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                            SUMMARY

                             DRAFT

                 ENVIRONMENTAL IMPACT STATEMENT

                              on

              MANAGEMENT PLAN FOR WASTEWATER  SLUDGE
       BY METROPOLITAN DENVER SEWAGE DISPOSAL  DISTRICT NO.  1
                       DENVER, COLORADO



                              by

              U.S.  ENVIRONMENTAL PROTECTION AGENCY

                      REGION VIII, DENVER



                            May 1976

              Approved by:    John A. Green
                             Regional  Administrator
                           Q£s&-
                           CONTENTS

                                                        Page

Why This E.I.S.?                                           1

The Problem and the  Plan                                    3

The Analysis in this E.I.S.                                 9

The Alternatives                                          11

Potential Impacts, Mitigative Measures,                     15
  Unavoidable Effects and Long-Term Implications

The Important Issues                                      20

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                                                           1601
WHY  THIS  E.I.S.?
      In 1969 a law of far-reaching significance for Federal  agencies
was passed by Congress.  This law, called-the National  Environmental
Policy Act (and referred to as NEPA), requires a Federal  agency to
take  account of and make known the environmental impacts  of any ma-
jor action it is about to undertake.  The agency must decide whether
a given action is a major one that will have a significant effect on
the environment.  The document that a Federal agency must prepare
on such a major action is called an environmental impact  statement
(the  EIS).

EPA and NEPA—the difference

     The Environmental Protection Agency (EPA) is responsible for
seeing to it that many of the environmental  laws passed by Congress
are put into effect; however, it is also one among many Federal
agencies which must also comply with NEPA in its own actions.   The
action EPA could take in this case is the approval of a plan by the
Metropolitan Denver Sewage Disposal District No. 1 or 'Met™1  to de-
sign and construct a sludge processing and disposal  system in Adams
County.

     Under the Federal Water Pollution Control Act Amendments of
1972  (Public Law 92-500), EPA is responsible for approving such
plans for water pollution control improvements of municipal  sewage
treatment systems.  As part of this law, Congress set aside  $18
billion for design and construction of facilities, which  EPA has
the responsibility for distributing.  Should this plan  be approved
for funding, 75 percent of the eligible portion of the  project
could be paid for with a Federal grant.

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     EPA decided that the  proposed Metro project involved signifi-
cant environmental  impacts,  and  therefore has written this environ-
mental impact statement.   The  National Environmental Policy Act re-
quires a thorough review of  the  EIS by other Federal agencies,
State agencies, local  governments and interested citizens.  The
idea is to get the  benefit of  expertise both of other agencies and
of citizens, as well  as tQ inform the public of what is about to
take place.  The EPA  must  carefully weigh the comments it receives
before any final action can  be taken.

     This version of  the EIS is  a draft for your consideration; a
final EIS will  be prepared and circulated after comments have been
received on the draft.  No action will be taken in approving this
facility plan until  thirty days  following the release of the final
EIS.

The Draft EIS

     The EIS outlines in detail  the proposed design of the project.
This includes the location,  alternatives to the project as a whole
or to parts of the  project,  and  the environmental effects of what
is planned, as well  as  the likely impacts of alternative options to
the plan.

     The discussion  of  environmental impacts includes both direct
and indirect impacts  to the  extent that they can be predicted.
NEPA requires disclosure of  impacts of an irreversible or long-
lasting nature.  A  very important feature of the impact statement
is its attempt to propose  ways to lessen the negative impacts
identified.  These  methods are known as "Mitigative Measures."
                            NERA
     It should be made clear that the  term  "environment," as used

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in the National Environmental  Policy Act,  is  very  broad;  it applies
to people and social institutions as well  as  the biological and
physical world.

The Facilities Plan

     Because of problems with  its present  sludge disposal system,
the Metro District has developed a plan  to dispose of  its sludge by
recycling it to the land.  Formally, the plan is called a facilities
plan under Public Law 92-500.   A mechanism for parcelling grant mon-
ies was developed whereby an applicant such as Metro,  after having
been given priority standing by the State, would develop  and  submit
a facilities plan.  This is known as STEP  I.   This plan must  meet
State water quality goals as well as the Congressionally  ordered
goals (viz., wherever possible, the nation's  streams would become
fishable and swimmable, maximum recycling  of  resources, etc.).  EPA
has also developed, in its construction  grant regulations, a  fairly
lengthy list of what other information must be presented  in a facil-
ities plan.  Among these requirements is an environmental assessment
that helps EPA to decide upon  the environmental importance of the
project.  It is only after EPA has fulfilled  its obligation under
the National Environmental Policy Act that STEP II funds  can  be
awarded for design.  After the State has approved  these design
plans, a STEP III construction grant can be made.


THE PROBLEM AND THE PLAN

     Metropolitan Denver Sewage Disposal District  No.  1  (Metro) pro-
vides sewage treatment for most of the Denver metropolitan area.
It is a District with 52 member sanitation districts in and around
Denver.  The main treatment plant is located  on the South Platte
River at Commerce City, as shown on Figure A.

What is Sludge?

     The Metro's (wastewater treatment)  facility must  dispose of on
the average over 100 dry tons  of sludge  per day.   Sludge  is the
mixture of water and solid materials found in sewage that is  re-
moved from wastewater in the process of  purifying  it.  Sludge con-
tains water, the organic matter of human wastes, paper, some  oils
and grease, traces of heavy metals and other  elements, and some
salts.  Sludge also contains those critical nutrients—nitrogen,
phosphate and potassium—in quantities similar to  commercial  fer-
tilizers.  Table A below indicates the relative amounts of these
three constituents in Metro sludge, other  natural  fertilizer
sources and commercial fertilizer.

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                                                                              METRO  DENVER
                                                                         EXISTING AND PROPOSED
                                 ^^ SLUDGE  MANAGEMENT FACILITIES

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    Table A.  CONCENTRATIONS OF MAJOR PLANT NUTRIENTS IN SLUDGE
                   AND OTHER FERTILIZER SOURCES

                      (percent of dry weight)
                  Total nitro-  Total  phosphoric  Acid-soluble po-
   Fertilizer	gen (N)	acid (P20s)      tassium (K20)
Metro digested
sludge
Ammonium sulfate
Anhydrous ammonia
Urea
Farm manure
Chicken manure
Cottonseed meal
3.0 to 4.0
20.5
82.0
38.0
1.2
4.1
7.0
2.3 to 3.4
-


1.2
3.7
2.5
0.7 to 1.4
-


1.2
2.3
1.5
Source:  Metro Denver District Sludge Management, Volume III,
         Table 7-2.
     Sludge produced in the course of the wastewater treatment pro-
cesses is collected in primary and secondary settling tanks  (clari-
fiers).  At the present time, Metro sludge is a mixture of primary
sludge (30 percent of the total) and secondary, waste-activated
sludge (58 percent of the total) from the Central  Plant plus pri-
mary digested sludge (12 percent of the total) from the City of
Denver's North Side plant.  Thus, the currently produced sludge is
composed of 88 percent undigested sludge.

     Raw primary sludge is that sludge which settles out when sew-
age is first brought into settling tanks at the Central Plant.
Waste-activated sludge is produced when the sewage is brought into
contact with air and microorganisms.  Much of the  original material
in the sewage is converted into a living cell mass by this process.
These two types of sludge are highly odorous and have a high energy
content.  In both types of sludge it is extremely  difficult  to sepa-
rate the solid matter from the water in the sludge.

     Anaerobically digested sludge is produced in  large, covered
tanks using self-sustaining, slow microbial combustion process that
reduces the energy content of primary and secondary waste-activated
sludge, as well as to break down the more complex, odorous com-
pounds in the sludge.  What is left is a relatively inert, dark

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 material, rich in nitrogen,  phosphate,  and  trace elements.  Anaer-
 obic digestion generally performs  in  short  time the natural break-
 down of complicated organic  material  that is  continually occurring
 in nature.

 Metro's Current Sludge Operation

      The District now handles  the  sludge produced at the two plants
 by first chemically treating it to reduce possible harmful bacteria
 and other organisms and to make it possible to remove greater
 amounts of water from the sludge.   The  sludge is "de-watered" and
 then hauled by truck to a part of  the Lowry Bombing Range area that
 is leased by the City and County of Denver  for solid waste dispos-
 al, shown on Figure A.   There, it  is  spread over the surface of
 the land and disc-plowed into the  topsoil after some air drying has
 taken place.

      Although this  method of disposal has shown some positive bene-
 fits (such as improved  forage for  cattle),  there are a number of
 outstanding problems with the present system:

      First, the  present sludge mixture  is not of the proper type
 for land recycling.   Metro must use large doses of lime and ferric
 chloride to disinfect the raw and  primary sludge, to control odors,
 and to dewater the  sludge.   This is expensive and adds large
 amounts  of chemicals (up to  30 percent  of the dry weight of the
 sludge)  to the soil, with no benefit.   Furthermore, odors from
 these sludges are difficult  to control.

      Second,  the amounts  of  sludge  now  spread on the Lowry Bombing
 Range are  great enough  to cause concern about eventual effects on
 the  groundwater.  The loading rates are excessive for the purpose
 of  using the  sludge's nutrients on  this kind of land in Denver's
 semi-arid  climate, given  the limited  area where sludge can now be
 spread.

      Third, Metro's  existing sludge treatment and disposal  system
 is nearing  its capacity  in some units.  Funds will  have to be
granted either to expand  the present system or to find another
alternative.

      Finally, the system  is expensive and highly energy-consuming.
Metro would like to  cut operating costs while at the same time try-
 ing to find a way to use  the nutrients and soil-building potential
of the sludge.

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Metro's Sludge Recycling Plans

     With the above problems in mind, Metro began  searching  for  a
method of disposing of its sludge in a way that it could  be  of use
on agricultural lands.  Metro originally proposed  a system of
spraying sludge on dryland fanning areas to the northeast of Denver
in Adams County.  The lands would have either been owned  outright
and farmed by Metro or leased back to local farmers.   This system,
however, was highly criticized by the local farming community be-
cause of the high loading rates suggested for dryland  farming.
Farmers were also not happy with the prospect of having Metro as
a governmental competitor in the farming business.  Fears were also
expressed about odors and the loss of land values  around  the site.

     The Metro District then reviewed its original plans  with its
engineering consultant, Cornell, Howland, Hayes, and Merryfield
and Hill (CH2M-Hill for short), and came up with a more flexible
plan for recycling sludge to the land.  Instead of getting into
the farming business itself, Metro now proposes in their  facilities
plan to build a drying, storage and distributing center in the same
general area it had proposed for the spraying/farming  operation.
After the sludge has been pumped and dried at the  site, the  sludge
could then be sold at some reasonable charge to metropolitan area
users.  The system would take advantage of plentiful solar heat  to
dry the sludge.

     Features of the Metro Proposal —

     Anaerobic Digesters—At the Metro Central Plant,  the system
would make use of new anaerobic digesters.  These  digesters  are  an
essential part of any land application plan for sludge.   They allow
sewage solid material to be fermented in an air-free environment
for a period of 22 days on the average, resulting  in a stabilized,
and relatively odor-free sludge.

     This product then, is the material that would be  pumped some
22 miles by pipeline to the drying/storage site.  At this time,
the only operating digesters in the Metro system are at the  Denver
Northside Plant about a mile upstream of the Central  Plant.   Its
sludge accounts for only a small percentage of Metro's total
sludge to be disposed of.  Metro is responsible for further  pro-
cessing and disposal of this sludge.  It may be of interest  to
note that at present, Metro is dewatering this sludge  separately
from the rest of Metro's sludge.  The Denver Parks Department
wishes to use this sludge on parklands, and Metro  is storing and
drying this sludge in a small area of the Lowry Bombing Range  for
use by the Parks Department.

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       Recently,  EPA gave  the Metro District a construction grant to
  build enough  anaerobic digesters to handle all of Metro's present
  and projected sludge  loads to 1985.  The grant was given with the
  understanding that EPA would not be committed to approval of any
  final  method  of disposal of the sludge.  It was expected that the
  anaerobic digesters would be-beneficial to the Metro system no mat-
  ter what type of final disposal was selected.  Some disposal alter-
  natives  (such as incineration) might operate better without diges-
  tion,  but enough options would still remain available for disposal
  to  permit such  a grant.  Thus, for all practical purposes, anaero-
  bic digestion of sludge must be considered a part of any future
  sludge handling plans.

      Sludge Transport—The liquid digested sludge would be pumped
  from the Central Plant through two pipelines, using two pumping
  stations (at  the Plant and midway), to the sludge drying, storage
  and  distribution center 22 miles east of the Central  Plant in
 Adams County.

      Sludge Drying,  Storage and  Distribution—Metro's proposed  sys-
 tem calls for a  site in western  Adams County in Range 64 West,
 Township 2 South,  comprising Sections 16 and 21  and the western
 halves of Sections 15  and 22.  This  site is  known as  B-2, as shown
 on Figure A.   Sludge would  be  air dried in unlined earthen basins
 for about six months.   Then it would be scraped  and stockpiled  for
 another six months prior to shipment for reuse.

      The site would  include 600  acres of drying  basins  within its
 total 2,000-acre area.   Two impoundments  are  planned  for  capturing
 all  surface runoff from  the site.  A smaller  area  would  be  used to
 stockpile the dried  sludge  on  the  land  surface.  A variety  of re-
 search and demonstration  plots would  surround the  drying  area,  as
 shown on  Figure  3 in the  body of the  EIS.  Metro also plans  to  use  the
 site for  emergency disposal of the dried  or  liquid sludge,  if neces-
 sary.

      Land Application  of  Sludge—The heart of the  proposal  is to
 provide Metro  dried sludge  to willing users in the entire metropoli-
 tan  area.  Metro has indicated that potential areas of use  include
 irrigated farms, dryland  farms, sod farms, Denver  parks and other
 metropolitan  parks, and mine spoil areas.  Metro has also received
 a considerable number of  letters from individual home owners who
 would like to  use the sludge on home gardens and lawns.  Other pos-
 sible candidates include a company interested in bagging and market-
 ing  dried sludge fortified with additional fertilizer nutrients.
 Another company  proposes to utilize sludge and garbage as a fuel
 source for a coal gasification plant.  To a great extent, the suc-
 cess  of Metro's  proposal will depend on the ability to develop a
market for the sludge.

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               AREA  IN FOREGROUND RECEIVED SLUDGE
THE  ANALYSIS  IN THIS E.I.S,


     The National Environmental Policy Act requires that an EIS
evaluate the following five items:  (1) the environmental  impact of
the action, (2) alternatives,   (3) adverse impacts that cannot be
mitigated, (4) irreversible and irretrievable committments and (5)
short-range versus long-term resource tradeoffs.  Because EPA has
been given the responsibility by Congress to develop overall  pol-
lution control approaches to wastewater treatment (including
sludge treatment and disposal), EPA is also very much interested
in seeing that the best possible methods are incorporated into
sludge processing and disposal  projects.  EPA has generally en-
dorsed the idea of recycling waste materials wherever it is cost-
effective and environmentally suitable.  This includes making
use of the nutrient and soil-building benefits in municipal
sludge.

     EPA is also aware of the myriad problem areas in applying this
general concept to a particular situation.  Denver's case, for ex-
ample, requires a close look at the peculiarities of climate, soils,
water availability, the groundwater situation, health effects, sys-
tem design and a host of other  factors.  All environmental areas--
biological, cultural and physical—must be considered and protected

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 in evaluating such a proposed system.  EPA considers impacts occur-
 ring  "offsite," that is, where the sludge will ultimately be applied,
 to be of critical importance.  Factors such as loading rates, the
 condition of the sludge, what the uses of the land are and how well
 control will be exercised over areas receiving the sludge are im-
 portant in  deciding the overall merit of the proposal.  The EIS is
 EPA'S tool  for evaluating these areas of concern on a site-specific
 level.

      In preparing this draft environmental impact statement, EPA
 hired an environmental consultant to help evaluate the project.
The work of the consultant, Engineering-Science,  was  closely man-
aged by the EPA Region VIII staff in the preparation  of the  EIS.
The consultant was charged with the following tasks:   (1)  to review
and evaluate the work done by the Metro District  and  its engineer-
ing consultant, CH2M-Hill, (2) to evaluate Metro's  tentative pro-
posals for use of the sludge in six areas—irrigated  farms,  dry-
land farms, sod farms, mine-spoil areas, parklands  and home  gar-
dens and (3) to develop its recommendations for any measures it
felt were needed to protect any and all environmental  areas.  The
environmental consultant evaluated the costs of 17  different sludge
treatment and disposal systems and compared them  for  environmental
and engineering tradeoffs.

     EPA specifically asked the consultant to evaluate the two
most likely alternatives to Metro's proposal:  continuation  of
the existing system at Lowry and the combination  of Metro's  sludge
                                10

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with a Denver solid waste recycling  system under study by the Denver
Regional Council  of Governments  (DRCOG).  The latter involved pos-
sible use of sludge with solid waste in the Denver area for sup-
plementary fuel or for production  of synthetic gas.
THE ALTERNATIVES
     The EIS considers both entirely  new  sludge treatment and dis-
posal systems as well  as options  within the  basic Metro plan, as
alternatives.  These subsystem options include changes in site
location, sizing, and drying-basin design.
                                n

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 Alternatives to the Overall  Metro Plan

      EPA first reviewed the  work that had  been done by others in de-
 veloping overall  system alternatives.  Metro  had considered three
 basic options in its 1972 Predesign  Study:  the present disposal
 system at Lowry, incineration,  and a form  of  land recycling using
 sludge spraying equipment.   CH2M-Hill performed a more detailed
 evaulation of sludge processing and  disposal  alternatives in Volume
 II of the facilities plan.   Eight systems were selected for detailed
 comparison, including the present system, the proposed drying/distri-
 bution method, composting, the  use of heat treatment technology and
 incineration.   Engineering-Science was asked  to evaluate combined
 solid waste-sludge  systems,  the eight facilities plan alternatives
 and additional  feasible systems.

      The solid waste-sludge  combination seemed promising at first,
 but the recent defeat in the State legislature of a bill to provide
 funding for such  a  system has made this option much less realistic.
 To a great extent,  the compatibility of the two wastes would depend
 on the system  eventually selected  by DRCOG.   For example, sludge
 would not fit  well  with the  use of solid wastes for supplemental
 fuel; however,  a  combination composting system could use sludge
 fairly well.

      CH2M-Hill  and  Engineering-Science both concluded that the
 Metro overall  proposal  was probably  the most  economical for Metro
 and likely the  best overall  system.  Engineering-Science's cost
 evaluation is  found in Appendix A  of the EIS.

      EPA  prepared its  own general  comparative evaluation, using
 environmental,  engineering and  economic criteria, for this EIS.
 This  evaluation,  presented in Section II and summarized in Table 2,
 includes  general  sludge disposal options; EPA feels that the ulti-
 mate  disposal choice  in the  overall  sludge processing system has
 the most  important  environmental implications.  EPA likewise con-
 cludes  from an  overall  standpoint  that the land recycling approach
 is generally preferable  to other alternatives, for the Metro
 situation.

      EPA decided that  two basic alternatives should be considered
 further and evaluated  in detail:  Metro's proposed system and the
 existing Lowry system.  The  latter must be considered further be-
 cause  it  is an ongoing  system, and future changes to the system
might make it more  economical and environmentally less damaging.
At present, there are  no Federal funds available for construction
of the proposed Metro  system.  Therefore, Metro might have to con-
tinue to use the Lowry area for a number of years.
                               12

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Alternatives to Portions of the Metro Plan

     The EIS evaluates possible alternatives within  these  two  sys-
tems.  In the Metro proposal, alternative sites for  the  sludge dry-
ing and distribution center were evaluated.   EPA reviewed  the  com-
parisons of 11 sites in a 1973 study developing the  agricultural
reuse program.  EPA also reviewed the evaluation of  three  sites se-
lected by Metro for more intensive consideration in  the  facilities
plan.  In Section II, a discussion of other suggested sites  is pre-
sented, including areas at the Lowry Bombing Range,  the  Rocky  Moun-
tain Arsenal and areas to the north of the South Platte  River.
Part of the assignment of Engineering-Science was to evaluate  the
site location from the standpoint of costs and energy requirements
for hauling sludge by truck to possible sludge reuse areas.

     It appears that the proposed site B-2 shown in  Figure A is a
reasonable choice for a sludge drying and distribution center.  No
one site appears to be completely favorable when all  factors (such
as nearness to markets, elevation, soils, nearness of human  habi-
tation, land values, etc.) are considered.  It is perhaps  more im-
portant, from an environmental viewpoint, to design  correctly  for
the site-specific conditions, whatever the site chosen.   It  is
somewhat distressing, however, that little soils and groundwater
information is available for proper evaluation of site differences
and impacts.

     Other subsystem alternatives considered for the Metro system
are:  digestion, conditioning, transportation of the sludge, drying
basin design, controls at land application sites and the sizing of
the system.  Anaerobic, mesophilic digestion appears to  be the only
realistic conditioning alternative at this point. Furthermore,
there appears to be little problem with the choice of pipeline
route or pipeline design selected.

     Design of the drying basins may need to be changed if a danger
to groundwater quality exists.  The design could also be modified
if salts are a problem or if longer drying times are needed.  Metro
will have to demonstrate that there will be no groundwater problem
with its proposal.

     In order to control the amounts of some heavy metals in the
sludge, Metro might be required to institute some control  over dis-
charges into the sewer system.  The most critical need for control
would likely involve discharges of cadmium into the  system.

     The question of who should be allowed to use the sludge will  be
an important one from a public health standpoint.  Either restric-
tions could be placed on the types of users, "or the  system design
                               13

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could be changed to produce a sludge so benign as to allow for the
whole range of possible users, without any potential health hazard.

     System Capacity--

     EPA considered a change in the design capacity of the project.
The project was originally designed for a growth rate considerably
greater than the present rate.  Furthermore, the sizing appears to
be out of line with DRCOG desirable population growth limits for the
metropolitan Denver region.  However, EPA has decided not to require
a change in the system capacity at this point, for two reasons:
(1) the greater capacity would be useful  for a longer period of time
and might be needed if longer drying and storage times became neces-
sary for pathogen reduction, and (2) the effect on secondary impacts
(air pollution and land use from new populations) is only very dis-
tantly related to sludge handling subsystems.  A more definite con-
trol can be put on the wastewater treatment facilities in their
drainage basin population sizing.

Lowry Disposal System Modification

     Alternatives to the present Lowry system are described in the
EIS.  Metro's new anaerobic digesters will change the type of sludge
being applied to the Bombing Range.  Some form of composting/drying
and storage could be instituted at Lowry to allow eventual reuse of
some or all of the sludge.  It is possible that more land could be
acquired at the Bombing Range to improve the soils and vegetation
without accumulating excess metals in the soils or nitrates in the
groundwater reservoir.
              SLUDGE APPLIED TO LOWRY BOMBING RANGE
                               14

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POTENTIAL IMPACTS,  MITIGATING  MEASURES,
UNAVOIDABLE EFFECTS AND LONG-TERM IMPLICATIONS
     The evaluation of environmental impacts is carried out in this
EIS in the following way.  A  description of potential positive and
negative impacts from the  proposed Metro system is provided.  Wher-
ever possible, impacts are quantified with reasonable basic assump-
tions regarding the system and prevailing conditions.  Where quanti-
fication is difficult due  to  lack of basic data or an imprecise
state of knowledge, ranges of possible impacts or qualitative state-
ments of impacts are made. In all cases, thresholds of significance
for impacts are determined from the experience of the professionals
on the environmental team  and from knowledge of local conditions.

     Mitigative measures are  developed for reducing the severity of
impacts.  Section VII is devoted to a listing of negative or adverse
effects that cannot be avoided and of the long-term implications of
the proposal.

     The EIS looks at three basic areas in analyzing the environmen-
tal impacts:  Metro's proposed system, including digesters, pipeline,
site and drying/processing/storage facilities; off-site areas where
the sludge is likely to be applied; and the part of the Lowry Bomb-
ing Range containing the existing Metro sludge processing system.
Schematic representations  of  impacts In these three basic areas of
concern are presented in Figures 16, 17 and 18 in the main text.

     Table B provides a rough summary of the major impacts expected
from the proposed Metro system and the existing Lowry operation, di-
vided into the same three  basic areas.  This table also summarizes
possible mitigating measures  and those adverse effects that cannot
be lessened.
                                15

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Table
Environmental
parameter
Soil/land
Groundwater
Water quantities
Air quality
Public health
Energy use
Nutrient resources
Food chain
Public health
Water quality
Soil productivity
Soil salinity
B. SUMMARY OF MAJOR POTENTIAL IMPACTS, MITIGATION MEASURES AND UNAVOIDABLE EFFECTS
lapact
Destruction of profile
Nitrate and salt con-
tamination
Removal from South Platte
Odor generation; particu-
lates
Pathogen survival and
vector proliferation;
airborne particles
beneficial
beneficial
Magnification of heavy
metals, especially
cadmium
Pathogen survival, es-
pecially Ascari*
Nitrate apd salt concen-
tration
beneficial
adverse
Icpor-
tance
moderate
high
minor
negligible
high
moderate
high
high
high
high
high
moderate

Severity Feasi-
of inp.ict bility
Sludge Dryins, Storage and Distribution Site
Confined to site, -
severe
Potentially severe +
moderate P
Negligible except P
with digester up-
set; particulars
in severe wind
Low, except with +
loss of control
NA
NA
Sludge Application Areas
Low under strict •*•
controls
Low on sod farms, +
high on hone jar-
dcns
Minor on drylands,
severe on others
NA
High on dryland
farms only
Mitigation3
Methods
NA
(1) Lino basins; (2) Renove
decant; (3) Collect drain-
age; '4) Promote anaerobic
conditions
(1) Avoid irrigation;
(2) Return water
(1) Bury sour digester con-
tents elsewhere; (2) Keep
stockpiles moist
(1) Medical attention;
(2) Insect control
NA
NA
(1) Limit sites, crops,
users, rates; (2) Control
heavy -i^tals at source
(1) Restrict use of sludge;
(2) Longer drying, storage;
(3) Medical attention
NA
NA
NA
Unavoidable
effects8
Elimination of agriculture
in the site; destruction of
wildlife habitat
Mitigation will increase
project cost

Minor odors on calm days;
sone particulate dispersal
in severe winds
none
NA
NA
Heavy metals contamination
in soils; exposure of bur-
rowing animals to toxic
elements
Possible mismanagement of
the sludge reuse
Long-term cumulative ef-
fect in entire region
NA
Long-term cumulative ef-
fect in dry farms

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Plant nutrition

Energy use
       beneficial

Fuel requirement for
trucking
moderate

moderate
                Lover than present
                operations
                            NA                     NA

                            +           Develop  markets  in vicinity
                                        of  site
                                              NA
                                                                                                                                                   Moderate fuel consumption
                                                                      Lowry Bombing Range Existing Operations
Food chain



Public health



Soil productivity

Soil salinity
Domestic anlnals grazing
on sludge-amended fields
Exposure of people in
parks and hone gardens
to pathogens

       beneficial

Salt buildup in root
zone
  high
potentially severe
Groundwater quality     Nitrate pollution, salt
                        increase
Air quality
Energy
Chemicals resources
                        Odors
Use of large amounts of
fuel for transport
                        Use of conditioning chem-
                        icals (ferric chloride
                        and line)
very high       potentially severe
  low

moderate




  high


  low




moderate



moderate
     moderate
                                                 Low to potentially
                                                 severe

                                                 Low except with
                                                 digester upsets
                                                                                high
                                                        high
                            NA

                            P
(1) Restrict grazing;
(2) Control heavy metals at
source

(1) Longer drying tine;
(2) Medical attention
            NA

(1) Remove decant,
(2) Spread over larger
areas and lower the load-
ing rates

            NA
                                        (1)  Source control of toxic
                                        materials; (2) Optimal oper-
                                        ation of digesters;  (3) Bur-
                                        ial  of  sour digester sludge

                                        (1)  Use of anaerobic sludge
                                        reduces total load, produces
                                        gas

                                        Use  of  anaerobic digesters
                                                                                          Heavy metals accumulation
                                                                                          in soils
            NA

Gradual salt buildup in
the region
                                  Groundwater pollution In
                                  irrigated farms

                                  Complaints from neighbor-
                                  ing areas
                                  Loss of energy; resources
                                  wasted
 "The symbol + indicates totally feasible;  - Indicates  infeasible; P  indicates feasible in part; NA indicates not applicable.

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  Sludge Drying and Distribution Site

      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.  Other impacts will  occur to downstream water
  users because of increased consumption of water; minor impacts will
  also be felt from occasional odors.  Very little mitigation of the
  soil destruction is possible; groundwater effects and exposure of
  the public to pathogens can be controlled with proper measures as
  shown in Table B.

  Land application Areas

      Land application areas hold both the greatest promise for bene-
 fits as well  as the greatest amount of potential detrimental  impact
 from sludge application.   On the positive side,  the Metro proposal
 would lessen  overall  energy use^-in comparison with commercial  fer-
 tilizers,  which require energy for their  production—by taking  ad-
 vantage of solar heat in  the drying process.   A  beneficial  effect
 is expected on the soil  structure and  moisture-holding  capacity of
 the soil  as a  result  of sludge application.   Properly applied,  the
 nutrients  in  sludge can replace commercial fertilizers.   Sludge ni-
 trogen  is  also of the slow-release form that  would  be available to
 plants  over a  number  of years,  somewhat in harmony  with plant  needs.

      The principal  negative features of the application of  sludge
 on farms and gardens  are  keyed  to  the  specific kind of  land use in-
 volved.  Dryland  farms  have different  (lower) requirements for
 amounts of nutrients  and  sludge from those of  irrigated  areas.  Ex-
 posure to pathogens will differ greatly, depending on whether sludge
 is applied to  farmland or to city  parks and home gardens.

     The principal areas of concern in applying  sludge  to lands on
 which various  kinds of crops for human use are grown would be:  nu-
 trient loadings, toxic or plant-inhibiting effects of heavy metals,
 salt accumulation in the soil profile and food-chain effects (the
 gradual  buildup of trace elements  in plants and animals or in humans
 consuming the plants and specific organs of the animals).  Other
 concerns involve effects on groundwater and runoff effects on water
 quality.  The latter are not considered very significant overall be-
cause of the projected recommended loading rates considered for this
 semi-arid area.

     Each of the above problem areas can be mitigated to a large ex-
tent, either by controlling how much sludge is applied and where it
is applied  or  by source control of heavy metals and greater treat-
                               18

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ment at the Metro facility.  Such measures  will  require  greater man-
agerial control by the Metro District as to the  final  disposition  of
sludge.  Currently, legislation is pending  in the  State  of Colorado
to remove sewage sludge from the category of solid waste and,  pre-
sumably, to set up a new statute or bring sludge application  into
closer harmony with existing public health  laws.  This,  in turn,
would mean that the State Health Department could  establish regula-
tions defining where and how sludge could be applied  to  the land.

     In the present EIS, EPA has provided recommended measures for
minimizing the environmental impacts of the use  of sludge on  land
areas.  A set of recommendations is presented in Section VI of the
EIS.

Disposal Operations at Lowry Bombing Range

     The impacts associated with the continued use of the existing
system, including final disposal of sludge  at the  Lowry  Bombing
Range, must be considered generally negative at  this  point.   The
existing system uses considerably more energy and  chemicals than
would be required with the Metro proposal.   Little agricultural pro-
ductivity, except for grazing forage, is now derived  from Lowry
rangelands.   At the present rates of application,  there  could be
discernible effects on groundwater quality  around  the landspreading
area in the future, and heavy metals will accumulate  in  the soils.
Since cattle grazing is the chief use of Lowry lands, possible toxic
chemical buildup in cattle tissues will have to  be monitored. A
study is underway at present, funded by the U.S. Food and Drug Admin-
istration, to determine what heavy metals buildups are taking place
in cattle now grazing on the sludge application  areas.  Cattle are
known to ingest a substantial amount of soil as  part  of  their diet.

     Mitigation of some of these impacts at Lowry  could  be achieved
by spreading the sludge over larger areas of the Bombing Range.  The
use of anaerobic digesters could also produce a  better sludge, which
could be stockpiled at Lowry and distributed to  farmers, thus lessen-
ing the burden on the soil of the Bombing Range.

Long-Term Implications

     The Metro proposal offers an opportunity to increase the use
of renewable resources as well as to lessen the  use of non-renew-
able materials.  The extensive use of chemicals  can be eliminated.
The sludge drying and distribution proposal will lessen  Metro's
consumption of dwindling fossil fuels; reuse of  nutrients would also
lessen the amount of fossil fuel needed to  produce these fertil-
izers.  Soil productivity could be improved by recycling carbona-
ceous material to the soil.  Solar energy would  replace  the fossil
                                19

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  fuel  energy  needed to dry the sludge.  Additional gas from the
  anaerobic digestion process would also substitute for commercial
  fuels at the Metro plant.

       Long-term uses of heavy metals in sludge on soils are not ex-
  pected to significantly deteriorate soil quality if the conserva-
  tive application rates are followed.  Some metals could be bene-
  ficial as micro-nutrients to crops.


  THE IMPORTANT  ISSUES


      This section of the Summary Document is an  attempt to bring
  into focus what EPA considers to be the most important issues  sur-
  rounding the Metro project at the time of the writing of the draft
  EIS.  Some of the issues have arisen from people's reactions to
 the Metro agricultural  reuse proposal; other issues were identified
 in the course of  the analytical  process in the EIS.  Some are  tech-
 nical  issues while others  represent potential  value judgments  in
 the political process.

     The EIS process  has thus far served to sharpen the focus  and
 put into perspective  the relative severity of  impacts that give
 rise to  these issues.  The Draft EIS points out where additional
 basic  data  are  needed and  where  the need for intensive monitoring
 is most  critical  for  continuous  safeguarding of the environment.
 The continuous  need for  specialized expertise  in  the various dis-
 ciplines  of  soil  science,  entomology,  public health medicine, en-
 gineering, etc.,  in the  proposed  project  cannot be  overemphasized.

     EPA  expects  to resolve  these issues  in the course of the EIS
 process.  The final EIS will make specific  recommendations  on the
 following issues  (or any other issues  raised in public and  agency
 review and comment) that will become a  part of the  grant  require-
 ments.  The  issues below are  listed as  they appear  in  the  evalua-
 tion of environmental impacts; the order  in which they are  listed
 does not necessarily reflect the  importance  of the  issues.

 Source Control of Trace Elements  in Sludge

          Will heavy metals affect crop growthf soil  pro-
     ductivity and/or the food chain?   Should Metro  insti-
     tute source control  of .cadmium, since ttie cadmium/zinc
     concentration ratio is  in excess of the recommended 0.01?

     The general heavy metals effect at the recommended sludge  ap-
plication rates for dryland and irrigated croplands  is expected to
be small.  A comprehensive discussion of this issue  is provided in
Appendix D of the  EIS.
                               20

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     Cadmium has been identified as a  special  problem  because of
its known toxic effects in humans (kidney damage  and hypertension).
Although the absolute concentrations of cadmium are lower than  in
many large metropolitan area municipal  sludges, the Cd:Zn concen-
tration ratio is relatively high (0.017) compared with recommended
levels variously set at 0.005 and 0.01.  The calcareous nature  of
soils in the Denver region makes heavy metals less available for
plant uptake and may somewhat compensate for this high concentra-
tion ratio.

     A very effective method of control of the heavy metals (cad-
mium in particular) would be for Metro and its member  districts
to survey industrial sources of cadmium, such as  electroplating
firms, and to impose pre-treatment requirements on their discharges.


Sludge Drying and Distribution Site Selection

          Should Metro  look for another site for  its  drying/
    distribution site?

    This is an extremely controversial issue that cannot be de-
cided solely upon technical grounds.  CH2M-Hill  has  established
that the present site is a reasonable choice, although it is  not
an optimum site by any means.  Metro has stated  that  its overwhelm-
ing concern is to place the site as far away as  possible from
human habitation.  This site was selected even though it had  ob-
vious disadvantages, one being its distance from potential  irri-
gated farm markets and the  Central  Plant.

    EPA has experienced in its construction grants program that
site locations are always controversial.  All other things being
equal, no one wants a sewage treatment plant located  close to them.

    EPA further evaluated through its consultant the  relative
benefits and costs of having the site located so far  from its po-
tential markets.  Using the nitrogen fertilizer value in the
sludge as a sole criterion, it appears that up to distances of
50 to 70 miles, the value of the nutrients in the sludge exceeds
the cost of truck-hauling the sludge.   Whether a potential  sludge
user would realize the same economics is another matter.

    EPA has raised other site possibilities such as the Rocky
Mountain Arsenal or the Lowry Bombing Range, because  some people
have expressed interest in knowing whether these sites would  be
better.  At this point in time, this issue is still  unresolved.
                                21

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 Lining of the Drying Basins

          Will nitrate concentration and  salt buildup  in  the
     qroundwater below the drying site be a  problem?   Should
     Metro be required to line the drying basins  or use some
     other technique to prevent groundwater  contamination?

     Indications are that a substantial part of the total nitrogen
 available in the sludge may be converted to nitrate.  In this
 highly soluble form, nitrates could move easily  toward the ground-
 water.
      The  exact  amount  of nitrate reaching the groundwater must be
 considered  an unknown  at this  point.  In an anaerobic environment
 as  could  occur  at  the  bottom of the drying basins, nitrate is
 converted to nitrogen  gas, which is itself harmless.  Nitrate in
 groundwater is  a public  health hazard, since high concentrations
 of  nitrate  are  linked  to methemoglobinemia in infants.

      Metro  liquid  sludge presently contains a high concentration
 of  soluble  salts.  Under present design conditions, a highly con-
 centrated salt  solution  would move unrestrained toward the ground-
 water table.

      Mitigation for nitrates and other salts could easily be ac-
 complished  by lining the  600 acres of drying basins, but this
 would be  very expensive.  A system of vacuum filtration and
 decanting liquid from the pumped sludge could be installed at
 the drying  site that would also be very expensive.  The decant
 would have  to be stored and treated.  Metro has suggested pumping
 the groundwater if a problem were discovered, but this will  not
 be a  reliable way of handling the problem.  The pumped water would
 in turn need proper disposal.

      For the present, EPA will  require Metro to develop a research
 site under conditions similar to the operation expected at the
 site.  Nitrate and other  s.alts concentrations will then be mon-
 itored to determine the seriousness of the problem.   Only if Metro
can conclusively demonstrate that the nitrate has been converted
to nitrogen gas and that other salts do not pose a serious prob-
lem under all  operating conditions will  the original  proposal be
approved.
                               22

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Reduction of Pathogenic Organisms

          Should Metro dry and store the sludge  for  longer
     periods of time (than the six months drying, one year
     total storage now stipulated) to adequately overcome
     pathogen survival?

     Although many pathogenic organisms  have  fairly  short life-
spans in dried sludge, some organisms such as Ascaris can live
for two years or more.  To a great extent, this  issue should be
decided by the type of land to which sludge is applied.  If
individual homeowners are to be allowed  to use the sludge, a
longer storage time (up to three years)  may be needed.

Use Restriction of the Sludge

         Should Metro place restrictions on the  use  of  the
    dried sludge, especially where parklands  and individual
    home users are concerned?  What crops should be  restricted?

    This EIS argues that environmental impacts will  be  felt  dif-
ferentially from the use of sludge at different  application  sites.
Given Metro's proposal for sludge drying and  storage, pathogens
can be reduced but cannot be eliminated  entirely.  Home gardens
growing leafy vegetables will be particularly vulnerable to  con-
tamination by pathogens.  People eating  these vegetables would
run the risk of disease.  Direct contamination could occur  in
parklands if people were to use grass areas that had been treated
with sludge.

    Depending on the results of the study underway to determine
the amounts of heavy metals uptake by cattle  at  Lowry,  it may
become advisable to restrict sludge applications or  restrict
cattle grazing where sludge is applied.   Certain crops  are  also
susceptible to heavy metal uptake.  Swiss chard, lettuce,  spinach
and sugar beets are among the most efficient  accumulators of
heavy metals.  By contrast, the use of sludge on sod farms  and
certain irrigated and dry farm lands may pose fewer  problems.

     EPA feels that these differences should  be  taken  into  account
in developing markets for future use of the sludge.   Eventually,
the State of Colorado will have to set such limits through  its
regulations on sludge use.  The final EIS will  develop recommenda-
tions and require Metro to develop its own guidelines  as to best
areas for sludge use as well as what areas should be restricted.
                                23

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 Control and Surveillance over Sludge Users

          Once sludge has been sold  to the ultimate  user,
     should Metro or another responsible  agency control
     the manner and rate of  appl ication?

     Application of sludge to various soils  and crops, under dif-
 ferent management conditions, requires a sophistication of ap-
 proach that is somewhat more than that required for use of com-
 mercial fertilizers and farm manures.  Furthermore, some of the
 negative impacts transcend  the boundaries of the farm area on
 which the sludge is applied.   Hence, land application of sludge
 by individuals becomes  a public concern  and may need to be regu-
 lated by appropriate public agencies,  such  as public health de-
 partments.   It may be necessary to  obtain binding agreements with
 users, delineating precise  manners  of use,  annual rate limitations,
 time  of cessation of use, field  re-entry periods, crop use limi-
 tations in  succeeding years,  etc.  Such agreement would best in-
 clude provisions  for field  inspection, monitoring, additional
 management  practices and amendments, and termination conditions.

      Present  State of Colorado statutory and regulatory provisions
 may not be  adequate to  ensure good control over the sludge applica-
 tions.   There are changes being  proposed to the State Solid Waste
 Act and new regulations  being initiated dealing with sludge appli-
 cations that  may  improve State control over this area.

 Control  of  Salt Accumulation

          Will soluble  salt  loadings from the sludge buildup
      in the soil  inhibit plant growth  in the sludge applica-
      tion areas?

      Salt contamination of western soils is a common problem.
 Gradual  buildups  of  salts in the soil profile can inhibit plant
 growth.  Sensitivity  to salts varies with the kind of crop grown.
 Sugar  beets and citrus crops are especially sensitive, corn mod-
 erately so and grasses very salt-resistent.

     Metro has reported that the salt content of the sludge was
measured at about 6,000 ppm.  However, the most critical  con-
 stituents, sodium and chloride, accounted for only about five
 percent of the total dissolved salts (IDS).   Data on concentra-
tions of other cations and anions is lacking; however, it would
 not be unreasonable to expect that much of the salts are of the
calcareous, alkaline  earth kind, with some sulfate.   These salts
are generally less of a  problem than sodium and chloride.   EPA
will  require Metro to provide a more complete cetion and anion
analysis for the sludge   stream expectec1  at  the drying site.
                               24

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     Mitigation would be best accomplished for soluble  salt re-
moval by separating the decant from the heavier sludge, if
necessary.  Irrigated land application of sludge might  not be
a problem if sufficient water is applied to flush  the salts through
the soil profile.

Air Pollution Abatement

          Could airborne sludge from the sludge drying  and
     distribution center create health problems around  the
     site?

     The possibility exists that pathogens could be transmitted
through the air.  This statement is made mostly because of the
lack of any definite evidence to the contrary.  The studies that
have been performed on workers at sewage treatment plants does
not indicate any greater health risk than for the  general popula-
tion.  Metro's sludge will also have undergone anaerobic digestion
that greatly reduces the number of pathogens in sludge. The distance
from human habitation is also a factor that would  minimize this
problem.  However, the exposed nature of the proposed stockpile
windrows makes aerosol and particulate matter blowing a problem
during the more severe windy conditions.  Metro will be required
to develop a contingency plan to protect against fugitive dust
leaving the stockpile areas during high wind conditions.

 Odor Problems  and  Land  Values

          Will  the  proposed  Metro  system of  drying  sludge at
     Site B-2  create odor  problems?   What effect will it have
     on  the  value of adjacent lands?

     This is a controversial  issue that cannot be  decided solely on
 technical grounds.   Sludge  has been  processed by  anaerobic diges-
 tion for most of this century and is known to be  much  less odorous
 than raw or activated sludge from municipal  treatment  plants.
 This is not to say that some persons might not find the odor un-
 desirable.  The B-2 site  location offers a buffer from human habi-
 tation  that would  make any  odors  difficult to detect.   Calm in-
 version conditions might  occasionally allow odors to carry offsite,
 but this would occur infrequently.   Upset of the  anaerobic di-
 gesters that  can happen occasionally would create a much more
 odorous sludge. Metro will  have  to  develop a contingency plan
 before  the  final  EIS is issued, showing how they  will  handle this
 situation.  A comparison  is fortunately available from actually
 operating digesters at the  Denver Northside Plant that could tell
 how often such a situation  might  occur and what is done under these
 conditions.  The Northside  plant  is  an exceptionally good example
                                25

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 because  it  receives the  bulk of the industrial discharges in the
 metropolitan Denver system.  Slugs of heavy metal discharges are
 generally the cause of disruption of the anaerobic digestion pro-
 cess.

    The  effect on land values is unclear.  Since the lands around
 the B-2  site are mostly dryland farms, little or no change would
 be expected in their present farm value.  Such land would be less
 valuable for sale for housing developments or other urban uses.
 If County, Regional, local or state planners are interested in
 preserving areas around the metropolitan region for open space,
 this use would be quite compatible with such goals.  Adams County
 is considering the development of a regional airport in the future,
 possibly located near the B-2 site in Range 65 West.  The large
 open space afforded by this drying site could be useful as a safe
 "clear zone" for airplanes landing and taking off at such an airport.

    Finally, if the Metro distribution center were to become a
financial success and if sludge application on dryland farms proves
feasible, nearness of such farms to the distribution center could
be an advantage.

 Continuation of Landspreading of Sludge at Lowry

          Could Metro use the existing sludge treatment
     and disposal system at Lowry without having to de-
     velop a new system?

     EPA has presented briefly some possibilities for an improved
 sludge disposal and perhaps utilization approach that could be de-
veloped at Lowry.  This will depend on a number of very uncertain
factors:   how the treatment system will operate with the new
anaerobic digesters, whether more land could be acquired at Lowry,
and whether Federal  construction grant funds become available for
the proposed Metro project.

     The EIS has tentatively concluded that the overall Lowry sys-
 tem is not as environmentally desirable a system as the agricul-
 tural reuse plan, especially as the Lowry system is now operated.
 Whether  it is worth the investment of some $18 to $22 million of
 Federal funds to achieve this improvement is a difficult question
 to answer, especially where Federal funding for water quality im-
 provements is limited.

     Metro will have to explore further other possible ways to
make use of the present Lowry-based system, at least for the near
future.  The present system may be needed for a number of years
if Federal  funds are not available, if litigation holds up the
funding process, or if EPA does not approve the proposal.
                               26

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          Should EPA even consider approval  of the  Metro land
     recycling proposal in the event that Metro is  not able
     to demonstrate that a users market will  be available for
     the dried sludge?  Could Metro use site B-2 for disposal?

     This is an extremely complex question to answer that depends
upon many factors.  With a pioneering project of this kind,  it  may
not be completely possible to evaluate the full market potential
for the use of sludge until some time after the project has  been
in existence.  Strictly from an economic perspective, the value of
sludge will depend on how farmers and other potential users  per-
ceive the value of the sludge, efforts by the Metro District to
familiarize and convince potential users about the  benefits  of  the
sludge, and the rates Metro will charge for the product.  State
regulations could also affect the extent to which various users
could apply the sludge.  Research and demonstration efforts, which
can only be done over an extended period of time, may be necessary
to convince potential users about the value of sludge.

     EPA recognizes that there is a certain amount  of risk involved
in terms of the "success" of the project.  The Agency can evaluate
the technical merits of the proposal as it has done in this  EIS,
make recommendations, and see to it that certain procedures  are
followed.  It cannot, however, guarantee that the project will  be
a success.  Many other public institutions and private individuals
will have a hand in its success or failure.

     It is possible for Metro to operate the drying/distribution
operation for some period of time before any distribution will  be
required.  The size of the proposed site offers a great deal of
flexibility in storing stockpiled sludge for greater amounts of
time than currently proposed (six months).  Metro has indicated
in its facility plan that some sludge could be buried on-site if
necessary for disposal purposes.  Metro could also itself haul
dried sludge to a landfill, if no other market were available for
recycling.  The cost evaluations by both CH2M-Hill  and Engineering-
Science considered the relative economics of the "worst-case"  con-
dition of no market for the sludge and showed that even under this
condition the drying/distribution was competitive with other al-
ternatives.

     It does not appear then, that the fact of an immediate lack
of a market for the sludge product would necessarily preclude EPA
from approval of the proposed project.  EPA will require Metro to
become more specific about the most likely markets for sludge use
in the final EIS.  In addition, Metro will have to spell out
exactly how the sludge would be disposed of .and where, both on-site
and off-site, in the eventuality that for at least the short-term,
no users market were available for the dried sludge.
                                27

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     Regarding the second question, EPA would be strongly opposed
to having Metro use the drying/processing site for any ultimate
disposal of sludge other than for research and demonstration pur-
poses.  The evaluation of sludge injection for a secondary disposal
system at site B-2 (page 166 of the EIS) indicates that severe ef-
fects on plant life, the soil profile, and groundwater would be
expected at the application rates proposed.  The site is not large
enough to effectively dispose of the sludge either liquid or dried.
Therefore, as mentioned above, Metro will have to develop a con-
tingency plan of some form of off-site disposal  to handle all  ex-
cess sludge that cannot be marketed or used in the research and
demonstration plots, for the final  EIS.
                              28

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     Readers of this  document and  of the EIS it summarizes are re-
quested to comment with  respect to contents, conclusions and the
project evaluated.  All  comments may be addressed to:

                Regional Administrator
                U.S.  Environmental  Protection Agency
                Rocky Mountain-Prairie  Region VIII
                Suite 900
                1860  Lincoln  Street
                Denver,  Colorado  80203

     Copies of the full  EIS may be reviewed at public  libraries and
the libraries of Colorado  State University and the  University of
Colorado as well as at the address shown above.  A  public hearing
will be held to receive  additional  written or oral  comments from
the general public.
                                 29

                                           * U.S. Government Printing Office: 1976-678-852

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