908578001C
                           SUMMARY
                            FINAL

                           E.I.S.
                             on
              METRO DENVER SLUDGE MANAGEMENT PLAN
          FACILITIES FOR METROPOLITAN  DENVER SEWAGE
                     DISPOSAL DISTRICT NO. 1
                    COMMERCE CITY, COLORADO
                             by
             U.S.  ENVIRONMENTAL PROTECTION AGENCY
                            and
                     ENGINEERING-SCIENCE
                        February 1978
             Approved by:  Alan Merson
                          Regional Administrator
                          CONTENTS
                                                       Page
Where We Stand                                           1
Why This E.I.S.?                                         2
The Problem and the Plan                                 4
The Analysis  in this E.I.S.                              10
The Alternatives                                        12
Potential  Impacts, Mitigative Measures,
  Unavoidable Effects and Long-Term Implications          16
The Important Issues and Their Resolutions               21

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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 commerical 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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                  SUM|M  ARY
WHERE WE  STAND

In May 1976,  Region VIII EPA released a  draft environmental  impact
statement (referred to as an EIS) about  the  Denver Metro Sludge Manage-
ment Facilities  Plan.  This document explained the project,  its impacts
and the main  alternatives as EPA saw it.  This EIS was written in accor-
dance with  the National Environmental Policy Act as will be  explained
below.  A summary  document was included  with  this EIS; it discussed
what EPA felt to be the most important issues on this project.

     The different volumes in this package are the final EIS on this
project.   Volume I is an updated version of  the draft EIS.  It details
the project's impacts, both short- and long-term, direct and indirect,
possible mitigating measures and alternatives in the manner required
under NEPA.   Volume II contains the written  responses and comments on
the draft EIS by State, Federal and local agencies and concerned citi-
zens.   The  EPA reply to each  comment is provided side-by-side for easy
reading.  This volume also identifies the issues  we now believe most
important on  this  project.  We have also provided a detailed discussion
of these issues  and how we think they can or should be resolved.  In
this Summary, these issues are listed and the proposed method of
resolving them is  presented.

     EPA held public hearings in Denver  and  at the Adams County Fair-
grounds on  September 8th and 9th, 1976.  Both oral and written testi-
mony taken  from  these hearings as well as written comments were used
to develop  the issues discussions.

     It has been a difficult and time-consuming task to prepare the
final  EIS.  EPA  staff personnel have negotiated with a number of
different parties  involved in the project to come up with resolutions
of issues.  We have attempted to incorporate the latest information
available on  controversial issues in particular.

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     The final  EIS will  be distributed to persons  and  agencies who have
indicated an interest in the project (by letter or at  the hearings).
This Summary will attempt to explain where the  final EIS effort was
directed.  We presume that you have already read the draft  EIS.

     By releasing this final EIS, EPA intends to approve the Metro
Denver Sludge Management Plan with certain conditions.  These  conditions
are spelled out briefly in the Summary issues discussion and in Appen-
dix A of Volume II in more detail.  This approval  means that Metro
Denver will be eligible to receive Step II design  funds and eventually
Step III construction funds for this project.

     EPA will not approve the plan until 30 days after release of the
final EIS.  We will be willing to give some additional  time for review
and discussion if anyone so requests by phone or by letter  before the
end of the 30-day period.
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 major 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 en-
vironment.  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 'Metro1 to design 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.  The recently passed Amendments of 1977 to the Clean

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Water Act provide another $25 billion dollars for wastewater treatment
funding,

     EPA decided that the proposed Metro project involved  significant
environmental impacts, and therefore has written this  environmental
impact statement.  The National  Environmental Policy Act requires  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 to 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.

     The legal obligation under the National  Environmental Policy  Act
is to circulate the draft EIS to agencies and persons  having expertise
on the subject or an interest in its outcome.  The comments then re-
ceived as written replies or through the public hearing  process must
then be reflected in the development of the  final  EIS.   The final  EIS
must similarly be circulated to expert agencies and the  public  for a
minimum 30-day period.  Although NEPA EIS's  have not always been
viewed as decision documents, EPA takes the  position that  its final
EIS is a decision-making point.   Therefore,  according  to our own regu-
lations on NEPA, we have tried to sort through the project's various
benefits and impacts and corrective measures  to arrive at  a point
where we feel comfortable with proceeding with this project.

     At a minimum, the EIS is a public disclosure document.  The
discussion of environmental impacts includes  both direct and indirect
impacts to the extent that they can be predicted.   NEPA  requires dis-
closure 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".
                                                  "•*«<,
                                            fiESSSteLr-^

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     It should be made clear that the term "environment,"  as  used
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  re-
cycling it to the land.   Formally, the plan  is  called  a facilities^
plan under Public Law 92-500.   A mechanism for  parcelling  grant  monies
was developed whereby an applicant such as Metro,  after having been
given priority standing by the State, would develop  and submit a faci-
lities 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  devel-
oped, in its construction grant regulations,  a  fairly  lengthy list of
what other information must be presented in  a facilities  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.  Further on in this summary,  we  briefly explain  how Metro's
plan has been changed in this  EIS process.
THE PROBLEM AND THE PLAN
     Metropolitan Denver Sewage Disposal  District  No.  1  (Metro)  provides
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  removed from waste-
water in the process of purifying it.   Sludge contains water, the or-
ganic 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  quanti-
ties similar to commercial fertilizers.   Table A below indicates the

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                                                 A A't
                                                 /•/i' • «!f_. n\ N
                                            SS&SITE A-2J
                                                                PROPOSED
                                                                DRYING 8
                                                                DISTRIBUTION
                                                                SITE B-2
                                         PROPOSED
                                         PIPELINE ROUTE
METRO
CENTRAL
PLANT
                                                      —ir.7^>**°J
                                           4VWAT LOWRY BOMBING RANGE
                                                    METRO  DENVER
                                                 EXISTING AND PROPOSED
                                            SLUDGE MANAGEMENT  FACILITIES
                                                                              to
O>

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relative amounts of these three constituents  in  Metro sludge,  other
natural fertilizer sources and commercial  fertilizer.
     Table A.  CONCENTRATIONS OF MAJOR PLANT NUTRIENTS  IN  SLUDGE
                  AND OTHER FERTILIZER SOURCES

                     (percent of dry weight)
  Fertilizer
Total nitro-
  gen (N)
Total phosphoric   Acid-soluble po-
  acid (P20s)	tassium (K30)
Metro digested
  sludge
 3.0 to 4.0
   2.3 to 3.4
0.7 to 1.4
Ammonium sulfate
Anhydrous ammonia
Urea
Farm manure
Chicken manure
Cottonseed meal
20.5
82.0
38.0
1.2
4.1
7.0
-


1.2 1.2
3.7 2.3
2.5 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  primary
digested sludge (12 percent of the total) from the City of Denver's
Northside plant.   Thus, ,the currently produced sludge .is composed
of 88 percent undigested sludge.

     Raw primary sludge is that sludge which settles out when sewage
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.

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 In  both  types  of sludge it is extremely difficult to separate the
 solid  matter from the water in the sludge.

     Anaerobically digested sludge is produced in large, covered tanks
 using  a  self-sustaining, slow microbial combustion process that re-
 duces  the energy content of primary and secondary waste-activated sludge,
 as  well  as to  break down the more complex, odorous compounds  in the
 sludge.  What  is left is a relatively inert, dark material, rich in
 nitrogen, phosphate, and trace elements.  Anaerobic digestion generally
 performs in short time the natural breakdown 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 disposal, 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 benefits
 (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 chemi-
 cals (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  trying
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 spray-
ing sludge on dryland farming 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, how-
ever, was highly criticized by  the local farming  community because 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, Rowland, Hayes,  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 on the  same general area
it had proposed for the spray ing/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 fully operational digesters in the Metro system are  at  the
Denver Northside (DNS) 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  processing
and disposal of the DNS sludge.  It may be of interest to note that at
present, Metro is dewatering the DNS sludge separately from  the  rest
of Metro's sludge.  The Denver Parks Department has been  using the
DNS sludge on parklands, and Metro is storing and drying  the DNS sludge
in a small area of the Lowry Bombing Range for use  by the Parks  Depart-
ment.

     Recently,  EPA gave  the Metro  District a construction grant  to
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build enough anaerobic digesters to handle all  of Metro's  present and
projected sludge loads to 1985.  The grant was  given with  the under-
standing 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 matter what type
of final disposal was selected.  Some disposal  alternatives (such as
incineration) might operate better without digestion, but  enough
options would still remain available for disposal to permit such a
grant.  Thus, for all practical purposes, anaerobic digestion of
sludge must be considered a part of any future  sludge handling plans.
Metro District has now begun using these digesters to process its
own raw primary sludge.

    Sludge Trans port—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 distri-
bution center 22 miles east of the Central Plant in Adams  County.

    Sludge Drying, Storage and Distribution—Metro's proposed system
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 lined 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 research
and demonstration plots would surround the drying area,  as  shown on
Figure 3 in Volume I of the EIS.   Metro plans to use the site for
emergency disposal by underground injection of  soured digester sludge
on ly.

    Land Application of Sludge—The heart of the proposal  is to
provide Metro dried sludge to willing users in  the entire metropolitan
area.  Metro has indicated that potential  areas of use include  irri-
gated farms, dryland farms, sod farms, Denver parks  and  other metro-
politan parks,  and mine spoil areas.   Metro has also received a con-
siderable number of letters from individual  home owners  who would
like to use the sludge on home gardens and lawns.   Other possible  can-
didates include a company interested in bagging and marketing dried
sludge fortified with additional  fertilizer nutrients.   Another com-
pany proposes to utilize sludge and garbage as  a fuel  source for a
coal  gasification plant.   To a great  extent, the success of Metro's
proposal  will depend on the ability to develop  a market  for the sludge.

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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 pollu-
tion 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  endorsed  the idea  of re-
cycling waste materials wherever it is cost-effective and environment-
ally 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, system
design and a host of other factors.  All environmental areas—biolo-
gical, cultural and physical--must be considered and  protected
in evaluating such a proposed system.  EPA considers  impacts occurring
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"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  import-
ant in deciding the overall  merits of the  proposal.   The EIS is EPA's
tool for evaluating these areas of concern on a site-specific  level.
Because of the obvious concerns about the  impacts  of  the site  B-2
drying/storage operation, the final  EIS has  concentrated more  on
these site issues.

    In preparing this environmental  impact statement, EPA hired an
environmental consultant to  help evaluate  the project.
The work of the consultant, Engineering-Science, was  closely managed
by the EPA Region VIII  staff in  the preparation of  the  EIS.  The
consultant was charged with the  following  tasks in  the  draft EIS:
(1) to review and evaluate the work done by  the Metro District  and
its engineering consultant, CH2M-Hill,  (2) to  evaluate  Metro's
tentative proposals for use of the  sludge  in six areas—irrigated
farms, dryland farms, sod farms,  mine-spoil  areas,  parklands and
home gardens 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.
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     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 with a Denver
 solid waste recycling system under study by the Denver Regional
 Council of Governments (DRCOG).  The latter involved possible use
 of sludge with solid  waste in the Denver area for supplementary fuel
 or for production  of  synthetic gas.

     In the final EIS, the consultant analysed many of the issues
 concerning site  B-2.  Some of the recommendations for changes for
 the project were developed by the consultant.

 THE ALTERNATIVES
                              n
     The draft EIS  considered both entirely new sludge treatment and
disposal systems  as well  as options within the basic Metro plan, as
alternatives.   These subsystem options included changes in site
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location, sizing, and drying-basin  design.   The  final  EIS  goes  into
more detail on site location alternatives,  drying  basin  design  (to
protect water quality), and a new issue  of  separate  versus  confined
treatment for the Denver Northside  Plant.   Additional  treatment alter-
natives such as pyrolysis were briefly evaluated.
Alternatives to the Overall  Metro Plan
     EPA first reviewed the work that had been  done  by  others  in  dev-
eloping 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
evaluation 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 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 compatability 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 Volume I 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 of
Volume I, includes general  sludge disposal options;  EPA feels  that the
ultimate disposal choice in the overall sludge  processing system  has
the most important environmental implications.   EPA  likewise concludes
from an overall standpoint  that the land recycling approach  is generally
preferable to other alternatives, for the Metro situation.

     In the draft EIS, EPA  decided that two  basic alternatives should
be considered further and evaluated in detail:   Metro's proposed
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system and the existing Lowry system.  The  latter  must be considered
further because 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 continue to use the Lowry area for  a  number  of years.

     For a number of reasons, the alternative systems at Lowry have
not proved favorable.  The final  EIS  concentrates  its discussion of
Lowry options to the use of the Lowry Bombing Range  as a site for the
solids recycling/drying project proposed  for  site  B-2.

Alternatives to Portions of the Metro Plan

     The EIS evaluates possible alternatives  within  these two systems.
In the Metro proposal, alternative sites  for  the sludge drying and
distribution center were evaluated.   EPA  reviewed  the comparisons
of 11 sites in a 1973 study developing the  agricultural reuse program.
EPA also reviewed the evaluation  of  three sites selected by Metro for
more intensive consideration in the  facilities plan.  In Volume  II,
a discussion of other suggested sites is  presented,  specifically the
areas at the Lowry Bombing Range  and the  Rocky Mountain Arsenal.
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 habitation,
land values, etc.) are considered.   It is perhaps  more important, from
an environmental viewpoint, to design correctly for  the site-specific
conditions, whatever the site chosen. More information on soils and
groundwater is now available for  proper evaluation of site differences
and impacts and to suggest proper controls  to protect the surrounding
environment.

     Other subsystem alternatives considered  for the Metro system were:
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  real-
istic 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  will be  changed to  protect groundwater
quality.  Metro will have to demonstrate  that there  will  be no ground-
water problem with its proposal during operation or  will  face  further
controls.
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     In order to reduce the amounts of some heavy metals  in  the sludge,
Metro will eventually be required to institute some control  over
industrial discharges into the sewer system.  The most critical  need
for control would likely involve discharges of cadmium and nickel
into the system.

     The question of who should be allowed to use the sludge will
be debated from a public health standpoint.  Either restrictions
could be placed on the types of users, or the system design  could  be
changed to produce a sludge so benign as  to allow for the whole range
of possible users, without any potential  health hazard.   This  will
be decided on a state-wide basis through  agricultural  use regulations.

     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  necessary
for pathogen reduction, and (2) the effect on secondary impacts  (air
pollution and land use from new populations) is only very distantly
related to- sludge handling subsystems.

Lowry  Disposal  System Modification

     Alternatives to the present  Lowry system were described  in the
EIS.   Metro's  new anaerobic digesters will  change the  type of  sludge.
                                  15

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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.   These systems have not proven to be practical
as long-range solutions  to Metro's sludge management problem.
 POTENTIAL  IMPACTS, MITIGATING MEASURES,
 UNAVOIDABLE EFFECTS AND LONG-TERM IMPLICATIONS
     The evaluation  of environmental impacts was carried out in this
EIS in the following way.  A  description of potential positive and
negative impacts from the  proposed Metro system was provided.   Wherever
possible, impacts were quantified with  reasonable basic assumptions
regarding the system and prevailing conditions.  Where quantification
is difficult due to  lack of basic data or an imprecise state of know-
ledge, ranges of possible  impacts or qualitative statements of impacts
were made.  In all cases,  thresholds of significance for impacts were
determined from the  experience of the professionals on the environmental
team and from knowledge of local conditions.

     Potential mitigative  measures were developed for reducing the sever-
ity of potential 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.  From these  measures, certain ones were chosen as
                                  16

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grant requirements for the project.

     The EIS looked at three basic areas in analyzing the  environmental
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  Bombing
Range containing the existing Metro  sludge processing system.   Schematic
representations of impacts in these  three basic areas of concern were
presented in Figures 16, 17 and 18 in Volume I.

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

Sludge Drying and Distribution Site

     The most serious negative environmental impacts at  the sludge
drying and distribution center are on soil  productivity, groundwater
quality and the public health through nitrate pollution  of  groundwater
and pathogen problems.  Other minor  impacts will  occur to downstream
water users because of increased consumption of water; some impact 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 will be controlled with proper measures as  shown
in Table B.

Land Application Areas

     Land application areas hold both the greatest promise  for benefits
as well  as potential detrimental  impact from sludge application.  On
the positive side, the Metro proposal would lessen overall  energy
use—in  comparison with commercial fertilizers, which require  energy
for their production—by taking advantage 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 some  commercial
fertilizers.   Sludge nitrogen is  also of the slow-release form  that
would be available to plants over a  number of years, somewhat  in har-
mony 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 involved.
Dryland  farms have different (lower) requirements for amounts of
nutrients and sludge from those of irrigated areas.   Exposure to
pathogens will  differ greatly, depending  on whether sludge  is applied
to farmland or to city parks and  home gardens.
                                  17

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                   Table  B.   SUMMARY OF MAJOR  POTENTIAL  IMPACTS,  MITIGATION MEASURES  AND UNAVOIDABLE  EFFECTS
                                (Underlined mitigation measures  indicate  those chosen for  this  project)
       Environmental
         Parameter
                                 Impact
                             Importance
                      Severity
                     of Impact
                                                                     Mitigation3
                 Feasibility
                                                                                                           Methods
                                                                        Unavoidable Effects3
                                                        Sludge Drying, Storage and Distribution Site
00
       Soil/Land
       firomidwater
Destruction of Profile
Loss of 200 acres
of productivity
(•>- SlOO,000/yr)

Nitrate and salt
       Water Quantities    Removal from South
                          Platte
       Air Quality
       I'ublic Health
       Energy Use

       Nutrient
        Resources
Odor generation,
participates
                          Pathogen survival and
                          vector proliferation;
                          airborne particles
    beneficial

    beneficial
 moderate




   high





  minor



negligible




   high




 moderate

   high
Confined to site,
     severe
                                                Potentially severe
                                                    moderate
Negligible except
with digester up-
set; participates
in severe wind

Low, except with
loss of control
                     NA

                     NA
                                                                                                              NA
                              (1)  Line  basins;
                              (2)  Remove decant;
                              (3)  Collect drainage;
                              (4)  Promote anaerobic
                                  conditions

                              (1)  Avoid Irrigation;
                              (2)  Return water
                                             (1) Bury sour digester
                                                 contents elsewhere;
                                             (2) Keep stockpiles
                                                 moist

                                             (1) Medical attention;
                                             (2) Insect control
                                             (3) Perms & wetting
                                                 sludge

                                                       NA

                                                       NA
                                                                        Elimination of  Agri-
                                                                        culture in the  site;
                                                                        destruction of  wild-
                                                                        life habitat

                                                                        Mitigation will
                                                                        Increase project  cost
Minor odors  on calm
days, some particulate
dispersal in severe
winds

         Hone
          NA

          NA
                                                                   Sludge Application Areas
       pood Chain
       Water Quality
                          Magnification of  heavy
                          metals, especially
                          Cadmium
Nitrate and  salt
concentration
high
high
                                                Low  under strict
                                                controls
                  Minor  on drylands,
                  severe on others
                                                                                                                             (h)
                                                (1) Limit sites, crops
                                                   users, rales;
                                                (2) Contto 1_heavy metals
                                                   at source
                                                         HA
                                                        Heavy metals contam-
                                                        ination in soils;
                                                        exposure of burrowing
                                                        animals to toxic
                                                        elements

                                                        Long-term cumulative
                                                        effect in entire
                                                        region

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Soil Productivity
Soil Salinity
Plant Nutrition
Energy Use

Food Chain

Public Health
Soil Productivity
Soil Salinity
«D
Groundwater
Quality
Air Quality

Energy
Chemicals
Resources
beneficial high
adverse moderate
beneficial moderate
Fuel requirement for moderate
trucking
Lowry
Domestic animals grazing high
on sludge-amended fields

Exposure of people in t very high
parks and home gardens
to pathogens
beneficial low
Salt buildup in root moderate
zone

Nitrate pollution, high
salt increase
Odors low

Use of large amounts moderate
of fuel for transport
Use of conditioning moderate
chemicals (ferric
chloride and lime)
aThe symbol + indicates totally feasible; - indicates iufeasible;
State Regulations.
NA NA
High on dryland - NA
farms only
NA NA
Lower than present + Develop markets In
operations vicinity of site
Bombing Range Existing Operations
Potentially severe + (1) Restrict grazing;
(2) Control heavy metals
at source
Potentially severe + (I) Longer drying time;
(2) Medical attention
NA NA
moderate P (1) Remove decant;
(2) Spread over larger
areas and lower the
loading rates
Low to potentially - NA
severe
Low except with + (1) Source control of
digester upsets toxic materials;
(2) Optimal operation
of digester;
(3) Burial of sour
digester sludge
high + (I) Use of anaerobic
sludge reduces total
load, produces gas
high + Use of anaerobic digesters
P indicates feasible in part; NA Indicates not applicable.
NA
Long-term cumulative
effect in dry farms
NA
Moderate fuel con-
sumption

Heavy metals
accumulation in soils


NA
Gradual salt buildup
in the region

Groundwater pollution
in irrigated farms
Complaints from
neighboring areas

Loss of energy;
resources wasted



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     The principal areas of concern in applying sludge to  lands  on
which various kinds of crops for human use are grown  would be:   nutri-
ent 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  because of the
projected recommended loading rates considered for this semi-arid area.

     Each of the above problem  areas will  be  mitigated to  a large
extent, either by controlling how much sludge is applied and where  it
is applied or by source control  of heavy metals and greater treatment
at the Metro facility.  Such measures will require greater managerial
control by the Metro District as to the final  disposition  of sludge.
Legislation was passed in the State of Colorado to remove  sewage
sludge from the category of solid waste and set up a  new statute to
recognize the agricultural benefits of sludge in closer harmony  with
existing public health laws.  In turn,  the State Health Department is
establishing regulations 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.  The most important condition will  be  that Metro will not be
allowed to distribute sludge until State regulations  are finalized.

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, were 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 productivity,
even 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 Administration,  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.  The only long-term  mitigation
is to stop the present form of disposal at the site and allow the lands
to gradually restore themselves.
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 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-renewable
 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 a-
 mount of fossil fuel needed to produce these fertilizers.  Soil
 productivity could be improved by recycling carbonaceous material  to
 the soil.  Solar energy would replace the fossil 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  expected
 to significantly deteriorate soil quality if the conservative applica-
 tion rates are followed.  Some metals could be beneficial as micro-
 nutrients to crops.


 THE IMPORTANT  ISSUES AND  THEIR RESOLUTIONS
     In the draft EIS, the Summary accompanying  the EIS  listed what  EPA
felt to be the most important issues surrounding the Metro offsite solids
proposal.  These represented our best judgment at the time.  Since then,
the many comment letters and discussions  we had  in the public  hearings
have raised other important issues.

     The following list was developed from the above sources and
indicates where EPA must make a decision  about these issues or problems.
They are in the form of questions, in order to better focus on the
specific problem facing this project.  There were other  issues raised
that we felt could be best answered  directly to  the letters.   This is
done in another section of Volume II.  The issues  here represent the
ones most often raised or felt to be the  most critical.  The issues
are separated into different categories;  I,  those  involving the pro-
posed changes at the central plant and pipeline;  II,  site-related
issues; III, present operation at Metro;  IV, alternatives; and V, sludge
use issues.  (This summary discussion of  issues  parallels the  more
detailed discussions of issues in Volume  II.  The  same identifying
numerals are used.)   EPA's proposed  action or reaction to the  issue
questions are given  as  answers.
                                   21

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                 I.   CENTRAL  PLANT AND  PIPELINE  ISSUES
Issue 1-1.   What kind of source  control  at  the Metro plant is needed
to limit concentrations  of heavy metals  and persistent orgam'cs such
as polvchlorinated biphenvls  (PCB's)  and pesticides for sludge
application to the land?

     EPA has concluded that based  on  the present  information  and
criteria, none of the identified contaminants  require  immediate special
pre-treatment.  EPA will be following a  national  policy under the  1977
Amendments   requiring additional  pre-treatment for industries dis-
charging to municipal treatment  plants.   Metro is  still beginning  its
study to identify who its industrial  dischargers  are and what they're
discharging.  EPA on a national  level  is also working  on  regulations
and guidelines for acceptable levels  of  toxic  pollutants  in sludge;
when this information is available, it will be integrated  into require-
ments for the Metro District.  In  the long  run, Metro  District will be
required to reduce the amounts of  heavy  metals and toxic substances
entering the sludge to create a  better agricultural product.

Issue 1-2.   Please provide a better description of the proposed pipe-
line, routing, existing conditions and impacts along the  pipeline
right-of-way.

     This has been done in Volume  I of the  EIS and in  the Issues
discussion.  We concluded that the impacts  are not that significant.

Issue 1-3.  Will the added use of  water  in  the Metro offsite  solids
project over thajb now presently used for sludge treatment  involve  a
water rights conflict and create a significant downstream impact?

     We conclude that the amount of water involved in  the offsite
project compared to  flows in nearby irrigation  ditches is  negligible.
More importantly, the Denver Water Board has control  over much  of
Metro's wastewater and has not indicated that there  is any problem
from their  point of  view.  Metro thinks  that it  is legally correct
for them to use the  additional water as  part of  the  sludge treatment
process.  There is still the potential for disagreement  on this  issue,
however.

Issue 1-4.  Will the proposed project affect historical/archaeological
resources  and  is a survey  required?

     Metro  has  had a surface archaeological survey done for the final
three sites  (including  site  B-2) in its  selection process.  No signifi-
cant resources  were  indicated on site B-2.   The State Archaeologist
has  reviewed  the pipeline  route and indicated that a preliminary survey
is not  necessary.  EPA will  require Metro  (per the recommendations of
                                  22

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the State Archaeologist) to have an on-site  archaeological  monitor
for the first part of the pipeline construction (from the plant to
Colorado Boulevard).  The remainder of the route and the site con-
struction would be supervised by Metro personnel who have been famil-
iarized with archaeological artifacts.  A procedure for notifying the
State Archaeologist in the event of a find will be followed  (see
Grant Conditions in Volume II, Appendix A).

Issue 1-5.  What is Metro's contingency plan  for a pipeline  break?

     Metro will have redundant equipment in the form of dual  pipelines
and pumps to handle most emergency situations.   The line will be ex-
tensively monitored electronically; there are also shutoff and blowoff
valves along the line that can be triggered automatically.   Metro will
detail just how it will respond to a variety of different emergency
situations with the pipeline in the required Ope rati ons Man ual to be
developed by Metro in Step II of this project.   See Grant Conditions.

Issue 1-6.  How would Denver Northside Treatment Plant's si udge be
h_a_ndTjed_ in the Metro off site solids proposal?

     Until the comments on the draft EIS for this project were received,
it has always been assumed that Northside sludges (which are now
treated at Metro) would be part of the sludges  to be sent to the off-
site drying basins.  The City of Denver is now interested in pursuing
separate treatment for the Northside sludge.   The merits of  this
suggestion are discussed under Issue IV-3.  If Northside sludge is
processed in the Metro offsite project, there are potential  cost
savings for Northside; there may also be benefits to Metro as well from
added flexibility to stabilize the raw sludges.  The Denver  Parks De-
partment would be guaranteed sludge for parkland use in the  offsite
system.  EPA recommends that management from Northside and Metro get
together to work out the optimum arrangement  for both parties within
the offsite solids system.  See Grant Conditions.
                         II.   SITE-RELATED ISSUES

Issue I1-1.  Please provide a better description  of existing conditions
at siteB-2 anda better definition of on-site  environmental  impacts.

     An expanded description  of existing conditions and impacts  at
site B-2 can be found in this discussion.   Information  is  also available
in the EIS in Volume I, Section III and Appendix  E.

     We conclude that there will  be a significant  impact as  a result  of
the loss of productivity of 2000  acres at  site  B-2.   About 1 percent
productivity from fanning in  Adams  County  will  be  lost,  totaling about
                                   23

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$105,000 per year.   This is  mitigated by the  fact  that  the  potential
value created by the Metro offsite operation  could be much  greater
(see Issue II-8).  Some of the land on the site  could continue  in
agricultural production.

Issue II-2.  Will groundwater deterioration  occur, particularly in
the Lost Creek aquifer, and what mitigating measures such as  lining
are necessary?

     This is perhaps the potentially most severe impact expected from
the project.  EPA will require that certain performance standards be
met in the construction of the basins to insure  minimizing  leaching
to the groundwater.  Metro will  be required to  demonstrate by  whatever
means it chooses to see that an  impervious layer equivalent to  a
compacted layer at least 12" thick with 12" of cover material meets
a permeability limit of no greater than 1 x 10"7 cm/sec, wherever liquid
sludge will come into contact with the  ground.  Further, Metro will
be required to monitor the groundwater beneath the site for a variety
of pollutants.  If drinking water quality standards are violated, Metro
will also have to pump the contaminated groundwater to  the  surface for
treatment.  See Grant Conditions.

     There will still be some residual water  quality effects  from site
leaching even with these mitigating measures.  At  present,  EPA  believes
they are minimal and not a cause for concern.

Issue II-3.  Will odors create a problem in the  vicinity of the site
either from normal operations or with digester upsets?

     EPA does think there will be some occasional  odors, even under
normal operations, that would principally affect the two residences
closest to the site.  Metro will be required  to  submit  a contingency
plan in the Operations Manua1 to make sure that  emergency burial
measures of sour digester contents do not create an odor problem.

     It is still somewhat uncertain as to how often and how bad a
problem odors from normal operations would be for  the closest residents.
Metro must be prepared to compensate these residents if the odors
create a nuisance.

Issue II-4.  Hill land values in the area decrease as a result  of the
Metro project and should Metro purchase a buffer zone to compensate
owners ?

     Predicting what the economic effect on nearby lands will be  from
this project is very complex.  The area is far enough away  from the
metropolitan area now to probably be out of the  range of urban  develop-
ment speculation; as the city grows, this situation will undoubtedly
                                   24

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change.  The project should have no effect on agricultural  land values.
We do not think any compensating measures are required.

Issue II-5.  Mill wind transport of stockpiled sludge create hazards
offsite?

     The fierce, high winds we occasionally  experience in  Colorado
could move some of the dried sludge product offsite.  We do not believe
it to be a potential public health problem, but it could be a nuisance.
Metro intends to wet down the sludge during these conditions.  Hydrants
will be placed in the stockpile area.  EPA will further recommend that
Metro construct berms to protect the sludge against wind movement.
See Grant Conditions.

Issue II-6.  Is the design of the runoff retention system sufficient,
especially during extreme rainfall events?

     EPA's consultant has evaluated the design of the runoff retention
system.  The design appears satisfactory for most runoff situations.
The Metro District will have to apply for an NPDES Permit to discharge
to surface streams.

Issue 11-7.  Should final EIS completion await the site designation
process of Adams County?

     The County feels that Metro should go through the site designation
process required for a solid waste disposal site (this project site
operation falls under this category), before EPA completes  the EIS
process.  EPA has decided to finish the EIS process first in the
interests of time, and also to provide technical information to County
decision makers.

     EPA will require that the site designation process be finished
before Metro can receive design and construction funds for this project.
If a site change is necessary, EPA will write a supplement to the EIS.

Issue 11-8.  How does the loss of farmland productivity from site B-2
compare with the agronomic value in the sludge?

     EPA thinks that the offsite solids project could potentially
create more value than would be lost through eliminating farming on
site B-2.  The estimated value of the sludge  as a salable  item ranges
from $288,000 to perhaps over a million dollars per year.  This com-
pares with a farm productivity loss of some $105,000 per year.  The
higher values for the sludge would occur if the sludge product were
upgraded (bagged products, sold in retail stores, or mixed with chemical
fertilizer components).  In the balance, the net economic effect would
be positive.
                                   25

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Issue II-9.  Are land uses in the vicinity of site  B-2  compatible
with the proposed Metro operation?

     EPA thinks they are at present.   The project  is an  agriculturally
related one, and would sit in an area of dryland farming.   Future
activities such as a regional airport for Adams  County and urban
development would probably be less compatible.   We think the  likelihood
for development is still many years away.   The  airport and sludge site
could be compatible.  The airport could use the  sludge site as  a  flyway
area that would stay as open space.

Issue II-10._  Hill insects and birds  be attracted  to the B-2  site and
create a future hazard for airport traffic?

     EPA does not think that this is  an imminent hazard.   We  have not
been formally told that the airport will even be located close  to the
site.  Adams County did inform us that they were strongly considering
a site for the airport about two miles to the west of site B-2.

     Insects will be controlled by Metro in the  basins.   They are working
with a State entomologist to develop  a vector control program.  This
will keep to a minimum food that birds could use.   There does remain
the possibility of having birds hit by airplanes.   We have looked at
a few other similar situations and decided that  there is only a very
small chance that birds would be attracted to the  site and cause  a
problem for aircraft.  EPA will require that Metro minimize weeds and
aquatic growth in the site reservoir.  See Grant Conditions.

Issue 11-11.  Is this project of such an untested nature as to  require
further research before the project is built?

     We do not think so; drying and selling sludge for agricultural
use is being practiced around the country.  We  have provided  a  list
of these communities.  There are some genuine research issues (especial-
ly ones dealing with Western semi-arid conditions) that  need  studying.
Metro's proposed research and demonstration areas  could  provide some
of these answers.  There are also some long-range research issues that
are being studied nationwide.  EPA thinks that  enough information is
available to go ahead with this project.

Issue 11-12.  Is the drying basin capacity sufficiently  designed?

     Yes, there is sufficient design  at present and for  the projected
design year tonnage.
                                   26

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Issue 11-13.  How soon will additional  capacity be required at the
sludge basins, and will more land be required?"

     The project was designed to treat a certain capacity by 1985.
Metro based their calculations on a faster growth rate than now exists.
EPA thinks they could well have enough capacity to last to the year
2000.  Additional basin capacity could also be added onsite.  We don't
think more land will be needed.

Issue 11-14.  Is site B-2 at such a distance from potential markets as
to affect sludge marketability, and is there a better site elsewhere?

     EPA thinks that while there might be a slightly better site closer
to the metropolitan area, it would conflict sooner with urban growth.
Metro has a large number of options as to where they could market
their sludge product.  These markets are quite dispersed and no one
site is ideally suited for all of these markets.

Issue 11-15.  What are Metro's plans for emergency disposal of
sludge if the markets do not develop as expected?

     If a market for the sludge does not develop as expected, Metro
plans to temporarily store it onsite and, if necessary, dispose of
excess dried sludge by landfill ing at the Lowry site.


                       III.  PRESENT OPERATIONS

Issue III-1.  Could the sludge disposal operation now used by Metro
at Lowry be continued or modified, instead of the offsite solids
project?

     Metro has told us that they could continue to use the Lowry site
indefinitely for sludge disposal.  It would be very expensive, and
would waste valuable materials in sludge.  The draft EIS discussed
the possibility of using the Lowry site as a storage area for sludge
dried at the plant and shipped there by truck.  This would allow the
sludge to be recycled, but it would still be expensive.  Also the
kind of sludge that has to be treated at Metro does not dewater well
and might make this alternative unworkable.  EPA thinks that this
operation is not a good long-run solution.
                                 27

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                        IV.   ALTERNATIVES

Issue IV-1.   Should another  site for the offsite solids  project,
particularly the Lowry Bombing Range and the Rocky Mountain Arsenal,
have preferentially been chosen?

     There is merit to using public instead of productive private
lands for this project.  Metro did try to obtain lands for this project
from the General Services Administration, the Rocky Mountain Arsenal,
and the Lowry Bombing Range  without much success.  EPA thinks that
Metro did a satisfactory job in looking at alternative sites for this
project.  We did look at Lowry (where Metro is now landspreading sludge)
more closely as a site for the recycling project.  We concluded that
it is probably an acceptable site, although not an ideal one.  We
think B-2 is a better site.   Acquiring the land at Lowry is probably
the biggest problem.  EPA does recommend that Metro try to obtain a
Lowry site if B-2 is not chosen.

Issue IV-2.  Why couldn't alternative technologies like incineration,
thermophilic digestion, "the Swedish method", or pyrolvsis be used
instead of the Metro offsite solids proposal?

     The EIS does look at a wide variety of alternative technologies
that could have been used for this project including the ones ventured
here.  EPA still thinks Metro made the best overall choice.  The
above technologies were suggested by commenters on the draft EIS.
Except for incineration, these technologies are still experimental.
They also have  considerable problems of  their own.  Metro has stated
that if the offsite project were not built, incineration would be
their next choice.

Issue IV-3.   Should EPA participate in separate planning and funding
for  Denver Northside Treatment Plant sludge disposal as suggested by
Denver?

     EPA  analysed  the  rough cost figures given  by  Denver for their
alternative  plan for  separate Northside  sludge  treatment.   We  con-
cluded  that  it  would  cost Denver a  lot more money  in  the long  run to
go  separate.   Based on EPA  cost-effective criteria, EPA will not
participate  in  funding for  a  separate Denver  system.

 Issue  IV-4.   What  alternatives  are  available  to control  qroundwater
quality at  site B-2?

     Discussion of alternative  systems  is provided in Volume II.
Lining  was  chosen  as  the  most cost-effective  solution.
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                        V.  SLUDGE USE ISSUES

Issue V-l,   Will EPA place constraints on sludge use because of
'public health problems from pathogens, salt accumulations or effects
of toxic substances (especially heavy metals and organics)?

     The three areas—pathogens, salts, and toxic materials--were
identified as the principal constituents of most concern in sludge.
EPA considered placing constraints if necessary on certain uses be-
cause of these problems.  We now feel that there is not enough
evidence to suggest that any particular facet of Metro sludge or the
design of this project would require special constraints on sludge
use.  Pathogens will be effectively killed for most uses with the
combination of anaerobic digestion and drying/storage.  Salts (upon
receipt of better information) do not appear to be as great a problem
as was earlier estimated.  Heavy metals and organics appear to be
within tolerable limits as defined by Federal and State guidance.

     EPA still recommends that a cautionary approach be used where
human food chains are involved.  The next issue describes where
such cautionary approaches are needed.  EPA will periodically be
providing new guidance on acceptable limits for these various sub-
stances.  In new regulations required under the 1977 Amendments,
EPA will recommend a constraint on Cadmium.  See Grant Conditions.

Issue V-2.   Should constraints to Metro sludge use be set depending
upon the kinds of use contemplated?

     The following areas' of caution should be observed for the various
uses contemplated:  city parks - avoid contact with human activity;
home gardens - avoid use on leafy vegetables and crops that uptake
heavy metals, and crops that can be eaten raw; irrigated farms - avoid
situations similar to home gardens; and dry land farms - avoid wide-
scale use until better studied on small operations, avoid over-
fertilizing.  These recommendations will be proposed to Metro District
as guidelines for its users.  See Grant Conditions.

Issue V-3.   Are Metro's plans for use reasonable and compatible with
market trends?

     EPA thinks that although a market survey might be helpful now,
this marketing work will have to be done eVentually by Metro to make
the project successful.  There does appear to be enough different
markets to use the final product.
                                  29

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Issue V-4.  How will controls over sludge use and management be imple-
mented by Metro, the County, the State or others?

     The primary guiding force for management and control of sludge
will be through State control.  The State is now developing guidelines
for application of sludge to land.  EPA will require Metro to store
the dried sludge on-site until such time as the State guidelines are
passed (with the exception of municipal parkland users).  See proposed
State Guidelines in Appendix B, Volume II.

Issue V-5.  What are the long term implications for sludge recycling
to the land?

     EPA concludes that the prospects are generally favorable—added
soil tilth and moisture holding capacity, the recycling of nutrients,
etc.  The cautionary problems - heavy metals accumulations, salts,
and pathogens—are not believed to be serious enough to work against
the overall benefits of sludge recycling.  Work in the future to re-
duce present sludge contaminants should make municipal sludge a
better material to recycle to the land.

     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.   EPA will  not make
a  final decision on this EIS  untilj  wK l§ ^
                                   30

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
   EPA 908/5-78-001C
                                                            3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
   Summary- Final  EIS
   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 III of  III  Volumes; Volume  I:EIS;  Volume II: Issues  and Resolution;
                               Volume  III:  Summary
16. ABSTRACT            '    ~~"~—————————————————————^———————	

       This volume summarizes the information contained in the  two volumes dealing
  with the Metro Denver Sludge Management  Plan.   The summary describes the
  problems with current Metro Denver sludge handling that led  up to the current
  plan.  A brief description of the proposed sludge recycling project is presented.
  The summary then  highlights the primary  impacts of the project.
       A final section  contains a definition of the thirty-one  issues considered
  to  be the most significant about this  project.   These issues  are discussed and
  resolved in Volume II  of this EIS.  The  summary presents the  main conclusions
  regarding these issues.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                               b.lDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
  sludge;  solids; semi-arid;  dried sludge;
  solids  recycling; groundwater impacts;
  basin  lining; EIS; final  EIS
Denver; Colorado; 201;
facilities  plan
18. DISTRIBUTION STATEMENT
          unlimited
                                               19. SECURITY CLASS (This Report)
                                                   unclassified
                        21. NO. OF PAGES
                                33
                                               20. SECURITY CLASS (Thispage)
                        22. PRICE
EPA Form 2220-1 (R»v. 4-77)   PREVIOUS EDITION is OBSOLETE

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