver is then cast as a product.

FURTHER PURIFICATION

After separation, gold and silver can  be further refined by vari-
ous means.  One technique to further refine gold is  electrolysis.
Impure gold is cast into anodes and purified  electrolytically by
the Wholwill process in a chloride solution.   Gold, which is
oxidized at the anode, passes  into solution and is deposited upon
the cathode.  The gold cathode  is melted and  cast into bars with
a purity greater than 99.9 percent.  As  described above, gold
slimes can be further purified  using an  acid wash and water rinse
process.
                               26

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 PROCESS WASTEWATER  SOURCES

Although a variety  of  processes  are  involved in primary precious
metals production,  the process wastewater  sources  can be sub-
divided as follows:

      1.  Smelter wet air  pollution  control,
      2.  Silver chloride  reduction  spent  solution,
      3.  Electrolytic  cells wet  air  pollution control,
      4.  Electrolyte preparation wet air  pollution control,
      5.  Silver crystal wash water,  and
      6.  Gold slimes acid wash and water  rinse.

DESCRIPTION OF PRIMARY MERCURY PRODUCTION

Primary mercury is  produced from mercury  ores and  gold-bearing
ores  by roasting or calcining.   The  primary  mercury production
process is presented schematically  in Figure III-2 and  described
below.

RAW MATERIALS

The principal source of mercury  is cinnabar  ore (mercury sul-
fide).  Cinnabar ore is mined primarily in Nevada,  California,
and Oregon.  In addition, a small amount  of  mercury is  recovered
as a  co-product from gold ore.

ROASTING

After mining and beneficiation,  mercury is extracted from
mercury-bearing ores by roasting or  calcining.   In  the  roasting
process, the mercury is vaporized and then recovered in a con-
denser, while the sulfur  is oxidized to SOo.   Some  water may
condense with the mercury and is  discharged  as  a waste  stream.
The mercury recovered  from the condenser may be washed  with  water
prior to being sold.   The mining  and beneficiation  stage of
mercury production  is  not within  the scope of this  subcategory.

Sulfur dioxide (S02> and  other gaseous emissions from the mer-
cury roasting furnace  are controlled with a  multistage  scrubber.
Sulfur dioxide emissions  are controlled with a  wet  scrubber.
After S02 removal,   the clean stack gases are cooled with
contact cooling water  and discharged to the  atmosphere.   Calciner
S02 scrubber liquor and stack gas contact cooling water are
discharged as waste streams.
                              27

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PROCESS WASTEWATER SOURCES

Although a variety of processes are  involved  in primary mercury
production, the process wastewater sources can be  subdivided  as
follows:

     1.  Calciner wet air pollution  control,
     2.  Calcine quench water,
     3.  Calciner stack gas contact  cooling water,
     4.  Condenser blowdown, and
     5.  Mercury cleaning bath water.

OTHER WASTEWATER SOURCES

There are other waste streams associated with the  primary
precious metals and mercury subcategory.  These waste  streams
include, but are not limited to:

     1.  Casting contact cooling water,
     2.  Stormwater runoff, and
     3.  Maintenance and cleanup water.

These waste streams are not considered as a part of  this rulemak-
ing.  EPA believes that the flows and pollutant loadings associ-
ated with these waste streams are insignificant relative to  the
waste streams selected, or are best  handled by the appropriate
permit authority on a case-by-case basis under authority of
Section 403 of the Clean Water Act.

AGE, PRODUCTION, AND PROCESS PROFILE

Figure III-3 shows the location of the eight primary precious
metals and mercury plants operating  in the United  States.  Four
of the eight plants are located in Nevada, with one  of the
remaining plants each being located  in Idaho, Montana, Colorado,
and South Dakota.

Table III-1 shows the relative age and discharge status of the
primary precious metals and mercury  plants.  Seven of  the eight
plants in this subcategory have a zero discharge status, and  one
plant is a direct discharge facility.  The average plant age  is
less than 12 years.  Tables III-2 to III-4 provide a summary  of
the current production ranges.  It can be seen that  production  of
gold is evenly spread along the ranges with a mean production of
70,000 troy ounces/year.  The mean production of silver is
222,500 troy ounces/year.

Table III-5 provides a summary of the number of plants generating
wastewater for the waste streams associated with various proces-
ses and the number of plants with the process.
                               28

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                           Table III-1

     INITIAL OPERATING YEAR (RANGE) SUMMARY OF PLANTS IN THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY BY DISCHARGE TYPE
                   Initial Operating Year (Range)
                        (Plant Age in Years)
Type of
Plant
Direct
Indirect
Zero
TOTAL
1983-
1973
(0-11)
1
0
4
5
1972-
1968
(12-16)
0
0
1
1
1967-
1958
(17-26)
0
0
1
1
1957-
1918
(27-66)
0
0
0
0
Before
1918
(66%)
0
0
1
1
Total
1
0
]_
8
                              29

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        PRODUCTION RANGES FOR THE PRIMARY PRECIOUS METALS
                      AND MERCURY SUBCATEGORY
Mercury production ranges are not presented here because  the
information on which they are based has been claimed
confidential.
                               32

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                            Figure  III-2

             PRIMARY  MERCURY PRODUCTION  PROCESS
                                 35

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                            SECTION IV

                        SUBCATEGORIZATION


As discussed in Section IV of the General Development Document,
the nonferrous metals manufacturing category has been subcate-
gorized to take into account pertinent industry characteristics,
manufacturing process variations, and a number of other factors
which affect the ability of the facilities to achieve effluent
limitations.  This section summarizes the factors considered
during the designation of the primary precious metals and mercury
subcategory and its related subdivisions.  Production normalizing
parameters for each subdivision will also be discussed.

FACTORS CONSIDERED IN SUBCATEGORIZATION

The following factors were evaluated for use in subcategorizing
the nonferrous metals manufacturing category:

      1.  Metal products, co-products, and by-products;
      2.  Raw materials;
      3.  Manufacturing processes;
      4.  Product form;
      5.  Plant location;
      6.  Plant age;
      7.  Plant size;
      8.  Air pollution control methods;
      9.  Meteorological conditions;
     10.  Treatment costs;
     11.  Nonwater quality aspects;
     12.  Number of employees;
     13.  Total energy requirements; and
     14.  Unique plant characteristics.

Evaluation of all factors that could warrant subcategorization
resulted in the designation of the primary precious metals and
mercury subcategory.  Three factors were particularly important
in establishing these classifications:  the type of metal pro-
duced,  the nature of the raw material used,  and the manufacturing
processes involved.

In Section IV of the General Development Document, each of these
factors is described, and the rationale for selecting metal prod-
uct,  manufacturing process,  and raw materials as the principal
factors used for subcategorization is discussed.  On this basis,
the nonferrous metals manufacturing category (phase II) was
divided into 21  subcategories, one of them being primary precious
metals  and mercury.


                               37

-------
FACTORS CONSIDERED IN SUBDIVIDING THE PRIMARY PRECIOUS METALS AND
MERCURY SUBCATEGORY

The factors listed previously were each evaluated when consider-
ing subdivision of the primary precious metals and mercury  sub-
category.  In the discussion that follows, the factors will  be
described as they pertain to this particular subcategory.

The rationale for considering further subdivision of  the primary
precious metals and mercury subcategory is based primarily  on
differences in the production processes and raw materials used.
Within this subcategory, a number of different operations are
performed, which may or may not have a water use or discharge,
and which may require the establishment of separate effluent
limitations.  While primary precious metals and mercury is  still
considered a single subcategory, a more thorough examination of
the production processes has illustrated  the need for limitations
and standards based on a specific set of  waste streams.  Limita-
tions will be based on specific flow allowances for the following
subdivisions:

     1.  Smelter wet air pollution control,
     2.  Silver chloride reduction spent  solution,
     3.  Electrolytic cells wet air pollution control,
     4.  Electrolyte preparation wet air  pollution control,
     5.  Silver crystal wash water,
     6.  Gold slimes acid wash and water  rinse,
     7.  Calciner wet air pollution control,
     8.  Calcine quench water,
     9.  Calciner stack gas contact cooling water,
    10.  Condenser blowdown, and
    11.  Mercury cleaning bath water.

These subdivisions follow directly from differences within  the
three distinct production stages of primary precious  metals  and
mercury.

The smelting of precious metals bearing concentrates  to produce
Dore metals gives rise to the first subdivision:  the smelter wet
air pollution control wastewater.  If any remelt furnaces are
used in the process, the resulting off-gases are usually combined
with smelter off-gases for air pollution  control.  Thus, the
smelter wet air pollution control subdivision represents the wet
air pollution control wastewater for both smelters and remelt
furnaces.  The next two subdivisions result from the  Miller
process (electrolytic refining of gold) for purifying high  silver
content Dore metal.  The electrolytic cells scrubber  wastewater
is the principal waste stream, but spent  solution from silver
reduction is also discharged.
                               38

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The  electrolytic refining  of  silver  from Dore  metal gives rise to
the  next three subdivisions.   The  washing of  electrolysis prod-
ucts (silver crystals  and  gold slimes)  creates two waste streams
that can potentially be discharged.   The fourth subdivision is
created by  the wet  scrubber used  to  control  air emissions from
the  electrolyte preparation stage.

The  last five subdivisions result  from  the production of primary
mercury.  The treatment of calciner  off-gases  by wet scrubbing
gives rise  to the first of these  subdivisions.  Waste streams may
also result from the quenching of  calciner wastes to reduce their
temperature prior to disposal  and  the cooling  of calciner off-
gases before discharge from the stack.   During condensation of
the  vaporized mercury, the condensation of a. water fraction can
occur and this condenser blowdown  is  a  possible waste stream.
After condensation  the liquid  mercury may be  further purified by
use  of cleaning baths.  This  cleaning operation is also a
potential source of wastewater.

OTHER FACTORS

The  other factors considered  in this  evaluation either support
the  establishment of the 11 subdivisions or were shown to be
inappropriate bases for subdivision.  Air pollution control
methods, treatment  costs,  and  total  energy requirements are
functions of the selected  subcategorization factors—metal
product, raw materials, and production  processes.   Therefore,
they are not independent factors and  do not affect the subcate-
gorization which has been  applied.  As  discussed in Section IV of
the  General Development Document,  certain other factors,  such as
plant age, plant size, and the  number of employees,  were also
evaluated and determined to be  inappropriate for use as bases for
subdivision of nonferrous metals plants.

PRODUCTION NORMALIZING PARAMETERS

As discussed previously, the effluent limitations  and standards
developed in this document establish  mass  limitations on the dis-
charge of specific pollutant parameters.   To allow these regula-
tions to be applied to plants with various production capacities,
the mass of pollutant  discharged must be  related to  a unit of
production.   This factor is known  as  the  production  normalizing
parameter (PNP).

In general,  for each production process  which  has  a  wastewater
associated with it,  the actual mass of  precious  metal or mercury
product produced will  be used as the  PNP.  Thus,  the PNPs  for the
11 subdivisions  are as follows:
                               39

-------
          Subdivision
                                            PNP
 4.
Smelter wet air pollution
  control

Silver chloride reduction
  spent solution

Electrolytic cells wet air
  pollution control

Electrolyte preparation
  wet air pollution control
 5.  Silver crystal wash water
 6.  Gold slimes acid wash and
       water rinse

 7.  Calciner wet air pollution
       control

 8.  Calcine quench water

 9.  Calciner stack gas contact
       cooling water

10.  Condenser blowdown
troy ounce of gold and  silver
  smelted

troy ounce of silver reduced
  in solution

troy ounce of gold refined
  electrolytically

troy ounce of silver in elec-
  trolyte produced

troy ounce of silver crystals
  washed

troy ounce of gold slimes
  washed

kkg of mercury condensed


kkg of mercury condensed

kkg of mercury condensed


kkg of mercury condensed
11.  Mercury cleaning bath water    kkg  of mercury  condensed

Other PNPs were considered.  The use of  production  capacity
instead of actual production was eliminated from  consideration
because the mass of the pollutant produced is  more  a  function  of
true production than of installed capacity.  The  use  of  some com-
mon intermediate (i.e., gold and silver  cathodes  or silver  chlo-
ride) as a basis for PNPs for all processes was rejected  since
not all plants follow the same production path to get to  the
specific end-product.  Additionally, some plants  divert  part of
their intermediate products and sell them instead of  processing
all input raw materials to one final product.   If an  "end-
product" were chosen as the PNP, plants  that had  these upstream
diversions would be allowed to discharge more  per mass of product
than their competitors who did not.
                                40

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         PRIMARY  PRECIOUS METALS AND  MERCURY SUBCATEGORY

                             SECTION V

             WATER USE AND WASTEWATER CHARACTERISTICS
This section describes the characteristics  of  the  wastewaters
associated with the primary precious metals and  mercury subcate-
gory.  Water use and discharge  rates are  explained and  then
summarized in tables at  the end of  this  section.   Data  used to
characterize the wastewaters are presented.. Finally, the
specific source, water use and  discharge  flows,  and wastewater
characteristics for each separate wastewater source are
discussed.

Section V of the General Development Document  contains  a detailed
description of the data  sources  and methods of analysis used to
characterize wastewater  from the nonferrous metals manufacturing
category.  To summarize  this information  briefly,  two principal
data sources were used:  data collection  portfolios (dcp)  and
field sampling results.  Data collection  portfolios contain
information regarding wastewater flows and  production levels.

In order to quantify the pollutant  discharge from  primary pre-
cious metals and mercury plants, a  field  sampling  program was
conducted.  A complete list of  the  pollutants  considered and a
summary of the techniques used  in sampling  and laboratory analy-
ses are included in Section V of the General Development Docu-
ment.  Samples were analyzed for 124 of  the 126  toxic pollutants
and other pollutants deemed appropriate.   (Because the  analytical
standard for TCDD was judged to  be  too hazardous to be  made gen-
erally available, samples were  never analyzed  for  this  pollutant.
Samples were also not analyzed  for asbestos.   There is  no reason
to expect that TCDD or asbestos  would be  present in nonferrous
metals manufacturing wastewater.)  A total  of  two  plants were
selected for sampling in the primary precious  metals and mercury
subcategory.  In general, the samples were  analyzed for three
classes of pollutants:   toxic organic pollutants,  toxic metal
pollutants, and criteria pollutants (which  includes both
conventional and nonconventional pollutants).

As described in Section  IV of this supplement, the primary
precious metals and mercury subcategory has  been split  into 11
subdivisions or wastewater sources, so that the proposed regula-
tion contains mass discharge limitations  and standards  for 11
unit processes discharging process wastewater.  Differences in
the wastewater characteristics associated with these subdivisions
are to be expected.  For this reason, wastewater streams corre-
sponding to each subdivision are addressed  separately in the
discussions that follow.  These  wastewater  sources are:
                              41

-------
      1.   Smelter wet air pollution control,
      2.   Silver  chloride reduction spent solution,
      3.   Electrolytic cells wet air pollution control,
      4.   Electrolyte preparation wet air pollution control,
      5.   Silver  crystal wash water,
      6.   Gold  slimes acid wash and water rinse,
      7.   Calciner wet air pollution control,
      8.   Calcine quench water,
      9.   Calciner stack gas contact cooling water,
     10.   Condenser blowdown,  and
     11.   Mercury cleaning bath water.

 WASTEWATER FLOW  RATES

 Data supplied  by dcp responses were evaluated,  and two flow-to-
 production ratios,  water use and wastewater  discharge flow, were
 calculated for each stream.  The two ratios  are  differentiated by
 the  flow  value used in calculation.  Water use  is defined as the
 volume of water  or other fluid required for  a given process per
 mass of product  and is therefore based on the sum of recycle and
 make-up flows  to a given process.  Wastewater flow discharged
 after pretreatment or recycle (if these are  present) is used in
 calculating the  production normalized flow—the  volume of waste-
 water discharged from a given process  to further treatment,
 disposal,  or discharge per mass of product produced.  Differences
 between the water use and wastewater flows associated with a
 given stream result from recycle, evaporation,  and carryover on
 the  product.   The production values used in  calculation corre-
'spend to  the production normalizing parameter,  PNP, assigned to
 each stream, as  outlined in Section IV.  As  an  example, calcine
 quench water flow is related to the production  of the refined
 mercury.   As such,  the discharge rate  is expressed in liters of
 quench water per metric ton of mercury produced  (gallons of
 quench water per ton of mercury).

 The  production normalized discharge flows were  compiled and sta-
 tistically analyzed by stream type.  These production normalized
 water use  and  discharge flows are presented  by  subdivision in
 Tables V-1  through V-11 at the end of this section.  Where appro-
 priate, an attempt was made to identify factors  that could
 account for variations in water use and discharge rates.  These
 variations are discussed later in this section  by subdivision.  A
 similar analysis of factors affecting the wastewater flows is
 presented  in Sections X,  XI,  and XII where representative BAT,
 NSPS, and  pretreatment flows are selected for use in calculating
 the  effluent limitations.

 The  water  use  and discharge rates shown do not  include nonprocess
 wastewater,  such as rainfall runoff and noncontact cooling water.
                               42

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WASTEWATER CHARACTERISTICS  DATA

Data used to characterize the  various  wastewaters associated with
primary precious metals  and mercury  production come from two
sources—data collection portfolios  and  analytical data from
field sampling trips.

DATA COLLECTION PORTFOLIOS

In the data collection portfolios, the primary precious metals
and mercury plants  that  generate  wastewater  were  asked to specify
the presence or absence  of  toxic  pollutants  in their wastewater.
In most cases, the  plants indicated  that the toxic organic pollu-
tants were believed to be absent.  However,  two of the plants
stated that they either  knew or believed the metals to be
present.  The responses  for asbestos,  cyanide,  and the metals are
summarized below:*

         Pollutant     Known Present     Believed Present

         Antimony            0                 0
         Arsenic             1                  0
         Asbestos            0                 1
         Beryllium           0                 0
         Cadmium             1                  0
         Chromium            1                  0
         Copper              1                  0
         Cyanide             1                  0
         Lead                1                  0
         Mercury             2                 1
         Nickel              1                  0
         Selenium            1                  0
         Silver              1                  0
         Thallium            0                 0
         Zinc                1                  0

Although asbestos was reported as believed present by one plant,
the trip report from this facility stated it  was  the mineral
cummingtonite which was  present and  not  asbestos.  Although the
two minerals have some similarities  such  as  similar chemical
formulas,  cummingtonite  is  not  listed  by  EPA as a toxic
pollutant.
*Six plants which produce primary precious metals and mercury
 have been omitted due to lack of data.
                               43

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FIELD SAMPLING DATA

In order to quantify the concentrations of pollutants  present  in
wastewater from primary precious metals and mercury  plants,
wastewater samples were collected at  two plants.   The  analytical
results from one of these two plants  are not presented  here
because they are claimed to be confidential by  the plant.  A dia-
gram indicating the sampling sites and contributing  production
processes at the non-confidential plant is shown  in  Figure V-1
(at the end of this section).

Raw wastewater data are summarized in Tables V-12 through V-15
(at the end of this section).  Analytical results  for  the com-
bined stream of smelter scrubber water and Miller  electrolysis
cell scrubber water as well as spent  solution from silver
reduction are contained in the confidential record.  Table V-12
presents data for each of the three stages of the  calciner
scrubber system.  Tables V-13, V-14,  and V-15 present  sampling
data for calcine quench water, calciner stack gas  cooling water,
and mercury cleaning bath water, respectively.  Note that the
stream numbers listed in the tables correspond  to  those given  in
the individual plant sampling site diagram, Figure V-1.  Where no
data are listed for a specific day of sampling, the  wastewater
samples for the stream were not collected.

Several points regarding these tables should be noted.   First,
the data tables include some samples  measured at  concentrations
considered not quantifiable.  The base-neutral  extractable,  acid
extractable, and volatile organics generally are  considered  not
quantifiable at concentrations equal  to or less than 0.010 mg/1.
Below this concentration, organic analytical results are not
quantitatively accurate; however, the analyses  are useful to
indicate the presence of a particular pollutant.   The  pesticide
fraction is considered not quantifiable at concentrations equal
to or less than 0.005 mg/1.

Second, the detection limits shown on the data  tables  for toxic
metals and conventional and nonconventional pollutants  are not
the same in all cases as the published detection  limits  for  these
pollutants by the same analytical methods.  The detection limits
used were reported with the analytical data and hence  are the
appropriate limits to apply to the data.  Detection  limit varia-
tion can occur as a result of a number of laboratory-specific,
equipment-specific, and daily operator-specific factors.  These
factors can include day-to-day differences in machine  calibra-
tion, variation in stock solutions, and variation  in operators.

Third, the statistical analysis of data includes  some  samples
measured at concentrations considered not quantifiable.  For data
considered as detected but below quantifiable concentrations,  a
                               44

-------
value of  zero  is used  for  averaging.   Toxic organic,  nonconven-
tional, and conventional pollutant  data reported with a "less
than" sign are considered  as  detected,  but not further quantifi-
able.  A  value of  zero  is  also  used for averaging.   If a pollu-
tant is reported as not detected,  it  is assigned a value of zero
in calculating the average.   Finally,  toxic metal values reported
as less than a certain  value  were  considered as below quantifica-
tion, and consequently  were assigned  a  value of zero  in the
calculation of the average.

Finally,  appropriate source water  concentrations are  presented
with the  summaries of  the  sampling  data.   The method  by which
each sample was collected  is  indicated  by number, as  follows:

     1     One-time grab
     2     Manual  composite during  intermittent process operation
     3     8-hour  manual composite
     4     8-hour  automatic composite
     5     24-hour manual  composite
     6     24-hour automatic  composite

WASTEWATER CHARACTERISTICS AND  FLOWS  BY SUBDIVISION

Since primary  precious  metals and mercury production  involves 11
principal sources  of wastewater and each has potentially differ-
ent characteristics and flows,  the  wastewater characteristics and
discharge rates corresponding to each subdivision will be
described separately.   A brief  description of why the associated
production processes generate a wastewater and explanations for
variations of  water use within  each subdivision will  also be
discussed.

SMELTER WET AIR POLLUTION  CONTROL

Six of the eight plants in this  subcategory smelt or  roast the
precious metal-bearing  raw material.  Only three of those facil-
ities, however, use a wet  air pollution control device to control
air emissions  from the  furnace.  Two  of these devices are scrub-
bers, while one (at plant  1003)  is  an electrostatic precipitator
(ESP).  Two plants practice dry  air pollution control,  and one
plant does not practice any air  pollution control.  The produc-
tion normalized water use and discharge rates are presented in
Table V-1  in liters per troy ounce  of gold and silver smelted.

Analytical data for the combined smelter  wet air pollution con-
trol and electrolytic cells wet  air pollution control waste
streams are contained in the confidential record.   The data show
that this  wastewater contains treatable concentrations of toxic
metals,  suspended solids, and oil and grease.
                               45

-------
SILVER  tILORIDE REDUCTION SPENT  SOLUTION

Only on  plant in the subcategory uses  the Miller  process  to
refine  are metal.  Spent solution  from the  reduction  of  silver
chlorid  to silver metal is a potential waste  stream.   The pro-
duction lormalized water use and discharge flows are presented in
Table V 2, in liters per troy ounce of  silver  reduced  in
solutio .

Samplin  data for spent solution are contained  in  the
confide tial record.  This waste stream is very acidic (pH 0.9)
and the sampling data indicate that high  concentrations of toxic
metals, suspended solids, and oil and grease are present.

ELECTRC YTIC CELLS WET AIR POLLUTION CONTROL

The use of wet scrubbers to control emissions  from electrolytic
cells i  practiced at only one plant in this subcategory.   Pro-
duction normalized water use and discharge rates are presented in
Table V 3.  Sampling data for the combined smelter wet air pollu-
tion cc trol and electrolytic cell  wet  air pollution control
waste s ream are contained in the confidential  record.  The data
show th s waste stream to contain treatable  concentrations of
toxic m tals, suspended solids,  and oil and  grease.

ELECTRC YTE PREPARATION WET AIR  POLLUTION CONTROL

The sil er nitrate electrolyte used in  the electrolytic refining
of Dore metal is prepared by combining  pure  silver with nitric
acid.   cie one facility that uses this  process  also uses  a wet
scrubbe  to control air emissions from  the preparation step,
thereby generating a waste stream.  Production  normalized  water
use and discharge rates are presented in  Table  V-4 in  liters per
troy ou ce of silver in electrolyte produced.   No  sampling data
were ga tiered for this waste stream; however,  it is expected to
have ch racteristics similar to  those of  the combined  raw  waste-
waters  rom smelter wet air pollution control  and  the  electroly-
tic eel  scrubber.  This waste stream,  therefore,  is expected to
contain treatable concentrations of suspended  solids,  toxic
metals, and oil and grease.

SILVER  RYSTAL WASH WATER

After e ectrolytic refining of Dore metal, the  silver  which is
deposit d upon the cathode is removed and washed.   Production
normali ed water use and discharge  rates  for this  waste stream
are pre ented in Table V-5, in liters per troy  ounce of silver
crystal  washed.
                               46

-------
Although no  samples  of  this  waste  stream were analyzed,  it is
expected that its characteristics  will  be similar  to wastewater
from  the secondary silver  subcategory,  and is contained  in the
nonferrous phase  I public  record for  that subcategory (see stream
40 at secondary silver  plant A).   The data show treatable concen-
trations of  toxic metals,  suspended solids,  and oil and  grease.

GOLD  SLIMES  ACID WASH AND  WATER RINSE

Gold  slimes  remaining in the canvas anode bag from electrolytic
refining of  Dore metal  contain significant amounts of gold and
some  silver.  The gold  slimes are  washed with nitric acid and
water to remove the  silver by dissolving it  into solution.  These
wash  waters  are currently  sent to  a cementation step,  and repre-
sent  a potential source of wastewater.   Production normalized
water use and discharge rates for  this  subdivision are presented
in Table V-6 in liters  per troy ounce of gold slimes washed.   No
sampling data were collected for this waste  stream; however,  it
is expected  to have  characteristics similar  to those of  gold
precipitation and filtration (a very  similar process step) waste-
water in the secondary  precious metals  subcategory.  This waste
stream, therefore, is expected to  contain treatable concentra-
tions of toxic metals and  suspended solids.

CALCINER WET AIR POLLUTION CONTROL.

One of the two plants producing primary mercury uses a water
scrubber to  control  air emissions  from  the calciner.   This plant
uses  a series of three  scrubbers (Venturi,  Impinger,  and S02).
Sampling data for the wastewater generated by these scrubbers are
presented in Table V-12.   The scrubber  waters have a low pH (2.3
to 2.6) and  contain  treatable concentrations of toxic  metals  such
as lead, mercury, thallium and zinc,  and suspended solids. The
production normalized water  use and discharge rates are  shown in
Table V-7.

CALCINE QUENCH WATER

One mercury  producer uses  water to quench the waste calcines  from
the mercury  roaster to allow faster handling and disposal of
these  materials.  Table V-8  presents  the production normalized
water use and discharge rates for  this  waste stream.   Sampling
data  are summarized  in Table V-13  and show high concentrations of
toxic metals such as arsenic, mercury and zinc,  and suspended
solids.  This waste stream has a nearly neutral pH of  6.8.

CALCINER STACK GAS CONTACT COOLING WATER

One facility uses contact  cooling water  to reduce  the  temperature
of the calciner off-gases before releasing them to  the atmo-
sphere.  Sampling data for this waste stream are summarized in
                               47

-------
Table V-14.  This waste stream has a pH of  2.5 and  contains
treatable concentrations of mercury and suspended solids.   Pro-
duction normalized water use and discharge  rates are  given  in
Table V-9.

CONDENSER SLOWDOWN

When mercury is vaporized in the calciner,  some water  contained
in the Cinnibar or gold ore may also be vaporized.  The  condensa-
tion of mercury for recovery may result in  the condensation  of
some water which is discharged as condenser blowdown.  Table V-10
summarizes the production normalized water  use and  discharge
rates for this waste stream.

Although no sampling data were collected  for  this waste  stream,
it is expected to be very similar to the  discharge  from  the
mercury cleaning bath.  The data are presented in Table  V-15, and
the condenser blowdown stream is expected to  contain  treatable
concentrations of mercury and suspended solids.

MERCURY CLEANING BATH WATER

Condensed mercury is processed for the removal of impurities by
being passed through a water cleaning bath.   This Waste  stream
contains treatable concentrations of mercury  and suspended  solids
and very low concentrations of other toxic metals.  The  sampling
data for this waste stream are presented  in Table V-15.   Produc-
tion normalized water use and discharge rates are provided  in
Table V-11.
                               48

-------
                            Table V-1

                WATER USE AND DISCHARGE RATES FOR
                SMELTER WET AIR POLLUTION CONTROL

          (liters/troy ounce of gold and silver smelted)
       Plant Code

          1131*

          1003

          1137

          1068

          1158
Percent
Recycle

   76

   90

  100

  Dry

  Dry
Production
Normalized
Water Use

  25.8

   5.3

   8.41
Production
Normalized
Discharge
   Flow  -

   6.2

   0.53

   0
*No operations conducted in 1982; water use and discharge rates
 based on projected 1983 figures.
                               49

-------
                     Table V-2

         WATER USE AND DISCHARGE RATES FOR
      SILVER CHLORIDE REDUCTION SPENT SOLUTION

 (liters/troy ounce of silver reduced in solution)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1003            0          0.4             0.4
                         50

-------
                     Table V-3

         WATER USE AND DISCHARGE RATES FOR
    ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL

(liters/troy ounce of gold refined electrolytically)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1003            0          198            198
                       51

-------
                      Table V-4

          WATER USE AND DISCHARGE RATES FOR
  ELECTROLYTE PREPARATION WET AIR POLLUTION CONTROL

(liters/troy ounce of silver in electrolyte produced)
                                           Production
                            Production     Normalized
                Percent     Normalized     Discharge
 Plant Code     Recycle     Water Use         Flow

    1160           0           0.05           0.05
                        52

-------
                     Table V-5

         WATER USE AND DISCHARGE RATES FOR
             SILVER CRYSTAL WASH WATER

   (liters/troy ounce of silver crystals washed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1160           0           0.29           0.29
                         53

-------
                     Table V-6

         WATER USE AND DISCHARGE RATES FOR
       GOLD SLIMES ACID WASH AND WATER RINSE

     (liters/troy ounce of gold slimes washed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1160           0           4.0            4.0
                         54

-------
                     Table V-7

         WATER USE AND DISCHARGE RATES FOR
         CALCINER WET AIR POLLUTION CONTROL

         (liters/kkg of mercury condensed)
Plant Code

   1124
(Venturi)

   1124
(Impinger)

   1124
(S02)

TOTAL
Percent
Recycle

   16
   16
   16
   16
Production
Normalized
Water Use

   4,607
   7,536
 209.524
 221,667
Production
Normalized
Discharge
   Flow

   3,870
   6,330
 176.000
 186,200
                         55

-------
                     Table V-8

         WATER USE AND DISCHARGE RATES FOR
                CALCINE QUENCH WATER

         (liters/kkg of mercury condensed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1124           0          17,600         17,600
                        56

-------
                     Table V-9

         WATER USE AND DISCHARGE RATES FOR
      CALCINER STACK GAS CONTACT COOLING WATER

         (liters/kkg of mercury condensed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1124           0           4,150          4,150
                         57

-------
                     Table V-10

         WATER USE AND DISCHARGE RATES FOR
                 CONDENSER SLOWDOWN

         (liters/kkg of mercury condensed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

   1068       '    0          13,800          13,800

   1124          Dry
                         58

-------
                     Table V-11

         WATER USE AND DISCHARGE RATES FOR
            MERCURY CLEANING BATH WATER

         (liters/kkg of mercury condensed)
                                          Production
                           Production     Normalized
               Percent     Normalized     Discharge
Plant Code     Recycle     Water Use         Flow

  '1124           0           1,400          1,400
                         59

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Hg Raw
Material
                                                 To Tailings
                                                 To Tailings
                                                 To Tailings
                                                 To Tailings
                                                 To Tailings
                                          Mercury Product


                                              " * To Tailings
                         Figure V-1

         SAMPLE LOCATIONS AT PRIMARY  PRECIOUS
               METALS AND MERCURY  PLANT A
                            75

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76

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         PRIMARY  PRECIOUS METALS  AND  MERCURY SUBCATEGORY

                             SECTION VI

                SELECTION OF POLLUTANT  PARAMETERS
Section V of this supplement presented  data  from primary precious
metals and mercury plant  sampling  visits  and subsequent chemical
analyses.  The analytical data  from  one primary  precious metals
plant was not presented in  Section V because it  was  claimed to be
confidential.  This section examines  both the confidential and
nonconfidential data and  discusses the  selection or  exclusion of
pollutants for potential  limitation.  The legal  basis  for the
exclusion of toxic pollutants under  Paragraph 8(a) of  the
Settlement Agreement is presented  in Section VI  of the General
Development Document.

Each pollutant selected for potential limitation is  discussed in
Section VI of the General Development Document.   That  discussion
provides information concerning the  nature of the pollutant
(i.e., whether it is a naturally occurring substance,  processed
metal, or a manufactured  compound);  general  physical properties
and the form of the pollutant;  toxic  effects of  the  pollutant in
humans and other animals; and behavior  of the pollutant in POTW
at the concentrations expected  in  industrial discharges.

The discussion that follows describes the analysis that was per-
formed to select or exclude toxic  pollutants for further consid-
eration for limitations and standards.  Also,  it describes the
analysis that was performed to  select or  exclude conventional
pollutants for limitation.  Toxic  pollutants will be considered
for limitation if they are present in concentrations treatable by
the technologies considered in  this  analysis.  The treatable
concentrations used for the toxic  metals  were the long-term
performance values achievable by chemical precipitation,  sedimen-
tation, and filtration.   The treatable  concentrations  used for
the toxic organics were the long-term performance values  achiev-
able by carbon adsorption (see  Section  VII of the General
Development Document Combined Metals  Data Base).

CONVENTIONAL POLLUTANT PARAMETERS

This study examined samples from the  primary precious  metals and
mercury subcategory for three conventional pollutant parameters
(oil and grease,  total suspended solids,  and pH).

CONVENTIONAL POLLUTANT PARAMETERS  SELECTED

The conventional pollutants or  pollutant  parameters  selected for
limitation in this subcategory  are:
                               77

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     oil and grease
     total suspended solids  (TSS)
     PH

Oil and grease was detected  in two of  10 samples at  concentra-
tions above the treatability concentration of  10.0 mg/1.   The
measured concentrations were 60 and 170 mg/1.  These high  concen-
trations occurred in the combined raw wastewater stream  from the
smelter and electrolytic cells wet air pollution control and in
the silver chloride reduction spent solution.  Therefore,  oil and
grease is selected for limitation in this subcategory.

TSS was detected at concentrations above the treatability  concen-
tration of 2.6 mg/1 in eight of the 10 raw waste samples analyzed
for this study.  These eight TSS concentration values  ranged from
4 to 3,700 mg/1.  Furthermore, most of the specific methods used
to remove toxic metals do so by converting these metals  to pre-
cipitates, and these toxic-metal-containing precipitates should
not be discharged.  Meeting  a limitation on total suspended
solids helps ensure that removal of these precipitated toxic
metals has been effective.   For these reasons, total suspended
solids are selected for limitation in this subcategory.

The nine pH values observed  during this study  ranged from  0.9 to
8.4.  Six of the nine values were equal to or  less than  2.6, one
value was 6.8 and the other  two fell within the 7.5  to 10.0 range
considered desirable for discharge to receiving waters.  Many
deleterious effects are caused by extreme pH values  or rapid
changes in pH.  Also, effective removal of toxic metals  by
precipitation requires careful control of pH.  Since pH  control
within the desirable limits  is readily attainable by available
treatment, pH is selected for limitation in this subcategory.

TOXIC POLLUTANTS

The frequency of occurrence  of the toxic pollutants  in the raw
wastewater samples taken is  presented  in Table VI-1.   Table VI-1
is based on the raw wastewater data presented  in Section V (see
Tables V-12 through V-15) as well as the primary precious  metals
analytical data being held confidential.  These data provide the
basis for the categorization of specific pollutants, as  discussed
below.

TOXIC POLLUTANTS NEVER DETECTED

The toxic pollutants listed  below were not detected  in any raw
wastewater samples from this subcategory; therefore, they  are not
selected for consideration in establishing limitations:

       1.  acenaphthene
       2.  acrolein
       3.  acrylonitrile
                               78

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 5.  benzidine
 6.  carbon tetrachloride
 7.  chlorobenzene
 8.  1,2,4-trichlorobenzene
 9.  hexachlorobenzene
10.  1,2-dichloroethane
11.  1,1,1-trichloroethane
12.  hexachloroethane
13.  1,1-dichloroethane
14.  1,1,2-trichloroethane
15.  1,1,2,2-tetrachloroethane
16.  chloroethane
17.  bis(2-chloromethyl) ether  (deleted)
18.  bis(2-chloroethyl) ether
19.  2-chloroethyl vinyl ether
20.  2-chloronaphthalene
21.  2,4,6-trichlorophenol
22.  parachlorometa cresol
23.  chloroform
24.  2-chlorophenol
25.  1,2-dichlorobenzene
26.  1 ,3-dichlorobenzene
27.  1,4-dichlorobenzene
28.  3,3'-dichlorobenzidine
29.  1,1-dichloroethylene
30.  1,2-trans-dichloroethylene
31.  2,4-dichlorophenol
32.  1,2-dichloropropane
33.  1,3-dichloropropylene
34.  2,4-dimethylphenol
35.  2,4-dinitrotoluene
36.  2,6-dinitrotoluene
37.  1 ,2-diphenylhydrazine
38.  ethylbenzene
39.  fluoranthene
40.  4-chlorophenyl phenyl ether
41.  4-bromophenyl phenyl ether
42.  bis(2-chloroisopropyl)ether
43.  bis(2-chloroethoxy)methane
45.  methyl chloride (chloromethane)
46.  methyl bromide (bromomethane)
47.  bromoform
48.  dichlorobromomethane
49.  trichlorofluoromethane (deleted)
50.  dichlorodifluoromethane (deleted)
51.  chlorodibromomethane
52.  hexachlorobutadiene
53.  hexachlorocyclopentadiene
54.  isophorone
55.  naphthalene
56.  nitrobenzene
                          79

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 57.   2-nitrophenol
 58.   4-nitrophenol
 59.   2,4-dinitrophenol
 60.   4,6-dinitro-o-cresol
 61.   N-nitrosodimethylamine
 62.   N-nitrosodiphenylamine
 63.   N-nitrosodi-n-propylamine
 64.   pentachlorophenol
 67.   butyl benzyl phthalate
 69.   di-n-octyl  phthalate
 71.   dimethyl phthalate
 72.   benzo(a)anthracene
 73.   benzo(a)pyrene
'74.   3,4-benzofluoranthene
 75.   benzo(k)fluoranthene
 76.   chrysene
 77.   acenaphthylene
 79.   benzo(ghi)perylene
 80.   fluorene
 82.   dibenzo(a,h)anthracene
 83.   indeno (1,2,3-cd)pyrene
 84.   pyrene
 85.   tetrachloroethylene
 87.   trichloroethylene
 88.   vinyl chloride
 89.   aldrin
 90.   dieldrin
 91.   chlordane
 92.   4,4'-DDT
 93.   4,4'-DDE
 94.   4,4'-DDD
 95.   alpha-endosulfan
 96.   beta-endosulfan
 97.   endosulfan  sulfate
 98.   endrin
 99.   endrin aldehyde
100.   heptachlor
101.   heptachlor  epoxide
102.   alpha-BHC
103.   beta-BHC
104.   gamma-BHC
105.   delta-BHC
106.   PCB-1242     (a)
107.   PCB-1254     (a)
108.   PCB-1221     (a)
109.   PCB--.232     (b)
110.   PCB-1248     (b)
111.   PCB-1260     (b)
112.   PCB-1016     (b)
113.   toxaphene
                          80

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      116.  asbestos
      129.  2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

 (a),(b)  Reported  together.

 TOXIC POLLUTANTS NEVER FOUND ABOVE  THEIR ANALYTICAL QUANTIFICA-
 TION  CONCENTRATION

 The toxic pollutants  listed below were  never  found above their
 analytical quantification  concentration in  any raw wastewater
 samples from  this  subcategory;  therefore, they are not selected
 for consideration  in  establishing limitations.

      65.  phenol
      66.  bis(2-ethylhexyl) phthalate
      68.  di-n-butyl phthalate
      78.  anthracene      (a)
      81.  phenanthrene     (a)
      114.  antimony

 (a)  Reported together.

 TOXIC POLLUTANTS PRESENT BELOW  CONCENTRATIONS ACHIEVABLE BY
 TREATMENT

 The pollutants  listed below are not  selected  for  consideration in
 establishing  limitations because  they were  not found in any raw
 wastewater samples from this subcategory above concentrations
 considered achievable by existing or available treatment tech-
 nologies.  These pollutants are discussed individually following
 the list.

      117.  beryllium
     125.  selenium

 Beryllium was detected at  a concentration of  0.15 mg/1 in one of
 the 10 samples  analyzed.   Available  treatment methods  can reduce
 beryllium concentrations only to  0.2 mg/1 and this pollutant is,
 therefore, not  considered  for limitation.

 Selenium was detected in two of 10 samples  at concentrations
 ranging from 0.044 to 0.063 mg/1.  These  concentrations are below
 the minimum selenium  concentration of 0. 2 mg/1 achievable by
 available treatment methods.  Additionally, these concentrations
of selenium may be attributable to its  presence in the source
water at a concentration of 0.10  mg/1.   Selenium,  therefore,  is
not considered  for limitation.
                               81

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TOXIC POLLUTANTS DETECTED  IN A  SMALL  NUMBER  OF  SOURCES

The following pollutants were not  selected for  limitation  because
they are detectable in the effluent from only a small number  of
sources within the subcategory  and they are  uniquely related  to
only those sources.

       4.  benzene
      44.  methylene chloride
      70.  diethyl phthalate
      86.  toluene
     121.  cyanide

Although these pollutants were  not selected  for limitation in es-
tablishing nationwide regulations, it may be appropriate,  on  a
case-by-case basis, for the local permitter  to  specify  effluent
limitations.

Benzene was detected above its  treatable concentration  of  0.01
mg/1 in one of three samples analyzed at a concentration of 0.016
mg/1.  This pollutant is not attributable to specific materials
or processes asociated with the primary precious metals and
mercury subcategory, and is not expected to  be  present  in  the
wastewater.  For this reason, and because very  little removal of
benzene can be expected with treatment, this pollutant  is  not
considered for limitation.

Methylene chloride was detected above its treatability  concentra-
tion of 0.01 mg/1 at concentrations ranging  from 0.036  to  0.046
mg/1 in all three samples analyzed.   This pollutant is  not
attributable to specific materials or processes associated with
the primary precious metals and mercury subcategory, but is a
common solvent used in analytical  laboratories.  Because methyl-
ene chloride is not expected to be present in the wastewater,  as
well as the high probability of sample contamination, this
pollutant is not considered for limitation.

Diethyl phthalate was detected  above  its treatable concentration
of 0.01 mg/1 in one of three samples  analyzed at a concentration
of 0.016 mg/1.  This pollutant  is not attributable to specific
materials or processes associated with the primary precious
metals and mercury subcategory, and is not expected to  be  present
in the wastewater.  For this reason,  and because very little
removal of diethyl phthalate can be expected with treatment,  this
pollutant is not considered for limitation.

Toluene was detected above its  treatable concentration  of  0.01
mg/1 in two of three samples analyzed at concentrations of 0.023
and 0.05 mg/1.  This pollutant  is not attributable to specific
materials or processes associated with the primary precious
                               82

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metals and mercury  subcategory,  and is  not expected to be present
in  the wastewater.   For  this  reason,  and because very little
removal  of toluene  can  be  expected with treatment,  this pollutant
is  not considered for limitation.

Cyanide  was measured at  concentrations  ranging from 0.049 to 0.2
mg/1  in  three of the four  samples  for which it was  analyzed.
These concentrations are above  the treatability concentration of
0.047 mg/1, but are suspected to be present because of source
water contamination.  The  source water  was found to contain
cyanide  at a concentration of 8.6 mg/1.   Because of its presence
in  the source water at a high concentration,  cyanide is not
considered for limitation.

TOXIC POLLUTANTS SELECTED  FOR FURTHER CONSIDERATION IN ESTAB-
LISHING  LIMITATIONS AND  STANDARDS

The toxic pollutants listed below are selected for  further con-
sideration in establishing limitations  and standards for this
subcategory.  The toxic  pollutants selected for further consider-
ation for limitation are each discussed  following the list.

      115.  arsenic
      118.  cadmium
      11 9.  chromium
      120.  copper
      122.  lead
      123.  mercury
      124.  nickel
      126.  silver
      127.  thallium
      128.  zinc

Arsenic was detected in  two of  10  samples  at  concentrations of
0.6 and  17 mg/1.  The concentration achievable by treatment
methods is 0.34 mg/1.  These  concentrations were detected in
silver chloride reduction  spent  solution and  calcine quench
water.  Arsenic was  detected, but  at  levels below treatability,
in  the other eight  samples.   Therefore,  arsenic is  selected for
further consideration for  limitation.

Cadmium was detected above  its  treatable concentration (0.049
mg/1) in two of 10  raw wastewater  samples  analyzed.   The treat-
able concentrations were detected  in  silver chloride reduction
spent solution and  calcine  quench  water.   Therefore,  cadmium is
selected for further consideration  for limitation.

Chromium was detected above its  treatable  concentration of 0.07
mg/1 in silver chloride  reduction  spent  solution and calcine
quench water.   The highest  concentration was  25 mg/1.   All eight
                               33

-------
other samples indicated that chromium was present, but  at  a
concentration below treatability.  Therefore, chromium  is
selected for further consideration for  limitation.

Copper was measured in two samples at concentrations  above the
treatable concentration of 0.39 mg/1.   Copper was also  detected
in the remaining eight samples, but at  concentrations below  that
achievable by treatment.  The highest concentration of  copper
found was 23,000 mg/1.  Therefore, copper is selected for  further
consideration for limitation.

Lead was detected in six raw waste streams at concentrations
above the 0.08 mg/1 attainable by identified treatment  technol-
ogy.  These concentrations ranged from  0.1 to 600 mg/1.  For this
reason, lead is selected for further consideration for  limita-
tion.

Mercury was detected in six of the 10 samples analyzed  at  concen-
trations ranging from 0.84 to 360 mg/1.  These concentrations are
well above the concentration of 0.036 achievable by current
treatment methods.  In addition, mercury was detected in the
remaining four samples, but at values below the treatable  concen-
tration.  For these reasons, mercury is selected for  further
consideration for limitation.

Nickel was detected in the silver chloride reduction  spent solu-
tion at a concentration of 29 mg/1.  The treatable concentration
for nickel is 0.22 mg/1.  Nickel was detected, but below treata-
ble concentrations in all nine of the other samples.  Therefore,
nickel is selected for further consideration for limitation.

Silver was detected in two samples at concentrations of 0.13 and
6.1 mg/1.  These concentrations are above silver's treatable
concentration of 0.07 mg/1.  Silver is, therefore, selected  for
further consideration for limitation.

Thallium was detected above its treatable concentration (0.34
mg/1) in two of 10 samples analyzed.  The quantifiable  concentra-
tions ranged from 0.12 to 2.6 mg/1.  Since thallium was present
in concentrations exceeding the concentration achievable by  iden-
tified treatment technology, it is selected for consideration for
limitation.

Zinc was detected above its treatable concentration (0.23  mg/1)
in three of 10 samples analyzed.  The quantifiable concentrations
ranged from 0.10 to 15.0 mg/1.  Since zinc was present  in  concen-
trations exceeding the concentration achievable by identified
treatment technology, it is selected for consideration  for
limitation.
                               84

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          PRIMARY  PRECIOUS  METALS  AND MERCURY SUBCATEGORY

                            SECTION VII

                CONTROL AND TREATMENT TECHNOLOGIES


The preceding sections  of  this  supplement  discussed the sources,
flows, and  characteristics of  the wastewaters from primary pre-
cious metals and  mercury plants.   This  section summarizes the
description of  these wastewaters  and indicates the treatment
technologies which are  currently  practiced in the  primary
precious  metals and mercury subcategory for each waste stream.
Secondly, this  section  presents the  control and treatment tech-
nology options  which were  examined by the  Agency for possible
application to  the primary precious  metals and mercury
subcategory.

CURRENT CONTROL AND TREATMENT  PRACTICES

Control and treatment technologies are  discussed in general in
Section VII of  the General Development  Document.   The basic prin-
ciples of these technologies and  the applicability to wastewater
similar to that found in this  subcategory  are presented there.
This section presents a summary of the  control and treatment
technologies that are currently being applied to each of the
sources generating wastewater  in  this subcategory.   As discussed
in Section V, wastewater associated  with the primary precious
metals and mercury subcategory  is characterized by the presence
of the toxic metal pollutants,  suspended solids, and oil and
grease.   This analysis  is  supported  by  the raw (untreated)
wastewater data presented  for  specific  sources.  Construction of
one wastewater  treatment system for  combined treatment allows
plants to take  advantage of  economic scale and in  some instances
to combine streams of different alkalinity to reduce treatment
chemical  requirements.

All but one of  the plants  within  this subcategory  have a zero
discharge status.  The  one  discharging  facility discharges  to a
surface water from a tailings pond.   Zero  discharge is achieved
in most plants  through  a combination treatment system consisting
of a tailings pond and  recycle or reuse.   One of the three  plants
with a smelter  scrubber  achieves  zero discharge of that waste
stream by 100 percent recycle.  Partial recycle is  used only on
two waste streams, the  smelter scrubber and the calciner scrubber
wastewater.   Table VII-1 presents  a  summary of the  number of
plants with each waste  stream and the treatment technologies
currently in place.
                               89

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CONTROL AND TREATMENT OPTIONS

The Agency examined three control and  treatment  technology
options that are applicable to the primary precious metals  and
mercury subcategory.  The options selected for evaluation
represent a combination of in-process  flow reduction,  preliminary
treatment technologies applicable to individual  waste  streams,
and end-of-pipe treatment technologies.

OPTION A

Option A for the primary precious metals and mercury subcategory
requires control and treatment technologies to reduce  the
discharge of wastewater volume and pollutant mass.

The Option A treatment scheme consists of chemical precipitation
and sedimentation technology.  Specifically, lime or some other
alkaline compound is used to precipitate toxic metal ions as
metal hydroxides.  The metal hydroxides and suspended  solids
settle out and the sludge is collected.  Vacuum  filtration  is
used to dewater sludge.

Preliminary treatment consisting of oil skimming to remove  oil
and grease is also included in Option  A.

OPTION B

Option B for the primary precious metals and mercury subcategory
consists of the Option A (oil skimming, chemical precipitation
and sedimentation) treatment scheme plus flow reduction  tech-
niques to reduce the discharge of wastewater volume.   In-process
changes which allow for recycle of smelter, electrolytic cells,
and calciner scrubber water are the principal control  mechanisms
for flow reduction.

OPTION C

Option C for the primary precious metals and mercury subcategory
consists of all control and treatment  requirements of  Option B
(in-process flow reduction, oil skimming, chemical precipitation
and sedimentation) plus multimedia filtration technology added at
the end of the Option B treatment scheme.  Multimedia  filtration
is used to remove suspended solids, including precipitates  of
metals, beyond the concentration attainable by gravity sedimen-
tation.  The filter suggested is of the gravity, mixed-media
type, although other forms of filters, such as rapid sand filters
or pressure filters would perform satisfactorily.  The addition
of filters also provides consistent removal during periods  of
time in which there are rapid increases in flows or loadings of
pollutants to the treatment system.
                               90

-------
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          PRIMARY  PRECIOUS METALS AND MERCURY SUBCATEGORY

                            SECTION  VIII

            COSTS, ENERGY,  AND  NONWATER  QUALITY ASPECTS


This section presents a summary of  compliance  costs  for  the
primary precious  metals and mercury subcategory and  a description
of the treatment  options and subcategory-specific  assumptions
used to develop these estimates.  Together with the  estimated
pollutant reduction performance presented in Sections IX,  X, XI,
and XII of this supplement, these cost etimates provide  a  basis
for evaluating each regulatory  option.   These  cost estimates are
also used in determining the probable economic impact of regula-
tion on the subcategory at  different pollutant discharge levels.
In addition, this section addresses nonwater quality environ-
mental impacts of wastewater treatment and control alternatives,
including air pollution, solid  wastes, and energy  requirements,
which are specific to the primary precious metals  and mercury
subcategory.

TREATMENT OPTIONS FOR EXISTING  SOURCES

As discussed in Section VII, three  treatment options have  been
developed for existing primary  precious metals  and mercury
sources.  The options are summarized below and schematically
presented in Figures X-1 through X-3.

OPTION A

Option A consists of preliminary treatment using oil/water-
separation where  required and chemical precipitation and sedimen-
tation end-of-pipe technology.

OPTION B

Option B consists of in-process flow reduction  and oil/water
separation preliminary treatment where required, and end-of-pipe
technology consisting of chemical precipitation and  sedimenta-
tion.   The in-process flow  reduction measure consists  of the
recycle of smelter scrubber water,  electrolytic cells  scrubber
water,  and calciner scrubber water  through holding tanks.

OPTION C

Option C requires the in-process flow reduction and  oil/water
separation preliminary treatment measures of Option  B, and end-
of-pipe treatment technology consisting of chemical  precipita-
tion,  sedimentation,  and multimedia filtration.
                               93

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COST METHODOLOGY

A detailed discussion of the methodology used  to develop  the  com-
pliance costs is presented in Section VIII of  the General Devel-
opment Document.  Plant-by-plant compliance  costs have  been
estimated for the nonferrous metals manufacturing category and
are presented in the administrative record supporting this regu-
lation.  The costs developed for the proposed  regulation  are  pre-
sented in Table VIII-1 for the direct dischargers.

Each of the general assumptions used to develop compliance costs
is presented in Section VIII of the General  Development Document.
No subcategory-specific assumptions were used  in developing
compliance costs for the primary precious metals and mercury
subcategory.

NONWATER QUALITY ASPECTS

A general discussion of the nonwater quality aspects of the con-
trol and treatment options considered for the  nonferrous  metals
category is contained in Section VIII of the General Development
Document.  Nonwater quality impacts specific to the primary pre-
cious metals and mercury subcategory, including energy  require-
ments, solid waste and air pollution, are discussed below.

ENERGY REQUIREMENTS

The methodology used for determining the energy requirements  for
the various options is discussed in Section  VIII of the General
Development Document.  Energy requirements for the three  options
considered are estimated at 4,224 kWh/yr, 4,224 kWh/yr, and 5,155
kWh/yr for Options A, B, and C, respectively.  Option B energy
requirements are the same as those for Option  A because the one
discharging plant has no flow reduction.  Option C, which
includes filtration, increases energy consumption over  Option B
by approximately 18 percent.  Option C represents roughly 1
percent of a typical plant's electrical energy usage.   It is
therefore concluded that the energy requirements of the treatment
options considered will have no significant  impact on total plant
energy consumption.

SOLID WASTE

Sludge generated in the primary precious metals and mercury
subcategory is due to oily wastes from oil/water separation and
the precipitation of meual hydroxides and carbonates using lime.
Sludges associated with the primary precious metals and mercury
subcategory will necessarily contain quantities of toxic  metal
pollutants.  These sludges are not subject to  regulation  as
hazardous wastes since wastes generated by primary smelters and
                                94

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refiners  are  currently  exempt  from  regulation by Act of Congress
(Resource  Conservation  and  Recovery  Act  (RCRA),  Section 3001(b) ) ,
as  interpreted  by  EPA.   If  a small  excess  of lime is added during
treatment, the  Agency does  not  believe these sludges would be
identified as hazardous under  RCRA  in  any  case.   (Compliance
costs include this amount of lime.)  This  judgment  is based on
the  results of  Extraction Procedure  (EP) toxicity tests performed
on similar sludges (toxic metal-bearing  sludges)  generated by
other industries such as the iron and  steel  industry.  A small
amount of  excess lime was added  during treatment,  and the sludges
subsequently  generated  passed  the toxicity test.   See CFR
§261.24.   Thus, the Agency  believes  that the wastewater sludges
will similarly  not be EP toxic  if the  recommended technology  is
applied.

Although  it is  the Agency's view that  solid  wastes  generated  as  a
result of  these guidelines  are  not  expected  to be hazardous,
generators of these wastes  must  test the waste to determine if
the wastes meet any of  the  characteristics of hazardous waste
(see 40 CFR 262.11).

If these wastes should  be identified or  are  listed  as hazardous,
they will  come  within the scope  of RCRA's  "cradle to grave"
hazardous waste management  program,  requiring regulation from the
point of  generation to  point of  final  disposition.   EPA's gener-
ator standards  would require generators  of hazardous nonferrous
metals manufacturing wastes to  meet  containerization, labeling,
recordkeeping,  and reporting requirements; if plants dispose  of
hazardous wastes off-site,  they  would  have to prepare a manifest
which would track the movement  of the wastes  from the generator's
premises  to a permitted  off-site treatment,  storage, or disposal
facility.  See  40 CFR 262.20 45  FR 33142 (May 19,  1980),  as
amended at 45 FR 86973  (December 31, 1980).   The  transporter
regulations require transporters of hazardous  wastes to comply
with the manifest system to assure that  the  wastes  are delivered
to a permitted  facility.  See 40 CFR 263.20  45 FR 33151  (May  19,
1980), as amended at 45 FR  86973 (December 31,  1980).   Finally,
RCRA regulations establish  standards for hazardous  waste treat-
ment, storage,  and disposal facilities allowed to receive such
wastes.   See 40 CFR Part 464 46  FR 2802  (January  12, 1981), 47 FR
32274 (July 26, 1982).

Even if these wastes are not identified  as hazardous,  they still
must be  disposed of in  compliance with the Subtitle D open dump-
ing standards,  implementing 4004 of RCRA.  See 44 FR 53438
(September 13,  1979).    The Agency has calculated  as  part of the
costs for wastewater treatment  the cost  of hauling  and disposing
of these wastes.  For more details,  see  Section VIII of the
General Development Document.
                                95

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Sludge generation for BPT of the primary precious metals and
mercury subcategory is estimated at 11.355 metric tons per year.
Sludge generation for BAT is not expected to be significantly
different.

AIR POLLUTION

There is no reason to believe that any substantial air pollution
problems will result from implementation of oil/water separation,
chemical precipitation, sedimentation, and multimedia filtration.
These technologies transfer pollutants to solid waste and are not
likely to transfer pollutants to air.
                                96

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                  Table VIII-1

           COST OF COMPLIANCE FOR THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
               DIRECT DISCHARGERS

             (March,  1982 Dollars)
              Total Required        Total
   Option      Capital Cost      Annual Cost

     A           27,500             9,000

     B           27,500             9,000

     C           30,000            10,000
                     97

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         PRIMARY PRECIOUS METALS AND MERCURY  SUBCATEGORY

                            SECTION IX

                BEST  PRACTICABLE CONTROL  TECHNOLOGY
                        CURRENTLY AVAILABLE


This section defines  the effluent characteristics  attainable
through the application of best practicable control  technology
currently available (BPT), Section 301 (b) (a) (A) .   BPT reflects
the existing performance by plants of various  sizes,  ages,  and
manufacturing processes within the primary precious  metals  and
mercury subcategory,  as well as the established performance of
the recommended BPT systems.  Particular  consideration is  given
to the treatment already in place at plants within the data base.

The factors considered in identifying BPT include  the total cost
of applying the technology in relation  to the  effluent reduction
benefits from such application, the age of equipment  and facili-
ties involved, the manufacturing processes employed,  nonwater
quality environmental impacts (including  energy requirements),
and other factors the Administrator considers  appropriate.  In
general, the BPT level represents the average  of the  existing
performances of plants of various ages, sizes, processes,  or
other common characteristics.  Where existing  performance  is
uniformly inadequate, BPT may be transferred  from  a  different
subcategory or category.  Limitations based on transfer of
technology are supported by a rationale concluding that the
technology is, indeed, transferable, and a reasonable prediction
that it will be capable of achieving the  prescribed  effluent
limits (see Tanner's  Council of America v. Train,  540 F.2d  1188
(4th Cir. 1176).BPT focuses on end-o±-pipe  treatment rather
than process changes  or internal controls, except where such
practices are common  within the subcategory.

TECHNICAL APPROACH TO BPT

The Agency studied the nonferrous metals  category  to  identify  the
processes used, the wastewaters generated, and the treatment pro-
cesses installed.  Information was collected  from  the category
using data collection portfolios, and specific plants were  sam-
pled and the wastewaters analyzed.  In making  technical assess-
ments of data, reviewing manufacturing processes, and assessing
wastewater treatment  technology options, both  indirect and  direct
dischargers have been considered as a single group.   An examina-
tion of plants and processes did not indicate  any process  differ-
ences based on the type of discharge,  whether  it be direct  or
indirect.
                                 99

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As explained in Section  IV, the primary precious metals  and  mer-
cury subcategory has been subdivided  into  11 potential wastewater
sources.  Since the water use, discharge rates, and  pollutant
characteristics of each  of these wastewaters is potentially
unique, effluent limitations will be  developed  for each  of the  11
subdivisions.

For each of the subdivisions, a specific approach was followed
for the development of BPT mass limitations.  The first  require-
ment to develop these limititations is to  account for production
and flow variability from plant to plant.   Therefore, a  unit of
production or production normalizing  parameter  (PNP) was  deter-
mined for each waste stream which could then be related  to the
flow from the process to determine a  production normalized flow.
Selection of the PNP.for each process element is discussed in
Section IV.  Each process within the  subcategory was then ana-
lyzed to determine (1) which subdivisions  were  present,  (2)  the
specific flow rates generated for each subdivision,  and  (3)  the
specific production normalized flows  for each subdivision.  This
analysis is discussed in detail in Section V.   Nonprocess waste-
waters such as rainfall  runoff and noncontact cooling water  are
not considered in the analysis.

Production normalized flows for each  subdivision were then ana-
lyzed to determine the flow to be used as  part  of the basis  for
BPT mass limitations.   The selected flow (sometimes  referred to
as a BPT regulatory flow or BPT discharge  rate) reflects  the
water use controls which are common practices within the  cate-
gory.  The BPT regulatory flow is based on the  average of all
applicable data.  Plants with normalized flows  above the  average
may have to implement some method of  flow  reduction  to achieve
the BPT limitations.

The second requirement to calculate mass limitations is  the  set
of concentrations that are achievable by application of  the  BPT
level of treatment technology.  Section VII discusses the various
control and treatment technologies which are currently in place
for each wastewater source.  In most  cases, the current  control
and treatment technologies consist of a combination  of tailings
ponds and reuse and recycle of process water.   Chemical  precipi-
tation .and sedimentation technology and performance  is trans-
ferred to this subcategory, because current treatment is
inadequate.  Oil skimming is applied  to streams with treatable
concentrations of oil and grease.

Using these regulatory flows and the  achievable concentrations,
the next step is to calculate mass loadings for each wastewater
source or subdivision.   This calculation was made on a stream-by-
stream basis, primarily  because plants in  this  subcategory may
perform one or more of the operations in various combinations.
                              100

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The mass  loadings  (milligrams  of  pollutant  per  troy ounce or
metric ton of production  - mg/T.O.  or  mg/kkg) were  calculated by
multiplying the BPT regulatory flow (1/T.O.  or  1/kkg)  by the con-
centration achievable by  the BPT  level of  treatment technology
(mg/1) for each pollutant parameter to be  limited under BPT.
These mass loadings are published in the Federal Register and in
CFR Part  400 as the effluent limitations guidelines.

The mass  loadings  which are allowed under  BPT for each plant will
be the sum of the  individual mass loadings  for  the  various waste-
water sources which are found  at  particular  plants. Accordingly,
all the wastewater generated within a  plant  may be  combined for
treatment in a single or  common treatment  system, but  the efflu-
ent limitations for these combined  wastewaters  are  based on the
various wastewater sources which  actually  contribute  to the com-
bined flow.  This method  accounts for  the variety of combinations
of wastewater sources and production processes  which may be found
at primary precious metals and mercury plants.

The Agency usually establishes wastewater  limitations  in terms of
mass rather than concentration.   This  approach  prevents the use
of dilution as a treatment method (except for controlling pH).
The production normalized wastewater flow  (1/T.O. or 1/kkg) is a
link between the production operations and  the  effluent limita-
tions.  The pollutant discharge attributable to each operation
can be calculated  from the normalized  flow  and  effluent concen-
tration achievable by the treatment technology  and  summed to
derive an appropriate limitation  for each plant.

INDUSTRY COST AND  POLLUTANT REMOVAL ESTIMATES

In balancing costs in relation to pollutant  removal estimates,
EPA considers the volume  and nature of existing discharges, the
volume and nature of discharges expected after  application of
BPT, the general environmental effects of the pollutants,  and the
cost and economic  impacts of the  required pollution control
level.  The Act does not  require  or permit  consideration of water
quality problems attributable  to  particular  point sources  or
industries, or water quality improvements in particular water
quality bodies.   Accordingly,  water quality  considerations were
not the basis for selecting the proposed BPT.   See  Weyerhaeuser
Company v. Costle, 590 F.2d 1011  (D.C.   Cir.  1978).

The methodology for calculating pollutant removal estiamtes and
plant compliance costs is discussed in Section  X.   Table X-2
shows the estimated pollutant  removals  for each treatment  option
for direct dischargers.   Compliance costs are presented in Table
X-3.
                              101

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BPT OPTION SELECTION

The technology basis for the  BPT limitations  is  Option  A,  chemi-
cal precipitation and sedimentation  technology to  remove metals
and solids from combined wastewaters and  to control  pH, and oil
skimming to remove oil and grease.   These  technologies  are not
in-place at the one discharger  in  this  subcategory.   The pollu-
tants specifically proposed for regulation at BPT  are arsenic,
lead, mercury, silver, zinc,  oil and grease,  TSS,  and pH.

Implementation of the proposed  BPT limitations will  remove
annually an estimated 914 kg  of toxic metals  and 334 kg of TSS.
We project a capital cost of  $27,500 and  an annualized  cost of
$9,000 for achieving proposed BPT  limitations.

More stringent technology options  were  not selected  for BPT since
they require in-process changes or end-of-pipe technologies less
widely practiced in the subcategory, and,  therefore,  are more
appropriately considered under  BAT.

WASTEWATER DISCHARGE RATES

A BPT discharge rate is calculated for  each subdivision based  on
the average of the flows of the existing  plants, as  determined
from analysis of the dcp.  The  discharge  rate is used with the
achievable treatment concentration to determine  BPT  effluent
limitations.  Since the discharge  rate  may be different for each
wastewater source, separate production  normalized  discharge rates
for each of the 11 wastewater sources are  discussed  below  and
summarized in Table IX-1.  The  discharge  rates are normalized  on
a production basis by relating  the amount  of  wastewater generated
to the mass of the intermediate product which is produced  by the
process associated with the waste  stream  in question.   These pro-
duction normalizing parameters, or PNP's,  are also listed  in
Table IX-1.

Section V of this supplement  further describes the discharge flow
rates and presents the water  use and discharge flow  rates  for
each plant by subdivision.

SMELTER WET AIR POLLUTION CONTROL

The BPT wastewater discharge  rate  for smelter wet  air pollution
control is 13.2 liters per troy ounce (3.5 gal/troy  ounce)  of
gold and silver smelted, based  on  zero  percent recycle.  This
rate is allocated only for plants  practicing  wet air pollution
control for the smelter.  Three plants  reported  this waste
stream, as shown in Table V-1.  The  BPT rate  is  based on the
average water use rate for these three  plants (25.8,  8.4,  and  5.3
liters per troy ounce).
                               102

-------
EPA is also considering  a  BPT wastewater  discharge rate for this
waste stream of  1.32 liters per  troy  ounce,  based  on 90 percent
recycle.  Recycle  is demonstrated  for this  waste  stream.   EPA
will select between the  two flow rates  at promulgation, based on
public comment.

SILVER CHLORIDE  REDUCTION  SPENT  SOLUTION

The BPT wastewater discharge rate  for silver chloride reduction
spent solution is  0.4 liters per troy ounce (0.11  gal/troy ounce)
of silver reduced  in solution.   Water use and discharge rates are
presented in Table V-2.  This normalized  flow is based upon the
only reported value.

ELECTROLYTIC CELLS WET AIR POLLUTION  CONTROL

The BPT wastewater discharge rate  for the electrolytic cells wet
air pollution control is 198 liters per troy ounce (52.3 gal/troy
ounce) of gold refined electrolytically.  This  normalized flow is
based upon the only reported value for  this  subcategory.   The
reported water use and discharge rates  are  presented in Table
V-3.

ELECTROLYTE PREPARATION WET AIR  POLLUTION CONTROL

The BPT wastewater discharge rate  for the electrolyte preparation
wet air pollution control  is 0.05  liters  per troy  ounce (0.013
gal/troy ounce)  of silver  in the electrolyte produced.   This
normalized flow  is based upon the  only  value reported for this
subcategory.  Water use and discharge rates  are provided  in Table
V-4.

SILVER CRYSTAL WASH WATER

The BPT wastewater discharge rate  for silver crystal wash water
is 0.29 liters per troy ounce (0.08 gal/troy ounce)  of silver
crystals washed.  Table V-5 presents  the  water  use and discharge
rates for this waste stream.  The  BPT rate  is based  on the only
reported value.  This rate is allocated to  any  plant washing
silver crystals refined electrolytically.

GOLD SLIMES ACID WASH AND WATER  RINSE

The BPT wastewater discharge rate  for this waste stream is 4.0
liters per troy ounce (1.06 gal/troy  ounce)  of  gold  slimes
washed.   This normalized flow is equivalent  to  the only value
reported for gold slimes acid wash and  rinse waLer.   Water use
and discharge rates are provided in Table V-6.
                              103

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CALCINER WET AIR POLLUTION CONTROL

The BPT wastewater discharge rate for  the calciner  wet  air  pol-
lution control is 186,200 1/kkg  (49,200 gal/kkg) of mercury con-
densed.  This normalized flow is based upon  the  sum of  the  flows
from three in-series scrubbers at the  only facility reporting  a
calciner scrubber (plant 1124).  Table V-7 summarizes the water
use and discharge rates for this subdivision.  This discharge
rate represents 16 percent recycle of  scrubber liquor,  which is
the rate currently achieved by the one plant with this  stream.

CALCINE QUENCH WATER

The BPT wastewater discharge rate for  calcine quench water  is
17,600 1/kkg (4,650 gal/kkg) of mercury condensed.  This produc-
tion normalized discharge rate is based upon the only reported
value for this waste stream.  Water use and  discharge rates are
presented in Table V-8.

CALCINER STACK GAS CONTACT COOLING WATER

The BPT wastewater discharge rate selected for calciner stack  gas
contact cooling water  is 4,150 1/kkg  (1,096  gal/kkg) of mercury
condensed.  This discharge rate is equivalent to the discharge
rate of the only plant reporting this  waste  stream.  Table  V-9
presents the reported water use and discharge rates for this
waste stream.

CONDENSER BLOWDOWN

The BPT wastewater discharge for condenser blowdown is  13,800
1/kkg (3,646 gal/kkg) of mercury condensed.  Water  use  and  dis-
charge rates for this waste stream are provided  in  Table V-10.
The condenser blowdown normalized discharge  rate is based upon
the only value reported for this waste stream (plant 1068).

MERCURY CLEANING BATH WATER

The BPT wastewater discharge rate for  mercury cleaning  bath water
is 1,400 1/kkg (370 gal/kkg) of mercury condensed.  This normal-
ized flow is equivalent to the only reported water  discharge rate
for this waste stream.  Table V-11 provides  the  reported water
use and discharge flows for this subdivision.

REGULATED POLLUTANT PARAMETERS

The raw wastewater concentrations from individual operations and
the subcategory as a whole were examined to  select  certain  pollu-
tant parameters for limitation.  This  examination and evaluation
is presented in Sections VI and X.  Eight pollutants or pollutant
                               104

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parameters are selected for limitation under  BPT and  are  listed
below:
115.
122.
123.
126.
128.
arsenic
lead
mercury
silver
zinc
           oil and grease
           total suspended solids  (TSS)
           pH

EFFLUENT LIMITATIONS

The concentrations achievable by application of  the proposed  BPT
treatment are explained in Section VII of the General  Development
Document and summarized there in Table VI1-19.   The achievable
treatment concentrations (both one-day maximum and monthly aver-
age values) are multiplied by the BPT normalized discharge flows
summarized in Table IX-1 to calculate the mass of pollutants
allowed to be discharged per mass of product.  The results of
these calculations in milligrams of pollutant per troy ounce  or
kilogram of product represent the BPT effluent limitations and
are presented in Table IX-2 for each individual waste  stream.
                              105

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                        Table  IX-2

     BPT MASS LIMITATIONS  FOR THE PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
 (a)  Smelter Wet Air  Pollution  Control

   Pollutant or        Maximum  for        Maximum for
 Pollutant Property	Any One  Day	Monthly Average

        mg/troy ounce of gold and silver  smelted

 Arsenic                  27.590            12.280
 Lead                      5.544             2.640
 Mercury                   3.300             1.320
 Silver                    5.412             2.244
 Zinc                     19.270             8.052
 Oil and grease          264.000           158.400
 Total suspended         541.200           257.400
  solids
 pH                     Within the range of 7.5 to 10.0
                                 at.all times
(b)  Silver Chloride Reduction  Spent  Solution

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average

      mg/troy ounce of silver reduced  in solution

Arsenic                   0.836             0.372
Lead                      0.168             0.080
Mercury                   0. 100             0.040
Silver                    0.164             0.068
Zinc                      0.584             0.244
Oil and grease            8.000             4.800
Total suspended          16.400             7.800
  solids
pH                     Within the range of  7.5 to 10.0
                                 at all times
                              107

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                 Table IX-2  (Continued)

     BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                 413.800           184.100
Lead                     83.160            39.600
Mercury                  49.500            19.800
Silver                   81.180            33.660
Zinc                    289.100           120.800
Oil and grease        3,960.000         2,376.000
Total suspended       8,118.000         3,861.000
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
(d)  Electrolyte Preparation Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

    mg/troy ounce of silver in electrolyte produced

Arsenic                   0.105             0.047
Lead                      0.021             0.010
Mercury                   0.013             0.005
Silver                    0.021             0.009
Zinc                      0.073             0.031
Oil and grease            1.000             0.600
Total suspended           2.050             0.975
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               108

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                 Table  IX-2  (Continued)

     BPT MASS LIMITATIONS  FOR  THE  PRIMARY PRECIOUS
             METALS AND MERCURY  SUBCATEGORY
 (e)  Silver Crystals Wash  Water
   Pollutant or
Pollutant Property
Maximum for
Any One Day
               Maximum for
             Monthly Average
        ing/troy ounce of silver  crystals washed
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
  solids
PH
   0.606
   0.122
   0.073
   0.119
   0.423
   5.800
  11.890
                  0.270
                  0.058
                  0.029
                  0.049
                  0.177
                  3.480
                  5.655
Within the range of  7.5 to  10.0
          at all times
(f)  Gold Slimes Acid Wash and Water Rinse
   Pollutant or
Pollutant Property
Maximum for
Any One Day
               Maximum for
             Monthly Average
          mg/troy ounce of gold slimes washed
Arsenic
Lead
Mercury
Silver
Zinc
Oil and grease
Total suspended
  solids
PH
   8.360
     680
     000
     640
     840
  80.000
 164.000
1.
1.
1.
5.
 3.720
 0.800
 0.400
 0.680
 2.440
48.000
78.000
Within the range of 7.5 to 10.0
          at all times
                              109

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                 Table IX-2 (Continued)

     BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
(g)  Calciner Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                 388.800           173.000
Lead                     78.120            37.200
Mercury                  46.500            18.600
Silver                   76.260            31.620
Zinc                    271.600           113.500
Oil and grease        3,720.000         2,232.000
Total suspended       7,626.000         3,627.000
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
(h)  Calcine Quench Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  36.790            16.370
Lead                      7.392             3.520
Mercury                   4.400             1.760
Silver                    7.216             2.992
Zinc                     25.700            10.740
Oil and grease          352.000           211.200
Total suspended         721.600           343.200
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               110

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                 Table  IX-2  (Continued)

     BPT MASS LIMITATIONS  FOR  THE  PRIMARY PRECIOUS
             METALS AND MERCURY  SUBCATEGORY
 (i)  Calciner Stack Gas  Contact  Cooling Water

   Pollutant or        Maximum for        Maximum  for
 Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million  Ibs) of  mercury condensed

 Arsenic                   8.674              3.860
 Lead                      1.743              0.830
 Mercury                   1.038              0.415
 Silver                    1.702              0.706
 Zinc                      6.059              2.532
 Oil and grease            83.000             49.800
 Total suspended          170.200             80.930
  solids
 pH                     Within the range of  7.5 to 10.0
                                 at  all times
(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

      mg/kg  (Ib/million Ibs) of mercury  condensed

Arsenic                  28.840             12.830
Lead                      5.796              2.760
Mercury                   3.450              1.380
Silver                    5.658              2.346
Zinc                     20.150              8.418
Oil and grease          276.000            165.600
Total suspended         565.800            269.100
  solids
pH                     Within the range  of  7. 5 to 10.0
                                 at all  times
                              111

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                 Table IX-2  (Continued)

     BPT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
(k)  Mercury Cleaning Bach Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   2.926              1.302
Lead                      0.588              0.280
Mercury                   0.350              0.140
Silver                    0.574              0.238
Zinc                      2.044              0.854
Oil and grease           28.000             16.800
Total suspended          57.400             27.300
  solids
pH                     Within the range of  7.5 to  10.0
                                 at all times
                              112

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                        113

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          PRIMARY  PRECIOUS  METALS  AND  MERCURY SUBCATEGORY

                            SECTION X

        BEST AVAILABLE  TECHNOLOGY ECONOMICALLY ACHIEVABLE


The effluent limitations which must be  achieved  by July 1,  1984
are based  on the  best control and treatment  technology used by a
specific  point source within the  industrial  category or subcate-
gory, or  by another  category where it is  readily transferable.
Emphasis  is placed on additional  treatment techniques applied  at
the end of the treatment systems  currently used,  as well as
reduction  of the  amount of water  used and discharged, process
control,  and treatment  technology optimization.

The factors considered  in  assessing best  available technology
economically achievable (BAT) include the age  of  equipment  and
facilities involved, the process  used,  process changes, nonwater
quality environmental impacts (including  energy  requirements),
and the costs of  application of such  technology  (Section 304(b)
(2)(B) of the Clean Water  Act).   At a minimum, BAT represents  the
best available technology  economically achievable at plants of
various ages, sizes, processes, or other  characteristics.   Where
the Agency has found the existing performance  to be uniformly
inadequate, BAT may be  transferred from a different subcategory
or category.  BAT may include feasible  process changes or inter-
nal controls, even when not in common practice.

The statutory assessment of BAT considers costs,  but does not
require a balancing  of  costs against  pollutant removals (see
Weyerhaeuser v. Costle, 11 ERG 2149 (D.C. Cir.  1978)).   However,
in assessing the  proposed  BAT, the Agency has  given substantial
weight to the economic achievability  of the  technology.

TECHNICAL APPROACH TO BAT

The Agency reviewed a wide range  of technology options  and
evaluated the available possibilities  to  ensure  that the most
effective and beneficial technologies were used  as  the  basis of
BAT.   To accomplish this,  the Agency  elected to  examine three
technology options which could be  applied to the  primary precious
metals and mercury subcategory as  alternatives for the basis of
BAT effluent limitations.

For the development of BAT effluent limitations,  mass loadings
were calculated for each waslewater source or  subdivision  in the
subcategory using the same technical  approach  as  described  in
Section IX for BPT limitations development.  The  differences in
the mass loadings for BPT and BAT  are due to increased  treatment
                                115

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effectiveness achievable with  the more  sophisticated  BAT treat-
ment technology and reductions  in the effluent  flows  allocated  to
various waste streams.

In summary, the treatment technologies  considered  for the primary
precious metals and mercury subcategory are:

Option A (Figure X-1):

     •  Oil skimming preliminary treatment for  streams  containing
        oil and grease at treatable  concentrations
     •  Chemical precipitation  and sedimentation

Option B (Figure X-2) is based  on

     •  In-process flow reduction of wet air pollution  control
        water
     •  Oil skimming preliminary treatment for  streams  containing
        oil and grease at treatable  concentrations
     •  Chemical precipitation  and sedimentation

Option C (Figure X-3) is based  on

     •  In-process flow reduction of wet air pollution  control
        water
     •  Oil skimming preliminary treatment for  streams  containing
        oil and grease at treatable  concentrations
     •  Chemical precipitation  and sedimentation
     •  Multimedia filtration

The three options examined for  BAT are  discussed in greater
detail below.  The first option considered is the  same  as the BPT
treatment technology which was  presented in the previous section.

OPTION A

Option A for the primary precious metals and mercury  subcategory
is equivalent to the control and treatment technologies  which
were analyzed for BPT in Section IX.  The BPT end-of-pipe treat-
ment scheme includes chemical precipitation and sedimentation
(lime and settle) technology, with oil  skimming preliminary
treatment of wastewaters containing  treatable concentrations of
oil and grease (see Figure X-1).  The discharge rates for Option
A are equal to the discharge rates allocated to each  stream as a
BPT discharge flow.

OPTION B

Option B for the primary precious metals and mercury  subcategory
achieves lower pollutant discharge by building upon the Option A
                               116

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 (oil skimming preliminary  treatment,  chemical precipitation and
 sedimentation) treatment technology.   Flow reduction measures are
 added to  the Option A treatment  scheme (see Figure X-2).   These
 flow reduction measures, including  in-process changes,  result in
 the concentration of  pollutants  in  some wastewater streams.  As
 explained in Section  VII of  the  General Development Document,
 treatment of a more concentrated effluent  allows  achievement of a
 greater net pollutant removal  and introduces the  possible eco-
 nomic benefits associated  with treating a  lower volume  of
 wastewater.

 Option B  flow reduction measures are  reflected in the BAT waste -
 water discharge rates.  Flow reduction has been included  in
 determining the BAT discharge  rates for smelter wet air pollution
 control,  electrolytic cells  wet  air pollution control,  and cal-
 ciner wet air pollution control.  Based on available data, the
 Agency did not feel that further flow reduction over BPT  would be
 feasible  for the remaining eight waste streams in the primary
 precious metals and mercury  subcategory.   These waste streams
 are:

     1.   Silver.chloride reduction spent solution,
     2.   Electrolyte  preparation wet  air pollution control,
     3.   Silver crystal wash water,
     4.   Gold slimes  acid  wash and water rinse,
     5.  Calcine quench water,
     6.  Calciner stack gas  contact cooling water,
     7.  Condenser blowdown, and
     8.  Mercury cleaning  bath water.

 Flow reduction measures used in  Option B to reduce process
 wastewater generation or discharge rates include  the following:

 Recycle of Water Used in Wet Air Pollution Control

 There are four wastewater  sources associated with wet air pollu-
 tion control which are regulated under the primary precious
 metals and mercury subcategory:

     1.  Smelter wet  air pollution control,
     2.  Electrolytic  cells  wet  air pollution control,
     3.  Electrolyte  preparation wet  air pollution  control,  and
     4.  Calciner wet  air  pollution control.

Table X-1 presents the number  of plants reporting wastewater from
 the wet air pollution  control  sources  listed above,  the number of
plants practicing recycle,  and the range of recycle values being
 listed.  Recycle of smelter  scrubber  water,  electrolytic  cell
 scrubber water,  and calciner scrubber  water are required  for BAT.
 Recycle of electrolyte preparation wet air pollution control is
                              117

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not required for BAT because  the  BPT discharge  flow is  close  to
the minimum possible water discharge from a  scrubber. The  recycle
rate used for all three other sources  is based  on  90 percent
recycle of the average water use  reported by all the plants with
each waste stream, as will be shown later.

OPTION C

Option C for the primary precious metals and mercury subcategory
consists of all control and treatment  requirements  of Option  B
(in-process flow reduction, oil skimming preliminary treatment,
chemical precipitation and sedimentation) plus  multimedia  filtra-
tion technology added at the end  of the Option  B treatment scheme
(see Figure X-3).  Multimedia filtration is  used to  remove sus-
pended solids, including precipitates  of toxic  metals,  beyond the
concentration attainable by gravity sedimentation.   The  filter
suggested is of the gravity, mixed media type,  although  other
filters, such as rapid sand filters or pressure filters, would
perform satisfactorily.

INDUSTRY COST AND ENVIRONMENTAL BENEFITS

As one means of evaluating each technology option,  EPA developed
estimates of the pollutant removal benefits  and the  compliance
costs associated with each option.  The methodologies are
described below.

POLLUTANT REMOVAL ESTIMATES

A complete description of the methodology used  to  calculate the
estimated pollutant removal, or benefit, achieved  by the applica-
tion of the various treatment options  is presented  in Section X
of the General Development Document.   In short, sampling data
collected during the field sampling program  were used to charac-
terize the major waste streams considered for regulation.  At
each sampled facility, the sampling data was production normal-
ized for each unit operation  (i.e., mass of  pollutant generated
per mass of product manufactured).  This value, referred to as
the raw waste, was used to estimate the mass of toxic pollutants
generated within the primary precious metals and mercury subcate-
gory.  The pollutant removal estimates were  calculated  for each
plant by first estimating the total mass of  each pollutant in the
untreated wastewater.  This was calculated by first  multiplying
the raw waste values by the corresponding production value for
that stream and then summing these values for each  pollutant  for
every stream generated by the plant.

Next, the volume of wastewater discharged after the  application
of each treatment option was estimated for each operation  at  each
plant by comparing the actual discharge to the  regulatory  flow.
                               118

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The  smaller of  the  two  values  was  selected and summed with the
other plant flows.   The mass of  pollutant  discharged was then
estimated by multiplying  the achievable  concentration values
attainable with the  option  (mg/1)  by  the estimated volume of
process wastewater  discharged  by the  subcategory.   The mass of
pollutant removed is  the  difference between the estimated mass of
pollutant generated  within  the subcategory and the mass of
pollutant discharged  after  application of  the  treatment option.
The  pollutant removal estimates  for direct dischargers in the
primary precious metals and mercury subcategory are presented in
Table X-2.

COMPLIANCE COSTS

In estimating subcategory-wide compliance  costs,  the first step
was  to develop a cost estimation model,  relating  the total costs
associated with installation and operation of  wastewater treat-
ment technologies to  plant  process wastewater  discharge.  EPA
applied the model to  each plant.   The plant's  investment and
operating costs are  determined by  what treatment  it has in place
and  by its individual process  wastewater discharge flow.  As dis-
cussed above, this flow is  either  the actual or the BAT regula-
tory flow, whichever  is lesser.  The  final step was to annualize
the  capital costs, and  to sum  the  annualized capital costs,  and
the  operating and maintenance  costs for  each plant, yielding the
cost of compliance for  the  subcategory (see Table  X-3).   These
costs were used in assessing economic achievability.

BAT OPTION SELECTION

Our proposed BAT limitations for this subcategory  are based on
preliminary treatment consisting of oil  skimming and end-of-pipe
treatment consisting  of chemical precipitation and sedimentation
(BPT technology),  and filtration  (Option C).

The pollutants specifically limited under  BAT  are  arsenic,  lead,
mercury, silver, and  zinc.  The  toxic pollutants cadmium,  chro-
mium, copper, nickel, and thallium were  also considered for regu-
lation because they were  found at  treatable concentrations  in the
raw wastewaters from  this subcategory.   These  pollutants were not
selected for specific regulation because they  will be effectively
controlled when the regulated  toxic metals  are treated to the
concentrations achievable by the model BAT technology.

Implementation of the proposed BAT limitations would remove annu-
ally an estimated 914.5 kg of  toxic metals.  Estimated capital
cost for achieving proposed BAT  is $30,000 and annualized cost is
$10,000.
                              119

-------
Oil skimming is demonstrated  in the nonferrous metals  manufactur-
ing category.  Although no primary precious metals  and mercury
plants have oil skimming in place, it  is necessary  to  reduce  oil
and grease concentrations in  the discharge from  this subcategory.

WASTEWATER DISCHARGE RATES

A BAT discharge rate was calculated for each subdivision  based
upon the flows of the existing plants, as determined from analy-
sis of the data collection portfolios.  The discharge  rate  is
used with the achievable treatment concentrations to determine
BAT effluent limitations.  Since the discharge rate may be  dif-
ferent for each wastewater source, separate production normalized
discharge rates for each of the 11 wastewater sources  were  deter-
mined and are summarized in Table X-4.  The discharge  rates are
normalized on a production basis by relating the amount of  waste-
water generated to the mass of the intermediate  product which is
produced by the process associated with the waste stream  in ques-
tion.  These production normalizing parameters (PNP) are  also
listed in Table X-4.

As discussed previously, the  BAT wastewater discharge  rate  equals
the BPT wastewater discharge  rate for  eight of the  11  waste
streams in the primary precious metals and mercury  subcategory.
Based on the available data,  the Agency determined  that further
flow reduction would not be feasible for these eight wastewater
sources.  Wastewater streams  for which BAT discharge rates  differ
from BPT are discussed below.

SMELTER WET AIR POLLUTION CONTROL

The BAT wastewater discharge  rate for  smelter wet air  pollution
control is 1.3 liters per troy ounce of gold and silver smelted.
This rate is based on 90 percent recycle of the  average water use
rate reported for this waste  stream, as shown in Table V-1.   This
rate corresponds to 90 percent recycle of the BPT discharge rate.
As shown in Table VI-1, recycle is demonstrated  for this  stream.

ELECTROLYTIC CELLS WET AIR POLLUTION CONTROL

The BAT wastewater discharge  rate for  electrolytic  cells  wet  air
pollution control is 19.8 liters per troy ounce  of  gold refined
electrolytically.  This rate  is based  on 90 percent recycle of
the water use rate reported by the one plant with this waste
stream, as shown in Table V-3.  The Agency believes this  waste
stream can be operated with 90 percent recycle,  even though
recycle is noL demonstrated for it.
                               120

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CALGINER WET AIR  POLLUTION  CONTROL

The BAT wastewater  discharge  rate  for  calciner wet air pollution
control is 22,000 liters per  metric  ton  of mercury condensed.
This rate is based  on  90 percent recycle of the water use rate
reported by the only plant  with this waste stream.   As shown in
Table V-7, the plant reported a flow of  186,000 1/kk.g, which
represents a 16 percent recycle rate.  The BAT rate was
determined by the following formula:

     (186,000 1/kkg) (1.00  -  0.90) = 22,000 1/kkg
                     (1.00  -  0.16)

Although 90 percent recycle is not demonstrated for this  waste
stream, the Agency  believes it is  achievable.

REGULATED POLLUTANT PARAMETERS

In implementing the terms of  the Consent Agreement in NRDC v.
Train,  Op. Cit.,  and 33 U. S.C. §1314(b) (2) (A and B) (11T767,  the
Agency placed particular emphasis  on the toxic pollutants.  The
raw wastewater concentrations  from individual  operations  and the
subcategory as a  whole were examined to  select certain pollutant
parameters for consideration  for limitation.   This  examination
and evaluation, presented in  Section VI,  concluded that 10 pollu-
tants are present in primary  precious metals  and mercury  waste-
waters at concentrations than  can  be effectively reduced  by
identified treatment technologies  (refer to Section VI).

The high cost associated with analysis for toxic metal pollutants
has prompted EPA  to develop an alternative method for regulating
and monitoring toxic pollutant discharges  from the  nonferrous
metals manufacturing category.  Rather than developing specific
effluent mass limitations and standards  for each of the toxic
metals found in treatable concentrations in the raw wastewaters
from a given subcategory, the Agency is  proposing effluent mass
limitations only  for those  pollutants generated in  the greatest
quantities as shown by the  pollutant removal  analysis.   The
pollutants selected for specific limitation are listed below:

     115.   arsenic
     122.   lead
     123.   mercury
     126.   silver
     128.   zinc

By establishing limitations and standards  for  certain toxic  metal
pollutants,  dischargers will attain the  same degree of control
over toxic metal pollutants as they would  have been required to
achieve had all the toxic metal pollutants  been directly  limited.
                              121

-------
This approach is technically justified since  the  treatable  con-
centrations used for chemical precipitation and sedimentation
technology are based on optimized treatment for concomitant
multiple metals removal.  Thus, even though metals have  somewhat
different theoretical solubilities, they will  be  removed at very
nearly the same rate in a chemical precipitation  and sedimenta-
tion treatment system operated for multiple metals removal.
Filtration as part of the technology basis is  likewise justified
because this technology removes metals non-preferentially.

The toxic metal pollutants selected for specific  limitation in
the primary precious metals and mercury subcategory to control
the discharges of toxic metal pollutants are  arsenic, lead,
mercury, silver, and zinc.

The following toxic pollutants are excluded from  limitation on
the basis that they are effectively controlled by the limitations
developed for arsenic, lead, mercury, silver,  and zinc:

     118.  cadmium
     119.  chromium
     120.  copper
     124.  nickel
     127.  thallium

EFFLUENT LIMITATIONS

The treatable concentrations, achievable by application  of  the
BAT technology (Option C), are summarized in  Table VII-19 of the
General Development Document.  These treatable concentrations
(both one-day maximum and monthly average) are multiplied by the
BAT normalized discharge flows summarized in  Table X-4 to calcu-
late the mass of pollutants allowed to be discharged per mass of
product.  The results of these calculations in milligrams of
pollutant per troy ounce or kilogram of product represent the BAT
effluent limitations for the primary precious metals and mercury
subcategory.  BAT effluent limitations based  on Option C (oil
skimming, chemical precipitation, sedimentation,  in-process  flow
reduction, and multimedia filtration) are presented in Table X-5.
                               122

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                            Table X-1

           CURRENT RECYCLE PRACTICES WITHIN THE PRIMARY
             PRECIOUS METALS AND MERCURY SUBCATEGORY
Smelter wet air pollution
  control

Electrolytic cells wet
  air pollution control

Electrolyte preparation
  wet air pollution
  control

Calciner wet air pollution
  control
 Number of
Plants With
Wastewater

     3


     1


     1
                                            Number
                                          of Plants
                                          Practicing
                                           Recycle
0
0
           Range
         of Recycle
         Values (%)

           76-100
0
0
                               16
                               123

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                   Table X-3

COST OF COMPLIANCE FOR DIRECT DISCHARGERS  IN THE
PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY
             Total Required
              Capital Cost
  Option     (1982 Dollars)

    A            27,500

    B            27,500

    C            30,000
    Total
 Annual Cost
(1982 Dollars)

     9,000

     9,000

    10,000
                       125

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-------
                        Table  X-5

     BAT MASS LIMITATIONS  FOR THE  PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
 (a)  Smelter Wet Air Pollution  Control

   Pollutant or        Maximum  for        Maximum  for
 Pollutant Property	Any One  Day	Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of gold and
1.807
0.364
0.195
0.377
1.326
silver smelted
0.806
0.169
0.078
0.156
0.546
 (b)  Silver Chloride Reduction  Spent  Solution

   Pollutant or        Maximum  for       Maximum  for
Pollutant Property	Any One  Day	Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver reduced
0.556
0.112
0.060
0.116
0.408
in solution
0.248
0.052
0.024
0.048
0.168
(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                  27.520             12.280
Lead                      5. 544              2.574
Mercury                   2.970              1.188
Silver                    5.742              2.376
Zinc                     20.200              8.316
                               127

-------
                 Table X-5  (Continued)

     BAT MASS LIMITATIONS FOR THE  PRIMARY  PRECIOUS
             METALS AND MERCURY SUBCATEGORY
(d)  Electrolyte Preparation Wet Air Pollution  Control

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly  Average

    mg/troy ounce of silver in electrolyte produced

Arsenic                   0.070              0.031
Lead                      0.014              0.007
Mercury                   0.008              0.003
Silver                    0.015              0.006
Zinc                      0.051              0.021
(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver crystals washed

Arsenic                   0.403              0.180
Lead                      0.081         '     0.038
Mercury                   0.044              0.017
Silver                    0.084              0.035
Zinc                      0.296              0.122
(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

          mg/troy ounce of gold slimes washed

Arsenic                   5.560             "2.480
Lead                      1.120              0.520
Mercury                   0.600              0.240
Silver                    1.160              0.480
Zinc                      4.080              1.680
                               128

-------
                 Table  X-5  (Continued)

     BAT MASS LIMITATIONS FOR  THE  PRIMARY PRECIOUS
             METALS AND MERCURY  SUBCATEGORY
 (g)  Calciner Wet Air Pollution  Control

   Pollutant or        Maximum for       Maximum  for
 Pollutant Property	Any One Day	Monthly Average

      rog/kg (Ib/million  Ibs) of  mercury  condensed

 Arsenic                   30.580             13.640
 Lead                      6. 160              2.860
 Mercury                   3.300              1.320
 Silver                    6.380              2.640
 Zinc                      22.440              9.240
 (h)  Calcine Quench Water

   Pollutant or        Maximum for       Maximum  for
 Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury  condensed

 Arsenic                  24.470             10.910
 Lead                      4.928              2.288
 Mercury                   2.640              1.056
 Silver                    5.104              2.112
 Zinc                     17.950              7.392
(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   5.769             2.573
Lead                      1. 162             0. 540
Mercury                   0.623             0.249
Silver                    1.204             0.498
Zinc                      4.233             1.743
                              129

-------
                 Table X-5 (Continued)

     BAT MASS LIMITATIONS FOR THE PRIMARY PRECIOUS
             METALS AND MERCURY SUBCATEGORY
(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average
mg/kg
Arsenic
Lead
Mercury
Silver
Zinc
(Ib/million

Ibs) of mercury
19.180
3.864
2.070
4.002
14.080
condensed
8.556
1.794
0.828
1.656
5.796
(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406             0.168
Zinc                      1.428             0.588
                              130

-------
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134

-------
         PRIMARY  PRECIOUS METALS  AND MERCURY SUBCATEGORY

                             SECTION  XI

                  NEW  SOURCE  PERFORMANCE  STANDARDS
The basis for new source performance  standards  (NSPS)  under
Section 306 of the Act  is  the  best  available  demonstrated tech-
nology (BDT).  New plants  have  the  opportunity  to  design  the  best
and most efficient production  processes  and wastewater treatment
technologies without facing the added  costs and restrictions
encountered in retrofitting an  existing  plant.   Therefore,
Congress directed EPA to consider the  best demonstrated process
changes, in-plant controls, and end-of-pipe treatment  techno-
logies which reduce pollution  to the maximum  extent  feasible.

This section describes  the technologies  for treatment  of  waste-
water from new sources  and presents mass  discharge standards  for
regulatory pollutants for  NSPS  in the  primary precious metals and
mercury subcategory, based on  the selected treatment technology.

TECHNICAL APPROACH TO NSPS

New source performance  standards are  equivalent to the best
available technology (BAT) selected for  currently  existing
primary precious metals and mercury plants.   This  result  is a
consequence of careful  review by the Agency of  a wide  range of
technical options for new  source treatment systems which  is
discussed in Section XI of the  General Development Document.
This review of the primary precious metals and  mercury subcate-
gory found no new, economically feasible, demonstrated technolo-
gies which could be considered  an improvement over those  chosen
for consideration for BAT.  Additionally, there was nothing found
to indicate that the wastewater flows  and characteristics of  new
plants would not be similar to  those from existing plants,  since
the processes used by new  sources are not expected to  differ  from
those used at existing  sources.  Consequently,  BAT production
normalized discharge rates, which are based on  the best existing
practices of the subcategory,  can also be applied  to new  sources.
These rates are presented  in Table XI-1.

Treatment technologies  considered for  the NSPS  options are
identical to the treatment technologies considered for the  BAT
options.   These options are:
OPTION A
        Preliminary treatment with oil skimming  (where required)
        Chemical precipitation and sedimentation
                               135

-------
OPTION B
     •  Preliminary treatment with oil skimming  (where  required)
     •  Chemical precipitation and sedimentation
     •  In-process flow reduction of smelter,  electrolytic  cells,
        and calciner scrubber liquor

OPTION C

     •  Preliminary treatment with oil skimming  (where  required)
     •  Chemical precipitation and sedimentation
     •  In-process flow reduction of smelter,  electrolytic  cells,
        and calciner scrubber liquor
     •  Multimedia filtration

NSPS OPTION SELECTION

We are proposing that NSPS be equal to BAT.  Our review of  the
subcategory indicates that no new demonstrated technologies  that
improve on BAT technology exist.  We do not believe that new
plants could achieve any flow reduction beyond the allowances
proposed for BAT.  Because NSPS is equal to BAT we believe  that
the proposed NSPS will not have a detrimental  impact on the  entry
of new plants into this subcategory.

REGULATED POLLUTANT PARAMETERS

The Agency has no reason to believe that the pollutants that will
be found in treatable concentrations in processes within new
sources will be any different than with existing sources.
Accordingly, pollutants and pollutant parameters selected for
limitation under NSPS, in accordance with the  rationale of
Sections VI and X, are identical to those selected for  BAT.  The
conventional pollutant parameters oil and grease, TSS,  and  pH are
also selected for limitation.

NEW SOURCE PERFORMANCE STANDARDS

The NSPS discharge flows for each wastewater source are the  same
as the discharge rates for BAT and are shown in Table XI-1.  The
mass of pollutant allowed to be discharged per mass of  product  is
calculated by multiplying the appropriate treatable concentration
(mg/1) by the production normalized wastewater discharge flows
(1/T.O. or 1/kkg).  The treatable concentrations are listed  in
Table VII-19 of the General Development Document.  The  results  of
these calculations are the production-based new source  perfor-
mance standards.  These standards are presented in Tables XI-2.
                               136

-------
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                       Table XI-2

    NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      S UBCATEGORY
(a)  Smelter Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of gold and silver smelted

Arsenic                   1.807              0.806
Lead                      0.364              0.169
Mercury                   0.195              0.078
Silver                    0.377              0.156
Zinc                      1.326              0.546
Oil and grease           13.000             13.000
Total suspended          19.500             15.600
  solids
pH                     Within the range of  7.5 to  1 0. 0
                                 at all times
(b)  Silver Chloride Reduction Spent Solution

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/troy ounce of silver reduced in solution

Arsenic                   0.556             0.248
Lead                      0.112             0.052
Mercury                   0.060             0.024
Silver                    0.116             0.048
Zinc                      0.408             0.168
Oil and grease            4.000             4.000
Total suspended           6.000             4.800
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               138

-------
                 Table XI-2  (Continued)

    NSPS FOR THE PRIMARY  PRECIOUS METALS AND  MERCURY
                      SUBCATEGORY
 (c)  Electrolytic Cells Wet Air  Pollution  Control

   Pollutant or        Maximum for       Maximum for
 Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

 Arsenic                  27.520   .          12.280
 Lead                      5.544              2.574
 Mercury                   2.970              1.188
 Silver                    5.742              2.376
 Zinc                     20.200              8.316
 Oil and grease          198.000            198.000
 Total suspended         297.000            237.600
  solids
 pH                     Within the range of  7.5 to  10.0
                                  at all times
(d)  Electrolyte Preparation Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

    mg/troy ounce of silver in electrolyte produced

Arsenic                   0.070              0.031
Lead                      0.014              0.007
Mercury                   0.008              0.003
Silver                    0.015              0.006
Zinc                      0.051              0.021
Oil and grease            0.500              0.500
Total suspended           0.750              0.600
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
                               139

-------
                 Table XI-2  (Continued)

    NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver crystals washed

Arsenic                   0.403             0.180
Lead                      0.081             0.038
Mercury                   0.044             0.017
Silver                    0.084             0.035
Zinc                      0.296             0.122
Oil and grease            2.900             2.900
Total suspended           4.350             3.480
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

          mg/troy ounce of gold slimes washed

Arsenic                   5.560             2.480
Lead                      1.120             0.520
Mercury                   0.600             0.240
Silver                    1.160             0.480
Zinc                      4.080             1.680
Oil and grease           40.000            40.000
Total suspended          60.000            48.000
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               140

-------
                 Table XI-2  (Continued)

    NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
 (g)  Calciner Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
 Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

 Arsenic                  30.580             13.640
 Lead                      6.160             2.860
 Mercury                   3.300             1.320
 Silver                    6.380             2.640
 Zinc                     22.440             9.240
 Oil and grease          220.000            220.000
 Total suspended         330.000            264.000
  solids
 pH •                    Within the range of  7.5 to  10.0
                                 at all times
(h)  Calcine Quench Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

            (Ib/million Ibs) of mercury condensed

Arsenic                  24.470            10.910
Lead                      4.928             2.288
Mercury                   2.640             1.056
Silver                    5.104        .     2.112
Zinc                     17.950             7.392
Oil and grease          176.000           176.000
Total suspended         264.000           211.200
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                              141

-------
                 Table XI-2  (Continued)

    NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      fflg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   5.769              2.573
Lead                      1.162              0.540
Mercury                   0.623              0.249
Silver                    1.204              0.498
Zinc                      4.233              1.743
Oil and grease           41.500            41.500
Total suspended          62.250            49.800
  solids
pH                     Within the range of 7.5 to  10.0
                                 at all times
(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  19.180             8.556
Lead                      3.864             1.794
Mercury                   2.070             0.828
Silver                    4.002             1.656
Zinc                     14.080             5.796
Oil and grease          138.000           138.000
Total suspended         207.000           165.600
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                               142

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                 Table XI-2  (Continued)

    NSPS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406             0.168
Zinc                      1.428             0.588
Oil and grease           14.000            14.000
Total suspended          21.000            16.800
  solids
pH                     Within the range of 7.5 to 10.0
                                 at all times
                              143

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         PRIMARY PRECIOUS METALS AND MERCURY  SUBCATEGORY

                           SECTION  XII

                      PRETREATMENT  STANDARDS
Section 307(b) of the Act requires EPA  to  promulgate  pretreatment
standards for existing sources  (PSES),  which  must  be  achieved
within three years of promulgation.   PSES  are  designed  to  prevent
the discharge of pollutants which pass  through,  interfere  with,
or are otherwise incompatible with the  operation of publicly
owned treatment works (POTW).   The Clean Water Act of 1977
requires pretreatment for pollutants, such as  heavy metals, that
limit POTW  sludge management alternatives.  Section 307(c) of  the
Act requires EPA to promulgate  pretreatment standards  for  new
sources (PSNS) at the same time that  it promulgates NSPS.   New
indirect discharge facilities,  like new direct discharge facili-
ties, have  the opportunity to incorporate  the  best available
demonstrated technologies, including  process  changes,  in-plant
controls, and end-of-pipe treatment technologies,  and  to use
plant site selection to ensure  adequate treatment  system instal-
lation.  Pretreatment standards  are to  be  technology  based,
analogous to the best available  technology for removal  of  toxic
pollutants.

EPA is not proposing pretreatment standards for  existing sources
in this subcategory because no  indirect dischargers exist.  How-
ever, EPA is proposing pretreatment standards  for  new sources
because plants may be constructed in  the future which  may
discharge to a POTW.

This section describes the control and  treatment technologies  for
pretreatment of process wastewaters from new sources  in the
primary precious metals and mercury subcategory.   Pretreatment
standards for regulated pollutants are  presented based  on  the
selected control and treatment  technology.

TECHNICAL APPROACH TO PRETREATMENT

Before proposing pretreatment standards, the Agency examines
whether the pollutants discharged by  the industry  pass  through
the POTW or interfere with the  POTW operation  or its  chosen
sludge disposal practices.  In  determining whether pollutants
pass through a well-operated POTW, achieving secondary  treatment,
the Agency compares the percentage of a pollutant  removed  by POTW
with the percentage removed by  direct dischargers  applying the
best available technology economically  achievable.  A  pollutant
is deemed to pass through the POTW when the average percentage
removed nationwide by well-operated POTW meeting secondary
                                145

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treatment requirements,  is  less  than  the percentage  removed  by
direct dischargers complying with BAT  effluent  limitations
guidelines for that pollutant.   (See  generally, 46 FR  at  9415-16
(January 28, 1981)).

This definition of pass  through  satisfies  two competing objec-
tives set by Congress:   (1) that standards  for  indirect dis-
chargers be equivalent to standards for direct  dischargers while
at the same time, (2) that  the treatment capability  and perfor-
mance of the POTW be recognized  and taken  into  account in regu-
lating the discharge of  pollutants from indirect  dischargers.

The Agency compares percentage removal rather than the mass  or
concentration of pollutants discharged because  the latter would
not take into account the mass of pollutants discharged to the
POTW from non-industrial sources or the dilution  of  the
pollutants in the POTW effluent  to lower concentrations due  to
the addition of large amounts of non-industrial wastewater.

PRETREATMENT STANDARDS FOR NEW SOURCES

Options for pretreatment of wastewaters from new  sources  are
based on increasing the  effectiveness  of end-of-pipe treatment
technologies.  All in-plant changes and applicable end-of-pipe
treatment processes have been discussed previously in Sections X
and XI.  The options for PSNS are the  same  as the BAT and NSPS
options discussed in Sections X  and XI, respectively.

A description of each option is  presented  in Sections X and  XI,
while a more detailed discussion, including pollutants controlled
by each treatment process is presented in Section VII of  the
General Development Document.

Treatment technologies considered for  the PSNS  options are:

OPTION A

     •  Preliminary treatment with oil skimming (where required)
     •  Chemical precipitation and sedimentation

OPTION B

     •  Preliminary treatment with oil skimming (where required)
     •  Chemical precipitation and sedimentation
     •  In-process flow  reduction of  smelter, electrolytic cells,
        and calciner scrubber liquor
                                146

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OPTION C

     •  Preliminary  treatment  with  oil  skimming (where required)
     •  Chemical precipitation and  sedimentation
     •  In-process flow  reduction of  smelter,  electrolytic cells,
        and calciner  scrubber  liquor
     •  Multimedia filtration

PSNS OPTION SELECTION

We are proposing PSNS equal  to NSPS and BAT for this  subcategory.
It is necessary to propose PSNS to  prevent  pass-through of
arsenic, lead, mercury,  silver,  and zinc.   These  toxic pollutants
are removed by a well-operated POTW at  an average  of  62 percent,
while BAT technology  removes approximately  93  percent.

The technology basis  for  PSNS  thus  is chemical precipitation and
sedimentation, oil skimming, wastewater flow reduction and
filtration (Option C) .   Flow reduction  is based on 90 percent
recycle of scrubber  effluent that is  the flow  basis of BAT.

We believe that the proposed PSNS are achievable,  and that they
are not a barrier to  entry of  new plants into  this subcategory.

REGULATED POLLUTANT PARAMETERS

Pollutants selected for  limitation, in  accordance  with the
rationale of Sections VI  and X,  are identical  to  those selected
for limitation for BAT.   It  is necessary to propose PSNS to
prevent the pass-through  of arsenic,  lead,  mercury, silver,  and
zinc.

PRETREATMENT STANDARDS

Pretreatment standards are based on the  treatable  concentrations
from the selected treatment technology,  (Option C), and the
discharge rates determined in  Sections  X and XI for BAT and  NSPS,
respectively.   These  discharge rates are presented in Table
XII-1.   A mass of pollutant per mass of  product (mg/troy ounce  or
mg/kilogram) allocation is given for each subdivision within the
subcategory.  This pollutant allocation  is  based on the product
of the treatable concentration from the  proposed treatment (mg/1)
and the production normalized  wastewater discharge rate (1/troy
ounce or 1/kkg).  The achievable treatment  concentrations  for BAT
are identical to those for PSNS.  These  concentrations are listed
in Tables VII-19 of the General  Development Document.   PSNS  are
presented in Table XII-2.
                              147

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                      Table XII-2

    PSNS FOR THE PRIMARY  PRECIOUS METALS  AND  MERCURY
                      SUBCATEGORY
 (a)  Smelter Wet Air Pollution  Control

   Pollutant or        Maximum  for       Maximum  for
 Pollutant Property	Any One  Day	Monthly Average

        mg/troy ounce of gold and silver smelted

 Arsenic                   1.807              0.806
 Lead                      0.364             0.169
 Mercury                   0.195              0.078
 Silver                    0.377              0.156
 Zinc                      1.326              0.546
(b)  Silver Chloride Reduction Spent Solution

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average
mg/troy ounce
Arsenic
Lead
Mercury
Silver
Zinc
of silver reduced
0.556
0.112
0.060
0.116
0.408
in solution
0.248
0.052
0.024
0.048
0.168
(c)  Electrolytic Cells Wet Air Pollution Control

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

     mg/troy ounce of gold refined electrolytically

Arsenic                  27.520            12.280
Lead                      5.544             2.574
Mercury                   2.970             1.188
Silver                    5.742             2.376
Zinc                     20.200             8.316
                               149

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                Table XII-2  (Continued)

    PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
(d)  Electrolyte Preparation Wet Air  Pollution  Control

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly  Average

    mg/troy ounce of silver in electrolyte produced

Arsenic                   0.070              0.031
Lead                      0.014              0.007
Mercury                   0.008              0.003
Silver                    0.015              0.006
Zinc                      0.051              0.021
(e)  Silver Crystals Wash Water

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

        mg/troy ounce of silver crystals washed

Arsenic                   0.403              0.180
Lead                      0.081              0.038
Mercury                   0.044              0.017
Silver                    0.084              0.035
Zinc                      0.296              0.122
(f)  Gold Slimes Acid Wash and Water Rinse

   Pollutant or        Maximum for       Maximum  for
Pollutant Property	Any One Day	Monthly Average

          mg/troy ounce of gold slimes washed

Arsenic                   5.560              2.480
Lead                      1.120              0.520
Mercury                   0.600              0.240
Silver                    1.160              0.480
Zinc                      4.080              1.680
                               150

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                Table XII-2  (Continued)

    PSNS FOR THE  PRIMARY  PRECIOUS  METALS  AND MERCURY
                      SUBCATEGORY
 (g)  Calciner Wet Air Pollution  Control

   Pollutant or        Maximum for        Maximum  for
 Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of  mercury  condensed

 Arsenic                   30.580             13.640
 Lead                      6.160              2.860
 Mercury                   3.300              1.320
 Silver                    6.380              2.640
 Zinc                      22.440              9.240
 (h)  Calcine Quench Water

   Pollutant or        Maximum for       Maximum  for
 Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

 Arsenic                  24.470             10.910
 Lead                      4.928              2.288
 Mercury                   2.640              1.056
 Silver                    5.104              2.112
 Zinc                     17.950              7.392
(i)  Calciner Stack Gas Contact Cooling Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg'(Ib/million Ibs) of mercury condensed

Arsenic                   5.769             2.573
Lead                      1. 162             0.540
Mercury                   0.623             0.249
Silver                    1.204             0.498
Zinc                      4.233             1.743
                              151

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                Table XII-2 (Continued)

    PSNS FOR THE PRIMARY PRECIOUS METALS AND MERCURY
                      SUBCATEGORY
(j)  Condenser Slowdown

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                  19.180             8.556
Lead                      3.864             1.794
Mercury                   2.070             0.828
Silver                    4.002             1.656
Zinc                     14.080             5.796
(k)  Mercury Cleaning Bath Water

   Pollutant or        Maximum for       Maximum for
Pollutant Property	Any One Day	Monthly Average

      mg/kg (Ib/million Ibs) of mercury condensed

Arsenic                   1.946             0.868
Lead                      0.392             0.182
Mercury                   0.210             0.084
Silver                    0.406             0.168
Zinc                      1.428             0.588
                              152

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         PRIMARY PRECIOUS METALS AND MERCURY SUBCATEGORY

                           SECTION XIII

          BEST CONVENTIONAL POLLUTANT CONTROL TECHNOLOGY
EPA is not proposing best conventional pollutant control
technology (BCT) for the primary precious metals and mercury
subcategory at this time.
                                153

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