-------
EPA-908/5-78-001B
FINAL
E.I.S.
VOLUME II
on
METRO DENVER SLUDGE MANAGEMENT PLAN
(FACILITIES FOR METROPOLITAN DENVER SEWAGE
DISPOSAL DISTRICT NO. 1
COMMERCE CITY, COLORADO)
EPA Project Number: C0080341
by
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII, DENVER
February 1978
Approved By: Alan Merson
Regional Administrator
Prepared under Contract Number 68-01-3407 between
Engineering-Science, Inc.
EPA and 600 Bancroft Way
Berkeley, California 94710
-------
This report has been reviewed by the Region VIII
Office of the U.S. Environmental Protection Agency
and approved for publication. Mention of trade
names or commercial products does not constitute
endorsement or recommendations for use.
This document 1s available to the
public through the National Technical
Information Service, Springfield,
Virginia, 22161.
1
-------
TABLE OF CONTENTS
Page
List of Figures
List of Tables
IV
i v
Section
A
B
INTRODUCTION
COMMENTS ON THE DRAFT EIS AND EPA RESPONSES
Introduction
Draft EIS Written Comment and Issues Matrix
Letters with EPA Responses
DETAILED ISSUES DISCUSSIONS
Issue I
Issue 1-1 -
Issue 1-2 -
Issue 1-3 -
Issue 1-4 -
Issue 1-5 -
Issue 1-6 -
Issue II
Issue II-l -
Issue 11-2 -
Issue I1-3 -
Issue I1-4 -
Issue 11-5 -
Issue II-6 -
Issue I1-7 -
Plant Operation and Pipeline
Impacts
Source Control of Heavy
Metals and Organics
Pipeline Route and Impacts
Water Rights Conflicts
Historical/Archaeological
Resources Along Pipeline
Route
Contingency Plan for Pipeline
Break
Denver Northside Plant
Sludge Treatment
Drying and Distribution
Site Issues
Existing Conditions at
Site B-2
Groundwater Deterioration
at Site B-2
Odors at Site B-2
Land Values Around Site
Windblowing of Stock-
piled Sludge
Design of Runoff Retention
System
County Site Designation
Process
3
3
4
9
149
149
154
158
153
159
161
169
169
172
185
186
188
189
191
ii
-------
TABLE OF CONTENTS (continued)
Page
Section
C
Issue 11-8 -
Loss of Farmland Pro-
ductivity
192
Issue II-9 -
Land Use Conflicts at
Site B-2
198
Issue 11-10 -
Insects and Birds at Site
199
Issue 11-11 -
Research Requirements
201
Issue 11-12 -
Drying Bed Capacity
204
Issue 11-13 -
Future Drying Capacity
206
Issue 11-14 -
Distance From Markets
208
Issue 11-15 -
Emergency Disposal of Sludge
209
Issue III
Present Operation Issues
210
Issue III-l -
Continuation of Disposal
at Lowry
210
Issue IV
A1ternatives
212
Issue IV-1 -
Alternative Sites
212
Issue IV-2 -
Alternative Technologies
217
Issue IV-3 -
Separate Planning for Denver
Northside Sludge
219
Issue IV-4 -
Groundwater Quality
Control Alternatives
231
Issue V
Sludge Use
234
Issue V-l
Salt, Pathogen, and Toxic
Substances Problems
234
Issue V-2
Constraints to Sludge Use
241
Issue V-3
Sufficiency of Metro's Plans
for Use
246
Issue V-4
Controls Over Sludge Use
247
Issue V-5
Long-Term Implications
249
D
REFERENCES
iii
251
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APPENDICES
Appendix
A Proposed Grant Conditions for Metro Offsite Solids Proposal
B State of Colorado Draft Guidelines for Sludge Utilization
on Land
C Selected Correspondence with Relevant Agencies on Possible
Utilization of the Rocky Mountain Arsenal Sites for Sludge
Dry i ng
D Project Proposal for Water Resources Investigation at the
Sludge Drying Site
Table
LIST OF FIGURES
LIST OF TABLES
Page
Figure
1 Sludge Pipeline Route 155
2 Archaeological Resource Considerations for the
Pipeline Excavations 160
3 Schematic Diagram of Existing Denver Northside
and Metro Denver Treatment Plant Principal
Units and Flows 163
4 Chlorides and TDS Concentrations in Wells Sampled
During Lowry Goundwater Study 174
5 Wells in the Vicinity of Site B-2 177
6 Ownership Map of Lowry Bombing Range Near Metro
Disposal Operation 215
1 Average Heavy Metal Content of Metro Denver
Sewage Sludge for the Year 1975 150
i v
-------
LIST OF TABLES
Page
Table
2
Heavy Metals Content of Anerobically Digested
Sewage Sludge
150
3
Proposed Ranges of Trace Element Concentrations
in Sludges Applied to Land in the State
of Colorado
151
4
Concentration of Organic Residues in Metro
Denver Sewage Sludge
153
5
Quantities of Sludge Treated by Metro in 1976
164
6
Projected 1986 Sludge Quantities to be Dried
at Drying and Distribution Center
168
7
Wells in the Vicinity of Proposed Drying and
Distribution Center
176
8
Sludge Distribution Practices for Municipalities
(from Literature Review)
193
9
Sludge Distribution Practices for Municipalities
(from Telephone Review)
196
10
Projected Sludge Quantities Produced by Metro
for the Years 1977, 1985 and 2000
207
11
Annual Cost to the City of Denver and Other
Metro Members for Various Sludge Treatment
Alternatives at Northside
226
12
Present Worth Analysis for Various Northside-
Metro Sludge Alternatives
228
13
Drying Basin Liner Analysis Summary
232
14
Chemical Constituents of Anaerobically Digested
Primary Sludge from the Denver Northside Plant
237
15
Maximum Recommended Quantities of Metals Which
Should be Added to Agricultural Soils
V
240
-------
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-------
This section provides a brief introduction to
Volume II of the EIS. It explains the organization of
Volume II and the reasons that EPA felt that this
volume was necessary to clarify and discuss the important
issues surrounding the proposed project.
-------
SECTION A
INTRODUCTION
This EIS has been organized in the following manner: Volume I
is an updated corrected version of the draft EIS. It contains the dis-
cussion of the required five points under NEPA. This volume (II) builds
on the first volume by expanding discussion on critical issues involved
with this project.
Readers who are familiar with the draft EIS, and are aware of the
project and its impacts, can confine their reading to Volume II. Es-
sentially Volume II represents work done by EPA on the EIS, after the
release of the draft.
Volume II is organized as follows: The first section contains a
copy of all of the written correspondence received on the draft EIS.
Copies of written testimony given at the public hearing are also in-
cluded. We have reviewed the oral comments given at the public hearing;
we think that the written comments provided here adequately reflect all
of the issues raised at the public hearing. Side-by-side with the writ-
ten comments are EPA responses. Some of the questions and comments were
of a specific or one-of-a-kind comment as to be answered directly. This
is done on most of the letters.
Where a comment raises a general issue, one of interest to many
persons or agencies, the reader is referred to the issues section of
Volume II. Here the issues are discussed in more detail.
Thirty general issues were identified. Some were included because
of the recurring interest of many citizens. Others were included be-
cause EPA itself felt more information or issue resolution was needed.
The issues are broken down into five areas: I, plant and pipeline
issues; II, site issues; III, present operation issues; IV, alternatives
issues; and V, sludge use issues. Every attempt was made to provide the
latest information and to secure the positions of persons or agencies
involved in the issue. The issues are framed as questions in order to
better focus on the specific problem at hand.
Although a few new issues were raised in the draft review, we
think the real value of the comments was to dtVect EPA as to where
it should focus its attention on issues already raised in the draft EIS.
We have developed the issues discussions to a point of resolution.
Either the issue involved is important and needs some project modifi-
cation or it is not. We have tried to presmt these discussions in
a conclusive manner.
-------
Finally, the Appendices in Volume II contain two important quali-
fications to the presently proposed Metro offsite solids project. Ap-
pendix A is a list of proposed grant requirements, most of which stem
from the issues discussions. Appendix B is a copy of the Colorado
Health Department's proposed sludge application guidelines. These re-
quirements will be an essential part of the agricultural distribution
operation of Metro Denver and other communities. As of this writing,
they are still in proposed form and may be changed.
2
-------
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-------
This section presents copies of the letters received
during the course of the review of the draft EIS. Specific
EPA responses are presented next to each letter. These
letters are presented to give an idea of the way the
public and other agencies viewed the project issues.
-------
SECTION B
COMMENTS ON THE DRAFT EIS AND EPA RESPONSES
INTRODUCTION
This section contains the written comments received by EPA subse-
quent to the release of the draft EIS. Next to each of the comments
is the specific EPA response or the location where the particular is-
sue is addressed further in the final EIS. Preceding the written com-
ments is a matrix showing each commenter, the pages on which a copy of
the comments is found, and the particular issues addressed by each
letter. This matrix thus provides a cross-reference for indication
which commenter addressed which issue, as well as showing which page
each letter is on.
In general, the letters are found on the left side of the page,
with the EPA response on the right side. Where a letter addresses sev-
eral issues, the sections of the letter specifically addressed and the
response are both numbered for easy identification.
3
-------
DRAFT EIS WRITTEN COMMENT AND ISSUES MATRIX
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DRAFT EIS WRITTEN COMMENT AND ISSUES MATRIX (Continued)
ISSUES
Source Control of Heavy Metals
-4 Pipeline: Impacts, Archae-
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Hater Rights Conflicts
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Betty Mundell Bennett
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Council on Environmental
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Vincent Sauter
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Lost Creek Ground-
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DRAFT EIS WRITTEN COMMENT AND ISSUES MATRIX (Continued)
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-------
CLIMAX MOLYBDENUM COMPANY
AonnsaoaioF AMAKk
HENDERSON MINE
Boxes
Empire, Colorado 80438
(303) 569-3221
November 30, 1976
Letter #1
v£>
Mr. Mike Gunaecki
D. S. Euviiiiiiwnriil Protection Agency
Rocky Mountain Prairie Region
Suite 900
1860 Lincoln Street
Denver, Colorado 80203
Dear Mr. Gunaecki:
A previous letter from me pertaining to the use of sewage
sludge for the reclamation of mined lands was Included as part
of Appendix F In the draft EIS on the Metro Denver Sludge
Manageaent Plan. I was unable to present testimony at the
public hearings and, by nay of this letter, would like to further
substantiate my previous feelings.
The use of sewage sludge for reclamation of sterile nine
waste covering the falling ponds at AMAX Inc.'s Urad Mine is
longer experimental. Sludge is the single aost important Ingre-
dient In the revegetation portion of the reclamation of the mine.
Approximately 40 acres have been successfully revegetated with
air-dried, anaeroblcally digested sludge from the Metropolitan
Denver Sewage Disposal District's No. 1 plant. The reclamation
plan timetable Is on schedule, and approximately 4,000 dry-weight
tons of sewage will be used by 1980. He are also using all
available excess sludge from the Idaho Springs plane. The quan-
tities froa Idaho Springs are small and are not Included in the
above figure.
Overall, the use of sludge is proving more satisfactory In
every respect than Initially expected. Hot only is it Instrumental
as a nutrient source and soil builder, it is also easy and unof-
fensive to work with. Equally as Important, it is economical.
Haulage costs 87 miles one way from the Lowry Bombing Range are con-
siderable but are actually cheaper (all things considered) than
using the required quantities of inorganics to accomplish the same
end.
In short, I strongly endorse the proposal to recycle municipal
wastes.
Sincerely,
fO*~l
Larry F. Brown, Ph.D.,
Environmental Control Engineer
LFB:mb
EPA Response
Ve thank Mr. Brown for his letter of support for the project.
The use of Sludge on reclamation of mine tailings has been shovn to
be of considerable benefit. We are particularly iapressed that the
economics for hauling sludge 87 niles one way continues to still
be favorable. Such uses, however preferable, will still only con-
stitute a saall portion of the eventual sludge use.
-------
DEPARTMENT OF THE AIR FORCE
HEAOQUARTnS LOW** TECHNICAL TWUNINS CCNTC* (ATC1
IOWOT AID FORCS IASI. COLOHAOO 10210
«n»o' uaev , - ;
mmo: Draft EnvlrooMntal Iepact SutMsC for Hetio Hum Sludge Management
Flan
» M|ioul Administrator
0. S. bflroonUl Protection Agency
Rocky Mountain - Prairie Region Till
Suite 900
I860 Lincoln Street
Denver, CO 80203
Attn: Mr Mike Ganseck:
After careful atudy of the Draft Environmental Iepact Statement For the
Metro Denver Sludge Henageaeot Flan of May 1976, we determined that the
tapleasntatloo of the proposed action or alternatives will not impact
upon the aiaaion of loary Air Force Base.
Letter #2
WU» H FEARS, Col, DSAF
Baa* Civil engineer
EPA. Response
Although we agree that neither the proposed actions nor any of
its alternatives will affect the lowry Air Force Base operations, the
question of the availability and use of portions of the Lowry Boabing
Inge is critical to this EIS. By separate ctwunication. EPA has
received a aap showing the current ownership of the Btabiig Range.
Xt is presented and discussed under the Issue IV-1, dealing with al-
ternative eites for the proposed operation.
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UHITEO STATES
ENERGY RESEARCH AND DEVEtQFMEMT ADMINISTRATION
HASH(«erO«. D C. 2K4S
NOV 1 5 W7B
Nr. Ma A. 6reen
tajlMl Mrfiristntar
U.S. Ewrli uinamul Protection
Agency
tan Lincoln Street
tamer, Colorado 80103
Dear Nr. Green:
TMs U la response to your transmittal doted July 28, 1976,
requesting review and coaaent on the draft environmental 1«pact
statement and separate suaaary docuaent for the Denver Netropolltan
Sewage Disposal District's Sludge Management Plan.
He have reviewed the statement and suanry document and have
determined that the proposed action will not conflict with current
or known future Energy Research and Development Administration
program. However, soae discussion 1n the final statement should
be given to the presence of organic pollutants In the sludge,
which In Industrial organic effluents has caused severe problem
during land ampliations In the past.
Thank you for the opportunity to review and coaaent on this draft
statement.
GHLi
W. H. Pennington, Director
Office of KM Coordination
cc: CEQ (5)
(&J
EPA Response
Organic pollutants In sludge, particularly PCB's, banre been rec-
ognized by EPA as * potential problem. Data has been presented by
Metro shoring organic and pesticide concentrations in their sludge.
^ ¦ore coaplete discussion on heavy metals and organic source control
Is found under Issue 1-1.
-------
QATEl
November 12, 1976
TO: Mr. Hike Gansecki
U. S. Environmental Protection Agency
Rocky Mountain Frairie Region
Suite 900. 1860 Lincoln St., Denver CO 80203
FROMi
Letter #4
William F. Sharp Jr.
(a farmer of Adams County)
Rt. 3, Box 7A
Brighton C9 80601
Bear Siri
This letter is my comment on the sludge drying facility proposed for
Adams County location by Metro Sewage Disposal 3ist. 41.
Recent emotional attacks made by Adams County officials and by Town of
Brighton officials are not responsive to the facts of the proposal
and are damaging to the welfare of both their constituencies.
Adams County, although heavily urbanized in its extreme vest and
southwest areas, still remains largely an agricultural county. The
environmental impact statement issued by Metro Sewage District con-
cerning their proposed facility is conservative in its estimation of
agricultural benefits and is cautious about chemical and organic problems
which may limit the agricultural uses of the product.
I have had the opportunity to use digested sludge furnished by the
Sewage District on an irrigated hay meadow (sprinkler irrigation) on
my farm. Actual comparison of yields between cow manure fertilizer
and sludge fertilization of this field shows almost unbelievable
benefits from the use of sludge. The hay yield, with the use of sludge,
was over 3 tines the hay yield after the use of cow manure. Odor
problems were non-existent during and after the application of the
sludge. My home is within 200 yards of the hay field where che sludge
was used.
I hired Brooks Laboratories (a recognized firm of agronomists) to
analyze my soil and submit a written report on what was needed to
bring the soil to its optimum productive capacity. The agronomists of
Metro Sewage District found that their sludge would almost exactly
furnish those elements needed by my soil and in the proper amounts by
regulating the application rate. 1 am presently feeding the sludge
fertilized hay, and it is a superior grade of feed. My animals
eagerly eat it and are remaining in excellent condition. Adequate
irrigation will prevent the accumulation of heavy metals in my soil
according to tests made by the District on their own experimental farn.
During the experimental phase of the sludge program the economic cost
of the use of sludge is, of course, much less than the cose of either
commercial (manufactured) fertilizer or natural cow manure. Even when
Nov. 12, 1976, Mr. Mike Gansecki, US EPA, page two
full costs of production are included in the fees charged for sludge,
the greatly increased yields will make sludge the most economical
fertilizer.
My experience with this material convinces me that the hay and cattle
production capabilities of Adams County would be substantially
enhanced by the location of the sludge treating facility in our
county. The resultant availability of a superior fertilizer without
the cost of long distance transportation would also reduce che cost
of hay and cattle production. The importance of economical food
production to our economy cannot be overstated. The simultaneous
benefit of cheap disposal of what has been a troublesome waste
product makes the District's proposal irresistible.
Sincerely,
William F. Sharp Jr;
WFS/es
CCi Mr. Bill Martin
Metro Sewage Disposal District vl
EPA Response
Hr. Sharp a letter does Indicate the positive agricultural bene-
fits that can be achieved from using sludge. Personal experience
with sludge- applications appears to be the best way to convince
others of its potential value.
-------
Department of Local Affairs
Colorado Division of Planning
Philip H. Schmuck, Director
'1*7*
Richard D. Lann, Governor
Letter #5
November 5, 1976
Mr. John A. Green
Regional Administrator
Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado 80203
*** SUBJECT: Draft Environmental Impact Statement
Metro Denver Sludge Management Plan
Dear Mr. Green:
Enclosed please find consents of the Colorado Division of Wildlife
to the above-referenced Statement.
Very truly yours,
Charles G. Jordan
Senior Planner
[/...
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BMtKMOF WRDUFE
iMill.*MkaNolar
OOW(w II—)
Letter #6
November 3, 1976
Mr. Philip H. Schmidt, Director
Colorado Division of Planning
S20 State Cntaaaitl Bldg.
1313 Sherman Street
Ourtr, Colorado 80203
Dear Phil:
The Division of Wildlife has reviewed the Draft Environmental.
Statement for the Denver Metro Sludge Management Plan by the
0. S. Environmental Protection Agency. We have delayed our
r>. response so that oar field personnel could fully evaluate the im-
pact of the project upon wildlife resources. It is their opinion
that the impact upon existing wildlife will be minimal and that
the dis cuss ion on wildlife is adequate. Any program which will
increase cover in the area will benefit wildlife.
We thank yoa for the opportunity to comment on this program.
Sincerely fours,
nosjh
cc: E. P. Coek
EPA Response
He agree that overall wildlife lapacts froa the project operation
Will be Minor. He shall discuss with the Metro District the possi-
bility of preserving part of the relictual prairie area on the drying
•lte.
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^Board of <*tOater 0oMMi««ioNcr<
IhTM;1 1M VMtOJbsATCW D—; Calowiln 80308 Ptoo.ZZM611
October 19, 1976
Mr. John A. Gr«en
Adminis trator, Region VIII
United States Environmental
Protection Agency
1860 Lincoln St.
Denver, CO 80203
Dear Mr. Green:
tr> Thank you for the opportunity to consent on the draft Environ-
mental Impact Statement, 'Metro Denver Sludge Management Plan."
The Denver Hater Department's staff has reviewed the draft state-
ment and we generally find the district's proposed action to be
an environmentally sound approach to the sludge management problem.
The quantity of water used to transport sludge is mentioned in
the summary, Table B, page 16, and in the text, pages 54, 91 and
112. It is stated on page 112 that .the Denver Water Board
ia the owner of the water transferred front the western slope
and will presumably allow Metro to use these additional waters
as part of the treatment process." The Board is indeed owner
of these return flows. The matter of use, however, is presently
under review and discussion with the Metro staff.
Again, thank you for the opportunity to comment.
Sincerely,
» ¦ •
J. L. Ogilvie
Manager
JLO/em
EPA Response
EPA raised the issue of the potential inter rights iapact and
lapact on dovnstreae users as a result of increased constaptive use
of water in the new sludge process. This letter is critical because
the waters involved are under the control of the Denver Water Board.
This letter does not indicate any concern on the part of the Board as
far as increased use is concerned. This issue is discussed in greater
detail under Issue 1-3.
-------
Distrlot
Metropolitan
MARY B.O'OELL, Cha-rmsn
ALAN L.CANTER,S«cr«tary
BORIS S.VOUKOVITCH. Trwiuw
WILLIAM E.KORSiTZ, P. E.,Manag«r
3tOO EAST BOTH AVENUE
COMMERCE CITY, COLORADO S0022
TELEPHONE 303 230-5041
October 14, 1976
Letter #8 Hr* James w- Sanderson
_______ Regional Counsel
U.S. Environmental Protection Agency
Region VIII
I860 Lincoln Street
Denver, Colorado 80203
Dear Mr. Sanderson:
Enclosed is a copy of a letter received from Harold V. Cook,
Denver Manager of Public Works, in which the status of Denver
controlled Lowry Bombing Range land is set forth.
You will recall that at the time of the public hearings on
the Metro District Sludge Drying Basin Project Environmental
Impact Statement a number of individuals suggested that the
drying basin facility should be placed on the 2,600 acres
of Lowry Bombing Range under the control of the City and
—' County of Denver. It should be obvious that such land will
01 not be available to the Metro District for sludge drying
purposes.
You are requested to make this information a part of the
record of the Environmental Impact Statement procedure, or
at least considered in the final Environmental Impact State-
ment to be issued by the U.S. Environmental Protection Agency.
Sincerely, —>
William E. Korbitt,, VP. E.
Manager
Enclosure
cc: William J. Martin
William H. Page
WEK/j
-------
mm
CITi' AND COUNTY OF DENVER
« H. McNtCHOLS. JR.
Uayer
Letter #9
BEPARTMENT OF PUBLIC TORKS
October 12, 1976
OFFICE OF THE MANAGER
CITY AND COUNTY
BUILDING
DENVER. COLORADO 863)2
Mr. William E. Korbitz, P.E.
Manager
Metropolitan Dewiec Sewage Disposal District "o. 1
3100 East 60th Avenue
Commerce City, Colorado 80022
Dear Mr. Korbltz:
Tour request for the use of 2,000 acres of Lowry Bombing Range land
for disposal of sludge from Metro District Ko. 1 has been revieoed
and the following resulted.
The original granting of the land to Denver was based on the landfill
operation, and it is presently estimated that we have tuenty-five
jears of capacity within the 2,600 acres. ' Your using approximately
2,000 acres would decrease the capacity to approximately five years.
The ongoing sludge drying project is acceptable; however, any in-
creases such as total dedication of the 2,000 acres is objectionable.
Ve therefore deem it necessary to deny Metro District the land for
a sludge drying area.
Sincerely,
itarold V. Cook /
Manager
HVC:kd
EPA Response
The draft EIS discussed the possibility of using the Lowry Bomb-
ing Range by Metro in much the same fashion as they are currently
doing. The obvious question has been raised why the Bombing Range
could not be used for the proposed drying/distribution site. The
issue is discussed in detail under Issue XV-1. However, the avail-
iblity of the site is a critical point in this discussion; the Mana-
ger of the Denver Public Works Department has indicated here that
nee of the greater portion of the city-owned land, which is 810 ha
out of 1048 ha [2000 acres out of 2600] would eliminate the longevity
of the present Denver landfill.
-------
Letter #10
Planning Department EPA Response
June 17, 1976 r
CO
Mr. John A. Green, Regional Administrator
Environmental Protection Agency
1860 Lincoln Street
Denver, CO 80203
Dear Mr. Green:
Adaas County is currently in the process of developing a General
Aviation Airport Site Selection and Master Plan Study which has
identified two primary alternative sites in the very near vicinity
of the proposed Metropolitan Denver Sludge Manageoent Plan Drying
Beds. A potential problem of birds being attracted by flies and
other insects breeding in the drying beds has arisen as an environ-
mental concern. The preliminary draft of the Denver Sludge En-
vironmental Impact Statement indicates that some sort of controls
would have to be developed if a vector problem should develop.
Unfortunately, this does not provide us with adequate information
as to what impact could develop foT aircraft.
It is requested that EPA provide us with any information they may
have on bird/insect problems at similar sludge drying facilities
and particularly, what could or would exist at the proposed site
in Adams County. As our site selection process is rapidly ap-
proaching a recommended site, we would appreciate any input you
may be able to provide.
Sincerely yours,
This itn is discussed under Issues II-9 and 11-10.
j&jhd.
Robert N. Fleming
Planning Di^*^eor
JN:hj
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Letter #11
UNITED STATES DEPARTMENT OF AGRICULTURE
VATION SCNVICC
P. O. Bote 17107, Denver, fblorarto 80217
august 5, 1976
Mr. John A. Green
Htgirml Mrinlatxatxja
ttiited states Bndronnental Protection Agency
I860 Lincoln Street
Denver, (btoaifa 80203
Dear Mr. Green:
Thar* for nonrtlnij as a aagj of the draft Bwironnental Stataaent for
the tfaUu Denser Slurlry Mmwywrrt Plan. We have reviewed the docinrat
and rtw ocnoents:
1. He anryjturt. the nert.im dnallng with description of the proposed action
be placed as Section II of the EXS. It appears illnrpnal to discuss
alternatives and environnental setting before the water knows «bst
action is proposed.
2. A map of the yn'tiumul project should be added to Section IV (Fig. A
fron the Smeary). It is difficult far the reader to jrap back and
forth to orient the elanents of the proposal.
3. Page 91 (Description of the Propound Actions). He description of
the slirty Tivixn L Systaa appears inadequate. Is the pipeline
to be buried car above ground? How moch land will be required for
the rii^iL of-wy? ttsce is tte internediate pwp station located and
what size area will it occupy? Mat roads, nl nunii, utility lines,
etc., will be nrnsned fcy the pipelines?
4. Section 1X1 - Bnrixomental Setting. This section presents awiron-
nental descriptions foe the broad study area, but includes practically
no npprrific site infoonation foe the areas to be physically injected
by implementation of the proposed action—the pipe! Inc righta-of-«ey,
the intermediate ptn^ang station, and the sludge drying and distribu-
tion oenter. la Appendix £, site specific descriptions appear for
the SOX mine, and Iowry Bomhing Range, but not for the sites to be
directly Japacted by the pcimry facilities. He believe specific
information is necessary if the physical impacts are to be evaluated.
5. Section V - Ispacts. Me find the information in this section insuf-
ficient to evaluate the priaary physical inpacts to the land resulting
fron isplanentaticn of the proposal. Qnphasis appears to be wholly on
secondary laynrts resulting fron use of the sludge material after it
is produced. Fran Section HI, page 72, for exarople, we know the site
Continued next page
EPA Response
1. The organization of this EIS follows the approach EPA has devel-
op- in Its regulations for environmental Impact stateaent preparation.
The Um of having an alternative discussion before the actual project
description is to define the proble® end possible approaches to sol-
Ting It before the aoit acceptable choice Is explained. Chronologi-
cally, we believe that this approach aore closely reflects the actual
coarse of events. Since the Municipal client In the PL 92-500 waste-
tracer treatment grants progrss prepares the plan well in advance of
EPA approval, such of the alternatives development is done In advance
of the actual project choice.
2. A wore detailed aap (Figure A of the Suanary) will be added to
Section IV of the final EIS, Voluse 1.
3. Answers to these questions can be found In discussion under Issues
1-2 and 1-4.
4. See Issues II—1 and II-8.
5. Again, see Issues II-l and II-8 and also II-9.
-------
far the sludge processing site is rural and that sane of the site and
adjacent land is used far pasture and dryland farming. Ifte impact to
land use on page 126 is described as ocnpatible with surrounding land
Letter //ll use. niece is no specific information or impacts presented. How
; —~ much cropland, pasture, etc., will be lost along the pipeline route
continued and facility sites and far how long? What is the present productivity
in terms of crops and NM's of grazing? What is the ecomnic value
of products lost?
These same oonraents apply to Section VI.
6. Sunnary.
H>e obvious weakness throughout the EIS is failure to present specific
information concerning the sites upon which the systan will be con-
structed.
ro
O
This weakness occurs continually frcm description of the proposal and
environmental settings through iiqpacts.
We suggest more site specific information be included in the final state-
ment.
We appreciate the opening quotation frcm Hugo's Lee Miserablee
appropriate.
very
Sincerely,
M. 0. Burdick
State Ctanservationist
y
Council an Environmental Quality (5 copies)
R. M. Davis, AfrriniBtrator, SCS, fbshington, D.C.
Office of the Cbardinator of Bxvironoental Quality Activities,
Office of the Secretary, OSOA, Washington, D.C.
EPA Response
6. He appreciate the cranents on the draft EIS froa Sell Conser-
vation Service. He are soaevhat perplexed by the lack of SCS consent
on any sludge use issues.
-------
FEDERAL ENERGY ADMINISTRATION
REGION VIII
107S South Yoi«on
P.O. Bob 26247. Beimor Bremen
Lake^ood, Colorado 302i6
August 18, 1976
Mr. John A. Green
Regional Administrator
Environmental Protection Agency
Region VIII
I860 Lincoln Street
Denver, Colorado 80203
Dear Jack:
The Federal Energy Administration Regional Environmental Specialists
have reviewed the Draft Environmental Inpact Statement (Draft-EIS)
on the District Sludge Management Plan dated May, 1976. The FEA
Mould like to submit the following consents on your proposal:
A. We concur that alternative two, with site B-2, is the
Ideal choice, based upon the Information reviewed, with alternative
seven as a passible backup. It Is felt alternative two Is the best
suited choice for the following reasons:
1) If built as planned, the project will require no external
energy resources except electricity for puaps and general in-house
use, and some petroleum for dried sludge removal stockpiling and
miscellaneous use. All process heat, according to the Draft EIS,
will be provided by methane produced In the anaerobic digestion
process.
2) It appears economically sound, since the system will not
be dependent upon inflationary fuels and chemicals except for those
mentioned above.
3) Slurry pipelines, according to most studies, are extremely
energy efficient and definitely will produce major energy savings by
their utilization.
*) It will provide a valuable product for farm use, and if
marketing conditions slow down, will provide injection fertilization
for lands owned by the city. These fertilizer products could
effectively save thousands of barrels of oil by replacing petroleum-
derived fertilizers.
Continued next page
EPA Response
QVe are in general agreement with the FEA as to the positive aspects
the proposed project. Point # 4 under A. indicates that the sludge
product will be available for injection fertilization by the city.
As currently planned, only dried sludge vill be available, and it vill
either be distributed to private or municipal users, or else buried at
the Denver landfill. This does not detract from its potential use-*
fullnes as an energy-saver.
-------
2
B. The following questions are ones concerning FEA:
t 1) Site B-2 appears Ideal for creating less potential
Letter f LZ, ¦ citizen objections, but considering energy and economic aspects,
continued 1 Q) "Ore thought wight be made In locating the plant closer to the
^ sanitation treatment facilities, especially 1f 1t can be demonstrated
the operation will emit little or no odor. In any event, any site
chosen will likely be surrounded by housing projects 1n the future,
so even B-2 can be expected to create sone objection by developers.
2) Die treated sludge, according to your report, will
contain a rather high concentration of heavy netals. These will
®be found In compound fbrn, with many being water soluble; consequently,
what degradations can be expected on surface waters and ground waters
fn the Injection and drying areas? The classic example In this area
1s the Rocky Mountain Arsenal Lake "F" that has from time to time
caused contamination of surface waters and ground waters.
0 3) The sludge could have a high sand content. How will
slurry lines and pueps be built to keep mechanical abrasion to a
¦inlmua? What backup system will be available If slurry lines do
need repair?
4) According to your figures, the sludge will have a
rather high pH. Is there any plan to possibly reduce this pH to
make the sludge more useable 1n areas already experiencing high
alkaline salt problems?
rv>
^ 5) The system seems Ideal for moderate weather conditions.
Ifcat provisions are being considered to dewater during periods of
freezing weather?
9
®
6) Have there been any long-range studies regarding sludge
Injection 1n winter months? If Injection use proves limited for
winter use, what alternatives have been proposed to dispose of the
sludge?
The FEA 1s extremely Interested 1n systems such as this one that
•re, for the most part, energy efficient and produce a useable
byproduct. Mhen one considers the many commercial fertilizers
produced from petroleum products and the finite future of these
products, it 1s encouraging to see processes being planned that
potentially could save thousands of barrels of petroleum and still
provide a valuable replacement product.
Thank you for the opportunity to coament on this fine draft statement.
,£1 merely,
cc: Or. Robert Stern (NFEA))^ Regional Administrator
1 Dudley E. Faver
EPA Response
QA discussion of alternative sites is discussed under Issue IV-1.
la not possible to guarantee that there will not be sone odors
froa the project operation.
fjj Generally, heavy metals are sparingly soluble. They axe also
irfgwiy p on clay soils. pH is also critical in determining
the solubility of metals. The locally alkaline soil pH tends to
favor precipitation of nose heavy metals. In general, we expect most
of the heavy aetals to remain hound up in the top layer of soil whan
asUad, See discussion under Issue 1-1 and V—1.
Metro has indicated that they expect no problems with sand in the
ilfaatad sludge (Reference 1). Sand and grit have never been exces-
sive in Metro sludge, and grit removal units will remove any poten-
tially harmful quantities of this material before it is punped. The
sladge transport system will consist of one 12 inch and one 10 inch
pipeline with four props at both a Bain and booster pump station.
Crossover valves at various points along the route will allow seg-
aaats of either pipeline to be used while repairs are being made on
the other line; similarly, two of the four pumps at each station have
sufficient capacity to handle the entire sludge flaw in case the other
two pumps need servicing or replacing.
tsJ The presently disposed sludge at the Lowry Bombing Range does
live a high pH 01-12). This however, is done because of the effec-
tiveness of using high pH's from added lime to kill pathogens. The
pi sf emaerobically digested sludge will be closer to a neutral pi;
this sladge is what will be applied to area croplands after being
dried aad stockpiled.
Cy The system is designed to allow for sufficient storage capacity
MClag winter weather, so that winter drying will not he necessary.
Ike design assises a 9-month drying period. During the winter, sludge
will simply be pumped and stored on site. There will be sone occa-
sismml drying even during this period, however.
®° attempt will he made to Inject sludge during the winter months.
Wtro will have a research and demonstration area on site; they could
Investigate this possibility, if there is same interest.
-------
United States Department of the Interior
GEOLOGICAL SURVEY
Box 25046
Donee Federal Cesser
Dcawt, Colorado 80225
Mall Stop #415
Water Resources Division
Colorado District
August 27, 1976
Regional lililnltntor
U.S. tninoaaul Protection Agency
Rocky Hmailefii Prairie Region VIII
Suite 900
MM Lincoln Street
iwm, Colorado 80203
Dear Six:
Iftn reviewing the draft wliia—iti) lapact tutcmt for the Metro
¦smr Sludgy Management Plan we concur Kith the Information and con-
rlnslaes presented with regard to the water resources of the anas
itlaraeaad The 0-S. Geological Survey baa been working at the Lovry
lsdilai Ha pi disposal. area la cooperation with the Metropolitan Denver
Bene US Wspssal District In order to asasss the effect of waste disposal
activities an gcamd water quality. Our findings agree with those
pwaatad a* pages 170 and 171 of the BIS. The Bis correctly <*aphssis«s
Che
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DEPARTMENT of HEAi-TH EDUCATION. AND WE-p"Af?c
=»£.". 0«* v:
fEOra i_ -pr C£ '
ceNve«
,.:ng
--SETS
302C2
August 30, 1976
Mr. John A. Green
Regional Administrator
Environmental Protection Agency
1860 Lincoln Street
Denver, CO 80203
Dear Mr. Green:
Thank you for the opportunity to review the draft Environ-
mental Impact Statement (BIS) for the Metro Denver Sludge
Management Plan.
It appears that the impacts expected to result from the pro-
posed project and reasonable alternatives thereto have been
adequately addressed.
Jely yours,
R. Garfield
al Director
cc-. Office of Environmental Affairs,
SEK, Washington, D.C.
Council on Environmental Quality
Washington, D.C. (2 Copies)
EPA Response
Ro comaent
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MRS. RONALD O. WARNER
Miwi i. cctowADQ aom
September 1, 1976
Letter #15
Regional Administrator
U.S. Environmental Protection Agency
Rocky Mountain-Prairie legion VIII
Suite 900
1860 Lincoln Street
Denver, CO. 80203
RK: Metro Denver Sludge Management Plan
Gentlemen:
ro
cn
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Regional Administrator
U.S. Environments! Protection Agency
Page 2
Letter #15.
continued
®L Colorado Archeological Society and has for years maintained an interest
la tbe history of the area. He has valuable arrowhead collections obtained
from the the lands bordering this site and shares his knowledge and back-
ground with all. Re,indeed,Is part of the history of the area.
He hare lived here well over 20 years, and have always gloried in the
wide open spaces surrounding us. He do not feel Isolated or abandoned
by society. City people have often asked for permission to walk across
our fields just to enjoy the feeling of openness It gives the*. This
could well be established, and sore to the benefit of the County, and
_State, as an "open space area".1
In closing, we note your E.I.S. takes advantage of quotes from Victor
Hugo... we would like to quote from the dedication of a book entitled
"Our Side of the Mountain" written by a local resident, Etna Michell,
who has earnestly worked to preserve the aesthetics and history of this
area of Colorado.
"....to the pioneers who had the foresight and stamina to endure
the hardships necessary to establish and preserve a heritage for
IV> this and future generations.
o\
Is this what Is to be covered with sludge?
Sincerely,
' >• "V
Lillian M. Warner
(Mrs. Ronald D.)
EPA Response
The point on historic resources in Appendix C, page G-3, simply
compares this sice with other sites. He doubt tbe surveyors were
awsre of the presence of the homesteader you refer to. This resident
•till has the right to object to the present evaluation of archaeol-
oglc and historic resources in the area.
\SJ Although there will be occasional odors, the nature of the oper-
ation will be such thst there should be very little change In land
uaes in the site vicinity.
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Letter #16
DEPARTMENT OF THE ARMY
OMAHA DISTRICT. COUP* OF tNftlNUW
*•14 u.s. post optics mo comrr houm
OMAHA. WtWIOWU MIOS
WXD *" 3 : 2 September 1976
\1%IH
Mr. John A. Green
Bntlnnil Administrator
Oblted States Sjvli onuutal Protection Agency
Beglni TOX
i860 Margin ftmt
Sbtrt! Colorado 60203
ro
>4
Dear Mr. Green:
Oils
to your notice of 28 July 1976 , Draft EIS, Metro Denver
nau
Oils action will have 00 significant impact on tar existing studies or
projects of the Oaaba District. Thank you for tbe opportunity to ewi.ut.
Sincerely toots a
X loci
Special notice
S. TOUSBUfiKX, P.E.1
Chief, PI inning Division
SPKIAL too.
It Is noted Oat this project Bay inrolre sork la or adjacent to one or
several streaas. Utter under Section 10 of the Hirer and Harbor Act of
Nsrefc 3, 1899 (30 Stat. 1151; 33 BSC k03) or under the prorlsloa of Section
MA of the Federal Hater Pollution Control Act Aaendaent of 1972, a per-
¦lt pay bt required fra the Carps of Engineers prior to this start of
construction. It your are not fsaillar with the permit regulations,
additional Information can be obtained frca this office upon reiu-st.
Please write to:
District Engineer
ttnUt District, Corps of Engineers
ittWs Operations Division
folk (I. S. Post Office and Courthouse
Qasha, Bebraaka 68102
EPA Response
We shall lnfora the Metro District that a Section 404 Perait
should he applied for. there may be seme question whether a Section
404 Perait would apply, since these streaas adjacent to the site are
intermittent and normally contain no flow.
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Bagional Administrator
U.S. E.P.A.
Rocky Mountain - Prairie Region VIII
Suite 900
I860 Lincoln St.
Denver, Colo., 80203
Dear Sire:
He know that Denver Metro has a problem to dispose of their sludge;
but shouldn't sore testing and experimenting be made with it, as to its
value as fertilizer for this entire area, before good fan land is con-
doned and taken for its drying pits.
They keep saying it is used extensively in the London, Chicago areas,
but they have vote aoietuxe there than we have in this area. What about
a couple of experimental plots that we made in this Bennett area? The
falser who used it one year, his crop practically burned up, while the
farmer across the road had good wheat. Why didn't that farmer continue
to use it? Vhy has he changed to a chemical fertilizer? Most farmers
in this area use their stubble and summer fallow as their means of ferti-
lising.
The area which they have chosen to dry it in has a large run-off when
we have any excessive moisture. Come out and see for yourselves after we
have hard rains and run-off from snow. See the ditches and washes it makes
on the land. Bow ouch damage will it do to the water basin, to the wells
in the area and to the farmers further north as it flows that way.
There is bound to be an odor from the area, and it will certainly be
carried to other surrounding areas hy the winds which we have. Before Barr
Lake was cleaned up we could smell the odor from it when the wind was in
the right direction. I live near the Bennett settling pounds and the odor
from it is teTTible When the wind is right. It is supposed to be water con-
trolled and is a small area. The drying pounds there of Metro's would be
auch larger, so the odor would be much stronger and cover a wider area.
The winds which we have in this wide open area would certainly carry
particles of sludge over a wide area. Do we have enough moisture to handle
the minerals which are in the sludge? I have been told that too much sludge
fertilizer helps to shall I say, run the soil together.
The area they have chosen is certainly not close to any markets, or
very close to transportation to take it to markets. It is 15-20 miles from
a market snd rather poor transportation means to get it to a market. Dry-
land is not a market for it.
It will certainly devaluate the value of land in the area, and
take a lot of tax-mooey from Adams County.
What were the results of the tests that were made on this land this
ammmzl I feel those results should be made to the farmers whose land they
were made on. I strongly feel that there are better and cheaper says for
Continued next page
EPA Response
QA discussion of research need surrounding this project, and the
rel of uncertainty Involved is found under Issue 11-11.
Cj) The tests referred to in this letter were made in 1973-4 on dry-
land fan areas. The tests results indicated that there were signifi-
cant benefits to utilizing sludge, as well as a considerable uptake
of heavy netals. These tests and their results are discussed in Issue
I*-l. Metro's present position is that because of the low nutrient
requirements on dryland areas, Metro sludge will probably not be used
to any great extent on dryland farm areas.
f3J Wholesale runoff including sediment could move undesirable metals
and pathogens into local streams on dryland areas. However, Metro's
preferred agricultural areas would be with Irrigated farming, where
tailwater control on irrigated lands is likely to be practiced, or at
least where mild slopes would not pose such a runoff hazard.
UJ Shallow aquifer (alluvial) wells could conceivably he affected hy
Ieachate from the drying site itself. EPA will therefore require
lining of the basins to minimize Ieachate movement (see discussion on
Issue 11-2).
8 Odors from the site are discussed under Issue II-3.
Airborne transport of sludge at the site is discussed under Issue
II-5.
QThis letter indicated information to the effect that sludge appli-
rions would cause soil clogging. EPA's best information is that ap-
plied dry sludge generally has the opposite effect; i.e., that the
organic material added to the soil increases soil porosity as well as
water retention.
I8J This issue of sludge marketability and distance from markets is
discussed under Issues 11-14 and V-4.
(?) See Issue II-4 on the question of land values.
DO) The tests performed on site 3-2 during the summer of 1976 were to
collect soils, permeability and structural engineering information.
CH2M-H111, the consulting engineers for Metro, have prepared a Geotech-
nical and soils Report containing this Information. Much of the rele-
vant information is discussed under Issue II-2, on groundwater Impacts
at the site.
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Letter #17,
continued
Metro to dispose of the sludge than to use it for fertiliser*
How can the drying pits help but contaminate the water, the air and
the surrounding environment? They have a long lease on the bombing range,
why not continue to transport it there?
Hhere are they going to get the water to bring it to this chosen site?
There are no irrigation wells in this area, which would help them.
I have lived and farmed in this area for 35-40 years. We have enjoyed
life in this area. I can certainly say I hate to see part of our good farm
land which we have owned for almost that whole time, taken and used for this
purpose.
Tours truly,
ro
to
/s/ Catherine M. Mundell
EPA Response
|UJ Recycling of sludge for agricultural use is probably Che most
economical way to process sludge, If the difficulties can be resolved.
Chapter II in Voluae I of the EIS demonstrates the cost-effeetivness
of this approach.
Q2J Problems with the present operation at Lowry Bcabing Range are
aXscussed under Issue III-l. This syatea could continue, but is ex-
pensive and has no agricultural benefit. The use of Lowry for the pro-
posed operation is found under Issue IV-1.
Q Metro proposes to construct a snail veil at the site for potable
ufe. Water for irrigation and research will be pumped occasionally to
the site and stored in the irrigation iapouttdaent (see Figure 12,
Volvc I, Chapter IV). This water is needed to occasionally purge the
sludge transport lines. Hater impounded on-site during rainfall events
will also be puaped back to the reservoir.
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typed from handwritten letter.
September 6, 1976
United States Environmental Protection Agency,
Region VIII,
1860 Lincoln Street,
Denver, Colorado, 80203.
Bear Friends,
This letter is written in regard to Denver Metro Sewage District's
proposed plan to pipe and dry their sewage on a 900 acre site in Adams
County. Being a faraer near this area, I have serious reservations on
boo this would or could Jeopardise our daily lives and ultimately our
future for continuance in farming in this area. I, as well as many other
farmers, are not enthusiastic to have an unproven experiment of this
size thrust Into our area which as you well know is subject to dry
weather and wind erosion. Also, with Denver's rapid growth now and in
the future, we fear that the proposed 900 acre site would shortly become
Inadequate and the outward expansion in this area would mushroom despite
Metro Sewage's past promises that 900 acres would be all they need.
X will not take more of your time but will ask for your fair and
honest consideration of our problem - thank you!
Sincerely yours,
Donald A. Uailes
Bos 156
Strasburg, Colorado 80136
EPA Response
^ The issue of wind erosion at the site is discussed under Issue
Q Capacity of the proposed system is found under Issue 11-12.
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Letter #19
u
©
<3>
®r
Bt.l Box 25
Bennettt Colo. 80102
September 7, 1976
Baglonal Administrator
U.S. Bwlro—sntal Protection Igency
Rocky Mountain - Prairie Bsgion 8
Suite 900
1860 Unco In Street
Denver, Colo.
Dear Slrt
Z am writing la regard to tea proposal of Metro
Sewage District of buying private land la Adams County
to try oat t^elr sludge drying and selling Idea.
As I reside within one alls of the proposed aite,
1 a* opposed to the purchase of the land for t&e following
masons*
I question Metro's need to take private land when
they hare not thoroughly investigated the possibility
of using the bombing range. The private land la question
Is productive farm ground which will be difficult to
replace by the Individual land outers.
Secondly I feel your report brings 19 the serious
question of possible contamination of the underground
mater supply. At the present tine the water in the basin
Is safe for htaan consumption, but will It reaain so
if the sludge Is placed taere as Hetro plans f As you
pointed out In your report, it la a closed water basin
that affects a large area.
Shirdly I feel that since tu.a Is a pilot pro gran,
vie research needs to be done to prove that sludge
can be used by dry-land farmers, and if it will be used
by tbee in wahat amounts.
Hi your report you also state the possible bad effects
on certain broad leaf plants, xou also state that turf
farms will be big users, but the area selected is In the
middle of dry-land farms which tolerate only a minimum
of fertiliser. The nearest turf fan is approximately 20
ailes any, and It is a small one.
1 believe there is insufficient evidence to prove
that dryland operators at* going to eagerly buy the
district's products.
1 feel that tue district ehould attempt to develop
this product on the bombing range, xhan if there la
a market select a site which will be centrally located
to the aajor users.
I also question the effect the drying and stockpiling
Continued next page
EPA Response
Dee of the Lowry Boabing Kange for this project is discussed
S&der lame IV-1.
0 Po
L2j Potential groundwater contamination at the site is covered under
issue n-2.
Q Experimental nature of the project is covered under Issue 11-11.
M Market distance is evaluated under Issue 11-14. Ho one site can
Be close to both the turf feras in the northeast Platte River area
and the area along Cherry Creek.
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Letter #19,
continued
©
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Letter #20
September 9i 1976
Regional Administrator
U.S. Environmental Protection Agency
Rocky Mountain-Prairie Region VIII
Suite 900
i860 Lincoln Street
Denver, CO. 80203
RE: Metro Denver Sludge Management Plan
Gentlemen:
Having read the Draft E.I.S. I feel a distinct need to relay my
feelings about this proposal.
I reside appox. 5 miles northeast, of Site B2 my residence here
began W7 years ago, talcing an active intrest In community affairs
co I have become quite familiar with this area.
go
P I have attended all puolic meetings held by "Metro" tryed to compre-
I hend the printed material they have supplied. I have served on the
Qjl Citizens Advisory Committee for over two years, missing only one ®eet-
ing last July 19. However my name is omitted from your list pases
I 199-300. I am flattered Metro would omit a member with the probable
L best attendence.
In my conversations with Metro personnel, they have convinced me they
are faced with a monumental problem, I concur completly with the in-
tent to turn negative to positive action. However to move a problem
to a different location Is not a solution, Metro research at this
time does not justify this project there are to many unresolved items,
too little dedicated consederation.
Site 32 Is predominantly located in a closed water basin, I am sure
you realize the unique problems in this kind of area, without a pro-
ject such as Metro proposes.
The location is not energy efficient considering the distance from
the Commerce City facility and in the opposite direction from the
market for this marginal product.
Continued next page
EPA Response
on our reading of the Advisory Group attendance records,
are certain Metro's oaission of your naae was inadvertent.
.2 J The issue of goundvater contamination and the "closed basin" under
Ene site is covered under Issue II-l and II-2.
3y Even given the distance of site £-2 fro* the potential users, the
proposed systea is still aore energy efficient than the present *ethod
of operation and other alternatives. Also, see letter froa Larry
Brown, MUX Mining, on econsaics of hauling sludge (Letter #1). See
Issue 11.14.
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Regional Administrator
U.S. Environmental Protection Agency
Page 2
Forced aquisition of private owned land in a state that is one half
public owned, Lowry Bombing range is about equal distance as site E2,
another the Rocky Mountain Arsenal, either or both of these locations
could and should be used in a concerned and dediciated research pro-
gran to prove the worth of the project as to the safety of the sur-
rounding area, value and market of this proposed operation.
The total loss to the Adams County area will not be measured by the
2,000 acre site and ve have no assurance more land will not be ccndemed
at a future date,the greater loss will be the devaluation of the sur-
rounding area, witness Draft £.I.S.
Figure 16 page 136. In regard to this summary I disagree with the low
rating given air quality also no mention of wind movment of dried
material.
Metro management has acknowledged their first proposal would have been
a complete disaster, if the Adams & Veld county residents had not
resisted, that project would have been instituted several years ago.
I sincerely believe the present proposal is lacking proof of success.
I appreciated the appearance by Mr. Qanseki at Metro's Advisory
Committee meeting sometime ago, I would be pleased to meet with E.P.A.
personnel at anytime.
Sincerely,
Lawrence E. Wailes
rw
EPA Response
©
Site alternatives are dlcussed under Issue IV-1.
©
Future capacity needs are discussed under Issue 11-13.
0
Wlndbloving At the site is covered under Issue 11*5.
Q Metro's earlier proposal as presented in 1972 might well have
canned problems free over supply of nitrogen on dryland areas. Metro's
present proposal is such mate flexible, and even if dried sludge were
to be landfill, the costs would be less than the present operation.
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THE STATE HISTORICAL SOCIETY OF COLORADO
Colorado State tfuna, 200 Fourteentk Atmum, Dtnetr SOX3
September 13, 1976
Mr. John A. Green
Regional Administrator
United States Environmental Protection Agency
Region VIII
I860 Lincoln Street
Denver, Colorado 80203
RE: Draft Environmental Impact Statement for Metro
Denver Sludge Management Plan
Reference is made to the above statement drafted by the
Envircmental Protection Agency.
Based cm the information contained in the statement, no
oj historical properties were found within the project area.
In addition, we have reviewed the Colorado Inventory of
Historic Sites and the national Register of Historic
Places for information about known properties located
within or near the project area; none were found in ei-
ther listing that would be affected. Therefore, insofar
as historic properties are concerned, the Environmental
Protection Agency has met its responsibilities with re-
spect to 36 CFR 800. The Office of the State Archaeolo-
gist of the State Historical Society will reply separately
with respect to the possible existence of archaeological
resources in the project area.
FOR THE STATE HISTORIC PRESERVATION OFFICER
Cuiator, Historic Preservation
EPA Response
Archaeology issues on this project have been discussed vlth the
State archaeologist. See Issue 1-4.
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Department of Local Affairs
Colorado Division of Planning
Richard D. Lm, Governor Philip H. Scfcauck, Director
Letter #22
September 13, 1976
Mr. John A. Green
Regional Administrator
Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado 80203
SUBJECT: Draft Environmental Impact Statement
Metro Denver Sludge Management Flan
Dear Mr. Green:
The above-referenced Environmental Impact Statement was received and distributed
for review by state agencies In accordance with the National Environmental Policy
Act. All responses are enclosed herewith.
The primary state concerns may be summarized as follows:
Water quality. As discussed by the Department of Health and Colorado Geological
Survey, the questions of potential aquifer pollution have not been sufficiently
answered. Both agencies offer constructive suggestions for monitoring and
mitigation. It should be recognized that the water quality considerations have
Implications on future land use plans for the area which currently foresee con-
tinued agricultural uses. Aquifer pollution would likely alter that projection,
causing a loss of a valuable agricultural resource as suggested by the Department
of Agriculture.
Water resource allocation. The enclosure from the Division of Water Resources
sets forth legal water use criteria which must be met. In addition, however,
the draft statement Inadequately evaluates the environmental effects of water
resource consumption. A content near the top of p. 112 suggests that the EIS
treats only the legal constraints of water use rather than the environmental
and economic Impacts. In a water deficient area it Is Important that water
conservation be a major consideration for any development proposal. Therefore
we feel that the treatment of alternatives In the Final EIS should consider the
. alternative demands upon water use.
I Agricultural Impacts. From the conments of the Department of Agriculture, it
is apparent that the EIS does not adequately weigh the positive effects of
providing fertilizer and maintaining the ecological life cycle against the
I negative impacts of loss of agricultural land, water use and pollution, and
CO
cr>
©
Continued next page
EPA Response
^ See discussion on groundwater problems under Issue II-2.
Qln the discussion on water rights (Issue 1*3 ), a discussion of
t aggregate environmental Impacts is Bade. The overall impact is
expected to be minor.
QThe agricultural impact expected as a result of the B-2 site
luisition is found under Issue II-8. The overall balance is also
discussed here.
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Eu» ltwental Protection Agency
Be: Metro Denver Sludge Management Plan
September 13, 1976
Page 2
potential deterioration of the quality of life In the commlty selected for
drying sites. These should be objectively balanced to determine the net
^impact on agriculture.
In addition to the foregoing comenta, I wish to point out that on p. 81 of
the EIS, the third sentence states that the Colorado Land Use Commission has
jurisdiction for Managing state lands. I believe that the agency intended
, ns the Colorado Board of Land Commissioners.
Thank you for the opportunity to consent on this proposal. I look forward
to receiving a copy of the Final EIS.
Very truly yours,
Senior Planner
Reviewed; " . /<
Philip B. Sctauck.
Director, State Clearinghouse
CGJ/vt
Enclosures
cc: Department of Health
Department of Agriculture
Colorado Geological Survey
Division of Hater Resources
State Archaeologist
EPA Response
41 This correction has been made in the text.
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COLORADO DEPARTMENT OF HEALTH
42D E.1TTH A/BMJE DBMVS^ B0E2O PMOJE 3B0 BM1
ANTHONY ROBBINS.M.D..M.P.A. EXECUTIVE DIRECTOR
Septeaber I, 1976
Mr. PhirSdawidc, Director
State Clearinghouse
520 State Centennial Building
1313 She nan
Denver, CO 80203
RE: DC IS - Den war Metro Sludge Management Plan #76-132
Dear Mr. Schmock:
The Colorado Department of Health has reviewed the DEIS for the Denver Metro
Sludge Management Plan and has the following coarsen ts:
Air Pollution Control Pi vision
I. it was determined that the air quality impact of the proposed project was
adequately addressed in the DEIS. We would concur that the most si^iificait
Missions from the sludge drying facility would be fugitive dust and odor.
Although no specific permit is required, we would recaraoend that a fugitive
dust control plan be implemented in order to reduce these emissions to the
t greatest possible extent.
2> Standards for the emission of malodorous compounds are covered by Air
Pollution Control Coanission Regulation No. 2. As was stated in the docu-
ment, a definitive plan for the control of malodorous emissions must be
submitted to the Air Pollution Control Division for review. We would agree
that the emulative air quality impact upon the proposed project would be
minimal.
Engineering and Sanitation Division
1. The EIS mentions the addition of pesticides (Organophosphates) to sludge
at the plant to prevent and control Insect populations in sludge drying
beds. Nothing was mentioned for insect control In the impoundment ponds,
¦"•e report and plan should include a contingency plan for control of insects
and rodents. There may be problems relative to birds feeding on insects
and using the sludge ponds.
2. The alternative of drying beds wi th underdrain systems to collect and
process the supernatant was not included in the alternatives investigated.
This alternative could minimize the issues of dissolved salts and heavy
metals.
Continued next page
EPA Response
fu EPA will require that a fugitive dust control plan be developed
la the plans and specifications for this project. Metro has Indicated
by 11—11111 ill Inn of June 9, 1977, the current plans for dust control:
"the solids stockpile area* are provided with strategically locat-
ed fire hydrants for use in wetting the solids stockpiles at
tlae of high winds to prevent wind blowing of the material if
this should prove to be a problem. Hater used for this operation
is that which is pumped to the drying and distribution canter
from the Central Plan for cleaning the transport system pipline*
and also runoff water collected from the drying and distribution
site."
© EPA will require as a Step II and III grant condition that the
Hetro District submit a plan for control of malodorous aiaslons to
the Colorado Air Pollution Control Division.
QSee discussion in Issue 11-10, concerning vector control. EPA will
luire as a grant condition that a vector control plan be developed.
\AJ The alternative of using underdrains at site B—2 is costed in the
discussion on groundwater quality control alternatives (Issue IV-2).
-------
Nr. Phil Sdnuck
September I, 1976
Page 2
3. Dried sludge should not be applied to root crops or leafy vegetables that
could be eaten ra« unless the sludge has been stored for a minimum of one
year.
It Is agreed that anae rob leal ly digested sludge is less odorous than raw
or activated sludge fran municipal treatment plants. Hany factors such
as precipitation, temperature, wind, soil permeability, evaporation rates,
can influence odor conditions. This sludge nay not have objectionable
odors in coqparitfvely snail amounts. However, it is difficult to predict
wherr^ considering SOO acres of drying beds.
Water Quality Control Division
1. Our one remaining concern with the plan is the proposed use of unlirted
drying beds. The ElS recojpilzes this concern also, and provides proper
mitigating measures (p. 181, 182). Me strongly urge that the proposed
project be smmended to Include i"pervious lining of the beds and some type
of uidsrdrainage.
2. Ml other elements of the project are environmentally sound from a water
qua!|ty aspect.
Thank you for die opportunity to review the DEIS. Please contact us if any of
our comments require clarification.
Wary truly yours,
FOB PI HECTOR, WATER QUALITY CONTROL DIVISION
t«V v A
/
Jonathan Scherschligt, P.E.
Planning Engineer
Water Quality Management Planning Section
JS/ab
cc: Bob Stek
John O'Neal
Nike Ganseckl, EPA
EPA Response
EPA will adopt this recommendation In Its Mitigating Measures
ticm. Also see discussion on Sludge Use Constraints (Issue V-l).
G/ He generally agzee that with 240 ha (600 acres] of drying beds,
there are likely to be occasional odors. A definite odor vas noticed
at the San Jose, CA drying beds with a strong wind, mostly from re-
cently filled basins. See discussion under Issue I1-3.
EPA sill require lining of the drying basins to minimise leachate.
Issue XI-2. EPA will also require an emergency plan to ptap ont
groundwater in the event significant concentrations of water pollu-
tants develop under the site. He do not think that any form of under-
dralnage is feasible because of costs (see Issue IT-2).
0.
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, OEm'°I,(;w
..... t^llJ
R.^M.ri o. **""* — -"<«*»•> *"' Ar*.ruiTU«AL CO^J.SSION
Govt""** Xj \ \v' < M ClAMrtce Stone. Cento?
C**V ' V '¦•>¦--
Resource Information Specialise
SUBJECT: Colorado Department of Agriculture Review of the Metro Denver
Sludge Management Flan Draft EIS
COMMENTS ON THE TECHNICAL ACCURACY OF THE EIS
The EIS was reviewed in depth by staff from the Inspection and Consumer
Services Division of this department. In general, the technical accuracy of
the document is considered to be very high. Four specific comments follow:
1. The value of the dried sludge as fertilizer (pages 122, 164 and elsewhere)
say be. overstated since (a) there is no present shortage of fertilizer,
and (b) the cost of time, equipment and energy in applying a low analysis
fertilizer vs. a high analysis commercial fertilizer is not considered.
Ia addition, food producers using the sludge would need to comply with
additional regulations of the State Department of Health and the Food and
Drag Administration. The value of additional time spent in complying with
these regulations (filling out forms, meeting with inspectors, etc.) should
be deducted from the gross value of the sludge to obtain a net value.
2. On page 20 (Table 2), the use of sludge materials for cattle feed is con-
sidered. Under current state feed and fertilizer regulations ("Rules and
Regulations Regarding Processed Animal Haste Products," Colorado Department
of Agriculture Regulation No. 6-1) this is not permitted at the present
time.
3. On page 82, It is stated that nitrogen fertilizer is manufactured in the
state. According to our Inspection and Consumer Services Division, there
is no such fertilizer production In Colorado at this time. Also, Colorado
potash manufacturing is Insignificant.
A. On page 84, it is stated that "the fertilizer for the agriculural economy
of the state Is presently in short supply..." According to the Inspection
and Consumer Services Division, there is no such shortage at the present
time.
Continued next page
EPA Response
1. Tine has a way of making EIS' 6 outdated; at the time of preparation
of the draft EIS, an energy crisis was still a reality, and there were
concerns about shortages of natural gas-derived fertilizer. For the
short-term at least, this is now not a problem. EPA does agree that
there is a cost associated with applying a low-grade fertilizer such
as dried sludge versus a high-grade fertilizer. The discussion under
Issues 11-14 and V-3 discusses such added costs. He do not think that
bureaucratic forms and regulations should be realistically considered
in cost terms or constraints; such forms and regulations could crop
up anywhere.
2. The discussion on sludge use under Issue V-l (constraints) and
V-2 (Control of applications offsite) recognises that this is not
permitted.
3. This has been corrected.
4. See comment 1. above. This change has been noted in the text.
-------
Charles Jordan
10 Septcabcr 1976
Letter #24, Page 2
continued
ADDITIONAL COMMENTS
The disposal of sewage sludge may be considered from several perspectives.
Including the following:
(a) disposal of undersirable materials
(b) inproving water quality
(c) increasing food production; food and feed crops, grasslands
(i) application of dried sludge as fertilizer
(11) application of wet sludge, both for fertilizer value and
water content
(d) inproving soil fertility in non-food applications (parks, sod farms,
etc.)
(e) mined land reclamation
(i) application of dried sludge as fertilizer
A (li) application of wet sludge, both for fertilizer value and water
' content
(f) production of methane gas for commercial use
(g) quality of life and property values in the area surrounding the
drying site
flhe EIS considered most directly objectives (a), (c)-(il), (d), and (e)-(ii), at
least lmplldty. However, to what extent is the project compatible with the
other objectives listed above? More specific consents and questions follow.
(a) laproving water quality. What Is the location of the drying sites
in relation to groundwater and surface waters? Said another way,
were the drying sites selected to mininize possible adverse effects
to water quality?
' (c)-(ii) Increasing food product ion through wet slcJge application.
Setting aside, for a moment, important problems affecting the potential
use of wet sludge for growing crops and forage vegetation, such as
heavy metals, salt buildup, pathogens, etc., what Is the future
potential for increased irrigation acreage near the east of Denver
if maximum food production becomes important In the not-too-distant
future? How many acre-feet of water per year would be available for
this purpose? Where are the lands east o£ Denver with high inherent
agricultural productivity that are currently underutilized because
of a lack of water? Were the drying sites and pipeline corridors
chosen with these lands in mind?
Continued next page
EPA Response
Tour ci.i—rnt is an excellent one, although quite complex to answer,
r general response to the question you posed as to the extent of
project comparability with objectives (a) thru (g), would be as fol-
lows: The project is generally Intended to further these objectives
with the possible exception of objective (g). In the latter case, the
project is designed to minimize the negative impacts on the quality of
life of persons in the site area, although there will be some negative
impact. Another qualification Is th«t then are now no current plans
by Metro to market wet or liquid sludge, although this could still be
done. He will also attempt to respond to your specific questions
directly below.
Although' the water quality and groundwater were not actively con-
dered in the decisions about site location by Metro, It does happen
that the choice of sites for other reasons turn out to be generally
compatible from a water quality standpoint. For instance, locating
in die dryland areas away from perennial streams minimizes the Impact
on surface waters. The fact that Metro selected their site based on
the ability to control runoff from the site (in an upstream area of
a watershed) makes control of water quality simpler. Finally, the
choice of a site at a considerable distance away from shallow ground-
waters in an area of generally clayey soils makes it more feasible to
control leachate to the groundwater. Distance from households was a
factor in this selection, and this minimizes the potential for con-
tamination of domestic and other supply wells. EPA is also requiting
additional controls to protect groundwater quality.
7J Because of the favorable economics of hauling sludge over fairly
rang distances, the distance from markets is not a critical factor.
There will probably be relatively little use of the dried sludge in
the site or pipeline vicinity. Metropolitan area and irrigated areas
to the north will probably use the sludge in greater quantities. The
selection of the pipeline route and site were made to minimize con-
flict with existing land uses, and not because of potential markets.
-------
Letter #24,
continued
Charle* Joedon
10 Scpccaber 1976
Page 3
EPA Response
©
-F*
no
(e)-(ii) Mined Land reclamation through wet sludge application. Denver
is located on the western edge of a vast coal basin, containing large
Mounts of lignite. A lignite gasification plant is scheduled to be
built near tfatkins in the early 1980's. Presumably much of the lig-
nite for this plant will be strip-mined. Have the lands lost likely
to be mined been identified? Again, were the drying sites and pipe-
line corridors chosen with these lands in mind?
In addition, will the drying sites take valuable agricultural land
out of production? Are other less productive lands available for
drying sites and pipeline corridors?
(f) Production of ete thane gas for commercial use. Due consideration should
given to the research sponsored by the Four Corners Regional Coaaission
regarding the conversion of biodegradable materials to aethane gas.
Has the production of aethane gas been considered as a possible com-
ponent of the sludge management plan? Bow many cubic feet of aethane
par day couli be generated? In view of decreasing availability of
natural gas, che production of aethane gas for coanercial use ought
to be carefully considered.
(g) qnalltv of life and property values in the area surrounding the drying
site. Hill this project result in odor, seepage, blowing, or other
unpleasant effects such as heavy traffic,burden on roads, or other
facilities, which will diminish the quality of life in the surrounding
area? Hill these effects force surrounding farmers to flee the area?
What will the effect be upon property values? Have other drying sites
been considered which would ainlaize the loss of the valuable rural
setting or agricultural economy of the area?
8J The site waa not chosen with lignite mining in mind. However, the
tklns strip nine/gasification proposal does appear to be an ideal
location to be serviced by Metro sludge both for land reclamation sad
perhaps even in the gasification process itself.
©
See dicusslons under Issues 1-2 and H-8.
'The digesters recently constructed at the Metro District plant do
e gas burners to utilize a portion of aethane generated in the di-
gesters for heating the digester contents. Optlan performance of
digesters can be achieved by maintaining fairly close temperature
limits on digester operation. Metro considered the use of the excess
aethane gas for electrical generation, but found that the costs of the
conversion equlpaent were prohibitive. Therefore, seme of the excess
gas is wasted, although during the winter, aost will probably be uaed
to aalntaln the digester tsmperature.
@ There will be some negative iapacts on residents and properties
the vicinity of the proposed drying site. These are discussed ss
separate topics under the following issues: odor (Issues II-3), seepage
(II-2), blowing (Issue II-5), effects on property values (issue II-9),
and other potential sites (Issue IV-1).
The Colorado Department of Agriculture strongly supports the responsible aanage-
aant of sewage sludge for a wide range of beneficial uses. Although several
significant problems must be contended with, we encourage continued efforts
In research and aanageaent to utilize the nutrient content of sewage wastes
resourcefully. However, we urge that a wide range of current and potential
uses be coaside--ed in the design and operation of a specific aanageaent plan
such as the plan submitted by the Denver Metro Sewage District. Specifically,
we request that the location of the drying sites and pipelines be reviewed from
a food production, water quality and quality of life perspective to obtain maxi-
mum beaefit from this forward-looking project.
DU/pjc
-------
Letter #25
RICHARD O. LAMM
Govcmno*
STAT"' ^ -%
SsXllo.
EPA Response
JOHN «. HOLD
COLORADO GEOLOGICAL SURVEY
DEPARTMENT OF NATURAL RESOURCES
715 STATE CENTWNIAL BUILDING - 1313 SHERMAN STREET
DENV€H COLORAOO 80203 PHONE 13031 892-261!
September 3, 1976
Mr. Philip Schmuck, Director
State Clearinghouse
Colorado Division of Planning
520, 1313 Shewn Street
Denver, CO 80203
Dear He. Schmuck:
RE:
DRAFT EIS, DENVER METRO SLUDGE MANAGEMENT
PLAK
¦Ch
u
©
®[
This office has reviewed the above draft EIS report, especially those sections
pertaining to possible pollution or contamination of ground-water supplies.
As pointed oat in dm report, Oils proposed action could have, serious adverse
ispact on the ground-water supplies In the vicinity of the site If adequate
surveillance Is not maintained.
This office Is In complete agreement with the rcquirevnts set forth by the
EnvlnxcDaitcl Protection Agency, that an experimental operation be first
established to determine what, if any, adverse ground-water quality problem
night develop sad for the Monitoring of the ground-water under the drying
ad storage sites. The final design of the drying and storage sites should
be based on results obtained free the experimental site. Ue would also add that
before the drying and storage site is designed, a thorough and complete
evaluation of the ground—water conditions In the area be made. This evaluation
should include,among other things, the depth to mater, direction and rate of
ground-water flow, and chemical make-up of the waters. Provisions for monitoring
wells aust be a part of the final design of the storage sites. These wells
should be located completely around the site, and especially in a down-gradient
direction. In order that escaping effluent might be detected at the earliest,
the wells should be located in very close proximity to the drying beds or any
other source of pollution. Provisions should be made fog-the-should- be made
fo* the sampling of these observation wells on a long-term basis. The results
of this sampling should be reported to the Colorado Department of Health on
a regular, predetermined basis.
One other area that should be addressed in the final report is a contingency
plan for any break that might develop in the pipeline. He do not feel that
this problem was adequately discussed la the draft EIS.
Sincerely,/
Cj The discussions under Issues II-l and 11-2 define the groundwater
situation in and around site B-2. A discussion of the results from the
greeley test plots Is also contained here. Based on these studies,
EPA has developed recfii n iler ions for lining of the basins to protect
the groundwater (Issue II-2). The DSGS will be performing monitoring
with the ongoing project; a description of this task is set out in
Appendix B. EPA will recnTnd that these tests be submitted to the State
Department of Health.
121 The contingency plan for a pipeline rupture is discussed under
tissue 1-5.
RHP/jp
/ ¦ /¦
Richard H. Pearl,Chief
Ground-water Investigations Section
GEOLOGY
Story of the past ... ke> to the future
-------
RICHARD O. LMN
Governor
Letter #26
DIVISION OF WATER RESOURCES
Department of Natural Resources
1313 Sherman Street - Room £02
Denver, Colorado 80203
Administration (303) 892-3581
Ground Water (303) 892-3587
September8, 1976
MEMORANDUM
TO:
FROM:
PHILIP H. SCHMUCK, DIRECTOR, STATE CLEARINGHOUSE
DR. JERIS A. DANIELSON, DEPUTY STATE ENGINEER
SUBJECT: DENVER METRO SLUDGE MANAGEMENT PLAN
DRAFT ENVIRONMENTAL IMPACT STATEMENT
-C*
J*
-------
Letter #27
EPA Response
THE STATE HISTORICAL SOCIETY OF COLORADO
State Archaeologist (Interim address) Pioneer Hall,
University of Denver, Denser 80210
¦t*
Ul
September 7, 1976
Mr. Philip H. Schmuck
Colorado Division of Planning
520 State Centennial Building
1313 Sherman Street
Denver, Colorado 80203
RE: Denver Metro Sludge Management Plan (f76-132)
Dear Nr. Schmuck:
The Office of the State Archaeologist of Colorado has
received and reviewed the archaeoloqical/cultural resources
management statements of the Draft Environmental Impact
Statement by the U.S. Environmental Protection Agency for the
Metro Denver Sludge Management Plan. (The Office of Historic
Preservation of the State Historical society will comment
separately for the State Historic Preservation Officer re-
garding historical resources.)
Archaeological resources have been, in general, adequately
considered. In spite of the negative surfa® evidence, there
remains a possibility of encountering sub-surface resources.
Therefore, excavations should be monitored by someone with
archaeological training.
With this proviso, the project may proceed according to
our review.
For the State Historic
Preservation Officer
SrU\
peteau, Ph.D.
logist Colorado
44-1713
Phone:
TMs recommendation will be included in the grant conditions for
this project. Based on discussions with Dr. Rippeteau, Metro nay be
given the option to train workers and/or supervisors on the construc-
tion project to recognize archaeological artifacts.
Additionally, EPA has worked with the State Archaeologist in re-
solving the questions raised by the US Department of Interior letter
(Letter #31) on pipeline routing and potential archaeological dis-
coveries .
BER:ng
cc: Office of Historic
Preservation
-------
Letter #28
Mnw vm
DEPARTMENT OF HOUSING ANO URBAN OEVW-OPUENT
REGIONAL OFFICE
EXECUTIVE TO*l« . 14*5 CURTIS STRtET
OENVEH, COLORAOO MM!
September 14, 1976
80E
Mr. John A. Green
Regional Administrator
Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado 80203
Dear Nr. Green:
This Is in response to the Draft Environmental lapact Statement
(EIS) on the Denver Metropolitan Sewage District's Sludge Management
Plan. You probably know that the Department of Housing and Urban
Development (HUO) has two principal environmental concerns. These
are (1) the effect of a proposed action on the urban environment
p, and 12) the consistency of such action with the comprehensive
cr\
planning for the area, which involves use of the A-95 process.
It appears that the A-95 process is being utilized, and that the
proposed project will have no significant adverse Impact relating
to HDD's concern with the urban environment.
Sincerely,
Robert
Assist;
uschek
llonal Administrator
Community Planning and Development
EPA Response
-------
John A. Green
Regional Administrator
Environmental Protection Agency
1860 Lincoln. Suite 900
Denver. Colorado 80203
Sear Nr. Green:
thank you for the opportunity to review the Draft Environmental
Statement far the Denver Metropolitan Sewage Disposal District's
-j
Sludge Management Plan. Me have no comments.
Sincwely,
AS. H. HANKS
" Deputy Regional Forester, Resources
EPA Response
-------
Letter #30
Dasel E. Hallmark, PE &
3480 South Ivy Way
Denver, Colorado 80222
September 17, 1976
Regional Administrator
U.S. Environmental Protection Agency
Rocky Mountain - Prairie Region vm
1860 Lincoln Street, Suite 900
Denver, Colorado 80203
Re: Metro Denver Sludge Management Plan
Draft EE May 1976
oo
Gentlemen:
0
I have not made a complete review of this document which
has brought together valuable technical information but would like
to make one brief comment,
to looking at Table 14, page 79, I was surprised to find that
abait 8 lis of sludge is projected as generated per capita per day.
Isn't this rate very high? In line with this I would assume industry is
loading die plants at a high rate but not necessarily paying their share
at costs. As stated on page 10, the 2556 share would be bora pro-
portionately by individuals, industry, ami busitesses.
Somewhere in the EPA Federal Registers I remember reading
that industry must pay their total costs. If this is still true then why
Infer differently in this report. At 8 lbs sludge per capita per day
projected, it is no wonder Metro is in die "sludge mess".
Sincerely yours,
Dasel E. Hallmark, PB & LS
EPA Response
nj The amount of sludge generated per parson per day according to
Table 14 is not 8 lbs per capita/day. In 1985, for example, the
figure would lie between .13 and .15 lb/capita/day, depending on
whether the DR00G or Metro population forecast is used {97 at/day * 2204
Ib/nt -f population). This would be considered a normal sludge generation
figure. Note that this is the quantity of dry solids remaining after
anaerobic digestion.
K) Public Law 92-500 and tbe older vater pollution control laws re-
quire that industries discharging to a municipal facility pay their
fair share of capital and operating costs. In general, they would
pay an wwat proportional to their waste strength. EPA1 s recent
policy in accordance with the Act has been to stress industrial pre-
treatment, where there is any chance of creating problem; ia tbe
wastewater plant. In the long ten, EPA expects to have industries
provide sore pretreatment in order to reduce tbe heavy netal content
in sludge. Metro District is initiating an Industrial survey to
identify heavy netal sour—es (see Issue 1-1)* Hie preponderance of
sludge generated at tbe plant, however, Is still from domestic sources.
-------
Letter #31
m uhy ttrs* to-.
EK-76/746
United States Department of the Interior
OFFICE OF THE SECRETARY
MISSOURI BASIN MCWM
auiLOWe «T. OINVIR FKOERAL CCHTU
DCMVCM. COLORADO SOUS
SEP I»W6
Mr. John A. Green
Regional Muiutrttor
Environ—ntal Protection Agency
Region VIII
I860 Lincoln Street
Denver, Colorado 80203
Dear Mr. Green:
-P»
t£>
©
This is in response to your request for the Department of the Interior
to review end cairnt on the draft environmental statement and draft
hi—iji for the Denver Metropolitan Sewage Disposal District's Sludge
Manage—nt Plan, Adams County, Colorado. He have the following comments
to include in your final environmental statement.
General fa—iiti
1. The Metro Denver Sludge Management Plan appears to be an excellent
solution to the sewage disposal problem. However, inasmuch as the success
of the proposal will be dependent on the ability to develop a market for
the sludge, it would seen that further investigation and study of this
phase of the proposal ia a prerequisite to initiation of the proposed
construction.
»
Because the Bureau of Mines' concern in any project is possible Mineral
involvement, it haa no objection to the proposal as outlined in the draft
environmental statement.
2. Under provisions of the proposed action as presented in the draft
environmental impact statement, impacts on wildlife and related habitats
are adequately discussed.
»
3. The final environmental statement should demonstrate implementation
of actions that are necessary so the proposed project will not have any
adverse effect on historic sites or structures. These actions include:
a. The most current listing of the National Register of Historic
Places and all monthly supplements should be consulted.
b. The State Historic Preservation Officer for the State of Colorado
should be consulted to determine whether the proposal will affect any
cultural site he is nominating to the national Register.
Continued next page
EPA Response
The systtm proposed does not depend on a ready market for sludge
» he at least minimally successful. Even if the sludge were dried
then landfilled, the coat of the syston would be less than the
present operation. Considerable energy savings would still occur.
Metro will also not need an Immediate market, since the aite can hold
the dried sludge for a number of years. In the lone run. however.
EPA does think that the potential benefit of this system will not
be achieved (I.e., recycling of nutrients and soil amendment), until
agricultural or other markets are developed for the sludge. See
discussions on marketability (Issue V-4) and emergency disposal
(Issue 11-15).
L2J EPA has consulted the national Register of Historic Places and
has determined that no structures will be affected by this project.
The State Historic Preservation Officer for Colorado has also been
consulted on this project (see Letter # 27).
-------
Mr. John A. Green, EPA, Denver, Colorado
e. Pursuant to Executive Order 11593, Sections 1(3), 2(a), and 2(b),
there is a need for a surface survey of the entire pipeline route by a
professional archeologist and a professional architectural historian.
We note that a records search was made and that much if not all of the
pipeline follows a roadway right-of-way; however, in the absence of a
documented statement by the State Archeologist or other competent
authority confirming that in his judgment the likelihood of any cultural
resources being present is minimal, it is agency responsibility to survey
all terrain that will be disturbed by construction activity.
d. The results of the surveys should be fully detailed in the final
environmental statement along with the specific comments and recommendations
of the principal investigators.
e. He need to know whether the pipeline right-of-way will penetrate
undisturbed terrain or whether it largely follows the roadway right-of-way.
f. Specific guidelines for i imr diate work stoppage, notification of
the State Historic Preservation Officer, evaluation by a professional
archeologist, and excavation, if warranted, should be stated in the final
environmental statement to be agency policy if unknown cultural resource
sites are located during construction.
Use actions suggested are consistent with Section 106 of the National
Historic Preservation Act of 1966 end the Advisory Council on Historic
Preservation "Procedures for the Protection of Historic and Cultural
Properties" (36 CFR, Part 800). If it is determined that any of the
proposed developments will adversely affect cultural resource sites that
meet Rational Register criteria, then the undertaking agency has the
responsibility to provide to the maximw extent possible for mitigation
of all such adverse effects noted. The undertaking for mitigation should
be in consultation with the State Historic Preservation Officer and the
Advisory Council.
Specific Ca—ents
1. On Table B, page 16 of the "Summary," water quantity is stated as
an environmental parameter at the proposed sludge drying, storage, and
distribution site, the stated impact is its removal from the South
Platte liver. The importance is said to be minor, and the severity of
impact is said to be moderate. Mitigation is said to be feasible in
part. The stated mitigetion methods are said to be: (1) to avoid
irrigation and (2) to return the water. Perhaps the information as
provided in this table should be expanded and clarified in the text of
Continued next page
EPA Response
EPA has consulted with the State Archaeologist on this point,
sent the Archaeologist detailed «aps of the pipeline right-of-way.
It was agreed that because the pipeline exclusively follows public
rights-of-way that have been considerably disturbed (Burlington Ditch
eabaninent, roadways, Sand Creek sever line), a surface archaeological
investigation would probably prove inconsequential* EPA will require
the Metro District in a grant condition to either hire an archaeologist
to monitor construction of the pipeline, or else provide training to
supervisors and/or workers on the construction project to recognize
archaeological artifacts and situations. Metro District would still
be responsible for notifying the State and EPA in the event of a find.
A proposed statement of this grant condition is found in Appendix A
of this voluae. Also a better description of the pipeline routing is
found in Issues 1-2 and 1-4, along with potential i^acts*
This wording will be incorporated into the grant conditions in
Appendix A.
-------
Mr. John A. Green, EPA, Denver, Colorado
the final environmental statement. Ho Mention could be found in the
text of the EIS of the actual quantity of water needed, nor of the
expected return flows to the South Platte River. It is suggested the
mitigation methods of avoiding irrigation and/or returning the water
I be fully diacuaaed in ten* of their possible implementation. What are
' the impacts of avoiding irrigation or returning the water? Hhat are
the implications of either mitigation method on the water quality of
th* South Platte River and the future Harrows Reservoir to be located
7 milea meat of Fort Morgan, Colorado. On Narrows Dam will start
, intercepting South Platte water for storage in 1983.
2. Page 13 shows a liat of alternatives which includea "no action."
Ihe final environmental statement should elaborate on the ramifications
of the "no action" alternative. Hhat are the implications of this
alternative regarding the population growth, refusing more sewer hookups,
controlling population growth (constitutional implications), energy
generation and conveyance requirements and water development and
conveyance requirements?
3. OB pages 46-55, the general configuration of the Denver basin should
ba described in the si—17 of geology and geohydrology, because it is
directly significant in controlling the ultimate direction of movement
of ground water in the confined and seai-confined aquifers below the
unconsolidated surficial materials.
4. figure 6 on page 47 suggests that the distribution center may be
east of section 22 and possibly in section. 23 of Township 2 South,
tl—|ii €3 Vest; figure 12, on the other hand indicates a location in
sections 12, 21 and in the western halves of sections 15 and 22.
localise the hydro logic properties of the materials underlying these
respective locations may differ considerably, the location should be
consistently and correctly shown,
5. On pages 54 and E-31 the environmental statement declare* that between
the valley fill aquifers and the Laraaie-Fox Hills aquifers lies a thick
aeries of rocks of low permeability, this appear* to ignore the sand,
sandstone, and conglomerate aquifers of the Denver, Arapahoe and Dawson
Formations; in the iaadiate vicinity of the project these aquifers have
been tapped principally for domestic supplies, but only a short distance
downgradieut to the west and southwest they have afforded supplementary
public supplies.
6. The potential for overflow of the drainage impoundments at the proposed
center (p. 96, par. 3; p. 94, fig. 12; and p. Ill, par. 4) should be
mentioned, even though it does not appear that it would result in
Continued next page
Qjrr
Response
better description of the amounts and lapacts of the additional
star use thru this system is found in the discussion under Issue 1-3.
The mitigation measures suggested in the draft EIS were in part devel-
oped because the resolution of the issue at that time was an open
question. EPA felt that the likely Impact on existing water rights
would be considered "minor". However, it did not know the extent of
the concern about this issue, and had to be prepared to discuss al-
ternatives to increased consumption if necessary. Our reading of the
situation at present is that the key actor In this issue, the Denver
Water Board, is not overly concerned about the Impact. Until EPA is
Informed otherwise, that the amounts of water to be used in this pro-
posed project are not acceptable, we do accept the Metro proposal as
originally envisioned. This would include the uae of purge water on
the site a* irrigation water.
0 Since the amount of water involved in the proposed project would
be about 4160 a3/day [1.1 mgd] versus about 490 n^/day [.13 agd] now
consiaed in the Lowry Bombing Range operation, EPA still maintains
that the overall effect on Platte River quantity is small. By con-
trast, the Burlington Ditch, which runs by the Metro plant, can with-
draw up to 1.47x106 s^/day [388 agd] from the River. Therefore
changes to water quality by depletion are insignificant whether the
present system, the proposed system, or a modified proposed systea
without irrigation Is used. In tens of the return flm aad its
effect on water quality, EPA would expect that all necessary permit
limitations would still be aet; «ae additional treatment costs would
be experienced at the Metro plant. There should be a negligible
affect on the waters that eventually reach the area where the Narrows
Ereject is proposed.
171 Ihe "no action*1 alternative in this case has a realistic meaning,
¦etro District already has an existing sludge operation, although
it is close to capacity in some unit process areas. Were EPA to
choose the "no action" alternative, this would first of all wean a
continuation of the operations at the Lowry Bombing Range. This al-
ternative is thoroughly discussed in the EIS and further in Issue
III-l. Choice of this alternative still allows a further choice of
fading additional units to the existing systea or no federal funding.
EPA could well fund additional capacity to the existing systea;
environmental Impacts directly attributable to the systea would be
identical to those described under continued Lowry operation. EPA
could also choose to not fund this project at all, given other prior-
ities. This need not be assuaed to be an antlgrowth effect. Metro
District members could raise funds for construction of the project aa
well. Since the choice here Is not a systea versus no systea, but
rather a "better" systea sgainat an existing systea, EPA thinks that
the approach taken in the EIS In developing and evaluating alternatives
is a reasonable one. A discussion of project alternatives is found
Cr Issue IV-3.
The configuration of the Denver basin is presented in the improved
rlption of the B-2 site. The Lost Creek Groundwater District
(see Letter #44) has raised issues dealing with possible contaaina-
tioa of various aquifers beneath the site.
Figure 6 on page 47 of Volume I shows an arrow pointing toward
Distribution Center. The site is off the map to the east. Figure
12 shows the correct location of the alte. Incidentally, the site is
located in Range 640, Township 2S, and includes all of sections 16
and 21, and the western halves of sections 15 and 22.
@The groundwater formations under site B-2 are discussed in Issues
1 and H-2. The discussions there recognise that doaeatlc wells do
draw water froa the Deuvei-Bawaon-Arkoae formations, although in aaall
quantities. EPA is concerned that this formation be protected froa
leaehate froa the sludge drying operation.
-------
4
Letter #31,
continued
LT
ro
©
Mr. John A. Green, EPA, Denver, Colorado
significant problems. Presumably an extreme storm event causing overflow
would provide ample dilution, and the long reaches of ephemeral channels
would provide ample dispersion prior to entry into biologically active
waters.
7. On the first page of the EIS, in Section 3, "Environmental Impacts,"
it states that "an increased amount of water over that now consumed in
the existing sludge disposal practices of metro will be carried in sludge,
purge water and additional irrigation water to the Adams County sice,
reducing flows in the South Platte River downstream of the central plant."
It is suggested that estimated figures of the amount of water needed for
the sludge, the purge water, and the subsequent irrigation be giver..
8. On pages 111-112, the first sentence under the hearing "Water Rights"
needs clarification. It says, "In the process of transporting liquid
sludge to the drying and distribution center, and during the periods of
purging the pipelines with secondary effluent and any additional
irrigation water beyond what is now consumed in the sludge disposal
process will be carried from the central plant to the Adams County site."
What will be carried from the central plant to the Adaos County site?
How much? When? What are the environmental implications?
9. Page 213, it is not clear what the environmental team is, nor what
the members of the team did with regard to this report. Perhaps the
environmental team could be listed as Section X of the EIS aod a
statement made whether these persons are CH2M-Hill employees,
Engineering-Science employees, EPA personnel, etc.
10. On page £-14 impacts on ground water from the use of mine spoil sites
in sludge disposal are reportedly considered to be insignificant, because
ground water is not plentiful in the consolidated rocks involved. However,
the statement should also address the ground water/surface water relation-
ships involved and the related fate of leachates» Movement of leachates
through the fractures in consolidated rocks of the types mentioned should
be relatively rapid, and there should be very little opportunity for
melioration of quality from chemical changes, ion exchange, adsorption,
or absorption. Impacts of the resultant rapid transmittal of pollutants
through fractured aquifers to streams should be evaluated.
We appreciate the opportunity to consent on your environmental statement.
Sincerely,
pecial Assistan
to the Secretary
EPA Response
©
This issue Is discussed under Issue 11-6.
0 See Issue 1-3.
V-3J The typographical error in this sentence has been corrected,
see discussion under Issue 1-3.
U4I The persons listed on the "Environmental Team" prepared portions
or this EIS. The list has been updated and clarified.
U5J These statements are all true. However the runoff from these
Sine spoil sites is quite degraded before sludge application, being
highly acidic. The use of sludge on sites such as these will in-
itially raise the pH of the runoff, while adding other pollutants
frcv the sludge. The net effect on runcff quality may in some cases
actually be positive, and in most cases will not significantly de-
grade further the runoff quality. In the long-term, the application
of sludge will reduce the quantity and improve the quality of runoff
by improving the moisture-holding capacity of the soil and enhancing
revegetatlon of the site. Each mine spoil site should be evaluated
before sludge application for potential effects based on site-specific
conditions.
-------
Letter #32 dr. f. robert mcgregor
2078 SOUTH WINONA COURT
DENVER, COLORADO 80219
17931
22 September 1976
Mr. John A. Green
Environmental Protection Agency
1860 Lincoln Street - Suite 900
Denver, Colorado 3020 3
Re: Denver Metro Sludge
Environmental Impact Statement
Dear Sir:
The sludge recycling effort of the Metropolitan Denver Sewage
Disposal District is an encouraging forward step. This step, however,
is too small for this age of energy shortage and conservation momentum.
A great deal of study has been completed on the international
level concerning the recycling of resources including municipal waste-
water sludge. As a result of these efforts, a greal deal of interest
has been focused on sludge recycling. Major capital expenditures are
about to be made on sewage treatment systems in this area and we cannot
afford to make mistakes. We need to take full advantage of the expe-
rience of others in this regard. The proposed plan does not take full
advantage of the knowledge previously developed in this field.
Economic considerations should he a foremost long-term objec-
tive in recycling. A sludge recycling system must be optimized to be
of economic value. The values take on many forms including fertilizer,
saved treatment costs, increased agricultural production, clean water
and clean air.
The approach taken by Denver Metro should be more optimized.
The wet sludge should be injected directly into the agricultural
fields rather than being first dried in large sludge drying beds which
may cover as much as a square mile. Further, the sludge should be
utilized on agricultural fields in the South Platte Valley where the
benefits per ton can be maximized. The sludge is a marketable material
and it is not necessary to own the lands___that^it is used upon if this
approach is taken.
Continued next page
EPA Response
Although EPA agrees in concept with your statement that such a
system should be optimized, we think that we are a long way from know-
ing how to accomplish this. There is a lack of information about exis-
ting sludge recycle systems in this semi-arid area, simply because they
are so few in number.
For example, you suggest that wet sludge should be applied in-
stead of dried sludge. We agree that this would recycle greater
amounts of nitrogen to agriculture. However, some forte of storage
would be needed during winter months. A different selection of crops
(more restrictive) would be required for the wet sludge, because of
the greater potential for pathogen transmission. Metro has chosen the
dried sludge approach because it offers the potential for greater
flexibility of use. We also ausc point out that optimizing for poten-
tial uses assumes that there are willing users. This is not completely
the case at present; Metre's system must go through a trial-and-error
process to discover what the best potential use(s) are.
-------
Mr. John A. Green
-2-
22 September 1976
Further public education is needed relative to recycling
of wastes. Sometimes local political problems are difficult to over-
come. Nevertheless, the American people are about ready to accept the
waste recycling concept. Not nearly enough has been done by Denver
Metro on public information dissemination. Often times the data that
has been distributed has been in a defensive posture. An aggressive
and forward looking farmer or rancher truely interested in agriculture
would quickly recognize the added value of having sludge applied to
his land. The approach of buying the farm lands is too expensive and
not necessary. The sludge is a marketable material of significant
value. We don't believe that these individuals have been identified.
It is time that some of the money spent on studies is spent on
positive data dissemination and planning which would lead to a strong
and viable sludge recycling program which would aid the environment,
add to our food and fiber production capability, improve the economy
of the Denver metro area, and more fully utilize these valuable
fertilizers which are normally thrown away.
Very truly yours,
Dr. F. Robert McGregor
EPA Response
You are absolutely correct that further public education concern-
ing the recycling of waste is needed. EPA has begun to strongly en-
courage the recycling of wastewater, solid aaterials such as aluminum
cans, bottles, combustible materials, and of course, sludge. There is
a formidable problem of public acceptance, however, that must not be
overlooked. This EIS indicates a segment of the public that is looking
to this system for eventual use of sludge on home gardens (see Volume
I, Appendix F) . However, there is an equally vocal portion of the pop-
ulation who do not consider the use of sludge as a benefit. In partic-
ular, the numerous fanners in the vicinity of the proposed site E-2
who objected to the project feel that the dried sludge will have little
or no benefit to them. EPA does agree that sludge will have only
liaited value to dryland farming operations, especially because of
costs. On the other hand, Metro has indicated that a number of farmers
are interested in trying the sludge (e.g. see letter #4). EPA thinks
that while nutrient-bearing sludge may eventually be marketable, for
the near-term Metro may have to develop the market thru an aggressive
promotion and perhaps free distribution of the material. EPA will also
continue to promote the beneficial use of sludge, while trying to elimi-
nate some of the constraints to its use.
-------
Letter #33
CITY AND COUNTY OF DENVER
W. H UcNICHOLS. Jfl.
tMyor
DEPARTMENT OF PUBLIC WORKS
September 23, 1976
OFFICE OF THE MANAGER
CITY AND COUNTY
BUILDING
DENVER. COLORADO 80202
Mr. James Sanderson
Regional Counsel
U. S. Environmental Protection Agency
Region VIII
1860 Lincoln Street
Denver, Colorado 80203
Dear Mr. Sanderson:
Re: Draft Environmental Impact Statement for Metropolitan Denver Sewage
Disposal District No. 1, "Sludge Management Plan"
tn
en
The above statement was presented orally at the Public Hearing held on September 8,
1976 in Room 269 of the U. S. Post Office at Denver, Colorado, and the following
comprises our written comnents on the proposal.
m
The City and County of Denver has, for several decades, been involved in the land
disposal of sludge, and it had only been during the "Sludge Incineration Process
Years" of operation at the Metro District facility that Denver sludge was unavail-
able for use by the Denver Parks Department. Historically, the Denver Parks De-
partment has been the major recipient of "air dried" digested sludge resulting
from the anaerobic digestion process within the operation of the City's primary
sewage treatment plant, normally referred to as the Denver Northside Plant. Since
the Metro sludge incineration process was abandoned several years ago in favor of
land disposal of sludge at the Lowry Bombing Range, the Denver Parks Department
has again been utilizing Denver digested sludge in limited amounts. There is, has,
and will continue to be a market within the City and County of Denver Parks Depart-
ment for this anaerobically digested sludge.
The Denver Northside Treatment Plant was originally constructed to provide the
capability of air drying digested sludge resulting from its anaerobic sludge di-
gesters. The use of these sludge drying beds was minimized at the request of the
State of Colorado Department of Health during the formative years of the Metro
Denver Sewage Disposal District (of which Denver is the principal financial con-
tributor) in order to protect the local groundwater from probable contamination
"The draft Environmental Impact Statement as prepared by the U. S. Environmental
Protection Agency relating to the Sludge Management Plan of the Metropolitan
Denver Sewage Disposal District No. 1 has been reviewed and evaluated. The
City and County of Denver supports the concept of land disposal of sludge gen-
erated by the Metro and Denver Northside Treatment Plants. Specific comments
relative to the draft Impact Study will be forwarded at a later date."
O
<2>
Continued next page
EPA Response
EPA recognizes that the City and County of Denver's Parks Depart-
ment has been an old and substantial user of Metro District sludge in
a beneficial way. EPA can only deplore the chain of events that has
made it difficult for the City to be a continual user of this sludge.
EPA will continue to press the Metro District to minimize the financial
burden that would accrue if the District were to charge the City for
use of this sludge. Other municipalities inside and outside of the
District are interested in using this sludge material for parks im-
provement (see Volume I, Appendix F).
-------
Mr. James Sanderson
Page 2
September 23, 1976
from percolation of decant water through the unlined drying beds. With the con-
sideration of abandonment of the drying beds in mind, appropriate contract nego-
tiations proceeded, once the District was formed, and the requirements of the
current "Service Agreement" were finalized. Under terms of that agreement, Denver
enjoys the option to transfer its sludge to the District facility for disposal or
not.
Therefore, the City, through its Wastewater Management Division, has been inves-
tigating the possibility of reactivating its sludge drying beds for independent
control of its sludge resource. (There is no apparent logic in Denver discharging
its sludge to the Metro District, paying the District for its disposal and then
buying it back for use as a compost or limited fertilizer by the Denver Parks
Department.) This particular cost aspect of the Metro proposal is currently under
detailed analysis by Wastewater Management personnel.
The City has approached the State Water Quality Control Division and Environmental
Protection Agency in order to consider a viable alternative to the current Metro
plan. As a result, the City anticipates presenting its proposal to the State
Water Quality Control Commission at the October Commission meeting. Briefly, the
proposal consists of reactivating the existing Denver Northside sludge drying beds
as follows:
1. Waterproofing all beds with an impervious material so
that subsurface filtration will be precluded;
2. Installing a sand or filter bed on top of the impervious
material and an underdrain which will assure flow by
gravity;
3. Construction of recovery tanks for the underdrains to
collect the runoff and return it to the plant headworks;
4. Construction of the beds in order to take full advantage
of evaporation.
So«ie of the benefits to be derived from this method of handling Denver's digested
sludge would be as follows:
1. The Denver cost of pumping digested sludge to Metro at a
5 per cent solids concentration will be precluded;
2. The cost and use of chemicals (polymers) added to assist
in Denver sludge de-watering by Metro will be eliminated;
3. The total cost of de-watering the Denver sludge at Metro
(vacuun filtration) will be eliminated;
Continued next page
EPA Response
2J Issue IV-4 discusses the Denver Northside proposal for separate
Sludge treataent and disposal of Northside digested sludge. It is
EPA's position that Northside sludges are already factored into the
design of the Metro District's offsite solids program proposed in this
E1S. EPA therefore will not fund facility planning* design or con-
struction of separate sludge drying/disposal facilities at the Denver
Northside Plant.
Ttour discussion also did not recognize the potential benefits that
could accrue to the Denver Northside and Metro liquid phase operations
if the Northside decant were to be included in the pipeline flows to
the drying site. A substantial decrease in BOD, suspended solids and
nitrogen loading to the Metro waste activated secondary system could
occur that would have financial benefits to Northside as well.
-------
Letter #33,
continued
Nr. Janes Sanderson
Page 3
Septaiter 23, 1976
©
<3>
4. The cost of transporting the Denver sludge, plus residual
chemicals, to a disposal site will be eliminated;
5. The life of the disposal site, insofar as sludge disposal
is concerned, will be increased by t 15 per cent;
6. Sludge recycling can be accomplished much sooner by util-
ization of the Denver drying- beds;
7. There is an inmediate market for the dried sludge within
the Denver Parks Department;
8. There is a strong possibility of handling additional digested
sludge from the Metro District at some time in the near future;
9. Possible advantages accruing to the Metro District in view of
this proposal and the fact that Metro will, in the near future,
have its own anaerobic digester capability are:
a. A viable alternative by reducing the land requirements
for the Metro sludge farm;
b. Cost savings of a potentially considerable magnitude
concerning pipelines, pump stations, land acquisition,
land development, litigation costs, replacement water
costs;
Preliminary savings 1n excess of $300,000 can be realized by the City and County
of Denver in handling its own sludge disposal. Overall savings to the agencies
^Involved 1n the Metro District could be considerably more.
Other concerns which the City wishes to identify with regard to the draft Environ-
mental Impact Statement are as follows:
1. The apparent continuing misconception relating to what the Metro
District is and who they serve. On page 3 of the summary report,
the District should be identified as a special service district
with 21 current members operating a single treatment plant located
1n Commerce City. Several members of the District operate their
own facilities and contract to provide services to still other
smaller local government entities. (The City, as but a single
member of the District, provides service to 45 other local govern-
ments, as well as its own population tributary to Denver Northside)
The perpetuation of a concept that the District represents the City
and County of Denver or any other district member must be clarified
and the subliminal theme of the draft report which dramatizes this
misleading concept must be corrected;
Continued next page
EPA Response
EPA does recognize this arrangement of municipalities and districts
within the MDSDD #1. It is a fact, however, ¦that approximately one-
half of the Metro District Board is comprised of City and County of
Denver member^. It is also the case that the Metro District Central
Plant provide* secondary vastewater treatment to most of the metro-
politan area,j including the City and County of Denver.
-------
Letter #33,
continued
Nr. Jones Sanderson
Page 4
September 23, 1976
2. In describing Metro's current sludge operation on page 6 of the
sunmary report, it 1s Implied that Denver sludge as well as the
Metro sludge is responsible for a number of outstanding prob-
lems with regard to disposal at the Lowry Bombing Range. It
must be noted that disposal of Denver's sludge as a discreet
material Is not subjected to the same requirements as the Metro
product. The Metro District staff has chosen to utilize Denver
sludge as a conditioning agent for their sludge disposal process,
thereby reducing the overall cost requirements for de-watering
and polymer addition in their normal operating procedures. Further,
utilization of the Lowry Bombing Range area for disposal 1s provided
by the City and County of Denver to the Metro District on a no-fee
basis;
3. The complex water rights issue appears to require immediate atten-
tion. On page 112 of the complete report, the validity of the
assumption by the Environmental Protection Agency that the Denver
Water Board will allow Metro to continue to use its water for the
sludge transportation system needs verification before that trans-
portation plan can be accepted. That assumption alone could heavily
impact the choice of final sites for the "sludge farm," and therefore,
the feasibility of continued use of lowry Bombing Range land should
be reenphasized.
The City considers the reactivation of the Denver sludge drying beds to be a most
important alternative in the final design of the Metro proposed "sludge farm"
disposal plan, as well as the feasibility of continued use of Lowry Bombing
Range land. The staff of the Wastewater Management Division is available to
meet and discuss these proposals at your convenience.
Very truly yours.
Manager of Public Works
s ©
HVC:clj
EPA Response
4y The positive value of Denver's digested sludge is recognized.
"Calculations of the cost benefit of using Denver digested sludge as a
coulltioning agent are shown in the discussion under Issue IV-4. The
City Mist recognize, however, that the secoodary waste activated sludge
generated at the Metro plant Is also in part Denver's sludge. This
also contributes to the present high cost of sludge processing at the
Metro District plant which has spurred the search for a better, less
costly way of disposal. EPA can sympathize with the City and County
that perhaps the original contract between the City and the District
is not reflective of current financial trends and aay need to be revised.
QSee discussion on water rights in Issue 1-3. This issue is not
p*eted to affect the development of the Metro project.
-------
11227 Woodson Ave.
Kensington, Maryland 20795
September 27, 1976
Mr. John A. Green
Regional Administrator
U.S. EAvironstnUl Protection Agency
Rocky Mountain - Prairie Region VIII
Suite 900
1860 Lincoln Street
Denver, Colorado BO203
Dear Nr. Green:
As a joint owner of a considerable portion of the land within the
proposed site for drying and storage of sludge from Metropolitan Denver,
I would like to comment on the draft Environmental Impact Statement (EIS)
regarding the Manageaent Plan for Vastewater Sludge.
A Major shortcoming of the above EIS is that it fails to adequately
address the issue of the irreversible destruction of quslity
farmland. Although the EIS briefly mentions the destruction of the
soil profile at the proposed site (B-2), no attention is given to
the quality of farmland at this site, nor are there comparisons of
agricultural quality of land at alternative sites.
The attached, recent memorandum from the Chairman of the President's
Council on Environmental Quality, August 30, 1976, instructs federsl
agencies to determine the existence of prime farmlunda in the areaa
sf impact analyzed in Environmental Impact Statements. Has information
on the relativs agricultural quality of land at the proposed sits been
obtained from the State Soil Conservationist for the purposes of the EIS?
I presume that the requirement in force since August 30, 1976, allies
to ths Denver Sludge EIS since it is still in the process of completion.
I bslieve that it is unconscionable, from both an environmental and
civil rights point of view, that the proposed Denver sludge disposal
might condemn private farmland rather than use potentially available
public land such as ths Lowry Bombing Range. Has EPA required the
full iavestigation of whether permission ean be obtained for use of
the Lowry Bombing Rang* for ths proposed drying/distribution site?
It would seem that condemnation uf private land would necessitate
irrefutable evidence that land already in the public trust is not
available.
I will appreciate your reply to this letter, with answers to my questions
Respectfully yours,
/ . • -
Betty Mund.ll Bennett
cc. Representative Ted Strickland
Marl in 0|>perWD, Attorney at La*
EPA Response
The discussion of farmland productivity loss as a result of the
site B-2 operation is found under Issues II-l, and II-8.
The Soil Conservation Service commented on this EIS, but did not
discuss the issue as to whether the lands affected by site B-2 were
considered "prime agricultural lands" as defined by the Council on
Environnental Quality. £?A has evaluated the potential for conversion
of prime agricultural lands in its Denver Overview EIS released in
June, 1977. Prime agricultural lands indentified were predominantly
irrigated farmland areas, particularly along the South Flatte River.
It is certainly EPA's intention to minimize the impact of its project
on existing farmlands. EPA would prefer to locate this drying/distri-
bution on public lands. However, the discussions under Issue IV-1
demonstrate that such public lands are not ismediately available,
and possibly never will be in this area.
-------
Attachment to Letter #34
EXECUTIVE OFFICE OF THE PREUDCNT
council. ON INVMONMKHTAL QUALITY
fit JACH&ON PlACC. N. W.
•AttlfMTON. 0. C. 20004
Letter #35
Auguat 30, 1976
MEMORANDUM FOR HEADS OF AGENCIES
SUBJECT: Analysis of Impacts on Prime and Unique Farmland
in Environmental Impact Statementa
This memorandum providea guidanoe to Federal agenciea on how
to carry out evaluation of the impact of major agency actiona on prime
and unique farmland in the courae of preparing environmental impact
atatementa (EIS). *
Paragraph 101(b)(4) of National Environmental Policy Act (NEPA)
eatabliahea a Federal policy to preaerve important hiatoric, cultural
and natural aapecta of our national heritage and maintain, wherever
poaaiblc, an environment which supporta diveraity and variety of
Individual choice. Thia policy ihould be underatood to include highly
productive farmlands.
Efforta should be made to aasure that auch farmlanda are not
irreveraibly converted to other uaca unlcaa other national intereata
override the importance of preservation or otherwiae outweigh the
environmental benefits derived from their protection. Theae benefits
• Prime farmlanda are thoae whoae value derives from their general
advantage aa cropland due to soil and water conditions. Unique farmlands
are thoae whose value derivea from their particular advantagea for
growing specialty crops.
•tem from the capacity of auch farmland to produce relatively more
food with l«aa erosion and with lower demands for fertilizer, energy,
and other resourcea. In addition* the preeervation of farmland in
general providea the benefits of open apace, protection of acenery,
wildlife habitat and, in aome cases, recreation opportunities and
eontrola on urban aprawl.
Aa part of lta policy to preaerve the Nation'a prime farm, range,
and foreat lands, the Department of Agriculture (USDA) haa recently
announced a general policy to establish and keep current an inventory
of prime and unique farmland. Recent eatimatea conclude that of
1.4 billion acrea of privately owned landa in the United States, approxi-
mately 275 million are classed as prime farmlanda.
Federal agenciea should attempt to determine the exiatence of
prime and unique farmlanda in the areas of impact analyzed in environ-
mental impact statementa prepared in compliance with Section 102(2)(C)
of the NEPA. This should include threats to the continued use and
viability of these farmlands not only from direct construction activities,
but also from urbanization or other changes in land uae that might be
Induced by the Federal action.
Continued next page
-------
The Department of Agriculture, it Us field locations throughout
the country, is committed to assisting Federal agencies in the ideati-
ficstion of prime or unique farmland a, end In nearly all cat a a has
complete information on land area* which may be impacted. Thia
should simplify and reduce the burden on other agencies in carrying
out their impact analysis. Initial contact should be made with the
USDA Land Use Committee in the state where the lands under con-
side ration are aituated. This Committee can be located by contacting
either the Chairman of the USDA Rural Development Committee in
the state, or any nearby USDA office. The State Land Use Committee
will then help facilitate contacts with the appropriate USDA office and
personnel so that all available Information on prime and unique farm-
lands within the project area Is accessible to the agency preparing an
EIS.
Finally, the Department of Agriculture has agreed to place a
major new emphasis on the review and evaluation of draft environmental
impact statements with respect to impacts on prime and unique farmland.
In undertaking these reviews, USDA will use soil, range, forest, water
resource, and other surveys and information which may be applicable.
Thia service of the Department should help improve the quality of all EIS a.
-4-
Further information on where agencies may obtain assistance in
identifying prime and unique farmland and analyzing significant impacts
on It from agency activities, can be obtained from State Soil Conserva-
tion Service (SCS) offices shown on the attachment. Information on
new USDA procedures to review impact on prime and unique farmlands
in draft EIS a can alto be obtained from these sources.
Russell W. Peterson
Chairman
Attachment
-------
Attachment to Letter it35
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-------
Letter #36
TRI-COUNTY DISTRICT HEALTH DEPARTMENT
<857 SOUTH OflOADWAY
ENOLEWOOO. COLORADO SO110
303 761-1340
September 28, 1976
Mr. John. A. Green, Regional Administrator
United States Environmental Protection Agency
Region VIII
1860 Lincoln Street
Denver, Colorado 80203
Dear Mr. GTeen:
This department has reviewed the draft Environmental Impact
Statenent on:
Managenent plan for waste vater sludge
Metropolitan Denver Sewage Disposal District No. 1
Denver, Colorado
E.P.A. Project Number: C0080341
Ci Yfe would offer the following observations and comments for
w the record:
i •
1. page 93. "The drying basins could process about 33,000
dry metric tons (36,000 short tons) of sludge per year.
Sludge applied to the basins in layers of 60 cm (24 in.)
can be expected to dry to 40 to SO percent solids in
about twelve months."
page 30. Indicates that 1974 sludge production was
357000 tons with a projection to 61,000 tons in early
1980's.
CD ^age 31. "Secondly, the actual time needed for drying
in the basins is not precisely known, A year's time
is assumed for design purposes, but longer or shorter
drying tiroes might be needed." "Metro District has
indicated that no raore than 180 hectares (450 acres)
of the proposed 240 hectares (600 acres) drying storage
area need to be developed immediately."
This department has had conversation with Metro
representatives as late as July 20, 1976. On that
occasion we were led to believe the proposal was to
charge the basins at I - 4 inch depth and not 24 inches.
At 24. inches there will be crusting which inhibits
evaporation and air drying- The majority of dewatering
would be by percolation, possibly causing water pollution
problems. This recent alternate proposal as to basin
loading is not covered in the HIS.
Continued next page
EPA Response
1J A discussion of the adequacy of Metro1£ design capacity for the
sludge drying basins Is presented under Issue 11*12. You should be
aware of soae inaccuracies in your assumptions under point #1 of your
letter: Metro's projected sludge generation for 1965 is expected to
total 61,000 tens as stated on page 30 of the EI5. Bovever, only
about 36,000 tons would reach the drying site because of anaerobic
digestion. Even If the Northside Plant were to add its supernatant
to the pipeline flow, the expected yearly aaount of flow would only
be about 345,000,000 gallons pet year, rather than the 716,750,000
gallons calculated under your point 2 (e). It is also very likely
that Metro's projections are high, since they aesurcd a 4-52 per year
grnrth rate; the Metropolitan area growth rate recently has bees be-
tween 2 end 3S. Finally, Metro indicates in their aost recent cor-'
respoodence that they are again proposing to load the basins with up
to 24" of sludge, Tathex than the 2-V depth they were claiming at
the tiAe your letter was written.
-------
Letter #36,
continued
U.S. Environmental Protection Agency
9/28/76, page 2
The degradation of ground water is also referred to
in the EIS at page 29 "Some water will be lost to evapo-
ration and some will stay in the dried sludge, but most
will move downward where it will likely result in
degradation of water quality to a degree that would make
the ground water unacceptable as a source for drinking
water."
-------
Letter #36%
continued
0
U. S. Environmental Protection Agency
9/28/76, page 3
digestion can improve the dewatering characteristics of
sludges (resulting in les? chemicals for conditioning}.
However, digestion of secondary waste activated sludge
may not perform in the same fashion. It might be
expected that odor and chemical-related problems at the
Lowry site will be reduced by the measures already under
construction. Conversion of the digestors to the thermo-
philic mode might further improve sludge dewatering
characteristics."
-------
U.S. Environmental Protection Agency
9/28/76, page 4
(c) That if the end product does not meet said standards,
we are assured it is disposed of in a manner that it
does not create a health hazard or nuisance.
We recommend this proposal be amended to provide the second
alternate stated in #4 above as the short term management plan
and the long term management plan be delayed until more is known
about the newly completed plant's sludge characteristics.
If there are questions, please contact me.
Sincerely,
Donald L. Turk, Associate Director
Environmental Health Services
DLT:bmm
-------
Letter #37
DEPARTMENT OF HEALTH. EDUCATION. AND WELFARE
PUBLIC HEALTH SERVICE
FOOD AND DRUG ADMINISTRATION
WASHINOTON. D.C. SUM
September 29, 1976
Mr. John A. Green
Regional Administrator
United States Environmental Protection Agency
Region VIII
1860 Lincoln Street
Denver, Colorado 80203
Refs 8W-EE
Dear Mr. Green:
Thank you for your latter and Cor the copy of the draft Environmental Impact
Statement for Metro-Denver'a Sludge Management Plan.
After an Informal review of this veil written document with several other
scientists, I have the following personal coaments and/or suggestions:
CD 0 Like most large cities, Denver produces sludge containing
¦"*' levels of heavy metals which are higher than the "background"
due to contamination, presumably by Industrial effluents.
Fortunately, levels (especially of cadmium) are not as high
as those of some other sludges, and land application la
feasible, provided suitable safeguards and controls are
exercised. However, reduction In the amounts of heavy metals
and organlcs (PCB, etc.) present Is highly desirable, and would
open up a broader range of use options. Such improvement
In sludge quality would obviously result by requiring industry
to pretreat their effluents sore thoroughly prior to discharge
to the municipal sewage systems.
(2) An area of concern is the unregulated and uncontrolled distri-
bution of sludge, compost or sewage in any form to farmers,
home gardeners and other users because of the potential for
Improper handling and abuse. If sludge/compost is available
free or at low cost, there is the potential for use of excessive
amounts on a given land area; present levels of chemical contaminants
in Denver sludge are high enough under such circumstances to cause
food contamination and adverse health effects. This is especially
so, if emulator crops are used or sludge is applied onto growing
crops, resulting in physical contamination. The possibility of
direct ingestion of sludge by grazing of domestic animals should
also be avoided.
Continued next page
EPA Response
UJ CPA agrees Chat In comparison Co aany American metropolitan areas,
Hetr© Denver's cadniua levels are quite lev. EPA will also continue
to press the District to develop policies that vill require industrial
pretraataent thus lowering the quantities of heavy metals and toxic
organics in the sludge. See discussion under Issue 1-1.
EPA vill develop recommendations for the District as to preferred
and unsatisfactory uses for the sludge. Tour reconendations vill be
closely followed» particularly in the areas of hose gardens, grazing
aniaals, and excessive applications where cinsulator crops are involved
See discussions under Issue V-l.
-------
Letter #37,
continued
©
cr>
oo
-2-
Denver sludge would, as Che project progresses, be digested
anaeroblcally in Its entirety. This should reduce the micro-
biological hazard, but not eliminate it. According to recent
studies, even digested sludges contain ascarls ova (worm eggs)
and other pathogens, which may survive on soils and crops for
long periods of time. For this reason, sludge should not be
used If crops are planted which are eaten raw or are brought
into the household or kitchen prior to cooking. Uncontrolled
use of sludge may present human health problems, and this is
more likely to occur when sludge is sold or given away.
In summary, I feel that the following is advisable: 1. To use Denver
sludge on which is owned or leased, so that proper controls can be
exercised as to the rate of application, the nature of the crops grown,
agricultural practices used, and their timing. 2. Sludge may be sold
or given away, if the State of Colorado enacts suitable laws/regulations
which will provide appropriate limitations, penalties, controls and
monitoring to prevent abuse in all its forms. 3. Further research by
Matro-Denver and also efforts by the city to reduce its pollutant inflow
are desirable and should broaden Denver's options in this area.
Thank you for the opportunity to con&ent on this document,
free to contact ae if I can be of further help.
and please feel
Sincerely yours,
George L. Braude, Ph.D.
Chemical Industry Practices Branch
Division of Chemical Technology
HFF-424
EPA Response
EPA will recommend that Metro be required to inform potential
users of this hazard. The State of Colorado will have primary re-
sponsibility for enforcing regulations on sludge use (see Issue V-4).
In regard to the following recomnendatiotis, some lands such as
parks are owned by local municipalities and can control the rate of
application of sludge. However, the bulk of the disposable sludge
could end up in private hands. The State of Colorado is in the process
of enacting regulations on the use of sludge. EPA vill require that
Metro dried sludge not be distributed offsite (except where munici-
palities have control of the sludge), until such time as the State
adopts its sludge regulations. EPA will also press the Metro District
to reduce its industrial contribution of heavy metals and toxic
organics.
-------
Letter #38
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
Dearer Airports District Office
10255 Eaat 25th Avenue
Aurora, Colorado 80010
en
»sD
O
©I
Regional Administrator
U. S. Environmental Protection Agency
Bocky Mountain - Prairie Region YUI
i860 Lincoln Street, Suite ,>00
Denver, Colorado 80203
SUBJECT: Metro Denver Sludge Management Flan
Gentlemen:
Ve have reviewed the draft environmental impact statement for the subject
project and wish to offer the following concents for your consideration.
This agency is participating in the development of a master plan for a
new general aviation airport to be located in County. Potential
sites for the proposed airport have been subjected to an airspace feasibility
analysis and although the site selection, is Btill subject to concurrence of
the Artamn County Cosmissian, the site located jjnaiediately vest of the pro-
posed sludge processing and disposal site has been indicated by this agency
as being the most desirable of thoae identified for study.
Hie forecasts of aeronautical demand to be placed upon the proposed airport,
indicate that it should be developed to serve a significant segment of the
general aviation activity in the Denver metro and northeastern suburban area.
Experience has shown us that airports of this character have a decided
attraction for aviation oriented business development and subsequent sup-
portive residential development. Ehie very desirable business development,
not only adds to the tax base of the County, but also provides a by
which the airport can become an economically sound public entity which causes
no burden upon the taxpayer
It is felt that the proposed sludge processing »r>H disposal site may alter
the existing environmental characteristics of the area, for which it is
planned, sufficiently to detrimentally affect the development of the proposed
• airport.
Specifically the feared potential environmental impacts and resultant affects
are as follows:
A. Air Quality: It is feared that the odor produced from the
processing and disposal operation will be sufficiently
objectionable that the development of business and residential
areas in the vicinity of the airport would be depressed.
Continued next page
ETA Response
The issue of potential land use between the proposed Adams County
Regional Airport and the Metro drying site is discussed under Issues
11-9 and 11-10.
This issue is also discussed in Issue 11-9. There vill be soae
odors as a result of this project operation. However, the drying
basins vill be located perhaps two miles to the east of the proposed
airport site in the direction of the prevailing vinds. Stapleton
Airport, incidentally, has directly to the east of the east-vest run-
way, a sludge drying area operated by the City Parks Department.
Very few odor problems have been noted. We do feel that since the
business activity involved with the airport will have most of its
interaction with the urbanized area to the west of the airport, such
a potential "depression" of business development would be minimal.
Vie were not aware that residential development in proximity to an
airport was to be encouraged. EPA still feels that with proper coor-
dinated planning on the airport and sludge site, the open space func-
tion of the sludge drying site would be very compatible with airport
development.
-------
Letter #38f
continued
O
G>
0
B. flood Chaini It 1b feared that the drying beds nay have
& potential for the attraction of birds whlnh could cxeata
a collision hasaxd far aircraft.
C. Natural Bivironaent: It ia feared that the high moisture
content and haat oxidation may have a potential for the
generation of fog or low visibility condition* in the area
proposed for aiting of the airport.
D. Construction Conflict: It is feared that the routing of
the pipeline to the proposed sludge processing and treatment
facility nay be in the immediate area of excavation for
construction of airport facilities, thereby jeopardizing
design features or escalating the cost of construction of
airport facilities.
E. fiiergy: It ia feared that the competitive demand for
utilities (water, electrical energy) aajr be of such severity
that airport related bosinaaa and residential develojKerit
would be depressed.
V* appreciate the opportunity to cooaent on the subject proposal.
Sincerely,
t
3sL1 C4.
V SDtfAED G. TATTK, Chief
Denver Airports Iti strict Office
EPA Response
QThia iten is discussed under Issue 11-10, The lack of a food
tree for birds would lessen this possibility. If the TkA still
thinks that birds could be a hazard at this site, EPA vould be happy
to utt with FAA staff to discuss specifics such as required LTO
distances & positive prevention steps that could be taken to minimize
this hazard.
o
See discussion under Issue 11-10.
Issue 1-2 lays out the pipeline routing froa the Metro Central
plant to the drying site. The pipeline will be laid in the 88th
Avenue right-of-way at a depth of 5-10 feet. We do not anticipate
that this would cause a problem greater than any other buried utility
such as gas lines or water lines.
Tbe EIS demonstrates that there are sufficient utilities present
in tbe area (roadway capacity, electrical power, etc) to aupply the
Metro facility. Should rapid developaest of the airport and urban
ftrnrth occur in this area, there will have to be wholeaale additions
of utilities of all foms. We seriously doubt the existing utilities
could perform such a service. A description of potential growth trends
in the area as predicted by DRCOC to the year 2000 is found Its the
discussion uder Issue II-6.
-------
jo-4-^
BENEDETTI. OPPERMAN & MARTINEZ. P C. .
ATtomrrt amo couwwllom at law vl»'
ONI MUM CCNTRAL SUIT* «4«
DCNVCH. COLORADO MtOI
(MS) IIS-tlTO
^fjX-
FMILC HNIDCrn
HMUN P- UWMWM
viviam T tuurrmaz. jm
joHNA-HUNiHoa October 4, 1976
Mr. John A. Green
Regional Administrator
U.S. Environmental Protection Agency
Rocky Mountain - Prairie Region VIII
Suite 900
1860 Lincoln Street
Denver, Colorado 80203
Dear Mr. Green:
This office represents certain persons owning real
property located at the proposed B-2 Site for the Metropolitan
Denver Sewage Disposal District's proposed sludge processing
facility. This letter on behalf of said landowners is intended
to be recorded in the official record of the Environmental Pro-
tection Agency as a comment upon the Draft Environmental Impact
Statement concerning the proposed sludge facility and its site
selection.
Mr. Marlin D. Opperman of this office presented an oral
statement during hearings held by the Environmental Protection
Agency.
The Draft Environmental Impact Statement has failed to
fully analyze available data, has failed to properly compare
alternative processes and site locations, and has proceeded
on the basis of improper comparisons and assumptions. These
defects are most clearly demonstrated in the following three
aspects of the Draft Environmental Impact Statement.
First, the draft analyzes and compares only present
landfill cultivation operations conducted at the Lowry Site
and the proposed B-2 Site. No other methods of sludge processing
are thoroughly analyzed in the draft statement, including the
method of ultimate disposal. Changes in the thinking of the
District as to utilization of the final product have not been
analyzed to determine their effect upon site selection.
Continued next page
EPA Response
EPA's position regarding the evaluation of alternative* (here
termed alternative systems of sludge processing) is that all reason-
able alternatives should be evaluated. Because the nusfcer of systems
can get inordinately large vith changes in one or sore unit processes
within an overall system, it Bakes sense to talk about general ap-
proaches. EPA experience has been that it Is the sludge disposal
(as opposed to in-plant treatment) that results in the potentially
greatest environmental problems and also public controversy. There-
fore, EPA developed its analysis of overall methods of sludge disposal
alternatives; by necessity, the discussions had to be correspondingly
general. Options such as composting, land recycling, the present
method of landspreading, Incineration, and landfilling are the basic
ways to dispose of sludge. Table 2 in the EIS (Volume I) identifies
the key environmental impacts, engineering factors* costs, and a
discussion of institutional ability to Implement. At a preliminary
level, this kind of analysis fj»n be used to judge the relative merits
of these proposals. Since most of these systems are in use at one
place or another in this country, it is not unreasonable to assume
that any or all of these systems could be used. EPA's nationwide
experience is that they can all be used; EPA has never endorsed one
particular form of sludge treatment and disposal. Only local varia-
tions are likely to make one system preferable to another, such as
institutional constraints. In addition, the Metro District has ana-
lysed three different systems in detail—incineration, the land
recycling scheme (an earlier version), and the present system of oper-
ation. Engineering-Science, the environmental consultant for this
EIS, coated out and achematically defined 16 system alternatives that
could be used in the Metro situation. Additionally, EPA specifically
requested that a promising alternative— that of combining sludge
with the DRC0G solid waste proposal— be evaluated, institutional
constraints in this case made the prospect unrealistic. The discussion
under Issue IV-3, discusses other potential systems suggested in the
course of this draft EIS review.
The analysis of sites for the proposed Metro systeo did identify
and comparatively analyse criteria for site selection (see Agricultural
Reuse Program, MDSDD #1, March 1973). Additional environmental anal-
yses of the three most preferable sites are also comparatively analysed
(see Appendix G, Volume 1 of this EIS).
-------
Letter #39.
continued
0
t
G>
<3>
-*sj
PO
€>
Pag* 2
October 4, 1976
Without a clear analysis of the alternative sludge pro-
cessing methods, their environmental impact, ultimate disposal
of the processed sludge, and its environmental impact, the
Environmental Impact Statement would fail to satisfy the
statutory prerequisites for an analysis of project alternatives
Secondly, the Draft Environmental Impact Statement has
not properly compared the proposed B-2 Site with the Lowry
Site. The Environmental Protection Agency should compare
sites only after it has fully analyzed the alternative methods
of sludge processing. Once a particular process has been
settled upon, for instance, the proposed sludge drying beds,
all site selection should be evaluated on the basis of the use
of that process.
The Draft Environmental Impact Statement compares the
present landfill cultivation operation conducted at Lowry
Site with the proposed drying facilities at the B-2 Site.
Neither the Lowry Site nor any other site has been evaluated
on the basis of use for the sludge drying facility. Before any
proper Environmental Impact Statement may be completed, the
alternate sites including the Lowry Site must be evaluated on
exactly the same basis and in exactly the same manner as the
B-2 site. Such an analysis should assume utilization of the
sane technical process at both sites. It should assume col-
lection of the same data on each alternative site. Finally, it
should assume the same conclusion that the selected site will
not be used for final disposal of the material produced. None
of these conditions have been satisfied, and therefore, compari
•on between the Lowry Site and the B-2 Site is defective and
its use as the basis for a Final Environmental Impact Statement
would not satisfy standards for such a statement.
Thirdly, the Draft Environmental Statement has been
issued without analysis of available test boring data taken by
the Metropolitan Denver Sewage Disposal District. This data
is now available and was just received by our clients and our
office on Friday, October 1, 1976. Such data analyzes
the soil structure of the proposed B-2 Site and our preliminary
analysis suggests that substantial percolation problems may
exist and that ground water contamination may be possible at
the B-2 Site. This data was available to the Metropolitan
Denver Sewage Disposal District at the time that the Draft
Environmental Impact Statement was being finalized and printed
and that draft should have been delayed until this data could
have been evaluated. Because the Metropolitan Denver Sewage
Disposal District had full access to and complete control of
this data, delaying release of the data until this date sub-
Continued next page
EPA Response
t j EPA agrees with your point th*t the Lowry «ite should have been
systematically coapared with the other potential sites for the Metro
sludge drying project. This analysis Is presented under Issue rv-1.
Based on this analysis, EPA thinks that the B-2 is still a better site,
but that the Lowry site could be a reasonable option. Institutional
constraints, couple* land ownership, and higher elevation, all make
the Lowry site less favorable than B-2. It should be noted that the
City and County of Denver has refused to allow Metro to use the Cltv-
ownad land at Lowry for the peraanent drying facility (see letter 19).
EPA does feel that only the Lowry site, where the existing sludge
ration ia already taking place, needs to be systematically analysed
Othar Lowry options would involve taking new lands, some of which are
in private ownership (see discussion uder Issue IV-1 for a map of the
existing Lowry ownership).
UyJ D>A did recognize that there was a lack of soils and groundwater
data for the B-2 6ite analysis; EPA also felt that there was enough
uncertainty as to when the data would be available to Justify going
ahead vith the draft EIS. The CB2K-Hill Geo technical ana Soils Report
Is now available and has been used in the analysis of soils and ground-
water at the B-2 site presented in Issue Xl-1 and Issue II-2.
-------
Page 3
October 4, 1976
stantially prejudices the ability of ourselves and our clients
to fully analyze this report and make appropriate comments on
the Draft Environmental Impact Statement in view of this data.
Furthermore, no such data has been taken of the alternative
Lowry Site. Therefore, a proper soil analysis is not presently
available to permit a proper comparison between the B-2 Site and
the Lowry Site.
The Draft Environmental Impact Statement fails to address
itself to other applicable governmental regulations affecting the
site selection process. This includes other significant environ-
mental implications for future land uses in the general area
including industrial and airport uses, and the effect upon
developed communities in the nearby area such as Watkins and
the town of Bennett. Without an analysis of the complete land
use implications of the proposed sites, the Environmental Impact
Statement will have failed to evaluate all significant environ-
asntal impacts inherent in such a proposed project.
Therefore, it appears clear to our clients and ourselves
that a Final Environmental Impact Statement cannot be prepared
or issued until the above studies have been completed. In
particular, it seems imperative that the Environmental Protection
Agency should include a full analysis of the soil tests taken at
the B-2 Site and should require a similar analysis of alternative
sites before proceeding with any further revisions of the Draft
Environmental Impact Statement.
Furthermore, wherever the Draft Environmental Impact State-
ment: reflects lack of information available or fails to state
the exact basis for conclusions reached, the Environmental Pro-
tection Agency should require that the Final Environmental Impact
Statement be delayed until such informational gaps are filled.
The opportunity to comment on the Draft Environmental
Impact Statement prior to any issuance of a Final Environmental
Impact Statement certainly encompasses the right of our clients
to have a full and complete opportunity to comment upon the soil
test data available to Metropolitan Denver Sewage Disposal
District which was made available to our clients October 1, 1976.
Metropolitan Denver Sewage Disposal District cannot expect to
comply with the requirements of NEPA by releasing essential data
at a late date and then hoping that Environmental Protection
Agency will proceed according to the most expeditious schedule
permitted by statute. The Environmental Protection Agency should
Continued next page
EPA Response
The Hetrc District was concerned about potential groundwater and
surface water contamination at the Lowry site, and hired the US Geo-
logical Survey to do a surface and groundwater study at the Lowry site.
The data in the subsequent report does allow a comparison of the Lovry
and 3-2 sites.
©
Effects on adjacent land uses is discussed under Issue II-9.
Qy EPA has decided to prepare the final EIS on this project, rather
tnan a revised draft EIS. Although review of the final EIS calls for
only a 30-day period» EPA wil) honor any requests during this tiae
period for reasonable additional time to complete a review. EPA will
also be willing to meet with Interested parties at their request to
discuss issues in this EIS.
Uncertainty exists at all levels of understanding; this is parti-
cularly true in the field of environaental ispact evaluation. EPA
feels that its responsibility Is to sake the decision-makers and other
readers aware of where areas of uncertainty exist. However, a decision
oust still be made whether or net to proceed based on the current state
of knowledge. In this case, areas of uncertainty are spelled out in the
discussion under Issue 11-11. SPA feels that tbe project will still raeet
its principal objectives given the propeT mitigation measures (such as
basin lining). Other areas of uncertainty include political-institu-
tional ones such as the review by the County for a Site Designation
Permit. EPA sees no particular merit in waiting, given the lack of
initiative by the District or the County to begin this process. If
after such a review, the project is deened infeasibie for one reason
or another, EPA will be willing to consider other alternatives. This
EIS can provide technical information that may be helpful to other
decision makers in deciding the fate of this project.
-------
Pag* 4
October 4, 1976
require the Metropolitan Denver Sewage Disposal District to
await EPA determination until such time as EPA has received
all of the data necessary for evaluation of the proposed
sludge drying facility and has evaluated all soil tests
necessary for proper site selection.
Very truly yours,
" John A. Meininger
JAM:sr
-------
Letter #40
BOARD
OF
COUNTY COMMISSIONERS
ADMINISTRATION BUILDING
450 SOUTH 4TH AVENU£
BRIGHTON, COLORADO S0601
SO<6S»-2120
COMMISSIONERS
John (3. GvnpMtf
p*f m m fi*2
I M. Cony
CL£RK OP THE BOARD
WtMvn Soirof
October 4, 1976
Ur. John A.Green, Regional Adminstrator
United States Environmental Protection Agency
Region VIII, 1860 Lincoln Street
Denver, Colorado 80203
RE: Draft Environmental Impact Statement on Management Plan
for ffestewater Sludge by Metropolitan Denver Sewage Disposal
District So.l, Denver, Colorado, EPA Project Number: C0080341
cn
O
Dear Mr. Green:
Any determination of approval or disapproval of the above refer-
enced project by the Environmental Protection Agency (EPA) should
be withheld until the Adams County Board of County Commissioners
have made a decision on a certificate of site designation pur-
suant to 30-20-102, Colorado Revised Statutes 1973, as amended.
It is felt that EPA should be aware of local considerations and
decisions on this project to adequately assess all impacts.
The agricultural reuse proposal of the Sludge Management Plan
for Metropolitan Denver Sewage Disposal District No.l (iletro)
raises serious potential environmental concerns for Adams County.
ITith proper control and mitigation procedures, the use of sludge
for agricultural purposes could be a beneficial use. However,
the Environmental Impact Statement (EIS).demonstrates that in-
sufficient knowledge of hazards is available at this time and
that adequate management and control systems have not yet been
delineated.
There are several concerns with this project which the EIS does
not adequately answer:
1. A management/inspect ion program has not been developed to
insure that proper controls are used to prevent misuse (over-
. application) of sludge material and to inspect disease dan-
gers. Also, cessation procedures need to be prepared should
noncompliance occur. ^ho will provide these services and how
will it be paid for?
Continued next page
EPA Response
EPA considered the possibility of avaiting such a eite designation
process before issuing the final EIS. We have, however, decided to
release the final EIS for a number of reasons. For one, there has
baen no action on the part of Metro District or the County to begin a
formal proceeding on this issue. Wore importantly, EPA think.6 that
since the EIS has been prepared with a great deal of technical infor-
mation, such information could be of value in making decisions about
the project. We also think that since th* iopact issues on this pro-
ject are now fairly veil defined a reading of this final EIS will b«
helpful in determining bov some of the impacts can be minimized through
aitigating grant conditions, and whether the resulting project is
acceptable. EPA will not fund Step II (design) or Ste? Ill (construc-
tion) phases, unless the Site Designation process has been satisfac-
torily resolved. We shall closely consider the decision of the County
Commissioners on this action. Should the turn of events so dictate,
EPA would be willing to perform supplementary EIS work. EPA is highly
¦ensitive to local concerns on this project; we shall be guided to a
large extent by those decisions.
2y A discussion of management and control of sludge applications is
?rejected under Issue V-4. State regulations are currently being de-
veloped; EPA will require Metro to agree not to disseminate dried
sludge except on city—owned lands, until Buch time as these regula-
tions are finalized.
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Ur. John Green
Page 2
The very real problem of dangers from improper management is rec-
ognized on page 9, and elsewhere in the E.I.S. The E.I.S. stres-
ses that it is a very important and implicit assumption that sludge
application rates be adhered to by the recipients of the materials.
As such adherence can not be guaranteed and to the extent that
recommendations are not followed the number and severity of impacts
will increase. The very fact, that no prodedures have been enumer-
ated to establish management/control systems to monitor possible
misuses is cause for concern. On pages 147 and 184 it is suggested
that record keeping, inspection of sludge application operations on
individual sites and monitoring of environmental parameters are
functions which must be carried out by Metro or another responsible
agency. It is further suggested,that it would be adviseable to
establish binding agreements permitting monitoring and inspection
and to provide for cessation of sludge supply in cases of noncom-
pliance. These procedures have not been established and are not
envisioned in present plans (page 192) and may be difficult to
obtain from the farm owners without interferring with the farmer's
operating rights. The monitoring and control program has not been
sufficiently developed or analyzed. It is doubtful that it would
be acceptable for Metro to provide these functions and, this raises
the questions of who would and how would it be paid for to insure
unbiased management. It would be difficult to accept the sludge
reuse proposal without an adequate and acceptable management/in-
spection/cessation plan.
Continuing with the management/inspection situation it would appear
that even if a mechanism were established, it would create a very
significant inspection and records keeping system which could easily
result in inadvertent errors, resulting in significant environmental
or health problems. On page 145, it is recognized that the public
health department would have increased monitoring activities to
cover all the land recycling areas receiving sludge. Can the health
department adequately increase its manpower requirements and how
should this rightfully be paid for? On page 81 health concerns with
the project is assigned to the Tri-County District Health Department,
but there is no indication as to whether or not they would be able
to establish the manpower requirements generated by this additional
responsibility.
Pathogen problems appear to be low while salts accumulation pro-
bleas are high but, to a significant degree depend upon proper
management and operation procedures. Stronger evidence of proper
health inspection, management, and operation procedures should be
provided.
2. Since federal grant funds are currently unavailable
Metro should demonstrate how it will fund the project?
Much of the capital cost of the project would be from a 75% grant
through the Environmental Protection Agency (EPA). Since there
are currently no funds available for this type of project (page 10)
it should be necessary for Metro to demonstrate how it would fund
this project should funds not become available. This does not
Continued next page
EPA Response
See discussion under Issue V-4. EPA recommendations to Metro are
contained in Appendix A of this Volume.
This problas will have to be worked out with the State, which hmm
primary enforcement responsibility. Perhaps with close cooperation
with the Metro District, voluntary reporting and mutually acceptable
policies on sludge use could lessen this burden.
J The draft EIS reported that at that time, no federal funds were
areliable for construction of this project. Since that tine, Congress
haa authorized additional monies that could be used. In addition*
Congress is now contemplating long-term future authoriratione of money
for wastewater treatment construction as high as $45 billion dollars
over the next ten years. The likelihood is now high that this project
would be paid for with federal funds upon approval of the facilities plan.
-------
llr. John Green
Page 3
appear in the report.
3. Detailed information on soil conditions and groundwater
depth and quality at the distribution center should be essential
to insure proper design of the facility.
The Lost Creek Groundwater District has indicated opposition to this
project because it would pollute their Systran and be contrary to
their management criteria. The Lost Creek Basin has been described
as a closed basin with many intermingling aquifers. Only fresh
water recharge is allowed in the District and no other sources should
be injected into the basin. To avoid contamination, a soils anal-
ysis is essential, liuch of the processing site area is to be
used for marketing, research, and demonstration plots to test var-
ious sludge loading rates. Subsurface injection rates as high as
390 tons per acre would be used should insufficient markets develop
(page 96). Such high rates would eventually contaminate the closed
basin which is in conflict with the management criteria of the
Water District. The project does need to take this into consider-
ation. Since the test plots are considered an important part of the
project the inability to use the test plots would make a significant
change in the project design,and this problem needs to be investigat-
ed. The project,if approved,would need sealed drying basins and
bentonite would not be acceptable because it would be damaged when
the dried sludge was removed from the drying beds. Sealing with
concrete may be an acceptable method, but for 600 acres this would
be extremely expensive. This expense has not been included in pro-
ject costs as a possible alternative, Honitoring systems placed
under the drying beds to detect pollution would provide a warning
which may be too late. Even if Metro were to pump the polluted
water out,some would get past and then there is also the problem
of what to do with the pumped out water since it could not be re-
moved from the Water District.
Detailed information on soil conditions and groundwater depth and
quality is not available for the distribution center site (page
25 and 28). This information should be considered essential prior
to any decision and could have major impacts on the design of the
disposal system. Some soils testing has recently been done by
Metro, but this information has not been made available to other
agencies. It is requested that Adams County be provided with all
pertinent information so that it can be analyzed by the County.
»
4. The project would cause degradation of groundwater which
may be in direct conflict with CRS 25-8. The issue of whether
or not the high levels of groundwater degradation at the dis-
tribution center and the lower levels at individual user sites
would be acceptable under CRS 25-8 has not been addressed.
Perhaps the most significant impact is the inevitable degradation
of water quality by nitrates to a degree that would make groundwater
unacceptable as a source of drinking water (page 29). This envir-
onmental impact should be sufficiently objectionable to consider
. this project unacceptable. Denitrification mitigation is unknown
for the sites (page 29) and definitely needs to be resolved before
Continued next page
EPA Response
A detailed discussion of the existing groundwater situation in the
vicinity of the 3-2 site is presented in Issues II-l and II-2. EPA
recognizes the valid concern of the Lost Creek Groundwater District in
wanting its ground and surface waters protected. EPA will therefore
require the Metro District to provide a lining of specified thickness
and permeability. This Information is presented under Issue II-2. A
discussion of alternative lining methods is presented in Issue IV-2.
Some of the soils and groundwater information developed by CH2M-
tfill for the B-2 site is presented in Issues II-l and II-2. Copies of
the original reports will be made available to the County upon request-
^8J EPA believes that groundwater contamination at sludge use sites,
given proper application rates baaed on available nitrogen, will not
cause groundwater probleas. At a minimum, problems should be no worse
than that experienced from present fertilizer applications.
^ Permeability calculations for the lining at site B-2 have been
made with drinking water standards in mind. Metro will also be re-
quired to submit a groundwater pumping plan in the event that moni-
toring in and around the site indicates a pollution problem. Extensive
monitoring will also be part of the Metro operation, run by the US
Geological Survey (see Appendix D).
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ilr. John Green
Page 4
finalized design of the drying basins. Current design does not
include lining of the drying basins to prevent percolation (page
110) and it is merely suggested that it may be necessary to do
so (page 111). Cost estimates or such a procedure are not pro-
vided. Since the degradation of groundwater may be in direct
conflict with CRS 25-8 it would appear that measures need to be
taken to prevent this from occurring. The Colorado Water Quality
Control Coomissioa is currently considering specific standards for
groundwater contamination. As the contamination potential is
greatest at the drying basins this should be of major concern.
Slitlgative measures for slowing leachates from moving to the water
table on page 181 are not sufficient. On page 185 it is also re-
cognized that the leaching process can only be slowed and indic-
ates that applications would have to stop when concentration be-
come too high and that potable use of water would have to be res-
tricted. Mitigation procedures need to be established to prevent
the loss of potable water, by establishing much lower permissable
lev©ls of application. Off site contamination is also inevitable
although to a lesser degree and over a much longer period of time.
However, the issue of whether or not these levels would be accept-
able under CRS 25-8 has not been addressed.
5. iiore definite scheduling of operation procedures should
be provided.
The actual time necessary to allow for drying of sludge in the bas-
ins is not precisely known (page 31) and this could have signifi-
cant impacts on the designed staging of the facility. This ties
in with points 3 and 4 concerning the need for lining the drying
beds. As one of the factors in drying the sludge would be percol-
ation the use of concrete to line the beds would have an effect
on the drying times. The Incorporation of drainage tiles in
the concrete system would greatly increase costs which have not
been calculated. At the designed application depths of 24 inches
(page 93) it is probable that crusting would occur. This would have
an inhabitory effect on the drying rate through evaporation and
Increase percolation needs. In addition, the potential for the
creation of odors would increase. Careful investigation of cal-
culated drying rates and odor problems should be made. The dried
sludge would be stockpiled until used and it is indicated that to
prevent the blowing of the material during high winds that a spray-
ing system would be provided to wet it down. There is a definite
concern that this would not work as well as planned and that signi-
ficant blowing would occur posing health dangers over a large area.
Since the occurrance of strong winds could not be predicted fax
enough in advance, it would probably not be possible to adequately
schedule wetting times. Another concern is the potential of salts
accumulating on the surface and being blown onto surrounding lands.
Information on the degree of salts deposits subject to blowing is
not provided and should be investigated.
A significant concern was expressed during the public hearings con-
cerning the drying periods for the sludge. It was felt that during
Continued next page
EPA Response
EPA feels that groundwater pimping as a backup system is ieasible
because of the geological configurstioo under the site. Test borings
have indicated that for the most part, a very impermeable layer of
¦iltscone and claystone underlies the 1 to 6m (2 to 20 feet} of soil
material. A perched aquifer would likely develop over tftifc impermeable
layer, allowing for reaoval of contaminated water by pumping. The
possibility does exist that on at least a small portion of the site,
the bedrock may be as porous or more permeable than the overlying
materials. In this case, no perched aquifer would form. The area
Identified lies in the northwest corner of the site, near the loca-
tion of the catchment reservoir. Here, however, water quality from
the runoff reservoirs may still meet drinking water standards after
percolation. A final consideration is chat in the relatively low-
probability event that some leachate does reach an aquifer, the rela-
tive volumes of leachate to native groundwater flow will determint
the final concentrations. In this case, only nitrates and salt con-
centrations would be of concern; pathogens, solids, and organic con-
taminants would he essentially removed by the soil filtration process.
In the discussion of basin drying capacities, EPA concludes chat
the design Is probably conservative, and that there is sufficient
capacity to handle 1965 design, year sludg* flows. Ue do agree that
lining of the basins could here an affacfc on overall drying times.
Metro's experiments ae Greeley indicated chat very little percolation
water moved baa**C& drying bads- containing a relatively lazuiy sell.
Metro conclude* fchet rapid aaaiing of ttm soil layer cook place. Sim-
ilar data ttom the San Joae, California drying baiins indicates that
drying tiana comparable Co Metro'9 were experienced in an area of
shallow groundwater and clayey soils. The operators at San Jose in-
dicated that at times groundwater may actually flow into the drying
basins (Reference 24). Metro plans to use equipment on the drying beds
Co break up the surface crust periodically-
(12} Discussions on odor (Issue II-3) and wiodbloving (Issue 11*5)
should be consulted. Salts are not present in high enough concentra-
tions to blow; the salts are interspersed in the dried sludge.
-------
Mr. John Green
Page S
a wet year the stockpiled material would absorb water and prolong
the drying periods. Uetro Indicated that the water would be shed
off tbe piles while EPA's consultant felt the material would absorb
water. This concern was not addressed in the EIS and should be
investigated.
6. Insufficient knowledge of dangers from heavy metal accum-
ulation in tbe human food chain is of concern.
The uptake of beavy metals by plants grown on sludge distribution
sites varies with the type of plant and the growing conditions.
Additional Information is needed to better understand the impact
of heavy metals, particularly nickel and cadmium. The U.S. Food
and Drug Administration has yet to promulgate guidelines for con-
trol of levels of possible harmful substances in sludge applied
to crops which enter the human food chain (page 87,112). Sug-
gested loading rates in the project attempt to be cautious but
the safe levels still are an unknown. One mitigation procedure
for safety of meat from animals grazed on or fed from sludge grown
crpps would be to dispose of the kidneys and livers which are organs
of metals concentration . The economic impacts of such a loss are
not Included (page 184).
House Bill 1191 amended 30-20-102, CR3 1973 to permit the bene-
ficial use of sludge which has been processed and certified or des-
ignated as meeting all applicable regulations of the Department
of Health and the Department of Agriculture. Without the exlst-
ance of such regulations establishing safe standards there can be
no market for the dried sludge.
7. There may be conflicts with the proposed Adams County
General Aviation Airport caused by insect nuisance and the
attraction of birds which could cause accidents with air-
craft. Concern also exists with the compatability of des-
ired industrial development around the airport.
The report suggests (page 93 and 126) that the sludge drying site
would be compatible as a land use with the proposed Adams County
General Aviation Airport which may be in close proximity. A
recent concern expressed in a letter dated June 17, 1976, to
Mr. John Green, Regional Administrator, EPA, requests assistance
in evaluating tbe possible impacts of Insects breeding at the
site and causing a nuisance in themselves as well as attracting
birds which could cause accidents with aircraft. Tbe evaluation
of compatibility of the sludge site with off airport growth such
as for industry is also being evaluated. From a point of view
of creating a clear zone for the aircraft and reduction of res-
idential pressures, the sludge site may be a benefit to the pro-
posed airport, but this needs to be re-evaluated in light of
the concerns expressed in the letter to the EPA.
The Phase II portion of the airport study is to evaluate the pot-
ential site alternatives, environmental impacts and reconmend the
best site. Significant analysis has been accomplished to date and
the Federal Aviation Administration has evaluated the site alter-
Continued next page
EPA Response
s
(q Occasional wetting of sludge is not believed to present * probl«.
overall dryness greater than 4CV-30Z can be achieved. Hater added to
this material simply results In a damp, spongy material that Is more
stable.
Discussions on heavy metals limits on sludge use Is presented
under Issues V-l and V-4; discussion on source control of heavy metals
at Metro Is presented under Issue 1-1. The FDA did provide a letter
of coa«Qt (see letter #37).
±y As stated elsevhere, IPA vill not permit Metro to disperse sludge
uStil State regulations on use of sludge sre finalized.
fiy EPA maintains
patlble land uees.
Issue 11-10.
that the sludge site and the airport can be com-
Thls Issue Is discussed under Issue II-9 and
-------
Mr. John Green
Page 6
natives indicating that site E is the most desirable of the three
locations. This is located approximately two and one half miles
west from the western edge of the sludge drying site. However,
a determination by the County as to which site will be selected
is still pending. After a site selection is made this will only
determine which site will be given full investigation and does not
mean that a decision to develop an airport has been made.
8. Metro's management plan should include Metro obtaining
development rights in a buffer zone of at least 2 miles in all
directions around the distribution center to protect the
public from potential hazards from insects, pathogens and water
pollution.
Consideration of the location near the proposed airport brings to
light a point for consideration that is not addressed in the report.
is suggested that some procedure be established to maintain a
buffer zone around the sludge site of perhaps 2 miles in all dir-
ections to prevent conflicts. This may be through the obtaining
of development rights.
9. The design life of the project nay appear acceptable but
the long term implications of the project on soils and ground-
water are significant and of great concern. Sufficient in-
formation on long term impacts is not provided.
The report itself asks a very important question which is not ade-
quately addressed, it summarizes a major long term concern for en-
vironmental impact, "The land recycling proposal by Metro will pro-
bably have a duration of 25 to 50 years. This is a rather long
period of time, given the rapidity of change in today's society.
Nevertheless, it is a fair and important question to ask what the
implications of the project may be for the next few hundred years
with regard to the soils." (page 194)
10. Further investigation of incineration of non-anaerobically
digested sludge with solid wastes or with coal should be at-
tempted considering the increasing value of energy resources.
Although current legislation is not amenable to this the long
term nature of this project may make this alternative more feas-
ible within a reasonable amount of time.
On page 9, a trucking distance of 60 miles for air-dried sludge for
land application is established as cost effective. Although, it
would appear there should be adequate land area to dispose of
this material, there have been no preliminary agreements established
to determine how many users and how much land would be available for
application. The report does not attempt to investigate alternative
sludge handling systems should there not be an adequate market and
states on page 7, that at worst Metro could dispose of the dried
sludge in a sanitary landfill. This would add significant costs to
the project and introduce additional environmental issues. Consid-
ering the capital costs of the project (S25.9 million, page 9) it
would be logical to investigate the impacts if no market developed
and the possibility of a different project design. As part of the
Continued next page
EPA Response
Given the present configuration of land uses, EPA feels that this
measure is presently unjustified. The airport preferred site is aj>-
PToxiaately 3km [2 miles] from site B-2; perhaps County planning could
determine how future industrial patterns develop in the airport vicin-
ity. EPA feels that residential development is not a particularly de-
sirable feature near an airport.
L18J While this is technically true that such loag-tersi implications
IJSve not been carefully researched, other siudge application exper-
iences lead EPA to believe that the long tern soil prospects are
favorable. Micronutrient additions to the soil are important; as
long as application rates are kept at a reasonable level, we have no
reason to believe there will be any untoward effects on the soil.
See discussion under Issue V-5.
y.9J These alternatives have been investigated in the draft EIS.
Tnere is still no movement in the Denver metropolitan area to develop
such solid waste schemes. EPA does encourage such combined uses, but
at present there are not sufficient funds to federally sponsor such
projects. Sludge may also not be compatible with some of these
scheoes, such ae supplemental power plant fuel.
(20j The cost of landfilling the dried sludge if adequate markets do
develop is estimated to be S3.5t [S3.25/t^n] for hauling costs,
'in addition to landfill charges. Even if tSis is npcessarv, the
sludge disposal will be cheaper overall than the current disposal
method. See Issue 11-15.
-------
Letter /MOr
continued
oo
Mr. John Green
Page 7
National Environmental Policy Act, it is necessary to investigate
reasonable alternatives which may reduce negative environmental
impacts (page 11). One alternative, has been investigated by the
Denver Regional Council of Governments, in the form of a solid waste
incineration plan, incorporating the sludge as one of the materials
but this has not been approved by the State as a possible program
at this time. Perhaps if 'Jetro finds that its current project will
not become reality and would assist in lobbying this approach, a
new perspective may be achieved. Although, unproven and perhaps
technically not feasible,another possible uninvestigated alternative
would be solar incineration of the material, which may not have
the air pollution problems associated with other incineration methods
Pyro1y sis was investigated in the study but analyzed as costly and
experimental. It is felt that pyrolysis in the long term may be
more economical and beneficial considering the many negative envir-
onmental impacts of the current proposal. It is reported in the
August 1976 issue of Planning Volume 42, Number 7, page 13, that the
use of the pyrolysis method is advocated by the Interstate Sanita-
tion Commission for application to New York City's sludge. Since
the pyrolysis process involves a combustion process that would burn
the sludge without oxygen or emissions into the air and convert it
into useful methane gas it would appear that more investigation into
this method is justified.
The current proposal envisions using the mesophillic process in the
anaerobic digestion process whereas the thermophillic range results
in a better stabilized sludge which is more easily dewatered and
reportedly has a greater pathogen reduction. EPA states that it in-
tends to evaluate this alternative (page 23) and this information
should be made availabe prior to any decisions.
Considering the controversial nature of site selection, EPA has sug-
gested that further investigation of alternative sites be attempted.
One possible location is the Lowry Bombing Hange as the drying dis-
tribution center (page 27). Since EPA finds no overwhelming superior
site location (page 28), it appears that more emphasis should be
placed on the benefits to be derived from alternative site location.
Considering the many unresolved problems of this project it perhaps
would be desirable for the second alternative of some modified type
of drying/windrowing operation at the Lowry site as suggested on
^ page 33 to be used.
11. Further investigation of the effects of the sludge to
dryland farms is suggested.
During the public hearings there were several individuals that strong
ly spoke of the dangers of crop damage with the application of the
sludge. The concern was that in the dry climate of this region the
crops would have inhibated growth,and actually burn due to the lack
of sufficient rainfall at proper intervals to compensate for the fer-
tilizer actions of the sludge. Additional investigation of dryland
farming characteristics is warranted.
Continued next page
EPA Response
y23J Alternative sludge processing techniques are discussed in Issue
IV-3. The conclusion at this stage is that the systems listed are
either too unproven or are inferior to the proposed system. Thermo-
philic digestion is an option that is still open to Metro; however,
it does not affect this project as the remaining sludge must still
be dewatered and disposed.
©
i
The use of the Lowry site is discussed in more detail in Issue
\23j EPA now believes that dryland farms will not be large consumers
01 dried sludge. In any case, if sludge is applied to dryland farms
in amounts based on supplying the crops' nitrogen requirements ad-
verse effects on crop development is not expected.
-------
Letter //401
continued
Mr. John Green
Page 8
It is the opinion of the Adams County Board of County Commissioners
that the EIS does not adequately address many significant environ-
mental concerns and the management plan of the proposed project is
ineffective. The current Metro proposal should not be approved by
the EPA.
Yours very truly,
00 , ¦ _ / .
1X3 JAMES M. COVEY
CHAIRMAN
-------
TYPED FROM HANDWRITTEN LETTER OS KALCEVIC FARMS, INC.
LETTERHEAD, page 1>
United States Environmental Protection Agency
Mr. John A. Green
Regional Administrator
pear Mr. Green:
My name is John G. Kalcevic, President of Kalcevic Farms. Inc.
of Bennett, Colo, and an concerned about having any proposed Metro
Denver Sludge treating plant being located in Adams County.
We own the S.E. 1/4 of Sec. 22 T2S-R65W Adams County which is
located on the East line of Proposed Site B-2, also own S.W. 1/6 of
Sec. 20 T2S-R65W located 1/2 mile West of Proposed Site B-2.
As outlined in the Environmental Impact Statement there is no
pervission to keep the dryed soluble salts from blowing on the farm
land located around either of the proposed sites.
During high Colorado wind periods the dryed soluble salts will
blow at least 5 to 10 miles from any of the proposed sites, and will
salt the soil to a point that will kill any growing grain crops within
5 miles of the proposed sites.
Therefore Metro Denver should be forced to purchase at a 5 mile
buffer zone around any site selected by Metro Denver.
You will note the following information given in the Ohio State
University Bulletin #598 on land application of sewage sludge.
Page 4. Biological Characteristics -
Various pathogenic microorganisms which may cause diseases such
as Cholera, typhoid, tetanus, and dysentery may be present in sewage
sludge as it is applied to the land. These organisms are associated
with fecal waste and some of them will survive conventional sewage treat-
ment processes. Additional treatments which would destroy almost all
pathogens are:
1. Storing in lagoons for long periods of time.
2. Pasteurizing at 70'C for 30 minutes.
3. Adding lime to raise the pH of the sludge to 12.4.
4. Chlorinating or other chemical treatment.
Continued next page
EPA Response
1j Because of the way in which the sludge dries, it is unlikely that
tnere will be any significant movement of soluble salts apart fro® the
dried solid material* If the sludge were to be pulverized, this could
occur; as long as the sludge remains intact, there should be little or
no blowing of salts from the sludge (see discussion on windblowing,
Issue 11-5). We cannot agree that on the basis of this issue, that
Metro should be required to purchase a 5 mile buffer around the site.
2J Air-drying is also an effective way to reduce pathogenic micro-
organisms concentrations in sludge. A few pathogens are long-lived,
particularly in spore or egg forms (such as Ascaris). Page 114 of
Volume I of this EIS identifies these organisms and their reported
survival times in various media such as soil or on plants. The com-
bination of sunlight radiation, heat, and dryness should reduce or
eliminate most pathogenic organisms. A more detailed discussion of
this issue is found under Issue V-l.
-------
Letter #41
continued
Page 2.
United States Environmental Protection Agency
CD
©
However, most cities do not employ these processes. Furthermore*
no process will kill 100 percent of such disease organisms.
Page 6.
Most sludges are high in soluble salts, and although this should
not be a major problem in high rainfall areas like Ohio, salt accumulation
could be a problem in depressional areas.
If you study the Ohio Bulletin 598 seriously you will conclude
that Eastern Colorado with 10 to 12 inches of rainfall per year is no place
to add sewer sludge to the land.
The most feasible and economical way for Metro Denver to dispose
of the Metro Sewer sludge is to haul or pump it to the present bombing
range.
But if Metro Denver is determined to spend the taxpayers money is
to build an underground sewage sludge disposal plant as they do in Sweden.
I have not met anyone who wants the Metro Denver to dump sewer
sludge in Adams County in any form whatsoever.
We do not want any sewer sludge on our farm in any form of sludge
or fertilizer*
We urge the United States Environmental Protection Agency to disapprove
any and all proposals of Metro Denver Sewage disposal District fil to dump any
sewage in any form in Adams County.
Sincerely yours,
Kalcevic Farms, Inc.
By John G. Kalcevic, President
EPA Response
QThe types of constituents in the soluble salts associated with
tro sludge are discussed under Issue V-l. A substantial percentage
of the salts are nutrients, similar to soluble salts in fertilizer.
Q Discussions about the present system of operation at Lowry Boab-
S Range are covered under Issue III-l; an analysis of the potential
use of Lowry Bombing Range for this proposed drying project is found
under Issue IV-1,
QA discussion of the "Swedish system" is found under Issue IV-3.
would not be applicable for large-scale wastewater treatment in
the Metro area.
-------
Attachment to
Letter #41
TK'SS- i. HORN
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-------
Attachment to
Letter #41
Contents
mi r«at
Characteristics ef Sludge 3
Terminotoer * 3
Physical Characteristics 3
Chemical ChwcmMio 4
Biological PvateOetistics: 4
"Nutaancg" Considerations 4
MKHpmnt 4
Sit* Selection 4
Handling andApplication 6
Crop Management 8
Pathogens 8
Ejtcess Trace Element* 8
Nutrient Requirement* 9
Sludge on Crops 9
Time of Application 10
Economic Consideration! 10
Testing 10
Social Concerns 11
Relationship Among Agencies 12
TASK FORCE
ON
LAND APPLICATION OF
SEWAGE SLUDGE
Appointed By,
feyM-Kottoaa.
Director, Ohio Agricultural neiaoiih and
Dwelopment Center
Director, Ohio Cooperative Eideneien ttrilca
Dean. Collegt of Agriculture and Horn* Ecwiwiu.
Tbt (Mo State University
Byron L Bondurant. Extension Agricultural Engineer
Samuel W. Bone. Extension Agronomist
Robert E. Brown. Ohio Environmental Protection Agency
Richard R. Davit, Assistant Director, OARDC
Riley S. Doufan, Assistant Director. Comrmxilty and
Natural Resouce Development, Ohio Cooperative
Extension Service
Lynn Forster. Assistant Professor. Department t*
Agnetr.lurtl Economies tut Rur*l
Fu Maghiri, Professor, Department of ^ronorny.
OAROC
George F. Had. Auodati Professor, Department of
Agronomy
ltrry Jl Logan. Assistant Professor, Department el
J^ronorny
Byron H. Nolle. Extension Agricultural Engineer
Melville U Palmer. Ertension >^nculturat Engineer
Albert R. Pugh. Extension Economist. Department 0<
Agncuttural Economics and Rural Soook®
Bertie L. Schmidt. Astociele Chairman, Department ef
Agronomy, OARDC
Glenn 0. Schwab. Professor, Department of Agricultural
Engineering
Paul Sutton. Professor, Department of Agronomy
Paul R. Thomas. Tes* Force Chairmen. Associate State
Leader. Community end Natwal Resource
Development Ohio Cooperative Extension Service
John F. Trurweiler, Associate Professor, Departmer* of
Agronomy
John P. VjmmerstedL Associate Professor, Department
of Forestry, QARDC
T. Craig WeidensauL Heed. Laboratory for Environ-
mental Studies, and Associate Professor, Plant
Pathology. OARDC
Richard K. White. Extension Agricultural Engineer
Publication Prepared By:
Rnbert E. Brown Albert R. Pujfh
Riley S. Dotiirmn Paul R. Thome*.Chairman
Lynn Forvler John F. Trimrrilrr
Fat H»srhin John P. Vimmer»t#dt
CeonW F. Halt T, Crmi/r Weidenaaul
Terry J. UfU Richard K. Whlw
Edited by: Geraid C. Groom*
Auislant Exiention Editor
Pubi (ration*
Ohio AirnotHural Rnranh and Development Center
W'oMlcr, Ohio
Ohio Cooperative Eileniion Service
The Ohio Stale University
Columbia*. Ohio
July l*tt
2
Continued next page
-------
OHIO GUIDE FOR
LAND APPLICATION OF SEWAGE SLUDGE
REPORT OF THE TASK FORCE ON LAND APPLICATION OF SEWAGE SLUDGE
An increasing number of landowners, local offi-
cial* and other cithtena have been asking question*
about the application of sludge to farm land.
Sludge ha* been applied to land for a number of
years in Mtmr communities. However. recent
action hv the I'.S. Environmental Protection
ApUf)'. increased costs of fertiliser, and a con*
cern for efficient energy utilisation haver'-nerated
further interest in the handling of sewage uludrt*.
(in one unit of the coin. muNiripiMir* art* fared
with the problem of how best to dispose of *ew-
ace sludges that are produced by the urlwn and
industrial segments of society. lh*|K>»al of sludge
by current incineration and landfill operation
methods now used by most communities has raised
serious environmental concerns.
though. are concerned al»out the
feasibility of applying sludge to their land. While
intfrcKtitl in the economic benefits sludge may
have, they art*. at the same time, concerned with
question* related to application rates, potential
httzunio «if heavy metals, possible odor problems,
and hchllli hazard* that micrht l*e associated with
ftludgv application
The follovinp guideline* art* baM^i «»n the most
recent n-wMfrli information available, and arv
mjlywl to change a» additional research i* com-
pleted. It must In* clearly under*t«M»d thai the in
formation due* mil indicate shut may or may not
l>e acceptable from a regulatory standpoint. An\
regulation* governing the application of sludge
will In* dev»-l«n»ed by the U.S. Knvironmentul Pro-
tection Agency yr Ohio Environmental l'r"UfU««n
Agency and local health departments.
The l>x«ir intent of this publication is to assist
landowner* in making decisions a« they consider
application of sludge to their land. Further, the
content should help local officials understand the
limitation* and capabilities of miiI u mean* of
sewage sludge disfKtsul. The publication aNo pto
vide* factual information lor the general puMu
ruii<-«-rnt»iir the nature of the fludge product
and it* dis|N»nal.
A f|oe»tion frequently uxkitl is. "How many tons
of sludge van 1 apply in my IuihP" It i«> ini|M».s*i
!»!«• in that question until two pniiiv laetor*
are kiinH ii; the composition of the sludge. and tlw
physical and chemical properties of the soil. So.
before a recommendation can be made, it's neces-
sary that the results of the sludge and soil analyse*
be available. Then, through the formulas detailed
later in thin publication, it will 1m* poimihlc to
recommend safe limits of application for given
sludge, soil, and croppinc situations.
CHARACTERISTICS OF SLUDGE
Sewage Kludge characteristics may be categor-
ized into physical, chemical, biological, and "nu-
inmif«*",The character!* i»c* depend on the type of
sewage and the sludge treatment processes.
Terminology is related to the type of treatment
process
Terminology
Two broad classes of sludge arv: ll untreated
irawi. and 2) treated. I'rimary fdudge is raw sludg*-
ohtained in the primary stare of tin* treatment
plant |»y collecting settleable and suspended
N»lids. Activated sludge is obtained in the second
ary stage of the treatment plant by settling Him
minted hactena celln that have l*een feeding on
th<* soluble and suspended organic material in the
»«*wage. Primary and activated sludges are further
treated |o obtain a Mabilizrd Kludge in which the
organic matter has been decomposed into a
relatively stable material Anaerobic digestion, a
common method of stabilizing sludge. proihic*'«
digested Kludge. Sludges may also l»c stabilized
by thermal conditioning
-------
tent. If a sludge has 6 percent solids, it is >5 per-
cent water. Three ranges of solids content that re-
late to different handling methods are shown in
Table 1.
Table L Sludge Solids Content and Handling
Charactanstet .
1-10*
Conmra. sugsc.
tmck tmmn
bm)
ronr »mm)
•nick tv»mp*rt
tbot)
TstrtsZ. lUnft of N, P, and K Contents of
Sswags tUtdfi
——
* _
»MSI
Total Nitrogen
3 5-6 4
70-126
OrfMic Ntaofw
2.04.S
40-f0
PtPhn&CHM)
O.S-3.9
it- n
PaO» (PhoaphMri
1.M.7
36-174
K (PwwsiiaK
0.2-0.7
4-14
tUOIftotsah)
0.244LB4
5-17
Titti S. Tract Etommt Concentrations in
Stvatt SMfi
There is an overlap of solid* content for the types
noted due to characteristics of particular sludges
and handlinjr equipment. Normally a sludge with
over 10 percent solids will not flow by gravity
through a aix ineh pipe.
Chemical Characteristics
Organic matter content, fertiliser nutrients, and
trace elements are the chemical components of
concern. Tables 2 and S present their rang* of
concentration in sewage sludge. There is great
variability due to the source* of aewage and type*
of treatment. There are also other trace elements
present which are not listed in Table 1
Biological Characteristics
Various pathogenic microorganism* which may
cause diReam such as cholera, typhoid, tetanus,
and dysentery may be present in sewage sludge
as it in applied to the land. These organism* are
aaaociated with fecal waste and some of them will
aurvivr conventional sewage treatment processes.
Additional treatments which would destroy al-
most all pathogens are:
1) Storing in lagoons for long periods of time.
2) Pasteurizing at 70T for SO minutes.
Si Adding time to raise the pK of the sludge to
J — — " " "—\
(T 4) Chlorinating or other chemical treatment. >
j However, most cities do not employ these proc- '
j eases. Furthermore, no process will kill lODprrrent '
| of dim^»sc organisms. . :
The level of pathogens in digested sludge is l»«.
but care should be taken in handling. It i* not
practical to disinfect sludge prior to land applica-
tion becauae of the organic matter present. Kr-
cent studtea have shown that when sludge i* ap-
plied to land, microbe* are retained at the **>») sur-
face and soon die. Therefore, the presenn* of some
pathogens in the sludge should not limit land ap-
_ to-hPrfQ. utrnm"
*-1000 so
CaOrwiuwi 1*1900 10
cmMuM ao-iacoo zoo
CabaS . 2460 10
Copper 52-11.700 900
IO-5J00 50
C&MQ0 900
Untxrr 0.1-96 5
21000 5
Lead IS-26.000 500
2*c 72-49.000 2000
••TiweeSJnTlwi «*> VttchKM wtttmmwi'iiw*.
W tM «t wyKl. «* MCtl
plication of digested sludge. But sludge ahould
not be applied to land during the year when
crops are to be grown for raw consumption.
"Nuisance** Considerations
Odors are the primary nuisance involved with
land application of digested sludge. It in recom-
mended that only digested or stabilised sludge be
applied to land.
Odor nuinance can be mimmiied by manage-
ment decisions. Spreading should lie at (east 2.V)
feet fr«m I lie ncirvnl residence. If large quantities
are »pre«d »n a short period of time, the distance
may need to be increased. If sludge storage la-
sr«»on* are located in the area of application, they
will need to tie at leant 1S00 feet from residence*.
Management
Site Selection
Thf pnmary reasons for applying sewage sludtrr
on airnrultural land are to u»e th<* nutrients t «.t.
tainfii in sludge for crop production and. at Hit-
same time, to minimize the environmental ol>j«-< -
tion> of sludge disposal. In order to do this,
attention muM I* given to the land»capi' and m>i1
characteristics of the application site. Suitability of
Continued next page
-------
00
V£>
sludge and rilei to use will depend on the heavy
met*) content of the sludge. In the absence of
high concentrations of heavy metals, nitrogen and
phosphate contents of kludge csn limit the
amount that shouid be applied.
The ideal site is one in which sludge material*
can be utilized by crops and which will allow no
movement of sludge components from soil as run-
off or tearhatc.
The primary site criteria to be considered are
landscape features, along with chemical and
physical properties of the soil:
Landscape Features:
Slope: Sludge should not be spread on slopes
greater than 12 percent. On 6*12 percent slopes,
spread onlv when at least RO percent of the soil
i* covereo with vegetation, when immediate
incorporation is pmtsible. or when erosion con-
trol m***ts recommendation* in Ohio Erosion
Control and Sediment Pollution Abatement
Guide. Cooperative Extension Service Bul-
letin 594.
Proximity lo Water: Sludge should not In*
spread within 3(H) frrl of pond*, lakev ur drum
age ditches.
Hood Hazard: Sludge should not »*• applied to
soils which art- suhj<-cl*-d lo pemwht' n T«»vic heavy metal* art- nn»r«
available to the piiint it! low pll'*. Soil pH'-
rnurh higher or lower than w»i) redurt
the ability of microorganism* in *oil to ih-
rom|>«»>e Mode-
ration K%rhance ( apacitt iCECi; Swi* with
higher iulli.li ewhaiige v»|tin it ie« haw
division of greater ;ti>iht\ to h>>ld ami
i in in id • 1117* heavv in.taU The e*n»«t »..t>
given lit the heav\ metal «>etli..|j ieh»?«-
»iudge loading rate* to , \
coafM
medtum
Ime
organic soft
ccc
MHHWkmK
5-1S
10-30
25-30
fraater |h«n SO
.ha
rups
..r i»hiM s.»»u
m nitlhe«|tit\ah-nt »> t*ri 1i»u t-i.
vmj| nnt*i| Iini g
Organic Matter (OM): Mineral soils with
greater division than 5 percent OM content
are better suited to application of sludge*
high in heavy metals because OM increase*
the CEC of the soil and also immobilizes
some hear J* metals.
Phosphorus Retention: Sludges contain
large amounts of phosphorus, all of which
will become available with time. High rate*
of sludgv application should not he made on
sandy or organic soil* because these soil*
have a low phosphate retention capacity and
large sludge applications could result »n
downward movement of phosphate into
groundwater.
Phtaicai:
Texture: Texture i» probably the most im-
portant physical characteristic of soils lie-
cause it affects many of the other soil physi-
cal properties, in general, the limitations on
sludge application by texture include:
Sandk. loam> nands: Leaching of .nitrates
and other soluble
sludge -components
is the major hazard:
sands also have low
phosphate retention
capacity, low CK<"
and low buffer
capacity (does n-'t
resist changes »'i
pHi.
l>oam». sand> loams: Then- soils have
limitations to sludg*-
application.
Silt loams: Major limitutions include soil
crusting and erodihiluy
(*la>«. sih> cla>s, rla> loams. *ill> fl»*
loam*.; Minor liimiuliotc- are jmmit druii<
ace. poor aeration, and slow per
niealuht \.
Structure: Soils with nui«<ii
*1 h»- u*e of sew aire -ludiM- on soiN with mm I.
Mti.Mirfavt' 11") i/oiitfor «-\;iinpW'. fra^ipaii"
'lu.IlM itt- ;i\ Miti.-.l
S«»il Kr«»dihiiitN : 1 »i«- su>> i-ptilMhty of a «*.ol \>
• i|i'|M'ii>|- «»i; main fat-tors, tin* in»»*:.
imjH.r!anl «»t wlmh aie ^ul t«vtutv.
aini \ rL'etat i \ i' i-«»vci. Th«* t'l fat»••*! lia/.n .J i-
<>ii fine t •*vl t*» ••• i -.otl-s. Siu«i^r<' apph« ;tl»*ii
(trreater tiian J |H*rr«ntJ. fuie tex
Continued next page
-------
tured ioQi should be unless Tereta-
il re cover ia mtinliined on Uwm hUi to in-
crease infiltration.
Unincorporated iludye on bare slopes rei>
ter than 6 percent will move during runoff.
Erosion rontrol should meet the recommen-
dations in the Ohio Erosion Control and Sed-
iment Pollution Abatement Guide, Coopera-
tive Extension Service Bulletin SM.
Soil PenaeabiBty: The rate at which water
moves through aoi) is important in sludge
application. Soils with either very High or
very low permeability should be avoided.
Highly permeable soils are auseeptible to
leaching, aod sludge may contaminate the
groundwater. Those with low permeability
have internai drainage problems which re-
strict sludge decomposition.
Draiaage: Successful decomposition of
aludge in soil requires good aeration and
therefore soils with poor internal drainage
should be avoided for sludge application.
FinMHtured and poorly-drained soils, and
soils in depressions should be property
drained before they are used for sludge
Most sludges are high in aoluble salt*. and(
although this should not be s major problem
in high rainfall areas like Ohio, salt accumu-
lation could be a problem in depressions!
areas. ' _
Summary ef Site Raftrictiaet far Studft Appfecatiofi
by So* Tartars! Ctati
to
o
taM
Oess
tsmvri
Omi
*>y«ka1
Owaiiil
Cosne
&Mt*s
UMrundi
Sandy taB*»
W**««otMn.
OMplSSCJM*
Law P fttcnton.
low pM buffer
capacity, low
C£C
Mtdiwm
Umm
SS loamt
D»«— submit-
lacttanim
mckidmt
t'f^swv
cma«t
Fib*
Cteys
Ctsylesms
Sidy clay teams
Poo* daup,
poor
¦lowpsvni*-
sO*ty. rsptf
nMdasim
MgSfOSV
eredtOdfty
Sad attwwuU
ban
Handling and Application
The principal factor in determining proper ap-
plication techniques is the physical characteristics
of the sludge. Will it be handled as a liquid, semi-
solid, or aoCd? It is assumed that the sludge to be
applied to land is digested or stabilized. In the di-
gestion process, the tots! solids content normally
ranges from 3 to & percent, i*.t 9? to 95 percent
water. The solids content can be increased by
various processes at the treatment plant, such as
thickening, dewatering, or drying. The decision as
to equipment for transporting the sludge, apply-
ing K to the land, and/or incorporating it into the
aoi) will dictate the aolidscontent that csn be used,
or rice versa.
Other factors affecting the method of transport
and application are: quantity of sludge produced
(sit* of the city), land considerations (topography,
vegetative cover, soil type, acreage available), and
time of application (westher. soil trafftcability,
cropping!.
Environmental concerns affecting the method of
applying sludge to cropland are: control of surface
and groundwater contamination, odor, and aerosol
(mist) control. Methods of storage, handling, tim-
ing, and rate of application and type of land used,
can be managed to minimise these environmental
problems.
This section considers application of sludge in
the "liquid** form using1 spray irrigation, overland
flow irrigation, tank truckrwagons and immediate
soil incorporation. Also, handling sludge cake in
the "solid" form using truck spreaders will be dis-
rupted. Irrigation equipment will bfuxrd primarily
by a large city. since the capital costs for equip-
ment capable of pumping, transporting and ap-
plying sludge is too great for small citiea. Small
municipalities will most likely use tsnk trucks
which allow flexibility in selecting application sites
and lime of Mpphemlion. Immediate soil incorpora-
tion can be used with irrigation equipment or tank
trucks. Capital costs for dewatering equipment
are high so that only larger cities likely will be
concerned with applying sludge cake in the
"solid" form, with the one exception of cities
that uae sand filter'drying beds.
Sprinkler Irrigation: Where sprinkler irrigatM»n
is selected, a solid-set system a*> rrnimmrnrird
tivrr a purtsblr pip* ay-stem fur operating and
manairemvnt reasons, £e(f*propriJ«*
-------
hfwtw 1. tftwtaf vnpbM sjrttMt In ijMnMB.
Tsak Truck: Commercial tank trucks and tank
wagons are available. Thome with hiirh flotation
tires for traversing aoft ground may have a re-
stricted hauling range. Regular trucks can he used
on grass covered or dry fields. Attachments for
tank trucks to allow for field spreading are very
simple, involving a quick opening closing valve
and a deflector plate to fan the slurry aver a wider
area. In most rases, gravity discharge is used,
but sunn* commercial tanks can be pressurized or
pumped. Kiirun* 'J show* a tank trurk with gravity
discharge. The tank trurk own l»e elevated to give
more uniform disrhurgv ami remove solids. Fig-
ure M showy h truck vt it ii n pumped discharge
which can lie directed to tin- side Tins trurk ran
ftwar|« et iMfi with UMbtWy *f
fifura 3 Co«nm«rct*4 tank trvck witti ptf*np«e) 0 |»errenl of the water is removed.
Tin- conventional !h>x spreader ha* iK*en used f««r
many years tu field-spread animal manure. Adap
tation of the manure spreader to a truck mounted
spreader, as shown in Figure h. ran In- used for
spreading semi-solid or solid sludges. Truck at
tuehmerits have l»een developed for direct in-
corporation of M-mi ^ulid or nolid sludge into M«il
using a moldboard or disc plow.
* nure S Truck bo J ftprcsder Photo courteiy at I I MoMrfoctumtc
to.. Ckodg* City. Kjnui
Continued next page
-------
Crop Management
Sludge contain* plant nutrients (See Charac-
teristics of Sludge), and when used by the grower
with proper management, it is a valuable supple*
ment to chemical fertiliser. Sludge also can con-
tain varying amounts of metals which can be toxic
in the food ehain when concentrations are high.
Therefore, the Quantity of aludge which can be
applied safely on-aoii must take into account the
amount of heavy metals applied as well as the
nutrient requirements of the crop. When the heavy
metal content is high, the sludge application rate
will be determined by the amounts of these metals
that can be tolerated aafely. With "clean** sludge*
(those low in heavy metals), the application rate
will be determined by the nitrogen requirement of
the crop, since excess applications of nitrogen can
result in contamination of ground and surface
waters. Other criteria which should be considered
with respect to land application of sludge are
pathogens, site characteristics, monitoring, and
economic considerations. The last three are
Pathogens: Some pathogens will reach the soin
and vegetation during recycling of sludges. How-
ever, due to a relatively rapid mortality of patho-
gens in the soil, the presence of these organisms
should not be a large factor in limiting the appli-
cability of land application of sludge wastesi Root
7rop£ or ervps ¥aten rsw~should not "be grown in
the year of sludge application. '
Excess Trsce Elements lacleding "Heiry
Metals": Although sewage sludge contains all
nutrient elements essentisl for the growth of
higher plants, it also contains, depending on the
source. other elements which might be harmful to
crops and to the food chain if applied to soils in
excessive amounts. These elements are: Zinc (Zn),
Copper (Cu). Nickel (Ni). Cadmium (Cd). Chrom-
ium (Cr), Mercury (Hg), Lead (Pb), Boron k* in retain-
inir heavy metals through its high cation rxchangr
capacity and chelating ability. I'hosphat*** reduc«-
the stunting injury to plants from high levels of
cop}ht. zinc, and nickel. Plant species and varieties
vary in their abiliiim to accumulate heavy metals.
B*»ed on current knowledge of relative crop toler-
ance* to heavy metals, some vegetable crop*,
e.g.. U'fU, kale-, mustard, turnips, and tomatoes,
are reported to Ur very sensitive wlule other*
fcurh at beans, cabbage. and rollurdx are con-
sidered to be sensitive. Field crop* such as corn,
soyia-ans, and snmli grains arc- moderately toler-
ant and most grasses (e.g.. fescue, lovegrass,
bermudafrrBK.s. and fwrt-nnml ryecra**) are classi-
fied sn tolerant. The concentrations of heavy
metaU in the vegetative tissues of plants are
much higher than in fruits and seeds.
Continued next page
-------
u>
According to the U.S. Environmental Protection
Agency's proposed guideline* (Acceptable Meth-
ods for the Utilization or Disposal of Sludges),
application of digested sludge with sine equiva-
lents up to 10 percent of cation exchange capacity
is permisaable on agricultural land with the pH of
or rreftcr.
Baaed on the alwve- proposal, wo grratrr total
amount of dilated mlmdpr May ever br applied
than that calculated fry aquation I for the tludfft
and toil «n fMiljM,
Equation t:
Xuiml Amount of sludge (dry tons/acre) -
CEC a >£,700
- ppm In * ftppm Cu) ~ 4(ppm ND-500
CCC - cation exchange capacity of soil before
sludge application (meq/100 g)
ppm - parts per million or mg metal'kg dry weight
of »ludge
Equation denominator • Zn equivalents indicate
ing that Cu is two timet
and Nl four tlati as
toxic at Zn to plants.
J* mddition, the VS. Bnvironwttntml rrwfwftoit
Affmry rrmmmrndM thai ahtdpe mot ke applied Is
rmpltind if the cadmimm romtrni tfs higher tkmm f
percent «»f the »inr romtemL
Equation 1 should he used u a guideline far
slightly acid to neutral soils where toil pi! can to
maintained at 6.5 or higher at all times. However,
in those region* where »oil pH is not maintained at
f*.;* or mun*. total digested niudge that may ever be
applifd is calculated by Equation 2 which would
permit sludge application with a zinc equivalent of
a percent of the ration exchange capacity.
Equation 2:
Total amount of nludgv (dry tons acre) -
CKV x K5..V.0
|t|»in Zn • Jtppnt Cu) • 4(ppm Ni)—2•»•!»•«• uIm< be considered ill ili li'intin
im* t»»»* to apply ut any one time.
Sludfe on Crops: Sewage Muiiirf, Iwsum* of
its nature, should not In- applied to certain rrops
Hiiih as root crops and ieafy vegetables. Sludire
-houlil not Itf iip|tlti-il to pu*ture crops unless ant
mul* are reti)ove«J fiotu the pastur«a until the slutli;*-
ha*» lut'ii u uhIiimI t*ff I he leaves. It xltnuM l*e note, in« linhng vegetables. toraAT<*s.
a»«) silaire. than Mith era in an
-------
Sludge can be applied on forest crops, but the
same restrictions apply to forest as to food crops in
order to pre nerve the wildlife And water resources
associsted with woodlands. Nitrogen leaching to
groundwater in undisturbed forest soil is a major
hazard with aludge application. Undisturbed forest
soils contain larjre pores that transport water
rapidly. These pores, earthworm and insect tun*
nels, small mammal burrows, and old root chan-
nels may extend downward for several feet, and
laterally for lens of feet. In aandy soils, root chan-
nel! fill up with sand; but in finer textured soils,
the channels persist like drain tile. Clay skins and
root bark prevent water movement from the pores
into adjacent soiL
Infiltration from sewage sludge applications
will move rapidly throujrh these large pores with*
out wetting the soil mass, so there is a potential
for both groundwater contamination by rapid
verticil movement and for stream pollution by
rapid lateral flow down slopes. Lateral flow could
be interrupted by thoroughly disturbing a strip of
soil between the sludge application area and the
watercourse. Protecting the groundwater will be
more difficult. Forested areas where groundwater
i* an important resource should not be used for
sludge application. Problems associated with rapid
vertical and lateral water movement in channels
will be less serious on coarse textured soils such as
sandy loams and silt loams, and more serious on
silty clay loams, clay loams, and day soils.
Dried sludge can be used on lawns snd or*
namental species as long at direct humsn con-
tact with the material is avoided. Heavy metal
and nitrogen limitation* also apply to these crop*,
and it should be noted thst some ornamental crops
are probably sensitive to heavy metals.
Time of Applicatioa: It is best to apply sludge
when it can most efficiently be utilised by the crop
and, if possible, sludge should be incorporated into
the soil to redure odors and runoff problems
Sludge should not be applied on snow-covered,
froaen, sloping land unless there i> adequate plant
cover or residue to retard runoff. It should not be
applied to poorly-drained soil when the water
table is near the surface. In general, it ts best to
apply and incorporate sludre several weeks be-
fore planting. Sludge can be applied to established
forage stands at most times of the year as long as
adequate time is given for the sludge to wash into
the soil before the forage is rut or animal* art al-
lowed to grate. Trees arc perennial crops and mu«t
survive cold winters in many areas of the country.
Application of sewage sludge in late summer or
early fall could prevent development of cold hardi-
ness by stimulating a new Hush of rapid twig
growth. Therefore* sludge should not be applied to
forest land in late summer or early fall, but in
spnng and early summer, up to around July IS.
Economic Considerations
Substituting Sludge for Commercial Fertiliser:
Valuing sludge as a substitute for commercial
fertilizer is complicated by its variable chemical
composition and by fluctuating fertiliser prices.
Table 4 presents three price levels for fertiliser
to be used in arriving at the nutrient value of
sludge.
Table 4: Aaiumad hicn for Fertikzer Nutrients
Fvtea bfi OMMvt/PsMS)
MM
M0
Ut
ft fWiliSgiW)
40
JO
JO
PriOi {^osptoaM
JA
jo
.15
feOCFWM
.14
.a
JO*
Table b demonstrates the range In the fertiliser
replacement value of sludge which Ohio munici-
palities might provide using the price levels shown
in Table i.
Tabis S. Vslu« of Nutrients in One Ton of Dry
Sewage Stutifs Undertime Alterna-
tive Assumptions tor Nutrient Con-
tent and Commercial Fertilizer
friw*
*¦*»«¦ i iMSIMp
lMris« tammt N«li" Ns*m" law*
Lorn m - I Sa. -l#*. *14.91 SU M S1O.40
lU>-0 24*)
MaOHsnfft-4 40S3 31.9S 23 14
5.2V*. K*0»0S4^)
H«MN-&4V 62 75 49 30 35.S6
Kj0« 0.M1)
—(WWWIHIWl ¦ ¦ I II
Table 5 demonstrates that the value of sludtrv
varies tremendously a* a fertiliser replacement.
The value may vary from $10.40 per ton to ap-
proximately S63.4H) |K*r tun. Thus, landowner*
w ill need tucarefully determine the current uludge
content and nutrient value in making a decision
relative to having »ludge applied to their land.
Testing
Routine tests should be made on aludge before
the material i* used. Several of these determina-
tion* are the same as those used in routine soil
analyse*. Organic matter, pH. and soluble salts
content telectrical conductivity) test* of the sludgt-
ahould be made. Sludge* from different munici-
palities vary considerably in their moisturr con-
tent and, therefore, total solid* tdry matter) de-
terminations must be made before any recom-
Continued next page
-------
vo
cn
neodationi can be pven regtrdini the amount
of material to apply.
The nutrient element content of sludge must be
measured to help determine if additional fertiliser
should be added to balance the amount of nutri-
ents supplied. Types and quantities of metals in
sludge vary considerably from one municipality
to another, and even at a given facility depending
on when the Kludge is-sampled. Metals would be
expected in greatest amounts in sludge from muni-
cipalities which service certain kinds of industries.
Conversely, these metals will probably be less
sijrniftcant in sludge from primarily residential
areaa. However, determinations of the metal con-
tent ahould be made regardless of source. All test
results should be msde available to the grower well
in advance of land application to allow enough
time to determine application rates.
Standard aoil tests should be made prior to
sludge application m grower* can determine the
total amount* of nutrient* thst will be available
from both sludge and soil. Samples for this test
should represent no more than 20 acres. These
tests consist of pll, cation exchange capacity, lime
test index* available phosphorus, exchangeable
potassium, calcium and magnesium. Additional
tests should be made for available tine, boron,
and possibly molybdenum. Waterways adjacent
to the anticipated application area and nearby
spring* and wells should be tested to determine
background levels of nitrate-nitrogren and eoli-
form bacteria.
Monitoring Schedule After Application
The soil torn* mentioned above should he made
each year prior to fertilizer application*. Some
constituent* of sludge will remain in the soil
for many venr* while others will disappear rather
rapidly. If any nutrient imbalance in the crop is
suspected, plant anslyKes should be used to help
diagnose potential nutritional problems, either
toxicities or deficiencies. Heavy metal analyses of
consumable plant parts from sludge-amended
soils in desirable. especially when amounts applied
approach or exceed recommendation* given in
this publication. Water source* originating near
the sludge application area and eventually dis-
chargtng into larger streams should Ik* peri«»di<
rally sampled and tested for the presence of trace
ele»rirwt' ••*"* "itmlrt —
It in important to point out that in addition to
heavy metaU. aewaire sludge may contain some
persistent compounds which tnay lie harmful !<>
crops.. Since these comj>oumls ruMiiot l»e ident ified
easily, simple seed gernntiutioii test* in Imth un-
contaminuted soil and soil mixed with sewage
sludge are desirable.
Procedure for Collecting. Handling, and
Submitting Sludge for Analysis
When submitting ft sample for tmiyaii,thf name
of the municipal sewage treatment plant should be
provided so that sludge from different localities
can be characterized, to help develop sound
recommendations for the grower who uses slodm
as a fertilizer. Tests of sludge samples ran be
conducted by several laboratories located around
the country. County Extension office* are being
provided the addresses of known facilities.
Furthermore, some of the larger municipalities
either have or are obtaining the capability L«
analyse sludge.
Sludge should be collected in water-tight, air-
tight plastic containers of approximately one pint
site, depending on the estimated water content.
The table below indicates the sample size to
be collected relative to the estimated water cob-
tent.
Water Cssl.1 SsMl VsfcMW » CMSCt sr WeifM Is »— irl
m
2*
lgaMon
• R*.
95
5
1 l?ousrt»
3.2 tot.
90
10
1 12pnts
1.6 to
80
20
1 pmt
OJtos.
70
30
1/2 pmt
0 51*.
Social Concerns
The concept of land application of sludge for
crop production has been used for centuries in the
Asiatic and European countries. They consider
sludge as a valuable natural resource which can
replace fertilizers and increase crop yields.
A key consideration in determining the practic*
ability of land application of sludire is whether
landowners, farmers and other persons in the com-
munity do in fact see an advantage to receiving
this material and view the material as not being
a problem from the standpoint of either eco-
nomic. health or nuisance considerations. fast
experiences have clearly demonstrated the nrt*d
for land
-------
The following considerations with regard to an
educational program are recommended:
Educational material* must be developed which:
—clearly and concisely state current status of
aludge disposal in the community involved and
indicate the likely future possible sequence of
event*.
—depict what information is of a specific nature
and which can be generalised
—clearly outline the practical alternatives in-
volving land application of sludge
—supply a means to permit local landowner* and
citiaena to evaluate these alternatives before
final recommendations are made
This will require a simplified analysis of the pros
and eons of each alternative. This information
should include not only the technical aspects but
the social, economic and political aspects as well.
Those involved in an educational program should
not try to **aelP any one proposed alternative.
(Every effort must be made to provide local citi-
zens opportunities to make choices). Any educa-
tional effort should let jt be known early that its
main function is to disseminate information and
provide an objective forum for discussion of the
various alternatives in dealing with the whole
question of sludge disposal,
An opportunity should be provided for interested
persons to visit sites where sludge has been
applied to the land. In addition, where possible, it
would be desirable to establish demonstrations
at several farms located in the area under con-
sideration.
An educational or information program should
accompany the establishment of such demonst-
rations. A program should be one where:
*
—the problem is clearly identified
-^factual information regarding alternative sol-
utions is presented
—a forum ia provided for input by all intereated
—it is recognised that in the final anaiyais the
decision of which alternative ia implemented is
made by the people
Effort must be made to make certain that all
possible factual information relating to the de-
monstration is presented.
Relationship Among Agencies
The authority of the Ohio Environmental Pro-
tection Agency to regulate land application of aew-
age aludge is derived from both state and federal
laws. Sections 6111.44 and 6111.4$ of the Ohio
Revised Code require that plans for all sewage
and industrial waste treatment systems be sub-
mitted to OEPA for approval and that auch ap-
proval be based on whether or not the proposed
system will pollute the state** waters or present a
hazard to the public'* health. The National Envi-
ronmental Policy Act (NEPA) of the U.S. Con-
gress also requires that an environmental assess-
ment be prepared for any proposal which would
receive federal funds. In practice, thia means that
plans and, if appropriate, an environmental as-
sessment should be submitted to the OEPA. The
OEPA engineers and planner* would then verify
that the proposal is based on sound engineering
judgment and that it would not cause significant
water pollution or present a threat to the public's
health. If federal funds are involved, OEPA would
also verify the cost effectiveness of the proposal
and consider the overall environmental impact of
the proposal.
It is important for landowners to understand
that an approved plan for sludge application
does not remove their responsibility for water pol-
lution or health hazards that result from the ap-
plication of this sludge on their land. Plan approval
means that in the judgment of OEPA the proposed
system should function satisfactorily. However, it
is possible thst unforeseen problems might arise.
In such situations the OEPA would give the Land-
owner s reasonsble penod of time to rectify the
problem. Of course, the landowner should also re*
serve the option to discontinue sludge application
on farmland in the event of such unforeseen prob-
lems.
The local health department would become in-
volved only if a nuisance or health hazard aitus^
lion were to exist. It is recommended that land*
owners contact the local health department for
guidance and aupport prior to applying aludge to
their land.
III! is
«n Ivftfwsnce of CaapwXw trtmnow ma, set* pi M6 »nd June 30. 19)4. m cooperate** W* U S Oro»rtm»rt St
AfncuHt** Roy M Hon man. Owvcto* o) ft* Ceopwstw* Litanwi Snwci. The Otoo $!*(•
-------
Letter #42
Route 1 Box 198
Keenesburg, CO 80643
September 3, 1976
Gentlenen:
1 regret that I could not present this in person, but I would like
to sake my opinion known, and share what knowledge I have of sludge
with you.
As a junior majoring in agronoay at Colorado State University, I had
an opportunity to work with several graduate students and professors
on the subject of sludge composition and effects on the land when it
was spread.
EPA Resoonse Inhibition of germination is generally related to the unavailabil-
r of nitrogen, which may be consumed during active biological de-
composition processes in manure, sludge, or any rotting organic matter.
The Metro product will have been anaerobically digested and dried for
almost a year's time. There should be relatively little germination
inhibition with sludge applied under these conditions (Reference 45).
Metro will have the opportunity to evaluate the timing of sludge ap-
plication in their research and demonstration areas, if this project
is built. We do feel that if a rational approach that includes a con-
sideration of timing of application and crop growth is followed, the
beneficial aspects of sludge can be achieved.
As the writer states, this probla can occur with certain crops
under certain conditions. However, with proper aanagssent procedures,
this problen should not occur with any of the proposed uses of Denver
sludge. In general, if the management procedures currently followed
for animal aanures are followed with sludge application, no stunting
or other adverse effects to crops will occur. (Reference A).
Scmm of the problems inherent with sludge are:
©[
©[
©
®f
1.
Sludge, as is true with manure, sometimes causes crops to
fail because of germination inhibition.
2. Sludge sometimes causes severe stunting or necrosis in cer-
tain crops at a particular stage of growth,
3. Under certain conditions which prevail in the area where the
sludge dispersal is planned, Nitrate-Nitrogen leaching is
severe. Applying sludge on winter wheat lands in the fall
would many times be a complete waste of time, as all the
Nitrogen would have been released in the Nitrate form, which
readily leaches.
4. Sludge is high in toxic heavy metals. Although the analysis
usually shows only a few parts per million (ppm), it should
be noted that small quantities can be toxic. For example,
for most crops zinc is toxic for plant growth at levels of
1 ppm and iron at 4 ppm, and sludge has much greater concen-
trations than this. Other metals frequently found in sludge
are copper, cadium, lead, manganese, and nickel, among others.
Some root crops cannot be grown because of the metals.
5. Sludge has the inescapable problem of the pathogens which
cannot economically be eliminated and which pose a threat to
the public safety.
6. Another problem relating to sludge and soil fertility is the
problem of residual phosphorus in the upper six inches of soil.
Continued next page
QTtae beneficial aspect of applying sludge as fertilizer is that
th of the nitrogen is in the organic form that is only slowly re-
leased. Therefore a winter wheat application of sludge in the fall
could be a valuable exercise. Certain areas that have s nitrate
leaching problem, often from overappllcatlon of commercial fertilisers,
would indeed be a bad choice for sludge application. On the other
hand, fertilizer applications should also be restricted to correct
the problem.
UJ Heavy metal chemistry in the soil is an extremely complex issue.
iQBi heavy aetals et aicronutrient concentrations (Cu, Mn) ere toxic
at higher concentrations. The presence of metals in the soil is no
guarantee of their availability. Likewise, applications of certain
concentrations of heavy aetals is not always reflected in plant up-
take. Each plant species also has differing sensitivities to various
metals, as wel3 as differing uptake rates. For these reasons, experts
and researchers in the field of 6ludge application studies are not
able to agree on firm values for heavy metal limits. There is much
research to demonstrate the general effectiveness of sludge as bene-
ficial to most growing crops, however. A recent suamary appraising
the potential hazards of heavy aetals to plant and animals was pub-
lished by the Council for Agricultural Science and Technology entitled;
Application of Sewage Sludge to Cropland, Report No. 64, November 15,
1976. Their susnaries on the effects of application of zinc and iron
are as follows:
Fe:
"The levels of iron... in sludge usually will not be of any en-
vironmental concern. Even though many tertiary sludges may be high
in iron., (it) will not be a limiting factor in determining the quan-
tity of sludge that may be applied to agronomic crops if the soil pB
is maintained above pH 5.5 and the soil., is well aerated." (p.25)
Zn:
"In general, if the pH value of sludge-treated soils is main-
tained at the recommended level, zinc should not be serious hazard
to plants or to the food supply unless exceptionally high levels are
added in the sludge. In many instances, a moderate increase in the
zinc content of the food supply should be beneficial because there
is evidence that diets are often deficient In zinc." (p. 36)
The apparent key to minimizing the negative effects of heavy
aetals is by control of pH at ox above 7. Host Western soils are
alkaline and meet this criterion. The sensitive crops are generally
the ones least likely to have sludge applied, such as edible root
crops or vegetables. The crops constituting the bulk of Coloredo
production— corn, wheat, grasses, and perhaps even sugar beets-
could make safe use of the sludge.
-------
Letter #42,
continued
September
Page 2
3, 1976
©
©
ID
CO
The labile phosphorus and available phosphorus do not leach
but accumulate in the soil if not used and can become toxic
under certain conditions.
7. An evident problem associated with sludge is ODOR. Hie ap-
plication of sludge on land will result in considerable of*
fense to the residents and landowners of land in an area much
greater than the site of application.
At present, the Denver Metropolitan area produces oil the average about
100 tons of sludge a day, or 36,500 tons a year. The average analysis
shows sludge is 5 percent nitrogen. If this nitrogen was applied at
200 pounds nitrogen per acre (which is even a high rate for irrigated
crops—dryland use would be 30*50 pounds per acre), it would fertilise
18,250 acres per year, or 28.5 sections. Sludge application on a year
after year basis would ruin the soil for crop production. Therefore, I
think there would be a great problem with oversupply and almost no demand
, for th* sludge.
On the basis of these reasons, I strongly urge the Environmental PrOtec-
Agency to deny the Denver Sewage District the permission to build
this planned facility. Sludge as a fertilizer has many problems and
could ruin production of the land. With an ever-increasing population,
we cannot afford to take a chance to hurt productivity.
Respectfully yours,
}-
J
John J. Sauter
JJSfkls
EPA Response
Again, the threat to public safety is a relative one. EPA feels
t sludge applications on home gardens, particularly edible root
crops and leafy vegetables, are the least desirable form of sludge
application. Applications on individual irrigation or sod farms
allwrs a greater degree of monitoring of possible pathogen effects,
and minimizes the risk of transmission of any pathogens.
[6J This statement is true. However, the high calcium content and
nigh pH of the area soils will render excess phosphorus insoluble, and
largely mitigate this problem. Over a long period of 6ludge applica-
tion phosphorus could build up to harmful levels. However, It is
likely that buildup of other materials, such as metal6 or salts, will
limit sludge application long before phosphorus reaches unacceptable
levels.
There will be some odors from the drying/distribution site, al-
it is not expected to be generally noticeable any distance
from the site. Odor problems are not expected on individual applica-
tion sites (see letter from William Sharp, Letter # k ). Also see
discussion on odors, Issue II-3.
Because of the drying procedure, the total nitrogen content of
dried sludge will be between 2 and 51. We agree that If all the
sludge was dryland spread, your estimate of the number of acres need-
ad is valid. However, where more intensive applications of fertilizer
are called for (e.g. irrigated or sod farms), the nitrogen require-
ments might be increased by one to three orders of magnitude. The EIS
concludes on page 104 (Volume I) that if all sludge were applied to
irrigated farms, about 2800 ha [7000 acres] of land would be needed.
There could be an oversupply of sludge in certain times; under these
circumstances, the dried sludge could be stored or buried in the
Lovry Landfill at relatively low cost.
&
-------
Letter #43
T.'v name is /incen:. Cauter. I'-i ¦x :D_ir-ia" '_?i .-n-ijor at
t:id University of Colorado, and I've been a resident of
rural Adams Oounty for 23 years. My father farms approximately
seven miles northeast of the proposed dunpina: site. Tnerein
lies my initial interest.
But on the other hand I see an issue that has, and I think
will remain an emotional one. The opportunity to speak ones
mind at a public hearin« such as this is the only way problems,
in a democratic fashion, can be solved. I welcome this
ODrortunity to sceak, because I see the need of the opposition
to the nro^osal, in this case a ninority, to have their
riirht to an airin? of some very concerned opinions. In so
many Issues, such as this one, where arrroval or disapproval
of something rests on the shoulders of a few, I think it
10 imperative that we elve those peocle who will ultimately JB
ID
make the rulinp, sonethinc they can base that rulirur on.
I'm very concerned that the people who a*e opposed to
Metros dumpine of sludge in rural Adams County won't speak up
the way they should. I'm concerned because I sense a feeling
of frustration in these people, a feelinc of frustration
Mowine out of the fact that they fe- 1 over-power^ and over-
shadowed by a very lar?e government entit>|*hich can drastically
influence their lives.
But these people shouldn't feel afraid to sneak their
minds and hearts. They have a very lane stake to lose, and
they should fieht for what they believe is ri*ht.
For many of the people livina near or adjacent to the
proposed ducpin* site, this plan by Metro is an affront to their
Continued next page
-------
dignity and livelihood. Many of them have lived and farmed
in that area for kO or more years-a time in wnioh thsy have
grown to love the purity of the region. No matter how desolate
and barren the area may seem to city dweilars, it still serve3
as home for quite a few who cherish the fresh air and clean
water. And it is a very productive agricultural area.
Anyone can attest to that who has seen the large amount of
wheat harvested there.
Some proponents of the plan will say, "ereat, the
application of sludge will improve that productivity",
wherein the farmers who have lived and worked in the region
will counter that it's a semi-arid region where the annual
precipitation isn't great enough to off-set the burning of
the crors.
The proponents will say the sludee can be used with
irrigated crops, but they had better warn the applicators
about usage on vegetables since it hasn't been proven whethei
or not slud«re can be detrimental to the food chain.
I think that something this important can't be answered
vaguely. It needs a yes-no answer; something black and white,
not gray.
I don't think the peocle in the affected area are that
concerned with the pros and cons of sludge usage on farm land.
Their main fears are ones concernine water and air quality.
This region wouldn't have been settled if there wasn't
sufficient, pood drinking water.
Continued next page
EPA Response
ly EPA is willing to go along with Metro's choice of site for this
project because it believes that the project with suitable modific*-
tioos will be compatible with the present farming operations. Its
presence should not be radically different from any agricultural-
supportive business such as agricultural equipment or fertilizer-
sales ativities.
Current Metro plans call for sludge use on irrigated farms or by
municipal parks. It is true that the immediate area around the site
vill derive little or no benefit from the operation. There are
enough irrigable lands in the general northeast area growing competib
crops that can receive sludge amendments.
-------
The water is relatively pure-tasting compareu to drinKine
water in Denver.
The Impact Statement talis about pti-maabiiity rates
and says it would take several years before the water table
could be affected. There's the problem. It's not a questi.n
of if, but when. I have been told that the proposed site
lies above a closed basin known as the Lost Creek Basin.
That means that the acuifer will, once polluted, be unable
to cleanse itself, so to sr.eak. That -neans that the water
Quality will continually deterioate, and eventually could be
used only to help pump sludge through pipelines. I'd like
to point out that the Lost Creek Basin doesn't just lie
under a handful of farmers to the north of the site, but it
encompasses some 30 miles of area to the north, and the water
from the Basin is used by some irrieated farmers.
Air duality is important, everyone realizes that,
esrecially the Environmental Protection Agency. The proponents
claim that the sludpe in the drying basins will be relatively
stable in hirh winds, and if need be, it could be sprayed down.
That is noinfr to increase drastically the time necessary for
the slud?e to dry. Coup led with the Infrequent dov.n-cours in
the area, th"- six months that Metro says it will take the
sl'-ids-e to dry seems a little unrealistic.
The aue3t4on of aesthetic* arises. Wanv say that's no proDiem
since farmers are use to barn-yard smells, and anyway
the sludu-e won't smell that bad.
Continued next page
EPA Response
3J EPA will not proceed with this project if it does not believe It
Tin adequately protect water quality. From what EPA has seen of
geological, soils and groundwater evidence, we believe that positive
protection measures can be taken to Inaure that groundwaters will be
protected. See discussions under Issue II-2.
Drying times have not been firmly established. There appears to
be adequate capacity in the basins to handle the prcjected 1985 flows.
The additional areas set aside for dried sludge storage would add an
additional tvo year storage capacity onsite. Therefore, wetting
the sludge periodically vill not cause any significant problems. The
sludge is capable of reaching 502 dryness or higher. There should be
little problem in re-drying the sludge. In order to afford a more
positive approach in protecting against vindbloving of stockpiled
sludge, EPA vilJ recommend to Metro that the sludge be stockpiled in
earthen berms, as vas originally planned. See discussion on Issue
Again, EPA believes that thl6 problem can be controlled.
5J The question of odors from che sice (not the application areas,
vnich we do not think will be a problem), is a difficult one to re-
solve. Our own field trip to San Jose has convinced us that there
will be occasional odors, especially from the ireshiy puinpea sludge.
How far those odors will carry is problematic at this time. We thinn
that given the distances of most people in the area from the site,
odors vill not generally be a problem. For those residents nearest
the northern and eastern edge of the site, there may be noticeable
odor at times. As a last resort, if the odors should prove to be a
nuisance to these neighbors, Metro District should consider buying
their properties and/or relocating them. EPA does not Eeel that the
problem should extend beyond the two households discussed here. See
discussion on odors under Issue II-3.
There is a general problem faced by any new enterprise, whether
private or publicly sponsored, that some individuals are bound to be
negatively affected by a project. There is no perfect solution to
the problem of managing metropolitan Denver wastewater sludge that
will not affect someone adversely. EPA feels that its duty is to
minimise harm to any individuals potentially adversely affected by
such a project, as well as to the natural environment. EPA will
develop grant conditions listed in Appendix A of this Volume to
minimize these impacts.
-------
I contend that's the very reason Metro wants the site so
far from Denver. They don't vant people to comrlain about
the smell, and they are stupid enough to believe that silly
barnyard stereotype so lone assosiated with fanners.
I say to those peoule that play down the odoe and talk
about aesthetics that they are quite mistaken, because a
rose by any other name still smells lijce a rose, and that
also applies to sludge.
I'd like to close by saying I hope the E-P.A. does tak?
into account not only the economic and environmental
applications, but also the sociological problem facing the
farmers in the area. In any democratic nation, the
government must watch out for the rights of the minority
lest big, powerful entities encroach on the individual who
is so often overlooked.
Finally, I'd like to point out the vary real possibility
of future litigation which could make Metro's proposed use
of the B-2 site a very costly mistake. Thansyou.
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^ , LOST CREEK
Letter #44 Ground Water Management District co,o,ad„ sows
9 September. 797°
EPA Response
Regional AdminLitAatoA.
U.S. [nvijiomnenial P/wtection rlg.en.cy
Rochj fountain - pAjubxte Ration. Vtll
l8o0 Lincoln. Stne.it Suite fOO
Denver, (olo/iado 8020J
fte: /1e6u> Deiwen. Sludge, Management Plan
(kaft (JJS /lay 1<]7»
O
CO
/Ac (Luie.cMj.XA of Lo/it (jieeh (j/iound. I-aten. I^anagement Oiatxict have filed
a lette/i, dated. JU Aug.. 7b, 'oith joun. of.fj.ce stating. oun. objection to
the pnjopoteA plan. of. locating. -ilucL^e aLxying baaing in the Lo^t ( tee/i
cbiainage btLain. On that letteA. you a-ie adv^ed that the plan pn.opo^ed
i>envej1 /'"lejbio Sewage Di^t/iict La in cLuiect violation of Jie^iilatLon-j
pnjomuljjated bp the di/iecloi^ of Lo^t (jieeh (jiound UateA i'h/ia^.ement iJi^tu-ct.
O The pu/ipo^e of i/iLd statement La to psie^esit in gsieaten deltuJ. -Oie /lea^oru)
foA. qua. opposition to the. pnopo^ed al.udg,e dn.ij.inq. plan, A* \ep/ie^eniutx.v&4
of the. people living, in the. Lo*t (jieek batin, ive feel an acute. ob-€ i~a a te/iiou* danger of contamina/iJtd *uch cui nitrate14, taltsi,
<2> and heavy melal* entering, thi*6 important ac^uifer from the proposed drying.
bd4xrL4. Since thi* i-4 a closed batin, *uch stable contaminant* would
jwiely build up to unacceptable levels and utould have a deieAe/iioiuj
effect on foodstuff *vtoduced from the land.
Tke^e contaminant* would aJLao po^e a much mo/ie i"^edia£ and serious t»oieal
QIo addition to the materials appended to thia letter, EPA baa
tained a copy of the Groundwater Resources of the Lost Creek
Drainage Basin, prepared by Kelson, Haley, Patterson, and Quirk, Inc,
June 1967. Information from this docmeot has been integrated into
the discussion on groundwater conditions in the vicinity of site B-2
(Issue II-l). Further, EPA has taken the position that groundwater
resources belov the site oust maintain drinking water standards. To
this end, EPA will require Metro to deaonstrate a positive inpermeable
lining (see Issue II-2), as velJ as to develop both an intensive site
monitoring plan and a positive plan to intercept any sit^-derivad
groundwaters that could adversely affect the area groundwater, tte
believe that given the geology of the area and these mitigation aeas-
ures, that the water resources of the Horse and Lost Creek Basin areas
will be protected.
Oj While nitrates and salts are of paramount concern to EPA, we be-
lieve that heavy seta Is will not be a problem in the groundwaters.
Beavy setals are preferentially adsorbed onto exchangeable cation
sites on materials such as clay particles. Metro will be required to
Bonitor for these heavy metals in any event in the groundwater. EPA
also does not believe that sludge applications onsite or in the 1»-
sadiate vicinity of the site will result in deleterious heavy metal
accumulations. EPA will not permit Metro to utilize the site for
sludge applications in excess of acceptable agronomic rates.
Continued next page
-------
Letter #44
continued
to ike kealth and welfare. of ike estimated, hi0\) ze^-uierit^ of trie ocla-ui.
r\ la/ipe pe/icentape of the domestic and Itve-ituch well* in trie. a~<-ea a/ie
de.veJ.oped in ike alluvium a^utfe/i. All dome^tcc uxitesi {M/i yie^tdejit^ of
the. di^sixtci -including, nuntci-pal <$w>pti.eA- nuL^i be. pumped ^w/n
und&iyzound ^ounce^. /ke/ie ta evidence ileal -Liesle -C4 tome inievrun^-^ux^.
of ivaten. fxom bedrock and. alliLvixun aitfiifen* 40 tkene Ld a xeat jA>44
-------
Attachment to
Letter #44
o
cn
WELD CO
MORGAN CO.
ROGGEN
KEENESBUI
HOSPCCT
VALLEY
jcfterson
CO
MORGAN CO
ADAMS CO
DENVER
iflENNETT
US. MWY.
NO 16
NELSON - HALEY - PATTERSON
AND QUIRK, INC.
ENGINEERING CONSULTANTS
GREELEY, COLORADO
PROPOSED GROUND WATER BASIN
LOST CREEK DRAINAGE AREA
WELD — ADAMS - ARAPAHOE COUNTIES
COLORADO
-------
Attachment to
Letter #44
o
CTi
7- s
lOSTCAt
W£ID -4Da
Y - P4 7 TEA SON *»° QU/AK
i/A/££ff£ 4A/D GEOLOG/S TS
'NCTJOM, COLO84DO
WATER 7
AND SATi
TU/CKAJEL
-------
-------
Attachment to
Letter if44
o
00
-------
Sept. 9, 1976
Toi N.E.P.A.
Froai John 5. Meyer
3.3.1 Bo* 87
Bennett, Colo.
Hei M3TR0 SLTO3E
I want to make a few coraenta about the use of sludge on farm land.
.After talking to several farmers surrounding site 3-2 and as far as
Byers, in the Prospect Valley area, and the .fatkins farmers will have
no use fnr sludge. You state by 1985 100,000 acres will be needed
for sludge application. By the report it 3eems that faro land is the
biggest dumping ground and if farmers say no to sludge that stockpiles
of sludge are going to get mighty tall. If they, Metro Sludge, can
push this on us, then we as farmers have no rights left in this country.
I wonder how many Metro citizens would turn around and use sludge on
their lawns and gardens?
Land values were discussed in the book, stating that this would
have no effect on land aalues. It was my understanding that this i3 the
reason that future developenent of Lowry is impossible. You must wonder
how many people would like to build around sludge, .tfould you?
Sludge is Metro's problem. >Vhy should it be the farners?/e didn't
hare anything to do with it's development . Many older families came
here when nobftdyelse wanted the land. It seems like the drought of
the thirties,flood of 1965, and today's market pricestare enough
problems to partake, must you also push problems like this back on them.
I am sure that every person's values his property highly because
it is something that he and she and both have worked for and paid highly
"1etro sludge thinks that it has the right to come into a community and
say here we are going to put sludge plant and ha\ng_the property owner
in that community not fight for their rights.
'e always' hear the statement this year because of our 200th
Birthday "'fe came a long way America". Have we came far enough that one
party can overtake another man's property because they need it for sludge?
In closing I quote many farmers young and old "the farmer doesn't
want Metro Sludge". Thank You
John 3. Meyer
EPA Response
CO On page 105 of the EIS, Volume I, CPA indicated that up to 40,000 ha
1100,000 acres] of dryland farms would be needed by 1985 to spread the
quantity of sludge available front the drying basins. It is highly
unlikely that Metro sludge would ever be used in great quantities on
dryland operations because of cost and the close tolerances required
on nutrient application. Metro feels that most of the sludge will
be used on irrigated farmland, mine spoil areas, municipal parks,
and sod farms. Substantially less acreage would be needed because
greater nutrient loading would be required.
Metro has about two years of storage for dried sludge in the
proposed stockpile areas. If sludge could not be distributed for
one reason or another, Metro would haul the 6ludge to the Lovry land-
fill for burial.
(?) Many urban citizens are interested In using sludge on lawns,
ornamentals, and even gardens. See Appendix T of the HIS, Volume 1.
EPA does not think that sludge should be used in hone vegetable
gardens, especially on leafy vegetables or edible root crops. See
discussions of use, Issue V-2.
QThe effect of the drying and distribution center on land values
the area is discussed in Issue 11*4.
(5) The problem presented here is, unfortunately, difficult to resolve
to everyone's satisfaction. Public utilities in general and sewage
treatment facilities in particular do not usually make welcome neigh-
bors. However, they are a necessary part of modern life and have to
go somewhere. The proposed project ie being designed to minimize as
much as possible the adverse impacts at the site and elsewhere. This
EIS process is the means by which these impacts are assessed and, if
possible, reduced to as low a level as possible. It is hoped that
eventually the resources represented by sludge wil3 be viewed as an
asset* not a liability, to the local residents.
-------
September 9, 1976
Testimony of Held County
Denver Metro Sludge Management Plan
Draft EIS May 1976
Position: The position of Weld County regarding the recommended alternative
presented is negative.
The sludge drying facilities will have negative impacts on Weld
County with: 1. deterioration of ground water quality due to leachates
carrying salts, including nitrates, to the water table; 2. odor from the
drying basins and stockpiles; and, 3. loss of irrigation water due to use
in transport. •
A sizeable parcel of agricultural land area in Adams County will
be removed from production.
The sludge reuse area will have a negative effect on Weld County
with: 1. introduction of heavy metals into the soils and food chain creating
hazards to human consumption and possible crop yield reduction; 2. hazards
of parasite longevity in the sludge; 3. water quality degredation due
to leaching; 4. air quality degredation due to particulates and aerosols;
and, 5. long term impacts of accumulation of trace elements which become
inhibitors of plant growth, salt accumulations which become plant growth
inhibitors and potential ground water pollutants, heavy metal accumulation
which affects the food chain, and nitrate pollution and eutrophicaticm of
surface water due to run off and irrigation tail water.
Control and mitigation measures are not cleat, nor are thev adequately
defined regarding UU UJllLUrili of Weld County. Management techniques regarding
sludge application leadings are not developed to a sophistication that define
accurate practices.
Water pollution c^oround watecAihich will ultimately affect Weld
County is expected from sludge drying. Southern Weld County is currently
affected by high nitrates and undisolved solids in domestic and municipal water
supplies. Accumulative effects to this problem will be detrimental to those
supplies. The actual contamination of the ground water and the extent of that
ground water pollution is not defined. The proposal does not define mitigation
or management techniques of the drying site. Corrective action procedures
are not developed to reclaim polluted ground water from the escaped contaminates.
If the proposed alternative is selected, site B-2 appears to be the
best alternativg__foc_the_drying facilities. Weld County would require drying
beds to be/fCBoletely lingE to avoid leachate of contaminates into the ground
water. Also test Mies must be required to moniter the ground water affect by
the drying facilities. Complete mitigation and management practices must be
detailed and approved prior to operation.
Continued next page
EPA Response
uj Bach of these Impacts has been recognized in the EIS. Discus-
sions of these probleas and potential resolutions are found under
II-2, (groundwater). Issue 11-3 (odors)» and Issue 1-3 (water
rights). __
l2J This Impact is discussed under Issue 11-8. EPA believes the loss
ot farmland and productivity to be relatively snail.
All of these potential impacts are discussed under the following
topics: heavy metals, Issue I-*l; parasite longevity, Issue V-l; vater
quality. Issue Il-2i aiT quality, Issue II-5; and long tern. impacts
under Issue V-5. EPA does not believe that any serious air or water
quality inpacts will occur with proper sludge applications, particu-
larly if irrigated farmland is used.
The State of Colorado is formulating regulations on the utiliza-
tion of sludge for both agricultural and other uses. EPA will not
allow Metro to distribute sludge except to municipalities until these
regulations are finalized. EPA will also recommend specific measures
for management and control to the Metro District (see Appendix A and
discussion under Issue V-£).
QEPA will require lining of the basins at the B-2 site, as well as
nti&uous aonitoriag and an emergency plan for pumping in the event
that pollutants are detected. See discussion under Issue II-2.
-------
If sludge application Is to be considered on land 1n Weld County,
complete management and record keeping techniques must be developed and nore
detailed data regarding application loadings must be obtained prior to actual
application.
»
It Mould appear to Weld County that other alternatives discussed
for Metro Sludge disposal may be more environmentally sound and have less
inpact on Meld County than the selected alternative. It appears that
economics have been the major factor in determination of alternative
selection. Weld County would suggest a more complete review of other
alternative that may require more capital expenditure but would be more
environmentally sound.
EPA Response
[6J EPA agrees that a systs» of record keeping la Important for the
Twageeent and control of sludge. EPA will i n iinsii nil a systsa to
Metro; however, state controls will have prlaaey.
Economics have not been the prime consideration In EPA's deter-
tlon that the proposed systoa should be lapleaeated. There Is
an Institutional problea Involved In the National Envlroraental
Policy Act procedure as It applies to mmicipal wastewater treatment
grants. In the past and in this case as well, the EIS was not de-
veloped until Metro had already gone thru its own evaluation process
and selected the land application alternative. EPA is in the position
of having to stake an overall judgment about the nerlts of a selected
proposal against other possible but often not as intensely evaluated
alternatives. EPA's position has been that it will accept Metro's
reasoning and data on the subject unless it has reason to question
the logic or data. We have differences over specific portions of the
project and differences In Judgment as to whether factors, such as
the presence or absence of a ready aarket, are critical or not to the
overall "success" of the project. EPA and Metro do agree In princi-
ple however, that a land recycling approach for wastewater aludge is
a desirable way to proceed, unless there are substantial adverse ef-
fects in doing so. The problcas so far raised, the critical ones
such as groundwater problems, do appear to have nitigating solutions.
Most of the other areas of concern—heavy metals, ready markets, means
of control, etc.—are areas of uncertainty. Data is not definite enough
to be able to sake certain statements on most of these Issues. Two
positions are clear, however: 1) the Metro system will "work", at
least to the extent sludge will be converted into a more usable and
disposable form; 2) the type of sludge created does have enough nu-
tlents and soil-building materials to warrant this type of approach*
There are also some minor adverse impacts that would occur no matter
where this system would be implemented: loss of soil where the basins
arc constructed, some odors, and sane resentsent by people living in
the area. EPA is also willing to look at other alternatives In detail*
If this system should prove to be politically lnfeaslble.
<2L
-------
Letter #47
EPA Response
This petition contains the names of 292 persons in the general
vicinity of the proposed fi-2 drying site who are opposed Co the
project. A number of the persons on this list have stated their
objection to this project through letters in this document or at
the public hearings. EPA can only anticipate that the sludge
drying project will not be able to utilize very tauch of the dry-
land farm operations in the rural Adams County area with this kind
of opposition.
/-/ IN .a S L 0
si g^tT^re s i
A -\Vi v:e' the ur.d^rsigh^ ^residents and/or landowners of eastern
/ Adams County DO/APPROVE of Metro Denver Sewer spreading the
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sludge of its operation in eastern Adams County.
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We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
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-------
We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sower spreading the
sludge of its operation in eastern Adams County»
Letter #47,
continued
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-------
Letter #47.
continued
We, "the—undersigned residents ancf/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
SIGNATURE
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Letter #47,
continued
We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adair.s County.
SIGNATURE
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-------
Letter #47„
continued
We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
SIGNATURE
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ADDRESS
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-------
He, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
SIGNATURE
PRINT NAME
ADDRESS
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-------
We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
SIGNATORIES NAME
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Letter $47
continued
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Wo, the undersigned residents and/or landowners of eastern
Adams County DO HOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
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-------
Letter #47
continued
We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
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-------
Letter #47
continued
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We, the undersigned residents and/or landowners of eastern
Adams County DO NOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
SIGKATPRS
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-------
Letter #47
continued
We, the undersigned residents and/or landowners of eastern
Adams County DO HOT APPROVE of Metro Denver Sewer spreading the
sludge of its operation in eastern Adams County.
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-------
A RESOLUTION OPPOSING THE DUMPING OF SLUDGE
FROM METRO SEWAGE DISTRICT IN ADAMS COUNTY. , „
to I 3-24
WHEREAS, Metro Sewage District has historically dumped
Letter #48
1 sluuge from disposal planzz at the Lowry cc&bing Range; and
WHEREAS, the dumping of sludge at the Lowry Bombing Range
has contributed to the deterioration of the environment for
the surrounding area; and
WHEREAS, this process of disposal of sludge has created
noxious odors and a potential health hazard for the general
public; and
WHEREAS, the dumping of sludge has rendered areas of
Lowry Bombing Range unsuitable for reclamation.
NOW THEREFORE, BE IT RESOLVED that the City Council of
the City of Brighton vehemently opposes the dumping of sludge
in Adams County.
BE IT FURTHER RESOLVED that the City of Brighton pursue
every legal mechanism to prohibit the dumping o£ sludge by
Metro Sewage District at the Rocky Mountain Arsenal or at any
location within Adams County. ^
ADOPTED this 3rd day of August, 1?J
Rayor //
Attest: ______
Pub"e hearln9*
y The U. S. EiHiiumrwnfl Preiocbos Aft-
" cy has scheduled pMbbc besriafi Sept. I
• oe the sludge dtapoeal plan proposed by the
Metropolitan Denver Sewage Diipoael
Dutnct
TV meeting oo Sept I will befta at lam
in Room of the U & Post Offiee MUtac,
ICS Sun* St a Denver. Tte SepL * meeting
will comet o( two iiwiw, 1:31 pm. mm
7 9 p.ot« m the Adama Couty Tligi—I
Fairgromda Aanei flaking, East UMh An*
mm and tfcndcraan Road.
1H» commas period oa Ike dnft aav»
menu! impact tatpment will oaaad Ml
EPA Response
The City of Brighton is oppoaed to any "dumping of sludge" on the
Rocky Mountain Arsenal or anywhere in Ada&s County, in view of the
experiences at Lowry Bovblng Range. It is sonevhat understandable
that the city of Brighton is opposed to further activities that could
endanger their water supply, especially as a result of activities on
the Arsenal, and the long history of poor sewage treatsent effects on
Ban Lake. It is also sotaewhat unfortunate that the city was so non-
specific about the type of operation proposed. Metro will not be
duaplng sludge in teras of disposing of it at the proposed B-2 site.
Disposal if necessary vill continue to take place at the Lovry Book-
ing lange. Sludge applications could take place in Adaas County, but
only at agronomic rates intended to maintain agricultural production.
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Letter #49
EPA Response
The Board of Directors of the Brighton Chamber of
Commerce have unanimously adopted a resolution opposing
the dumping of sludge in Adams County. The dumping of
Metro Sewage District's sludge was seen by the Board as
a detriment to the quality of life in Adams County and
especially the Greater Brighton Area. The dumping would be
in direct contradiction to the Chamber's goals of improving
the area for living, farming, and doing business.
The resolution is as follows:
WHEREAS, the dumping of Metro Sewaoe District sludge would
substantially deteriorate the environment of the surrounding
area as it has at the Lowry Bombing Range; and
WHEREAS the process of disposal of sludge has created
ro
ui noxious odors and a potential public health hazard; and
WHEREAS valuable land could be rendered unsuitable for
reclamation.
NOW THEREFORE, BE IT RESOLVED that the Board of Directors
of the Greater Brighton Area Chamber of Commerce opposes the
dumping of sludge by the Metro Sewage District in Adams
County.
ADOPTED this 27th day of August, 1976.
David W. Grayjfilli
Executive Vice President
It is also not clear what Is meant by the "deteriorated environ-
Mot" at the Lowry Bombing Range. Metro sludge applications before
1972 did cause an odor problem, due in part to the kind of sludge
appliad and the form of operation. We believe that this problen has
essentially been corrected. Furthermore, the Lowry operation includes
the Denver landfilling operation which probably poses a greater envi-
ronmental long-term hazard than Metro's sludge landspraading. Metro's
rates of applications are now in excess of agronomic rates, but given
enough time, there is still the strong likelihood that the area of
Metro sludge applications could revert to productive grazing land.
A groundwater study by USGS has shown that although some well con-
tamination has taken place, this could be due to surface runoff in
certain areas. The type of system proposed by Metro is Intended to
eliminate this form of concentrated dumping of sludge in a small area.
The Impacts are severe because too many nutrients as well as metals
have been loaded into one area; overfertilixation could create the
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Letter #50
CITY AND COUNTY OF DENVER
a. H. UettlCHOLS. JR.
DEPARTMENT OF PUBLIC WORKS
Septeaber 8, 1976
WASTEWATER MANAGEMENT D[V.
5055 WASHINGTON STREET
DENVER, COLORADO 80216
U. S. Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado 80203
Gentlenen:
Re: E.I.S. for Denver Metropolitan Sewage Disposal District Sludge
Management Plan
The draft Enviromiental Iapact Statement as prepared by the U. S. Environmental
Protection Agency relating to the sludge management plan of the Metropolitan
Sewage Disposal District has been reviewed and evaluated. The City and County
of Denver supports the concept of land disposal of sludge generated by the
Metro and Denver Horthslde Treatment Plants. Specific contents relative to
the draft iapact study will be forwarded at a later date.
Sincerely yours,
P.E.
itor
JZ:clj
EPA Response
-------
Letter #51 . . . EPA Response
Statement by Alan L. Canter, Chairman
Metropolitan Denver Sewage Disposal District No. 1
at the September 8, 1976
Public Hearing by U.S. Environmental Protection Agency on the
Metropolitan Denver Sewage Disposal District No. 1
Sludge Management Plan
0
ro
-------
The statement on page 13 of the summary concerning the need to re-
duce the amount of cadmium or other heavy metals being allowed in
the sewer system is noted, and you can be assured that the Metro
District Board of Directors has the necessary legal authority and
will take action to amend that portion of the Service Agreement if
necessary.
On pages 13 and 14 of the summary is an indicated concern about con-
trolling sludge application to agricultural lands. The 1976 session
of the Colorado General Assembly amended the Colorado Solid Waste
Disposal Sites and Facilities Act to make the Colorado Department
of Health and the Colorado Department of Agriculture responsible
for applicable regulations and control of sludge application on ag-
ricultural land. It would be appropriate to assume that the state
agencies will act responsibly in this regard. Appropriate state
regulations are presently being formulated, and the Metro District
will certainly comply with those regulations.
The suggestion on pages 14 and 19 of the summary for mitigating ne-
gative impacts at the Lowry Bombing Range by spreading sludge over
larger areas of the bombing range can be helpful only if additional
lands can be made available to the Metro District. At the present
time all land which is actually available to the Metro District is
being used for sludge recycle purposes. In addition, the Lowry ope-
ration still requires high expenditure of energy and money and high
chemical content of the sludge cake, and we are trying to eliminate
these. Of great environmental importance is the fact that the Lowry
Bombing Range site has three drainage basins bringing surface water
flow through the site, whereas proposed Site B-2 is located at the
top of a drainage basin with much less drainage for which control
would be required.
The statement on page 22 of the summary to the effect that EPA will
require the Metro District to develop research sites should be tem-
pered with the realization that the Metro District already has many
Continued next page
EPA Response
4J EPA will Insist that Metro take all possible measures to reduce
Tot heavy metals and toxic organic contributions from Industrial
sources into the Metro wastewater systea. Metro should accelerate
its Industrial source survey prograa before construction of this
project Is begun. See Issue 1*1.
^5^ EPA will require Metro to store sludge onslte or dispose of It by
landfill (except for nuniclpal use) until such time that the final
regulations are put into effect by the State of Colorado. See Issue
V-4.
Ve agree that it does not sake sense to continue the sane mode of
operation at Lowry Bashing Range over greater areas. Ve do feel that
consideration of Lovry Boshing Range as an alternative site for the
Metro sludge should be pursued by MetTO, even though technlcslly the
b-2 site is better. Land ownership of Lovry Bombing Range is cootpla,
with the City of Denver, the State of Colorado, private parties and
the U.S. Air Torce owning various parcels is the area.
-------
research projects underway for the purpose of revising the design
of the facility if needed, for preparation of an operations manual,
and for developing a system for recommending sludge application
rates and practices to the ultimate users.
The concern stated on page 27 of the summary in the event that there
would be an inadequate market for sludge is probably not a valid
concern. We have indications from a large number of individuals and
agencies that a need and a desire for the dried Metro District sludge
•xiats. In the unlikely event that there would be a market problem,
the Metro District could truck the dried sludge to the Lowry Bombing
Range, could truck the dried sludge to some other approved sanitary
landfill, could burn the sludge as a fuel, or could use the sludge
for a number of other purposes such as animal feed or poultry feed.
It is improbable, however, that the Metro District would not have a
sufficient market for the dried sludge production by the time the
sludge drying facility would be in operation.
On page 25 of the summary is a stated concern about airborne sludge
problems. The design of the sludge drying facility provides for
watering stockpiled sludge in the event of high wind problems.
The offensive odor problem mentioned on page 25 of the summary prob-
ably will not result based on decades of experience with anaerobically
digested sludge, but in the event of an upset digester problem, the
Metro District would store such sludge in a sludge holding tank and
then provide subsurface injection under controlled conditions.
A general statement concerning the Environmental Impact Statement
Summary would be in order. Some portions of the summary are not sup-
ported by the information contained in the draft Environmental Impact
Statement. As an example, the advantages and disadvantages of using
the Lowry Bombing Range as found on pages 27 and 28 of the draft
Environmental Impact Statement do not support the inferences in the
summary document that more consideration should be given to continued
use of the Lcwry Bombing Range site.
Continued next page
EPA Response
0, EPA1a intention here was to develop research data from ongoing
studies by Metro at the Greeley test area. This information was
provided to EPA.
V* reluctantly agree that the proposed drying system could still
prove successful in cost-effective terms even if the dried sludge
were to be trucked and disposed of at the Lowry Landfill. EPA does
not think that the evidence has been presented that most or all of
tfcs sludge can be beneficially recycled at this point in time. How-
ever, EPA also thinks that developing such markets can cone only after
Che system has been operational for a while. The research and demon-
stration proposed with this system is also critical in developing
an understanding as to which potential markets would be best for this
type of sludge. See Issue V-3.
(9) EPA feels that Metro should give strong consideration to restoring
tne original concept of sunken earthen basins to store sludge, in
order to lessen the windblowing potential. Also, Metro plans and
specifications must contain a detailed plan for wetting and control-
ling sludge movement in the event of high winds. See Issue II-5.
UQj Although odors from the drying basins will be considerably lees
t&an that from undigested sludge and other normal wastewater treatment
plant odors, there will still be an odor detectable fro® the drying
basins. EPA will require an emergency disposal plan for sour digester
contents. Metro should be prepared to campensste those two residences
heereet the site to the north and east, in the event sludge odors
prove to be 8 nuisance.
Q Ths final EIS and mwry will hopefully be more consistent.
-------
4
Table A on page 5 of the summary indicates concentrations of major
Letter plant nutrients in sewage sludge and various other sources of fer-
COIltinued tilizer. It is suggested that a similar table be provided which
would indicate the comparison of heavy metals found in commercial
fertilizers and other fertilizer sources to that found in sewage
sludge.
EPA Response
Q3 EPA does not have this information at lt« disposal, &1 though
¦re aware that cooeerclal fertilisers do contain other aaterlals,
eluding soae residual heavy metals.
<3>
On page 20 of the summary as well as throughout the Environmental
Impact Statement draft is the general statement that intensive moni-
toring would be required for this facility. It is important for
all concerned to understand that intensive monitoring is a part of
the design and operation plan for the drying basin site, and such
intensive monitoring has been an important part of the total District
plan not only for the future facilities but also—for the past, present
and future use of the Lowry Bombing Range site.
Yes, we recognize that Hetro is prepared to intensively monitor
groundwater around site B-2. EPA has prepared a suggested oon-
icorlng scheme chat is contained in Appendix A; EPA will also require
Metro to develop a plan of action for renoval of contaminated waters
that could affect any aquifers offsite. See discussion under Issue
II-2.
0
OJ
o
In the draft Environmental Impact Statement on page S4 reference is
made to the cost of land for proposed Site B-2. The one statement
which has an estimated cost of one million dollars for the site is a
rough high cost estimate, and does not agree with the anticipated
market value of the land.
Along with this statement we are submitting a separate document which
includes numerous technical corrections for use in revising the final
Environmental Impact Statement.
©
This will be updated to reflect current coat*.
Again, I compliment: the Environmental Protection Agency for the
thorough job accomplished in assessing the environmental impacts
of the proposed Metro District sludge drying basin facility, and
thank you for the opportunity to present a statement at this public
hearing.
WEK/J
3/31/75
Continued next page
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Corrections and Conments to Accompany Statement by
„ Alan L. Canter, Chairman
Letter Metropolitan Denver Sewage Disposal District So. 1 EPA Response
COIltinued at t11® September 8, 1976
Public Bearing by D.S. Environmental Protection Agency on the
Metropolitan Denver Sewage Disposal District No. 1
Sludge Management Plan
p.i.
p.i.
2.
3.A.(1)
p.i. 3.A.(2)
CO
Description of action. Sludge production will be 107
dry tons per day, .not per year.
EPA indicates that soil as an agricultural resource
will be lost from the 600 acre drying basin. This is
not necessarily the case. Irrigated farming could ac-
tually occur in the bottoms of the drying basins, which
could in effect increase the agricultural output of the
600 acres as opposed to dry land farming now practiced.
This item indicates that the ground water quality in
the area of the sludge drying and distribution center
will gradually be deteriorated by the leachates from
the bottom of the drying basins, carrying salts, in-
cluding nitrates, to the water table. From our field
investigation no water was found at even 100 feet below
the ground surface. Discussions with a farmer in the
area of the drying center indicated that ground water
is more than likely about 240 feet below the ground
surface. A reasonable estimate would indicate that
leachate from the basins would take many years, pos-
sibly longer than 100 years, to reach the ground water.
The quality, as well as quantity, of the leachates is
still unknown and both of these items can best be deter-
mined from field investigations after the system is ope-
rating. Because of the long period of time before the
leachate could reach the ground water, ample opportunity
is afforded to determine the extent of the potential
problems under actual operating conditions and to in-
plement mitigative measures. An intensive monitoring
system is planned as part of the project. The system
includes deep and shallow monitoring wells and lysimeters
under selected drying basins for determining the quantity
and quality of any leachate. If a problem is predicted
as a result of the monitoring program, mitigative measures
can be taken to prevent the potential problem from be-
coming a reality. The alternative mitigative measures
could include lining or underdraining the basin, installing
cutoff trenches down to bedrock, a system of shallcv and
deep veils, or some combination of these methods. A po-
sitive method of ground water pollution abatement can be
p. 1 2. Corx«et«d.
P i 3A(1) Restoration of this faralasd vill be essentially irrever-
sible In the next 23-50 years. The possibility of loi-
ter* reclamation does exist.
p 1 3A(2) Well water is found at varylag depths In the site vicinity
(See Imm XX-1). EPA feels that positive protection via
lining vust be deaonstrated as well as nonitorlog and
emergency pumplag procedures.
Continued next page
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2
Letter #51.
continued
CJ
r\j
devised once the extent of the problem is known. All
of the alternative methods are costly, though some
more so than others. The money used to implement any
one or a combination of these methods could be wasted
if it were included with the initial project construc-
tion and no serious problem actually existed.
In the EIS the EPA contends that lining the basins with
pigmented bentonite is the only positive means of pre-
venting leaching from the drying basin. We disagree.
Because of the alternate wetting and drying cycles in
the basin, the bentonite will crack allowing leakage.
Further, the EIS says that ground water pumping is not
a positive way of preventing ground water pollution.
He disagree with this statement. It has been our ex-
perience that ground water pumping can be an effective
means of keeping undesirable materials out of the ground
water.
p.i. 3.A.(3) This item indicates that an increased amount of water
over that now consumed in the existing sludge disposal
practices of Metro will be carried in the sludge, purge
water and additional irrigation water to the Adams County
site, reducing flows in the South Platte River downstream
of the central plant. It is anticipated that at the maxi-
mum, purge water may amount to roughly 1.3 million gallons
per day (MGD). With this purge water and sludge at 3 per-
cent solids concentration, the total amount of waters sent
out to the drying and distribution center would amount to
less than 1 percent of the anticipated total plant dis-
charge in 1985. This represents an insignificant 1.7 MGD
at maximum.
p.i. 3.A.(5} Concern is raised in this item that odors generated in
the drying basins — especially during digester upsets —
may be objectionable to the surrounding farmers and other
residents. On numerous occasions we have indicated to
the Region VIII Environmental Protection Agency office
and to Engineering Science, Inc., preparers of the Envi-
ronmental Impact Statement, that sludge from improperly
operated or upset digesters would not go to the drying
basins. This material would either be returned to the
sludge digestion system or injected at the drying and dis-
tribution center, thus preventing any odor problem, with
the 25 mile sludge transmission pipeline, approximately
one day of time is available to take preventive measures
at the drying and distribution center to keep the unwanted
material out of the drying basins and divert it to the
subsurface injection area. It is our opinion that this
operational ability is sufficient to prevent odor problems
at the drying and distribution center site from improperly
digested sludge.
EPA Response
P i 3A(3)
This issue is discussed under Issue 1-3 ar.d reflects your
latest data.
3A(5)
EPA experience is that there will be soae odors free nor-
tn&l operation of this system. The emergency procedures
for disposal of sour digester contents bus': also be fol-
lowed. See Issue II-3.
Continued next page
-------
3
EPA Response
Letter #51.
continued
p.ii. 3.A.(6) It is indicated in this item that severe effects on
soilsr plants and ground water would occur if the site
were to be used for a disposal area. This conclusior
is questionable without any stated basis.
p.ii. 3.B.(1) Heavy metals in crops have never been shown to be a
hazard to humans even though there may be a possible
hazard.
p 3A(6) LPA agrees that the potential impacts are problematic; ve
are not w:lllng to accept such potential degradation,
however. Emergency disposal at Lovry is acceptable. See
Issue 11-15.
p ii 3B(1) True, lap ,cts should be stated ss potential.
W
oo
p.ii. 3.B.(2) EPA indicates that the longevity of certain parasites
such as ascaris beyond the drying storage period com-
prises a public health hazard, especially in home garde.is
and city parks. There is no basis in fact on which to
conclude that a public health hazard is associated with
the use of sludge on home gardens and cicy parks (ref.
page 113 and 143).
p.ii. 3.B. (3) EPA indicates that water quality degradation from salt
and nitrate movement below the root zone in home gardens,
irrigated farms, city parks and sod farms is a long-term
cumulative fact. It must be pointed out that the use of
sludge presents less of a threat to the water quality than
does the use of commercial fertilizers w.lich are currently
being used. One must realize that fertilizer is a neces-
sity (ref. page 144).
p.ii. 3.B.(4) EPA indicates that air quality may be degraded by parti-
culates and aerosols during severe wind storms, especially
in dry famed areas. It is inconceivable at the loading
rates proposed for the dry land farmed areas that there
could be any quantifiable degradation of air quality as
a result of sludge particulates and aerosols during severe
wind storms.
p li 3R(2) EPA has modified it; position on park use, as long *s
>5etro is willing to make the risks itnovn to potential
users. State regul tions should also be able to control
this problec, ETA &till opposes use of sludge ort home
vegetable gardens. See Issue? V-l, V-I, and V-4.
p ii 3B(3) EPA agrees that the potential threat is nc greater than
for corroercial fertilizers if properly applied.
p ii 3B(£) We agree that the hazard is very slight.
p.ii. 3.C.(1) It has not been shown that heavy metals enter the food
chain. It is possible that just the opposite is true.
p. 9 The first paragraph on this page indicates concern about
the reliability of individual farmers adhering to recom-
mended sludge application rates and quantities for a
given piece of land and other required cultural practices.
It is highly unlikely that farmers would overload their
fields with detrimental levels of "sludge" fertilizer
just as they would not do this with commercial fertilizer.
Such action would be monetarily wasteful both in terms
of production deterioration and the cost of the wasted
fertilizer.
p ii 3C(1) Research has established beyond a doubt that certain
plants and animals do concentrate heavy metals. See
Issues 1-1 and V-l.
p 9 We agree chat this possibility is low, although over-
enthusiasm could be a problem.
P- 9
The last paragraph on this page indicates that the pro-
posed alternative has a total capital cost of $25.3 mil-
lion. It is difficult to derive this cost even if the
digesters are included in this cost. The construction
Continued next page
V 9
The present worth cost should have been $2£.0 million
including the digesters, $17.7 million without including
digesters (see Table 1, Volume I). These figures are
estimates only so nay differ slightly from estimates from
other sources.
-------
Letter #51.
continued
p. 12
p. 12
p. 17
co
p. 18
p. 23
cost for the digesters is approximately $6,500,000,
so the remaining cost for the solids recycling program
vould be $19,400,000 according to the information in
this last paragraph. This amount is higher than the
CH2M Hill estimate for the capital costs of implementing
the solids reuse system, which is roughly $17,000,000.
EPA indicates that subsequent complaints about odors
forced Metro to modify its method of sludge disposal
from landfilling to land spreading at Lovry. This state-
ment is incorrect. It should state that subsequent com-
plaints about odors led Metro to modify its method of
operation from surface land spreading to land spreading
and incorporation into the soil.
In the last full paragraph near the bottom of the page
it is indicated that Metro Denver adopted the recommen-
dation of land disposal because of an environmental net
benefit and the possibility of revenue from the sale of
agricultural products. To our knowledge, the Metro Dis-
trict never adopted a land disposal system, but instead
they adopted a solids recycling or beneficial reuse sys-
tem. Also, the possibility of revenue from the sale o£
agricultural products was not a deciding factor in adopting
the solids reuse system.
"Alternative No. 16D, Vacuum Filtration - Pipeline Trans-
port to Solid Haste Recycling Plant."
ttie final findings of the Denver Regional Council of
Governments Resource Recovery Management Committee in-
dicated that it would appear that this alternative, al-
though showing much promise, will not be implemented
for many years due to the poor economics associated with
resource recovery and reuse of solid waste materials.
EPA indicates that recent work on composting sludge shows
great environmental and economic promise. This is a dif-
ferent picture than can be gleaned from the references
relating to composting. Although it may have promise,
there are certain distinct disadvantages with compost.
Probably the major problera is the reduction in nitrogen
concentration in the end product. Nitrogen content of
compost is only about 1/3 of that which is in sewage
sludge before composting.
The statement is made that EPA intends to evaluate whether
the thermophilic range is desirable and within reasonable
cost limits given the present design of the anaerobic di-
gesters. There are many promising attributes to thermo-
philic digestion, however, there are also .Tiany problems
associated with thermophilic digestion. It is suggested
EPA Response
P 12
Thie statement: has been corrected.
P 12
This stateaeot has been corrected.
P 1'
EPA has so stated in this KIS.
p 18
The we nitrogen loss 1b evident In sludge drying (aee
Figure 13, Voliae I of this EIS) .
P 23
EPA agrees tad Is willing to discuss the po»»lbility of
evaluating thermophilic digester operation.
Continued next page
-------
Letter #51,
continued
EPA Response
p. 26
p. 28
p. 28
OJ
CJ1
p. 29
p. 29
p. 30
that the Metro District and EPA enter into a joint
effort to evaluate thermophilic digestion when the
District's anaerobic digesters are in operation.
Figure 3 identifies the Metro Denver sludge drying and
distribution site B-2 and the Lowry Bombing Range as
well/ however, the figure is incorrect. The location
of the Lowry Bombing Range should be to the west of
site B-2, rather than east of site B-2.
In the paragraph at the top of the page it is indicated
that the Lowry recycle site is closer to sod farms than
is the selected site B-2. By scaling off the map pro-
vided in the Environmental Impact Statement, the sod
farms are considerably farther away from the Lowry re-
cycle site than is site B-2. For this reason, this
statement in the EIS appears erroneous.
Item 5 - The statement is made that a potential health
risk may be associated with actual physical contact
with the sludge. If this is so, wastewater treatment
plant operators should not have one of the lowest in-
cidences of disease normally associated with contact
with domestic wastewater. It appears that EPA is doing
little to eliminate the stigaaa surrounding recycling
of domestic wastewater or sludge for beneficial purposes.
At the bottom of this page it is indicated that nitrate
concentrations in the percolating water from the drying
basins may be reduced by bacterial denitrification. It
is further indicated that this process occurs under
aerobic conditions. This is probably a typographical
error, because denitrification occurs under anaerobic
conditions.
"Drying basin design alternatives." In this section it
is indicated that deterioration of ground water quality
may occur beneath the drying basins due to percolation
of the liquid phase of the sludge into the ground water.
Particular concern is associated with nitrate contamina-
tion of the ground water. The concern for ground water
contamination is understandable, but the actual contami-
nation may never occur, and if it did it probably would
not occur for many years, perhaps more than 100 years,
even if no mitigating measures were taken. Consequently,
there is ample time to put the system in operation, mo-
nitor the percolation characteristics such as quality,
rate of movement, etc., and then devise mitigating measures
EPA indicates that the work being done at Greeley might
be expanded to include studies of denitrification in the
ponds. One must recognize that time is of the essence
P 26
p 28
This figure hu been corrected.
Distance-vise, the Lowry site is closer to sooe sod farms.
p 28
P 29
EPA oust approach pathogen transfer from a public health
standpoint that the risk is increased. Although no obvious
increase in vaterborn pathogen diseases has been noted with
wastewater treatment plant workers, there is also very
little hard research data on the subject.
This has been corrected.
P 29
See discussion under Issue II-2.
P 30
EPA has waited until the Greeley test results were avail-
able. See Issues 11-1 and II-2.
Continued next page
-------
6
Letter #51.
continued
p. 30
p. 31
p. 32
p. 51
00
cn
p. 68
p. 72
in this program, but the District certainly would be
willing to cooperate further with EPA and look at
d«nitrification at Greeley.
EPA indicates that they are interested in whether ex-
cess capacity will have an influence on secondary growth
impacts and whether this capacity is excessive. They
feel that it should be evaluated further. It is unrealis-
tic to believe such excess capacity could have any effect
on area growth.
EPA states that the Metro District has indicated that
no more than 180 hectares, 450 acres, of the proposed
240 hectares, 600 acres, drying and distribution storage
area need to be developed immediately. Current District
plans are to develop the entire 600 acres at this time
due to the inflated costs associated with development of
the area at a later date.
EPA indicates that although the proposed system appears
most advantageous, some modified version of the existing
system is the most likely option in the event the proposed
system proves infeasible. Based on the alternative study,
this statement is incorrect. If the present system were
to prove infeasible, incineration would probably be the
next most likely alternative.
In response to the statement that "the proposed sludge
reuse site, except for the irrigated farms in Weld County,
are plotted on a geological map. In general, water
bearing formations used intensively as a ground water
source are less suitable for sludge disposal. Many other
factors are important, however, the geologic character
of an area cannot be the only criteria for site selection",
it can be stated that the District will comply with all
requirements and standards as established by the Depart-
ment of Agriculture and the State Department of Health in
regard to the distribution of its marketable product as
a fertilizer, and would not attempt to select sites which
should be included or excluded from sludge utilization.
EPA indicates that because of the potential for emission
of odorous air contaminants from the drying distribution
center, an emission permit from the Air Pollution Control
Division of the Colorado Department of Health will be re-
quired. The Metro District will certainly acquire such
a permit if it is required for the operation of the faci-
lities .
EPA indicates that the representative irrigated farm also
lies in an area which is devoted to farming activities.
It is located approximately 0.8 kilometers Cs mile) east
of Platteville, which is a small rural community. The
farm lays 1.5 miles east of Platteville rather than 0.5
Eliles.
EPA Response
p. 30
V 31
V 32
P 51
66
T 72
The CIS acknowledges this point in the second paragraph
on p. 31. The draft Denver Regional E1S for Wastewater
Facilities and the Clean Water Plan discusses the proble
of grovth in detail. The problen of present and future
capacity is discussed fron an engineering viewpoint in
Issues 11-12 and 11*13.
This will be reflected in the EXS»
This position of Metro has bees noted.
We expect Metro to do so. See Issue A.
Metro will be required to apply for an eaission permit
with the Colorado Air Pollution Control Division.
This has been corrected.
Continued next page
-------
Letter #51.
continued p. 81
p. 81
p. 84
co
p. 89
p. 93
EPA Response
EPA indicates that the Denver Regional Council of P Thi» has been amended in the EIS t«xt.
Governments is the planning agency whose purpose is
to coordinate plans of local and county governments
and to ensure through the A95 review process that
federally funded projects are in harmony with these
coordinated plans. It infers that COG is presently
studying the feasibility of coordinating a solid waste
management program with Metro Denver sludge management
system. This, however, is no longer the case, and the
findings of the Solid Hastes Management Committee are
that the coordination of programs is uneconomical at
this time.
EPA indicates that the City and County of Denver uses p. 81
a small portion of the Lowry Bombing Range for the
disposal of its solids waste. Metro Denver Sewage
Disposal District also uses this area on an interim
basis for its sludge recycle operation. The Metropoli-
tan Denver Sewage Disposal District does not use the
City and County of Denver sanitary landfill area, but
does use a portion of the land under ownership of the
City and County of Denver.
Under the section entitled "Land Values," it is indi- P 84
cated that the present market value of the 2,000 acres
of land under consideration for the drying and distri-
bution center is $1 million. A CH2M Hill report entitled
"Metro Denver District Sludge Management, Volume III
Agricultural Reuse System Predesign" is indicated as the
source of this market value amount. The subject report
in no way indicated that the market value of the land
was $1 million or $500 per acre. The value for the land
indicated in the report was based on the assessed valua-
tion of the property per the Adams County Tax Assessor's
records. The assessed valuation was considered to be
33 percent of the market value, but even using this ap-
proach the market value seemed to be lower than reality.
In some cases the land value would have been less than
$50 per acre. Consequently, the consultants arbitrarily
settled on $500 per acre as the cost of the land solely
for the purpose of economic comparison of the three sites
investigated in the report. The $500 per acre amount
was used for each of the three sites.
The reference to Volume II Agricultural Reuse Predesign P 89
is incorrect. It should be Volume III Agricultural Reuse
Predesign.
Section entitled "Drying and Distribution Center Operation P 93
and Layout." The first paragraph under this section in-
dicates that liquid sludge could also be distributed from
the central plant and booster purr.p station. This mode of
operation was discussea in the predesign report, but the
ability to obtain liquia sludge at the booster puir.p station
has been eliminated in an attjp.pt to centralize the distri-
bution of sludge at the drying and distribution center.
This has been noted In Che EIS.
This will be aaended.
This has been corrected.
This has been corrected.
Continued next page
-------
EPA Response
P- 93
Letter #51
continued
p. 96
p 96
In the last paragraph on this page at the bottom of p 93
this paragraph it is indicated that fences will be
erected around the drying basins and stockpile area.
Since this information was given to the preparers of
the Environmental Impact Statement the design has
changed, and fences will be provided around the entire
solids drying and distribution center.
First paragraph - Die discussion of subsurface injection
of sludge as a backup disposal method was essentially
correct at the time the EIS was prepared, but the philo-
sophy of operations of the solids reuse system has changed.
The EIS indicates that up to 10 percent of the liquid
sludge would be injected into the soil at high rates of
875 tons per hectare (390 tons per acre). It is now an-
ticipated that sludge would only be injected if for some
reason the liquid material were unacceptable for distri-
bution to the public or for drying, or if the market for
sludge reduced in the future. It appears at the present
tine that there could be an adequate market to use all
of the Metro District sludge in 198S.
This has been corrected.
EPA vlll not permit disposal ocslte except for eaergenc;
sour digester disposal and only at agronomic rates. See
Issue H-15.
p. 96
CO
00
p. 91
p. 100
p. 102
In the middle of the paragraph it is indicated that a
liquid sludge storage tank and a secondary effluent storage
tank would be part of the on-site control complex at the
solids drying and distribution center. Again, while at
the time the EIS was prepared the need for liquid sludge
and secondary effluent storage tanks was anticipated,
they are no longer needed.
It is indicated that no definite contractual arrangements
have been made for specific sludge recycling areas, it
should be pointed out that the Metro District does not
contemplate at this time entering into definite contrac-
tual arrangements for specific sludge recycling areas.
Rather, it wishes to maintain a diversity in market which
will provide the greatest opportunity for promotion of
its products.
EPA indicates that an examination of characteristics of
each sludge application sita is necessary prior to em-
barking upon a sludge application program. Such examina-
tion should include analysis of soil (C.E.C.), pH and
background heavy metals. This recommendation i3 feasible
only when dealing with extremely large areas. However,
when sludge is distributed to individual gardeners and
home owners for use on extremely small plots of ground,
this recommendation becomes inappropriate (as per the EPA
Technical Bulletin on Municipal Sludge Management).
Section entitled "Total Sludge Application Surface Rate
Limitation." The EIS uses a zinc equivalent formula
originally proposed in the reference 79 as indicated in
p. 96
p 97
p 100
p 102
This has been corrected.
While we can understand Metro's desire to maintain a di-
versity of sarkets, the lack, of any definable narket areas
has aade it difficult to assess the impacts as well as the
potential for overall success of thl6 project. EPA will
reluctantly approve this project, because It believes
that even with the lack of a proven market, the energy
efficiency and the ability of this project Co stake re-
cyclable sludge available is sufficient to go ahead with
the project.
We agree that for anall areas this nay not be necessary.
State guidelines should be followed on this point.
(Issue V-4).
EPA has recognised the United value of the zinc equivalent
approach. Specific lialtB on heavy metals are sore likely
to be set, based on cation exchange capacities of soils
(See discussion under Issues 1-1 and V~l).
Continued next page
-------
Letter #5L
continued
9
EPA Response
this section. The EPA advocated the use of the zinc
equivalent to determine the total amount of sludge that
could be applied to a given parcel of land in their
technical bulletin entitled "Technical Bulletin Muni-
cipal Sludge Management Environmental Factors," July
1975. On June 3, 1976, the EPA proposed revised guide-
lines that no longer rely on the zinc equivalent. Even
though there is much controversy surrounding the vali-
dity of the use of the zinc equivalent equation, appli-
cation of this equation in the EIS indicates that the
Metro sludge can be applied to land for an extended
period of time without detrimental effects from heavy
metals.
p. 105 and 106
Co
lO
p. 107
In the discussion of sludge recycling at Lowry Bombing ; 105,6
Range, there are several incorrect statements. EPA in-
dicates that contour strips are loaded to a maximum of
175 tons per acre and then the operation moves on to a
new tract, nils is not correct. Thirty tons of sludge
are applied annually to each acre of land at the Lowry
Bombing Range. There are no additional tracts to use.
The 175 tons per acre figure is now 205 tons per acre.
Next year it will be 235 tons per acre.
EPA also indicates that during the winter months when
land application becomes impeded by ice and snow on the
ground, the land spreading operation is temporarily re-
placed by direct dumping of sludge into pits in a manner
similar to solid waste landfilling. This is not correct.
Sludge is dumped directly onto the surface of the soil
and intermixed with dirt at five parts of dirt to one
part of sludge. No pockets of sludge are allowed to
accumulate in the Lowry operation.
EPA indicates that if the proposed sludge recycling plan P 107
is somehow aborted and if Metro Denver is also barred
from land spreading at the Lowry Bombing Range, it is
possible that sanitary landfilling would be the reason-
able alternative. Based upon the alternative study, the
next best alternative would be incineration.
This loading rate cm Lowry has been corrected,
operation has been aaended In the text.
The winter
This sentence now reflects Metro's position.
p. 109 and 111 EPA indicates in the paragraph on soil that the excavation p 109, 111 Effectively, the aoll capacity would be lost for at least
of the 240 hectares, or 600 acres, of land to five feet the life of the project. Given the disruption of the sub-
depth for the drying basins would effectively disturb all soil layers, it is difficult to predict whether the soil
of the soil in a large area, and thus an irretrievable could be returned to its former capclty.
loss of the soil resource from the site would occur.
Sludge has long been noted for its ability to develop
soils in waste areas, strip mines, etc. Therefore,
through the use of sludge on this area, the soil resource
would not be irretrievably lost.
Continued next page
-------
10
EPA Response
p. 111
Letter #51,
continued
p. 116
-p»
o
p. 116
EPA Indicates that monitoring of leachate water quality p 111
and movement rates will be necessary whether or not
basins are lined. The District currently anticipates
a comprehensive joint ground water monitoring program
with the U.S. Geological Survey at the 2,000 acre site;
a comprehensive program similar to the one which has
recently been completed at the Lowry Bombing Range. It
is the intent of this joint effort to begin monitoring
of ground water quality prior to the implementing of
the drying/distribution facilities operation, and to con-
tinue to monitor the effect which this system operation
will have on ground water quality i'\ the area. EPA fur-
ther states that the rate of movement would be slow; it
would take 20 to 100 years for the water from the basins
to reach the ground water table.
EPA indicates that public access to the drying beds should P 116
be curtailed while the sludge is drying and special peri-
odic medical examinations and preventive treatment by
qualified physicians should be made available to project
personnel and consumers who come to the site to collect
sludge. The Metro District has been in operation for 10
years and literally hundreds of its employees have been
in direct contact with raw sludges, both primary and se-
condary, and there has not been a reported case of disease
being transmitted as a result of their exposure. Recog-
nizing further that the anaerobic digestion of sludge is
known to be an effective means of destroying pathogen and
other organisms in raw sludge, it would appear that such
a recommendation would be unnecessary.
Second paragraph - There is a statement in this paragraph P I16
that indicates that the run-off impoundments will be 50
feet above the water table. Field investigations indi-
cated that the ground water table is more than 100 feet
below the surface. Therefore, the impoundments will be
more than 100 feet above the water table.
This is still EPA'a position, thst monitoring will be re-
quired, along with lining of the basins. The soil per-
meabilities have been modified baaed on data from the
Geotechnical Report (Issues II-l and II-2).
Metro, however, does plan to fence the entire site; admit-
tedly , there are no documented cases of disease trans-
mission from this operation.
This has been changed; also it is expressed In terms of
the existing water table, since the table could be modified
radically after Metro operation.
p. 119
p. 120
EPA states that an emission permit is required from the p 119
Air Pollution Control Division of the Colorado Department
of Health under regulation Ho. 2 promulgated by the Colo-
rado Air Pollution Control Commission. Included in this
permit would be a definite plan for the control of odor
emissions. In addition, a complete inventory of quanti-
ties and rates of emission is required for all odorous
compounds being emitted from the site. Based upon the
experience of the District in the utilization of anaero-
bically digested sludge, there has not been any problem
with odors as a result of anaerobically digested sludge.
Paragraph 4 - The last sentence in this paragraph states p 120
that during digester malfunctions severe odor problems
The Air Pollution Control Division will have to aBseas the
odor potential from this type of operation in their permit
process.
This has been corrected.
Continued next page
-------
Letter #51.
continued
11
EPA Response
p. 128
p. 136
p. 138
p. 141
p. 141
may be expected at the drying and distribution center
if sludge were to be pumped to the site. Little or no
odor problems would occur at the site even if sour sludge
were pumped to the site under such conditions because
the sludge would be directly incorporated and would not
be exposed to the atmosphere.
EPA indicates that unpaved sections of roadway on Held P 128
County Road 30, for example, can lead to dust problems
under conditions of heavy traffic. Because many areas
in which deliveries will occur are under jurisdiction of
an air pollution control district, Colorado's fugitive
dust law will apply, requiring a dust abatement plan to
be filed prior to the start of deliveries over unpaved
roads (ref. 104).
Figure 16 - This comment is general for the whole EIS, P 136
not only specific to Figure 16. It appears as though
EPA is placing far too much significance on negative im-
pacts to ground water quality due to leaching from the
drying basins. With many years before the leachate will
reach the ground water, if ever, and with little or no
information of the possible effects on the ground water
due to the leachate, the impact placed on this item in
the EIS seems out of balance with the potential benefit
to be received from the solids reuse project and the ne-
gative impacts of not proceeding with the project.
Figure 17 - Both this figure and Figure 16 contain ambi- p 138
guity. For example, in Figure 17 under the impact para-
meter "aesthetics" it is indicated that there will be a
low negative impact if sludge is to be used on city parks,
however, there will be a high beneficial impact on aes-
thetics if the sludge is used on a mine spoil site. Pre-
sumably, the reason for the high beneficial impact for
the mine spoil site is the result of the lush vegetation
that would be grown on the mine spoils. Obviously, use
of sludge on city parks will result in lush vegetation
in the city parks. This, therefore, should also be a be-
neficial impact. This same comment applies to the use
of sludge on home ornamental gardens or edible plants.
The first sentence of the last paragraph is misleading. p 141
It tends to indicate that concentrations of Cd are greater
than Cu or Zn, which is not true.
The sentence that refers to 1 percent of Cd to Zn concen- P 141
tration is misleading. There is recent evidence that would
indicate that Zn does not affect Cd uptake into plant tis-
sues .
We are not sure whether
this neaoE Metro will have to do the dust abating on un-
paved roads or not.
We have taken pales to point out that this display of
impacts cannot be sumated; the number of negative Impacts
tends to outweigh the positive ones because the National
Environmental Policy Act requires a closer look at adverse
impacts than positive ones. Each negative Impact is singled
out for discussion. Its importance can vary from an Intense
but small area Impact (such as site soli loss) to one of
potential broad impact (such a6 the benefits of recycling
Bludge nutrients). Therefore it is not intended as an
overall evaluation, simply a display for rating the im-
portance of each impact discussed. Mitigation can also
play a role in reducing some of the negative aspects.
There is a problem here Df the subjectivity of the observer
in assessing impacts on aesthetics. Actually a more real-
istic rating might say that the effect of sludge applica-
tions on parks runs the gamut of a very negative impact
on some persons who object to the public use of sludge to
a highly positive impact as a result of the ornamentals
grovn. In any case, we rate the importance of the impact
only as "low". Incidentally, these Surinary Comparison
figures have been updated to reflect EPA's latest appraisal.
This has been amended.
See discussions under Issues 1-1 and V-l.
Continued next page
-------
12
EPA Response
p. 143
Letter §5L
continued
144
p. 144
-c*
r-o
p. 145
EPA makes the statement that if sludge is used to fer- p U3
tilize crops or home garden vegetables, which will be
eaten raw within the first year of application, adverse
health impacts will result. It should be pointed out
that for many years individuals have been utilizing
anaerobically digested sewage sludge on vegetables to
be eaten raw and no adverse impact has resulted. This
statement would more appropriately read ... "if sludge
is used to fertilize crops or home garden vegetables,
which will be eaten raw within the first year of appli-
cation, adverse health impacts may result" (ref. page 14;
EPA indicates that if a two-year drying period is insti- p 144
tuted it will ensure that no significant impacts will
result from park application of sludge. This safety
measure will be necessary because particles of sludge
will probably be ingested by some picnickers and children
playing in the dirt, etc. The two-year drying period is
inconsistent with statments made on page 113. EPA indi-
cates that long-term storage of sludge is an effective
reducer of pathogenic organisms (ref. 82). Storage of
liquid digested sludge for sixty days at 20 C (68 F) or
120 days at 4 C (40 F) has been reported to be a success-
ful pathogen reduction measure (ref. 79) . Based on this
statement, the two-year storage time for pathogen destruc-
tion is excessive. (Also read page 143, Public Health.)
EPA states that potential pollution of groundwater will p 144
not pose a significant health hazard. The primary chem-
ical constituent of concern is nitrate. Nitrate levels
of 4S parts per million measured as nitrate in drinking
water are considered to be harmful to infants (ref. 112).
However, as indicated below under "Water Quality", ground-
water contamination under most land recycling schemes would
be less than, or the same as, from the use of commercial
fertilizer. This statement could also be appropriate for
all other consideration of nitrate pollution of the ground
water where sludge is used in the place of commercial
fertilizer.
Last paragraph - It is indicated in this paragraph that
application of sludge to city parks will result in nitrate
leaching to the ground water in about 20 to 100 years.
Further, it is stated that this leaching rate may be in-
creased because of past applications of commercial ferti-
lizers which presumably are high in nitrates. Concern
with nitrate leaching to the ground water due to sludge
application is puzzling, especially when admittedly com-
mercial fertilizers that are higher in nitrates than
sludge are also potentially causing groundwater pollution
problems and yet little is done to curtail the use of com-
mercial fertilizers for this same reason.
This has been amended.
145
Although the methods on page 113 are stated to be effective
pathogen reducing mechanisms, they are no guarantee against
survival of the organisms liite Ascaris that can survive for
longer periods. We believe that general approach suggested
at the end of the discussion on Pathogens on page 144
is still valid: ". . as the level of human contact becomes
more probable for each use (dry farms, irrigated farms,
home gardens, vegetable crops, in increasing order), re-
quired length of storage time in the drying and stockpile
areas should be increased."
EPA recommendations for pathogen control are found in the
discussion under V-l, V-4, and Appendix A of this document.
We agree.
We agr*
Continued next page
-------
Letter #51,
continued
p. 147
p. 166
OJ
p. 167
13
EPA indicates that if large numbers of home owners and
gardeners adopt sludge amended practices, water pollu-
tion hazards on a large scale will be inevitable. Orna-
nental plants and vegetables are both typically heavily
irrigated and often over irrigated, causing both deep
seepage into the ground water reservoir and run-off
toward surface streams on a regular basis. Opportunities
for improperly high application rates and consequent
degradation of water supplies are thus abundant in this
type of recycling of sludge. In this case, EPA's state-
ment should indicate that ground water contamination
under most land recycling schemes would be less than or
the same as from the use of commercial fertilizers.
Another appropriate factor is that small quantities of
this valuable resource would be distributed over many
acres within the urban community, thus reducing the total
impact of ground water and surface water contamination.
This page discussed the impacts of subsurface injection
of liquid sludge at the drying and distribution center.
When the project was initially conceived, a 60-acre sub-
surface injection area was to be used for that period
of time until a sludge market could be developed. It
was not felt, however, that this 60 acres could be used
for long-term use for disposal of the sludge. Because
a significant market for the sludge has developed in the
past year, the present concept is not to use this area
as a disposal area, but more of a research demonstration
area similar to the rest of the buffer area surrounding
the drying basins.
EPA indicates that the disposal of sludge to the Lowry
Bombing Range represents the no-action alternative and
would be continued if agricultural reuse of sludge is
not implemented. Once again, reference should be made
to the alternative study; if beneficial reuse concept
is not adopted, incineration would be the next best al-
ternative.
EPA Response
p 1*7
1M
p 167
This has been modified.
EPA will not permit Che use of the B-2 site as a "disposal*'
area. Agronomic rates oust be met for sludge injection.
EPA would at this time recommend same form of sludge re-
cycling centering around the Lowry site, if the Metro pro-
posal should falter. We do recognize that Metro's position
is that they favor incineration as a project alternative.
EPA does not feel that a resolution of this difference of
opinion is necessary at this time.
p. 170
p. 171
EPA states the organic matter contents of the soil will p 170
rise to about 1.75% in the top 15 centimeters (6") of
the soil at the current 400 metric tons per hectare (175
tons per acre) total loadings. It should be pointed out
that the total loadings to the Lowry site currently ex-
ceed 175 tons per acre. Each acre of the available land
at Lowry is loaded at 30 dry tons per acre per yearr and
will continue to be loaded at that rate each year until
the new system is implemented.
EPA indicates that the preliminary raw data from the sur- p 171
face water analysis at Lowry are still not enough to help
set actual impacts. It can be summarized from th? trends
This has been noted. Metro*s present operation at cbc
240 ha [600 seres] Lowry site should be characterized as
a disposal system, not a beneficial recycling system, sines
the land is dedicated for the use of sludge disposal (as
agreed to by the City of Denver) and eventually as s land-
fill. Therefore loading rates of sludge sre not limited
by agronomic factors.
Ve would agrse with this general assessment of pollution
at the Lowry site. See the discussion on Issue 111-1.
Continued next page
-------
14
Letter #51.
continued
p. 172
P. 175
p. 176
-P»
p. 177
p. 181
p. 182
p. 182
that nitrate/nitrogen is already finding its way into
the surface water and the shallower ground water reser-
voirs. Based on the information which the District has
currently concerning the ground water project, there is
insignificant ground water pollution at Lowry. Catch
basins are subject to run-off, however, cattle wade and
defecate into these basins which accounts for the high
nitrate content.
Chaney's more recent work shows that zinc does not limit
cadmium uptake.
EPA indicates that under the present operations at Lowry
with largely undigested sludge, odors are easily per-
ceived at close proximity to the application areas, es-
pecially when digester problems are encountered. The
last part of this statement reads incorrectly because
the District encounters no digester problems with no
digesters in operation.
EPA indicates that should the project not be implemented,
truck traffic to and from the Metro Denver central plant
facility and the Lowry Bombing Range will continue at a
rate of 35-40 truck trips per day until such time that
the land can no longer accommodate additional increments
of heavy metals associated with the Metro Denver sewage
sludge. Theoretically, the Lowry site is designated as
a solids waste landfill, and the soil could thus accommodate
heavy metals for eternity, however, there would be no pro-
duction of vegetation on this 3ite.
Cadmium is not the most mobile of heavy metals.
EPA indicates that lining the bottom and the sides of
basins with impermeable materials is the only fully ef-
fective way to mitigate nitrate and other salt accumu-
lations in the ground water. This has not been substan-
tiated as mentioned previously.
Section entitled "Surface VJater Pollution From Experimental
Plots." This item need not be listed here as a negative
impact with recommended mitigative measures. As mentioned
previously in the EIS, surface water will be impounded and
tested to ensure safety from a public health standpoint
prior to release to natural drainage-ways. Listing of
this item here gives the impression that in the proposed
solids reuse system there is no provision for run-off
collection and pollution abatement to surface waters.
EPA indicated that a qualified entomologist should be
retained at the early stage of the full utilization of
the drying basins to identify species of insects coloni-
zing the basins and control measures defined through the
EPA Response
p 172
P 179
p. 176
177
181
p 182
p 182
This consideration has been reflecced in Che
is discussed in Issue V-l.
This has been changM.
:inal EIS and
EPA afrets.
Cadmium Is one of the more mobile heavy metals.
The wording has been changed; however, the basic position
that lining is necessary is not changed.
This has been corrected.
It is Important that the Metro District does develop an
adequate plan to minimize insect and rodent vectors on
the B-2 site. EPA will insist that Metro report the
development of such an insect control plan before construc-
tion approval is given*
Continued next page
-------
IS
EPA Response
identification process should be implemented. This
expertise should be provided for during the early
stages and the full utilization of the drying basin.
Over the past several years the Metro District has
utilized the Colorado State Health Department's Vector
Control Division, specifically Mr. Ted Davis, to assist
with all vector problems. In discussions with Mr.
Davis, he indicated that he would be willing to assist
during the initial stages of the operation.
Section entitled "Land Application in Sludge Recycling p 183 EPA will continue to encourage the District to proceed in
Areas." It is recommended in this section that the this Banner.
most important overall mitigative measure for negative
impacts of land application of sludge would be to limit
the land application, in the initial years, to sites
with the least area of adverse impacts. Such sites would
include mine spoil sites and sod farms. It appears that
with this philosophy the District's solids reuse system
may be forced into a self-destruct situation. Unless
many mining companies other than Climax Molybdenum were
to undertake mine tailings reclamation and unless more
sod farms were to be established in the Metro Denver
area, the District would have a difficult .tine marketing
the sludge. By suggesting that application to irrigated
farms be limited during the initial years of the project
a considerable potential market for the sludge would be
eliminated.
EPA indicates that removal or reduction of sources con- p 183 EPA does not nov encourage this form of control in the
tributing heavy metals to the wastewater management sys- Metro situation, where other factors such as soil pH
tem will mitigate many of the adverse impacts on soils, predoninate.
plants, animals and the food chain. This can be done by
promulgation of a special wastewater ordinance setting
tolerable limits on concentrations of various substances
entering the sewer system, thus forcing industries to
adopt inplant measures to curb discharge of heavy metals.
Regulations now exist within the District Act to control
toxic substances which could effect the end use of sewage
sludge.
EPA indicates that, control of the cadmium/zinc ratio is
another important mitigating measure. If this ratio is
kept below 1%, acceptability of the sludge for use on
feed crops and foods will be greatly enhanced through the
plant yield reduction affected by zinc long before either
element accumulates in toxic concentration. The problem
with the Metro District sludge is that it is low in metals
as reported in the body of the EIS. - The only reali'stic
approach perhaps to resolve this problem is to add addi-
tional zinc to the sludge prior to application. The Cd/Zn
ratio is ineffective. Zn does not affect Cd uptake into
plants.
p 183 EPA does not encourage the use of the Cd/Zn as the manage-
ment control method In light of recent research findings.
The management procedures with respect to heavy metals is
discussed in Issues 1-1 and V-l.
Continued next page
-------
16
EPA Response
p. 184
Letter $51,
continued
p. 184
p. 184
4*
CT>
EPS indicates that: record keeping, inspection of sludge
application operations on individual sites and monitoring
of environmental parameters are functions which must be
carried out by the District or another responsible agency,
and close cooperation with individual fanners and opera-
tors. These functions will prevent inadvertant aggrava-
tion of impacts by excessive non-uniform or careless ap-
plication of sludge and will mitigate the adverse impacts.
It may be necessary to obtain binding agreements with re-
cipients of sludge to permit inspection and monitoring
and to provide for cessation of sludge supply in case of
noncompliance with recommended management practices. It
should be pointed out that the fanner today is a highly
technically competent person. It is inconceivable that
fanners would haphazardly apply sludge to their land as
it is inconceivable that farmers would haphazardly apply
other types of commercial fertilizers. The cost impacts
are of such significance today that this situation will
mitigate itself.
As stated in previous sections, the soil should be main-
tained at a minimum pH of 6.5. Calcium in itself does
not affect heavy metal uptake. Where necessary, mitiga-
tive measures should be used to raise the soil pH where
it is below 6.5.
Although heavy metals from plant materials do accumulate
in kidneys and livers of animals, there has bean no do-
cumented case where concentrations of these metals reached
a level which would be harmful to humans. Metro studies
would tend to indicate that older animals having never
been exposed to sludge have higher levels of heavy metals
in kidney and liver than younger animals fed sludge di-
rectly. Without any evidence or data of any sort, it is
improper to make this kind of recommendation.
p 184 Metro should, however, provide guidance Co farmers by
recooaiend ing rates and proper management techniques. Al-
though nose of today's fanaers are quite sophisticated,
the District should not expect the farmer to have full
knowledge of all the parameters involved in proper sludge
management. The record-keeping and inspection functions
provided by the District should also serve as an educa-
tional process on the benefits and limitations of sludge
use for sludge users.
p 184 This has been corrected. It is the carbonate, not the
calcium that affects heavy metal availability through
control of pH.
p 1B4 This recomendation lies in the area of possibility,
should research so indicate a concentrating effect in
livestock livers and kidneys to levels considered harmful
to humans.
p. 185
p. 185
Section entitled "Nitrate Pollution of Ground Water, Es- p 185
pecially in Irrigated Farms, Sod Farms, Home Gardens,
City Parks." This section indicates that the preparers
of the EIS feel that a potential user of the sludge would
be careless or wasteful in the use of this material. Most
users, particularly farmers, would likely be judicious in
the use of sludge as a fertilizer just as they are with
conmercially available synthetic fertilizers. Over ap-
plication of this material would not only be wasteful of
the material itself, but also costly to the farmer. Con-
sequently, it is doubtful that the individual farm user
would inadvertently apply this material in heavy concen-
trations . p 185
EPA indicates in the section on nitrate pollution and
eutrophication of lakes and other water bodies that the
use of liquid sludge injectors applying sludge at greater
Continued next page
We are somewhat concerned about overzealous use of the
material. The philosophy, "if a little bit is good,
a lot must be becter", would aot work in this situation.
We can agree, however, that most farmers would be mostly
concerned about keeping operating costs down, and hence
avoid overuse.
We have deleted this reconnendation, although in specific
cases, it might still apply. If sludge were to be used
in proximity to a lake or stream, and no tailwater control
on the land were practiced, a judicious use of sludge in-
jection would probably be preferred over dried 3ludge.
We agree that the potential for groundwater contamination
might be somewhat greater with this approach* particularly
if the sludge were Injected below the plane root zone*
-------
Letter #51,
continued
p. 185
p. 186
-F*
^1
p. 187
p. 187
p. 188
p. 192
EPA Response
depth should be preferred over application of dried
sludge. The District recognized the potential for
liquid sludge, however, it believes that the most ac-
ceptable method for applying sludge to land is in the
dried form. Care must be used with liquid sludge in-
jectors sludge is not injected at a depth where the
nutrients are not readily available to the plants. In
this case, nitrogen movement downward would not be
available for growing, and therefore, a waste of the
valuable resource.
Section entitled "Exposure of Humans to Viable Pathogens P- 183
and Parasites." This section suggests that sludge should
be air dried for at least two years prior to use in land
application operations in order to reduce the numbers of
viable pathogens. Later on in this statement, it suggests
that an alternative method of pathogen reduction is to
store liquid sludge for 60 days at 20 C or 120 days at
4 C. It seems that if storage of liquid sludge for 120
days at 4 C is adequate to reduce the numbers of visible
pathogens then storage of dried sludge for two years is
far too conservative.
EPA indicates that current research Shows preliminary P- 186 EPA agrees chat this method of disinfection is not feasible
promise in the use of high energy electrons for disin- at present,
fection of sludge passing in a thin stream in a specially
adapted process, the feasibility of use of these and
other means of pathogen destruction should be continually
considered for application and use. The Metro District
is currently following the innovative technologies which
are being developed in the industry, however, after re-
cent communications with the manufacturers of high energy
electrons disinfection devices it does not appear to be
economically feasible at this time.
The two year period mentioned Includes both drying and
storage tiae, and Is Intended for the aost sensitive use
In terms of public health, na*ely individual hone garden
use. For all others uses where human contact is such leas,
a one-year drying and storage tlae it adequate.
EPA has indicated that in the initial toxicity of liquid P 187
sludge to seeds and young plants, the use of special in-
jectors applying the material in separate bands deep into
the soil will help in the mitigation of toxicity to seed
and young plants. One should caution about the deep in-
corporation approach; sludge applied too deeply in the soil
will not provide the nutrients to support the plant's growth.
This has been amended.
The paragraph on heavy metals accumulation in soils, plants,
animals, and food chain is difficult to understand.
P 187
This has been changed.
The second paragraph on initial toxicity of liquid sludge p 188
to seed and young plants is redundant, the same subject
is covered on page 187.
Section entitled "Destruction of Wildlife Habitat." It P 192
is suggested in this section that most of tha 2,000 acre
drying and distribution site would be irretrievably lost
Continued next page
True.
EPA would like to discuss with Metro the proposed status
for the "relictual prairie" area identified in the facil-
ity plan environmental assessment. Perhaps Metro could
create a more productive wildlife area through use of sludge
application.
-------
18
Letter #51,
continued
as a wildlife habitat. Because of the intense farming
operations presently in effect at the site of the drying
and distribution center, it is likely that the wildlife
habitat has already been destroyed or at least greatly
disturbed.
p. 192
Salt accumulations from the utilization of sludges should
be no worse than those effects from using commercial fer-
tilizers or manure from cattle. If agricultural produc-
tion is to remain at its present level or increase, salts
(which are plant nutrients) will have to be added to the
soil, thus, the accumulation of salts will occur regard-
less of the use of sludge.
p. 193
No danger or hazard has been demonstrated. In fact, where
studies have been conducted (notably Australia) where
cattle are exposed to raw untreated sewage, the animals
have shown no disease problems or accumulations of heavy
metals. At the present time these dangers are speculative,
not confirmed.
p. 194
p. 194
-p»
CO
p. 195
Soil profiles will be obliterated, but the insinuation that
these soils will permanently lose their agricultural char-
acteristics is erroneous.
The assumption that unlined basins or fields where sludge
is used will lead to contaminated ground water is not
necessarily true. Most of .the South Platte River basin
and indeed much of the ground water in agricultural a-eas
of Colorado is already polluted to a greater extent than
leachate from the drying basins, or sludged fields, where
sludge is applied properly. It is necessary to make an
assessment of the ground water quality in a given region
before stating categorically that ground water pollution
will occur.
Soils are dynamic environments which maintain equilibrium
with many solution and solid phases (particularly where
metals are concerned). The assumption that soils vjill be
a repository for heavy metals is true, but to conclude
that this is an adverse effect is false.
p. 196
Iron is never toxic to plants,
ment.
at least in a soil environ-
WEK/j
9/7/76
EPA Response
P 192
p 193
p 194
p 194
p. 19 5
p. 196
It is true chat most solid fertilizers are applied through the
use of ionic species [e.g. (NH4>2SC>4, NaNOj, Ca3 (P04>2J and
that use of the nutrient species still leaves the ionic resi-
dues in the soil. The chief Issue is whether sludge contains
excess salts that have no nutrient value. This issue is
discussed under Issue V-l. _
CPA still feels that this practice represents a potential
hazard, as does the FDA (see Letter #37) and Che Colorado
Department of Agriculture (see Letter #24)*
EPA maintains chat soil productivity will be lost and that
reclaaatlon of the soil profile to its present state is
problematic.
EPA agrees that sludge applications on fields in agronomic
amounts poses no greater threat than commercial fertilizers
The drying basins however, vill be receiving 1900 to 3800
o3/day [.5 to 1 mgd] of nutrient and salt laden materials.
The discussion referred to here was merely pointing out
some of the adverse effects which may occur with long-
term use of sludge. Addition of heavy metals in quanti-
ties higher than soils can tolerate is an adverse inpacc.
Monitoring sludge amended soils for metals at five year
intervals will detect increasing concentrations soon
enough tc cease sludge application before the metals reach
unacceptable levels.
EPA agrees that iron will not present any problerr for
sludge application.
-------
w
-------
This section presents the detailed discussions
of the important issues raised by the letters and
comments received during the review of the draft EIS.
The issues are broken down into five categories,
namely (1) pipeline and plant issues; (2) site-
specific issues; (3) continuation of the present
operation; (4) alternatives; and (5) constraints
to sludge use offsite. Each of the various issues
are discussed under the appropriate category. Where
an issue is also addressed in Volume I, a reference
is made to the section in which it may be found in
that volume.
-------
SECTION C
DETAILED ISSUES DISCUSSIONS
ISSUE I
PLANT OPERATION AND PIPELINE IMPACTS
ISSUE 1-1. What kind of source control at the Metro Plant is needed
to limit concentrations of heavy metals and persistent orqanics such
as polychlorinated biphen.yls (PCB's) and pesticides for sludge appli-
cations to land?
This issue was raised by EPA in the draft EIS and subsequently by
many others. In order to gain a perspective on the issue, it is first
necessary to look at the problem of heavy metals and persistent organ-
ics. What are the present concentrations in sludge, and what levels
of various metals are considered hazardous? Finally, what is Metro
and EPA doing to control the levels of these sludge contaminants?
Heavy-metal buildup in the soils and its concentration in the food
chain is a major concern in the use of sludge on cronland. This prob-
lem has received much attention recently as it oresents one of the maj-
or potential hazards in the use of sludge on soils. EPA recently re-
leased an appraisal of the problem written by a task force of experts
in the field (the CAST study, Reference 38). A study of the soils in
the area, and a test of the impact of Denver liquid sludge applied to
wheat grown at the Watkins Test Site in Adams County have been carried
out (References 2 and 3). This information allows an appraisal of
the potential hazards expected to be encountered with the application
of dried sludge to crop land, which is discussed in more detail in
Issue V-l.
Metro routinely analyzes its sludge for Manganese (Mn), Zinc (Zn),
Copper (Cu), Nickel (Ni), Cadmium (Cd), and Lead (Pb). The average
heavy metal content of Denver sludge determined by Metro for the year
1975 is presented in Table 1. In addition, the results for Metro Den-
ver sludge of an analysis carried out in 1972-1973 on sludges from 16
American cities are also presented for comparison (Reference 4). All
of these metals have been identified as posing a potentially serious
hazard to plants or animals except Mn (Reference 5). In addition, the
149
-------
concentrations of Molybdenum (Mo), Arsenic (As), Mercury (Hg), and Se-
lenium (Se) were analyzed in Denver Northside anaerobically digested
primary sludge. These concentrations, as well as those reported in
Reference 4 for Metro's sludge, are presented in Table 2 and represent
the average from two to three different grab samples.
Table 1. AVERAGE HEAVY METAL CONTENT OF METRO DENVER SEWAGE
SLUDGE FOR THE YEAR 1975
SIudge
mq/kq Dry Weight
Type
Mn
Zn
Cu
Ni
Cd
Pb
Polymer treated
anaerobically
digested primary
sludge.'
186*69
1140-350
978^245
260-90
23-7.5
600^97
85% Waste acti-
vated & 15% Raw
primary treated,
with FeCl^+lime
277-61
1075-196
740-204
192-48
19-6.9
312-68
Waste activated
treated with
FeCl2+1ime^
224
2860
1370
562
46.1
1011
^Source:. MDSDD #1.
2
Source: Reference 4. The exact source of sludge in this study was
not given. A single sample was provided by MDSDD #1 from its central
plant and is presumably similar to the waste-activated/primary mixture
above.
Table 2. HEAVY METALS CONTENT OF ANAEROBICALLY DIGESTED SEWAGE
SLUDGE
mq/kq Dry Weight
Element
Northside Primary Sludqe1 Metro Waste-Activated Sludqe*1
As
1.3
14
Hg
11
3.6
Mo
40
18.1
Se
5
3.5
^Source:
MDSDD #1.
^Source:
Reference 4.
150
-------
A comparison of the values presented by Metro with those presented
in Reference 4 show discrepancies in several metal concentrations.
In particular, the values for Zn, Cd, Pb, and Ni reported in Reference
4 are over twice as high as those reported by Metro. However, the
analyses in Reference 4 were performed in 1972-73; Metro's values
are for 1976. It would appear that the levels of trace metals in
Metro's sludge are decreasing.
The State of Colorado draft regulations on limits for heavy metal
concentrations in sludge applied to the land are presented in Table 3.
Sludges having metals within these ranges would be considered accep-
table. The draft guidelines do not have criteria for metals other
than those in Table 3.
Table 3. PROPOSED RANGES OF TRACE ELEMENT CONCENTRATIONS IN
SLUDGES APPLIED TO LAND IN THE STATE OF COLORADO
Element Range, mg/kg
Zinc
(Zn)
500-3000
Copper
(Cu)
230-1500
Lead
(Pb)
100-1500
Nickel
(Ni)
25-1000
Cadmium
(Cd)
5-30
Source: Reference 5
A comparison of the values in Table 3 with those reported by Metro
in Table 1 shows that Metro's sludge falls within the recommended limits.
If these limits are adopted and Metro's sludge continued to show the
same or lower metal content, then no further mitigative actions need
be taken.
The U. S. Food and Drug Administration recently adopted recommend-
ations for sludge use on land (Reference 6). The FDA recommends that
sludge applied to land used to grow human and animal food not contain
more than 20 ppm Cd, 1000 ppm Pb, or 10 ppm PCB's on a dry basis.
Metro's sludge has slightly more Cd and less Pb and PCB's than recom-
mended by the FDA.
A source control program will be conducted by MDSDD #1 to reduce
the quantity of metals discharged to the sewage system. A survey is
now beginning to ascertain which industries are discharging excessive
151
-------
quantities of metals to the system, and these industries will be re-
quired to pretreat their effluent to remove as much of these metals
as possible. In this way, the metal content of the sewage and sludge
will be reduced to as low a value as practical.. The U.S. Department
of Agriculture has recommended source control to reduce the heavy
metal content of wastewater sludges (Reference 7).
Until the state has adopted final regulations for sludge used on
land, Metro will be required to stockpile its sludge. These guidelines
should be adopted before Metro is ready to begin disbursing sludge to
consumers, since sludge will require a year to dry and a year of stock-
pile before release in any case. The public health, plant, soils and
long-term effects of metals in sludge applied to land are assessed in
Issue V-l.
Table 4 presents the concentrations of various pesticides, herbi-
cides and PCB's found in a one month composite sample of Metro sludge.
No guidelines have been issued to date by any agencies on tolerable
levels of pesticides or herbicides; however, the concentrations found
should pose no problem for sludge applied to land.
PCB's are reported in Table 4 as AR-1254. Other types of PCB's
were not specifically determined, but are reported as AR-1254. There-
fore, this value is representative of the total PCB concentration in
this sample of Denver sludge (Reference 8).
The 1977 amendments to the Clean Water Act considerably strengthen
the requirements for pretreatment of industrial wastes entering munici-
pal treatment systems. Under these amendments, EPA will have to es-
tablish national pretreatment standards for toxic pollutants. Indus-
trial discharges will be required to reduce these toxic pollutants us-
ing the "best available treatment economically achievable". Higher
concentrations of toxic pollutants discharged to a municipal treatment
plant would be allowed only if it can be demonstrated that such con-
centrations would not violate effluent standards if discharged directly
by the industry, and that they would not prevent proper sludge use.
Congress has thus created a mechanism that should reduce the heavy
metals and other toxic substances in sludge thereby improving its qual-
ity for agricultural use.
Sewage treatment plants like Metro's will be required to have their
National Pollutant Discharge Elimination System (NPDES) permits amended
to identify sources and amounts of industrial pollutants entering their
plants. These industries will have to comply with the pretreatment
standards. Loans from the Small Business Administration will be made
152
-------
Table 4. CONCENTRATION OF ORGANIC RESIDUES
IN METRO DENVER SEWAGE SLUDGE
(all values in ppb, dry weight basis)
Compound
Anaerobically Digested
Treated with Polymer
Waste Activated plus
Primary Treated With
FeClg and Lime
P, P ' -DDT
T*
202
P ,P' -DDE
300
94
P,P' -DDD
497
65
P,P' -BHC
16
20
Dieldrin
86
35
Hexachlorobenzene
NF**
4.9
Chlordane
1535
636
AR-1254
4252
751
0,P' -DDT
NF
NF
0,P' -DDE
NF
NF
Beta-BHC
NF
NF
Heptaclor
NF
NF
Endrin
NF
NF
Lindane
NF
NF
Heptachlor Expoxide
NF
NF
Oxychlordane
NF
NF
Mi rex
NF
NF
trans-Nonachl or
NF
NF
Aldrin
NF
NF
Methoxychlor
NF
NF
* - Trace
** - Not Found
153
-------
available to industries to help with pretreatment costs.
EPA has already begun requiring removal of known hazardous substan-
ces from industrial operations entering municipal treatment plants. For
example, EPA recently published Pretreatment Standards for Electroplating
Industries (Reference 9).
As the regulations under this act are developed, specific pre-
treatment limits will be set for Metro. Metro will be required to
submit a pre-survey report to EPA within a year identifying sources
and likely reductions available with added pretreatment (see Appendix A).
Issue 1-2. Please provide a better description of the proposed pipe-
line, routing, existing conditions and impacts along the pipeline
ri qht-of-way.
EPA was severely criticized in the draft EIS for a lack of
specific information on this issue. This section describes in more
detail the pipeline route, which is shown in Figure 1. Wherever possible
the route has been chosen to stay within established road right-of-
ways or to cross previously disturbed land. The route is as follows:
the line crosses the Metro plant site and goes through an adjacent
greenhouse/agricultural area. It passes beneath the Burlington Ditch,
following the right-of-way of the existing Sand Creek sewers, then
follows the east bank of the Burlington Ditch to 64th Avenue. The
line goes eastward along 64th Avenue to Colorado Boulevard, and
follows the west side of Colorado Boulevard to 72nd Avenue. It pro-
ceeds along 72nd Avenue to Colorado Route 2, following this right-of-way
to 92nd Avenue. It follows 92nd Avenue along the north side of the
Rocky Mountain Arsenal. The booster pump station is located just before
Potomac Avenue along this route. The line follows the continuation
of 92nd Avenue (Buckley Road) where it turns south, then continues
on 88th Avenue (Irondale Road) eastward until reaching the edge of
the Solids Drying and Distribution Site.
It is evident that the pipeline does not traverse any area which
has not already been considerably disturbed. Since most of the route
is along established road right-of-ways, no disruption of agricultural
or any other land use will be caused by the pipeline construction.
Some disruption of traffic and the usual increase in noise and dust
which accompanies any construction effort will occur during the actual
building of the pipeline.
154
-------
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-------
Issue 1-3. Will the added use of water in the offsite solids project
involve a water rights conflict and create a substantial downstream
impact?
A number of agencies (State Natural Resources Department, City
and County of Denver), felt this to be a potentially important impact.
3
The proposed project is expected to require about 4160 m /day
(1.1 mgd) of water for sludge transport and pipeline purging (Refer-
ence 26). This quantity of water will be transported to the drying
site and thus will be lost to the South Platte River. The current
sludge disposal operation uses about 490 m^/day (0.13 mgd).
This quantity of water is not unreasonable for consumption in
a sludge disposal system. It represents a small percentage (less than
one percent) of the total plant flow and its loss will have a neg-
ligible impact upon downstream users.
The Metro district treats wastewater that originates on both
the east (Platte River drainage) and the west slope (transbasin di-
versions). Both sources of water are controlled or owned primarily
by the Denver Water Board. Waters originating in the South Platte
River basin that have historically been diverted for municipal use
(through existing water rights) must be released downstream after
a single use. Recent court cases have established the rights of sub-
sequent use for waters that have been imported from other basins.
Therefore, the Denver Water Board can be considered the outright
owner of much of this western slope water. It would therefore be
within the purview of the Denver Water Board to decide how these
waters are to be managed.
EPA was particularly interested in the position that the DWB
would take regarding this project. Letter #7, from the Denver Board
of Water Commissioners, does not indicate any outstanding problems
with this project from their point of view. The letter simply in-
dicates that "the matter of use, however, is presently under review
and discussion with the Metro staff." This letter was written over
a year ago, and no change in position has been forthcoming. Given
this apparent lack of conflict, EPA can only assume that the use of
these waters are not a significant legal problem.
Issue 1-4. Will the proposed project affect historical and/or archae-
ological resources and is a survey required?
The State Archaeologist has reviewed the sludge pipeline route
and provided recommendations for protection of archaeological resources
(Reference 10). Since the surface area that the pipeline route follows
has already been seriously disturbed, no surface archaeological survey
158
-------
is required. The site B-2 has already been investigated and no sig-
nificant artifacts were uncovered. Also, most of the pipeline follows
the routes of various existing buried utility lines, so professional
archaeological monitoring during excavation is not required. Profes-
sional monitoring will be required during excavation of the route
through the plant site and up to Colorado Boulevard. The remainder
of the trenching will require "informed, faithful" monitoring by
Metro's excavation inspectors (Reference 10). Should archaeological
resources be encountered, adverse impacts must cease until EPA and
the State Archaeologist assess the cultural resource represented.
At that time appropriate mitigative measures will be taken. See
Grant Condition #2.
The State Archaeologist has presented the archaeological re-
source considerations for the sludge pipeline excavations, shown
in Figure 2. This figure shows the archaeological situation and
the appropriate measures required to ensure that destruction of
historical resources does not occur. The implementation of these
recommendations will adequately mitigate impacts to archaeological
resources during pipeline construction.
Issue 1-5. What is Metro's contingency plan for a pipeline break?
Metro has provided the following description of the pipeline
design and operating procedure:
"In general, the transport system pipelines have been designed to
be buried with a minimum of 5 feet of soil cover. This is approx-
imately 1 foot deeper than the normal design practice in the Den--
vet area for frost protection for utility pipelines. The reason
for the deeper burial of the transport system pipelines was to
locate the pipes so that they were relatively free from future
disturbance during repairs on other utility pipelines or buried
cables. The pipelines, of which there are two (a 10-inch and a
12-inch), have been designed with four cross-over valves to al-
low alternate use of sections of the pipelines if for some rea-
son any one of the pipelines is unusable along any given stretch.
Also, there are 18 blowoff valves along the pipelines for use in
cleaning the pipelines of accumulated solid materials that may
accumulate at the deeper points of the pipeline. There is an
in-line valve at each blowoff to prevent flow in the pipeline
downstream of the blowoff valves. Either the in-line valves
of the blowoff valves or the crossover valves would be used in
the case of a pipeline rupture. In-line valves located at the
crossovers or the blowoffs would be closed to prevent back-
drainage of the material in the pipeline out of the ruptured section
of the pipe.
159
-------
ARCHAEOLOGICAL RESOURCE CONSIDERATIONS FOR THE PIPELINE EXCAVATIONS
PLANT SITE SLUDGE LINE
Plant Site to Colorado Boulevard
DRYING AND
DISTRIBUTION
Colorado Boulevard! to Site B-2
SITE 1
GENERAL SITUATION
Apparently
previously and
extensively
disturbed
Generally disturbed
line due to alignrae
corridors
along actual sludge
,nt with existing
Largely
undisturbed
GENERAL ARCHAEOLOGICAL
RESOURCES
Historical:
Prehistorical:
possible
likely
possible
likely
possible
unlikely
none]
none
STATE ARCHAEOLOGISTS'
RECOMMENDATIONS FOR
FOR ACTUAL EXCAVATION
Monitor w
archaeol
ith qualified
ogist/historian
l
Monitor by EPA a
excavation insp
nd Denver Metro
ectors
j
cn
o
^ Survey has revealed no resources.
Source: State of Colorado, State Archaeologist
-------
Although the production of H2S is definitely a product of
anaerobic digestion, the amount of this gas produced can be min-
imized by proper operation of the anaerobic digesters at the Central
Plant. Such operation would include maintenance of an adequate
alkalinity level in the digesters to minimize the amount of free
hydrogen ions and thus minimize the amount of H2S produced. The
transport system includes 21 combination air release valves (CARV).
These valves have the ability to automatically release small accu-
mulations of gas that may form in the pipeline at the high spots
along the pipeline profile. The amount of this gas released at
any one time will be small. Because relatively small quantities
of gas will be released, no facilities for odor scrubbing or after-
burning of any flammable gasses are provided. The amounts of
these grasses would be too small to justify costly scrubbing or
after-burning equipment at 21 locations."
In the event of a rupture in one pipeline, sludge would be
pumped through the other pipeline until repairs were made. If
both pipelines were ruptured in the same section, sludge transport
would have to be temporarily halted until repairs were made. The
main and booster pump stations are both equipped with four sludge
pumps, of which two at each station are required at any time to
pump sludge (Reference 46). This allows any two of the four pumps
at each station to be inoperable without interrupting sludge flow.
This information will be developed into a contingency plan
in the Operations and Maintenance Manual for this project. See
Grant condition 3.a.
Issue 1-6. How would Denver Northside Treatment Plant sludge be
handled in the Metro offsite solids proposal?
This issue was by and large raised by the City and County of
Denver in its comments on the draft EIS (see Letter #33). EPA is
very much interested in the resolution of this issue, because it has
important implications for Colorado wastewater treatment funding. To
better understand the resolution of this issue, background information
will be presented below concerning current operations at the Northside
Plant in conjunction with the Metro plant, and a discussion of how the
Northside operation would relate to the proposed Metro solids recycling
plan.
The Denver Northside Plant (DNS), which is owned and operated by
the City and County of Denver, is a 400,000 m3/day (106 mgd) primary
treatment plant located about 2.4 km (1.5 miles) upstream of the Metro
plant in North Denver. The plant handles raw wastewater flows from
the City of Denver as well as from some special districts surrounding
161
-------
Denver. The Northside plant provides primary treatment only; the pri-
mary effluent is discharged through a 760,000 m3/day (200 mgd) pipe-
line to the Metro Central plant for secondary treatment, as shown in
Figure 3. Primary sludge withdrawn at the Northside plant is anaer-
obically digested onsite. Northside's digesters were recently upgraded
under an EPA grant and have a total capacity of 36,000 m3 [9.6 mil gal]
(Reference 11). This volume is capable of processing sludge from a
470,000 to 510,000 m3/day [125 to 135 mgd] primary wastewater plant
(Reference 11). There is, therefore, considerable excess anaerobic di-
gestion capacity at the Northside plant.
Before 1965, the Northside plant handled its processed anaerobic
sludge in drying beds located at the plant site. The City stopped the
use of these drying beds at the insistence of the Colorado Department
of Health because of the groundwater pollution resulting from leaching
of nitrates into the alluvium and eventually the South Platte River.
The construction of the Metro Central plant in 1965 provided an accept-
able alternative for disposal of Northside-generated sludge. Two
eight-inch pipelines were constructed from the Northside plant to the
Metro central plant for transport of Northside digested sludge to Metro
for further treatment. The contract between the Metro District and the
City calls for at least a 5 percent solids sludge to be pumped to Metro
at Metro's expense. This means that the anaerobic sludge must first be
settled and decanted, with the supernatant being returned to the primary
treatment headworks.
The City and County of Denver Parks Department had historically
used Denver anaerobically digested sludge as a soil conditioner in
City-owned parks and golf courses. When the Metro Central plant was
constructed, sludge incinerator-dryers were installed, presumably in
part to provide a stabilized dried sludge for use by the Denver Parks
Department. Up to 4100 dry metric tons/year [4500 dry tons/year] were
to be used. Subsequent operational failures of the dryer/incinerators
led to their abandonment in 1971. The present system of disposal by
truck hauling vacuum filtered sludge to a portion of the Lowry Bombing
Range (owned by the City of Denver) was implemented at this time.
The Metro Central plant currently handles all sludges generated at
both the Metro plant and from Northside by vacuum filtration and truck
hauling to the Lowry landspreading site. The relative amounts of sludge
from the different sources that were treated by Metro in 1976 are given
in Table 5.
Northside sludge constitutes only about 13 percent of the total
Metro sludge load by weight and about 11 percent by volume. More im-
portantly, digested primary sludge dewaters quite well. Metro's cost
of sludge operation is very sensitive to two factors: 1) the cost of
chemicals to aid in sludge dewatering and 2) the degree to which the
162
-------
FIGURE 3
DNS Wastewater Influent
Decant
DENVER
NORTHSIDE
Anaerobic
Digestion
' Primary
iClarif iers
PLANT (DNS)
200 mgd capacity
effluent line
2-8" sludge
pipelines
Metro Wastewater Influent
METROPOLITAN
' Primary \
.Clarif iers.
DENVER
SEWAGE
Secondary
Activated
Sludge Basins
DISPOSAL
DISTRICT #1
Floatation
Concentration
PLANT
Secondary \
Clarif iers/
Sludge Mix
and Storage
Chlorination
Vacuum Filtration
Wastewater Discharge to the
Landfill Disposal at
Lowry Bombing Range South Platte River
—~ Solids Flows
~ Liquid Flows
SCHEMATIC DIAGRAM OF EXISTING DENVER
NORTHSIDE AND METRO DENVER TREATMENT
PLANT PRINCIPAL UNITS AND FLOWS
163
-------
Table 5. QUANTITIES OF SLUDGE TREATED BY METRO IN 1976
Weiaht Drv Solids
Volume of Water
SfTOtal
Sludqe Origin
rat/day
tons/day
mt/vr
tons/yr
m-Vday
qal/dav
Solids
DNS digested
primary
12.1
13.3
4,427
4,870
175
46,580
5.0
Metro raw
primary
33.1
36.4
12,950
14,250
467
123,290
7.1
Metro raw
concentrated
activated
sludge
39.0
42.9
14,410
15,850
881
232,880
4.4
Total
84.2
92.6
31,790
34,970
1,524
402,750
-
sludge can be dewatered. The digested Northside sludge has at times
been blended with other Metro sludges because it acts like a sludge con-
ditioner and reduces the amount of chemicals required for dewatering.
Metro estimated that a cost savings of $2.00 per dry ton was achieved
on sludge processed at Metro by blending Denver anaerobic sludge with
other Metro sludges (Reference 42).
Because of the continuing need for dried sludge by the Denver Parks
Department, Metro has recently processed the Northside sludge separately
for park use. Denver anaerobic sludge has also been similarly processed
for use in reclaiming land at the AMAX Urad mine near Berthoud Pass.
Metro's recent communication described the manner in which Denver sludge
is processed:
"Polymer conditioned anaerobically stabilized vacuum filter cake
is loaded into Denver Parks Department trucks for transport to a drying
site located on the Denver City Jail property at Smith Road and Havana
Street (east of Stapleton Airport). The sludge is spread on the surface
of the soil to a depth of 12 inches and allowed to dry. Occasionally
during the drying process the sludge is turned with a front-end loader.
This operation results in a savings to the District of $30 per dry ton
of sludge processed in this manner. Officials of the Denver Parks De-
partment report their cost for the transport and drying operation to
be about $16 per dry ton of sludge processed. From the stockpile,
sludge is transported to parks in the City of Denver and areas being
developed as parks. The sludge is spread and/or incorporated into the
soil. The Denver Parks officials report the cost for this operation to
be $2 to $4 per dry ton. There have been no special controls applied
to the application of sludge to the land being developed as parks. Lo-
cation of several parks which have been developed or have otherwise
utilized sludge as fertilizer are as follows:
164
-------
1) Ruby Hill Park
West Jewel and South Platte River
2) Crestmoor Park
1st Avenue and Monaco
3) Cook Park
Monaco and Cherry Creek
4) Washington Park
5) Hampden Heights Parks
Cornell and Dayton".
Since the inception of the Metro offsite solids program, it
has always been assumed that Northside sludges would be included
in the reuse system. Recently the City has proposed that a separate
sludge disposal system involving rehabilitation of the sludge drying
beds at Northside be studied in a separate facilities plan (see Let-
ter #33, from the City and County of Denver). This issue is dis-
cussed under Issue IV-4.
EPA became concerned in the course of the review of the draft
EIS that design for Northside sludge treatment by Metro consider
three important factors involved with the proposed offsite solids
system:
1.) In a letter to the Metro District, EPA recognized the fact
that the Northside plant must maintain under contract a 5 per-
cent dry solids sludge concentration for sludge pumped to the
Metro plant. This requires a substantial decant to be returned
to the primary clarifier system at Northside and eventually to
the Metro Plant.
With the Metro solids management plan, no decant return to the
Metro central plant is envisioned, Both decant and sludge solids
would be pumped to the drying basins. This would have the triple
advantage of retaining additional nutrients in the sludge stream,
removing nutrients from the wastewater, thus reducing the load on
the treatment plant, and eliminating the necessity to dewater the
anaerobically digested sludge at the plant.
EPA questioned whether the same arrangement could be used for
Denver Northside sludge in the long-range Metro solids manage-
ment plan; that is, to include the Northside decant from the
anaerobic digesters 1n the pipeline. It appeared that such
an arrangement could have a substantial cost benefit as well,
by removing a portion of the biochemical oxygen demand (BOD)
165
-------
and suspended solids load on the Metro plant that ultimately is con-
verted into the difficult-to-dewater waste activated sludge. EPA
also felt that the City could benefit as well in this situation
through reduced charges for BOD and suspended solids entering the
Metro plant and with reduced sludge handling costs.
2.) Another point that concerned EPA was the primary/secondary
sludge imbalance between the Metro and Northside plants.
Denver Northside processes only primary sludge, while the
great bulk of Metro sludge is secondary waste activated (WAS). It
could well be the case that optimum operation of the Metro
digesters may require blending with primary sludge. It appeared
that separating the operations of the two plants might fore-
close this option. EPA also wanted to know if removal of •
Northside digested sludge would have any effect on Metro
sludge drying times.
3.) The third point that concerned EPA was the future availability
of dried sludge to Denver Parks Department in view of the great
distance from the proposed drying site to the downtown Denver
area. EPA recognized that there were certain benefits to
having dried sludge available close to markets in the Denver
metropolitan area, such as the Denver parks. It is also the
case that other municipalities have expressed an interest in
using dried sludge on park lands. Perhaps drying some portion
of the sludge on the Northside drying beds could provide a
less expensive means to provide sludge to willing users in the
core metropolitan Denver area.
Metro responded to each of these points in turn. The following
constitutes Metro's view of how the Northside-Metro sludges would be
handled with the offsite solids system:
"1- Jt is anticipated that when the proposed system is operational,
Denver will send their anaerobic digester contents in entirety
to the Metro District for transport to the drying/distribution
center. It should be pointed out that Metro, in cooperation
with Denver, will attempt to manage both facilities to provide
the greatest cost benefit possible. It will, however, be nec-
essary for Metro and Denver to continue to return their decant
from the anaerobic digestion process to the primary treatment
facilities until the new drying basin project is completed. At
that time, it is anticipated that all supernatant or decant will
go to the drying basin for drying; the primary reasons for this
are outlined by you in your comment regarding triple advantages. . .
2. The operation of the Metro District facility and the Denver North-
side facility area .are, and have been, under separate management
166
-------
and control, However, Metro and Denver Northside staffs have
worked diligently through an Operations Coordinating Committee
to bring about optimization of both facilities. It is envis-
ioned that this endeavor will continue throughout the years.
It is impractical for one facility to be operated in a manner
which would not complement the operation of the other. The
imbalance of sludge (waste activated to primary) will continue
to be a major problem for both facilities. With regard to
the question of drying times, it is impossible to predict
drying time effects at this time because the sludge in question
has not yet been produced by the Metro facilities. . .
3. In response to the comment regarding flexibility, we feel this
point is the single most important consideration in the oper-
ation of the two facilities. For example, if Denver Northside
sludge could be dried at the Denver Northside facilities or
could be sent to Metro or any conceivable configuration between
these two extremes, the greatest cost benefit for both facilities
would be realized."
On the latter point, Metro has very recently indicated that they
are studying the possibility of drying and storing a limited amount of
polymer dried anaerobic vacuum filtered sludge at the Metro plant site.
The Parks Department would then be able to haul the dried sludge di-
rectly to parks from the Metro plant rather than haul the sludge to the
Denver Jail site near Stapleton for further drying. Cost savings to
the Denver Parks Department could then be achieved.
Therefore, the current Metro plan for Northside sludge management
in the offsite solids project calls for pumping most or ail of the
Northside sludge and decant to the offsite solids drying area, except
for occasional vacuum drying of limited amounts of digested sludge
at the Metro site. If the sludge is dried to the 20 percent cake
solids now achievable with Denver vacuum filtered digested sludge,
there should be no leachate problem at the Metro plant site. A
certain amount of ground preparation to contain occasional rainfall
runoff should adequately protect the South Platte River. Because
this option is still very preliminary, the definitive information
on tonnage and design is unavailable. Such an operational change
would require an NPDES permit change and would be extensively re-
viewed. With the full decant from Northside being sent to the offsite
solids site, the quantities of total sludge volumes expected in the
1985 design year are given in Table 6. The expected increase in
sludge volume would be on the order of 8.5 percent, which is only
a minor increase to the system, EPA discusses the capacity of this
system under Issues 11-12 and 11-13. There appears to be sufficient
capacity to handle this flow. There will also be a minor increase in
operational costs.
167
-------
EPA believes that close cooperation between the Denver Northside
and Metro Districts is essential to optimum performance of this pro-
posed offsite solids system. The system does have promise to reduce
costs to both districts if carefully managed. Metro and Denver should
begin negotiating necessary agreements, including amending the con-
tract calling for a 5 percent solids from DNS if necessary.
Table 6. PROJECTED 1985 SLUDGE QUANTITIES TO BE DRIED AT DRYING AND
DISTRIBUTION CENTER
Weight Dry Solids
Vol ume
of Water
Percent
SIudqe Oriqin
mt/day
tons/da.y
m3/day
qal/dav
Total Solids
DNS digested
primary
w/o decant
18.2
20
360
95,000
5.0
DNS digested
primary
w/decant
18.2
20
640
170,000
2.8
Metro primary
digested and
concentrated
WAS
81
89
2930
775,000
2.8
Total w/o
decant
99
109
3300
871,000
3.1
Total w/
decant
99
109
3580
945,000
2.8
168
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SECTION II
DRYING AND DISTRIBUTION SITE ISSUES
ISSUE II-1. Please provide a better description of existing condi-
tions at Site B-2 and a better definition of on-site environmental
impacts.
The general environmental setting of Site B-2 is described in
Section III and Appendix E of Volume I of the EIS. The site is more
or less visually indistinguishable from the surrounding area, most
of which is used for dryland wheat farming. This section discusses
some of the existing conditions at Site B-2 which will be directly
affected by the sludge drying and distribution center. Particular
emphasis is given to the geology and geohydrology and the potential
for groundwater contamination.
Loss of Productivity
As noted above, Site B-2 is currently used for dryland winter
wheat farming. This land will of course be lost to wheat production
when the drying and distribution center is built. This is a loss of
about 810 ha [2000 acres] of productivity.
The B-2 site is now under the ownership of several individuals;
a 320-acre section is also owned by the State of Colorado. As it now
stands, no one owner will lose more than 320 acres, except perhaps
for Mundel1, who has part ownership of one-half section and ownership
of another within Site B-2. Because of the dispersed nature of the
pieces of land cultivated by dryland farmers of the area and the
relatively large size of these farms, it is not believed that purchase
of these lands in B-2 will result in any individual fanning operation
being put out of business. This statement is made primarily because
of a lack of evidence to the contrary; none of the current owners
who have commented on this EIS (Meyer, Bennett, Mundell) have indi-
cated such a situation. A map of the current owners can be found
in the attachments submitted by John Kalcevic (see Letter #41).
In 1975, the site was estimated to have a productivity similar
to that of Adams County in general. This was 27 hi*/ha [30 bu/acre].
In Adams County, some 53,000 ha [131,000 acres] of land is dryland
*hl = hectolitre (100 litres)
169
-------
farmed. In addition, about 1,600 ha [4,000 acres] of land is used
for irrigated wheat farming and some 21,700 ha [53,600 acres] for
other irrigated and non-irrigated crops. The loss of 810 ha [2,000
acres] therefore represents a loss of 1.5 percent of the total wheat
acreage, and a loss of 1.0 percent of the total farmland acreage in
Adams County. Assuming an average price of $9.62/h1 [$3.50/buJ for
wheat, the financial sales loss to the county will be about $105,000/yr
(Reference 12). This represents less than one percent of the total
value of all crops produced in Adams County in 1972 and 1973. Some
of this impact may be mitigated by having agricultural production on
the research and demonstration portion of the site (roughly 530 ha
[1300 acres] out of 810 ha [2000 acres] could be used).
Surface Mater Resources
As noted in Volume I of the EIS, the site has no perennial
streams or other bodies of surface water and is located on slightly
higher ground than the surrounding terrain. When rainfall occurs,
the site does not receive runoff from outside its borders, except
on two ephemeral streams bordering the site, Lost Creek on the eastern
edge and Horse Creek on the western edge. Lost Creek flows to the
north-northeast, Horse Creek to the north-northwest.
Geology
The site lies within the Denver Basin on the western edge of the
Lost Creek Drainage Basin. The general geology of the Denver Basin
is described in Section III and Appendix E of Volume I.
In order to assess more precisely the subsurface geology at
the site, a geotechnical investigation was carried out in 1976 (Refer-
ence 13). This investigation was conducted by examination of a
number of test pits and holes at the B-2 site. The investigation found
that eolian (windblown) deposits blanket most of the site, with
alluvial (stream-deposited) soil being found at the extreme southeast
comer of the site. Soil types beneath the site consist of: silty
and sandy clay, silty to clean, fine sand, clayey and silty sands,
and silty to clean, well graded sands and gravel. Bedrock consists
mostly of interbedded claystones and sandstones. Transition from
soil to parent bedrock is often gradual. Clayey soils probably make
up about two-thirds of all soil types present, with most of the rest
being silty to clean, fine sands. Depth to bedrock varies from about
0.6 m [2 feet] to 12 m [38 feet]. No free groundwater was encountered
in any of the test pits or holes.
The bedrock beneath the site consists of conglomerates, sand-
stones , si Its tones , and shales of the Arapahoe, Denver and Dawson
formations. These formations are all quite similar in character
and are often indistinguishable from each other. The bedrock is
170
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weathered and partially decomposed and is easily broken. It tends
to be close to the surface near the topographic highs at the site
and somewhat deep near the topographic lows. In other words, the
bedrock surface generally is reflected by the ground surface so
the flow of any perched groundwater beneath the site will most likely
be in the same direction as surface water (Reference 14). The site
is located on a topographic ridge, with drainage to the north-north-
east, along Lost Creek, on the eastern side, and to the north-northwest,
along Horse Creek, on the western side. Flow of a perched aquifer
formed from bed leachate would likely also follow these stream
channels.
The Arapahoe, Denver and Dawson formations have small to moderate
groundwater yields and are tapped primarily for livestock and domestic
wells in the region of Site B-2. The sandstone members of these
formations are the water bearing strata. The clay, siltstone and
shale strata act as aquitards, or barriers to groundwater flow. Sand,
gravel, and conglomerates with minor amounts of clay in the lower part
of the Arapahoe formation have somewhat higher though still moderate
yields of water.
Below the Arapahoe, Denver and Dawson formations are the Fox
Hills and Laramie sandstones. These occur approximately 300 to 370 m
[1,000 to 1,200 feet] below the ground surface in the vicinity of
Site B-2 (Reference 15). These sandstones yield small to moderate
quantities of water to domestic, stock, public supply and industrial
wells throughout the area. The Fox Hills sandstone is the most
prolific of the deep bedrock formations (Reference 15).
Groundwater Flow Beneath Site B-2
On the basis of the U. S. Geological Survey (U.S.G.S.) survey
of the Lowry Bombing Range area and of the geotechnical investigation
of Site B-2 (References 16 and 13), Stanley Robson of the U.S.G.S.
has made estimates of the probable groundwater flow beneath the
site (Reference 14). At present no perched aquifer in the unconsoli-
dated sediments of the site exists. If the rate of leaching from
the drying beds exceeds the vertical water flow into the bedrock,
then a perched aquifer will form in the overlying unconsolidated
sediments. The flow in this aquifer will for the most part follow
the slope of the bedrock surface, which tends to be congruent with
the land surface. The bed leachate would then flow along the route
of Horse Creek to the north-northwest and Lost Creek to the north-
northeast. Robson estimates the rate of lateral flow in this aquifer
would be 0.17 m/yr [0.55 feet/yr], assuming the permeability of
the sediment to be 1.8x10"2 m/day [6x10-2 ft/day], a porosity of 0.25,
and a hydraulic gradient of 6.2xl0"3.
If the rate of leachate flow through the beds is not greater
171
-------
than the rate of vertical movement in the bedrock, then no perched
aquifer will form. In this case, leachate from the beds will move
downward into the bedrock below the site, and will eventually reach
the bedrock aquifers. This leachate would be mixed with the water
already in the bedrock aquifers. Robson has calculated the approxi-
mate flow of water in the upper bedrock aquifers. Assuming the
same lateral permeability as used in the Lowry Bombing Range study
of 0.86 m/day [2.8 ft/day] and considering only the upper 91m
[300 feet] of the bedrock aquifer, then 3.1x10^ m3/yr [250 acre-ft/yr]
of groundwater will cross the southern boundary of the drying site.
Presumably this would be the approximate yearly volume of water
available for dilution of the leachate from the beds which reaches
the upper 91m [300 feet] of the bedrock aquifer.
A real-world situation could also occur where both a perched
aquifer forms and some bedrock aquifer recharge takes place. This
could happen if the unconsolidated sediments are generally more perme-
able than the underlying bedrock. However, if the bedrock is occasi-
onally discontinuous or if there is a permeable outcrop of a porous
bedrock material such as sandstone, recharge to deeper aquifer
could occur. The exact flow under this situation cannot be precisely
determined until actual unconsolidated flow of leachate takes place.
The quantity of leachate which percolates from the beds will
depend on the permeability of the bed lining, t;ie depth to which the
beds are loaded, and the area of beds actually leaching water at
any given time. This factor is discussed in the following section.
ISSUE II-2. Will groundwater deterioration occur, particularly to
the Lost Creek aquifer, and what mitigating measures such as lining
are necessary?
From the data obtained during the geotechnical investigation
of the soils at the site, it was determined that neither the upper
unconsolidated deposits nor the upper bedrock strata were saturated
(Reference 13). In most of the test holes and pits, the bedrock-
unconsolidated deposit interface consists of low-permeability clay-
stone or more permeable siltstone. Leachate or groundwater could
move through the siltstone stratum if saturated conditions occurred.
The unconsolidated sediments overlying the bedrock have
permeabilities estimated to range from 10~2 to 10 cm/sec [28 to
2.8 ft/day] for clean sands to around 10 cm/sec [2.8 x 10"' ft/day]
for si 1ty sands and clays (Reference 13). Permeabilities in the
higher range would allow significant leachate flow within the uncon-
solidated sediments. If the vertical flow of water into the bedrock
formation is very slow, as seems likely, then a perched groundwater
172
-------
aquifer will form in the upper sediments if enough water leaches
from the drying beds.
In 1976, the U.S. Geological Survey conducted a study of
groundwater movement and contamination in the vicinity of the current
sludge disposal and landfill areas at the Lowry Bombing Range (Refer-
ence 16). The landfill operation began in 1966, and sludge disposal
operations in 1969. Both operations are continuing at present. The
sludge disposal at Lowry consists of trucking both digested and
undigested sludge of about 10 to 16 percent solids to the site,
where it is dumped onto the soil in a uniform layer about 15 cm
[6 in] thick. The sludge is then plowed into the soil. Loading
rates are very high, about 67 mt/ha/yr [30 tons/acre/yr]. The sludge
also contains chemicals used to aid in dewatering by vacuum filtra-
tion.
Geological conditions beneath the Lowry Site are more or less
comparable to those beneath Site B-2; that is, unconsolidated alluvial
and eolian deposits with a maximum thickness of about 7.6 m [25 ft]
overlying Denver and Dawson bedrock formations. Groundwater in this
area moves through the unconsolidated sediments in the general direc-
tion of the alluvial valleys. This is generally to the north and
northwest. The same is true of the water in the upper 30 to 110 m
[100 to 350 ft] of the bedrock. In the lower bedrock, about 170 to
480 m [570 to 1,570 ft] below ground level, the groundwater flow is
to the west, suggesting that aquifers in the two depth intervals do
not have good hydraulic connections. The alluvial aquifer generally
has a greater potentiometric head than the bedrock aquifers indi-
cating a potential for downward flow of water in addition to lateral
flow.
Twenty-eight wells tapping both the alluvium and the bedrock
around the landfill and the sludge disposal area were examined for
evidence of groundwater contamination. In addition, four wells some
distance away were sampled to provide background concentrations.
High chloride and TDS concentrations were used as indicators of
contamination. A plot of the mean chloride versus mean TDS concen-
trations in all wells sampled is shown on Figure 4. Five wells per-
forating the alluvium were found to have markedly degraded water
quality. These wells are in Region 3 on Figure 4. One of the wells
was located in the landfill, two are immediately downslope of two
large areas used to bury sewage sludge, and two are near stagnant
manure-contaminated stock ponds. Fifteen other wells, those in
Region 2, contained water showing higher than expected values of TDS
and chlorides, and ten wells in Region 1 had values similar to
those of background values. Four wells within the study area but not
near the landfill or sludge-disposal areas were used to estimate
background values since no analyses were available predating
173
-------
FIGURE 4
1000
l r
I I I
*6CDA
n—i—r
600
s
3
ss
(9
d
§ 100
Region 3
2
z
ui
U 50
z
o
o
ui
o
§
-j
X
u
z
2
3
Region 2
4CAB1
4DBC
9ACD
4CAC
.29AAA
.•CDC
.9BAA
.28BDD
*34068
4AAA2 _6CP0
33BAB1 -6 BOD
*33BAB3
.30DCD
32CBC. W?DCA
.32BM
Region 1 •
• 9D0A
(31DP
. 6ABC
4 BOB
.32A0A
32ADD
10
\oo
.30 BOO
b31DDC
X
I I I I I
_L
NOTE: Underlined welt numbers
indicate wells located
in SC5-65, all other
wells are located in
SC4—65
I I I I l I—L
«0Q 1000 5000
MEAN DISSOLVED—SOLIOS CONCENTRATION. IN MILLIGRAMS PER LITER
10.000
CHLORIDE AND TDS CONCENTRATIONS IN
WELLS SAMPLED DURING LOWRY GROUNDWATER STUDY
Source: Reference 16
174
-------
commencement of landfill operations in 1966. These were wells
31DDC, 30BDD, 9DDA, and 3ABB, in Region 1 on Figure 4.
Water from twelve wells perforating the upper bedrock were also
examined for evidence of degradation. Although chloride concentra-
tions were higher than background values in two wells, no discernable
degradation was found in upper bedrock groundwater. Analyses on
water from three wells perforating the lower bedrock also show no
effects.
The conclusion from this study is that the primary negative
effect of the sludge disposal operation at Lowry has been on the
alluvial aquifer, with no discernible effects as yet on deeper water-
bearing strata. The alluvial degradation is not yet serious; however,
the potential definitely exists for groundwater deterioration from
sludge leachate, and for this reason every effort should be made to
minimize the quantity of leachate allowed to percolate into the
ground.
Groundwater Quality Requirements at Site B-2
The EPA policy for the proposed project shall be that all chemi-
cal , biological and pesticide criteria specified in EPA's Manual
for Evaluating Drinking Water Supplies will be met for permanent
groundwaters potentially affected by percolate from the site
(Reference 17). Where a drinking water parameter in the ground-
water already exceeds the criteria, no further degradation will
be allowed. There will also be no significant deterioration of
other parameters (such as TDS) which would impair any other existing
uses of the groundwater in and around the site.
The U.S.G.S. has recently made a survey of the wells in the
vicinity of the site. The well locations, depths, water levels and
uses are given in Table 7. The location of each well is also shown
on Figure 5. These wells would be the first to show any deterioration
of water quality in the event that bed leachate reaches the bedrock
aquifer.
Lining of Drying Basins
In order to reduce as much as possible the quantity of leachate
entering the ground from the drying beds, EPA will require the equi-
valent of a clay liner beneath all beds. This liner will be at least
0.30 m [1 ft] thick, and have a permeability less than or equal to
1.0 x 10"' cm/sec [2.83 x 10"4 ft/day]. Liners with these character-
istics could be at least partially constructed by compacting clays
available onsite. Liners with this permability will keep the infil-
tration of leachate from the beds into the groundwater below the site
175
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Table 7. WELLS IN THE VICINITY OF PROPOSED
DRYING AND DISTRIBUTION CENTER
Reference Location2 Depth
Letter1 n ft
Water Level Date of
Below Water Level
Land Surface Measurement Use
m ft
A
2S-64W-2ADD
79.3
260
38.72
126.99
6/77
Domestic
B
-4 BBC
-
-
37.10
121.7
bill
Domestic
C
-5ABD
54.9
180
33.13
108.65
5/77
Domestic
D
-5CAC
-
-
-
-
Abandoned
E
-6BBB
122
400
53.11
174.2
5/77
Domestic
T
-6 CAB
134
440
49.2
161.43
bin
Abandoned
G
-6DDC
101
330
27. i
90
7/74
Domestic
H
-7DAA
83.5
274
-
-
Domestic
I
-8CBC
82.3
270
-
-
Stock
J
-10CDD
93.6
307
54.93
1803
Domestic
K
-11DDD
39.6
130
29.37
96.34
5/77
Abandoned
L
-14BCD
30.5
100
22.80
74.79
bin
Abandoned
M
-14CAB
30.5
100
-
-
Domestic
N
-17DAA
44.2
145
27.88
91.45
bin
Abandoned
0
-18CCB
76.2
250
7.83
25.67
bin
Domestic
P
-19BCC
84.5
277
7.6
25
1965
Domestic
Q
-19CDC
11.1
36.5
7.15
23.44
bill
Irrigation
R
-20DDC
37.5
123
Dry
Abandoned
S
-22CBC
70.1
230
33.63
110.3
5/77
Abandoned
T
-23DBA
24
80
Dry at 16
.5 m [54
ft]
Abandoned.
D
-28AAB
-
-
Dry at 15
.6 m [51
ft]
Abandoned
V
-31DAA
20
64
5.72
18.76
-
Domestic
W
-34BCA
-
-
27.41
89.90
bin
Abandoned
X
-35CCC
30
97
25.63
84.05
bin
Abandoned
Source: Reference 22 except where noted
1 Refers to Map Location on Figure 2
^Location based on U.S.G.S. system for locating wells (see Reference 16)
Source: Reference 23
176
-------
FIGURE 5
\JtKICQWETR
V !
r \ ¦**»
k it
\1 PROPOSED I J
Drying
' ' Irondalie Road
au \
LEGEND
• DOMESTIC WELL
a IRRIGATION OR
STOCK WELL
¦ ABANDONED WELL
WELLS IN THE VICINITY
OF SITE B -2
177
-------
to as low a quantity as possible without installing expensive liners
or leachate collection systems, such as those discussed in Issue
IV-2. This will minimize the potential for groundwater pollution
from bed leachate.
In order for clay liners such as those recommended to be
feasible for this type of operation, certain precautions must be
taken during construction and operation. The clay liners must be
covered initially with at least 30 cm [1 ft] of another material,
such as sand or other type of soil. This cover will serve two
purposes. The first is protection of the liner during removal of
the dried sludge. When front-end loaders are used to scrape the
sludge from the beds, a certain amount of bed material will also be
removed. The cover material will prevent the clay liner from being
harmed, and the quantity removed must be replaced after each sludge
removal operation. The second function of the cover is to prevent
the clay liner from becoming excessively dried and, therefore, subject
to cracking during the latter stages of sludge drying. The clay
liner will not dry out completely and crack if it is protected in
this manner from direct sunlight. With these precautions, clay
liners will provide a suitable liner for the drying beds. The
requirements for lining are set out in Grant Condition #5 in
Appendix A.
The quantity of water which will leach through these linings
can be calculated from Darcy's Law, knowing the total bed area and
the pressure head, or depth of water in the beds (Reference 18).
Darcy's Law for water leaching through a medium can be stated as:
Q = KA(^)
where Q = volume of water leached, m^/sec
K = permeability of medium, m/sec
A = area through which water is leaching, m
H = pressure head through medium, m
L = thickness of medium, m
Assuming that half the total 243 ha [600 acres] of beds will have free
water available for leaching at any time, and that these beds contain
water at a depth of 0.61 m [2 ft], then the quantity of water leached
will be:
(1.0xl0"7^)x(^px104 m2Mo(i£)x(lW ^x(24x3600x365) = 76'600 Ay
178
-------
[(2.83x10"4 ft/day)x-f^O_acx43>56o)x2_ftx 365 = 2.70xl06 ft3/yr]
This is the maximum quantity of water which should leach from
the beds because the soils may become even less permeable after
sludge application. Several investigations (References 19, 20, 21)
have found that soils beneath holding ponds tend to become less
permeable after animal wastes have been applied to them. The process
generally occurs over periods of weeks. The same phenomenon would be
expected to occur when sludge is applied to clay soils. Tests
conducted by Metro at a site in Greeley, Colorado, using Denver
sludge, found that the permeability of sandy soils decreased to
almost zero within a year after sludge application. The soil permea-
bility in all of these investigations returned to its original value
after being dried, so the mechanism by which clogging occurs is a
reversible one.
Leachate Flow in Unconsolidated Sediments
If the leachate from the beds forms a perched aquifer below the
site, the water will likely flow laterally through the unconsolidated
sediments along the bedrock surface. Occasional fracturing or out-
cropping of porous bedrock formations could still result in some
percolation to deeper aquifers. The site lies on a slight ridge
which runs roughly from its southwest corner to the midpoint of the
north border. Approximately one-third of the site lies to the west
of the ridge and two-thirds to the east. This means that about one-
third of the perched aquifer will flow to the north-northwest, along
Horse Creek, and two-thirds to the north-northeast, along Lost Creek.
North-Northeast Flow Rate - -
Robson of the U.S.G.S. has estimated the lateral flow rate in
the unconsolidated aquifer would be 0.17 m/yr [0.55 ft/yr]. He
assumes a sediment permeability of 2.1x10"^ cm/sec [6x10""^ ft/day],
a porosity of 0.25 and a hydraulic gradient (slope) of 6.2x10*3.
Data describing the hydrologic character of the alluvium in
several areas approximately 25 km [15 mi] southeast of the site found
that the hydraulic conductivity of the alluvium ranged from 2x10"3 to
40 m/day [8xl0-3 to 130 ft/day]. The mean was 10 m/day [32 ft/day].
The mean value is close to the highest permeability estimated at the
site for clean sands in the unconsolidated sediments (Reference 13).
Using this hydraulic conductivity as a closer estimate of the permea-
bility of the sediments underlying the site than that used by Robson,
then the rate of lateral flow in the aquifer, using the same porosity
and hydraulic gradient, can be calculated by applying Darcy's Law
to flow within a porous medium. The equation for velocity becomes
179
-------
(Reference 18)
V - -nff
-------
(10 m/day)x(6.8x10'3)x(o^)x(365) = 99 m/yr
[(32 ft/day)x(6.8xl0"3)x(Q^-)x(365) = 318 ft/yr]
The Colorado State Engineer's office and the U.S.G.S. have no
record of any alluvial wells located along Horse Creek within 6.5 km
[4 mi] of the drying site. There are several alluvial wells along Box
Elder Creek to the west of Horse Creek (Wells 0, P, Q, and U on
Figure 5). This creek is separated from Horse Creek by a ridge
which will in all probability prevent any alluvial groundwater from
flowing from Horse Creek alluvium into Box Elder Creek alluvium.
Apparently, then, the more critical alluvial aquifer is that along
Lost Creek, and should be monitored more carefully.
Leachate Flow in Bedrock
Since most of the wells in the immediate vicinity of the site
tap the bedrock aquifer, the rate of flow into this aquifer is
important. Flow within the bedrock will be both vertical and lateral,
with lateral flow rates generally greatly exceeding vertical rates.
Lateral Flow Rate - -
No data exist on the permeability of the bedrock beneath the
site. Data do exist for bedrock of the Denver and Dawson formations
at other locations in the vicinity of the Lowry Bombing Range (Refer-
ence 16). The hydraulic conductivity of six samples from the upper
bedrock formation near Lowry range from 2.9x10"^ to 2.7 m/day
C9.4x10-t> to 8.7 ft/day], with a mean of 0.86 m/day [2.8 ft/day]
(Reference 16). The mean porosity was .41.4 percent. Water-level
measurements in the wells tapping the bedrock aquifer near Site B-2
indicate that the groundwater flows in the same general direction as
do surface waters; that is, to the north-northwest along Horse Creek
and to the north-northeast along Lost Creek (Reference 23). The
hydraulic gradient is about 4.7x10"^. The lateral rate of ground-
water flow using the mean hydraulic conductivity given above is then:
(0.86 m/day)x(4.7x10"3)x(q12jj^)x(365) = 3.6 m/yr
[(2.8 ft/day)x(4.7xl0"3)x(jj-^-)x(365) = 11.6 ft/yr]
181
-------
Vertical Flow Rate - -
The rate of vertical water flow in saturated materials is con-
trolled primarily by the stratum having the lowest vertical hydraulic
conductivity and greatest thickness. Siltstone in the upper part of
the bedrock formation probably has the lowest hydraulic conductivity.
Again using data from the Lowry study since none is available at
Site B-2, the vertical flow rate can be estimated. In the Lowry study
the vertical hydraulic conductivity was estimated to lie midway between
the mean and minimum lateral hydraulic conductivity, or 4.9x10~J m/day
[1.6xl0~2 ft/day]. The head difference at Lowry was estimated from
well data to be about 2.0 m [6.5 ft] across a zone about 50 m [160 ft]
thick consisting primarily of siltstone. A porosity of 41.4 percent
was again assumed. Using these assumptions, the vertical flow rate
is then:
(4.9xl0-3 m/day)x(^~)x(q-^)x(365) = 0.1 7 m/yr
[(1.6x10"2 ft/day)x(^-)x(g-J17)x(365) = 0.57 ft/yr]
The shallowest bedrock well in the immediate vicinity of the
site is Well J at the site's northeast corner. This is a domestic
well with a water level of approximately 55 m [180 ft]. At the above
calculated vertical velocity, the time required for leachate to first
reach this well is:
30 m = 323 yrs
Discussion
0.17 m/yr
The preceding calculations of leachate flow rates through the
unconsolidated and bedrock aquifers should be considered order-of-
magnitude estimates only, as they are not based on firm data from the
site but on extrapolations of data from other areas. The estimates
presented should represent the upper bounds of the most probable true
rates; that is, the actual rates are very possible lower than those
presented, but are probably not any higher. The estimates are pre-
sented to give some idea of the time frame in which evidence of
groundwater pollution is likely to first be noticeable in existing
wells in the area.
On the basis of the soil data obtained at the site, it appears
that the more permeable sediments and bedrock are on the western
rather than the eastern side. This means the leachate flow in the
unconsolidated sediments along Lost Creek will be much slower than
the flow along Horse Creek. There are no wells tapping the alluvium
along Horse Creek within 6.5 km [4 mi] of the site. There apparently
is an abandoned alluvial well within 2260 m [7390 ft] of the site
132
-------
along Lost Creek.
The greatest potential for groundwater pollution appears to be
in the bedrock beneath the site. Most of the wells shown on Figure 5
are bedrock wells. It is impossible with the available data to
predict the extent to which deterioration of the bedrock aquifer will
take place. A more accurate assessment of this potential will be
possible after the beds have begun operation. A monitoring program
will be set up to determine actual rate of leaching from the beds and
direction and extent of leachate flow.
Groundwater Monitoring Program
The U.S.G.S. has submitted a proposal for monitoring groundwater
in both the unconsolidated sediments and bedrock beneath the site.
This proposal is presented in Appendix D. The proposal calls for
drilling twenty-nine onsite and five offsite wells for monitoring any
water in the unconsolidated, or alluvial, sediments. Six wells will
be drilled for monitoring the upper 30 to 60 m [100 to 200 ft] of
bedrock groundwater. In addition, six pan-type lysimeters will be
installed under selected drying basins to determine rate of leachate
movement and to monitor leachate quality. It is also planned to
monitor as many as possible of the existing wells within a three-mile
radius of the site. EPA thinks that more monitoring of the unconsoli-
dated flow should be done in the initial stages of the project. Addi-
tional multi-stage vacuum lysimeters should be used; once a better
idea of the kind of groundwater movement is obtained, well placements
could be made.
This program with subtle modifications will allow a fairly
accurate assessment of the effects on groundwater quality by the
sludge drying project. Evidence of potentially serious contamination
problems should become evident long before a serious problem develops.
If such indications appear, appropriate mitigative actions would be
taken. This would include lining the basins with a completely imper-
vious liner, installing a leachate collection system, or as a last
resort, ceasing drying operations altogether. EPA will require sub-
mission of a comprehensive groundwater monitoring program plan to be
submitted in time for at least six months of data collection prior
to project implementation (see Grant Condition #3f).
Groundwater Quality Implications
3 fi 3
Approximately 77,000 m /yr [62 acre-feet or 2.7 x 10 ft /yr] of
free water associated with the sludge drying operation are predicted
to move through the unconsolidated materials beneath the site toward
permanent groundwaters each year with the suggested lining measures.
183
-------
The principal constituents of concern would be soluble species,
primarily TDS and nitrates. EPA has little doubt that suspended
solids, heavy metals, bacteria and viruses will be effectively
removed and contained in the soil medium by adsorption, ion-exchange,
and filtration processes. Therefore, further discussion will focus on
these two species -- TDS and nitrates. EPA is concerned that drinking
water standards be maintained in the regional groundwater supply.
Nitrates. - Nitrates pose the most serious hazard to drinking
water supplies. Drinking water standards call for an upper limit
of 10 ppm nitrate (as N) in order to protect against the possibility
of methaglobanemia, a disease affecting newborn and infant children.
Nitrate contamination is a problem in the lower reaches of the Lost
Creek Groundwater District. This is believed to be caused by leaching
of applied fertilizers on irrigated lands, which predominate in the
lower reaches of the Lost Creek basin. For this reason, the Lost
Creek Groundwater District has opposed this project (see Letter #44),
citing the dangers threatening domestic users of this groundwater
supply from a cumulative buildup of nitrates in the groundwater.
Presuming that nitrate pollution is directly related to irrigated
agriculture, there is little reason to believe that there is any
current nitrate problem in the groundwaters beneath site B-2. Under
this assumption, background nitrate concentrations should be near
zero. This assumption can be tested when the U.S.G.S. is allowed to
develop pre-project groundwater monitoring.
Metro's test data at the Greeley drying site has indicated
nitrate concentrations in the range of 20-200 ppm as N as instantan-
eous concentrations. Assuming a long-term average concentration of
100 ppm of nitrates in the percolating waters from the sludge opera-
tion, and a 60 acre-foot per year leaching rate, a rough order-of-
magnitude estimate of the groundwater nitrate concentration can be
made. Further assuming a background nitrate concentration of zero,
a 2" precipitation recharge rate, and approximately 250 acre-feet/year
of groundwater crossing the site (Reference 14), a concentration of
nitrates in the groundwater leaving the site of 9 ppm would be pre-
dicted. This is in the vicinity of the 10 ppm standard. Further
mixing would reduce the concentration in the area.
EPA does recognize that there will be some impact of increased
nitrates in the vicinity of the site, even with the proposed mitigat-
ing measures. EPA will insist that concentrations of nitrates
leaving the site B-2 boundary be maintained within the 10 ppm standard.
The cumulative impact can be stated in terms of total tons added to
the groundwater. With the predicted rates and totals, about 8.5
tons of nitrates per year would be added to the groundwater. Were
the B-2 site under irrigated agriculture, a rough order-of-magnitude
estimate of the leached nitrogen (based on current practices) would
184
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be about 40 tons per year, from a 2000 acre site. The estimated
concentration would be about 20 ppm nitrate as N. The total
cumulative impact of the sludge operation would be about 1/2 that
of an irrigated field of the same size.
TPS -- Similar calculations can be made for the effect of the
added salts from the proposed sludge drying operation. Draft EIS
estimates of TDS in sludge were as high as 6000 ppm (early Metro
data). More recent data from Metro (see discussions under Issue V-l)
indicates that salt concentrations would be nearer 2-3000 ppm.
Assuming a salt loading of 3000 ppm and a natural background of about
400 ppm TDS, the expected concentration of TDS in the groundwater
would be about 640 ppm. This would add about 245 tons of salt per
year into the groundwaters of the area. This should be considered to
be an insignificant increase; the 40,000 acre-feet of water drawn
from the Lost Creek aquifer each year (assuming a 400 ppm TDS) con-
tains some 21,800 tons per year of salts. Drinking water standards
would not be significantly affected by this increase, except perhaps
for isolated wells. Further pumping by Metro could reduce the amount
of salts carried off site beneath Site B-2 if a problem were iden-
tified.
Since these calculations are quite tenuous, Metro will be re-
quired to submit a contingency plan to pump out contaminated water
in the event of a drinking water quality standards violation. County
and State Health Departments will receive data periodically from
Metro and will determine the need for mitigation (see Grant Conditions
#3e and 6).
ISSUE II-3. Will odors create a problem in the vicinity of the site
either from normal operations or with digester upsets?
Concern for potential odor problems near the site has been
expressed by a number of nearby residents in letters to EPA on the
draft EIS. Foul odors emanating from Barr Lake in the past and from
the earlier Lowry disposal site operations are cited as evidence
that such odors will be emitted. However, anaerobically digested
sludge has little odor (most of the sludge disposed at Lowry is not
digested). No situation analogous to that which occurred at Barr
Lake in the past should exist with the present project. If a digester
upset occurs, planned standard monitoring of digesters will alert oper-
ators to the existence of the problem before sludge is released to
the pipeline. Proper corrective action will be taken at the plant
to store the sour sludge for subsequent controlled subsurface injec-
tion. Only properly digested sludge will be transmitted to the
drying bed. If, for any reason, improperly digested sludge is
released to the pipeline, it will be intercepted at the site before
being placed on the drying beds and will be injected into the soil at
185
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the site. This will prevent any foul odors from escaping. These
procedures should prevent foul-smelling sludge from ever being placed
on the drying beds. This procedure will be developed in the Operation
and Maintenance Manual for this project (see grant condition #3b).
Even though properly digested sludge has very little odor,
the cumulative effect of 240 ha [600 acres] of sludge exposed to the
air will produce some noticeable odor. San Jose, California, current-
ly uses about 170 ha [400 acres] of lagoons for drying its sludge.
Although the current mode of operation at San Jose involves filling
the lagoons with liquid sludge to depth of 4 m [13 ft], the district
has used sludge depths of 45 cm [18 in] in the past (Reference 24).
The plant superintendent reported that noticeable odors were pro-
duced when this method of operation was used, mainly after rainfall
rewet the sludge in the lagoons which had already dried. During a
site visit in late August of 1977 by EPA personnel, odors were
noticeable but not objectionable. Weather conditions were slightly
overcast with no rain having occurred recently, and sludge was in
various states of dryness in various lagoons. The greatest source
of odor appeared to be linked with freshly pumped sludge. Sludge
in various states of dryness had no noticeable odor. The plant opera-
tor did report some complaints he believed resulted from rewetting of
the dried sludge.
The San Jose, California basins are located near San Francisco
Bay. A strong continuous onshore wind was evident during the field
trip; this type of steady wind was undoubtedly responsible for carry-
ing the noticeable odors from the newly filled sludge basins. This
type of meteorological condition would bring the odors to someone
directly downwind of the site for perhaps 1.0 to 1.5 km [0.5 to 1
mile]. This could create an occasional odor problem for residents
in the two dwellings east and north of the site within one mile of
the site boundary. Metro should be prepared to compensate the owners
of these properties if the odors prove to be a nuisance. At this
time, EPA cannot definitively say whether such odor potential would
in fact cause a problem for these two residences.
ISSUE II-4. Will land values in the area decrease as a result of
the Metro project and should Metro purchase a buffer zone to compen-
sate owners?
As noted in the discussion of Issue 11-1, the primary land use
in and around Site B-2 is dryland wheat farming. Site B-2 and most
of the property within a ten-mile radius of it are zoned A-2 according
to the Adams County Zoning Department (Reference 12). This zoning
is for agricultural use.
An appraisal of the property at Site B-2 was conducted in 1975
186
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by a private real estate appraisal company (Reference 12). This
appraisal set the fair market value of the 810 ha [2000 acre] site
at about $500,000 in 1975. Although land values fluctuate somewhat,
this value is expected to be more or less that the property is worth
in 1977 (approximately $250/acre).
Use of this site for the sludge drying and distribution center
should not materially affect the value of the surrounding land. If
the center is properly operated, few direct effects will be noticed
outside the borders of the site. The dryland wheat fields around the
site are not in conflict with the proposed use; in fact, the ferti-
lizer and soil conditioner value of the dried sludge may prove to be
an asset to nearby land. For this reason, it is not recommended that
a buffer zone larger than that already proposed be acquired around the
drying beds.
According to the DRCOG land use projection for the Denver Region,
it appears that no land use changes are anticipated near the site
before the year 2000, with the possible exception of a regional air-
port. This aspect is discussed in Issue 11-9.
The potential effect of this sludge drying operation on land
values in the future is somewhat mixed. The value of adjacent lands
will in part depend upon the projected uses. If the area continues
in dryland wheat production, there is no apparent reason why the land
values should rise or fall. Existing adjacent land uses should
continue as before.
Should companion enterprises to the sludge drying operation be
set up, the value of the adjacent lands could increase somewhat. As
far as residential development is concerned, there will probably be
a delaying effect on lands around the site due to the general inflation-
ary rise in land values based on urban development speculation. As
urban developments leapfrog into agricultural lands in rural Adams
County, adjacent properties become desirable for additional develop-
ment and hence, more valuable. Agricultural lands on the entire
Denver metropolitan urban fringe are under considerable pressure from
speculative buyers who are hoping to buy cheaply and sell dearly at
some time in the future.
The location of a solids drying and distribution center in the
rural Adams County area would probably have a retarding effect on
speculative buying of adjacent lands in this area. Given other
available lands, speculators would probably not buy in this area first.
A number of qualifications need to be added, however.
In the first place, site B-2 is located far enough away from
187
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currently developing areas to be an unlikely candidate for near-term
speculative buying. Anyone interested in a relatively quick return
on investment would probably not buy in this area at present. As
the metropolitan area grows, however, this situation would change.
DRCOG projections for urban growth to the year 2000 for the
Denver metropolitan area indicate that site B-2 is still outside of
the areas most likely to be developed. Such development is extremely
difficult to predict; it is possible, however, that such growth (and
its concomitant speculative buying) probably would not seriously
occur until beyond the year 2000.
Another factor to be considered is the possibility of the Adams
County Regional Airport being located at the site 3 km [2 mi] west of
B-2 in the near future. A growth and development scenario much more
rapid than pictured above could occur. It is most probable, however,
that urban and commercial development would preferentially locate
west of the airport, closer to the metropolitan area. The general
effect of the offsite solids project at site B-2 on this development
is that land values around the site might increase, but at a lower
rate than either the lands to the west of the airport or if there
were no sludge project.
EPA does not believe that the presence of the offsite solids
project in any of the situations described above constitutes a sig-
nificant detrimental impact financially to any landholders in the area.
For this reason, no further mitigating measures such as acquiring a
buffer zone is felt necessary.
ISSUE 11-5. Will wind transport of stockpiled sludge create hazards
offsite?
A potential problem with stockpiled sludge identified by various
agencies is the windblowing of the sludge particles. This problem
will be mitigated by proper handling procedures. When the sludge has
dried to 40 to 50 percent solids, it will be removed from the drying
beds by front-end loaders and piled in windrows for further drying
and curing. Although the sludge will essentially be in massive form,
with a high fiber content which will bind particles intimately, some
particles will be loose and readily picked up by the wind. This is
expected to be a very small quantity of sludge. Some pulverization
will also result from transport of sludge from drying beds to stock-
pile areas.
During extremely high winds, the windrows will be wetted down in
order to increase resistance to wind-blowing. Hydrants will be
located at strategic points in the sludge stockpile area to facilitate
188
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wetting of the sludge. Water used for this operation will be plant
effluent used to purge the transport system pipelines as well as
runoff water from the drying and distribution site. Although this
practice will moderately increase drying time, it is not expected to
be necessary except under severe wind conditions. Although a very
small amount of sludge will be subject to windblowing, the quantities
are minor. Once the sludge has dried to 30-40 percent solids, addi-
tional wetting will not materially change the consistency of the solids.
The dried material can hold the added moisture, but will probably
lose the water quickly through evaporation given the large amounts
of air space in the stockpiled material.
EPA will require Metro to evaluate the use of earthern berms
constructed at the sludge storage area. These berms would shield
the sludge from direct wind and greatly reduce the opportunity for
sludge particles to be transported offsite. Metro's original design
for the site called for earthern berms, but drainage was felt to be
a problem. EPA would suggest that berms be placed in such a manner
as to avoid creating drainage problems. Berms could be placed parallel
in a north-to-south direction about 1 to 2 m [3 to 5 ft] high
without seriously impeding the runoff (see Grant Condition #7).
ISSUE II-6. Is the design of the runoff retention system sufficient,
especially during extreme events?
The current design of the Drying and Distribution center includes
two runoff impoundment basins which will store rainfall runoff from
parts of the site. One basin is located in the northwest corner of
the site, and has a total storage volume of about 32,500 m3 [26.4
acre-ft]; the other is in the northeast corner, and has a volume of
about 79,500 m3 [64.5 acre-ft]. These basins will collect only run-
off from areas other than the actual drying beds and sludge stock-
pile areas; rainfall impacting these areas will be retained and
eventually evaporated.
The impounded water can either be released to downstream natural
watercourses (Lost Creek and Horse Creek) or can be pumped back to
the plant effluent impoundment for disposal through the crop watering
systems. Before any water is discharged to surface streams, its quality
must be determined to ensure acceptability.
The runoff collection system consists of grass-lined excavated
drainage channels which drain to the impoundment areas. The north-
west impoundment will collect rainfall from about 77 ha [192 acres];
and the northeast impoundment from about 212 ha [526 acres]. This
area does not include the rest of the site exclusive of the basin
and stockpile area; some rainfall hitting parts of the site will run
off to natural watercourses. However, all areas which will have sludge
189
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applied or which will be modified significantly will have the runoff
collected. The areas on which runoff is not collected are generally
around the edge of the site and are expected to be left essentially
undisturbed as buffer areas.
The two impoundments were designed to hold the runoff from the
20 year, 12 hour storm. This event will result in a rainfall of some
6.73 cm [2.65 in.]. Any greater quantity of rainfall will result in
water being discharged through a spillway in each impoundment. The
spillway crest is located about 1 m [3 feet] below the dike crest,
so that no water should overflow the crests under most conditions.
The spillways discharge to downstream water courses. If an extreme
event occurs which threatens to cause overflow of the dikes, sluice
gates within transfer structures at the base of the dikes can be
opened to allow a greater discharge.
The dikes proposed are earthern embankments which will be formed
by material available primarily at the site. A foundation key is
recommended in the design and the side slopes of the embankment will be
3 horizontal to 1 vertical.
The characteristics of the excavation and foundation material
which are on the site and proposed for use in the embankment are
reported in Reference 13. The report recognizes the existence of
loess in the area and the fact that when wetted, the material exhibits
relatively low shear strengths and is collapsable. The report further
recognizes that the founding material is variable and that some local
slope failures or foundation failures may take place. The specifica-
tions require excavation of the foundation key to "the lines and
grades shown. The engineer may change the depth of the core trench
depending on the gradation or character of the soils encountered"
(Reference 25). The specifications appear to attempt to preclude any
additional payment for this. Additionally the specifications point
out to the contractor that additional cohesive fill may be required
from an off-site location at a negotiated unit price.
In order to assure ease of administration without the problem of
negotiated extra orders, it might be well to provide for a pay item
for foundation key below the plan elevations shown on a unit price
basis and an item for additional cohesive fill on a unit price basis.
This will provide a contingency item in the bid and permit field
personnel to readily administer such a contingency.
Further, during excavation and placement an experienced soils
engineer should be on site or as a minimum on call with scheduled site
visits to assure quality control. The specifications might also
include a general statement as to what condition would require addi-
tional foundation key excavation.
190
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The embankment and foundation stability has not been evaluated
herein under the assumption that the engineer has done so given the
fact that the soils problems have been identified. A more detailed
soils evaluation is not warranted because the embankment failure
appears to pose little or no threat to health or public safety and
has no irreversible adverse environmental impacts.
Issue 11-7. Should Final EIS completion await the site designation
process of the County?
This issue was raised by the Adams County Board of Commissioners
(Letter #40) and by others. Basically, EPA has the option of either
proceeding to the final EIS in order to complete its NEPA require-
ments before the local site designation process is begun, or awaiting
its completion before finalizing the EIS. EPA has carefully considered
both options.
It is EPA's belief that the situation would be better served
by first completing the EIS. This EIS process has developed a
considerable amount of technical information regarding the proposed
B-2 site as well as other sites. EPA has developed its own judgments
as to the merits of this and other sites.
More importantly, EPA is detailing in this EIS (Appendix A of
Volume II) the necessary mitigating measures in the form of grant
conditions which EPA believes will minimize the identified environ-
mental problems. This information will allow decision-makers at
the local and state level to better decide whether the project with
the added conditions will be acceptable.
EPA believes, based on available information, that given a
few additional mitigation requirements, a great many sites could be
used for this project. Similar mitigating measures would be necessary
in most or all alternative sites to make the project acceptable.
The merits of alternative sites, including the present Lowry
Bombing Range, have been presented under Issue IV-1. Thus the local
county decision-makers will also have the opportunity to evaluate
the relative prospects for locating the site elsewhere.
A final reason for proceeding with the final EIS is the extensive
amount of time already consumed by this EIS preparation. EPA has
taken the time to collect additional data enabling a better resolution
of the issues identified in the draft EIS. EPA also feels that it has
a responsibility to complete the EIS process within a reasonable
length of time. We believe the resolution of the siting issue is
complex, requiring much institutional cooperation among the Metro
191
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Districts, local residents, the county and the state. EPA is con-
cerned that awaiting resolution of this process could delay the EIS
indefi nitely.
EPA will not allow Step II and III design and construction funds
for the project to be spent, however, until the local site designation
issue is resolved. If convincing evidence for a site reevaluation is
forthcoming, EPA will then prepare a supplement to the final EIS
presented here.
ISSUE 11-8. How does the loss of farmland productivity from Site B-2
compare with the agronomic value of the sludge?
The loss of productivity to Adams County both financially and in
terms of wheat production is estimated under Issue 11-11. This loss
of productivity must be balanced by the gain in fertilizer and soil
conditioner benefits which will accrue by the addition of some
TOO mt/day [110 tons/day] of sludge to the various sites to which
it is applied.
A rough estimate of the fertilizer value of sludge can be made
based on the value of the sludge nitrogen content. The value of
nitrogen in commercial fertilizers was estimated in Reference 26 and
Appendix D of Volume I to be about $0.55/kg [$0.25/lb] in 1974. If
air-dried sludge has a nitrogen content of approximately 3.5 percent,
then the value of the nitrogen is:
1.0 x 10^ kg/day x 0.035 x $0.055/kg x 365 = $703,000/year.
[2.2 x 105 lbs/day x 0.035 x $0-25/1 b x 365 = $703,000/year]
Current prices for bulk fertilizer in the Denver area average
between $160 to $200 per ton (Reference 27). This price is relatively
insensitive to the different mixes of N, P, and K, as long as the
fertilizer is high-grade (i.e., mixed in proper proportions satisfying
different uses). Since the N:P:K amounts to roughly 30-40 percent
of the total material by weight, the value of the nitrogen and
phosphorus in the sludge can be roughly estimated, assuming sludge
has about 5 percent N and P, to be about $20 per ton. At this
price, the 35,000 tons of sludge dried to 50 percent solids dryness
would be worth approximately $1,400,000 per year.
The actual market value of the sludge product would be substan-
tially less, based on current prices for bulk dried sludge. Tables
8 and 9 show the values for sludge sold by municipal plants across
the country (Reference 28). The authors of this publication estimate
that a reasonable selling price for the sludge in bulk is $4 to $10 per
192
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Table 8. SLUDGE
DISTRIBUTION PRACTICES FOR
MUNICIPALITIES
(From Literature Review
d)
Location
Year
0utputb
T reatment
Nutrients'" Distribution
Price
Remarks
Aaarillo, Texas
1961
nad
A1r dried,pulveri
zed, unbagged
na
user hauls
$3/cu yd
Annual revenue =
$3000.00. Word of
mouth advertising.
Demand exceeds supply
Baltiaore, Maryland
1961
na
head treated,
granulated
N=3%
P=2*
sold to jobber
for delivery
$5.00-$7.50
per ton
Battlecreek, Michigan
1960
200 tonse
na
N-2.82
P=2.6%
100 lb. bags
$2.00/
bag
Battlecreek Plant
Foodf
Beltsville, Maryland
Birmingham, Alabama
1973
1960
50 tons/day9
48,000 cu hd
mixed with wood
chips, windrowed
na
H,P0.=2.7%
MO. 2%
N=0.9t
N=2.25*
P=3.0%
municipal use no charge
only,user hauls
1)ground l)$3.50/cu yd
2)unground 2)$1.50/cu yd
demand exceeds supply
still operating in 1970
Boise, Idaho
1960
200-350 tonse
na
N=3.59%
retail outlets
$3.15/80 lb
BI Organic^
Farmers are largest
users
Bristol, Connecticut
1960
600 cu yd
1)air dried
2)pulverized
M=2.69%
P=2.52%
na
. 1 )$1.60/cu yd
2)$.25/bushel
Sludge soil
Conditioner'
Central la, Washington
1961
na
open air dried
some ground & bagged
na
user haul
' no charge
Municipality takes loss
but improves public
relations
Chicago, Illinois
1975
25,500 tons
Imhoff treatment
sand & gravel
drying beds
stockpiled
N=4%
P=6%
K=0.1%
24 cu yds or
more delivered
user load &
haul
no charge
Nu-Earthf
Duluth, Minnesota
1960
44 tonse
na
N=U
P=1.5%
100 lb bags
$1.00/bag
Soil conditioner-
sewage sludge ferti-
lizer
a. Source: Reference 28
b. Ory tons or cu yd per year unless otherwise noted
c. Expressed as percentage by weight.
d. Not available g. Wet sludge (221
e. Met or dry basis cannot be determined for reference solids)
f. Product name
-------
Table 8 (Continued)
Location
Year
Output
T reatment
Nutrients Distribution
Pri ce
Remarks
Enumclaw, Washington
Fargo, North Dakota
Fond Ou Lac, Wisconsin
Fort Wayne, Indiana
Houston, Texas
Indianapolis,
Indiana
Jasper,
Indiana
Kirkland,
Washington
Lewis town,
Pennsylvania
Los Angeles,
California
Mi lwaukee,
Wisconsin
Mobile,
Alabama
New Brunswick,
New Jersey
Oklahoma City,
Oklahoma
Omaha, Nebraska
Oshkosh,
Wisconsin
1961
na
1960 12,000 tons
1960 2,000 tonse
1960 3,000 tonse
1972
1960 50 tons
1960 50 tonse
1961 na
I960 na
1973 36,000 tons
1968 80,000 tons
1968 na
I960 21,000 tons
1960 na
1960 500-600 tons6
1960 600 tonse
na
na
na
na
heat dried
na
Filter Dried
Drying beds in
glass buildings
Windrow com-
posting
heat dried
na
na
na
na
na
na
100 lb. bags $1.50/bag Population=3000
Income pays for chemicals
N=2*
P=2S
N=2.5%
P=2.53J
N=5%
H3P04=4%
N=5.0%
P=2.7%
N=5.89Z
P=3.49S>
na
N=1.0K
P=1. %
K=0.01%
N=2.66%
P=2.1ffi
N=l. 77L
P=2.1«
na
N=2.K
p=i.a
N=2.09S
P=2.653S
na
$.50/1000 lb
1)80 lb bags 1)$2.00/bag
2)bulk 2) $ 18.75/ton
na
competitive bid, $21.00/ton
bagged for resale
by contractor
na
Fond Ou Green
Hou-Act1nite*
Indus^
na
user hauls
$3-5/cu yd
$6-22/cu yd
nominal fee
Population 5,500
Price depends on quality
bought/bagged
for resale by
Kellogg Co.
Distributors
deal 50 lb.bags
25-50 lb bags
na
sel1 at beds
for $l/ton
1) bulk
2) bag
sold locally
from plant
Retail price
$1.59/50 lb bag
Nitrohumus
Retail price Milorganite
$4.50/bag Demand exceeds supply
M0BILEAIDf
no charge
na
na
1)$15/ton
2)$1/100 lb.
$0.25/cu yd
$2/cu yd
ground
downward trend reported
in 1960.
still operating 1n 1970
still operating in 1964
distribution through
contractor
Oshkonite^
-------
Table 8 (Continued)
Location
Year
Output
Treatment
Nutrients
Distribution
Price
Remarks
Pennsauken,
New Jersey
Roanoke,
Vi rginia
San Diego,
California
Santa Fe,
Mew Mexico
1960
1960
1970
1960
200 tons
1,688 tons
500 tons
ground & unground
mixed with seaweed
and leaves, air
dried
bagged S ground
na
N=2.5%
P=1.5*
na
na
1)80 lb bags
2)bulk
Park Dept.
100 lb bags
1)$2/bag
2)$18.75/ton
not for sale
$2.50/bag
All is used for Mission
Bay Development
Schenectady, 1960 250 tons
New York
Seattle, 1961 na
Washington
Sheboygan, 1960 1000 tonse
Wisconsin
Springfield, 1960 na
Illinois
Vancouver, 1961 na
Washington
Wichita, 1961 5000 cu yd
Kansas
Winston-Salem, 1971 na
North Carolina
flash dried
air dried
air dried
glass covered
drying beds
Digested, air
dried then flash
dried in rotary
unit
N=23S
P=2«
K=0.5X
na
N=1.9ffi
P=1.658
na
N=2.1%
P-0.2%
na
65 lb bags
user hauls
city use only
bar or bulk
user haul
80 lb bags
1 )user haul
2)del ivered
bulk or in
50 lb bags
$1/65 lb bag 0RGR0T
still competing in 1970
no charge
$.50/80 lb
$5.75/ton
no charge
$2.50/bag
1 )$2/cu yd
2)$3-4/cu yd
$30/ton bulk
$1.05-1.95
bagged
main users-fanners, park
board, golf courses
Wichita Soil Conditioner
Operating since 1958
-------
Table 9. SLUDGE DISTRIBUTION PRACTICES FOR MUNICIPALITIES
(From Telephone Review)
Location
Output3
Treatment
Distribution
Price
Nutrient
Dates of
Operation
Remarks
Aaarlllo, Texas
2,000
air dried on land Kentucky &
and sand beds Tennessee
heat dried by Relco
nab
N=2-
P =
K =
-3%
2%
0
1960 - now
air dried sludge sold to
Relco Inc. for $l/ton
Birmingham,
Alabama
na
1)flash dried
2)air dried
user hauls
1) bagged
2) bulk
T)$1.50/lb
2)$1.50/cu yd
N =
P =
K =
1.7*
0
0
1953 - now
Grow-Goc private company
failed so City takes loss
Corpus Christi,
Texas
na
vacuum filtered
rotary kiln
user hauls;
bagged & sold
at plant
$2/80 lb bag
1 $10/cu yd
H =
2.5 %
1936-55
air dried
1955-now
vac filtered
high costs may cause shift to
land application of wet sludge
Ft. Lauderdale,
Florida
2,500
heat treat to
40% solid cake
dispose in
landfi11
free for
asking
N = 0
P = 0
not really
compost
may go to compost when solids
increase to 50 tons/day
Houston,
Texas
25,000
heat drying of
activated sludge
by contract
with broker
$21/ton
na
1950-now
Hou-Actini tec
Mi lwaukee,
Wisconsin
70,000
kiln dried
activated sludge
distributor
hauls
$65/ton
N =
P =
K =
6%
2i
02
1926 - now
Mobile, 45-30.000
Alabana
air dried
user haul
free
na
1948 - now
market 100%
Oklahoma City,
Oklahoma
na
air dried
901 landfill free
10% user haul
N =
P =
K =
0.5%
0
0
1950 - now
Oshkosh,
Wisconsin
na
air dried what user haul
could be distributed;
trucked the rest to landfill
$.25/bushel
$3.00/cu yd
na
1960-1972
could not distribute the
dried sludge
San Diego,
California
10,000
air dried
stacked
park dept. not for sale
uses to develop
Mission Bay
na
1960-now
private company tried to
bag & sell but failed
Schenectady,
New York
130
furnace dried,
digested primary
user haul $1.65 lb bag
N =
P =
K =
2%
2%
0
1960-1973
0RGR0c,not much demand,
losing money so not drying now
So. San Francisco na
California
wet sludge nixed
with rice hulls
& coffee grounds
sold in bulk $3.00/cu yd
to distributor fob
).69-.99/bag
N =
P =
K =
2%
0.5%
0.25%
1950-now
Tilloc Company
The Dalles,
Oregon
10 cu yd
per day
air dried ground
user hauls
free
na
7-1975
now apply wet sludge on
airport
a. dry tons per year
b. data not available
c. brand naae of product
-------
ton. At these prices, Metro's potential return from the marketed
sludge would be in the vicinity of $288 to $900,000/year.
By comparison, the expected loss in revenue annually by use of
the B-2 site for sludge production is estimated at $105,000 per year.
An additional amount of net loss of about $15,750 must be added as
lost tax revenue to the County (Reference 51).
Based on the above figures, the Metro operation should add value
to the area economy. If Metro were to bag the dried product for
small home and specialty users as is done in many other communities,
a ton of dried sludge product could sell for as much as $40 to $60/ton
(Reference 28). This would create a market value of perhaps 3 million
dollars per year, although the extent of market demand would limit
how much of the material could be sold in the bagged form. Metro
could also work in conjunction with a fertilizer distributor to
fortify the dried sludge to high-grade quality fertilizer; this would
result in a much higher value operation. Metro has been investigating
this possibility although it is very preliminary at this point
(Reference 29). In California, for example, Los Angeles County sells
its sludge compost to the Kellog Supply Company under a long-term
contract* The company then retails a bagged product through K-Mart
outlets, nurseries, etc.
The overall balance does appear promising to the Adams County
area for future increased economic value then, in spite of the land
and agricultural productivity loss at site B-2.
A number of other factors must be considered when assessing
the sludge worth. First, a disadvantage of using sludge for its
fertilizer value is its low density, thereby requiring the transport
and application of relatively large volumes of material. This in-
creases the handling costs. Second, sludge is not a balanced ferti-
lizer, so supplemental fertilizers must be added to supply the
potassium requirements of crops. These disadvantages are offset to
some degree by the soil conditioning qualities of sludge. It is
expected that addition of dried sludge to the soil will improve its
moisture-holding capacity, increase its humus content, and decrease
the soil's susceptibility to wind erosion. A study by the U.S.D.A.
in Beltsville, Maryland, found that sludge and sludge compost applied
to silt loam soil at rates of 40 and 240 mt/ha [17 and 106 tons/ac]
increased its moisture-holding capacity, its cation-exchange capa-
city, and levels of phosphorus, nitrogen, salinity, and chlorides
(Reference 30). At present, it is impossible to put a value on these
various aspects of sludge use.
One final consideration when considering the fertilizer value of
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sludge is the likelihood that commercial sources of nitrogen will
grow increasingly scarce and expensive in the future. This is
directly related to the rising cost and scarcity of natural gas
from which much commercial fertilizer is produced. As this trend
continues, the attractiveness of utilizing the resources available
in organic fertilizers will grow. Again, it is impossible to put a
dollar figure on this consideration at present but it is very likely
that the relative value of using sludge instead of commercial ferti-
lizers will continue to increase. Overall, EPA believes that the
effort to encourage recycling of nutrients and soil-building materials
through this product will have a beneficial effect on the entire
Denver metropolitan area.
Finally there is a potential savings to the Metro District of
perhaps $500,000/year over the current disposal system that will
make this project even more desirable.
ISSUE _II-9. Are land uses in the vicinity of site B-2 compatable
with the proposed Metro operation?
The present land use around the site is primarily dryland wheat
farming. This use is not expected to change in the foreseeable
future. This activity is quite compatable with the sludge drying and
distribution site. The site requires a large amount of open space
away from dense residential or commercial developments and there is
an advantage to having the site near the sludge markets. Because
of the wide range of potential markets, no site can be ideally located,
but utilization of sludge as a fertilizer and soil conditioner on
farmland is one of its major potential uses. Odors and windblowing
of sludge (Issues 11-3 and 11-5) are not expected to be problems.
A measure of the likely conflict between the proposed sludge
drying operation and future residential/urban development would be
the likely rate of urban development for this portion of Adams County.
The Denver Regional Council of Governments has developed a land use
projection model to estimate future land uses in the Denver metro-
politan area. Current projections for the year 2000 show that this
area would still be largely rural. DRCOG's intention policy-wise is
to maintain a 2.35 million person total metropolitan population by
the year 2000, encouraging infill and development close to the
existing urban areas. Other private investment decisions may well
be at odds with these policies; to a great extent the Adams County
Commissioners will have much to say about the future growth in this
area in the next 25 or so years. The proposed use of site B-2 for a
basically agricultural operation does appear to conform to the
DRC0G overall land-use plan.
One potential land-use conflict which has aroused concern is the
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proposed Adams County general avaiation airport which may be located
about 3 to 5 km [2 to 3 miles] west of the site. The primary concern
is that the sludge drying beds may attract insects and birds which
would be a hazard to aircraft. This problem is discussed in the next
section; the conclusion is that few insects or birds will be attracted
to the site. This factor, combined with the distance of the site
from the airport, should obviate any bird problem. Another considera-
tion is that commercial, industrial, and residential development may
follow the airport development and be incompatable with the drying
site. In general, however, it is desirable to minimize development
near airports. The drying site will help provide open space and dis-
courage development around the airport, which is an asset, not a
liability.
A final possible incompatability of the airport and the sludge
drying site is the generation of fog by the sludge lagoons. Fog
generally is not formed in the Denver area except occasionally during
the spring and fall (Reference 31). This fog usually forms in low-
lying areas near water when cold fronts pass through the area. The
low humidity which generally prevails effectively prevents the
formation of widespread, dense fogs. However, fog will form over
pools of free water under clear, cool, windless conditions. Such
pools will occur at the site after fresh sludge is introduced to
the beds. This type of fog generally remains directly over the beds
and does not extend more than 3 to 6 m [10 to 20 ft] above the
water surface. Winds in the area are less than 5 kph [3 mph] only
10.6 percent of the time; the relative humidity is above 80 percent
only 13 percent of the time. For these reasons, generation of fog
at the site is very unlikely to become a problem, even upon the rare
occasions when it occurs.
The environmental assessment by the consulting firm CH2M-Hi11
indicated that a small portion of site B-2 near the southeast corner
consists of a relictual prairie area. Evidently this area has not
been farmed because of the drainage. EPA will discuss with the Metro
District the possibility of preserving a portion of this area in its
natural state. We will recommend that Metro consult with the State
Division of Wildlife on the matter.
ISSUE 11-10. Will insects and birds be attracted to the B-2 site and
create a future hazard for airport traffic?
Insect infestation at the drying and distribution site could
pose a health hazard and be a nuisance to nearby residents. A
qualified entomologist has been retained by Metro to investigate and
implement any necessary measures to control insect infestation at the
site. With proper control, insect populations in the stockpiled
sludge can be kept to a low enough level to virtually eliminate any
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hazards or nuisance which they might cause.
Birds attracted to the site could be a major hazard if a regional
airport is located nearby. The proximity of open dumps and sanitary
landfills to airports has caused serious problems to aircraft because
of birds attracted to them at some areas around the country (Reference
32 and 33). A study conducted by EPA's Office of Solid Waste Management
Program found that the attractiveness of such sites was directly
related to the availability of food, water and, to a lesser extent,
suitable shelter (Reference 32). By converting open dumps to sanitary
landfills, availability of food and water is reduced, and the bird
problem is consequently lessened. The study did not consider sludge
drying beds; however, the conclusion that food availability is a
major attractant implies that the Metro Denver site would not be
particularly appealing to birds. The only food source which might
be available at the site is insects, which will be kept to a minimum
by proper control. The intermittent existence of free water on the
drying beds when sludge is first introduced may be something of a bird
attractant, but this aspect is felt to be secondary to the availability
of food and is not expected to attract many birds. The experience of
smaller sludge drying bed operations and of the San Jose sludge
lagoons has been that birds and insects are not attracted to this type
of environment.
A similar issue has been raised with a newly constructed waste-
water lagoon near an existing airport near Boise, Idaho. Pilots
have become concerned that just the presence of open water could
pose an attractant to migrating birds.
There always is the possibility that some birds could be attracted
by the particular facility and result in a bird-airplane strike.
However, every other open water pond or reservoir would create a
similar hazard. EPA does not believe at present that there is suffi-
cient evidence to indicate that birds would be attracted in signifi-
cantly large numbers to the. sludge drying site. Near Travis Air Force
Base in California, for example, a 120 ha [300 acre] lagoon was
recently constructed. The Air Force did insist upon steep-walled
sides for the lagoon as well as weed control, to minimize the poten-
tially available food for aquatic birds. Many of America's largest
airports are located very close to productive bodies of water (San
Francisco Airport, Logan in Boston, etc.). It does not appear that
the mere presence of the sludge drying beds and associated reservoir
located at a distance of some 3 to 5 km [2 to 3 miles] from the
potential airport can be considered an immediate or unnecessary hazard
to aircraft. EPA will require Metro to utilize weed control on the
reservoir as well as the rest of the site to minimize the attractive
potential to birds (see Grant Condition #8).
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ISSUE 11-11. Is this project of such an untested nature as to require
further research before the project should be implemented?
Concern has been expressed that the current project is not
feasible or at least is untested. However, most aspects of the pro-
posed system have been widely used by other agencies, on smaller
scales and with minor variations. Pumping of liquid sludge is a
common practice, and use of the most up-to-date engineering design
and practice (Reference 34) will enable a reliable and safe pipeline
to be built and operated. Sludge drying beds have long been widely
used, and their design principles are well known. Dried sludge has
been fairly widely used as a soil conditioner/fertilizer with great
success under a number of conditions and after various types of
treatment (see Tables 8 and 9 under Issue 11-8 which identifies
municipalities across the country marketing or distributing various
forms of processed sludge to agricultural users).
It is true that most other drying bed/soil conditioner systems
used by other plants have been much smaller in size than the proposed
project. Obviously, then, this variable cannot be tested any further,
but there is no reason to believa that the proposed project is too
large.
In comments on the draft EIS, the following areas were identified
by individuals or agencies as being areas of unknowns or uncertainty
that might require further research:
soils and groundwater data to assess impacts at the site;
the "success" of the project in terms of developing a market;
the effects of sludge applications on dryland farms;
testing to determine the value of the fertilizer content;
proper application rates of sludge and heavy metal accumu-
lations in the human food chain;
sludge injection requirements during winter months;
long-term soils productivity;
the method of operation at the site (drying times, loading
rates, etc.);
the best kind of digester performance (mesophilic vs.
thermophil ic);
research on industrial pretreatment;
heavy metals toxicity to plants;
the means of controlling sludge applications.
Some of these are genuine research areas; others already have
research data available. Each will be discussed in turn.
a) Soils and groundwater data are now available and are dis-
cussed under Issue 11-1 and II-2. Further data would not be essential
201
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at this point in time; it is believed Metro can adequately protect
the groundwater with the proper lining techniques.
b) "Success" can only be determined after the project has been
in operation. Other similar operations (see Issue II-8) indicate
success can be achieved.
c) A genuine research issue is the practicality and feasibility
of using sludge on dryland farms. These farms can tolerate only a
low level of fertilization; however, since the fertilizer content of
the sludge is known, application rates of sludge can be kept within
the limits which the dryland soil can accommodate, and no problem should
ensue. In fact, it is quite possible that the output of dryland
farms will be improved because sludge increases the moisture-holding
capacity of the soil. In any case, if signs of over-application
appear, sludge use can be discontinued on dryland farms. Sludge has
been used with no harmful effect in several irrigated or high-rainfall
situations, and its use on irrigated farms has been proved beneficial
(References 38 and 35). The same is true for parks and grass areas.
Metro currently does not expect to supply much sludge to dryland
farms; irrigated farms, sod farms and municipal parks would preferen-
tially receive the sludge. The research and demonstration areas
on site could be used to test the value of using sludge on dryland
operations.
d) The fertilizer content in sludge is readily known; the
actual effect of using sludge can only be appraised by in-the-field
experience. There is considerable country-wide research and practical
experience to indicate the beneficial impact of using sludge (see
(e) below).
e) The Metropolitan Sanitary District of Greater Chicago is
currently using sewage sludge to reclaim strip-mined land in Fulton
County, Illinois (Reference 36). The district intends to grade the
land to control runoff, increase the soil humus by the addition
of sludge and restore the land to full productivity. Eventually,
some 2,898 ha [7,156 acres] is to be reclaimed. In 1972, 108 ha
[268 acres] received 661 mt [729 tons] digested sludge. Operations
continued in 1973, 1974 and 1975 with 27,500 mt [30,388 tons] of
solids being applied to 695 ha [1,713 acres] in 1975. This is a
loading rate of 39.6 mt/ha [17.7 tons/acre]. The sludge is applied
in liquid form, being either sprayed onto the land or injected into
the soil.
The district conducted a four year monitoring program from 1971
to 1974 to assess the impacts of the project on surface and ground-
water, on crops grown at the site, and on soils. Conclusions from
the program include: (1) surface waters in streams receiving runoff
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from the site have been unaffected by the sludge application; (2)
groundwater monitoring wells near the site show no evidence of
groundwater contamination; and (3) after three years of sludge
application, metal levels in corn grown on sludge-amended soils show
no significant increase (Reference 36).
The Council for Agricultural Science and Technology (CAST) has
recently reviewed the potential problems, limitations, and constraints
which should be considered when applying sludge to land (Reference 38).
The basic conclusion of this report is that the potential exists for
harm, but with proper management and monitoring, adverse effects
can be minimized or avoided. The study recommends various procedures
and monitoring programs which should minimize the chances of adverse
effects from sludge use on crops.
Enough data is available to indicate that the proposed Metro
project should be allowed to proceed if certain precautions are taken.
Monitoring of groundwater at the site is discussed in Issue II-2.
Rates of application of sludge to soils should be limited to that
quantity which supplies sufficient nitrogen for plant growth. This
generally results in application rates of from 5 to 40 mt/ha [2.2
to 17.8 tons/acre] (Reference 38). This rate should limit the
application of potentially toxic metals to levels that are of no
concern except with sludges having excessively high metal content.
To assess long-term metal accumulation, the soils on a representative
tract of land receiving the highest sludge loading recommended should
be sampled every five years to determine metal content. If signifi-
cant increases are found, sludge application could be discontinued or
reduced as needed.
f) Metro does not now plan to apply sludge during winter months.
The basin capacity includes three months of storage for winter months.
Metro's research and demonstration areas could be used to test
wintertime applications.
g) While there is no formal long-term soils productivity study
available for sludge use, sludge applications on soils for the last
10 to 15 years do not indicate any drastic effects. Such a research
effort would require cessation of land application of sludge nation-
wide for perhaps 25 to 50 years. EPA does not believe the potential
hazards so far indicated warrant such a drastic moratorium.
h) Many of the unanswered questions about on-site operations
could best be resolved through actual operating experience. EPA
believes that once it has been established that the Metro project
is reasonably designed and will work based on best available infor-
mation, there is no reason to further delay the project. The dis-
cussion under Issue 11-12 argues that drying capacity appears
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satisfactory; Metro's Greeley test data indicate that sufficient dryincj
of sludges similar to Metro's has occurred in shorter times than the
project design calls for.
i) The best form of digester performance is also a potential
research area, but one that can be done after project implementa-
tion. Metro is interested in testing the thermophilic mode of digester
operation as a research effort. The success of the project is not
dependent on the outcome of such research, however.
j) Industrial pre-treatment to lower heavy metal content in
Metro sludge will be ongoing. EPA national policy now is to require
industrial pretreatment where it is practical. Since the heavy metal
concentrations in Metro sludge are relatively low, the success of
these further removals will not affect the overall design of the
solids drying project.
k) He^tvy metals toxicities to plants are being extensively inves-
tigated by various~institutions such as agricultural colleges, the
U. S. Department of Agriculture and others around the country.
Valuable corroborative and area-specific data could be achieved if
Metro District were to conduct similar research experiments on
plant toxicity on the drying site.
1) Means of controlling sludge application is a current institu-
tional problem, but one under consideration now by the State of Colo-
rado (see Issue V-4). Reasonable application rates and requirements
for applicators and distributors will be part of the regulations
being developed by the State. While proper rates may have to await
actual experience, it is believed that conservative estimates are
being incorporated into these regulations. The Metro experience
will be valuable in setting future standards for other municipal
operations of the same kind.
It is EPA's belief that none of the areas of needed research
cited above are obvious or alarming enough to require delay of this
project. To the contrary, going ahead with this project will provide
some valuable answers to the research questions posed for the semi-arid
Colorado situation.
ISSUE 11-12. Is the drying bed capacity sufficiently designed?
The drying beds have been designed to handle the 1985 sludge
production from both the Denver Northside and MDSDD#1 plants. This
is expected to be 151 mt/day (160 tons/day) before digestion and
100 mt/day [110 tons/day] after digestion (Reference 26). The liquid
sludge from the digesters will be pumped to the site at a solids
concentration of approximately 2.8 percent, resulting in the
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transport of some 3470 m day [917,000 gal/day] of water to the site.
Plant effluent used to periodically flush the sludge pipelines will
raise the total to about 4160 m3/day [1.1 mgd].
At the site, 243 ha [600 acres] of drying beds will be used
to dry the sludge to about 40 to 50 percent solids. The total
volume of water which needs to be removed annually if the sludge is
dried to 50 percent solids is:
4160ffii. - o.o X 105^a x x 365 = 1.48 x 106 m3/yr
[1J x 106 df^ - (2-2 x 1C)5di7 x 8.341 lb x 365 = 3'92 x 1q8 9a1/^r]
To this quantity must be added the rainfall which impacts the beds
during drying. The average rainfall in the area is estimated to be
about 300 mm/yr [12 in/yr] (Reference 26). The evaporation rate required
to evaporate this quantity of water from 243 ha [600 acres] is:
3
1.48 x 106 m3/yr x ^ x x —p1 + 300 mm = 910 mm/yr
ro Qo Y in® nai/ * ^ ^ Y 1 acre 1 12 in
[3.92 x 10 gal/yr x 7AB gal x ^ ^ ^ x 600 acres x ft
+ 12 in/yr = 36 in/yr]
If this quantity of water must evaporate within nine months to allow
three months storage of dried sludge in the beds, then the evapora-
tion rate must be:
91Cx trr*= 1200® t36£ x ^ = 4(#]
The above calculations are conservative because some water is lost
by percolation, and a sludge dryness of 40 percent instead of 50
percent is acceptable. However, these quantities of water are
small in comparison to the total. Evaporation rates in the area are
estimated to range from 927 mm/yr [36.5 in/yr] to 1524 mm/yr
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[60 in/yr] (References 15, 26, arid 37).
On the basis of these calculations, it appears that sufficient
capacity is available at the site to dry the sludge. These calcula-
tions are valid only if careful operating procedures are followed.
Most importantly, a sludge crust on the surface of the drying sludge
must not be allowed to form. If it does, drying may be greatly
inhibited. Crusting apparently is more of a problem when water is
lost by evaporation rather than by percolation. Metro has indicated
that breaking up of a sludge crust on the surface will be a routine
operating procedure. Another factor is that surface runoff must
not be allowed to enter the beds; also, during wet years, drying
times may be extended beyond those predicted.
The estimates for drying times presented herein will be refined
once actual operation has begun. Tests conducted by Metro at the
Northern Colorado Research and Demonstration Center at Greeley, Color-
ado, indicate that faster drying times may actually be achieved.
Tests were conducted using four 30 m x 30 m [100 ft x 100 ft]
earthern drying basins similar to those to be constructed at the
proposed drying site. Two types of sludge were used, an anaerobically
digested primary sludge from the Denver Northside Plant, and an
anaerobically digested mixture of primary plus secondary sludge from
Ft. Collins, Colorado. These two sludges are expected to closely
represent the type of sludge that will be dried at the proposed site.
Both sludges were found to have similar drying rates. The sludges
were loaded on the beds at depths of 25, 76, and 61 cm [10, 31, and
24 inches] and were allowed to dry to a 60 percent solids content.
The 25 cm [10-inch] loadings dried within 95 to 96 days, the 76
cm [30-inch] loading dried within 149 days, and the 61 cm [24 inch]
loading dried within 117 days. These drying times are considerably
quicker than those that would be predicted based on the assumptions
contained herein. However, it must be noted that leaching rates
in the initial days of drying were considerably higher than those
that will occur at the center with lined beds. The quantity of
water* leached was not great compared to the quantity evaporated on
the beds loaded at 61 and 76 cm [24 and 30 inches].
ISSUE 11-13. How soon will additional capacity be required at the
sludge basins, and will more land be required?
The assumptions of the preceding section provide an estimate of
the maximum quantity of sludge which could be dried at the site.
Using the average value of the evaporation rate, and keeping all other
values the same, the quantity of sludge (in terms of dry weight) which
could be dried at the site (with a 9-month drying time) is:
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1225 (100 mt/day) = 102 mt/day [ 48 x (110 tons/day) = 111 tons/day]
1200 48.3
This quantity is the predicted ultimate capacity of the sludge
drying beds.
Predictions of future sludge loads are difficult to make
accurately mainly because of the difficulty in predicting future
population. Estimates of the future Denver regional population in the
year 2000 contributing to Metro's sludge load vary from 1,981,000 to
3,399,000 residents. (See Table 13, Volume I of the EIS). EPA's
policy has been to support no greater than the DRC06 policy growth
rate of 2,350,000 persons by the year 2000.
The design for this project is based on a projected sludge
load of 151 dry mt [166 dry tons] per day by the design year 1985.
This projected value has been adopted from the 1972 CH2M-Hill report
entitled: "Metro Denver: Sewage Treatment Plant Expansion."
(Reference 50). At that time the Denver metropolitan area was growing
at 4 to 5 percent per year. Using a value of 0.06 kg [0.13 lbs] of
solids generated per day per person, the 151 mt [166 tons] per day is
equivalent to a population of 2,550,000 persons for the year 1985
that would be serviced by this Metro facility. Since then the metro-
politan area growth rate has slowed to a 2 to 3 percent per year in-
crease. Assuming a 2.5 percent compound increase in population (the
DRC06 policy forecast rate for the Denver metropolitan area), the cur-
rent Metro District population of about 1,000,000 persons would
increase to only about 1,280,000 persons by 1985.
Because of anaerobic digestion that reduces the total mass of
generated sludge by about 35 percent, the actual sludge generated
for pumping to the offsite solids area would be reduced by a third
or so. Based on the above assumption, Table 10 indicates the popu-
lation, sludge generation, and sludge to be pumped to the offsite
solids area for the years 1977, 1985 and 2000.
Table 10. PROJECTED SLUDGE QUANTITIES PRODUCED BY METRO FOR THE
YEARS 1977, 1985, and 2000.
Sludge Generated Sludge to Basins
Year Population of Service Area (mt/day) (fTons/Day]) (mt/dav) (fTons/Day])
1977
1,000,000
89
[98]
61
[67]
1985
1,800,000
106
[117]
71
[78]
2000
2,350,000
138
[152]
94
[103]
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If growth occurs at rates higher than the predicted DRCOG
rate, the drying beds might not have sufficient capacity to handle
the year 2000 sludge flows. EPA will be determining air quality
criteria to insure that growth rates are compatible with air
quality problems. Even if the median predictions given in Volume
I, Table 12 of 2,780,500 residents were reached in the year 2000,
the year 2000 sludge quantity would be 161 mt/day [177 tons/day].
This is a slightly larger quantity of sludge than the beds are pre-
dicted to be able to handle by the year 2000.
There would be several ways to increase the capacity of the
drying beds without increasing their size. First, the sludge could
be pumped to the site at a solids concentration of up to 4 percent
rather than at 2.8# percent as presently envisioned. This will
involve a certain'amount of sludge thickening at the plant, with
return of supernatant to the treatment works. This will increase
the load on the treatment plant. Using a 4 percent solid concentra-
tion instead of a 2.8 percent solids sludge will reduce the water
content by 34 percent, which effectively increases the bed capacity
by 50 percent. Another technique is to decant the free liquid on
the top of recently loaded beds and use this liquid for irrigation,
dust control, etc., at the site. This technique will not be feasible
if good solids/liquid separation does not occur in the beds. Pilot
studies conducted by Metro on digestion of a 50-50 mixture of secon-
dary waste activated and primary sludge indicate that solids/liquid
separation does not take place (Reference 1). However, chemicals
could be added if desired to improve separation.
If, at some future date, more bed capacity is required, then
more drying beds could be constructed using another portion of the
810 ha [2000 ac] site. This may require a loss of some research
and demonstration areas. It is likely that this alternative would
be preferable to acquiring more land around the site. The calcula-
tions and possible mitigating measures discussed here indicate that
bed expansion will probably not be necessary before the year 2000.
ISSUE 11-14. Is Site B-2 at such a distance from potential markets
as to affect sludge marketability? Is there an optional site
elsewhere?
At present, Metro plans to dispose of its final dried sludge
product through the following markets: (1) Denver parks, (2) sod
farms, (3) mine spoil sites, (4) irrigated farms, and (5) dryland
farms. Each of these users is discussed in Section IV of Volume I.
In Section V of Volume I the relative fertilizer value of the sludge
nitrogen is calculated and compared to the energy cost of sludge
transportation. Using a cost of $0.08/m3-km [$0.10/yd^-mile], the
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break-even trucking distance was determined to be almost 100 km
[60 miles]. A large amount of farmland acreage is within this
distance of the drying/distribution center, as are sod farms and
Denver parks. However, this calculation should be considered with
caution, because of many factors affecting the actual present and
future value of the sludge (see discussion of Issue 11-8).
Because of the geographic diversity of potential markets, it
is impossible to select a site ideally located with respect to all
of them. Site B-2 is midway between the sod farms. It is 13 to 32
km [8 to 20 miles] away from the large irrigated farming areas along
the South Platte northeast of Denver. It may be somewhat distant from
the municipal market (32 to 48 km [20 to 30 miles]). A slightly more
favorable location closer to Denver from a market standpoint would
put the site into conflict with the urbanizing areas. The B-2 site
is approximately 13 km [8 miles] away from a railroad siding near
Manila. The site is also favorably located with respect to the sug-
gested Watkins strip-mining/gasification project.
EPA does not think a relocation of the site is justified on
market grounds, unless one of the potential uses were likely to
predominate. We have no evidence to indicate that this is the case.
As explained elsewhere (see Issue 1-6), Metro is considering storing
some anaerobically digested primary sludge on the Commerce City plant
site for Denver parks use. This would help relieve the burden of a
30-mile one-way trip to obtain sludge for city parks.
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 sludge by landfilling at the Lowry site. Metro estimates
that some 283,000 m3 [1.0 x 10 ft ] of storage space is available,
onsite for-storage of dry sludge. Assuming a density of 560 kg/m
[35 lbs/ft ] for sludge with a 50 percent solids content, this is
enough storage for approximately two years at a production rate of
100 mt/day [110 tons/day] of dry solids.
In the event that landfilling of the dried sludge becomes neces-
sary, the sludge will be trucked to the Lowry landfill located about
25 km [15,mi] from Site B-2. At a trucking cost of $0.08/m3 — km
[$0.10/yd — mi], it will cost $3.58/mt [$3.25/ton] to haul sludge
to the landfill, in addition to whatever landfilling charges are
imposed.
Disposing of sludge greater than 40 percent solids which has been
stockpiled for several years should pose no problems whatsoever in a
well-run sanitary landfill.
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ISSUE III
PRESENT OPERATION ISSUES
ISSUE III-1. Could the sludge disposal operation by Metro at Lowr.y
be continued or modified for future use, instead of the offsite solids
project?
One alternative to the proposed project is to have Metro continue
to dispose of sludge at Lowry in the same manner as they are doing at
present. Metro has listed the following major deficiencies in the
Lowry operation:
"1) It is much more costly than the proposed agricultural
reuse system.
2) Because of the massive quantities of sludge disposed of
at Lowry, the salt concentration in the soil has risen to the
point that crop production is practically impossible.
3) Because of the constant turning up of previously covered
sludge, fly and odor problems are increasing. By incorporating
the sludge to a two foot depth, hopefully, some of the salt,
odor and fly problems will be alleviated through the dilution
of deeper soil."
The present operation at Lowry could continue indefinitely,
but continued soil deterioration would occur. The current loading
rates of 82 mt/ha [30 tons/acre] per nine month period has rendered the
soils almost toxic to growth of everything but weeds in the short
term.
The recent Lowry groundwater study has found evidence of some
groundwater contamination in the immediate vicinity of the sludge
disposal sites (Reference 16). The problem is not yet serious, but
continuation of this type of operation over a period of decades may
cause significant groundwater deterioration. More details of the
impacts of the present Lowry operation are described in Sections
VI and VII of Volume I.
Were Metro to continue using the Lowry site, it would be done
so strictly as a disposal operation. Agronomic rates of sludge ap-
plication have already been exceeded, and any nutrients or soil-
building benefits from the sludge would simply be wasted.
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From the point of view of the City of Denver, who owns the por-
tion of the Lowry Bombing Range Metro is now using for sludge dis-
posal, this land is dedicated as a solid waste landfill site and will
eventually be used for that purpose (25-50 years). There is thus no
particularly severe impact from overloading the soils on the Lowry
site, since the landfill operation will also destroy the soil profile.
Offsite impacts such as groundwater contamination still could affect
downstream reaches of Murphy and Coal Creeks, particularly in the
shallow aquifers.
In the draft EIS, alternatives were suggested for using the
Lowry Bombing Range as a storage/drying area for distribution. Such
a system would depend on using much the same system as at present for
bringing the sludge to the Bombing Range. The critical problem with
this alternative lies with secondary waste activated sludge. This
sludge currently accounts for about 60% of all the sludge treated at
Metro. It is a difficult substance to dewater, using expensive chem-
icals and energy in the process. For a successful scheme to use
Lowry as a storage area, the sludge to be transported to the Bombing
Range must be both relatively dry (high cake solids percentage) and
stabilized (either anaerobically or aerobicall.y digested). It has
been the unfortunate experience of Metro that neither aerobic nor
anaerobic waste activated sludge dewaters well. In fact, dewatering
characteristics are worsened after stabilization. This means that a
system involving trucking of stabilized sludge to Lowry would be ex-
tremely expensive. It does not appear to be a satisfactory long-
term solution. The offsite project has the overwhelming advantages
that a) the cost of pipelining the dilute stabilized sludge is rel-
atively inexpensive and b) that the solar drying method is the only
feasible way to both dewater and make suitable for agricultural use
the waste activated stabilized sludge. The latter process is also
much cheaper than any mechanical dewatering process.
In summary, it appears that long-term continuation of the current
disposal methods or the method suggested in the draft EIS at Lowry
are unsatisfactory from either an environmental or financial stand-
point. The disposal method now used at Lowry is adequate for the
short-term, but EPA feels that a long-term environmental goal of
recycling both sewage sludge nutrients and solid wastes should be
preferred.
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ISSUE IV
ALTERNATIVES
Issue IV-1. Should another site for the offsite solids project,
particularly the Lowry Bombing Range or the Rocky Mountain Arsenal,
have been preferentially chosen?
A number of people have raised the question of why Site B-2 was
chosen instead of other sites, especially ones at either the Rocky
Mountain Arsenal or the Lowry Bombing Range. Metro has made re-
peated attempts to obtain land within the Rocky Mountain Arsenal,
and has been told by the Department of the Army that no arsenal land
will be made available until the demilitarization of chemical war-
fare agents has been completed. It appears at present that no ar-
senal land will be released to public use in the forseeable future
as it is currently committed or scheduled to be committed to other
uses. The letters in Appendix C demonstrate the consistent refusal
on the part of the Army to allow the use of arsenal land for sludge
drying. The use of the Lowry Bombing Range is considered further
below.
Metro's consultants, CH2M Hill, did a comprehensive analysis
of eleven sites in Adams County to the north and east of the central
treatment plant (Reference 26). A number of factors were included
in this analysis and given various weighting factors in proportion
to their importance. Using this technique, the sites were given
numerical ratings indicating their relative suitability for the
drying and distribution center. Three sites were determined to be
favored over the other eight. In a subsequent report, Volume III
of the facilities plan, these sites were compared in more detail
(Reference 39). This analysis led to the selection of Site B-2 as
the preferred site. The selection of this site was based on the
expectation that it would involve the least amount of public inter-
action. In other respects, notably distance from the central plant
and distance from potential markets, Site B-2 was somewhat inferior
to the other sites. The sites were considered approximately equi-
valent from an environmental standpoint. The land use aspect, how-
ever, was considered important enough to outweigh these disadvantages.
Since this analysis was performed, more data have become avail-
able allowing a better assessment of the environmental impacts of
various sites. The most sensitive environmental issue is the potential
impact on groundwater beneath the site from sludge leachate. Site B-2
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is located in an area where impacts on ground and surface water are
expected to be minimal. This is discussed in Issues 11—1 and 11-2.
As noted in these discussions, there is no alluvial aquifer beneath
the site, and the nearest alluvial well is at least 2.3 km [1.4 mi]
from the eastern edge of the site. Also, the soils beneath the site
are largely silty clay and clay, which are relatively impervious to
groundwater flow. The few areas of more permeable sandy soils are
under the western side of the site, which is in the direction of the
fewest wells. Township 2S, Range 64W, in which Site B-2 is located,
has the lowest average groundwater pumpage of any area within the
39,800 km1- [15,500 mi^] area of the Denver Basin, according to the
Colorado Geological Survey. Finally, the site is on a ridge bisec-
ting two watersheds, and therefore receives runoff only from within
its own borders. The surface streams in the area are intermittent,
so the potential for surface water pollution is minimal.
These results indicate that Site B-2 is in fact relatively well
located with respect to minimizing water pollution, at least compared
to other sites in Adams County. Most of the other factors used in
the original site comparisons have not changed. It should be noted
that the distance of the site from irrigated farms and sod farms is
related to potential water quality problems, because these operations
are in areas of high groundwater use. This increases the likelihood
that leachate from the beds will contaminate groundwater supplies.
Minimizing this possiblity is considerably more important than prox-
imity of the site to these farms.
A more detailed comparison of Site B-2 with the Lowry Bombing
Range is also possible with more recent data. The U.S.G.S. has re-
cently conducted an assessment of the groundwater quality near the
present sludge spreading area and the Denver landfill area at Lowry
(Reference 16). This study found that subsurface conditions at Low-
ry are basically similar to those at Site B-2; that is, alluvium
ranging up to 7.6 m [25 ft] deep overlying undifferentiated Denver
and Dawson formations of mudstone, sandstone and lignite. The alluv-
ium consists of clay, silt, sand and gravel, and is thickest along
Coal Creek. The alluvium along Coal Creek also has the highest yield
of water to wells, up to 38 1/min [10 gal/min]. Except for along
Coal Creek, the alluvium has a small saturated thickness, fine grain
size and poor sorting, and wells usually yield less than 0.4 1/min
[0.1 gal/min]. This yield is still higher than the alluvium directly
beneath the site B-2, which is not saturated and thus yields no water
to wells.
Several observation wells tapping the alluvium in and near the
sludge disposal and landfill areas were examined for evidence of water
quality degradation. Five wells quite near potential pollution sources
were found to have markedly degraded water quality. No evidence of
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groundwater degradation could be discerned from wells tapping the bed-
rock. The conclusion drawn from this study is that some alluvial
pollution is taking place, but it has not as yet affected any bedrock
groundwater. This study is also discussed in Issue II-2,
The situation at Lowry thus appears to be very similar to that at
Site B-2 with respect to minimizing the potential for groundwater
pollution. Any site selected for the drying center should be located
in an area with minimal use of the alluvial aquifer for domestic or
other uses; and preferrably on a topographic ridge so surface runoff
is also minimized. Compaction of clayey materials to minimize leaching
would also be required at this site.
The land ownership situation at Lowry is somewhat complex, with
the City and County of Denver, the State of Colorado, the U.S. Air
Force, and private individuals all owning portions of the site. If
the bombing range is used, the most logical location for the 241 ha
[600 acres] of drying beds would be Section 32 of Township 45, Range
65W. This land is currently owned by the City and County of Denver.
This area also lies on a ridge separating two watersheds, and is the
site of the present sludge spreading operation. Two intermittent
streams border the site, Senac Creek on the eastern side and Murphy
Creek on the western side. There are two alluvial wells used for
domestic purposes less than 1.5 km [1.0 mi] from the northeast corner
of this site along Coal Creek. This is considerably closer than any
alluvial well is to Site B-2. Figure 6 shows the land ownership
pattern near the Metro Lowry sludge spreading operation.
This site has a number of advantages and disadvantages relative
to Site B-2. The advantages are as follows:
1.) The land is already being used for disposal of sludge, so
a significant change in land use will not occur. Also, because
of the large quantity of sludge which has been disposed at
this location, the land has at least temporarily lost much
of its original productivity. Construction of drying basins
will therefore not represent any loss of productivity.
2.) The site is adjacent to an ongoing landfill operation,
which will help limit development in the area and will obviate
the need for a large buffer zone around the sludge drying beds.
Also, the added attractiveness of sludge drying beds to birds
will be negligible compared to that of a landfill,
3.) Most of the land is already owned by public agencies, there-
by requiring less condemnation and purchase of private land than
required for Site B-2.
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FIGURE 6
OWNERSHIP MP OF LOWRY BOMBING RANGE NEAR METRO DISPOSAL OPERATION
B\ 21
Metro
Sludge landspreadlng
Operation -><*'
TL
(1300 ac)
1
Denver
Sanitary^ ia
Landfi 11
! * (150 ac)
V >0/
8
(
/KirAX
R.65W.
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The disadvantages of this site are;
1.) As previously noted, it is not far from at least two
alluvial wells used for domestic purposes, thereby increasing
the potential problem from any adverse effects of bed leachate
on groundwater,
2.) The site is located about 150 m [500 ft] higher in elevation
than Site B-2, which will increase the power required for pump-
ing sludge to the site.
3.) The site has somewhat more topographic relief than Site
B-2 and thus will require more excavation for bed construction.
This will increase construction costs.
4.) The City and County of Denver plans to eventually use its
entire 1,050 ha [2,600 acres] in the Lowry Bombing Range as
landfill. Denver has indicated an unwillingness to relinquish
this land permanently for the proposed use (see Letter #9), be-
cause this would substantially decrease the life of the landfill.
This could present a problem in acquiring land at Lowry; some
other parcels not now used for sludge disposal operations
would be required.
5.) The Lowry site is somewhat closer to housing development
than is Site B-2. Development is occurring about 10 km [6 mi]
west of the Lowry Site.
6.) The pipeline to Lowry will have to go through a more de-
veloped area than that to Site B-2. The route could, however,
follow existing right-of-ways and thus minimize the pipeline
construction impacts.
In terms of other factors such as distance to markets, aesthetics,
distance from Metro plant, and land cost, the two sites are approxi-
mately equivalent. Lowry is somewhat closer to Denver metropolitan
parks, but Site B-2 is closer to irrigated farms.
The Lowry Site clearly has a number of disadvantages with its
use, several of which may be difficult or impossible to resolve.
It appears from the above advantages and disadvantages that Site
B-2 is still preferable to Lowry for the drying and distribution cen-
ter. However, if for any reason Site B-2 cannot be acquired, the Lowry
Site should be considered as the preferred alternative because of its
lack of probable public controversy and present use for sludge dis-
posal operations.
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ISSUE IV-2. Why couldn't alternative technologies such as incineration,
thermophilic digestion, "the Swedish method", or pyrolysis be used in-
stead of the Metro offsite solids proposal?
This issue has been addressed in part in Volume I of the EIS
under Section II entitled "Alternatives". This section describes
the various technological alternatives considered by CH2M Hill, con-
sultants for Metro, by EPA's consultant Engineering-Science, and by
EPA itself. These discussions need not be repeated here. This sec-
tion will discuss technological solutions to sludge disposal raised
by individuals and agencies during the draft EIS review process.
Incineration - Pyrolysis of Wastewater Treatment Plant Sludges
Incineration of sewage sludge has been practiced in various forms
since the early 1900's. Air pollution problems, rising energy costs
and the advent of more advanced type sludges which are more difficult
to dewater have led to more advanced equipment designs (Reference 40).
Traditionally, combustion of sewage sludge has been viewed as a means
of disposal, but recently more attention has been given to recovery
of the energy in sludge. In order to efficiently combust sludge,
it must be initially dewatered to a solids concentration of greater
than about 25 percent. Sludges with a higher water content than this
will require auxiliary fuel for proper combustion.
The heat value of wastewater sludges ranges from 11,200 to 23,000
Kj/Kg [4,800 to 10,000 BTU/lb] (Reference 41). Most sludges require
auxiliary fuel to maintain combustion, which is the major operational
cost (Reference 40). Two types of incinerators are commonly used,
the multiple hearth furnace (MHF) and fluid bed furnace (F5F). The
FBF has a lower capital cost and lower auxiliary fuel requirements
than the MHF, but has more operating and maintenance problems.
Incineration was considered as an alternative in the original fa-
cilities plan and in the EIS, and was found to have high capital and
energy costs and to have potentially severe air pollution problems.
Incineration is the disposal method preferred by Metro if for any
reason the proposed drying and reuse system cannot be implemented.
Pyrolysis is defined as the gasification and/or 1iquification of
the combustion elements by heat, either in the total absence or in
the presence of a controlled amount of oxygen (Reference 40). The
useful product of pyrolysis of sludge is a fuel gas consisting of such
gasses as carbon monoxide, methane, hydrogen, ethylene and some high-
er hydrocarbons, as well as appreciable quantities of carbon dioxide
and water vapor. An ash is also produced which contains non-combust-
ible material and some fixed carbon not volatilized during combustion.
The yield and composition of pyrolysis products are dependent upon
the complex interactions of several variables making prediction of
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the final products difficult.
Pyrolysis has recently been investigated as a more efficient
alternative to incineration (Reference 40). Conventional MHF and
FBF units can be converted to pyrolysis reactors with minor changes.
Use of pyrolysis results in heat recoveries up to 82 percent greater
than that attained by incineration. Pyrolysis gas has a heat value of
up to 4.84 Kj/1 [130 BTU/standard cubic foot].
Pyrolysis has not yet received widespread testing and field ap-
plication, although it is being used successfully by some agencies.
This alternative was also considered by the facilities plan and in
the EIS, but was rejected because of its still unproven technology
for a project as large as this one.
Thermophilic Digestion
Thermophilic sludge digestion is distinguished from mesophilic
or standard digestion, in that digestion occurs at temperatures in the
range of 49-57°C [120-135°F] instead of 30-38°C [85-100°F]. Advan-
tages of operating in the higher temperature range are that pathogens
are more effectively killed, digestion proceeds more rapidly, and
increased quantities of methane gas are produced. Disadvantages are
that the process is more sensitive to slight changes in temperature,
digestion tanks may require insulation, more fuel is required for
heating, and more careful operation is required.
Thermophilic digestion has not been widely used in the past,
primarily because the disadvantages have usually outweighed the ad-
vantages. The most significant advantage of this mode of operation
to the proposed project would be the more effective reduction of
pathogens in the digested sludge. Metro already has anaerobic di-
gesters which were designed for and are operating in the mesophilic
range. These digesters may not be suitable for thermophilic op-
eration. Metro is interested in reevaluating the design of the
digesters to see if thermophilic digestion could be used. This op-
tion is, therefore, still open to Metro within the constraints of
the present digestion system design.
Swedish Method
We think that the "Swedish Method" referred to by several people
is the Clivus Mulstrum or other similar types of on-site waste disposal
systems recently developed. These systems utilize composting toilets
and washwater trickling filters with a drainfield for disposal rather
than discharge of wastes from a home to a central sewer system. Solid
and liquid wastes are composted in the system and the product is even-
tually utilized as a soil conditioner on-site.
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While this system has been shown to be feasible in numerous
Icoations, both in the U.S. and abroad, its use has been mostly con-
fined to a few individuals willing to try an alternate waste dis-
posal/utilization system, The system requires more user care and
maintenance than the current waste disposal systems used in the Den-
ver region and throughout most of the U.S. Its use on a widespread
basis will require much research into the health, public awareness
and acceptance, financial and technical aspects of its operation.
One of the stated advantages of the system is that it is cheaper
on a per capita basis to install than a sewer network with a central
treatment plant. However, in an area such as Denver where the
sewers and treatment plants have already been built, this advantage
does not exist.
In summary, widespread use of this system will not be feasible
in a large metropolitan area such as Denver for some time. A great
deal of research and public education will first be required. The
system does have many advantages, notably a greatly reduced water
requirement and recycling of wastes, and research into its use should
be pursued. This type of research is not, however, within the scope
of an agency such as MDSDD#1 at the present time.
ISSUE IV-3. Should EPA participate in separate planning and funding
for Denver Northside (DNS) Treatment Plant Sludge Disposal as suggested
by Denver?
This was not at issue at the time of release of the draft EIS.
The City and County of Denver indicated in their letter of comment
on the EIS (see Letter #33), that they are interested in pursuing
federal funding for separate sludge treatment and disposal at the
Northside Plant.
The identified benefits described in the letter by the Denver
Department of Public Works for a system of onsite sludge drying beds
is as follows (Reference 42):
"1. The Denver cost of pumping digested sludge to Metro
at a 5 percent solids concentration will be precluded;
2. The cost and use of chemicals (polymers) added to assist
in Denver sludge dewatering by Metro will be eliminated;
3. The total cost of dewatering the Denver sludge at Metro
(vacuum filtration) will be eliminated;
4. The cost of transporting the Denver sludge, plus residual
chemicals, to a disposal site will be eliminated;
5. The life of the disposal site, insofar as sludge disposal
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is concerned, will be increased by about 15 percent;
6. Sludge recycling can be accomplished much sooner by
utilization of the Denver drying beds;
7. There is an immediate market for dried sludge within the
Denver Parks department;
8. There is a strong possiblity of handling additional
digested sludge from the Metro District at sometime in
the near future;
9. Possible advantages accruing to the Metro District in
view of this proposal and the fact that Metro will, in the
near future, have its own anaerobic digester capability, are
a. a viable alternative by reducing the land requirement
for the Metro sludge farm;
b. cost savings of a potentially considerable magnitude
concerning pipelinesr pump stations,, land acquisition,
land development, litigation costs and replacement water
costs; and
10. Preliminary savings in excess of $300,000 can be realized
by the City and County of Denver in handling its own sludge dis-
posal. Overall savings to the agencies involved in the Metro
District could be considerably more. .
Background information of the Denver Northside Plant sludge op-
erations is found under Issue 1-6. It is important to note that all
planning heretofore has included Denver Northside sludges in the Metro
offsite solids reuse plan. This issue discussion also focuses on po-
tential modifications to Northside's operation by including the di-
gester supernatant in the pipeline flow that could reduce costs at
the Northside plant as well as at Metro.
The assumptions stated above by the City and County of Denver
must be qualified. Relevant points will be discussed in turn here.
Points #1 through #4. These are in fact identifiable costs
factors of the present DNS-Metro sludge operation. Estimates of the
change will be provided below.
Point #5. This is true; however, since there is considerable
uncertainty as to exact capacities needed, and since the bulk of the
costs will occur in the initial construction, this is probably not an
important issue. Changes in mode of operation of drying could also
have the same effect.
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Point #6. This would be true if no objections would be raised
to the drying bed proposal, EPA does not feel this is the case.
This is discussed in more detail below.
Point #7. This is true; however, the Denver Parks department
is now using Metro sludge, and would likely continue to do so under
the offsite drying proposal. Therefore, the Northside proposal is
simply another way of providing the Parks Department sludge. It
should be tested on cost effective, engineering and environmental
grounds. We also assume that the DNS system will have to haul to
the bombing range any sludge the parks cannot use.
Point #8. This is also true. However, this fact would work
against the DNS drying bed proposal. The Metro plant has an imbal-
ance of secondary to primary sludge; Northside treats only primary
sludge. If Metro were to send sludge to Northside for treatment,
it would undoubtedly be secondary waste activated sludge (WAS).
Current Metro experience is that any significant amount of WAS in
anaerobic digestion greatly .reduces the dewatering capability.
Hence, Northside would find its drying beds working less well than
with the easy-to-dewater primary digested sludge. Odor problems
would be more likely. Digester decanting would be more difficult.
The use of single-stage digestion with discharge of the contents
into the pipeline system, however, would not hurt DNS operations
even after mixing with secondary WAS.
Point #9. Based on the relatively small volume ratio of DNS
to Metro sludge, and the advanced nature of the project, EPA ser-
iously doubts there will be any significant cost reductions to the
offsite project if the DNS sludges are treated separately. The
land area requirement for the drying basins is relatively insen-
sitive to drying capacity. The site would still be about 810 ha
[2,000 acres] in order to provide research and buffer areas. Be-
cause Metro recognized an inflation problem, they plan to construct
all of the drying beds initially. Pipe sizes and pumps are also
highly insensitive to a small change in flow. No reduction would
likely take place here either. A considerable change in design
at this point would also cost money. EPA assumes for cost calcu-
lation that there would be no change in project size if DNS flows
are removed. There are, of course, operational cost differences
that will be calculated. Litigation costs will undoubtedly be the
same with either option. There are no identifiable water replacement
costs at present.
Point #10. The last point regarding cost savings of $300,000
per year, is surprising, to say the least. An article in the pub-
lication SLUDGE (Reference 43), raises the apparent cost savings
even higher. This article has been reproduced here for convenience.
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"ABOUND THE STATES
Colorado — Metropolitan Denver Sewage District Board last
month tentatively approved a $1,25 million plan for the City
of Denver to dispose of its own sewage sludge. Plan calls
for reactivation of 64 abandoned sludge drying beds at the
Denver Northside Treatment Plant and hauling treated sludge
to the Metro disposal site on the old Lowry Bombing Range
east of the city. Denver officials say the plan will reduce
annual costs from $500,000 to less than $100,000; Metro of-
ficials say Denver's handling its own sludge processing will
cut Metro's sludge processing costs $300,000 per year. Final
approval of the Metro Board is required before Denver can
apply for Federal funding."
Metro provided more detail on this reported cost savings in their
recent correspondence (Reference 42).
The increased cost of processing Metro sludge separately is
equal to:
$2.00 x 79.3 = $159
per dry ton tons per day per day.
Metro's comment on EPA's inquiry into the SLUDGE article was as
follows:
"It would appear that EPA officials have assumed that the
savings which would accrue to Denver and Metro were additive, and
they are not. It is rarely clear where the information for such
articles comes from. Such articles often do not have any basis
in fact. The resolution regarding this matter, passed by the Board
of Directors at the November 1976 meeting is reproduced. . .
RESOLUTION
BOARD OF DIRECTORS
METROPOLITAN DENVER SEWAGE DISPOSAL DISTRICT NO.1
November 16, 1976
WHEREAS, the City and County of Denver has requested that the
Metropolitan Denver Sewage Disposal District No. 1, hereinafter referred
to as the "Metro District", approve the reactivation of the Denver North»
side Treatment Plant sludge drying beds; and
WHEREAS, the staff of the Metro District and the Operations and
Budget Committees have reviewed the proposal and recommend that the
Board of Directors approve the request of the City and County of Denver;
and
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WHEREAS, the Executive Committee has reviewed the proposal and
the recommendation of the staff and other Committees and adopts
said recommendation and recommends that the Board of Directors approve
such a request;
NOW, THEREFORE, BE IT RESOLVED, that pursuant to C.R.S. 1973,
32-4-548; the Bond Resolution, Section 820; and the Service Agree-
ment, Section 304, the Board of Directors of the Metropolitan Den-
ver Sewage Disposal District No. 1 hereby consents to and approves
the plans and specifications for the reactivation of the sludge
drying beds of the City and County of Denver at its Denver North-
side Treatment Plant."
City and County officials have also offered a limited amount of
information on the costs of separate sludge drying bed reactivation
(Reference 11):
"1. There are currently 64 sludge drying beds on land which
contain the Denver Northside Primary Treatment Plant. The
beds were used until 1966, at which time they were filled
and sludge was pumped to the Metro Plant. Renovation and
modification of the beds include restoration to original
condition, placing an impervious bottom in each bed, in-
stallation of a gravity underdrain system, placement of a
graduated sand filter over the underdrains, and construction
of a collection system to return bed effluent to the
plant headworks.
2. it is anticipated sufficient area exists to permit year
round drying of all primary sludge produced at the Denver
plant. In the event of an unusually wet year with sub-
normal evaporation, flexibility exists in having the capacity
to transfer digested sludge (not dried) to the Metro Plant
for disposal.
3. Estimated costs for accomplishing the proposed plan are
as follows:
EPA initially assumed that the cost savings were additive. This
is not the case; Metro District costs are absorbed by the City and
County of Denver and other district members. Therefore, the cost
saving of $254,000 to Metro would be shared in a 2:1 ratio between
Denver and the other members. We still have a problem in trying to
understand how Denver itself could save so much ($300,00Q/year).
A. Study and Design
B. Construction
C. Operation and Maintenance (annual)
$ 75,000
1 250,000
70,000"
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EPA, therefore, developed a cost-effective alternatives analysis
to better understand the situation. Four separate alternatives were
analyzed to look at both the present Metro system and the offsite
solids project, with and without the Denver Northside sludge flows.
The four alternatives costed out are:
1) The present arrangement (as of 1976 costs) of DNS sludge
being pumped to Metro for treatment. Treatment at Metro con-
sists of vacuum filtration and hauling to Lowry for land
spreading. Out of 4413 mt [4854 tons] of digested sludge
pumped annually to Metro, 2730 mt [3000 tons] are separately
vacuum filtered using polymers and hauled away by the Denver
Parks Department. The remaining 1683 mt [1854 tons] of DNS
sludge is vacuum filtered and hauled away to Lowry Bombing
Range.
2) Metro continues to treat its own sludge by vacuum filtering
and hauling to Lowry. Northside constructs sludge drying
beds for $1.25 million. Disposal of DNS sludge is exactly
the same as above (costs will vary on hauling).
3) Offsite solids project as proposed. Cost calculations
assume that Parks Department will haul dried sludge from
8-2 site directly to parks. System assumes that DNS di-
gester decant is included in the pipeline flow.
4) Offsite solids project with DNS sludge drying project.
Parks Department takes same amount of sludge as 1. It is
assumed that offsite project size and cost is the same as 3.
The results of this analysis, as well as the key assumptions,
ace presented in Tables 11 and 12. The first table presents the results
in terms of "Costs to Denver and Costs to other Municipalities'1. Table
12 identifies the present worth annual equivalent costs to all parties
affected by Denver Northside/Metro sludge operations. It should be
noted that the present worth analysis makes some simplifying assump-
tions: 1) no salvage value calculation, and 2) no 0 & M cost in-
creases over time. The latter assumption was necessitated by the
lack of long-term comparable cost data. However, it can probably
be assumed that Denver and Metro 0 & M costs will rise proportionately
with both the present and offsite solids systems.
The immediate conclusion in looking at these tables is that
there are relatively small cost differences in the various systems.
There appears to be little reason to justify separate Denver sludge
disposal when all factors are taken into account. The principal
224
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reason for the lack of any really large differences is that the pro-
cessing of Denver Northside primary digested sludge simply is not a
very large cost item. This is to be expected since the total ratio
of DNS to Metro sludge is small (about 15 percent of the total) and
the digested primary sludge dewaters well.
Metro considerably overestimated their own cost savings if North-
side sludge were removed ($255,000). If, in fact, the Denver Parks
Department will take the polymer conditioned sludge as was suggested
in this analysis, the cost savings to Metro of removing DNS sludge
would be only about $178,000 per year. This would have to be bal-
anced by Denver's increased costs of treatment at Northside. It
is difficult to understand how Denver officials could have arrived
at the $300,000 annual savings figure. The City of Denver's total
sludge costs include Northside sludge treatment and disposal costs,
Denver's 67 percent share of Metro's treatment costs, and Denver
Parks Department sludge handling costs. Calculated with these
considerations, Denver's short-term savings is about $10,000 per
year. Other Metro district members would share a $162,000 per
year savings.
Once the offsite solids project is built, the separate treatment
by Northside would become much less cost-effective. In particular,
the City and County of Denver would stand to lose on the order of
$115,000/year as a result of paying for the bulk of two sludge
treatment projects. EPA fails to understand the rationale behind
the City's opting for separate sludge treatment. Based on the cost-
effective analysis above, EPA cannot justify the need for separate
facilities.
Separate sludge treatment at Denver Northside was evaluated
by the consulting firm of Camp, Dresser and McKee in 1974 (Refer-
ence 11), including the potential for reactivation of the sludge
drying beds. The consultants did not recommend proceeding inde-
pendently, based on the following evaluation:
"In the following paragraphs, alternative methods for the dis-
posal of anaerobically digested sludge from the Northside
plant, if the present disposal method is discontinued, are
briefly discussed. These alternatives were not studied in
depth, because it is assumed that there will be no change
in the current procedure.
It is reported that digested sludge was formerly conveyed to
the Denver Parks Department for use as a soil conditioner.
This department's requirement for sludge has not been inves-
tigated, but it obviously would be far less than the quantity
available from the Northside plant.
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Table 11. ANNUAL COST TO THE CITY OF DENVER AND OTHER METRO MEMBERS FOR VARIOUS
SLUDGE TREATMENT ALTERNATIVES AT NORTHSIDE
Plants &
Paying
Municipalities
Unit
Processes
Costs
1-Present
Operation
1. Denver
Northside
Plant
2. Denver
Parks
Dept.
3. Metro
District
Plant
O&M
"STudge Processing $213,000(3)
Drying Beds -0-
Haul to Lowry -0-
Other -0-
AMORT CAPITAL COSTS -0-
TOTALS $213,000
O&M 58,500 (4)
a. O&M(DNS Sludge Only)
Pumping 17,100(5)
Vacuum Filter 118,000(6)
Haul to Lowry 43,500(6)
b. O&M (All other)
Total
c. AMORT CAP COSTS
TOTALS
2,677,400(7)
-0-
2,856,000(7)
4. 67% of
Total(1)
Sludge Operations
Paid by Denver
5. 33% of Total (2)
Metro Sludge
Operations Paid
by Other
Municipalities
1,904,000
952,000
2-Present Metro &
Separate DNS
Alternatives (Annual Costs in Dollars)
3-Metro Offsite
4-Metro Offsite &
Separate DNS
$213,000
52,300 (8)
33,000 (9)
-0-
30,000(10) (local)
328,300
58,500
-0-
-0-
-0-
2,677,400(11)
-0-
2,677,400(11)
1,785,000
892,000
$213,000
-0-
-0-
(-) 25,000(12)
-0-
188,000
25,800(13)
30,000(14)
-0-
-0-
$213,000
52,300
33,000
-0-
30,000
328,300
58,500
563,000*(15)(16)(17) 508,000
420,000(18) 420,000
1,013,000 928,000
675,000
338,000
618,700
309,000
Total Sludge Cost(l)
Paid by Denver (1+2+4)
2,175,000
2,166,000
890,000
1 ,005,400
*Total Includes DNS Sludge Costs
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FOOTNOTES FOR TABLE 11
(1) The City of Denver is obligated to pay for three different areas
of Denver Northside-Metro plant sludge treatment: 1) the costs
at the Northside plant, 2) the Denver Parks Department's sludge
preparation for park use and 3) 2/3 of the Metro treated plant
siudge costs.
(2) All other municipalities in the Metro District pay for the other
third of the capital and operating costs, as we understand it.
(3) Metro data cited $15/ton to process Northside sludge. Annual
figure based on the total value of sludge generated at the North-
side plant (4854 tons 1/3)
(4) Metro data from Denver Parks Department: $16/ton to dry and haul
and $3.50 to spread. Assumes 3000 dry tons/year to Parks Depart-
ment and 1854 dry tons/year of Northside sludge to Lowry.
(5) Metro data: $3.60/ton
(6) Calculated data based on 1976 Metro performance and budget data:
$24.50/dry tons to vacuum filter Northside sludge and $23.50
to haul to Lowry landfill; average Metro costs are higher.
(7) Based on 1976 actual Metro operating costs
(8) Estimated by Denver Northside at $11/ton
(9) Assumes 25% dryness at $4.45/wet ton to haul to Lowry (1854
tons/year)
(10) Estimated Denver local 25% annual repayment share (20 years, 7%
interest)
(11) Simple difference between 3b and 3a under Alternative 1.
(12) Rough estimate of lowered Northside costs by switching to single-
stage digestion and lack of implant recycle.
(13) Cost to Parks of truck hauling 3000 tons of dried sludge to Parks
(no storage, drying, or preparation assumed).
(14) Estimate including added pumping costs of decant
(15) Worst-case assumption of disposal of 24,300 tons of dried sludge
in Lowry landfill 0$3/ton hauling costs (Metro estimate)
(16) Metro data•
(17) Includes a very conservative estimate of cost-savings to Metro
as a result of a 270 reduction in B0D/SS from Denver Northside
to Metro secondary facility. If advanced waste treatment is
needed at Metro, the ammonia reduction would further reduce
Metro operating and capital costs (perhaps 5-7%)
(18) Total project cost $17.6 million (Metro estimate) amortized at
7% interest, 20 year repayment.
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Table 12. PRESENT WORTH ANALYSIS FOR VARIOUS NORTHSIDE-METRO SLUDGE ALTERNATIVES
(thousands of dollars)
Alternative 1
Present Operation
Alternative 2
Present Metro
Separate DNS
Alternative 3
Metro Offsite
Solids Project
Alternative 4
Metro Offsite
& Separate DNS
Northside
Plant
Parks
Metro
Plant
Capital
(total)
0 & M
(Annual)
Capital
(total)
0
59
59
0
0 & M
(Annual) 2,856
Total Present
Worth 33,138
Annual Equivalent
Cost 3,128
1,250
298
59
0
2,677
33,392
3.152
0
188
26
1,766
593
26,149
2,468
1,250
298
59
1,766
508
280,138
2,644
Assumptions:
1. No salvage value at end of repayment period.
2. No growth requiring further sludge treatment expansion or additional operating costs, and no
inflation costs.
3. Data from Table 11 on Denver costs.
4. 20 years of operating costs.
5. 20 year repayment at 7% interest.
6. 1976 costs for 0 & M.
-------
Because digestion may not destroy all pathogenic organisms,
there is a potential hazard in applying liquid sludge to land.
Other factors of concern are the effects of nitrogen compounds
and of heavy metals. Land application of liquid sludge has
been extensively studied and practiced throughout the world
for many years. Under certain conditions and with certain con-
trols, the method is satisfactory and beneficial agriculturally.
However, additional studies of the specific area to which the
sludge would be applied and the means of applying it would
be necessary before this method could be recommended in Denver.
Other methods include:
Vacuum filters (followed by landfill or incineration)
Pressure filters (followed by landfill or incineration)
Drying beds (followed by landfill) . . .
DRYING BEDS. Drying beds depend largely on drainage and
evaporation, although in some cases gravity separation and
decanting of the clarified supernatant are used. Drying bed
size depends on the nature and quantity of sludge, climate, and
soil conditions. Comparatively large areas of land are
required; this factor, and the serious odor problems associated
with drying bed operations, would probably preclude its use
at the Northside plant. Advantages of drying beds include
reduced expenses and ease of operation. Disadvantages include
area required, potential nuisance problems, susceptibility to
adverse weather conditions, and the requirement that sludge be
well digested prior to dewatering.
Liquid sludge is conveyed by a drainage system to the drying
bed. After 1 to 3 months' dewatering, sludge is removed by
mechanical scraper or hand shovel and the drying beds are
restored by removal of the top few inches of sand and discing.
The top layer of sand is then replaced. This operation is
the major item of expense in sludge bed operation.
The least costly system for drying and disposal of anaerobi-
cally digested sludge is usually the drying bed-landfill com-
bination. However, land availability and the effect of re-
turned drainage liquid on plant operation must be evaluated,
if the Northside plant sludge is to be disposed of as a
separate operation. If these factors detract from the choice
of this system, vacuum filtration and landfill would probably
be the next most acceptable alternative. Systems employing
incineration usually have a high initial cost, which precludes
their use unless suitable conditions for landfill are not
available.
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No additional conclusions can be made at this time. Choice of
drying beds, vacuum filters, or pressure filters for dewatering
should be based on additional studies and tests, if the present
sludge disposal system is discontinued. .
EPA is similarly concerned about a number of impacts mentioned by
the consultant -- odors, large amounts of land required, nuisance con-
ditions and adverse weather problems. There are residential areas
in close proximity to the Denver Northside plant. The old drying
bed areas now act as a buffer to these residential areas; utilizing
the beds could put the sludge operation quite close to existing res-
idences. If waste activated sludge were to be mixed with the North-
side primary, the possibilities for odorous sludges would be increased.
EPA feels that an EIS would probably be required if such a proposal
were to be funded.
EPA sees no advantage in having Northside develop the drying beds
for Parks Department use. As the consultants' analysis above indicated,
the Parks Department would, in all probability, not be able to use all
of Northside's sludge. The remainder would probably have to be hauled
to the Lowry Bombing Range. Under the Northside system, the Parks
Department would have to further dry and store the sludge before it
could be used at park areas. Metro's offsite system will perform
this in the drying/storage process. Thus the Parks Department could
use this sludge directly.
A final factor to be considered is that given the assumption that
the offsite solids project will be built, there will still be two
alternative processes for handling Northside (or Metro) sludge. The
vacuum filters will still be available for occasional use. Metro
officials have indicated that they are considering the possibility
of vacuum drying, on the Metro plant site, a limited amount of di-
gested polymer-treated sludge for park use. Since the anaerobic
sludge can be filter-dried to 20+ percent solids, there will be
little free water to contaminate groundwater or surface waters.
As long as Metro suitably prepares the area to contain any surface
runoff, EPA believes the problems will be minimal. This would ac-
complish the goal of allowing Parks Department use of sludge without
expenditure of extra federal funds.
The potential market for dried sludge on park lands could expand.
Letters in Volume I of this EIS (Appendix F) indicate an interest in
dried sludge use by other communities, including Northglenn, Aurora
and Commerce City. Either the offsite solids system or the Metro on-
site proposal could provide for this demand. Based on the cost anal-
ysis, either system would be reasonably cost-effective. If one as-
sumes an operating cost of about $4.50/mt [$5/ton] to further dry
230
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the vacuum filtered sludge, the total Metro cost might be $27 to $32/mt
[$30 to $35/ton]. If the sludge were dried offsite and trucked back
to Denver, a cost of about $23 to $27/mt [$25 to $30/ton] would result.
Actual experience will better define these costs.
Based on this analysis, EPA believes that the City and County of
Denver would be ill-advised to develop independent Northside sludge
treatment capabilities. EPA will therefore not participate in any
funding of plans, designs or construction of additional sludge treat-
ment in the form of drying beds, unless persuasive evidence contrary
to the analysis presented here can be offered.
EPA does recognize the importance of assuring a high quality de-
pendable source of dried sludge for Denver Parks use. EPA believes
that such use could in the near term constitute the most important
reuse potential for Metro offsite dried solids. EPA will set a
grant condition that Metro will not distribute the dried sludge to
users, with the exception of municipal park districts, until State
Agricultural use regulations on sludge are finalized. EPA believes
that municipal park use has been firmly established without notice-
able problems in the past. EPA also will strongly urge Metro to en-
courage such municipal use by avoiding unnecessary charges for
sludge used in this manner.
ISSUE IV-4. What alternatives are available to control groundwater
qua!ity at Site B-2?
There are several ways to provide protection to the groundwater
beneath Site B-2. The most positive, and most expensive, method is
to provide a completely impervious liner beneath all the drying beds.
Metro has provided an estimate of the costs and efficiencies of seven
types of liners, shown in Table 13. As the table shows, a completely
impervious liner such as Portland Cement Concrete or a PVC liner
would be quite expensive. Bentonite clay is the cheapest of these
liners; if installed as discussed in Issue 11-2 with a cover layer
of soil, a clay liner should not dry out and crack. Because of the
large amount of clay at the site, Metro should be able to construct
a liner without purchasing clay from an outside source.
In addition to lining the beds, there are two other methods by
which groundwater pollution can be minimized or eliminated. The first
is to install a series of alluvial wells around the perimeter of the
drying beds, and pump out the leachate which reaches the alluvium.
While this method would effectively remove most of the leachate
which reaches the alluvium, if leachate moves into the bedrock
aquifers directly beneath the drying beds it won't be removed.
From the geotechnical investigation, it does not appear that the
bedrock-alluvium interface will allow leachate movement into the
231
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Table 13. DRYING BASIN LINER ANALYSIS SUMMARY
Material
Estimated
Linear Cost
Comments
Bentonite
$ 4,600,000 Reduces seepage; doesn't stop it
Will crack due to wetting - drying
cycles
Not appropriate for intended
application
Soil Cement $12,800,000
Portland Cement
Concrete
Bituminous
Concrete
Bituminous Base
Stabilization
$45,700,000
$20,100,000
$12,400,000
Asphalt Membrane $10,100,000
PVC Liner
$16,500,000
Will get shrinkage cracks
Hard impermeability
Hard and durable
Favorable past experience
Dense and permeable
Not common for waterproofing hy-
draulic structures
Efficacy uncertain
Has many precedents
1.5 gals/sq. yd. for 3/16" to
5/16" membrane
Requires 1' to 3' earth cover
Asphalt Institute says this is
less costly and as good as any
other liner
No seepage
Requires minimum 2' soil cover
Source: MDSDD #1
232
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bedrock directly below the beds (Reference 13). This method requires
disposal of the water pumped up; it should be returned to the beds for
removal by evaporation. No cost estimate is available for this option.
The second alternative to impervious liners is to install tile
drains beneath the beds to collect the leachate. This system is
commonly used with sand drying beds for leachate collection, and in
other applications where removal of groundwater is required. This
system would cost approximately $10,000,000 to install at Site B-2.
The leachate would be returned to the beds for drying as with the well
system. Most, but not all, of the leachate would be collected with
this system.
Any of these alternative systems could be installed after the
beds have become operative if monitoring of the groundwater deter-
mines that significant groundwater pollution is occurring or is
likely to occur. The cost would probably be somewhat higher if liners
are installed after bed construction, however. If clay liners with the
permeability given in Issue 11-2 are installed, the quantity of leach-
ate is expected to be small enough that no further mitigation is
necessary. At this time, it would be unwise to invest in a more
costly alternative which may not be necessary, since at worst the
monitoring program will determine if a problem develops and appro-
priate action could be taken at that time.
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ISSUE V
SLUDGE USE
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 organicsl?
The three principal constituents of sludge posing the possibility
for constraints on its use for land recycling have been identified as
toxic substances (notably heavy metals and certain complex organics),
soluable salts, and bacterial and viral pathogens. Each of these will
be discussed below, including consideration of areas in which con-
straints on use are felt appropriate.
Pathogen Survival and Transport
The Colorado State Department of Health has issued draft Guide-
lines for Sludge Utilization on Land (Appendix B). These guidelines
set requirements for treatment, handling, use and regulation of
sewage sludge utilized on land. The Department will be responsible for
all monitoring and for enforcement of the compliance of sludge users
with the guidelines. The proposed project will meet the requirements
set forth in the draft guidelines for the treatment of sludge. The
sludge will be disbursed to farmers and homeowners with instructions
on its safe use; it will then be the responsibi1ity of the user to
follow the instructions, and the responsibility of the Department
of Health to see that they are followed (Reference 5, Appendix B).
The guidelines have been written with consideration of the most up-
to-date knowledge of the potential problems which sludge application
may cause. They have been designed to minimize the known harmful
effects of sludge misuse. If the guidelines are rigorously followed
and enforced, the possible negative impacts of sludge use will be
substantially reduced.
A great deal of concern has been expressed over possible health
problems caused by parasites, bacteria, and viruses in dried and
stockpiled sludge. In view of the treatment the sludge will re-
ceive before distribution, i.e., anaerobic digestion, air-drying,
and stockpiling for at least one year, this problem will largely
be mitigated. The notable possible exceptions are Ascaris ova,
which have been shown to survive for several years in sludges and
soils. However, these survival times have been in moist, warm
climates, which differ drastically from the cool, dry conditions
in the Denver region. It is possible that these ova will be present
in the final product; however, the extent to which this would pose
a health hazard is unknown at present. Since digested, air-dried
sludge has been fairly extensively used in the past with no documented
234
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health problems, it is felt that the risk posed by Ascaris would
likely be quite small. However, medical checkups should be made
available to anyone who uses the product, and if any signs of health
problems due to sludge use are found, additional precautions (such
as longer drying times) will be required. Also, sludge use by in-
dividuals on home gardens may be prohibited in order to lessen the
chances of misuse and greatly reduce the number of people who come
into contact with the sludge.
Pathogens may also be transported from the site by both insect
vectors and by windblowing of stockpiled sludge. Insect control is
discussed in Issue 11-10. Although some insects will of course be
found in and near the site, their numbers are expected to be small.
The likelihood of human infection by this means is remote. Wind-
blowing of sludge is discussed in Issue 11-5. As noted in that
discussion, only a minute quantity is expected to be blown from the
stockpile area. The chances of human infection occurring from this
means of pathogen transport is almost zero.
On a national level, EPA has been working on the development of
criteria for uses of solid wastes, including sludges, as well as
what constitutes "hazardous wastes" (which come under the control of
the recently passed Resource Conservation and Recovery Act, PL 94-
580). As of this time, the preliminary draft of regulations to im-
plement these criteria indicate that wastewater treatment plant sludges
containing pathogenic organisms are considered "infectious" (i.e.,
capable of producing human diseases) unless the sludge has received
the treatment equivalent of anaerobic digestion (at least 10 days'
digestion at 95°F and a 97 percent plus pathogen destruction). Under
these criteria, the Metro land recycling proposal would meet the
minimum criteria and would not be considered an infectious waste. The
air drying and storage under this plan for a year's time or so would
have a further pathogen-killing effect.
For this project's proposed uses, it is felt that the likely
pathogen reduction achievable would make the sludge suitable for
most agricultural uses. Only direct ingestion either by humans or
domestic animals is felt to be still a potentially infectious situation
that may need to be controlled (see discussion under Issue V-2 on
Types of Uses).
Salt Contamination of Soils, Surface Water and Groundwater
The application of sludge containing salts could pose a signif-
icant impact on soils and groundwater where sludge is used. The chem-
ical constituents of a ten-day composite sample of anaerobically di-
gested liquid sludge from the Denver Northside Plant is given in
235
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Table 14. The sludge eventually sent to the drying and distribution
site is expected to have concentrations similar to those in this
table. These data indicate soluable salt concentration (%2000 ppm TDS)
considerably less than estimated in the draft EIS (up to 6000 ppm TDS).
Volume I of the EIS discusses problems related to salt accumu-
lation in the soils in Section V, Section VII, and Appendix D. As
these discussions indicate, increased salt concentrations in the
soil resulting from sludge applications over a long period of time
could decrease plant yields. Consequently, soils receiving sludge
on a regular basis should be monitored for accumulation of salt. This
is easily accomplished by measuring the electrical conductivity of a
soil extract solution. If the conductivity begins to approach about
4 mmhos/cm, sludge use should be discontinued. This problem is not
expected to be severe for either dryland or irrigated farms. For
dryland farms, the sludge application rate is so low that salt will
probably not accumulate to a harmful level to plants for an extremely
long time (on the order of 100 years). For irrigated farms, the
leaching provided by irrigation waters should prevent a harmful build-
up of salts.
It should be recognized that 32 percent of the total weight of
soluble salts reported in the Metro data are considered plant nutrients
(NH4+, P0it = , and K), and are commercially applied as fertilizer on
cropland. Based on this evidence, it does not appear that salt
accumulations would pose a hazard for sludge users. Therefore, apart
from monitoring dryland areas occasionally for conductivity and ap-
plying good irrigation practices to move salts through the soil pro-
file, no further mitigation is felt necessary at this time.
Heavy-Metal Accumulation in Soils and Crops
One of the prime concerns about extensive use of sludge on
farmland is the potential damage to crops and soils by heavy metals in
sludge, as well as the risk posed to humans by accumulations in the
human food chain. The metal content of Denver sludge and proposed
programs for reduction of metals in the system are presented in
Issue 1-1.
A large amount of research is currently being conducted on the
effect of the trace metals in sludge on crops and soils. The effects
of metals vary widely depending upon soil and crop type to which
sludge is applied. Leafy plants combined with low-pH soils are
the worst conditions with regard to the occurrence of toxic metal
levels. Volume I of this EIS discusses the heavy metal problem as
it relates to the proposed uses in Section V and Appendix D. The
conclusion is that the proposed farmland sites for sludge application
236
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Table 14. CHEMrCAL CONSTITUENTS OF ANAEROBICALLY DIGESTED
PRIMARY SLUDGE FROM THE DENVER NORTHSIDE PLANT
Analysis
Concentration
In Liquid Sludge
Concentration
mg/kg Dry Solids
Total Solids
6.9%
-
TDS
2110 mg/1
-
HC03
360 mg/1
5200
NO3
0.4 mg/1
5
P04
32 mq/1
463
NH4
576 mg/1
8350
SO4
10 mg/1
145
CI
375 mg/1
5400
K
66 mg/1
960
Na
114 mg/1
1650
Ca
93 mg/1
1350
Mg
20 mg/1
290
Conducti vity
4180 umhos/cm
237
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are well suited for minimizing the impacts from sludge metals. The
reasons are the highly calcareous soils in the area, the relatively
low sludge loading rates proposed, and the relatively high phosphorus
content of Denver sludge which tends to make both zinc and cadmium
less available to plants.
A study of the application of liquid sludge to wheat in Adams
County was carried out in 1974 to determine the metal composition of
the wheat and soil after application (Reference 3). This study
analyzed a number of metals and used sludge loadings of 0, 55, 109
and 150 mt/ha [0, 20, 40, and 55 tons/acre] on test plots growing
hard winter wheat. Of all the metals tested, only zinc, cadmium
and nickel showed significant increases in the sludge-amended wheat
as compared to the control wheat. The value for zinc, though higher,
was still within the range expected on the basis of an analysis
of 12 wheats from various other parts of the county. Nickel and cad-
mium would then appear to be the two metals of concern for Denver
sludge. It should be noted, however, that an analysis of Denver
sludge from 1972 to 1973 showed a very high nickel concentration of
562 ppm (Reference 6). A more recent analysis, in 1975, gave lower
values for nickel as shown in Table 1. The application of sludge to
wheat reported in this section was carried out in 1974. It appears
that the nickel content of Denver sludge may be decreasing; a source
control program should decrease it even further. Also, the report
stated that even though the levels of these two metals are anomal-
ously high, they do not appear to be potentially detrimental to
either plants or animals, including man.
In the sludge-amended soils, cadmium was below the detection
limit of 1 ppm, nickel showed a slight increase, and zinc approx-
imately doubled in soils with the highest loading, increasing less
with the intermediate loadings. Copper, lead, mercury, silver and
tin also showed marked increases in sludge-amended soils, with anti-
mony, arsenic and chromium showing lesser increases. The soil pH
was also decreased somewhat by the sludge addition.
When comparing these results with what may be expected to
occur with the proposed drying and recycling plan, it must be re-
membered that the cited study used liquid sludge, whereas primarily
dried sludge will be applied in the project under consideration.
The application rates (dry weight basis) were in the upper range
of the probable rate of dry sludge to be applied to irrigated farms
and sod farms, and are considerably higher than the rate that would
be considered for dryland farms. Also, when sludge applications are
based initially on supplying the crop with adequate nitrogen, ap-
plications of potentially toxic metals will be limited to levels
that are of no concern except for sludges that have an excessively
high metal content (Reference 38). Nickel is the anomolously high
238
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metal in Denver sludge; proper source control should ameliorate
this condition. Another factor which will lessen the impact of metals
on soils in the area is the high pH of the soils; all are well above
pH 6.5, which is the recommended minimum (Reference 2). Taking into
account these considerations, no harmful short-term effect on crops
is likely to occur from trace metals.
Along with pH, the soil cation exchange capacity (CEC) plays a
large part in controlling the effects that heavy metals in soil will
have on plants. The higher the CEC, the greater the concentrations
of metals which can be tolerated in the soil without ill effects.
Table 15 gives the total amount of various metals which should be
added to soils having low, medium and high CEC's. Application of
sludge to a parcel of land should be terminated when any metal listed
in the table exceeds the recommended limit. The quantities of each
metal added can be calculated knowing the concentration of the metal
in the sludge and the sludge application rate.
A study of the soils at Site B-2 in 1976 determined the CEC of
two typical soils which are expected to represent the range of soil
properties at the site (Reference 7). The Ulm series soil profile
had an average CEC of about 30 meq/100 gm, and the Ascalon Series
profile averaged about 15 meq/100 gm. Both of these CEC's are in
the high range given in Table 15. If these CEC's are representative
of those found in the entire area, then the soils should be well
suited to minimize problems resulting from metal applications.
The only metal not listed in Table 15 which is considered by
the CAST study to pose a potentially serious threat to cropland is
Molybdenum (Mo)(Reference.38). Mo, unlike most other metals, in-
creases in availability as the soil pH increases. Therefore, its
application rate should be monitored carefully in the high-pH soils
in the area. No recommended limits for Mo in soils have been de-
termined. However, Mo does not appear to be very toxic to plants
(Reference 38). If the total quantities of other metals are kept
within the recommended limits, it is likely that no problems with
excess Mo would occur. Metro should, however, include Mo as one
of the metals routinely analyzed in its sludge.
Since continued application of sludge will cause a buildup of
trace metals in the soil over a period of time, monitoring of metals
in sludge-amended soils should be carried out every five years. If
any metal approaches the limits in Table 15, sludge use should be
discontinued. Monitoring at five year intervals should detect any
potentially harmful metal accumulations before they reach the point
at which crop damage or high concentrations in crops occur (Reference
38). The sludge will be monitored periodically for its metal con-
tent before it is disbursed to the users, and any dangerously high
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Table 15. MAXIMUM RECOMMENDED QUANTITIES OF METALS WHICH
SHOULD BE ADDED TO AGRICULTURAL SOILS
0 •
Soil Cation Exchange Capacity (Meg/lOOg)
-5 5-15 >15
Amount of Metal
Metal
kg/ha
lb/ac
Kg/ha
1 b/ac
Kg/ha
lb/ac
Pb
564
500
1130
1000
2250
2000
An
282
250
564
500
1130
1000
Cu
141
125
282
250
564
500
Ni
56
50
113
100
225
200
Cd
6
5
11
10
23
20
Source: Reference 44
concentrations detected before it is released to the user. EPA will
recommend the above approaches to the Metro District, both for their
own research as well as information to users.
The problem of metal accumulations in animals fed with hay or
other fodder grown on sludge-amended soils may necessitate the ex-
clusion of the livers and kidneys of these animals from public con-
sumption. A sampling program to determine whether dangerous levels
of metals are being accumulated in these organs should be instituted;
in this way, the magnitude of the problem can be assessed. No danger-
ous buildup of metals should occur in other animal tissues. Metro is
currently studying buildup of heavy metals in tissues of cattle feed-
ing on areas of the Lowry Bombing Range containing Metro sludge.
The 1977 Amendments to the Clean Water Act require EPA to de-
velop regulations or guidelines for sludge use and disposal. Congress
recognized the right of local determination of the type of sludge use,
but insisted that the systems chosen must be in accordance with the
guidelines. EPA will have to identify concentrations, of pollutants
in sludge interfering with possible uses of sludge.
The following is the language of the Amendments pertaining to
sludge use guidelines EPA would have to develop:
"(d) The Administrator, after consultation with appropriate
Federal and State agencies and other interested persons, shall
develop and publish, within one year after the date of enactment
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of this subsection and from time to time thereafter,
regulations providing guidelines for the disposal of sludge
and the utilization of sludge for various purposes. Such
regulations shall -
'(1) identify uses for sludge including disposal;
'(2) specify factors to be taken into account in deter-
mining the measures and practices applicable to each
such use or disposal (including publication of infor-
mation on costs );
'(3) identify concentrations of pollutants which in-
terfere with each such use or disposal.'
The Administrator is authorized to revise any regulation
issued under this subsection.
(e) The determination of the manner of disposal or use of
sludge is a local determination except that it shall be un-
lawful for the owner or operator of any publicly owned treat-
ment works to dispose of sludge from such works for any use
for which guidelines have been established pursuant to sub-
section (d) of this section, except in accordance with such
guidelines
EPA will therefore be more directly involved in the future in
defining where various constituents could pose limitations to
sludge application. Limitations on cadmium suggested in grant con-
dition No. 11 represent the pollutants EPA thinks pose the greatest
hazard in sludge at this point in time. EPA recommends that no more
than 1-2 kg/ha [1-2 lbs/acre] of cadmium be applied to cropland annually.
ISSUE V-2. Should constraints to Metro sludge use be set depending
upon the kinds of use contemplated?
Metro has identified six principal markets for the dried sludge:
(1) city parks, (2) sod farms, (3) mine spoil sites, (4) irri-
gated farms, (5) dryland farms, and (6) home gardens. In addition,
a coal gasification project near Watkins may use Denver sludge as
part of its fuel feedstock. Each of these uses with their impacts
and possible mitigative measures have been described in Section IV
and V and Appendices D and E of Volume I. The major aspects of
each of these uses is briefly summarized here.
City Parks
The Denver Parks Department has been using dried sludge to aid
in preparing topsoil for establishment of new parks. Since public
use of park areas is high, particular care must be exercised to en-
sure that pathogens (especially Ascaris ova) are completely killed
in the sludge product. The one-year stockpile time planned for
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Denver sludge should achieve this goal. The sludge loading rate
should also be limited to that which does not cause significant
groundwater or surface water pollution from nitrates or TDS. This
rate would ideally be computed by balancing the nitrogen content
of the sludge with the nitrogen requirement of the grass being
grown at the park.
Communities in the area other than Denver have also expressed
interest in a similar use of dried sludge. In light of the suc-
cesful use of sludge for this purpose in the past, there seems
little reason why it cannot continue. Other than maintaining care-
ful management practices described above, there seems little jus-
tification for any further controls.
Sod Farms
Application of sludge to sod farms will probably be conducted
by using manure spreaders or similar equipment. This application
has the smallest potential for harm of any of the oroposed uses.
Sod farms have a high rate of irrigation which will help keep
sludge particles and nutrients in the soil profile. The cyclic
removal of thin layers of soils during harvest will prevent the
buildup of any harmful sludge constituents which may be present.
Sludge nutrients will help increase productivity while reducing
the need for commercial fertilizers. Grass is a good crop for
sludge fertilization because it is tolerant of heavy metals, is
not used for human or animal food, has a high rate of nitrogen
uptake, and minimizes problems from runoff and erosion. Only con-
trol of runoff during early stages of application is felt neces-
sary as a mitigating measure.
Mine Spoil Sites
Many mining sites in the Rocky Mountains and elsewhere have
large piles of acidic mine tailings created during the metal ex-
traction process. Because of their coarse particle size and high
acidity these inert heaps may remain unvegetated and unsightly for
decades unless a deliberate effort is made to restore them. Sludge
for this purpose will be mixed with wood chips and applied at a
rate of about 67 mt/ha [30 tons/acre]. A higher application rate
than this may prove to be optimal for reclamation.
These spoil sites are generally characterized by extremely
acid soil conditions, high rates of erosion and runoff, toxic
levels of certain metals in the soil, low soil fertility, low
soil moisture content, and high summer surface temperatures. Sludge
helps ameliorate these conditions by raising the soil pH, thus
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immobilizing to some extent the acid-leached metals, and helps build
up desirable soil characteristics allowing plants to grow. Once
vegetation has been reestablished, erosion and temperature problems
are lessened. Because of the severe conditions at these locations,
no crops for human consumption are grown there.
Mine spoil sites in the area are mostly located at high ele-
vations in areas where little groundwater occurs. At the represen-
tative mine near Berthoud Pass owned by Climax Molybdenum, surface
runoff flows into Woods Creek, which is a tributary of Clear Creek.
Flow through fractures in the bedrock and into the streams is prob-
ably fairly rapid. The quality of this runoff before sludge ap-
plication is quite poor and is highly acidic. The use of sludge
on mine spoils may actually improve the surface runoff quality
immediately by raising its pH. The runoff quality is still expected
to be poor, however. The long-term effect on runoff quality and
quantity will be beneficial, because of the improvement of the
moisture-holding capacity of the soil and the revegetation of the
site. In short, the conditions at these sites are already very
degraded, the addition of sludge is unlikely to significantly de-
grade them further, and will in all probability improve runoff
characteristics, at least in the long term. Such applications
would best be characterized as experimental at this point in time.
Exact management practices will be developed after more studying
and monitoring is done.
Irrigated Farms
The use of sludge on irrigated farms is probably the most sen-
sitive area of application. Care must be taken to ensure that the
proper application rates are used. The method for computing appli-
cation rates based on the sludge nitrogen content is given in Sec-
tion IV of Volume I. These rates should be strictly adhered to,
and the quantities of Zn and Cd added to each farm should be recorded.
Since this application rate is site-specific for each farm and
each soil type, it is important that the sludge limit be computed
for each. If this is done, sludge should prove to be beneficial
fertilizer for irrigated farms.
Control of irrigation rates and other standard farming practices
will minimize the effect of sludge on groundwater and surface water
quality. The impact of sludge nitrates on water quality should be
no greater than that of commercial fertilizers, except that runoff
from sludge-amended fields may have somewhat higher TDS than from
fields not so treated. For this reason, sludge should be preferen-
tially used on farms which are carefully managed and operated to
minimize tailwaters. Generally, because of the intensive nature of
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this type of farming, irrigated farms in Adams County are operated with
a high degree of control.
EPA does recommend that Metro sludge not be applied to land
growing directly consumable vegetable crops in raw form, particularly
leafy vegetables. Even such crops mioht be able to be grown on sludge
amended fields, if the sludge were applied a year in advance of the
growing season. Some risk of pathogen contamination would still be
present, though small. No clear danger has been identified for grow-
ing crops such as corn, alfalfa, sugar beets, etc. with dried sludge.
It would be advisable for Metro to continue experimentation on locally
grown crops to identify the extent of heavy metals accumulation and
toxicities in various crop species (and where in the plants these
metals are concentrated, i.e. seeds, leafy parts, roots, etc.). Such
a program could be developed in the context of the proposed project
on Site B-2, and would be a helpful companion study to many already
in progress nationwide by universities, EPA, USDA, etc.
Dryland Farms
Dryland farming constitutes the largest farmland area in Adams
County. These farms are less intensely farmed and have considerably
lower yields per hectare than do irrigated farms. Consequently, they
require a much lower quantity of fertilizer. In practice, it is ex-
pected that injection of liquid sludge in bands beneath the soil
surface will be more practical than surface application of dried
sludge. This is primarily because the injection process will also
scar the land, a common practice in the area, which allows better
penetration of rainfall and improved water retention.
Dried sludge could also be applied at rates sufficient to pro-
vide for the crops' nitrogen requirement, as with irrigated farms.
Because of the low application rates, buildup of heavy metals will be
much slower than with irrigated farms. However, salt accumulation
could be more of a problem with dryland farms because they will not
be leached out of the soil. Salt content of the soil should be mon-
itored on dryland farms receiving sludge in order to ensure that it
does not rise to intolerable levels. If this is done, use of sludge
on dryland farms should pose no other particular difficulties.
Home Gardens
This use of sludge entails some risks because of a high number
of people being exposed to sludge and the impossibility of any agency
monitoring each and every user. If sludge is dispensed to individuals,
it should have been stockpiled for as long as practical, but at least
one year, in order to ensure complete pathogen die-off. In addition,
users should be clearly cautioned against using sludge on soils growing
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any edible crops, especially during the season of sludge application.
Its use should be restricted to soils growing lawns or ornamentals.
EPA is expected to issue an information bulletin in the near future
on the home uses of sewage sludge (Reference 47). This bulletin will
be prepared for both municipalities and the general public. EPA at
this time has no well defined position on home uses, because of the
wide divergence of opinion on the dangers involved.
If the sludge is bagged and clearly labelled as to recommended
uses and potential hazards, then use on home lawns and gardens will be
acceptable. Many small wastewater agencies in the U.S. presently
allow the general public to use air-dried sludge with no restrictions.
To date, no problems with this practice have been documented. Generally
speaking, a user who goes to the trouble to acquire a product such as
this will also take the trouble to use it properly.
EPA feels that the highest priority of control should be toward
minimizing the entrance of quantities of heavy metals and toxic sub-
stances into the human food chain. Since leafy vegetables absorb
fairly large quantities of heavy metals, sludge use should be restricted
if it is used in home gardens near those crops whose leafy parts are
consumed directly or where heavy metals are known to concentrate in
vegetables.
Watkins Gasification Project
The Watkins project is a conceptual plan to develop largely
untapped reserves of lignite coal near Denver. The coal will be
combined with solid waste and gasified to pipeline quality natural
gas. Denver sludge and solid wastes may be mixed together and pressed
into briquettes. These would provide approximately 20 percent of the
fuel feedstock for the project. This use of sludge is quite accep-
table and should have no adverse environmental effects if normal
precautions are taken to minimize air pollution.
In summary, EPA Region VIII will be making a number of definitive
recommendations on restricting sludge use, and will recommend pre-
cautionary measures. A national EPA and other Federal agency task
force is working to define the necessary restrictions on sludge use;
regulations required under the 1977 Amendments will define the pro-
posed uses and any constraints necessary. A consensus so far on
appropriate limits has been difficult to achieve because of the variety
of opinions and conflicting scientific research findings. At such
time as regulations or technical guidance are available, Region VIII
EPA will see to it that the Metro District implements new policies
and practices regarding sludge use. It is EPA's belief that the
basic design of the system provides adequate sludge treatment for most
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of the proposed uses. Caution is of course important where sludge will
be used on human food chain crops. The need for good management prac-
tices with sludge use and continuing research are the two most es-
sential other requirements for a safe sludge use program. It appears
that the Metro District is committed to both of these.
ISSUE V-3. Are Metro's plans for use reasonable and compatible with
the market trends?
Metro has identified a variety of potential uses for the dried
sludge product (dryland farms, sod farms, etc.). Others have suggested
the use of sludge as a fuel in a gasification facility near Watkins.
A number of individuals (see petition under Appendix F, Volume I,
signed by 461 persons, Letters # 1 and # 4 in comments on the draft
EIS) and municipalities (see also Appendix F, Volume I) have indicated
an interest in using Metro sludge.
More recently Metro District staff has indicated two other areas
of potential sludge marketing: in the irrigated agricultural areas
called Prospect Valley to the northeast of site B-2, and in preliminary
negotiations with fertilizer manufacturers to develop a fortified,
bagged sludge product. Metro now estimates it has a firm commitment
to use 35 percent of the available sludge product.
If anything, Metro's proposals suffer from an overabundance of
potential markets; making a definitive analysis of the firmness of
these markets is correspondingly more difficult. What has not been
done formally is a marketing study to test the feasibility and cer-
tainty of these proposed users, and the strength of the potentiaTmarket
demands. Two cities, Washington, D.C., and San Francisco, have con-
ducted studies of potential sludge marketing areas, with occasionally
conflicting and somewhat inconclusive results (References 48 and 49).
Both studies indicate, however, that the potential markets are large
enough to absorb all of the producible sludge from those cities. In
the San Francisco case, the use of sludge in bagged form for home
and specialty use (nurseries, etc.) appears to have the greatest
potential market. In the Washington study done for the 208 Agency,
estimates of potential markets varied by orders of magnitude, indicating
the extreme uncertainty involved in predicting public response, although
the potential market amounts could absorb the available sludge.
The latter point underscores the limitations of most marketing
studies. The dried sludge product is something that can be made more
or less attractive depending on public acceptance, how it is sold, and
in what form. It is essentially the imagination of the seller that
can determine how successfully sludge is eventually sold. An inter-
esting sidelight on this is the number of communities now distributing
dried sludge in some form that have adopted a trade name for their
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product: Nu-Earth (Chicago), Hou-Actinite (Houston), and BI Organic
(Boise, Idaho) are but a few listed in Table 9 under Issue II-8.
Apparently if the producer is convinced that the dried sludge product
is a salable commodity, the public thinks so too. It is also in-
structive to see in this table how much more 50-100 lb. of sludge
in bagged form can be sold for than sludge sold in bulk form.
The principal factor in the marketing situation is public
aversion/acceptance of sludge as a useful product. EPA feels that
a reasonable minimum in the way of technical design has been developed
for this project by Metro; its overall success will be determined by
how well Metro persuades the Denver metropolitan public that the
product is worth buying. EPA itself has been promoting recycling of
nutrients in sludge and wastewater and will continue to do so in the
future. EPA feels reasonably confident that Metro is capable of
promoting the distribution and sale of the dried sludge product to
make the overall project a "successful" one.
ISSUE V-4. How will controls over sludge use and management be
implemented, by Metro, the County, the State, or others?
This is an issue of obvious concern to local residents as
well as County governments. Metro's own philosophy of its role in
the management and control of sludge distribution and use is as follows
Metro Denver will strictly adhere to the State guidelines
regulating the use of sewage sludge. These guidelines are
presently being drafted and should be in their final form
within the next couple of months (see Appendix B) . Until
the implementation of this document Metro .plans to abide by
guidelines recommended by the u.s.D.A. and EPA.
Metro will provide agricultural recommendations as to the
proper use of sludge. Sewage sludge will be applied to
agricultural land at agronomic rates which will be based
upon soil analyses in conjunction with the type of crop
grown. Records of use, i.e. amount applied by individual
farmers to specific fields, and where possible, yield
results will be kept by Metro. The chemical composition
of sludge distributed will be determined; therefore, rates
of N, P, K, and heavy metals application will be known.
Since Metro is developing a long-term market it is to
Metro's advantage to ensure that the sludge materials
(Metrogro) are utilized properly to avoid any adverse
consequences from the misuse of this product.
If Metrogro is bagged, a complete chemical analysis, which
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will include macro~nutrients, Zn, Cuf Nit Cd f and Fe will
be placed on the bag. Complete control of bagged materials
is impossible since the number of potential users is so
great. Studies being conducted by EPA* Metro and U.S.D.A,
will eventually determine possible pathogen hazards. Any
bagged material sold to the public will be pathogen safe
and recommended for lawn use.
"Guidelines for Sludge Utilization on Land", a technical
policy document from the Colorado State Department of Health was
released on December 8, 1976 in draft form. A copy of these guide-
lines are included in this volume as Appendix B. The guidelines
provide a basis for evaluating the Metro sludge product and proposal;
Section IV of the document on sludge quality defines minimum/maximum
constituents of nutrients and heavy metals that qualify as applicable
to agricultural lands. Metro's sludge appears to be consistent with
this section.
Section V describes the manner in which agronomic loading rates
can be estimated for various kinds of sludge applications. Other
considerations for sludge application on land are given in Section
VI that affect potential Metro uses: for instance, sludge shall not
be applied to crops that could be eaten raw. A one year*storage
time shall be rquired for sludge to be applied to such crops. Live-
stock should not be allowed to graze on sludge application areas.
Other considerations such as site slopes, ice conditions, and depth
to the water table are also presented.
Section VIII defines the monitoring and analysis responsibilities
of the sludge producer. An amended NPDES permit or a special disposal
permit will be written for each producer of sludge. The permit will
set the required monitoring including frequency of sampling and the
required kinds of analyses. A producer will have to keep records
of sludge distribution: to be filed with the Health Department. A
blank copy of such a permit is provided in the Appendix to this docu-
ment. User permits would be required only where minimum standards
set forth in this regulation are not followed.
Given the impetus of State control and Metro commitment, EPA
believes that effective and safe management and guidance over sludge
application can be attained with the Metro offsite project. EPA will
periodically provide national guidance on technical and research
findings concerning sludge use that could be incorporated into future
State sludge use regulations.
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ISSUE V-5 What are the long-term implications for sludge recycling
to the land?
EPA has adopted a national policy strongly encouraging recycling
of sludge, wastewater, and solid waste materials. In the long-run,
there is no question that this nation will have to depend more on re-
newable resources and less on depletable resources such as coal, oil,
rock phosphate, etc.
As this EIS has pointed out, reuse of human wastes is a very
old process in agriculture. Two considerations--public health factors
and the addition of technological waste products to municipal waste-
water—have complicated and forced a thorough re-analysis of this es-
sentially ancient recycling process. It is probably true that lack
of hygenic practices may have at times contributed to the dissemination
of water-borne human diseases in this process. With the rapidly de-
veloping understanding of the nature and spread of viral and bacterial
pathogens, there appears to be no insurmountable obstacle to carefully
utilizing stabilized municipal sludge in agricultural areas. There
does remain some uncertainty regarding the exact fates of some patho-
gens, particularly viruses, but there is little in the way of sub-
stantial evidence to suggest that these viruses are a problem. Recent
studies on the worldwide distribution and inter-species interactions
of some viruses suggest that mankind is probably very limited in its
ability to affect or drastically change the various viral transmission
routes that have been established for eons. Prevention of obvious un-
hygenic and unsafe practices would appear to be the most prudent ap-
proach unless some definite evidence to the contrary is developed.
The introduction of largely chemical wastes (by-products of our
industrial society) into municipal wastes does represent a novel sit-
uation that should be approached with caution. In particular there
are heavy metals such as cadmium, chromium, etc. that do not occur in
very large concentrations naturally, and the complex toxic organics
such as PCB's and pesticides that appear to constitute the greatest
potential threat to safe agricultural recycling of municipal sludges.
At the same time, there is still little or no direct evidence that
these materials in sludge have caused or will cause severe problems.
It is generally by analogy to or extrapolation from other areas of
study (e.g., exposures to industrial workers, animal toxicology
studies, certain epidemiological cases not related to sludge handling)
that judgments about the potential significance of heavy metals and
organics in sludge are made. Much empirical research on crop uptake
of heavy metals has been done but little in the way of correlation of
this diet to human health has been firmly established.
The specific concern over heavy metals and toxic substances in
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the sludge getting into the human food chain is part of a larger en-
vironmental concern over human intake of these substances from many
different areas of industrialized society (air emissions, pesticide
applications, spills, etc.). The current EPA approach of requiring
further pretreatment by industries discharging to municipal systems
is consistent with trying to reduce the potential future body burdens
of these substances for a large population of mankind. Events and
further research could show that some significant substance was over-
looked or not adequately protected against, but again, there is no
firm basis for suggesting so at present.
The central issue for the farming community is the long-term
fate of the soils upon which sludge is to be applied. Again, there
is no evidence at present to indicate that soils would be irretriev-
ably degraded by the materials in sludge. One significant change
in using sludge instead of present agricultural practices would be
a reversal of the trend allowing a gradual depletion of soil carbon
and micronutrients through the exclusive use of chemical fertilizers.
Sludge contains carbon and many micronutrients in abundance that add
a measure of water retention and increased friability to the soil
structure. As long as current knowledge regarding soil chemistry
(Sodium Adsorption Ratio values, limiting amounts of metals and salt
that have phytotoxic effects) is followed, there appears to be a
significant potential benefit through recycling these sludge ma-
terials to the soils and little likelihood of soil damage.
The EIS discusses in Volume I, Section VII the benefits of
large scale conservation of non-renewable fossil fuel resources
used in the manufacture of fertilizers that this type of project
exemplifies. While nitrogen has received the most attention, the
supplies of mineable phosphate are similarly limited. Sludge con-
tains a fairly large concentration of phosphorus that could be re-
used in an agricultural setting.
It is EPA's overall conclusion on this project that recycling
of sludge and wastewater nutrients are an eventual certainty and one
that should be pursued vigorously now. EPA's best judgment is that
this proposal is a reasonable one that is geared to achieving the
long-range goal of recycling resources and should be supported.
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A
w
If
¦p
i
H
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References listed in this section include
published material, unpublished reports and articles,
personal communications (telephone, visits, letters,
etc.), meeting notes and other sources of data used
in the preparation of Volume II.
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SECTION D
REFERENCES
1. Putenney, John, MDSDD #1, personal communication on 27 October 1977.
2. CH2M Hill, Inc., Agricultural Soils Report, Metro Denver Solids
Drying and Distribution Center Site, for the Metropolitan Denver
Sewage Disposal District No. 1, September 1976.
3. Erdman, J. A., and H. A. Tourtelot, Denver Liquid Sewage Sludge:
Its Agricultural Benefits and Its Effect on the Metal Composition
of Wheat Grown at the Watkins Test Site, Adams County, Colorado,
U.S.G.S. Open File Report No. 76-810, 1976.
4. Furr, A. K., A. W. Lawrence, S. S. C. Tony, M. C. Grandolfo,
R. A. Hofstader, C. A. Bache, W. H. Gutenmann, and P. J. Lisk,
"Multielement and Chlorinated Hydrocarbon Analysis of Municipal
Sewaae Sludges of American Cities", Envir. Sci. & Technol. 10,
683-687, 1976.
5. Colorado State Department of Health, Technical Policy, Guidelines
for Sludge Utilization on Land, Draft Copy, 1976.
6. Food Chemical News, pp 40-41, December 20, 1976.
7. Sludge, Vol. 1, No. 7, p 52, October 1976.
8. Tessari, John, Colorado State University, personal communication
on 2 November 1977.
9. Federal Register, July 12, 1977.
10. Rippeteau, Bruce, State Archaeologist, Colorado, letter to Mike
Gansecki, EPA, on October 12, 1977.
11. City and County of Denver Wastewater Control Division, Recommended
Improvements to the Northside Wastewater Treatment Plant, Camp,
Dresser, and McKee, December 1974.
12. Thomas, Neil A., and Kinney, Robert J., Appraisal of 1920 Acres
in Adams County, Colorado, T. C. Hitchings & Sons, Inc., Denver,
Colorado, April 18, 1975.
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13. CH2M Hill, Geotechnical Report, Solids Reuse System, prepared for
MDSDD#1 , Denver, Colorado, September 1976.
14. Robson, Stanley G., U.S.G.S., letter to Mike Gansecki, EPA, on
December 9, 1976.
15. Nelson, Haley, Patterson & Quirk, Inc., Ground Water Resources
of the Lost Creek Drainage Basin, Weld, Adams, and Arapahoe
Counties, Colorado, prepared for Colorado Ground Hater Commission,
June, 1967.
16. Robsori, S. G., Ground-Water Quality Near a Sewage-Sludge Recycling
Site and a Landfill Near Denver, Colorado, U. S. Geological
Survey Water Resource Investigations 76-132, May 1977.
17. Green, John A., EPA, letter to Mr. William Korbitz, Manager,
MDSDD#1, Denver, Colorado, September 1976.
18. Todd, David K., Groundwater Hydrology, John Wiley & Sons, New
York, 1960, 336 p.
19. Chang, A. C., Olmstead, W. R., Johanson, J. B., and Yamashita,
G., "The Sealing Mechanism of Wastewater Ponds," Jour. WPCF 46,
1715-1721, 1974.
20. Lehman, 0. R., and Clark, R. N., "Effect of Cattle Feedyard
Runoff on Soil Infiltration Rates," J. Envir. Qual. 4, 437-439,
1975.
21. Miller, M. H., Robinson, J. B., and Gallagher, D. W., "Accumulation
of Nutrients in Soil Beneath Hog Manure Lagoons," J. Envir. Qual.
5, 279-282, 1976.
22. Robson, Stanley G., U.S.G.S., personal communication on 11 October
1977.
23. Anderson, George, U.S.G.S., personal communication on 11 October
1977.
24. Gerlach, Charles, Plant Engineer, San Jose Sanitary District,
personal communication on 27 August 1977.
25. CH2M Hill, Preliminary Specifications for MDSDD#1 Solids Reuse
System.
26. CH2M Hill, Agricultural Reuse Program, Metro Denver, March 1973.
252
-------
27. Colorado Fertilizer and Chemical Company, personal communication
on 25 November 1977.
28. Ettlich andvLewis, Culp, Wesner, and Culp; User Acceptance of
Wastewater Sludge Compost, Environmental Protection Technology
Series, EPA 60012-77-096, August 1977.
29. Martin, Bill, MDSDD#1 staff, personal communication in November
1977.
30. Epstein, E., Taylor, J. M., and Chaney, R. L., "Effects of
Sewage Sludge and Sludge Compost Applied to Soil on Some Soil
Physical and Chemical Properties," J. Envir. Qua!. 5, 422-426,
1976.
31. U. S. Weather Bureau, Denver Office, personal communication on
18 February 1977.
32. Davidson, G. R., T. V. Degeare, Jr., T. J. Sorg, and R. M.
Clark, Bird/Aircraft Hazards, Report SW-116, Solid Waste Manage-
ment Series, 1971.
33. Dept. of Transportation, F.A.A. Advisory Circular, Bird Hazards to
Aircraft, AC No. 150/5200-3A, March 2, 1972.
34. Engineering-Science, Inc., Pipeline Transport of Digested Sludge
to Strip Mine Spoil Site for Spoil Reclamation, National Environ-
mental Research Center, U.S. EPA, August, 1975.
35. Hinesly, T. D., Jones, R. L., Tyler, J. J., and Ziegler, E. L.,
"Soybean Yield Responses and Assimilation of Zn and Cd from
Sewage Sludge-Amended Soil," Jour. WPCF 48, 2137-2152, 1976.
36. Zeng, R., Peterson, J. R., Brooman, D. L., and Lue-Hing, C.,
"Environmental Impacts of Land Application of Sludge," Jour.
WPCF 48, 2332-2342, 1976.
37. Turk, Donald L., Tri-County District Health Department, Engle-
wood, Colorado, Letter to John A. Green, EPA, on 28 September
1976.
38. U. S. Environmental Protection Agency, Application of Sewage
Sludge to Cropland: Appraisal of Potential Hazards of the Heavy
Metals to Plants and Animals, Report MCD-33, Nov. 15, 1976.
39. CH2M Hill, Metro Denver District Sludge Management Volume III,
Agricultural Reuse System Predesign for MDSDD#!, February 1975.
253
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40. Sieger, R. B., and Maroney, P. M., "Incineratiori-Pyrolysis of
Wastewater Treatment Plant Sludges," prepared for the EPA Tech-
nology Transfer Design Seminar for Sludge Treatment and Disposal,
1977.
41. Metcalf & Eddy, Inc., Wastewater Enqineerinq: Collection Treat-
ment, Disposal, McGraw Hill Book Co., New York, 1972, 782 p.
42. Metro response to EPA queries on Metro Sludge Project, cover
letter dated 9 June 1977.
43. Sludge, Vol. 1, No. 9, p. 71, December 1976.
44. Knezek, B. D., and Miller, R. H., Application of Sludges and
Wastewaters on Agricultural Land: A Planning and Education^
Guide, North Central Regional Committee NC-118, (also Research
Bulleton 1090, Ohio Res. and Devel. Center, Wooster, Ohio.)
45. Hinesly, D., and Sosewitz, Ben, "Diaested Sludae Disposal on
Crop Land," Jour. WPCF 41, 822-830, 1969.
46. CH2M Hill, Draft Operations and Maintenance Manual, Solids
Reuse System.
47. SIudge, Vol. 2, No. 9, p. 68, September 1977.
48. Gruen, Gruen & Associates and Culp, Wesner, and Culp, San
Francisco Bay Region Wastewater Solids Study, Marketing Report,
"[Phases I and II), March 3, 1977.
49. Hand, C. W., Gershnan, H. W., and Navarro, P., "Market Study for
Composted Sewage Sludge in the Metropolitan Washington Area: A
Case Study," in: Proc. of the Third Nat. Conf. on Sludge Manage-
ment, Disposal, and Utilization, December 14-16, 1976, Miami
Beach, Florida.
50. CH2M-Hi11. Sewage Treatment Plant Expansion, Predesiqn Study,
for MDSDD#1, April 1972.
51. Adams County Tax Assessor's Office, personal communication on
7 February 1978.
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M
Biii
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255
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This appendix contains the proposed grant conditions
which must be implemented by Metro before EPA will allow
Step II or Step III grant funds to be allocated for the
project.
256
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APPENDIX A
PROPOSED GRANT CONDITIONS FOR
METRO OFFSITE SOLIDS PROJECT
1. The grantee shall agree to complete an industrial pre-treatment
survey within a year period following this agreement identifying
contributing sources of heavy metals and industrial organics, and
likely reductions available with added pre-treatment. The grantee
shall agree to provide a report to EPA and the State Water Pollution
Control Division containing the above information.
2. The grantee shall agree to hire a qualified archaeologist to
monitor the progress of excavation/construction of the offsite solids
pipeline from the Metro Central Plant to Colorado Boulevard. In
other areas, the nrantee shall reimburse the archaeologist to train
a qualified Metro employee(s) to recognize archaeological artifacts
and to follow the proper procedures in the event of a significant
find. Metro will agree to identify an individual(s) responsible for
identifying archaeological resources.
The grantee shall take the following steps in the event of an
archaeological find:
a. Construction work shall be halted to protect the discovery.
b. The State archaeologist and EPA shall be notified and be
allowed to inspect the find.
c. The archaeologist hired to perform the work described above
can be used under b., in lieu of the State archaeologist.
d. If a determination is made that construction needs to be
halted for more than a single working day, the State Water Pollution
Control Division will also be notified. Steps will immediately be
taken to protect the archaeological resource as well as to minimize
construction delays.
3. The grantee shall agree to develop as part of the Operations and
Maintenance Manual for this project, the following conditions:
a. A contingency plan, to be followed in the event of a pipeline
disruption/shutdown. The procedure for handling sludge during the
downtime, considering the extent of storage available, will be ex-
plained. For a pipeline break, the grantee will explain how emergency
procedures will be followed to prevent contamination of surface water,
groundwater and adjacent properties;
257
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b. A contingency plan explaining how sour digester contents
will be handled at the plant or in the event of a need to dispose
of soured sludge. Such a plan will detail where the sludge will be
buried, the type of equipment to be used, and the proposed rate of
application of sludge and critical constituents. The applicant agrees
to follow agronomic rates in such a form of emergency disposal;
c. A contingency plan to mitigate windblowing of stockpiled
sludge;
d. An emergency procedure to be used in the event the ground
water below the site violates drinking water quality standards. The
grantee s|iall specify the manner of removal of contaminated percolate
from aquifers including the form of treatment of the contaminated
water;
e. A comprehensive ground water monitoring program at the site
acceptable to the Colorado Department of Health and Region VIII EpA.
A monitoring plan should be laid out and submitted to both agencies
for approval. It should include exact locations and depths of moni-
toring wells, information on how they will be sampled, at what fre-
quency, specifics on the analytical determinations to be made and to
whom information will be submitted. The plan should be implemented
in time for 6 months of sampling to be accomplished prior to use of
the sludge disposal site; and
f. A vector control program for the site.
4. The grantee shall agree to pursue negotiations with the City of
Denver Wastewater Control Division and Denver City Parks Department
to optimize arrangements between these parties and the Metro District
to treat and use sludge in the Metro offsite solids project. The
grantee will agree to submit a report outlining the chronology of
events, and status of agreement between the two parties prior to
final payment of the construction Step III grant.
5. The grantee shall develop an impervious liner on all areas of
site B-2 to be used to hold and dry liquid sludge. This shall in-
clude any ground areas considered to be at or below the high water
mark of the drying beds. The liner shall be of a permanent nature
and meet the following performance specifications:
a. The liner shall be the equivalent of a compacted clay layer
12" thick and have a measured permeability after compaction of no
more than 1 X 10"7 cm/sec.
b. A suitable cover material the equivalent of at least 12" of
a suitable soil type shall be placed over the liner to insure that the
258
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liner is not disrupted by subsequent operations.
Further, the grantee shall agree to furnish proof during con-
struction in the form of permeability test data that the performance
standards are met. Test data shall be submitted to the EPA, the
State Wastewater Pollution Control Division and Adams County. Should
a lining and cover material other than stated above be chosen, the
grantee will have to submit a lining plan to EPA before construction
demonstrating that the above performance standards will be met.
6. The grantee agrees to report any violation of drinking water qual-
ity standards to the Colorado Department of Health and the Tri-County
Department of Health. Monitoring test data on water quality will also
be submitted to these Departments at least quarterly and more often
if requested.
7. The grantee will agree to incorporate changes in design to the
dried sludge storage portion of the site to preclude or minimize
windblowing of stockpiled sludge offsite. The grantee will agree to
study the incorporation of earth berms in the storage area design
and report its conclusions to EPA before Step III funds are issued.
8. The grantee shall agree to take necessary steps to minimize weed
growth on the site. The grantee also agrees to develop a contingency
plan to minimize aquatic weed growth in the storage reservoir that
could serve as a habitat for waterfowl.
9. The Metro District will agree to retain dried sludge onsite (ex-
cept for municipal parkland uses or for landfill disposal) until State
guidelines for sludge reuse have been formally promulgated.
10. The Metro District will provide adequate warning or otherwise
prevent from distribution, the use of the dried sludge product in
the following areas:
a. Parkland areas where direct human contact is likely (apart
from park personnel);
b. In use on home gardens on leafy vegetables and crops that
take up heavy metals, or on crops that could be eaten raw;
c. On irrigated farms, on crops that could be eaten raw;
d. Any widespread use on dryland farms until firm guidelines
for the amounts and timing of sludge applications are available; and
e. Any designated or known wetland and floodprone areas.
259
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11. The Metropolitan Denver Sewage Disposal District No. 1 will,
insofar as it has influence and authority, limit annual application
rates of cadmium in sludges produced by the facility to 2 kg per
hectare [1.8 lbs per acre] for dewatered sludges and 1 kg per hec-
tare [0.9 lbs per acre] for liquid sludges applied to cropland. Th«
grantee will agree to recommend this limit for cropland applications.
260
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H
1
¦^1
261
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This appendix contains a copy of the State of
Colorado Draft Guidelines for sludge application to land.
262
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263
STATE OF COLORADO
DEPARTMENT OF HEALTH
Technical Policy
."V
* i *
COPY
¦ BRAF^
''i II ¦'/
11 //
GUIDEIilNES .FOR
SLUDGE ' i UTILIZATION
LA'ND
^ lON
\W
//
•A
- Referenced to > 1
\C.R.sl l973, 25-'l/107
V'\\ 25*8-202 (I), (l)(c),(2)
V\ 25-0-205 (I)(a),(|)(b), (l)(c)
\\\ 25-0*207 (l)(c)
V \; l 30-20-102(3)
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264
GUIDELINES FOR SLUDGE UTILIZATION
ON LAND
INDEX
Page
I Acknowledgments 3
II Introduction 4
III Definitions 6
IV Sludge Stability 9
V Sludge Quality 11
VI Nutrient and Trace Elements Application 12
VII Sludge Application on Land 16
VIII Sludge Storage 19
IX Monitoring and Analysis 23
X Permit Requirements 26
APPENDIX
Example Calculations 29
Tables 32
Figures 34
User Permit 35
Information Sheet 37
Universal Soil Loss Equation
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265
i
ACKNOWLEDGMENTS
The State of Colorado Department of Health wishes to ccnirend the members of the
Sludge Task Force for their efforts in the development of these Guidelines.
These Guidelines represent the cooperative effort of the entire Sludge Task Force,
however, it should be recognized that individual members of the Task Force may
not agree with all of the criteria as set forth in this document.
Sludge Task Force
Chairperson
Ruth Wright
State Board of Health
1911 - 11th Street
Boulder, Colorado 80302
Micki Barnes
Office of the Governor
State Capitol
Denver, Colorado 80203
Susan Griffiths
Colorado Municipal League
4800 Wadsworth Blvd, Suite 204
Wheat Ridge, Colorado 800 33
Dan Johnson
Colorado Counties, Inc.
1.500 Grant Street
Denver, Colorado 80203
Richard D. Johnson
Wright-McLaughlin Engineers
2420 Alcott Street
Denver, Colorado 80211
Daniel Lav/
Denver Regional Council of Governments
1776 South Jackson, Suite 100
Denver, Colorado 80210
Anthony Joe Madonna, Director
Boulder County Solid Waste Program
P.O. Box 471
Boulder, Colorado 80302
William J. Martin
Metropolitan Denver Sewage Disposal
District No. 1
6450 York Street
Denver, Colorado 80229
Hester P. McNulty
League of Women V'oters
2160 Vasaar Drivo
Boulder, Colorado 80 30 3
Don Miles
CSH Extension Service
P.O. Box 190
Rocky Ford, Colorado 81067
Frank J. Rozich, Director
Water Quality Control s
Public Health Engineering Division
Colorado Department of ilcalLh
4210 F.. 11th Avenue
Denver, Colorado 80220
Burns Sabey
Colorado Static University
Agronomy Department
Fort. Collins, Colorado 80521
Jim Schwing
CH2M II ill
12000 E. 47th Avenue
Denver, Colorado 80239
Kobort D. Siak, Assistant director
Department or" Health, Env: ronmfintal
Hea]th
Colorado Department of Health
42]0 E. 11th Aver.ue
Denver, Colorado 80220
Or"ille Stoddard
Project Director Solids Wast;?
Management Projects
Engineering Eoction
Colorado DCp-rtnerit of ti' ilth
4 210 E. 13. th Avenue
Denver, Colorado G0220
L. Turk
Tr i -County biotrict ileal Mi Dcp^rtm«.'r.t
•1ftr>7 South i.O'onriw.v/
tiii'i J I'wood , Colorado 30110
Peter I. Vrcn
Cole. Dept. cf Agriculture
re<_il or lVi. lili .'.or acei-ion
2331 toest .Use Avenue
Denver, Colorado r>0211
J. Mi.chm?l W^Ilnce
Environmental Affairs Ariministratcr
Adolph Coorr Conpany
Go] Jon, Colorado 80401
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266
II
INTRODUCTION
Sludge utilization on land comes at a time when our Nation
is valuing its natural and energy resources as never before.
The United States Congress passed into law the Federal Water
Pollution Control Act Amendments of 1972 as PL 92-500. The
Act encourages recycling of sludge through agricultural pro-
duction and the ultimate disposition of sludge in a manner
that will not result in environmental degradation. It is
therefore appropriate that Colorado consider carefully the
opportunities that are presented by the recycling of sludge
onto land. A policy on the utilization of sludge is neces-
sary in order to give direction to the producers, handlers
and users.
These guidelines are presented for the utilization of sludge
as a recyclable resource. The guidelines address methods of
sludge handling, storing and application which provide for
maximum reasonable control of potential environmental problems.
These guidelines will minimize administrative procedures and
allow sludge to be applied more readily at agronomic rates in
an environmentally acceptable manner on land throughout the
State of Colorado.
The Colorado Department of Health has concluded that an en-
vironmentally acceptable alternative for solving sludge
management problems is utilization of stabilized sludge on
land for agriculture, silviculture or reclamation purposes.
This recycling will help to conserve the nutrients, humus,
and energy resources of the State while serving its economy.
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267
Sludge contains the concentrated waste of the community and
certain components of sludge may be toxic and/or hazardous
depending upon their concentration and the intended means
of disposal. Application of sludge containing these compon-
ents, as well as the nutrients nitrogen (N) and phosphorus (P),
to the surface and groundwaters must be controlled to prevent
degradation in water quality. In addition, the salt content
of sludge may inhibit plant growth if applied to soils in
high concentrations or at an inappropriate time. Therefore,
the quality of the sludge together with agronomic application
rates are the keys to an environmentally sound land applica-
tion program.
The management of sludge generated by wastewater treatment
plants in Colorado is subject to the regulations promulgated
by the Colorado Board of Health, the Water Quality Control
Commission and the Department of Agriculture. Administration
and enforcement of the regulations are handled by the Colorado
Departments of Health and Agriculture. The program is based
upon the best available technology; thus, the main thrust
of municipal sludge projects is utilization, as this makes
best use of this resource. However, in isolated instances due
to economics or an unacceptable sludge, landfilling, land
disposal, or other techniques may be the best alternative
available.
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268
III
DEFINITIONS
Aerosol - A gaseous suspension of ultra microscopic particles
of a liquid or solid.
Agronomic Rates - An application rate of plant nutrients that
can reasonably be expected to be taken up and utilized by
agricultural crops.
Department - The Colorado Department of Health.
Dried Sludge - Sludge that has been dewatered to 13% solids
or greater and can be transported and handled as a solid
material.
Incorporation - To mix the sludge with the soil in the upper
horizon by such means as subsurface injection, rotQtilling,
discing, or plowing.
Sludge - The accumulated solids resulting from processing
sewage in a treatment plant.
NPDES Permit - National Pollutant Discharge Elimination System
permit. A permit system established under the authority of
the Federal Water Pollution Control Act Amendment of 1972.
The permit system is administered by the Colorado Department
of Health.
Off-Site Storage - The storage of sludge at a site which is
not under the jurisdiction of the Producer and outside of
the transporting vehicle.
On-Site Storage - The storage of sludge at a site which is
under the jurisdiction of the Producer.
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269
Pathogen - An organism, chiefly a microorganism, including
viruses, but also including all forms of animal parasites,
that are capable of producing an infection or disease in a
susceptible host.
Person - An individual, corporation, partnership, association,
state, or political subdivision thereof, federal agency,
state agency, municipality, commission, or interstate body.
Producer - Operator of the wastewater treatment facility gener-
ating sludge intended for use on land.
Speciality Fertilizers - Dried stabilized sludge distributed
primarily for non-farm use, such as gardens, lawns, shrubbery,
flowers, golf courses, parks, cemetaries, greenhouses, nur-
series, and hydroponics.
Spray Application - Liquid sludge application by sprinkling
devices such as center pivots and stationary or movable spray
irrigation mechanisms. Spray application does not include
application by tank truck spreading devices emitting a stream
of less than 10 feet in any direction, and not creating aero-
sols .
Stabilized Sludge - Liquid or dried sludge from wastewater
treatment plants that has been treated to obtain pathogen
destruction, volume and weight reduction, odor control, and
putrescibility control.
State Waters - Any and all surface and subsurface waters
which are contained in or flow in or through Colorado,
except waters in sewage systems, waters in treatment works
or disposal systems, waters in potable water distribution
systems, and all water withdrawn for use until use and treat-
ment have been completed.
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270
Surface Application - Application of sludge to the land sur-
face by means other than spray application as defined herein.
Trace Elements - Those elements generally found in small con-
centration in municipal wastewater. Trace elements can be
concentrated to higher levels in municipal sludge and can be
toxic to plants and animals at higher levels. Those elements
of most concern are cadmium (Cd), copper (Cu), lead (Pb) ,
zinc (Zn), and nickel (Ni).
User - The person applying sludge to land.
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271
IV
SLUDGE STABILITY
The purpose for stabilizing sludge is to obtain pathogen
destruction, volume and weight reduction, odor control,
and putrescibility control to the point where they will
not present a public health hazard or nuisance.
Stabilization of sludge can be by chemical treatment, diges-
tion, incineration, heat treatment or composting, the most
common form being digestion by aerobic or anaerobic means.
These guidelines concentrate on acceptable levels of stabili-
zation through aerobic and anaerobic digestion. Sludge from
other stabilization processes and sludge not meeting the
following criteria will be considered the Department on
a case-by-case basis. The following are standards for
ascertaining the stability of sludge:
A. Aerobic Digestion of Sludge
1. Hydraulic detention time shall be 15-20 days secondary
sludge alone; 20-25 days secondary sludge + primary.
2. Volatile solids reduction shall be 40% or greater.
B. Anaerobic Digestion of Sludge
1. Volatile solids reduction shall be 40% or greater.
Normally, this can be accomplished in a high rate
digestion system after 20 days digestion under meso-
philic conditions. For a thermophilic digestion
system, 15 days detention is normally required. In
a standard rate system, 30 to 40 days detention time
is normally required.
2. pH shall be 6.8 to 7.8.
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272
Volatile acids concentration shall be less
500 mg/1. Some variation of this level is
possible depending on the alkalinity of the
sludge under digestion.
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273
V
SLUDGE QUALITY
Stabilized sludge which is to be applied to land does not
require aV permit if it does not exceed the levels established
as minimum standards. Sludge not meeting these criteria will
be considered by the Department on a case-by-case basis.
Constituents
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Minimum Standards
(Dry Weight Basis)
Nutrients
Level
6%
6%
1%
Normal
Range
2-6%
2-6%
.25-1%
Trace Elements
Constituents
Zinc (Z)
Copper (Cu)
Lead (Pb)
Nickel (Ni)
Cadmium (Cd)
Level
3000 ppm
1500 ppm
1500 ppm
1000 ppm
30 ppm
Normal
Range
500-3000 ppm
250-1500 ppm
100-1500 ppm
25-1000 ppm
5-30 ppm
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274
VI
NUTRIENT & TRACE ELEMENTS APPLICATION
The following guidelines pertain to stabilized sludge.
Application rates not requiring a User Permit are limited
to agronomic applications as set forth in the following
paragraphs. Higher application rates will be considered
by the Department on a case-by-case basis.
A. Nutrient Availability by Methods of Application
Different methods of application result in different
percentages of ammonia nitrogen in the sludge that
will be available to the crop being grown. For design
purposes the following percentages should be used.
1. Surface application of liquid sludge without incorp-
oration results in about 80% loss of ammonia nitrogen
leaving about 20% of ammonia available for plant
growth.
2. Surface application of liquid sludge with immediate
incorporation results in 30-70% loss of ammonia
nitrogen, 'depending on how soon incorporation occurs.
3. Subsurface application of liquid sludge results in
negligible loss so nearly 100% of the ammonia nitrogen
would be available.
4. Some losses of nitrate nitrogen can occur when deni-
trification proceeds as soils are aerated and then
flooded for a period of several days.
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275
5. The Five-Year Cycle of Organic Nitrogen Availability:
In the first year after the sludge application, 203
of the organic nitrogen is available to the crop.
In the second year it is assumed that another 10%
of the remaining organic nitrogen becomes available
to the crop from the sludge applied the first year.
Additional sludge can be applied to provide additional
available organic nitrogen to the crop. In the third
year, 5% of the organic nitrogen applied in the first
year will become available. In addition, another 10%
will become available from sludge applied during the
second year. Again, additional sludge can be applied
to provide additional available orcranic nitrogen to
the crop. The fourth and fifth years are similar to
the second and third years' pattern with 1.25%, 2.5*,
5% and 10% of the remaining fraction of the organic
nitrogen becoming available to a fifth year crop from
the first, second, third and fourth year applications,
respectively (see Table 1 of the Appendix). After the
fifth year it is thought that no appreciable organic
nitrogen will become available for crop usage from the
first year application. Five years or more after appl
cation the sludge will not yield appreciable nitrogen
for crops. Calculations should be made to determine
in what year equilibrium will be reached for any
design scheme. Sample calculations are included in
the Appendix.
Summary of Factors Governing Loading Rates:
The basic premise governing sludge application to agricul-
tural land is that rates shall be based upon agronomic
requirements for crop fertilization. If necessary,
supplemental fertilizer should be applied to balance the
nutrient supply required by the crop.
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276
There are three major areas of consideration: nitrogen,
phosphorus, and trace elements.
1. Nitrogen: In the short-range (five years), nitrogen
in the sludge is considered to be the limitinq factor
to application rates. In a typical Colorado situa-
tion, maximum loading rates of sludge applied to
the land are based on the nitrogen required for
growing a crop. Sludge shall not be applied at rates
that exceed the nitrogen fertilization rate (plus
losses) for the crop grown as specified in Table 2
in the Appendix.
2. Phosphorus: In the long run, phosphorus content of
the soil may govern loading rates for the sludge.
After five years the phosphorus level in the soil
should be determined and sludge application be re-
duced or ceased if the phosphorus content in the
soil, as determined by the Olsen Bicarbonate Test,
exceeds 400 pounds per acre.
3. Trace Elements: For the short-range, the loading
rates calculated to provide nitrogen for growing crops
usually result in the application of trace elements
to the soil in amounts that would not be harmful from
a water and food chain standpoint. In the long run,
the trace elements content in the soil should be moni-
tored for trace element buildup. The frequency of
monitoring of the soil will be dependent upon the
quality of the sludge. Monitoring of the trace ele-
ments in the sludge soil mixture should be done once
every five years starting with the fifth year of con-
tinuous application.
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277
Most of the trace elements in sludge applied to
soils are retained in surface soils; only small
amounts may go into solution. Thus, pollution
potential for surface waters is greater than that
of ground water. Since trace elements applied to
the soil are largely concentrated in the surface,
drainage from surface soils into surface waters may
contribute to pollution of state waters. Concentra-
tion of trace elements in water considered to be
toxic to aquatic organisms are, in many cases, lower
than those considered toxic to higher plants and
animals. Since these tolerances are so low, surface
run-off of either sediment or solution into surface
waters must be held to a minimum.
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278
VII
SLUDGE APPLICATION ON LAND
It is of vital importance that a sludge application program
be carefully managed and regulated to avoid ground and
surface water pollution and potential health and aesthetic
problems. All sludge which is to be applied to land must
be stabilized.
A. General Considerations
1. Crops: Sludge shall not be applied directly to
crops that could be eaten raw. Stabilized sludge
which has been stored on-site (i.e., a site under
the jurisdiction of the Producer) for a minimum of
one year prior to application may be applied to
land where crops are produced that could be eaten
raw.
2. Cropping: Sludge shall not be applied to land which
will lie fallow for more than one cropping cycle
(maximum one year and one-half). Where liquid sludge
is applied to pasture crops, it is recommended that
livestock not be allowed to graze on the pasture
until the sludge has been washed from the foliage
by rainfall or irrigation.
3. Precipitation: Sludge shall not be applied during
precipitation or when precipitation is imminent.
B. Application Methods
1. Incorporation: Incorporation is the preferred method
of application for conservation of nitrogen. It also
minimizes potential aesthetic problems. No User Per-
mit is required when greater than 20 feet from occupied
dwellings.
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279
2. Spray Application: A User Permit is required.
The Department will review each spray application
request on a case-by-case basis.
3. Ridge and Furrow Application: A User Permit is
required. The Department will review each ridge
and furrow application request on a case-by-case
basis.
C. Site Considerations
1. Slope: For surface application, the slope of the
receiving land must not exceed 5%, or the land
must have sufficient soil conservation measures
established that average annual soil losses will
be less than five tons per acre, as determined by
the Universal Soil Loss Equation (USLE, see Appendix).
However, if the sludge is incorporated into the soil,
it may be applied on slopes of up to 8% regardless
of the annual soil loss. For slopes in excess of
eight percent, the annual soil loss cannot exceed
five tons per acre.
No User Permit is required for these slope conditions.
2. Ice-Covered, Snow-Covered or Frozen Land: Sludge
may be applied on ice-covered, snow-covered, or
frozen land without a User Permit provided the land
does not exceed a 5% slope. If the land does not
exceed a 5% slope, sludge may be applied provided
the annual soil loss does not exceed five tons per
acre as determined by the USLE.
3. Water-Ponded or Saturated Land: Sludge shall not be
applied on water-ponded or saturated land.
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280
4. Depth to Mean Annual Groundwater Table: No User
Permit is required when the mean annual groundwater
level is greater than 7 feet from the surface of
the land.
5. Distance From a Domestic Water Well: No User Permit
is required when greater than 150 feet.
6. Flood Plain: No User Permit is required when outside
of the 10-year (10%) flood plain.
7. Soil Texture: Application of sludge on land comprised
of loamy sand or coarser material, as described in
the U.S. Department of Agriculture Textural Chart,
requires a User Permit. See Figure 1 of the Appendix.
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281
VIII
SLUDGE STORAGE
Unstabilized sludge may be retained at the wastewater treat-
ment facility while awaiting stabilization provided the
facilities used for retention of said sludge have met the
appropriate requirements of the Department. This chapter
of the guidelines deals specifically with the storage of
stabilized sludge.
All sludge which is to be stored until use must be stabilized.
A prime consideration in the storage of sludge is the :-Tr>tac-
tion of state waters from pollution. Sludae should r;¦.r be
stored on a site where the drainage therefrom could pollute
surface or ground water.
Other considerations regarding sludge storage are to ensure
that the pathogenic organism content has been reduced rind
l.o minimize insect and rodent infestation and odors t"
point where they will be inoffensive. Control measur .rmst:
be- instituted if problems exist in the operation of thf;
storage site. Factors that will affect the odors emitto'
from a sludge storage area include the degree of stabili; atirn,
the volume of sludge stored and climatic conditions. Total
odor emissions are directly proportional to the effective
exposed surface area of the storage facility. For licui :
sludge, wave action or turbulence increases the total effective
surface area and therefore total emission. With rcemrrts tn
climatic conditions, odors can be intensified through precipita-
tion, increase in temperature, wind action and atmospheric
inversions.
kludge storage sites must comply with local zonina and adopted
comprehensive land use plans.
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282
Storage of sludge is permissible provided that the following
criteria are followed:
A. On-Site Storage of Stabilized Sludge (i.e., Storage at a
Site Which is Under the Jurisdiction of Producer)
1. Dried Sludge:
a. Sludge may be stored on properly designed
sludge drying beds approved by the Department.
b. Dried stabilized sludge meeting established
minimum standards shall be stored in a manner
and location so as to protect state waters
from pollutants.
2. Liquid Sludge:
a. Liquid sludge may be stored in properly designed
sludge drying beds approved by the Department.
b. Storage of liquid sludge will be permissible
only in properly designed storage facilities
approved by the Department.
B. Off-Site Storage of Stabilized Sludge (i.e., Storage at
a Site Which is Not Under the Jurisdiction of Producer)
1. Dried Sludge:
a. Sludge shall be stored in a manner and location
so as to protect state waters from pollutants.
b. Sludge shall be stored in a manner and location
so as to prevent nuisances.
2. Liquid Anaerobically Stabilized Sludge:
Liquid anaerobically stabilized sludge must be stored
by enclosing the sludge in a structure approved by
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283
the Department and not directly accessible to the
outside atmosphere. Closed storage facilities shall
have an air breather vent pipe(s) properly capped to
preclude the entrance of precipitation. Minimum
height from top of vent to ground level shall be
ten (10) feet. Appropriate signs shall be posted
in the immediate vicinity of the storage facility
which as a minimum must state, "DANCER, NO SMOKING."
Closed facilities having an effective volume in
excess of one (1) million gallons shall incorporate
into the vent design a device to minimize point
source emissions of odors.
Storage facilities shall be properly designed to
prevent explosive situations. Electrical eauipment
in the immediate vicinity of the closed storage
facility shall comply with the National Board of
Fire Underwriter's specifications for hazardous
connections. Any forced air ventilation equipment
shall be fabricated from non-sparking material.
Access shall be provided for all closed liquid storage
facilities. Entrance into such facilities shall not
be done without the use of self-contained oxygen-
supplying equipment approved by Colorado Occupational
Safety and Health Administration.
Closed liquid storage facilities must be constructed
with relatively impermeable materials (clay, concrete,
or equivalent).
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284
Under isolated conditions and upon approval of the
Department, open storage may be permissible.
3. Liquid Aerobically Stabilized Sludge:
a. The storage site shall be isolated from residen-
tial and commercial developments.
b. The storage facility shall be of a design
approved by the Department.
c. Aeration equipment shall be provided to maintain
measurable amount of dissolved oxygen.
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285
IX
MONITORING AND ANALYSIS
Sludge monitoring and analysis is the responsibility of
the Producer. A Producer of sludge which is to be used
in land application must monitor and analyze the sludge
according to conditions set forth in the NPDES permit.
In developing a sludge utilization program, representative
sludge samples and adequate analyses of the sludge are re-
quired. To obtain a representative sample, a number of
samples collected periodically over a twenty-four hour
period should be composited. Samples should be stored in
sealed glass or plastic bottles in a refrigerator and
analyzed as soon as possible. It is beyond the scope of
this document to give details on how to conduct analyses of
sludge. The methods are set forth in the documents listed
below. Certain analyses, particularly of the trace cLements,
require complicated instrumentation and trained technicians.
Except for larger organizations, these analyses should not be
undertaken by the entity. Care must be taken with the nitro-
gen analyses, as ammonia volatilizes readily from the sample
and an underestimate of the nitrogen content of sludqe can
result. Acceptable methods of analyses are contained in the
following documents: (1) United States Environmental Protec-'
tion Agency, Methods for Chemical Analysis of Water and Wastes
(197 4), (2) American Public Health Association, Standard
Methods for the Examination of Water and Wastes (Current Edition).
A. Frequency of Sampling
1. All plants with a treatment capacity of up to 10
million gallons a day (10 MGD) require a minimum
of one sludge analysis quarterly.
2. All plants with a treatment capacity of 10 million
gallons a day (10 MGD) or more require a minimum
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286
of one sludge analysis monthly.
3. The Department may require increased frequency of
sludge analysis in specific cases.
B. Collection of Samples
1. Sludge Storage or Drying Basins (Solid and Semi-
Solid Sludge)
a. Collect samples during dry periods and not
sooner than 48 hours following the last
measurable precipitation. Samples should not
be collected sooner than 48 hours following
a thaw.
b. To obtain a representative sample from a solid
or semi-solid sludge which is evenly dispersed
in a storage basin or drying area, the area is
divided into six equal sections. Core samples
of approximately 1/2 pound each are taken from
the centers of these sections. The core samples
are then composited. The composite sample shall
be refrigerated at 4°C and the required analyses
run as soon as possible.
c. To obtain a representative sample from piled or
windrowed sludge, take at least six core samples
of approximately 1/2 pound each from representa-
tively random sections of the piles or windrows
and composite.
2. Digesters and Storage Tanks (Liquid Sludge)
A composite sample should be procurred and the
sample should be representative of the sludge
which has been pumped from the digester or from the
storage tank over a 24-hour period. This sample
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287
should consist of a minimum of three grab samples
of 500 ml each taken at the start, middle and
end of the pumping cycle. If pumping is continu-
ous or with brief interruptions during the day,
grab samples of 2 50 ml each should be taken hourly
and composited. The composite sample shall be
refrigerated at 4°C and the reouired analyses run
as soon as possible.
C. Analyses Required
1. Percent Total Solids
2. Percent Volatile Solids
3. pH
4. Volatile Acids (for liquid anaerobic sludge)
5. Ammonia Nitrogen
6. Organic Nitrogen
7. Total Nitrogen
8. Total Phosphorus
9. Total Potassium
10. Conductivity
11. Trace Elements (Total)
a. Copper
b. Zinc
c. Nickel
d. Lead
e. Cadmium
12. The Department may require additional analyses, particu-
larly for those plants providing wastewater treatment
for industry.
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288
X
PERMIT REQUIREMENTS
A. Producer
1. The Producer has the responsibility for the sludge
up to the point of acquisition by the User.
2- Where the Producer of sludge possesses a NPDES Permit,
the permit will be amended to include the require-
ment regarding the disposition of the sludge. The
permit will reflect the analyses which are required,
the frequency of the analyses and the method for
reporting the results.
3. Where the Producer of sludge is not required to
possess a NPDES Permit, he shall contact the Depart-
ment to obtain a special permit relative to the
disposition of sludge. The permit will reflect the
analyses which are required, the frequency of the
analyses and the method for reporting the results.
4. The Producer is required to maintain dried and liquid
stabilized sludge distribution records for all sludge
produced and distributed. The Producer shall file
these records with the Department on a quarterly basis.
The records of the Producer shall be available to the
Department for periodic review upon request.
5. Sludge that is marketed must be registered with the
Colorado Department of Agriculture.
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289
6. Failure of the Producer to acquire a valid permit
will subject the Producer to prosecution under
Colorado State law.
B. User
1. No User Permit is required when the sludge and its
application complies with all of the established
minimum standards set forth in these guidelines.
2. No User Permit is required when the sludge is used
as a speciality fertilizer, providing that the sludqe
has received an on-site storage time of not less than
one year including the time required for drying unless
thermally processed to ensure pathogenic destruction.
3. A User Permit is required when the sludge or its appli-
cation is not in compliance with all of the established
minimum standards as set forth in these guidelines.
4. Failure of the User to acquire a valid permit when
a permit is required will subject the User to prose-
cution under the Colorado State law.
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290
APPENDIX
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291
Example Calculation For Determination Of Nitrogen Requirements
For Sludge Application To Land
The following procedures are recommended for calculating sewage
sludge application rates for a field if you have a SOIL TEST
REPORT or if you do not have a SOIL TEST REPORT.
WITH SOIL TEST — (This is most desirable)
A. Obtain nitrogen recommendation in #/acre » (A) from
test results.
B. Calculate the available N from NH4 in sludge added for
the current year using the following formula:
, j 2000 #/ton
%NH -N in sludge x ... ,^9,\
4 100 (conversion from %)
= %NH4-N x 20 = (B) #NH -N/ton sludge
4 — 4
If surface applied and not incorporated until dry, reduce
this value (B) to one-fifth or multiply it by 1/5 or 0.2.
C. Calculate the available N from organic N in sludge added
for the current year using the following formula:
%organic N x x 0.2 (mineralization rate, 20%)
= % organic N x 4 - (C) # organic N/ton
D. Residual sludge N in soil ¦ (D) # N/A
If soil has received sludge in the past five years,
calculate residual N from Table 1.
E. Sludge application rate, tons/acre (E)
= Nitrogen recommendation/ #/acre - Residual N, #/acre
# available N/ton sludge
* !b{ ~ {°!
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292
Example Calculation
Corn; Weld County; yield potential - very high
Soil test results Fertilizer recommendations
Texture: clay loam Corrective and Maintenance
Organic matter: 1.5% N: 160 #/acre
NO-j-N: 12 ppm
Sludge Analyses
NH^-N = 1.5% Organic N = 2.5%, Surface application-3rd year;
5 tons/acre applied in year 1 and 2.
1. Fertilizer N recommended = 160 #/acre = (A)
2. Available N from NH^ in sludge (current year)
1.5 (%NH^-N) x 20 x 0.2 (for surface application)=
6 #/ton = (B)
3. Available N from organic N in sludge (current year)
2.5 (% organic N) x 4 = 10 #/ton = (C)
4. Residual N, from Table 1 for 2.5% organic N
Sludge added 1 year previous 5 tons/acre x 5 = 25 #/acre
Sludge added 2 years previous 5 tons/acre x 2.5 = 12.5
#/acre
Total residual N = 25 + 12.5 = 37.5 #/acre = (D)
5. Sludge application rata - $ ; jg> - "° I ^'5 -
7.66 or about 8 tons/acre
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293
WITHOUT SOIL TEST — N requirement can be obtained from Table 2
instead of a SOIL TEST REPORT (This is not
as desirable as getting the N requirement
from a soil test).
A. Obtain N requirement from Table 2 = (A) #/acre
B & C. Calculate available N in sludge as in items B and C
above (B) and (C) #/acre.
D. Residual sludge N in soil = (D) l/acre
If soil has received sludge in past three years, calculate
residual N from Table 1 as in item D above.
E. Sludge application rate, tons/acre
_ # crop N requirement - # N residual N (A) - (D) . ,
# available N in sludge (B) + (C)
Example calculation
From Table 2, N needed for 120-140 bushels of corn
= 170# N per acre = (A)
The remainder of the calculations are as shown previously.
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Z94
Table 1. Release of available N (per ton of solids) during
sludge decomposition. This table can be used to
calculate D in the formulas.
Years after
Sludge Mineralization % N in Sludge
Application Rate 2.0 2.5 3.0 3.5 4.0 4.5 5.0'
# of N available
1st
20
8
10
12
14
16
18
20
2nd
10
4
5
6
7
8
9
10
3rd
5
2
2.5
3.0
3.5
4
4.5
5
4 th
2.5
1
1.25
1.5
1.75
2.0
2.25
2
5th
1.25
0.5
0.62
0.75
0.87
1.0
1.12
1
Example — If you were calculating the amount of available N that
would be released from the organic N contained in the
sludge added in previous years (Residual N or D in the
formula) for the current year (C in the formula) this
table could be used.
Assume that 5 tons of sludge had been added each year
for 4 previous years and you want to know how much
residual N will be supplied on the 5th year by the pre-
vious sludge additions. If the sludge had 2.5% organic
N, then 0.62#, 1.25#, 2.5# and 5# would be supplied from
1 ton of sludge applied during the 4 previous years.
That would be a total of 9.37# of N per ton of sludge.
Since 5 tons of sludge were added each year, then
9.37 x 5 « 46.85# of N would be available during the
5th year from the previously applied sludge.
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295
TABLE 2 . Nitrogen Requirements for Colorado Crops (Pounds of tO
Crop
Typical Yields
Per Acre
Available
N (#)
lbs/Acre
Corn for grain
Corn for silage
Wheat (1)
Oats (1)
Barley (1)
120-140 bu
25-30 tons
60-80 bu irrigated
20-30 bu dry land
80-100 bu irrigated
30-40 bu dry land
80-100 bu irrigated
30-40 bu dry land
1,
7,
2,
1.
3/bu
5/ton
3/bu
1/bu
1.5/bu
170
200
160
60
100
40
140
50
Malting barley (1)
(irrigated)
Grain sorghum for grain
Grain sorghum for silage
Forage grasses
Potatoes
Sugar beets
Alfalfa (2)
Clovers (2)
Dry beans (2)
80-100 bu irrigated . 7/K
30-40 bu dry land
8000# 2/100 #
15-20 tons 7.5/ton
4-6 tons 40/ton
12-15 tons 10/ton
20-25 tons 6/ton
4-6 tons (2)
4-6 tons (2)
2000# (2)
120
45
160
130
200
140
140
200
200
200
(1) If the straw is removed
(2) Legumes can obtain most of their N from the air and are normally
not fertilized with N. However, if included in a crop rotation
with N using crops, they will use the available N in the soil
and will fix very little N from the air. Therefore, it can be
assumed that they will remove as much N as corn for grain in the
same rotation.
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296
Figure 1. Textural classification chart (U.'S. Department
of Agriculture) and comparison of particle size
scales.
Sand —2.0 to 0.03 mm. tfamttir
5ilt-r0.03 to 0.002 mm. diomotor
Cloy—imollof ttion 0.002 mm. tfiomator
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297
DRIED STABILIZED SLUDGE
USER PERMIT
1. Date:
2. Producer: Address:
3. Name of User:
4. Address of User:
5. Phone Number of User:
6. Location Where Sludge is to be Used:
7. Distance (feet, yards, miles) to nearest: (a) Stream ;
(b) Pond ; (c) Well ; other Water Supply,
(describe)
8. Amount of Sludge Desired (Dry Tons):
9. Actually Loaded (Dry Tons):
j.O. Number of Acres to Receive Sludge
11. Application rate (Dry Tons per Acre)
12. Describe Use(s) of Sludge (e.g. Soil Conditioning of Farmland, Garden,
Yard, Reclamation of Nutrient Deficient Land, Other:
13. Manner in Which Sludge is to be Applied:
14. Will Sludge be Stockpiled Before Application: Yes No (Circle One)
15. Estimated Length of Time Sludge is to be Stockpiled:
16. Type of Crops to be Grown on Sludge Conditioned Land:
The information set forth above is true and correct to the best of my
knowledge.
User's Signature Producer's Signature
Dept. Approval:
Representative's Signature
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2*8
LIQUID STABILIZED SLUDGE
USER PERMIT
1. Date: ;
2. Producer: Address:
3. Name of User:
4. Address of User:
5. Phone Number of User:
6. Location Where Sludge is to be Used:
7. Distance (feet, yards, miles) to nearest: (a) Stream
(b) Pond ; (c) Well ; (d) Other Water Supply,
(describe)
8. Amount of Sludge Desired (Dry Tons):
9. Actually Loaded (Dry Tons):
10. Number of Acres to Receive Sludge
11. Application Rate (Dry Tons per Acre '
12. Describe Use(s) of Sludge (e.g. Soil Conditioning of Farmland, Garden,
Yard, Reclamation of Nutrient Deficient Land, Other):
13. Manner in Which Sludge is to be Applied anchor Incorporated
14.
15.
16.
APPLICATION
(Check One)
Splash plate
Spray irrigation equipment
Other surface application
(Specify)
Direct injection of sludge
into the soil
INCORPORATION
(Check One)
Discing
Chisel Plowing
Mold Board Plowing
Rototilling
Yes
Will Sludge be Stored Before Application: No
Estimated Lenght of Time Sludge is to be Stored:
Types of Crops to be Grown on Sludge Conditioned Land:
The information set forth above is true and correct to the best of my
knowledge.
User's Signature Producer's Signature
Dept. Approval: ________
Representative's Signature
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299
PRODUCER DRIED STABILIZED SLUDGE
INFORMATION SHEET
1. Date:
2. Producer: Address:
3. Name of User:
4. Address of User:
5. Phone. Number of User:
G. Location Where Sludge is to be Used:
7. Distance (feet, yards, miles) to nearest: (a) Stream ;
(b) Pond ; (c) Well ; Other Water Supply,
(describe)
8. Amount of Sludge Desired (Dry Tons):
9. Actually Loaded (Dry Tons):
10. Number of Acres to Receive Sludge
11. Application rate (Dry Tons per Acre)
12. Pescnb'3 Use(s) of Sludge (e.g. Soil Conditioning of Farmland, Garden,
Yard, Reclamation of Nutrient Deficient Lar.u, Other:
13. Manner in Which Sludge is to be Applied :
14. Will Sludge be Stockpiled Before Application: Yes No (Circle One)
15. Estimated Length of Time Sludge is to be Stockpiled:
16. Type of Crops to be Grown on Sludge Conditioned Land:
The information set forth above is true and correct to the best of my
knowledge.
User's Signature Producer's Signature
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300
PRODUCER LIQUID STABILIZED SLUDGE
INFORMATION SHEET
1. Date:
2. Producer:
Address:
3. Ndme of User:
4. Address of User: .
5. Phone Number of User:
6. Location Where Sludge is to be Used:
7. Distances (feet, yards, miles) to nearest: (a) Stream
(b) Pond ; (c) Well ; (d) Other Water Supply,
(describe)
8. Amount of Sludge Desired (Dry Tons):
9. Actually Loaded (Dry Tons):
10. Number of Acres to Receive Sludge .
11. Application Rate (Dry Tons per Acre
12. Describe Use(s) of Sludge.- (e.g. Soil Conditioning of Farmland, Gatc'ion,
Yard, Reclamation of Nutrient Deficient Land, Other):
13. Manner in Which Sludge is to be Applied and/or Incorporated :
APPLICATION
(Check One)
INCOinv'i^ to:
(Chec-fv
(Specify)
Direct injection of sludge
into the soil
14. Will Sludge be Stored Before Application: No Yes
15. Estimated Lenght ol Time Sludge is to be Stored:
Splash plate
Spray irrigation equipment
Other surface application
Discing
Chir.ol i" i ov/> ¦
Mol <1 IV'M I I ! "l. I 1 "m
Rototi 1 L i r.'.i
Yes
16. Types of Crops to be Grown on Sludge Conditioned Land:
The information set forth above is true and correct to the beet of my
knowledge.
User's Signature
Producer ': • wnn tu
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UMVERSAL
SOIL LOSS
EQUATION
TECHNICAL NOTE 50
(REVISED JAN 1077)
COLORADO
SOIL CONSERVATION SERVICE
US DEPARTMENT OF AGRICULTURE
301
-------
TABLE OF CONTENTS
SECTION I Universal Soil-Loss Equation
SECTION II Procedure for Estimating Average Annual Soil Loss
Resulting from Water Erosion (Sheet and Rill)
SECTION III Predicting Soil Loss for Periods Less Than 12 Mon
SECTION IV . Soil Loss vs Sediment Yield
SECTION V Figures for Determining Erosion Factors
LIST OF FIGURES
FIGURE
1
Map of factor "R" for Colorado
FIGURE
2
Erosion Index Distribution Curves
FIGURE
3
Soil Nomograph
FIGURE
4
Value of Topographic Factor "LS"
FIGURE
5
Crop Management Factor "C" Eastern Colorado
FIGURE
6
Crop Management Factor "C" Western Colorado
FIGURE
7
Factor "C" for Pasture and Rangeland
FIGURE
8
Factor "C" for Various Quantities of Mulch
FIGURE
9
Factor "C" for Woodland
FIGURE
10
Factor "P" for Conservation Practices
302
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TECHNICAL NOTES
U.S. DEPARTMENT OF AGRICULTURE SOIL CONSERVATION SERVICE
AGRONOMY NOTE 450 (revised) .January, 1077
To: All Offices
From: Arnold D. King, Agronomist
UNIVERSAL SOIL-LOSS EQUATION
The Universal soil-loss equation is a means of estimating soil loss aru'.
evaluating conservation alternatives on a quantitative basis. It was
developed primarily for use in predicting sheet and rill ercsio- or r.or. -
irrigated croplands- It does not account for gulley erosion snd
not calculate sediment yield.
Recent developments, particularly in "C" factors has exp4nJ.? \ its use
to estimating soil loss on various types of project arc.\s.
SECTION I
The Universal Soil-Loss Equation
The soil-loss equation is
A = RKLSCP
Where A is the soix loss (Tons/Acre/Year)
R, rainfall factor
K, soil erodibility factor
L, length of slope)
) Combined into an LS factor
S, percent slope )
C, cropping management factor
?, erosion control practice factor
Each of the five factors mentioned above are multiplied tor,other to
the answer "A, Soil Loss" in terms of Tons/Acre/Year. Therefore, the
smaller the factors, the smaller the amount of soil loss from water erosion.
It must be recognized that the USLE is an empirical formula; based or.
research, experience and observation. Good judgement must b
-------
R (rainfall) factors are assigned by geographical regions based on
weather data furnished by the U. S. Weather Service. R values are
based on rainfall amount, time, and intensity. In the mountains,
R values were computed primarily for valley areas and have been
increased to account for run-off from snow melt.
An iso-erodent map, "R" factor map, has been developed for the
entire state. In the mountain regions it was necessary to general-
ize to a large extent because of the wide variation in rainfall
patterns. See figure 1.
The rainfall information has been plotted on curves for various
locations. This information can be used to predict erosion for
periods less than 12 months. See figure 2. This will be discussed
in more detail in the example section of this technical note.
K (soil erodibility) factors are assigned each soil series. Soil
Scientists have developed a listing of "K" factors for all soil series
being mapped in Colorado. The "K" factor will change for a given soil
series as different horizons are exposed by a land disturbing activity.
Therefore it was necessary to assign "K" factors for the various soil
horizons occuring in a soil series.
K values are determined by use of a nomograph. See figure 3. Refer
to "Erodibility and Loss Factors for Soils of Colorado" to determine
"K" factors for soils of Colorado. An SCS soil scientist should be
consulted for assistance, if additional "K" values are needed.
LS (length and percent slope) factors account for the length and per-
cent slope. These factors will be taken from Table
Length of slope begins at the top of the micro-watershed. This is
usually the top of a hill, ridge, terrace, or diversion. The length
of slope is considered to end for a given field at one of the following
places: (1) the point where the slope decreases to the extent that depos-
ition occurs (2) the point where runoff enters a well-defined channel,
gulley, terrace, or diversion or (3) where water leaves the field.
If terraces or diversions are used to achieve the proper LS factor for
the given situation, they must be constructed in accordance with appro-
priate engineering Sandard and Specifications.
Uniform slopes are ideal for use in the USLE, but are uncommon. Slopes
are usually convex (steepening substantially toward the lower end) or
concave (flattening toward the lower end).
When the lower end of the slope is steeper than the upper end (convex-
slope), the gradient of the steeper segment should be used with the over-
all slope length to enter the LS chart.
On a concave slope, deposition may occur at the lower end of the slope.
In such cases, the appropriate length and gradient are those of that
segment of the slope that is above the point where it flattens enough
for deposition to occur.
Page 2
304
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If the field is divided into segments according to degrees of erosion,
each segment must be treated separately as needed. If the field remains
as one segment, it must be treated to control the most severely eroding
areas.
C (cropping - management) factors are the ratios of soil losses from
lands cropped under specified conditions to the corresponding losses
from tilled, continuous fallow.
Cropland C values will be taken from Figure 5 or 6. Select the appro-
priate charts, then select the correct cropping sequence for the given
field. It will be necessary to exercise good judgement when selecting
C values. All crops are not listed, because many are similar. There
would be no appreciable difference between wheat and barley. Also,
there would be no appreciable difference between corn harvested <^s
silage and sorghum; planted in rows, harvested as bundles.
If additional C values are needed, notify the State Agronomist. He is
responsible for their computation.
"C" factors for land uses other than cropland are included en Ti,:ures
7, 8, and 9. The percent ground cover is the primary item to consider
because a slight change in percent ground cover will result in a sig-
nificant change in the erosion prediction.
Figure 8 was developed for use on critical areas and various land dis-
turbing projects. It should be recognized that straw mulch begins to
lose its effectiveness after a few months depending on moisture, temp-
erature, 3oils, etc.
? (erosion control practices) factors are support practices which slew
runoff water and thus reduce the amount of soil it can carry. The P
factor is the ratio of soil loss with the supporting practice to that
of soil loss with up-and-down-hill culture.
Read the appropriate P value for each field from figure 10. Values
are based on percent slope and method of farming.
Definitions:
(a) Contour stripcropping is alternate strips of a sod producing crop
and a cultivated crop. Strips of sod must be as wide as the strip
of cultivated crop.
(b) Cross slope farming with strips is similar to Item (a), above, but
is not on contour.
(c) Contour farming is tillage and planting on the contour, but; does
not necessarily involve strips.
(d) Cross slope farming without strips is simply farming a field cross
slope.
305
Par,« 3
-------
(e) Up and down hill farming is farming without regard to slope.
Figure 10 provides the values for factor P.
SECTIOK II
Procedure for Estimating Average Annual Soil Loss Resulting
From Water Erosion (Sheet and Rill)
R-rainfall factor: "R" values for each county are shown on the state map
TFigure 1). See Section III to determine "R" for only a portion of the year.
K-soil erodibility factor: "K" values for each soil are shown in the field
office Technical Guide, or may be included on a chart supplementing this
document.
L-slope length factor: Estimate slope length in the field. Slope length
Ts the distance from the point of origin of overland flow to the point where
(l) slope decreases to the extent that deposition begins or (2) runoff enters
a defined channel. If the field is terraced, L is the distance between terraces.
S-slope gradient factor:' Estimate percent of slope in the field.
LS-Rlope-Effect factor: Values for slope length and slope gradient are
combined into the Slope-Effect factor (LS). When slope length and gradient
have been determined, the LS value is found Figure 4.
C-cropping-management or plant cover factor: Figures 5 and 6 show cropping-
management "C" factors for various crops and tillage practices in rotation on
cropland. Yearly "C" values were combined to calculate "C" values for various
crop rotations. To determine factor "C" for land uses other than cropland,
refer to Figures 7, 8, and 9.
P_ - erosion control practice factor: Figure 10 shows values of P_for cross-
slope farming, contouring, and stripcropping. ~
Example Situation:
A farmer is growing winter Wheat at Craig, Colorado. He uses a wheat fallow
rotation, plows with moldboard in the fall and by planting time, no residue
remains on the soil surface. The soil map shows that the dominant soil in
the field Is Hesperus loam. Field examination shows the slope lertgth is
approximately U00 ft and the slope is approximately 6%. The farming operations
are generally up and down the slope. What is the predicted average annual soil
loss in tons per acre?
Solution:
Use the Universal Soil Loss Equation A * RKLSCF or Soil-Loss calculator.
Page 4
306
-------
Step 1
Determine "R" from Figure 1. R - 40
Step 2
Determine "K" from "Erodibility and Loss Factors for Soils of Colorado".
K = .28
Step 3
Determine the combined "LS" factor from Figure <*. LS = l.u
Step
Determine factor "C" from Figure 6 Wheat-Fallow, Fall plowinr, 1-0 lbs
residue/AC. C a ."+6
Step 5
Determine factor "P" from Figure 10. Up and down slope farmina
operations. P 8 1.0
Step 6
Multiply (R»40) x (K « .28) x (LS * l.H) x (C * .U6) x (P = 1.0)
The product of these factor values indicate that approximately 7.2 tons/
AC/Yr of erosion occurs on the field.
Planning Considerations;
The soil loss tolerance, T Factor, for Hesperus loam is 5 tons. The
predicted soil loss of 7.2 tons/Ac/Yr is excessive and in order to have
an adequate resource management system the predicted soil loss from wind
and water must be reduced to 5 tons/AC/Yr or less. Wind erosion is not
considered significant in this county so practices that will reduce
water erosion will be the primary concern.
Water erosion can be reduced by the following:•
1. Leaving additional crop residue
2. Changing the cropping system
3. Shorten the slope with diversions or terraces.
4. Install a strip cropping system
5. Perform contour farming in combination with terraces. S«e footnote
1/ Figure 10.
The most acceptable solution to the erosion hazard would probably be to
improve the residue management program. Far example, if the farmer would
agree to leave his crop residue standing through the winter, plow in the ,
spring leaving approximately SOS lbs of residue at planting time, his soil
loss would be reduced to 3 .7 totvs/Ac/Ysar,
307
Page 5
-------
SECTION III
Predicting Soil Loss for Periods Less Than 12 Months
The information in this section provides a procedure for predicting soil
loss for any period of time within a year. For example, project areas
may be bare for a short period of time and then be mulched or protected
by temporary seeding. To accomplish this it is necessary to determine
the percentage of factor "R" that will occur during a given time span
of the year. Figure 2 can be used to determine the adjusted factor "R".
Example Situation
A critical area treatment project is planned in Fremont county. The entire
drainage area of 30 acres will be shaped, mulched and seeded. Sediment
basins will be constructed to retain the predicted amount of sediment. The
structures will be designed to retain sediment for a two year period be-
ginning immediately after shaping. What is the predicted soil loss during
the two year period? Can we convert this to sediment yield?
Step 1
Determine values for R,K,LS, and P. R ~ 40, K = .34, LS = 6.0(50ft x 30^),
C (To be determined for each stage), P = 1,0
Step 2
Determine adjusted "R" values by use of E.I. distribution curves. See
Figure 2, then determine "CM values for each cover condition.
1st Stage - Bare soil, August 1st to November 1st.
R = 8.8 (10x22%) x K = .34 x LS = 6.0 x
C = 1.0 (bare ground) x P » 1.0 = 17.9 Tons/Ac
2nd Stage - Mulch and seed, November 1st to August 1st
R = 31.2 (40x78%) x K = .34 x LS = 6.0 x
C s .06 ( See Figure 8) x P « 1.0 = 3.8 Tons/Ac
3rd Stage - Growing grass, 2nd year, August 1st to August 1st
R = 40 (Full year) x K = .34 x LS = 6.0 x C • .07 (50% ground cover including
mulch) xP* 1.0 *5.7 tons/Ac
Step 3
The predicted soil loss for the first two years after construction is 822 tons
(27.4 x 30 Ac). This data is based on average climatic conditions, so the
engineer may want to apply a safety factor. A geologist or engineer can use
the predicted soil loss, determine a sediment delivery ratio and calculate the
amount of sediment the structure will need to retain. Refer to Section IV for
additional guidance.
Page 6
308
-------
SECTION IV
SOIL LOSS VS. SEDIMENT YIELD
Sediment yield is equivalent to the gross erosion minus what is
deposited enroute to a given point. Sediment yield estimates are
needed to evaluate sediment damage and to determine sediment design
requirements. The yield of a given area varies with the changing
patterns of precipitation, soil, cover, drainage patterns, topography,
and channel density.
A method of determining sediment yield has been used for many years by
the Soil Conservation Service. The estimate of sediment yield is made
by use of the following equation:
V = E(DR)
Where Y * sediment yield (tons/unit area/year)
E = gross erosion (ton/unit area/year)
DR = sediment delivery ratio (always less than 1)
Gross erosion can be estimated by use of the Universal Soil-Loss Equation.
The sediment delivery ratio should be determined by a sedimentation geol-
ogist or engineer. Many interrelationships of watershed characteristics
must be considered in order to determine accurate sediment delivery ratios.
309
-------
CO
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*•«•••••*«• «¦ I
FIGURE 1
-------
100
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LU
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S 40
IxJ
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Erosion Index Distribution Curve
for Computing Factor "R" for Less than 12 f'onths
FIGURE 2
1
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EASTERN -
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DATE
310
-------
CO
70
viry tin* |r«»ulir
i- ««# »r §*•»*¦!••
4*kluhy, •' •ollifi
/ .
.60
.90
~ SOIL STRUCTURE
20
30
70
>V
o
<40
,30
20 .70
Ui
.60
.10
,50
30
PERMEABILITY
* 6/
PERCENT SANO
(0.10*2. Omm)
80
20
90
c
6- »•'»
5* tlow
4- ilo« |« A|4.
3- mod«rol«
100
.20
WOttPMH: ulti 44U. **Uf 1C*1* it lift m prtctM to r«pr«i*ntt»»j
tM tall I I lt«4 (0.10-2.9 m), 1 orgtMC •itlu, structure, iig p*n*«btlttj. In tftil
I'Ul^UU kttatf* flottM c«r««|. T«t *)ttH ll«< IllwttriUl pr*c«4wrt for « tJll
Il, OH l.li, tirwctur* 2. »«r***fc11itjr *. I - 0.11
iu,
FIGURE 3 - SOIL NOMCCPAPH for
determining fa'-tor "k"
-------
FIGURE U
Values of the Topographic Factor "LS"
Length
of Percent Slope (S)
Slope
-------
FIGURE 5
CROP MANAGEMENT FACTOR »C" EASTERN COLORADO
Cropping Sequence
Management
Practice
"C" Tactor
Wheat, grain sorghua
1 fallow
Minimum tillage
Tallow operations (wheat)
Men* - summer I fall
1 or it - spring i summer
0-200 lbs sorghum residue
200-500 lbs sorghum residua
500-1,000 lbs sorghum residue
1,000-1,500 lbs sorghum residue
1,500-?,000 lbs sorghum residue
2,000-2,500 lbs sorghum residue
0.38
0.38
0.33
3.27
o.:t
0.?2
Wheat, fallow
corn (grain), fallow
Minimum tillage
Tallow operation!
None - summer & fail
) or » • sprinf. t summer
600-1,000 lbs wheat residue
500-1,000 lbs corn residue
o.j:
Wheat, corn (grain),
fallow
Minimum tillac.*
Tallow opera t ions (uhea-.l
Nona • summer & fall
1 or t - sprinf £ summer
500-1,000 lbs wheat residue
500-1,000 Ihs corn residue
1,000-1,500 lbs corn rrr.idue
1,500-2,000 llij corn residue
2,000-2,500 lbs corn residue
0.3U
0.28
0.2S
0.23
Com (grain) ( fallow Minimum tillage
Tallow operations
Nona • summer i rail
J or * - spring & summer
500-1,000 lbs residue 0.50
1,000-1,500 lbs rasidua O.uO
1,500-2,000 lbs residue 0.3H
2,000-2,500 lbs residue 0.31
Craln sorghum ( fallow Minimum til lair"
fallow operations
None - summer I fall
3 or M - spring I summer
0-200 lbs residua
0.61
300-500 lbs residue
0.51
$00-1,000 lbs residue
0.50
1,000-1,500 lbs residue
0.39
1,600-2,000 lbs residue
0.33
2,000-2,500 lbs residue
0.30
Continuous grain sorghua Minimum tllljga 0.«
-------
FIGURE 5 Cont'd
CROP MANAGEMENT FACTOR "C" EASTERN COLORADO
Cropping Sequence
Management
PractIce
"C" l"ecrr:
Wheat t fallow
Minimum tillar.e
fallow operations
1-summer I fall
3-ipring ( Sumner
500-1,000 lbs residue
1,000-1,S00 lbs residue
J,500-J,000 lbs residue
0.71
c.u
0.07
Vheat C fallow
Minimum tillaee
fallow operations
Nona - summer t fall
*-spring t summer
0-200 lbs residue
200-&00 lbs residue
S00-l,000 lbs residue
1.000-1,500 lbs residue
1,100-2,000 lbs residue
o.?.i
.in
c.;i
j. i"
o.ci
Mhsat t fallow
Minimum tillace
fallow proration*.
1-sumnor I fall
*-spring ( sunmer
0-200 lbs residue
200-&00 lbs residue
S00-1,000 lbs residua
1,000-1,100 lbs residue
l,SOO-2,O0O Ibt residua
O.uo
0.3^
0.2'
O.IS
0.0'j
Wheat t fallow
Conventional tillage
fallow operations
1-aummer TTaTT
•-spring t summer
0-200 lbs residua
20Q-S00 lbs residue
0.S7
0.«6
Wieat ( fallow
Conventional tlJian*.
fallow operations
1-aummer V fall
7-spring I summer
0-200 lbs residue
200-S00 lbs residue
o.ss
0.15
Vhexr I fallow
Conventional tillage
(HoldLoard t>lowin(P
fall plowing
O.SS
Vheat ( fallow
Conventional tlllate
(Holdtaard plowing!
Spring plowing
0.37
314
-------
FIGURE 6
CROP MANAGEMENT FACTOR "C" WESTERN COLORADO
Cropping Sequence
Manageoent
Praetle*
"C" Factor
Winter whaat ( fallow
first fallow operation
in fall of year
Wold board plow
Ha residue
Minimum tillage
0-200 lb* residue
200-500 lbs residue
500-1,000 lbs residue
1,000-1,500 lb* residue
1,500-2,000 lb* residue
0.H4
0.1*2
0.31
0.13
0.13
0.07
Winter wheat
Tallow
Winter wheat (froien out)
Spring whaat
Continuous
Winter aliMI
rirat fallow operation
in spring of year
Holdboard plow
Ho residue
Minimum tillage
0-200 lb* residue
200-500 lb* residue
500-1,000 lb* residue
1,000-1,500 lb* residue
1,500-2,000 lbs residue
Moldb^ard plow
No residue
Minimum tillage
0-200 lbs reiiiiue
>00-500 IBs residue
S00-1,000 lb* residue
1,000-1,500 lbs residua
1,500-2,000 lb* residue
0.17
3. 3 a
e.22
0.15
0.19
0.3«
0.3"
0.31
0.18
0.13
0.09
Continuous wheat Holdboard plow
-Winter wheat (frozen out) No residue 0.58
•Spring wheat
i Minimum tillage
0-200 lbs residue 0.5<
200-500 lbs re*idue 0.56
500-1,000 lbs residue 0.3*
1,000-1,SOC lbs residue 0.21
1,500-2,000 lbs residue 0.13
Winter wheat ( fallow rirst fallow operation
in spring of year
Holdboard plow
No residue 0.23
Minimum tillage
0-200 lbs residue 0.29
700-500 Ih* residue 0.2«
500-1,000 lb* residue 0.16
1,000-1,500 lbs residue 3.12
1,500-5,000 lb* residue 0.09
Continuous bean*
1 yr beana I 1 yr wheat 0.27
2 yrs bean* C 1 yr wheat 0.38
J yrs bean* t 1 yr wheat o.«J
* yr* bean* I 1 yr whaat o.U7
t yr* boons I 1 yr whaat a.n»
Alfalfa *0*4 production (Row*) r includes year of 0.21
establishment
I yr* alfalfa I grass - Includes year of estsblishment 0.73
(Pasture l Hayland)
1 yr fallow
2 yrs baana
Crete eeed (irixluctton (Now.) - includes y*«r of o.Il
•stall I eloiext
315
-------
FIGURE 7
"C" Factors for Permanent Pasture and Rangeland ]/
Vegetative Canopy
Cover That Contacts the Surface
of Raised Canopy ?/
Cover 3/
X "
Type £/
0
20
Percent Ground
40 60
Cover
ao
•5-lOfl
Column ho.:
z
3
4
5
0
7
8
9
No appreciable canopy
6
.45
.20
.10
.042
.013
.003
W
.45
.24
.15
.090
.043
.011
Canopy of tall ferts
25
6
.36
.17
.09
.038
.012
.003
or short brush
W
.36
.20
.13
.OR?
.041
.011
(0.5 m fall ht.)
50
G
.26
.13
.07
.035
.012
.GC3
H
.26
.16
.11
.075
.03?
.011
75
G
.17
.10
.Pfi
.031
.011
.003
W
.17
.12
.07
.067
.03w
.011
Appreciable brush
25
G
.40
.18
.09
.010
.0' *
.<*03
or brushes
W
.40
.22
.14
.085
'.Ci'z
on
(2 m fall ht.)
50
G
.34
.16
.036
.038
.v.?
.003
W
.34
.19
.13
.081
.011
75
G
.28
.14
AO
.036
.C'"!3
W
.2fl
.17
J2
.077
.0-10
on
Trees but no appre-
25
G
.42
.19
.10
.041
.013
.'•03
ciable low brush
H
.42
.23
.14
.087
.0
.011
(4 m fall ht.)
50
G
.39
.18
.09
.040
.on
.003
W
.39
.21
.U
.085
.04?
..on
75
G
.36
.17
.09
.039
.012
.003
W
.36
.20
.13
.083
.041
.011
\J All values shown assume: (1) random distribution of mulch or vegetation, and (.?) mulch
of appreciable death where it exists.
2/ Average fail height of wate'rdrops from canopy to soil surface: m » meters.
3/ i'ert'lon o- total-area surface that would be hidden from view by canopy in a vertical
~ projector-, (a bird's-eye view).
4/ C: Covpr at surface is grass, grassllke plants, decaying compacted duff, or litter.
W. Caver ?.? surf-ice is mer.'-y broadleaf herbaceous plants (as weeds with little lateral-
root M*iw.>rt! roar the surface, and/or urcir-cayed residue.)
FIGURE 8
Factor "C" for Various Quantities' of Mulch
Mulch - adequately crinped into soil
"C" Factor
barr areas
1/4 ton st
1,2 "
3/4 "
1 '
1-1/2 "
2 "
3 •
« •
aw mulch ner acre
1.0
.52
.35
.24
.18
.10
.06
.03
.02
316
-------
riGUKE 9
**C" fadtors for Woodland
v y y
rtrut
Tn* CMWfy litter "C"
% t( Mr** % ef Arc* Undergrowth Factor
1O0-75 100-90 Managed 4/ .001
Unmanaged 4/ .003-.011
70-40 05-75 Managed .022-.004
Onmanaged .01 -.04
35-M 70-40 Managed .003-. 009
Unstanaged 5/
2/ When tree canopy it lets than 20%, the area will be considered as
grassland, or cropland for estimating soil loss. See Table 1.
2/ rarest litter is assumed bo be at least two int;!.:s deep over the
percent ground surface area covered.
y Undergrowth is defined as shrubs* weeds, grasses, vines, etc., on
the surface area not protected by forest litter. Usually found under
eanspy openings.
A/ Managed - grazing and fires are controlled.
Onstanaged - stands that are overgrazed or subjected to repeated burn-
ing.
Jj/ Per unmanaged woodland with litter cover of less than 75%, C value*
should be derived by talcing 0.7 of the appropriate values in Table 5.
The factor of 0.7 adjusts for tho much higher soil organic matter on
permanent woodland.
name 10
"p" ractors tor conservation1 practices
Slepe
(Percent)
Op 4
Dm
Kill
Cress Slept
Pa rain*
Without Scrips
Contour
Farming
Cross Slope
Farming With
Scrips
Contour
Scrip
Croppinc
1.1- 7.9
1.0
0.75
0.50
0.37
0.25
7.1-12.0
1.0
0.80
0.60
0.45
0.30
u.i-ia.o
1.0
0.90
0.80
0.60
0.40
It.1-14.0
1.0
0.93
0.90
0.67
0.45
1/ Cwrteer limits - 2 percent t00 ft, B percent 200 ft, 10 percent
100 ft, lH-2t percent 60 ft.
317
-------
¦
¦^1
-------
This appendix contains selected copies of relevant
correspondence pertaining to Metro's attempts to obtain
land in the Rocky Mountain arsenal for the Drying and
Distribution Center.
319
-------
March 22, 1971
Lt. Colonel Harold W. Shear
Conmanding officer
Rocky Mountain Arsenal
Denver# Colorado 80240
Dear Colonel Shears
Approval is requested for the Metropolitan Denver Sewage Dis-
posal Distr5.ct Mo. 1 to utilize a portion df Rocky Mountain
Arsenal property for the application of dowatered sewage sludge
to the soil. The proposed project can provide multiple benefits#
These benefits include improvement of specific soils for vege-
tation, providing of a better location for periodic diav>oaal o£
sewage sludge from the Metropolitan Denver Sewage Disposal Dis-
trict No. 1 treatment facilities, and research information which
hopefully can encourage beneficial application of sewage sludge
to the soil throughout the United States.
Enclosed are letters from the Colorado Water Pollution Control
Division and the Air Pollution Control Division of::the Colorado
Department of Public Health and the Tri-County Diotrict Health
Department indicating support of the proposed project on a trial
basis for a period of approximately eight weeks. Other letters
from the Adams County Commissioners and other governmental agencies
supporting this proposed use of Rocky Mountain Arsenal property will
be submitted when they are received. Verbal approval to this trial
basis project has been given by the Adcma County Commissioners. If
tho oludgo application project proves aatiofactory to all concerned
parties, the Metropolitan Denver Sowage Disposal District: No. 1
would wish to continue the project until come other method of re-
cycling oludge to the soil would be developed and adoptod. Other
such methods are now under study by the Metro District staff.
Also enclosed are small maps which indicate the area in tho south-
west corner of Section 20 within th-a Rocky Mountain Arsenal pro-
perty on which tho District would px'opoae to perform this oludgo
320
-------
it, colonel Harold Shear
pago Two
March 22, 1971
application to the coil*
Use by the Metropolitan Denver Sewage Disposal District No. 1 of
the proposed Rocky Mountain Arsenal site for the application of
dewatered sludge to the soil would provide significant financial
savings to the District* It is proposed that the trial demonstra-
tion project be performed on the basis of applying sludge 24 hours
por day for a period of approximately two weeks, followed by a
four week pariod of no sludge application, then followed by another
two vcck period of sludge application at the Arsenal site* After
tha second period of r.ludcjo application it would be appropriate for
all concerned parties to decido whether they would favor continuation
of the established procedure of application or would favor a revised
procedure throughout the future. I should mention that Mr. Donnelly,
Director of Facilities at the Rocky Mountain Arsenal, is familiar
with the proposed methods to be employed.
It in presently the intention of the Board of Directors of the
Metropolitan Denver Scv/age Disposal District No. 1 to eliminate
incineration of sewage sludge end to contract for application of
liquid sludge to tho soil at one or more sites throughout cistern
Colorado, This now system of liquid sludge application would hope-
fully commence by March or April of 1972.
The sludge application project at the Rocky Mountain Arsenal would
be comparable to that which has been in process at the Lowry Bomb-
ing Range for the past year. Trucks with sealed boxes would haul
dewatered sludge (approximately 16% solids content) to the Rocky
Mountain Arsenal site and unload the sludge into agricultural
manuro spreaders. Th® manure nprcrde.rrj pulled by a 70 H.P. agri-
cultural tractor would distribute the sludge over a 10 to 12 feet
wido path at a rate of application of approximately 10 dry tons
por aero. It ia anticipated that three applications would be
attempted totalling 30 dry tons por acre* This is a relatively
low application rate for sewage sludge. Following each application
a rotary hoe will bo used to pulverize a thin layer of soil and
mix it with the sludge. This operation will not. harm the ekisting
vegotivo cover* but will provide soil conditioning and fertilizer
benefits' to the soil.
Experience with the Lowry operation has indicated no problems with
tho transportation of tho sludge or with any odor, water pollution
or air pollution problems at the sludge application site.
321
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jt, cclonel Harold Shear
pnc;o Throo
March 22, 1971
Inasmuch as the need for financial savings to the District ia
immediate and the time during which dewatered sludge will be
available is limited, it is requested that a decision on this
request bo provided at an early date. Your favorable considera-
tion of this request will be most helpful to the people of the
metropolitan Denver urea and will be most sincerely appreciated
by the Board of Directors of the Metropolitan Denver Sewage Dis-
posal District No. 1,
Yours very truly,
William X. Korbitz, P#E.
Manager
WEK/d
CC - Ed C. Hoskinson
Enclosures
322
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DEPARTMENT OF THE ARMY
HEADQUARTCI
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September 11# 1974
The Honorable Howard Callaway
Secretary of the Army
Tho Pentagon ,
V?ashingcon, D. C. 20025
Dear Mr. Secretary:
It is respectfully requested that approximately 2,000
acres of land in the northeast corner of the Rocky
Mountain Arsenal be furnished to tho Metropolitan Denver
Sewage Disposal District No. 1 for an organic solids
processing facility for the metropolitan Denver area.
The aubject land includes parts of Sections 19, 20, 29,
30 and 32 in Range 66 V7est, Township 2 South.
The activity intended by the District, to commence in
mid 1976 to late 1976, includes air drying of sludge in
large drying basins totalling about 300 acres, the nub-
cur face injection of sludge on several hundred acres, and
extensive research plots as well as a landscaped' buffer
jsone around the periphery of tho property. The sludge
•will be biologically stabilised, so there would be no ob-
noxious odors, fly or rodent problems. Many decades of
experience with this type of sludge has indicated that
there is no need to fear problems from heavy metals, bac-
teria, viruses or other health or environmental hazards.
The plan of the District for beneficial ranee of organic
solids {ncwage sludge) includes anaerobic digoutlon of
the sludge at a central treatment plant located in Cotr.rr.erco
City# tho piping of the sludge of attprorciir.ntoly 4% solids
content to the processing sito, and at tho processing site
providing air dryir:^ of: sn-.c of the nluugo, subc»ur£*>co
injecting of noma of the sludge, and using tho balance
of the sludge in continuing research efforts of tho Di«-
tr.ict. At seme later date, scne of tho Kludge wr»y be
pulverised, palletized, stockpiled, mucked and ;;old.
325
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2
This is an excellent opportunity' for the Department of the
Array to participate in a significant environmental and
energy conservation activity which could provide significant
national as well as regional benefits, I sincerely hope
that this request will receive your most serious consideration.
Additional information including maps will be provided to
the appropriate personnel of the Department of the Army at
such time as such personnel find need for such additional
information.
Respectfully,
William 13. Korbitz, P.E.
Manager
ccs Mary B o'Dell
Y7EK/j
326
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HEADQUARTERS UNITED STATES ARMY MATERIEL COMMAND
S001 EISENHOWER AVE., ALEXANDRIA, VA, 22304
DEPARTMENT OF THE ARMY
26 September 1974
Mr* William E. Korbitz, Manager
Metropolitan Denver Sewage Disposal
District No* 1
3100 East 60th Avenue
Commerce City, Colorado 80022
Dear Mr. Korbitz:
The Secretary of the Army has asked me to reply to your inquiry
in which you requested that the Army furnish approximately
2000 acres of Rocky Mountain Arsenal land, to the Metropolitan
Denver Sewage Disposal District No* 1, for use in your proposed
sludge disposal project*
The Department of Defense Explosive Safety Board has consistently
disapproved the release of any land at Rocky Mountain Arsenal until
the current demilitarization program is completed. This is now
scheduled for late in 1976.
In view of the current situation surrounding Rocky Mountain Arsenal,
it is suggested that the Denver Sewage Disposal District explore
alternate solutions and notjplan on using Arsenal land* However,
if no other solution can be found, your request will be reexamined
a year from now.
I regret that the circumstances in this instance preclude a more
favorable reply.
Sincerely,
NEii/'s * Godwin
Acting Special Assistant
for Congressional Affairs
327
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September 11, 1974
The Honorable Howard Callaway
Secretary of the Array
The Pentagon t
Washington, d. C. 20025
Dear Mr. Secretary:
It io respectfully requested that approximately 2,000
acres of land in the northeast corner of the Rocky
Mountain Arsenal be furnished to the Metropolitan Denver
Sewage Disposal District no. 1 for an organic solids
processing facility for the metropolitan Denver area.
The subject land includes parts of Sections 19, 20, 29,
30 and 32 in Range 66 VJest, Township 2 South*.
The activity intended by the District, to commence in .
mid 1976 to late 1976, includes air drying of sludge in
large drying basins totalling about 300 acres, the sub-
surface injection of sludge on several hundred acres, and
extensive research plots as v;ell as a landscaped1 buffer
Rone around the periphery of the property. The sludge
trill be bioD.ogically stabilised, so there would be no ob-
noxious odors, fly or rodent problems. Many decades of
experience with this type of sludge has indicated that
there is no need to fear problems from heavy mefcalc, bac-
teria, viruses or other health or environmental hazards.
The plan of the District for beneficial ranr.o of organic
solids (i;ewage sludge) includes anaerobic digestion of
the sludge at a central treatment plant located in Commerce
City, the piping of the sludge of approximately >1% solids
content to the proccjuing site, and at the processing site
providing air drying of sc^.e of the alvtd^o, subsurface
injecting of soma of the sludge, end using the balance
of the sludge in continuing research efforts of tho Di«-
trict. At some later date, acne of two nludye may be
pulverized, pcllctixcd, stockpiled, mucked and
328
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2
The Metro Denver Sewage Disposal District is dedicated to the
beneficial use of sewage sludge with savings in commercial
fertilizer and energy. The continued use of the Lowry Bombing
Range where the Metro District presently recycles its sludge
will probably result in retardation of growth and also limits
the beneficial use of the sludge to some 1,500 acres of land
and only one cattleman rather than to many thousands of acres
of land and scores of farmers and other users.
At your earliest opportunity I would appreciate learning of
any plans for disposal of portions of the Rocky Mountain Arse-
nal land, also information concerning what is needed by you
for a decision on this Metro Denver District request as well
as other pertinent information. I sincerely hope that the De-
partment of the Amy will be able to participate in this valu-
able program of providing increased food production, alleviating
the present critical fertiliser shortage in the United States,
relieving the critical energy shortage problem, and providing
general improvement to the environment.
Respectfully,
William E. Korbi^tz^P.E.
Manager
cc: Senator Floyd Haskell
Senator Gary Hart
Congressman William Armstrong
Congresswpman Patricia Schroeder
Congressman Timothy Wirth
Mary B. O'Dell
Robert C. McWhinnie
WEK/j
329
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January 23, 1976
The Honorable Richard D. Lamm
Governor of Colorado
State Capitol Building
Denver, Colorado 80203
Dear Governor Larams
Enclosed is a copy of a letter addressed to the Secretary of
the Army concerning the use of Rocky Mountain Arsenal land
by the Metropolitan Denver Sewage Disposal District Nos 1.
Subsequent to sending the letter to Secretary Hoffman, I
learned that you had established a committee concerning
arsenal land use, and I would like to have the request of
the Metro Denver Sewage District considered in connection
with future Rocky Mountain Arsenal land use.
Xn the event that the Metro Denver Sewage Disposal District
officials and personnel can be of help in connection with
Rocky Mountain Arsenal land use planning, please eo advise
roe.
Respectfully*
William
Manager
Enc.
WEK/blm
330
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DEPARTMENT Or THE ARIf*
orrice
-------
PRCIS-MR
DEPARTMENT OF THE ARMY Development & Readiness Cnid
HEADQUARTERS UNITED STATES ARMY MATERIELVONWIXNli
6001 EISENHOWER AVE., ALEXANDRIA, VA. XX3M 22333
1 1 FED '1976
Mr. William E* Korbitz, Manager
Metropolitan Denver Sewage Disposal
District No. 1
3X00 East 60th Avenue
Commerce City) Colorado 80022
Dear Mr. Korbitz:
The Secretary of the Amy has asked me to reply to your inquiry
wherein you requested the Army to provide 2000 acres of the
Rocky Mountain Arsenal to the Metropolitan Denver Sewage Disposal
District No* 1 for sludge disposal*
In our letter to you on 26 September 1974 we explained that the
Department of Defense Explosive Safety Board has consistently
opposed the release of any land at the arsenal until the demilitarization
program is completed* This program has now been rescheduled for
completion during fiscal year 1977*
As long as this demilitarization program continues, all the land
comprising the arsenal must remain under the control of the Department
of the Army and none can be made available at this time*
I regret that a more favorable response could not be made to your
request; however, I trust you will understand our position*
Sincerely,
Special Assistant for
Congressional Affairs
332
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fllm
flkn
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This appendix contains the proposal by the U.S.G.S.
to install and maintain monitoring wells and lysimeters
at Site B~2 to detect possible groundwater contamination
beneath the site.
334
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PROJECT PROPOSAL
WATER RESOURCES INVESTIGATION
SLUDGE DRYING SITE
ADAMS COUNTY
COLORADO
by
S. G. ROBSON
MARCH 1977
335
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INTRODUCTION
The Metropolitan Denver Sewage Disposal District No, 1 (MI)SDD) plans
to replace the current sewage sludge land disposal area cast of
Denver, Colorado, with sludge drying basins to facilitate sludge
disposal and allow use of dried sludge as fertilizer. It is planned
that about 600 acres of drying basins will be contained in the 2,000-
acrc site which is located about 25 miles northeast of Denver. About
100 dry tons of sludge per day will be pumped through slurry pipelines
to the drying basins. The MDSDI), the Environmental Protection Agency,
and local residents are concerned over the effects the estimated 22
acre-feet per year of drying basin leachate could,have on local
ground-water quality.
PROBLEM
Although about 20 unused or domestic wells are thought to be located
within a 3-mile radius of the drying basin site, no well data are
available to determine the lateral extent or depth of alluvial and
bedrock aquifers in the area. The native ground-water chemical quality
and direction of movement are also ill defined. In addition, no on-site
data are available to determine the volume or chemical quality of sludge
leachate that will percolate from the basins. As a result, the effects
of the drying basins on local ground-water quality "cannot be accurately
determined from existing data. The distribution of existing wells is
such that it will not be possible to monitor the ground-water quality
near the site without additional wells.
PROPOSAL
It is proposed that a ground-water quality monitoring program be
established within a 28-square-milo area around the drying site.
Objective; The purpose of the water-quality monitoring program would be
to gather data describing the location, depth, and extent of permeable
and impermeable materials beneath the drying site, depth to ground
water, chemical quality of ground water and leachate, and the rate of
leachate movement into the unsaturated zone. These data would allow a
determination of the depth and lateral extent of alluvial and bedrock
aquifers at the drying site. The direction of movement and chemical
quality of the native ground water would also be defined, an will the
volume of leachate movement into the unsaturated zone and the chemical
quality of the leachate. This information would allow an assessment
of the probable long-term effects of the drying basins on the local
ground-water quality and should have transfer value to similar installa-
tions in other areas. Continued monitoring of ground-water quality
in the study area will provide information about the current effects
of lcnchntc movement on local ground-water quality.
Approach! The 28 nqunre-mile utudy area, centered around the drying
ban"in"site, is located in an area of rolling hills and shallow valleys.
336
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337
Bedrock consisting of mudstonc and sandstone of the Denver Formation
occurs beneath a shallow veneer of alluvium on the hills, and is
overlain by as much as 40 feet of alluvium in the valleys. Ground
water Is thoucht to occur at depths of about 200 feet in the bedrock
and at shallow depths in the larger alluvial valleys. No natural
ground water is thought to occur in the alluvium under the drying
basin site although leachate may ultimately form a saturated zone in
this area. Stream channels are normally dry and only carry flow
following heavy precipitation.
It Is proposed that about 40 wells be drilled aud cased for ground-
water quality monitoring near the site. Twenty-nine on-site wells
and 5 off-site wells will be drilled and cased to enable sampling of
any water in saturated permeable zones in the alluvial materials.
Six sites will be drilled for installation of multiple piezometers
in any permeable zones found in the upper 100-200 feet of the bedrock
formation. In addition, it is planned that six pan-type lysimeters
will be installed under selected drying b.asins in order to determine
the rate of leachate movement and obtain leachate samples for chemical
analysis. Eight domestic wells and 12 unused wells are thought to
be located within a 3-mile radius of the drying basins. It is planned
that as many as possible of these wells will be sampled for water-
quality analysis. It will be necessary to get the property owners
permission to renovate the existing unused wells before they can be
sampled.
If the ground-water quality is degraded by' basin leachate, the zone
of degraded water will originate near the basins and slowly spread
to more distant locations. As a result, water-quality samples from
locations near the drying basins will be gathered at more frequent
intervals than will samples from more distant locations. The lysimeters
under the drying basins will probably be sampled on a monthly basis
with wells near the drying basins sampled on a quarterly basis. The
off-site wells to be drilled and the existing domestic and unused
wells will be sampled on an annual basis. This sampling schedule
will be intensified if changes in ground-water quality are thought
to warrant cither more frequent sampling or the installation of
additional observation wells. If insufficient water for chemical
analysis accumulates in the lysimeters during the one-month sampling
interval, the sampling frequency may be reduced in order to obtain
an adequate volume of sample.
Tho samples obtained during the first 1 to 2 years of monitoring
will be analyzed for all major anions and cations, selected inorganic
nutrlentn, heavy metals, dissolved solids, and dissolved organic
carbon. Once baseline concentrations have been established for native
ground water and leachate, the lint of dofcernitnud constituents will
be reduced to eliminate repratcd ana.lyein of constituents not found
to be useful indicators of water-quality degradation.
2
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338
The majority of the vatcr-qunliLy analyses will be performed in the
MDSDD Laboratory, with supplemental and check analyses on split
samples analyzed in the USCS Laboratory. The analytical techniques
used by the USCS Laboratory have produced analytical results which in
the past have been comparable to the results obtained from the MDSDD
laboratory.
Cost and Timing; It is proposed that the. Initial phase of the ground-
water monitoring near the drying site be undertaken over a 3-year
period.
First Year (1977 FY)
Canvas, measure, and sample, if possible, all existing wells in the
study area. Construct potentiomctric contour maps for the bedrock and
alluvial aquifers to aid in selection of site and depth of subsequent
observation wells. The 1977 fiscal year funding required is $13,060,
of which the USGS and MDSDD will contribute equal shares of $6,530.
The MDSDD funding will include $3,000 worth of•laboratory services for
which they will receive direct credit.
Second Year (1978 FY)
The primary expense during the second year of the study results
from the installation of new wells and lysimeters, renovation of
existing unused wells and the analysis of water-quality samples. It
is estimated that the 1978 FY funding required will be $75,750.
MDSDD and USGS shares would be $37,875 with MDSDD receiving direct
credit for. $15,000 worth of laboratory services.
Third Year (1979 FY)
Work undertaken in the third year of the study involves water-quality
sampling and analysis and preparation of a report documenting the
findings of the first three years' work. Funding for the third and
subsequent years of water-quality monitoring is difficult to estimate
at this time for the number of dry wells in the monitoring network cannot
be readily estimated. Current estimates indicate that $42,330 of funding
will be required with MDSDD and USCS contributions of $21,165. MDSDD
will receive direct credit for $15,000 worth of. laboratory services.
Report Format;
It Is anticipated that the final report will bo published as part of
the USGS Water-Resources Investigation series. The report should
contain about 10 illustrations and 100 pages including an appendix of
data collected during the study. The content: and format of the report
should bo very similar to the report "Ground-water quality near a acwnp.e-
uludge voc.yc.li.iu', site and a landfill near Denver, Colo." prepared in
cooperation with the MDSDD in 1976.
3
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 2
EPA-908/5-78-001B
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Final EIS- Volume II
Metro Denver Sludge Management Plan
8. REPORT DATE
February 1978
8. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO ADDRESS
Engineering-Science, Inc.
600 Bancroft Way
Berkeley, California 94710
10. PROGRAM ELEMENT NO.
1 f. WlMYhACTAiRANT 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
16. SUPPLEMENTARY NOTES
Volume II of III Volumes; Volume I:EIS; Volume II:Issues and Resolution; Volume III:
abstract jummary
This volume concerning the Metro Denver Sludge Management Plan presents
written responses to the draft EIS, a "discussion of the principal Issues and
problems with the project, and their resolution.
Written responses received on the draft EIS and at the public hearings
held 1n conjunction with the review of the draft EIS are presented. Specific
EPA responses are provided alongside the comments.
Thirty-one principal issues are Identified and discussed. These Issues
are broken down into five areas: pipeline and central plant Issues, drying site
Issues, present operations, alternatives and sludge use Issues. Each of these
are discussed 1n turn, with detailed Information provided where needed. Issues
are presented 1n a consluslve manner; I.e., they are either judged Important,
unimportant, or 1n need of further study. Appendix A contains a proposed 11st
of grant conditions for successive phases of work on the Metro Denver sludge
plan, based on the Issues discussions. Appendix B contains the proposed
State of Colorado guidelines for agricultural applications of sludge.
17. KEY WORDS ANO DOCUMENT ANALY8I8
a- DESCRIPTORS
b. 1DENTIF1ERS/OPEN ENDED TERMS
c, COS ATI Field/Group
sludge; sol Idsi sem1-ar1d; drted sludge;
solids recycling; groundwater Impacts;
basin lining; EIS; final EIS
Denver; Colorado; 201;
facilities plan;
18. DISTRIBUTION statement
unlimited
io. H6u*ity iukti (fUr Jt«pW
unclassified
31. n6. of
353
30. SECURITY CLA8* (TMt pagej
23. PRICE
CPA Farm 2230-1 (»•*. 4-77) previous Coition is ouoliti
339
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