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.
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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
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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.
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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.
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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
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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
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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.
28
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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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