EPA-903/5-78-001A


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  |     UNITED STATES ENVIRONMENTAL PROTECTION AGENCY


                                 REGION VIII

                               1860 LINCOLN STREET

                             DENVER COLORADO 80295
                               MAR  1 3 1978
            TO ALL INTERESTED GOVERNMENT AGENCIES,  PUBLIC
                       GROUPS AND  INDIVIDUALS
     Enclosed is a copy of  the  final  environmental  impact statement
(EIS) for the proposed Sludge Management  Plan of the Metro Denver
Sewage Disposal District, Commerce  City,  Colorado.   Your review and
comment on the EIS is appreciated.  Written  comments should be sent
to the above address.  Please contact Mike Gansecki  (837-4831) of
the Region VIII staff for additional  assistance.

     The EIS comprises three volumes:  Volume I is the EIS statement.
Volume II contains written  comments and public hearing testimony on
the draft EIS and a detailed discussion of the important issues, and
Volume III is a summary.

     EPA intends by release of  this final EIS to approve the Metro
Denver Sludge Management Plan with  certain modifications and condi-
tions described in Volume II and  the  summary.  EPA will  not take
action for final approval of this facilities plan until  completion
of the thirty-day review period ending April 15.
                                        Merson
                                   Regional  Administrator

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EPA-908/5-78-001A
                        FINAL EIS

                       VOLUME I


                           on


                  METRO DENVER SLUDGE MANAGEMENT PLAN

               (Facilities for the Metropolitan Denver Sewage
               Disposal District #1, Commerce City, Colorado)

                    EPA Project Number-  C0080341
                                by
                U.S. ENVIRONMENTAL PROTECTION AGENCY

                        REGION VIII, DENVER
                           February 1978

                     Approved By:  Alan Merson
                                   Regional Administrator
         Prepared under Contract Number 68-01-3407 between
           EPA           and         Engineering-Science  Inc.
                                         600 Bancroft Hay
                                    Berkeley, California 94710

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    This report has been reviewed by the Region VIII
Office of the U.S. Environmental Protection Agency
and approved for publication.  Mention of trade
names or commercial products does not constitute
endorsement or recommendations for use.
          This document is available to the
          public through the National  Technical
          Information Service, Springfield,
          Virginia, 22161.

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       Metropolitan Denver Sewage Disposal District No,
                        Denver, Colorado
                    EPA Project No. C-0080341
 (  ) Draft                  (x) Final Environmental Impact Statement

 1.  Name of Action:      (x) Administrative        ( ) Legislative

 2.  Description of Action:  The Metropolitan Denver Sewage Dispos-
 al District No. 1  (Metro)  has proposed to construct the necessary
 facilities to  transport sludge to a site in Adams County for air
 drying  in earthen  basins,  stockpilina in above-ground windrows and
 distributing to the  farming community to be reused on land for grow-
 ing crops.  It is  envisioned that anaerobically digested sludge--
 digester construction  already being funded by EPA--in the
 amount  of 107  dry  tons per day  will be produced in the design
 year  1985.  The types  of lands expected to receive sludge from
 Metro include  city parks in the metropolitan area, sod farms, mine
 spoil sites, irrigated farms, nonirrigated farms and home gardens.
 It is assumed  that application rates will be consistent with the
 nutrient uptake rate of the growing plants and that sludge applica-
 tion  on a given piece  of land will be terminated when the heavy
 metal loading  limit  specified for that particular land will have
 been  reached.

 3.  Environmental  Impacts:

    A.  At the sludge  drying and distribution center:

        (1) At least 243 ha [600 acres] of dryland wheat production
 will  be lost.  Production  on the remaining 775 ha [1320 acres] will
 depend  upon Metro  research and demonstration activities.

        (2) Groundwater quality could gradually be deteriorated by
 the leachates  from the bottom of the drying basins, carryina salts,
 including nitrates,  to the water table.  EPA will require lining of
 the basins to  minimize leachate movement to the water table.

        (3) An increased amount of water up to 6,000 cubic metres
 [1.5 million gallons] per  day, more than that now consumed in the
 existing sludge disposal practices of Metro will be carried in sludge,
 purge water and additional  irrigation water to the Adams County site,
 slightly reducing flows in the South Platte River downstream of the
 Central  Plant.

        (4)  A  sizable saving in transport energy (0 million KUH/
yr) will be realized over  the current method of sludge disposal
 In addition,  about 20 million K'.JH/yr of equivalent energy will be
 saved if all  the sludge is successfully marketed to replace com-
 mercial  fertilizer.  If the digester gases are coverted into
 usable energy,  another major saving of 50 million K'JH/yr will  be
 reali zed.
                            i11

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        (5) Odors generated in the drying basins-- may occasionally be
objectionable to the surrounding farmers and other residents.  Grant
conditions will limit the use of the site for digester upset disposal
to underground injection at agronomic rates.

        (6) Severe effects on soils, plants and the groundwater
would occur if the site were to be used for a disposal area.  How-
ever, EPA grant conditions will prohibit use of the site for disposal
except as provided under (5), above.

    B.  At the sludge reuse areas:

        (1) Introduction of excessive heavy metal elements,  particularly
cadmium, into the soils and the food chain, and their gradual concen-
tration magnification in various tissues, could'pose a health hazard
to humans and possible reduction in yield of crops.  These hazards
are the greatest in home gardens and on irrigated farms.  EPA will
recommend limits for use and indicate areas where sludge should not be
applied.

        (2) Longevity of certain parasites such as Ascaris beyond
the drying/storage period may comprise a public health hazard,
especially in home gardens and city parks.

        (3) Water quality degradation from salt and nitrate movement
below the root zone in home gardens, irrigated farms, city parks and
sod farms is a long-term, though minor, cumulative impact.

        (4) Air quality may be degraded by particulates and aero-
sols during severe windstorms, especially in dry-farmed areas.  This
impact will be limited because of the generally cohesive nature of
dried sludge.

        (5) Soil productivity will improve (although salinity will
gradually increase) with the addition of the organic matter  in the
sludges, resulting in improved vegetative growth and crop produc-
tion.

        (6) Conservation of natural resources, especially fossil
fuels and plant nutrients, is a prime reason for, and the most
salient beneficial impact of, the project.


    C.  At the Lowry Bombing Range sludge disposal area, if the
current disposal method is continued:

        (1) Heavy metal  elements may be introduced into the food chain
through grazing of livestock on the sludge-amended fields.

        (2) A potential  public health hazard to the operators at
the Bombing Range is posed by the high pH raw sludges now deposited.

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        (3) There is a threat to groundwater quality from the move-
ment of salts (particularly nitrates) below the root zone.  Surface
water is also affected during periods of runoff.

        (4) Even though soil structure and water-holding capacity will
increase, excessive salt and nutrient loading rates will somewhat
limit the increase in productivity.

        (5) The sludge drying practices and transport method to carry
sludge to the Bombing Range use large amounts of energy.

        (6) Large amounts of chemicals are used to reduce odors and
dewater the sludge under present operation.

        (7) The Metro Central Plant will  experience increases in load-
ings of suspended solids, BOD and ammonia due to return of supernatant
from the anaerobic digesters.
4.   A1ternatives:  Sixteen alternatives, ranging from no action to
heat treatment-air drying-landfill  to vacuum filtration-pipeline
transport and recycling with solid  wastes were considered.   They
are summarized in Tables 1  and 2.

5.   Distribution: The distribution list is presented in Appendix H.

6.   Draft Statement Sent to Council  on Environmental Quality:
     29 July 1976.

7.   Final Statement Sent to Council  on Environmental Quality:

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                        TABLE OF  CONTENTS
List of Figures

List of Tables

Section

  I         BACKGROUND                                           1
               Introduction                                       1
               The Reason  for  This  Document                       2
               History of  the  Project                             5
               The Proposed  Action                                7
                  Financing  the  Project                         10

  II        ALTERNATIVES TO  THE  PROPOSED  ACTION                 11
               Introduction                                     11
               Historical  Development  of  Alternatives           12
               Comparative Evaluation  of  Sludge Treatment       14
                 System Alternatives
               Sub-System  Alternatives                         22
                  Sub-System Alternatives to  the Metro  Land     22
                    Recycling  Proposal
                  Sub-System Alternatives to  the Present        32
                    Lowry  Disposal  System

  III        ENVIRONMENTAL  SETTING                               35
               Climate                                         36
                  Temperature                                   36
                  Precipitation                                 36
                  Wind                                         36
                  Regional Climatic Variations                  41
               Topography                                       41
               Geology                                         44
                  Earthquakes                                   51
               Soils                                           52
               Water                                           54
                  Groundwater                                   54
                  Surface  Water                                 55

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                   TABLE OF CONTENTS (Continued)
Section                                                       Page

               Biology                                          56
                  Cultivated Lands Unit                         58
                  Uplands Unit                                  59
                  Riparian and Aquatic Unit                     59
                  Urban/Residential Unit                        60
                  Rare and Endangered Species                   61
               Air Quality                                      64
                  Odor                                          68
               Archaeology and History                          71
               Land Use                                         71
               Land Tenure                                      73
               Population                                       73
                  Regional Population                           73
                  Metropolitan Denver Sewage Disposal Dis-      75
                    tn'.ct No. 1
                  Adams County                                  75
                  Population Projections                        76
               Transportation and Circulation                   76
               Recreation                                       80
               Institutional and Governmental Agency Juris-     80
                 dictions
               Socio-Economic Setting                           82
                  Adams County Agricultural Economy             82
                  Sources of Fertilizer                         82
                  Urban/Rural Characteristics                   84
                  Land Values                                   84
                  Employment                                    86
               Visual Aesthetics                                86
               Public Health                                    87

   IV        DESCRIPTION OF PROPOSED ACTION                      89
               Sludge Treatment                                 89
               Sludge Transport System                          91
               Sludge Drying and Distribution Center            92
                  Sludge  Drying and Distribution Center Site    92
                    Selection
                  Drying  and Distribution Center Operation      93
                    and Layout
               Proposed Land Application of Sludge by Metro     96
                 Denver
                  Sludge  Recycling Areas                        98
                  Sludge  Disposal at  Lowry Bombing Range        105
                    (No Action)

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                  TABLE OF CONTENTS  (Continued)


Section                                                      Page

  V         ENVIRONMENTAL  IMPACTS  OF  THE  PROPOSED ACTION       109
               Introduction                                   109
               Impact of Sludge  Processing, Transfer,          109
                 Drying and Distribution
                  Soil  Loss                                   10?
                  Water                                       110
                  Public Health                                112
                  Loss  of  Habitat                              117
                  Air Quality                                 117
                  Noise                                       120
                  Energy Use                                  121
                  Aesthetics                                  123
                  Plant Operation  and Plant Effluent           124
                    Quality
                  Natural  Resources                            124
                  Archaeology and  History                     125
                  Land  Use                                    126
                  Land  Tenure                                 127
                  Population                                  127
                  Transportation and  Circulation               127
                  Recreation                                  129
                  Governmental Agency Jurisdiction             130
                  Employment                                  130
                  Land  Values                                 130
                  Construction  Impacts                        131
                  Secondary Impacts                            132
                  Summary  of Impacts  at the Sludge Drying      135
                    and Distribution  Center
               Impacts  of  Land Application of  Sludge on        137
                 the Recycling Areas
                  General                                      137
                  Food  Chain                                  141
                  Public Health                                143
                  Water Quality                                145
                  Soil  Properties                              148
                  Air Quality                                 154
                  Flora and Fauna                              156
                  Noise                                       162
                  Aesthetics                                  162
                  Natural  Resources                            163
                  Traffic  and Circulation                     164
                  Agricultural  Economy                        164
                  Land  Values                                 165
                  Summary  of Land  Application  of Sludge on     165
                    the Recycling  Areas

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                  TABLE OF CONTENTS  (Continued)


Section

               Impacts of Subsurface  Injection of  Liquid       166
                 Sludge at the Drying/Distribution Center
               Impact of Sludge Disposal  at  Lowry  Bombing      167
                 Range
                  Food Chain                                  167
                  Public Health                               169
                  Plant Operation and Effluent Quality         169
                  Soil Properties                             170
                  Water Quality                               170
                  Flora and Fauna                             171
                  Noise                                       174
                  Air Quality                                 175
                  Aesthetics                                  175
                  Traffic and Circulation                     176
                  Public Reactions                            176
                  Natural Resources                            176
                  Land Use                                    176
               Impact of Sludge Landfill ing  at Lowry          177
                 Landfill
                  Soil Properties                             177
                  Water Quality                               177
                  Flora and Fauna                             178
                  Air Quality                                 178
                  Explosive Gas Production                    179
                  Land Use                                    179
                  Resources                                   179
                  Summary of Impacts  of Sludge Disposal  at    179
                    the Lowry Bombing Range

  VI        NEGATIVE IMPACTS AND RECOMMENDED .MITIGATIVE        181
              MEASURES
               Processing, Transfer,  Drying  and  Distribution  181
                  Groundwater Pollution by Nitrates and        181
                    Salts Leaching from Sludge Drying Basins
                  Surface Water Pollution from .Experimental    182
                    Plots
                  Potential Threats  to Public  Health          182
                  Proliferation of Insect Vectors  on Sludge    182
                    Drying Basins
                  Air Pollution from Particulate Matter  of    182
                    Sludge Origin
                  Production of Nuisance Odors  in  Drying      182
                    Basins
                  Negative Public Reaction to  Establishment    183
                    of the Drying and Distribution Center

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                  TABLE OF CONTENTS (Continued)


Section

               Land Application in Sludge Recycling Areas
                  Heavy Metals Accumulation in Soil,
                    Plants, Animals and the Food Chain
                  Nitrate Pollution of Groundwater, Espe-     185
                    cially in Irrigated Farms, Sod Farms,
                    Home Gardens, City Parks
                  Nitrate Pollution and Eutrophication of     185
                    Lakes and Other Water Bodies
                  Air Pollution from Particulate Matter of    185
                    Sludge Origin
                  Exposure of Humans to Viable Pathogens      185
                    and Parasites
                  Exposure of Animals to Viable Pathogens     186
                    and Parasites
                  Odor                                        186
                  Adverse Public Reactions                    186
                  Initial  Toxicity of Liquid Sludge to        187
                    Seeds and Young Plants
                  Ingestion of Sludge from Foliage and Soil    187
               Existing Disposal Operations ("No Action")
                 at Lowry Bombing Range
                  Heavy Metals Accumulation in Soil, Plants,   187
                    Animals and the Food Chain
                  Possible Loss of Unique Vegetation Type     187
                  Possible Destruction of Rare and Endan-     187
                    gerea Plant Species
                  Possible Loss of Black-Footed Ferret Habi-   188
                    tat
                  Initial  Toxicity of Liquid Sludge to        188
                    Seeds and Young Plants
                  Air Pollution from Particulate Matter of    188
                    Sludge Origin
                  Reduction of Grazing Resource               188
               Lowry Landfill                                 188
                  Removal  of Wildlife Habitat                 188
                  Groundwater Pollution                       188
                  Explosive Gas Production                    189

VII          LONG-TERM CONSIDERATIONS                          191
               Adverse Impacts that Cannot be Avoided         191
                  Sludge Drying and Distribution Site         191
                  Land Application Sites for Recycling        192
                    Sludge
                  Lowry Bombing Range Sludge Disposal          193
                    Area ("No Action'')

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                  TABLE OF CONTENTS (Continued)


Section                                                       Page

               Irreversible and Irretrievable Resource         193
                 Commitments
                  Destruction of Soil  Profile                  194
                  Energy Use                                   194
                  Groundwater Use as Receiving Medium          194
                  Application Site Soil  Commitment             194
               Relationship Between Short-Term Uses of the     194
                 Human Environment and the Maintenance and
                 Enhancement of Long-Term Productivity
                  Conservation of Non-Renewable  and            195
                    Renewable Resources
                  Potential Cumulative Long-Term Environ-       196
                    mental Damage
                  The Long-Term Environmental  Perspective       197

  VIII      COORDINATION WITH AGENCIES AND PUBLIC INVOLVEMENT  199
               Governmental Agencies                           199
               Public Involvement                              199
                  Public Reaction to Drying and  Distribution   202
                    Site
                  Public Reaction to Land Application Sites     202

  IX        REFERENCES                                         203

Environmental Team                                             213

                           APPENDICES
Appendix

   A        Evaluation of Alternative Sludge Handling and       A-l
              Disposal Systems

   B        Soils                                              B-l

   C        Biology                                            C-l

   D        Sludge Application to Land                         D-l

   E        Environmental  Settings of Drying and Distribu-     E-l
              tion Site and Specific Land Application
              Sites for Metro Denver Sludge

   F        Examples of Approval  for or  Interest in the        F-l
              Proposed Project

   G        Summary of Impacts at Alternative Sludge Drying/   G-l
              Distribution Sites

   H        Distribution List                                  H-1
                             xn

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                          LIST OF FIGURES
Figure                                                        Page
   1     Project area and example sludge application  sites       8
   2     Potential drying and distribution center  sites          24
   3     Irrigated and dryland farms,  sod farms  and parks        26
           of the Denver area in relation to  the sludge
           distribution site
   4     Generalized precipitation pattern in the  Metropoli-     38
           tan Denver region
   5     Topography of project area                             45
   6     Geologic map of areas in the  vicinity of  Metropoli-     47
           tan Denver
   7     Soil associations in vicinity of Denver                53
   8     Natural vegetation of Colorado                         57
   9     Summary of biotic community characteristics, Metro-     62
           politan Denver area
  10     Colorado Air Quality Control  Regions                   65
  11     Annual frequencies of winds of various  velocities       67
           at Stapleton Airport, Denver, Colorado
  12     Metropolitan Denver proposed  sludge  drying and  dis-     94
           tribution center
  13     Ammonia and total Kjeldahl nitrogen  concentration       95
           as a percent of the total solids concentration
           in three layers in air drying basins
  14     Relationship between allowable sludge application      101
           rate and uptake of mineralized nitrogen for
           sludges containing different amounts  of nitrogen
  15     Annual sludge application rates                       103
  16     Summary of impacts at the proposed sludge drying       136
           and distribution center for Metro  Denver
  17     Summary comparison of relative impacts  of sludge       138
           recycling on various land application sites in
           the vicinity of Denver
  18     Summary impacts of sludge disposal at the Lowry       168
           Bombing Range
                             xi ii

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                   LIST  OF  FIGURES  (Continued)

Figure                                                        Page
  A-l     Process  trains  for various alternatives               A-12
  D-l     Daily consumptive  water use of crops grown near       D-21
           Denver,  Colorado
  E-l     Sod  farm and dryland wheat farm                       E-6
  E-2     Soils on the sod farm and adjoining dryland farms     E-7
           in Adams  County
  E-3     Representative  mine spoil site                        E-12
  E-4     Representative  agricultural reuse areas               E-17
  E-5     Lowry Bombing Range disposal area                     E-26
  E-6     Soils of tne Lowry Bombing Range sludge disposal      E-30
fable
           areas
                        LIST OF TABLES
   1      Summary of Sludge System Alternatives Evaluation      16
   2      Final Sludge Handling Alternatives Comparison         20
   3      Temperature, Precioitation, Snow and Freeze Data,     37
          Denver  (WB City)
   4      Maximum Precipitation Frequency, Thunderstorm and     39
          Relative Humidity Data, Denver
   5      Wind Data, Denver (WB Airport)                        40
   6      Temperature, Precipitation, Snow and Freeze Data,     42
          Denver  (WB Airport) and Fort Lupton
   7      Temperature, Precipitation, Snow and Freeze Data,     43
          Cherry Creek Dam and Byers
   8      Typical  Elevations for Sites Within the Study Area    44
   9      Stratigraphic Units and Their Water-Bearing Proper-   50
          ties in the Vicinity of Denver
 10      Population by County, 1970-1975                       74
 11      Population Growth Rates, Adams County                 75
                            xiv

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                    LIST OF TABLES (Continued)
Table                                                         Pac
e
  12     Selected Population Projections for Counties  in         77
           Vicinity of Metro Denver
  13     Population Forecasts for the Five-County Denver         78
           Region in the Year 2000
  14     Population and Sludge Load Projections  for  Metro        79
           Denver District
  15     Value of Crops Produced in Adams County, 1972-1973      83
  16     Livestock on Farms, 1 January 1973, Adams County,       83
           Relative to All Colorado Counties
  17     Contrasting Socio-Economic Characteristics              85
  18     Adams County Employment Patterns,  1973                  86
  19     Changes in Characteristics of Sewage Sludges  Through    90
           Digestion
  20     Survival Times of Pathogenic Microorganisms in         114
           Various Areas
  21     Estimated Capital Cost and Approximate  Allocation      134
           to Land, Labor and Materials
 A-l     Cost of .Alternative Systems                           A-6
 A-2     Cost of Alternative Systems Treating the Capital       A-7
           Cost of Anaerobic Digestion as a Sunk Cost
 A-3     Cost Summaries Using 10 Percent Discount -  No        A-28
           Inflation
 A-4     Cost Summaries Using 10 Percent Discount and          A-29
           8 Percent Inflation
 B-l     Soil Associations in tne Vicinity  of Denver           6-1
 C-l     List of Plant Species Observed Daring Field Recon-     C-l
           naissance, August 7, 1975
 C-2     Commonly Occurring Range Species in the Denver Area    C-3
 C-3     Native Trees and Associated Shrubs in the Denver       C-5
           Area
 C-4     Common Birds of the Denver Region                      C-6
 C-5     Common Maiirruls of the Denver Region                  C-10
 C-6     Common Amphibians and Reptiles of  the Denver  Region   C-12
                              xv

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                   LIST OF TABLES (Continued)
Table                                                         Page

 C-7     Common Fishes in Streams and Lakes of the Denver     C-13
           Region

 D-l     Three Main Categories for Haste Organics Applica-    D-3
           tion to Land
 D-2     On-Farm Fertilizer Used in Denver Area,  1970         D-18

 D-3     Reported Nutrient Removal by Crops                   D-20

 D-4     Sludge Heavy Metals Content Computed  from Samples    D-25
           Obtained and Analyzed over a  Period of Four
           Months in Early 1975

 D-5     Comparison of Metro Denver Sludge Heavy  Metal  Con-   D-26
           tent with Suggested Limits

 E-l     Comparative Fertilizer Usage at Selected Sod Farms   E-9
           in the Denver Region

 E-2     Temperature, Precipitation,  Snow and  Freeze  Data,    E-13
           Berthoud Pass

 E-3     Value and Area of Crops Harvested in  Weld, Adams     E-16
           and Arapahoe Counties in 1973

 E-4     Pertinent Characteristics of Selected Soils  Under    E-19
           Irrigation in Weld County

 E-5     Pertinent Characteristics of Selected Soils  in Dry-  E-24
           land Farming in Adams County

 E-6     Pertinent Characteristics of Soils in Lowry  Bomb-    E-28
           ing Range Sludge Disposal  Sites

 G-l     Summary of Impacts at Alternative Sludge Drying/     G-l
           Distribution Sites
                             xvi

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w
i
H

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     This section provides an introduction to
the problem of sludge handling at Metro and a
brief description of the proposed land-recycling
system.  It also explains the role of EPA in the
project and its reguiremencs for fulfilling the
National Environmental Policy Act.

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                            SECTION I

                           BACKGROUND
INTRODUCTION

     Victor Hugo's Paris was discarding some five mill inn francs
worth of sewage per year, by his estimates, in the mid-19th Cen-
tury.  His graphic and prophetic lament on the wastage of this
valuable material was in part motivated by the untenable social
and economic conditions dramatized in i.es A?i sera hies.   While many
underlying conditions have drastically changed and new types of
social problems and technologies have since emerged,  it appears
that we nave come full circle back to the realization  of the po-
tential resource value of our waste products.

     The outbreaks of cholera in Europe in tne early 19th Century
led to the beginnings of sanitation systems.  Today,  in many de-
veloping countries which have not adopted such systems, the rate
of incidence of enteric diseases is still vivid testimony to the
need for the protection of human health.  Tne potential health
problems of waste application to land have multiplied since
Victor Hugo wrote his masterpiece by the introduction  into the
sewers of large quantities of exotic elements and by the sheer in-
crease in the size of our metropolitan areas.  Thus,  realistically,
waste products of human beings are both a valuable resource and a
potential environmental hazard.

     Placement of sludge upon the land is at once the  oldest and
the most recent concept in the use and/or disposal of  this mate-
rial.  It is an old practice in all parts of the world.  Before
communities evolved into complex social structures that required
proper sanitation facilities, land disposal of human wastes was
the most logical approach.  In many developing countries, these
wastes are even now directly utilized for crop Tertilization, and
as such they are traded as a valuable commodity.

     Application of sludge to land is a relatively new concept in
the more technologically advanced countries—particularly in the
United States—because of recent concerns over water quality degra-
dation caused by the various other existing sludge disposal prac-
tices. Modern widespread consciousness ot the energy and resource

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values that could be derived from sludges is another impetus for
land application.  Thus, in a recent revision to EPA's grant regu-
lations and procedures, it is stipulated that:

          Grantees must participate in the National Energy
     Conservation Program by fostering, promoting, and
     achieving energy conservation in their grant programs.
     Grantees must utilize to the maximum practical extent
     the most energy-efficient equipment, materials, and
     construction and operating procedures available.
                                            (Reference 1)

     A main factor causing the great difference between the "new"
land application and reuse of sludges and the "old" fertilizer use
of human wastes is the altered chemical properties of the respec-
tive materials involved.  Modern plumbing systems, and industrial
inputs into municipal sewers have changed the  character of sludges
by introduction of potentially toxic and otherwise dangerous mater-
ials.  This, coupled with the ever present microorganisms, includ-
ing pathogens, makes sludge application to land a very sensitive
matter which must be subject to careful design, surveillance and
management control.

     The environmental impact of land application of sludge in-
cludes the beneficial impacts (such as conservation of energy and
nutrients and improvement of physical characteristics of the soil)
and adverse impacts  (such as potential degradation of ground and
surface water quality and soil chemical characteristics as well as
numan health and the food chain).  The degree and extent of these
impacts vary qualitatively and quantitatively from one proposed
application site to another, sometimes in an entirely opposite fa-
shion.  Therefore, the impacts of sludge application are clearly
identified with the category of land use to which the sludge might
be applied.  For each category, typical sites were selected and
studied in detail, and the conclusions are expected to be typical
for other areas of similar character and use.

THE REASON FuR THIS DOCUMENT

     The National Environmental Policy Act (NEPA) requires every
Federal agency to prepare a detailed statement on environmental
impact for each of its major proposed actions significantly affect-
ing the environment.  In this case, the Environmental Protection
Agency is proposing to approve a facilities plan tor the management
and disposal of sludge, by the Metropolitan Denver Sewage Disposal
District No. 1.

     EPA's responsibility for the approval of a wastewater treat-
ment facility is given to it under Public Law 92-500, known as the

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Water Pollution Control Act Amendments of 1972.

     EPA has decided that approval of this plan  constitutes a major,
significant action under NEPA and is therefore preparing a detailed
environmental impact statement.  An environmental  impact statement
(EIS) must consider the environmental impacts of a proposed action,
both short and long term (and especially the irreversible, adverse
kinds), and alternatives to the action.

     Under Title II of the Water Pollution Control Act Amendments,
EPA is given authority to distribute construction  grant fundings
for municipal wastewater treatment facilities,   ihis section of  the
Act defines a three-step process of planning (Step I), design (Step
II) and construction (Step III) that must be fulfilled for an eli-
gible grant applicant to construct a facility with Federal funds.

     Tne Step I process works as follows:  an applicant who is cer-
tified through a State priority system prepares  a  facilities plan.
EPA will pay 75 percent of the costs of  such a plan.  Before a plan
can proceed to the design and construction phase,  the plan must  be
approved by EPA.  Design (Step II) review is delegated to the State.
EPA has determined that tne approval process ot  a  facilities plan
constitutes the Federal action under NEPA.

     Sludge treatment and disposal units are considered an integral
part of the wastewater treatment process and hence are eligible  for
funding.  Section 212(A) of the Act defines  such facilities to in-
clude land acquisition costs if they are part of the treatment process:

          The term "treatment works" means any devices and
     systems used in the storage, treatment, recycling, and
     reclamation of municipal sewage or  industrial wastes of
     a liquid nature ... including site  acquisition of the
     land that will be an integral part  of the treatment
     process or is used for the ultimate disposal  of residues
     resulting from such treatment.

     The Congressional philosophy for the need to recycle and re-
claim many of the pollutants in sewage,  including sludge, in a
beneficial manner is clear in Sections 201(d), (e) and (f) of the
Act:

          (d)  The Administrator shall encourage water treat-
     ment management which results in the construction of
     revenue producing facilities providing for—

               (1)  the recycling of potential sewage pollu-
          tants through the production of agriculture, silvi-
          culture, or aquaculture products,  or any combination
          thereof;

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               (4)   the ultimate disposal  of sludge in a
          manner that will not result in environmental
          hazards.
          (e)   The  Administrator shall encourage waste
     treatment management which results in integrating fa-
     cilities  for sewage treatment and recycling u'j th faci-
     lities to treat, dispose of,  or utilize other indus-
     trial and municipal wastes, including but not limited
     to solid  waste and waste heat and thermal discharges.
     Such integrated facilities shall be designed and oper-
     ated to produce revenues in excess of capital and
     operation and  maintenance costs and such revenues
     shall be  used  by the designated regional management
     agency to aid  in financing other environmental improve-
     ment programs.
          (f)   The  Administrator shall encourage waste
     treatment management which combines "open space" and
     recreational considerations with such management.

     In addition to the environmental considerations required under
NEPA, EPA must determine whether the facility considered in this
plan meets the goals of the Federal Water  Pollution Control Act
Amendments of  1972  stated above.

     The Metropolitan Denver Sewage Disposal District No. 1 (re-
ferred to as "Metro") has submitted a facility plan to EPA and the
State of Colorado to process and dispose of its sludge by recycling
it to the land.  This EIS considers the effect such a plan would
have with regard to requirements of the following Federal environ-
mental laws, among  others:

     (1) Federal Water Pollution Control Act Amendments of 1972
     (2) Clean Air Act (of 1970)
     (3) various legislation regarding noise, solid waste and pesti-
         cides
     (4) Historic Sites, Buildings and Antiquities Act of 1935
     (5) the Endangered Species Act of 1973 and Endangered Species
         Conservation Act of 1969  and amendments

     Because sludge is being considered for use on products that
could reach the human and animal food chains, the expertise of the
Food and Drug  Administration and the Department of Agriculture
will be solicited.   All appropriate State  standards and regulations
will have to be met, including the Solid Waste Disposal Sites and
Facilities Act requirements.  This act is  administered jointly by
the State Health Department and the Board  of County Commissioners
for the county in which the proposed site  is to be located.

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     Uhile the Department of Health makes recommendations, the
County must approve specific site  locations for any solid waste
disposal area.  State  law defines  sludge as a solid waste for
purposes of this act.

     Agency expertise  and public opinion were sought by EPA for this
project.  The draft EIS has been distributed for review, and EPA has
conducted public hearings to solicit additional information.  This
document is the final  EIS for the  Denver Metro Sludge Management
Plan.  This document contains a resolution of any  issues raised in
the course of the review of the draft EIS.  EPA has determined that all
of the important issues have been  satisfactorily resolved, and after
at least 30 days from  the release  of the final EIS, this facility
plan will be approved.

     EPA assigned the  consultant Engineering-Science, Inc. to assist
the agency in reviewing this very  complex plan, to obtain additional
expertise and to help  prepare the  EIS document.  This document repre-
sents the position of  the Environmental Protection Agency regarding
this plan except where the consultant's own recommendations or posi-
tions are explicitly identified.

HISTORY OF THE PROJECT

     The Metropolitan  Denver Sewage Disposal District wastewater
treatment facilities were originally constructed in 1966 with a
design capacity of 5.15 cu m/sec [117 mgd].   The overall BOD reduc-
tion goal was 80 percent.  Sludge  processing involved ciewatering
through dissolved air  flotation, vacuum filtration, flash drying and/
or incineration.  At that time, it was expected that the relative
proportions of raw primary sludge, anaerobically digested sludge
and undigested waste-activated sludge would be such that the vacuum
filter would produce a filter cake solids concentration of 22 to
25 percent.

     By 1967, the District realized that the proportion of waste-
activated sludge in the mixture was much larger than had been ex-
pected, giving rise to increased difficulty in dewatering the sludge
mixture (achieving only 14 to 18 percent solids concentration of the
filter cake).  Thus, the need for  chemicals for vacuum filtration
more than doubled, and the increased moisture content overloaded the
design capacity of the flash dryer-incinerator.  Corrosion of the
stainless steel components of the  dryer-incinerator resulted from the
heavy doses of ferric  chloride used in sludge conditioning, further
compounding the problems with the  sludge handling  system.

     This problem became intolerable in the fall of 1968.  More than

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half of the evaporative capacity of the dryer-incinerator had be-
came unavailable because of mechanical problems; and activated
sludge was accumulating in the biological treatment system, rapidly
deteriorating the effluent quality.  Therefore, lagoons were con-
structed for the winter months of 1968 and 1969.  Odors generated
in these lagoons brought about loud complaints and forced the Dis-
trict to shift to land disposal of the filter cake in May 1969.
Since that time, land disposal, with various types of equipment, at
various rates and under different conditions, has been practiced at
an abandoned portion of the Lowry Bombing Range, some 40 km [25
miles] southeast of the treatment plant.

     Some of the land application operations were conducted by
District personnel, while others were performed by contractors.
Odor problems resulting from the method of disposal used by con-
tractors gave rise to adverse neighborhood reactions and complaints
to Arapahoe County Commissioners.  A public hearing was held on 20
June 1972 at which the District was committed to a new, revised
land application method aimed at eliminating odor and fire hazards
(Reference 3).  The new method has since been utilized during dry-
weather conditions, as described in Section IV under Land Applica-
tion at Lowry Bombing Range.  Inclement weather operation is simi-
lar to standard sanitary landfill ing of solid wastes.

     In 1971, the District consultants prepared an expansion plan
for the central plant and recommended an agricultural reuse scheme
for the sludges produced (Reference 4).  After two public meetings
with residents of the proposed reuse area in the winter of 1972-
1973, some revisions were made, and a new agricultural reuse pro-
gram was prepared by the District (Reference 5).  The system has
since been further refined in concept, and in February 1975 a four-
volume sludge management plan was published, comparing alternatives,
describing the recommended agricultural reuse scheme in detail and
assessing the environmental impact of the recommended plan (Refer-
ence 6).

     That report comprises a facilities plan, which was submitted
to the U.S. Environmental Protection Agency on 27 February 1975.
Earlier, applications for a Step I grant for the sludge management
plan had been made to the State and to EPA (on 19 November and 22
November 1974, respectively).  On 9 June 1975, the Regional Admin-
istrator of the U.S. Environmental Protection Agency sent a "Notice
of Intent to Prepare an Environmental Impact Statement" for the pro-
posed sludge management program of the Metropolitan Denver Sewage
Disposal District No. 1.

     On 30 June 1975, EPA authorized Engineering-Science, Inc. to
prepare an Environmental Impact Statement on the proposed action in

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the plan in accordance with all relevant legislation and policies
and the regulations of EPA.  EPA required an additional  evaluation
of the environmental impact to off-site areas being considered by
Metro for land application of sludge.  Engineering-Science presented
a preliminary draft EIS to EPA incorporating the analysis of off-site
impacts.  The draft EIS was written by Engineering-Science under EPA
management using much of the information in the preliminary report
prepared by Engineering-Science.

     Since release of the draft EIS on 29 July 1976, EPA has solicited
comments and conducted several public hearings in order  to receive
input on all issues.  The results of these comments clearly indicated
that several issues needed a more thorough analysis and  resolution.
This final EIS is, therefore, being presented in two volumes.   Volume
I is the updated version of the draft EIS released last  year.   Volume
II contains a more thorough discussion of those issues which were
determined to be of primary importance.  Volume II also  contains
copies of the letters and written comments which were received relat-
ing to the project.  EPA reponses to points raised in the letters are
listed next to each letter.

THE PROPOSED ACTION

     The sludge management plan proposed by Metro involves treat-
ment, pipeline transport, drying, distribution and application on
land of anaerobical1y digested sludge from the Metropolitan Denver
Sewage Disposal District No. 1 sewage treatment plant in Commerce
City.  Figure 1 shows the location of various components of this
plan in the Denver Metropolitan area.

     All of Metro's sludge would first receive anaerobic digestion
treatment at the central plant before further disposal.   This pro-
cess stabilizes the sludge and reduces odor and pathogens.  EPA
recently gave the District a $5.5 million grant to construct anaer-
obic digesters at the central plant.

     The sludge would then be transported by pipeline to a drying/
storage center site located in western Adams County near Irondale
Road and about 18 kilometers [11 miles] southeast of Barr Lake.
There the sludge would be dried in open basins and stored for fu-
ture use.  This processing site would also be used for marketing,
research and demonstration areas, and as a disposal site on occa-
sion.

     Metro contemplates marketing the dried or liquid sludge to
local dryland and irrigation farmers, for municipal parks, for
mine-land reclamation, and perhaps for individual garden use.  At
worst, Metro could dispose of the dried sludge in a sanitary land-
fill if no markets were available.

     Land areas that might utilize the sludge extend from the AMAX
mine spoils site, near Berthoud Pass, to many of the park areas  in
the metropolitan Denver areas.

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         - \rt	
—•	  ^
COMMERCE CITY, ROCKY
MOUNTAIN ARSENAL,
    ™v~,' BOW DOER 1 K.^ "  -•„
                M£TR,QPQLltAf
                                                                      i
                                                                            •
                                                                  .

                                                                 AAto      M      S
                                                          TRANSPOfiT
                                                  O PIPELINE ROUTE
                                                  fr-^Ri^NT iLub^>^aaM^r7!!!TtOM1
                                                               P   AH   O  .. E
    *J&j&jtm pRpABf? SON

                                                        PROJECT AREA
                                                    AND EXAMPLE  SLUDGE
                                                     APPLICATION  SITES

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It is proposed that air-dried sludge be trucked to application
sites of the types described above and incorporated into the top
layers of soil for ready use of nutrients by plants and improve-
ment in the physical condition ot soils.  A very important assump-
tion implicit in the environmental analysis of the proposed action
is that sludge application rates  (metric tons per hectare per year)
ana quantities (ultimate metric tons per hectare) recommended for
a given piece of land, and other required cultural practices, will
be adhered to by the recipients of the materials. The Colorado
Department of Health has developed regulations for the treatment,
storage, dispersion, and use of stabilized liquid and dried sludge
(reference 130).  Administration  and enforcement of these regula-
tions is the responsibility of the Colorado Department of Health.

     The proposed project will encompass primarily Adams County,
Colorado but will also include the City and County of Denver and
perhaps portions of Arapahoe, Weld, Douglas, Elbert, Jefferson and
Clear Creek counties.  In fact, the cost of transport of air-dried
sludge may become the main factor limiting the distance the mater-
ial is shipped for land application.*  For the purposes ot envi-
ronmental impact analysis, six representative land application
sites are selected, as shown on Figure 1.

     The service area contributing wastewaters to the sewage treat-
ment plants, which in turn produce sludges from the v/astewaters, is
most of the metropolitan Denver area, comprised of more than 20
political entities.  Excluded from the service area at present are
tne separate districts of Commerce City, Rocky Mountain Arsenal,
Glendale, Littleton and Englewood.

     In order to construct facilities considered in any one of the
alternatives (excluding the no-action alternative) discussed in
Section II for the full projected sludge generation rate of 150 dry
metric tons [166 tons] per day, a capital expenditure ranging from
$2.2 to $29 million would be required, depending on the alternative
ultimately selected.  The currently recommended alternative, de-
scribed in detail in Section IV,  has a capital cost of $17.8 mil-
lion as evaluated by Engineering-Science without including cost of
the digesters which have already  been constructed at a cost of
$6.5 mill ion.
 At a trucking cost of $0.08/cu meter-kilometer [$0.10/cu yd-mile],
a distance of 100 km [60 miles] would represent the limit at which
transport cost of dried sludge (with 5 percent nitrogen and 50
percent solids content) equals the current price of equivalent com-
mercial chemical fertilizer nitrogen ($0.55/kilogram [$0.25/lb])
alone.

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Financing the Project

     If approved, the U.S. Environmental Protection Agency would
pay 75 percent of the grant-eligible portion of the capital cost if
further Congressional funding became available, and the District
would bear the remaining 25 percent, as provided by the Federal
Water Pollution Control Act as amended in 1972.

     The local share (25 percent) of the capital cost would have to
be borne proportionately by the users; i.e., the individuals, indus-
tries and businesses using the District's sewerage facilities.
Approval of this plan would allow EPA to reimburse Metro for 75 per-
cent of the eligible design costs of this project.
                                10

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w
 h

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     This Section considers the alternatives to
the proposed project.  It looks at the historical
development of alternatives and provides a com-
parative evaluation of reasonable alternatives,
using environmental, engineering and cost para-
meters.  Areas where alternatives were considered
include processing and disposal, site locations
and transportation.

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                           SECTION II

               ALTERNATIVES TO THE PROPOSED ACTION
 INTRODUCTION
     The National  Environmental Policy Act requires Federal agencies
to consider  "alternatives to the proposed action" in every environ-
mental impact statement.  The law does not specify how thorough
the alternatives must  be, but courts have interpreted it to mean
that a "reasonable" number of alternatives must he considered,
especially any which may have merit in reducing the negative environ-
mental impacts of  the  project as originally proposed.

     This very broad definition of alternatives suggests that not
only are very broad "total  system" alternatives to be considered
but, where particular  features of a given proposal may have unusual-
ly severe impact,  subalternatives within a system should also be
evaluated.   In the case of Metro Denver's proposal, site location
alternatives or drying basin design alternatives might be sub-
alternatives worthy of consideration.

     A second factor must be borne in mind in the review of alter-
natives for  a construction grants program project.  EPA does not
initiate a proposal for construction grant funding; that is the
prerogative  of any legal wastewater management district.  Upon
certification by the State, a district evaluates alternatives and
develops a plan.  The  plan is then sent to EPA for final review.
Although EPA has developed guidelines to assist grant applicants
in order to make them  aware of EPA's responsibilities in consider-
ing project  alternatives, it is inevitable that the applicant will
view the alternatives from a somewhat different perspective than
will  EPA.

     To overcome this difficulty, EPA will give equal consideration
to all alternatives but will recognize the effort that has been
invested in the development of the proposed project.  Only if there
are significant environmental or other objections to the proposed
overall  system will a wholly different system be advanced.  Even
within a given proposal, however, major changes could be required
if the situation so warranted.
                               11

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     This Section describes the historical  background of Metro
District planning leading to the development of alternatives and
to the present proposal; compares total  system alternatives; and
reviews subalternatives to both the proposal and the existing sys-
tem.

HISTORICAL DEVELOPMENT OF ALTERNATIVES

     The Metro Denver Central Plant, built in 1965, is a secondary
biological treatment facility.  The plant not only processes
residual solids from its own aqueous-phase treatment units but
also handles anaerobic digested sludge pumped from the Denver North-
side Plant.  Sludge treatment and disposal  has always been problem-
atical at the plant, as evidenced by the fact that Metro has re-
ceived a number of research grants to evaluate alternative sludge
treatment processes.

     When the Metro plant was built, flash-dry incinerators were
installed to dry sludge for reuse as a soil conditioner in local
parks.  Because of operational problems, Metro abandoned the in-
cinerators in 1971 in favor of dewatering on vacuum filters and
disposal by surface landspreading at the Lowry Bombing Range.
Subsequently, complaints about odors forced Metro to modify its
method of sludge disposal from surface landspreading to landspread-
ing and incorporation into the soil at Lowry.

      In 1971, Metro hired the firm of CH2M-Hill to develop plans for
the Central Plant expansion,  including an evaluation of alternatives
to  the present sludge treatment and disposal system, which was  be-
coming increasingly expensive.  CH2M-Hill studied and evaluated
from an engineering point-of-view three basically different sludge
treatment and disposal systems:

     1.  The present Metro system.
     2.  Multiple hearth incineration.
     3.  Land disposal of digested sludge.

     While the incineration and land disposal alternatives were
felt to be close in overall costs and much preferable operationally
to the present system, Metro  adopted the recommendation of  a
beneficial reuse  system because of an environmental  "net benefit".
In  its land recycling proposal, Metro would  have sprayed anaerobically
digested sludge on about 2,400 ha  [6,000 acres] of farmland either
owned  and operated outright by Metro or leased to farmers.

When  Metro presented this option to the farming community in
western Adams County, it encountered considerable resistance.
Farmers objected to the  loading rates, the effect of having Metro
                                12

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entering the farming business in a large-scale operation and po-
tential effects of odors on land values and health in the area
where the sludge would be stored.  As a result, Metro concluded
that more land would probably be needed to accommodate lower load-
ing rates and became less enthusiastic about engaging in a farming
operation itself.

     CH2M-Hill was authorized to evaluate in more detail  the land
recycling alternatives and in March 1973 produced a study entitled
"An Agricultural Reuse Program" (Reference 5).  This study eval-
uated in much more detail a comprehensive approach to land re-
cycling, using the latest information then available.  The report
considered issues such as various sludge characteristics and their
effects on the land; water-rights issues; state-of-the-art compost-
ing and landspreading systems; fertilizer considerations; loading
rates for semi-arid areas; and the types of crops most likely to
benefit from sludge applications.  A number of land application
alternatives were evaluated in the study.  The more promising sys-
tems identified were drying beds with application to agriculatural
land, permanent subsurface injection on Metro-owned land and re-
cycling on private farm land with short-term injection on Metro-
owned land.  Two other alternatives (spray irrigation or subsurface
injection on privately owned dry farmland, and irrigation of crop-
land owned by Metro) were eliminated because of high cost and
water-rights problems.

     The report included a preliminary site evaluation which served
as a basis for a more detailed site evaluation in the facilities
plan (considered below).  A preliminary design configuration for
the most favored alternative, recycling on private land with short-
term injection on Metro-owned land, was presented in the report.

     Metro remained committed to the concept of land recycling but
required the facilities planner to develop a more comprehensive re-
view of all alternatives.  In the facilities plan, a wide range of
processing and disposal alternatives was evaluated and eight over-
all processing and disposal alternatives were evaluated in detail.
These included:

     1.  The existing system--"no action",
     ~2\  anaerobic digestion--pipeline transport to a drying/dis-
            tribution facility--beneficial reuse,
     3.  dewatering by filter presses--incineration--landfill ,
     4.  heat treatment--dewatering on vacuum filters — landfill,
     5.  heat treatment — pi pel ine transport—drying—landfill ,
     6.  heat treatment—vacuum filtration—incineration—landfill ,
     7.  anaerobic digestion—dewatering by filter presses—com-
            posting—beneficial  reuse, and

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      8.   dewatering by filter presses--composting--beneficial  reuse.

!      The facilities planners recommended the second alternative:   i.e.,
'anaerobic digestion, pipeline transport to a drying/distribution  fa-
'cility and beneficial  reuse.  This alternative became Metro's  pro-
 posed system and is the principal  focus of this particular EIS pro-
 cess.

      In June 1975, EPA retained Engineering-Science (ES) to review
 the facilities plan and develop the EIS.  Part of Engineering-Science's
 task was to evaluate the existing  alternatives and to propose  addi-
 tional alternatives that appeared  promising.  A total  of 17 alterna-
 tives for the processing and disposing of sludge were developed and
 evaluated for this EIS, including  the eight alternatives studied by
 CH2M-H111.

      Table 1 shows the 17 alternative systems evaluated by Engineering-
 Science.  The basic form of disposal  is shown next to the process de-
 scription.  Cost information includes present-worth values with and
 without anaerobic digestion as a sunk cost, with and without an eight
 percent inflation rate and with and without revenue.  Generally,  cost
 information showed that many of the process options were close in
 overall  costs, but land recycling  became much more cost-effective
 when revenues, inflation and sunk  costs were considered.  Alternatives
 in which Metro sludge would be processed together with municipal
 refuse also appeared to be economically advantageous.

      Further evaluation might be warranted if these latter types  of
 systems were to be developed.  However, the Colorado legislature
 failed to act on a Denver Regional Council of Governments (DRCOG)
 bill sponsored to develop a solid  waste recycling system.  Therefore,
 while the systems are promising, the possibility that an actual
 system might be developed in the near future seems unlikely.   Metro
 has indicated that incineration is their preferred alternative if
 the land recycling proposal is not implemented

      Environmental, engineering and cost factors considered,  Engi-
 neering-Science also concluded that the "apparent best alternative"
 involved the Metro land recycling  proposal.  The Engineering-Science
 evaluation is contained in Appendix A, which summarizes the perti-
 nent assumptions made in evaluating the alternative systems.

 COMPARATIVE EVALUATION OF SLUDGE TREATMENT
 SYSTEM ALTERNATIVES

      In considering the work performed by the consultants and  the
 Metro District, a useful perspective can be gained by comparing
 the disposal element in each alternative, since this is the ele-
 ment of a sludge management system that has the most significant
 environmental impact.   The processing alternatives generally
                                 14

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have a relatively small environmental impact; the most important
in-plant consideration is the selection of a combination of pro-
cesses that will efficiently and economically produce a treated
sludge with the requisite characteristics for each particular  dis-
posal mode.  Thus, the comparative evaluation of sludge management
alternatives for the Metro system has as its focus the disposal
elements of the alternatives.

     EPA recently finalized sludge management guidelines (Reference
79) that provide an indication of the way in which the agency
approaches the issue of sludge disposal  from an environmental  point
of view.  The guidelines recognize that disposal of the solid
material in sludge can have significant impact on the environment;
disposal can simultaneously affect air, land and water and may en-
compass such varied considerations as human health, animal health,
plant growth and the protection of ground and surface water from
pollution.  A basic distinction made by the guidelines in consider-
ing the final disposal of sludge is the division of management
techniques into those in which sludge is utilized as a resource
and those in which sludge is not used for any beneficial  purpose.
Examples of beneficial use include land recycling or incineration
for heat or power, while in the case of nonbeneficial disposal,
landfill ing or incineration would simply dispose of the unwanted
sludge without any return benefit.

     Semantic confusion surrounds the word "disposal."  In a gen-
erally accepted sense, the word is taken to mean the last step in
the sludge handling process, regardless of whether beneficial  reuse
is involved.  In the distinction often made, the word "disposal"
is used only to indicate those forms of sludge management where no
beneficial reuse occurs.

     The basic intent of disposal  is simply to take the sludge, as
an unwanted residual material , out of the sewage treatment process
and put it into some other system where it is relatively "harmless."
An environmental concern that must be kept in mind, however, is
that a residual material like sludge is never destroyed by a dis-
posal process but simply converted to another form of matter and/or
energy that continues to exist in the biosphere.

     A distinction between "beneficial" and "nonbeneficial" dis-
posal methods worth noting is that a beneficial method allows
some re-entry of previously unwanted materials into the socio-
economic system; the nonbeneficial system simply puts the residual
material into larger environmental systems—air, land or water.
As a way of maintaining this distinction, disposal systems are re-
ferred to in this EIS as beneficial or nonbeneficial.
                               15

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                                      Table  1.   SUMMARY OF SLUDGE SYSTEM ALTERNATIVES  EVALUATION51

                                                                (millions  of  dollars)
                                                                                                         Cost  comparisons
Alter-
native
numb er
Description
    of
alternative
 Basic
disposal
 method
Anaerobic digestion costs included     Anaerobic digestion not  included  (sunk cost)
   Unadjusted           8%                     Unadjusted            8%
  for inflation      inflation                for inflation      inflation
            Bc
                                                                                                    B
                                                                                                                              B
                                                                                                                                               B
   1A   Existing system—waste-activated and
        other sludges trucked to Lowry  Bomb-
        ing Range for landspreading
   IB   Existing system with anaerobic digestion
   2    Anaerobic digestion,  pipeline transport,
        air drying and beneficial  reuse  (prod-
        uct:  100 percent air-dried  sludge)

   3    Filter presses, incineration, landfill
        of ash

   4    Heat treatment, vacuum filtration,
        landfill

   5    Heat treatment, air drying,  landfill

   6    Heat treatment, vacuum filtration, in-
        cineration,  landfill  of ash

   7    Anaerobic digestion,  filter  presses,
        compost (product:  100 percent nutrient-
        enriched composted sludge)

   8    Filter presses, compost (product:  100
        percent nutrient-enriched  composted
        sludge)

   9    Anaerobic digestion,  centrifugation, com-
        post (product:  100 percent  nutrient-
        enriched composted sludge)

  10    Anaerobic digestion,  pipeline transport,
        air drying,  compost  (product:  50 per-
        cent air-dried sludge; 50  percent
        nutrient-enriched composted  sludge)
                               predominantly
                               land disposal
                                 (spreading)
                                 with some
                                 landfilling

                               land disposal
                                 (spreading)

                               land recycle
                               incineration


                               land disposal


                               land disposal

                               incineration


                               land recycle



                               land recycle



                               land recycle



                               land recycle
                    24.1   24.1
                    24.7   24.7
                    24.0   19.3
                                                     24,2   24.2
                    22.5   22.5
                    28.8  '20.5
                    34.3   34.3
                    30.1   30.1
                    17.7   10.£
                                    26.8   26.J
                    25.9    25.9
                    33.3   33.3      30.2   30.2

                    23.6   23.7      23.6   23.6


                    30.3   19.6      35.1   19.3



                    34.0   17.0      45.1   20.1



                    33.8   25.9      40.1   28.5
                    24.4    12.3
24.1   24.1
22.5   22.4
34.3   34.3
18.6   18.6      26.4    26.4
17.8   13.1      14.0     7.1
                                              24.2   24.2      26.8   26.8
26.0   26.0
33.3   33.3      30.2   30.2

23.7   23.7      23.6   23.6


24.2   13.5      31.4   15.6



33.9   17.0      45.1   20.1



27.6   19.8      36.3   24.8



22.7   14.4      20.7    8.6

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 11    Anaerobic digestion, centrlfugation,          land disposal
       landfill

 12    Anaerobic digestion, pipeline  transport,      land recycle
       air drying, landfill, compost  (product:            and
       33 percent air-dried sludge; 33 percent       land disposal
       nutrient-enriched composted sludge; re-
       mainder to landfill)

 13    Anaerobic digestion, vacuum filtration,       land recycle
       compost (product:  100 percent nutrient-
       enriched composted sludge)

 14    Vacuum filtration, compost  (product:          land recycle
       100 percent nutrient-enriched  composted
       sludge)

 15    Anaerobic digestion, vacuum filtration,         conversion
       pipeline transport to solid waste  re-
       cycling plant

 16    Vacuum filtration, pipeline transport           conversion
       to  solid waste  recycling  plant
26.4   26.4      30.8   30.(
26.9   20.7      24.5   12.4
28.4   20.5      33.8   22.2
27.0   14.5      36.4   18.0
16.8   16.8     17.8   17.8
10.1   10.1     13.3   13.3
20.2   20.1      27.1   27.1
                                            22.8   14.5      20.9    8.7
22.2   14.4      30.1   18.5
30.0   14.5      36.4   18.0
10.6   10.6      14.1   14.1
10.1   10.1      13.3   13.3
 By Engineering-Science,  Inc.

 Without  revenue.

"With revenue.
 Sludges containing  less  than 25  percent  solid materials  would  require  the expenditure of additional resources for the removal of water.

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     The Congressional  philosophy expressed in the Water Pollution
Control Amendments of 1972 makes it apparent that the Congress was
very much concerned with developing and promoting beneficial  ways
to use both sludge and treated wastewater.   In the portions of the
Act quoted in the first Section of this EIS, beneficial  disposal
of sludge can be accomplished either separately by the wastewater
treatment entity or in combination with municipal solid  waste sys-
tems.  Because cost, engineering, institutional  and, to  a certain
extent, environmental considerations differ between these two ap-
proaches, they are distinguished in the comparative evaluation
that follows.  A separate wastewater district might find it very
uneconomical  to incinerate sludge for power purposes, but, in com-
bination with municipal refuse incineration, the system  could prove
attractive.

     Table 2 compares environmental impact, engineering  considera-
tions, institutional factors and costs as they relate to a number
of courses of action.  The alternative courses of action are  or-
ganized in three groups--nonbeneficial disposal, separate beneficial
use and combined municipal refuse and sludge beneficial  use.   It
should be noted that the ranking shown in the Table is,  at present,
simply serving as a guide in the process of comparison;  it is not
yet being used as a decisive factor in the selection of  alternatives.

     The comparative evaluation shows the general preferability of
separate land recycling schemes.  Were the DRCOG solid waste  re-
cycling alternatives a real  possibility, some of these alternatives
would be more attractive.  Metro has evaluated air basin drying
versus composting approaches and decided upon the former as the
method of land recycling.  There appear to be no outstanding  reasons
from EPA's point of view as to why one should be chosen  over  another
in this case.  Recent work on composting sludge shows great environ-
mental and economic promise (Reference 129).

      Other disposal and  recycling  systems do not fare as well for
a  variety of  reasons.   Incineration  (whether heat or power benefits
are  gained or not)  involves air quality problems and is highly en-
ergy-demanding with Metro sludge.  Land disposal methods such as
landfill or  land spreading do not  rate as high overall because of
greater adverse environmental impact, little or  no positive bene-
fit  and higher costs.  Other schemes  involve unproven technology
or are associated with higher costs.

      It is concluded,  from a review of all  the available informa-
tion  at hand, that  some  form of land  recycling,  utilizing air-dried
anaerobically digested sludge,  is  a generally environmentally sound
and  cost-effective  alternative  for the Metro District.  At this
point  in time, EPA  does  not feel that a further  evaluation of al-
together novel sludge  handling  and disposal systems need be consid-
ered;  a more detailed discussion is found in Volume II,  Issue IV-2.

                                18

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     However, in view of the fact that Ketro had an ongoing sludge
handling and disposal system at the Lowry Bombing Range that would
be replaced by a different system, EPA felt that the alternative
of continued use of the Lowry disposal system (perhaps modified to
a certain extent) must be considered in detail.   The National  En-
vironmental Policy Act requires a Federal agency to review the
null or "no-project" alternative.  It seems reasonable for EPA to
question whether a new system, even with the inclusion of environ-
mental improvements, should be funded in lieu of the existing system.
Past evaluations by the Metro District and consultants have indi-
cated problems with groundwater contamination and excessive soil
loadings at Lowry.  Therefore, the Lowry system  is evaluated further
in this document, as well as in Volume II, Issue III-l.

     The EPA guidelines recognize that the choice of a disposal
method is not as important as properly evaluating the chosen method
with respect to a wide range of environmental conditions.   The EIS
process functions to evaluate in detail  any impacted environmental
elements in order to insure the least environmental degradation.
The guidelines indicate that for land recycling  schemes the follow-
ing elements must be considered:

     1.  Soils.
     2.  Groundwater.
     3.  Stabilization of sludge.
     4.  Sludge characteristics (heavy metals, nutrients).
     5.  Pathogen reduction.
     6.  Crop suitability.
     7.  Public access.
     8.  Surface runoff.
     9.  Application methods.
    10.  Application rates (nutrients and trace  elements).
    11.  System operation control.
    12.  Monitoring.
    13.  Food chain considerations.

     Thus, in the body of this Environmental  Impact Statement, EPA
considers in detail the following two sludge management systems.

     1.  Metro's proposed land recycling system  using anaerobic
djgestion, pipeline transport, drying beds, storage and distribution
to the land.  Metro has proposed that dried sludge could be used on
irrigated areas, dryland areas, sod farm operations, metropolitan
Denver parks and reclamation of some mine spoil  areas.  It has also
been suggested that dried sludge might be made available to individ-
ual  home gardeners.  Metro has also indicated the possibility that
the sludge could be bagged and sold commercially.

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Table 2. FINAL SLUDGE HANDLING ALTERNATIVES
FOR METRO DENVER DISTRICT
Sludge
handling
alternative

Land disposal
Landfill





Landspreading




Incineration —
ash disposal




Environmental impacts
Beneficial


None





Can improve soil
structure and add
nutrients


Minimal, material
volume reduced




Adverse


Groundwater leachate
problems, soil sta-
bility, explosive
gas production


Can harm soil quali-
ty by excessive met-
al loadings; can af-
fect groundwater,
food chain
Releases particulates
and gases to air; ash
disposal can create
leachate problems in
groundwater; high
energy utilization
Engineering
Feasibility
Dispo

High





High, but requires
large land areas
and. constant moni-
toring

Moderate, moisture
content of sludge
could affect oper-
ation


factors
Reliability
al

High, but requires
close control of
deposition and must
be mixed with dry
solid waste and/or
soil
Moderate, requires
standby system for
winter and wet days


High, except air
pollution control
equipment may have
problems


COMPARISON
Institutional
ability to
implement


High-existing, but
would require new
disposal sites



High-existing, but
would require new
landspreading sites


Moderate, because
of air pollution
problems





Costs


All disposal operations
have no revenue, low
capital costs and high
operating, energy and
chemical costs

Low capital costs;
moderate operating
costs; high energy
and chemical costs

High capital and energy
costs; moderate operat-
ing costs; chemical
costs could be high



Overall3
rating


Marginal





Acceptable




Marginal





Recycling — Separately
Land recycling
Air drying




Composting




Incineration
Drying —
recyc e


Improves soil
structure; adds
nutrients; mini-
mizes energy use

Improves soil
moisture; high
nutrient value;
minimum energy
use

Cattle feed;
soil amendment


Localized groundwater
problems at drying
site; pathogen prob-
lem; control of final
use difficult
Sane as air-drying





Odor problems; ash
disposal; low inten-
sive energy use


High, but requires
complex coordina-
tion for recycling


Moderate, requires
good market for re-
cycled material



Low with past Metro
experience; could be
higher with anaero-
bic sludge

High, except for
occasional digest-
er failure


High, except for
potential contam-
inants



Low to moderate be-
breakdowns


High, except for
fanning community
resistance to land
se aesthetic de-
terioration
Limited Metro ex-
perience or re-
search in this
area


Low, Metro exper-
unf avorable


High capital coats and
low operating, energy
and chemical costs;
high revenue likely

Same as air-drying;
revenue could be high,
uncertain at this time



Same as air-drying;
uncertain at this time


Most fa-
vorable



Favorable





Acceptable



-------
Ash-heat
product ion

Conversion
Pyrolysis


Cattle feed



Land rcc yc le——
compose ing


Incineration —
power product ion





Conversion
Supplemental
boiler fuel

Synthet ic gas
production



*The overall rating
Produces useful
teat


Useful carbon-
black product

Valuable cattle
feed supplement


Large amounts of
fertiliser and
soil amendment a

Useful heat or
•team energy
produced ID
Large amounts




Energy source
for industrial
use
Synthetic natural
gas for indus-
trial/domestic use


scale (unacceptable ,
Disposal of ash and
leachate to ground-
vater problems

Heavy metal contam-
inants; releases
gases
Unknown, potential
metal contaminants
In food chain

Control of pa t ho—
gens difficult;
odor problems

Ash disposal; re-
lease of gases to
air





Air pollution, ash
residue

Ash residue




marginal, acceptable.
Low as a separate Low
system


Experimental Unknovn


Experimental Unknown


Combined Recycling with Municipal Solid Wastes
Probably high High



Potentially high; /robably high
wat er content in
sludge lowers heat
value; past oper-
at ing problems
with CO from in-
cinerators

Very low, imprac- Low
tical with DRCOC
proposal
Moderate, caloric High, if sludge
and high water con- quality constant,
tent of Metro but unknown re-
sludge somewhat liability for
unfavorable overall system
favorable and most favorable) was developed through
Moderate



Low; untested


Low; untested




ielative support
fr r f inane ing sol-
id waste systems
Low; lack of leg-
islative/financial
support





Low; lack of leg-
islative/financial

Low; lack of leg-
islative/financial
support


a semi-quantitative
ranking and evaluation of the alternatives on the basis of parameter presented In this Table. The subjective nature of this method
High capital, operating
energy and chemical
costs; low revenues

High capital, operating
energy and chemical
costs; revenue unknown
Same as pyrolysls




great extent for all
combined opt ions

Costs unknown, could
be low for Metro






Costs unknown , could
be low for Metro

Costs unknown , could
be low for Metro



relative
is shared
Unaccept-
able


Unaccept-
able

Acceptable



Maro inal



Marginal







Unaccept-
able

Acceptable






by all such attempts at numerical evaluation.

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     2.  Metro's existing disposal  operation of landspreading and
occasional burial  at the Lowry Bombing Range.   The system will  be
modified by the addition of anaerobic digesters at the Metro plant.
Other possible modifications are also discussed.

     The analysis of the alternative systems is prefaced in this
Section by a discussion of the sub-system alternatives within each
of the major alternatives.

SUB-SYSTEM ALTERNATIVES

     Many environmental impacts can be lessened by careful  attention
to the design details of the chosen system.   The  National Environ-
mental Policy Act requires that consideration be  given to lessening
environmental impact of a project by evaluation of alternatives and
selection of an environmentally sound option and  then by mitigation
of negative impacts through careful attention to  design details.
This Section of the EIS discusses the basic  components of the major
alternatives, their environmental impacts and the means by which
their impacts might be mitigated.

Sub-System Alternatives to the Metro Land
Recycling Proposal

     Stabilization--

     Some form of sludge stabilization is necessary before sewage
sludge can be applied to the land.   Stabilization involves the des-
truction of volatile matter in the sludge.  If sludge were applied
to the land unstabilized, odiferous conditions would result.

     The most commonly applied stabilization process is digestion,
either aerobic or anaerobic.  Based on many  years experience with
both digestion processes, Metro has selected the  latter for this
project, for the following reasons:  (1)  Anaerobic digestion is a
well-established process in the sewage treatment  technology field;
it has very low energy use requirements, whereas  aerobic digestion
requires considerable energy to supply air to the mixed sludge,
(2) The methane gas from anaerobic digestion can  be used to power
the digestion process and perhaps other units, and (3) Aerobic
sludge must be very well digested in order to avoid odor problems,
if the sludge becomes septic.

     An issue within the general choice of anaerobic digestion is
whether the process should be mesophilic (operating at temperatures
between 21°C and 39°C [70°F and 103°F]), or  thermophilic (operating
between 40°C and 54°C [104°F and 130°F]).  Thermophilic digestion
results in a better stabilized sludge that can be more easily de-
                                22

-------
watered.  Pathogen reductions are also reported to be more effective
with this process.  The principal negative aspects of thermophilic
digestion are the high additional costs for insulation and extra
heating.  Metro has decided to operate the system in the mesophilic
range.

     The actual range of choice for the digestion sub-systems is
extremely limited because EPA has already provided the Metro Dis-
trict with funds for anaerobic digesters.  EPA intends to evaluate
whether operation in the thermophilic range is desirable and within
reasonable cost limits, given the present design of the anaerobic
digesters.  Such a study can be performed in a future research
project.

     Transportation--

     The principal means of conveyance to a sludge drying/storage
facility in the Metro proposal is by pipeline.  Two pipes (25 and
30 cm [10 and 12 in.]) will carry the sludge,  with a pumping station
at the Central Plant and an intermediate pumping station.   A prelim-
inary design of the pipeline is available at the time of this writing,
and is discussed in more detail in Volume II,  Issue 1-2.  An earlier
description of the pipeline design is given in Volume III of the
facilities plan (Reference 55) and Section IV  of this EIS.   Generally,
EPA has not had any outstanding conceptual problems with the pipeline
design and, hence, no design alternatives are  offered here at this
time.

     Pipeline routes were also considered to be of minor importance.
CH2M-Hill considered two pipeline alternatives depending on the sites
for the distribution center.  Since Site B-2 is preferred, the route
along Irondale Road is the corresponding alternative for the pipe-
line.  Because the pipeline will  follow roadway right-of-ways, min-
imum environmental or social impact is expected.

     Sites for Drying and Distribution Center--

     The most controversial element in Metro's proposed system is
the location of the drying and distribution center.  When Metro first
proposed its spray irrigation system for sludge disposal in 1972,
the agricultural  areas to the northeast of Denver in Adams County
were felt to be best for this type of system.   At that time, it was
anticipated that dryland farming  would be the  principal user of the
sludge.  Six sites in this general area were evaluated (See Figure 2)
and a site near the present B-2,  although much larger in area, was
selected.

     Metro modified its land recycling proposal after meetings with

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         LEGEND

I	(ORIGINAL 6 SITES DESIGNATED
I	I IN PHASE  I REPORT
    REVISED POTENTIAL SITES
    (AGRIC. REUSE PROGRAM REPT.)

   [ALTERNATIVE SITES SELECTED
   IFOR FINAL CONSIDERATION
    (AGRIC. REUSE PREDESIGN REPT.)
                         KILOMETERS
                                                                                                  RECOMMENDED
                                                                                                     SITE
                                                          SLUDGE CONVEYANCE
                                                          PIPELINE TO SITE
                                           ROCKY

                                          MOUNTAIN

                                           ARSENAL
METRO
CENTRAL
PLANT
                                                                                      SOURCE^ CH2M HILL
                                                                  POTENTIAL  DRYING
                                                                         AND
                                                           DISTRIBUTION   CENTER  SITES

-------
local farmers who felt the loading rates for nutrients were too
high and that sludge directly applied to crops could have detri-
mental effects.  The 1973 study (Reference 5) recommended a drying
system whereby Metro would dry and store the sludge and make it
available to private farms.  A preliminary site evaluation for a
drying/processing/storage site was made in the same general area
of Adams County.  Eleven sites were evaluated, as shown in Figure 2.
A rating system was used to compare factors such as distance from
the Metro plant location with respect to markets, nearness to exist-
ing populations, soil suitability, number of homesites that would
have to be removed, visibility, elevation and land costs.  No eco-
logical factors were evaluated.  The evaluation led to the selec-
tion of three sites to be studied in more detail.  Figure 2 shows
the location of the original  six sites, the eleven sites under the
modified proposal and the three preferred sites—A, A-2 and B-2.
An environmental assessment of the three preferred sites was in-
cluded in the facilities plan and is reproduced in summary here in
Appendix G.

     The environmental assessment included an ecological  comparison
of the three sites and an archaeological investigation.   The archaeo-
logical investigation identified only one prehistoric  site of pos-
sible concern located on site A-2.  The ecological evaluation con-
cluded that sites A-2 and B-2 were floristically rich  areas with a
greater potential as wildlife habitat.  This was in large part due
to the presence of "relictual prairie areas" within the sites.   On
the basis of this information, Metro redefined the sites to avoid
the relictual prairies.   Detailed information on soil  conditions
and groundwater depth and quality is not available; thus these
factors, although important,  played only a minor role  in the eval-
uation.

     Metro's reasons for preferring site B-2 are described in
Chapter 6 of Volume III  of the facilities plan.  Environmentally,
only land-use considerations  were felt to be significantly dif-
ferent for each site.  Metro's overwhelming reason for selection
of the B-2 site was to stay as far away as possible from concen-
trated population areas  to avoid any further controversy.  This is
candidly admitted to be  the principal  reason for the selection
indicated in the facilities plan.   From the point of view of prox-
imity to markets and ease of  land acquisition, B-2 compares some-
what unfavorably with the other sites.  Figure 3 shows the relation-
ship of the three sites  to the expected principal users of the dried
sludge:  irrigation farms, sod farms and Denver park areas.  The
cost of construction and operation at the preferred site is also
estimated to be greater  than  at the other sites.  More information
is provided  on the relative merits of the three sites  on pages 92
and 93.

     On 8 May 1975, EPA, recognizing the controversial nature of


                               25

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                                                        FIGURE  3
                                                               '•
                                                               L
                                                          C;RY
                          IRRIGATED KARM AREAS
                          DRYLAND FARiM AREA
                                                       CH2M HILL
                                                DENVER TELEPHONE DIRECTRY
                       IN THE-DENVER
                                                    DENVER CITY MAP
                      NOtE: SOD FARMS-AND CIT'
                                 ' PARKS ARE APPROXIMATE LOCATIO
                           NOT TO SCALEGrefe***P SOURCE — U.S.G.S.)

                                  .nis f
 D -E R
                                                  METRO DENVER  SLUDGE
                                                  DRYING AND DISTRIBUTION
                                                  SIT^B-2    M      S
MOUNTAIN!
ARSENA
          >

F F E R S O  N
                                             PRESENT DISPOSAL SIT
                                             LO~WRY BOMBING RANGE
            '
    IRRIGATED AND  DRYLAND  FARMS,  SOD FARMS AND PARKS
          OF  THE DENVER  AREA IN RELATION TO THE
                   SLUDGE  DISTRIBUTION  SITE

-------
site selection, requested that the Metro District Board of Direc-
tors refrain from any actions to acquire the B-2 site until the
National Environmental Policy Act process was completed.   EPA feels
that the work done to date by the District and CH2M-Hill  represents
a reasonable effort at evaluating the sites considered so far; how-
ever, it is necessary to evaluate a wider range of sites, which have
been suggested by others.  For example, suggestions have been made
to use the Rocky Mountain Arsenal or the Lowry Bombing Range as a
drying/distribution site.  The facilities plan did not discuss
these possibilities.   Others have expressed a desire to know why
the site could not be located further north in Weld County or fur-
ther to the southeast in the vicinity of Lowry Bombing Range.

     The Metro District has indicated to EPA that the Defense De-
partment is opposed to any use of the Arsenal site for a  sludge
drying/distribution center.  At this point, it would be difficult
to say how favorable or unfavorable the Arsenal  would be  from a
soils or groundwater standpoint.  It is likely that unless the
Defense Department has developed a definite plan for the long-
range use of this facility, it would be reluctant to provide a por-
tion of the Arsenal on a piecemeal basis.  The site does  contain
significant wildlife and natural areas; it also contains  sites
where very toxic materials are stored.   It has recently been indi-
cated that the Army will have to exhaustively search any
part of the Arsenal that becomes open to public access for stored
poisons or weapons.  The Army Department also informed Metro that
no Arsenal land could be used until the nerve gas detoxification
program is completed in 1977.

     The Lowry Bombing Range would seem to be an ideal site for the
proposed sludge drying and distribution operation since Metro has
already been operating there.  However, the pipeline would have to
traverse a developed urban area with a  consequent increase in cost
and inconvenience.  A second consideration is that the elevation
of the Lowry site is about 150 m [500 ft] higher than the B-2
site which would approximately double the pumping costs.   In addi-
tion to the above disadvantages, there  is a rapidly developing
urban fringe in the southeastern Denver area within eight km [five
miles] of the site, which may cause a future land-use conflict.
There are also institutional  problems in acquiring the site.
Finally, the site is remote from most potential  markets,  as shown
on Figure 3.

     The principal way to avoid some of these conflicts is to obtain
some part of the Lowry Bombing Range that would not involve popula-
tion conflicts.  The institutional arrangement at present does not
allow an easy transfer of land within the range.  Metro District
utilizes a portion of the bombing range that has been leased to
                                27

-------
the City and County of Denver from the U.S.  Government.   Again,  it
is premature to develop any detailed comparison of the benefits  and
costs of this site unless indications could  be obtained from the
Defense Department that such land could potentially become available.
Were this the case, environmental and engineering information would
be required to evaluate the merits of sites  in the general vicinity.
Finally, it would appear that the site would be located at some  distance
from its potential markets, especially irrigated farms.   However, some
sod farms and Denver parks would perhaps be  somewhat closer than with
the B-2 site.  A more systematic comparison  of the preferred site, B-2
and Lowry, is found in Volume II, Issue IV-1.

     Lands to the north and west of the Platte River would generally
be unfavorable because of their proximity to populated areas.  Weld
County has already indicated a lack of interest in having the Metro
District locate their sludge distribution center within the county.
However, the presence of large amounts of irrigable lands and sod farms
makes this area attractive from a potential  market standpoint.   Lands
lie at lower elevations in this general  direction and would result in
lower pumping costs; land values are higher, however, and would  increase
the capital costs of the project.  Additional  discussions of site alter-
natives are presented in Volume II, Issue IV-1.

     The principal conclusions of EPA at this  time with  regard to site
locations would still  be the following:

     1.  There appears to be no site that is overwhelmingly superior
from an overall standpoint.
     2.  It is generally true (at least in the predominantly dryland
areas selected for site consideration) that  there are no significant
environmental issues involving vegetation or wildlife areas that could
not be avoided.
     3.  There is enough specific soils and  groundwater  data in  the
principal sites considered to indicate the beneficial and adverse
impacts of locating there.
     4.  Cost differentials between sites considered are small.   The
cost implications of some of the suggested sites are unknown.
     5.  A potential health risk may be associated with  actual  phys-
ical contact with the sludge.  However,  no significant health risk
exists as a result of the presence of members  of the public living,
working or merely visiting within the environs of the sludge drying
and distribution center as long as appropriate precautions are observed.
     6.  No matter which site is selected, there will be public  contro-
versy about the location of a facility of this kind.  A possible except-
ion could be one of the two Federal  areas--Lowry or the  Arsenal.
However, it does not appear that these areas will  be available.
     7.  Selection of an area that is reasonably close to market areas
could be important if trucking and sludge distribution costs are high.
However, with the range of potential  uses suggested for the dried
                                    28

-------
sludge--from sod farms to parklands--and with no definite information
about the preponderant users of the sludge, the optimal  location of
the site from this viewpoint is impossible to determine  at this  point.

     On the basis of information available to EPA,  site  B-2 is  accepted
by EPA as a "reasonable" site for sludge drying operations.  EPA feels
that the principle which was advanced in the discussion  of overall
alternatives pertains here as well:  once a "reasonable" choice  is  made,
it may be more important to evaluate a given site in detail and  suggest
design features to minimize effects on the natural  and human environment,
rather than try to select an optimum site.   Those factors which  could be
important from a locational  standpoint—distance from market,  soils,
groundwater conditions--while they may differ from a cost and  environ-
mental standpoint, are not significant enough to warrant a change of
site.  The reasons for this conclusion are found in the  discussion  under
Issue II-l , Volume II.

     Drying Basin Design Alternatives--

     Although there are a variety of design alternatives that  could
be of potential interest, only one at this point has been identified
as an environmental issue:  control of percolation waters from the
drying sludge that could result in groundwater contamination.

     At present, Metro is planning to take the supernatant from
anaerobic digestion that is usually treated at the wastewater  treat-
ment plant to the drying site.  In order to pump sludge  the distance
called for in this plan, a sludge of two to three percent solids is
necessary.  This involves the use of some of the supernatant which
normally runs at about one percent solids.   There is an  agricultural
advantage to pumping the supernatant with the sludge, since it con-
tains considerable amounts of nitrogen and phosphorus.

     A difficulty occurs when the sludge is applied to the drying
basins.  With the sludge in a liquid form, most of the free water
could percolate downward toward the water table.  Some water will
be lost to evaporation and some will stay in the dried sludge, but
most will move downward where it will likely result in degra-
dation of water quality to a degree that would make the  groundwater
unacceptable as a source of drinking water.  High nitrate concentra-
tions in drinking water can cause infant methemoglobinemia.  High
concentrations of dissolved solids will deteriorate groundwater
quality for both potable use and irrigation.

     Nitrate concentrations in the percolating water may be reduced
by bacterial  denitrification, a process that occurs under anaerobic
or least depressed dissolved oxygen conditions.  It is not known
                               29

-------
to what degree the process mignt occur1 in the drying basins.

     Metro believed that the likelihood of groundwater contamination
is low and proposes to monitor groundwater quality in order to
rapidly detect any deterioration.   If deterioration occurs, Metro
would install  a system to collect and treat percolating waters.
Alternatively, the drying basins could be lined.   EPA will  require
lining of the  drying basins to minimize leaching  to the groundwater
reservoir (see discussion in Volume II, Issue II-2).

     Alternative Design Capacities--

     The presently proposed system is designed to handle the sludge
loads from the Metro system projected to occur in 1985.  The facili-
ties plan indicates that the sludge loads will increase from 30,000
dry metric tons [33,000 tons] in 1974 to 55,000 dry metric  tons
[61,000 tons]  per year in the early 1980's.  These sludge quantities
are proportional to the wastewater flow volumes to be treated at the
Metro central  (and possibly satellite plant)  facilities.

     EPA has become sensitive to the possible secondary impact of
funding large  excess capacities for utilities such as sewage treat-
ment facilities.  The issue becomes especially critical in  air
quality priority areas such as Denver where water quality benefits
obtained from  providing treatment to future residents conflict with
the additional air quality degradation from the automotive  habits
of these newer residents.  EPA has funded a Section 208 study under
the Federal  Water Pollution Control Act Amendments of 1972  that  will
evaluate and guide population projections of facilities plans in the
Denver area.  The designated planning agency is the Denver  Regional
Council of Governments(DRCOG).  At present, DRCOG has been  working
with facilities planners to reduce the somewhat inflated earlier
individual Districts' population projections, to  conform with the
planned growth figure of 2.35 million persons in  the overall  Metro
area by the year 2000.  The latter goal  has been  adopted by the
DRCOG and approved by its members.

     EPA recognizes that concern of local  farmers that more land may
be needed in the future if present sizing of facilities proves to be
inadequate.

     The sludge loads projected by the Metro District and its
facilities planning consultant were developed as  far back as  the
1972 predesign study.  The values  presented in Volume III of the
facilities plan (Reference 55) on  page 4-1  are essentially  un-
changed from earlier projections.   The annual  rate of population
growth and hence growth in sludge  loads is  estimated to be  at
                                30

-------
5.5 percent per annum over the 1975-1935 period.   While this rate
did occur in the early seventies, current growth rates in the metro-
politan area are much closer to the recommended DRCOG growth rates
of 2 to 2.5 percent per annum.  Thus it appears that at least the
amount of excess capacity designed into the sludge handling system
may be beyond that necessary to support the aqueous stream treat-
ment facilities sized on the basis of the lower population projec-
tions.  The capacity of the drying bed design is  more thoroughly
evaluated in Volume II, Issues 11-12 and 11-13.

     There appears to be little direct correlation between the
addition of sludge handling capacity and induced  growth.   That is
to say, additional capacity will  not in itself induce individuals
to settle in the metropolitan Denver area.   However, EPA  has gener-
ally tried to coordinate its planning efforts for wastewater facil
ities with other plans in a given area for  consistency.   Because
additional capacity accommodates  additional  growth, it can still
contribute toward excessive growth that may be inconsistent with
other planning efforts.  In this  case, the  planning involves EPA's
own responsibilities under the Clean Air Act.  This issue has been
dealt with in more detail in the  Denver Regional  Overview EIS.

     "Excessive" capacity is also exceptionally difficult to define
in the case of the design of this project.   The only 'average1
figures available for design purposes are the projected sludge
loads.  Design values for most of the equipment are based on peak
flows that vary with the particular unit.  Anaerobic digestion
equipment is already under construction and therefore not really
an issue.  Pipeline sizing and pump sizing  is based on peak flows
for limited time periods.  These  can be related to an average flow,
but sizing requirements are not very sensitive to average changes.
The basin sizing is a function of the amounts of sludge and waste-
water to be dried, but two constraints apply.  First, an  average
value of wet sludge, about three  percent solids,  is assumed, but a
change in consistency to say 2.5  percent solids might be  more im-
portant than the actual solids amounts involved.   Secondly, the
actual time needed for drying in  the basins is not precisely known.
A year's time is assumed for design purposes, but longer  or shorter
drying times might be needed.  Construction of basin volume can be
staged to meet needs as demonstrated in the early years of the
project.  However,  due to inflated costs  associated with  later
development,  Metro District currently plans  to develop  the entire
240 hectares  (600 acres)  at this  time.

     The principal alternative to the present sizing may be to
limit the monies spent on the drying/storage system.  From the
point of view of secondary impacts, since control of the  size of
aqueous stream treatment facilities will accomplish control of the

-------
rate of wastewater utility growth, control for sludge management
facilities may not be necessary.

Sub-System Alternatives to the Present
Lowry Disposal System

     In a sense, sub-system alternatives to a null alternative are
a contradiction in terms.  However, the null alternative may be
improved by certain changes which can be regarded as mitigation
measures or sub-alternatives.  This may be important because, al-
though the proposed system appears most advantageous, some modified
version of the existing system is the most likely option in the
event that the proposed system proves infeasible.

     Variations to the present Lowry system presented here are
tentative; they have had neither the benefit of a cost evaluation
nor  an engineering and environmental evaluation.  EPA simply sug-
gests these alternatives at this time as somewhat less preferable
alternatives  that may have to be evaluated in more detail if funding
is not available for the more capital-intensive land recycling system
now  proposed  by Metro.  In the interim, some form of land recycling
system may be used if the sludge drying project is delayed.  Metro
has  stated that incineration would be the preferred sludge disposal
system if the sludge drying project is delayed.

     Sludge Conditioning and Digestion--

     It has already been mentioned that Metro has received a Federal
grant to construct facilities at the Central Plant to anaerobically
digest all Metro sludges.  Part of the problem at the Lowry site
has  been the deposition of large amounts of unstabilized sludge con-
taining large quantities of chemicals used for conditioning.  These
chemicals include ferric chloride, lime and polymers.  While they
have not been considered to be deleterious to the soil, it would be
preferable to keep them out of the sludge if possible.

     The performance of anaerobic digesters on the raw and waste
activated sludges now treated at Metro must be considered an un-
known area at present.  Anaerobic digestion can improve the dewater-
ing characteristics of sludges (resulting in less chemicals for
conditioning).  However, digestion of secondary waste activated sludge
may not perform in the same fashion.  It might be expected that odor
and chemical-related problems at the Lowry site will be reduced by
the measures  already under construction.  Conversion of the diges-
ters to the thermophilic mode might further improve sludge dewater-
ing characteristics.

     Transport--

     CH2M-Hill indicated in its evaluation of the present alterna-
tive that  it  might  become more economical  for Metro to purchase its
                              32

-------
own fleet of trucks to haul  sludge to Lowry;  Metro recently did this.
A pipeline would have been a reasonable alternative only if Metro had
been guaranteed long-term use of the Lowry site,  which was  not the case.

     The Lowry Site--

     As discussed previously, use of the Lowry Bombing Range is contin-
gent upon City and County of Denver approval  or possibly through obtain-
ing a long-term lease for some part of the bombing range.   The present
operation is predominantly a landspreading operation where  sludge is
being loaded onto the land at annual rates considered highly excessive
for good sludge recycling practices on dryland.  As long as the area
involved is small, the use of a "sacrifice area"  is reasonable.  Denver
plans to eventually use this area as a landfill.   Some plant species,
including wheat, will grow on the site even with  the high  loading rates.
The sacrifice would generally be in the potential  contamination of
surface water supplies and food chain hazards posed by grazing animals.
A modification might involve restriction of grazing animals from direct
contact with sludge-amended areas.

     If grazing were to be permitted but controlled, additional  forage
growth might be provided for cattle.  This could  be expensive for Metro
since large land areas would be involved.  The fact that many separate
owners are involved would make acquisition of large areas  of the bombing
range difficult.

     A second alternative might be to develop some modified type of dry-
ing/windrowing operation to store anaerobically digested-vacuum filtered
sludge at Lowry for sale or distribution to local  farmers,  sod farms,
etc.  This would involve a substantial change of  the use of the bombing
range that would need approval by the local managers.   The  alternative
suggested here differs from the site alternative  consideration for the
Metro proposed system in that minimal capital investment for new facili-
ties would be required.  Metro could store some sludge and  landspread
the remainder until a market developed.  Such a system would need large
amounts of land available in order to remain  flexible.  The operating
costs for such a system would remain high since vacuum filters and truck
hauling (the largest part of present operation costs)  would still be re-
quired.  The key to success  of such an alternative is the  economical de-
watering of the bulk of Metro's sludge (secondary waste-activated sludge)
Tests by Metro indicate that this sludge does not dewater  well after
anaerobic digestion.
                                33

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-------
w
 h
HI
it

-------
     This section contains a description of the
general setting for the project.  The environ-
mental and social areas covered are ones that
might reasonably be expected to affect or be
affected by this project or its alternatives.
     Because sludge applications could occur
almost anywhere in the Metropolitan Denver area,
it is necessary to broaden the focus of study to
include the overall environment.  EPA is partic-
ularly concerned about impacts that could occur
after the sludge has left the drying and distri-
bution site and is finally applied to the land.
Therefore, the environmental settings for actual
use sites (Denver parkland, sod farms, mine-
spoil reclamation sites, irrigated and dryland
farms) are described to the extent that there
are recognizable differences in the way the im-
pacts might occur at different sites and with
different uses of the land.  These site-specific
descriptions are found in Appendix E, which also
contains a description of the Lowry Bombing range
since that site is considered a basic alternative
to the project proposed.

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                          SECTION III

                      ENVIRONMENTAL SETTING
     The study area is comprised of several sites, which are
 highly  diverse in natural and artificial characteristics.  The
 service area of the wastewater management system and the City
 parks are  in a highly urbanized setting; most of the proposed
 sludge  reuse sites are rural, and che mine spoil reclamation
 sites are  extremely remote and isolated from public access.
 While most potential land application sites are within 50 km [30
 miles]  of  the proposed sludge drying and distribution site and
 to the  east of the site, the mines are generally mucn farther
 away, to the west.

     The environmental setting for the proposed action comprises
 the entire  Denver region.  The general discussion of the region
 in this Section is supplemented in Appendix E by descriptions of
 environmental settings in five specific sites, providing examples
 of possible agricultural  reuses of anaerobically digested, air-
 dried sludge.  For each category of reuse potential, a represen-
 tative  site was selected—mainly by virtue of the interest ex-
 pressed by  the owner and/or operator of the site in the use of
 sludge  in  the operation—for detailed investigation of the envi-
 ronmental  setting and the probable impacts.

     The representative sites serve to pinpoint the impacts which
 can be expected from sludge application to all  areas of similar
 characteristics.   For those areas which have very different char-
 acteristics, the impacts  may vary widely.   Therefore, it is impor-
 tant that,  prior to drawing generalizations from assessments made
 here, one compare the environmental  characteristics of the pro-
 posed sites with those of the representative sites.  Clearly,
 some extrapolations and approximations will be possible in many
 cases;  but, in some cases, it may be necessary to reevaluate the
 impacts  and adjust application rates and management conditions to
match the requirements  of the particular site.

     A  discussion of the  environmental setting at the Lowry Bombing
Range sludge disposal  area is presented, also in Appendix E, to
serve as a  basis  for the  evaluation  of impacts  of the "no-action,"
present  alternative.
                              35

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CLIMATE

     The Metropolitan Denver region,  lying on the western edge of
the Great Plains,  near the foothills  of the Rocky Mountains, is
an area of transition from the climate of the plains to the cli-
mate of the foothills.  The region has a high-elevation continen-
tal climate that has been characterized as semi-arid,  Steppe-type
clime (Reference 9).

Temperature

     Temperatures are generally moderate, with a mean  annual tem-
perature of 11.3°C [52.3°F].  Ranges  in extremes have  been recorded
from -34°C [-30°F] to 40°C [|05°F].   Mean monthly temperatures for
Denver are presented in Table 3.

Precipitation

     Monthly precipitation data tor Denver are shown in  Table  3,
Generalized precipitation patterns for the Denver region and sur-
rounding areas are shown in Figure 4.  Precipitation is relatively
light (average annual depth:  31 cm [12 in.]), with a  large pro-
portion of the rain falling during the growing season  from April
to September.  Much of this summer precipitation occurs as a re-
sult of thunderstorm activity.  Table 4 shows the seasonal occur-
rence of thunderstorms.  Heavy thunderstorms in  the eastern foot-
hills and plains area occasionally cause damaging flash floods.
Maximum expected precipitation frequencies as flood-producing
events are also shown in Table 4, together with  relative humidity
data.  The generally  low relative humidity is a  major  factor in
the areal potential evapotranspiration rate of 610 mm  [24 in.]
per year (Reference 9).  This amount  is twice the average precipi-
tation and is an indication of the aridity of the area.  Periods
of drought one to two years in length are fairly common in portions
of Adams County (Reference 10).

     Snowfall is generally not heavy, with most  snow occurring
between November and April.  Mean monthly snowfall data for Denver
are shown in Table 6.  Extensive flooding caused by snowmelt in
the mountains occurs only at times when there has been either a
heavy accumulation of snow or a sudden increase  in high-elevation
temperatures (Reference 11).  The growing season is approximately
five to six months long, from April  to September, when the temper-
ature does not fall below freezing.

Wind

     Wind data for the Denver airport are presented in Table 5.
                               36

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         Table 3.   TEMPERATURE,  PRECIPITATION, SNOW  AND FREEZE  DATA, DENVER (WB CITY)

Mean
Temperature
°C
[°F]
Precipitation
mm
[in.]
Snowfall
cm
[in.]
Freeze
Jan

1.2
34.1

8.6
0.34

15.7
6.2

Feb

1.8
35.3

16.3
0.64

23.6
9.3

Mar

3.6
38.5

20.6
0.81

29.7
11.7

Apr

8.8
47.8

36.8
1.45

27.2
10.7

May

14.7
58.4

65.0
".56

3.0
1.2

Jun Jul

20.8 23.6
69.4 74.5

25.9 37.3
1.02 1.47

0.3 T
0.1 T

Aug Sep

22.9 18.4
73.2 65.1

30.5 19.3
1.20 0.76

T 3.3
T 1.3

Oct

12.1
53.7

24.4
0.96

8.1
3.2

Nov

4.7
40.5

14.2
0.56

17.5
6.9

Dec

2.6
36.6

10.7
0.42

17.0
6.7

Annual

11.3
52.3

309.6
12.19

145.5
57.3

  No.  days with     25     22     21     10      1      +a    0      0     +     5     18     24      126
    temperature
    1  0°C [32°F]
Freeze threshold
°C [
0 [
-2.2 [
-4.4 [
-6.7 [
-8.9 [
temperature
°F ]
32 ]
28 ]
24 ]
20 ]
16 ]
Mean number of days between
spring occurrence and first
166
192
212
231
239
date of last
fall occurrence





a+ - 0 > .5
Source:  Decennial Census of United States Climate.

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 • SELECTED REPORTING WEATHER STATION
  - ISOHYET, mm (inches)

SOURCE  WATER QUALITY MANAGEMENT PLAN REPORT
  GENERALIZED  PRECIPITATION
       PATTERN IN THE
  METROPOLITAN DENVER REGION

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Table  4.  MAXIMUM PRECIPITATION FREQUENCY, THUNDERSTORM AND RELATIVE HUMIDITY DATA, DENVER

Maximum amounts of precipitation to be expected within
Frequency, 6-hour total
years mm [in.]
2 36 to 41 [ 1.4 to 1.6 ]
5 46 to 51 [ 1.8 to 2.0 ]
10 56 to 64 [ 2.2 to 2.5 ]
25 71 to 76 [ 2.8 to 3.0 ]
50 76 to 86 [ 3.0 to 3.4 ]
100 86 to 97 [ 3.4 to 3.8 ]
io Thunderstorms, mean number
different time periods (frequencies)
24-hour total
mm [ in . ]
46 to 56 [ 1.8 to 2.2 ]
61 to 71 [ 2.4 to 2.8 ]
66 to 86 [ 2.6 to 3.4 ]
86 to 97 [ 3.4 to 3.8 ]
97 to 117 [ 3.8 to 4.6 ]
107 to 127 [ 4.2 to 5.0 ]
of days
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
0 +a + 1 6 10 12 8 4
1 + 0 43
Relative humidity
percent percent of
time
0 to 29 27
30 to 49 28
50 to 69 23
70 to 79 10
80 to 89 9
90 to 100 4
The symbol + indicates a range between 0 and .5.
Source: Water Quality Management Plan, Denver Regional Council of Governments.

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Table 5. WIND DATA, DENVER (WB AIRPORT)
Wind speed Jan
Mean hourly speed
mps 4.3
[mph] 9.6
Prevailing direction S
Fastest speed
mps 18
[mph] 41
Direction NW
O Frequencies of wind speed
0-1 mps [ 0 - 3 mph] 9.6
2-3 mps [4-7 mph] 25.6
4 - 5 mps [ 8 - 12 mph] 34.4
6 - 7 mps [13 - 18 mph] 24.2
8-10 mps [19 - 24 mph] 4.6
11 - 13 mps [25 - 31 mph] 1.4
14 - 16 mps [32-38 mph] 0.2
17 - 20 mps [39 - 46 mph] 0
t 21 mps [ t 47 mph] 0
+ •= < 0.5 percent.
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

4.5 4,8 4.7 4.4 4.4 4.0 3.7 3.7 3.8 4.3 4.5
10.1 10.7 10.6 9.9 9.8 9.0 8.3 8.3 8.5 9.7 10.0
SSSSSSSSSSS

22 24 23 19 21 20 18 21 18 18 23
49 53 52 43 47 44 40 47 40 40 51
NW NW SE NW S SE 6W NW SW NE NE
percent
9.2 8.6 8.0 9.1 9.8 11.6 14.3 13.1 13.4 10.1 10.2
25.1 23.2 23.5 24.8 25.2 28.2 27.6 30.4 33.5 26.9 25.8
33.0 33.5 31.4 33.4 34.0 35.4 35.6 34.1 33.0 33.6 34.2
24.1 22.7 24.3 24.2 23.0 20.5 19.3 18.9 16.6 23.1 22.2
5.8 7.0 7.9 6.3 3.4 2.6 2.9 2.9 2.7 4.4 5.2
2.4 3.6 3.9 1.6 1.5 C.8 0.7 0.6 0.6 1.4 1.8
0.4 1.1 0.7 0.4 0.3 0.1 +a 0.1 0.3 0.4 0.5
+ 0.2 0.2 + + + 0 0 0.1 + 0.2
00 + 00 + 00000

Annual
mean

4.2
9.5
S

24
53
NW

10.6
25.7








Source: Water Quality Management Plan, Denver Regional Council of Governments.

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Air  quality  is adversely affected  by  low wind speeds and special
atmospheric  gradients.  Air  pollution  in Denver can occur when wind
speed  is  1 mps [3 mphj or  less.  A wind blowing at 2 mps [4 mph]
will usually clear polluted  air out of the city in about two hours
(Reference 9).  At the airport (see Table 5), wind speeds of 1 mps
[3 mph] or less occur 10.6 percent of the time; winds blowing at
3 mps  [7  mphj or less occur  36.3 percent of the time.

     Chinook winds periodically blow from the mountains with great
turbulence.  This phenomenon results from high-elevation westerly
winds  being  warmed in their  rapid  descent through a shallow layer
of cool air  covering the plains.   Sudden rises in temperature ac-
companying these gusty winds exert a moderating influence on winter
temperatures.

Regional  Climatic Variations

     Additional climatic data are  presented for the six weather
stations  whose locations are snown in Figure 4.  Climatological
data for  the city of Denver was presented previously In Table 3.
Information  from this table  is applicable to the city's parks.
Data provided by the Denver Airport and Fort Lupton weather sta-
tions  (Table 6) are applicable to  sod farms, irrigated farms and
dryland farms.   The Cherry Creek Dam and Byers weather stations
(Table 7) are at the western and eastern extremes, respectively,
of the Lowry Bombing Range.  Data  from these stations also pertain
to some of the sod farms south of  the Denver Metropolitan Area.
These five weather stations fall within the Denver region, an area
tnat is generally uniform climatically, although there are some lo-
cal variations.

     The  sixth selected weather station, at Berthoud Pass, is lo-
cated on  the crest of the Continental Divide and experiences a dif-
ferent climate altogether.  Discussion is deferred to a separate
heading under Mine Spoil Site in  Appendix E,  as  data  from this sta-
tion are applicable to that area only.

TOPOGRAPHY

     The  Metropolitan Denver region is located along the western
periphery of the high plains of Colorado, which slope gently up-
ward for  almost 300 km [186 miles] from the eastern border of the
state to  the base of the foothills of the Rocky Mountains.  The
relief can be characterized  as rolling prairie, with some hills and
ridges intersected by nearly flat  f loodplains along watercourses.
Much of the  land currently under cultivation, mostly to the east
and northeast of Denver, is  nearly flat and level.  Most of the
land in Adams and Arapahoe counties has a slope equal to or less
                               41

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         Table  6.   TEMPERATURE, PRECIPITATION,  SNOW AND FREEZE DATA,
                      DENVER  (WB AIRPORT)  AND FORT LUPTON
Mean
Temperature
Denver AP
•c
[•F]
Ft. Lupton
•c
[•F]
Precipitation
Denver AP
mm
[in.]
Ft. Lupton
mm
[in.]
Snowfall
Denver AP
cm
[in.]
Ft. Lupton
cm
[In.]
Freeze
No. days with
temperature
< O'C [32*F]
Denver AP
Ft. Lupton
Jan


-0.3
31.5

-1,2
29.8


13.0
0.51

12.2
0,48


19.8
7.8

21.8
8.6




29
30
Feb Mar Apr


0.7 2.9 8.1
33.3 37,3 46,6

-0.3 3.1 9,3
31.4 37.5 48,8


23.4 34.5 45.5
0.92 1,36 1.79

14.5 23.4 26.7
0.57 0.92 1,05


27.9 38.9 30.2
11.0 15.3 11.9

18.5 12.2 6.4
7.3 4.8 2.5




26 25 13
27 28 15
Freeze threshold
temperature






•c
0
-2.2
-4.4
-6.7
-8.9
t 'F ]
32
28
24
20
16
Hay Jun Jul Aug Sep Oct


14.1 20,2 23,1 22.3 17,8 11.3
57.4 68,3 73,5 72,2 64,0 52,4

14,9 20.5 23,4 22.2 17,6 10.9
58,8 68.9 74.1 72.0 63.6 51,7


77,0 25.4 50.8 39.1 23.6 29.7
3.03 1.00 2,00 1,54 0.93 1.17

54.1 16,8 32.5 36.6 23.6 24.6
2.13 0.66 1,28 1.44 0.93 0.97


3.3 0.3 T 0.3 4.3 9.4
1.3 0.1 T 0.1 1.7 3.7

0.8 0 0 0 0 0.3
0.3 0 0 0 0 0.1




1 +" 0 0 + 7
2 + 00 1 13
Nov Dec


3.7 0.9
38,6 33.7

3,1 -0.2
37.5 31.6


20.3 14.7
0.80 0.58

11.4 10.7
0.45 0.42


23.4 19.3
9.2 7.6

5.3 8.6
2.1 3.4




23 29
27 30
Annual


10.4
50,7

10.3
50.5


397.0
15.63

287.0
11.30


177.0
69.7

73.9
29.1




153
173
Mean number of days between date of last
spring occurrence and first fall occurrence
Denver AP Ft, Lupton
160 148
184 175
198 196
222 213
230 226












 + - 0 > .5
Source:  Decennial Census of United States Climate.
                                       42

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       Table 7.   TEMPERATURE,  PRECIPITATION,  SNOW  AND FREEZE  DATA,
                          CHERRY  CREEK DAM AND  BYERS
Mean
Temperature
Cherry Cr. Dn
•c
[•F]
Byers
•c
[•F]
Precipitation
Cherry Cr. Dan
mi
[in.]
Byera
na
[In.]
Snowfall
Cherry Cr. Dan
cm
[In.]
Byers
cm
[In.]
Freeze
No. days with
temperature
i O'C [32*F]
Cherry Cr. Dam
Byers
Jan

-0,3
31,5

-1.1
30.1


7.9
0.31

11.2
0.44

22.1
8.7

7.9


29
30
Feb Mar Apr

0,6 2,8 8,1
33.1 37.1 46.6

0.2 2.6 7.9
32.4 36.6 46.2


16.3 20.1 41.4
0.64 0.79 1.63

13.0 22.1 34.0
0.51 0.87 1.34

21.6 28.7 22.9
8.5 11.3 9.0

8.9 10.6 7.6


27 28 17
27 28 17
freeze threshold
temperature






•c
0
-2.2
-4.4
-6.7
-8.9
I -F ]
32
28
24
20
16
May Jun Jul Aug Sep

13.5 19,7 21.9 21.3 17.3
56,3 67,4 71,5 70,3 63,2

14.0 20.1 23,0 22.1 17.8
57,2 68.2 73.4 71.8 64.1


78.7 28.4 43.7 30.7 18.3
3.10 1.12 1.72 1.21 0.72

65.8 30.7 58.2 40.9 20.8
2.59 1.21 2.29 1.61 0.82

3.0 0 0 0 1.5
1.2 0 0 0 0.6

1.2 T T T 0.9


3 +a 0 0 1
2 + 001
Oct Hov Dec

11.2 3.7 0.7
52,2 38.6 33,3

11.2 3.1 0.1
52,1 37.6 32.1


26.9 13.7 11.2
1.06 0.54 0.44

21.8 14.0 8.9
0.86 0.55 0.35

16,0 15.7 22.9
6,3 6.2 9.0

1.9 7.3 5.0


10 26 29
9 25 30
Annual

10.1
50,1

10.1
50.2


337.3
13.28

341.4
13,44

154.4
60.8
130.3
51.3


170
169
Mean nuuber of days between a-te of last
spring occurrence and first fall occurrence
Cherry Creek Ban
135
155
190
211
222
Byers
138
168
183
204
222






 + • 0 ' .5
Source:  Decennial Census of United States Climate; Cliiutologlcal Data for the U.S.: Colorado,
                                       43

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than nine percent, as shown below (References 10,14).

                       Percent of total land area in county
         County	   <. 5% slope           S  9% slope

        Adams                63.7                75.5

        Arapahoe             55.7                73.0

     Elevation in the eastern plains section of Colorado ranges
from 1,020 m [3,350 ft] at the lowest point in the state (where
the Arkansas River crosses the border) to about 1,600 m [5,280 ftj
around the Denver area.  West of Denver, the plains give way abruptly
to the foothills, with elevations of 2,100 m to 2,750 m [6,890 ft
to 9,025 ft].  Typical elevations for sites within the study area
are shown in Table 8.  General elevations for the region are shown
in Figure 5.


   Table 8.  TYPICAL ELEVATIONS FOR SITES WITHIN THE STUDY AREA

Study site
City park
Sod farm
Sod farm
Sod farm, irrigated farm,
dryland farm
Irrigated farm
Dryland farm
Lowry Bombing Range
Lowry Bombing Range
Nearby city or
weather station
Denver
Littleton
Brighton
Fort Lupton
Platteville
Watkins
Cherry Creek Dam
Byers
E
m
1,609
1,634
1,518
1,497
1 ,469
1,685
1,721
1,584
levation
[ft]
[ 5,280 ]
[ 5,362 ]
[ 4,982 ]
[ 4,914 ]
[ 4,820 ]
[ 5,530 ]
[ 5,649 ]
[ 5,200 ]
     Many rivers and creeks flow out of the mountains and foothills,
mostly in a south-to-north direction through the Denver region, in
the Platte Drainage watershed.   The South Platte River and Cherry
Creek flow through the heart of Denver.

     Separate discussion of the topography of the mine spoil  site
is presented under that heading in  Appendix E,

GEOLOGY

     The Metropolitan Denver area is located in the Denver Basin
                              44

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/        JO U
/     -v* ^
-'-•"•
                                                   A  R  A   ...P   A   H   O   E
                                                       CONTOUR INTERVAL VARIABLE
  ,^>^
                                                            TOPOGRAPHY
                                                                 OF
                                                           PROJECT  AREA

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near its boundary with the Front Range.   The strata of the Denver
Basin dip slightly toward the east,  while the strata of the Front
Range have a steep dip.   The two geologic regions are separated by
a zone of sharp,  almost vertical folds.   Thus the dip of a forma-
tion several kilometers west of Denver would be high (>90 percent),
while the dip of  the same formation  several  kilometers east of
Denver would be slight (
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                             FIGURE  6
              GEOLOGIC  MAP

      OF AREAS IN THE VICINITY OF

     I    METROPOLITAN DENVER


        FOR EXPLANATION OF SYMBOLS
        SEE THE FOLLOWING 2 PAGES

        SOURCE^ GENERALIZED SURFICIAL GEOLOGIC MAP
              OF THE DENVER AREA,COLORADO
1,1

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                                                                                                            FIGURE   6  (cont.)

                                                 EXPLANATION
                                  Loess, eolian sand, colluvium
                                        undifferentiated
                             Wind-deposited silt, sand: sand and cobbles on
                              foothill slopes.  Silt and sand deposits 0-40
                              feet thick, sand and cobbles as much  as 10
                              feet thick.  Saturated sand and gravel may
                              yield 1 to 5 gpm to wells
                             Post-Piney Creek alluvium, Piney Creek
                               Alluvium, pre-Piney  Creek  alluvium,
                               Broadway and Louviers Alluviums
                             Sand, grai-el. silt,  and clay.  Deposits range
                              from 0-60 feet thick.  Saturated sand and
                              gravel yield as much as 2.000 gpm  to wells.
                              Chemical quality of water generally good
                                Slocum, Verdos, and Rocky Flats
                                           Alluviums
                            Reddish-brou-n silty clay, silt,  sand, pebble
                              lenses,  and loess.  Coarse gravel and sand
                              and  volcanic ash  underlie  high   terrace
                              remnants. Unit may exceed 50 feet in thick-
                              ness  locally.   Yields 1 to 5  gpm  to u-ells
                              irhere materials are saturated.  Grarel and
                              sand near Burr Lake yield as much as 200
                              gpm  to trellx.    Water generally  of poor
                              quality, contains  excessive concentrations
                              of fluoride
                            Castf? Rock Conglomerate, upper pn-t
                              of  Dawson   Formation,  and   upper
                              part of Denver Formation
                            Gray, brown, tan. and greenish-gray shale.
                              clay, and siltstone, and numerous lenticular
                              beda of  light-colored  conglomerate  and
                              sandstone.    A ndesitic  mudflow breccias
                              common in ridnity of Table  Mountains
                              and Green  Mountain.  Beds of sandy lime-
                              stone, lignite, coal, and carbonaceous shale
                              are common.  Unit ranges in thickness from
                              300 to HOO feet  Yields less  than 25 gpm
                              to wells in  most of the area, but as much as
                              150 gpm in southeast part.  Locally water
                              contains high   concentrations of dissolved
                              solids,  iron, radioactive constituents,  and
                              hydrogen sulfide gas
                             Lower part of Dawson Formation, Arap-
                               ahoe Formation,  and  lower part  of
                               Denver Formation
                             White  to yelloir  arkosic sandstone and con-
                              glomerate interbedded  ii'ith  gray,  green,
                              and  red  shale and  clayatone.   Contains
                              alluvial and  mudflote  andesitic detritus.
                              Conglomerate heds  thicken in  upper part,
                              and are thicker nnd  more numerous toirard
                              souihtt it part of the basin.  Unit ranges
                              from $00 to 1.^00 feet thick   Yields to veils
                              average 100 (/pm and are »» much as400gpm.
                              Water generally of good quality
                                Upper part of Laramie Formation
                            Blue-gray silty shale, thin  silty  sandstone.
                              limestone, and coal; coal thickest  in loirer
                              part.  Yields 1  to  2 gpm of poor quality
                              water to »?//».   Water contains hydrogen
                              sulftde,  iron, and methane
    Volcanic rocks
Lava flows on Table Moun-
  tains, vent source  near
  Ralston Creek, and ash
  flow  tuffs  near Castle
  Rock.   Ash flaie  tuffs
  underlie  Castle   Rock
  Conglomerate.      Not
  known  to be saturated
fr-
  tt
  U
Geological  map  of   areas  in  the  vicinity  of  Metropolitan  Denver  (cont'd)
                                                              48

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                                                                                                        FIGURE   6   (cont.)
                                    •      •' •
                       Lower part of La ramie Formation and
                               Fox Hills Sandstone
                     Medium-grained   sandstone   (60-80  fttt),
                       orerlying and grading into fiHfr grained
                       thin-bedded  sandstone  interbedded  tritk
                       siltstone and thale (JO-100 feet).   Fiue
                       grained  quartette  sandstone,  siltstone,
                       skate 16Q-1SQ ftet).  Wells  pr net ruling en-
                       fire unit generally yield 100 gpm and a fete
                       yield a* muck at 400 gpm.   At places ipater
                       may  cantata  objectionable  amounts  of
                       methane, hydrogen smlfide.  iron,  and fluo-
                       ride
                         Pierre Shale, Niobrara Formation,
                                and Ben ton Shale
                     Gran, blue, and btack thole, sandy shale, and
                       thin limestone;  some tUty sands tome, ben-
                       ton ite seams, chalky  marl, and limestone.
                       Units may total S.OOOfeet in, Denver Basin.
                       Fractured zones in shale may yield 1 to 2
                       gpm of poor quality trater to well*
                                  Dakota Group
                     Upper 100 feet gray-irhite f\ne- to medium
                       grained sandstone, thin-bedded to massive.
                       Middle 150 feet  dark-gray silty carbona-
                       «ow  shale,  contain*  refractory  clay.
                       Lower 60 feet gray coarse sandstone, locally
                       conglomeratic,  crossbedded.     Sandstone
                       yields 5 to 30 gpm to  trtlls  near outcrop.
                       Water contains excess ire iron locally
                        Sedimentary rocks undifferentiated
                     Includes Upper Jurasxic Morrison  (300 feet}
                       and Ralston Creek (110 fevt) Forma (ions.
                       Triassicf?) and Permian Lykins Formation
                       (+00 feet); Permian Lyons Sandstone UW
                      feet}, and Loirrr  Permian  and Upper and
                       Middle Pennttyli-aman FouHtain  Forma-
                       tion (1,200 fett).  Lyons Sandstone, shotcn
                       by stipple, generally yields 5 to 10 gpm, and
                       as much  as 80 gpm  to icells near outcrop
                       area*. Fountain Formation sandy conglom-
                       erate may yield 1  to o gpm  to veils  Water
                       may contain excess ire iron and fluoride
                         Igneous and metamorphic rocks
                                undifferentiated
                     Granite,  gneiss, schist,  quartzitf,  pegmatite,
                       guartz  iti'iis, intrusive igneous rocA'x,  Yield
                       1 to 5 gpm of generally good quality  water
                       to wells that tap fractures or weathered
                       zones
                                     Contact
                                      Fault
                                                                    y
                                                                  zui
Geological  map  of   areas   in  the  vicinity  of  Metropolitan  Denver   (cont'd)
                                                            49

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Table 9. STRATIGRAPHIC UNITS AND THEIR WATER-BEARING PROPERTIES IN THE VICINITY OF DENVER
System
Quaternary
Tertiary
Cretaceous
Series
Recent and
Pleistocene
Pleistocene
Paleocene
Upper
Cretaceous
Subdivision
Dune sand
Slope wash
Valley-fill
deposits
Upland
deposits
Denver
formation
«
o
^
ti
(0
C
0
m
3
OJ
Q
Arapahoe
formation
La ramie
formation
Fox Hills
sandstone
ness
m3
0-15
0-9
0 - 40
0-5
0-60
0 - 185
0 - 185
0-75


Fine to medium sand and minor amounts of clay
and silt.
Poorly sorted clay, silt, sand and gravel;
grades into valley-fill deposits.
Interbedded c lay , silt, sand and gravel that con-
tains some cobbles and boulders and beds of al-
tered volcanic ash. Underlies the flood plain
and terraces on the South Platte River valley and
underlie floor of Beebe Draw and Box Elder Creek
Valley. Include some slope wash along the edges
of Beebe Draw and Box Elder Valley.
Deposits of sand, gravel, conglomerate and vol-
canic ash that mantle the bedrock in the upland
areas . Inc lude col luvium , r 'siduum and remnants

Varicolored clay, soft shale and siltstone con-
taining much carbonaceous material, interbedded
with lenticular poorly sorted generally moder-
ately indurated yellowish-brown sandstone and
conglomerate. Locally contains andesitic mate-
rial and beds of weathered volcanic ash and ben-
tonitic clay.
Upper part (120 m): Soft predominantly blue or
gray sandy to clayey shale and clay and a few
lenticular beds of sandstone.
Lower part (60 m) : White to yellow sand, gravel
and conglomerate, variously indurated and in-
cluding minor amounts of shale and clay.
Upper part (120 m) : Chiefly olive-gray silty
stone; contains numerous carbonaceous clay
beds and lignitic seams.
Lower part (60 m) : At top, a sequence of thin
beds of blue -gray silty shale, sands tone and
lignitic material. At bottom several relatively
thin beds of sandstone, fairly thick beds of
subb i t urn i nous coal , and several other thinner
sandstone units that locally coalesce with the
thick basal sandstone .
Uniformly bedded buff to pale-yellow friable
to black silty shale and silty sandstone. About
15-18 m of massive sandstone at top.
Water-bearing
properties
Serves mainly as medium for recharge from pre-
cipitation. Locally yields snail quantit.dS of
water to domestic and strc1-: vplls.
Yields small to moderate
domestic and stock wells
we I 1 s .
quantities of water to
and to a fei* Irrigation
The most important aquifer in the report area and
the source of groundwater for nearly all the
large-capacity wells. Yield moderate to large
quantities of water to nany dones tic, stock,
Irrigation, public-supply and industrial wells ,
Topographically high and


Yields small quantities
of water to domestic
and stock wells in the
southern part of the

Yields small to moder-
to domestic, stock, pub-
lic-supply and industri-
al wells in the southern
part of the report area.
well drained. Not a


The Dawscn arkose,
stratigraphically
equivalent to part
cf the Denver and
Arapahoe formations,
yields small to
moderate quant it ies
of vater to domestic.
stccV: , public- supply
and industrial wells
part of the report
area .
Some of the sandstone units in the upper part
yield small to moderate quantities of water to
domestic, stock and industrial wells through-
out the report area.
The basal sandstones In the lower part yield
small to moderate quantities of water to domes-
tic, stocV, publ ic -supply and Indus trial wells
throughout the area.
Yields small to moderate quantities of water to
domestic , stock, public-supply and industrial
wells throughout the report area.
Water yield , ^
liters per seer *• d "
0.1 - 0.3
125
125
0.3 - 13
1-9
1 - 9
6-25
upper: 0.1
lower: 6-25
6-25
al meter - 3.281 feet
1 liter per second - 15.85 gallons per minute

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The Dawson Arkose and Denver formations, unlike the Arapahoe,  have
poor groundwater yield and serve as an aquitard.   The upper parts
of these formations outcrop in southeastern Arapahoe County.

     Most of the surface of the study area is covered by unconsoli-
dated Quaternary deposits which range in thickness from 0 to  20 m
[0 to 66 ft].

     Early in the Quaternary, before the Wisconsin glaciation,  de-
bris from the Front Range formed large deltas in  the Denver Basin.
The deltas included layers of silt, sand and gravel as well as  some
volcanic ash.  The pre-Wisconsin Quaternary deposits are designated
as Qsi on the geologic map presented on Figure 6.   The water  yield
of these deosits is small and generally of poor quality.

     During the Wisconsin glaciation, the Denver  Basin, particularly
the western portion near the city of Denver, served as an outwash
area for the glaciers in the mountains to the west.  The torrential
flow of the outwash streams eroded the underlying  deltas and  depos-
ited as much as 20 m L66 ft] of sand, gravel, silt and clay over
them.  Thus outcrops of the Qsr formation represent topographic
highs which were not destroyed by the outwash streams.  The allu-
vium from the glacier forms an aquifer with good  water quality  and
yield as high as 125 Ips [2,000 gpm].  The Wisconsin alluvium is
depicted as Qpl on the geologic map.  Strong winds capable of car-
rying heavy bedloads also characterize outwash areas.  The winds
shift the unconsolidated alluvium.  These eolian  deposits, depicted
as Qs on the geologic map, cover more of the surface than does  any
other deposit in the study area.  They range in thickness to  about
three meters [10 ft] and have a small yield (about 0.3 Ips [5 gpm]).

     The proposed sludge reuse sites, except for  the irrigated  farms
in Weld County, are plotted on the geologic map.   In general, water-
bearing formations used intensively as a groundwater source  are
less suitable for sludge disposal.  Many other factors are impor-
tant, however; the geologic character of an area  cannot be the  only
criterion for site selection.

Earthquakes

     During the history of Denver, only one earthquake of damaging
proportions has been reported near Denver.  In the mid-1960's,  how-
ever, several mild earthquakes occurred.  These earthquakes centered
around the Rocky Mountain Arsenal well, where millions of gallons
of contaminated water were injected into the highly faulted pre-
Cambrian bedrock (Reference 19).  In the future,  it is unlikely that
major earthquakes will  occur in the Denver area.   It will probably
not be necessary to incorporate earthquake lateral force considera-

-------
tions into design features  for the sludge disposal  systems.

SOILS

     Soils in the study area  have been  surveyed by  the U.S.  Soil
Conservation Service (SCS)  in recent years.   Final  reports on de-
tailed soil surveys have been published for  Adams County (Refer-
ence 10) and Arapahoe County  (Reference 14).   As for Weld County,
a detailed survey has been  completed, but no published report is
available.  Official soil  series descriptions and interpretations
for the Weld County soils  which may be  subjected to sludge appli-
cation were obtained from  the SCS field office in Greeley (Refer-
ence 22).

     Soils in most of the  potential areas of sludge application
are for the most part calcareous.  They fall  within about 20 dis-
tinct associations with characteristics typical of  their geographic
setting.  The topography,  drainage, texture  and parent materials
of these soils are presented  in Appendix B and are  shown graph-
ically on Figure 7.  Specific characteristics of soils in each
typical site under investigation are presented separately under
the discussion of the environmental setting  of the  particular site
in Appendix E.  The published soil surveys are indispensable as a
tool tor planning sludge use  in agriculture  on a regional basis.
However, for application on a specific  field, this  information
should be augmented with additional field investigations by soil
scientists and/or agronomists.

     An important soil property which should be carefully consid-
ered in sludge application  is the micro-community inhabiting the
soil.  Microbial populations  living in  the soil include viruses,
bacteria, actinomycetes, fungi, algae and protozoa.  Soil aeration,
acidity, temperature, moisture content, organic matter, inorganic
nutrient supply and other  parameters determine the  relative popula-
tions of the various microbial groups.   Some of the important func-
tions of soil microorganisms, insofar as sludge application is con-
cerned, are (.1) uptake of  nutrient elements  and their conversion
to organic matter, (2) production of growth  factors stimulating
other organisms, (3) breakdown of complex organic molecules to
simpler, more readily usable  forms, (4) production  of antibiotics
which inhibit some organisms, (5) symbiotic  relationships between
certain organisms, (6) predation and parasitism between organisms,
(7) nitrogen fixation from  the atmosphere under certain conditions
and (8) production of enzymes which promote  many different biochem-
ical reactions.
                               52

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                                                                     FIGURE  7
27
SOIL ASSOCIATIONS IN
 VICINITY OF DENVER
                                        SOURCE : WATER QUALITY MANAGEMENT PLAN
                                              U.S. SOIL CONSERVATION SERVICE

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 WATER

     The Metropolitan Denver area is water-deficient.  It is
 through large-scale transmountain diversions that the demands of
 the  area are  balanced with imported supplies.  Intricate and long-
 standing water rights and allocations dictate ownership and use of
 the  existing  and developed supplies.  Municipalities, irrigated
 farms, industries, recreation projects, fisheries and stream aes-
 thetic requirements impose cumulative ana sometimes conflicting
 demands upon  quality and quantity of water in the study area.

     Even  though sludge-handling is an important phase of the to-
 tal  water  management picture in the region, it neither demands nor
 supplies significant quantities of water to the total system.  How-
 ever, sludge  must be viewed as a potential threat to the quality
 of waters,  both in the ground and on the surface.  Thus, the dis-
 cussion that  follows is not aimed at being a comprehensive eluci-
 dation of  the water supplies of the region; rather, it is meant to
 provide the basic background for the impact statements which are
 presented  in  the succeeding sections.

 Groundwater

     The water-bearing properties of strata underlying the study
 area are presented in Table 9 under Geology.  Valley fill deposits
 of Recent  and Pleistocene series, ranging in thickness from 0 to
 40 m [0 to  125 ft] comprise the most important aquifers in the
 area.  These  aquifers underlie various thicknesses of dune sand
 and  slope wash.  The valley fill deposits yield moderate to large
 quantities  of water to the domestic, stock, irrigation, public
 supply and  industrial wells.  Depth to water table ranges from a
 meter [a few  feet] to 30 n [100 ft].  Detailed data on groundwater
 occurrence  and movement are not available.

     Below  this aquifer formation,  strata with generally low permeability
 Uquitards) separate the upper aquifer from the important Laramie-
 rox  Hills aquifer, which lies at considerable depths (90 m [300
 ft]  at Piatteville;  520 m [1,700 ft] at Lowry Bombing Range; 400 m
 LI,300 ft]  at the proposed sludge drying and distribution center)
 frc'n the land surface.   Wells penetrating the full thickness of
 this aquifer  can yield  from 6 to 60  liters per second [100 to 900
 gallons per minute].   The Denver-Dawson-Arapahoe formations, which
 lie above the Fox Hills  aquifer, do  have interbedded layers  of sand-
 stone which yield  low to moderate quantities of water to domestic and
 stock wells in the region

     Water quality in  the upper aquifer is generally good,  although
scarcity  of data  preclude adequate  evaluation.   The Laramie-Fox
Hills aquifer  water  quality  varies  from one place to another.   Near
its  recharge sites,  to  the  south and east, the quality is  superior
to that at  some  other locations, where  objectionable amounts  of

                               54

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methane, hydrogen sulfide, Iron and fluorides are encountered.

Surface Water

     Even though the study area, is interlaced with many of the trib-
utaries of the South Platte River, most of the creeks in the east-
ern part of the study area are dry during most parts of the year.
Some streambeds are wet only on rare occasions:  once every several
years.  Streams draining the western parts of the Metropolitan
Denver area flow during most of the year and include St. Vrain
Creek, Boulder Creek, Coal Creek, Big Dry Creek, Clear Creek, Sand
Creek, Cherry Creek, Bear Creek, Plum Creek and many smaller creeks.
Many diversion structures across streams on the western slopes of
the Continental Divide have been constructed to transfer water
through the mountains to the eastern slopes and to discharge the
water in the above-mentioned streams.  These water diversions, res-
ervoirs built on tne creeks themselves, groundwater withdrawals,
irrigation diversions and their return flows have drastically
changed natural flow patterns in these streams.  A discussion of
the quantities and quality of water in the streams, as well as a
model of stream water quality in the Denver Basin, are presented in
the recently published Water Quality Management Plan (Reference 9).

     During the period 1966 through 1970, annual stream flow into
the Metropolitan Denver area totaled 450 million cubic meters
[185,600 cfsd], 95 percent of which was diverted from the streams.
Fully 38 percent of the streamflow into the Denver Area in that
period was wastewater treatment plant effluents from upstream areas,
and over half of the water leaving the metropolitan area was gen-
erated within the area (Reference 9J.

     The lakes in and around the metropolitan area are of special
significance.  Most of the lakes were used for irrigation before
the area became heavily urbanized.  Most are now used for recreation
and as centers of real estate development.  There are some 50 lakes
with surface areas greater than 10 hectares [25 acres], with a total
combined area of 3,686 hectares [9,108 acres] and a total shoreline
of 185 km [115 miles].  The three largest lakes are:

                                    Surface area
Lake
Barr
Stand! ey
Chatfield
hectares
708
492
465
[ acres J
[ 1,750 ]
[ 1,216 ]
[ 1,149 ]
There are another 113 lakes of 2 to 10 hectare [5 to 25 acre] sur-
face area, with a total  area of 526 hectares [1,300 acres] and a
shoreline of 110 km (.68 miles] (.Reference 23).
                               55

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     Uater quality in the lakes  Has  deteriorated progressively
over the past decades with chemical  and biological  pollutants
emanating from the increasingly  heavy use and development of the
surrounding area.   A recent investigation of the present quality
of waters in these lakes, including  parameters such as salinity,
pH, transparency and coliform bacteria, is reported by the U.S.
Geological Survey in graphic format  (Reference 23).

     Site B-2 straddles a low ridge  separating the  upper drainage
areas of Lost and Horse Creeks.   Both are intermittent prairie
streams.  Horse Creek drains into Horse Creek Reservoir, which is
used primarily for irrigation.  Lost Creek flows into Prospect
Valley, an intensively irrigated area in Weld County.

BIOLOGY

     Tne Metropolitan Denver region  is part of the  high plains area
that extends from the Great Plains to the foothills of the Rocky
Mountains.  The elevation of the study area ranges  from 1,400 m to
1,800 m [4,600 ft to 6,000 ft],  placing it within the Upper Sonoran
life zone (Reference 24).  This  zone begins at the  Transition zone
of the foothills of the Rocky Mountains and extends beyond the
eastern border of Colorado.  The growth and distribution of vegeta-
tion is  largely dependent upon climate, relief, substrate, fire and
the occurrence of human activities such as grazing  and agriculture.
With an average annual precipitation rate of only 30 to 40 cm [12
to 16 in.], water availability is the chief limiting factor leading
to the low growth of grasses and forbs on the plains.

     Prior to settlement, the plains supported a mixed prairie which
was made up primarily of perennial bunchgrasses.  Short grasses such
as blue grama and buffalo grass  dominated on drier  sites, and taller
grasses (western wheatgrass ana  little bluestem) occurred on sites
with higher moisture, such as along  eastern stream  courses and to-
ward the mountains to the west.   Prior to settlement, a very complex
mosaic of steppe communities existed in the Denver  area in response
to the numerous soils (Reference 9).  Under natural conditions, the
three major plant communities probably were (1) upland prairie or
short-grass plains, (2) meadow and (3) cottonwood-willow.  The
plains did not support tree growth except along the watercourses,
which were fringed with cottonwoods  and willows.  Dense thickets of
wild plum and chokecherry, with  scattered clumps of hackberry and
box elder, occurred sometimes in gulches and arroyos (Reference 24).
The original  distribution of natural vegetation in  the Denver region
(Reference 25) is shown in Figure 8.

     Hunan activities, mainly in the form of cultivation and live-
stock grazing, have altered the  natural vegetation  considerably.
Sixty-five percent of Adams County is currently under cultivation,
and 35 percent of Arapahoe County is similarly utilized.  The remain-
ing uncultivated lands are generally used for pasture and range or
urban and residential  purposes (References 10,14).


                                 56

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      NATURAL  VEGETATION OF COLORADO

LEGEND

1-GRASSLANDS OF THE PLAINS-Blue gramma is the dominant
    grass.
2-GRASSLANDS OF THE PLAINS-Blue grama, sand dropseed,three-
    awn, sand reed, bluestem,  sideoats grama, and yucca.
3-GRASSLANDS OF THE PLAINS-San reed, bluestem, sand drop-
    seed and sand sage  on  sandhills.
4-GRASSLANDS OF THE FOOTHILLS-Wheatgrass, needlegrass, sand
    reed,  bluestem, and blue grama mixed with areas of
    shrub  and occasional ponderosa pine.
5-WOODLANDS OF THE  LOWER MOUNTAINS-With stands of ponder-
    osa  pine (and often Gambel Oak) with Douglas-fir, blue
    spruce, white fir and  occasional aspin mixed with
    fescue, muhly,  bluegrass,  shrubs and forbs.
6-WOODLANDS AND GRASSLANDS OF  SUBALPINE AREAS-With stands
    of spruce and fir or lodgepole pine, or aspen.
    Thurber's fescue grassland parks intermingle with
    timbered areas.
7-GRASSLANDS AND MEADOWS OF ALPINE REGIONS ABOVE TIMBERLINE
    With sedges, grass,  willow, birch and forbs.

SOURCE :  SOIL CONSERVATION  SERVICE , OCTOBER 1972
                                          GOLDEN
                                                                                 METROPOLITAN  v
                                                                                 DENVER SEWAGE \
                                                                                 DISPOSAL DISTRICT*
                                                                                  MDSDD-I
                                                                                                         0   5   10   15
                                                                                                           35S55!
                                                                                                           KILOMETERS

                                                                                                      0      5     10     1
                                                                                                                                         a
                                                                                                                                         c
                                                                                                                                         3)
                                                                                                                                         m
                                                                                                                                         oo

-------
     The present biotic  communities  can be calssified according to
the following general  vegetation units:  (1)  Cultivated, (2) Uplands
Vegetation,  (3)  Riparian and Aquatic and (4)  Urban/Residential.  A
listing of common plants and animals in these units is given in
Appendix C.
                                 ~*r*-  v
                     ' ^»
     w   - —_-
                         "". -.%...
                        -  '.jii'V'
                              •5
                       -j.  -             ..  .•<*jfrt

                TYPICAL  UPLAND  VEGETATION  UNIT  WITH
                COTTONWOOD  TREES  INDICATING  SEASONAL
                            RIPARIAN  ZONE


 Cultivated  Lands Unit

      Cultivated vegetation  includes  sod farms,  irrigated  farms  and
 dry  farms.  Thousands of hectares of the  plains are devoted  to  irri-
 gated farming along the South  Platte River, and to dryland farming
 on adjoining uplands.   In  some areas, such  as  in  Arapahoe County,
 irrigated farmland has decreased significantly in the  past 30 years
 because of  community development and the  diversion of  water  from
 the  South Platte River for  domestic  purposes.

      Agricultural lands are typically cultivated  as monoculture
 units.  The allocation of  large parcels of  land to only a few plant
                                58

-------
 species  leads to a simplified environment with low animal diversity.
 Animal populations are generally characterized by numerous small
 burrowing rodents, seed-eating birds and a few wide-ranging preda-
 tor species.  Although a monoculture yields little variety in habi-
 tat,  the crops provide an important food source for wildlife.  This
 is particularly significant in migratory bird wintering areas near
 Riparian-Aquatic habitats.  The stubble, fence rows and unharvested
 remains  are often vital to wildlife for sustenance and cover during
 the winter months.  Such a situation exists at Site B-2; a small
 area  of  relictual prairie on the southeast end offers additional
 habitat  to wild!ife.

 Uplands  Unit

      Uplands vegetation includes pasture and range lands whose spe-
 cies  composition varies with soil character and past use.  Current
 Upland vegetation on uncultivated soils is typically a weedy grass
 type  that has suffered from too heavy grazing.  The two major short-
 grass species of the mixed prairie, blue grama and buffalograss, are
 hardy perennials that can withstand heavy grazing since they grow
 close to the ground and form a cover of bunchy sod.  Both of these
 grasses  increase when tall-grass associations are overgrazed.  When
 overgrazing occurs on the short-grass units, the sod mats weaken and
 are invaded by annual grasses and annual and perennial weeds (Refer-
 ence  26).  Good examples of the tall-grass prairies and mixed-grass
 prairies are now becoming scarce in the Denver region (Reference 9).

      Wildlife patterns have also changed in response to prairie suc-
 cession and alterations in land use.  Formerly abundant animals such
 as the prairie dog, American buffalo and pronghorn antelope have be-
 come  limited in distribution because of human intervention and changes
 in the short-grass prairie habitat.  The black-footed ferret, which
 had a Historic range dependent upon that of the prairie dog, is con-
 sidered an endangered species (Reference 27).  The greater and the
 lesser prairie chicken are examples of species which are endangered
 by the diminishing size of the mixed prairie habitat.  The Uplands
 vegetation area is now primarily inhabited by jackrabbits, rodents
 and many reptiles which are tolerant to change and can coexist with
 human activities.

 Riparian and Aquatic Unit

     Riparian and Aquatic units occur along major watercourses, such
as the South Platte River and Cherry Creek.  Associated with most
watercourses are wide, nearly flat floodplains.  Many of the creeks
 in the study area seldom flow for more than two weeks, generally in
March and April  and during heavy storms in the summer.  Most of the
suitable terrace soils along streams have been cultivated, and other
Kiparian zone sites, which have not been utilized for gravel mining
or occupied by industrial  sites, have been grazed for 100 or more
years.  In bottom lands where there is no current grazing, there is
                               59

-------
a greater variability in vegetative cover [Reference 9).

     Colorado's semiarid Front Range Urban Corridor has many lakes
of high value.   In the past,  they were used to store water for irri-
gation and domestic uses, with occasional  use for recreational acti-
vities.  As a result of rapid suburban development, their importance
at present is as recreational areas and centers of real estate de-
velopment.  The major lakes of the Denver region are Cherry Creek
Lake, Cnatfield Lake, Marston Lake, Standley Lake and Barr Lake.
The network of smaller lakes, ponds and reservoirs also plays an  im-
portant role in the natural ecosystem.

     Riparian and Aquatic units include some of the most important
wildlife habitat in the area.  The Platte River Valley and its trib-
utaries produce one-third of Colorado's annual water fowl crop and
provide winter habitat for tens of thousands of migrant birds.  The
trees of the floodplain supply nesting and roosting areas for large
numbers of birds of many kinds, including small  numbers of bald
eagles.  In the metropolitan area, most marshlands have been elimi-
nated, although many floodplain oxbow lakes, ponds and marshes per-
sist in the more rural areas.  Marshes provide a valuable wildlife
habitat, serving as home for amphibians and aquatic mammals, and  as
nesting and feeding grounds for waterfowl.   The dense vegetation
provides excellent winter storm cover for pheasants, rabbits and
many other kinds of wildlife (Reference 9).

     The larger lakes of the Denver region are stocked with gamefish
such as brown trout and rainbow trout.  All lakes generally contain
several species of roughfish, which provide important food supply
for wildlife as well as maintaining the aquatic ecosystem.   Lakes
and ponds that are less disturbed by human activities comprise the
necessary aquatic habitat for migrant waterfowl.

Urban/Residential Unit

     The original site of Denver was a virgin prairie traversed by
two tree-lined streamcourses.  With urban growth and development, a
large variety of non-native shrubs and trees have been introduced
into the Denver area.  A vast City park system interlaces the city,
providing a wealth of greenery, open space and artificial lakes and
ponds.  Denver has more than 100 parks covering more than 1,100 ha
[2,800 acres],  as shown on Figure 3,

     The present vegetation is a cross-section of many plant types
from midwestern and eastern United States.   Parks and residential
areas are lined with shade ana fruit trees, ornamental shrubs and
flower gardens.  Many large areas are landscaped with grasses and
other ground covers for recreational  use.   This wealth of foliage
                                60

-------
har attracted several midwestern birds, such as the red-eyed vireo
and bronzed grackle, unknown within the area before 1910 (Reference
28).  Thus, in the past century, the urbanization of Denver has re-
sulted in the creation of woodland, shrub and aquatic habitats in
formerly barren areas.

     A summary of the major biotic units, with their characteristic
plant and animal species, is shown in Figure 9.

Rare and Endangered Species

     The Federal Register for rare or endangered plant species was
reviewed for the State of Colorado (Reference 34).  No plant species
were considered to be threatened in the Denver Region.

     The Nongame and Endangered Species Conservation Act (Reference
35) for the State of Colorado is consistent with Title 50,  Part 17
of the U.S. Conservation of Endangered Species Act.  The Colorado
Division of Wildlife further protects several wildlife species not
covered by the Federal Conservation Act.  The Wildlife Division has
recognized the stress on wildlife caused by a growing population and
changing land use, and endeavors to protect wildlife habitat as well
as endangered wildlife species.  Animals protected by State and Fed-
eral regulations (Reference 34) that may occur within the study area
include the black-footed ferret, peregrine falcon, white pelican,
and river otter.

     Black-Footed Ferret--

     The black-footed ferret (Musteia nigripe) occurs within snort-
grass prairies.  Its historic range coincides closely with that of
its prey species, the prairie dog.   The population has been dras-
tically reduced and its range decreased due to changing land uses
and programs to control or eliminate prairie dogs.  Scattered re-
ports of the black-footed ferret indicate nearly statewide distri-
bution, with tendencies toward the eastern grasslands.  The lands
within the study area are largely cultivated or grazed and probably
represent a marginal habitat for the black-footed ferret.

     Peregrine Falcon—

     Colorado has two recognized subspecies of the peregrine falcon:
a winter nesting resident, the American peregrine (Faico peregrinus
anatum), and the arctic peregrine (Faico p. tundrius), a migratory
visitor during the spring and fall  (Reference 36).  The resident
subspecies is of greater concern within the Rocky Mountain area.  Hu-
man activities such as road-building, forest- and sagebrush-clearing,
game-hunting and outdoor recreation have deteriorated the quality of
                               61

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en
ro
                 Unit
             Cultivated
               Lands
Uplands
  Vegetation
                            Location and examples
               Flat or rolling farm-
                 lands ;  east and
                 north of Denver.
                 Major portions of
                 Weld and Adams
                 counties.

               Rural dwellings;
                 farm buildings.
                            Steep dirt  banks;
                              along ditches  and
                              seasonal  streams.
Arid plains region;
  typically found in
  eastern Adams and
  Arapahoe counties.
                            Bluffs  and  cliffs
                                       Characteristic vegetation
                        Alfalfa,  corn, sugar beet,
                          vegetables, wheat, oats,
                          barley, rye, forage sor-
                          ghum.
                                                   Sunflower, prickly let-
                                                     tuce, Russian thistle,
                                                     tansy mustard, dande-
                                                     lion, garden escapes.
Blue grama grass,  buffalo
  grass, western wheat-
  grass, little bluestem,
  Junegrass,  needle-and-
  thread, red three-awn,
  locoweed,  sunflower,
  aster, fanweed,  prickly
  pear, plantain,  yucca.
                                                   Characteristic birds
                           Brewer's blackbird,
                             western vesper
                             sparrow, ring-
                             necked pheasant,
                             western meadow-
                             lark, lark bunt-
                             ing.
                           Barn swallow, Say's
                             phoebe, housefinch.
                                                                  Bank swallow,  king-
                                                                    fisher.
Burrowing owl,  desert
  horned lark,  moun-
  tain plover,  turkey
  vulture, red-tailed
  hawk.
                                                                               Cliff swallow,  prairie
                                                                                 falcon,  ferruginous
                                                                                 roughleg hawk.
                                                                                        Characteristic animals
                      Meadow vole, pocket
                        gopher, ground
                        squirrel, harvest
                        mouse, western jump-
                        ing mouse, weasel,
                        bullsnake, garter
                        snake.
                      House mouse, raccoon,
                        feral cat, spade-
                        foot toad, garter
                        snake.
                      Fence lizard.
Jackrabbit, prairie
  vole, pocket mouse,
  Ord kangaroo rat,
  coyote, pronghorn
  antelope, prairie
  rattlesnake, bull-
  snake, central
  plains milksnake,
  sagebrush lizard,
  horned lisard.
                           Summary  of biotic  community characteristics, Metropolitan Denver area
                                                                                                                            CT>
                                                                                                                            C
                                                                                                                                         m

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Unit
Riparian and
Aquatic






















Urban/Resi-
dential







Location and examples
Cottonwoods ; along
rivers and streams
such as South
Platte River and
Cherry Creek.



Shrubbery; along
streams and creeks
and intermittently
between stretches
of cottonwood.
Lakes and ponds ;
storage reservoirs
such as Barr Lake
and ponds through-
out farming region
and urban areas.
Marsh areas and
swamps ; along the
floodplain of
South Platte
River.
Greater Denver Metro-
politan area; in-
cludes residential
environs , City
parks and other
recreational faci-
lities.


Characteristic vegetation
Plains cottonwood, box
elder, willow, narrow
leaf cottonwood.





Chokecherry, wild plum,
buf f aloberry , hawthorn,
rabbitbrush. willow.


Willow, rushes, cattail,
sedge, salt grass and
aquatic plants.



Salt grass, bulrush and
other rushes, sedge.



Ornamental shrubs , flow-
ers , lawn-type grasses,
soft maple, elm, weep-
ing willow, Carolina &
Lombardy poplar, ash
sycamore, Norway pine,
Russian olive, and
several varieties of
fruit trees.
Characteristic birds
Red-headed woodpeck-
er, Rocky Mountain
screech owl, Swain-
son's hawk, crow,
Bullock's oriole,
kingbird, western
mockingbird, white-
rumped shrike.
Black-headed gros-
beak, catbird,
brown thrasher,
yellow warbler,
song sparrow.
Grebe, gull, tern,
goose, green heron,
mallard, pintail,
shoveler and other
ducks, shorebirds.

Rail, coot, heron,
bittern, duck, red-
winged blackbird,
yellowthroat .

Robin, starling,
mockingbird, house
sparrow, black-
capped chickadee,
chipping sparrow,
rock dove, red-eyed
vireo, bronzed
grackle.

Characteristic animals
Raccoon, fox squirrel,
shrew, weasel, bat,
barred tiger sala-
mander, yellow-
bellied racer, gar-
ter snake.


Striped skunk, rac-
coon, eastern wood-
rat , deer mouse ,
yellow-bellied ra-
cer, garter snake.
Snapping turtle, box
turtle, boreal
chorus frog, carp,
brown . trout , chub,
minnow, shiner, cat-
fish.
Muskrat, coyote, bull-
frog, leopard frog,
boreal chorus frog,
garter snake, nor-
thern watersnake.
House mouse, Norway
rat, pocket gopher,
feral cat.






Source:  References  28, 29, 30, 31, 32 and  33.
        Summary of biotic  community characteristics,  Metropolitan Denver  area (contined)

-------
the environment for this species.   The peregrine falcon requires
high cliffs for nesting sites and  a food supply of small birds.
Accurate information about breeding pairs has been difficult to
obtain.  However, the plains area  may still  have some value as a
feeding range for this species ^Reference 36).

     White Pelican—

     The white pelican (peiicanus  erythrorhynchos] is common in
portions of the United States and  is not considered endangered on
a national basis.  Within Colorado, it is presently considered en-
dangered as a nesting summer resident.  White pelicans may be found
at several reservoirs along the South Platte River drainage; how-
ever, they nest and rear young only at Riverside Reservoir, outside
of the study area.

     River Otter—

     The river otter (mtra canadensis)  formerly ranged over many
of the rivers and lakes of North America.  Due  to hunting and human
encroachment, otters have been eliminated or their numbers reduced
over much of their range.  However, the  river otter is not consid-
ered endangered on a national basis.  The otter has probably always
been rare in Colorado ^Reference 36).  Scattered sightings have
been reported in the South Platte  River  drainage in Weld County,
and it is unlikely that a breeding population is present.  Because
this species is usually limited to wilderness areas, it is unlikely
that it could ever exist in any numbers  in the  study area.  Most of
the streams and lakes are influenced by  adjacent homes, industry or
other incompatible human developments.

AIR QUALITY

     The project study area is located within Air Quality Control
Region 2 (AQCR2)—Metropolitan Denver (see Figure 10).  Air pollu-
tion control  priorities for this region  have been determined by the
Colorado Air Pollution Control  Division  and  the U.S. Environmental
Protection Agency on the basis of  the following five considerations:

     1.  existing air quality data
     2.  population status and trends
     3.  degree and type of industrialization (emission inventory)
     4.  amount of vehicular traffic
     5.  topographic and meteorologic factors

     On the basis of these criteria, pollutants are given priority
rankings of l,  II or III, with Priority  I as the most severe.  Par-
ticulates, carbon monoxide and reactive  hydrocarbons and oxidants
                               64

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                                                              LOGAN
                                                                        i SEOGWICK
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                                                                         PHILLIPS
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I _________

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                                           SDNivDENVER M t I K U

                                                   DE¥VER
                  ^PTTKIN"
                   GUNNISON\


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        I


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                                                                 COMANCHE
                                        S_AN_ ISABEL
                                       CUSTER"   TT'X \ \
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                          'RIO GRANDE  ,'ALAMOSA
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                            SAN  LUIS
                           	i
                            /-/•tklC IrtC   '— -  —f
                                                                    KILOMETERS

                                                                     10   20   30
                                              JIMAS   Y A
MONTEZUMA
I    I CID J /         ARCHULETA    I CONEJOS


j        /FOUR  CORNERS  K


SOURCE- COLORADO DEPARTMENT OF HEALTH, ~
AIR POLLUTION CONTROL COMMISSION.
                                                             STATE AIR POLLUTION CONTROL
                                                             DESIGNATED AREAS
                    COLORADO AIR QUALITY CONTROL REGIONS

-------
are ranked Priority I and sulfur dioxides and nitrogen oxides are
ranked Priority III; Priority II ranking has not been assigned to
any pollutant (Reference 37).  These pollutants mentioned are gen-
erally related to human activity and thus decrease markedly as one
leaves the urbanized regions.  Carbon monoxide in AQCR2 is due al-
most entirely to vehicular traffic.   It is currently felt that com-
pliance with Federal carbon monoxide standards will not be achieved
in AQCR2 by the 31 May 1977 target date (Reference 37).  Reduction
in vehicular traffic will be needed  to achieve the standard, par-
ticularly during the winter months when frequent inversions occur.
The very small traffic flows in rural Adams County preclude carbon
monoxide pollution problems.

     Ozone, produced as a product of reactions between oxides of
nitrogen and reactive hydrocarbons in the presence of sunlight, is
one of the photochemical oxidants which cause the unpleasant effects
of "smog."  Federal standards for ozone levels are commonly exceeded
in AQCR2.  Control of these levels is achieved by reducing the pri-
mary pollutants, hydrocarbons and NOX.  In order to meet Federal
standards, hydrocarbon emissions must be reduced by about 80 percent
(110,000 metric tons/yr [120,000 tons/yr]) by 31 May 1977.  It is
not expected that this reduction will be attained.  In the rural
setting of the project area, however, ozone concentrations are not
as high as in urban areas, although  sporadic violations may occur.

     The Federal primary and secondary standards for particulates
are exceeded in A(jCR2.  The primary standard is set to protect the
public health at 75 yg/m3, geometric mean.  Levels in the urban
Denver area are generally over 100 yg/m3, diminishing to two-thirds
this  level in outlying areas.  Contaminants previously discussed
are monitored at only six stations in the Metropolitan Denver area.
The particulate concentrations are sampled more widely (22 stations).
The monitoring station nearest the project is in Brighton, about
16 km [10 milesj northwest of the sludge drying sites.  In 1974, a
year of average meteorological conditions, the annual arithmetic
mean particulate level was 103 vig/m3.  The State standard is 70
vig/m3.  While rural areas may experience high particulate levels
due to agricultural operations, these levels are generally lower
than those of urban areas.  For this reason, particulate levels
around the project site are not presently considered significant.

     Wind transport of pollutants into or away from the project area
can be surmised from wind speed and  direction, as described on Fig-
ure 11.  The data used in this figure, from Stapleton Airport on
the northeast edge of Denver, are representative of wind patterns
in the study area.  The average wind speed and direction is 15 km
[9.5 miles] per hour from the south.  Infrequent strong, destructive
winds generally come from the northwest.
                               66

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                                                      FIGURE  II
                                 N
                   NNW
     NNE
         NW
                NE
WNW
   i5°/c
W
WSW
                       ENE
                       ESE
         SW
                SE
                   SSW
SOURCE; BASED ON 10 YEARS OF DATA
(DECENNIAL CENSUS), 1951 - I960, BY
JOHN BENCI, DEPT OF ATMOSPHERIC
SCIENCE, COLORADO STATE UNIVERSITY
(REFERENCE 38).
     SSE
     LEGEND

SYMBOL       WIND SPEED
        1.8-5.4 mps (4- 12 mph )
        5.4-11.0 mps (13-24 mph)
         > 11.0 mps (> 24 mph)
    ANNUAL FREQUENCIES OF WINDS OF VARIOUS  VELOCITIES
          AT STAPLETON AIRPORT, DENVER COLORADO
                               67

-------
     The average annual  temperature is about 10°C [50°F], with the
highest temperatures usually occurring in July and the lowest in
January.  Daily differences tn temperature extremes (high-low) are
usually about 17°C [30°F] in most months (Reference 8).  The summer
temperature conditions are favorable for smog formation, while win-
ter conditions cause frequent inversions.  The mean morning mixing
height is relatively low in Denver, averaging only about 60 m [200
ft].  This limits the dilution of air pollutants.  However, this
low mixing height rises quickly in the afternoon due to the sun's
heat.  During the summer months, the afternoon mean mixing height
is about 1,000 m [3,300 ft].

     Precipitation is relatively mild, averaging about 41 cm [16
in.] per year, as discussed under Climate.   These dry conditions
cause additional particulate emission problems.

Odor

     Background odors generally associated with the study area are
those normally associated with urban, suburban and farming communi-
ties.  The petroleum refineries east of Denver emit characteristic
odors which are especially noticeable at distant locations during
calm periods when mixing with the upper air layers is minimal.
Other odorous materials are those commonly associated with farming
operations in the area.   For example, a chicken farm may heat-
pressurize chicken manure, producing very offensive odors.  These
fertilizer and manure odors are generally accepted as part of normal
farm operations and are therefore tolerated.

     Odors are regulated by Odor Emission Regulation No.  2 of the
Colorado Department of Health, Air Pollution Control Commission
(Reference 37).  This regulation sets forth three types of odor
limits.  For residential or commercial areas, odorous substances
must be undetectable from beyond the property line of the emission
source after being diluted with seven volumes of odor-free air.  A
scentometer allows this dilution and measurement to be taken.  For
other areas, a dilution of 15 volumes of odor-free air must render
the odor undetectable.  A special  regulation exempts agricultural
and manufacturing processes, provided the best practicable methods
have been employed to control odors.  For all odor sources, however,
there is an upper limit which must not be exceeded:  they must not
be detectable after having been diluted with 127 volumes of odor-
free air.

     Because of the potential for emission of odorous air contami-
nants from the drying and distribution center, an emission permit
from the Air Pollution Control Division of the Colorado Department
of Health will be required.
                               68

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ARCHAEOLOGY AND HISTORY

     Transient and sedentary Indian tribes once associated with
eastern Colorado and the general Great Plains complex include the
Ute, Cheyenne, Arapaho, Comanche, Kiowa, Pawnee and Plains Apache
(Reference 42).  Because of the locational association with the
proposed project, an archaeological survey was undertaken and was
completed in August 1974 (Reference 8).  The primary survey area
was the proposed drying basin site, where major excavation activi-
ties would take place.

     During its investigation, the archaeological  team found no
surficial evidence of existing archaeological sites on the proposed
drying basin site; a single, isolated mano, probably of Ute origin,
was discovered immediately to the northeast of the site.   The team
determined that, since the proposed site has been  under long-term
cultivation, any artifacts lying on or near the surface would have
been scattered during plowing and seeding activiites.   During the
course of the survey, the team,did discover evidence of a nearby
archaeological site, approximately 8 km [5 miles]  to the northeast
of the proposed drying basin site.

     While land beneath the Metro Denver Plant may contain a con-
cealed archaeological site, the land has undergone development,
and any surficial evidence would have been scattered or destroyed.

     As indicated on Figure 1, the proposed pipeline route lies along
and within various roadway rights-of-way (See map  in Volume II, Issue
1-2).  Consequently, any evidence of associated archaeological  sites
would have been obliterated through adjacent road  building activities,

     Representative off-site distribution areas have also been dis-
turbed in the last century by human activities such as cultivation,
mining and park-building.  Surface archaeological  remnants would
not be present on these areas.

     In terms of historical importance, no known historical site
has been officially designated on or near project  sites which lie
in Adams County (Reference 43).   Since the proposed project opera-
tion will  not disturb any existing historical sites on or near
sludge recycling areas, no historical survey was conducted for
this project.

LAND USE

     Areas in the proximity of the proposed project are presently
used for a variety of urban and rural land use purposes.  Those
areas which are entirely urban in function include land in the
                              71

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immediate vicinity of the Metro Denver Central  Plant and various
parks in the Denver area which will  become project distribution
sites.  Areas which are rural  include the drying basin site, the
Urad Mine and the sod, irrigated and dryland farms.  Other project-
related areas consist of the proposed pipeline  route and the Lowry
Bombing Range site, which also contains the landfill site.

     The Metro Denver Plant facility which will  house the anaerobic
digesters is located within the Denver urban core area.  Use of the
lands immediately surrounding  this facility is  industrial and in-
cludes a rendering plant, a refinery and a variety of factories.

     The site proposed for the drying basins is  rural  in character.
While some of the site and the land  adjacent to  it is used for pas-
turing, the majority is under  dryland cultivation, with  wheat as the
principal crop.  Buildings within one kilometer  of this  site include
a farmhouse and two structures related to agriculture, all of which
are located 0.4 km [1/4 mile]  east of the site.   Subdivisions in the
vicinity are located on five four-hectare [10-acre] lots to the north-
west of the site, but none is  closer than six km [four miles] (Refer-
ence 44).  The area is zoned for agriculture and large subdivision
lots.  County land use plans would continue agriculturally related
uses but also propose an airport facility for this area  (References
45,46).  As proposed, the Adams County General Aviation  facility
will be in excellent conformity with the drying  basin site since the
facility will be flat, low and sparsely populated (Reference 47).

     The Urad Mine, under consideration for sludge application, lies
in a rural area of Clear Creek County approximately 13 km [8 miles]
west of the city of Empire. While the mine is not presently used,
evidence of mining operations  remains, including deforested land
and large volumes of tailings  and other mining wastes deposited near
the vacant mines.  Amax, Inc.  plans  eventually to revitalize the
area by application of its "Comprehensive Plan for Land  Reclamation
and Stabilization at the Urad  Mine"  (Reference 48).  In  time, the
area will be restored through  reforestation and  revegetation activi-
ties (Reference 48).

     The sod farm chosen as representative for sludge recycling lies
close to the drying basin site and,  like that site, is part of a
rural, agricultural area where wheat is the primary crop.  Because
of its proximity to Box Elder  Creek, turf and river bottom grasses
are also grown here.  The only structures on the property are a few
farm buildings.

     The representative irrigated farm also lies in an area which is
devoted to farming activities.  It is located approximately 2.4 km
[1.5 mile] east of Platteville, which is a small, rural  community.
                               72

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Buildings lying on the property include a farmhouse, barn and stor-
age shed.

     Dryland farms to be used for sludge application are coterminous
with the representative sod and irrigated farm areas and therefore
have common environmental characteristics.

     The pipeline proposed for transport of the processed sludge
from the Central Plant to outlying drying basins will traverse both
urban and rural land.  Initially the line will pass through the in-
dustrialized area surrounding the Central Plant.  It will then cross
into Commerce City, a suburb of Denver, and skirt the Rocky Mountain
Arsenal.  From that point it will run beneath the Irondale Road
right-of-way, through land which is rural in character,  until it
reaches the drying basin site in Adams County.

     Because the area surrounding the Lowry Bobming Range is sparse-
ly developed and lightly populated, it may be characterized as rural.
No change from its present use as a sludge deposition and landfill
site is proposed at present.  However, potentially detrimental levels
of heavy metals may have accumulated in the soils (Reference 45),  and
this situation may limit its future land use potential.

LAND TENURE

     The Metro Denver treatment plant facilities are situated on
publicly owned lands.  Various roadway right-of-way areas which will
accommodate the proposed pipeline are also publicly owned, as are
the project-related parks in the Denver area.  The Lowry Bombing
Range, which contains the Lowry Landfill  site, is partly U.S. Air
Force property, partly private and partly state-owned.  Privately
owned lands include the proposed 800-hectare [2,000-acre] drying
basin site, the Urad Mine area and the representative sod, irrigated
and dryland farms.

POPULATION

Regional Population

     The service area where the sludge originates and the areas to
receive the dried sludge are located within the jurisdiction of the
Denver Regional Council  of Governments (DRCOG).  Recent DRCOG popu-
lation trends, disaggregated according to county, are given in
Table 10.

     In common with major metropolitan areas throughout the country,
there has been a recent shift in population from the central city
to the suburbs.  During the year 1974-75, while Denver County's
population remained essentially static, two of the three counties
                               73

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                          Table 10.  POPULATION BY COUNTY, 1970-1975

County
Adams
Arapahoe
Boulder
Clear Creek
Denver
Douglas
Gilpin
Jefferson
Region
1970
183,000
161,000
130,000
4,600
514,000
8,000
1,200
231,000
1,232,800
1971
191,600
166,800
136,700
5,500
518,600
9,700
1,500
245,700
1,276,100
1972
202,800
179,000
145,200
5,700
523,700
10,900
1,600
264,500
1,333,400
1973
213,200
196,000
156,300
5,700
528,000
13,100
1,900
292,300
1,406,500
1974
225,600
211,300
164,200
5,700
529,600
15,800
1,900
310,800
1,464,900
1975
232,100
224,800
171,500
5,900
529,700
18,000
2,000
322,800
1,506,800
Note:  All estimates as of January 1 of each year.
Source:  "Population Change in the Seventies."

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which contain the suburban communities around Denver grew at a rate
faster than that for regional annual popuTation growth, which was
2.97 percent:  Arapahoe County, 6.4 percent, and Jefferson County,
3.9 percent; the tnird, Adams County, grew at a rate of 2.9 percent,
nearly equal to the regional  rate (Reference 49).

     Regional growth reached a peak rate of 5.5 percent per year in
1972-73 and has since declined to a rate close to the 1960-1970
average of 2.6 percent.  This decline in growth rate is attributed
to declining fertility rates, restrictions on new gas and water con-
nections which began in 1972 and a general economic slowdown, which
has reduced the rate of immigration into the region and has brought
new residential construction almost to a standstill (Reference 49).

t^etropolitan L^en^ar Sewage Disposal District No.  1

     The population within Metropolitan Denver Sewage Disposal Dis-
trict No. 1 (Metro Denver) in 1975 was 1,081,000 (Reference 50).
The District serves most of the population of Adams, Arapaho, Jef-
ferson and Denver counties.

Adams County

     Adams County, a rapidly growing section of the Denver Metropoli-
tan area, had the highest growth rate among the DRCOG counties from
1940 to 1950.  In the 1950's it almost tripled its  population.  This
growth has leveled somewhat over the past two decades, as shown in
Table 11.
         Table 11.  POPULATION GROWTH RATES, AUAMS COUNTY

                        (percent per year)

Growth period
1940-1960
1960-1970
1970-71
1971-72
1972-73
1973-74
1974-75
1970-1975
Growth
Annual


4.7
5.8
5.1
5.8
2.9

rate
Average
6.8
4.4





4.9
Source:   Reference 49.
                               75

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     Almost two-thirds of the population of Adams County is concen-
trated in the cities of Aurora, Northglenn, Commerce City, Thornton
and Westminster.   About 95 percent of the population is in urban
areas.  The sewage from 78 percent of the population of Adams County
is generated and  treated within the Metro Denver district.  Adams
County accounts for 17 percent of the population in the Metro Denver
service area.

Population Projections

     Projections  of population for the counties of concern are given
in Table 12.

     DRCOG population estimates were adjusted by Metro Denver staff
for use in their  Long Range Planning Study.  These figures give a
total District projection for the year 2000 which is 16 percent
higher than that  projected by DRCOG for the same area for that year
(.Reference 9).  Table 13 shows a range of eight projections for the
five-county Denver region for the year 2000.   On the basis of the
16 percent difference mentioned, it would appear that Metro Denver's
projections fall  somewhere near the middle of the range of projec-
tions made by various agencies.

     The projected sludge load increases used to estimate the 1985
levels are given  in Table 14 along with Metro Denver and DRCOG popu-
lation growth assumptions for a similar time  period.

TRANSPORTATION AND CIRCULATION

     Roadway, railroad and air travel are the primary modes of trans-
portation used in the region of the proposed  project.  While road-
ways serve most areas, railroad travel is concentrated on lines pass-
ing through Denver and airplane travel facilities are interspersed
throughout the region.

     Roadways of  a variety of types serve the region.  Minor streets
and arterials are found in urbanized areas, particularly those sur-
rounding the City and County of Denver, along with state, interstate
and federal highways (Reference 56).  In rural  and sparsely populated
areas, roadways are limited to minor streets  and arterials, which
are variously classified, depending on surface composition character-
istics and design width (Reference 57).  In general, these roads are
infrequently travelled, with average daily travel (ADT) ranging from
90 to 230; however, many are adequate in design to carry heavy, agri-
culturally related trucks and can accommodate an ADT as high as 6,200
(Reference 59),

     Railroads in the region are concentrated around Denver.  These
                                76

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                     Table  12.   SELECTED  POPULATION PROJECTIONS FOR COUNTIES
                                   IN VICINITY  OF METRO  DENVER

County
Denver
Adams
Arapahoe
Jefferson
Weld

Population,
1975a
529,700
232,100
224,800
322,800
114,000

State of Colorado
low
392,000
314,000
322,000
483,000
138,000



projections13, 1995 DRCOG projections0
high
538,000
432,000
443,000
664,000
160,000
1990
602,000
295,000
345,000
515,000
(not
2000
709,100
326,000
413,000
658,000
in DRCOG)
 Source:   Reference  51  for  Weld  County,  Reference  49  for  all others.
 Source:   Reference  51.
"Source:   Reference  52,  Denver Regional  Council  of Governments.

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                Table 13.  POPULATION FORECASTS FOR THE FIVE-COUNTY DENVER REGION IN THE  YEAR 2000


          	Agency	Population  estimate

                 U.S. Department of Commerce, Office of Business  and               1,981,000
                   Economic Research Service (OBERS)

                 Colorado Land Use Commission                                      2,175,000

^                Denver Regional Council of Governments (DRCOG)                     2,350,000
co                  (policy forecast)

                 Denver Research Institute (DRI)                                   2,675,000

                 Colorado Division of Planning (county total)                       2,886,000

                 Colorado Division of Planning (city total)                         2,892,000

                 Metropolitan Denver Water Study Committee                         3,000,000

                 Colorado Division of Planning (adjusted city  total)               3,399,000


          Source:   "Appraisal of the DRCOG Policy Population Forecast."

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           Table 14.   POPULATION AND  SLUDGE  LOAD  PROJECTIONS FOR METRO DENVER DISTRICT

Projections
DRCOG population projection
for Metro Denver district3,
persons
Metro Denver population pro-
ir jection , persons
Metro Denver sludge load
projection0, dry metric
tons/day
Time period
1970-1985

1970-1985
1977-1985
Year Average
1970 1977 1985 growth
1,074,775 1,469,420 2.

1,080,032 1,683,400 3.
68 97 4.
annual
rate, %
1

0
8
 Source:   Reference 9.

 Source:   Reference 47.
Q
 Source:   Reference 55.

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include the Union Pacific and Burlington-Northern Railroad lines.
Although there is variation in routes, most of the lines pass
through Denver (Reference 56).  The line closest to the proposed
sludge drying basin site lies 11 km [7 miles] to the south.

     Airport facilities located within the region include Stapleton
International Airport in Denver and a variety of noncommercial pri-
vate facilities in Adams, Arapahoe, Weld and Denver counties  (Ref-
erence 60).  The proposed Adams County General Aviation Airport is
located in the proximity of the area slated for the sludge drying
basins.

RECREATION

     The State of Colorado is divided into several recreational
regions.  Denver, Adams, Weld and Arapahoe counties are included
in Metro Region No. 9, while Clear Creek County lies in the North-
Central Colorado Region No. 7 (Reference 43).  There are a number
of officially designated recreational areas within these two re-
gions.  They include reservoirs, rivers and streams, natural lakes,
cold springs, forests the parks (Reference 43).  Recreational areas
of several types are found near the proposed project.   The proposed
South Platte River recreational area is located approximately 1.6 km
[one mile] east of the Metro Denver Plant; Barr Lake and Barr Lake
Duck Club lie 18 km [11 miles] northeast of the proposed drying basin
site.  In the vicinity of sludge recycling sites are the Big Bend
Picnic Grounds, about 1.6 km [one mile] northeast of the Urad mine;
the Old Fort Vasquez site, about 1.6 km [one mile] southwest of the
Platteville sod farm; and 120 developed neighborhood parks in Denver
County (Reference 40).

INSTITUTIONAL AND GOVERNMENTAL AGENCY JURISDICTIONS

     The jurisdictional issue of principal concern for the proposed
project is the conflict between Adams County and Metro Denver over
final approval of the drying and distribution center.   Since the
proposed site for this operation is within unincorporated County
territory, and therefore under the jurisdiction of the Adams County
Planning Commission, the County feels it should have the power to
accept, modify or veto the operation.  Very recent litigation has
determined that Metro Denver needs a Certificate of Designation
from the Adams County Board of Commissioners in order to proceed.
The application for Certificate of Designation, including support-
ing documents (such as this Draft EIS), would be reviewed by the
Colorado Department of Health, who would recommend approval or dis-
approval  to the County Commissioners (Reference 61).  If approval
is not forthcoming, the District can attempt to exercise its power
to condemn property required for its operations (Reference 62).
                                8U

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A recent amendment to Colorado State solid Haste legislation has re-
moved the need for farmers using sludge for agricultural purposes
to obtain a certificate of designation.  Metro drying facilities
will still be required to obtain such a certificate.

     Most of the farmlands affected by the proposed project are
within unincorporated County territory and are under the jurisdic-
tion of the Adams County Planning Commission.

     The Colorado Board of Land Commissioners is the Statewide plan-
ning body responsible for the management of State lands.  The State
of Colorado owns about 130 hectares [320 acres] of the recommended
site (B-2).

     The regional planning body with jurisdiction in the study area
is the Denver Regional Council of Governments (DRCOG).   This is a
planning agency whose purpose is to coordinate plans of local and
county governments and to ensure, through the A-95 review process,
that federally funded projects are in harmony with these coordi-
nated plans.  DRCOG has studied the feasibility of coordinating
a solid waste management program with Metro Denver's sludge
management system, but found that coordination of programs is
uneconomical at this time.  As of March 1976, the Colorado legi-
slature has let die proposed legislation which would have made
regional solid waste management possible.

     The U.S. Environmental Protection Agency is the Federal body
charged with managing the Federal funds provided for construction
of the proposed project.  Another Federal  agency with jurisdiction
and interest in the proposed project is the U.S. Food and Drug
Administration (FDA).  The FDA generates and enforces regulations
for the application of sludge on crops which enter the human food
chain if they are to be used in interstate commerce. Jurisdiction
over the immediate health concerns associated with the project is
held by the Tri-County District Health Department.  This Department
oversees the present operations at Lowry Bombing Range and would
also be responsible for checking the  proposed operation in Adams
County.

     The City of Denver uses a small portion of the Lowry Bombing
range for the disposal of its solid wastes.  Metro Denver Sewage
Disposal District uses on an interim basis another area of the
range which is owned by the City and County of Denver.  The City
maintains jurisdiction over the area, and no lona-term or written
agreement is in effect between the two entities.  The City has
expressed its intent to eventually utilize the additional Lowry space
including the 240 ha [600 acres] of present Metro operation, for its
own future sanitary landfill operations (see letter in Volume II and
Reference 63).
                              81

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SOCIO-ECONOMIC SETTING

Adams County Agricultural Economy

     Agriculture has been the mainstay of the Adams County economy
since homesteaders first arrived in the 1860's (Reference 45).  Al-
most 95 percent of the area of the county is presently in agricul-
tural use.

     In 1973, Adams County ranked seventh among the 65 counties in
the state in winter wheat production, tenth in barley, seventeenth
in sugar beets, nineteenth in corn for grain, twentieth in sorghum
for grain and eleventh in total crop production.

     Truck farming activities in western Adams County are concen-
trated along the Platte River.  The main irrigated crops are alfal-
fa, corn, barley, sugar beets, oats and rye.  Greenhouses and turf
farms are increasing,  and this trend is expected  to continue [Ref-
erence 45).  Dryland farming is carried out primarily in the east-
ern part of the County (including the vicinity of the proposed dry-
ing and distribution center site).  The main nonirrigated crops are
winter wheat, forage sorghum and barley.  The values of the various
crops produced in Adams County are shown in Table 15.

     Livestock population in Adams County is shown in Table 16.

Sources of Fertilizer

     Nitrogen fertilizers are manufactured using  nitrogen from the
atmosphere and hydrogen from fossil sources (coal, pertroleum and
natural gas).  The fossil resources and phosphorus are imported from
other states.  Sources of potash exist in southwestern Colorado,
although current production is insignificant.  Additional supplies
are available from southeastern Utah, where potash is mined exclu-
sively.

     The main source of organic fertilizer in Colorado is livestock
manure.  Dried manure  comprised about 88 percent  of the total or-
ganic commercial  fertilizer sales in 1972 in the  Mountain States;
about 10 percent consisted of activated sewage sludge; the other
two percent was composed of other sewage organics and tankage, and
dried blood.   Similar  percentages are assumed to  hold for Colorado
(Reference 5).

     There were 281,000 metric tons [309,551 tons] of fertilizer
sold in Colorado in 1972, up from about 175,000 metric tons [193,000
tons] in 1965.   During the same period, the commercial sale of natu-
ral organic materials  dropped from 16,000 metric  tons [18,000 tons]
to 6,600 metric tons [8,000 tons].
                                82

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               Table 15.  VALUE OF CROPS PRODUCED IN
                     ADAMS COUNTY, 1972-1973

Crop
Wheat
Corn, grain and silage
Barley
Sorghum grain
Sugar beets
All other crops3
TOTAL
1972
Value
$ 6,752,900
2,310,000
832,000
25,100
744,400
4,529,300
$15,193,900

%
44
15
6
—
5
30
100
1973
Value
$13,768,000
2,467,100
763,500
35,700
—
5,590,500
$22,624,800

%
61
11
3
—
—
25
100
*3
 Includes dry beans, rye, hay, potatoes,  oats,  broomcorn,  fruits
 and vegetables.

Source:  Comprehensive Plan:   Adams County.
         Table 16.  LIVESTOCK ON FARMS,  1 JANUARY 1973,
         ADAMS COUNTY, RELATIVE TO ALL COLORADO COUNTIES

Livestock
Cattle and calves
Milk cows
Hogs and pigs
Stock sheep
Cattle on feed
Number
70,000
5,000
22,500
4,300
40,000
Ranking
13
3
4
25
5
Source:  Comprehensive Plan:   Adams County.
                               33

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     The fertilizer required for the agricultural economy of the
state was in short supply, at the time of the release of the draft
EIS.  This situation was linked to fuel and natural gas shortages
and to increase demand in this country and abroad; however, present
supplies seem adequate.  Future shortages related to the increasing
scarcity of fossil fuels will undoubtably occur.

Urban/Rural Characteristics

     The socio-economic characteristics of the Metro Denver service
area differ greatly from the characteristics of the area proposed
for the sludge drying and distribution center.  This difference re-
flects the urban/rural contrast:  Metro Denver serves the urbanized
Metropolitan Denver area, while the proposed site is situated in
rural Adams County.  There are perhaps even greater differences
between the eastern and western parts of Adams County than between
Denver County and Adams County, as indicated in Table 17.


     Table 17 shows some of the contrasts among socio-economic
characteristics of the three areas (Reference 43).  In 1972, about
95 percent of the population of Adams County was urban rather than
rural, with approximately 65 percent of the population concentrated
in five cities in the far western part of the county adjacent to
Denver (Aurora, Northglenn, Commerce City, Thornton and Westminster).
Census Tract 084 consists of that part of Adams County east of Box
Elder Creek (roughly the eastern two-thirds of the county), the
~.rea in which the sludge drying and distribution center would be
located.

Land Values

     An appraisal  of Site B-2 in 1976 by a private firm set its value
site at $540,000.   This sets the value of the land at about $700 ha
[$280/acre] (Reference 132).

     Market values fluctuate considerably, but the current market
for land bought by a farmer in large tracts in the general  area of
the proposed project site is approximately $500/hectare [$200/acre]'
for dry farmland and $1,000/hectare [$400/acre] for farmland with
wells adequate for irrigation (Reference 66).

     Through speculation, often in anticipation of a special demand
for a particular parcel,  property values may rise as high as $5,000/
hectare [$2,000/acre],  or prices may be increased because of a trans-
action which involves  a low downpayment (Reference 66).   The recent
trend in  land  values  in the area is one of sporadic increases in
property  value.   The  general  trend in Colorado shows a 25 percent

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                      Table 17.   CONTRASTING SOCIO-ECONOMIC CHARACTERISTICS

Characteristic
Total population
Mobility /stability
Commuting patterns
Education
Family size
Income
Age
Farm population
Criterion
Numbers of people
Lived in same house, 1965-1970
Work in county of residence
High school graduates, 25+ yrs old
College graduates, 25+ yrs old
Children born/women married, 35-44
yrs old
Median family income
Median age
Number of farm-related jobs: farmers,
mgrs, foremen, workmen
Farm and related jobs/100,000 population
Denver
County
514,678
44.0%
78.1%
61.5%
15.5%
3.0
$ 9,654
28.6
1,020
198
Adams
County
185,789
46.6%
32.7%
62.7%
8.6%
3.0
$10,409
22.8
1,613
868
Census
tract 084a
2,233
50.6%
69.4%
58.0%
5.2%
2.7
$ 6,374
28.2
277
1189
 Approximately the eastern two-thirds of Adams County.
Source:  1970 Census of Population and Housing (Reference 64);  1970 Census  of  Population
         (Reference 65).

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increase in land value from 1972 to 1973, a 14 percent increase
from 1973 to 1974 and a seven percent increase from 1974 to 1975
(Reference 66).  Land values may change near the proposed site in
response to a number of currently unpredictable factors, including
changes in farm prices and the rate of growth of the Denver region.

Employment

     The employment-generating facilities associated with the pro-
posed project will be located in Adams County.  The major employ-
ment classifications in Adams County are given in Table 18.


         Table 18.  ADAMS COUNTY EMPLOYMENT PATTERNS, 1973
_          Employment category                 Number employed

     Retail trade                                   8,700
     Manufacturing                                  7,300

     Contract construction                          5,100

     Services                                       4,900
     Farm-related jobs (farmers, man-               1,800
       agers, foremen, workmen)

     Wholesale trade                                1,600
     Transportation and other public                1,600
       utilities
     Finance, insurance,  real estate                1,200

Source:  1970 Census of Population (Reference 65); Adams County In-
         formation Service (Reference 43).


     The Urad mine is one of the sites being evaluated as a sludge
recycling area.   The mine is one of three owned by Climax Molybdenum
Company, which is the largest private employer in Colorado, employ-
ing 3,500 workers (Reference 41).

     The unemployment rate in the eight-county Denver-Boulder Labor
Market Area in September  1975 was 5.7 percent; the Adams County rate
was 5.8 percent (Reference 67).  The national rate at that time was
eight to nine percent.

VISUAL AESTHETICS

     The rural  regions within the study area are characterized by a
                                86

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broa-J, rolling topography.  Uhile there are generally no particu-
larly striking features in this agricultural area, an expansive
and restful atr.osphere gives the area a pleasant contrast to the
urbanized areas to the west.  Dryland farms bear relatively fev,<
signs of agricultural activity and thus do little to disturb the
area's original prairie impression.  Irrigated farms are more ac-
tive; their green crops exist in greater variety and provide a
mor2 stimulating rural backdrop.

     The Denver Parks provide a variety of well-maintained, attrac-
tive areas within Ihe city.  The 1,800 acres of parkland range from
quiet, secluded neighborhood parks to the spacious City Park, whici
includes a number of lakes and provides a setting for many culutral
and recreational activities.

     To reach the mine reclamation site farther to the west, one
leaves the flat, rural regions and climbs into the rugged, moun-
tainous terrain more commonly associated with the Rocky Mountain
region.  The Urad Valley is one of the many high, scenic valleys
along U.S. Highway 40, but its scenic valuo has been impaired by
mine tailings deposited on the floor of the valley.

     Specific descriptions of the environmental setting of the
various representative sludge application areas are presented in
Appendix E.

PUBLIC HEALTH

     The agency charged with maintenance of the public health in
Adams, Arapahoe and Douglas counties is the Tri-County District
Health Department.  This agency monitors the present Metro Denver
sludge disposal operations at Lowry Bombing Range in Arapahoe
County and would also monitor the health impacts of the proposed
project.  A project requiring a Certificate of Designation is sub-
ject to review by the Colorado Department of Health, who would
have veto power over the project (Reference 73).

     The U.S. Environmental Protection Agency takes public health
impacts into consideration in awarding grant monies.  These consid-
erations are contained in the tentative guidelines presently being
circulated for review before being formally released by EPA  (Ref-
erence 79).

     The Agricultural Research Service of the U.S. Department of
Agriculture sets down criteria to ensure that heavy ,,etals in
sludge (zinc, copper, cadmium, etc.) will not harm plants or the
soil.  The U.S. Food and Drug Administration has yet to promulgate
guidelines for control of levels of possibly harmful substances in
sludge applied to crops which enter the human food chain.
                              87

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w
 h
H
H

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     The principal features of Metro's proposed
sludge management plan are described in this
Section.  Main features include anaerobic di-
gesters, pipeline and pumping facilities, the
drying/storage/distribution center and proposals
for on-site irrigation and disposal.  Metro is
planning to market the sludge to farmers and
other users.  The type of uses considered and
their general locations are described here.
Discussion of recommended loading rates and
limits based on research in each type of land
use is presented.

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                           SECTION IV

                 DESCRIPTION OF PROPOSED ACTION


     Metro Denver's proposed sludge management plan involves
treatment of sewage sludge at the District's Central  Plant and
pipeline transport to a sludge drying and distribution center 40
km [25 miles] east of the Metro Denver Central Plant.   Air-dried
and liquid sludges will be taken from the center and  applied to
the land in various ways.  Each component in the proposed sludge
management system is described in this Section.  A predesign and
site selection study was conducted for Metro Denver in 1974-75.
The recommended plan is discussed in detail  in the "Metro Denver
District Sludge Management, Volume I - Summary Report  and Volume
III - Agricultural Reuse Predesign" (References 55 and  118).   Ex-
cerpts from these reports are used extensively in this Section
for the description of the proposed action.

SLUDGE TREATMENT

     Raw sewage sludge is generally unacceptable for  land appli-
cation due to the problems of odors, vectors and disease trans-
mission.  These aesthetic and public health problems  can be al-
leviated by stabilization of the putrescible organic  material in
the sludge.  Sewage sludge at the Metro Denver Central Plant will
be stabilized by anaerobic digestion.  The Denver Northside Plant
sludge is digested prior to conveyance to the Central  Plant.  This
process will involve the decomposition of most of the  organic ma-
terials by micro-organisms in the absence of oxygen.   The sludge
will be processed in mesophilic digesters with a constant temper-
ature maintenance at 35°C [95°F] and continuous gas-diffusion
mixing.

     The digesters are designed for loadings of 2.1 kg of volatile
suspended solids (VSS) per day per cubic meter of digester [0.13
Ibs/day/cubic foot] and a 22 day digestion period.  At the end of
this detention period, 50 percent volatile solids destruction and
three  percent solids concentration should occur.  Most of the organic
material will be converted into water, methane, carbon dioxide
and other gases.  A comparison of changes in sewage sludge char-
acteristics through anaerobic digestion is given in Table 19.
                              d9

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Table 19.
CHANGES IN CHARACTERISTICS OF
SEWAGE SLUDGES THROUGH DIGESTION3
Concentration from treatment oreceedine analysis



Primary settling
Constituents
Total solids, %
Suspended solids, %
Volatile solids,
% of T.S.S.
Chemical oxygen
demand, ppm
Total nitrogen, ppm
Organic nitrogen,
ppm
Phosphate, ppm
Grease, ppm
Alkalinity, ppm
Range
4.25- 8.90
-
72.0 -94.5

36,800-98,280

1,070- 2,734
340- 2,626

1,237- 2,257
8,544-13,916
1,000- 2,420
Mean
6.4
-
80.2

61,267

2,066
1,874

1,795
11,080
1,603
Dissolved Suspended
Cadmium, ppm
Nickel, ppra
Lead, ppm
Silver, ppm
Zinc, ppm
Copper, ppm
Arsenic, ppm
Chromium, ppm
Typical ranges and
0.02
0.67
Total: 8.
Total: 2.
1.55
11
0.01
0.09
2.48
10.43
00
40
119
52
1.0
45
means were obtained from
Primary to secondary sludge solids
ratio 15
Activated
sludge
Secondary settling
flange
0.44- 0.89
0.10- 0.79
57.3 -92,0

4,224-11,408

481- 799
462- 580

963- 1,360
248- 528
330- 520
Dissolved
0.03
0.38
0.25
0.30
0.25
0.50
0
0.07
data at the City
Mean
0.69
0.58
73.1

7,106

541
512

1,148
400
430
Calculatedb
Combined sludges
Mean
4.02
-
79.8

38,699 12

1,431 1
1,30

1,525 1
6,630 1
1,114 4
Suspended . Dissolved Suspended
0.77
1.42
2.25
2.00
12.8
11.5
0.14
16
of Los Angeles
; 1; primary to secondary sludge
0.02 1.77
0.55 6.68
Total: 5.71
Total: 2.36
1.01 75
6.6 35
0.006 0.64
0.08 33
Hyperion Wastewater
flow ratio 1.4:1.
Mesophilic
digestion
Range
1.15- 2.98
1.04- 3.23
35.8 -71.5

,900-42,400

,840- 2,173
720- 969

,250- 1,734
,576- 2,672
,900- 6,700
Dissolved
0.02
0.36
0.50
Total:
0.06
11
0.01
0.06
Mean
2.12
2.22
59.9

24,195

2,000
869

1,570
1,981
5,520
Suspended
2.98
9.14
7.5
3.30
77.3
32
0.08
50.3
Thermophilic
digestion
Range
1.67- 3.64
1.06- 3.67
37.8 -70.5

19,200-47,200

1, 516-^2,079
320- 790'

1,101- 1,697
2,468- 3,264
5,190- 7,900
Dissolved
0.02
0.45
0.45
Total:
0.20
0.27
0.04
0.15
Mean
2.35
2.49
62.0

33,420

1,992
697

1,604
2,820
6,190
Suspended
2.78
11.1
7.55
2.40
67.8
36.7
0.87
52.5
Treatment Plant.





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The example data are drawn from the Hyperion Wastewater Treatment
Plant in Los Angeles which treats sludges with higher metal  content
than Metro Denver's and utilizes thermophilic digestion.   While
the changes in characteristics of sludges occur at a faster  rate
in thermophilic digestion, the change in characteristics is  gener-
ally similar to that from a mesophilic process.  However, it is
expected that microorganisms (pathogens in particular) will  not be
reduced in numbers as effectively with the mesophilic process.

     At the anticipated design loading, ten digesters would  be  re-
quired with a total volume of 2.4 million cubn'c feet.  First, eight
concrete anaerobic digesters with a total  volume of 54,000 cu m
[1.9 million cu ft] would be built to accommodate 1977 sludge load-
ings at the Central Plant of 2,047 cu m/day [547,000 gal/day].
These digesters have been constructed as part of the present
Central Plant expansion.  Two additional digesters would be  con-
structed sometime prior to 1980 to handle the 1985 design capacity
of 3,100 cu m/day [824,000 gal/day].

     In the predesign study, it was assumed that all initial eight
units would operate as primary digesters.  Four of these units,
however, have been designed with the flexibility of operating as
secondary digesters for gravity thickening of the digested sludge.

     Three existing sludge holding tanks at the Central Plant
would be used in the sludge digestion and agricultural reuse sys-
tem.  One tank would provide storage for the undigested Central
Plant sludge.  Another tank would store the Central Plant sludge
after it is digested as well as the Denver Northside digested
sludge.  The sludge in this latter tank would be pumped to the
sludge drying and distribution center.  The third tank would be
used for storage of the liquid sludge in the event of some emer-
gency in the system.

SLUDGE TRANSPORT SYSTEM

     The liquid sludge would be transported from the Central Plant
to the distribution center through two pioelines, 25 cm [10  in.]
and 30 cm [12 in.] in diameter.  Each pipe would be capable  of
handling 40 I/sec [600 gal/min] of sludge or secondary effluent.
Secondary effluent would be pumped tnrougn me force mains to
clean out solids deposits.  At the distribution center the efflu-
ent would be used for irrigation, dust control and fire protection
of on-site facilities.

     The proposed pipeline route to the sludge distribution  center
site is shown on Figures 1 and 2.  The criteria used for locating
the route were length of route, elevation along the route and

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 proximity  to  established rights-of-way  for easy  access  to  power
 lines.   These criteria were  used to minimize costs  and  environ-
 mental  impacts.  The pipeline will run  parallel  to  the  railroad
 tracks  heading northeast from the District's plant and then turn
 eastward along the northern boundary of the Rocky Mountain Arsenal.
 From there the pipelines will turn east to the distribution center
 along Irondale Road.

     A  system of Central  Plant pumps and booster pumps at an inter-
 mediate  pump  station would be used to produce the required head of
 240 m [800 ft] to pump the material  from the Central Plant to the
 distribution  center.  The Central Plant pumps would develop 120 m
 [400 ft] of head, and the additional  120 m [400 ft] would be sup-
 plied by the  booster pumps.

     All transport system pumps would be controlled from the Cen-
 tral Plant.   Gauges and meters at both the Central  Plant and dis-
 tribution center would monitor the operation of the transport
 system.

 SLUDGE  DRYING AND DISTRIBUTION CENTER

 Drying  and Distribution Center Site Selection

     The three potential  sites for the drying and distribution
 center,  shown on Figure 2, were compared to determine the best
 location on the basis of economic and environmental considerations.
 Factors  examined in making the site selection are shown in an ap-
 pendix  to the Environmental Assessment for the Metropolitan Den-
 ver Sewage Disposal District Sludge Management (Volume IV) (Ref-
 erence  8) and  reproduced  nsre in  Appendix  G.

     The environmental  factors investigated in comparing the sites
 included historic value of each site, climate, plant and animal
 ecology, traffic and aesthetic impacts, economic investment and
 land use.  Land use was found to  be the most distinguishing factor
 among the three sites.   The least amount of project impact on pres-
 ent and  potential  land  use would  occur at  site B-2.  Both sites A
 and A-2  have the disadvantage of  being located near an existing
 housing  subdivision which is scheduled for future expansion.  Be-
 cause site B-2 is near  the fewest number of private homes, loca-
 tion of the facility at that site would be more acceptable to the
 local  community.

     In an economic comparison conducted in Appendix A of "Agri-
 cultural Reuse Predesign" (Volume III), the present worth for 10
years  of design,  construction and operation for sites A, A-2 and
 B-2 is $11,948,000, $11,695,000 and  $12,899,000, respectively.
                                92

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Thus, on the basis of the economic comparison, site A-2 would be
the preferred location, and site B-2 the least desirable location.
However, site B-2 was recommended as the best location for the
drying and distribution center primarily because it was not near
any major residential development.  The potential  social  problems
associated with locating the distribution center near a subdivision
far outweighed all other differences among the three sites.  Solu-
tions or compromises could be worked out for most of the environ-
mental and economic problems.  However, strong public opposition
to the project would be difficult to resolve and could be detri-
mental to the success of the project.  Locating the distribution
center at site B-2 would minimize this problem.  Furthermore, the
projected location of a new regional airport near site B-2 com-
prises a highly compatible land use.

Drying and Distribution Center Operation and Layout

     The sludge drying and distribution center would operate as  a
drying, storage, marketing and research and demonstration center.
Facilities which would be used for these functions are illustrated
on Figure 12 and are described in the following paragraphs.  Sludge
could be purchased at the distribution center in both dry and liq-
uid forms.

     The sludge would be air-dried in earthen drying basins which
would occupy about 240 ha [600 ac] at full  development of the pro-
ject. The open, unlined basins would be separated by  earth berms.
The drying basins could process about 33,000 dry metric tons
[36,000 short tons] of sludge per year.  Sludge applied to the
basins in layers of 60 cm [24 in] can be expected to dry to 40 to
50 percent solids in about eight to twelve months.  Since sludge
will not materially dry during the winter, a nine month drying time
is assumed for design purposes.  It should be noted that during  the
drying process, further changes occur in sludge characteristics.
The probable changes over 50 days in nitrogen content, for example,
are shown in Figure 13, as measured at the Colorado State University
Agricultural Experimental Farm at Fort Collins using anaerobically
digested liquid sludge in the winter of 1974.

     Dried sludge will be removed from the basins when test indi-
cate that the required solids content has been achieved.  Front-
end loaders will  load dried sludge into special trucks (not yet
specifically determined) for transport to the stockpile area. The
stockpile area will  serve as the storage area and as the distri-
bution point where users could obtain dried sludge.  The dried ma-
terial will be stored between the drying beds as shown in Figure 12.
Fences will be erected around the entire solids drying and distri-
bution center area to keep out grazing animals and wildlife.  The
capability for manual wetting of the stockpiles will be provided
                               93

-------
                                                            FIGURE  12
               ;        '                       '                  /  • /  I
                                                                '.''"•'  /  /
           rw                                                     H-
                                                          .
                                                      10  l
                                             SIDE-ROLL
                                             IRRIGATION
                       RUN-OFF
                       MPOUNDMENT
                                               ^-STOCKPILE AREA
V  DRAINAGE DITCHES-'
 \   "-V  '   \
                                                      o ^RUN-OFF
                                                         IMPOUNDMENT
                               SLUDGE  DRYING
                                 0 HECTARES
    , % PURGE
      "IMPOUNDME
/     \ ^-J"\ \  «s
  IMPOUNDMENT-v, a1.
                                                      J*  INJECTION
                                                      10
                                                      10 ) /
                                                  r
                                                      1 :  /;
                                                      0>+METRO  SITE
                         oooooooooooooooooooooooooo'o ooooooo
                          ^CONTROL
                            COMPLEX

               /-.           f
                               /
                                        SOURCE^ SLUDGE MANAGEMENT PLAN FOR
                                               METRO DENVER DISTRICT
              METROPOLITAN   DENVER  PROPOSED
          SLUDGE  DRYING  AND DISTRIBUTION  CENTER

-------
                                                    FIGURE  13
  16
  15
  14 -
  13-
  12
  i
  10
p
o
u_
O

I-  8
UJ
O
IT
UJ
Q_
UJ
(5
O
a:
                                       LEGEND AND NOTES

                                           NH-* -N
                                         TKN
                               TOP LAYER   	®-	

                               MIDDLE LAYER	A	
              ^BOTTOM LAYER	-®	


                \    I. BASIN DEPTH  I METER (40 INCHES)

                 \   2. BOTTOM OF BASIN WAS LINED
                                        -X-*s
         _L
            SOURCE: METROPOLITAN DENVER SEWAGE  DISPOSAL DISTRICT NO. I
_L
JL
_L
_L
   0      5     10     15     20    25    30    35     40    45     50

   TIME, DAYS SINCE LIQUID SLUDGE WAS INTRODUCED  INTO DRYING BASIN
           AMMONIA AND TOTAL KJELDAHL NITROGEN
     CONCENTRATION  AS A  PERCENT OF THE TOTAL SOLIDS
   CONCENTRATION IN  THREE LAYERS  IN AIR DRYING BASINS

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as a means of preventing air pollution during strong windstorms.
Dried sludge will be transported by truck to agricultural users'
farms and to other land application areas.


     On-site subsurface and surface application areas could be used
to test and illustrate the effects of using liquid or dried sludge
for agricultural purposes.  Present plans call  for subsurface injection
of sludge only if for some reason the liquid sludge was unacceptable
for distribution or drying, or if the market was inadequate.   However,
it appears at present that an adequate market will exist for all the
District sludge in 1985.


     Land application of sludge on the research and demonstration
plots would test the effects of various sludge loading rates  on
crop production.  Both irrigated and dryland crops would be grown
on these plots.  Various control features would ensure reliable
and efficient operation and maintenance of the distribution center.
A control and administration building, a maintenance building, and a
laboratory would be parts of the on-site control complex.  All of
the automatic controls and monitoring devices for operating the
distribution center would be housed in the control and administra-
tion building.  Another control feature would be the collection
and impoundment of the on-site surface runoff water by a system
of earthen channels and dams to prevent possible contamination
of surface waters, as shown on Figure 12.  Offsite runoff would
be diverted around the site.  Also, soil  and groundwater would be
monitored continually to provide information for research purposes.
and for protection against potential  environmental damage.
PROPOSED LAND APPLICATION OF  SLUDGE  BY  METRO  DENVER

     The Metropolitan Denver  Sewage  Disposal  District No.  1  pro-
poses to make sludge available for recycling  on various agricultural
areas in the vicinity of Denver.  The agricultural  reuse program
would involve controlled seasonal applications  under careful  nutri-
ent and toxin management.  Disposal  landfilling would probably occur
only under emergency conditions at the  Lowry  Bombing Range Sanitary
Landfill.  High-rate sludge application, as proposed by Metro Den-
ver, would be conducted in the open  lands of  the Lowry Bombing
Range if the proposed sludge  recycling  plan is  not  implemented.
Controlled sludge application areas  may include Denver Parks, sod
farms, mine spoil  areas, irrigated and  dryland  farms and possibly
some home gardens.
                                96

-------
     It is envisioned that no single type of application will  be
used for the ultimate disposal  of the entire sludge generated  in
Denver.  More likely, a combination of two or more types of land
application, with varying proportions from year to year (and
greater variety in the years following the initial few years)  will
take place.  Because of the varying environmental  settings of  the
different sites and the different possible impacts of each type of
land application, separate discussions of each type and the methods
of application envisioned for those types are presented.  Figure 3
shows potential areas for each category of sludge  application.
No definite contractual arrangements have yet been made for specific
sludge recycling areas, nor are any contemplated at present.
       SPECIALLY EQUIPPED TRUCK SPREADS SLUDGE ON FARMLAND


     In the following paragraphs, the proposed sludge recycling
areas and the present disposal operations at Lowry Bombing Range
(the no-action alternative) are discussed with a view to recom-
mended methods and rates of application and operation.
                               97

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Sludge Recycling Areas

     Denver Parks--

     Over the past few years, some dried sludge (containing 20 to
30 percent solids) has been used in preparing topsoil  for estab-
lishment of new city parks in Denver and other cities  in the area.
The stockpiled and air-dried sludge has been incorporated into top-
soil at about 112 metric tons/ha [50 tons/ac] prior to spreading
the topsoil on new park areas for seedbed preparation.  The Parks
Department now takes vacuum-filtered digested sludge and dries it
near Stapleton Airport for use on parks.

     In the future, if the proposed reuse scheme becomes operational,
anaerobically digested and air-dried sludge will  be spread during
winter months on already established parks.  It is expected that the
sludge will be applied to the grass at the same total  rate (112
metric tons/ha [50 tons/ac]) during the wintertime. The City and
County of Denver Parks Department has received sludge  free of charge
in the past and expects to utilize up to a maximum of  4,500 metric
tons [about 5,000 short tons] per year on that basis.   However, if
a charge is imposed or if the delivery responsibility  is shifted to
the recipient, a change in this projection may occur.

     Other communities indicating interest in sludge application to
park areas are Northglenn, Commerce City and Aurora.   Parks in the
Denver area which are potential sludge candidates are  graphically
shown in Figure 3.

     Sod Farms—

     Application of anaerobically digested air-dried sludge on sod
farms will  probably be conducted by broadcasting of the dry material
using manure spreaders or similar equipment.  The relatively fre-
quent sprinkler irrigation, typical of such farms, will provide the
necessary mechanism for moving sludge particles and soluble mate-
rials into the soil root zone.

     With the cyclic removal of thin layers of soil during the har-
vest operations, residual  sludge and its components—not used by
plants—are also removed from the site and transported to the con-
sumer.  At the final destination, sludge materials in  the sod root
network and the soil carried with it are gradually dispersed into
the soil and eventually taken up by plant root systems.

     Representative locations of major sod farms in the Denver area
are depicted in Figure 3.
                              98

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     Mine Spoil  Sites--

     In many parts of the Rocky Mountains, the natural  landscape
has been marred by large piles of mine tailings created  in the  pro-
cess of extracting molybdenum and other elements from mined ores.
Without a deliberate effort to reclaim these spoil  areas and im-
prove their potential productivity, these inert heaps may remain
unvegetated for many decades.  On some sites, where particle sizes
are uniformly coarse (large gravel, boulders and rocks), larger
particles may have to be crushed or finer materials imported before
attempting to add organic materials.

     For the example mine spoil site—the URAD mine near Berthoud
Pass—it is expected that Climax Molybdenum will furnish the neces-
sary trucks and other equipment needed for transporting  and applying
dried sludge.  Sludge will  be mixed with wood chips in equal  pro-
portions and applied at an initial rate of 45 metric tons/ha [20
tons/ac] of the sludge (90 metric tons/ha [40 tons/ac]  of the mix-
ture).   It is planned to add another 22 metric tons/ha  [10 tons/acj
of sludge within the first two years after the initial  application.
Thus, a total of 67 metric tons/ha [30 tons/acj of  sludge will  be
added to reclaimed spoil areas.  It is expected that this applica-
tion rate will prove to be lower than optimal for spoil  reclamation.
With a total spoil area of 50 ha [125 ac] , this will amount to  a
total sludge dry solids utilization of 3,400 metric tons [3,800
tons] at this particular mine.

     Another area of potential sludge usage is the  Watkins Project,
approximately 17 miles east of downtown Denver on Highway 70.  The
Watkins Project is a conceptual plan to develop largely untapped
reserves of lignite coal near Denver.  Under this scheme, the coal
resource would be combined with solid wastes and converted (gas-
ified)  into pipeline quality natural gas.  The energy source for
operation of the coal mine, the coal gasification plants and re-
clamation and restoration programs, as envisioned by the Mintech
Corporation, may potentially be derived from Denver sewage sludge
and solid wastes.  Briquettes pressed from mixtures of solid waste
(garbage) and liquid sludge could supply approximately 20 percent
of the  fuel feedstock.  Dried sludge may also be used as an alter-
nate energy source.

     The earliest projected date for project completion is 1981,
depending upon various financial arrangements and approvals by
State and Federal regulatory agencies.

     Irrigated Farms--

     Sludge application on irrigated farms will be the most sensi-
                               99

-------
five of the agricultural  reuse schemes, because of the intensive
food crop production on such farms.  It is important to note that
the sludge application procedures and rates described here are those
best suited for the specific site studied.  Impacts discussed in
Section V are similarly site specific.   Therefore, an examination
of the characteristics of each site is  necessary prior to embarking
upon a sludge application program.  Such examination should include
analyses of soil cation exchange capacity (C.E.C.), pH and back-
ground heavy metals.

     At the present time, barnyard manure is used on many irrigated
farms, particularly in sugarbeet fields.  Conversion to use of
sludge or supplementation of this material can be readily accom-
plished with existing equipment and procedures.

     Annual Application Rate Limitations--It is expected that an-
nual sludge application rates will be limited to the quantity which
provides nitrogen in amounts that can be taken up by the crops
grown on the farm.  A formula of this general  character requires
a number of assumptions,  regarding the  basic parameters determining
nitrogen balance.  The more significant of these parameters are:

     1.  potential annual uptake of nitrogen by each crop, U, in
         kilograms per hectare per year

     2.  total nitrogen content of applied sludge, M as percent
         of sol ids

     3.  proportion of crop nitrogen removed from the land at
         harvest, Cj

     4.  percent of nitrogen which is mineralized (made available
         to plants) in a  given year, c2

     5.  total background nitrogen in soil, p, in metric tons
         per hectare

     Using these values,  annual application rate, R, in metric tons
per hectare, is  given by  the formula:
R =
                              c1  U
                           1 ,000 c2 M
                                                      (Equation 1)
     A plot of this equation is shown on Figure 14, in which p is
assumed to be zero.  Under most conditions this is a reasonable
assumption for the first year of sludge application.  On a farm
which has received sludge or other nitrogenous organic materials
in past years, p can be approximated by assuming that 30 percent
                                100

-------
  H~D
3)
m
m
   c/>
m
m
m
   o —
        m
     m
            o
            H
    CO
    CO
     o

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            o
            LO
            O
                c
                T)
                o
                -n
                m
                o
O
                m
        DD
        -<


        T)
                                                  ALLOWABLE  SLUDGE APPLICATION  RATE

                                                 metric tons per hectare per  year  ( I st year)
                                                                         DRY L'AND WHEAT I

                                                                         SMALL GRAINS--

                                                                         WHEAT
                                                                                 BARLEY, OATS-
                                                                     	CORN, SORGHUM-

                                                                        //	SUGARBEETS
                                                                                                                     O
                                                    short  tons  per  acre  per year ( I st  year)

-------
of the nitrogen in applied sludge becomes  mineralized (made availa-
ble for plant uptake) in the first year, 15 percent in the  second
year, 10 percent in the third year and 5 percent in the fourth and
succeeding years.   While controlled experimental  data in this area
are rather sparse, this decay series provides  a tentative and con-
servative guide for protection against over-application.  Using
these assumptions  and further assuming that sludge contains 3.5
percent nitrogen on a dry weight basis, allowable application rates
over time are graphically portrayed in Figure  15.  For other sludges
with different sludge concentrations (other than 3.5 percent) the
plots should be adjusted proportionately,  i.e.,


                          R  =     R                  (Equation 2)
to obtain the proper application rate,  R^.

     Sludge application rates which are greater  than  the  rates
given in Figure 15 for a given crop will  result  in  leaching  of  ex-
cess mineralized nitrogen beyond the root zone and  eventually to
the groundwater table.  It has been estimated  by Pratt  that  it
takes from 10 to 50 years for excess nitrogen  to travel 30 m [100
ft] vertically in an unsaturated medium,  depending  on the inter-
vening soil types present (Reference 96).   The nitrogen balance
is discussed more fully in Appendix D.

     Total Sludge Application Surface Rate Limitation—The total
sludge quantity which may be permitted  on a piece of  land is lim-
ited by the heavy metals which can safely be tolerated  in the soil.
A quantitative guide on the tolerable amount of  sludge  which can
be allowed is that the total amount of  heavy metals introduced
therewith should not exceed ten percent of the soil cation exchange
capacity.  A formula proposed by the EPA (modified  to metric units)
in the tentative guidelines (Reference  79) suggests:

  Total Sludge (dry solids, metric tons per hectare)  =

         73,000 x Cation Exchange Capacity (meq/100 g soil)
      Zinc (mg/kg) + 2 Copper (mg/kg) + 4 Nickel (mg/kg)  - 200

                                                      (Equation 3)

The implicit assumption of this formula is that  copper  is twice as
toxic as zinc and nickel is four times  as toxic. Soils that might
receive Denver sludge in Arapahoe or Adams County may have a cation
exchange capacity of 20 meq/100 g.  Typically, Denver sludge con-
tains 1,145 mg/kg zinc, 808 mg/kg copper and 282 mg/kg  nickel
                               102

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                                              FIGURE  15
                                                    200
                                                  - 100
                                                        O
                                                        0>
                                                        O)
                                                        Q.
                                                        O)
                                                        O
                                                        O
                                                        0>
                                                        o.

                                                        (A
                                                        c
                                                        o
                                          50   70   100
                  TIME ,  years
NOTES:
1.  ASSUMING 3.5% N IN SLUDGE WITH 0.30, 0.15, 0.10,

    0.05 ••-• DECAY SERIES FROM YEAR 1 ON.

2.  RATES NECESSARY TO MINERALIZE (MAKE AVAILABLE)

    CONSTANT NITROGEN QUANTITIES FOR VARIOUS CROPS

    AND/OR LEACHING OF EXCESS N TO GROUNDWATER.

3.  1 Kg/ha = 0.892 Ib/ac




 ANNUAL  SLUDGE APPLICATION  RATES
                     103
ENGINEERING-SCIFNCR, INC

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(chemical characteristics of Denver sludge are given in Appendix D).
Equation 3 yields a total permissible sludge application of about
400 metric tons/ha [180 short tons/ac].   Comparing this representa-
tive total loading with annual  rates given earlier for irrigated
farms, it appears that sludge application can be conducted  on a
given piece of land for 20 to over 100 years (depending upon ap-
plication and uptake rates) before the limit is reached.

     It is very important that the limit should be computed for
each soil on each farm.  Average values  and representative  condi-
tions can be deceiving with respect to actual  field implementation
of a project.  For the purposes of this  environmental  impact state-
ment, values found on the farms studied  are used as a  means of
assessment of impact on those sites as reported in Section  V.  The
specificity of the impacts to the site cannot be overemphasized.
The applicability of these impacts to the entire study area is
valid only insofar as planning is concerned.   Design and implemen-
tation should be viewed from an entirely site-specific point of
view.  Using safe average application rates, if all  the 1985 pro-
jected sludge quantities were to be applied to irrigated farms,  a
total of about 3,000 ha [7,000 ac] of irrigated farms  would be
needed.

     Dryland Farms--

     As noted in Figures 14 and 15, wheat grown under  dryland
farming practices uses very little nitrogen due to the lower pro-
duction rates, compared with irrigated crops.   Therefore, sludge
application rates consistent with nitrogen uptake are  rather low,
ranging from less than one to three metric tons/ha [0.3 to  1.5
tons/ac] per year.  At such low rates, rather extensive areas of
application and, consequently, greatly increased operation  expendi-
tures are involved.  On the other hand,  due to the lower applica-
tion rates, the dryland farms can be utilized for sludge reuse over
a much prolonged period (over 300 years) before the total limit  of
heavy metals loading is reached.   Furthermore, impacts would occur
at a proportionately slower rate, providing greater opportunity
for mitigation and amelioration.

     Experimentation with methods of direct injection  of liquid
sludge at various depths has been conducted in the Denver-Boulder-
Fort Collins area and equipment is available from commercial  manu-
facturers (References 97 and 98).   These methods have  promise par-
ticularly for dryland farms with the lower application rate re-
quirements.   The effort involved in such methods is about equal  to
land scarification procedures widely utilized by farmers for water
conservation.  Sludge injectors achieve  both functions in the same
operation (Reference 97).
                                104

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     Application  of  air-dried sludge with manure spreaders or other
 similar  equipment can  be controlled to achieve proper application
 rates.   Due to  the relatively low rainfall rates and minimal culti-
 vation processes  in  the dry-farmed areas, it is expected that in-
 corporation of  sludge  within the soil root zone will be a rather
 slow process; loss of  nitrogen to volatilization would be greater
 and the  rate of breakdown of organic matter would be accelerated.

     If  all the 1985 projected sludge quantities were to be ap-
 plied to dryland  farms within safe application rates, a total of
 about 43,000 ha [100,000 ac] of non-irrigated farmland would be
 needed.   If non-cultivated range land is to be included in sludge
 application, adequate  areas exist within reasonable distances from
 the proposed distribution center.

     Home Gardens—

     The dried  sludge  could possibly be made available to the gen-
 eral public for use  in home gardens.  Users would purchase the
 sludge at the distribution center and apply it to ornamental plants,
 such as  lawns and flowers.  Although highly unadvisable, home gar-
 deners may choose to apply sludge to vegetable gardens.  Metro
 Denver could recommend appropriate usages of the sludge, similar to
 the criteria for  irrigated farmlands, but would not be able to con-
 trol or  restrict  ultimate uses of the sludge by the home gardener
 once the material  is in his or her possession.  Metro Denver also
 contemplates marketing the dried sludge (presumably fortified and
 sanitized) in bags for use by home gardeners in a similar fashion
 to the Milwaukee  "Milorganite" and the Rhode Island "Organiform."

 Sludge Disposal at Lowry Bombing Range (No Action)

     The present  sludge disposal practice involves a large-scale
 trucking operation from the Metro Denver Central Plant 40 km [25
 mi] southeast to  the Lowry Bombing Range.

     For the high-rate sludge applications, the transfer trucks
 are unloaded on a special ramp at the Bombing Range into an en-
 closed hopper which  in turn drains into smaller spreader trucks.
 The spreader trucks  convey the dewatered (10 to 16 percent solids)
 sludge to the application areas where sludge is dumped in a uniform
 layer (about 15 cm [6  in.] thick) atop the ground surface and left
 to dry partially.  The sludge is later plowed into the topsoil
 using moldboard plows  pulled by a track-type tractor along the
 contours.  Alternate contour strips are used to plow in the sludge
 while the  intervening  strips are cropped and used for pasture.
 A given  contour strip  receives sludge in thi? manner once every
nine months at a  rate of 67  metric ton/ha/yr [30 ton/ac/year].
As of 1977, each  contour had received 459 metric tons/ha
                               105

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(205 tons/acre).   It is  expected that if the agricultural  reuse
plan is fully implemented,  disposal  operations  in  the  Lowry
Bombing Range will  be phased  out.
      SLUDGE  IS SPREAD ON  LOWRY BOMBING RANGE BEFORE DISCING


      During  winter months when land application becomes impeded by
 ice  and  snow on the ground, this operation is temporarily replaced
 by direct dumping of the  sludge directly onto the soil  surface and
 intermixing  with soil at  a ratio of five parts soil  to  one part sludge,

      Sludge  Landfill ing—

      Landfilling sludge along with other municipal solid wastes is
 a widely accepted practice, generally used for ultimate disposal
 of the solid wastes.  Typically, partially dried sludge is dumped
 into the landfill and covered with other refuse.  However, under
 well-managed sanitary landfill ing procedures—increasingly in use
 in communities across the country—strict operating techniques are
 followed.  Foremost among these techniques is a sound site selec-
 tion process in which the environmental implications of candidate
 sites are exhaustively researched and compared.  The U.S. Environ-
 mental Protection Agency  has published a recent design and opera-
 tion manual  incorporating site selection, construction, operation
 and  maintenance procedures (Reference 98).  The methods and pro-
 visions  standard on truly sanitary landfills are aimed at odor
 control, protection of public health, groundwater quality protec-
 tion and prevention of various hazards.  Monitoring provisions are
 aimed at determination of long-term impacts and early warning of
                               106

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adverse impacts.  At the Lowry landfill,  sludge disposal  is  expected
to occur only during emergency periods when the normal  operations
are temporarily disrupted.  Also, if the  proposed  sludge  recycling
plan is somehow aborted, and if Metro Denver is also  barred  from
landspreading at the Lowry Bombing Range,  it is possible  that  sani-
tary landfilling would be the reasonable  alternative, at  least  in
the short run.  Metro expects that incineration would be  chosen as
the long-term solution.
                               107

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co
o

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w
 N
mm
H

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     This Section is the core of the EIS.
It is here that the impacts of the proposed action
are presented and discussed.
     Because of the highly site-specific nature
of the impacts, this Section is organized to empha-
size the most important issues likely to arise at
the most vulnerable sites.  It is divided into
three main parts.  First, impacts expected during
the processing, transfer, drying and stockpiling
of the sludge are analyzed.  Second, impacts at
the land application sites (sludge recycling areas)
are presented.  Finally, impacts at the Lowry land
disposal and landfill—which comprises the "no-
action" alternative—are discussed.

     Throughout, an attempt has been made to pre-
sent the impacted environmental parameters and
criteria in descending order of importance and in-
tensity of impact, as perceived under the existing
state of knowledge and as judged from the perspec-
tive of overall human welfare.  A great deal of
research in the field of land application of sludge
is currently in progress and is planned for the
future.  Therefore, many of the stated impacts must
necessarily be considered tentative in intensity
and, in some cases, in magnitude and direction, as
well.

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                           SECTION V

          ENVIRONMENTAL IMPACTS OF THE PROPOSED ACTION
INTRODUCTION

     The Metro Denver sludge management plan, proposing the re-
cycling of organic solids on land, is a relatively complex scheme
involving several treatment subsystems and numerous different
types of application sites.  Such complexity and diversity gives
rise to different types and intensities of impact, necessitating
separate and distinct evaluation in the decision-making process.
The reader who is interested in only one type of application site,
under a given local condition, is cautioned to read this draft EIS
with a special view to the specific sites and conditions discussed
under each impact category.  In the present draft, impacts are ar-
ranged in order of general severity and with particular reference
to the sites of sludge application where they will be encountered.

IMPACT OF SLUDGE PROCESSING, TRANSFER,
DRYING AND DISTRIBUTION

     The environmental impact of the proposed action was partially
assessed in the facilities planning process and reported in Febru-
ary 1975 (Reference 8).  A summary of environmental impacts of
sludge drying and distribution activities at the alternative sites,
prepared by the facilities planners (CH2M Hill) is presented in
Appendix G.  Impacts attributable to the reocmmended sludge drying
and distribution site (B2) are summarized in this Section.

     Impacts of processing and transfer (pipeline) will be rather
temporary and slight compared to those of the sludge drying/distri-
bution site and those at the application sites.

Soil Loss

     The excavation of 240 hectares [600 acres] of land to 1.5-m
[5-ft] depth for the drying basins would effectively disturb all
soil in this large area.  Even though the disturbed soil mass
would remain at the drying/distribution site, soil profile charac-
teristics, structure and other physical properties would be so
thoroughlv destroyed or modified that an agricultural substratum
                             109

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would no longer exist.  Furthermore, the soil mass thus removed
would cover over other soil areas, gradually changing their physi-
cal, chemical and microbiological characteristics.  Thus, an irre-
trievable loss of the soil resource from the site would occur.

     Soils in the proposed drying/distribution site are largely
in soil capability unit Ill-e (irrigated) or IV-e (nonirrigated).
This indicates that, with a moderate degree of management control
(especially to prevent erosion), the soils can be generally produc-
tive (particularly under irrigation).  Soil impacts arising from
experimental programs on the distribution site will be highly vari-
able due to the wide range of application rates and methods typi-
cally used in a controlled experiment.   It is expected that these
experiments will be conducted with adequate monitoring of the vari-
ous sludge components and environmental  parameters during and be-
yond the experimental period.  Results  obtained from monitoring
programs should provide the necessary information for minimizing
and mitigating adverse impacts.   The size of the experimental
areas will be generally limited, and accumulations of excess quan-
tities of heavy metals in plots  receiving high application rates
will eventually be dispersed, in part to surrounding soils (by cul-
tivation practices) and in part  to underlying strata.

     The impacts of sludge reuse on agricultural land per se are
discussed in later parts of this Section.  Many of the statements
made with reference to off-site  impacts  are equally applicable to
conditions on the distribution site insofar as irrigated crop pro-
duction is concerned.

Water

     Groundwater Quality--

     Due to the low permeability of soils in the distribution site,
and the proposed basin lining, it is expected that water movement
toward the groundwater reservoir will be very slow.   Notwithstanding
the slow initial rates of water  (and sludge leachate) movement and
the further clogging of soil  particles,  salt-laden water will  even-
tually move past the upper soil  strata.   In time, this drained water
and the solutes it carries will  percolate into the water table and
deteriorate groundwater quality.  It is  expected that the extent of
groundwater pollution from this  source will be significant consider-
ing the proposed 240 hectares [600 acres] of sludge drying basins.
With a total  dissolved solids concentration of 3,000 to  6,000 mg/1,
the percolate is a threat to  groundwater quality.   Both  the inor-
ganic components and the stable  organic  portion of this  leachate
can damage the groundwater quality and thus gradually reduce bene-
ficial  uses of the water.   The contamination of groundwater by
                              110

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nitrates is discussed under Public Health, below.

     The soils in the proposed drying basins have  a permeability of
3.3 x 10~4 to 1.3 x 10-3 cm/sec [0.008 to 0.03 in/hr].   Those soils
with higher clay contents can be compacted to give a permeability of
1.0 x 10~7 cm/sec.  Metro will be required by EPA  to line all the
basins with a layer of clay about 30 cm [1 ft] thick compacted to
provide this permeability.   This clay layer will be covered by sand
or a similar cover material to prevent the clay from drying and crack-
ing and to prevent damage during sludge removal operations.

     Assuming that at any given time, half the basins are wet enough
to release water for percolation, and assuming a  total  dissolved solids
concentration of 5,000 mg/1, the quantity of leachate and salts moving
toward the groundwater can be calculated.   This amounts to about
38,000 cu m [1.3 million cu ft] of leachate carrying almost 190 mt/yr
[210 tons/yr] of salts towards the groundwater table.   This estimate
is conservative, because it is quite likely that clogging of the
soil by sludge particles will decrease the permeability to below
this level.  Even so a substantial quantity of leachate will move
slowly toward the groundwater.  Because of the slow rate of leachate
movement, it will take 20 to 100 years for the water to reach the
groundwater table, and a similar length of time to terminate this
pollution.  Thus, a lack of evidence of water pollution in the initial
decades of operation cannot be reviewed as a sign  of absence of im-
pact.  The groundwater mound eventually created will move horizontally
and may affect wells in the vicinity.

     Because of the potential severity of this impact,  more data has
been collected and analyzed since the release of  the draft EIS.  This
analysis is presented in Volume II, Issues II- 112.

     Other, partial, solutions include separation  of decant, use of
underdrains, pumping leachate from the ground and  vacuum filtration
of the sludge at the site before air drying.  Mitigation measures
against this severe impact are discussed in Section VI.  Monitoring
of leaching water quality and movement rates will  be necessary.

     Surface Water Quality--

     Surface water protection will be effectively  provided with the
provision of drainage channels and earthen dams with adequate impound-
ment areas.   These features have already been incorporated into the
facilities plan for the drying and distribution area.   Provision is
made for analysis of impounded water for BOD, COD, biological indi-
cators, nitrogen, total  dissolved solids and other parameters, as
set forth by agencies regulating discharges to surface water.  Contami-
nated water would not be discharged to streams but would instead be
used for surface irrigation (See above for groundwater quality effects)
An exception could occur under extreme rainfall events  (See Volume II,
Issue II-6.
                                 Ill

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      Hater  Rights —

      In  the  process of transporting liquid sludge to the drying and
 distribution  center, and during the periods of purging the pipelines
 with  secondary effluent, about 1.1 - 1.7 mgd of water will be carried
 from  the Central Plant to the Adams County Site.  This is an increase
 over  the approximately 130,000 gpd currently disposed at Lowry, but
 will  still  be less than 1 percent of the total plant discharge.  It
 is  anticipated that this removal of water will have some impact on
 appropriations downstream of the Central Plant discharge into the South
 Platte River.  Under the existing system of appropriations, the treat-
 ed  and discharged sewage would belong to senior consumptive users
 downstream.   However, under Colorado Supreme Court decisions, water
 transferred  interbasin belongs to the diverter and can thus be reused.
 In  this  particular case, the Denver Water Board is the owner of the
 water transferred from the western slopes and will presumably allow
 Metro to use  these additional waters as part of the treatment process.
 This  issue  is discussed in Volume II, Issue 1-3.

 Public Health

      General--

      Biological health hazards associated with sludge include patho-
 genic bacteria, viruses and parasites which may have survived the ini-
 tial  treatment process.  The major bacterial diseases have been con-
 trolled  well  by traditional treatment processes.  Statements about
 viral health  problems must be more guarded and uncertain because of
 the difficulty in measuring viruses and the lack of standards for vi-
 rus levels.   In general, however, viruses are more short-lived than
 bacterial pathogens (References 39,80).  Intestinal parasites may also
 be  present  in various forms in the sludge.   Parasites and their eggs
 or  cysts are  only partially destroyed by traditional treatment processes.
 Other biological hazards associated with sludge are such disease-
 carrying vectors as flies, mosquitoes and rats.

      Threats  to health from chemicals with the sludge are generally
 chronic  and indirect.  Before the chemicals can reach the human body,
 they  usually  pass through at least two biological systems (plants and
 livestock); acute effects can be noted at these intermediate stages.
 The treatment process itself is a relatively sensitive biological sys-
 tem which can be upset at the activated sludge or anaerobic digestion
 stage if high concentrations of certain elements enter the system.
 Chemicals applied to the soils would affect the crops if they built up to
dangerous levels.   Present standards for heavy metals are based on  deter-
minations of  the levels at which there is toxicity to plants (Reference 79)
The human health effects of long-term, low-level consumption of these
materials cannot be determined at this time.  Therefore,  potential  adverse
effects  on human health cannot be overemphasized.  Traditional  sludge
                               112

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treatment processes do not reduce hazards to human health from heavy
metals in the sludge.  An interim primary standard has been established
by the EPA for nitrates at 45 ppm (as nitrate) in drinking water
supplies.  If levels are kept below this threshold, a safe water sup-
ply is generally presumed.  Regulations also exist to control  the
levels of persistent organic chemicals in certain components of
the food chain.  (See Volume II, Issue V-l.)

     Health Protective Factors Associated
     with Sludge Management—

     There are a number of factors which help to ensure that the
potential health hazards associated with sludge will not be real-
ized to the extent of creating actual health problems.  The an-
aerobic digestion process destroys many of the human pathogens.
Fecal coliforms, an indicator of pathogens, are reduced by 97  per-
cent or more in a well-run anaerobic digester (Reference 79).   An-
aerobically digested sludge is generally considered biologically
safe to use on farm crops without further treatment (Reference 81).
Eggs and cysts of enteric parasites are able to survive the diges-
tion process and remain alive for relatively long periods of time.
The subsequent drying and soil incorporation processes are deadly
to pathogens due to the exposure to ultraviolet light, desiccation
and unsuccessful competition with the indigenous soil organisms.
However, many parasites have long survival periods in tne soil in
cyst form or in the egg stage.  Long-term storage of sludge is an
effective reducer of pathogenic organisms (Reference 82).  Storage
of liquid digested sludge for 60 days at 20°C [68°F] or 120 days
at 4°C [40°F] has been reported to be a successful pathogen reduc-
tion measure (Reference 79).

     Pathogens--

     Because potential hazards exist in the use of recycled, di-
gested sludge, proper precautionary measures must be provided to
assure that no significant harm to human health will result from
this practice (Reference 39).

     Pathogenic microorganisms will not pose a significant public
health threat at the distribution site if the proposed project is
operated as designed.  The project will include a soil and ground-
water monitoring system to monitor environmental quality.  Six on-
site wells around the perimeter of the drying site and other near-
by wells will be used to monitor approximately 15 biological and
chemical parameters.

     The survival times of various pathogens associated with sew-
age sludge are given in Table 20.  Ascaris ova (eggs of a para-
sitic worm) are particularly long-lived and thus are good indica-
tors for monitoring the general sanitary quality of the sludge.
salmonella, relatively common pathogenic microorganisms, are also

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Table 20.   SURVIVAL TIMES  OF PATHOGENIC MICROORGANISMS IN VARIOUS MEDIA
Organism
Ascaris ova



Cholera
vibrios







End amoeba
histolytica
cysts


Enteric viruses




H.okworm larvae

Leptospira

Salmonella typhi















Medium
soil
soil
plants and
fruits
spinach, lettuce
cucumbers
non-acid vegeta-
bles — onions,
garlic, oranges,
lemons, lentils,
grapes
rice and dates

river water
soil

tomatoes
lettuce
roots of bean
plants
soil
tomato and pea
roots
soil

river water
soil
dates
harvested fruits
apples, peats,
grapes
strawberries
soil
soil
soil

pea plant stems
radish plant
e terns
soil

lettuce and
endive
Type of application
not stated
sewage
ACb

AC
AC
AC




infected
feces
AC
AC

AC
AC
AC

AC
AC

infected
feces
AC
AC
AC
AC
AC

AC
AC
AC
AC

AC
AC

AC

AC

Survival time
2.5 years
up to 7 yearsa
1 month

22 - 29 days
7 days
2 days




hours to
3 days
8-40 days
8 days

18 - 42 hours
18 hours
at least
4 days
12 days
A - 6 days

6 weeks

5-6 days
15 - 43 days
68 days
3 days
24 - 48 hours

6 hours
74 days
70 days
•t least
5 days
14 days
4 days

up to
20 days
1-3 days

                                 114

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           Table 20 (continued).   SURVIVAL TIMES OF PATHOGENIC
                      ORGANISMS IN  VARIOUS MEDIA
Organism









Salmonella,
other than
typhi




Shigella




Tubercle bacilli



Medium
soil
soil
lettuce
radishes
soil
soil
son
cress, lettuce,
and radishes
lake water
soil
vegetables
tomatoes
soil
potatoes
carrots
cabbage and
gooseberries
streams
harvested fruits
market tomatoes
market apples
tomatoes
soil
grass
sewage
soil
Type of application
AC
AC
infected
fee PS
infected
f eces
infected
f eces
AC
AC
AC
AC
AC
AC
AC
sprinkled with
domestic sewage
sprinkled with
domestic sewage
sprinkled with
domestic sewage
sprinkled with
domestic sewage
not stated
AC
AC
AC
AC
AC
AC
?
?
Survival time
2 - 110 days
several months
18 days
53 days
74 days
5-19 days
70 - 80 days
3 weeks
3-5 days
15 - 70 days
2-7 weeks
less than
7 days
40 days
40 days
10 days
4 days
30 minutes -
4 days
minutes -
5 days
at least
2 days
at least
6 days
2-7 days
6 months
14 - 49 days
3 months
6 months
      warm, moist conditions not encountered in the Denver area.

 AC •* Artificial Contamination
Source:  Evaluation of Municipal Sewage Treatment Alternatives (Reference  80).
                                     115

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fairly hardy and therefore  good  indicators  for  monitoring the
safety of the sludge.

     Because of the remoteness of the  site, human  exposure to the
drying sludge will  be  limited, further ensuring that no  significant
health impacts will result  from  the  proposed project.  However,
public access to the drying beds  should be  limited while the sludge
is drying.

     An adequate soil  barrier/filter exists for protection of the
groundwater from any pathogenic  microorganisms  in  the sludge.  Sur-
face water runoff will be contained  behind  earthen dams  on sites
generally above the present water table, and access to this water
will be controlled to bar potential  health  and  safety problems.

     Nitrates--

     It is probable that significant quantities of nitrogen, in the
soluble nitrate form, will  move  with the leachate  water  from the
bottom of the sludge drying basins toward the groundwater table.
The precise quantity and rate of movement of the nitrates depend
on several factors (denitrification  rates under anaerobic condi-
tions, mineralization of organic nitrogen forms by microorganisms,
oxidation of the ammonia form under  aerobic conditions,  etc.), each
of which may be occurring at different times and places  in the ba-
sins at different rates.  Once nitrate begins to migrate beneath
the basins, it will remain unchanged and may gradually increase in
concentration in the groundwater reservoir, eventually exceeding
the 45 mg/1 standard.   High nitrate  (H0~3) concentrations in drink-
ing water supplies have been linked  to methemoglobinemia, a rare
"blue baby" disease resulting from reduction of the oxygen-transfer
capacity of blood in infants.  The problem of nitrate, coupled with
the other salts discussed above  under groundwater quality, can be
reduced by lining the basins and other measures enumerated.

     Vectors--

     Gnats, flies and mosquitoes are the most common vectors of
pathogens expected to be present in  the vicinity of the  drying ba-
sins.  It is important that qualified specialist entomologists be
consulted for the identification of  specific species of insects
that_will emerge in the basins.   While gnats and flies will remain
within one km [^0.6 mile] of the basin boundaries, mosquitoes can
travel (even under severe wind conditions)  up to 40 km [25 miles]
                               116

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away.  Mosquitoes and some species of flies can transmit certain
diseases; nence, it is important t.iat integrated insect control
measures be instituted with a view to maximizing natural control
mechanisms.  The drying basins (240 hectares [600 acres] in size)
will provide a large, permanent ecosystem with a wide range of
moisture, food supply, breeding environments and surrounding vege-
tation.  It is difficult to predict the actual  invertebrate spe-
cies that will inhabit this new ecosystem.  However, it is possible
that a few species will predominate in the absence of natural  ene-
mies.  Only after accurate identification of the prevalent species
can proper control measures be recommended.  Hence, consultation
with specialist entomologists is important at tne initial  stages
of operation of drying basins.  It may be necessary to add safe
insecticides (such as organophosphates) to sludge at the treatment
plant.

     Experimental sites for liquid sludge application may  also at-
tract some insects and require control measures.  Vectors  such as
rates and mice are usually not attracted to drying basins  or to
stockpile areas, but small burrowing animals will  inhabit  the  basins
The proposed activities in the experimental areas are therefore not
expected to influence either the presence or the size of population
of such vectors.

Loss of Habitat

     Animal species diversity at the proposed site will  be somewhat
reduced due to the removal of habitat during the construction  of
facilities and the excavation of vast areas for the sludge drying
basins.  Some species, including mice, voles and rabbits,  may  re-
turn to cultivated portions of the site when crops are growing.
Some of tne birds presently found on the proposed site may return
if the level of human activity and the types of crops grown in
tnese areas are not incompatible with tneir resting and feeding
requirements.  At the time of facilities planning investigations,
consultants found "no nesting areas which might be disturbed"  (Ref-
erence 8).  Tne disturbance to vegetation along the 40-km  [25-mile]
pipeline and within the 800-hectare [2,000-acre] distribution  site
would :iot be of a drastic nature because most native vegetation
nas long oeen replaced by farming.  Vegetation will be readily re-
stored along the pipeline.  At the distribution center, all vege-
tation at the site of tne drying basins and stockpile area will
be removed for tne indefinite duration of the project.  At the
experimental areas, a presumably well-managed farming operation
will replace tne existing dryland farms.

Air Duality

     The proposed project is not expected to cause a significant
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air quality impact on the alternative drying and distribution cen-
ter sites during any but the most severe windstorms.   (Odors are
discussed as a separate topic in the pages following.)

     During operation of the sludge  drying center,  considerable dust
will originate primarily from vehicles  driving  on the  dirt  roads of the
site.   A problem lesser in magnitude but perhaps greater  in public
awareness is the dust which will  be  blown from  the  dried  sludge piles.
Because the sludge particles will  have  been  thoroughly dried before
becoming airborne, little odorous, volatile  material will be present
and pathogenic organisms will  have been  largely desiccated.   However,
spores and certain parasite eggs  can survive in dry conditions  for
relatively long periods.

     Normal winds will not spread significant amounts  of  dried
sludge, though the strong (over 11 mps  [24 mph]) winds which oc-
casionally occur (during about two percent of the year) will
spread the dried material, probably  to  the east or  south  (see Fig-
ure 9 for wind distribution patterns).   It is difficult to  esti-
mate the amount of material blown during such winds.   During most
wind storms, the contributions from  the sludge piles  probably will
not be quantitatively or qualitatively  significant  because  of the
cohesive, fibrous nature of the dried stockpiled material.

     Air pollutants generated during transport and  delivery of
the dried sludge will not be of great enough quantity  to  signifi-
cantly affect air quality.  Impacts  on  air quality  were determined
assuming "worst case" conditions during peak periods:   30 truck
trips/day and 200-km [120-mile] maximum roundtrip (Reference 77).
From these figures and emission factors appropriate for the trucks
(Reference 99), it is calculated that the maximum amounts of air
pollutants generated during the spring  and fall peak  delivery per-
iods are:  hydrocarbons, 1ft kg/day [23  lb/day]; carbon monoxide,
70 kg/day [150 lb/day]; nitrogen oxides, 110 kg/day [240  lb/day].
This will not cause a significant air quality impact,  being about
0.03 percent of the pollutants emitted  daily in Air Quality Con-
trol Region 2 (see Figure 8) (Reference 38).

     Ammonia nitrogen (as N) accounts for three to  four percent
of the dry weight of the liquid sludge  (Reference 55); 50 percent
of this will be lost to the atmosphere  during drying  (Reference
88).  On the basis of design sludge  quantities, this  amounts to
approximately 620 metric tons [683 tons] per year of  nitrogen-
containing gases emitted.  Liquid sludge loses  about  one-fourth
as much ammonia nitrogen and therefore  will  emit less  of  this ma-
terial to the air.  These emissions  have caused no  known  air qual-
ity problems in similar operations in Los Angeles County, Califor-
nia (Reference 100).  It is doubtful that this loss in ammonia
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nitrogen will have a significant effect on air quality (Reference
101).

     oecause there is no air quality standard in Colorado for am-
monia emissions, odor is the only parameter of concern with regard
to this yas.  An emission permit is required from the Air Pollution
Control Division of the Colorado Department of Health under Regula-
tion No. 2, promulgated by the Colorado Air Pollution Control Com-
mission.   Included in this permit would be a definitive plan for
the control of odorous emissions.  In addition, a complete inven-
tory of quantities and rates of emission is required for all odor-
ous compounds being emitted from the site.  (Odor conditions are
described  separately below, and are discussed in Vol.11, Issue II-3),

     The Department of Health further stipulates that significant
emissions  be modeled to estimate maximum concentrations and their
locations  downwind of the site.  Similarly, it will  be necessary
to include a plan for the control of fugitive dust.

     Odor—

     Two sets of observations have been gathered on  odors which
night possibly enter the environment surrounding the proposed
sludge drying and distribution center.  One test was carried out
by the Metro Denver staff in cooperation with Colorado State Uni-
versity on a system similar to the proposed new system.  A second
set of observations of interest was gathered by the  Tri-County
District Health Department on the sludge drying system presently
operating  at the abandoned Lowry Bombing Range.

     In the first test, the Metro Denver District staff constructed
and monitored six 8-m by 9-m [25-ft by 30-ft] sludge drying basins
at the Colorado State University research farm at Fort Collins.  A
panel of Colorado State University faculty members and wastewater
treatment  plant operators was assembled.  The odor tests were taken
within a few meters of the basins over a period of 6 to 12 months.
The panel  was asked to describe the odor level  in terms of the fol-
lowing numerical  rating system:

                    0  -  undetectable
                    1   -  faintly detectable
                    2  -  detectable
                    3  -  objectionable
                    4  -  very objectionable

The basins took from 6 to 12 days to reach the No. 1 level.  The
panelists  noted that the odors did not carry very far beyond the
basins.
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      The results  of  the  tests  were  confirmed  by  Metro  representa-
 tives during  a field trip  to drying  basins  in Sioux  Falls,  South
 Dakota;  Topeka and Wichita, Kansas;  and Tulsa and  Oklahoma  City,
 Oklahoma.   None of those facilities  had serious, continuing odor
 problems.   However,  odors  were a  problem where inadequate diges-
 tion occurred due "to system failure  (Reference 8).

      The present  Metro Denver  operation at  Lowry Bombing Range is
 monitored  for odors  and  other  factors  by the  Tri-County District
 Health Department.   The  Department  also receives any complaints
 concerning odor problems of the operation.  There  are  about 10
 complaints a  year concerning odors  emanating  from  the  site.   These
 complaints come from areas up  to  10  km [six miles] from the Lowry
 site.  However, complaints coming from this distance were found by
 the Health Department to be unjustified ones:  "The  range of what
 were considered justified  complaints was one  or  two  miles [two to
 three km]  from the Site" (Reference  39).  The complaints usually
 conincided with unusual  meteorological conditions  and/or system
 failure.

      Some  past odor  problems (such  as  the one occasioning the pub-
 lic hearing of 20 June 1972) were due  to system  inadequacies which
 were subsequently corrected.   About  80 percent of  the  complaints
 were found by the Health Department  to be due to other odor sources
 in the area,  such as the landfill operation at Lowry and the gas
 processing plants in the vicinity.   The remaining  20 percent of
 the complaints occurred  during unfavorable  weather or  operation
 breakdown  (Reference 39).

      Anaerobically digested sludge will be  less  odorous than the
 material presently deposited at the  Lowry site.  After the  sludge
 has been dried almost all  of the  volatile,  odorous materials will
 have left  the sludge.  During  normal operations, some  odors will
 nevertheless  be noticeable near the  drying  beds.   During digester
 malfunctions  (souring),  severe odor  problems  may be  expected if
 sludge is  pumped  to  the  site.   If this occurs, the malodorous sludge
 will  be  injected  at  the  site at agronomic rates.

 Noise

      Traffic,  aircraft and farm equipment comprise the main  sources
 of  existing background noise in the  vicinity  of the  proposed  drying
 and distribution center,  with an average noise level  of 35 decibels
 on  the A scale  (35 dB-A)  and a  maximum of 60 dB-A [Reference  8).
 It  is expected that  the site will  be designed  in such a way that
most of the noise-generating activities will occur at the center of
the 800-hectare [2,000-acre] site and thus  be surrounded  by experi-
mental fields.  Further,  it is  possible to equip all  internal com-
bustion engines with  noise  mufflers, reducing noise to  80 dB-A at
15m [50 ft].
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     Noise levels are expected to rise on Irondale Road with in-
creasing truck traffic, particularly during the heaviest periods
of sludge application.  These noises, as well  as all others dis-
cussed above, would occur only during the least noise-sensitive
daylight hours and would not disturb the comfort of residences or
pose a health threat to operators or other persons on the site.

Energy Use

     Metro Denver Sewage Disposal District No. 1 used about 50 mil-
lion kilowatt hours (KWH) of electricity for its total  operations
in 1975 (Reference 73).  On a per capita basis, this amounts to
about 50 KWH/person/year, which compares to a  total per capita
energy consumption in the United States of about 100,000 KWH/year
(References 74,75).  The current sludge handling and disposal  sys-
tem has total energy costs, for electrical power and fuel, equiva-
lent to roughly 20 million KWH of energy (References 8,55,70), or
20 KWH/person/year.

     Viewing the energy required for sludge handling and disposal
in the perspective of the total energy use within the District's
service area, sludge accounts for about 0.02 percent of the total
energy consumption in that region.  Viewed in  absolute terms,  it
is roughly equivalent to the total annual energy consumption of
70 homes.

     Energy Value of Sludge Nutrients—

     An energy parameter of significance is the amount of energy
required to produce and ship fertilizer in the area.  For produc-
tion of the three macronutrients essential for fertilizers:  ni-
trogen, phosphorus and potassium, costs to the consumer that are
due to energy costs are estimated to be 50, 25 and 30 percent,
respectively (Reference 76).  Assuming that the nutrient elements
are available in proportions of two nitrogen,  one phosphorus and
no potassium in Metro Denver sludge, the weighted average energy
equivalent of the nutrient value of the sludge becomes 40 percent.

     If recycling of nutrients in the sludge is successfully
achieved, a saving will be realized that is equivalent to the en-
ergy requirement for mining, manufacture and transport of commer-
cial  chemical fertilizers which otherwise would have been needed.
Assuming (a) a nutrient value benefit of $28/metric ton [$25/ton]
for Metro Denver sludge (on the basis that nitrogen is the only
nutrient of value, with five percent of the dry matter in the
sludge worth $0.55/kg [$0.25/1b]); (b) design  production of 97
metric tons [107 tons] of dry sludge per day,  and (c) an energy
factor of 40 percent of the total fertilizer cost, an energy equiv-
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alent of about $400,000/yr is obtained.  At $0.02/KWH, this trans-
lates into energy savings of about 20 million KWH per year.

     Energy Produced in the Digestion Process--

     Methane gas is generated in the anaerobic digestion process
at the rate of nearly one cu m/kg [15 cu ft/lb] of volatile mater-
ials destroyed in the digesters.  The energy value of methane thus
produced will be almost 70 million KWH/yr using conservative as-
sumptions in basic production rates.  Since an equivalent of about
20 million KWH will be used annually for heating the digesters, a
net gain of about 50 million KWH/yr would be realized if energy-
conversion equipment (boilers, steam turbines, etc.) were to be
available for utilization of the excess energy.  At this point,
however, such equipment is not envisaged in the facilities plan;
therefore, this rather large energy item is not included in the
total energy picture.

     Energy Used in Transport of Sludge—

     Another major energy economy can be achieved through the more
efficient transportation system (in comparison to the Lowry dispos-
al operations) designed for the recycling project.   About 680,000
liters [180,000 gallons] of diesel fuel per year are consumed in
the Lowry operation, assuming 35 truck trips/day, 80-km [50-mile]
round trip and 1.5 km/1 [3.5 miles/gal] (References 55,77).  This
energy is equivalent to nine million KWH/yr and is  included in the
total energy figure given above for the present operation of the
sludge handling and distribution systems.

     By contrast, only about 80,000 liters [20,000 gallons] of
fuel per year would be required to deliver the present sludge load
to the land application areas.   Net savings  accomplished  by the  new
transport system (including  the  sludge  pumping  energy  requirement)
over the  Lowry operation  amount  to about  eight  million  KWH/yr.

     Energy Balance in Sludge Transport to Farms—In order for the
shipping of sludge, from the drying and distribution center to re-
use areas, to be economical,  the cost of  shipping must not exceed
the price of equivalent fertilizer delivered at the reuse site,
This assumes no value for the soil-structure-enhancing benefits of
sludge recycled to  land.   Assuming further that nitrogen is the
only constituent of value in  sludge,  maximum distance—beyond which
shipment  of sludge  would  be  uneconomical—is obtained  by:


                          D  = fSti                (Equation 3)
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in which:  D = distance from the distribution center to the
               ultimate application area,

           F = fertilizer cost,
           N = fraction of nitrogen in the sludge dry solids,

           W = fraction of total solids in the sludge shipped,

           S = specific weight of stockpiled sludge, and
           Y = volumetric unit transport cost.

With:      F at $0.55/kg [$0.25/lb] of elemental  nitrogen,

           N at 0.05, i.e., five percent of the dry matter,

           W at 0.50, i.e., 50 percent of the sludge,
           S at 560 kg/cu m [35 Ib/cu ft], and
           Y at $0.08/cu m-km [$0.10/cu yd-mile],

the breakeven distance, D, is calculated to be nearly 100 km [60
miles].

     In summary, it can be seen from the discussions presented
above that a total  energy saving of at least 28 million KWH/year
could be realized if a successful  sludge recycling program  were
instituted to replace the present system:  eight million through
abandonment of the Lowry operation and 20 million from fertilizer
recycling revenues.  This is equivalent to the average annual en-
ergy consumption of 98 homes, or about 0.03 percent of the  total
energy consumed within the District boundaries in a year.

Aesthetics

     The visual impact of the proposed sludge drying site,  as de-
signed, will be perceptible mainly from within the site and from
above  (from aircraft).  The demonstration plots will be visible to
the passing motorist from Irondale Road, the most heavily travelled
road bounding the site (though even this road carries only about
210 vehicles per day).  The beds are, however, about 400 m [1300
ft] from Irondale Road and generally slope away from the road so
they will be relatively unobtrusive.  It is expected that thae  site
of the drying basins may be unpleasant to those associating the site
with the fecal origin of sludge.  Otherwise, the distinctive geo-
metric patterns formed by the basins (schematically presented on
Figure 13) and stockpile windrows could provide an interesting  visual
contrast (particularly from the air) to adjacent farmland patterns.
The association of the project with energy and resource conservation
will  further improve its aesthetic status in the minds of people
who are aware of the limits of our planet.
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Plant Operation and Plant Effluent Quality

     Because Metro is installing anaerobic digesters at the Metro
Central Plant, a different strength waste stream will result com-
pared to the present system.  In a wastewater treatment plant using
digesters, supernatant from the digesters is often recycled to the
plant.  This recycle stream can put an additional treatment burden
on the plant operation from addition of suspended solids, BOD, am-
monia and other substances.

     With the Metro land recycling proposal, the digester super-
natant would be pumped along with the digested sludge to the drying
and distribution site.  This proposal would therefore leave the re-
cycle situation at the Metro plant comparable to what it is now.
However, if the use of the Lowry Bombing Range were continued for
disposal (and presuming that the present operation of vacuum filter
and truck haul were also to be continued with digested sludges) the
Metro Central Plant would experience additional  loads on the liquid
treatment portion of the plant.  A rough estimate of the additional
load would be as follows:  suspended solids: 10 to 15 percent, BOD:
3 to 6 percent, and ammonia: 4 to 8 percent, assuming both Metro
and the Northside plants were to recycle or add supernatant to the
plant.  The first two constituents would probably be further treated
in the plant process and might not affect effluent quality.  Ammonia,
however, could pass through existing plant treatment units unchanged
and increase ammonia loadings to the South Platte River.  Any alter-
native involving recycled supernatant to the wastewater plant would
have this effect.

     The tradeoff between the Metro proposal and any alternatives
involving recycle to the plant involves the additional  treatment that
may be necessary at the drying site to handle the supernatant and
additional excess water in the digested sludge.   Cost estimates for
various control methods which may be used to prevent migration of
soluble nitrate in the sludge water into the groundwater are present-
ed in Volume II, Issue IV-2.

Natural Resources

     While the proposed action will  conserve a presently wasted re-
source of significant potential  value, it will  require use of fuel
for transport and application of sludge to land and will necessi-
tate disturbance of the soil resource on some 240 hectares [600
acres] of the proposed drying basins and stockpile areas.

     Organic Matter and Plant Nutrients

     The single most  important impact of the proposed action is
the conservation of the soil-conditioning/fertilizing capability
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of sludge.  Within the framework of limitations discussed in Sec-
tion IV, sludge comprises a valuable resource whose magnitude is
only now becoming apparent to the general  public.   Depending on
process train and application type, the total nitrogen value alone
of Denver sludge can range from $4 to $4.6 million per year under
present prices and values.  Sludge contains phosphorus in abundant
quantities as well as minor amounts of all other essential  ele-
ments.  It also has the ability to improve soil conditions  for
plant growth.  However, it lacks adequate  potassium.   It  is  ex-
pected that the money-equivalent value of  sludge will  increase
sharply in future years as fossil fuels (primary sources  of com-
mercial nitrogen fertilizers) become ever  more scarce  and other
shortages of natural resources become more apparent than  at
present.

     Use of Fuel for Transport of Sludge—

     As discussed above under Energy Use,  the fuel  required under
the proposed action is far less than that  used for present  opera-
tions at the Lowry Bombing Range site.  Nevertheless,  it  is a sig-
nificant commitment of resources.

     Soil —

     Disturbance of soil profiles at the sludge drying basins has
already been discussed in the early part of this Section, under
Soil Loss, and need not be restated here.

Archaeology and History

     The proposed project should not have  an adverse impact on
either the archaeologic or the historic characteristics of  land
affected by the proposed project.  Land underlying the site of
the anaerobic digesters has already been developed, as has  the
land adjacent to the proposed pipeline route.  Furthermore, there
was no surficial evidence at the proposed  drying basin site to
indicate underlying archaeologic sites (Reference 3),  and no his-
toric sites have been designated in that area (Reference  43).

     While all evidence indicates that the proposed project will
not jeopardize archaeologically or historically important sites,
the remote possibility exists that heretofore unknown  sites will
be discovered during construction activities connected with exca-
vation of areas for the installation of anaerobic digesters, with
laying the pipeline and with construction  of the drying basins.
In the event of such a discovery, the Colorado State Antiquities
Law should be reviewed and its provisions  implemented. The par-
ticular significance of this law in relation to the National
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 Historic Preservation Act of 1966 and the Archaeological and His-
 toric  Preservation Act of 1974 should be recognized in making pro-
 vision for the possible discovery of archaeological and historic
 resources* More discussion of archaeological issues is found under
 Issue  1-4.
 Land Use

     Land uses within the immediate boundaries of sites to be used
 for the installation of the anaerobic digesters, pipeline route
 and drying basins will change as a result of implementation of the
 proposed project.  These changes will be compatible with surround-
 ing land use activities and will not conflict with relevant land
 use plans or zoning regulations.

     Installation of anaerobic digestors at the Metro Denver Cen-
 tral Plant facility will cause an internal  land use change.  This
 change will be compatible with the present use since plant opera-
 tion will not change and use of the land will continue to be for
 sewage processing.

     The proposed pipeline route, lying beneath the roadway right-
 of-way areas, will not precipitate adjacent land use changes.  Ex-
 cept for other utility and municipal service lines which lie be-
 neath  these areas, the land is presently vacant; addition of the
 pipeline will leave the status of the land  unchanged.

     The agricultural area to accommodate the sludge drying and
 distribution site will change in use, but this change will be com-
 patible with surrounding land uses since the project will  provide
 fertilizer for agricultural use.  Because of this function, the
 proposed location of these basins is consistent with Adams County
 land use plans and with County zoning regulations which seek to
 perpetuate both agricultural  and agriculture-related land uses
 (References 45,46).  A potential impact of  benefit would result
 from reduction of pressure for future large-lot subdivision in
 the vicinity of the sludge drying and distribution center.

     It is not likely that the proposed storage and distribution
 system will provide the stimulus for any significant land use
 changes in the surrounding area.  At this time it appears that the
 major  cause of future land use changes in the area will be the pro-
 posed Adams County General Aviation Airport.  Sites to the west of
 the proposed sludge drying and distribution center are being con-
 sidered for the airport.   A "growth corridor" running from the pro-
 posed airport northwest to Brighton is likely.   The drying and dis-
 tribution center might limit  growth which would otherwise extend
 eastward from the proposed airport.   However, in general  there ap-
 pear to be no major negative  land use impacts associated with the
 proposed drying and distribution center (Reference 44).  Further
discussion  of this  topic  is found in Volume II,  Issues  II-4,  II-9
and 11-10.

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Land Tenure

     Should the proposed project be implemented, there will be
varying effects on land associated with the sludge processing,
transfer and drying facilities.  In terms of the Metro Denver Cen-
tral Plant, there will be no impact on land tenure since no trans-
fer of ownership is anticipated.  Likewise, no tenure change is
anticipated for the roadway right-of-way areas for the pipeline
since an easement will probably be obtained.  However, ownership
of the drying basin site will be transferred from private into
public ownership.

     No other impacts on land tenure will be incurred by the pro-
posed project.  The Lowry Bombing Range and landfill  site will re-
main in public ownership whether or not the project is implemented.

Population

     The project will not have a significant impact on the popula-
tion growth rate in Adams County or in the Metro Denver service
area as a whole.  It seems likely that the project would encourage
the continuation of agricultural activity and sparse population in
the region surrounding the drying site.  This impact on population
distribution is predicated on two factors:  (1) The proposed proj-
ect would provide a conveniently located source of fertilizer/soil
conditioner, to the benefit of farmers; and (2) the project may
inhibit residential development in the immediate vicinity of the
sludge drying site.

     The impact on population distribution is uncertain and will
probably be diffuse.  It would tend to maintain a sparsely popu-
lated rural area in its present state and thus aid in limiting
sprawl  radiating from the Denver area.

     The 18 new jobs generated by the drying/distribution center
will not significantly affect population growth or distribution
in the area.  It is expected that the project will have no signifi-
cant growth-inducing impacts.

Transportation and Circulation

     The proposed project could have a variety of direct impacts
on transportation facilities which will serve the proposed drying
basin site.  Average daily traffic (ADT) will  increase, roadways
will deteriorate, highways might become littered and  dust will be
generated as a consequence of sludge trucking.  No impacts are ex-
pected  on transportation facilities located in the area surround-
ing the Metro Denver Plant or along the proposed pipeline route.
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     Average Daily Travel —

     Average daily travel  will  increase  on  roadways  serving the
proposed sludge drying and distribution  center  as  a  result of
trips made by facility employees  traveling  to and  from  work and
trucks using various roadways to  deliver dried  sludge.   The ma-
jority of this traffic will be  concentrated on  such  roadways as
Irondale Road, Bromley Lane and Hacksmount  Road, which  will serve
the drying and distribution center.   The impact declines as road-
way travel radiates toward destination points.  This increase in
average daily travel will  not adversely  affect  traffic  flow since
the roads in question are infrequently traveled and  have design
capacities adequate to carry the  additional traffic.

     Assuming an average daily  sludge production of  190 metric
tons [210 tons] and a truck capacity  of  14  metric  tons  [15 tons],
annual truck traffic will  total about 5,000 trips.   Assuming a  de-
livery period of four months (two months during the  spring and  two
months during the fall), five days per week, daily truck trips
will total 60 to 65.  Further assuming a delivery  radius of 100 km
[60 miles] from the sludge drying site,  this number  of  truck trips
distributed over an area of over  31,000  sq  km [11,000 sq miles]
will not cause a significant impact on traffic.

     Highway Bridge Capacity—

     A potential problem is inherent  in  the fact that highway
bridges in some areas have posted capacity  limits  below 14 metric
tons [15 tons], the assumed average truck load. County Road 30,
for example, which serves the representative irrigated  farm in
Weld County, includes two bridges, 30/25A and 30/25B, the former
with a posted limit of 4.5 metric tons [five tons] and  the latter
with a capacity of seven metric tons  [eight tons]  (Reference 105).
The routing of trucks will therefore  require consideration of
bridge capacities in order to avoid accidents and  bridge damage.

     Traffic Dust—

     Unpaved sections of roadway, on  Weld County Road 30, for ex-
ample, can lead to dust problems  under conditions  of heavy traffic.
Because many areas in which deliveries will occur  are under the
jurisdiction of an air pollution  control  district, Colorado's Fugi-
tive Dust Law will apply,  requiring a dust  abatement plan to be
filed prior to the start of deliveries over unpaved  roads (Refer-
ence 104).

     Dust generated by increased  traffic could  annoy residents  of
the area.  This problem would be  minor,  however, since  most of  the
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roadways are paved except for a six-km [four-mile] segment of
Hacksmount Road (Reference 103).

     Damage to Roadways—

     It is expected that deterioration of road conditions will
accelerate as a consequence of increased average daily traffic
associated with the conveyance of three-axle trucks carrying
dried sludge loads estimated at 14 metric tons [15 tons]  (Refer-
ence 77).  Hacksmount Road, Bromely Lane and Irondale Road have
design capacities adequate for such loads and presently are used
by agriculture-related trucks carrying similar loads.

     Sludge Spillage in Transit—

     Load spillage on these roadways is another potential problem
related to the distribution operation.  However, spillage occur-
ring on roadways related to the Lowry Bombing Range facilities,
whose operation is similar to that of the proposed delivery sys-
tem, has been minor, with only two sludge-carrying trucks having
overturned durinq three years of operation (Reference 77).  There-
fore, it can be assumed that spillage and littering will  not be a
major problem in the operation of the proposed project.

Recreation

     Odors produced by operation of the proposed project  represent
the only potential impact of the project on recreational  areas  and
their users.  Impact would be limited to the vicinity of  the Metro
Denver Plant, which will house anaerobic digesters.  Should those
digesters fail, odors produced would radiate for a distance of  1.5
to 3 km [one to two miles] from the Central Plant facilities.  The
only recreational area located within that distance is a  ten-mile
segment of the South Platte River area proposed for boating, bi-
cycling and picnicking activities (Reference 106).  Although some
users would be affected by odors once the recreational area had
been developed, the impact would not be a major one.  Overall plant
odors are more likely to be the chronic nuisance.

     The probability of anaerobic digester breakdown is small;  de-
sign features appear to be adequate, and operational precautions
will presumably be incorporated.  If a system failure does occur,
the impact period will be limited to the time required for repair.
The potential impact of such a failure is considered minimal be-
cause the Metro Denver facilities are located in an industrial  cor-
ridor.  Other odors generated in this area would tend to mingle
with and hence lessen the perceptible intensity of those produced
by anaerobic digester failure.  There are no recreational areas
within the odor range of the pipeline facilities or drying basin
areas.
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Governmental Agency Jurisdiction

     The proposed project has precipitated a jurisdiction! dispute
between Adams County and Metro Denver.  The relative authority of
these two bodies over the proposed project has become the subject
of  litigation.  The proposed project would remove the Metro Denver
sludge management operations from the Lowry Bombing Range and
therefore from the jurisdiction of the City and County of Denver.
While the present working arrangement has been satisfactory, the
District could not expand beyond the present disposal area.

     The project does not appear to be in conflict with any acti-
vities of planning agencies concerned, with regard to jurisdiction
in  the study area.  However, an important question remains as to
which agency will have the necessary authority, responsibility,
funding (for monitoring, surveillance and enforcement of proper
application restrictions) and administrative structure to regulate
the proposed project.

Employment

     A full-time staff of 18 people will  be required for operation
of  the distribution center facilities at  full  development (1985).
This will not have a significant effect on employment in the area.

Land Values

     If the proposed drying and distribution center is operated
according to accepted sanitary engineering principles, it is not
expected to have a significant ultimate effect on surrounding land
values (References 66,52).

     Some impact, over and above the various physical impacts de-
scribed elsewhere in this report,  would probably be felt on the
value of land surrounding the proposed project.  A psychological
impact, which would make people reluctant to live near such a cen-
ter, would inhibit residential  development around the site.  This
could limit future increases in property  values associated with
such development.  On the other hand, agricultural  activity might
be  intensified in the proximity of the fertilizer storage and dis-
tribution system, and secondary development associated with such
increased activity might also occur.   Each of  these events would
be  likely to raise property values.

     While it is  difficult to generalize  from  other sludge recy-
cling operations, land values near other  such  projects have not
decreased  and it  is therefore considered  unlikely that decreases
would occur  in the vicinity of  this  operation  (Reference 108).
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Therefore, the net effect of the proposed project on the value of
property surrounding the site is likely to be minor (see Volume II,
Issue II-4).

Construction Impacts

     Transportation and Circulation—

     Transportation facilities associated with the Metro Denver
Central Plant facility, the proposed pipeline route and the dry-
ing basin site may be affected during the construction phase of
the proposed project.  However, these impacts will be of short-
term duration and in most cases insignificant.

     In order to construct anaerobic digesters, large equipment
will be moved in over roadways surrounding the Central  Plant fa-
cility.  This activity may cause a disruption of normal traffic
flow patterns and may even necessitate traffic diversion.   How-
ever, such impacts will be of a temporary nature and will  be in-
significant since the transport of heavy equipment into the in-
dustrialized corridor surrounding the plant is a normal occur-
rence.

     Pipeline construction activities may be of longer duration than
those associated with the digester construction.  Traffic  patterns
on adjacent travelways such as Irondale Road and Colorado  State
Highway 2 could be affected.  Construction impacts associated with
Irondale Road should not be a problem since activity will  concen-
trate on right-of-way areas and should disrupt traffic  on  this
infrequently traveled rural roadway to only a minor extent.  Con-
struction activities adjacent to 104th Street may have a more se-
vere impact because this travelway accommodates large volumes of
daily traffic.  Impacts incurred, including delay periods  and pos-
sible detours, will  be temporary.

     Activities of 80 to 100 construction employees, deliveries,
inspections, etc. associated with construction at the drying ba-
sins will  increase average daily traffic on servicing roadways by
360 (Reference 55).   These roadways have the capacity to accommo-
date the temporary increase.  Because current average daily traf-
fic on these travelways is low, temporary slowing of traffic over
triem will  not be significant.  Therefore, any impact incurred
will be negligible.

     No other construction-related impacts on transportation or
circulation are anticipated as a result of the proposed project.
                             131

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     Flora and Fauna/Habitats—

     The temporary nature of the construction activities at the
Central Plant, along the pipeline and at the drying/distribution
site tends to minimize impacts upon flora,  fauna and wildlife
habitats.  With successful  quick revegetation and adequate plan-
ning, construction impacts  can be kept below significant thresh-
olds.

     Soils—

     Soil profile along pipeline route will  be completely de-
stroyed and replaced by a blending of underlying materials and
the initial soil layers.  The linear nature of this impact makes
it of relatively little concern, especially since most of it will
take place along the previously disturbed soils of road easements.

     Utilities—

     In order to extend electricity and telephone service to the
drying basin site, easements will  be obtained along farmlands and
roadway right-of-way areas  (Reference 72).   During construction
activities, farming operations and even travel on adjacent road-
ways may be disrupted.  However, the impact would be of short du-
ration and the area of disruption small in  scale.

     Air Quality—

     During construction of the drying and  distribution facility
and the pipeline, dust will be generated and pollutants emitted
by construction equipment.   However, the effect on ambient air
quality will be insignificant.  While much  dust will be stirred
up on the project site, this impact will be temporary and will be
localized to a very sparsely populated area.

     Employment—

     During construction of the pipeline and distribution center,
80 to 100 people will  be employed.   These workers will be re-
cruited from the local Denver area work force.

Secondary Impacts

     Economy—

     The construction  of a  large public facility inevitably has
impact on the local  economy as a result of  both the construction
process and the subsequent  operation of the facility.
                              132

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     Direct economic impacts, including employment and potential
impacts on agricultural activity, are discussed elsewhere in this
volume, both with regard to temporary construction employment and
to permanent employment.  With respect to the operation of the fa-
cility, there appear to be virtually no significant secondary im-
pacts other than those associated with agricultural activity.
The small volume of permanent employment and the relatively small
demand on community resources—when the facility is fully opera-
tional—suggest that secondary impacts of the operation will be
negligible or nonexistent.

     The same conclusions cannot be drawn with respect to secondary
impacts of construction.  The total capital  cost of the proposed
facility is approximately $17.8 million.  The maximum construction
employment will be approximately 130 persons.  In addition, a sub-
stantial portion of the capital cost will be accounted for by
items other than direct labor, with a fraction of this amount ex-
pended for local materials and services.

     Two steps are used for estimating secondary impacts.  First,
an attempt is made to make preliminary allocation of capital costs
among labor and materials and to provide an estimate of the allo-
cation of the material costs between local and imported components.
The second step uses an employment multiplier dealing exclusively
with construction employment to estimate the potential indirect
employment that will be created.

     The estimates are based largely on experience with other,
similarly capital-intensive projects in Devner and elsewhere,
using the lower end of estimates to formulate possible minimum
dollar impact on the local economy.  The results of the initial
step are shown on Table 21.

     It is assumed that only half of the "materials, expenses,
fees, etc." component will be spent in the Denver Standard Metro-
politan Statistical Area.  This assumption is not as completely
conservative as it may seem; while many of the materials and ser-
vices may be purchased in the Denver metropolitan area, their
original sources lie elsewhere, and the value added in distribu-
tion within the local metropolitan area may be relatively small.

     Employment—

     The foregoing analysis suggests that approximately $5.2 mil-
lion in total payrolls may be generated locally by the project
along with approximately $9.35 million in local expenditures for
material expenses, professional services, etc.
                             133

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       Table 21.  ESTIMATED CAPITAL COST AND APPROXIMATE
            ALLOCATION TO LAND, LABOR AND MATERIALS
                                                       Amount,
	Cost estimate and allocation	1974 $

Capital cost (not including digesters)                 17,800,000

  Less estimated land cost (800 ha @                     500,000
    $625/ha)a                                        	
Total cost of improvements                            17,300,000

   (including contingencies, process-
   ing costs and engineering and other
   professional costs)

Approximate allocation
   Direct labor (20 percent)                            3,460,000
   Indirect labor (5 percent)                             865,000
   Materials, expenses, fees, etc. (75 percent)        12,975,000
    Spent in Denver SMSAb:         $6,488,000
    Imported:                      $6,488,000


a[2,000 ac @ $250/acJ.
 Denver Standard Metropolitan Statistical  Area.

     These estimates of expenditures may in turn be subjected to
further analysis to develop estimates of indirect employment and
economic impacts on the local  economy.   The purpose of this exer-
cise is to determine the order of magnitude of such impacts.
Quantification on any more precise basis would require disaggrega-
tion of capital  cost, which is not now available.

     As suggested above, gross payrolls associated with construc-
tion of the project are approximately $5.25 million.   It is a rea-
sonable inference that approximately 70 percent  would  be directly
reflected in the local  retail  purchases. .  This would amount to ap-
proximately $3.7 million,  an amount well under one percent of the
retail  sales in  Adams County.

     Based  on an approximate up-date of the 1972 Census of Business
estimates,  the retail  sales per employee are approximately $52,000.
Thus,  the introduced $3.7  million would create the annual  equiva-
lent of approximately 70 additional  person-years of new employment.
                              134

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     The  nonlabor  expenditures associated with the capital cost
 of  the  project would  be  spread over a wide range of materials and
 services,  probably concentrating  in the building and construction
 materials  and transport  services  areas.  A tentative approxima-
 tion of sales per  employee  in these sectors suggests that they
 are perhaps  $60,000 to $70,000 per employee.  On that basis, the
 employment impact  of  these  materials and other expenditures would
 be  approximately 140  employees.

     On the  basis  of  preliminary  and rough analysis, it is possi-
 ble that  the aggregate impact of  construction of the project
 would be  210 person-years of employment.  Since the additional
 employment impact  will spread over the entire Metropolitan Denver
 area, the  relative impacts  will  be fairly trivial, amounting to
 less than  l/20th of one  percent  of the areawide employment.

     Other Secondary  Impacts--

     Infrastructure investments  discussed above can have serious
 negative  secondary impacts  on air quality, urban runoff, sensitive
 areas,  etc.  from population growth induced or accomodated by the
 proposed  project.  The sludge processing and disposal project is
 necessary  for the  efficient operation of the overall Metro waste-
 water system.  Furthermore, the  issue of secondary impacts is being
 analyzed  in  detail in the EIS on  Metropolitan Denver Facilities Plans.
 Therefore, discussion of secondary impacts are deferred to that EIS
 process.   It is apparent that control over population growth pat-
 terns can  be more  directly  effected through the individual waste-
 water facilities plans and  NPDES  permits.

     Impacts of Sludge Disposal  at the
     Drying  and Distribution Center--

     Because the disposal portion of the operations at the processing
 site involves land application of sludge, the discussion of its im-
 pacts is presented on page  166 after the discussion of recycling im-
 pacts and  prior to disposal  impacts.

 Summary of Impacts at the Sludge Drying
 and Distribution Center

     The most serious negative environmental  impacts at the sludge
 drying and distribution center are on soil  properties, groundwater
 quality and the public health through nitrate pollution of ground-
 water and  pathogen problems.  Positive impacts are energy and re-
 source conservation.   The impacts are schematically represented on
 Figure 16  in a summary format to  indicate the rough order of impor-
tance  EPA places  on the  various  Impacts  surrounding the drying/
processing operation.
                                135

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                                                                   FIGURE  16
            SUMMARY OF POTENTIAL IMPACTS AT THE PROPOSED SLUDGE DRYING AND
                                DISTRIBUTION CENTER
                                 FOR METRO DENVER
                                                    Direction and potential
         Impact parameter	intensity	
         Soil loss/farmland productivity

         Groundwater quality

         Surface water quality

         Water rights

         Public health—Pathogens

         Public health—Nitrates

         Public health—Vectors                               •

         Loss of habitat                                      •

         Air quality (including odors)                         •

         Energy use                                         f  j

         Natural resources                                   f  J

         Construction impacts  (overall)                        •

         Secondary impacts  (economy/employment)                O


 a
  Symbols signify  relative  impacts, as defined below:
                                                    High    Moderate   Low

         Positive  (beneficial)  impacts:              C  J      C^\      Q

         Negative  (adverse) impacts:
 This  schematic representation of impacts should only be  interpreted within  the
 context of analyses of impacts presented in the main body of the EIS.   It is
 neither an attempt at quantifying the impacts nor reducing the diverse  environ-
 mental parameters to common bases for comparison.  However, it does provide a
 rough ranking of the relative importance of the various impacts.  The scales
 denocea by symbols used above are not intended to be compared with those used
on Figures 17 and  18.  These impacts are also subject to mitigation which could
lessen their importance.
                                      136       ENGINEERING-SCIENCE,  INC.

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IMPACTS OF LAND APPLICATION OF SLUDGE ON THE RECYCLING AREAS

General

     A large body of new data is being developed in various parts
of the country on impacts of sludge reuse in agricultural  and re-
lated activities under a wide variety of conditions.   A single
salient conclusion of the collective evidence to date is that the
impacts are site-specific.  Thus, statements made in  the following
paragraphs are necessarily applicable to the types of sites which
are described in Section III and Appendix E under Environmental
Setting.   Even though a finite number of sites were investigated
for the purpose of impact analysis, it is recognized  that  dried
anaerobically digested sludge may be used for a rather large
variety of applications.  It is expected that the city parks, sod
farms, mine spoil sites, irrigated and dry farms and  home  gardens
will provide examples of the entire range of application site pos-
sibilities and provide the information necessary to evaluate the
advisability of using the material on proposed sites.

     As an introduction to impacts of sludge application on land
recycling areas, a graphic representation of the severity  of the
various impact parameters on the representative types of applica-
tion sites is presented in Figure 17.  All of the subjective impact
levels assigned can be qualified depending upon prevailing condi-
tions, management practices and other mitigating circumstances.
These qualifications are presented below with particular emphasis
on site specificity.  An overview of the major concerns and advan-
tages of each type of land application site is presented prior to
the presentation of the impact parameters.

     City Parks--

     The application of sludge to city parks is potentially prob-
lematic because of the high rate of public use of the parks for
recreation.  Although sludge has been, and is being used,  as ferti-
lizer on the parks in the past, publicity resulting from the large scale
of the proposed project may engender some concern, if not opposition.
Public involvement is important, and the Denver Department of Parks
and Recreation should promote a program of public awareness to in-
form the public as fully as possible of the benefits  and potential
effects of sludge application.  Additionally, the use of sludge on
the City parks should be rigorously monitored to ensure the success
of the program.  The viability of pathogens (especially Ascaris
ova) is perhaps the most crucial issue and should be  closely moni-
tored.  The use of additional methods for pathogen reduction, as
described in detail  in Section VI and Appendix D, would provide
additional protection to the public.
                              137

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                                                                   FIGURE  17
         SUMMARY  COMPARISON  OF  RELATIVE POTENTIAL  IMPACTS   OF SLUDGE
    RECYCLING  ON  VARIOUS  LAND APPLICATION  SITES  IN THE  VICINITY OF DENVER
                                     Sludge  application site
      Impact
     parameter
                Mine    Irri-
City     Sod    spoil   gated    Dry
parks   farms   sites   farms   farms
                                          Home gardens
                                         Orna-   Edible
                                        mentals  slants
 Food chain

 Public health

 Water quality

 Soil productivity

 Soil salinity

 Soil heavy metals

 Air quality

 Vegetation

 Wildlife

 Habit-its

 Odor

 Noise

 Aesthetics

 Natural  resources

 Traffic  and
   circulation
O     o     o     O
                                         O     O
o
o
 •
        O    O
          •      o
          •      O
         •      O
        O    O
o    o     o     o
O    O     o      o
  Symbols signify relative magnitude and direction of impacts, as defined
  below:
                                          High'  Moderate   Low   None
      Positive (beneficial) impacts:

      Negative (adverse) impacts:
                      O
                               o
This schematic representation of impacts should only be interpreted within
the^context of analyses of impacts presented in the main body of the EIS.
It is neither an attempt at quantifying the impacts nor reducing the diverse
environmental parameters to common bases for comparison.  However,  it does
provide a rough ranking of the relative importance of the various impacts
and a comparison of sites vis-a-vis each parameter.
                                    138
                          ENGINEERING-SCIENCE, INC.

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     Sod Farms--

     The sod farms of the Denver area represent a specialized type
of irrigated farm.  While impacts are evaluated specifically for
one specific sod farm, many of the impacts may be extended to oper-
ations in similar situations.  Generally, sod farms represent the
best type of land recycling sites for sludge from the environmental
viewpoint.  The applied sludge and its constituents are transported
away from the sites and distributed thinly over a very wide area.

     Mine Spoil Sites--

     The proposed mine spoil sites for sludge application are
heavily disturbed unnatural  areas.  The proposed action represents
an initial step towards reclamation of these "waste areas" and,
thus, all impacts are evaluated in this perspective.  Mo food crops
are assumed to be grown on such spoil sites.  Public access and
exposure to the sites, especially during the reclamation period,
will  be limited.  Thus, mine spoil sites are generally the least
problematic for sludge reuse purposes.

     Irrigated Farms--

     Irrigated farms represent the type of land application candi-
date sites which may become major users of the Metro sewage sludge.
Allowable annual application rates are fairly high, as shown in
Figures 14 and 15 in Section IV.  Consequently, the number of years
of safe application is relatively short.  Thus, the opportunity for
corrective action, if indicated, is more limited than in the non-
irrigated applications.  On the other hand, irrigated farms are
generally more intensively and carefully managed because of the
higher value of crops grown on these farms.  In fact, many irrigated
farms have highly sophisticated irrigation equipment capable of
automatic control with sensors connected to tensiometers and other
devices determining plant-soil  moisture status.

     The availability of a competent and wel1-equipped management
system tends to give better assurance of (a) proper control of
application rates, (b) careful  monitoring of soil, crop and water
quality responses to applications of sludge to land and (c) accu-
rate recording and mapping of areas receiving measured quantities
of sludges from the very first application until the limit is
reached, and beyond.

     Application of lime, supplemental phosphorus and potassium,
if needed, and irrigation water are common practices on these
farms and can be readily adjusted to meet the additional require-
ments imposed by the sludge application.
                              139

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     Therefore, while irrigated farms will  be potentially the most
extensively and intensively affected by the sludge reuse scheme,
they are also the areas that offer the greatest opportunity for
control and mitigation.

     Non-Irrigated Farms--

     Non-irrigated farms abound in Weld, Adams and Arapahoe Coun-
ties, surrounded by extensive areas of drylands used as non-culti-
vated pasture.  These areas generally have  very low fertility, as
shown by production rates per unit surface  area, reported by the
Colorado Department of Agriculture (Reference 95 and shown on
Table E3 in Appendix E).  The low fertility is in part due to con-
tinuous cropping with little fertilization  or amendment.  It is not
expected that dry farms will also become extensive users of the
Denver sludge at low surface application rates over large areas
and over a much prolonged period of time.

     Use of liquid sludge will probably be  more successful on dry-
lands and non-irrigated farms with subsurface injection tools than
use of the air-dried material.  This is because the injectors can
serve the double function of soil water conservation through scar-
ring the land surface while applying sludge at a safe depth below
the soil surface.

     In general, impacts of sludge application on non-irrigated
farms and drylands will be far less intensive than the other agri-
cultural reuse candidate sites discussed in this volume.  Further-
more, the low application rates provide a safety mechanism and
greater opportunities for corrective action should unforeseen neg-
ative impacts become evident in the future.  The low application
rates could prove uneconomical to dryland farms.

     Home Gardens--

     A significant number of gardeners, organic growers and others
raising crops on relatively small scales have expressed interest
in and enthusiasm for the use of anaerobically digested dried
sludge for application to their soils (see  Appendix F).  Due to
the potentially large numbers and wide separation of sites in this
type of use of the sludge, it could be very difficult for any
jurisdiction to provide the supervision, control and monitoring
that is essential to the success of (including prevention of
environmental  hazards from) sludge recycling on the land.  Further-
more, the potential  for direct human exposure to the material
would be great because automated and mechanical  application is im-
practical  on small-scale operations.  Some  home gardeners would
use the sludge for amending soils supporting ornamental plants;
others  would use it on edible crops.  There are far fewer potential
                            140

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hazards associated with ornamental  than edible (especially leafy
vegetable) crops growing on soils amended with wastewater  sludge.
Regulating proper use of the sludge and maintaining  public health
protection in home gardens would require a very determined public
education effort including clear labelling, instructions,  warnings,
spot checks and, perhaps, provision of legal  constraints.

Food Chain

     The impact of sludge application in irrigated farms and  home
gardens upon the food chain is largely dependent upon  the  types of
food crops or feeds grown for direct and eventual  human consump-
tion.  Leafy parts of vegetables, beets, mint, vine,  lettuce  and
chard are examples of crops which accumulate  cadmium  in greater
concentrations (sometimes up to ten times) than found  in the  soil .
The animals eating such crops and ingesting sludge-amended soil
will further accumulate cadmium in the kidneys, liver  and  some
other organs and tissues.  Eating these tissues could give rise to
kidney diseases and hypertension in humans.  Some people tend to
consume these less expensive tissues as a substantial  part of their
diets.  The irrigated crops grown in the area are mainly wheat,
corn, barley, sorghum, beans, beets, oats, hay and potatoes.  None
of these crops is usually consumed unprocessed and/or  raw  and none
is known to be a particularly heavy accumulator of metal elements
in their usually edible parts.  On the other  hand,  leafy vegetables
grown in home gardens such as Swiss chard, spinach and lettuce
tend to magnify cadmium concentrations in their edible tissues.

     Because of its high toxicity, cadmium is the most important
element of concern in the Denver situation, while copper and  zinc
are far less important due to very low concentrations  and  much
lower toxicities.No standards have yet been established  for the
limitation of cadmium in foods.  The U.S. Food and Drug Administra-
tion proposes to establish such standards for cadmium in the near
future.  Generally, as long as sludge cadmium content is below  one
percent of the zinc concentration, and as long as recommended ap-
plication rates are not exceeded, potential cadmium  toxicity in
the food chain will be minimized.  Recent analyses (Table  D-4 in
Appendix D) indicate that even though cadmium levels  are far below
average for municipal sludges, average cadmium in the Denver sludge
is about 1.7 percent of the zinc content.  Although  this  value
somewhat exceeds the one percent limit stated above,  existing
mitigating circumstances are expected to adequately  compensate
for this ratio.  The favorable circumstances  are (1)  highly cal-
careous conditions, particularly in the lower soil  horizons on
most of the irrigated farms; (2) the conservative nature  of the
ultimate sludge loading rate, given in earlier sections;  (3)  the
relatively high phosphorus content of Denvir sludge,  which tends
to help make both zinc and cadmium less available to plant species:
                              141

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and (4) the poorly defined concept of "reversion," in which heavy
metal  elements gradually become combined into stable, unavailable
compounds.  This latter process is most rapid in calcareous, alka-
line soils such as encountered in most of the study area.  Possible
lowering of pH during the first few years after sludge application
may lead to release and uptake of these elements.

     Another important consideration is the possibility of reduc-
tion of the quantities of heavy metals in the wastewater system
from industrial and other sources in the future years.  It is
probable that significant reduction will be accomplished before
the ultimate surface application limit is reached  on most irri-
gated farms.

     The other elements of major concern to the food chain, in-
cluding copper, zinc, molybdenum, selenium and lead, are of suf-
ficiently low concentration in the Denver sludge so that they are
not expected to produce an adverse impact upon the food chain.
The favorable soil conditions discussed above also protect against
most other metals.  Most toxic metals sharply reduce crop yields
before they become high enough in concentration to pose a food
chain hazard.  This phenomenon constitutes a safety valve in the
food chain.  Additionally, organic compounds in sludge are able to
chelate heavy metals, making them even less available.

     Crops grown on non-irrigated farms are primarily winter wheat
and barley with lesser areas of grain, corn, sorghum,  oats and
spring wheat.  From the point of view of preventing heavy metals
accumulation in the food chain, more suitable cropping patterns
would be hard to accomplish.  The parts of these plants which are
used for animal feed and/or processed for human consumption are not
known to be accumulators of cadmium or any other heavy metals.   It
is not expected that cropping patterns will change appreciably  in
the future years; hence, it is expected that no significant food
chain hazards will exist with sludge reuse on non-irrigated farms.

     Sludge application, in excessive amounts on rangeland may  re-
sult in accumulation of cadmium and other heavy metals in the
leafy parts of some weeds.  Domestic animals feeding on these
rangelands will in time accumulate these elements  in their tissues
and pass them along to humans who eat the meat (especially liver
and kidneys) thus produced.  As long as recommended application
rates are not exceeded, excessive accumulations are not expected
to occur.   However, direct ingestion of sludge-amended soils by
livestock (ten percent of whose diet is soil particles) can sig-
nificantly increase heavy metal magnification along the food chain.
The present operations at the Lowry Bombing Range  are most conducive
to this sort of heavy metals assimilation by grazing animals.
                              142

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     The most effective and long-lasting solution to heavy metal
magnification problems in the food chain is removal--or reduction--
of discharges containing toxic elements from the sewer system, as
mentioned above.  This can be achieved through an extensive program
of source identification, promulgation of standards, regulation
and intensive enforcement of the discharge quality standards on
industrial dischargers.  This topic is discussed further in Volume
II, Issues 1-1 and V-l.

Public Health

     Although no documented cases exist in the United States that
associate the use of digested sludge on land with human disease,
two major factors require that the possibility of such an occur-
rence be considered.   First, City parks are heavily utilized by
the public who may come in contact with sludge in a number of
accidental and unforeseen ways.  Secondly, although sludge proces-
sing destroys a significant number of pathogens, some may survive
over long periods of time (see Table 20 on page 114).  The use of
sludge on City parks is practiced in many parts of the country
with no reported public health problems.

     Pathogens--

     The greatest areas of concern are home gardens where the pos-
sibility of direct human contact with pathogens on the soil, orna-
mental plants and edible crops is quite high.  The long survival
time observed for viruses and Ascaris ova makes it imperative that
(1) no food crops be raised on sludge-amended soil to be eaten
directly (unprocessed, raw) by humans, (2) long field re-entry
periods be established and strongly enforced on areas where sludge
is applied, (3) cases  of disease contracted from sludge sources be
identified, documented and followed through and (4)  a very rigor-
ous public health monitoring program be established as an integral
part of the reuse of sludge on food crops of all types.

     The pathogen problems associated with the dried sludge de-
livered to sludge recycling sites will be somewhat less intensive
than the material at the drying and distribution center because
of the natural die-off of the pathogens with time.  However, the
greater possibilities for human contact bring up additional pos-
sible public health impacts.  If sludge is used to fertilize crops
or home garden vegetables which will be eaten raw within the first
year of application, adverse health impacts could well result.  If
the one-year wait is observed, no significant health impact is ex-
pected.   Recommended waiting periods of from one year (Reference
81) to three years (Reference 79) between sludge application and
growing of crops to be eaten raw have been suggested.  However,
Metro plans presently call for a one-year drying period in the
                               143

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drying basins only,  before release of sludge to  the consumer.

     The EPA preliminary proposed  wait of  three  years  before rais-
ing crops to be eaten raw (Reference 79)  is  a cautious waiting
period for a cool, dry region like the Metropolitan Denver  area.
Table 20 indicates that Ascaris ova are the  limiting factor in
setting a safe period for pathogen die-off.   The EPA document is
nation-wide in scope, however, and the Ascaris problem is  primarily
of concern in moist tropical  regions, such as some  southern states
(Reference 111).

     Ascaris is not of great  enough importance in Colorado  to be
listed among the  22 diseases  on the Colorado State  communicable
disease report; the disease ordinarily has mild--often almost un-
noticeable--symptoms.  This disease has a  very low  incidence in
the area, and the long survival  time for  the parasite's eggs,
applies only under conditions favorable to the roundworm.   The
arid, cold seasons common to  this  area do  not provide  this  en-
vironment.

     The next hardiest pathogens are tubercle bacilli, which can
survive only six  months.  Continued application  of  sludge  to park-
lands will have no significant adverse health impacts.  The anaer-
obically digested sludge will have fewer  pathogens  than the ma-
terial presently being applied to  the parks.  If a  two-year drying
period is instituted, it will ensure that  no significant impacts
will result from park application  of sludge.  This  safety  margin
will be necessary because particles of sludge will  probably be  in-
gested by some picnickers, children playing  in the  dirt, etc.

     In view of the differences in pathogen  viability  and  concentra-
tion in the different types of sludges (liquid,  air-dried  and stock-
piled for various lengths of  time), their respective uses  should  be
limited appropriately.  For example:  (1)  liquid sludge should be
applied only by deep injection into the soil, with  no  possibility
of surface exposure; (2) as the level of human contact becomes  more
probable for each use (dry farms,  irrigated  farms,  home gardens,
vegetable crops,  in increasing order), required  length of  storage
time in the drying and stockpile areas should be increased.

      Nitrates--

      Potential pollution of  groundwater will not pose a significant
public health  hazard.  The primary chemical  constituent of concern is
nitrate.  Nitrate levels over 45 ppm  (measured as nitrate) in  drink-
ing water are  considered to  be  harmful to infants  (Reference 112).
However, as  indicated below  under Water Quality, groundwater contam-
ination under most land recycling schemes would be less than or the
same as from  use of  commercial  fertilizers.
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     Health Services--

     A significant impact upon the public health department serv-
ices is foreseen as a result of the proposed project.  The public
health department's monitoring activities will  need to be ex-
panded to cover all the land recycling areas receiving sludge.
This will increase the manpower requirements of the public health
services.

Hater Qua!ity

     Two potential water quality hazards posed  by sludge amendment
of soils are the total dissolved salts (TDS) and the nitrate form
(NO^) of nitrogenous compounds found in the sludge and supernatant
liquid.  If the supernatant is excluded from the land application
project, salt problems will largely be prevented.  The nitrate
pollution of groundwater and surface water remains as long as there
is a supply of nitrogenous compounds over and above the amount
which plants can take up and denitrifying bacteria in the soil can
denitrify.  Water pollution hazards posed at the six typical  sites
studied are presented separately below, in order to emphasize the
specificity of impacts to sites and conditions  as well as the
typical management practices employed.

     City Parks--

     Of the approximately 500 known wells within the City of Denver,
in 1964 (Reference 21) fewer than 50 were used  wholly or in part
for domestic purposes.  Most wells are used for irrigation, cooling
water, industrial  and other purposes.

     It is expected that at the proposed annual sludge application
rates of 56 metric tons/ha [25 tons/ac] per year and with the
typical irrigation practices on park lands, significant quantities
of dissolved salts, including nitrates, will leach toward the
groundwater reservoir.  In about 20 to 100 years these salt-laden
seepage waters will arrive at the groundwater table and will
gradually increase TDS and nitrate concentration of waters with-
drawn from the wells.  It is probable--though supportive data are
lacking—that even under past and present commercial  fertilizer
regimes, downward  movement of nitrates have been and are proceed-
ing.   Therefore, earlier arrival  of nitrates in the well waters
should be expected.

     If domestic uses of groundwaters  (for drinking and culinary
purposes) are altogether prohibited or otherwise terminated, the
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recommended limit of 45 mg/1 of nitrate nitrogen may be permitted
to be exceeded in the groundwater.   If, on the other hand, domes-
tic uses of groundwater in parts of the Denver area are indispen-
sable, sludge and fertilizer application rates should be limited
to levels recommended in Section IV.   Limitation of sludge appli-
cation, particularly in those parts of the City and County of
Denver and other cities using groundwater for drinking purposes,
is very important and necessary for public health protection.
Sucy controls should probably be made in conjunction with controls
for irrigation leaching.

     Pollution of surface waters, such as streams and lakes in
the City, through leaching and/or runoff is a distinct possibility.
It can be minimized through erosion control and judicious choice
of sludge application rates and methods to balance uptake of salts
by plants.

     Sod Farms--

     It is expected that with adherence to the recommended sludge
application rates (in Section IV) negligible nitrate leaching to
the groundwater will result.  Other soluble salts, however, will
gradually move downward with the irrigation waters applied over
and above the evapotranspiration needs of the grass.  The amount
of these salts applied with the sludge is expected to be relatively
moderate (about 350 kg/ha [300 lb/ac] per year) and significant
only from a long-range cumulative point of view.

     Surface water contaminations from portions of the sod farm
that are actively growing grass will  be insignificant, because of
the highly effective cover that sod provides against runoff and
erosion.  The soil in the sod farm studied, Truckton sandy loam,
is erodible unless it has adequate cover.  Therefore, without some
provision for catchment of surface runoff, pollution of streams
may be expected from portions of the  sod farms which have just been
harvested or which have been left unplanted.

     Mine Spoil Sites--

     The thickness of spoil  materials heaped on top of the natural
ground surface ranges from a few meters at the minimum to about
80 m [250 ft] at the top of the spoil  banks.  Irrigation water and
rainfall can travel  through these highly porous materials with
relative ease after  the rocks reach saturation moisture content.
It is  expected that  the more successful the reclamation of spoil
banks  is, the less excess water will  be available to leach through
the acidic spoil  materials and the less mine spoil drainage will
take place.   Irrespective of pollutant constituents of applied
sludge, mine spoil drainage is generally a severe contaminant of
surface waters.  Hence, use of sludge to slow down such drainage
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through entrapment and evapotranspiration of precipitation will
help mitigate an existing major water quality hazard.

     At the modest application rates proposed, especially with the
use of wood chips (with high C:N ratio, helping immobilize nitro-
gen from the sludge), it is expected that nitrate movement below
the root zone will be minimal, if any.  Heavy metals will probably
remain within the developing soil and become immobile and unavail-
able if pH is maintained above 7.

     Irrigated Farms--

     Irrigated farms generally possess some tail water control
provisions and are designed to achieve high water application uni-
formities and efficiencies, resulting in minimal wastage and con-
trol of excessive deep seepage.  With the use of sludge on these
farms, these controls are even more important.  Otherwise, (1)
excessive seepage will result in groundwater contamination with
nitrates and soluble salts, and (2) runoff could lead to direct
transport of sludge solids and soluble materials to the surface
water courses.

     It is difficult to quantify the precise impact of sludge
application on water quality.  The impact is not  only a function
of how well the recommended application rate limits are followed;
it is also determined by the manner in which other standard farm-
ing practices (irrigation, drainage, tillage, etc.) are performed.
It can therefore be surmised that the more sophisticated and suc-
cessful a farming operation is, the less are the chances for
sludge application on that farm to pollute water resources.  The
converse would hold true for poorly managed and operated farms.
Therefore, it is important that a judicious selection procedure
be set up and the material not be given simply to whoever asks
for it.  Binding agreements, permitting the District representa-
tives to conduct monitoring and inspection services, will help
guarantee against large-scale contamination of the water supplies.

     Home Gardens--

     If large numbers of homeowners and gardeners adopt sludge
amendment practices, some water pollution could occur.   Ornamental
plants and vegetables are typically heavily irrigated and very
often over-irrigated.  Therefore., both deep seepage into the ground-
water reservoir and runoff toward surface streams occur on a regular
basis, contributing to urban non-point runoff.   Opportunities for
improperly high application rates and consequent degradation of
water supplies are thus abundant in this type of recycling of the
sludge.   However, the total  amount of sludge thus used should be
relatively small  and will  be highly dispersed.
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Soil Properties

     Once sludge enters the soil, its impacts upon the various
components of the environment become indistinguishably interde-
pendent.  Thus, while this discussion is divided into separate
topics for clarity of presentation, the interdependence of the
physical, chemical and biological properties of the soil  and crop
responses, as well as animal  and human reactions to eating the
crops and animal tissues, should be clearly recognized.

     Soil Productivity--

     It can be expected that soil productivity will increase with
properly controlled and managed sludge application to any of the
proposed sites.  Many experiments with sludge application to soil
have borne out this conclusion (References 121, 122 and 123 to
cite a few), and some have shown increased productivity even above
that which could be expected from equivalent chemical fertilizer
applications (References 81 and 124).  The short-term annual in-
creases in yield, attributable to annual and residual releases of
sludge nitrogen, phosphorus and other essential elements, are by
no means the only contributions to soil  productivity.  A long-
lasting impact of sludge application to soils is the gradual in-
crease in the organic matter content of the soil  root zone.  As
              SOIL STRUCTURE IS ENHANCED BY SLUDGE


described below under Soil  Structure,  the increase in organic con-
tent leads to improved root penetration and other enhanced condi-
tions for plant growth, ultimately resulting in increased yield and
productivity.
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     If application procedures do not guard against uneven spread-
ing and variable incorporation of the sludge into the topsoil,  the
same types of problems as are associated with uneven fertilizer
application may be expected.   A typical  problem is non-uniform
soil fertility, resulting in  uneven growth, maturation and yield.
The commercial equipment available, if properly operated and main-
tained, can provide reasonably uniform spreading of the dry sludge.
Liquid sludge injectors which concentrate applications in a band
along the cutting "knife" will tend to produce a corrugated growth
and yield pattern during the  first few years unless successive  in-
jections are performed in a criss-cross fashion.

     Liquid sludge usually has a higher nitrogen content than dried
sludge and should be applied  at correspondingly lower surface load-
ing rates.  Furthermore, liquid  sludge tends to inhibit germina-
tion and to impose initial toxicity to young plants.  Damage can
be caused by excessive concentrations of ammonia, salts and organic
compounds or by creation of anaerobic conditions in the root zone
which reduce soil microorganisms and deplete oxygen in the soil.
The precise cause of initial  organic toxicity has not yet been  es-
tablished.  At recommended application rates, this initial  toxicity
will be limited to the immediate areas of application for only
short periods of time.  If injection of liquid sludge is limited
to periods far enough in advance of the growing season, the toxi-
city problem and related reduction in productivity will be mini-
mized.

     Phosphorus content of Metropolitan Denver sludge averages
about three percent of the dry solids (Reference 5).  Within the
recommended range of sludge application rates on irrigated farms,
8 to 35 metric tons/ha [3 to  16 tons/ac], about 240 to 1,050 kg/ha
[180 to 960 Ib/ac] of phosphorus (as P) is applied to the soil.
These excessive amounts of phosphorus would be potentially toxic
to plants were it not for two important considerations.  First,
phosphates in the sludge are  primarily in the precipitated form
and thus are not immediately  available for plant uptake.  Second,
the calcareous nature of soils in the irrigated farms, for the
most part, provides a ready mechanism for formation of insoluble
calcium phosphate forms which release available phosphorus to
plants over a long period of  time.  An important advantage of the
high phosphorus content of the sludge is its reported ability to
reduce the availability of zinc and nickel in the soil (Reference
124).

     An important aspect of increased fertility--particularly
nitrogen availability--is that continuous nitrogen availability
may make certain management practices more difficult.  For ex-
ample, in sugar beet culture, farmers have learned that by with-
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holding nitrogen and water in the last stages of growth, prior to
harvest, they can increase sugar content of the crop.  With the
use of sludge, this type of ready control of available nitrogen
may become difficult, if not impossible.  The Great Western Sugar
Company of Longmont, Colorado is presently conducting controlled
experimentation with the use of sludge on sugar beet farms (Ref-
erence 125).  Other effects of continuous availability of nitro-
gen, such as plant lodging, delayed maturation, color development
of certain fruits, etc.  generally do not apply to the types of
crops commonly grown in  the study area.

     Soil Structure--

     The anaerobically digested sewage sludge contains stable
humus-like organic compounds which resist decomposition, particu-
larly under irrigated farming conditions.  These molecules, when
well incorporated into the soil , tend to bring about changes in
soil structure which have long-term beneficial effects upon the
physical properties of the soil.  The importance of organic mat-
ter to soil conditioning has long been recognized by farmers who
have been applying barnyard manures, compost and other organic
wastes to soils since time immemorial.

     The principal change occurring as a consequence of organic
matter additions to the  soil is the gradual  formation of a loose,
friable soil structure,  contrasted with  the massive structure of
clayey soils and the granular character  of sandy soils.  Increased
organic content reduces  the possibility  of formation of shrinkage
cracks in clay soils and gives a more cohesive character to sandy
soils.  Epstein (Reference 126) found a  doubling of the percent of
stable aggregates in a soil  amended with sludge over a period of
175 days.  Organic matter increases the  water-holding capacity of
the soil; organic soils  can retain more  than their own weight of
water against gravity drainage, while a  sandy loam soil may hold
less than ten percent water.  Thus, successive applications of
sludge over the years slowly builds up the water-holding capacity
of the soil so that irrigation intervals may be increased, un-
wanted leaching of excess water reduced  and plant growth and yield
generally increased.

     The improved soil structure enhances root penetration and
vigorous growth throughout the soil  profile, leading to generally
healthier, more vigorous plant growth and increased crop produc-
tion.

     Soil Permeability--

     Movement of water through the soil  is governed principally
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by soil texture, structure, organic matter content, and the degree
of aggregation of clay particles.  Application of sludge to soil
can change the latter three parameters drastically, giving rise to
significant changes in permeability of the soil.  Epstein (Reference
126) reported an initial increase in permeability of a sludge-
amended soil followed by a return to initial  values.  Presumably,
the'initial increase occurred due to improved soil  structure,  and
the subsequent decline was caused by clogging of  pores.  Although
unsaturated hydraulic conductivities were not measured, it is  sur-
mised from increases in water content at all  soil-water tension
ranges that these conductivities probably increase with addition
of sludge to soil.  The increase in unsaturated conductivities
is important vis-a-vis water availability to  plant roots because,
commonly, unsaturated conductivity is the limiting factor in
moisture transport within the root zone.

     Soil Erodibility--

     Formation of stable aggregates, discussed above, helps increase
soil resistance to both wind and water erosion.  Additions of  sludge
over a number of years gradually reduces soil credibility and  thus
provides a self-correcting mechanism against  contamination of  sur-
face waters in addition to conserving topsoil . Many of the soils  in
irrigated areas are naturally moderately to highly erodible in the
absence of plant cover.  Over the years, sludge application can
significantly reduce soil credibility in these areas.

     Salt Accumulations--

     Liquid sludge from the Metro Denver Central  Plant contains
about 6,000 mg/1 total  salts, with only 180 mg/1  sodium and 140 mg/1
chloride.  Salt accumulation in the topsoil  can be regulated with
proper irrigation and drainage practices.  As long as the necessary
leaching fraction of the total  irrigation water requirement is pro-
vided, there should be no excessive salt buildup.

     Given a total dissolved solids concentration in liquid di-
gested sludge of about 6,000 mg/1, it can be  calculated that on
the average about 350 kg/ha [300 Ib/ac] of salts  will eventually
move into the groundwater reservoir.  These salts will be trans-
ported horizontally to downstream areas until the water is pumped
out again for irrigation or other uses.  Thus, over a very long
period of years (perhaps centuries), it can be expected that salt
buildup in the whole ecosystem will be inevitable.   Therefore, ir-
rigation water salt contents will increase gradually.  Even though
specific areas of sludge reuse will presumably be returned to  non-
sludge culture after the limit surface application rates are reached,
the salt content of the whole region will inevitably rise over the

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 long term,  as  new  areas  are  brought  into sludge application  cul-
 ture.   A more  recent  discussion of soil salinity is  presented  in
 Volume II,  Issue V-l .

      Soil  Impacts  on  Specific Sites —

      The general effects of  sludge application on soils, presented
 above, are  applicable to nearly all types of sites,  but are most
 representative of  the irrigated farms and home gardens, whether
 ornamental  or food crops are raised.  Specific variations from
 these generalities can be expected at other sites due to the dif-
 fering water regimes  and other management differences.  These var-
 iations are summarized for city parks, sod farms, mine spoil sites
 and  non-irrigated  farms.

      City  Parks—As discussed under Environmental Setting, most of
 the  City parks are constructed upon fill material from other areas,
 landfill  covers, construction debris and imported topsoil.  There-
 fore,  there is practically no indigenous soil  profile to be af-
 fected, directly or indirectly, by the sludge application and reuse
 scheme.  The pre-planting use of sludge and the proposed annual
 additions will aid in the formation and improvement of supportive
 substrata for City park plantings.  Improvements in  soil structure,
 water-holding capacity, root penetration, erosion resistance and
 permeability will occur, in similar fashion to those discussed
 above.

      It is  expected that much higher total  ultimate  loadings of
 heavy  metals can be allowed in City parks "soils" than in areas
 intended for food production.  Grasses and other plantings on park
 sites  are generally more tolerant to higher concentrations of
 heavy  metals in the soil.  Maintenance of high pH through a regu-
 lar  liming  program along with sludge application may be indicated
 through  testing of soil  pH on individual parks.  Use of sludge on
 City parks  subjected to a great deal  of foot traffic and compac-
 tion can be particularly effective in improving soil aeration and
 water  penetration.

     Sod Farms—The unique harvesting operations at  sod farms in-
 volve  the removal of a thin layer of soil (2 to 3 cm [0.8 to 1.2
 in.])  every year.  With this layer, most of the added organic
 matter  and  its constituents contributed by sludge are removed to
 their  ultimate location of use.  Thus, most of the direct soil-
 building potential  of the applied sludge is transferred to the
 ultimate consumer of the sod.  Since the amounts of sludge in-
 volved  in one cycle of sod production are relatively low, it is
 not expected that the effect upon soil  structure,  permeability,
and other physical  characteristics will  be significant unless the
consumer also applies sludge or other humic matter  to the lawns.
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The short-term positive impact on productivity is quite significant
and can exceed that of equivalent quantities of commercial  ferti-
lizers.  No significant salt-buildup in the soil  is expected.

     Mine Spoil Sites—Since at present there are no soils  on  the
surface of the mine spoil sites, no soil  impacts  are associated
with sludge application to these sites.  Natural  soils are  buried
beneath a great thickness of mine spoil materials.   Considerations
for soil building and reclamation of the sites to permit the nat-
ural succession of plant species are presented below under  Flora
and Fauna.

     Non-Irrigated Farms—The relatively low sludge application
rates recommended for non-irrigated farms and drylands make the
soil impacts relatively minor.  The amount of organic matter con-
tributed by sludge will average less than 0.1 percent of the plow
layer mass per year.  Furthermore, because of the dry conditions,
organic matter will be oxidized and destroyed more rapidly  than
under irrigated conditions.  Hence, it is not expected that any
perceptible improvement in soil physical  conditions will material-
ize as a result of sludge reuse.  Short-term soil fertility, how-
ever j will increase dramatically due to rapid availability  of
adequate quantities of nitrogen and other essential nutrients.

     Use of liquid sludge usually gives rise to an initial  toxicity
whose basic mechanisms are not yet well defined.   Special tools for
placement of liquid sludge in separate bands below the soil surface
have been developed and tested.  This type of liquid sludge appli-
cation, while conserving the maximum nutrient potential  of  liquid
sludge, minimizes initial toxicity by permitting  roots to grow
around the sludge areas rather than be confined thereby, and therein,
It is expected that future experimentation at the drying and dis-
tribution center will increase knowledge of soil  fertility/toxi-
city tradeoffs of the various application tools.

     Heavy metals accumulation in soil  will proceed at a rate far
lower than that of irrigated farms.  These metals will have ade-
quate opportunity to "revert" to unavailable forms in the cal-
careous soils typical of non-irrigated farmlands.  It is expected
that long before critical limits of these metals  (defined in
Section IV) are reached, industrial effluent exclusion or reduc-
tion schemes will have been instituted and implemented in the
Denver area, permitting almost unlimited periods  of sludge  reuse.

     Salt accumulation in the topsoil may become  a problem  after
many decades of sludge application.  Although annual salt accrual
rates are much lower than in irrigated farms (less than 20  kg/ha
[20 lb/ac]), lack of irrigation water, paucity of rainfall  and
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the  predominance of evapotranspiration rates all help keep salts
in the root zone of the soil.  It would take about 200 years, at
the  recommended sludge application rates, for soil salt content
to reach levels which would reduce crop yields significantly.
Thus, it appears that, instead of heavy metals, soluble salts im-
pose the upper  limit on ultimate surface application rates of
sludge in non-irrigated farms and other drylands.

Air  Qua!ity

     If dried sludge is left on the surface and subjected to blow-
ing  in the wind, hazardous air pollution conditions could occur.
Lead content of sludge is the most important constituent in the
airborne assimilation of sludge particles by humans, conceivably
causing cumulative toxicity to frequent passersby.  Other heavy
metals in sludge, as well as any surviving microorganisms, in-
cluding spores and eggs of parasites, could also be transmitted
by aerosols.  It is expected that proper application timing, sup-
plemental  sprinkling, and mechanical  incorporation of sludge into
the  soil will effectively eliminate the air pollution potential
of sludge reuse.

     Odors--

     Air-dried digested sludge, taken from the stockpiles, is ex-
pected to be nearly odorless.  When broadcast at the recommended
surface application rates and incorporated into the soil, it is
not  expected that odor from the sludge will  be detected at the
boundaries of the application sites except by those most sensitive.

     Liquid sludge, if applied with subsurface injectors (equip-
ment is manufactured by at least two  companies in the Denver area),
will  have no noticeable odor even at  close proximity to the ap-
plication equipment.  Spraying of the liquid sludge on the surface
with special  spreaders  behind tank trucks will  produce temporary
odors at close proximity to the application areas.  The higher the
application rate and the longer the sludge remains on the surface
before incorporation,  the worse the odors produced will  be.  On
the whole,  however, anaerobically digested sludge is stable enough
so that the odors produced are not very strong or offensive.

     The city parks and  home gardens  would be potentially the most
odor-sensitive application sites.   However,  the fact that sludge
has been applied to the  parks for years with no significant com-
plaints  is  a  good indication that continuation with digested  air-
dried sludge  will  have  no significant odor impacts.

     There may be  some odors the  first day or so  after  a large
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amount of sludge is spread on parkland.  This smell, which most
do not find particularly offensive, may carry for about a block.
The past practice of applying the sludge during low-activity per-
iods in the park reduces the airing-out period.   Similarly, ap-
plying the major portions in the winter when people tend to be in-
doors has effectively limited the number of complaints.

     If  any publicity is given this application practice, past
experience has shown that there will be a temporary increase in
odor complaints following the publicity.  Lately, sludge use has
become more commonly accepted as a positive conservation-minded
practice.

     It is expected that odor produced by sludge application to
such other sites as sod farms, mine spoil sites  and other farms
will be of minor significance due to the relative isolation of
such sites and the presence of other normally associated odors
(e.g. manure on farms).

     Air Quality Impacts on Specific Sites--

     Each site offers special opportunities and  limitations insofar
as air quality impacts are concerned.

     City Parks--It is expected that quick incorporation of sludge
into the seed bed, at the initial  stages of park establishment,
and into the turf during the annual  winter applications will mini-
mize air pollution hazards from this source.  The high accessibility
of these parks to human beings and the proximity of residences
make the potential impact on air quality quite significant.  Dried
sludge, blowing from the trucks as it  is hauled  to the City parks,
could, if not controlled, have highly  undesirable air quality im-
pacts.

     Sod Farms—Small  quantities of particulate  material may be
released to the air during and immediately after application of
the dried sludge material.  These effects may be heightened in the
presence of strong winds, especially during seed bed preparation
in the spring.   The frequent irrigation associated with sod farm-
ing would reduce the effect of dust blowing to insignificant levels.
The remoteness of sod farms further mitigates air quality impacts.

     Mine Spoil  Sites—The proposed reclamation  of mine spoil areas
is typically relatively short term.   Small  quantities of dust may
be released to the air during and immediately after the laying of
fine rock material  and composted sludge.  This effect may be in-
creased if winds are strong.  However, subsequent operation of an
irrigation system and growth of plants will mitigate this effect.

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The quantities of dust thus generated would only be a short-term
contribution to the air quality of the mine operations and would
be relatively insignificant, especially in view of the remoteness
of these sites from human exposure.

     Irrigated Farms—Sludge application on irrigated farms is_not
expected to give rise to deterioration of air quality if soil  in-
corporation of sludge and proper mixing are achieved immediately
upon application.  A significant threat from improper application
procedures, i.e. leaving dried sludge on the land surface, especial-
ly in windy conditions, can arise with the dispersal of particulate
matter on and beyond the farms.  Immediate mechanical incorporation
of sludge into the soil, followed by irrigation (or a fortuitous
rainfall), can control or minimize air pollution from this source.

     Non-Irrigated Farms--The threat of particulate dispersal  from
non-irrigated farms and other drylands treated with dry sludge is
rather severe.  No matter how well  dry sludge is incorporated  with
the soil, the dry nature of these lands will permit dust blowing
during severe winds.

     Application of liquid sludge,  on the other hand, with deep in-
jectors, will  alleviate this problem altogether.  This is particu-
larly important as dryland farms generally have soils whose deeper
strata are highly calcareous and can rapidly make heavy metals un-
available.  The binding effect of sludge on soil particles pro-
motes aggregate formation and reduces the potential  for the soil
to become easily airborne in moderate winds.

Flora and Fauna

     Impacts of sludge application  to land on vegetation and wild-
life is so highly site-specific that no attempt is made here to
make any generalizations.   At the risk of a few repetitions, im-
pacts are qualitatively described for each site under a separate
subheading.   Impacts on vegetation  are further discussed in more
detail  in Appendix D.

     City Parks and Home Gardens--

     Vegetation--Application of sludge to vegetation in the City
parks and  home gardens should have beneficial  impacts by stimu-
lating  plant growth.  Sludge contains all  of the elements that are
essential for  plant growth, and with proper application will serve
as an effective fertilizer.

     Any adverse impacts resulting  from sludge application would
be caused by excessive rates of application.  Grasses are tolerant
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of heavy metals and have a high rate of nitrogen uptake.   The per-
iodic mowing of grass will remove appreciable quantities  of salts
and nutrients that have accumulated in the plant tissue.   The salts
thus removed will probably be deposited in contained sanitary land-
fills.

     Grasses are effective in the control  of erosion and  runoff.
Surface runoff from the land would be minimized with a vigorous
cover of grass.

     Wildlife--Broad scale sludge applications would probably occur
in the late fall and winter during periods of minimal  park usage.
Sludge application, even on snow-covered areas, followed  by further
snowfall, minimizes the direct contact time for wildlife  and humans.
Overall bird populations are lower during  the fall  and winter, with
the exception of wintering species and semi-domesticated  species
such as rock doves.

     Sludge incorporation into the soil would probably have simi-
lar effects on burrowing and ground-dwelling rodents,  as  discussed
further below under wildlife impacts at the Lowry Bombing Range.
The effects may be less pronounced due to  the controlled  sludge
application rates and rodent control programs.

     Seed bed preparation with sludge supplement occurs generally
in the spring and late fall.  Bird species which forage on the
ground — such as robins and towhees--and feed upon terrestrial in-
sects and seeds are exposed to the sludge  mixture the  most.  These
birds may be exposed to a slight concentration of sludge  components
along the food chain.  However, these birds are not confined to
the City parks area and range throughout the urban areas.  Ani-
mals, including dogs, may be exposed to pathogens and  parasites
by direct exposure and ingestion.

     Sod Farms--

     Vegetation--The use of sludge as a fertilizer and soil condi-
tioner on sod farms will have beneficial impacts on sod production.
Sludge contains all the essential plant nutrients, and in some cases
sludge has been shown to generate higher crop yields than commercial
fertilizer.  Grass is a good crop for sludge fertilization because
it is tolerant of heavy metals, is not used as feed or food, has
a high rate of nitrogen uptake and minimizes problems  from runoff
and erosion.

     Wildlife--Due to the intensive management of a sod farm, di-
rect effects of sludge application upon wildlife would be few and
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probably limited to spring and fall during times of seedbed prep-
aration.  Bird species which forage on the ground—such as meadow-
larks and sparrows—feeding upon terrestrial insects and grass
seeds, are exposed greatly to the sludge mixture.  Heavy metals
and other sludge constituents accumulated by insects may be further
concentrated by bird predation.  On a well-maintained sod farm,
however, thick sod growth effectively minimizes uptake of sludge
constituents by insects.  The monoculture of selected short grass
species also represents an unbalanced ecosystem with only a few
insect and bird species.  Small rodent problems on a sod farm are
also minimal due to the poor burrowing quality of a thick, fibrous
turf and constant disturbance and "grazing pressure" of mowing
equipment.  Thus, incorporation of sludge constituents by small
rodents would not be a problem on this type of site.

     Mine Spoil Sites--

     Vegetation--The land application of stabilized sludge mixed
with wood chips to mine spoil sites will  have very beneficial  im-
pacts on vegetation.  Since mine spoil sites are typically devoid
of a substrate capable of supporting plant growth, the land appli-
cation of composted sludge would essentially be a soil building
process.

     Climax Molybdenum proposes to transport a total of 90 metric
tons/ha [40 tons/ac] of sludge mixed with wood chips (in a 1:1
ratio) to the mine spoil sites.  Assuming that this material  has
a density of 400 kg/cu m [25 Ibs/cu ft],  the total amount of com-
posted sludge to be applied will have a depth of 2.3 cm [0.9 in.]
before incorporation.   Proper substrate building procedures for
vegetation establishment should include:   (1) application of
smaller rocks above larger rocks; (2) application of well-graded
materials such as finely crushed rock and sand to a depth of 25 to
30 cm [10 to 12 in.];  (3) application of  the sludge-wood chip mix-
ture and (4) incorporation into the top 15 cm [6 in.] of the finer
material.  In this way, the top layer of  "soil" will contain ap-
proximately 13 percent organic matter after total composted sludge
application.  This is  a high percentage of organic material and
should provide a good  substrate for plant growth.

     The establishment of a ground cover  would probably follow the
basic pattern of plant succession.  Hardy pioneer species would
first become established and would slowly build up the depth of
the soil  profile over  time through decomposition of dead material,
thus permitting the growth and establishment of a more diverse
plant community.

     Plant succession  is generally an extremely slow process.   The
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rate of succession would depend on such factors as the amount of
sludge and other materials applied and the types of plant species
that are initially planted.  Grasses are relatively easily estab-
lished, but they do not provide large amounts of organic material
to be decomposed.  Some native shrubs such as bear berry and  buf-
falo berry, which are presently growing on the Urad Mine spoil
site, might be planted with some success.  These would provide
more substantial amounts of detritus in the form of leaf litter
than would grasses, although their rates of growth might be in-
hibited at first by the penetration of the roots deeper into  the
soil profile.  Trees might also be planted, although the penetra-
tion of their roots through the top layer into the coarse and
acidic spoils might limit their growth potential for many years.

     Because the total amount of sludge to be applied is relatively
low, the uptake of hazardous heavy metals, such as cadmium, zinc,
copper and nickel, should not present problems to plant growth.
Plant growth might be inhibited, however, by the uptake of heavy
metals present in the underlying spoil material, although this
situation should be alleviated over time as the soil  profile  in-
creases in depth.

     The establishment of a complete groundcover of vegetation  is
highly desirable since it can result in (1) earlier soil stabili-
zation and reduction of erosion; (2) earlier mitigation of acid
drainage in surface runoff through increased water holding capa-
city and through increased water use by evapotranspiration; (3)
acceleration of the accumulation of organic residues which will
chelate or otherwise make unavailable the soluble iron, manganese
and aluminum.  Organic residues also provide the necessary seed-
bed for plant germination.

     Wildlife--Mine spoils areas are typically rocky, barren  and
devoid of normal signs of life.  Application of sludge with in-
corporated wood residues would be an initial step towards the re-
clamation of these wastelands.  The successful establishment  of
vegetation over a period of time would help to restore some of
the habitat that had been destroyed by mining activities.

     Wildlife habitat would be minimal due to the severity of the
terrain and presence of limited types of vegetation.  However,  the
distinct transition from forested slopes to a broad open swale with
grass and shrub vegetation would provide an "edge" habitat favor-
able to wildlife.  Animals feeding upon vegetation in the re-
claimed mine spoils area are subject to accumulations of trace
elements as discussed under Food Chain, above.

     Limited sludge applications for only two years at relatively
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low rates greatly reduce the potential  for hazard.   Within 3 to 5
years, a permanent ground cover could be established.   Although
this habitat will not be very diverse,  the variation it provides
in the heavily-forested woods and Clear Creek Canyon is an impor-
tant ecological consideration.  With the decay of the  mine spoils
and long-term formation and maturation  of soils on  the site, larger
and more sensitive vegetation forms may become established.   Thus,
in the long term, partial or full reclamation of the mine spoil
sites would provide new wildlife habitats and an overall  benefit
to wild! ife.

     Irrigated Farms--

     Vegetation--Areas of irrigated farmland that are  subject to
the application of sludge are necessarily under cultivation  and
contain no native vegetation.  In general, sludge will have  bene-
ficial effects on plant growth by supplying all of  the essential
plant nutrients.   The accumulation of  hazardous heavy metals in
plants reduces the yield significantly  before these metals become
a danger to the food chain if the cadmium/zinc ratio is less than
one percent.  In the Denver sludge, this percentage is about 1.7
and poses a potential minor hazard.

     Selection of crops suitable for growth on sludge-enriched
soils should be made in consultation with the local extension
service of the U.S. Department of Agriculture.  Plants vary  widely
in their reactions to sludge application, and these reactions are
site-dependent.  Crops that are grown for their seeds  or  fruit
rather than for their vegetative tissue and crops whose younger
rather than older vegetative tissue is  utilized are more  desirable
in terms of trace element accumulation.

     Wild!ife--Insect populations and scavenging wildlife will con-
stitute a problem on sludge-amended farms, depending on the  type
of crop grown.  Large stands of monoculture represent  a greatly
simplified ecosystem with a preponderance of only a few insect and
animal species.

     Plants differ widely in accumulation of heavy metals and other
materials.  Zinc and copper in very small amounts are  micronutrients
beneficial to the animal  and human diet (Reference  127).   Evalua-
tion of potential effects of sludge on  wildlife and on domestic
animals requires individual  analyses of farms and of crop types
and their ability to accumulate trace elements.  The greatest con-
cern is for grazing animals who will consume forage crops such as
hay and alfalfa grown on sludge-aided soils.  Copper would be a
special hazard to grazing animals if sludge of high copper content
were sprayed on established pastures (Reference 128).   Leaf  surface
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copper is rapidly washed off with rain or irrigation water  but  re-
mains a hazard until removed.  "Dietary copper and  molybdenum  in-
teract in the ruminant.  When the molybdenum content of forage  is
known to be low, expected increases in copper content of some  for-
ages could be hazardous to sheep, while in forages  of normal molyb-
denum content copper can be considerably higher"  (Reference 128).

     Insects and small mammals dwelling in or feeding upon  ir-
rigated croplands are also subject to accumulations of trace ele-
ments and other materials.  Foliage-eating insects  and burrowing
rodents such as gophers are particularly susceptible.  These
secondary consumers in turn support upper levels  of the food
pyramid.

     Non-Irrigated Farms--

     Vegetation--The impacts to vegetation on dryland farms are
the same as those discussed under Irrigated Farms.   Agricultural
effects of sludge application are discussed in detail in Appendix
D.  In general, dryland farms will sustain a lower  rate of  sludge
application than irrigated farms because the rate of nitrogen  up-
take of dryland crops is much lower than that of  irrigated  crops.
Seed germination can be inhibited if planting operations are con-
ducted too soon after liquid sludge application.   If planting
is done from two weeks to one month after low-rate  sludge applica-
tion, seed germination is uninhibited.

     Wildlife—Sludge application would occur in  the spring or  fall
during seedbed preparation.  Application rates are  generally much
lower than on irrigated farms or sod farms.  Sludge constituents
are less likely to accumulate in the wheat and barley crops typ-
ically grown in dryland farming.  Thus, the hazards of high con-
centrations of trace elements are less significant.  The minimum
supervision and low maintenance required for a dryland farm allow
the fields to remain relatively undisturbed for long periods of
the year; thus, dry fields are easily incorporated  into the eco-
system and are suitable for wildlife habitat.  Mice, gophers and
jackrabbits particularly utilize this environment and will  be
constantly in contact with the sludge-treated ground.  Acute ef-
fects of grazing upon the vegetation are discussed  above under
irrigated farm impacts.  The low application rates  and low  uptake
of trace elements generally do not constitute a great hazard to
wildlife on a dry farm.

     Grazing animals and wildlife may be exposed  to pathogens  and
parasites by direct exposure and ingestion.  Pathogen survival  is
greatly reduced by stabilization; however, some parasite ova such
as Ascaris may remain viable for many years in the  soil.
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Noise

     Noise generated by sludge application (broadcasting, injec-
tion or spreading) equipment is expected to be similar to that
produced by similar farm and landscaping equipment, such as trac-
tors, trucks and manure spreaders.  Therefore, no particular noise
impact is anticipated.  Some reduction in noise may be expected
to the extent that sludge application replaces fertilizer and/or
manure application on these operations.

     In city parks, equipment and heavy machinery for applying the
sludge would generate noise levels that may be incompatible with
residential areas.  This noise generation is unavoidable, but is
generally limited to short durations a few times per year.  The
sludge application process is only a fraction of the parks main-
tenance program and, to some degree, is acceptable in consideration
of the benefits to vegetation and overall maintenance of the City
parks system.  Use of mufflers on such equipment can inexpensively
mitigate this minor problem.

     In sod farms, irrigated farms and dryland farms, continual
operation of farm equipment and the attendant machine noises during
the growing season are an integral part of the farming operations.
Some additional noise will be introduced by sludge transport trucks
delivering the sludge to remote plains areas.  In perspective,
sludge transport and application would only be a small fraction
of farm operations.  The local  climatological conditions and open-
ness of the plains help to disperse sound well.  In addition, the
low population density and isolation from other noise sources
make contributions from this part of the project insignificant.

     In mine spoil sites, noise generated from sludge transport
and application operations would by typically on a one-time basis.
The narrow valleys, steep grades and heavily forested slopes tend
to confine noises within the local area.   Noise generated during
sludge application and area seeding and planting would be greatly
masked by the noise from ore processing machinery at the molyb-
denum _mine.  Therefore, noise contributions from sludge transport
and mine spoil  reclamation would be relatively insignificant.

     In home gardens, sludge application  would probably be per-
formed with small  hand-operated equipment.   Noise from such
machines as rototillers might disturb neighbors for short periods
of time.

Aesthetics

     Since  people  generally accept the fact that fertilizer  must be
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applied to the lawns and gardens of the parks, and since the dried
sludge does not have a particularly offensive appearance, no sig-
nificantly adverse visual impacts are expected from the continued
application of the material to the parks.  As an added precaution
to avoid offending anyone's aesthetic sensibilities, the Park De-
partment attempts to apply the material during seasons and times
of the week when park use is low.  Applying the black material  to
snow-covered lawns in winter would make it highly visible until
the next snow.

     Application of sludge to mine tailings has a beneficial
aesthetic impact since it prepares the barren spoil areas for
the grass and tree plantings, examples of which are now success-
fully in progress.

     It is expected that the inert appearance and the nearly odor-
less characteristics of the dried sludge will  help overcome the
psychological image associated with the fecal  origin of the mate-
rial.  Positive experience with sludge over a period of several
years might reduce the negative aesthetic impact.
Natural Resources

     The resource value of sludge
is discussed at length above, un-
der the drying/distribution site
impact analysis.

     Intensive farm operations
(such as sod production and
other irrigated agriculture)
can deplete natural resources
over large areas.  The rapidly
growing plants extract large
quantities of nitrogen and
other elements from the soil.
In addition, thin layers of
soil material are removed from
the sod farms during harvest-
ing.  Without soil supplements
or some form of compensation,
a sod farm could deplete the
soil resource in a relatively
short time.  Sludge applications
would serve not only as a
fertilizer but also as a soil
DRIED SLUDGE
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 conditioner.  Dried sludge is high in nitrates and contains other
 macronutrients and trace elements required for plant growth.  Per-
 iodic cropping and annual harvesting can remove some accumulations
 of trace organic materials.  However, the long term accumulation
 of salts and trace elements may preclude sludge applications after
 a finite period of time, as discussed in Section IV.  Therefore,
 with controlled applications over a long period, sludge reuse on
 farms can  help maintain the soil resource.


     Mine  spoil areas are generally highly disturbed areas with
 effectively few resources.   The application of sludge to these
 waste areas is the initial  step towards reclamation of the areas.
 Establishment of ground cover will  eventually lead to the buildup
 of a stable ecosystem.  While the reclaimed areas may never be
 able to duplicate the original ecosystem, they would constitute
 a vast habitat improvement for wildlife resources and the natural
 system.  Thus, the proposed action would accrue an overall benefit
 by partial restoration of natural resources.

 Traffic and Circulation

     Most  of the sludge application sites will not be significantly
 affected insofar as traffic and circulation patterns are concerned.
 For example, if the City and County of Denver Park Department
 ultimately utilizes 4,500 metric tons [5,000 short tons] of dried
 sludge as  anticipated, average daily trips will increase annually
 by 200 (References 40, 77).   Since travelways such as Irondale
 Road and connecting major highways near the Denver urban core are
 adequate in design to accommodate this minimal increase, no sig-
 nificant impact on transportation and circulation patterns will
 ensue should the proposed project be implemented.

 Agricultural  Economy

     The agricultural  economy in the area will be aided by the pro-
 posed project, since it will  provide a local source of fertilizer/
 soil  conditioner,  a resource in increasingly short supply.  The
 nutrient benefit value of the design production capacity of 97
metric tons/day [107 tons/day] of dried sludge solids is worth at
 least one million  dollars per year at present prices.

     The productivity increases resulting from sludge application
will  undoubtedly vary among  the individual  farms using the material.
However, field tests by Metro Denver have verified the general  in-
creased  productivity results achieved elsewhere with agricultural
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 use  of  sludge.   For  example,  in well-managed  sludge application
 programs  there  have  been  2- to 4-fold  increases  in forage pro-
 duction,  2.5-fold  increases in wheat production, and 20 percent
 higher  corn  yields than were  achieved  by commercial fertilizer
 (Reference 81).  Mismanagement of the  sludge  application on farms
 could have adverse economic impacts.   Application rates in excess
 of those  recommended by the soil scientists and  agronomists could
 limit productivity due to  high nitrate or heavy  metal levels.

     A  small  benefit to the farmers  in this somewhat arid region
 is the  fact  that the "dried"  sludge will be about 50 percent water.
 Assuming  design  capacity  production at 97 metric tons/day [107 dry
 tons/day] of dry matter in the sludge, there  would be about 36,000
 cu m [30  ac-ft]  per  year  water in the  sludge.  This is a relatively
 small amount of  water and  will be distributed very thinly over a
 relatively large area.

 Land Values

     The  proposed  project  is  expected  to provide a free or inex-
 pensive fertilizer/soil conditioner for agricultural operations
 within  the delivery  area  of the sludge drying/distribution center.
 This will probably have a  positive  impact upon land values, based
 on the  assumption  that the sludge will improve the productivity
 of the  lands which receive it.  This assumption  seems justified
 by the  evidence  from other areas which have used anaerobically
 digested  sludge  as fertilizer.

     Chicago and Orlando  are  two of  a  number  of  cities which have
 demonstrated the agricultural benefits of controlled land applica-
 tion of sludge  for crop production.  Denver,  San Francisco, San
 Diego,  New York, Las Vegas, Miami and  other cities have used
 wastewater treatment plant sludge for  park and lawn development.
 In other  countries too, sludge is used for agricultural purposes
 (examples are Melbourne,  Australia;  Leipzig,  Germany; and the
 West Hertfordshire Main Drainage Authority in London, England).
 Increases in land  values  in sludge  application areas are in part
 attributable to  improved  productivity  of the  land.

Summary of Land Application of Sludge on  the  Recycling  Areas

     The most potentially  severe  negative  impacts are in  the  food
chain due  to  heavy  metals  uptake  by  plants  and animals.   Public
health  hazards and  water quality  problems  also rank  quite high
in potential  adverse  impact.   The worst application  sites vis-a-
vis reuse  of  sludge are  home  gardens,  city  parks  and  irrigated
farms,  while  the best sites are mine spoil  sites, sod farms and
dry farms.  The greatest beneficial  impacts are  in  improved soil
productivity  and conservation  of  resources.  A schematic  represen-
tation  of  the impacts at various  sites  is  presented  on  Figure
17 (page 138).

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IMPACTS OF SUBSURFACE INJECTION OF LIQUID SLUDGE AT THE
DRYING/DISTRIBUTION CENTER

     The Metro facilities plan called for the injection of some of
the liquid sludge on a 24 ha [60-acre] portion of the proposed site.
The area was contemplated by Metro to be both a demonstration area
and a possible secondary disposal  area for excess sludge.

     Metro's current plans call for only limited use of subsurface
injection of liquid sludge for demonstration purposes or for emer-
gency disposal of sour sludge.  In the original plan, injection of
sludge at rates up to 175 dry tons/ha [78 dry tons/acre] would have
been used.  At this rate, there is significant potential for ground-
water contamination from salts, and nitrates.  EPA will  require as a
grant condition that subsurface injection be limited to agronomic
rates, based on the nutrient supply for the area.  This will result
in very little leaching of nitrates to the water table, as most will
be utilized for plant growth.  The rate of sludge application will be
low enough that very little problem from salts reaching the ground-
water should be encountered.

     At the high application rates originally proposed, the fate of
the soluble nitrogen forms in the  soil is extremely important.   The
ammonia in sludge would be partially tied up on clay particles, mak-
ing it available for longer periods of time to plant; but  with  dry-
land crops and some inhibitory effects,  very little of the nitrogen
would be used by crops.   Gradually some of this nitrogen would  be con-
verted to the nitrate form and would migrate to the groundwater.
Severe localized effects could be  expected in groundwaters receiving
the nitrate slug with the leachates.   Because of this potential pro-
blem, the decision to limit subsurface injection to agronomic rates
was made.   This method of sludge utilization has shown promise  in
recent studies, and further study  of its effects under carefully con-
trolled conditions is warranted.

     The only time subsurface injection  of sludge will  be  used  as a
disposal  method is if,  inadvertantly,  sour or malodorous sludge is
sent to the site.   This  would prevent  the sludge from ever being
exposed to the air and  creating odor problems.   This event is expected
to occur only rarely, if at all, as under normal  circumstances  sour
or improperly digested  sludge will  be  retained at the plant for cor-
rection of the problem  and proper  digestion  before being sent to the
site.
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IMPACT OF SLUDGE DISPOSAL AT LOWRY BOMBING RANGE

     The disposal of sludge to the Lowry Bombing Range represents
the "no-action" alternative and would be continued if agricultural
reuse of sludge is not implemented.  Since sludge is currently being
applied at a relatively high rate on the bombing range, this  area
provides the opportunity to assess the effects of sludge applica-
tion.   The Metro Denver Sewage Disposal  District No. 1 is currently
engaged in several research programs to  determine some of these
effects (Reference 114).  Various types, rates and methods of
sludge application are being used to measure the precise impacts.
The results of Metro Denver's research project should provide
quantitative data on high-rate sludge application at this site.
The District's history of experience with land application of
sludges, gained at the bombing range, will be a valuable asset in
future reuse programs when the results are published.  A summary nf
impacts of the present operation is graphically shown on Figure 18.
            CONTOUR STRIP SLUDGE APPLICATION AT LOWRY
Food Chain
     The entry of heavy metals into the food chain is a potentially
adverse impact on areas of high-rate sludge application.   Animals
accumulate heavy metals not only from eating the plants,  but also
through direct ingestion of soil and sludge on the pasture areas.
The composition and amount of sludge that is applied as well as
soil conditions and plant characteristics are crucial factors in
the availability of heavy metals.  These relationships are dis-
cussed in detail in Appendix D.  The Metro Denver research project
should provide quantitative data on food chain parameters.

     Of all the land application areas studied, the present opera-
tion at the Lowry Bombing Range comprises the greatest potential
                              167

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                                                                    FIGURE 18
        SUMMARY IMPACTS OF SLUDGE DISPOSAL AT THE LOWRY BOMBING RANGE
                          LANDSPREADING OPERATIONS
	Impact parameter     	Direction and intensity'

          Food chain

          Public health

          Soil productivity

          Soil salinity

          Soil heavy metals

          Water quality

          Flora and fauna

          Odor

          Noise

          Personnel effects

          Plant operation and effluent quality

          Aesthetics

          Public reactions

          Natural resources

          Land use                                   £

 •3
  Symbols  signify relative impacts, as defined below:

                                          High   Moderate   Low

      Positive (beneficial) impacts:      C J

      Negative (adverse) impacts:
This schematic representation of impacts should only be interpreted within the
context of analyses of impacts presented in the main body of the EIS.   It is
neither an attempt at quantifying the impacts nor reducing the diverse environ-
mental parameter to common bases for comparison.  However, it does provide a
rough ranking of the relative importance of the various impacts.
                                      168       ENGIN E ERING-SCIENCE, INC.

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hazard to the food chain with cattle, destined for the slaughter-
house and the grocery store, grazing unrestricted on sludge-amended
areas.  Overall, existing operations represent only a moderate
adverse impact.

Public Health

      In the past, no significant health problems have been associ-
ated with the Lowry Bombing Range sludge disposal operations.   If
these operations continue, it is expected that, under most condi-
tions, the public health situation will not change.  However,  the
relative longevity of pathogens in soil (especially enteric para-
sites and their eggs or cysts, such as Ascaris ova) and the daily
proximity of workers and other project personnel with the sludge-
loaded soil would continue to present a health hazard that must
not be underestimated.

      Effects on Personnel--

      The present landspreading system in use at Lowry presents an
operating hazard to workers on the site.  The high concentration
of lime used to disinfect the sludge makes the material to be  ap-
plied very caustic (pH 11-12).  Injuries to skin and eyes of
workers have resulted on occasion.  Application by truck of a
semi-solid sludge also poses an operating hazard with the danger
of overturning or losing control of the truck.  With the advent
of anaerobic digesters, the pH of the sludge would be nearer a
neutral value  (7) and would present less of a hazard to workers.

Plant Operation and Effluent Quality

      If the present Lowry operation is continued, with the addi-
tion  of anaerobic digesters, recycle of supernatant from the di-
gesters is expected to have a negative impact on the Metro Central
Treatment Plant (see discussion on page 124).
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Soil Properties

     As long as soil incorporation of sludges at the currently
 heavy  rates are kept below the conservative guidelines  (presented
in  Section IV under irrigated farms and in Appendix D), it is ex-
pected that soil conditions and properties at the Lowry Bombing
Range disposal site will improve with increased fertilizer levels
and organic matter.  Obviously, nitrogen and other fertilizer com-
ponents of the applied sludge will be  far in excess of that
needed for the weeds and grasses growing on the site.  The organic
matter content of soils will  rise to about 1.75 percent in the top
15  cm  (6 in.) of the soil, at the current 400 metric ton/ha [175
 ton/acj total  loadings.  This value will continue to rise as more
 sludge is  added to  the soil.  This is a significant increase over
 the background  levels of less than 0.5 percent.  Thus, great
 immediate  benefits  to the soil structure, permeability, water
 availability,  root  penetration and erosion resistance will accrue.

     The  relatively high natural  pH  in  these  soils  will  help  keep
heavy metals  concentrations from  becoming  toxic to  plants  and  a
threat to  the food  chain.   The main  difference  between  the bombing
range condition and that of the  irrigated  farms is  that the  impact
occurs over a much  shorter  period  of  time  in  the case of the  bomb-
ing range.   Thus,  salt  accumulation  in  the  root zone  will  occur
rather rapidly, especially  with  the  low rainfall  levels and  lack
of a significant additional water  source limiting downward move-
ment of soluble compounds.  At  current  application  rates,  total
soluble salt content of  the soil  plow layer will  be increased  to
0.2 percent of the  soil  mass,  assuming  that initial  salt content
is nearly  nil.  This level  of  salt concentration is not expected
to cause more than  a 30  percent  plant yield reduction (Reference
115), given the existing vegetation.   In fact,  the  yield reduction
will probably be overshadowed  by  increases  arising  from enhanced
fertility  levels and soil conditions.

Water Quality

     The  Lowry Bombing  Range  sewage  sludge  disposal  operations pro-
vide a unique opportunity for  a  quantitative  assessment of impact
of sludge  reuse on  water quality.  Already, a network of catch
basins, spring stations  and monitoring  wells  have been  established
by the Metropolitan Denver  Sewage  Disposal  District No. 1  in  the
immediate  areas of  past  and present  sludge  disposal.   Sampling and
analysis of waters  from  these  stations  started  in 1973  and are
expected to continue on  a  regular  basis for an  indefinite  period
of time.   The groundwater  conditions  are monitored  through a  large
number of  shallow  and deep  wells  in  the areas of soil incorpora-
tion of sludge.  The cooperative  program was  started  in late  1974
by the U.S. Geological  Survey  and  Metro Denver  District and  is
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continuing at the present time.

     Preliminary raw data from the surface water analyses are still
not enough to help assess actual impacts.  It can be surmised from
the trends that nitrate nitrogen is already finding its way into
surface waters and the shallower groundwater reservoirs.  Individ-
ual catch basin concentrations of 29, 88 and 95 mg/1 nitrate nitro-
gen (as NOs) measured recently are alarming though not necessarily
indicative of wholesale contamination.  Most of the analyses indi-
cate concentrations below 5 mg/1.

     Preliminary data from the groundwater analyses show vertical
nitrate migration in areas downstream of the older land disposal
areas  (8 to 44 mg/1 N03-N) and in the vicinity of the landfill
(13 to 23 mg/1 N03-N).  Although these are single-sample prelimi-
nary results they may indicate real trends.  Despite certain doubts
about  the origin of the nitrogenous materials these trends may
continue.  Nitrate levels in groundwater could rise over the com-
ing few years to levels above 45 mg/1 (as NOg), the limit at which
their  use for drinking water would be inadmissible.*

     As expected, heavy metals concentrations have not yet increased
in groundwaters,  whereas preliminary measures in the topsoil  have
confirmed their accumulation.   These metals are not expected to  move
downward in these calcareous,  relatively high-pH soils.   The con-
tinuing monitoring programs are an important advance warning system
in this regard.   The final report for the Lowry groundwater study  is
discussed in Volume II, Issue  II-l.

Flora and Fauna

     Vegetation--

     Continuation of high-rate sludge application on the Lowry
Bombing Range will  cause similar impacts to the vegetation that
can now be observed on that portion of the bombing range that has
received sludge.   This site is referred  to as Site A and is shown
in Figure E5.  The sludge application process itself results in
the complete displacement of the existing vegetation.   However,
no rare and endangered species have been reported on this site
(Reference 34), and relictual  mixed-prairie units, which are be-
coming scarce in the Denver area, do not occur at the disposal  area.
This conclusion was made from  a field reconnaissance and should  be
verified by more thorough site surveys if land application is to


^Recommended limit for nitrate nitrogen  in domestic waters is
 45 mg/1  as NOg.
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continue.  The original  mixed-prairie unit has long been exposed
to heavy grazing and presently contains many introduced annual
grasses and annual  and perennial  weeds.

     The immediate impact of sludge application would be to stimu-
late the growth of weeds.  The major weedy species found on Site A
(common sunflower, Russian thistle, summer cypress and tumble pig-
weed) are fast-growing colonizers of bare soil whose growth has
been enhanced by the nutrient value of the sludge.  Over a long
period of time, certain grass species would become established  in
the absence of grazing.   Other management inputs,  such as weed
control and planting, would accelerate this process.  As long as
the site is grazed, however, cattle will selectively crop grasses
and the weeds will continue to be dominant.

     The establishment of a vegetative groundcover is essential to
control soil erosion and surface runoff.  Although grasses are
superior to weeds in checking erosion, the dense weedy growth on
Site A does serve to limit problems resulting from soil erosion and
runoff.

     Site A is being used for a research project by Metro Denver
Sewage Disposal District No. 1 on the effects of high-rate sludge
application on vegetation and cattle (Reference 114).  Two major
areas of concern are the high nitrate levels and the accumulation
of heavy metals in plants and in the food chain.  Many common
weeds have high nutrient requirements (nitrogen, phosphorus and
potassium) which limit to some extent the amount of nitrates that
can be leached into the groundwater.  Perennial  grasses also have
a high nitrogen requirement.  The movement of heavy metals into
plant tissue depends on many factors.  The high phosphorus content
of the sludge tends to make zinc, cadmium and nickel unavailable
to plants.  This property might be somewhat reduced by the cal-
careous nature of the soils.  Calcareous soils have a high pH and
tend to make phosphorus unavailable and immobile.   Cadmium is po-
tentially hazardous in the food chain, and its movement within
the soil-plant system can be controlled by limiting the amount
applied.   In this way, excess zinc would injure the crop before
the zinc or cadmium content of the crop constituted a health
hazard (Reference 116).   This relationship is explained more
fully in Appendix D.

     Seed germination is inhibited if planting operations are con-
ducted too soon after the application of liquid sludge.  If plant-
ing is done from two weeks to one month after sludge application,
seeds germinate successfully.
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     The impacts of high-rate sludge application to this  site will
presumably be quantified when the Metro Denver research report is
available.

     Wildlife--

     High-rate application of sludge upon the Lowry Bombing  Range
produces a distinctive plant community as described above.   The
resultant plant growth would exhibit a tendency towards a  variety
of herbaceous annuals.  These fast-growing "weeds"  can compete
with the existing grasses and are often thick-stemmed, fibrous,
and in some cases bearing thorns.  They are generally less  suit-
able than the short grasses for animal forage, but  may be  grazed
upon in the tender stages or during periods of food scarcity.  The
ability of various plant species to accumulate sludge constituents,
such as heavy metals, depends upon many factors as  discussed in
Appendix D.  High concentrations of zinc, copper and cadmium in
forage could have deleterious effects upon animals.  However,  se-
vere toxicity injury from metals normally occurs in vegetation at
lower concentrations than those toxic to animals.   Some grazing
animals, particularly sheep, are unusually sensitive to copper and
could be injured by eating some forages enriched in copper  by
sludge.  Few studies have been conducted on particular animal
avoidance by taste or odor of vegetation grown on  sludge  (Refer-
ence 117).  In general, when suitable grass forage  is available,
grazing animals will eschew the tough and unpalatable "weed"
species.  Cadmium and zinc are accumulated generally in the  foliage
and are found only in low concentrations in fruit,  root and  grain
parts.  Wild grains, seeds and fruit from grasses  and "weeds",
particularly sunflowers, would provide a satisfactory food  sup-
plement for seed-eating birds and small mammals.  This would be
particularly beneficial to wildlife in the fall and winter.

     The shift in plant species would also result  in a change in
the microclimate on the surface and several centimeters below the
surface.  The broad-leafed herbaceous plants with  relatively
deeper root systems would contrast sharply with the groundhugging
short grasses with shallow, fibrous root systems.   The combination
of reduced insolation and semi-moist organic material in  the soil
would lead to decreased surface and substratum temperatures  with
slight increases in humidity.  This micro-environment may  be par-
ticularly favorable to invertebrate species and may encourage the
establishment of new species as well.  The low-diversity and un-
balanced plant ecosystem may also lead to the preponderance  of
only a few species.

     High-rate sludge application and mixing into  the upper  soil
zone would probably have the greatest direct effect upon  burrowing
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and ground-dwelling rodents.   Initial  sludge application would
temporarily destroy the uplands vegetation habitat and cause a
displacement of local rodent  populations to adjacent areas.  With
the re-establishment of vegetation and aging and maturation of the
organic-laden soil, some rodents—such as pocket gophers and ground
squirrels--may return to the  area.  Ground squirrels are generally
seed-eating and use the underground burrows chiefly as retreat and
nesting areas.  Pocket gophers, on the other hand, reside almost
exclusively underground, burrow continuously and feed upon sub-
terranean root stocks and other material.  The gopher may actually
accumulate sludge constituents such as heavy metals through direct
ingestion as well as digestion of plant material.   A decrease in
rodent numbers may not be significant  to humans, but nevertheless
is important to the ecosystem balance.  Gopher populations within
an area may have a contributing effect upon the food chain, as
these small animals are preyed upon by hawks, eagles and coyotes.

     Grazing animals may be exposed to pathogens and parasites by
direct exposure and  ingestion during feeding.  Pathogens will be
greatly reduced over time and by thorough incorporation.  However,
parasite ova such as Ascaris  may remain viable over many years,
potentially causing serious animal diseases.

     The ecosystem shift and  effects upon wildlife are localized
to the sludge application areas and are generally short-term.
Without further sludge applications, the altered vegetation com-
munity would gradually change to an upland vegetation unit in
three to five years.  With continuing  periodic sludge application,
this altered and unbalanced ecosystem  could be perpetuated over
the long term.

     Large-scale sludge application at the Lowry Bombing Range may
affect the habitat of the endangered black-footed  ferret.   If the
project destroys any prairie  dog towns on the site, it may affect
the main food source of the black-footed ferret.

Noise

     Continuation of the present landfilling  and high-rate sludge
application methods would perpetuate the existing  noise levels
from machinery and associated activities.   As stated under the
environmental  setting,  the climatological  conditions and openness
of the prairie would disperse sound well.   In addition, the low
population density and  isolation from  other noise  sources  make
the noise contribution  from the project almost insignificant.
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Air Quality

     The application of sludge to the bombing range should not ad-
versely affect air quality if the sludge is promptly incorporated
into the soil.  The potential for particulate matter to rise and
be dispersed exists if the sludge is stockpiled or not incorporated
soon after optimum moisture condition is reached.  Particulate
matter can contain heavy metals and microorganisms that might be
ingested by people.  Lead, particularly, is a health hazard.  When
the sludge 'is well mixed in the soil, the potential  for dust and
particulate dispersal  is reduced by the soil-binding character of
the organic matter in sludge.

     Odor--


     The present operation's odor problems  are not now serious and
are not expected to be significant in the future.  Under present
operations, with largely undigested sludge, odors are easily per-
ceived at close proximity to the application  areas.   The small
amount of air-dried anaerobically digested  sludge currently stock-
piled is almost free from odors.

Aesthetics

     Continuance of operations at Lowry Bombing Range would have no
significant adverse aesthetic impact.  The  isolated  area and neigh-
boring landfill operations place the operation in an unobtrusive
setting.  Even at the close-range view, the application areas re-
semble newly-plowed fields.
                 SLUDGE ON LAND BEFORE PLOWING
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Traffic and Ci rcu1 at1 on

     Should the proposed  project  not  be  implemented,  truck traffic
to and  from the Metro Denver Central  Plant  facility  and  the Lowry
Bombing Ranqe will  continue  at  a  rate of thirty-five  to  forty
truck trips per day until  such  time as an alternate  disposal
method  is adopted.

Public Reactions

     Earlier adverse public reactions concerning Lowry operations
resulted from  system inadequacies which have since been remedied.
The  number and validity of the complaints about odor have been
dealt with in  the  section devoted to that topic.  Continued use of
the  Lowry  site would probably result in continuance of these com-
plaints.  Complaints have averaged about one per month, with 80
percent  found  to be due to some other source, and the remaining
20 percent due to  inclement weather or operations breakdown  (Ref-
erence 39).

Natural  Resources

     The lands on  the Lowry Bombing Range are currently utilized
as range and pasturelands and, thus,  this area exists as a grazing
resource.  As  such, the potential for grazing has been reduced in
areas of sludge application by the lack of range management prac-
tices that would ensure adequate forage species composition.  Al-
though these areas have been reseeded with wheat and forage grasses,
the  continuation of grazing combined  with the absence of weed con-
trol has produced  a site that is dominated by weeds and has margin-
al value as rangeland.  Continuation  of sludge application in the
absence  of sound range management techniques would thus constitute
a reduction in the grazing natural resource.

     High-rate sludge application could beneficially affect this
natural  resource if a weed control program was implemented and if
the  potential were recognized for hazardous heavy metals entering
the  food chain, and possible overloading of salts and nutrients
in the soil.

     The application of excessive amounts of sludge under a high-
reate application  program constitutes a loss of nutrient resources.

Land Use

     Should the proposed project not  be implemented, the Lowry
Bombing  Range may continue to be the  application site for Metro
Denver sludge.  There is evidence that heavy metals are building
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up in the soils as a direct result of intensive sludge application
(Reference 118).  This would reduce the types of uses which the
disposal area could otherwise offer.

IMPACT OF SLUDGE LANDFILLING AT LOWRY LANDFILL

     The landfill ing practice near the Lowry Bombing Range is es-
sentially a winter-weather and emergency practice which comprises
a portion of the "no-action" alternative.  During the winter, when
it is difficult to perform the regular soil  incorporation practices,
sludge is dumped at high rates on prepared bench-and-terrace areas.
Sludge is emptied from the backs of trucks to a depth of 60 cm [24
in.] and mixed at a 5:1 ratio with soil.  This amounts to a loading
rate of 670 dry metric tons/ha [300 dry tons/ac] per year.  Winter
landfill ing during December, January and February has been prac-
ticed since 1971 but is expected to cease if the proposed agri-
cultural reuse plan is implemented.

Soil Properties

     Native soil is removed from the landfill areas prior to dump-
ing sludge.  The soil  is stockpiled and used to mix with the sludge
during dumping and for final cover.  At the very high rates used,
sludge components will saturate the cation exchange sites of the
soil and increase its salt content, making it a practically unpro-
ductive material for crop production or pasture.  The increased
water-holding capacity caused by increased organic content will
help delay leachate formation but will not prevent it in the long
term.  Overall, the impact upon the soil from landfilling will be
destructive and extremely long lasting.

Water Quality

     Nitrates and heavy metals will gradually be leached by perco-
lating rain water and carried toward the groundwater reservoirs.
Already, concentrations of nitrates in well  waters in the vicinity
of the landfill area are significantly above background levels;
i.e., 13 to 23 mg/1 in contrast to background levels of 0.01 mg/1
or less.  These trends are expected to continue unabated unless an
impermeable layer is placed on top of the old fill areas and be-
neath the new ones.

     It is expected that heavy metals will gradually move downward
toward the water table from the landfill unless leachate-prevention
mechanisms are implemented.
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     Surface water pollution from the landfill ing operation is ex-
pected to be minimal  because of the soil  cover  provisions and prior
site preparations minimizing runoff from  the sites.

Flora and Fauna

     Vegetation--

     The impacts of a landfill  on vegetation are of  a complete and
long-term nature.  Existing vegetation is removed with the excava-
tion of trenches for sludge disposal.  At the completion of dis-
posal operations, the District  plans to overlay the  area with a
topsoil material and revegetate with annual  grasses.  The success
of the revegetation program depends primarily on such factors as
soil conditions and management  inputs, such  as  weed  control.
Grasses are generally tolerant  of heavy metals  in the soil, and the
establishment of a permanent groundcover  in  this area would prob-
ably not encounter any severe problems.  Heavy  metals accumulating
in plant tissues should be recognized as  a reality,  particularly
if the site is to be grazed by  livestock.

     wndlife—

     Long-term disposal  of sludge at the  Lowry  Bombing Range by
landfill ing would cause a definite change in the local plant com-
munity and a probable shift in  wildlife species.

     Landfilling, which would probably be a  seasonal activity, in-
volves complete destruction of  the existing  habitat  by excavation,
trenching, and deposition of sludge and placement of soil  cover
over the mound.  Wildlife, particularly small mammals such as mice,
ground squirrels and jackrabbits, would be displaced to adjoining
areas, causing temporary population stresses.  The completed land-
fill cover would be relatively  barren because of poorer soil con-
ditions, rapid runoff, poor water retention  capability and greater
exposure.  This anomaly in the  landscape  would  be difficult to
incorporate into the upland vegetation habitat  and is effectively
lost to wildlife usage.   Landfilling as a method of  sludge disposal,
however, does not disturb as great an area as does broad-scale
surface application because the material  is  concentrated in a
smaller area.

Air Quality

     Because the landfilling operation is restricted to the winter
season and adequate final  cover is provided, no air  pollution po-
tential is expected from this operation.   Safeguards against ero-
sion and removal  of the  final cover are essential, to maintain the
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sludge under constant cover and to prevent it from drying and blow-
ing in the wind.

     Odor--

     Similarly, if the final cover is maintained, no odors will
emanate from the site.  Otherwise, the landfill  can be expected  to
produce disturbing odors, detected at considerable distances, as
past experience with unauthorized dumping has indicated.

Explosive Gas Production

     Solid waste landfills in general, and sludge landfills in par-
ticular, produce significant quantities of combustible gases such
as methane during the process of anaerobic decomposition.  When
mixed with air  (5 to 15 percent combustible gas  in the mixture),
they are explosive and can pose a safety hazard  to humans in the
vicinity.  Special provisions for venting such gases are  necessary.

Land Use

     Whether the proposed project, i.e., beneficial agricultural
reuse of sludge, is implemented or not, general  uses of the Lowry
landfill will be unchanged since the area will remain a disposal
site for the Denver urban area.

Resources

     Burying the sludge in a landfill constitutes wastage of a re-
source of potentially high fertilizer and soil-conditioner value.
The extent of this loss can be visualized from the discussion of
impacts of sludge application on the soil, discussed in this
Section and in Appendix D.

Summary of Impacts of Sludge Disposal  at the
Lowry Bombing Range

     As currently practiced, the land spreading  operation at the Lowry
site exerts the greatest negative impact on the  food chain through
pasturing of domestic animals on sludge-amended  fields.   Heavy metals
accumulation in the soil,  salinity of the soil and groundwater quality
problems are other negative impacts of the current practices.   Improved
soil productivity and a partial  conservation  of  natural resources are
among the beneficial  impacts of the present disposal  operations.  These
impacts are schematically represented in Figure  18.
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^r.

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w
 h
mt
H

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     This section contains recommendations for
possible modification of the original project
proposal (or in the case of land application on
reuse areas, additional controls that were not
contemplated in the facilities plan)  to reduce
or eliminate environmental impacts.   Negative
impacts of major elements of the land applica-
tion plan—processing, off-site application
and the Lowry operation—are listed,  and miti-
gative measures are recommended.

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                            SECTION VI

      NEGATIVE IMPACTS AND RECOMMENDED MITIGATIVE MEASURES
     Key negative impacts identified and discussed in Section V are
listed in this Section with possible mitigative measures  which may
be selected during the review process of this Draft ELS for final
implementation.  These tentative mitigation measures are  recommenda-
tions by EPA and its consultant (Engineering-Science, Inc.) for con-
sideration by the reviewing agencies and the public.  Through the
review process, acceptable effective measures will be selected from
those presented here and those which may be offered by the reviewers
of this document.  The measures thus selected will become an inte-
gral  part of the design and operation of the facilities planned by
Metro before Step 3 grant monies are extended for the construction
of the facilities.  The final EIS will  include the selected mitiga-
tion  measures.

     It is extremely important that whatever mitigative measures are
adopted be integrated with the planned monitoring and surveillance
activities so that symptoms detected by the monitoring system can
lead  directly into specific mitigative action.

PROCESSING, TRANSFER, DRYING AND DISTRIBUTION

Groundwater Pollution by Nitrates and Salts Leaching
from  Sludge Drying Basins

     Lining the bottom and sides of basins with impermeable materials
is the only fully effective way to mitigate nitrate and other salt
accumulations in the groundwater.  Nitrate movement can probably be
slowed by maintaining anaerobic conditions in the bottom layer of  the
drying beds (this possibility has not been fully demonstrated as a
guarantee against nitrate movement).  Provision of drainage networks
below the basins can be effective against nitrates and other salts
but will not stop all leachates from moving to the water table.
This  method is more effective if an impervious layer is also in-
stalled.  Furthermore, the collected drainage water must also some-
how be safely disposed.

     Return of the supernatant from the digesters to the treatment
plant headworks (rather than pumping it along with the sludge to the
sludge drying and distribution center)  would be a great help in re-
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ducing salt pollution of the groundwater.  Drying of the superna-
tant in separate, lined drying basins and containment of the dried
salts would also be a suitable—though partial—alternative mitiga-
tion measure against alt buildup in the groundwater.   A discussion
of alternative types of liners is found in Volume II, Issue IV-2.

Surface Water Pollution from Experimental Plots

     Impoundment of runoff water in reservoirs at the lowest parts
of the center and treatment or proper disposal (e.g.  irrigation of
experimental plots and wetting the sludge stockpiles  on windy oc-
casions) of the waters gathered can adequately mitigate surface
water pollution.   This is part of the current site design.

Potential Threats to Public Health

     Pathogen transmission through the air and through surface run-
off waters and nitrate contamination of groundwaters  are two main
threats to public health which can be detected through continuous
monitoring of pathogen longevity and groundwater quality under the
drying and distribution site.   Mitigation measures for public health
hazards could include: (1) lining the drying basins with impermeable
materials, (2) provision of special medical  services  for the employees
at the center, (3) restriction of public access to the site, (4) main-
tenance of optimal digestion conditions in anaerobic  digesters, (5)
provision of special medical monitoring and  preventive treatment to
persons frequenting the site for taking delivery of sludge loads and
(6) a strict ban against pumping of undigested sludge at all times.

Proliferation of Insect Vectors on Sludge
Drying  Basins

     A qualified entomologist  should be retained at the early stages
of full utilization of the drying basins to  identify  specific insects
colonizing the basins.  Control measures defined through the identifica-
tion process should be implemented.

Air Pollution from Particulate Matter of
Sludge Origin

     Sprinkling of the stockpile areas during windy periods and stor-
age in gently sloping heaps (in contrast to  high abrupt mounds) would
help minimize dried sludge being blown in the wind.  However, with
above-ground storage it will not be possible to completely  prevent  loose
material  from  being  blown.

Production of Nuisance Odors in Drying Basins

     Odors can be minimized with proper digestion of  sludge and main-
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tenance of an adequate buffer zone between the basins and site bound-
aries.  Odor production on the site itself cannot be wholly prevented.

Negative Public Reaction to Establishment of
the Drying and Distribution Center

     A proper public education campaign with full disclosure of all
environmental, economic, political and social considerations involved
with the project should provide a healthy atmosphere of open dialogue.
This will help improve the acceptability of the drying and distribu-
tion center to the neighboring farming community.

LAND APPLICATION IN SLUDGE RECYCLING AREAS

     Lands which will be the ultimate repositories of dried sludge
will be the most critical impact areas in the sludge handling process.
This is due to the fact that many of the impacts discussed are of
a cumulative, long-term nature.  Therefore, mitigative measures
are essential for success of the beneficial reuse scheme.   EPA
will require that sludge be retained onsite until state regulations
on sludge management are finalized.

Heavy Metals Accumulation in Soil, Plants.
Animals and the Food Chain

     (1) Removal or reduction of sources contributing heavy metals to
the wastewater management system will mitigate many of the adverse im-
pacts on soils, plants, animals and the food chain.  This can be done by
enforcement of the  existing wastewater ordinance, setting tolerable
limits on concentrations of exotic substances entering the sewer sys-
tem, thus forcing industries to adopt in-plant measures to curb dis-
charge of heavy metals.

     Exclusion of industrial and other heavy metal discharges from the
wastewater treatment system will allow prolonged use of sludge on the
various sites.

     (2) Control of cadmium:zinc ratio is another important mitigat-
ive measure.  If this ratio is kept below one percent, acceptability
of sludge for use on feed crops and foods will be greatly enhanced
through the plant yield reduction effected by zinc, long before either
element accumulates in toxic concentrations.

     (3) Record-keeping, inspection of sludge application operations
on individual sites and monitoring of environmental parameters are
functions which must be carried out by the District or another res-
ponsible agency in close cooperation with  individual farmers  and oper-
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ators.   These functions will  prevent inadvertent aggravation of im-
pacts by excessive, non-uniform or careless applications of sludge
and will mitigate the adverse impacts.   It may be necessary to ob-
tain binding agreements with  recipients of sludge to permit inspec-
tion and monitoring and to provide for cessation of sludge supply
in cases of noncompliance with recommended management practices.

     (4) In many cases, it may be necessary to subsoil  the farmland
prior to or during the first  sludge application pass, in order to
bring to the surface some of  the calcareous material in the lower
soil horizons.   Alternatively, lime amendment would also help in-
crease soil pH,  if necessary.   This will  help hasten the "rever-
sion" of heavy metal  elements  to unavailable forms.

     (5) Crop selection to favor non-foliar edible parts and younger
rather than older plant parts  can help  reduce magnification of cad-
mium and other heavy metals in the food chain.

     (6) Surface spraying of  liquid sludge should be avoided, espec-
ially on pasture areas where  it may be  directly injected by livestock,

     (7) If research indicates that it  is  warranted, exclusion,  at
the slaughterhouse, of kidneys and livers  from  the meat of animals
having grazed on--or having been fed hay  and other feeds raised  on--
sludge-amended farms  and the  disposal  of  these  organs at a sanitary
landfill would be an  excellent mitigation  measure.   The ability  of
these organs to  concentrate heavy metals  would  thus  be  beneficially
used as a device to eliminate  them from the food  chain.

     (8) Restrictions  or discouraging  use  of sludge  on  home gardens,
especially where leafy vegetables are  grown.

            LIVESTOCK GRAZING ON SLUDGE-AMENDED  FIELD



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Nitrate Pollution of Groundwater, Especially in
Irrigated Farms, Sod Farms, Home Gardens, City Parks

     While the  active process of leaching of nitrates into the
groundwater table cannot be avoided, the extent and duration can
be substantially reduced.  Periodic "lonitoring should be conducted
on qroundwater assoicated with ead  ,ite that is receiving sludge.
Before nitrate concentrations reach 45 mg/1 N as N03, usage of
sludge should be curtailed, and the groundwater should be restrict-
ed from potable use.  Such a measure would be most appropriate in
the vicinity o* shallow groundwater supplies used for domestic pur-
poses.

Nitrate Pollution and Eutrophication of
Lakes and Other Water Bodies

     (1) The pollution of surface waters can be mitigated by strict
control over application rates so that a balance between nitrogen
uptake by plants and available nitrogen content of sludge is adhered
to as closely as possible.  Water quality should be monitored to de-
tect any buildup of nitrates.

     (2) Control of the tailwater in irrigation systems and use of
standard runoff and erosion control practices on the farm can reduce
the threat of surface water pollution.

     (3) Riverbeds, flood plains and steep slopes should be categor-
ically excluded from sludge application, unless positive tailwater
control is included.

     (4) Careful watering practices by users should include insur-
ing that surface runoff does not occur.

Air Pollution from  Particulate Matter
of Sludge Origin

     Participate matter from dried sludge applied to soils can be
reduced by several means:  (1) deep incorporation of sludge into the
soil by mechanical means as soon as possible after  application; (2)
subsequent irrigation to keep particulate matter in the soil;  (3) ap-
propriate scheduling to avoid or minimize sludge application during
windy conditions—particularly in the springtime; (4) opportunistic
timing to apply sludge immediately prior to forecasted rainstorms arid;
(5) injection of liquid sludge deep below the surface wherever tiis
is a feasible practice.

Exposure of Humans to Viable Pathogens
and Parasj_te_s_

     (1) The use of sludge which has been air-dried for at  least  two
years would greatly reduce the numbers of viable pathogens.  Addit-
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ional  methods of pathogen reduction in sludge include:  (a)  pasteur-
ization for 30 minutes at 70°C [158°F]; (b)  high pH treatment, typi-
cally with lime, at a pH greater than 12 for three hours; (c)  long-
term storage of liquid digested sludge (if applicable)  for  60  days
at 20°C [68°F] or 120 days at 4°C [40°F]; (d) complete  composting at
temperatures above 55°C [131°F] for at least 30 days;  (e) use  of chlo-
rine or other chemicals to stabilize and disinfect sludge.   Current
research shows preliminary promise in the use of high energy electrons
for disinfection of sludge passing in a thin stream in  a specially
adapted process.  The feasibility of use of these and other means of
pathogen destruction should be continually considered for application
and use.

     (2) The possible introduction of pathogens into surface waters
will be mitigated if sludge is not applied in the close vicinity of
lakes and other water bodies.

     (3) Soil and water monitoring for pathogens should be  regularly
conducted.

     (4) Use of sludge on vegetable crops (such as  in home  gardens)
and all foods eaten raw should be strictly banned.   EPA guidelines
suggest a three-year waiting period prior to using  sludge-treated
land for food crops to be eaten raw by humans.

      (5)  Use  of sludge on parklands should be controlled to avoid
areas  where  humans could come in contact  (e.g. grass areas) and lim-
ited  to areas where control can be maintained  (new sod, flower gar-
dens).  Sludge  applications should also be limited to  times of the
year  when chance of exposure  is slight.

Exposure  of Animals to Viable Pathogens
and Parasites

     Mitigative measures such as those enumerated above, under Expos-
ure of  Humans to Viable Pathogens and Parasites, are equally effec-
tive  in protecting domestic animals and wildlife from  adverse effects
of  sludge pathogens and parasites.

Odor

     Proper timing of sludge application will mitigate  odor impacts.
Further mitigation measures applicable to odor are discussed above,
under Air Pollution from Particulate Matter of Sludge  Origin.

Adverse Public Reactions

     The promotion of a public education program to inform the public
of the benefits and potential effects of sludge application will al-
most certainly increase acceptability of the concept and its wide-
spread adoption in the farming community.


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Initial Toxicity of Liquid Sludge to
Seeds and Young Plants

     Where liquid sludge is applied on irrigated or non-irrigated
farms, mitigation would consist of a delay of planting  until  one
month after application.

Injection of Sludge From
Foil age and Soil

     (1) Spraying of sludge on growing crops  and pastures  should be
avoided;

     (2) Cattle should not be pastured on land having received  sludge
recently;

     (3) Sludge should be incorporated into the soil  as  soon  as pos-
sible;

     (4) Use of deep liquid sludge injectors  should be  encouraged,
particularly on dryland farms and pastures.

EXISTING DISPOSAL OPERATIONS ("NO ACTION") AT LOWRY
BOWING RANGE

Heavy Metals Accumulation in Soil, Plants,
Animals and the Food Chain

     This impact could be particularly severe in areas  where  livestock
grazing is conducted.   It is somewhat mitigated by the  limitation  of
total application rates.  However, the high time rate of application
causes uneven incorporation and high local concentrations,  posing
hazards to the food chain.  Should it be demonstrated that grazing
in sludge application  areas, results in high  organ metal  concen-
trations, then livestock should be prohibited from grazing on sludge-
amended fields.  For mitigation measures, refer to page 183.

Possible Loss of Unique Vegetation
Type

     The location of any relictual mixed-prairie units  should be veri-
fied by a thorough site survey.  Loss of any  existing examples  of
this type would be mitigated by the exclusion of these  areas  from
future sludge application sites.
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P o s s i ble Destruction of Rare and _Endari£ered^
     The occurrence of any rare and endangered plant species should
be verified by a thorough site survey.   Destruction of these plants
would be mitigated by avoiding areas where they may be found.  Appro-
priate botanical authorities should be  notified of the location of
rare or endangered plants.

Possible Loss of Black-Footed
Ferret Habitat

     The location of any  prairie-dog towns should be noted, and a
thorough site survey conducted to determine concurrent habitat assoc-
iation for the  endangered black-footed ferret.  If the black-footed
ferret is found on the site, its habitat should not be used for sludge
application.


Air Pollution from Parti cul ate Matter
of Sludge Origin

     Mitigative measures  are discussed above, under Sludge Recycling
Areas.

Reduction of Grazing Resource

     The implementation of range management practices, such as weed
control and the exclusion of livestock from treated areas until a
forage crop is well established, will mitigate this impact.

LOWRY LANDFILL

Removal of Wildlife Habitat

     A rigorous attempt at revegetation of the final cover over the
landfill area will help restore the habitat to some extent.

jjroundwater Pollution

     Unless the bottoms of new fill  areas  and the  surfaces of old
areas  are covered  with impermeable  materials  such  as  liners or clay
layers, groundwater will  be polluted with  nitrates,  salts, carbon
dioxide gas and perhaps even heavy  metals  over long periods of time.

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Explosive Gas Production

     Use of venting systems, standard on sanitary landfills,  can
prevent accumulation of explosive concentrations  of combustible
gases generated in the sludge fill  area.  Such  systems  are  not
now in place at the Lowry landfill.
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     The long-term implications of the Metro
proposal and the continued use of the Lowry
system are reviewed in this Section.  First,
those impacts of an adverse kind that cannot
be avoided—even with the use of mitigating
measures proposed in Section VI—are described.
Next, consideration is given to the irrever-
sible commitments of resource use that will
occur with this proposal or with the existing
system.  Finally, an evaluation of overall
productivity in the long run is presented.

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                           SECTION VII

                     LONG-TERM CONSIDERATIONS
     Major projects such as the large-scale reuse of sludge on the
land have long-term implications which are often different from (and
sometimes far more significant to environmental  parameters than)
those initially envisaged.

     The state of knowledge on precise impacts of sludge reuse on
land is in the state of infancy.  Thus it is relatively difficult
to determine accurately the short-term effects (such as water pollu-
tion, public health hazards, air pollution, food chain disorders,
etc.).  There is even less basis for quantifying long-term effects,
which may be far more pernicious and pervasive than short-term im-
pacts, as a whole.  By the same token, the beneficial  long-term ef-
fects that can now be described only generally and qualitatively
may in time prove to have been totally underestimated or grossly ex-
aggerated.

     The very unknown nature of future cumulative impacts should be
ample warning to proceed with caution, to use sludge on lands where
known impacts are minimal (such as sod farms, mine spoil sites and
dry farms) and to avoid those where we now know the impacts can be
significant (such as home gardens and farms growing crops consumed
directly).  The transitional state of knowledge about sludge reuse
impacts also makes it extremely important that the planned and neces-
sary additional monitoring activities on all environmental parameters
be implemented rigorously and diligently to provide early warnings
of hazardous conditions which may be developing.

ADVERSE IMPACTS THAT CANNOT BE AVOIDED

Sludge Drying_and Distribution Site

     Disturbance of 240 Hectares [600 Acres]
     of Soi1--

     The destruction of soil profile to create the drying basins can-
not be mitigated.  Once the natural  soil strata are destroyed, they
cannot be exactly reconstituted, nor can they be restored to those
that were formed under natural  soil-forming conditions over geological
time.   Long-term reclamation including the use of sludge, could
restore some or all  of the former productivity of the land.  The
nature of the subsoil material  will, to a great extent, determine the
potential  for rehabilitation.

                               191

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     Salt Movement Toward Groundwater Table--

     Up to 190 metric tons [210 tons] of salts will leach each year
from beneath the sludge drying basins under present design conditions.

     Nitrate Pollution of the Groundwater
     Reservoir--

     Unless further research and possible procedural  adaptations can
assure complete denitrification at the bottom of the drying basins,
pollution of the groundwater by nitrates leaching from the sludge
drying basins will  be unavoidable under present design conditions.

Land Application Sites for Recycling Sludge

     Salt Accumulation in the Region--

     The soluble salts in the sludge constitute a cumulative, con-
servative (i.e. not subject to breakdown) pollution of the soils
and waters of the whole region.  Their dispersal  over a very large
area, as expected in the agricultural scheme, only delays the time
at which their increasing regional  concentration will  become per-
ceptible.  The time frame for such  accumulation will  probably be a
few hundred years.

     Exposure of Burrowing Animals  to
     Pathogens and Toxic Elements--

     No effective long-term mitigation measures exist  to prevent
burrowing animals from possible exposure to pathogens  and trace
elements by ingestion or direct contact.

     Mismanagement and Consequent
     Unmitigated Adverse Effects--

     Under present plants, no firm  controls on the ultimate users
of the sludge are envisioned.   The  possibility is very real  that
some of the recipients will  fail  to include recommended mitigative
measures in their sludge use activities.   This could  result in the
negative impacts enumerated  in Section VI,  under Land  Application
in Sludge Recycling Areas, to become threats to the region.
                               192

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Lowry Bombing Range Sludge Disposal
Area (No Action)

     Salt Accumulation in Soils--

     No mitigation measures exist for the addition and accumulation
of inorganic salts in the soils under present applications rates
and conditions.

     Nitrate Pollution of Groundwater--

     At the current very high annual application rates, far more
nitrogen is introduced into the soil than can be utilized by the
plants.  The balance is partly denitrified and partly leached--with
the occasional rainwaters—below the root zone and toward the ground-
water table.  The impact upon groundwater quality will not be evi-
dent for many decades because of the very slow rates of unsaturated
flow of water.  But eventually, perhaps in 50 to 100 years, impacts
will begin to appear.  It will then take many more decades to re-
verse the trend.

     Ingestion and Direct Contact with Sludge
     by Burrowing Animals--

     No effective long-term mitigation measures exist to protect
burrowing animals from the possible exposure and accumulation of
sludge constituents by ingestion or direct contact.

     Exposure of Domestic Grazing Animals to
     Heavy Metals Accumulation, Viable Pathogens
     and Parasites--

     Under present practices, domestic livestock graze the sludge-
amended fields without restriction, ingesting sludge along with soil
particles which comprise about ten percent of their regular diet.
To the extent that the "no-action" alternative implies continuation
of this and other existing practices, endangerment of animal health
and the subsequent food chain impact are a potential hazard.

     Waste of Nutrient Resources--

     No mitigation measures exist for the loss of nutrient resources
under a high-annual-rate sludge application program, or when sludge
is landfilled under emergency circumstances.

IRREVERSIBLE AND IRRETRIEVABLE RESOURCE COMMITMENTS

     Four main resource commitments are involved in the proposed
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project:

Destruction of Soil Profile

     Destruction of the soil  profile on 240 hectares [600 acres] of
land at the site of the proposed drying basins is irreversible.
These areas would be unfavorably altered as"agricultural  areas  with
their characteristic soils.

Energy Use

     Commitment of fossil  fuels to produce energy for treatment, pipe
transport, trucking and other sludge handling processes is necessary
and irretrievable.  The total value of this commitment for the  pro-
posed action has been estimated to be about eight million KWH per
year.  However, it is estimated that total savings in energy use accom-
plished by implementing alternative 2 (compared with the  "no-action"
alternative) amount to at least 28 million KWH per year.

Groundwater Use as Receiving  Medium

     Commitment of the groundwater reservoir as final repository of
soluble salts and nitrates leached from the applied sludge is im-
plicit under present design conditions for the sludge drying and dis-
tribution center.  Over several centuries, salt accumulations in the
groundwaters will gradually become increasingly appreciable.  It is
a slow but inevitable process that can only be corrected  by nature
over a similar length of time after cessation of land application
operations.

Application Site Soil Commitment

     Commitment of the soil root zone as a final repository of  heavy
metals (and in some locations soluble salts) in the sludge is inevit-
able as long as sludges continue to contain these materials.  This
allocation of the soil resource is irreversible in the sense that up-
on completion of the land application it will take many centuries of
continuous cropping to remove the heavy metals, through gradual  up-
take, from the soil.

RELATIONSHIP BETWEEN SHORT-TERM USES OF THE HUMAN ENVIRONMENT AND
THE MAINTENANCE AND ENHANCEMENT OF LONG-TERM PRODUCTIVITY

     The land recycling proposal by Metro will probably have a  dura-
tion of 25 to 50 years.  This is a rather long period of  time,  given
the rapidity of change in today's society.  Nevertheless, it is  a
fair and important question to ask what the implications  of the  proj-
ect may be for the next few hundred years—with regard to the soils,
                               194

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the water and other areas of human environmental  concern.

Conservation of Non-Renewable
and Renewable Resources

     Such an evaluation can begin with the baseline of how the  pro-
posed system compares with the existing Metro sludge handling and
disposal system.  At present, high doses of lime, ferric chloride
and polymers are necessary to obtain a dry enough sludge for truck
hauling.  Furthermore, the dewatering and trucking operations are
fairly energy-intensive, requiring the use of electricity  and fos-
sil fuels.

     The Metro proposal represents a positive step in conserving
natural resources by eliminating the need for chemicals.  Over  a
50-year period, more than 200,000 metric tons [220,000 tons] of
ferric chloride and 450,000 metric tons [500,000 tons] of  lime
could be conserved, along with a smaller tonnage of complex fossil-
based polymers.  These are chemicals that have little or no value
to Denver area soils or in the landfills.

     Overall, there is a net energy saving with the Metro  proposal
of at least 8 million KWH per year.  While this overall  amount  rep-
resents a small fraction of the total energy used in the Denver
metropolitan area, it nonetheless represents a significant step
toward an energy efficiency and conservation ethic in wastewater
management.  The chief purpose of chemicals and energy in  inputs
to the sludge handling process is stabilization and drying of the
sludge.  In the proposed system, anaerobic digestion is used in
lieu of chemicals and energy to stabilize the material; the pro-
posed air-drying process represents a shift toward the use of solar
energy in the drying basins, replacing mechanical dewatering sys-
tems, which require much energy derived from use of non-renewable
fossil fuels.   Solar energy is an inexhaustible replacement for
these rapidly diminishing fossil fuels.

     In the long term, the recycling of nutrients to the soil  rep-
resents a forward-looking step for a society that will have to  rec-
ognize the finite limitations of its natural resources.  At present
the bulk of our commercial fertilizers is produced from fossil
fuels, particularly natural gas.  While future sources of fertilz-
er (especially nitrogen fertilizers) will probably include coal,
this, too, is a fossil fuel which has its limits.  If nitrogen
that has already been fixed (that is, made chemically reactive, as
is the case with amino acids, proteins, nitrates, ammonia, etc.
found in sludge) is reused, society will be able to make much  fur-
ther use of the resources for which there are no substitutes.
                               195

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     At present, the primary source of phosphorus fertilizer is de-
posits of phosphate that are extremely limited.   Because phosphates
in wastewaters are concentrated in sludge as a result of the treat-
ment process, land recycling can be an important long-term mechanism
for reuse of this element, providing soils with one of the macronu-
trients essential for crop production.

     A third long-term benefit of land application of sludge from
the Metro system is its effect on soil structure.  Sludge contains
large amounts of organic matter; in semi-arid areas of the western
United States, where soils are poorly developed  and are high in
clay content, the addition of organic matter to  the soil mass im-
proves the friability of the soil and increases  its water-retention
capability.  Ultimately the soil becomes more porous and allows
greater root penetration.  Agricultural  experts  usually warn against
depletion of the organic matter in soils through exclusive use of
commercial fertilizers.  The Metro project could reverse this trend
by recycling carbonaceous matter to the soil.

Potential Cumulative Long-Term Environmental Damage

     A long-term view of the Metro proposal  must include potential
harmful effects.  Because sludge contains elements that may be toxic
or that may occur in combinations that are harmful, the potential
exists for some long-term damage to the productivity of soils for
growing crops.

     Many of the trace elements of concern (zinc, copper, iron, etc.)
are micronutrients when found within appropriate ranges of available
concentration in the soil.  It is their availability in excessive
quantities that can produce toxic or inhibiting  effects on plants.
Growing plants continually remove small  quantities of these elements
from the soil as they are cropped, but this  removal rate is far too
slow to be expected to remedy the effects of rapid additions of the
elements through sludge application—until  centuries after applica-
tion has ceased.

     Another undesirable aspect of sludge application is the addi-
tion of salts to the soil profile.  Over a long  period of time,
salts can have an inhibitory effect on plant growth.  This problem
is not confined to the Metro sludge operation but is common to all
irrigated agriculture.  Increased salinity of soils has an extreme-
ly harmful effect on the food-producing capability of a region.  It
is generally recognized in irrigated agriculture that proper long-
term maintenance of an irrigated soil includes a leaching require-
ment, for flushing these salts below the root zone.  This is accom-
plished through application of additional irrigation water, which
commonly is subsequently collected in subsurface drains.  While
                               196

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potential soil salinity can be remedied by leacning and drainaye
in irrigated agriculture, its occurrence on nonirrigated farms as
a result of sludge addition would be inevitable.

     Salts can also become contaminants of the groundwater resource.
On any given sludge application area, the total  annual  salt load
from applied sludge will be fairly small.  It is  at the sludge dry-
ing and distribution center tnat the greatest potential for effects
on groundwater can occur, hence the need for lined basins and  other
mitigative measures.

     The chief measure for avoiding tne detrimental long-term  ef-
fects of soil salinization and heavy metal  accumulation is limita-
tion of the amount of sludge applied to any one area to what is
considered safe for that type of soil and land use.  Recommended
safe levels are still somewhat tentative; any long-term assessment
of tnis project must recognize that some effects  may conceivably
occur in a manner different from that stated here.  However, assum-
ing that no change in sludge heavy metal content  will  occur, there
is nothing at present to indicate that any completely irreversible
damaging effects on productivity of the soil, through the proposed
sludge application system, might occur.

     What is most critically needed for the future is a researcn
program to find out what can and will happen on various soils  with
applications of sludge.  Maximum allowable heavy  metal  loading
rates (hence sludge application limits) may have  to be adjusted
downward or upward as experience with actual sluage application be-
comes available.  EPA feels that the limits so far recommended rep-
resent a conservative approach to protection of tne soil.

The Long-Term Environmental  Perspective

     EPA feels that, viewed from an overall perspective, this  proj-
ect can put into action the goals of the National Environmental Pol-
icy Act.  Although that part of NEPA requiring environmental impact
statements has received the greatest attention,  it should be remem-
bered that the basic intent of iJEPA is a national environmental pol-
icy integrating the actions of people with their  environment.   One
item in particular stands out in articulating this policy in the
Act which the proposed project can help achieve:

     10(b)(6)...[to] enhance the quality of renewable resources
     and approach the maximum attainable recycling of depletable
     resources.

     The extent to which the proposed project can  increase use of
renewable resources (such as nutrients, organic matter and  solar
energy) while decreasing dependence on nonrenewable chemicals  and
                               197

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fossil  fuels is considerable.   If the additional  measures recommended
to protect against untoward  effects (such as groundwater contamina-
tion and  heavy metal  accumulations) are included,  EPA believes that
this project can become a  valuable pioneering effort toward bu^J'.i:
                                                              or
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                             198

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     An important provision of the National En-
vironmental Policy Act is that during the EIS
process responsible public agencies and the pub-
lic must be provided ample opportunity to parti-
cipate and make contribution to the EIS.   This
Section is a brief report of the extent and na-
ture of such involvement in the process of prep-
aration of the EIS.  Discussions and letters
from citizens and Federal, State and local agencies
in response to the Draft EIS are contained in
Volume II.

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                           SECTION VIII

        COORDINATION WITH AGENCIES AND PUBLIC INVOLVEMENT
GOVERNMENTAL AGENCIES

     During preparation of this Draft EIS, regular contact was main-
tained with the various public agencies charged with responsibili-
ties for the environment, waste management, public health, food safety,
water supplies, agricultural  production, soil  conservation and other
public concerns related to the project.  Among the agencies whose re-
cent, current and planned activities were monitored in relation to
sludge management are:

     Various internal EPA units
     Metro Denver Sewage Disposal  District No. 1
     Denver Regional Council  of Governments
     Colorado Department of Health
     Adams County Commissioners
     USDA Soil Conservation Service
     U.S. Food and Drug Administration
     U.S. Bureau of Reclamation

     The Preliminary Draft EIS, prepared by Engineering-Science, Inc.
in November, 1975 was reviewed by the EPA and  local agencies dir-
ectly involved with the proposed project.  The comments received from
their review have been of value in upgrading the present Draft EIS.

PUBLIC INVOLVEMENT

     The proposed Metro Denver sludge management program has elicited
significant public reaction.   Some of the reaction was solicited by
the District through public meetings and formation of a Citizens'
Advisory Committee, formed in 1972, consisting primarily of represen-
tatives of interested agencies.  Interested groups and property owners
near the proposed site were also represented.   The members of the com-
mittee were:

     Beverly Fleming        Keep Colorado Beautiful (Chairwoman)
     Gary Eaton             Adams County Engineering
     Bob Fleming            Adams County Planning
     Alan Foster            Denver Regional Council of Governments
                                99

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     Jim Fowler              Sierra Club, Enos Mills Group, Denver
     William Gahr            Colorado Department of Health, Engineer-
                               ing and Sanitation Division
     Mike Gansecki           U.S.  Environmental Protection Agency
     Jack Haines             Adams County
     Richard Heaton          Denver Water Board
     Bernard Korbitz         Presbyterian Medical Center, Department
                               of Medicine
     Glenn Kreag             CSU Extension Service, Adams County
     Fred Matter             Colorado Department of Health, Water
                               Quality Control Division
     Rodney Preator          Soil  Conservation Service
     Elizabeth Richardson    League of Women Voters
     Steve Rohlf             City of Commerce City
     Robert Sandquist        Adams County
     Calvin Tupps            Property owner in proposed project area
     Wayland Walker          City and County of Denver Planning Office
     Bob Wardell             CSU Extension Service, Adams County
     Ann Ziegler             Property owner in proposed project area
     Bob Ziegler             Property owner in proposed project area

     While the reactions of environmentalists and public agencies
were generally favorable, the public meetings with citizens of ru-
ral Adams County showed a strong resistance to locating the site in
their vicinity.  Earlier plans to locate District facilities in Weld
County had met with similar resistance.   The 1972 meeting in Bennett--
a small town in eastern Adams County—drew about 80 persons.  The
strongest opinions of those attending the Bennett meeting were the
following (Reference 8):

     (1) The sludge application site should not be located in Adams
County.

     (2) More experimentation should be conducted before committing
a large land area to sludge application.

     (3) The consensus was that sludge application was not approp-
riate for dryland wheat farming.

     (4) Subsurface injection of sludge would be preferred rather
than spraying or other means of spreading on top of the ground.

     A petition was submitted at this meeting opposing location of
the sludge application in Adams County.

     Following the Bennett meeting and a follow-up meeting at the
Adams County Fairgrounds, and on the advice of the Citizens' Advi-
sory Committee, the project was modified to overcome several of the
                             200

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most serious objections.  The revised project was presented in the
March 1974 report "Agricultural Reuse Program" (Reference 5).   Citi-
zens and Commissioners of Adams County, however, still  expressed
opposition to locating the project in Adams County.   At the four pub-
lic meetings in 1974, concerns were again expressed  about possible
condemnation of the land required for the site, potential odor prob-
lems, the feasibility of marketing the sludge, land  devaluation and
the visual aspects of the facilities.  The major outcome of this
public involvement in the project was its influence  on  the site selec-
tion study.  The relatively isolated site finally selected (site B-2
shown in Figure 2) was recommended in large part to  minimize adverse
socio-economic impacts and public opposition.

     In summary, public involvement in the project since 1972  has in-
cluded seven sessions of the citizens' Advisory Committee and  seven
well-attended public meetings (with 75 participants).  Persons at-
tending the public meetings were antagonistic towards having the pro-
posed project located near them in Adams County.  The substantive
issues brought up (odors, public health hazards, water  quality im-
pacts, etc.) are treated elsewhere in this report.  Viewed simply
from the point of view of public opinion indices, the meetings dis-
play a negative view of public opinion toward the project.  However,
these views may be unrepresentative since those believed to have ob-
jections to the project were contacted for the public meetings, and
the meetings were held near the areas of greatest opposition to the
project.

     A meeting held with the Adams County Commissioners as part of
the EIS process (Reference 83) showed that the Commissioners gen-
erally reflected the views of their constituents at  the public meet-
ings.  While they were not opposed to the proposed project in  prin-
ciple, they wished to be more fully assured that potential environ-
mental degradation had been adequately studied, that Metro Denver was
not going to exploit Adams County and that the citizens of Adams
County were not being treated in a high-handed or arbitrary manner.

     Environmentalist groups have been in favor of the  proposed pro-
ject, generally viewing it as a beneficial reuse of  a resource.  It
has also been favorably received by the general public  (since  except
in the case of a very few people, the project is located near  some-
one else).

     Recent contacts with concerned parties have shown  that the gen-
eral attitudes described above are still prevalent at the time of
this study.  The farmers of Adams County have on the whole remained
opposed to the proposed project (References 84, 70).

     Some farmers within a 32-km [20-mile] radius of the drying sites
have expressed a desire to use the dried sludge (References 85, 86).

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Some have told the District that they are interested in using the
sludge but prefer anonymity because the project is so controversial
in this area.   A sampling of some of the favorable responses from
more distant areas is given in Appendix F.

Public Reaction to Drying and Distribution  Site

     The future project implementation in the area of the drying and
distribution site will  probably produce significantly adverse public
reactions.  One part of this expected impact is due to the rural/urban
difference between the sludge-generating and sludge-receiving areas.
If the residents of Adams County feel powerless to prevent, and are
unwilling to accept, the project proposed by the more populous region
to the west, public resentment will be inevitable.

     A second reason to expect adverse reactions is the history of
such reactions to Metro Denver in Adams County.  Opposition appears
to have hardened after years of altercations.  Much of this opposi-
tion is perhaps inevitable with projects of this sort: however, even
many sympathetic to the project have said that in the past Metro Denver
public relations programs have left much to be desired (Reference 39).
It will be difficult though not impossible  to reverse this unfavor-
able image.  The litigation between Metro Denver and Adams County con-
cerning jurisdiction over the proposed project will probably not im-
prove relations, regardless of its eventual outcome.  Future litiga-
tion over condemnation of land and rights-of-way would be probable
(Reference 113).

Public Reaction to Land Application Sites

     While a generally unfavorable reaction toward the project can be
expected, at least initially, adverse reactions against particular
users of the dried sludge are not expected.  A typical example of the
reasons for this can be seen in the case of a representative farm
studied east of Platteville (Reference 85)  in Weld County.  The farmer
involved is interested in using the dried sludge from Metro and does
not expect any problem with his neighbors.   His farm is large—as are
most farms in this general area—and the relative remoteness from the
public makes nuisance conditions unlikely.   This particular farmer
has had experience with similar uses of sludge in Denver on lawns
(about 30 years ago) and therefore sees no  problem with using it now.
He thinks that odors are not a problem and  that some neighboring
farmers are using smellier materials on their own land right now (e.g.,
heat-treated chicken manure from a nearby chicken farm).  Such ma-
nure applications are considered an accepted part of farming opera-
tions.  Finally, he has farmed his land for 30 years and is confident
that other farmers will generally respect his right to conduct his
operation as he judges best.

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H

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     References listed in this Section include
published material, unpublished reports and
articles, personal communications,  (telephone,
visits, letters, etc.), meeting notes and other
sources of data.

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                            SECTION  IX

                            REFERENCES
 1.    U.S.  Environmental  Protection Agency,  "Grant Regulations and
      Procedures  - 30.420-6 Conservation and Efficient Use of Energy",
      Federal  Register, July 1975.

 2.    Colorado  Department of Health, Water Quality Control Commission,
      "Water  Quality  Standards and Stream Classification, Denver,
      Colorado",  June  19, 1974.

 3.    Martin,  W.  J. and J. D. Boyle, "Alternatives for Disposal for
      the  Metropolitan Denver Sewage Disposal District No. 1", pre-
      sented  at Second National Conference on Municipal Sludge Manage-
      ment Disposal,  W18-20, Anaheim, California, August  1975.

 4.    CH2M HILL,  "Sewage  Treatment Plant Expansion - Predesign Study",
      for  Metropolitan Denver Sewage Disposal District No. 1, April
      1972

'5;>    CH2M HILL,  "Agricultural Reuse Program", for Metropolitan Denver
      Sewage  Disposal  District No. 1, March  1973

 6.    CH2M HILL,  "Metro Denver District Sludge Management, Volume  II,
      Alternative Systems", February 1975.

 7.    Brehany,  John J., Project Manager for  Ralph M. Parsons Co.,  Per-
      sonal Communications, 19 September and 27 October 1975.

 8.    CH2M HILL,  "Metro Denver District Sludge Management, Volume  IV
      Environmental Assessment",  February 1975.

 9.    Black and Veatch, "Water Quality Management Program, Volumes  I
      through  IV", for Denver Regional Council of Governments, May  1974.

 10.   U.S.  Soil Conservation Service, "Soil  Survey of Adams County,
      Colorado",  October  1974.

 11.   Officials of NOAA,  U.S. Department of  Commerce, C1imates of  the
      States,  Volume  II,  Water Information Center, Inc.,  Port Washington,
      New  York, 1974.

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12.  U.S.  Department of Commerce,  "Decennial  Census of United States
     Climate - Climatic Summary of the U.S.  - Supplement for 1951  -
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     D.C., 1964.

13.  U.S.  Department of Commerce,  "Climatological  Data for  the U.S.:
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14.  U.S.D.A., Soil  Conservation Service,  "Soil  Survey of Arapahoe
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15.  U.S.  Geological Survey, "Generalized  Surficial  Geologic Map of
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16.  Smith, Rex 0.,  Paul A. Schneider, Jr.,  and  Lester R. Petri,
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17.  Pearl, Richard  Howard, "Geology of Ground Water Resources in
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18.  Schwochow, S. D., R.  R. Shroba,  and P.  C. Wicklein, "Sand,  Gravel
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19.  Adams, W. and Ed Mansfield, "Engineering Geology Case  Histories
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20.  Price, Don and  Ted Arnow, "Summary Appraisals of the Nation's
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21.  McConaghy, J. A. et al., "Hydrogeologic  Data of the Denver  Basin,
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22.  U.S.D.A., Soil  Conservation Service,  Greeley Office, "Official
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 25.  U.S.D.A. Soil Conservation Service, "Natural Vegetation of
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 31.  Beckman, W. C., Guide to the Fishes of Colorado, University of
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( "32j>  Rodeck, H. G., Guide to the Mammals of Colorado, University of
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f'SSp  Beidleman, R. G., Guide to the Winter Birds of Colorado.Univer-
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 38.  Benci, John, Assistant Climatologist, Department of Atmospheric
      Science, Colorado State University, personal communication on
      September 3, 1975.

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 39.   Berve,  Dorm  W.,  Chief of  Environmental Health Services,  Tri-
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 40.   Park Superintendent  II, Denver General Parks Department, per-
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 41.   Brown,  Larry,  Environmental Control Engineer, Climax  Molybdenum
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 42.   Works Project  Administration in the State of Colorado, Colorado:
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 43.   Community  Resource Development Cooperative Extension  Service,
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 45.   Adams County Board of Commissioners, "Comprehensive Plan:  Adams
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 46.   Adams County Planning Commission, "Zoning Regulations:  Adams
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 47.;  Metropolitan Denver  Sewage Disposal District No. 1, "Long  Range
' -•'   Planning Study:  1974",  May 31, 1974.

 48.   Amax Inc., "Comprehensive Plan for Land Reclamation and Stabili-
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 50.   Henley, Jan, Economic Analyst, Metropolitan Denver Sewage  Dis-
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 51.   Thompson, Arthur, Statistician, State of Colorado, Office of
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 52.   Rail, Ellis, Communications Director, Denver Regional Council
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 53.   Johnston, William, Socio-Economic Analyst, Denver Regional
      Council of Governments, personal  communication on October 7, 1975.
                             :06

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54.   Denver Regional  Council  of Governments,  "Appraisal  of  the  DRCOG
     Policy Population Forecast",  August 1975.

55.   CH2M HILL, "Metro Denver District Sludge Management, Vol. Ill
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56.   Denver Regional  Council  of Governments,  "Regional  Simplified
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57.   Colorado Department of Highways,  Planning  and  Research Division
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58.   Kochevar, Robert, Traffic Engineer, Road and  Bridge Department,
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59.   American Association of State Highway  Officials,  "A Policy of
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60.   Colorado Department of Highways,  "Colorful  Colorado",  1974.

61.   Colorado Legislature, "Solid  Waste Disposal  Sites  and  Facilities
     Law", Chapter 36, Article 23, CRS 1963 as  amended  by Senate Bill
     132, July 1,  1971.

62.   Colorado, Colorado Revised Statutes, pertaining to Metropolitan
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63.   Korbitz, William, Manager, Metropolitan  Denver, meeting with
     management and staff personnel, July 18, 1975.

64.   United States Department of Commerce,  Bureau  of the Census, "1970
     Census of Population and Housing, Denver Colorado  SMSA",  March
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65.   United States Department of Commerce,  Bureau  of the Census, "1970
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     Characteristics", February, 1972.

66.   McDonald, F.  M., Deputy Assessor, Adams  County, Colorado,  personal
     communications on September 8, and 11, 1975.

67.   Flanagan, Linda, Research and Analysis Section, Colorado  Depart-
     ment of Employment, personal  communication on  October  24,  1973.

68.   Adams County  Sheriff's Department, Administrative  Officer, Brigh-
     ton, Colorado, personal  communication  on October 14,  1975.

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69.  Mr. Fitch, Fire Chief,  Brighton  Fire  Department,  Unit 500,
     Brighton, Colorado,  personal  communication  on  October 14,  1975.

70.  Schwing, James E., CH2M-Hill, Denver, Colorado, personal
     communication on October 2 and 17, 1975.

71.  VanBeek, Marvin,  U.S.  Disposal  Systems,  Commerce  City, Colorado,
     personal communication  on October 1,  1975.

72.  Rugtles, Dorothy, Engineering Technicican,  and Union Rugtles,
     Engineering Technicican,  Union  Rural  Electricity  Company,
     Brighton, Colorado,  personal  communication  on  October 2, 1975.

73.  Metropolitan Denver  Sewage Disposal District No.  1,  "1976  Budget,
     1975-1980 Program",  August 19,  1975.

74.  U.S. Department of Commerce,  Bureau of the  Census,  "Statistical
     Abstract of the United  States",  1972

75.  Ventura County Planning Department,  "Ventura County  Superregional
     Transportation Study,  1974:  Environmental  Evaluation, part 1",
     1974.

76.  Mitts, David, Production  Operations Manager, Bendini Fertilizer
     Company, personal communication  on October  6,  1975.

77.  Martin, William,  Metropolitan Denver  Sewage Disposal District
     No. 1, personal communication on October 1, 1975.

78.  Colorado Legislature,  "Solid  Waste Disposal Sites and Facilities
     Law", Chapter 36, Article 23, Section 5, CRS 1963 as amended by
     Senate Bill 132,  July  1,  1971.

79.  U.S. Environmental Protection Agency, "Technical  Bulletin-Muni-
     cipal Sludge Management Environmental Facors", preliminary draft,
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80.  Council on Environmental  Quality in association with the Environ-
     mental Protection Agency, "Evaluation of Municipal  Sewage  Treat-
     ment Alternatives",  February  1974.

81.  Chaney, Rufus L,  "Land  Application of Sewage Sludge, Benefits
     and Probe!ems", Proceedings of  the 1973  Lime and  Fertilizer Con-
     ference, 5:15-23, 1973.

82.  Dotson, G. K., "Constraints to  Spreading Dewage Sludge on  Crop-
     land", from "News of Environmental Research in Cincinnati",
     Environmental Protection  Agency, May  31, 1973.

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83.  Covy, James, Jerry Grant, John C.  Campbell,  Adams  County Com-
     missioners; Ralph Anderson,  former Adams County Commissioner;
     and Morris Lubow, Adams County Attorney, meeting on  September
     4, 1975.

84.  Kreag, Glen, Adams County Cooperative Extension Service, per-
     sonal communication on September 29,  1975.

85.  01 in, Ray, Weld County Farmer, personal  communication  on October
     9, 1975.

86.  Sharp, William, Adams County farmer,  personal  communication  on
     July 30, 1975.

87.  Romero, J. C. and E.  R. Hampton, Colorado Division of  Water  Re-
     sources and U.S. Geological  Survey, "Maps showing  the  approxi-
     mate configuration and depth to the top  of the Laramie-Fox Hills
     Aquifer, Denver Basin, Colorado",  1974.

88.  Baxter, John, Agricultural  Research Specialist, Metropolitan
     Denver Sewage Disposal District No. 1, personal communication on
     October 1975.

89.  U.S. Department of Transportation, "Transportation Noise and its
     Control", DOT P5630.1, June  1972.

90.  Sandy's Commercial Turf Farm, Brighton,  Colorado,  personal com-
     munication on October 27, 1975.

91.  Rambat, John, Reynolds Turf  Farms, Brighton, Colorado, personal
     communication on October 27, 1975.

92.  New, Rex, Denver Turf Farm,  Hudson, Colorado,  personal communi-
     cation on October 27, 1975.

93.  Rich, Mel, Richlawn Turf Farm, Parker, Colorado, personal  com-
     munication on October 27, 1975.

94.  Matthews, William, Matthews  Sod Farm, Brighton, Colorado,  per-
     sonal communication on October 27, 1975.

95.  Colorado State Department of Agriculture, "Colorado  Agricultural
     Statistics, 1974 Preliminary, 1973 Final", Bulletin  1-75,  July
     1975.

96.  Pratt, P. F., "Effects of Sewage Sludge  or Effluent  Application
     to Soil on the Movement of Nitrogen,  Phosphorus, Soluble Salts
     and Heavy Metals to Groundwaters", presented at 2nd  National

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      Conference  on  Municipal  Sludge Management  and  Disposal, Anaheim,
      California, August  18-20,  1975.

 97.   Danford,  Jack, President,  Organic  Earthworm Corporation,  per-
      sonal  communication on August 7, 1975.

 98.   Maphis,  S.  W., Principal,  Briscoe-Maphis,  Inc.  Deep-six division,
      personal  communication on  August 7,  1975.

 99.   State  of  California Air  Resources  Board, "Emissions  Forecasting
      Methodologies",  July 1974.

100.   Trammah,  Joseph,  Supervising Engineer,  Sewage  Treatment Plant
      Monitoring, Los  Angeles  Air Pollution Control  District, personal
      communication  on  October 3, 1975.

101.   Gerardi,  Albert,  Colorado  Air Quality Commission,  personal com-
      munication  on  October 3, 1975.

102.   Ulwelling,  William, "Smells in the Urban Environment", unpublished
      research  paper on file in  the U.C. Berkeley School of Environ-
      mental  Design  Library, 1972.

103.   Meyer,  Ron, Deputy  Director of Public Works, Adams County Road
      and Bridge  Department, personal communication  on October  15, 1975.

104.   Spiegel,  John, Engineering and Enforcement Officer,  Air Pollution
      Control  Department, Denver, Colorado, personal  communication on
      October 15, 1975.

105.   Straub,  Richard,  Engineer, Weld County  Engineering Department,
      Greeley,  Colorado,  personal communication  on October 15,  1975.

106.   Searne,  Robert,  Staff Coordinator, Mayor's Task Force for the
      Platte  River Development Committee,  Denver Planning  Department,
      Denver,  Colorado, personal communication on October  15, 1975.

107.   Hornback, Kenneth E., Joel Guttman,  et. al., "Studies in  Environ-
      ment:   Quality of Life,  Volume II",  prepared for Office of Re-
      search  and  Development,  November 1973.

108.   Roll,  John  L., Metropolitan Sanitary District  of Greater  Chicago,
      personal  communication on  September  15, 1975.

109.   Thomas,  Harold J.,  Manager, Mountain Bell  Telephone  Company,
      Aurr^a,  Colorado, personal communication on October  6, 1975.
                              210

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110.   McGauhey,  P.  H.,  and R.  B.  Krone,  "Soil  Mantle  as  a  Wastewater
      Treatment  System",  Sanitary Engineering  Research Laboratory
      Report 67-11, University of California  Press, Berkeley,  1967.

111.   Bernenson, Abram, ed.,  Control  of  Communicable  Disease  in Man,
      American Public Health  Association,  Washington, D.C., llth
      edition, 1970.

112.   Feth, J. H.,  "The Urban Environment", U.S.  Geological Survey,
      Circular 601-1, 1973.

113.   Deline, James,  Mohaghan Farms  Manager,  personal communication
      on October 2, 1975.

114.   Cohen, David  B.,  William J. Martin and  John Baxter,  "Agricul-
      tural Reuse Program: Applied  Research  and  Development  Budget
      (1975-76)", Metropolitan Denver Sewage  Disposal District No. 1,
      January 16, 1975.

115.   U.S.D.A.,  "Diagnosis and Improvement of  Saline  and Alkali Soils,
      Agriculture Handbook No. 60",  February  1954.

116.   Chaney, Rufus L,  "Crop  and  Food Chain Effects of Toxic  Elements
      in Sludges and  Effluents",  In  Proceedings of the Joint  Confer-
      ence on Recycling Municipal Sludges  and  Effluents  on Land, U.S.
      Environmental Protection Agency, U.S.D.A.,  and  the National
      Association of  State Universities  and Land  Grant Colleges,
      Champaign, Illinois, July 9-13, 1973.

117.   Wood, Gene W.,  D. W. Simpson and R.  L.  Dressier, "Effects of
      Spray Irrigation  of  Forests with Chlorinated Sewage  Effluent
      on Deer and Rabbits",  In Recycling Treated  Municipal  Wastewater
      and Sludge through  Forest and  Cropland,  Edited  by  William E.
      Sopper and Louis  T.  Kardos, Pennsylvania State  University Press,
      University Park,  1973.

118.   CH2M HILL, "Metro Denver District  Sludge Management, Volume  I:
      Summary Report",  February 1975.

119.   Mr. Frandsen, Construction  Engineer, District 1, Colorado Divi-
      sion of Highways, Denver, Colorado,  personal communication on
      October 15, 1975.

120.   Kelly, George T., Supervising  Architect/Planner, Metropolitan
      Sanitary District of Greater Chicago, personal  communication
      on September  17,  1975.

121.   Engineering-Science, Inc.."Pipeline  Transport of Digested Sludge
      to Strip Mine Spoil  Site for Spoil Reclamation", August 1975.
                              211

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122. King, L. D. and H. D. Morris, "Land Disposal  of Liquid Sewage
     Sludge:  I.  The Effect on Yield, in vivo Digestibility, and
     Chemical Composition of Coastal  Bermuda Grass", Journal of
     Environmental Quality. Vol. 1, No. 3, 1972.

123.  Sabey, B. R. and W. E. Hart, "Land Application of Sewage Sludge:
      1. Effect on Growth and Chemical Composition of Plants", Jour-
      nal of Environmental Quality, Vol. 4, No.  2, 1975.

124.  Lagerwerff, J. V., "Heavy-Metal  Contamination of Soils, in
      Agriculture and the Quality of Our Environment", American
      Association for the Advancement of Science,  Washington, D. D.,
      1967.

125.  Westfall, D., Agronomist, Great Western Sugar, Longmont, Colorado,
      personal communication on July 30, 1975.

126.  Epstein, Eliot, "Effect of Sewage Sludge on  Some Soil Proper-
      ties", Journal of Environmental  Quality, 4(1): 139-142, 1975.

127.  Scott, M. L., "Trace Elements in Animal Nutrition", In Micro-
      nutrients in Agriculture, Edited by J.J. Mortvedt,  P. M.
      Giordano and W. L. Lindsay, Soil Science Society of America, Inc.
      Madison, Wisconsin, 1972.

128.  Chaney, Rufus L., "Recommendations for Management of Potentially
      Toxic Elements in Agricultural  and Municipal Wastes", In Factors
      Involved in Land Application of Agricultural and Municipal Waste,
      USDA, ARS, Beltsville, Maryland, 1974.

129.  Epstein, E. and G. B. Will son,  "Composting Raw Sludge", in Pro-
      ceedings of the 1976 National Conference on  Municipal Sludge
      Management and Disposal, Anaheim, California, August 1975.

130.  Colorado State Department of Health, Technical  Policy, Guide-
      lines for Sludge Utilization on  Land, Draft  Copy, December,  1976.

131.  1974 Census of Agriculture,  Preliminary Reports  by  County.

132.  Thomas,  Neil A.,  and  Robert  J. Kinsey,  Appraisal of 1920
      Acres  in Adams  County,  Colorado,  T.C.  Hitchings  and Son,  Inc.,
      Denver,  Colorado,  April  18,  1975.

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         ENVIRONMENTAL TEAM RESPONSIBLE FOR EIS PREPARATION
ENGINEERING-SCIENCE,  INC.
  *BAMMAN SHEIKH-OL-ESLAMI,  Ph.D.,
     P.E.
   JOHN A. DAVIS, M.S., M.I.C.E.,
     P.E.
  *SAMUEL B. EARNSHAW. B.A., M.A.,
     B.S.
  *EMY CHAN, A.G.
   TARAS A. BURSZTYNSKY, M.S.,
     P.E.
   THOMAS T. JONES, B.S., M.S.
   PHILIP N. STORRS, M.E., P.E.
   MARY STAUDUHAR, B.A.
SOCIO-ECONOMIC SYSTEMS, INC.
   ALAN D. KOTIN, M.A.
   GEORGE A. JOHNSON, M.B.A., M.S.
  *WILLIAM P. ULWELLING, M.P.H.
  *JANICE HARWELL, M.A.
   SHLOMO BACHRACH, M.A.
EPA REGION VIII STAFF
   MICHAEL A. GANSECKI, B.S.,  M.S.

   STAN SMITH
   GEORGE HARTMAN
Project Manager; Agriculture,
  Soils, Water
Sanitary Engineering, Alterna-
  tives Evaluation
Vegetation, Sludge Reuse
  (Appendix D)
Fauna, Habitats, Graphic Arts,
  Noise
Sanitary Engineering, Alterna-
  tives Evaluation
Final EIS Preparation
Technical Direction
Editing, Typing Supervision
Economics
Economics
Public Health, Socioeconomics
Socioeconomics
Socioeconomics, Coordination
Project Officer; Legal  and Ju-
  risdictional Aspects, Alter-
  natives Evaluation, Summary
Heavy Metals Discussion
System Capacity Evaluation
* Members of the Association of Environmental Professionals
                                213

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111!!
In

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     This Appendix contains the cost, engineering
and environmental evaluations of basic process al-
ternatives for sludge handling and disposal by
EPA's consultant—Engineering-Science, Inc. (ES).
ES concludes that the ''apparent best alternative"
is the system proposed by the Metro District.   The
Appendix also contains a detailed description of
each alternative considered.  Process flow diagrams,
with sludge quantities passing through the process
train, are presented.  Pertinent assumptions in de-
sign and cost calculations are listed.

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                          APFLi\DIK A

           EVALUATION OF ALTERNATIVE SLUDGE HANDLING
                     AND DISPOSAL SYSTEMS
INTRODUCTION

     In the course of its efforts to improve its sewage sludge manage-
ment practices, Metropolitan Denver Sewage Disposal District No. 1 re-
tained an engineering consultant (CH2M Hill) to study alternative
sludge processing and disposal systems and to recommend the best alter-
native.  The results of the consultant's work are contained in a four-
volume report, Volume II of which is entitled "Alternative Systems"
(Reference 6).

     Part of the present study involves an independent evaluation of
the alternatives considered by the consultant, together with others,
prior to assessment of the environmental impacts associated with the
more promising alternatives.  The material contained in this section
summarizes the results of this independent evaluation.  A more de-
tailed description of the alternatives, with flow process diagrams,
and their associated costs is included at the end of this appendix.

SYNTHESIS OF ALTERNATIVES

     In order to compare alternatives in an equitable manner,  the basic
principle that each system must be complete in itself was adhered to.
Thus, the complete system must take as its starting point the raw and
digested sludges at the Central Flant, and as its end a disposal mode
that is truly final; that is, a disposal mode requiring no further ac-
tion to process or transport the sludge.

ALTERNATIVE SYSTEMS

     Sixteen alternative systems were considered, eight of them similar
to those evaluated and reported by CH2M-H111.  For convenience, the
numbering system used in the consultant's report has been retained.
Thus, Alternatives 1A through 8 are those evaluated by CH2M-H111.

     Alternative 1A       Existing system, waste-activated and other
                            sludges trucked to Lowry Bombing Range for
                            landspreading
                               A-l

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Alternative IB
Alternative  2


Alternative  3

Alternative  4


Alternative  5
Alternative  6


Alternative  7


Alternative  8


Alternative  9


Alternative 10



Alternative 11

Alternative 12
Alternative 13
Alternative 14
Alternative 15
Al t e r na t iv e 1 i.
Existing system with anaerobic digestion

Anaerobic digestion, pipeline transport,
  air drying and beneficial reuse  (prod-
  uct:  100 percent air-dried sludge)

Filter presses, incineration, landfill
  of ash
Heat treatment, vacuum filtration, land-
  fill

Heat treatment, air drying, landfill

Heat treatment, vacuum filtration, in-
  cineration, landfill of ash

Anaerobic digestion, filter presses,
  compost (product:  100 percent nutrient-
  enriched composted sludge)

Filter presses, compost (product:  100
  percent nutrient-enriched composted
  sludge)

Anaerobic digestion, centrifugation, com-
  post (product:  100 percent nutrient-
  enriched composted sludge)
Anaerobic digestion, pipeline transport,
  air drying, compost (product:   50 per-
  cent air-dried sludge; 50 percent
  nutrient-enriched composted sludge)

Anaerobic digestion, centrifugation,
  landfill

Anaerobic digestion, pipeline transport,
  air drying, landfill,  compost  (product:
  33 percent air-dried sludge; 33 percent
  nutrient-enriched composted sludge; re-
  mainder to landfill)

Anaerobic digestion, vacuum filtration,
  compost (product:  100 percent nutrient-
  enriched composted sludge)

Vacuum filtration, compost (product:  100
  percent nutrient-enriched composted
  sludge)

Anaerobic digestion, vacuum filtration,
  pipe.lii.ie transport to solid waste re-
  cycling plant

Vacuum filtration, pipeline transport to
  solid waste recycling plant
                          A-2

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     Reviewing the alternatives bricf'jy, alternatives 1A and 1^ ;;it
variations of the existing system, of processing at the Central riant,
with truck-haul to Lowry bombing Range for incorporation into t.ie soil.
Alternative 2 is the syter.i recommended by CH2M HILL, slightly modified.
As evaluated by CH2M-Hill, the final product of this system was a
stored stockpile of air-dried sludge, the presumption being that users
of the sludge would haul the product from the stockpile to the final
reuse sites.  As evaluated here, the truck-haul to the use site is in-
cluded as part of the total system.   Alternatives 3, 4, 5, 6 and 11
are options for processing prior to  landfill.  Alternatives 7, 8, 9,
13 and 14 are options for processing prior to composting and sale.
Alternatives 10 and 12 are variations on Alternative 2, but with a dif-
ferent product mix.

     Alternatives 15 and 16 are options for processing prior to trans-
port to a regional solid waste processing plant.  The feasibility of
these alternatives is currently being studied by Ralph M. Parson, Inc.
for the Denver Regional Council of Governments.  The alternatives con-
sidered here are based on the assumption that the solid waste process-
ing plant would be located 5 km [3 miles] distant from the District's
plant and that digested sludge, at 25 percent solids content, would be
accepted at the processing plant at  no charge to the District (Refer-
ence 7).

COST OF ALTERNATIVE SYSTEMS

     Economic evaluation of alternative sytems which incur future
costs and accrue future benefits, always difficult,  has become increas-
ingly so in a time of severe price inflation and doubt concerning fu-
ture resource costs and availability.  In view of these difficulties,
it is not surprising that differences of opinion exist in the engineer-
ing profession vis-a-vis the costs of certain processing and disposal
activities.

     The approach adopted in reevaluating the alternatives was to ac-
cept previous cost assumptions unless it appeared that an error of judg-
ment had been made which might have  a significant effect on the compar-
ative costs of alternatives.  After  thorough review, the earlier assump-
tions were found to be generally acceptable, an exception being the
omission of salvage values from the  cost calculations.  This omission
has been rectified in order to conform with EPA cost-effectiveness
guidelines.  A more detailed discussion of cost assumptions is included
elsewhere in this appendix.

     The presentation of system costs is prefaced by a brief discussion
of several factors that influence the economic evaluation.
                                  A-3

-------
js.even.ue

     All systems considered that involve beneficial reuse have a poten-
tial for revenue generation.   However,  the market for sewage-sludge-
derived products is somewhat  uncertain;  demand is low and competitive
products are still relatively cheap and  abundant.  The potential reve-
nues from beneficial reuse to be accrued in t'ae Denver area have been
estimated conservatively on the basis of experiences in other locations.
Because of the doubts about the marketability of the products, the cost
of each alternative assuming  no revenue  is presented in the cost tabu-
lation together with a cost adjusted for revenue,

Inflation

     Cost-effectiveness analysis guidelines published by the U.S. Envi-
ronmental Protection Agency dictate that the effect of inflation should
be neglected in cost comparisons of alternatives.  The basis for this
is the belief that, although  fur.ure costs will escalate, the ability
of the users to pay these costs will also escalate at the same rate.
In addition, the discount rate used in the present-worth calculations
is intended to take account of the declining value of money, the cost of
borrowed funds and the opportunity cost  of money.  Because the alterna-
tive sludge management systems range from those with a high initial capi-
tal cost and low operating expenses to those with low initial capital
costs and high operating expenses, the role of inflation in the cost com-
parison is crucial.  For this reason, comparative costs are presented
first without an inflationary factor and a second time with an inflation-
ary factor of 8 percent.

Sunk Costs

     A further difficulty was encountered in establishing a basis for
equitably comparing the alternatives. Recently, the District began
implementation of a plan to construct new anaerobic digestors.  How-
ever, some of the alternatives being considered do not include anaero-
ic digestion as a necessary step in the  total system.  The question
arises whether the cost of the digestors should be regarded as a sunk
cost, to be ignored in the evaluation, or (since the funds are com-
itted and construction is about to begin) be included in all alterna-
ives, irrespective of the need for this  system component.  Adopting
either of these approaches penalizes alterantives that do not include
anaerobic digestion.  Because of this problem, the cost comparison was
made in two ways:  first, and most logically, the total costs of each
system were compared, including a cost for digestion only where tech-
nically necessary; second, recognizing the realities of the situation,
a comparison was made treating the digestion cost as a sunk cost.
                                  A-4

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Comparative Cost of Alternatives

     Table 1 shows the present-worth cost of ten years of operation of
each of the alternative systems.  Similar information is presented in
Table 2, but in this case the capital cost of the new anaerobic diges-
tion system is treated as a sunk cost.  A notable feature of the cost
comparisons is the apparent economic attractiveness of alternatives 15
and 16, those that involve delivery of sludge to a regional solid waste
processing facility.  It should be remembered that at this stage these
alternatives are poorly defined; the corresponding cost estimates are
inevitably lacking in precision.  Of course, the viability of these
alternatives is predicated upon the existence of a facility of this
type in the future.  Because of the uncertainty, these alternatives are
not strictly comparable with the other alternatives considered and are
neglected in the following discussion.  However, alternatives 15 and
16 are worthy of serious evaluation; further remarks on this subject
are contained in the discussion that concludes this section.

     A review of Table A-l indicates that if inflation and revenue-
generation potential are ignored then Alternative 2, the recommended
plan, is one of a group of less costly alternatives, although by no
means the least costly.  If selection were to be based on this cri-
terion alone, then Alternative 2 offers no notable economic advantages.

     Considering the uninflated cost with revenue taken as a credit,
Alternative 2 is again one of a group of less costly alternatives, but
again not the cheapest.  However, it should be noted that those alter-
natives that become significantly less expensive than Alternative 2
rely heavily upon revenue generated from sales; and, of course, doubts
exist regarding the saleability of the product.

     Turning to the cost comparison adjusted for an 8 percent inflation
rate, the advantages offered by Alternative 2 become more apparent.
Even if no revenue is accrued, Alternative 2 is the least expensive.
If in fact sludge users collect dried sludge from the processing as
assumed in the original evaluation, then the total cost of Alternative
2 will be reduced still further.

     Table A-2 shows the cost of alternative systems treating the capital
cost of anaerobic digestion as a sunk cost.  As noted previously, this
reduces the apparent cost of all alternatives that include anaerobic
digestion.  Thus the economic advantages of Alternative 2 are empha-
sized in the cost comparison.

ENVIRONMENTAL IMPACT OF ALTERNATIVE SYSTEMS

     The environmental effects of the alternative systems fall into
two general categories:  the on-site effects—that is, the effects re-
                                   A-5

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Table A-l.  COST OF ALTERNATIVE SYSTEMS



            (million dollars)

Present-worth cost of
Unadjusted
Alternative
1A
IB
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
without revenue
24.1
24.7
24.0
24.2
22.5
33.3
23.6
30.3
34.0
33.8
28.8
26.4
28.9
28.4
27.0
16.8
10.1
with revenue
24.1
24.7
19.3
24.2
22.5
33.3
23.7
19.6
17.0
25.9
20.5
26.4
20.7
20.5
14.5
16.8
10.1
ten years of operation

Adjusted for 8% inflation
without revenue
34.3
30.1
17.7
26.8
25.9
30.2
23.6
35.1
45.1
40.1
24.4
30.8
24.5
33.8
36.4
17.8
13.3
with revenue
34.3
30.1
10.8
26.8
25.9
30.2
23.6
19.3
20.1
28.5
12.3
30.8
12.4
22.2
18.0
17.8
13.3

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Table A-2.   COST OF ALTERNATIVE SYSTEMS TREATING THE CAPITAL COST
               OF ANAEROBIC DIGESTION AS A SUNK COST

                         (million dollars)

Present -worth cost of
Unadjusted
Alternative
1A
IB
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
without
24.
18.
17.
24.
22.
33.
23.
24.
33.
27.
22.
20.
22.
22.
30.
10.
10.
revenue
1
6
8
2
5
3
7
2
9
6
7
2
8
2
0
6
1
with revenue
24
18
13
24
22
33
23
13
17
19
14
20
14
14
14
10
10
.1
.6
.1
.2
.4
.3
.7
.5
.0
.8
.4
.1
.5
.4
.5
.6
.1
ten years of
operation


Adjusted for 8% inflation
without
34
26
14
26
26
30
23
31
45
36
20
27
20
30
36
14
13
revenue
.3
.4
.0
.8
.0
.2
.6
.4
.1
.3
.7
.1
.9
.1
.4
.1
.3
with revenue
34.
26.
7.
26.
26.
30.
23.
15.
20.
24.
8.
.. / .
8.
18.
18.
14.
13.
3
4
1
8
0
2
6
6
1
8
6
1
7
5
0
1
3

-------
suiting directly from and at the site of the project components;  and
off-site effects.  Off-site effects are the effects of the ultimate
sludge disposal method used on the receiving environment.

     Volume IV of the Sludge Management report to the District (Refer-
ence 8 in Section IV of the main text) is an environmental assessment
of the alternative systems.  The analysis emphasizes on-site impacts and
concludes that Alternative 2 is the best option from an environmental
standpoint.  Off-site impacts are the subject of detailed  analysis in
subsequent sections of this report.

     An independent review ot the earlier assessment of on-site impacts
led to general concurrence with the major conclusions presented.   The
more significant points emerging from the review are discussed below.

Process Options

     Many of the alternatives are different only in that they employ
different methods for stabilizing and dewatering sludge.  The direct
environmental implications of these, different processing options  are
relatively insignificant when compared to the environmental consequences
of different transportation, and ultimate disposal methods.   One. excep-
ion to this is the relative resource economy of the processing options.
All alternatives that include vacuum filters, filter presses, incinera-
tors or heat treatment systems require chemicals and fuel  for success-
ful operation.  Alternative 2, which employs anaerobic digestion, re-
quires neither.  In a time of doubt concerning future energy and  mater-
ials costs and availability, the processing element of Alternative 2
offers a significant advantage.

Transportation

     Alternatives 2, 10 and 12 involve pipeline transport  of digested
sludge to a remote location, while the remaining alternatives involve
trucking of dewatered sludge, or ash to an ultimate disposal site.
Pipeline transport is superior because it consumes less energy, does
not involve vehicular air-pollutant emissions and does not involve
long-term impacts upon the community arising from traffic  and noise.

PERFORMANCE OF ALTERNATIVE SYSTEMS

     In this context, the performance of a sludge management system is
used as an index of its effectiveness as a method of residual solids
disposal.  A number of elements contribute to system performance; they
include process reliability, susceptibility to random physical and cul-
tural disruption (due to earthquakes, labor disputes, etc.), suscepti-
bility to resource shortages, and permanence.

-------
P_roc:ess Reliability

     Some of the process components of the alternatives are inherently
more reliable than others in making the required changes in sludge
quality.  Anaerobic digestion and air drying, the processes employed
in Alternative 2, are well understood and widely applied.  Properly de-
signed and operated, they  are proven to be reliable.  Vacuum filtra-
tion (employed in alternatives 1A, IB, 4, 6, 13 and 14) is probably the
most reliable of the mechanical dewatering methods, followed by centrif-
ugation (employed in alternatives 9 and 11) and filter presses (used in
alternatives 3, 7 and 8).  Incineration is a reliable process but is
inherently more hazardous than are the mechanical processes.  Heat
treatment systems are not widely applied and have incurred some problems
in continuous operation.

Susceptibility to Disruption

     All alternatives involve processing activities at the main plant
which would be disrupted during a labor dispute; the more complex pro-
cessing options are more vulnerable, however, due to the need for con-
tinuous operation by skilled personnel.  Pipeline transport would be
le.ss likely to be subject to disruption during a labor dispute than
would trucking because it is not a labor-intensive operation.  With
respect to disruption of ultimate disposal operations, Alternative 2
would be. less vulnerable than would other alternatives by virtue of its
considerable storage capacity.

     Alternatives involving pipeline transport are more vulnerable to
disruption due to physical phenomena such as earthquakes and accidental
damage during other, unrelated human activities.  However, the Dexiver
region is not particularly earthquake-prone, as discussed in the section
on environmental setting.

Susceptibility to Resource Shortages

     An alternative's susceptibility to resource shortages is directly
related to its requirements for energy and chemicals.  All alternatives
that employ truck haul are relatively high energy consumers.  All alter-
natives that involve mechanical dcvaLering are relatively high enemies]
consumers.  Ey virtue of its processing method  (anaerobic digestion),
its transportation method (pipeline transport) and it's u.-e of free solar
energy for dewatering, Alternative 2 emerges clearly as the best option
with respect to this evaluation factor.

Permanence

     Assuming that no unforeseen regulatory  :-r yb;-sical constraints
emerge, :i.U o it ci:u:-; fives considered cau represent nerra?v/ier.t solutions
                                   A-9

-------
to the sewage sludge disposal  problem.   Permanent, in this context,
means having a life in.  excess  of  130 years,

THE APPARENT BEST ALTERNATIVE

     An independent evaluation  of  the alternative sludge management
systems led to a general concurrence with the results of the earlier
evaluation, indicating  that Alternative 2,  anaerobic digestion, pipe-
line transport, air drying and  beneficial reuse,  is "he apparent best
alternative.  This conclusion  is drawn  on the basis or the following:
     1.  J.t Is economically attractive,  particularly when inflation
         is taken into  account.

     2.  Its economic appeal does  not depend  heavily upon revenue
         trom sales that may not,  in fact,  occur.

     3.  Tr. is flexible:  the  product mix can be  adapted to the
         needs of the ultimate  user;  even, under the worst circum-
         stances, air-dried sludge in excess  of need could be
         landfilled without seriously increasing  costs.

     4.  It is conservative of  energy arid materials.
     5.  Its on-site environmental impacts  are generally less
         serious than those resulting from the other alternatives.

     Disadvantages of Alternative  2  arc some  doubt regarding long-terra
off-site effects (discussed in  detail in a  later  section) and high ini-
cial cost.  A cost-benefit analysis  of  Alternative 2 is included as
Appendix j.

     l'*><:>.:--Lf£ or the present funding  arrangements  for water pollution
confr:>I !';u ili.u i es, projects with  a  high capital  cost and low operating
cost c\'-. i:r;ic;_ a larger proportion o£  Federal and State funds thai; do
pro'iecls \;ii n low capital cost  ana high operating  cost.   Thus it is in
the interCot of local agencies  responsible- for sewerage service i.o
select cap Ltal-iu'c '..•:i.-, ive projects  in order  to maximize, financing by
i.v.;t rf.'.cle agencies aiid minimize  local  user charges.   On the other ha;vi,
if -,\.'.y b.:.  in the interesL of the outside funding  ,igc>;ic i es to adopt an
Ouiposite -"pproaca in order to maximize  the  local  share-' ar.J distribute
•jlip available grant furds to z  larger: number  of individual prcvjerts.

     •r-is'! -'ally j high initial capital cost can be  regarded as a disad-
vaatM;- r' only if its inve.~ tneut  does  not bring a return in terms of
significantly reduced notal costs.   In.  the  ca^e of this project, and
rjcr.cMJi ii;g  tliat inflation shn-iid be accounted  for  in the cost ralcula-
ticii.v,  it appears t.uat  1'ie initial capital  investment dees in fact
-:'".:u.Lt  Lr.  significantly reJuced costs.

     The cost estimates for alternatives 15 and 16 (processing and
                                  A-10

-------
transport to a regional solid waste processing plant), admittedly soine-
what lacking in precision at this stage, do indicate tnat economically
these options and Alternative 2 are equally attractive.  This is par-
ticularly true if sludge can be delivered to the plant undigested in
order to retain a higher heat value.  Although Alternative 2 is pres-
ently the apparent best alternative, it is recommended that a detailed
environmental analysis of alternatives 15 and 16 be undertaken if there
is a decision to implement a regional solid waste processing facility.

DETAILED DESCRIPTION OF ALTERNATIVES Ai'ID
PROCESS FLOW DESIGNS

Alternative 1A

     Alternative 1A will involve the continuation of existing modes of
sewage sludge disposal.  The Denver Northside Plant will, in 1985, de-
liver 20 metric tons [approximately 20 short tons]  of dry sewage sludge
to the Central Plant to be put into storag,e tanks.   From the storage or
holding facilities, sludge would be withdrawn and receive polymer con-
ditioning, here estimated at 4 kg/metric ton [10 pounds per short ton]
of sludge solids.  The conditioned sludge would be dewatered on coil
vacuum filters and trucked to the Lowry Bombing range, where smaller
appropriate vehicles would apply the sludge to the land.

     It is envisioned that the present vacuum filter capacity would
need expansion to accommodate future flows, and chemical conditioning
facilities would be added with the new coil vacuum filters.  Expanded
dewatered sludge hauling needs would necessitate the use of additional
trucks.  Existing coil filters would need repairs and renovation, as
will the filtration building.

     It is believed that the existing waste-activated sludge thickener
can be used to thicken future design flows.

Alternative IB

     This alternative, similar to Alternative 1A, represents continua-
tion of the existing system but with anaerobic digestion as an early
processing step.  This results in a marked reduction in dry solids to
be handled in subsequent processing and disposal steps.

Alternative 2

     Alternative 2 embodies the basic concept of beneficial sludge
reuse through soil conditioning.  All waste sludges would be anaerobi-
cally digested and then pumped, unthickened, to a drying and distribu-
tion center.  The drying and distribution center, which is discussed in
detail in Metro Denver District Sludge Management, Volume III, Agricul-
tural Reuse Predesign, would air dry the sludge and stockpile it for
                                 A-ll

-------

CENTRAL 88 W-A-S
W.A.S (97) THICKENING
5kg
CENTRAL 45 151 CH
PRIMARY (49) (166) CON
W/
(10
NORTH SIDE |8
DIGESTED (20>
CENTRAL_88 W.A.S.
W.A.S. "(07) THICKENING

'"ANAEROBIC 7?fc
(146) DIGESTION (&f)
CENTRAL 45 fc ^
PRIMARY (49) (107)
NORTH SIDE ,R
DIGESTED (20)
UNITS ARE METRIC TONS (

ALTERNATIVE IA
/9 COIL
/metric ton £/ VACUUM
r.i>i^/i / FILTERS LOWRY BOMBING
EMICAL / 152 __ 	 	 RANGE (INCORPORATION
DITIONING ^ 	 (167) " ^ \ 1 RUCKING IN 1 U 1 Ht SOIL)
POLYMER 1 I J 144 51 ^
bAhort ton) ^H — (IS91 .<--__ 	 _J . 1 ( • 1' — ^r

r [ ^ y//y///////7////, Y///////J/////7///.
FILTRATE
TO TREATMENT
ALTERNATIVE IB
/"*) COIL
5kg/metricton V VACUUM Lnu/RY BnMp,Nft
-• 95 CHEMICAL / 95 fl"™<* TRUCKING RANGE (INCORPORATION
1 IIIUKLIMIWj •• CONUIIIONINU / nnciY \ OUIL;
U05) W/POLYMER1^ UUD)| ( J 3^ _^
- (lOlb/short ton) \. J_ J- 9I te, | ^ |— f^V-1 J
ig^ T'~ (l°°) CX.) O S'iVX ^
DECANT FILTRATE
TO TREATMENT TO TREATMENT
ENGLISH SHORT TONS IN PARENTHESES) OF DRY SOLIDS PROCESSED DAILY.
•n
o
c
m
i

-------
CENTRAL	88_
 W.AS    (97)
          45
CENTRAL
PRIMARY  (49)
NORTH  SIDE   !8
  PRIMARY
ALTERNATIVE
2
                                   133
                                  (146)
 DIGESTED   (20)
                                                                                                                      DISTRIBUTION
                                                         DRYING  BEDS
                                                                                                                        95(105)
ALTERNATIVE
3
  CENTRAL
    WA.S.
  CENTRAL  45
  PRIMARY  (49)
  NORTH  SIDE  l8
    PRIMARY   (20)
   DIGESTED

(166)
 CHEMICAL
CONDITIONING
W/LIME AND
FERRIC CHLORIDE
                                       (620 Ib/short ton)
                                                               FILTER PRESS
                                                 INCINERATION
                                                             TRUCKING
LANDFILL
                                FILTRATE
                              TO TREATMENT
                                                                                                                                       m
       UNITS ARE  METRIC TONS  ENGLISH SHORT TONS  IN  PARENTHESES)  OF DRY SOLIDS PROCESSED DAILY
                                                                                                                                       o
                                                                                                                                       o
                                                                                                                                       3

-------

CENTRAL 88 W.A.S
W.A.S. (97) THICKENING
TRE

CENTRAL 45 151
PRIMARY (49) * (166)
NORTH SIDE l8 fc
PRIMARY (20) ~~
DIGESTED
CENTRAL 88 W.A.S. HEAT
W.A.S. (97) THICKENING H TREATMENT
^
CENTRAI 45 5 1
PRIMARY (49) " (I66)
NORTH SIDE l8 fc

ALTERNATIVE 4
HEAT COOL AND
ATMENT DECANT
CLOTH
151 FILTER
(166) TRUCKING LANDFILL
J ^7^7^ 135 _
/\ $X$XX£ 	 	 ^^ ^\
((\] ( 1 )
^ ^ P V \ J 133 nl
H^ (1471 ^ 1 V
— 2 1 yu y ^
(2) '/////////////' '^>>*£$jj§§§5$/y'/'
\ '~~
DECANT 9 FILTRATE
TO TREATMENT
ALTERNATIVE 5
COOL PUMPING DRYING BEDS TRUCKING LANDFILL
r
r 1 f 	 	 1 5I.> . 133-142 5L,
151 |E>' / i-l - » / 	 '' "' '" V
(166) (I66)\_y yj^ '////////////// '"Sfygfjjjggfi"'
r
LEACHATE
TO TREATMENT
PRIMARY (20)
DIGESTED
UNITS ARE METRIC TONS (ENGLISH SHORT TONS IN PARENTHESES) OF DRY SOLIDS PROCESSED DAILY.
FIGURE A-' (cont.)

-------

CENTRAL 88 W.A.S.
W.A.S (97) THICKENING ~^
CENTRAL 45 l51
PRIMARY (49) " (166)
M("*RTH ^IDF" 18
PRIMARY (20)
DIGESTED
CENTRAL 88 WAS
WAS TqyT THICKENING"*1

I51 ANAEROBIC 7
(|46) DIGESTION (e
CENTRAL 45
PRIMARY (49)
NORTH SIDE l8

ALTERNATIVE 6
HEAT COOL AND
TREATMENT DECANT
CLOTH
r VACUUM
151 FILTER INCINERATION TRUCKING LANDFILL
(166)
•rWnXXX; — ^^ "" 	 v f— • '•»
/ V ^i^i^iXrv ^f \ \ 1
/ \ / \ ) \^ 	
M « r I ) '» JT "] « . ^
- (147) 1 (44) QO O *
^ 'f-'''''''/////////,' /^/r^\f^^f^'y'^'/'/'/''
- ^ \0 J
1 l""
DECANT 8 FILTRATE
TO TREATMENT
ALTERNATIVE 7
BULK
^SALE
FILTER PRESS TRUCKING COMPOSTING
9 A
7j 310 kg /metric ton y* r-i
97 ~| 95 CHEMICAL / 1^5 1 l |?4 ' — i >^§V S""Jt\
	 fcTHirKFMIMH 	 B mMniTIDMIMPi / — — -fc- 	 • ^ .f* ^ . 	 • 	 to- / / ' 1
nn7) \i\n^),. JC ,.,,-^b (i.SH) idW) C^O O /JS^S^ 1 1
1 W/LIMt AINU I '/////////////, /////r///// T I//
____,- .-..,-_,..-.- 1 ////////////// /////////, \ \ /
1 FERRIC CHLORIDE — — V-- - V'
^ (620lb/shor. ton) |~ | BAGGING
DECANT FILTRATE NUTRIENT
PRIMARY (20) "~ lu mtMiMtiMi TO TREATMENT
DIGESTED
UNITS ARE METRIC TONS (ENGLISH SHORT TONS IN PARENTHESES) OF DRY SOLIDS PROCESSED DAILY
FIGURE A-l (cont.)

-------
                                                      I ALTERNATIVE  8
 :ENTRAL
 W.A.S.
CENTRAL
88
W.AS
NORTH SIDE
 PRIMARY
 DIGESTED
(97) ""
45
(49)
DE '8
THICKENING


1 — v

151
(166)
310 kg/metric ton <
CHEMICAL /
CONDITIONING^
W/LIME AND
FERRIC CHLORIDE
(620 Ib/short ton)
F
D
197 [
(217) C

                                                           FILTER PRESS
                                                                      TRUCKING
                                                                                  COMPOSTING
                                                                         196
                                                    FILTRATE
                                                  TO TREATMENT
                                                                     3  (216)
                                                                       OQ
                                                                    h
                                                                    TT
 BULK
 SALE
                                                                               y//////////,
                                                                                                                           BAGGING
                                                                                                 NUTRIENT
                                                                                                 ADDITION
ALTERNATIVE
9
 CENTRAL B8
 CENTRAL 45
 PRIMARY (4cn
                                                                5 kg/metric ton
 NORTH SIDE
  PRIMARY  "
  DIGESTED
             18
   (20)
                                           (107)
TWIPI^FMIMC

195.


OJ
1
(105)
CHEMICAL /
W/ POLYMER
^ (10 Ib/short ton)
OJ
                                                                                 CENTRIFUGATION
                                                                               (105)
                                                                                        CENTRATE
                                                                                      TO TREATMENT
                                                       DECANT
                                                    TO TREATMENT
                                                                                                                          BULK
                                                                                                                         'SALE
                                                                         TRUCKING
COMPOSTING
                                                                                                  1
BAGGING
                                                                                                                  NUTRIENT
                                                                                                                  ADDITION
           UNITS ARE METRIC TONS (ENGLISH SHORT  TONS IN  PARENTHESES) OF  DRY  SOLIDS  PROCESSED DAILY.
O
C
m
>
 i
                                                                                                                                     o
                                                                                                                                     o

-------

CENTRAL 88 W.A.S.
"WAS 1^» THICKENING -«*| 133 ANAERQB|C 79
(146) Dlfat5TION (87)
CENTRAL 45 fc
PRIMARY (49)
NORTH SIDE 18 _
PRIMARY (go)
DIGESTED
PFMTRAI PQ WAS 	 ,

WAS (97) THICKENING 133 ANAEROBIC 79
' 	 ' (146) DIGESTION (87)
CENTRAL 45
PRIMARY (49)
NORTH SIDE l8 fc

ALTERNATIVE 10
PUMPING DRYING BEDS STORAGE
„ 	 . 97 ^x 95(105) , #&.
9?W ) (I07) ^ 	 1 	 / ^^^^i ^BULK

*!ywP^ 4 *( ( /
COMPOSTING 1 BAGGING
NUTRIENT
ADDITION
ALTERNATIVE II
/^ CENTRIFUGATION
5 kg/metric ton ^J
• /
97» THICKENING ~* ^fcCOrjDITIONINC^t/ 95 •/ A 5^ CENTRATE
(107) (105) W/POLYMER (|n^)V 7 (F,) TO TREATMENT

(10 Ib/short ton) °
OJ CVJ ^ -
•^ l i
! 1

ULLAN I A
TO TREATMENT OO O *
'//////////////, '///\,sf&88$^///'
PRIMARY (20) 'WSS//////
DIGESTED
TRUCKING LANDFILL
UNITS ARE METRIC TONS ( ENGLISH SHORT TONS IN PARENTHESES) OF DRY SOLIDS PROCESSED DAILY.

-------
I

CO
                                                          ALTERNATIVE 12
                                                                                                   TRUCKING
                                                                                                                        LANDFILL
     CENTRAL  88
       W.A.S.
                                                             PUMPING
                                                                     97
     CENTRAL  45
     PRIMARY (49)
      NORTH SIDE  l8
       PRIMARY
       DIGESTED
                                                                             DRYING BEDS

                                                                               95 (105)
                (20)
                   '//////////////,

                     STORAGE
                                                                                                                           BULK
                                                                                                                           SALE
                                                                                                   COMPOSTING
                                      I
                                                                                                                            BAGGING
                                                                                                                  NUTRIENT
                                                                                                                  ADDITION
                                                          ALTERNATIVE  13
Z
m
m
   1 CENTRAL J*8
   i  W.A.S. ^*
 Z
 CD
 I
 (/)

 ° i
   CENTRAL 45
   PRIMARY (49)
                           133
                               ANAEROBIC
                               DIGESTION
m  NORTH SIDE  IS
Z  ! PRIMARY  (20^
   ; DIGESTED
CLOTH
VACUUM
FILTER
                                                                                                                                BULK
                                                                                                                                SALE
                                           (107)
                                                                                                                               BAGGING
                                                      DECANT
                                                   TO TREATMENT
                                                                               FILTRATE
                                                                             TO TREATMENT
                                        NUTRIENT
                                        ADDITION
0
0
            UNITS ARE  METRIC TONS (ENGLISH SHORT TONS  IN PARENTHESES) OF DRY SOLIDS PROCESSED DAILY.

-------
ALTERNATIVE
14
CENTRAL
 W.A.S
CENTRAL 4b
PRIMARY (49)
NORTH SIDE
  PRIMARY
 DIGESTED
             18
                                        5 kg/metric ton

                                        CHEMICAL     /
                                       CONDITIONING^/
                                        W/POLYMER

                                        (10 Ib/short ton)
                                                              CLOTH
                                                             VACUUM
                                                              FILTER
                                                                                TRUCKING
                      COMPOSTING
                                                                                                                            ,BULK
                                                                                                                             SALE
                                                                                                                             BAGGING
                                                             FILTRATE
                                                           TO TREATMENT
                                                                                                                     NUTRIENT
                                                                                                                     ADDITION
ALTERNATIVE
15
 CENTRAL
  W.A.S.
 CENTRAL  45
 PRIMARY (49)
                                                                PUMP TO
                                                            PYROLYSIS SITE

                          (146)
                                       (87)
 NORTH SIDE_J_8_
  PRIMARY   (20)
  DIGESTED
                                           (107)
                      CLOTH
                     VACUUM
                      FILTER
SOLID
WASTE
 CHEMICAL
CONDITIONING
W/POLYMER^

(10 Ib/short ton)
                                                                                                                              PYROLYSIS
                                                       DECANT
                                                   TO TREATMENT
                   FILTRATE RETURN
                    TO TREATMENT
      UNITS  ARE METRIC  TONS (ENGLISH  SHORT TONS  IN  PARENTHESES)  OF DRY  SOLIDS  PROCESSED DAILY.
                                                                                                                                           CD

                                                                                                                                           3D
                                                                                                                                           m
                                                                                                                                           >
                                                                                                                                            I
                                                                                                                                           o
                                                                                                                                           o

-------
CENTRAL  88
 W.A.S.   (97)
CENTRAL 45
PRIMARY  (49)
ALTERNATIVE
16
NORTH SIDE
  PRIMARY
 DIGESTED
             18
                                          PUMP TO
                                       PYROLYSIS  SITE
                                                   151
                                                5 kg/metric ton
                       151
                                  (166)
                                                  (166)
 CHEMICAL
CONDITIONING
 W/POLYMER
                                                                                153
                                                                    (167)
                                                           (10 Ib/short ton)
(20)
                            CLOTH
                           VACUUM
                            FILTER
SOLID
WASTE
                                                                                                        PYROLYSIS
                                                                                                 144
                                                                                                (159)
                                                                                            CD
                                                                        FILTRATE RETURN
                                                                          TO TREATMENT
                                                                                                                                            m
      UNITS  ARE  METRIC TONS (ENGLISH SHORT  TONS  IN PARENTHESES) OF  DRY SOLIDS PROCESSED  DAILY.
                                                                                                                                O
                                                                                                                                o

-------
distribution.  The center would include demonstration facilities showing
the benefits of applying sludges to farmlands and would also have some
subsurface disposal capacity to be used as an interim measure until a
market for dried sludge develops.  The subsurface storage would be ac-
complished by injecting liquid sludge several feet into the eoil.

     New anaerobic digesters, some of which are under construction,
would be needed for the Central Plant sludge  as would a new pumping
and pipeline system.  The drying and distribution center location, ap-
proximately 40 km [25 miles] east of Denver, has not been finalized and
is one of three under consideration.

Alternative 3

     In this alternative plan, raw sludge from the Central Plant and
digested sludge from the Denver Northside Plant would be conditioned
with lime and ferric chloride, estimated at 230 kg [500 pounds] of lime
and 54 kg [120 pounds] of ferric chloride per ton of sludge solids.
This conditioning would permit a filter press to dewater the sludge to
35 percent solids content.  This level of dryness is desirable for the
subsequent step of sludge incineration.  It has been assumed that a
multiple-hearth furnace would oxidize the sludge to carbon dioxide and
water, leaving 35 percent of the original solids as ash.  The ash would
be trucked to a sanitary landfill or land application site within 40 km
[25 miles] of Metropolitan Denver.

     New chemical feed systems would be needed along with a completely
new sludge filtration system.  It has been assumed that all alterna-
tives involving filtration would need an expansion of the present
building and improvements to the ventilating systems.  Trucking system
improvements would include three new trucks for hauling incinerator ash
to the disposal site.  A multiple-hearth incinerator was chosen in
preference to a fluidized-bed incinerator because we feel that the lat-
ter has lower reliability due to feed mechanism difficulties and to
high corrosion and erosion from sludge and bed material, particularly
upon the subsequent air pollution control equipment.

Alternative 4

     Concern with the increasing costs of conditioning chemicals re-
quired prior to any sludge dewatering operation led to this alternative
using heat treatment of sludge to break down the gel structure of the
sludge particles and make them more amenable to settling and filtration.
Raw Central and digested Northside sludges would be heated in a Zimpro
Heat Treatment Unit and then cooled and decanted in a gravity separator.
The thickened sludge, of approximately nine percent solids content,
would be vacuum filtered through a cloth fabric on a belt or drum fil-
ter.  The thickened sludge, of approximately 25 percent solids content,
would be trucked to a sanitary landfill or a land disposal site.
                                 A-21

-------
      The decant from  the thickener would contain almost  10 percent  of
 the  original  sludge solids and pollutants.  This material would need
 treatment and represents a sizeable load upon any wastewater  treatment
 facility.  Published  results of the Porteous heat treatment unit  opera-
 tion at Colorado Springs indicate that the decant liquor has  contained
 8,470 mg/1 of COD and 3,800 mg/1 of BOD.

      New facilities needed for implementation of this alternative in-
 clude a heat  treatment unit, thickeners, expanded and renovated cloth
 filters and expanded  trucking facilities.  Additional treatment capaci-
 ty may need to be added for the heat-treated decant liquor.

 Alternative 5

      Alternative 5 is similar to Alternative 4 in the treatment and dis-
 posal of sewage sludge except that the dewatering by vacuum filtration
 would be replaced by dewatering on drying basins with an underdrain re-
 turn system.  Since the drying beds would be removed from the Central
 Plant location and it would be difficult to pump sludges of 9 to 10 per-
 cent  solids content, the heat-treated sludge would not be thickened,
 only  cooled after dewatering.  It is felt that pumping is to be pre-
 ferred over the daily trucking of large quantities of thickened but
 watery sludge.  It would be necessary to treat the leachate from the
 drying beds either at the Central Plant or at a new facility near the
 drying beds.  Dewatered sludge would be trucked to a landfill or land
 disposal site.

      New components needed for this alternative include a heat treat-
 ment  unit, cooling tank, pumping and piping facilities, drying beds
 with  under drains, leachate collection and treatment and a new truck-
 ing  system.

 Alternative 6

      Alternative 6 is similar to alternative 4 in that raw Central
 Plant sludge and digested Denver Northside Plant sludge would be heat
 treated, cooled and decanted, and then filtered through a cloth, belt
 or drum, vacuum filter.   However,  instead of directly trucking the
 sludge to a landfill,  in Alternative 6 an incinerator would be employed
 to reduce the sludge solids by 70 percent and the sludge water by 100
 percent to lessen the trucking and  land disposal costs.

     The following new items of process equipment would be needed to
 implement this alternative:   a heat-treatment unit,  assumed to be manu-
 factured by Zimpro;  cooling and decant tanks,  fabric media vacuum fil-
 ters, along with conversion of existing coil filters to fabric filters;
a multiple-hearth incinerator;  and  trucking facilities.
                                A-22

-------
     rue decani and filtrate from aeat-ureated sludges contain  .subs'_a.i-
liid io;?(ls of pollutants that must be properly treated.  This can 're-
quire expansion of existing wastewater treatment units to accommodate
the new load.

Alternative 7

     Composting of sludge for beneficial reuse is the principal feature
of Alternative 7.  Central Plant sludges would be anaerobically digested,
combined with Denver Northside Plant sludges and thickened in a gravity
thickener.  The thickened sludge, of approximately 5 to 7 percent solids,
would be conditioned with lime and ferric chloride prior to dewatering
in a filter press.  Dewatered sludge would be trucked to a 200-hectare
1500-acre] composting and storage area.  Approximately 70 percent of the
composted sludge would be sold in bulk, and 30 percent would receive nu-
trient enrichment to a fertilizer level of 6-6-6 and be bagged for urban
sale.

     New facilities necessary for implementation of this alternative
include anaerobic digester, gravity thickeners, chemical conditioning
systems, filter presses and trucking.  A new composting facility would
also be developed.

     It is felt that the addition of lime to the sludge on the order of
25 percent by weight makes the sludge generally unacceptable as compost.
For this reason Alternative 13 was developed to allow for a different
conditioning system.

Alternative 8

     Alternative 8 is very similar to Alternative 7 except that no
digesters would be constructed at the Central Plant, and most of the
sludges undergoing composting would be previously unstabilized.   Again,
the addition of lime to the sludge makes it a poor choice for general
use as compost material, and Alternative 14 was developed to overcome
this difficulty.

Alternative 9

     Alternative 9 would also produce composted sludge as a final prod-
uct with a variation in the sludge treatment system.  Anaerobically di-
gested sludges from both plants would be thickened and then chemically
conditioned with polymers on the order of 4 kg [10 pounds] of polymer
per ton of sludge solids.  The conditioned sludges would be centrifuged
to remove water and it is estimated that a sludge cake with 80 percent
moisture could be achieved.  The dewatered sludge would be trucked to
a new 200-hectare [500-acre] composting and storage facility.  From
there, 70 percent of the composted sludge would be sold in bulk, and
30 percent would be nutrient enriched and sold as a bagged fertilizer.
                                 A-23

-------
      New facilities required for  this alternative include anaerobic
 digesters,  gravity thickeners,  chemical conditioning systems,  centri-
 fuges,  trucking and composting.   The use of  polymers for sludge condi-
 tioning would make the sludge perfectly acceptable as compost.

 Alternative 10

      Alternative 10  is almost identical  to Alternative 2  in that  the
 sludge  treatment processes and the final drying and  distribution  center
 would be  the  same.   However,  it is felt  that the complete disposal  sys-
 tem  of  distribution  to farmers of bulk dried, stabilized  sludge may not
 necessarily be  sufficiently  encompassing of beneficial uses.   In  particu-
 lar,  a  substantial market need may exist for composted and enriched
 sludge  for urban homeowners  and landscapers.  Alternative 10 adds to  the
 process train of Alternative  2 the provision for composting, enriching
 and  bagging a portion of the  drying sludge.  At this  time it is diffi-
 cult  to specify the  size of  the market for composted  and  enriched sludge,
 and  this  disposal  system could be reserved as a contingency measure for
 excess  sludge disposal.  An  estimate  of  tonnage demand for costing  pur-
 poses could be made  after a market analysis for composted sludge.   In
 the  interim,  the additional  composting facilities are not reflected in
 any  costs of  alternatives.

 Alternative 11

      Alternative 11  is similar to Alternative 4 because  it would  provide
 a dewatered sludge for land disposal.  Alternative 11 adds anaerobic
 digestion for Central Plant  sludges in order to stabilize them and  make
 them less noxious.   The best  treatment system, and attendant strong de-
 cant  liquor,  of Alternative  4 would be replaced by polymer treatment  of
 the  digested  sludge, followed by centrifuge dewatering to produce a
 sludge  cake containing 20 percent dry solids.  This material would  then
 be trucked to a sanitary landfill or  other land disposal  site.

      New  facilities  needed for this alternative include anaerobic diges-
 ters, gravity thickeners, polymer feed systems, centrifuges and expanded
 trucking  capability.

 Alternative 12

      Alternative 12  is basically identical to Alternatives 2 and  10 in
producing anaerobically digested sludges for drying and distribution
for beneficial reuse.  This alternative includes a contingency plan to
produce some composted and nutrient-enriched sludge for the urban mar-
ket.   Additionally, if due to unforeseen circumstances a market for
dried or composted sludges is not  adequately developed or is delayed  in
expansion, provisions would be made for trucking the dried sludges to a
landfill site.
                                 A-24

-------
     New components of Alternative 12 which would be in addition to
those of Alternative 2 include composting pads, nutrient storage and
addition facilities, a bagging machine and trucks for hauling sludge to
a landfill.  These additional facilities have not been included in the
costs of Alternative 12 because the proportion of the sludge production
duction likely to go to each disposal system has not been determined.

Alternative 13

     Alternative 13 was developed to alleviate the concerns about lime
content of composted sludge in Alternative 7.  In Alternative 13, di-
gested sludges would be thickened and treated with polymers.   The condi-
tioned sludge would be dewatered to approximately 25 to 30 percent dry
solids content on a cloth vacuum drum or belt filter.  Trucks would
transport the dewatered sludges to a 200-hectare [500-acre] composting
facility, from where it is estimated approximately 70 percent would be
sold in bulk as compost.   Approximately 30 percent of the compost would
be enriched with nutrients to a 6-6-6 fertilizer level and sold to urban
users.  The fertilizer value of the compost could be adjusted to the
specifications of large-quantity purchasers.

     New facilities necessary for the implementation of this  Alternative
include anaerobic digesters, polymer mixing systems, trucking and a com-
posting facility.  It was calculated that the existing coil vacuum fil-
ters, if converted to fabric media with a loading rate of 17  kg/m2/hour
[3.5 lb/(ft^)(hr)], could readily handle the expected load of digested
sludge due to the solids  reduction that occurs in an anaerobic digester.

Alternative 14

     Alternative 14 is intended to provide a replacement for  Alternative
8, which employs lime and ferric chloride conditioning of undigested
sludges prior to dewatering in a filter press and composting.  In Alter-
native 14, the sludges would be conditioned with a harmless and accept-
able polymer and then dewatered on cloth vacuum filters.  The use of
filter presses can give drier sludge cakes, but with polymer  condition-
ing could result in poor  performance with rapid filter blending.  The
dewatered sludges would be trucked to a composting and distribution fa-
cility.

Alternative 15

     Alternative 15 involves anaerobic digestion and thickening, followed
by pipeline transport to  a regional soliu waste processing center assumed
to be located 5 km [3 miles] from the District's Central Plant.  At the
processing center site, the sludge will be chemically conditioned and
vacuum filtered to approximately 25 percent solids content.  This prod-
uct material will be accepted by the operators of the solid waste pro-
cessing center at no charge.
                                 A-25

-------
Alternative 16

     This alternative is similar to Alternative 15 except  that anaerobic
digestion is omitted in order to retain higher heat values  in the  final
product material delivered to the solid waste processing center.

Assumptions Used in Costing Alternatives

     1.  Process cost curves and other costing assumptions used by CH2M-
Hill were used in the cost analysis after review and verification.
Changes in basic assumptions were made only where it was determined that
the assumptions were clearly in error or were unacceptable for some
other reason.

     2.  Sources for cost and performance data were as follows.

         a.  "Metro Denver District Sludge Management Report, Volume II,"
by CH2M-Hill, 1975, together with back-up calculations supplied by CH2M-
Hill.

         b.  "An Analysis of the Sewage Sludge Disposal Problem in
Southern California," by Engineering-Science, Inc. and J. B. Gilbert and
Associates for EPA, 1974.

         c.  Composting cost and performance data were based upon esti-
mates prepared by Dr. Gar Forsht of the Economic Research Service, USDA
and supplied by CH2M-Hill.

         d.  Estimates of revenue from sale of composted sludge were
based on information supplied by Mr. Kellogg of Kellogg Sales Company,
Carson, California, the distributor of Los Angeles County's composted
sludge.

         e.  Engineering-Science, Inc. in-house files on sludge process-
ing performance and chemical dose rates.

     3.  All costs are related to an Engineering News-Record construc-
tion cost index of 2128,  applicable to the Denver area in December 1974.

     4.  Alternative facilities are sized for 1985 sludge production
projections.

     5.  Annual operation and maintenance costs derived for 1985 design
flows were assumed to apply uniformly to the period 1975 through 1985.

     6.  Alternatives 1A and IB involve continued use of existing coil
filters and addition of  new and similar filters to handle the increased
quantities of sludge.   Needed capacity of new filters (at a solids load-
ing rate of 17  kg/m2/hr  [3.5 Ib/ft2/hr]) was calculated on the basis of
the demonstrated  capacity of the old filters at L4.6 to 17 kg/m2/hr [3
to 3.5  Ib/f t-^/hr] .   The  earlier estimates were in error on this point;
                                  A-26

-------
i.Nj existing, filter capacity was calcuiatec too low by a factor of five.
Alternative IB woald result in substantially lower tonnage of sludge
solids fed to the filters because of reductions in the digestion process
and would need onl;/ a renovation, of existing filters.

     7.  Vacuum filters were assumed to be belt or druni type.  Perform-
ance and chemical dosage rates were assumed to be similar to those pub-
lished by Los Angeles County Sanitation District.

     8.  Composting costs were recalculated on the basis of information
contained in Dr. Gar Forsht's paper entitled "Estimated Processing Cost
for Composting Sludge."  The earlier estimates were in error in that a
purchase of 400 hectares [1,000 acres] of land for composting was treated
as an annual expenditure rather than a one-time-only initial cost.

     9.  It was assumed that for composting alternatives 30 percent of
the sludge would be nutrient-enriched to a 6-6-6 fertilizer value.

Estimated Costs

     Cost breakdowns for each alternative are shown in Tables A-3 and
A-4.  All costs are expressed in 1974 dollars.  Salvage values were de-
termined by straight-line depreciation on the basis of the estimated
useful life of system components.
                                  A-27

-------
                         Table A-3.   COST SUMMARIES USING 10 PERCENT DISCOUNT - NO INFLATION

                                               (thousands of dollars)
i
ro
oo
Alter-
native
1A
IB
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Over a
E
capital
2,186
9,893
25,759
14,236
12,636
29,060
20,636
15,503
8, .538
15,675
26,616
12,913
26,746
12,705
5,830
10,813
2,763
ten-year period
E salvage
value (P.W.)
193
2,390
7,913
3,045
1,664
7,437
3,720
3,309
1,249
3,358
7,913
2,782
7,913
2,893
846
2,714
485
„
Differ-
ence
1,993
7,503
17,846
11,191
10,972
21,623
16,916
12,194
7,289
12,317
18,703
10,131
18,833
9,812
4,984
8,099
2,278

10 year
0 and M
(P.W.)
22,102
17,229
6,157
13,014
11,484
11,693
7,484
18,175
26,655
21,481
10,108
16,228
10,108
18,557
21,97f
8,744
7,841

With digesters .
Revenue
0
0
4,710
0
0
0
0
10,748
16,947
7,846
8,238
0
8,238
7,846
12,474
0
0

Sub-total
w/o revenue
24,095
24,732
24,003
24,205
22,456
33,316
23,680
30,369
33,944
33,798
28,811
26,359
28,941
23,369
26,963
16,843
10,119

Total with
revenue
24,095
24,732
19,292
24,205
22,456
33,316
23,680
19,621
16,997
25,952
20,573
26,359
20,703
20,523
14,489
16,843
10,119

Without digesters
Sub-total
w/o revenue
24,095
18,568
17,839
24,205
22,456
33,316
23,680
24,205
33,944
27,634
22,692
20,195
22,822
22,205
26,963
10,679
10,119

Total with
revenuea
24,095
18,568
13,129
24,205
22,456
33,316
23,680
13,457
16,997
19,788
14,409
20,195
14,539
14,359
14,489
10,679
10,119


-------
                     Table A-4.  COST SUMMARIES
I
ro
USING 10 PERCENT  DISCOUNT AND 8 PERCENT  INFLATION

(thousands  of  dollars)
Alter-
native
1A
IB
2
3
4
5
6
7
8
9
10
11
12
13
It,
15
16
E
capital
2,186
9,893
25,759
14,236
12,636
29,060
20,636
15,503
8,538
15,675
26,616
12,913
26,746
12,705
5,830
10,813
2,763
£ salvage
value (P.W.)
416
5,160
17,084
6,573
3,592
16,054
8,031
7,144
2,696
7,248
17,084
6,005
17,084
6,245
1,826
5,859
1,046
Differ-
ence
1,770
4,733
8,675
7,663
9,044
13,006
12,605
8,359
5,842
8,427
9,532
6,908
9,662
6,460
4,004
4,954
1,717
10 year
0 and M
(P.W.)
32,562
25,383
9,071
19,173
16.919
17,227
11,026
26,777
39,270
31,647
14,891
23,908
14,891
27,339
32,38:
12,881
11,551
With digesters
Revenue
0
0
6,939
0
0
0
0
15,835
24,967
11,559
12,137
0
12,137
11,559
18,377
0
0
Sub-total
w/o revenue
34,332
30,116
17,746
26,836
25,963
30,233
23,631
35,136
45,112
40,074
24,423
30,816
24,553
^3,799
36,385
17,835
13,268
Total uith
revenue
34,332
30,116
10,807
26,836
25,963
30,233
23,631
19,301
20,145
28,515
12,286
30,816
12,416
22,240
18,008
17,835
13,268
Without digesters
Sub-total
w/o revenue
34,332
26,424
14,054
26,836
25,963
30,233
23,631
31,444
45,112
36,382
20,731
27,124
20,861
30,107
36,385
14,143
13,268
Total with
revenue3
34,332
26,424
7,115
26,836
25,963
30,233
23.631
15,609
20,145
24,823
8,594
27,124
8,724
18,548
18,008
14,143
13,268
        g
         Over a ten-year period.

-------

-------
     This Appendix contains descriptions of soils,
by county, within areas which may receive sludge
under the proposed recycling scheme.

-------
                     Table B-l.  SOIL ASSOCIATIONS IN THE VICINITY OF DENVER
   Soil association
                     Description
Map code*
ADAMS COUNTY

   Weld-Adena-Colby


   Samsil-Shingle



   Ascalon-Vona-Truckton



   Nunn-Satanta



   Alluvial land



   Terry-Renohill-Tassel



   Blakeland-Valent-Terry


   Arvada-Heldt-Nunn


   Platner-Ulm-Renohill
Nearly level to steep, well-drained, loamy soils formed        27
in wind-laid deposits; on uplands

Sloping to steep, excessively drained, clayey and loamy        72
soils formed in materials from soft shale and sandstone;
on uplands

Nearly level to strongly sloping, well-drained and some-       71
what excessively drained, loamy and sandy soils formed
in wind-laid deposits; on uplands

Nearly level, well-drained, loamy soils formed in alluvial     23
materials that are underlain by gravel in some places; on
terraces and fans
Nearly level, poorly drained to well-drained, loamy and        30
sandy soils formed in stream and river deposits; on flood
plains
Gently sloping to steep, well-drained and somewhat ex-          6
cessively drained, loamy soils formed in materials from
soft sandstone and shale; on uplands

Undulating to hilly, somewhat excessively drained,              5
dominantly sandy soils; on uplands

Nearly level, well-drained, loamy and clayey soils              8
formed in alluvium; on terraces and fans

Nearly level to strongly sloping, well-drained, loamy          73
soils formed in old alluvium on interbedded shale and
sandstone; on uplands
           O
           M
           t-
               T)
               W
               O
               I — I
               X

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                       Table  E-l  (continued).  SOIL ASSOCIATIONS IN THE VICINITY OF DENVER
         Soil association
                                                    Description
                                                           Map code*
bd
I
ARAPAHOE COUNTY

   Alluvial Land-Nunn


   Weld-Adena-Colby



   Renohill-Buick-Litle



   Nunn-Bresser-Ascalon



   Truckton-Bresser


   Stapleton-Bresser



   Fondis-Weld



OTHER AREAS

   Fluvaquents-Fluvents



   Valent-Vona
Deep, nearly level, mainly loamy and sandy soils;  on           23
flood plains and terraces
Deep, nearly level to sloping, loamy soils that have a          3
clayey to loamy subsoil; formed in silty,  wind-deposited
material; on high-lying divides between creeks

Sloping to steep, loamy soils that have a  loamy to clayey       4
subsoil; moderately deep and deep over shale or sand-
stone; on uplands

Deep, nearly level and undulating, loamy soils that have a     42
clayey to loamy subsoil; developed in outwash; on uplands
and terraces

Deep, rolling, loamy and sandy soils that  have a loamy         24
subsoil; on uplands

Moderately steep soils that are loamy throughout;              43
moderately deep and deep over arkosic sandstone; on
foothills

Deep, nearly level and gently sloping, loamy soils that        27
have a clayey layer in the subsoil; formed mainly in
silty, wind-deposited material; on foothills
                                     Deep, somewhat poorly drained, nearly level, coarse-           18
                                     textured soils; on flood plains and low terraces; commonly
                                     flooded

                                     Deep, excessively drained to well-drained gently sloping      148
                                     to moderately steep sandy soils;  on uplands

-------
                       Table B-l  (continued).   SOIL  ASSOCIATIONS  IN THE VICINITY OF DENVER
           Soil association
                     Description
Map code*
        OTHER AREAS (continued)

           Ascalon-Olney-Vona


           Nunn-Dacono-Altvan
Deep, well-drained, nearly level loamy soils; on
terraces with high water table
Deep, well-drained, nearly level soils; on terraces and
flood plains
  173
  174
         Map code numbers refer to Figure 7  in  Section  III
        Source:   Denver Region Water Quality Management Program
i
OJ

-------
fill
III

-------
     This Appendix contains tabular listings
of plant species observed during the field re-
connaissance phase of the EIS process,  at the
Lowry Bombing Range and at the sludge applica-
tion portion of the Range.  It also contains
lists of common plants, birds and mammals in
the Denver region.

-------
                             APPENDIX C
                              BIOLOGY
Table C-l.  LIST OF PLANT SPECIES OBSERVED DURING FIELD RECONNAISSANCE,
                            AUGUST 7, 1975





Common name Scientific name £P
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Tree
   Plains cottonwood
Shrub
   Broom snakeweed
   Rabbitbrush
   Willow
Herbs
   Alfalfa
   Aster
   Buffalobur
   Bull thistle
   Cocklebur
   Common burdock
   Common sunflower
   Coneflower
   Dandelion
   Fanweed
   Fetid marigold
   Golden aster
   Goosefoot
   Gumweed
   Mikvetch
   Narrow-leaved
     umbrella-wort
   Plantain
   Prickly lettuce
   Prickly pea?"
   Prickly pop;\>
   Prostrate knotweed
   Prostrate pigweed
   Redroot pigweed
   Rocky Mountain beeplant
   Russian thistle
   Sand verbena
   Scarlet falsemallow
   Sedge
   Skeleton weed
Populus sargentii
Gutierrizia sarothrae           x
Chrysothamnus nauseosus         x
Salix sp.                       x
Medicago sativa                 x
Aster sp.                       x
Solanum rostratum
Cirsium vulgare                 x
Xanthium itali cum               x
Arctium minus                   x
Helianthus annuus               x
Ratibida columnifera            x
Taraxacum officinalis           x
Thlaspi arvense                 x
Dyssodia papposa                x
Chrysopsis sp.                  x
Chenopodium leptophyllum        x
Crindelia squarrosa             x
Astragalus sp.                  x
Oxybaphus linearis

Plantago spinulosa              x
Lactuca scariola                x
Opuntia polyacantha             x
Argemone polyanthemos           x
Polygonum aviculare             x
Amaranthus graecizans           x
Amaranthus retroflexus
Cleome serrulata                x
Salsola kali var. tenuifolia    x
Abronia fragrans                x
Sphaeralcea coccinea            x
Carcx sp.                       x
Lygodesmia juncea
                                  C-l

-------
  Table C-l (continued).   LIST OF SPECIES OBSERVED DURING FIELD RECON-
                       NAISSANCE, AUGUST 7, 1975
Common name
Snow-on- the-mountain
Stinging nettle
Scientific name
Euphorbia marginata
Urtica dioica ssp. gra
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   Summer cypress
   Tansy mustard
   Tumble pigweed
   Umbrella plant
   Vervain
   Yucca
Grass
   Beardless wheatgrass
   Blue grama
   Buffalo grass
   Cheat grass
   Downy brome
   Fescue
   Junegrass
   Little bluestem
   Milo
   Needle-and-thread
   Oat
   Red three-awn
   Saltgrass
   Sand dropseed
   Sorghum sudangrass

   Squirreltail
   Sudan
   Three-awn
   Western wheatgrass
   Wheat
Kochia scoparia
Descurainia pinnata
Amaranthus albus
Eriogonum effusum
Verbena bracteata
yucca glauca
Agropyron inerme
Bouteloua gracilis
Buchloe dactyloides
Bromus japonicus
Bromus tectorum
Festuca sp.
Koeleria gracilis
Andropogon scoparius
Sorghum vulgare
Stipa comata
Avena sativa
Aristida longiseta
Distichlis stricta
Sporobolus cryptandrus
Sorghum bicolor X
  S. sudanense
Sitanion hystrix
Sorghum sudanense
Aristida sp.
Agropyron smithii
Triticum sativa
x
x
x
x
x
x
X
X
X
X
X
X
X
X
X
X
X
•3
 Portion of Site A not amended with sludge,  shown in Figure 12.

 Sludge-amended portion of Site A,  shown in  Figure 12.

"Planted by Metro Denver  Sewage Disposal District No.  1.
                                 C-2

-------
    Table C-2.  COMMONLY OCCURRING RANGE SPECIES IN THE DENVER AREA
            Common name
          Scientific name
Native, climax grass species

   Big bluestem
   Blue grama
   Buffalograss
   Indiangrass
   Junegrass
   Kentucky bluegrass
   Little bluestem
   Mountain muhly
   Needle-and-thread
   Needlegrass
   Prairie dropseed
   Red three-awn
   Sideoats grama
   Sloughgrass
   Squirreltail
   Switchgrass
   Western wheatgrass

Associated woody plants, forbs
   and legumes - noxious weeds

   Canada thistle
   Field bindweed
   Halogeton
   Horsenettle, Caroline
   Horsenettle, white
   Povertyweed, silver-leaf
   Povertyweed, woolly-leaf
   Russian knapweed
   Saint Johnswort
   Sorghum almum
   Sowthistle, perennial
   Spurge, leafy
   Toadflax, Dalmation
   Toadflax, yellow
   Whitetop, common
   Whitetop, hairy
   Whitetop, tall
Associated woody plants, forbs
   and legumes - poisonous to
   livestock

   Arrowgrass
   Brake fern
   Chokecherry
Andropogon gerardi
Bouteloua gracilis
Buchloe dactyloides
Sorghastrum nutans
Koeleria cristata
Poa pratensis
Andropogon scoparius
Muhlenbergia montana
Stipa comata
Stipa spartea
Sporobolus heterolepis
Aristida longiseta
Bouteloua curtipendula
Spartina pectinata
Sitanion hystrix
Panicum virgatum
Agropyron smithii
Cirsium arvense
Convolvulus arvensis
Halogeton glomeratus
Solanum carolinense
Solanum elaeagnifolium
Franseria discolor
Franseria tomentosa
Centaurea repens
Hypericum perforatum
Sorghum almum
Sonchus arvensis
Euphorbia esula
Linaria dalmatica
Linaria vulgaris
Cardaria draba
Cardaria pubescens
Lepidium latifolium
Triglochin spp.
Pteridium aguilinum
Prunus virginiana
                                  C-3

-------
   Table C-2 (continued).
                   COMMONLY OCCURRING RANGE SPECIES  IN THE
                     DENVER AREA
            Common name
                                     Scientific name
   Deathcamas
   Larkspur
   Locoweed
   Water hemlock

Associated woody plants,  forbs
   and legumes - others
   Black-eyed Susan
   Elderberry
   Goldenrod, stiff
   Horseweed
   Prickly pear
   Rose
   Russian thistle
   Sunflower
   Yucca
                           Zygadenus spp.
                           Delphinium spp.
                           Oxytropis spp.
                           Cicuta occidentalis
                           Rudbeckia hirta
                           Sambucus racemosa
                           Solidago altissima
                           Erigeron canadensis
                           Opuntia rafinesquii
                           Rosa acicularis
                           Salsola kali var. tenuifolia
                           Helianthus spp.
                           Yucca glauca
Denver Regional Council of Governments Water Quality Management
Plan.
Source:
                                 C-4

-------
   Table C-3.   NATIVE TREES AND ASSOCIATED SHRUBS IN THE DENVER AREA
            Common name
          Scientific name
Overstory and climax trees

   Alder
   American elma
   Box elder
   Douglas fir
   Hackberry
   Narrow leaf cottonwood
   Pinyon pine
   Plains cottonwood
   Ponderosa pine
   Rocky Mountain juniper
   Russian olive
   Siberian elma
   White fir
   Willow

Associated shrubs

   American plum
   Bitterbrush
   Buffaloberry
   Chokecherry
   Creeping mahonia
   Gambel oak
   Hawthorn
   Indigobush
   Leadplant
   Mountain mahogany
   Ninebark
   Rabbitbrush
   Redosier dogwood
   Sagebrush
   Sandcherry
   Serviceberry
   Skunkbrush
   Smooth sumac
   Snowberry
Alnus tenuifolia
Ulmus americana
Acer negundo
Pseudotsuga menziesii
Celtis occidental is
Populus angustifolia
Pinus edulis
Populus sargentii
Pinus ponderosa
Juniperus scopulorum
Elaegnus angustifolia
Ulmus pumila
Abies concolor
Salix spp.
Prunus americana
Purshia tridentata
Shepherd!a argentea
Prunus virginiana
Mahonia repens
Quercus gambeli
Crataegus spp.
Amorpha fruticosa
Amorpha canescens
Cercocarpus montanus
Physocarpus monogynus
Chrysothamnus spp.
Corpus stolonifera
Artemisia spp.
Prunus besseyi
Amelanchier spp.
Rhus trilobata
Rhus glabra
Symphoricarpos spp.
 Species is not native but has volunteered from established plantings.

Source:  Denver Regional Council of Governments Water Quality Manage-
         ment Plan.
                                  C-5

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             Table  C-4.   COMMON  BIRDS  OF  THE DENVER REGION
             Common name
            Scientific name
 Aquatic birds

    Canada  goose
    Whistling  swan
    Lesser  snow goose
    Mallard
    Gadwall
    American widgeon
    Pintail
    Green-winged teal
    Blue-winged teal
    Cinnamon teal
    Shoveler
    Redhead
    Canvasback
    Ring-necked duck
    Lesser  scaup
    Common  goldeneye
    Barrow's goldeneye
    Bufflehead
    Common  merganser
    Ruddy duck
    Red-breasted merganser
    Hooded  merganser
    Greater scaup
    Wood duck
    Pied-billed grebe
    Eared grebe
    Western grebe
Hawks and  falcons

    Turkey vulture
    Sharp-shinned hawk
   Marsh hawk
    Rough-legged hawk
    Ferruginous hawk
   Red-tailed hawk
    Swainson's hawk
   Golden eagle
   Bald eagle
   Prairie falcon
   Sparrow hawk

Grouse,  quail and pheasant

   Sharp-tailed  grouse
   Bobwhite quail
   Ring-necked pheasant
 Branta canadensis
 Cygnus columbianus
 Chen hyperboea
 Anas platyrhynchos
 Anas stepera
 Marceca americana
 Anas acuta
 Anas carolinensis
 Anas discors
 Anas cyanoptera
 Spatula clypeata
 Ay thya americana
 Aytha valisineria
 Aytha collaris
 Aytha affinis
 Bucephala clangula
 Bucephala islandica
 Bucephala albeola
 Mergus merganser
 Oxyura jamaicensis
 Mergus serrator
 Lophodytes cucullatus
 Aytha marila
 Aix  sponsa
 Podilymbus podiceps
 Podiceps  caspicus
 Aechmophorus occidentalis
Cathartes aura
Accipiter velox velox
Circus hudsonius
Buteo lagopus
Buteo regalis
Buteo borealis
Buteo swainsoni
Aguila chrysaetos canadensis
Haliaeetus leucocephalus
Falco mexicanus
Falco sparverius
Pedioecetes phasianellus
Colinus virgianus
Phasianus colchicus
                                C-6

-------
       Table C-4 (continued).  COMMON BIRDS OF THE DENVER REGION
              Common name
           Scientific name
Shorebirds

   Great blue heron
   Black-crowned night heron
   American bittern
   Sandhill cranes
   Virginia rail
   Sora rail
   American coot
   American avocet
   Killdeer
   Spotted sandpiper
   Willet
   Lesser yellowlegs
   Long-billed dowitcher
   Wilson's phalarope
   Common snipe
   Franklin's gull
   Black tern

Pigeons and cuckoos

   Band-tailed pigeon
   Rock dove
   Yellow-billed cuckoo

Owls and goatsuckers
   Screech owl
   Great-horned owl
   Short-eared owl
   Barn owl
   Burrowing owl
   Poor-will
   Common nighthawk

Terrestrial birds

   Ruby-throated hummingbird
   Belted kingfisher
   Red-shafted flicker
   Common redpoll
   Red-headed woodpecker
   Hairy woodpecker
   Downy woodpecker
   Eastern kingbird
   Western kingbird
   Say's phoebe
Ardea herodias
Nycticorax nycticorax
Botaurus lentiginosus
Grus canadensis tabida
Rallus limicola limicola
Porzana Carolina
Fulica americana americana
Recurvirostra americana
Charadrius vociferus
Actitis macularia
Catoptrophorus semipalmatus
Totanus flavipes
Limnodromus griseus scolopaceus
Steganopus tricolor
Capella delicata
Larus pipixcan
Chlidonias nigra surinamensis
Columba fasciata
Columba livia
Coccyzus americanus
Otus asio
Bubo virginianus
Asio flanmeus flanmeus
Tyto alba pratincola
Spectyto cunicularia
Phalaenoptilus nuttalli
Chordeiles minor
Archilochus coluoris
Megaceryle alcyon
Colaptes cafer
Acanthis linaria linaria
Melanerpes erythrocephalus
Dryobates villosus
Dryobates pubescens
Tyrannus tyrannus
Tyrannus verticalis
Sayornis saya
                                 C-7

-------
  Table C-4  (continued).  COMMON BIRDS OF THE DENVER REGION
          Common name
          Scientific  name
Traill's flycatcher
Horned lark
Barn swallow
Cliff swallow
Bank swallow
Black-billed magpie
Common crow
Black-capped chickadee
Common bushtit
Dipper
Red-breasted nuthatch
House wren
Mockingbird
Catbird
Brown thrasher
Robin
Hermit thrush
Veery
Golden-crowned kinglet
Ruby-crowned kinglet
Water pipit
Bohemian waxwing
Cedar waxwing
Loggerhead shrike
Starling
Warbling vireo
Orange-crowned warbler
Yellow warbler
Ovenbird
Yellowthroat
Yellow-breasted chat
American redstart
House sparrow
Western meadowlark
Yellow-headed blackbird
Red-wing blackbird
Brewer's blackbird
Common grackle
Brown-headed cowbird
Bullock's oriole
Lazuli bunting
House finch
American goldfinch
Dickcissel
Emphidonax traillii
Otocoris alpestris
Hirundo erythrogaster
Petrochelidon albifrons
Riparia riparia riparia
Pica Pica hudsonia
Corvus brachyrhynchos
Penthestes atricapillus
Psaltriparus minimus
Cinclus mexicanus unicolor
Sitta canadensis
Troglodytes aedon
Mimus polyglottos
Dumetella carolinensis
Toxostoma rufum
Turdus migratorius
Hylocichla guttata
Hylocichla fuscencens fuscescens
Regulus satrapa
Corthylio calendula
Anthus spinoletta
Bombycilla garrula pallidiceps
Bombycilla cedrorum
Lanius ludovicianus
Sturnus vulgaris vulgaris
Vireo gilvus
Vermivora celata celata
Dendroica petechia
Seiurus aurocapillus
Geothlypis trichas
Icteria virens
Setophaga ruticilla
Passer domesticus domesticus
Sturnella neglecta
Xanthocephalus xanthocephalus
Agelaius phoeniceus
Euphagus cyanocephalus
Quiscaleus quiscula
Molothrus ater
Icterus bullocki
Passerina amoena
Carpodacus mexicanus frontalis
Spinus tristis
Spiza americana
                             C-i

-------
    Table C-4 (continued).   COMMON BIRDS OF THE DENVER REGION
           Common name
          Scientific name
Rufous-sided towhee
Grasshopper sparrow
Lark bunting
Vesper sparrow
Lark sparrow
Tree sparrow
Chipping sparrow
Field sparrow
Lincoln's sparrow
Song sparrow
McCown's longspur
Chestnut-collared longspur
Townsend's solitaire
Pipilo erythrophthalmus
Ammodramus savannarum australis
Calamospiza melanocorys
Pooecetes gramineus confinis
Chondestes grammacus strigatus
Spizella arborea ochracea
Spizella passerina arizonae
Spizella pusilla arenacea
Melospiza lincolni lincolni
Melospiza melodia
Rhynchophanes mccownii
Calcarius ornatus
Myadestes townsendi
                               C-9

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           Table C-5.  COMMON MAMMALS OF THE DENVER REGION
           Common name
              Scientific name
Big game

   Antelope
   Mule deer
Small game

   Blacktail jackrabbit
   Whitetail jackrabbit
   Fox squirrel
   Desert cottontail
   Eastern cottontail rabbit
Furbearers
   Coyote
   Opossum
   River Otter&
   Bobcat
   Striped skunk
   Shortail weasel
   Longtail weasel
   Black-footed ferret3
   Raccoon
   Spotted skunka
   Gray fox
   Red fox
   Swift fox

Rodents, shrews, and bats
   Spotted ground squirrel
   Thirteen-lined ground
     squirrel
   Whitetail prairie dog
   Blacktail prairie dog
   Ord kangaroo rat
   Big brown bat
Rodents

   Porcupine
   Least chipmunk
   Colorado  chipmunk
   Plains  pocket gopher
   Silver-haired bat
   Red bat
   Hoary bat
   Prairie vole
Antilocapra americana
Odocoileus  hemionus
Lepus  californicus
Lepus  townsendi
Sciurus niger
Sylvilagus  audubonii
Sylvilagus  floridanus
Canis latrans
Didelphis marsupialis
Lutra canadensis
Lynx rufus
Mephitis mephitis
Mustela erminea
Mustela frenata
Mustela nigripes
Procyon lotor
Spilogale putori us
Urocyon cinereoargenteus
Vulpes fulva
Vulpes velox
Citellus spilosoma

Citellus tridecemlineatus
Cynomys gunnisoni
Cynomys ludovicianus
Dipodomys ordi
Eptesicus fuscus
Erethizon dorsatum
Eutamias minimus
Eutamias guadrivittatus
Geomys bursarius
Lasionycteris noctivagans
Lasiurus borealis
Lesiurus borealis
Microtus ochrogaster
                                 C-10

-------
      Table C-5  (continued).  COMMON MAMMALS OF THE DENVER REGION
            Common name
              Scientific  name
   Meadow vole
   California myotis bat
   Long-eared myotis bat
   Brown myotis bat
   Small-footed myotis bat
   Fringed myotis bat
   Long-legged myotis bat
   Eastern woodrat
   Northern grasshopper mouse
   Plains pocket mouse
   Silky pocket mouse
   Hispid pocket mouse
   Deer mouse
   Western big-eared bat
   Western harvest mouse
   Plains harvest mouse
   Masked shrew
   Merriam shrew
   Dusky shrew
   Mexican freetail bat
   Big freetail bat
   Northern pocket gopher
   Meadow jumping mouse
   Western jumping mouse
Microtus pennsylvanicus
Myotis californicus
Myotis evotis
Myotis lucifugus
Myotis subulatus
Myotis thysanodes
Myotis volans
Neotoma floridana
Onychomys leucogaster
Perognathus flavescens
Perognathus flavus
Perognathus hispidus
Peromyscus maniculatus
Plecotus townsendi
Reithrodontomys megalotis
Reithrodontomys montanus
Sorex cinereus
Sorex merriam
Sorex obscurus
Tadarida braziliensis
Tadarida molossa
Thomomys talpoides
Zapus hudsonius
Zapus princeps
a
 Classed rare to near extinct due to constriction of habitat.

Source:   Reference
                                 C-ll

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   Table C-6.  COMMON AMPHIBIANS AND REPTILES OF THE DENVER REGION
            Common name
                                               Scientific name
Salamanders

  Barred tiger

Toads

  Great plains
  Woodhouse's
  Plains spadefoot

Frogs

  Boreal chorous
  Bull
  Leopard

Turtles

  Snapping
  Painted
  Yellow western box
  Western spiny softshell

Lizards
  Lesser earless
  Eastern short-horned
  Northern sagebrush
Skinks

  Six-lined racerunner
Snakes

  Eastern yellow-bellied racer
  Prairie rattlesnake
  Plains hognose
  Central Plains milk
  Smooth green
  Bullsnake
  Plains black-headed
  Wandering garter
  Plains garter
  Red-sided garter
Ambystoma tigrinum mavortium
Bufo cognatus
Bufo woodhousei woodhousei
Scaphiopus bombifrons
Pseudacris triseriata maculata
Rana catesbeiana
Rana pipiens
Chelydra serpentina
Chrysemys pi eta
Terrapene ornata luteola
Trionyx spiniferus hartwegi
Holbrookia maculata
Phrynosoma douglassi brevirostre
Sceloporus graciosus graciosus
Cnemidophorus sexlineatus
Coluber constrictor flaviventris
Crotalus viridis viridis
Diadophis punctatus nasicus
Lampropeltis triangulum gentilis
Opheodrys vernalis
Pituophis melanoleucus sayi
Tantilia nigriceps
Thamnophis elagans vagrans
Thamnophis radix
Thamnophis sirtalis parietalis
Source:   Reference
                                C-12

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Table C-7.  COMMON FISHES IN STREAMS AND LAKES OF THE DENVER REGION
            Common name
              Scientific name
Brown trout
Carp
Tench
Creek chub
Fathead minnow
Red shiner
Carp sucker
White sucker
Channel catfish
Black bullhead
Killifish
White bass
Largemouth bass
Smallmouth bass
White crappie
Black crappie
Green sunfish
Blue gill
Pumpkinseed
Yellow perch
Log perch
Darters
Salmo trutta
Cyprinus carpio
Tinea tinea
Semotilus atromaculatus
Pimephales promelas
Notropis lutrensis
Carpiodes carpio
Catostomus cowmersonnii
Ictalurus lacustris
Ictalurus melaf
Fundulas sp.
Lepibema chrysops
Micropterus salmoides
Micropterus dolomieu
Pomoxis annularis
Pomoxis nigromaculatis
Lepomis cyanellus
Lepomis macrochirus
Lepomis gibbosus
Pesca flaves cans
Percina caprodes
Percidae sp.
Source:  Reference
                                 C-13

-------

-------
     This Appendix presents an overall discussion
of the feasibility of applying municipal sludge
to land, as evaluated by Engineering-Science, Inc.

-------
                             APPENDIX D
                     SLUDGE APPLICATION TO LAND
                         TABLE OF CONTENTS
INTRODUCTION                                                 D-l

PLANT NUTRIENT REQUIREMENTS                                  D-3

SOILS AS SLUDGE ASSIMILATORS                                 D-4

    Soil Suitability for Sludge Application                  D-4
    Allowable Sludge Application Rates                       D-4
    Chemical Reactions in Soil                               D-5
    Physical Effects of Sludge Addition to Soils             D-5

ENVIRONMENTAL CONSIDERATIONS AND CONSTRAINTS                 D-6

    Surface Runoff                                           D-6
    Groundwater                                              D-6
    Aesthetics                                               D-7
    Odor                                                     D-7
    Food Chain                                               D-7
    Nitrogen                                                 D-9
    Heavy Metals                                            D-ll
    Pathogens                                               D-12
    Salts                                                   D-14

AGRICULTURAL CONSIDERATIONS                                 D-15

    Fertilizer Value                                        D-15
    Fertilizer Market                                       D-15
    Crop Selection                                          D-16
    Germination                                             D-18
    Weeds                                                   D-21
    Application Rates                                       D-21
    General Conclusions                                     D-22

CHEMICAL PROPERTIES OF METRO DENVER SLUDGE                  D-24

LAND USE OPTIONS FOR SLUDGE APPLICATION                     D-24

    City Parks                                              D-24
    Sod Farms                                               D-28
    Irrigation and Dryland Farms                            D-28

REFERENCES                                                  D-30

                                 D-l

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                              APPENDIX D


                      SLUDGE APPLICATION TO LAND

INTRODUCTION

    The agricultural reuse of materials generated in the processing of
municipal wastes is a contemporary issue that has as its philosophical
base the belief that sewage wastes should be considered not as refuse
but as useful resources.  Past practices of sewage disposal have placed
a burden on the environment in the form of air and water pollution and
have essentially involved the elimination of a significant amount of
nutrient resources from the ecosystems.  Many communities in America are
involved in programs of recycling municipal sludges and effluents on the
land; many universities and public agencies are conducting long-term
research projects on the effects of waste recycling on the environment.
Preliminary results are appearing in increasing numbers in scientific
and technical journals and other publications.

    The intent of this appendix to the  Metro  Sludge EIS  is  to  provide
general information concerning the land application of sludge, with
specific consideration to the chemical composition of Metro Denver sludge
as it relates to agricultural reuse.  Sources for more detailed or more
situation specific information are given in the reference section.

    The Metropolitan Denver Sewage Disposal District No. 1 proposes the
transfer of anaerobically digested liquid sludge from the central plant
to a drying and distribution site, where the sludge would be air dried
and stockpiled for distribution for agricultural reuse purposes.  The
land application of sludge can be grouped into three general categories
according to application rates; these are presented below and summarized
in Table D-l.

        "The reuse of waste sludges for fertilization as shown in
         Table D-l utilizes low loading rates (less than 45 tons
         per hectare per year [20 tons/acre/year]), depending on
         sludge characteristics, soil,  and the crop grown.   The
         objective is the maximization of crop production by full
         use of the nutrients present.   Almost any soil suitable
         for high rate agricultural production is suitable for this
         type of operation.  The key feature of this system is that
         a balance between the nutrients added and the nutrients
         removed with the crops should be maintained.  Only the
         amount of organic material required to maximize crop
         production is applied.

         The 'high rate fertilizer' system uses higher loading rates
         (up to 170 metric tons per hectare per year [75 tons per
         acre per year]).  The objective is to maximize the amount
                                 D-2

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               Table D-l.   THREE MAIN  CATEGORIES FOR  WASTE ORGANICS  APPLICATION TO  LAND

Method
Fertilization








High rate
fertilizer








Disposal
(landfill)







Loading rates,
Annual
<2 to 45
depending
on waste
organics
character-
istic, soil
and crop
grown.

<11 to >168









11 to
several
hundred






, metric tons/ha*
Maximum
accumulation
224 to 2240 to
prevent excess
accumulation of
heavy metals or
other pollutants
in soil.



900 to 2240 to
prevent toxic
accumulations
of pollutants
in the soil.





Several hun-
dred to 2240
or more






Impact on quality
Objective
Maximize crop
production by
use of ferti-
lizer to sup-
ply part or
all of pri-
mary ana /or
micro nutri-
ents.
Apply organics
to cropped
soil. Main-
tain crop while
maximizing or-
ganics appli-
cations .



To dispose of
organics by in-
corporation in
soil. A crop
may or may not
be grown be-
tween applica-
tions.

Suitable soils
Any soil which
is suitable for
high agricultural
production.





Generally fine
textured soils
with a high capa-
city to adsorb or
precipitate
large quantities
of heavy metals
or other pollu-
tants.

Generally fine
textured soils
with a high capa-
city to adsorb or
precipitate
large quantities
of heavy metals
or other pollu-
tants.
Soil
Improves soil
fertility and
organics improve
soil structure.
No detrimental
effects.



May reduce soil
usefulness for
some crops or uses.
Soil would prob-
ably be improved
at lighter load-
ings. Accumula-
tion of pollutants
in soil must be
monitored.
Soil usefulness
will likely be
greatly reduced.
Accumulation of
pollutants in
soil should be
monitored.


Water
With a well managed
system there would
be no harmful effect
on groundwater or
surface water.




Possibly would result
in excess nitrogen
which could be
leached to ground-
water. Proper man-
agement of surface
runoff would protect
surface waters.


Excess nitrogen could
be leached to ground-
water. Proper man-
agement would mini-
mize potential for
pollution from other
materials.


al metric ton/hectare - 0.446 English tons/acre
Source:  Agricultural Reuse Program (Reference D-l).

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         of sludge applied, with crop production secondary in
         importance.  Solids suitable for this type of operation
         should be fine textured with a high capacity to absorb
         or precipitate large quantities of heavy metals.  Even-
         tually, continued unbalanced applications of waste
         organic materials may reduce the soil's usefulness to
         grow certain crops because of HI. cumulations of heavy
         metals or salts.   The application of the nitrogen con-
         tained in the waste organic materials would not be
         balanced by crop removal or natural denitrification,
         and accumulation of nitrogen in the soil would probably
         occur.  Nitrogen compounds could eventually reach the
         ground water or surface system if proper precautions
         were not taken.

         The third general method of operation involves 'dis-
         posal1 at very high loading rates (up to several hun-
         dred tons of waste sludge applied per hectare per year).
         The objective is to dispose of as much sludge as possible
         by incorporation into the soil with little or no emphasis
         on crop production.  Fine textured soils will precipitate
         large quantities of heavy metals or other pollutants and
         are suitable for this type of operation.  The end result
         of continued operation using the 'disposal' method is the
         potential impairment of the soil due to accumulation of
         salts, heavy metals, and nitrates in the soil.  Leaching
         of nitrates, salts, and heavy metals from the soil into
         the ground water or carrying of these materials into the
         surface water regime is a potential hazard that must be
         considered in design." (Reference D-l)

    The method characterized as "fertilization" is the one proposed by
Metro Denver and is the one that will be focussed upon in this appendix
as well as in the body of the environmental impact statement.
PLANT NUTRIENT REQUIREMENTS

    Sixteen elements are known to be essential for plants to be able to
complete their life cycle.  Ten of these elements are required in rela-
tively large amounts for plant growth.  These macronutrients are: carbon,
oxygen, hydrogen, nitrogen, phosphorus, potassium, sulfur, calcium, mag-
nesium and iron.   The remaining six micronutrients which are essential
in trace amounts are: manganese, zinc, copper, boron, molybdenum and
chlorine.  Certain plants may not require one or more of the sixteen
elements.  Certain others require still other elements, or they must be
able to substitute to a degree some elements for others.  Some of the
elements required by specific plants are sodium, selenium, cobalt and
silicon.  All of these nutrients with the exception of carbon are drawn
by land plants mainly from the soil.  Municipal sludge contains all of
                                  D-4

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the essential plant nutrients in varying amounts.
SOILS AS SLUDGE ASSIMILATORS

    Soil is primarily made up of mineral matter, organic matter, micro-
organisms, solutions and air.  The assimilative potential of a soil depends
upon its ability to filter, buffer, adsorb and absorb sludge constituents.
Soils chemically and biologically transform sludge component and support
plants which utilize the nutrients in them (Reference D-2) .

Soil Suitability for Sludge Application

    Physical properties that affect a soil's ability to assimilate sludge
include: porosity, structure, texture (grain-size distribution) and
mineralogy.  Soil filterability is a property that determines how
efficiently a soil can act as a physical filter of suspended particles
and pathogenic organisms. Permeable soils of intermediate texture with
enough colloidal content to trap particulates are generally the best
filters.  Soils that are least suitable for land application include
those that are: 1) extremely fine-textures; 2) extremely coarse-textured,
such as sands and gravels; 3) very shallow; 4) wet or undrained; 5) frozen;
and 6) solonetz and others that are sodium saturated (Reference D-3) .

    Aspects of  soil  chemistry that are of importance to sludge assimilation
include:   1)  ion exchange capacity,  2) chemical  alteration,  and 3)  soil
pH and calcium  reserve.

    Ion exchange capacity refers  to the total amount of cations and
anions that are sorbable per unit of soil weight (expressed as milli-
equivalents per 100 grams of soil) .  Most soils have moderate to large
cation-exchange capacities but only limited anion exchange capacities.

Allowable Sludge Application Rates

    The cation exchange capacity  is the sum of both the capacities of
organic and inorganic soil components.  The ability of a soil to retain
heavy metals from sludge applications - and to keep them out of the
ground and surface water and unavailable to plant tissues - is largely
a function of its cation exchange capacity (Reference D-3) .  Equation D-l
shows the maximum permissible sludge  loading rate as determined by the
cation exchange capacity of a soil and the heavy metals content of the
sludge, where CEC equals the cation exchange capacity of the unsludged
soil in meq/100 g. and ppm equals mg/kg dry weight of sludge (Reference
D-4) .   The constant-200 adjusts for the addition to the soil of some ex-
change capacity in the sludge (Reference D-5) .

    Total Sludge (dry wt. metric  tons /hectare) =

                     _ 73,000  (CEC)
                                         _
                     ppm Zn + 2(ppm Cu) + 4(ppm Ni) -200
                                  D-5

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    This equation limits the heavy metal additions calculated as zinc
equivalent to 10 percent of the cation exchange capacity.  The zinc
equivalent takes into account the greater plant toxicities of copper and
nickel.  This equation applies only to soil that can be adjusted and
held at a pH of 6.5 or greater for a period of at least two years after
sludge application (Reference D-10).

Chemical Reactions in Soil

    The soil may chemically alter many of the materials which have been
introduced into the profile through the addition of sludge.  These alter-
ations may lessen or increase the environmental impact of sludge applica-
tion.   For example,  through the conversion of organic nitrogen to nitrate,
a potential threat to groundwater quality and public health (Reference D-6)
is introduced.

    Soil pH and calcium reserve are very important properties that de-
termine to what degree a soil can inhibit the solubility of heavy metals
compounds.  Contrasting properties of alkaline (calcareous) and acid
soils are given below (Reference D-7):

    Alkaline (Calcareous) Soils                 Acid Soils


  High in calcium                     Low in calcium
  High in pH and carbonate            Low in pH; no carbonate
  Rich in nutrients                   Poor in nutrients
  Low solubility of heavy metal       High solubility of heavy metal
    ions                                ions
  High activity of nitrogen fixing    Low activity of nitrogen fixing
    and nitrifying bacteria             and nitrifying bacteria
Physical Effects of Sludge Addition to Soils

    Sludge can act as a soil conditioner by the provision of those
organic compounds that eventually become valuable humus in the soil.
Sludge humus performs all the beneficial functions in the soil that any
other kind of humus does: it holds large quantities of water, it improves
soil structure and water absorption capacity  (Reference D-8).  It also
improves root penetration and proliferation in the soil.

    Sludge as a soil conditioner promotes desirable physical properties
in soils such as friability (loose and crumbly rather than hard and
cemented) and improved drainage (Reference D-9).   Sludge residue decreases
the bulk density of the soil (Reference D-10).  In clay soil, sludge
alleviates unfavorable characteristics by providing large pore spaces
among soil aggregates.   In sandy soil, it creates chemical reaction sites
for nutrient exchanges, improves soil aggregation, and makes a good
                                 D-6

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binder to hold the sand from blowing away (Reference D-ll) .  It reduces
the erodibility of all soils through enhancement of more resistant soil
structure.

    Adding sewage sludge initially increases the hydraulic conductivity
of a soil, but the conductivity later decreases.  Organic matter, through
the activity of microorganisms, increases soil aggregation thereby
increasing permeability.   The subsequent decrease in hydraulic conductiv-
ity appears to be due to clogging of soil pores by microbial decompo-
sition products.

    Incorporation of sludge markedly influences the soil atmosphere.  The
low oxygen and high carbon dioxide contents initially result from high
rates of liquid sludge application which can reduce root growth, nutrient
uptake and plant growth.   Other gas products of decomposition, such as
methane and ethylene, can be detrimental to plants under high sludge
application rates (Reference D-12).  However, anaerobically digested
air-dried sludge is stable enough so that decomposition reactions take
place over a rather extended period of time and do not deplete soil
oxygen (Reference D-32).
ENVIRONMENTAL CONSIDERATIONS AND CONSTRAINTS

    The application of sewage sludge to the land can have effects on
many functional components of the ecosystem.  These effects, along with
the major constraints to sludge application, are discussed in this
section.

Surface Runoff

    The area east of the Metropolitan Denver area is subject to heavy
runoff during the spring thaw and during the summer when relatively
short duration, high intensity thunderstorm activity occurs.  Application
of sludge during the spring and summer months could, if not handled
correctly, contaminate surface runoff with elevated levels of nitrate,
salts and suspended organic materials.  Heavy metals contained in the
organic materials are bound physically and chemically in the soil (when
sludge is incorporated into the soil), and as long as the soil stays in
place, little movement of heavy metals is expected.  Special attention
should be given to methods of containing surface runoff in order to pre-
vent contamination of surrounding surface water supplies (Reference D-l).

Groundwater

    If the application of sludge on irrigated farmlands is implemented
by the private farms in the area, certain precautions concerning nitrogen
loading must be observed so that a balance between the amount of nitrogen
applied and the amount removed by the crops can be obtained.  This should
prevent excess nitrates from percolating into the groundwater table.
                                  D-7

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 For  dry  land  farm  applications,  the percolation problem  is much  less
 severe.   Downward  leaching of nitrates into the groundwater table would
 occur  rather  slowly, estimated by Pratt  (Reference D-30)  to average about
 0.15 to  0.75  m/yr  (0.5  to 2.5 ft/yr) through unsaturated  strata  in an
 area with characteristics similar to those of Adams County.  The possi-
 bility of groundwater contamination from excess nitrates  under excess
 sludge application regimes cannot be overemphasized.

 Aesthetics

     Land application of sludge can be managed so  that no  more of an
 aesthetic impact would  result than with  general agricultural field
 practices.  Certain precautions  can reduce any major aesthetic problems.
 Surface  application of  dry or liquid sludge should be followed shortly
 by incorporation into the soil either by discing  or plowing.  The time
 of the year when this is done should be  controlled to prevent dust con-
 ditions  from  occurring.  Farm practices  in the Denver area are fairly
 well defined  and a great deal of experience on the part  of the farmers
 has  been accumulated to prevent  dust problems.  Sludge should be applied
 only during the times of the year when proper dust prevention techniques
 can  be observed (Reference D-l).

 Odor

     Since the Metro Denver sludge would be anaerobically  stabilized,  the
 odor potential would be quite low.  The  odor conditions  are closely re-
 lated  to anaerobic bacterial action on volatile organic matter in both
 the  liquid and solid portions of the sludge.  Either a high degree of
 reduction of  volatile matter, or chemical treatment to inhibit bacterial
 action,  is necessary to prevent nuisance odors.   The degree of volatile
 reduction achieved by anaerobic  digestion is generally not less  than  40
 percent  to achieve a stabilized sludge (Reference D-4).

     The  application of  organic materials to the soil, followed by plowing
 in shortly thereafter,  should be no more objectionable than the  use of
 barnyard manure. With proper attention to application techniques, odors
 should not be detectable outside of the  immediate vicinity of application.
 Those  odors which  are detectable when standing within the application
 area can best be characterized as faint  tarry odors with  a slight trace
 of ammonia.   These odors will dissipate rapidly after application to
 the  land.

 Food Chain

     The  application of  sludge to agricultural land on which crops enter-
 ing  the  human food chain are grown is a matter of some concern,  although
 there  are  no  documented cases of disease resulting from the use  of sludge.
EPA guidelines require  that  the application of sludge to  lands  on which
crops entering the  human food chain will or may be grown  must be examined
closely in terms of hazards to human health and future land productivity.
(Reference D-4)

                                  D-8

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     The principle of food chain concentration  (biological magnifi-
 cation) involves the accumulation and concentration of some sub-
 stances as energy is passed in the form of food along the food chain.
 Thus, a substance which is contained in minute amounts in individual
 plants can become highly concentrated in certain organs in an animal
 which eats a large number of those plants.

     Heavy Metals in Sludge—

     Elements in sludge that are potential hazards to plants or higher
 species in the food chain are:  boron, cadmium, cobalt, chromium cop-
 per, mercury, nickel, lead and zinc.  The elements that are a signifi-
 cant potential hazard to the food chain through plant accumulation
 are cadmium, copper and zinc.  Molybdenum has on rare occasions caused
 animal toxicities when they have pastured on soils naturally rich in
 this element.  Sludge from Metro Denver District is not expected to
 contain toxic levels of molybdenum.  Toxic metals added to soils are
 not a hazard to the food chain until they have entered an edible part
 of a plant, such as the leaf, grain, fruit, or edible root or tuber.
 Copper will cause severe plant injury before the content is high enough
 to be toxic to most animals.  Cadmium and zinc, when added to the soil
 in sludge, can lead to increased food chain cadmium and zinc (Refer-
 ence D-13).

     Cadmium and Zinc—The Food and Drug Administration expects to
 specify the permissible level of cadmium in foods in the marketplace,
 possibly to be established at the c"rrent natural background levels
 (Reference D-13).  Cadmium accumulates in the kidney and liver over
 many years.  Kidney damage and hypertension have been related to in-
 creased cadmium levels in these organs.  "Itai-Itai" disease was caused
 in Japan by increased dietary cadmium; cadmium suppressed calcium
 absorption and led to weak bones in older persons (Reference D-5).

     The cnly apparent way proposed so far to ensure that the cadmium
 level in a Food crop grown on a sludge-treated soil will not be a
 food-chain hazard,  is to reduce the cadmium content of sludges to 0.5
 percent of the zinc content, and as near as possible to 0.1 percent
 of the zinc content.  In this way, zinc excess  (at about 500 ppm Zn
 in leaves) would injure the crop before the zinc or cadmium content
 of the crop became a health hazard.  Zinc appears to compete with
 cadmium at the sites of uptake and injury in animals, and the high
 zinc in crops grown on sludge-treated soil should serve to reduce
 cadmium uptake and accumulation.  Grain, fruit, and edible roots have
 a lower zinc content than the leaves of the same plants.  Cadmium is
 excluded even more strongly, so that the cadmium/zinc ratio of grain,
 fruit,  and edible roots are one-half to one-tenth that of leaves.  The
 choice of these types of crops in preference to leaf crops would mini-
mize cadmium movement into the food chain.  Further research is needed

                                   D-9

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 to  determine  what  levels  of  cadmium and  zinc  are safe for the human
 food  chain (Reference  D-13).

      Copper,  Mercury and  Lead—Copper, mercury,  lead  and some of the
 other elements  in  amounts normally  found in sludges will not cause
 appreciable plant  and  food chain  injury  unless  they are  sorbed onto
 vegetative material by direct  contamination and  then  ingested by
 animals  in large amounts  (Reference D-14).

      Direct Ingestion  of  Sludge by  Pasturing  Domestic Animals—

      Animals, notably  cattle,  are known  to eat  considerable  quantities
 of  soil  as part of their  daily diet.  Sludge-applied  soils,  eaten by
 domestic animals,  would short-circuit the capacity of the soil in
 screening contaminants from  the food chain.   Metro Denver District is
 now engaged in  a research project aimed  at determining accumulations
 of  heavy metal  elements in various  tissues of animals fed controlled
 quantities of sludge.

 Nitrogen

      Nitrogen contained in digested sludge is the most immediate limit-
 ing factor to annual rates of  application on  a given  tract of land.
 This  is  due to  the fact that addition of excess  nitrogen to  the soil
 involves the risk  of polluting the  groundwater with nitrates.   The
 threat of methemoglobinemia, caused by nitrates  and nitrites  in water
 supplies,  are discussed under  public health impacts.   The processes
 which affect  the form  of nitrogen in soils (mineralization, nitrifi-
 cation,  denitrification, immobilization, fixation, adsorption by cation
 exchange,  volatilization, convection, dispersion, and plant uptake)  may
 take  place concurrently.  The  reates of  these processes  are determined
 largely  by soil type and climate.   The nitrogen  content  of the anaer-
 obically digested  liquid sludge at  Metro Denver  will  consist  of  approxi-
 mately 40  percent  ammonia nitrogen  and 60 percent organic nitrogen
 (Reference  D-l).   During drying, most of the  ammonia  and  about half
 of  the organic nitrogen are lost tn volatilization.

      Nitrogen is available to plants mainly as nitrates  and ammonium.
 The ammonium form  is rapidly converted by soil nitrifying  bacteria
 to  the nitrate form.   Organic nitrogen is also mineralized to  the  nit-
 rate  form  abailable to plants.   Excess nitrates  not taken up  by  plants
 can be leached into the groundwater reservoirs.  Nitrogen is  lost
 through denitrification and volatilization of ammonia  and  nitrogen gas
 to  the atmosphere.   Volatilization  can account for at  least a  25 per-
 cent  loss of ammonia nitrogen,  with this percentage increasing  the
 longer the  sludge  is subject to air-drying.  Approximately 30  percent
of the remaining nitrogen in applied sludge becomes available  for  plant
uptake in the first year,  15 percent in  the second year,   10 percent  in

                             D-10

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the third year and 5 percent in the fourth and succeeding years.

     Nitrogen pollution problems can be controlled with correct management,
which involves the formulation of a nitrogen balance for the sludge
application program that prevents excessive nitrate leaching.  The com-
ponents of a nitrogen balance which must be known or estimated include:

   1)   Total nitrogen concentration of the applied sludge as percent
       of solids (N) ;
   2)   The amount of sludge applied in metric tons per hectare (R) :
   3)   The amount of residual available nitrogen in the soil in metric
       tons per hectare (p) ;
   4)   The percent of nitrogen which is mineralized in a given year (c ) ;
   5)   Nitrogen losses through denitrifi cation and volatilization;
   6)   Potential annual uptake of nitrogen by each crop in Kg/ha/yr (U) ;
   7)   Proportion of the nitrogen in the crop removed from the land at
       harvest (c^) ;
   8)   The amount of leaching to be allowed;
   9)   A timing pattern to retain the balance sufficiently close to an
       equilibrium.

The major elements of this balance are expressed in Equation D-2:

                            c  U
                                     - P         (Equation D-2)
                         1,000 c2 N
The variable p is assumed to be zero for the first year, and for success-
ive years is calculated according to the decay of residual available
nitrogen (30 percent in the first year, etc.)

     Nitrogen losses through denitrif ication and volatilization during
air-drying should be estimated and subtracted from the total before N
is computed.  The amount of leaching allowed is determined by the initial
groundwater quality, the size and rate of flow in the groundwater
reservoir, and the size of the sludge application site.  A certain amount
of leaching is required in order to restrict the buildup of soluble salts
in the soil root zone below tolerable limits.  This leaching water will
inevitably carry available nitrate forms to the groundwater.  As a
rule of thumb, sludge application rates should be such that no more than
one half of the nitrogen in the applied sludge can be carried by the
leaching fraction of irrigation water.  Timing of sludge application
depends on the site and the specific situation.  It depends on 1) the
rate of nitrification and, 2) assuming that nitrate ion movement occurs
only with percolate movement, the moisture content properties of the
soil, and 3) the amount of water added to the area.  If sludge nitrogen
is nitrified and moves below the root zone before it is absorbed by
plants, it will percolate on to the groundwater.  If leachate nitrate
concentration is low during most of the year, high levels for a short
period of time are more tolerable.  Monitoring of the leachate must be
included with the management program to compensate for unknown factors
                                D-ll

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(Reference D-15)

Heavy Metals

   Heavy metals are found in digested sludge and usually occur in the
soils as well.  Toxic conditions are not caused merely by a high metal
content in soil or sludge, but rather by the presence of heavy metals
in soluble form.   Heavy metals are adsorbed on the cation exchange sites
of soil clays.  Metals may also be precipitated, chelated, or complexed
with organic matter in a form that is unavailable to plants (Reference
D-16).  The major heavy metals that are potentially hazardous to plants
because of their amounts in sludge, availability in soils, and toxicities
to plants or animals are zinc, copper, nickel and cadmium (Reference
D-15).  Successful treatment of sludge heavy metals by the soil occurs
when they are adsorbed or otherwise held by the soil matrix so that
they cannot be taken up by plants or leached into the groundwater.

   The availability of heavy metals in sludge to crops is largely a
function of soil pH and cation exchange capacity, phosphorus, calcium,
organic matter, and crop variety, species,  organ and age.  The following
summary presents methods of minimizing metal uptake by crops (Reference
D-14):

               Factors  for  Reducing Availability of
          Sludge Trace Elements and Their Uptake by Plants

       Sludge:   Low concentration of trace elements
                 Low Cd to Zn ratio
                 High Phosphorus
                 High organic matter
                 High lime

       Soil:     Neutral to high pH
                 High cation exchange capacity
                 High organic matter
                 Calcareous soils

       Crop:     Trace element tolerant variety and species
                 Fruit and seeds compared with vegetative tissue
                 Younger compared with older vegetative tissue

Plants vary greatly in tolerance to heavy metal toxicity and the relative
tolerance of some plants is shown below (Reference D-14):
                                D-12

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                Relative Tolerance to Metal Toxicity

     Very        Beet crops (chard, sugarbeet, redbeet), kale, mustard,
   Sensitive:    turnip, tomato

   Sensitive:    Beans, cabbage, collards, other vegetable crops

  Moderately     Many farm crops, i.e., corn, small grains, soybeans
   Tolerant:

   Tolerant:     Most grasses, i.e., fescue, lovegrass, Bermudagrass,
                 perennial ryegrass
     Very        Ecotypes of grasses
   Tolerant:

    EPA guidelines for sludge application rates are based on the soil
cation exchange capacity and the concentrations of zinc, copper and
nickel, as shown above in Equation 1.  The limits imposed by this
equation are designed to keep down the level of heavy metals being
absorbed by plants and to protect the fertility of agricultural lands
(Reference D-4).

Pathogens

    The control of pathogens is of importance because of possible direct
exposure to sludge in the handling and application steps and in the
food chain.  Although anaerobic digestion reduces the pathogen content
of sludge, a significant number of pathogens may survive the process
(Reference D-2).   There is no documented evidence of disease caused by
the use of digested sludge on agricultural land, yet some pathogenic
organisms have been reported to survive in soils for long periods of
time.

    Four major groups of pathogenic organisms that are found in munici-
pal wastewater are:  1) Salmonella, Shigella and Mycobacterium bacteria;
2) the protozoa,  Entamoeba hystolytica and Naegleria; 3) Helminth
parasites, Ascaris, Ancyclostoma, Necator, Taenia, and Tricahuris; and
4) viruses.  Of the 150 viruses isolated from sewage, only two, the
causative agents  for poliomyelitis and infectious hepatitis, have been
found to be epidemiologically significant (Reference D-15).  The sur-
vival and movement of viruses through the soil is the subject of much
research (Reference D-16).  Fecal and total coliform bacteria, although
not pathogenic, are used for pathogen determinations because of their
large numbers and the ease of measurement as an indication of the
presence of other enteric bacteria and pathogens (Reference D-15).
                                D-13

-------
    Additional pathogen reduction beyond that attained by stabilization
can be achieved by the following methods:

    1) Pasteurization for 30 minutes at 70°C (158°F);
    2) High pH treatment, typically with lime, at a pH greater than 12
       for 3 hours;
    3) Long-term storage of liquid digested sludge for 60 days at 20°C
       (68°F) or 120 days at 4°C (40°F);
    4) Complete composting at temperatures above 55°C (131°F) for at
       least 30 days;
    5) Use of chlorine or other chemicals  to stabilize and disinfect
       sludge (Reference D-4, D-2).

Current research shows preliminary promise in the use of high energy
electrons for disinfection of sludge passing in a thin stream in a
specifically adapted process (Reference D-31).

    The viability of pathogens is extremely variable and may be from a
few hours to several months.  Among the factors influencing the survival
of pathogens in the soil and on vegetation are:

    1) Type of organism;
    2) Temperature - lower temperature increases viability;
    3) Moisture - longevity is greater in  moist soils than in dry soils;
    4) Type of soil - neutral, high moisture holding soils favor sur-
       vival; and
    5) Organic matter - the type and amount of organic matter present
       may serve as a food or energy source to sustain the microorgan-
       isms (Reference D-2) .

    The potential for groundwater contamination by pathogens is depend-
ent on the ability of pathogens to survive and move through the soil
system.  Fine clay solids are more effective than sandy soils for the
removal of pathogens.  A soil system is generally efficient in removing
pathogens unless rapid movement of sludge  (or later, irrigation water)
occurs through large cracks in the soil profile. Generally, surface
water contamination constitutes a greater  hazard through surface
erosion or surface water runoff during periods of snowmelt or thunder-
storm precipitation (Reference D-2).

    EPA guidelines state that sludge-treated land should not be used
for human food crops to be eaten raw until three years after sludge
application.   Sludge applied to crops which are cooked or processed be
before consumption, to pastures, or to crops used for forage, should
test negative for pathogens by normally applied analytical procedures.
EPA suggests the use of Salmonella and Ascaris as pathogens of choice
for a monitoring program (Reference D-4).
                                 D-14

-------
 Salts

     The  soluble  ions  calcium, magnesium,  sodium,  potassium,  chlorine
 and  carbonate  are  the principle  inorganic ions  added  to  soil in  sludge
 and  mineralized  from  sludge  organic materials in  large concentrations.
 These highly soluble  salts are involved in exchange reactions  in the
 soil and,  depending upon  the composition  of the adsorbed phase,  will
 be temporarily retained and  slowed in  their passage through  the  soil.
 In the Denver  area, normally there is  sufficient  excess  irrigation  or
 rain water available  to flush these ions  through  the  soil  and  into  the
 groundwater table.  In arid  and  semi-arid parts of the country,  water
 is relatively  expensive and  thus  scantily used, and rainfall is  infre-
 quent, resulting in an accumulation of salts in the upper  soil layers.
 This accumulation  can, in time,  prove  deleterious to  crops.   Frequently,
 in the case of high sodium concentrations, soil permeability is  drasti-
 cally decreased  before sodium directly affects  plant  growth.   This
 occurs with too  high  a percentage of sodium ions  on the  exchange sites
 when sodium replaces  calcium and magnesium ions on clay  particles,  dis-
 persing  the soil particles and decreasing soil  permeability.

     The  salt content  of soils is  determined by  the electrical  conductiv-
 ity  (millimhos per cm)  or percent of  the  soil mass  in more severe con-
ditions.   Generally,  when  the conductivity rises to  above 4.0 mmhos/cm,
the salt  content  is considered high  and will affect  yields  of all except
salt-tolerant  plants   (Reference  D-19).

     Crops  commonly grown  in  the  Denver region will suffer  50 percent
 reduction  in yield at a soil salt concentration of 0.25  percent  (with
 50 percent water saturation).  Assuming a 1.2 m [4 ft]-  root zone and
 a background salt  level of 0.05  percent,  200 metric tons [200  tons] of
 dry  solids would add  the  maximum limit of 0.20  percent more  salt to the
 root zone  (Reference  D-l).

     Low-rate application  of  sludge probably will not cause salt accumu-
lation in amounts that would  affect  plant  growth.   For irrigated  land,
the leaching provided by the  irrigation water should prevent a harmful
buildup of salts.  Crop yield would  be reduced  on dry land farms  by
lower salt concentrations  that were  not flushed  by leaching.  At  load-
ing rates of less than 1 m ton per year [1  ton/yr],  over  100 years would
be required to reach potentially harmful  salt concentrations of 0.15 per-
cent  in the soil  (Reference D-l).  Salt accumulation in  soils is  easily
monitored and  can be controlled with proper management.

    Boron  is a potentially hazardous element, commonly viewed with
alarm in irrigation waters.  The most boron-sensitive crops  are  adverse-
ly affected at levels above  0.3 mg/1 in the irrigation water.  No
limits have been established on the tolerable levels of  boron  in
sludges;  however, it is possible to compare boron loadings resulting
from typical irrigation applications with  equivalent applications of
                                D-15

-------
sludge.  About 100 mg/kg of boron concentration in sludge, applied with
recommended limits, can be considered a safe limit.  Historical data on
the boron concentration of sewage sludges in Denver do not exist.  A
recent grab sample analysis of the three Denver sludges produced the fol-
lowing boron concentrations:

       Denver Central Plant Primary Sludge:              60 mg/kg
       Denver Central Plant Waste Activated  Sludge:     62 mg/kg
       Denver North Side Digested Primary Sludge:        31 mg/kg
AGRICULTURAL CONSIDERATIONS

Fertilizer Value

    Anaerobically digested sludge contains all of the essential plant
nutrients and has valuable soil conditioning properties.  The literature
contains many references to increased plant growth resulting from the
application of sludge.  The major fertilizing elements, nitrogen, phos-
phorus and potassium, are present in varying proportions depending upon
the nature of the sludge and other factors such as the length of time
which the sludge has been dried or stored.  Essentially, the solids
portion of the sludge contains most of the nitrogen and phosphorus,
while the liquid portion contains most of the potassium (Reference D-20).
In calcareous soils, such as those found in the Denver area, potassium
is more available to plants than in non-calcareous soils, and thus the
low potassium content of dried sludge would probably not need to be
supplemented by commercial fertilizer.

    Total nitrogen content of air-dried sludge is approximately 6 to 8
percent of the dry weight, with about one-half of that present as
ammonium nitrogen.  It is assumed that approximately 30 percent of the
total nitrogen in applied sludge is made available for plant use in
the first year, 15 percent in the second year, 10 percent in the third
year, and 5 percent in the fourth and succeeding years.  Since nitrogen
is usually considered to be the limiting factor in annual sludge
application rates, sludge as a commercial fertilizer substitute can
supply the needed amount of nitrogen for a particular site and crop.
Other nutrients, such as potassium, may be deficient and require supple-
mental fertilization.  Phosphorus (at 3 percent of the dry solids) is
abundantly supplied in an application which is computed to balance
nitrogen with uptake by plants.  The possibility of applying excess
phosphorus exists in non-calcareous soils.

Fertilizer Market

    In 1972, 36,000 metric tons [40,000 tons] of fertilizer were sold
in the Denver area, a large part of which was used for urban lawns,
gardens and other non-farm purposes (Reference D-l).  The 1970 farm
fertilizer use percentage by crop and the total land area are shown
                                D-16

-------
in Table D-2. The main source of organic fertilizer in Colorado is
livestock manure (88 percent), with about 10 percent of organic fertiliz-
er sales consisting of sewage sludge  (Reference D-l).  Commercial
sales of natural organic fertilizers have dropped off considerably in
Colorado, but the amount of manure that is used for fertilizer far
exceeds the amount which is sold commercially  (Reference D-l).

    The overall commercial fertilizer market adds perspective to the
use of sludge in place of chemical fertilizers.  Increased demands are
being made on the fertilizer industry as a result of various  factors,
including the energy crisis, the need for heavier applications in old
farming areas, and increases in newly added farming areas.  Domestic
supplies are predicted to fall short  of the demand, and the increasing
prices of commercial fertilizer may induce more farmers to view the use
of sludge favorably.

    The ability of sludge to  compete with fertilizers in the  marketplace
is an issue that will certainly emerge in the  near future.  For example,
at a trucking cost of $0.08 per cubic meter-kiloraeter [$0.10/cu yd-mile],
distance of about 100 km  [60 mi] would represent the limit at which the
transportation cost of air-dried sludge (with  5 percent nitrogen on a
dry weight basis and 50 percent solids) equals the current price of
equivalent commercial chemical fertilizer nitrogen ($0.55 per kilogram
[$0.25/lb]) alone.  A general formula for computing the break-even
distance for trucking sludge is given simply by:

                           D ,  F N W S	           (Equation D-3)
where D  is distance  from  the  distribution  center  to the ultimate appli-
cation area, F  is unit commercial  fertilizer cost, N  is fraction of
nitrogen in  the dry  solids, W is the  fraction  of  solids in  theslude, S
is specific weight of sludge and Y is cost of trucking a unit volume of
sludge (including Water)  over a unit distance, all parameters being in com-
patible  (metric or English) units.  Application cost is assumed equal for
sludge and chemical fertilizer.

Crop Selection

    Selection of crops suitable for growth on  sludge-enriched soils
should be done  in consultation with the  local  extension service of  the
U. S. Department of  Agriculture.   Plants vary widely  in their reactions
to sludge application, and these reactions are site-dependent.  Under
most conditions, some crop species take  up and accumulate certain trace
elements, reducing crop yield  and  inhibiting use  in the food chain.  The
major factors governing crop  response on sludge amended soils are soil
type, pH, moisture content, climate,  and crop species.  Soils that
have a neutral  or higher pH,  a high cation exchange capacity and a
high amount of  organic matter reduce  the availability of trace elements
and their uptake by plants.

    Crops that  are grown for  their seeds or fruits rather than vegetative
                                 D-17

-------
                           Table  D-2.  ON-FAKM FERTILIZER USED IN DENVER AREA,  1970
oo

Crop
Corn
Wheat
Sugar beets
Potatoes
Barley
Oats
Dry beans
Sorghum
Alfalfa

Total tons sold
and surface
area
Percentage
N
51
7
23
1
10
2
0
1
5
100
4,003, metric

[4,413, short]
of total element
P
12
1
50
3
19
2
1
1
11
100
1,187, metric

[1,308, short]
applied
K
__
-
28
16
-
-
7
11
38
100
110,

[121,
Hectares
planted
32,684
123,525
8,829
830
33,453
14,418
4,617
3,657
37,058a

metric 259,070

short]
Acres
planted
80,700
305,000
21,800
2,050
82,600
35,600
11,400
9,030
91,500a

639,680


       Harvested.
      Source:   Agricultural Reuse Program (Reference D-l).

-------
tissue and crops whose younger rather than older vegetative tissue is
utilized are more desirable in terms of trace element accumulation.
Some crop species and varieties are more tolerant to trace elements
than others.  Field crops such as corn, small grains, and soybeans are
moderately tolerant.  Most grasses (fescue, lovegrass, Bermudagrass,
orchard grass, perennial ryegrass) are tolerant to high amounts of
metals.  Unusually metal-tolerant ecotypes of the grasses are found on
ore outcrops containing extremely high amounts of metals (Reference
D-5).  The leafy vegetables such as beets, mint, vine, lettuce, swiss
chard, tend to accumulate cadmium and other heavy metals in their
leaves.

    The nutrient uptake potential of different crops is essential
information for determining nitrogen loading rates, as discussed above
under Nitrogen.  Table D-3 presents nitrogen uptake by certain forage,
field and forest crops.  The varying capacities of different crop
species to use water through evapotranspiration relate to the water
regime of the area and possible salt accumulations in the soil. Daily
consumptive water use of three crops grown near Denver is shown in
Figure D-l.

    The selection of vegetative cover can also influence the potential
for contamination of surface waters, since certain plants stabilize the
soils and control erosion and runoff more efficiently than others.  For
example, most grasses would be superior to crops such as soybeans or
corn in the control of runoff (Reference D-20).

Germination

    The inhibition of germination following the application of liquid
digested sludge on soils has been occasionally reported.  The results
of two research efforts in this field are briefly presented below.

    Molina, Braids, Hinesly and Cropper conducted experiments with corn
and soybeans (Reference D-22).   Seeds did not germinate in the liquid
phase of fresh digested sludge.  This inhibition was not due to ammon-
ium nor solely due to a salt effect, an oxygen deficiency, or a low
oxidation-reduction potential of the medium, they concluded.  Seeds
did germinate in digested sludge which had been aged in contact with
the air for one week.

    Sabey and Hart worked with sorghum sudangrass, millet and wheat,
using Metro Denver sewage sludge (Reference D-19).  They found that
increasing amounts of sewage sludge caused increased inhibition of
germination and emergence of sorghum sudangrass and millet when planted
shortly after the sludge was incorporated into the soil.  Wheat was
planted five months later and did not show any inhibitory effects, even
with high rates of application.  A later greenhouse study (the results
of which have not been completely analysed) shows that with low applica-
tion rates (22 to 45 metric tons/hectare [10 to 20 tons/acre]), two
                                 D-19

-------
           Table  D-3.   REPORTED NUTRIENT REMOVAL  BY  CROPS

Crop
Forage
Coastal Bermuda grass
Reed canary grass
Fescue
Alfalfa
Sweet clover
Red clover
Lespedeza hay
Field
Corn
Soy beans
Irish potatoes
Cotton
Milo maize
Wheat
Sweet potatoes
Sugar beets
Barley
Oats
Forest
Young deciduous (up to 5 years)
Young evergreen (up to 5 years)
Medium and mature deciduous
Medium and mature evergreen
Nitrogen
(kg/ha/yr)

538-672
253-402
308
174-246
177
86-141
146

174
105-127
121
74-112
91
56-85
84
82
71
59

112
67
34-56
22-34
uptake
(Ibs/ac/yr)

480-600
226-359
275
155-220a
158a
77-1263
130

155
94-1133
108
66-100
81
50-76
75
73
63
53

ioob
60b
30-50b
20-30b
 Legumes obtain a substantial part of their nitrogen requirements
 from the air.

 Estimated.

Source:   Design Seminar for Land Treatment of Municipal Waste-
         water  Effluents (Reference D-21).

                               D-20

-------
I5
I
UJ
en
a.
o
o
< 2
Q
                                                           0.30
                                     LEGEND
                                             ALFALFA

                                             CORN (GRAIN)

                                             WINTER WHEAT
         I
I
I
I
I
                               0.25




                                   Q
                                   \
                               0.20 z'

                                   i
                                   UJ
                                   (/>

                                   UJ
                               0.15 >
                                   I-
                                   Q.



                                   Z
                                   O
                               0.10 °
                                                       *
                                                            0.05
1
     MAR.   APRIL    MAY   JUNE   JULY   AUG.   SEPT.    OCT.    NOV.
                            MONTH


   SOURCE : AGRICULTURAL REUSE PROGRAM ( REFERENCE D-l )
                         FIGURE  D-l
          DAILY CONSUMPTIVE WATER USE OF CROPS
              GROWN NEAR DENVER,COLORADO

                           D-21

-------
weeks to one month is sufficient to eliminate the inhibitive effects
on wheat.  The time period increases with higher rates of application.
The germination of corn and sorghum sudangrass hybrid was somewhat more
affected by the sewage sludge than the wheat, although this result was
thought to be adversely affected by greenhouse conditions.

    Sabey and Hart conducted a preliminary study to determine whether
inorganic salts or organic compounds caused the germination inhibition
(Reference D-19).   The authors concluded that the salt content of the
sludge did not cause the inhibition, and that the inhibitive factor is
associated with the organic compounds since destroying or volatilizing
the organic compounds eliminates the inhibition.

Weeds

    Weed control may be a major problem when sludge is applied to agri-
cultural land, although the literature contains few references to this
problem.  A cause of weeds associated with sludge applications is the
viability of seeds of many food crops through the human digestive
system and the wastewater and sludge treatment processes.  Application
of sludge may necessitate the use of herbicides for effective weed
control.  The concentration of herbicides in runoff and drainage water
should be monitored.

Application Rates

     Application rates depend on sludge composition,  soil characteris-
tics, climate, vegetation, and cropping practices.  Applying cludge at
an annual rate to support the nitrogen needs of a crop avoids problems
associated with pollution of water supplies.  Almost  all ill-effects a-
rise from too heavy or too frequent applications of sludge  (Reference D-3).
Total sludge application limitation is imposed by heavy metals content
of the sludge and is defined by Equation D-l on page  D-5.  Annual applica-
tion rate, on the other hand, is constrained by the available nitrogen
content of the sludge and is expressed in Equation D-2 on page D-ll above.

General Conclusions

     The application of liquid digested sludge has been shown by research
and by practical experience to have beneficial effects on agricultural
lands if proper rates of application (as determined by the properties of
the sludge,  the nature of the site and the characteristics of the crops
grown)  are adhered to.  These beneficial effects are  generally the re-
sult of the enhancement of soil properties and the addition of plant
nutrients that lead to increased crop yields.  There  are many references
that document increases in plant growth as a direct result of the applica-
tion of sludge.   Some studies even show that yields are higher on sludge
enriched soils than on soils which have received commercial fertilizer.
(Reference  D-23).
                                D-22

-------
    Although the application of sludge to a given area is extremely
site dependent,  some general conclusions which may be of use are pre-
sented below (Reference D-10, D-15, D-19):

    1)  Salt buildup in the soil can create a short term hazard to
        plant growth, but will not cause long-term problems if proper
        irrigation and drainage practices are followed.

    2)  Pathogenic dangers, as indicated by fecal coliforms, will not
        extend more than 120 to 150 cm (50  to 60 in.) into the soil
        profile, nor last more than 2.5 months near the soil surface.

    3)  Heavy metal contamination of the groundwater is  not a problem
        even at  high sludge loadings because of the soil's ability to
        adsorb and retain them.  Cadmium may be the first metal to
        present  such a problem (Reference D-15).

    4)  Heavy metal uptake by plants grown  on sludge amended soil is
        not expected to be excessive and should cause no plant toxicity
        or human dangers as long as the ultimate application rate limit
        is not exceeded.

    5)  Nitrate  leaching to the groundwater can be substantial, increas-
        ing directly with sludge application rates, and will be the
        first limiting factor for sludge application on a yearly basis.

    6)  Nitrate  leaching can be controlled  with management techniques
        involving balancing nitrogen applications with crop uptake.

    7)  Potential hazards to the groundwater can be more accurately
        monitored by measuring leachate quality and quantity than
        through  direct groundwater sampling.

    8)  Direct ingestion of sludge-applied  soil by domestic animals
        can be a potential danger to the human food chain through direct
        accumulation of heavy metals in edible tissues.

    9)  Seed germination can be inhibited if sludge is added just prior
        to planting.  If planting is conducted two weeks to one month
        after sludge application, seed germination is uninhibited.

   10)  Properly digested sludge will produce no offensive odors after
        application and incorporation into  the soil.

   11)  A sound  agronomic and environmental principle is to apply the
        least amount of sludge that will supply sufficient nutrients
        for plant growth.
                                  D-23

-------
    12)  Monitoring is necessary for sludge application programs  to
        ensure against creating environmental hazards.
 CHEMICAL PROPERTIES OF METRO DENVER SLUDGE

    The organic material generated by the Metro Denver Sewage Disposal
 District No. 1 will be anaerobically digested, and will contain organic
 and inorganic nutrients, humus, and residual levels of various metallic
 compounds.  The digested sludge will contain 6 to 8 percent  total
 nitrogen (expressed as a percentage of the dry weight of the organic
 materials), of which 3 to 4 percent (of the total dry solids) will be
 ammonia nitrogen.  The sludge will contain approximately 3 percent
 total phosphorus.

    The most recent heavy metals concentrations of primary and waste-
 activated sludges from the Northside and Central treatment plants are
 presented in Table D-4.  A flow-weighted average concentration is also
 computed and presented for the mixture that would result from blending
 these sludges.  A comparison of the quality of this mixture with that
 of a "good" sludge is presented in Table D-5.

    It can be seen that nickel and copper exceed the suggested limits.
 Excessive levels of these two heavy metals can adversely affect plant
 growth.  The cadmium/zinc ratio, which is perhaps the most important
 indicator of heavy metal toxicity, is higher than the suggested limits.
 However, with the conservative application rate recommendations and the
 calcareous nature of soils in the study area, it probably will not
 cause a significant problem.

    Metro Denver sludge contains all of the essential plant nutrients
 and possesses soil conditioning properties.  The nitrogen content is
 satisfactory for fertilization purposes.  The longer sludge is dried,
 the more ammonium nitrogen is lost through volatilization.
LAND USE OPTIONS FOR SLUDGE APPLICATION

    Four specific land use areas are being considered by Metro Denver
for the application of sludge.  These are: 1) city parks, 2) mine
spoil sites, 3) sod farms, and 4) irrigation and dryland farms.  In
this section, specific parameters will be discussed as they relate to
each land use.

City Parks

    The literature contains general references to the application of
sludge on city parks, lawns and golf courses, but no definitive studies
have been reported.   In New York City, sludge has been used as a soil
conditioner to produce artificial topsoil on proposed park sites (Ref-
                                 P-24

-------
Table D-4.  SLUDGE HEAVY METALS CONTENT COMPUTED FROM SAMPLES OBTAINED
       AND ANALYZED OVER A PERIOD OF FOUR MONTHS IN EARLY 1975



Parameter
Zinc
Copper
Nickel
Chromium
Lead
Cadmium
Manganese
Mercury6
Cd/Zn ratio


Pri-
mary
sludges3
927
587
268
301
275
9
131
17.8
0.0065

Heavy metals content ,
mg/kg dry sludge
Concentrated
waste-activated
sludges'3
1,252
916
289
545
383
24
97.5
4.2
0.019


Flow-
weighted
average0
1,145
808
282
465
347
19
109
8.7
0.017
 Arithmetic averages computed for 18 samples except for manganese and
 mercury (see footnotes d and e, below).

 Arithmetic averages computed for 17 samples except for manganese and
 mercury (see footnotes d and e, below).
Q
 It was assumed that the mixture contains 33 percent primary and 67
 percent concentrated waste-activated sludge.

 Arithmetic averages computed for two samples.
Q
 Arithmetic averages computed for three samples.

Source:  Raw data obtained from Metropolitan Denver Sewage Disposal
         District No. 1.
                                  D-25

-------
  Table D-5.  COMPARISON OF METRO DENVER SLUDGE HEAVY METAL CONTENT
                        WITH SUGGESTED LIMITS

                         (mg/kg dry solids)


Element
Zinc
Copper
Nickel
Chromium
Lead
Cadmium
Manganese
Mercury
Boron
Cadmium/ zinc
ratio

Existing
concentrations
1,145
808
282
465
347
19
109
8.7
51a
0.017


Suggested
(Reference D-24)
1,500
750
150
500
500
50
-
-
-
0.001 - 0.005b


limits
(Reference D-13)
2,000
800
100
-
1,000
< 0.5 % of zinc
-
15
100
0.005

a
 Obtained by computing  a  sludge  solids flow-weighted  average  of  grab
 samples described  on page D-15.  Grab samples were collected on 30
 October 1975.

 Reference D-13.
                                 D-26

-------
 erence D-ll).   Composted sludge and leaf mold are being used to
 renovate the  soil at the newly created Constitution Gardens in Washing-
 ton, B.C.  (Reference D-25).   Liquid and possibly dewatered sludge can
 be applied to the surface of turf grass, but odor might be a problem
 and time would be required before traffic could be allowed to return
 (Reference D-14).  The timing of sludge application could control the
 odor problem.   If sludge is applied in the winter, the snow and moisture
 will carry the nitrogen value to the root zone, will eliminate any
 perceptive odor,  and will accelerate lawn growth in the spring (Reference
 D-26).

     In general, grass is a good crop for sludge fertilization because
 it is tolerant of heavy metals, has a high rate of nitrogen uptake,
 and minimizes problems from runoff.  Furthermore, with each cutting
 appreciable quantities of salts and nutrients are removed from the
 land, if only to be placed in landfills.

 Mine Spoil Sites

     The literature contains many references to the use of sewage sludge
 for revegetation programs on mine spoil sites.  Most of these sites
 have been coal mine spoils, although the extreme environmental conditions
 associated with coal mine spoil sites are generelly similar to those of
 other large scale mining operations.  In general, problems result from
 extremely acid soil conditions, high rates of erosion and runoff, acidic
 runoff, toxic levels of certain metals in the soil, low soil fertility,
 low soil moisture content, and high summer surface temperatures.  Be-
 cause of the nature of mining operations, spoil sites necessarily do
 not possess a substrate favorable to plant growth.  Most soils evolve
 over long periods of time as a result of weathering of parent material
 and the accumulation of organic matter.

     Experiments with revegetation of spoil sites have confirmed the
difficulty of establishing vegetative cover on such harsh conditions.
There is frequently 100 percent mortality of plants on spoil sites with
no amendment.   On sites treated with sludge, plants germinate and
survive.

     The potential toxicity of a mine spoils site is best characterized
by the pH.  Although there is a difference in plant tolerance to acidity,
a spoil material with pH below 4.0 is toxic to most plants.  The pH of
most spoil sites is between 2.0 and 3.0.  At these values the high
solubility of certain metals such as iron, aluminum and manganese
severely inhibits plant growth.  Evans and Sopper report that on an
experimental plot, the untreated control boxes had complete mortality
of trees, grasses and legumes.  They also had the lowest average values
for phosphorus and nitrate-nitrogen and the highest values of iron,
manganese and aluminum.  Plots treated with effluent and sludge, had
the highest values for phosphorus and nitrate-nitrogen and the lowest
for iron, manganese and aluminum.  Since benign spoil materials are also
                                 D-27

-------
low in soluble phosphorus  and nitrate-nitrogen,  they concluded that
iron,  manganese and aluminum are more  directly related to revegetation
failures.   The higher concentrations  of these and other heavy metals
appear to. be the results of solubilization of the native rock by the
high acidity.   Irrigation  with effluent and sludge leached and diluted
the native salts (Reference D-27).   The addition of sludge also
increased both phosphorus  and potassium levels in the treated spoil
(Reference D-28) .

    The establishment of a complete ground cover of vegetation is highly
desirable since it can result in (1)  earlier stabilization and reduction
of erosion; (2) earlier mitigation  of  acid drainage by diminishing net
recharge through increased evapotranspiration losses; (3) the
acceleration of accumulation of organic residues which will chelate
and otherwise make unavailable the  soluble iron, manganese and
aluminum (Reference D-27).  Organic residues also provide the necessary
seed bed for plant germination.

     The major effects of the application of digested sludge to mine
the spoil sites include the improvement of spoil pH, increased
infiltration of precipitation, the  germination and establishment of
vegetation, and the reduction of acidity and concentrations of some of
the chemicals in the runoff issuing from the site (Reference D-29).

Sod Farms

     The use of digested sludge on  sod farms has been proposed by
Metro Denver and some of the sod growers in the Denver Area.  Sludge
contains all of the essential plant nutrients and enhances soil
properties through the addition of  organic residues.  Sod farming
involves the periodic removal of the topmost plant and soil layers,
thus the importance of the ability  of sludge to provide continuing
soil-building material becomes apparent.  Site conditions regulate the
application rate of sludge, depending on specific soil and crop
characteristics.  Grass is a good crop for sludge fertilization because
it is tolerant of heavy metals, is  not used as feed or food, has a
high rate of nitrogen uptake, and minimizes problems from runoff and
erosion.  If sludge is applied in the  winter, the snow and moisture
will carry nitrogen to the roots, will eliminate any perceptive odor,
and will accelerate vegetative growth in the spring (Reference D-26).

Irrigation and Dryland Farms

Digested sludge has been used widely in agriculture throughout the
United States and in other parts of the world.  Most of the material
discussed in this  appendix relates  to the agricultural use of sludge
and need not be repeated.   In general, dry farmland will sustain a
lower application  rate of  sludge because the rate of nitrogen uptake
of dryland crops is much lower than that of irrigated crops.  Most
irrigated and non-irrigated crops grown in the study area are either
                                D-28

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not consumed by humans or are processed to such a degree that sludge
contaminations are removed.

     Irrigated crops include many plants intended for direct human
consumption with minimal processing.  Even though it is not recommended
to apply sludge on fields growing such crops, proximity of the various
fields, rotation patterns and loss of records may lead to inadvertent
sludge contact with these plants.  Therefore, a greater degree of im-
portance should be attached to control and management recommendations
to mitigate adverse impacts on the food chain.
                                  D-29

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                     REFERENCES FOR APPENDIX D
 D-l.  CH2M HILL,  Agricultural  Reuse Program,  Denver,  Colorado,
       March 1973.

 D-2.  U.S. Environmental Protection Agency,   Process  Design Manual  for
       Sludge Treatment and Disposal,  EPA 625/1-74-006,  October  1974.

 D-3.  Evans, James 0., "Soils  as  Sludge  Assimilators,"  Compost  Science,
       Vol. 14, No. 6 (Nov.-Dec. 1973).

 D-4.  U.S. Environmental Protection Agency, Municipal Sludge Manage-
       ment: Environmental Factors,  Technical  Bulletin,  EPA 430/9-75-
       XXX, Preliminary Draft.

 D-5.  Chaney, Rufus L.  "Recommendations for  Management of Potentially
       Toxic Elements in Agricultural and Municipal  Wastes," in  "Fac-
       tors Involved in Land Application  of Agricultural and Municipal
       Waste," USDA, ARS, Beltsville,  Maryland,  1974.

 D-6.  Ellis, Boyd G.,  "The Soil as  a Chemical Filter,"  in Recycling
       Treated Municipal Wastewater  and Sludge Through Forest and Crop-
       land, Edited by William  E.  Sopper  and Louis T.  Kardos, The Penn-
       sylvania State University Press, University Park, 1973.

 D-7.  Epstein, Emanuel, Mineral Nutrition of  Plants:  Principles and
       Perspectives, John Wiley and  Sons, New  York,  1972.

 D-8.  Anonymous,  "Waste Water  Expert Answers  Indignant  Old Lady,"
       Compost Science, Autumn, 1969.

 D-9.  Lisk, Donald J.   "Trace  Metals in  Soils,  Plants,  and Animals,"
       Advances in Agronomy, Vol.  24, 1972.

D-10.  Hinesly, T. D.,  0. C. Braids, and  J. E. Molina, Agricultural
       Benefits and Environmental  Changes Resulting  from the Use of
       Digested Sewage Sludge on Field Crops,  U.  S.  Environmental Pro-
       tection Agency,  SW-30d,  1971.

D-ll.  Kirkham, M. B.,  "Disposal of  Sludge on  Land:  Effect on Soils,
       Plants, and Ground Water,"  Compost Science, Vol.  15, No.  2
       (March-April 1974).
                                 D-30

-------
D-12.  Epstein, Eliot, "The Physical Processes in the Soil as Related  to
       Sewage Sludge Application," in Proceedings of the Joint Confer-
       ence on Recycling Municipal Sludges and Effluents on Land,  U.S.
       Environmental Protection Agency, U.S.  Dept. of Agriculture,  and
       the National Association of State Universities and Land Grant
       Colleges, Champaign, Illinois, July 9-13,  1973.

D-13.  Chaney, Rufus L. "Crop and Food Chain Effects of  Toxic Elements
       in Sludges and Effluents," in Proceedings  of the  Joint Confer-
       ence on Recycling Municipal Sludges and Effluents on Land,  U.S.
       Environmental Protection Agency, U.S.  Dept. of Agriculture,  and
       the National Association of State Universities and Land Grant
       Colleges, Champaign, Illinois, July 9-13,  1973.

D-14.  Walker, John M., "Sewage Sludges — Management Aspects for  Land
       Application," Compost Science, Vol. 16, No. 2 (March-April  1975).

D-15.  Trout, T. J., J. L. Smith and D. B. McWhorter, Environmental
       Effects of Land Application of Digested Municipal Sewage Sludge,
       Interim Report, Department of Agricultural Engineering, Colorado
       State University, Fort Collins, Colorado,  1975.

D-16.  Office of Research and Monitoring, Task Force Report on Sludge
       Disposal, U.S. Environmental Protection Agency, April 1972.

D-17.  Malina, Joseph F., Jr., and Bernard P. Sagik, Eds., Virus Sur-
       vival in Water and Wastewater Systems, Water Resources Symposium
       No. 7, Center for Research in Water Resources, the University of
       Texas at Austin, 1974.

D-18.  Kellogg, Clay, "The Business of Processing and Marketing Wastes
       as Fertilizer and Soil Conditioner," Compost Science, Vol.  16,
       No. 3 (May-June 1975).

D-19.  Sabey, B. R. and W. E. Hart, Land Application of  Metro Denver
       Municipal Sewage Sludge, Final Report, Colorado State University,
       Agricultural Experiment Station, 1972.

D-20.  Carroll, Thomas E., David L. Maase, Joseph M. Genco, and Chris-
       topher N. Ifeadi, Review of Landspreading  of Liquid Municipal
       Sewage Sludge, National Environmental Research Center, Office of
       Research and Development, U.S. Environmental Protection Agency,
       EPA 670/2-75-049, June 1975.

D-21.  Powell, G. Morgan, Design Seminar for Land Treatment of Munici-
       pal Wastewater Effluents, prepared for U.S. Environmental Pro-
       tection Agency, Technology Transfer Program, CH2M HILL, Denver,
       Colorado, May 1975.
                                  D-31

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D-22.  Molina,  J.  A.  E.,  0.  C.  Braids,  T.  D.  Hinesly,  and J.  B.  Cropper,
       "Aeration-Induced  Changes  in Liquid Digested  Sewage  Sludge,"
       Soil Science Society  of  America  Proceedings,  35:  60-63,  1971.

D-23.  Struble, Robert G., "Sewage Sludge  Aids  Farm  Crops in  West  Ches-
       ter, Pennsylvania," Compost Science, Vol.  15, No. 2  (March-April,
       1974).

D-24.  Shipp,  Raymond F.  and Dale E.  Baker, "Pennsylvania's Sewage
       Sludge Research and Extension Program,"  Compost Science,  Vol.  16,
       No. 2 (March-April 1975).

D-25.  Patterson,  James C.,  "Enrichment of Urban  Soil  with  Composted
       Sludge and  Leaf Mold  —  Constitution Gardens,"  Compost Science,
       Vol. 16, No. 3 (May-June 1975).

D-26.  Olds, Jerome,  "How Cities  Distribute Sludge as  a  Soil  Condition-
       er," Compost Science, Autumn,  1960.

D-27.  Evans,  James 0. and William E. Sopper, "Forest  Areas for  Dis-
       posal of Municipal, Agricultural, and  Industrial  Wastes," Paper
       presented at the Seventh World Forestry  Congress, Buenos  Aires,
       Argentina,  October 4-18, 1972.

D-28.  Sutton,  P.  and J.  P.  Vimmerstedt, "Treat Stripmine Spoils with
       Sewage Sludge," Compost  Science, Vol.  15,  No. 1,  (January-Feb-
       ruary 1974) .

D-29.  Lejcher, Terrence R.  and Samuel  H.  Kunkle, "Restoration  of  Acid
       Spoil Banks with Treated Sewage  Sludge," in Recycling  Treated
       Municipal Wastewater  and Sludge  through  Forest  and Cropland,
       edited by William E.  Sopper and  Louis  T. Kardos,  The Pennsyl-
       vania State University Press,  University Park,  1973.

D-30.  Pratt,  0. F. "Effects of Sewage  Sludge of  Effluent Application
       to Soil on the Movement  of Nitrogen, Phosphorus,  Soluble Salts
       and Heavy Metals to Groundwaters,"  presented  at 2nd  National
       Conference  on Municipal  Sludge Management  and Disposal,  Anaheim,
       California, August 18-20,  1975.

D-31.  Farrell, Joseph, "High Energy Radiation  in Sludge Treatments —
       Status and  Prospects," presented at 2nd  National  Conference on
       Municipal Sludge Management and  Disposal,  Anaheim, California,
       August 18-20,  1975.

D-32.  Miller,  R.  H., "Factors  Affecting Decomposition of an  Anaerobi-
       cally Digested Sewage Sludge in  Soil," Journal  of Environmental
       Quality, Vol.  3, No.  4,  1974.
                                 D-32

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•

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     The discussion of environmental setting,
presented in Section III is supplemented in this
Appendix with a detailed 'study of site-specific
environmental characteristics.  The sites dis-
cussed here include the drying and distribution
site, the representative sludge reuse sites
(city parks, sod farms, mine spoil sites, irri-
gated farms and dryland farms), and the site of
the existing operations at the Lowry Bombing
Range.

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                            APPENDIX E

      ENVIRONMENTAL SETTINGS OF DRYING AND DISTRIBUTION SITE AND
        SPECIFIC LAND APPLICATION SITES FOR METRO DENVER SLUDGE
DRYING AND DISTRIBUTION SITE

     The proposed drying and distribution center, Site B-2, is located
about 32 km [20 miles] east of the District's Central Plant.  As shown
on Figure 2, it is 18 km [11 miles] southeast of Barr Lake and is bordered
on the south by Irondale Road.  The site is rectangular,  extending about
2.4 km [1.5 miles] in an east-west direction and 3.2 km [2 miles] in a
north-south direction.  The description of the environmental setting of
the drying and distribution site is taken from "Metro Denver Sludge Man-
agement, Volume IV, Environmental Assessment," by CH2M-Hill (February
1975).

Topography

     The topography of the project area is slight to moderately rolling
slopes.  Elevation of the terrain ranges from approximately 1,570 m to
16,40 m [5,150 ft to 5,390 ft] above sea level.  There is a slight ridge
running north-south through the center of the site.   The view to the
north from Irondale Road is generally unobstructed by topographic fea-
tures up to the ridge in the midpoint of the site.  A pronounced drain-
ageway occupies the southeastern corner of the site.

Soils

     The soils at the site are in general a tight, silty clay material
and have a low permeability rate compared to many soils in the area.
Soil depths have not been determined in the area of  the site.  These
soils have sufficient organic materials, with satisfactory nutrient lev-
els, for most crop production.  Low crop yields in the area can generally
be attributed to low rainfall.

Surface Water

     The project site has no perennial streams or other water bodies.
The site is on high ground and receives runoff only from within the site.
A natural drainage area in the southeastern corner of the site subjects
a small off-site area to surface inflow and possible flooding.
                                  E-l

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     Part of the site is subject to severe water erosion problems as a
result of high-intensity, sudden thundershowers and snowmelt on unpro-
tected soils.  The runoff is high in sediment and suspended solids.

Groundwater and Geology

     The proj'ect area is underlain by the Denver-Arapahoe-Dawson forma-
tion and the Laramie-Fox Hills formation.  Each of these formations
yields a small to moderate supply of water to wells for domestic and
livestock uses.  The uppermost bedrock is the Denver or Arapahoe forma-
tion.  Both formations are composed of layers of shale, sandstone
with some clay, and silt stone.  The aquifers in these formations are
more or less confined, and vertical permeability between water-bearing
zones does not occur readily.  The Laramie-Fox Hills formation under-
lies the site at an estimated depth of 270 to 400 m [900 to 1,300 ft]
and is considered the boundary between fresh water and brackish water.
Available resource information indicates that the water above the Laramie
formation is of good quality.

     The depth to groundwater on the site is typically 15 m [50 ft] or
more, with upland wells having a water depth of 30 m [100 ft] or more.
No groundwater was encountered in the top 3 to 4 m [10 to 12 ft] during
exploratory investigations with a backhoe.  The exact size and yield of
aquifers underlying the site is not known,

Biology

     Vegetation—

     Wheat crops are rotated on the project site, leaving 50 percent of
the crop area fallow each year.  Within the southeastern corner, the site
has a 1.6-hectare [4-acre] area of overgrazed prairie.  The site has no
trees or shrubs.  Vegetation consists of short grasses (blue grama, west-
ern wheat and buffalo), yucca, Russian thistle, wild lettuce, sunflower
and prickly pear cactus.  No rare or unique species of vegetation consid-
ered essential to the ecology of the region are present on the site.

     Wildlife—

     Wildlife studies did not identify any wildlife habitats essential
to the site's ecology.  In the general vicinity of the site, there are
varying species of rabbit, mouse, owl, hawk and coyote.  Except for the
coyotes, which are territorial animals, these species do well in dis-
turbed areas.  There is sufficient area surrounding the site to provide
new habitats for animals displaced by construction.

Air Quality

     Air quality in the vicinity of the project area is relatively good.
                                  E-2

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The site  is sufficiently removed from the Metropolitan Denver area to be
unaffected by the urban pollution problem.  The only significant deterio-
ration of air quality in the area occurs during dust storms.  The sever-
ity of these depends on conditions of wind, precipitation and soil dis-
turbance  such as plowing.  Even at its worst, however, wind-blown dust
does not  constitute a major problem in the area.

CITY PARKS

     The City of Denver has developed an elaborate park system.  More
than 100 named parks, and many interconnecting landscaped parkways,
cover more than 1,100 hectares [2,800 acres] within the city limits.
The topography of Denver is relatively flat, with an elevation ranging
from about 1,570 to 1,670 m [5,150 to 5,480 ft].  Two perennial water-
courses, the South Platte River and Cherry Creek, flow through the city.
Many lakes have been created,  most of which are included within the
City park system and are utilized for recreation.  The lakes are dis-
cussed under General Environmental Setting, above.  They are signifi-
cant with respect to runoff hazards from sludge applied to park areas
surrounding them.

Soils

     The soils in the City and County of Denver have not been surveyed
for agronomic purposes because of the predominantly nonagricultural
land use in the metropolitan area.  Therefore, detailed information
about these soils is unavailable.  The information presented is thus
surmised from the general surface geology and soil conditions of the
surrounding counties, augmented with limited site observations.

     It is assumed that soils in the City parks are generally low in
clay content (loams, silt loams,  sandy loams and possibly some dry
loams), with correspondingly low cation exchange capacity.  Most of the
soils are probably calcareous, beginning at some depth below the sur-
face,  if not found throughout the profile.  Because of the necessary
grading and leveling activities,  most of the profiles are probably sub-
stantially altered, and most of the topsoil has been moved from one
place to another.  Of the more than 100 established parks in Denver,
most are on subsoils of heavy clay "plated" with a thin layer (7.5 to
10 cm [3 to A in.]) of imported topsoil.  Some 15 to 20 parks are
planted on old landfills with a fine cover of topsoil.

Biology

     Vegetation—

     The vegetation of the City parks can be characterized generally
as urban landscaping and has been described above, under Urban/Residen-
tial Unit.  With the exception of the two stream courses traversing the
                                   E-3

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city, the site of Denver was originally part of the mixed prairie, but
a variety of nonnative trees has been planted along the streets and in
the parks.  Chief among these trees are soft maple, elm, weeping willow,
Carolina poplar, Lombardy poplar, ash, sycamore, Norway pine, Russian
olive and several varieties of fruit trees.   The City park system is
entirely artificial, with extensive lawns, gardens, shrubs and trees
having been planted on graded, leveled and filled areas.  Many of the
parks include golf courses with extensive areas of grass.

     Some nearby urban communities with extensive park sites, such as
Northglenn, Commerce City and Aurora, have expressed interest in apply-
ing sludge to their City parks, also.

     Wildlife—

     The urban and residential environs of the Denver Metropolitan area
represent a unique, though unnatural, environment.  The introduction of
nonnative shrubs, herbs, grasses and trees has incidentally selected
and attracted many animal species that normally would not occur in this
area.

     Chief examples of such introductions are the red-eyed vireo,
bronzed grackle, robin and house sparrow.  Some species are typically
introduced with urbanization and become established as pests which de-
stroy food and property or endanger public health.  These "undesirables"
include the starling, house mouse, Norway rat and, in some cases, the
pocket gopher.

     A woodland-type atmosphere has been created by planted groves of
trees within many of the City parks.  Native species which can adapt to
human presence include the black-capped chickadee, house finch and
chipping sparrow.  Occasionally several bat species may also be found
within the trees.  The large expanses of grass within the City park
system and golf courses particularly attracts robins and starlings.

Noise

     The Denver Metropolitan area has many noise sources and attendant
noise pollution similar to that found in all large cities.  In the resi-
dential areas, transportation systems are the most noticeable sources of
noise.  Generally, the extensive City parks are bounded and traversed by
multi-laned streets and expressways.  Steady automobile traffic produces
ambient noise levels of 60 to 95 decibels.  Particularly abrasive noises
greater than 85 decibels are generated by trailer trucks, motorcycles and
sports cars (Reference 89).

     Within the urban and residential areas, noise sources are regulated
by speed limits and designation of traffic corridors.  Thus, residences
                                  E-4

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and community facilities are somewhat screened from extreme noises.
Trees and shrubs in the residential areas, particularly in the patchwork
City park system of Denver, reduce sound levels to some degree.  The
presence of decorative plantings, although they do not significantly
reduce noise levels, often have the effect of reducing the incidence of
complaint about noise (Reference 89).

Odor

     At the present time, odors in City parks are determined by particu-
lar local neighborhood activities (industrial emissions in certain parts,
poorly controlled exhaust from stationary and mobile sources in other
parts and temporary odors caused by applications of chemicals to lawns
and trees, etc.).  City park and public works crews attend to the
cleanliness and maintenance of the park areas.  Overall, under most con-
ditions, there are no noticeable disturbing odors present at City parks
where large numbers of people spend a great deal of time walking, sit-
ting, lying on the grass, eating lunch and engaging in sports activi-
ties.

SOD FARMS

     Sod farms represent a special type of irrigated farm.  Many hec-
tares in Adams and Weld counties, as well as in other areas south of
Denver, are used for this grass culture.  Sod farms yield one of the
major nonconsumptive crops in the area.  The sod is used solely for
landscaping and decorative plantings.  Sod farms typically require warm,
sunny weather, frequent irrigation and heavy fertilization.

     A representative sod farm was examined in Adams County and is
shown in Figure E-l.  The farm is located near Brighton, east of Barr
Lake.  It is owned by Bill Mathews and includes areas in Sections 25
and 26, T.l.S, R.65W.  Elevations vary gradually.

Soils

     The soil in the Mathews sod farm is nearly uniformly Trackton
loamy sand,  on nearly level to moderately sloping land, as shown on Fig-
ure E-2.  The soil texture is rather uniform to a depth greater than
150 cm [60 in.].  It is a noncalcareous soil with neutral pH and rather
low cation exchange capacity.  The soil absorbs water rapidly and does
not allow runoff except at very high precipitation rates;  thus, water
erosion hazard is very low.  However, the soil is subject to severe
wind erosion if it is not stabilized with vegetation.

Water

     Groundwater is the only source of water for irrigation of the sod
farm studied.  Groundwater table is at a depth of about 20 m [60 ft].
                                  E-5

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             FIGURE E-l
     SOD FARM
        AND
DRYLAND WHEAT FARM

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NOTE : FOR A DESCRIPTION OF SOILS AND
    CORRELATION OF MAP SYMBOLS SEE
    TABLE


 SOILS ON THE SOD FARM AND

ADJOINING DRYLAND  FARMS IN

       ADAMS COUNTY

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However, deep reservoirs are pretreated for irrigation water supply.
The Laramie-Fox Hills aquifer,  at this point,  is at a depth of approxi-
mately 370 m [1,200 ft] from the land surface and is well protected by
a great thickness of intervening aquitards, as described under Geology,
above.

     Surface drainage is provided by Box Elder Creek, which traverses
the Mathews farm in a north-south direction.  The streambed is dry
nearly year-round and is used for a cow pasture.  (The owner of the
farm proposes to apply sludge to this part of his farmland as well as
to the sod farm and adjacent dryland wheat fields.)  Frequency of oc-
currence of flow in Box Elder Creek, by the estimate of the owner, is
once every five years.

Biology

     Vegetation—

     Kentucky bluegrass is the basic crop of the sod farm.  Thick sod
mats formed by this grass constitute a stable community, effectively
excluding other competitive plant species.  The crop period varies from
nine to 18 months and follows the procedure described below:

     1.  Seed bed preparation—The fields are plowed and graded where
necessary.  Chemical fertilizers with a nitrogen-phosphorus-potassium
(N-P-K) percentage of 16-16-8 or 18-46-0 are applied to the prepared
surface at up to 110 kg/ha [100 Ib/acre].

     2.  Seeding—Several varieties of Kentucky bluegrass may be used.
Particular strains may be chosen for their hardiness, ability to with-
stand cold and adaptability to local conditions.  Common blends include
merion, Windsor, pennstar, fyIking, baron, nugget and newport.

     3.  Cultivation and maintenance—The newly planted beds are irri-
gated frequently for the first three to four weeks until the plants are
set and a sod layer begins to form.  At this stage, the crop undergoes
a regimen of spray irrigation as often as once per day, weekly mowing
and monthly fertilization.  Chemical fertilizers most commonly used
have an N-P-K percentage of 20-20-10 or 16-16-8, such as ammonium sul-
fate, and are applied typically at 335 kg/ha [300 Ib/acre].  Compara-
tive fertilizer usage is shown in Table E-l.

     4.  Crop harvest—Prior to harvesting, the sod may be treated with
a high-nitrogen fertilizer such as 46-0-0 and irrigated every one to
two days to prepare it for transporting.  The upper sod layer is har-
vested with special machines, which cut an approximately 5-cm [2-in.]
thick sod and soil mat of 45-cm [18-in.] width.  The sod strips are
rolled up into large rounds and immediately shipped to the customer.
                                 E-8

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       Table E-l.  COMPARATIVE FERTILIZER USAGE AT SELECTED SOD FARMS IN THE DENVER REGION

Farm
A
B

C

Dd


Ee
Fertilizer
type,a
N-P-K
20-20-10
16-16-8
46-0-0
18-46-0
33-0-0
5-3-3
5-3-3
32-0-0
20-20-10
Application
rate,
kg/hac
225
335
450
110
225
1,900
1,455
450
335
Application
frequency,
times per year
7 to 8
7 to 8
1 to 2
1
4
1
7 to 8
1
4
Maximum nitrogen Crop
application rate,b cycle,
kg/ha months
335 12
705 9 to 12

315 18

450
t0 14
840

270 18
o
 Fertilizer composition expressed as percentage of  nitrogen,  phosphorus  and  potassium (N-P-K)

 the total mixture.

 Nitrogen is calculated as N,  assuming maximum amount  and  number  of  applications per year.

Cl kg/ha = 0.893 Ib/acre.

 Farm D utilizes dried poultry wastes as primary fertilizer.

^lathews farm used as representative sod farm.



Source:  References 90,91,92,93,94,
in

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As the cut sod does not store well, it is usually cut the day prior to
shipping.  The harvest period varies from 9 to 18 months.  Vegetative
growth is most active during the spring and summer and slows consider-
ably as the weather becomes colder.  During the winter months, the
grass enters a period of dormancy requiring little irrigation or fer-
tilization.  This resting period is necessary for future grass growth.
The type of grass species and length of winter dormancy determine, to
a great degree, the cropping period.  Sod crops can also be regrown
from the trimmed sod.  When the demand is low, the sod crop—unlike
consumptive products—can remain on the ground to be harvested at a
later date without deterioration of quality.

     Wildlife—

     A sod farm represents a greatly simplified ecosystem of short
grass and sod.  Wildlife is generally dominated by a few species, which
are seasonal in occurrence.  In the planting stage, seed-eating birds
such as Brewer's blackbird and the western vesper sparrow are common.
As the crop growth progresses, earthworms, grasshoppers and their preda-
tor, the western meadowlark, proliferate.  Small grass-eating and burrow-
ing animals are less common in a sod farm compared to other cultivated
fields.  This is due to the constant mowing and maintenance, which dis-
turb the animal habitat.  Mammal species which may be found in the vi-
cinity of sod farms are the pocket gopher, meadow vole and jackrabbit.

Noise

     The countryside is generally noted for its quietude.  The vastness
of the plains area and generally open conditions allow for rapid noise
dispersal.  The main sources of noise pollution are trucks and automo-
biles travelling on the roadways crossing the plains region as well as
farm equipment and machinery.  Farm equipment is generally heavy duty
and can generate noise levels equivalent to a truck-trailer.  However,
the relatively low density of farms and their remoteness make this
noise source insignificant in the overall context.

Odor

     There are usually no noticeable odors on a sod farm except imme-
diately after mowings.  These are pleasant and temporary smells con-
fined to the immediate area of the mowed fields.

MINE SPOIL SITES

     The Climax molybdenum mine,  used as an example of mine reclamation,
is situated in the Colorado Front Range approximately 80 km [50 miles]
west of Denver.  The location of  the mine and tailings pond is shown in
Figure E-3.   The mine site is reached via U.S. Highway 40 and is approxi-
mately 6 km [3.7 miles]  southwest of Berthoud Pass and 3.4 km [1.9 miles]
                                 E-10

-------
south of the Continental Divide.  The terrain is rugged and mountainous
and is transected by deep canyons.  The Urad mine and spoils site is
located in the narrow canyon of Woods Creek, which is a tributary to
Clear Creek.  The Henderson mine and spoils site is located in the upper
section of the west fork of Clear Creek.  Elevation at the site is ap-
proximately 3,100 m [10,400 ft] above sea level.

     The mining operations are conducted by Climax Molybdenum.  The
molybdenum-rich ore is mined from 900 m [3,000 ft] below the surface.
The ore is crushed and washed in an acid solution to extract the metal,
which is further refined.  The residual rock material is finally depos-
ited in the large tailings near the foot of Woods Creek Canyon and
Upper Clear Creek Canyon.  Leachates from the tailings are further col-
lected downstream in a settling pond before entering Clear Creek.

     The mine spoils areas are wedge shaped and cover approximately 60
ha [140 acres] to a depth of 75 m [250 ft].  The rock material on the
site is coarse monzonite, only 16 percent of which passes through a 2  mm
sieve.  The final surface of the spoils site has been leveled to pre-
pare for reclamation with sludge and wood chips and for plantings.  At
the present time, 6 ha [15 acres] have undergone initial reclamation
and another 50 ha [125 acres] await reclamation.

     Climax Molybdenum anticipates reaching full capacity at the Woods
Creek Canyon spoils site by 1980.  At that time, a new site will be
used for tailings, and the old site will be available for full reclama-
tion.  By the year 2030, the ore at this particular site will probably
be depleted, and the operations will be transferred to a site near
Leadville, 190 km [120 miles] from Denver.

Climate

     Located near the crest of the Continental Divide, the mine site
experiences some extremes in climate, as shown in Table E-2.  The mean
annual temperature is less than 0°C [32°F], and mean temperatures are
below freezing for six months per year.  The growing season is relative-
ly short, extending from one to two months in duration.  Precipitation
is heavy.  A great deal of the precipitation occurs as snowfall.  Snow-
fall amounts to more than one meter [3.3 ft] for at least six months per
year, with the period from June to September being the most clement.

Geology

     The mine spoil site is located on landslide deposits from the pre-
Cambrian Silver Plume Granite and the Tertiary Porphyritic Rhyolite.
Samples from the spoil site show that the tailings themselves are from
the Silver Plume Granite.  Most of the tailings are composed of porphyri-
tic quartz monzonite veined with molybdenite and pyrite.  Some pegmatite
with large grains of molybdenite also make up part of the tailings.
                                  E-ll

-------
                               FIGURE  E-3
       BERTHOUCh-RASS 5 km
                        ,02°
            ~\  Pia-te Gr, u.ivls  ^
                        DENVER 80km 50 miles)
                 REPRESENTATIVE
                        MINE
                    SPOIL SITE
E-K

-------
         Table E-2. TEMPERATURE, PRECIPITATION,  SNOW AND FREEZE DATA,  BERTHOUD PASS

Temperature
*C -11.4 -11.4
[°F] 11.5 11.4
Pr ecipitatipn
mm 72.9 73.2
[in.] 2.87 2.88
i Snowfall
00 cm 110.2 112.5
[in.] 43.4 44.3


-8.4 -4.4
16.8 24.1

91.7 108.5
3.61 4.27
134.6 144.5
53.0 56.9
Freeze threshold temperature
°C
0
-2.2
-4.4
-6.7
-8.9
[ "F 1
32
28
24
20
16


1.6 5.
34.8 42.

84.6 73.
3.33 2.
80.8 41.
31.8 16.
Mean
spring





Nov Dec

7 10.4 9.1 5.3 0.6 -6.2 -».l
3 50.8 48.3 41.6 33.0 20.8 15.6

4 72.9 63.0 58.2 55,1 73.7 94.5
89 2.87 2.48 2.29 2.17 2.90 3.72
7 0 0.8 23.9 65.0 112.3 125.5
4 0 0.3 9.4 25.6 44.2 49.4
number of days between date of last
occurrence and first fall occurrence
41
64
90
118
137
Annual

-1.5
29.3

921.5
36.28
951.7
374.7






Source:  Decennial Census of United States Climate;  Cllmatological Data for  the U.S.:   Colorado

-------
     Both molybdenite (MoS2) and pyrite (FeS2) are sulfides whose oxida-
tion leads to acidic mine drainage.   Without alterations and amendments,
these rocks can be expected to provide an inhospitable substratum for
plant growth,

Soils

     There are no soils in the mine spoil site under study; nor
would there be any developed soils at any other such sites destined for
reclamation.  The material involved in reclamation is processed rock,
extracted from great depths, largely unaffected by soil-forming factors.
At the Urad and Henderson mine sites, the spoil materials are very
coarse (from gravel to boulder-size primary particles),  are angular and
are incapable of supporting plant life.  Due to the acid treatment for
extraction of molybdenum, these rocks can be expected to retain an aci-
dic reaction for several years.  Any reclamation scheme  would necessari-
ly require a change in the texture of the surface material in addition
to introduction of organic matter and fertilizer elements.

Water

     Tributaries to Clear Creek, i.e., Woods Creek and the upper sec-
tion of the west fork of Clear Creek, flow along the mine spoil sites
studied.  Because of the exposed bedrock and occurrences of very thick
consolidated rocks in the area, groundwater is of minor  significance.
Large holding basins in the mining areas are used to settle the fine
particles suspended during processing of the rocks.   Effluent from the
ponds is discharged directly to the streams draining into Clear Creek.

Biology

     Vegetation—

     The vegetation on the mine spoil site is quite sparse, mainly be-
cause of the lack of soil.  A thin layer of sludge mixed with wood chips
and bark has been applied, and systematic planting of spruce, pine, juni-
per and aspen seedlings has been conducted.  Some grass  has also been
seeded, and a few other native plants, such as yarrow, big sagebrush,
bear berry and buffalo berry,  have established themselves with the germi-
nation and growth of a few individuals.  All of the vegetation on this
site is growing very slowly, and some of it, such as the buffalo berry,
appears stunted.  Some of the tree seedlings have died.

     Wildlife—

     The mine spoils site is a severely disturbed area with very sparse
plant growth, as described above.   The exposed strata of rock and gravel
provide a relatively sterile environment with no resident animal species.
Visitants from the neighboring lodgepole pine forests may include mule
                                E-14

-------
deer, coyote, striped skunk, mountain vole and snowshoe hare.  Probable
bird species passing over the area are Cooper's hawk, turkey vulture,
gray jay and gray-headed junco.

Noise

     The mine spoils site is rural and fairly isolated.  Traffic along
Highway 40, which is 1.6 km [1 mile] away from the site, represents a
small fraction of ambient noise.  The main source of noise is from the
processing of the ore.  The rock-crushing and washing apparatus prob-
ably generate the most noise, while the small but steady truck traffic
to and from the site augments the background noise levels.  The rela-
tive isolation, heavy growth of trees adjacent to the site and steep
valleys effectively confine the noise from the mining operations.

Odor

     The molybdenum mine has few associated odors.  On the limited
tailing areas where reclamation has begun, some odors uncommon to  the
area are generated.  The weathering of wood chips and sludge into  the
upper rock material exudes a faint decomposition odor at close range.
However, the material deodorizes rapidly, and no odors are perceptible
30 m [100 ft] from the site.

IRRIGATED FARMS

     There were almost 17,000 hectares [42,000 acres] of irrigated
farms in Adams County in 1973 (Reference 95), about five percent of
the whole county.  By contrast, only about 900 hectares [2,200 acres]
are irrigated in Arapahoe County (Reference 14), less than one percent
of the county.  Areas of irrigated crops and value of all crops grown
in Weld, Adams and Arapahoe counties are presented in Table E-3.  The
proportion of irrigated land increases from south to north due to  in-
creased availability of surface and groundwater supplies.  In Adams
County, most of the irrigated farms are along the South Platte River
and its tributary creeks.  Water is directed from these watercourses,
and pumped from the groundwater reservoir, as well as from various
sources on the western slopes of the Rockies.

     The principal irrigated farm used for detailed study is located
in the southern part of Weld County, east of Platteville, as shown on
Figure E-4.  It is a 223-hectare [550-acre] field owned by Ray Olin of
Platteville and is, in part, in Sections 16 and 17, T.3N., R.66W.   The
land has gentle, uniform slopes of about two percent draining into the
Platte Valley Canal.  It is, at its closest boundary, about one km
[0.6 mile] from the eastern edge of the town of Platteville.  U.S.
Highway 85 and the Union Pacific Railroad tracks are located about one
km [0.6 mile] to the west of the irrigated farms.  Road 32 connects the
farm to the town and to the major thoroughfares.
                                E-15

-------
     Table E-3.  VALUE  AND AREA  OF CROPS HARVESTED  IN WELD, ADAMS  AND ARAPAHOE COUNTIES IN 1973
Crop
Winter wheat
Spring wheat
Grain corn
Silage corn
Barley
Grain sorghum
Dry beans
Sugar beets
Oats
All hay
Potatoes
Other crops
All crops

Value,
1,000
dollars
15,644
18
15,284
35,789
3,138
35
7,396
20,033
388
14,700
2,285
4,529
119,239
Weld County
Irri-
gated

Non-
irrigated
(hectares)3
1,900
40
24,100
48,000b
9,500
40
7,400
14,300b
2,100
49,200b
1,400
....
157,980C
70,100
40
200
....
4,200
200
80
	
500
....
	
....
75,320C

Value,
1,000
dollars
14,073
179
1,442
1,560
921
86
122
474
54
2,644
...
2,624
24,179
Adams County
Arapahoe County
Irri- Non-
gated 	 irrigated
(hectares)*1
1,600
400
2,200
2,500b
1,400
100
200
400b
300
7,900b
...
. . .
17,000C
53,000
500
100
....
5,100
300
....
....
300
....
	
....
59,300C
Value,
1,000
dollars
5,378
13
125
320
304
24
...

4
711
...
358
7,237
Irri"
gated
Non-
irrigated
(hectares)"
200

100
700b
40
80


...
3,200b

. . .
4,320C
23,000
100
200
	
2,600
100
....
....
80
....
....
....
26,100C
 Original source data  are in acrei-:   1 hectare » 2.471 acres.
 Total area (irrigated and nonirrigated, if any).
 Total areas of harvested crops do not include "other crops" and vary considerably  from year to year.  Irrigated areas may include
 minor amounts of nonirrigated areas.

Source:  Colorado Department of Agriculture, 1973-1974 Colorado Agricultural Statistics

-------
                                                     FIGURE  E-4

        STATE HIGHWAY 85
                                          REPRESENTATIVE
                                            AGRICULTURAL
                                            REUSE AREAS
31
                            E-17

-------
     The crops that have been grown on this irrigated farm in recent
years include alfalfa, corn,  wheat and some sugar beets,  Groundwater
is used as the principal source of irrigation water supply.  Depth to
groundwater table is, at places, only one meter [3 to 4 ft] from the
surface.  Intensive agronomic management practices, typical of high-
yield irrigated agriculture,  are followed using modern equipment and
the recomendations of agricultural extension services.  Thus, a high
degree of control over application of amendments to the soils can be
expected in this and most other irrigated farms.  Commercial fertilizer
application rates commonly used in the irrigated farms in the area are
87 kg/ha [78 Ib/acre] nitrogen (as N) and 100 kg/ha [90 Ib/acre] phos-
phorus (as P) on pinto beans  and sugar beets.  Barnyard manure is used
on sugar beets in the early growing stages.  Corn receives from 112 to
225 kg/ha [100 to 200 Ib/acre] of nitrogen in anhydrous ammonia form,
injected into the irrigation  water.

Soils

     The most widespread soils which are found in the irrigated farms
in southern Weld County and northern Adams County (nearest to the sludge
distribution center) are presented in Table E-4.  The pertinent charac-
teristics of each soil are tabulated from data furnished by the U.S.
Soil Conservation Service. The suitability and limitations of each
soil are also presented, on the basis of the characteristics of the soil.
These subjective ratings do not include the properties and implications
of the crops grown upon these soils.  Crop implications are covered under
the discussion of impacts upon the food chain and in Appendix D.

     It appears that most of  the soils under irrigation in the study
area possess the properties which would potentially make them suitable
for sludge application.  There are, however, a few soils (such as Loup-
Boel, Valent and Tassel) which may be patently unsuitable for reuse of
sludge.

Biology

     Vegetation—

     Large areas of Weld County and smaller sections of Adams and
Arapahoe counties are irrigated farmland.  Primary crops are corn for
silage and grain, sugar beets, winter wheat and hay.  Crops of lesser
importance in the study area  are barley, dry beans, sorghum, oats, po-
tatoes, fruits and vegetables.

     Crops are generally cultivated on a rotational basis that varies
with the soil, terrain and available water.  Spring-planted crops are
seeded in the relatively dry, open-weather months, from early March
through June,  The ambient temperatures and type of crop determine the
                                 E-18

-------
               Table  E-4.   PERTINENT  CHARACTERISTICS3  OF  SELECTED  SOILS  UNDER  IRRIGATION  IN WELD  COUNTY
m

Soil M.-p
series, sym-
typeb bol
Vona, 51,
fine 51B,
sandy 11B
loam
Dacono, 17M
clay
loam
Olney, 21B
loamy
sand
Altvan, 23
loam

Thedalund, 43
clay
loam
Loup-Boel, -9
sandy
loam
Otero, 53,
sandy 54
loam
Renohill, 66B
clay
loam
Valent, 72
fine
sand
Depth Clay
to con-
rock, Slope, tent,
cmc % %
>150 0
to
12

>150 0
to
6
>150 1
to
10
>150 0
to
15
50 0
to to
100 15
(unavailable at


>150 0
to
10
>150 2
to
15
>150 0
to
25
low



35
to
50
18
to
35
17
to
35
18
to
35
the present


5
to
18
35
to
50
very
low

Cation
exchange
capacity,
<:eq per
100 g soil
very
low


60
to
80
12
to
20
_..


—


time)


—


70
to
100
very
low

pHd
6.6 to 7.3
7.4 to 8.4


6.6 to 7.8
7.4 to 8.4

6.6 to 7.8
7.9 to 8.4

6.1 to 7.3
7,4 to 9.0

7.9 to 8.4





7.4 to 8.4


6.6 to 7.8
7.9 to 9.0

6.6 to 7.8


Permea-
bility,
cms/hr
5
to
15

0.5
to
1.5
0.5
to
15
0.05
to
5
1.5
to
5



15
to
50
0.05
to
1.5
15
to
50
Sludge application/reuse
Suita- Limi- Management
bility tation needed
moderate low CEC liming,
and pH low rates


high low pH liming


moderate low pH liming


moderate surface
texture

high


low flooding —


moderate low CEC,
clay
content
high


low low clay liming
content,
low pH

-------
          Table E-4  (Continued).  PERTINENT CHARACTERISTICS  OF SELECTED  SOILS  UNDER IRRIGATION IN  WELD  COUNTY
i
ro
o


Soil
series,
typeb
Tassel,
fine
sandy
loam


Shingle,
clay
loam


Hop
sym-
bol
84





87B



Depth
to
rock,
cmC
25
to
50



>150





Slope,
%
3
to
25



0
to
25

Clay
con-
tent,
%
low





18
to
35
Cation
exchange
capacity,
tneq per
100 g soil
very
low




low




Permea-
bility,
PIT cms/hr
7.4 to 8.4 5
to
50



7.4 to 9.0 1.5
to
5




Sludge application/reuse
Suita- Limi-
bility tation
low low clay
content,
depth to
bedrock,
high per-
meability
moderate low clay
content

Management
needed
_..





__


 Basic soil characteristics were  obtained from soil survey descriptions and interpretations provided by  the USSCS.

 Soil type refers to  the texture  of the  airface of the typifying pedon.

°1 cm = 0.3937 In.


 The first values refer to soil characteristic in the upper layers (top 15 to 50 cm) and the second values refer to deeper layers-

-------
irrigation water need.  Spring and summer rainfall is generally inade-
quate for most crop production.  Harvest of spring grains begins in
August and is completed by mid-September.  Cutting of dry beans occurs
in early September, while corn and sorghum are harvested from late
September to mid-October.  Sugar beets are harvested from early October
to mid-November.

     Wildlife—

     Wildlife on cultivated lands is generally seasonal and often re-
flects the type of crop grown in an area.  On irrigated farmlands that
produce crops such as alfalfa, corn, vegetables and some grains, insec-
tivorous birds predominate.  Easily visible spring and summer birds in-
clude the western meadowlark, Brewer's blackbird, robin, lark sparrow
and grasshopper sparrow.  Seed-eating and often crop-eating birds,
which are most abundant after planting and at harvest times, include
several species of blackbirds, sparrows, migratory waterfowl and, in
some areas, the introduced ring-necked pheasant.

     Small rodents, generally viewed as agricultural pests, are an im-
portant part of the food chain.  Burrowing and nest-making animals in-
clude pocket gophers, ground squirrels, jackrabbits, harvest mice and
meadow voles.  Predators which control the small animal populations are
the red-tailed hawk, Swainson's hawk, ferruginous hawk and, rarely, the
golden-eagle.

     The cultivation of former prairie lands has not only changed the
overall habitat but has also added a few ecological "niches."  Agricul-
tural remnants and surplus areas, such as streambanks, road edges,
fencerows, corners and woodland patches are important wildlife shelter
and wintering areas.  Unharvested strips, stubble and fallow areas pro-
vide a valuable food supply during the winter.

Noise

     Noise levels of an irrigated farm are similar to those discussed
in the section on noise under the heading Sod Farms, above.

Odor

     Background odors on irrigated farms are often pleasant and natural:
the scents of the freshly turned soil and cut hay and the  subtle aromas
of growing crops.  To some, even the animal manure odors on farms are
not particularly unpleasant because of their association with the seren-
ity of rural living.  Where chemicals are used  (fertilizers, pesticides,
herbicides, etc.), temporary odors from their vapors, dusts and other
aerosol components spread to surrounding areas, downwind of application
areas.
                                 E-21

-------
DRYLAND FARMS

     In Adams! County there are 146,000 ha [360,000 acres] of nonirri-
gated farms, and in Arapahoe County nearly all farms are nonirrigated
(Reference 95).  Areas of various crops under nonirrigated culture are
shown in Table 22 for Weld, Adams and Arapahoe counties.

     An estimated 97,000 ha [240,000 acres]  in Adams County is unsuit-
able for cultivation or is in native grasses used for grazing (Refer-
ence 10).  These areas are also potential recipients of sludge for
improved production of fodder and are treated collectively under the
heading Dryland Farms both in the discussion of general environmental
characteristics in the present section and in the section on impacts,
below.

     Wheat and barley are the principal crops grown under dry farming.
Generally, dryland farming involves a lower degree of management control
than does irrigated farming because of the low relative value of crops
produced per unit area of land.  Occasional droughts (sometimes lasting
for two consecutive years) bring production down to nearly zero.  Dry-
land farming is typically characterized by very extensive land holdings
requiring highly mechanized harvesting procedures and equipment.  Soil
conservation practices, such as rotation fallowing, and water conserva-
tion practices, such as scarring the soil surface for better penetration
of rainfall and improved water storage, are generally practiced.

     In dry-farming areas, sources of water supply are generally at
considerable distances from the farms and thus are not threatened by
pollution from runoff from those farms.  However, in certain other areas
(where dry farms are adjacent to irrigated areas or dry river bottoms
are used for pasture), the groundwater table may be close to the surface,
and intermittent stream courses may be affected by the operations.

     Two example sites used for detailed study are (1) east of the sod
farm described earlier and (2) near the irrigated farm described above.
These sites are shown on Figures E-2 and E-4, respectively.

Topography

     Dry farms are generally located on gently sloping, rolling topogra-
phy with slopes up to about 15 percent.  The noncultivated pasture areas,
such as dry streambeds, flood plains, hillsides and rocky areas, have
less regular topography and have steeper slopes.  None of the dry-farmed
areas are graded.

Soils

     Soils in the dryland farm areas in Adams County are shown in Fig-
ure E-4.  Some of their characteristics pertinent to sludge application
                                 £-22

-------
are presented in Table E-5.  These soils are deep, almost uniformly non-
calcareous in the surface "plow" layer and highly calcareous below (with
the exception of Truckton, which is noncalcareous throughout).   This
pattern leads to low pH in the top layers and alkaline condition in the
lower strata.  Clay content and cation exchange capacity are generally
very low, and the soils are subject to erosion by blowing wind  and over-
land flow of water.

Biology

     Vegetation—

     Crops are generally cultivated on an annual cycle beginning in
the fall.  After the first fall rains, winter wheat and winter  barley
are seeded in September and October.  In some cases, erosion and crust-
ing of soils may necessitate a second seeding.  Favorable climatic con-
ditions during November and December enable the crops to grow to a
strong stand before entering dormancy during January and February.
The wheat plants begin greening up by March but are subject to  dry,
windy conditions during April and May.  The amount of spring and summer
rain determines the success of the wheat and barley crops.   Under favor-
able conditions, the crops can be harvested during the summer.   The
higher elevations are often harvested late into the summer.  With the
fall rains, the dry-farming cycle begins again.  Water conservation re-
quires fallowing and scarification of the land surface in the fall.

     Wildlife--

     Dryland farm areas are generally less intensively cultivated com-
pared to irrigated farm areas.  This seasonal monoculture of grain
crops leads to somewhat lower diversity of animals than is  found in
the irrigated farm.  Easily visible spring and summer birds include
the western meadowlark, Brewer's blackbird, robin, lark sparrow and
grasshopper sparrow.  Seed-eating and often crop-eating birds,  which
are most abundant after planting and at harvest times, include  several
species of blackbird, sparrow, migratory waterfowl and, in some areas,
the introduced ring-necked pheasant.

     Small rodents, generally viewed as agricultural pests, are an im-
portant part of the food chain.  Burrowing and nest-making animals in-
clude pocket gophers, ground squirrels, jackrabbits, harvest mice and
meadow voles.  Predators which control the small animal populations
are the red-tailed hawk, Swainson's hawk, ferruginous hawk and, rarely,
the golden-eagle.

     Dryland farming is generally practiced over large areas, with
minimal supervision.  The unharvested strips,  stubble and fallow from
these grainfields are an important winter food source for wildlife.
                                 E-23

-------
                Table  E-5.   PERTINENT  CHARACTERISTICS   OF  SELECTED SOILS  IN DRYLAND  FARMING IN ADAMS COUNTY
ro
Soil
series,
typeb
Ascalon.
sandy
loam
Platner,
loam

Stoneham,
loam

Truckton,
sandy
loam
Vona ,
loamy
sand
Map
sym-
bol
As


PI


St


Tt


Vi.


Depth
to
rock,
cmc
>150


>150


>150


>150


>150


Slope,
%
3
to
5
0
to
3
3
to
9
1
to
3
3
to
9
Clay
con-
tent,
%
very
low

mod-
erate

low


very
low

very
low

Cation
exchange
capacity!
meq per
100 g soil
very
low

low


low


very
low

very
low

Ptf*
6.6 to 7.8
7.9 to 9.0

6.6 to 7.3
7.9 to 8.0

7.4 to 7.8
7.9 to 8.4

6.6 to 7.8


6.6 to 8.4


Permea-
bility,
cms /hr
1.6
to
16
0.15
to
5.0
1.6
to
16
0.13
to
0.3
16
to
>20
Sludge application/reuse
Suita- Limi-
bility tation
moderate low CEC


moderate low CEC


low low CEC


low low pH


moderate low CEC


Management
needed
runoff
control




runoff
control

liming


runoff
control

           Basic soil characteristics were obtained from soil survey descriptions  and interpretations provided by the USSCS >
           Soil type refers to the texture of the surface of the typifying pedon.
          cl cm - 0.3937 in.
           The first value* refer to soil characteristic in the upper layers (top  15 to 50 cm)  and the second values refer to deeper layers.

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Noise

     Noise levels of dryland farming are similar to those discussed
in the section on noise under the heading Sod Farms, above.

Odor

     No particular odors are generally associated with dryland farms.
Only during the harvest is the subtle scent of crushed chaff barely
noticeable.

LOWRY BOMBING RANGE SLUDGE DISPOSAL
AREAS AND LANDFILL

     The Lowry Bombing Range is located 24 km [15 miles]  east of  Denver
in Arapahoe County.  The Metropolitan Denver Sewage Disposal District
No. 1 and the City and County of Denver are currently engaging in three
separate, although related, disposal operations on 810 hectares [2,000
acres] of the old bombing range, which is just to the west of the pres-
ent bombing range.  The site is bounded on the west by State Highway
30 and on the south by Airline Road, and falls within Sections 31 and
32, T.4S., R.65W. and Sections 4 and 6, T.5S., R.65W.  The locations
of the three operations are shown in Figure E-5.  Approximately 527 hec-
tares [1,300 acres] are currently being used for the land appliction
of dewatered sludge.  The City and County of Denver is utilizing  69
hectares [170 acres] in the western part of Section 6 as  a solid  waste
disposal dump.  In the eastern part of Section 4, approximately 145
hectares [360 acres] are being used for landfill operations  during the
winter.  These areas will be referred to as Sites A, B and C, respec-
tively.

     Site C is the winter disposal area where sludge is dumped when
the soil is frozen.  It is referred to as a deep incorporation area
because trenches are excavated and the sludge is dumped and  then cov-
ered up.  Upon completion of the operation, the site will be revege-
tated with native grasses.  The groundwater supply is being  monitored
to detect groundwater pollution.

     Site D, located south of Site C in the northeast part of Section  9,
T.4S., R.65W., is a completed winter landfill area that is being revege-
tated with native grasses.

Topography

     The elevation of this area ranges from 1,720 m to 1,785 m [5,650
ft to 5,850 ft].  The relief is subdued, consisting of gently rolling
hills and shallow valleys.  Murphy Creek and  several of its  tributaries
run from south to north through the western part of Site A.  Senac
Creek also runs from south to north, lying to the west of Site C and
                                E-25

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                                                    FIGURE E-5
     30 ,> -
   VER 24 km (15miles)
STATE HIGHWAY 3O
           TE    A
                   	          -IK
                                      •      .	^
                                     X / en  ^..^
                                   5"/  V  5"»>5--' X
                                                v-7 Sa
                                    SITE A - LAND APPLICATION
                                    SITE B - CITY AND COUNTY DUMP
                                    SITE C - LANDFILL
                                    SITE D - COMPLETED LANDFILL
                                             LOWRY
                                        BOMBING RANGE
                                        DISPOSAL  AREA
                      E-26

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to the east of Site A, and joins Coal Creek to the north of the prop-
erty.  Both creeks are dry most of the year, flowing only during per-
iods of stream runoff.  Associated with these watercourses are flat,
wide floodplains.

Soils

     Soil characteristics for this area are summarized in Table E-6,
and occurrence of the soils is shown on Figure E-6.  The particular
occurrence of lime layering in the soil profile is the most notable
property of these soils.  A layer of noncalcareous (acidic) surface
soil to a depth of from 30 to 60 cm [12 to 23 in.] overlies deeper,
highly calcareous (alkaline) materials.  This relatively uniform se-
quence has important implications for sludge application because of
the differential solubility of heavy metal compounds at various soil
reactions.

     Surface layers (to a depth of about 15 to 25 cm [6 to 10 in.]  are
also coarser (i.e., contain less clay) than are the deeper layers of
most soils in the area.  This usually gives rise to a corresponding
stratification in the cation exchange capacity of the soils.  Wind  and
water erosion hazards are generally severe on the Bombing Range, with
great dust clouds generated by trucks and automobiles, even in slow
winds.

     The Fondis and the Renohill soil series are the most extensive
soils in the study area, occurring on approximately 80 percent of the
total area, as shown in. Figure 13.  The Fondis series, which includes
the Fondis silt loam and the Fondis-Colby silt loam soil types, occu-
pies approximately 50 percent of Site A.  These are deep, well-drained
soils with a high water-holding capacity.  The surface layer of soil  is
15 to 17 cm [6 to 7 in.] thick and rests abruptly on the subsoil, which
consists of dense clay 46 to 51 cm  [18 to 20 in.] thick.  The Fondis
soils are high in natural fertility but are moderately susceptible to
water and wind erosion.  These soils are suited to native grasses and
cultivated crops.  Smaller units occur on Sites B and C.

     The Renohill series, which includes the Renohill-Buick loams and
the Renohill-Litle-Thedalund complex, occurs on approximately 30 percent
of Sites A and B, and on the majority of Site C.  These are moderately
deep, well-drained, gently sloping to steep soils that have moderately
slow to slow permeability and moderate water-holding capacity.  The
Renohill soils are moderate in natural fertility, but are  susceptible
to water and wind erosion.  These soils support native grass and are
unsuited to cultivation because of the shallowness of the  rooting  zone
and the severe hazard of erosion.
                                E-27

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Table E-6.  PERTINENT CHARACTERISTICS3 OF SOILS IN LOWRY BOMBING RANGE SLUDGE DISPOSAL SITES
Soil Map
series, s-w-
type bol
Buick, Bx
loam

Fondis, Fd
silt
loam
Fondis- Fo
Colby,
silt
loam
i
ro Renohill- Rh
00 Buick,
loam
Renohill- Rt
Litle-
Thedalund ,
complex
Nunn, 711
loam


Terry- Te
Olney-
Thedalund ,
sandy
loams
Weld- Wr
Deer trail,
silt
loam
Depth
to
rock,
cmc
120
to
180
>150


>150




50
to
100
50
to
100

>150



60
to
150


>150



Slope,
%
3
to
9
1
to
5
3
to
5


3
to
9
9
to
30

0
to
3

5
to
20


0
to
3

Clay
con-
tent?
%
low


low
high

low
high



moderate


moderate



moderate



very
low



low



Cation
exchange
capacity,
meq per
100 g soil
low


low
moderate
high
low
moderate-
high


moderate


moderate



moderate



very
low



low



PHd
6.8 to 8.0
8.0 to 9.0

6.4 to 7.5
7.5 to 9.0

6.4 to 7.5
7.5 to 9.0



7.5 to 8.5


7.5 to 8.5



6.5 to 7.0
7.5 to 8.5


6.8 to 7.5




6.5 to 9.0
8.0 to 9.0


Permea-
bility,
cms/hr
1.6
to
16
<1.6


<1.6




<1.6


<1.6



<1.6
1.6
to
16
1.6
to
16


<1.6
1.6
to
16
Sludge apjplication/disposal
Suita- Limi- Management
bility tation needed
moderate low CEC runoff
control

high — aubsoiling


high — subsoiling




moderate shallowness erosion
control

moderate shallowness erosion
control


high — erosion
control


moderate — erosion
control



moderate low CEC erosion
control



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                          Table E-6 (ccmtinued).   PERTINENT  CHARACTERISTICS3  OF SOILS
                                   IN LOWRY BOMBING  RANGE  SLUDGE DISPOSAL  SITES
*Ba»lC coll characteristics were obtained from soil survey descriptions and interpretations provided by the USSCS.
 Soil type refers to the texture of the surface of the typifying pedon.
el cm - 0.3937 in.
*The first values refer to soil characteristic in the upper layers (top IS to 50 cm) and the second values refer to deeper layers.

-------
        SOILS OF THE
  LOWRY BOMBING RANGE
  SLUDGE DISPOSAL AREAS
SOURCE US SOIL CONSERVATION SERVICE
                            RhD
                                       rn
                                      i 01

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Water

     Coal Creek, Senac Creek and Murphy Creek are ephemeral water
courses traversing the 850 ha [2,100 acre] disposal area at the Lowry
Bombing Range toward the north and northwest.  Groundxvater occurs both
in the alluvial material and in the underlying bedrock,  moving in a
northwest direction, similarly to the surface waters.  Shallow ground-
water, lying at a depth of about 18 to 30 m  [60 to 90 ft]  is of ade-
quate extent and yield to be used for some irrigation and/or domestic
purposes.  Deeper groundwater levels of the Laramie-Fox  Hills aquifer
lie at about 520 m [1,700 ft] from the ground surface (Reference 87).
This is an important regional aquifer, used principally  in the upstream
areas in eastern Arapahoe and Adams counties.  There are a number of
wells downstream, in Denver, tapping this aquifer.  In the immediate
vicinity of the Lowry Bombing Range disposal area, some  15 domestic
wells equipped with electrical or windmill-powered pumps are in active
use.  About 30 other observation and monitoring wells have been estab-
lished by the U.S. Geological Survey in cooperation with the Metropoli-
tan Denver Sewage Disposal District No. 1 to study impacts upon ground-
water quality.  Furthermore, the District maintains surveillance on
runoff and surface water quality by sampling and analysis  of waters in
six catch basins, two springs, two creek stations and two  wells.
Biology

     Vegetation—

     The vegetation of the bombing range can be described as being
characteristic of the Uplands Vegetation type.  It is primarily pasture
and range land that has been subject to grazing for many years.  While
the original vegetation was probably a short-grass prairie, heavy graz-
ing has changed it to a weedy grass type that contains annual grasses
and annual and perennial weeds along with the original perennial bunch-
grasses.  Good range management practices are needed to prevent over-
grazing and to control erosion, particularly on the Renohill soils.

     Site A has been subject to the land application of thousands of
tons of dewatered sludge since 1969.  The sludge is applied in alter-
nating strips of varying widths along 1-m [3-ft] elevation contours,
plowed under and planted with wheat and/or grasses, and subsequently
used for the grazing of 300 to 500 beef cattle.  This site will be used
by the City and County of Denver for solid waste disposal as soon as
current operations are completed on Site B.

     Most of the vegetation that has appeared on Site A can be charac-
terized as weedy species that are fast-growing colonizers of bare  soil.
                                 E-31

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Common sunflower, Russian thistle,  summer cypress and tumble pigweed
are almost ubiquitous, covering the belts of application with a swathe
of greenery that provides little food value to livestock.  The practice
of livestock grazing on this site has resulted in the almost total de-
-truction of the planted crops (milo, oats, wheat and sudan) since
cattle eat the succulent young shoots as soon as they reach a height
of 10 to 20 cm [4 to 8 in.].  Some grasses can be expected to appear
over time, although heavy grazing makes it difficult for them to be-
come established.

     Wildlife—

     Wildlife within the Lowry Bombing Range is characteristic of the
Uplands Vegetation unit.  The large expanses of rolling plains with low
vegetative cover favor small mammal species such as the prairie vole,
Ord kangaroo rat, pocket mouse, ground squirrel and jackrabbit.  These
rodents occupy varying ecological niches and occur sporadically through-
out the range area.  The openness of the plains area and relatively low
animal density contribute to several wide-ranging predator species such
as the red-tailed hawk, Swainson's hawk and coyote.  The thin stands of
cottonwood trees along the seasonal creek drainages in the area are
prime roosting areas for the predatory birds and for occasional golden
eagles.  Several reptiles may be found throughout this arid region, in-
cluding the bullsnake, prairie rattlesnake and central plains milksnake,
which prey primarily upon rodents.   Other reptiles, feeding upon in-
sects, are the horned lizard and sagebrush lizard.  Infrequent bluffs
and cliffs over river bottoms and eroded areas provide a specialized
habitat for the bank swallow and kingfisher, which utilize overhangs
ind vertical walls for nesting and  feeding.

Noise

     The countryside is generally noted for its vastness and quietude.
The main sources of noise pollution at the Lowry Bombing Range are the
roadways traversing the plains, farm equipment, solid waste processing
equipment at the landfill, sludge handling and transport vehicles and
aircraft.  Heavy equipment for solid waste and sludge handling probably
generates the greatest daily noise.  Military vehicles and aircraft also
cause disturbances, although infrequently.  However, the relatively low
density of the military reservation and its remoteness make all these
noise sources insignificant in the overall context.

Odor

     There are currently no significant odors originating at any of the
sites on the Lowry Bombing Range (Reference 88) .  There have been no
complaints since 1972, when the contractor had piled quantities of
sludge without plowing it under.  After public hearings in June 1972,

-------
the Metropolitan Denver Sewage Disposal District No,  1  revised methods
of land application, and current practices do not generate significant
odors.  Freshly applied sludge can be smelled only at very short  dis-
tances.
                                   E-33

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km

-------
     This Appendix contains examples of letters
of support for the Metro sludge recycling pro-
posal.  The letters were solicited by the Metro
District in order to obtain a semi-quantitative
estimate of the potential market for the sludge.
Many of the writers indicate a desire to have
the sludge available for their own uses.  This
Appendix is not intended to present representa-
tive samplings of opinion vis-a-vis the sludge
reuse concept.  An assessment of the public re-
actions to this concept is presented in Section
VIII.

-------
                           APPENDIX F

         ES OF APPROVAL FOR OR INTEREST IN THE  PROPOSED PROJECT

                          £V3OLYDF3[inU[V3 COCVJPANY
                        A DIVISION OF faPJ\ AL>  INC.
                             HENDERSON MINE
                                   Box 68
                           Empire, Colorado 80438
                               (303) 569-3221

                               July  25, 1975
Mr. William J. Martin
Director of Resource Recovery and Reuse
Metropolitan Denver Sewrge Disposal District No. 1
3100 East 60th Avenue
Commerce City, Colorado 80022

Dear Bill:

     This letter is basically to inform you that this year's
planting has gone very well.  The 300 dry-weight tons of
sewage you supplied for mine reclamation revegetation at  the
Urad mine has been spread on the 15 acres slated for seeding
this year, and the grass and trees are beginning to look  pretty
good.  The test plots planted last year are looking very  good
also, even with 18 consecutive  dry days in late June and  parly
July.

     Although the whole process is still somewhat in the  ex-
perimental stage, I can see no  reason why things shouldn't  go
pretty well as planned in tl 2 future.  The tentative schedule
for the future sewage needs is  as follows:

          Spring 1975           300 tons
          Fall 1975             300 tons
          Spring 1976           300 tons
          Fall 1976             650 tons
          Fall 1977             750 tons
          Fall 1978             750 tons
          Fall 1979             450 tons
          Fall 1980             350 tous

               TOTAL         3,850 tons
                                   F-l

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WJM                      July 25, 1975
     It is the sewage that is making the difference.  The sewage
Is pretty well the key to the whole operation of revegetating
the fragmented rock covering the mine, tailing.  We appreciate
everything you are doing to help us in this endeavor.

                               Sincerely,


                                ' f/C^A-14 "T- .  • 5x1
                               Larry F7 Brown, Ph.D.
                               Environmental Control Engineer

LFB:mb
                             F-2

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                                         f-iichael Dulacki
                                         65:S i.il:'c-u.-:e~: St.
                                         Denver, Colorado  80205
Metro Denver Sewage Disposal  Dist.   i'l
51CO £. 60th Avenue
Commerce City, Colorado     50022

Dear Sirs:

     I am writing this letter to   you  to tell you that  I endorse
the recycling of nuncipal  wastes  in general and that I endorse
your particular plan  of  recycling     Denv-er sewage sludge as a
fertiliser and soil conditioner.   The possibilities of this TDlan
are many; for one, the Denver Parks _-epartn-ent could use this
fertilizer for the city  parks.   -Another ercar.ole is the UGJ of
the fertilizer by private  citizens  for their own la ns and gardens
I hope you are successful  in  your  efforts to ir.plenent this plan.
                                          Sincerely yours,
                                  F-3

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                                         ATEO

                            IMP O R T E K S - EX P O HT E R_S

                      ORGANIC AND CHEMICAL FERTILIZER MATERIALS
TLAMTA                        .      _      .,
ORT SMITH                      ANIMAL FEEDING SUPPLEMENTS                  ULlPMONt
ORT WORTH                         f\   c      k4                       2I2-667-O2OO
ITTLE ROCK                         Ol LS. TATS AN O M EALS                      	
EW ORLEANS                                                           CA«Ll»DO«CS»
                                36O LEXINGTON AVENUE                    -BAKERBRO-

   	                  MX-TVV YOJili, JS1EAV YO RK 1O 012             TEC" V.o."!
AMBURG. WEST GERMANY                     -                                   323402
tN JOSE. COSTA RICA
                                          July  29,  1975
      Metropolitan Denver Sewage Disposal
      District No.  1
      Commerce City,  Colorado

      Gentlemen:

      We noticed  in the July 28th issue of the publication Air/Water
      Pollution Report, that you have been granted $76,029 to study
      the effect  of feeding to cattle, crops grown on sludge amended
      soils.  From our letterhead, you will see  that we are in the
      f-artilizer  and  feeding materials business,  and for many, many,
      years, we have  actively sold heat dried activated sewage sludge
      to the fertilizer industry.  Some of this  sludge finds its way
      on to pasture lands as part of a complete  mixed fertilizer„
      Consequently, we will be keenly interested in knowing the outcome
      of your study,  if this information could be made available to us.
      As a matter of  fact, we would like to know whether you are recovering
      and heat drying your sludge and whether you would be ?.n a position
      to offer us tonnage.  We are currently selling, nationally, the
      entire output of the Metropolitan Sanitary District of Chicago  for
      the people  who  have the contract with them and can handle additional
      supply.

      We look forward to the pleasure of hearing from you.
      JWR/nw                             /S. Wi  Reisack
                                                President
                                          Very  truly yours,
                BAKERBRO CENTROAM ERIC AN A S. A . COSTA RICA . NUTRITION PRODUCTS DIVISION'S KIPUL,
                DELPH.A . THE KA.NIT oms.ON. SAVANNAH . POULTRY BY.RRODUCTS^NC HANCEWU,^
                PRO-PAK CORPORATION. FERNAND.NA DCACH. FLORIDA . H. J. DAKCR fl, DRO  ' *-*"*"* V,THE

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The
  CITY of    -H
                                    10969 IRMA DRIVE
                                    NORTHGLENN, COLORADO 80233
(303)452-1941
                  Bill Martin
                  C/0 Metro Denver  Sewer
                  3100 E.  60th Avenue
                  Commerce City,  CO 80022

                       We  are extremely interested  in obtaining anarobically
                  digested stabilized  sludge  for  use on our parks and green-
                  ways.  We understand that this  material will be made avail-
                  able in  the near  future and would like to be contacted so
                  we can use this valuable resource.  We can use approximately
                  200 to 500 tons annually.
                       Could you  please send  me the Chemical analysis if the
                  material also,  what  method  will be used in transporting to
                  Northglenn.

                                              Thank you,
                                               (
                                             ATack DeBell
                                              Superintendent of Public Works
                                              City of Northglenn
                  JDB/cw
                                                   F-5
 office of the director of community works

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                   City of Commerce  City
                          4407 East 60th Avenue

                       Commerce City, Colorado 80022

                          TELEPHONE (303) 287-3485                       COMMUNITY
                                                             DEVELOPMENT
August 11, 1975
Mr. William J. Martin, Director
Resource Recovery & Reuse
Metropolitan Denver Sewage Disposal District #1
3100 East 60th Avenue
Commerce City, CO   80022

Dear Mr. Martin:

I am writing this letter pursuant  to  our  conversat-ion of Thursday,
August 7, 1975.

Ihe City of Commerce City has been strongly considering and hopes
at some future date using "sludge" as a fertilizer for both new park
development and park maintenance.  The City has approximately 40-
acres of developed park and open space which we are fertilizing
(commercial) a minimum of three times a year.   As well, we are
planning to construct between 10 and  15 additional acres each year
for the next four years in which we have  been applying manure for
topsoil development.

We would like to substitute your sludge in  both these instances.

Sinc^efely,
Dale W. Gilbert
Director of Community Development

th
                              F-6

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                                      August, 1971*
     TO I      THE METROPOLITAN DENVER  SEWAGE DISPOSAL DISTRICT NO. 1
            We,  the undersigned,  In  the  interests of minimizing environ-
     mental pollution and conserving  cur  resources,  wish to affirn our
     support for  the recycling of  nui.Icipal  wastes.   In particular, we
     strongly support efforts which would r.ake Euniciple wastes avail-
     able to the  public for use as an organic  fertilizer.
NAME                              ADDRESS                           ZIP
        This petition was signed by 461 persons,  primarily in the Metropolitan

        Denver area.
                                          F-7

-------
                            ^/"  r\
                             >;://        ff   ,» ,
                              / 7   s™-^ f  -\'& «
                              nl    jf  /U4-ILA
                               V^ fesU^i
                   COLORRDO ORGRN1C GROUERS'flNO naRKETERS'flSSOElM
                               DENfcR, COLORRDO 60211
Uthe Metropolitan Denver Sewage  Disposal District #1.

    V/e  the undersigned individuals, residents of Metropolitan Denver  com-
Ltted to the usage of natural fertilizers only and convinced that,  as
i^payers, we are entitled to stabilized,dry or semi-dried activated sludge
id concentrated anaerobic-produced sludge,  semi-dry or dried.
    Name
Address
land area
"ton 1/2 ton 1 ton
              This petition was signed by 15 persons who requested a total of 37 1/2

              tons of sludge.
                                    F-8

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mm

-------
     This Appendix comprises a reproduction of the
tabulation of the environmental evaluation ma-
trix used by the facilities planner (CH2M—HH1)
in selecting site B-2 from the three finalists
for a sludge drying and distribution site.  Even
though site B-2 has been selected by the plan-
ners as the most favorable location, nagging
problems remain with respect to neighborhood
acceptance and potential market proximity.  For
more information on the environmental, engineer-
ing and cost factors weighed in the process of
site selection refer to Reference 8 in Section IX
of the main body of the EIS.

-------
                                    CONSIDERATION

                                                   Overall tint} r,
                                                   Easaof Acquifit'G
                   CRITERIA

Are 2000 acies available*
                                                                                                                                                                                                                                 M due ID an enisling
                                                                                                                                                                          io be IBII tlfan the 1320 leei.


                                                                                                                                                                          •operty owners, including the        There art four property owners.
                                                                                                                                                                                                                                                                eKCBpl in* souiheast ana souin dti* to * natural
                                                                                                                                                                                                                                                                drainage course tnal exists tn I fie arM. Mow
                                                                                                                                                                                                                                                                Irondalc Road would toed to b* r«iocat«l t
                                                                                                                                                                                                                                                                expand to 111* saulti.

                                                                                                                                                                                                                                                                    i Irom ihe 116*1 m
                                                                                                       Where*ie me nMtnt "ij,ot *'len«il tuitJbie 'or       Bfomr.v L*nc twwyeiilfn ncnti tx>unoiry ol in>      HJCH Mount RcwO n the auio> norlh-ioutn           Irondale Road n the southern boundary to IhC

                                                                                                                                                          tnt'iegion w.lh po*i«d (p«eOi of 65 MPH. '   '         with ipe«H of 55 MPH.                   '          viiln a io«e of * potenlrji ouikel jiea sunourifling         of a potential mjfkel aiea lurroundi'iq Srignton.
                                                                                                                                                                                             lely IB miiet     Bri^nion. The in*ai»o lie* JOtwommjicly 10 miifli    This tile also lie* appioKimjicly 16 miles west
LAND USE
                                                                                                       Ate dower, «



                                                                                                                                                                                 1 land uwqe A a.
 SOU ANOCCOlOCV

-------
                SOIL AND GEOLOGY
                     (Continued)
 I
ro
                                                         CONSIDERATION
                                                                                                                                                                                                       features. Sludge inpcctmr
                                                                                                                                                                                                                                       Same ,iiSilc A.
                                                                                                                                                                                 Slope; on Ihe silc arc slight. No slides would be

                                                                                                                                                                                                                                       Nol  known at ll>.



                                                                                                                                                                                                                                                                                             SJITIU ,15 Situ A.
                                                                                                                                                                                                                        .in- [irctcnl    S.unc .n Silc; A.


                                                                                                                                                                                                                       ".If n          Sliniln ,)..(( \if.f, .iic not .iv.nl.ihlr:

-------
UttCCLLANCGUS
                                       CONSIDERATION
                                                                                                   Will in* DTQJCCl Cr«*IC
                                                                                                                                                                                                                                                      Virroundmg i«wdenc«t to* « 
-------
   APPENDIX H
DISTRIBUTION LIST

-------
                         DISTRIBUTION LIST

Federal Agencies

     Council on Environmental Quality
     Environmental Protection Agency
          Office of Federal Activities
          Office of Solid Waste Management Programs
          Office of Water Programs
          Office of Public Affairs
          Office of Legislation
          Dr. Joseph Parrel 1, NERC Cincinnati
          G. Kenneth Dotson, NERC Cincinnati
          Environmental Impact Coordinators,  Regions I-X
     U.S. Department of Agriculture
          Dr. Rufus Chaney, Agricultural  Research Service
          Dr. Elliot Epstein, Agricultural Research Service
          Forest Service, Region II
          Forest Service, James Evans, WO
          State Conservationist, Soil Conservation Service
     Food and Drug Administration, Dr. George  Braude
     Department of Interior
     Department of Health, Education & Welfare,  Regional  Director
     Department of Energy
     Army Corps of Engineers, Omaha District
     National Commission on Water Quality, Dr.  Harold Allen
     National Technical Information Service
     Department of Transportation
          Federal  Aviation Administration
     Department of Housing & Urban Development,  Regional  Director
     Department of Defense
          Commander, Rocky Mountain Arsenal
          Commander, Lowry Air Force Base
     Farmers Home Administration, State Director
     William Armstrong, U.S. House of Representatives
     Pat Schroeder, U.S. House of Representatives
     Floyd Haskell, U.S. Senator
     Gary Hart, U.S. Senator
     Jim Johnson,  U.S.  House of Representatives
     Dr.  Richard Hayes, Public Health Service,  Ft. Collins

State Government

     State Clearing House, Office of Planning
     Executive Secretary. Colorado Water Pollution Control Commission
     Colorado Department of Health
     Colorado Water Pollution Control Division
     Colorado Air Pollution Control Division
     Colorado Solid Waste Division
                          H-l

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     Colorado Department of Natural Resources
     Colorado State Land Use Commission
     Colorado State Department of Highways
     Colorado Wildlife Division
     Colorado State Water Conservation Board
     Colorado State Soil Conservation Board
     Office of the Governor
     State Historical  Society/State Archaeologist
     State Geological  Society

Regional,  County and Local  Governments

     Denver Regional Council of Governments
     Adams County Commissioners
     Adams County Planning Department
     Arapahoe County Planning Department
     Tri-County Health Department, Don Turk
     Larimer-Weld Planning Department
     City & County of Denver
          Planning Department
          Health Department
     Admas County Agricultural  Extension Service
     Denver Water Board
     City of Westminister
     City of Commerce City, Attn:   Mr. Dale Gilbert
     City of Bennett
     City of Brighton, Attn:  Mr.  Bill Sharp
     City of Prospect Valley
     Denver City Parks Department, Ron Maketric
     City of Aurora, Attn:   Mr.  Charles Wemlinger
     City of Thornton
     City of Northglen, Attn:  Mr. Jack Debill

Sanitation Districts

     Metropolitan Denver Sewage Disposal District #1
     City and County of Denver Wastewater Control  Division

Other Associations & Individuals

     Colorado Open Space Councel
     Rocky Mountain Center on Environment (ROMCOE)
     ECO-Center, Environmental  Clearinghouse
     Colorado Clean Water Action Project
     Sierra Club, Enos Mills Chapter, Jim Fowler
     Keep  Colorado Beautiful, Beverly Fleming
     Environmental Action,  Maury Wolfson
     League of Women Voters
     National Wildlife Federation
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Thorne Ecological Institute
The Denver Post
The Rocky Mountain News
Straight Creek Journal

Denver Public Library
Admas County Regional Library
University of Colorado Library
Colorado State University Library
Burlington Ditch Company

Larry Brown
Environmental Control Division
Climax Molybdenum Company
4704 Harlan
Denver, CO.

John J. Brehaney
RMP Company
100 West Walnut Street
Pasadena, California 91124

Jack Danford
1450 South Havana Street, Suite 340
Aurora, Colorado 80012

Mr. Bill Mathews
229 Pierce
Lakewood, Colo ado

Mr. Ray 01 in
No. 13487 Road 32
Platteville, Colorado

Dr. E. W. McCord
Northern Colorado Research Station
Greeley, Colorado

Mr. S. W. Maphis
Briscoe-Maphis, Inc.
Deep Six Division
2336 Pearl Street
Boulder, Colorado

Dr. Berne R.  Sabey
Department of Soils
Colorado State University
Fort Collins, Colorado
                      H-3

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Dr. James Smith
Department of Civil Engineering
Colorado State University
Fort Collins, Colorado

Reynolds Turf Farms
Post Office Box 595
Brighton, Colorado 80601

Dr. Duane Westphal
Great Western Sugar Company
Longmont, Colorado

Mr. Calvin Tupps, Adams County
Bob Ziegler, Adams County

Dr. Bernard Korbitz
Department of Medicine
Presbyterian Medical Center
Denver, Colorado

Jack Haines, Adams County
Robert Sandquist, Adams County

Dr. Edwin Bennett
Department of Environmental Engineering
University of Colorado

John Schwing, Jerry Boyle
Cornell, Hayes, Rowland & Merryfield-Hi 11 (CH2M-HILL)

Engineering-Science-, Inc.
Berkeley, California

Benedetti, Opperman & Martinez
1 Park Central

Ronald Warner, Bennett, CO

Catherine & Leroy Mundell, Bennett, CO

F.W. & Blanche Meyer, Bennett, CO

Clarence Smith, Commerce City, CO

Edith Marlott, Byers, CO

Brighton Adams County Standard
                      H-4

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The Brighton-Blade

Brighton Market-place

William Sharp, Brighton, CO

Donald B. Wailes, Strasburg, CO

John Mundell, Bennett, CO

Lawrence E. Wailes

Dasel E. Hallmark, PE & LS, Denver,  CO

Dr.  F. Robert McGregor, Denver, CO

Betty Mundell  Bennett, Kensington,  M.D.

John G. Kalcevic, Bennett, CO

John J. Sauter, Keenesburg, CO

Chris A. Wailes, President, Lost Creek Groundwater
   Management District, Keenesburg,  CO

John E. Meyer, Bennett, CO
                      H-5

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
  REPORT NO.
  EPA-908/5-78-001A
                                                            3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
  Final  EIS - Volume  I
  Metro  Denver Sludge Management Plan
                                5. REPORT DATE

                                    February  1978
                                6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
                                                            8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
  Engineering-Science,  Inc.
  600  Bancroft Way
  Berkeley, California  94710
                                                            10. PROGRAM ELEMENT NO.
                                11. CONTRACT/GRANT NO.

                                  68-01-3407
12. SPONSORING AGENCY NAME AND ADDRESS
  Environmental Protection  Agency
  Region  VIII
  1860  Lincoln Street
  Denver, Colorado  80295
                                13. TYPE OF REPORT AND PERIOD COVERED
                                 Final EIS
                                14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES

  Volume  I  of III Volumes;
Volume I-EIS; Volume  II-Issues & Resolution;
Volume  Ill-
      Summary
16. ABSTRACT
       This  is the final environmental impact statement  (EIS)  prepared by EPA for  the
  Metro Denver Sludge Management Plan.  The Metropolitan  Denver Sewage Disposal
  District #1  plan calls for  development of a pipeline and  drying/storage complex  some
  27 miles to  the east of  the Commerce City plant.  Up to 107  dry tons per day of
  anerobically digested sludge would be pumped to the drying  basins.  After drying and
  storage  of approximately a  year,  the dried sludge product would be sold or distributed
  for  a variety of uses.   It  is contemplated that municipal parks, irrigated farms,
  sod  farms  and home gardens  would  constitute the principal use areas.
      The  report describes the project, alternatives, environmental  impacts, and miti-
  gating measures.  The most  severe potential impact is  expected to be on the ground-
  water in the vicinity of the site.  Other impacts include added water consumption,
  odor problems, effects in the site area, effects in areas of use.   Recommendations
  are  made for basin lining,  control of uses, heavy metals  limits, etc.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.IDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Held/Group
 sludge;  ssVftiS semi-arid;  dried sludge;
 solids  recycling; groundwater impacts;
 basin lining;  EIS; final  EIS
                    Denver;  Colorado; 201;
                    facilities  plan
18. DISTRIBUTION STATEMENT
                   19. SECURITY CLASS (This Report)
                        unclassified
21. NO. OF PAGES
      395
           unl imi ted
                   20. SECURITY CLASS (This page)
                                              22. PRICE
EPA Form 2220-1 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE
                                                     *U.S. Government Printing Office: 1 9 7 8-7 8 2-3 80 , : 3 J Regions

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