HomeMy WebLinkAbout970563.tiffRESOLUTION
RE: ACTION OF BOARD OF COUNTY COMMISSIONERS OF WELD COUNTY,
COLORADO, CONCERNING SITE APPLICATION OF CITY OF EVANS, COLORADO,
AND AUTHORIZE CHAIR TO SIGN
WHEREAS, the Board of County Commissioners of Weld County, Colorado, pursuant to
Colorado statute and the Weld County Home Rule Charter, is vested with the authority of
administering the affairs of Weld County, Colorado, and
WHEREAS, the Board has received a site application from the City of Evans, Colorado,
3700 Golden Street, Evans, Colorado 80620, concerning re -rating the hydraulic capacity from
0.9 million gallons per day to 1.2 million gallons per day for an existing water treatment facility
located on the following described parcel of land, to -wit:
SE1/4 SE1/4 of Section 20, Township 5 North, Range 65
West of the 6th P.M., Weld County, Colorado
WHEREAS, the regulations for site applications for re -rating an existing wastewater
treatment facility require review of the site application by the Board of County Commissioners,
and further, that various local and state agencies be given the opportunity to review and
comment on said revised site application, and
WHEREAS, the site application from the City of Evans, Colorado, was submitted to the
Board of County Commissioners of Weld County for review and comment, a copy of said
application being attached hereto and incorporated herein by reference, and
WHEREAS, after study and review, the Board finds that said site application is
compatible with the Weld County Comprehensive Plan, and that it is in the best interest of Weld
County to recommend approval of said application.
NOW, THEREFORE, BE IT RESOLVED by the Board of County Commissioners of
Weld County, Colorado, that the site application submitted by the City of Evans, Colorado, be,
and hereby is, recommended favorably to the Colorado Department of Health, Water Quality
Control Commission, as being compatible with the Weld County Comprehensive Plan.
BE IT FURTHER RESOLVED by the Board that the Chair be, and hereby is, authorized
to sign said site application.
6-c /21 eva.t4
970563
PL0079
SITE APPLICATION - CITY OF EVANS, COLORADO
PAGE 2
The above and foregoing Resolution was, on motion duly made and seconded, adopted
by the following vote on the 26th day of March, A.D., 1997.
Dale K. Hall
eputy Clerk the Board
APPRO D AS Ts.a'RM:
BOARD OF COUNTY COMMISSIONERS
WELCyCOUNTY, COLORADO
Georg
E. Baxter, Chair
tance L. Harbert, P;o-Te
/
7, 4 s!)l u_
Barbara J. Kirkmeyer
W. H. Webster
970563
PL0079
' COLORADO DEPARTMENT OF HEALTH
Water Quality Control Division
'210 East 11th Avenue
enver, Colorado 80220
APPLICATION FOR SITE APPROVAL FOR CONSTRUCTION OR EXPANSION OF:
A) DOMESTIC WASTEWATER TREATMENT WORKS (INCLUDING TREATMENT PLANTS,
OUTFALL SEWERS, AND LIFT STATIONS) OVER 2,000 GPD CAPACITY.
B) INTERCEPTORS (IF REQUIRED BY C.R.S. 25-8-702 (3))
APPLICANT: City of Evans, Colorado - Evans U1112
ADDRESS: 3700 Golden Street. Fvanc4 Colorado
Consulting Engineer's Name and Address: HDR Engineering, Inc., 303 E. 17th Avenue, Suite 300
Denver, CO 80203
A. Summary of information regarding new sewage treatment plant:
1. Proposed Location: (Legal Description) SE 1/4,
Township 5N
PHONE: (970) 339-5344
PHONE:(303) 764-1520
SE 1/4, Section
, Range 65W
Weld County.
2. Type and capacity of treatment facility proposed: Processes Used
Aerated Lagoons, Chlorination, Dechlorination
Hydraulic 1,200,000 Organic 2,772
gal/day
Present PE 10,396
3. Location of facility:
Attach a map of the area which includes the following:
(a) 5 —mile radius: all sewage treatment plants, lift stations, and domestic
water supply intakes. See Attachment A
habitable buildings, location of potable water wells, and
an approximate indication of the topography. See Attachments MC
Surface discharge to watercourse See:Attachment D
Land
Other
lbs. BOD5/day
Domestic 99+
(b) 1 -mile radius:
4. Effluent disposal:
Subsurface disposal
Evaporation
I5.
20
% Industrial -1
Design PE 13,360
State water quality classification of receiving watercourse(s) See Attachment D
Proposed see`Ittntacihmenfl a Uons developed in conjunction with Planning
imitt
Section, WQCD: BOD4 mg/1 SS
mg/1 Fecal Coliform
Total Residual Chlorine mg/1 Ammonia
mg/1 Other
Will a State or Federal grant be sought to finance any portion of this project? NO
6. Present zoning of site area? Single Family Residental
and Standards
/100 ml
7. What is the distance downstream from the discharge to the nearest domestic water
supply intake? No intakes downstream in Colorado
(Name of Supply)
Zoning with a 1 -mile radius of site? See Attachment D
(Address of Supply)
What is the distance downstream from the discharge to -the nearest other point of
diversion? Patterson Ditch, approximately one mile
(Name of User)
(See Attachment A)
(Address of User)
WQCD-3 (Revised 8-83)
970563
8. Who has the responsibility for operating the proposed facility? City of
Evans, Colorado
9. Who owns the land upon which the facility will be constructed?
Evans, Colorado
(Please attach copies of the document creating authority in the applicant to
construct the proposed facility at this site.)
10. Estimated project cost: $15,000
fity of
Who is financially responsible for the construction and operation of the facility?
City of Evans, Colorado
11. Names and addresses of all water and/or sanitation districts within 5 miles
downstream of proposed wastewater treatment facility site.
City of Greeley, 1000 10th Street, Greeley, CO 30631
(WPCP actually discharges to Cach La Poudre River lust upstream of the
South Platte).
(Attach a separate sheet of paper if necessary.)
12. Is the facility in a 100 year flood plain
If so, what precautions are being taken?
no precautions taken.
or other natural hazard area? No
Located in 500 year flood plain,
Has the flood plain been designated by the Colorado Water Conservation Board,
Department of Natural Resources or other Agency? FEMA
(Agency Name)
If so, what is that designation? Zone R
13. Please include all additional factors that might help the Water Quality Control
Division make an informed decision on your application for site approval.
See attached Engineering Design Report
B. Information regarding lift stations: N/A
1. The proposed lift station when fully developed will generate the following additional
load: Peak Hydraulic (MGD) P.E. to be served
2. Is the site located in a 100 year flood plain?
If yes, on a separate sheet of paper describe the protective measures to be taken.
3. Describe emergency system in case of station and/or power failure.
4. Name and address of facility providing treatment:
5. The proposed lift station when fully developed will increase the loading of the
treatment plant to _
(Treatment Agency)
% of hydraulic and % of organic capacity and
agrees to treat this wastewater? Yes No
Signature and Title
WQCD-3 (Revised 8-83)
970563
C. If the facility will be located on or adjacent to a site that is owned or managed by a
Federal or State agency, send the agency a copy of this application.
'D. Recommendation of governmental authorities:
Please address the following issues in your recommendation decision. Are the proposed
facilities consistent with the comprehensive plan and any other plans for the area,
including the 201 Facility Plan or 208 Water Quality Management Plan, as they affect water
quality? If you have any further comments or questions, please call 320-8333, Extension
5272.
1.
2.
3.
pate
Recommend
Approval
See Below
5. ladea
6.
7.
Recommend No
Disapproval Comment Signature of Representative
Managemency
t (City of Fvans)
Local Government: Cities or Towns (If
site is inside boundary or within three
mil s) and/ Sanit tion Districts.
/Boar of County ommissionlersounty)
oca
C ty o
th Author(held Co. HPalth)
g"L'4JS
p.
ty nn ng ut or ty
cppj
Council of Governments/Regio al Planning
Not Required
State Geologist
(For lift stations, the signature of the State Geologist is not required. Applications for
treatment plants require all signatures.)
I certify that I am familiar with the requirements of the "Regulations for Site Applications
For Domestic Wastewater Treatment Works," and have posted the site in accordance with the
regulations. An engineering report, as described by the regulations, has been prepared and is
enclosed.
2.a
2.b
2.c
DATE //ZWg7
Applicant Earl Smith
ignature of
TYPED NAME
Recommend Recommend No
Date Approval Disapproval Comment Signature of Representative
Greeley
La Salle
Hill -N -Park Sanitation District
—3—
WQCD-3 (Revised 8-83)
970563
If the facility will be located on or adjacent to a site that is owned or managed by a
Federal or State agency, send the agency a copy of this application.
J. Recommendation of governmental authorities:
Please address the following issues in your recommendation decision. Are the proposed
facilities consistent with the comprehensive plan and any other plans for the area,
including the 201 Facility Plan or 208 Water Quality Management Plan, as they affect water
quality? If you have any further comments or questions, please call 320-8333, Extension
5272.
ate
1.
2.
Recommend Recommend No
Approval Disapproval Comment
Signature of Representative
See Below
3. a.-14 7. �
2747
5.
6.
Boa
Management ency
Local Government: t es or owns
site is inside boundary or within three
mi -s) anSanitation Districts.
4+ J- .
Comm ss oners
o Count
ea t Aut or ty
ty /County ann ng
7.
Counci o overnments
Not Re uired
State Geo og st
(For lift stations, the signature of the State Geologist
treatment plants require all signatures.)
I certify that I am familiar with the requirements of the "Regulations
For Domestic Wastewater Treatment Works," and have posted the site in
regulations. An engineering report, as described by the regulations,
enclosed.
DATE
Signature of Applicant
Recommend Recommend No
Date 4p royal Disapproval
Comment Si
2.a
2.b
2.c
is not required.
uthor3ty
egional' g ann ng
Applications for
for Site Applications
accordance with the
has been prepared and is
- F- 1 Rmith
TYPED NAME
nature of Representative
Greeley
La Salle
Hill -N -Park Sanitation District
WQCD-3 (Revised 8-83)
970563
ATTACHMENT TO SITE APPLICATION
accordance with C.R.S. 1981, 25-8-702 (2)(a), (b), and (c), and the "Regulations for Site
,,plications for Domestic Wastewater Treatment Works", the Water Quality Control Division mu,
determine that each site location is consistent with the longrange, comprehensive planning fc
the area in which it is to be located, that the plant on the proposed site will be managed to
minimize the potential adverse impacts on water quality, and must encourage the consolidation
of wastewater treatment works whenever feasible.
In making this determination, the Division requires each applicant for a site approval for a
domestic wastewater treatment works to supply an engineering report describing the project one
showing the applicant's capabilities to manage and operate the faility over the life of the
project to determine the potential adverse impacts on water quality. The report shall be
considered the culmination of the planning process and as a minimum shall address the
following:
Service area definition including existing population and population projections,
flow/loading projections, and relationship to other water and wastewater treatment plants
in the area.
Proposed effluent limitations as developed in coordination with the Planning and StandaIdE
Section of the Division. (Allow minimum four weeks processing time.)
Analysis of existing facilities including performance of those facilities.
Analysis of treatment alternatives considered.
Flood plain and natural hazard analysis.
Detailed description of selected alternatives including legal description of the site,
treatment system description, design capacities, and operational staffing needs.
Legal arrangements showing control of site for the project life.
Institutional arrangements such as contract and/or covenant terms for all users which will
be finalized to accomplished acceptable waste treatment.
Management capabilities for controlling the wastewater throughout and treatment within the
capacity limitations of the proposed treatment works, i.e., user contracts, operating
agreements, pretreatment requirements.
Financial system which has been developed to provide for necessary capital and continued
operation, maintenance, and replacement through the life of the project. This would
include, for example, anticipated fee structure.
Implementation plan and schedule including estimated construction time and estimated
start—up date.
Depending on the proposed project, some of the above items may not be applicable to address.
In such cases, simply indicate on the application form the non applicability of those.
-4—
WQCD-3 (Revised 8-83)
970563
DATE: March 26, 1997
NAME: City of Evans, Colorado
ADDRESS: 3700 Golden Street, Evans, CO 80620
REQUEST: Site Application for expansion of the Evans wastewater treatment plant
LEGAL DESCRIPTION: Part of the SE4SE4 of Section 20, T5N, R65W of the 6th P.M., Weld
County, Colorado
LOCATION: North of 37th Street and west of First Avenue in the City of Evans
THE DEPARTMENT OF PLANNING SERVICES' STAFF RECOMMENDS THAT THIS REQUEST BE
APPROVED FOR THE FOLLOWING REASONS:
1. Improvements to the treatment facility will not adversely affect the local water quality. The design
of the system will be of sufficient capacity to serve the approved service area.
2. The Weld County Health Department has reviewed this proposal and recommends approval of the
proposed expansion. North Front Range Water Quality Planning Association Board reviewed the
site application request and recommends approval to the State.
3. The Evans Planning Commission voted to approve the proposed expansion at its February 25, 1997
meeting.
4. The request complies with the Weld County Comprehensive Plan. The request proposes
improvements to an existing sewage treatment facility which services the incorporated municipality
of Evans.
The Department of Planning Services requests that the site application be approved by the Board subject to
the following condition:
Prior to construction occurring within any right-of-way in the unincorporated area of the county, the
applicant shall obtain an underground utility permit from the Weld County Public Works Department.
970563
mEmORAnDU
EliDe.
COLORADO
Gloria Dunn, Current Planner February 21, 1997
To
From
Subject:
Date
Don Carroll, Project Administrator 05.
Lease Water Treatment Plant Site Application by the City
of Evans, HDR
I have reviewed the application of the proposed Waste Water Treatment Plant expansion. In the
submitted Exhibit A, the City of Evans has indicated a five mile radius, which would include their
sewer district boundaries. Any work done within the five mile radius in Weld County's jurisdiction
would require an underground utility permit. This permit should be required prior to any
construction done within the right-of-way.
cc: Commissioner Harbert
plant
112 Dept
970563
The City of
March 12, 1997
Ms. Gloria Dunn
Weld County Planning Commission
1400 N. 17th Avenue
Greeley, Co 80631
Re: Evans Wastewater Treatment Plant; Site Application
Dear Gloria:
Per our conversation, enclosed is an Application for Site Approval for Construction or
Expansion of the Evans Wastewater Treatment Plant, signed by the Chairman of the
Evans Planning and Zoning Commission. Also enclosed is a certified copy of the
minutes for the Evans Planning and Zoning Commission meeting of February 25, where
the Commission reviewed and approved the application.
As you may know, the site application is to re -rate the existing plant from 0.9 MGD to
1.2 MGD through generally small additional upgrades and plant investment. The size
of the plant will not be increased, but existing operations will be enhanced to increase
efficiency.
If you have any questions, or wish to discuss this further, please call me at 339-5344.
Sincerely,
ecid
Earl H. Smith, P.E.
Director of Public Works
City of Evans
enc.
pc: Mike Smith, City Manager
Cr! 'nit/ Planning Dept.
MAR 1 7 1997
3700 Golden Street • Evans, Colorado 80620;2724 • (970) 339-5344 • FAX: (970) 330-34722 0563
Minutes
Planning & Zoning Commission
February 25, 1997
7:00 p.m.
I. CALL TO ORDER
The February 25, 1997 meeting of the Planning & Zoning Commission was called to order
at 7:05 p.m. by Chairperson Weisberg.
II. ROLL CALL
Commission Present:
Chairperson Weisberg
Vice Chairperson Grossnickle
David James
Pam Johns
Absent: Charles Riesselmann
Council Member Tiffany
Staff Present:
Earl Smith, Director of Public Works.
Tom Hamblen, Chief Building Official
Elizabeth Relford, Planner
Brenda Gutierrez, Community Development Secretary
III. APPROVAL OF MINUTES OF FEBRUARY 11, 1997 REGULAR MEETING
Commissioner Johns made motion seconded by Commissioner James to approve the minutes
of the February 11, 1997 regular meeting. Motion passed with all voting in favor thereof
IV. AGENDA ADDITIONS
There were no agenda additions.
V. AGENDA ITEMS
Agenda Item A - Public Hearing -SUB 9-1996 Preliminary Plan-Faules Valley Subdivision
Chairperson Weisberg opened the Public Hearing.
Chairperson Weisberg asked to hear a report from staff.
It was noted that the name of the subdivision has been changed from Nagel to Faules Valley
Subdivision. Dennis & Connie Nagel, along with their contractor Larry Andrews, requests
to subdivide the southwest corner of 37th St. and 17th Ave. into 13 conforming duplex lots.
970563
Planning & Zoning Commission Minutes
February 25, 1997
Page 2
Staff recommended that the Public Hearing be continued due to possible discrepancies found
with the original Valley View Subdivision Plat. Developer's have requested that Agenda
Items A & B be continued to a later date because there was surveying difference of 20 feet
discovered between Lifestyle Homes Plat (the adjacent development to the west) and Faules
Valley Plat. The land is being re -surveyed. Dennis Nagel asked the commission if the Public
Hearing had to be published a second time. The Commission stated that it would not have
to be published if this hearing was continued and not closed.
Chairperson Weisberg asked if there was anyone present who would like to speak in favor or
in opposition to this subdivision. There was no response from the audience.
Commissioner Johns moved to continue the Public Hearing for the Faules Valley Preliminary
Plat to March 11, 1997. Commissioner James seconded the motion. Motion passed with all
voting in favor thereof
Agenda Item B - Public Meeting -SUB 9-1996 Final Plat Review-Faules Valley Subdivision
The Public Meeting for the Final Plat Review of the Faules Valley Subdivision has been
moved to March 11, 1997, due to the continuation of the Public Hearing for the preliminary
plat review.
Agenda Item C - Rules of Procedure
A revised copy of the Rules of Procedure for Planning and Zoning Commission have been
provided to the Commission. The last time these rules were reviewed by the Commission was
July 9, 1996. Chairperson Weisberg noted that Section 8 (a) referred to the Evans City Hall
and asked if it should read the Evans City Complex. It was determined that this issue could
be dealt with when the rules will be under review next February when the new facility is ready
to occupy. Commissioner James recommended approval of the Rules of Procedure.
Commissioner Grossnickle seconded the motion. Motion passed with all voting in favor
thereof.
Agenda Item D - Election of Officers
Commissioner Johns made a motion nominating Harold Weisberg as the Chairperson of the
P & Z Commission. Vice -Chairperson Grossnickle seconded the motion. Motion passed with
all voting in favor thereof
Commissioner Johns made a motion nominating Debbie Grossnickle as the Vice -Chairperson
of the P & Z Commission. Commissioner James seconded the motion. Motion passed with
all voting in favor thereof
970563
Planning and Zoning Commission Minutes
February 25, 1997
Page 3
Agenda Item E - Waste Water Treatment Site Application
The Colorado Department of Public Health and Environment requires a re -rating of
wastewater treatment plants with a capacity over 2,000 gallons per day. Our current capacity
is 0.9 million gallons per day. The new rating would increase the hydraulic capacity to 1.2
million gallons per day. The Department of Health has stated that if a plant reaches 85%
capacity, the plant needs to divert the flow to reach full capacity. When a plant reaches 95%
capacity, a plant would have to be expanded to meet the growing needs of the City. By re -
rating the capacity, the current plant would meet the needs of the City for approximately 10
years.
The City's Consultants, HDR Engineering, Inc., prepared a site application requesting the re -
rating of 1.2 million gallons per day. Only minor additions to the aeration equipment and
conversion of the rock filter to a polishing pond are anticipated to meet the new design
capacity. Otherwise, the existing influent pump station, aerated lagoon system, chlorination
and dechlorination will remain in its current state.
As part of the application process, the City was required to notify several parties which might
be affected by the re -rating system. The Town of LaSalle, Hill -n -Park Sanitation District,
Weld County Board of Commissioners, City of Greeley, Weld County Board of Health and
Weld County Planning Commission are entities within the 3 mile radius that this re -rating may
have potential impact on receiving water from the South Platte River. Hill -n -Park Sanitation
District was the only entity to respond.
The Commission questioned why this issue has been brought before the P & Z Commission.
The State requires that this process be reviewed by several different Boards and Commissions
including the Evans Planning & Zoning Commission. Since the capacity will be increased by
25%, the plant will be able to meet the future growth needs of the residents of Evans. Also,
public utility facilities, such as police and fire stations, lagoons, etc., are legal conforming uses
in the R-1 Zone. Commissioner James moved to approve the wastewater treatment plant site
application as presented. Commissioner Johns seconded the motion. Motion passed with all
voting in favor thereof.
VI. AUDIENCE PARTICIPATION
There was no audience participation.
970563
Planning & Zoning Commission Minutes
February 25, 1997
Page 4
General Discussion Item A - Evans Business Park Annexation
The Council has approved Resolution 4-1997 in regard to the possible annexation of the
Evans Business Park to be located at the Northeast corner of 37th St. & 35th Ave. Evans
does not have water lines in that area so the City could negotiate with Greeley or Central
Weld County Water District for water service of the new development. Traffic would be
discussed when the site is further along with development.
A Public Hearing for the annexation has been scheduled before the City Council on April 1,
1997. It was noted that the wording of the plat should be changed to read that the Planning
and Zoning Commission has reviewed the plat instead of approved the plat.
VIII. ADJOURNMENT
The February 11, 1997 meeting of the Planning & Zoning Commission was adjourned at 8:30
p.m. by Chairperson Weisberg.
CITY OF EVANS
PLANNING & ZONING COMMISSION
I Harold Weisberg, Chairperson
ATTEST:
Kim Betz, City Clerk
970563
January 21, 1997
Weld County Planning Commission
1400 N. 17th Avenue
Greeley, CO 80631
Re: Evans Wastewater Treatment Plant
City of Evans, Colorado
Site Application
HDR Project No. 06923-006-050
To Whom It May Concern:
fill
Enclosed is a copy of the Site Application prepared for the planned re -rating of the Evans
Wastewater Treatment Plant (WWTP). The Site Application process is required by the Colorado
Department of Public Health and Environment (CDPHE) for re -rating wastewater treatment works
over 2,000 gallons per day.
The City of Evans' response is required as part of the Local Govetnment (within three miles of the
plant) review. As shown on page three of the Site Application, response can be provided in one of
three ways: recommended approval, recommended disapproval, or no comment. You have 60 days,
per CDPHE policy to respond. If no response is forthcoming after 60 days it is assumed there is no
objection. However, for the process to proceed in a timely manner we would appreciate a response
as soon as possible.
The Evans WWTP is currently rated at 0.9 million gallons per day (mgd) capacity. Recently
completed construction improvements included new aeration units in the first ce!I of the aerated
lagoon system. In addition, a new electrical system was added for all aeration units.
The Site Application is to re -rate the facility to 1.2 mgd. Only minor additions to the aeration
equipment and conversion of the rock filter to a polishing pond are anticipated to meet the new
design capacity. Otherwise the existing influent pump station, aerated lagoon system, chlorination
and dechlorination will remain in its current state.
If you have questions, please call me or Mr. Earl Smith, City of Evans, Director of Public Works at
(970) 339-5344 at your convenience. Thank you in advance for your timely review.
Very truly yours,
HDR ENGINEERING, INC.
Kevin J. Meador, P.E.
Project Manager
Enclosure: Site Application
HDR Engineering, Inc.
Employee -owned
, p:\evansmp\siteapp\Itrmrg.doc 1/20/97
Suite 300
303 East 17th Avenue
Denver, CO
80203-1256
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Telephone
303 764-1520
Fax
303 860-7139
970563
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a Salle
City of Evans
Wastewater Treatment Plant
Site Application
Five —Mile Radius Map
County
Municipal Algae rt
S•
Scout
Island
aston-Val ey View
4irport
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2/96
Attachment
A
970563 - -
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14690
465/,
City
SCALE 1.24 000
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1 MILL
City of Evans
Wastewater Treatment Plant
Site Application
One —Mile Radius Mop
4630
Date
2/96
Attachment
97(1563
ATTACHMENTS TO SITE APPLICATION
ATTACHMENT C
WELL SUMMARY FOR ONE -MILE RADIUS MAP
Map
Well
No.
1
2
Permit
Well
No.
19503F
87460
128949
3553F
5 44370
6 16991MH
7 20007MH
25574MH
70254
10 25549MH
13 5999R
14 14852
15 40122F
16 40123F
17 40124F
18 40125F
19 40126F
20 40127F
21 40128F
22 40129F
23 40130E
24 40131F
25 40132F
26 40133F
27 188581
28 194053
29 194054
11 3206AD
12 2433
30 40993
31 47421F
32 47420F
33 47422F
34 47423F
35 47424F
36 29533MH
Owner
Industrial Acres
McDoy Distributing Company
C.C. Clark
Shupe Brothers
Julia Meyers
Norwest Publishing
R.R. Donnelley Norwest, Inc.
R.R. Donnelley Norwest, Inc.
Fred Franklin
R.R. Donnelley Norwest, Inc.
Sussex Partners
W.C. Newport
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
Norwest Publishing Company
R.R. Donnelley Norwest, Inc.
R.R. Donnelley Norwest, Inc.
R.R. Donnelley Norwest, Inc.
Angel Padilla
-- -----------.-----
Douglas Stevenson
Piert P. & Florence Waddell
State Farm Mutual Automobile Insurance
State Farm Mutual Automobile Insurance
State Farm Mutual Automobile Insurance
State Farm Mutual Automobile Insurance
----- --------
State Farm Mutual Automobile Insurance
State Farm Mutual Automobile Insurance
Use
Crop Irrigation
Domestic
Domestic
Commercial
Domestic
Other
Monitoring Hole/Well
Monitoring Hole/Well
Household Use Only
Monitoring Hole/Well
Crop Irrigation
Domestic
Other
Other
Other
Other
Other
Other
Other
Other
Other
Other
Other
Other
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Other
Domestic
--- -------- ------------
Domestic
Other
Other
Other
Other
Other
Monitoring Hole/Well
970563
37 900
38 14592
43 90300
44 41128
41 90300
42 20196MH
39 15194F
40 128534
45 26149
46 48184
47 60135
48 170076
49 181736
50 181737
51 181738
52 181739
53 181740
54 182303
55 181741
56 181742
57 181743
58 44808F
59 44806F
60 44810F
61 44809F
62 44807F
63 145323
64 11981AD
65 1561
66 59056
67 62233 •
68 145323
69 148827
70 55244
71 21360MH
72 157753
73 26935F
74 39226
75 133451
76 16067R
77 9989
78 9989
79 160051
Rapps Enterprises
Rudy Marich
J.E. Brown
Wilber & Hattie J. Borchert
James Brown
Mineral Resources, Inc.
Royal B Associates
C.L. Knox
Herman A. & Marian Strasser
J.W. Clark
Carl D. Pinkstaff
Warren Henning
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Rothman Oil Company
Jean M. Brown
Patrick Mikes
Roscoe Miller
John E. & Virgie F. Crisp
James J. Rewents
Jean M. Brown
Edward A. & Ruth Brewer
J.D. Cook
Southland Corporation
Robert Quick
Jose D. Trujillo
Mary Luark
Jose D. Trujillo
Allie E. Miller
Allie E. Miller
Allie E. Miller
Gene Doty
Domestic
Domestic
Domestic
Domestic
Domestic
Other
Commercial
Domestic
Domestic
Domestic
Domestic
Livestock
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Monitoring Hole/Well
Other
Other
Other
Other
Other
Domestic
Crop Irrigation
Domestic
Domestic
Domestic
Domestic
Other
Domestic
Monitoring Well/Well
Domestic
Crop Irrigation
Domestic
Domestic
Crop Irrigation
Domestic
Domestic
Domestic
970563
80 91141VE Gene Doty
81 13250R Ethel O. & Winton Clark
82 6170R Hazel L. Zupke
83 1638 John Bragg
84 3935 John Bragg
85 14302R John W. Bragg
86 36748 Nelson Jay, Jr.
87 13601R Celeste W. & Walter Rumney
88 13602R Roy L. Schmidt
89 8183 Joseph P. Doll
90 19224 Ernest Wiltfang
91 1537R Drusilla & Eugene Gibbs
92 90524VE Samuel Holzmeister
93 138213 Samuel Holzmeister
94 138213 Samuel Holzmeister
95 158924 Samuel Holzmeister
96 6860R Arthur L. Pirnie
97 95388VE Elsro, Inc.
98 149306 Elsro, Inc.
99 573AD Lory F. Ferguson, Jr.
100 1335R Thomas Dorough
101 29936 Thomas Dorough
102 41127 Donald O. & Clara B. Norris
103 59057 John E. & Virgie F. Crisp
104 149306 Elsro, Inc.
105 26823 Johnny Laws
106 148828 Walter Latos
107 23693 John Kline
108 74543 Delia Aim Gibson
109 82309 Delia Ann n Gibson
110 141639 Mary I. Keefer
111 19299MH Southland Corporation
112 6300 Roy E. Johnson
113 82420 Arthur C. Roberts
114 82421 Arthur C. Roberts
115 82422 Arthur C. Roberts
116 28551 James R. Fugate
117 40126 Joe H. Mathis
_ _- - — -- ..__ ------ - -- ---- --------_.-...----
118 41197 Curtis W Nickols
119 84897 Thelma Leadabrand
120 182390 Murray Becker
121 27843 Ina Miner
Domestic/Livestock
Crop Irrigation
Crop Irrigation
Livestock
Domestic
Crop Irrigation
Domestic
Crop Irrigation
Crop Irrigation
Domestic
Domestic
Crop Irrigation
Domestic
Domestic
Domestic
Domestic
Crop Irrigation
Commercial
Commercial
...._..-_..-..
Crop Irrigation
Crop Irrigation
Domestic
Domestic
Domestic
Commercial
Domestic
Crop Irrigation
Domestic
Domestic
Domestic
Other
Monitoring Hole/Well
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
Domestic
970563
ATTACHMENTS TO SITE APPLICATION
ATTACHMENT D
EFFLUENT DISPOSAL, ZONING AND LOCAL SANITATION DISTRICTS
Effluent disposal: Surface discharge to watercourse Segment 2, South Platte River
Subsurface Disposal Not Applicable Land Not Applicable
Evaporation Not Applicable Other Not Applicable
State water quality classification of receiving watercourse(s) Class 2 Warm Water Aquatic Life.
Class 2 Recreation
Proposed Effluent Limitations developed in conjunction with Planning and Standards Section,
WQCD: BOD; 30 mg/L (30 -day average), 45 mg/L (7-dav average)
TSS 75 mg/L (30 -day average), 110 mg/L (7 -day average)
Fecal Coliform 2000 No./100 ml (30-dav ave), 4000 No./100 ml (7 -day ave)
Total Residual Chlorine 0.21 mg/L (30-dav average), 0.37 mg/L (daily maximum)
Ammonia None
Other Biomonitoring
Zoning with a 1 -mile radius of site Business, Single Family Residential, Manufacturing Single
Family Residential, Intermediate Residential, Medium Manufacturing, Mobile Home
Community, Planned Unit Development, Multi -Family Residential, Residential, Agricultural,
Industrial
970563
ATTACHMENTS TO SITE APPLICATION
ATTACHMENT E
ENGINEERING REPORT
Introduction
The Evans aerated lagoon wastewater treatment plant (WWTP) has been owned and operated
successfully by the City of Evans since 1985 and prior to 1985 it was owned and operated by the
Evans Sanitation District. The current design capacity of the plant is 0.9 mgd. The
Water/WastewaterMasterplan completed by HDR in March of 1996 recommended the City apply
to the Colorado Department of Public Health and Environment (CDPHE) to re -rate the plant to a
higher design capacity.
The mode for plant re -rating is the CDPHE Site Application process. The engineering report
presents the minimum criteria for the Site Application process in the order listed on the Site
Application as well as other pertinent information. The plant analysis portion of the report
identifies recommended improvements necessary to meet the new design flow and loading capacity
rating requested by the Site Application.
Additional WWTP improvements were recommended in the Masterplan including:
• Construction of a new influent pump station and screening facilities.
• Installation of a backup generator.
• Construction of a new laboratory.
• Modifications to the outfall pipeline.
These improvements will be completed in two to three years but will not effect plant capacity or
change the process. Therefore they are not be included as part of this Site Application but as
applicable will be documented via the Site Application Amendment process at the pertinent time.
The Water/Wastewater Masterplan includes relevant information to the Site Application.
Applicable sections of the Masterplan are included in the Appendix from which information will be
referenced and summarized.
Service area definition including existing population and population projections, flow/loading
projections, and relationship to other water and wastewater treatment plants in the area.
A description of the service area is presented in the Masterplan Technical Memorandum (TM) No.
1 which is included in the Appendix. The service area and urban growth area (UGA) boundaries
are shown in Figure 1-1 of TM No. 1.
Existing and projected populations are developed in Section 3.1 of TM No. 2 and summarized
below.
970563
Existing City of Evans Population = 6,817
Existing City of Evans plus UGA Population = 9,562
Projected 2005 City of Evans Population = 9,093
Projected 2005 City of Evans plus UGA Population = 12,438
Projected City of Evans Ultimate Population = 9,968
Projected City of Evans and UGA Ultimate Population = 36,504
TM No. 9 presents current and predicated wastewater flows for the different basins in the UGA.
Several scenarios of treatment are available for the Evans UGA and are discussed in TM No. 11.
They include treating wastewater at the Hill -N -Park WWTP, the Evans WWTP, the Greeley
WWTP, and combinations thereof. The recommendation in the immediate Evans area for the next
10 years is to provide treatment at the Evans WWTP. As population west of Evans more fully
develops, interceptors will reach into this area substantially increasing the flows to the Evans plant.
At that time or once the re -rated capacity is reached an expansion to the Evans plant or another
alternative of providing wastewater treatment will be required. See TM No. 10 for Wastewater
System Collection evaluation and recommendations. For this Site Application and plant re -rating,
only areas immediately around Evans will be served with the flows summarized below.
Average Day Flow, mgd
Maximum Month, mgd
Peak Hour (influent), mgd
Peak Hour (effluent), mgd
Current
0.77
0.87
Re -rated 2005
0.96 1.10
1.20 1.38
2.40 2.75
1.44 1.65
The current flows are based on 1996 flows through October. The average day 2005 flow is based
on the Masterplan value. The maximum month value for Re -rated and 2005 is found by using a
factor of 1.25 which is the average maximum month to average day ratio over the last six years.
The peak hour influent flow is found by using a peaking factor of 2.5 applied to the average day
value (no peak hour historical data is available). Similarly, the effluent peak hour factor is found by
using a factor of 1.5 applied to the average day value.
TM No. 11 of the Masterplan indicates prior to 1995 that influent five-day biochemical oxygen
demand (BOD5) averaged about 177 mg/L. Since then the plant staff has been running composite
samples but has been using incorrect sampling procedures resulting in erroneously high BOD5
loading values. Recent correction procedures have resulted in average influent BOD5 values of a
little over 200 mg/L. The influent flow and loading criteria in the Evan's permit results in a BOD5
limit of 277 mg/L. The plant evaluation will use the 277 mg/L value for design at average day and
maximum month flows.
Attachment B to the Site Application shows the other wastewater treatment facilities in the area and
include: Greeley, Hill -N -Park and La Salle.
970563
Proposed effluent limitations as developed in coordination with the Planning and Standards
Section of the Division.
The existing Evans WWTP Discharge Permit was issued in August of 1994. The permit will expire
September 30, 1999. The effluent limitations indicated in the permit are summarized below:
Parameter Limit
Flow, mgd
BOD5, mg/L
TSS, mg/L
Fecal Coliform, No./100 ml
Total Residual Chlorine, mg/L
pH, su (minimum -maximum)
Oil and Grease, mg/L
Total Ammonia, mg/L
0.9 (30 day average)
30/45 (30 day average/7 day average)
75/110 (30 day average/7 day average)
2000/4000 (30 day average/7 day average)
0.21/0.37 (30 day average/Daily maximum)
6.5-9.0 (Daily maximum)
10 (Daily maximum)
Report
In addition to the effluent limitations listed above, the facility must achieve 85 percent BOD5
removal on an average monthly basis.
The City of Evans obtained South Platte River pH, temperature and ammonia data for CDPHE to
evaluate potential future requirements for ammonia removal. CDPHE used this data to run the
Colorado Ammonia Model. The model determines, by month, the maximum allowable ammonia
concentrations permitted in the plant effluent such that there would be no significant detrimental
impact on the receiving stream. The model was run for plant flows of 1.2 and 1.4 mgd. The lowest
ammonia concentration limit was 52.2 mg/L at 1.4 mgd in the month of September. The model
results prompted CDPHE to state there would be no ammonia limitations required if the City
expanded to either 1.2 or 1.4 mgd. The letter from CDPHE documenting this conclusion and the
summary of data and chronic effluent total ammonia limits is included in the Appendix.
The ammonia limitation was the only known potential change to the City's existing permit, other
than biomonitoring. Biomonitoring is normally required for plants with design flows over 1.0 mgd.
Analysis of existing facilities including performance of those facilities.
TM No. 11 of the Masterplan evaluates the WWTP at 0.9 mgd design capacity. Since the
Masterplan was completed, the City has replaced the aerators in Cell No. 1 with 10-10 Hp
aspirating units. The flow direction capabilities of the aspirators promote a plug flow situation
reducing the possibilities of short circuiting. Cell No. 2 now has three aerators. The new aeration
units and the existing units are fed by a new electrical system. The plant layout including these
modifications is shown in Figure 1 and a process schematic is shown in Figure 2.
Plant influent flow and BOD5 loadings for the period from January 1993 through October 1996 are
shown in Figures 3 and 4 (as noted previously, improper testing of BOD5 composite samples has
970563
N
NO SCALE
VALVE NO. 1
VALVE NO. 2
VALVE NO. 4
INFLUENT LIFT
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VALVE NO. 5
CHLORINATION BUILDING
CHLORINE CONTACT
CHAMBER
FLOW MONITORING
BUILDING AND
DECHLORINATION
BUILDING
City of Evans, Colorado
Water/Wastewater Master Plan
EXISTING CITY OF EVANS
WWTP SITE PLAN
Figure 1 970544
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Water/Wastewater Master Plan
CHLORINE CONTACT CHAMBER
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970563
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970563
occurred recently and have just been corrected). Plant effluent BOD5 and TSS concentrations for
the same period are shown in Figures 5 and 6. As indicated in Figure 5, the permit limit for effluent
BOD5 was exceeded in January and February of 1996. This was caused by mechanical problems
with the aeration units and subsequent icing over. There were similar effluent violations in 1994
and 1995 which were also caused by mechanical problems. These problems occurred prior to
installation of the new aeration units and electrical system.
The plant analysis for the Site Application design flow is presented in Table 1 and 2. Table 1
presents a step by step review of facility capacities, etc.. Table 2 presents aeration requirements for
summer and winter time conditions. The one item which does not meet design criteria is the
available aeration capacity. The influent meter is rated slightly below the peak hourly design flow,
however it is not critical to get peak hourly flows, only maximum day flows are required. A new
meter will be installed with the new pump station with adequate range. The chlorine contact basin
has a detention time of twenty-nine minutes at peak hour effluent flows. Design criteria would
suggest a thirty minute detention time. Even though slightly below the thirty minute detention
time, it is recommended that the existing basin is adequate.
The summer time conditions prove to be the worse case scenario for aeration requirements. Table 2
indicates two aspirators and two aerators would be required to meet the summer time demand with
one aerator as backup. Depending on whether Cell No. 2 is discharging to Cell No. 3 or the
Chlorine Contact Chamber, the aerator nearest the relevant discharge would be shut-off.
An item not presented in the tables is the conversion of the rock filter to a polishing pond. The rock
filter has presented operational problems and is rarely used. A polishing pond would be of more
use to the operators even though the cell has a detention time less than the two days recommended
by the state.
A look at the overall aerated lagoon system indicates a total detention time of 23.1 days based on
average day flow and 18.5 days based on maximum month. CDPHE criteria suggest a detention
time of 12-30 days. The Evans lagoon cells have a depth of six feet which is less than the CDPHE
suggestion of 8 to 20 feet.
The only recommended improvements to re -rate the Evans WWTP are to increase the aeration
capacity and convert the rock filter to a polishing pond.
Other improvements presented in the Masterplan to be completed at a later date include: new
influent pumping and screening, a new lab, a new generator, and outfall improvements to allow
continuous effluent discharge through the normal outfall.
Analysis of treatment alternatives considered
The re -rating of the Evans WWTP involves using the established aerated lagoon process. The only
modification will be turning the rock filter basin into a polishing pond with no aeration. New
970563
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Table 1
EVANS WWTP
SITE APPLICATION
WASTEWATER TREATMENT PLANT ANALYSIS
TREATMENT PLANT DESIGN DATA
1. Average day design flow
2. Maximum month design flow
3. Peak flow (effluent), mgd
4. Peak flow (influent), mgd
5. Design influent BOD5 concentration
6. Design influent BOD5 loading
INFLUENT PUMP STATION
1. Influent Gravity Pipe, 24 -inch
Influent Pumping Capacity, min. firm capacity, 2000 gpm
Original design was based on 47 ft TDH at 2230 gpm.
3. Influent Metering Capacity, 1600 gpm
4. Influent Force Main, 10 -inch
AERATED LAGOON INFORMATION
1. Cell No. 1 Detention Time
2. Cell No. 2 Detention Time
0.96 mgd
1.20 mgd
1.44 mgd
2.40 mgd
277 mg/L
2772 ppd
Full Pipe Velocity
Average Day 0.5 ft/s
Max Month 0.6 ft/s
Peak Hr Infl 1.? ft/s
Plant Flows
Average Day 667 gpm
Max Month 833 gpm
Peak Hr lnfl 1667 gpm
Plant Flows
Average Day 667 gpm
Max Month 833 gpm
Peak Hr Infl 1667 gpm
Pipe Velocity
One Pump 4.5 ft/s
Two Pumps 8.2 ft/s
Average Day
Max Month
Average Day
Max Month
HRT
12.8 days
10.3 days
HRT
8.6 days
6.9 days
970563
Table 1
3. Cell No. 3 Detention Time
4. Total Detention Time
5. Aeration Equipment Provision and Requirements, See Table 2.
Average Day
Max Month
Average Day
Max Month
HRT
1.7 days
1.4 days
HRT
23.1 days
18.5 days
6. Interconnecting pipe, 6 -inch Pipe Velocity
CHLORINATION/DECHLORINATION SYSTEMS
1. Contact Chamber Detention Time
Volume equals 29,000 gallons
Average
Max Month
Peak Hr Infl
Average
Max Month
Peak Hr Effl
7.6 ft/s
9.5 ft/s
18.9 ft/s
HRT
44 minutes
35 minutes
29 minutes
2. Chlorinator existing size, 100 ppd
Required size to dose at 8 mg/L at max month 80 ppd
3. Sulfonator existing size, 100 ppd
Assume 2 mg of SO, is required to neutralize I mg of CI,
Maximum permissible CI, residual for sulfonator to handle at max month
EFFLUENT METERING AND OUTFALL
1. Parshall flume, 6 -inch throat, maximum capacity, 1740 gpm
2. Outfall gravity, 24 -inch
Minimum slope, 0.001
Average Day
Max Month
Peak Hr Effl
5.0 mg/L
Plant Flow
667 gpm
833 gpm
1000 gpm
Full Pipe Velocity
Average 0.5 ft/s
Max Month 0.6 ft/s
Peak Hr Effl 0.7 ft/s
Capacity at minimum slope flowing full 4.6 mgd
970563
Table 2
EVANS WWTP
SITE APPLICATION
AERATION AND MIXING CALCULATIONS (Summer)
TREATMENT PLANT AND DESIGN DATA
I. Average day design flow
2. Maximum month design flow
3. Peak flow, mgd
4. Design influent BOD5 concentration
5. Design influent BOD5 loading
6. Design Wastewater Temperature
7. Plant site elevation
0.96 mgd
1.20 mgd
2.40 mgd
277 mg/L
2772 ppd
20 Celsius
4,650 feet
OXYGEN AND MIXING REQUIREMENTS (Design Criteria)
1. Oxygen required per BOD5 2.0 lbs O,/BOD5
2. Mixing Hp required per volume of basin 7.5 Hp/million gallons
AERATED LAGOON INFORMATION
I. Cell No. I Volume
2. Cell No. 2 Volume
3. Cell No. I Aeration Equipment (Aspirators)
Number
Hp (each)
Standard Oxygen Transfer
4. Cell No. 2 Aeration Equipment (Surface Aerators)
Number
Hp (each)
Standard Oxygen Transfer
12.30 million gallons
8.25 million gallons
10
10 Hp
2.50 lb/Hp-hr
3
15 Hp
3.00 lb/Hp-hr
PRESSURE INFORMATION
I. Standard atmospheric pressure, Ps 14.70 psi
2. Pressure at plant site elevation, Pa 12.38 psi
OXYGEN SOLUBILITY INFORMATION
I. Alpha
2. Beta
3. Dissolved oxygen requirement in the wastewater, CL
4. Oxygen solubility at standard pressure and temperature, Cs
5. Oxygen solubility at wastewater temperature, Css
0.85
0.95
2.0 mg/L
9.17 mg/L
9.20 mg/L
970563
Table 2
OXYGEN CALCULATIONS (Based on Maximum Month)
1. Actual Oxygen Requirements (AOR)
GODS loading * oxygen required/pound of BOD5
2. Standard Oxygen Requirement (SOR)
SOR =
AOR
Alpha*(Csw-CL)*(I.024)^(T-20)
Cs
Csw = Beta * Css * P
P = Ratio of barometric pressure at the plant divided
by barometric pressure at sea level
P=
Csw =
0.84
7.36 mg/L
AOR = 5544 ppd
SOR = 11158 ppd
3. Standard Oxygen Available
Cell No. I =
Cell No. 2 =
Total
6000 ppd (600 per aspirator)
3240 ppd (1080 per aerator)
4. Standard Oxygen Available Firm Capacity (One aerator out of service)
Cell No. 1 = 600O ppd
Cell No. 2 = 2160 ppd
Total
5. Aeration Equipment Required to meet SOR
Aspirators in Cell No. I 12 at 10 Hp
Aerators in Cell No. 2 5 at 15 Hp
Standard Oxygen Available Firm Capacity (One aerator out of service)
Cell No. 1 = 7200 ppd
Cell No. 2 = 4320 ppd
Total
MIXING CALCULATIONS
I. Cell No. I recommended Hp for mixing
2. Cell No. 2 recommended Hp for mixing
3. Cell No. I available Hp including new aspirators
4. Cell No. 2 available Hp including additional aerators
9240 ppd
8160 ppd
11520 ppd
92 Hp
62 Hp
120 Hp
75 Hp
970563
Table 2
EVANS WWTP
SITE APPLICATION
AERATION AND MIXING CALCULATIONS (Winter)
TREATMENT PLANT AND DESIGN DATA
1. Average day design flow
2. Maximum month design flow
3. Peak flow, mgd
4. Design influent BOD5 concentration
5. Design influent BOD5 loading
6. Design Wastewater Temperature
7. Plant site elevation
OXYGEN AND MIXING REQUIREMENTS (Design Criteria)
1. Oxygen required per BOD5
2. Mixing Hp required per volume of basin
AERATED LAGOON INFORMATION
I. Cell No. I Volume
2. Cell No. 2 Volume
3. Cell No. 1 Aeration Equipment (Aspirators)
Number
Hp (each)
Standard Oxygen Transfer
4. Cell No. 2 Aeration Equipment (Surface Aerators)
Number
Hp (each)
Standard Oxygen Transfer
PRESSURE INFORMATION
I. Standard atmospheric pressure, Ps
2. Pressure at plant site elevation, Pa
OXYGEN SOLUBILITY INFORMATION
I. Alpha
2. Beta
3. Dissolved oxygen requirement in the wastewater, CL
4. Oxygen solubility at standard pressure and temperature, Cs
5. Oxygen solubility at wastewater temperature, Css
0.96 mgd
1.20 mgd
2.40 mgd
277 mg/L
2772 ppd
4 Celsius
4,650 feet
2.0 lbs O,/BOD5
7.5 Hp/million gallons
12.30 million gallons
8.25 million gallons
10
10 Hp
2.50 lb/Hp-hr
3
15 Hp
3.00 lb/Hp-hr
14.70 psi
12.38 psi
0.85
0.95
2.0 mg/L
9.17 mg/L
13.10 mg/L
Table 2
OXYGEN CALCULATIONS (Based on Maximum Month)
I. Actual Oxygen Requirements (AOR)
BOD5 loading * oxygen required/pound of BOD5
2. Standard Oxygen Requirement (SOR)
SOR =
SOR =
AOR
Alpha*(Csw-CL)*(1.024)^(T-20)
Cs
Csw = Beta * Css * P
P = Ratio of barometric pressure at the plant divided
by barometric pressure at sea level
P=
Csw =
3. Standard Oxygen Available
Cell No. I =
Cell No. 2 =
Total
0.84
10.48 mg/L
6000 ppd (600 per aspirator)
3240 ppd (1080 per aerator)
4. • Standard Oxygen Available Firm Capacity (One aerator out of service)
Cell No. 1 = 6000 ppd
Cell No. 2 = 2160 ppd
Total
5. Aeration Equipment Required to meet SOR
Aspirators in Cell No. 1 12 at 10 Hp
Aerators in Cell No. 2 4 at 15 Hp
Standard Oxygen Available Firm Capacity (One aerator out of service)
Cell No. 1 = 7200 ppd
Cell No. 2 = 3240 ppd
Total
MIXING CALCULATIONS
I. Cell No. I required Hp for mixing
2. Cell No. 2 required Hp for mixing
3. Cell No. I available Hp including new aspirators
4. Cell No. 2 available Hp including additional aerators
AOR = 5544 ppd
10308 ppd
9240 ppd
8160 ppd
10440 ppd
92 Hp
62 Hp
120 Hp
60 Hp
970563
headworks, a new standby generator, a new laboratory, and outfall modification are planned for the
near future.
TM No. 11 of the Masterplan looked at alternative locations and options for treating wastewater
including:
• Expanding the Evans WWTP
• Re -rating the Evans WWTP
• Taking over the Hill -N -Park WWTP and treating some flow there
• Sending all or some of the wastewater to Greeley.
The re -rating alternative was chosen to handle near future flows with the other alternatives being
more pertinent when the re -rated capacity is reached.
Flood plain and natural hazard analysis.
The Evans WWTP is located out of the 100 -year flood plain but within the 500 -year flood plain.
However, during the high South Platte flood levels in 1995 the outfall backed up requiring the re-
routing of plant effluent to an emergency channel for discharge to the South Platte. The City is
planning to alleviate this potential problem by installing a flood gate and constructing a pump pit to
discharge the effluent.
No other natural hazards have been identified in the area.
Detailed description of selected alternatives including legal description of the site, treatment
system description, design capacities, and operational staffing needs.
The modifications planned for handling the re -rated flow includes adding two aspirator units to Cell
No. 1, two aerators to Cell No. 2 and removing the rock filter in Cell No. 3.
The legal description of the plant is given in the ownership deeds presented in the Appendix.
The treatment system description includes the following processes:
• Influent pumping and flow measurement
• A three cell aerated lagoon system with the third cell serving as a polishing pond
• Chlorination
• Dechlorination with sulfur dioxide
• Effluent flow measurement and gravity outfall
970553
The design capacities are as follows:
Average daily flow, mgd
Maximum month average daily flow, mgd
Peak hour influent flow, mgd
Peak hour effluent flow, mgd
0.96
1.20
2.40
1.44
BOD5 max month loading, ppd 2772
Based on these design flows the City will need to start planning for an expansion or other treatment
alternatives when the 30 -day average flow reaches 0.96 mgd and begin implementation at 1.14
mgd.
The current and future requirements for operational staff are presented in TM No. 12 of the
Masterplan and includes:
1 - Supervisor
1 - Operator
1 - Tech I
Legal arrangements showing control of site for the project life.
The Evans Wastewater Treatment Plant is located on land which is owned by the City of Evans.
No additional land will be required to accommodate the system modifications associated with this
Site Application. The ownership deeds are presented in the Appendix.
Institutional arrangements such as contract and/or covenant terms for all users which will be
finalized to accomplish acceptable waste treatment.
Presented in the Appendix is applicable portion of the City of Evans Code of Ordinances.
Management capabilities for controlling the wastewater throughout and treatment within the
capacity limitations of the proposed treatment works, i.e., user contracts, operating agreements,
pretreatment requirements.
Management and operation of the Evans Wastewater Treatment Plant will continue to be done
solely by the City of Evans. Based on the current industry, no pretreatment program currently is
necessary.
970563
Financial system which has been developed to provide for necessary capital and continued
operation, maintenance, and replacement through the life of the project. This would include, for
example, anticipatedfee structure.
Enclosed in the Appendix is a copy of the resolution defining sewer rates and fees. Smaller
projects such as the improvements required for plant re -rating will be financed through the utility
fund from these fees. The City has applied for and will seek SRF funding for the other
improvements described earlier including new influent pump station headworks.
Implementation plan and schedule including estimated construction time and estimated start-up
date.
Construction of the improvements for the plant re -rating is dependent on approval by CDPHE.
Assuming approval, plans and specs would be finalized with bidding of equipment to occur such
that installation of the aeration equipment would be begin within one year of the Site Application
approval. The City has the two additional aerators. The two aspirators will need to be purchased
and power supplied to all the additional units.
970563
Appendix
Water/WastewaterMasterplan Technical Memorandums (TM)
TM No. I Introduction and Purpose of Masterplan
TM No. 2 Service Area Characteristics
TM No. 9 Wastewater Flows
TM No. 10 Wastewater Collection System Evaluation
TM No. 11 Wastewater Treatment Evaluation
TM No. 12 Wastewater 10 -Year Capital Improvements Plan (CIP)
CDPHE Letter, 1/9/96, Ammonia Limits
Ownership Deeds
City of Evans Code of Ordinances
970563
Water/WastewaterMasterplan Technical Memorandums (TM)
970563
TM No.1 Introduction and Purpose of Masterplan
970563
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO. 1
To: City of Evans, Colorado
From: HDR Engineering, Inc.
Date: March 7, 1996
Revised June 12, 1996
Subject: Introduction and Purpose of Master Plan
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Background and Purpose of Master Plan Update
The City of Evans is primarily a residential community of approximately 6,800 people.
Originally an agricultural community, Evans grew rapidly during the 1970s, nearly doubling in
size. Although the growth of the City in the 1990s has been substantially less than that of the
1970s, the City has recognized its need to plan for future growth and development in the
community. Water and wastewater system planning is one facet of that planning process.
The City of Evans presently purchases water treatment from the City of Greeley, Colorado. The
water is delivered to its residents through a distribution system owned and operated by the City
of Evans. The City operates its own wastewater treatment facility and collection system. In the
past, several planning reports have been prepared to evaluate system needs as the City of Evans
grows. However, the City desired a consolidated comprehensive master plan to address facility
needs both for the long-term and the next ten years.
The purpose of the water and wastewater master plan is to provide the City of Evans with a water
and wastewater master plan for use as a planning tool in meeting the City's existing and future
utility needs for growth during the next ten years. This master plan will serve as a guideline for
implementing future improvements to the water and wastewater systems. The recommended
improvements must consider future long-term requirements as well as existing needs in order to
meet long range planning goals.
1.2 Scope of Project
In order to accomplish the purpose of this report identified above, the following key tasks were
required:
PIEVANSAIRDO TMLAIC
TM1-1
970563
Water Rights
• Review of Existing Data and Planning Reports
• Establish Projected Land Use and Population
• Review Current Water Supplies and Identify Supply Needs
• Review Existing Water Demands and Project Future Demands
• Evaluate and Recommend Methods to Maintain Water Rights
Water Distribution System
• Project Future Water Demands
• Evaluate Master Meter Locations
• Evaluate Existing Water Distribution System
• Recommend Water Distribution System Requirements
• Develop 10 -Year Capital Improvement Plan
• Conduct Rate Study
Wastewater Collection and Treatment System
• Project Future Wastewater Flows
• Review Existing Wastewater Treatment Facility
• Review Existing Wastewater Collection System
• Recommend Wastewater Treatment and Collection System Requirements
• Develop 10 -Year Capital Improvements Plan
• Conduct Rate Study
1.3 Description of Service Area
The service area includes the existing City of Evans and the extended area referred to as the
Urban Growth Area (UGA). The UGA is bordered by 71st Avenue on the west, the City of
Evans existing City limits on the west, 32nd Street on the north and the Platte River on the south
and east. The existing City of Evans includes approximately 1700 acres. The UGA includes
approximately 6700 acres for a total service area of 8400 acres.
1.4 Abbreviations
Table 1-1 summarizes the abbreviations used in this report.
PAE V ANSMPDOCITM L DOC
TMl-2
970563
TABLE 1-1
List of Abbreviations
Abbreviation Description
of
Ave. or AVE.
avg. or AVG.
AD
cfs
CIP
DU
ea. or EA
fps
ft.
gpd
gpad
gpcd
gpm
HWY
in.
LF
max.
MD
MF
MG
MH
mgd
min.
MSL
PF
psi
Rd.
sf
SFD
UGA
WTP
WWTP
yr.
acre feet
Avenue
Average
Average day water demand
cubic feet per second
Capital Improvement Plan
Dwelling Units
Each
feet per second
feet
gallons per day
gallons per acre per day
gallons per capita per day
gallons per minute
Highway
inches
lineal feet
maximum
Maximum day water demands
multi -family
million gallons
Maximum hour water demands
million gallons per day
minimum
mean seal level
peaking factor
pounds per square inch
Road
square feet
single family detached
Urban Growth Area
Water Treatment Plant
Wastewater Treatment Plant
year
1.5 Existing Reports and Data
Table 1-2 summarizes existing reports and data utilized for this report.
PAEVANSA1P\DU(\tM I. DCC
TM1-3
970363
TABLE 1-2
Existing Reports and Data
Document/Reference
Meeting Minutes of Evans Water and
Sewer Board
City of Evans Water Master Plan
Northern Colorado Regional Planning
Study
City of Evans Water Rate Study
Investigation of Evans Ditch
Temporary Substitute Supply Plan
Evaluation of Wastewater Facilities
Volume I
Joint Southern Weld County Water
System Study
City of Evans Comprehensive Plan
Year Prepared By
1993-1994 City of Evans
1989 HDR Engineering
May 1995 BHA Design Inc./ERO
Resources Corp./Clarion
Assoc./Henderson Assoc.
1986
1987 Tipton and Kalmbach
1994 Rocky Mountain Consultants
March 1993 Rocky Mountain Consultants
March 1990 Rocky Mountain Consultants
1996 City of Evans
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TM No. 2 Service Area Characteristics
970563
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO.2
To: City of Evans, Colorado
From: HDR Engineering, Inc.
Date: March 7, 1996
Revised June 12, 1996
Subject: Service Area Characteristics
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Purpose of Memorandum
The purpose of this technical memorandum is to summarize the existing and projected future
service area characteristics including population and land use. The information will be used as a
data base for establishing water demands and wastewater flows for the City of Evans and the
future Urban Growth Area (UGA).
1.2 Service Area Physical Features
Ground elevations within the study area range between 4,900 feet MSL in the northwestern part
of the UGA to. 4,635 feet MSL in the southeastern part of the City. The area generally slopes
downward from the northwest to the southeast toward the South Platte River.
The Evans Town Ditch meanders its way through the City from the southwest to the northeast.
Several homes in the southeastern portion of the City are currently supplied irrigation water from
the Ditch through a City -operated irrigation piping system.
2.0 ANALYSIS
2.1 Existing Land Use
2.1.1 Development and Population. The existing land use within the City of Evans is
regulated by the City zoning ordinances. These ordinances help to direct development
according to the long range goals for the City. The existing development was identified
by the use of aerial photographs taken of the study area by the City in 1994. The current
population of the City of Evans is estimated at 6,817 people. There are approximately
2,901 residential dwelling units in the City, averaging approximately 2.4 persons per unit.
The average residential density is typical for communities similar to Evans. Typically,
densities vary for the various types of residential land use as summarized in Table 2-1.
P]E VANSMPNOCITM2. DOC
TM2-1
970563
TABLE 2-1
Existing Residential Densities
Development Type Person Per Unit
Low Density (Single Family Detached)' 2.8 - 3.5
Medium Density (Single Family Attached, Duplex/Mobile Home) 2.6
High Density (Multi -Family, Apartments) 2.3
'The density varies with the lower density found in the older part of the City and the
higher density in the newer west areas of the City.
2.1.2 Land Use. A comprehensive land use plan was recently completed by the City of
Evans in 1996 which identified the following major land use categories:
• Residential
• Commercial/Industrial
• Open Space
• Mixed Use
• Large Lot (2.5 acres/lot minimum)
For purposes of utility masterplanning another land use category defined as Public was
indicated. This designation was not included in the Comprehensive Plan since it is
typically included as a part of residential landuse. However, for masterplanning, public
land use represents a unique water demand. Therefore, the actual land use was included
as a separate category.
For the water and wastewater systems evaluations, the existing residential development
was categorized as either single family detached, multi -family, duplex/mobile home, or
large lot. Commercial and industrial land uses were combined since, typically, water
demands do not vary between the two land use types for the current development in
Evans. Public land use which includes parks, cemeteries, schools, and City offices was
also included because the water demands for these types of facilities generally differ from
other types of land use. Finally, open space areas were included since these areas do not
have any water use. Open space includes the U.S. Highway 85 and Union Pacific
Railroad rights -of -way, flood plan areas, and land use buffers. A summary of the existing
land use areas and residential house counts for the City and the UGA is summarized in
Table 2-2.
P?EVANSIP\DOCITM2.poC
TM2-2
970563
TABLE 2-2
Existing Land Use
LAND USE
City of Evans
Residential
Single Family Detached (Low
Density)
Duplex/Mobile Home (Medium
Density)
Multi -Family (High Density)
Subtotal Residential
Commercial/Industrial/Mixed Use
Public/Parks
Open Space
TOTAL
Urban Growth Area
Residential
Large Lot (Low Density)
Single Family Detached (Low
Density)
Duplex/Mobile Home (Medium
Density)
Multi -Family (High Density)
Subtotal Residential
Commercial
Public/Parks
Open Spaces
TOTAL
Developed Units Percent Of
Acres Units Per Acre Total Area
429 1,438 3.4 38%
104 414 4.0 9%
40 526 13.2 4%
573 2,378 4.2 51%
241 21%
125 11%
187 17%
1,126 100%
378' 151 0.4 44%
277 2072 0.7 32%
210 6443 3.1 24%
0 0 0 0%
865 1,002 1.2 100%
0 0%
0 0%
0 0%
865 100%
'Approximated based on number of homes in service area at 2.5 acres/unit
2Includes Arrowhead (151) and Carriage Estates (56)
3Includes Hill -n -Park and West Hill -n -Park (488), and Country Estates (156)
2.2 Future Land Use
The Evans 1996 Comprehensive Plan was used as a guideline to establish projected development
within the service area for ten year (2005) and ultimate development. Future residential
P:EV ANSMP\OOC\TM2. DOC
TM2-3
970563
development densities utilized in this study were based on average densities as summarized in
Table 2-3.
TABLE 2-3
Future Residential Development Densities
Development Type
Low Density Residential
Medium Density Residential
High Density Residential
Dwelling Units per Acre Dwelling Units per Acre
Comprehensive Plan Used for Master Plan
0-4
4-8
8 & up
4
8
12
Future land use areas were divided into similar categories as for existing land use. A summary of
the projected future land use area units and population is presented in Table 2-4. The future land
use areas were used to project water demands and wastewater flows for the service area. Figure
2-1 illustrates the existing land use and Figure 2-2 shows the projected 2005 and ultimate
development future land use.
3.0 SUMMARY
3.1 Population Projections
Based on the projected land use provided by the City of Evans and the residential unit densities
presented in Table 2-3, populations were projected for the 2005 and ultimate development in the
UGA summarized as follows:
Existing City of Evans Population
Existing City of Evans and UGA Population
Projected 2005 City of Evans Population
Projected 2005 City of Evans and UGA Population
Projected City of Evans Population
Projected City of Evans and UGA Ultimate Development Population
6,817
9,562
9,093
12,438
9,968
36,504
Table 2-4 summarizes the projected ten year (2005) land use and population. Table 2-5
summarizes the projected ultimate development land use and populations.
Figure 2-3 illustrates population growth projections for 1995 through 2015 for the City of Evans
and UGA. The population growth projections for 2%, 3%, and 4.55% are based on projections
provided in the Northern Colorado Regional Planning Study prepared in May 1995. The City of
Evans' projections, as shown on the figure, are within the regional planning study's range of
growth. Therefore, the City of Evans projections will be utilized for property water demands and
wastewater flows.
P\EVA NSMPNOC\TM2. DOC
TM2-4
970563
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970563
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970563
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970563
TM No. 9 Wastewater Flows
970563
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO. 9
To: City of Evans, Colorado
From: HDR Engineering, Inc.
Date: February 26, 1996
Revised June 12, 1996
Subject: Wastewater Flows
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Purpose of Memorandum
The purpose of this Technical Memorandum (TM) is to discuss methods and data used to
develop wastewater flows. The wastewater flows determined in this TM will become the basis
for evaluation of existing facilities and projection of future collection system and wastewater
treatment requirements.
1.2 Components of Wastewater Flow
Wastewater generally consists of three components:
• Domestic wastewater
• Industrial wastewater
• Infiltration and inflow (I/I)
Domestic Wastewater, also referred to as sanitary wastewater, is comprised of discharge from
residential, commercial, recreational, and institutional areas. Industrial Wastewater is
wastewater in which industrial wastes predominate. Infiltration/Inflow is water that enters the
collection system through indirect and direct means. Infiltration is extraneous groundwater
entering the system through cracks and breaks, leaking joints, and/or porous walls (indirect
means). Inflow is stormwater entering the system via storm drain connections, roof drains,
foundation and basement drains, and/or through sanitary sewer manhole covers (direct means).
1.3 Estimating Wastewater Flows
Various practices are currently used to estimate wastewater flows including:
• Estimations based on water supply data
• Published typical wastewater flow values
• Wastewater flows of similar communities
• Historical data collected within the study area
P EVANSMPD0C\TM9.D0C
TM9-1
970563
Evaluation of historical data, as is the case for the City of Evans, is the most reliable approach for
estimating projected wastewater flows.
The goal in estimating wastewater flows for this study is to predict four values:
Average daily flow. The average flowrate occurring over a 24 -hour period based on total
annual flowrate data. Average flowrate is used in evaluating treatment plant capacity and
in developing flowrate ratios used in design. The average flowrate may also be used to
estimate such items as pumping and chemical costs, sludge solids, and organic -loading
rates.
Maximum daily flow. The maximum flowrate that occurs over a 24 -hour period based on
annual operating data. The maximum daily flowrate is important particularly in the
design of facilities involving retention time such as equalization basins and chlorine -
contact tanks.
Peak hourly flow. The peak sustained hourly flowrate occurring during a 24 -hour period
based on annual operating data. Data on peak hourly flows are needed for the design of
collection and interceptor sewers, wastewater -pumping stations, wastewater flowmeters,
grit chambers, sedimentation tanks, chlorine -contact tanks, and conduits or channels in
the treatment plant.
Minimum daily flow. The minimum flowrate that occurs over a 24 -hour period based on
annual operating data. Minimum flowrates are important in the sizing of conduits where
solids deposition might occur at low flowrates.
2.0 WASTEWATER FLOW DETERMINATION
2.1 Analysis of Wastewater Flowrates
2.1.1 Historical Wastewater Flow Data. The City of Evans provided historical
wastewater flow and quality data collected at the treatment plant for the period of January
1986 through July 1995. The data provided was in the form of discharge monitoring
reports (DMR). Information from the DMRs has been tabulated and is included in Table
9-1 in Appendix 9-A.
Wastewater flow data was recorded beginning in August 1989. The Doppler ultrasonic
flow meter used to measure wastewater treatment plant (WWTP) influent was deemed
inaccurate in a report entitled Evaluation of Wastewater Treatment Facilities and Related
Investigations. filed by Rocky Mountain Consultants in March 1993. The meter was
recalibrated early in 1992 therefore, flow data for this study includes only information
collected after recalibration of the meter.
2.1.2 Seasonal Wastewater Flows. A plot of flow data for the period between May
1992 and April 1995, shown in Figure 9-1 at the end of this TM, indicates definite
fluctuations in wastewater flow relative to the time of year. Based on this observation, the
year was divided into a wet and dry season relative to wastewater flows with the wet
P \.EVANSNI%DOQTN19 DOC TM9-2
970563
season being defined as the period between May and September and the dry season from
October through April.
Increased wastewater flow recorded during the wet season appears to be due to the
presence of infiltration corresponding to beginning of the irrigation season. When the
Evans Ditch is charged in April, the local groundwater table, and consequently
potentiometric head, rises and older clay pipes in the system allow increased amounts of
infiltration. An estimation of system infiltration was calculated by subtracting the
average dry season wastewater flow from the average wet season wastewater flow. The
average I/I value, over the period from May 1992 through April 1995, was determined to
be 0.11 million gallons per day (mgd).
2.2 Determination of Wastewater Flows
2.2.1 General. Wastewater flows were analyzed over the wet and dry periods
discussed above, to determine the average daily domestic flow. The same division of
months is used to define summer and winter periods in an effort to determine warm and
cold season wastewater flows to assist in analyzing nitrification requirements at the
wastewater treatment facility.
2.2.2 Average Daily Domestic Flow. Table 9-1 is data compiled from the DMRs and
broken down into the above -mentioned seasons over the three years of information
analyzed. Table 9-1 contains calculations of average wet (summer) and dry (winter)
wastewater flows in mgd which have been summed and converted to units of gallons per
capita per day (gpcd). One of the final entries in the table, 110 gpcd, represents an
average daily wastewater flow per capita over the three year study period.
2.2.3 Maximum Daily Domestic Flow. In addition to average daily flows, Table 9-1
contains the maximum daily flow recorded for each month of data provided. The highest
maximum daily flow is shown in the maximum values row of information and is used to
determine the actual maximum daily peak factor, which is the ratio of maximum daily
flow to average daily flow.
The peaking factor used herein, 1.50, is the average value shown in Table 9-1. The
maximum daily flow has been determined to be 164 gpcd.
2.2.4 Peak Hourly Domestic Flow. Peak hourly domestic flow has been determined by
applying a peaking factor of 3.75 to the average daily flow of 110 gpcd. This factor was
taken from Figure 5-1 of Wastewater Engineering - Treatment, Disposal, and Reuse,
Third Edition. This yields a peak hourly domestic wastewater flow of 413 gpcd.
P ,EVANSMP\DOC\TM9 DOC
TM9-3
970563
TABLE 9-1
Estimated Average And Maximum Daily Wastewater Flows
Year 1
Year 2
Population 6092
6308
Year3
6817
Influent Flow
Influent Flow
Influent Flow
(mgd)
(mgd)
(mgd)
Month, Year Avg. Max.
Month, Year
Avg. Max.
Month, Year
Avg.
Max.
Wet/Summer
Wet/Summer
WedSurnmer
May. 1992 0.75 1.23
May. 1993
0.70 0.77
May. 1994
0.63
0.70
Jun. 1992 0.71 0.90
Jun. 1993
0.73 0.76
Jun. 1994
0.72
0.93
Jul. 1992 0.70 0.83
Jul. 1993
0.76 0.83
Jul. 1994
0.73
0.94
Aug. 1992 0.78 0.96
Aug. 1993
0.77 0.83
Aug. 1994
0.90
0.98
Sep. 1992 0.74 0.84
Sep. 1993
0.76 0.85
Sep. 1994
0.95
1.03
Ave Wet/Summer 0.74
0.74
0.79
1/! 0.11
0.11
0.11
Dry/Winter
Dry/Winter
Dry/Winter
Oct. 1992 0.69 0.85
Oct. 1993
0.67 0.69
Oct. 1994
0.74
0.98
Nov. 1992 0.64 0.71
Nov. 1993
0.65 0.68
Nov. 1994
0.68
0.71
Dec. 1992 0.63 0.77
Dec. 1993
0.63 0.65
Dec. 1994
0.64
0.70
Jan. 1993 0.61 0.68
Jan. 1994
0.63 0.89
Jan. 1995
0.63
0.65
Feb. 1993 0.63 0.64
Feb. 1994
0.70 0.89
Feb. 1995
0.62
0.64
Mar. 1993 0.61 0.63
Mar. 1994
0.59 0.82
Mar. 1995
0.64
0.74
Apr. 1993 0.67 1.06
Apr. 1994
0.60 0.75
Apr. 1995
0.68
0.89
Ave Dry/Winter 0.64
0.64
0.66
l/f 0.00
0.00
0.00
Ave Values 0.69
0.69
0.72
Max Values 1.23
0.89
1.03
Peak Factor 1.79
1.29
1.42
Ave Peak Factor 1.50
Total Flow Existing Areas:
Ave gpcd 113
110
106
Average Daily Flow for Study
Period gpcd 110
Maximum Daily Flow for Study
Period gpcd 164
2.2.5 Minimum Daily Domestic Flow - is typically taken as 25 percent of the average
daily domestic wastewater flow. This value is based on historical data for small
communities similar to Evans. The result is a minimum daily flow of approximately 28
gpcd.
P TVANS\IP\DOCATM9 DOC
TM9-4
970563
2.2.6 Summary of Per Capita Wastewater Flows
TABLE 9-2
Existing Wastewater Flowrates
Description Domestic Flowrate
Average daily flow
Maximum daily flow
Peak hourly flow
Minimum daily flow
110 gpcd
164 gpcd
413 gpcd
28 gpcd
Flowrates calculated in Table 9-2 represent values to be applied to existing areas of the
City being served by an older collection system. These flowrates consider City of Evans
historical data for both domestic wastewater and I/I. Wastewater flowrates for newer and
proposed developments will have the same domestic flowrate contribution as existing
areas although, newer collection systems will have a reduced I/I due to condition of the
pipelines. Typical published values of I/I contributions to wastewater flows are
approximately 10 gpcd, therefore, existing flowrates have been reduced by 6 gpcd to
predict flow rates from newer and proposed developments. These values are shown in
Table 9-3.
TABLE 9-3
Wastewater Flowrates
Proposed Developments
Description Estimated Flowrate (gpcd)
Average daily flow
Maximum daily flow
Peak hourly flow
Minimum daily flow
104
158
407
22
3.0 PROJECTED WASTEWATER FLOWRATES
3.1 Estimation of Wastewater Flows
3.1.1 Wastewater Basins. The area within the City's growth boundary has been
divided into eight wastewater basins. Each basin will contribute a given amount of
wastewater flow based on several factors including:
overall basin area
area of various landuses within the basin
density of each landuse type (households per acre)
density per household (people per household)
Figure 10-2, located in TM 10, shows how the growth area divided into wastewater
basins. Table 9-4, also at the end of this TM, presents a breakdown of the projected
P:\EVANSMPNOQT A19. DOC
TM9-5
970563
wastewater flow from each basin. The estimated average daily wastewater flow for the
eight basins, under current planned buildout, is approximately 3.79 mgd.
3.1.2 Undeveloped Areas Within Existing City Limits Contributing to Basin 8. These
areas will also contribute additional wastewater flows. As shown in Table 9-4, the
average daily wastewater flows estimated for this portion of development is
approximately 0.64 mgd.
3.1.3 Ten Year Growth Areas. Areas within the overall planned growth area
designated for development over the next ten years have been identified in order to
determine more immediate wastewater collection and treatment needs. These areas are
indicated on Figure 2-2, and estimated wastewater flows from these areas are identified in
Table 9-5. Additional average daily wastewater flow from the ten year growth areas has
been calculated at 0.38 mgd.
P'\P. VANSMP\DOC\TM9. D{)([
TM9-6
970563
TABLE 9-4
Projected Ultimate Average Daily Wastewater Flows For Urban Growth Area
And Undeveloped Areas Within Existing City Limits Contributing To Basin 8
People per Household
Unit Wastewater Flow per Capita
Unit Wastewater Flow per Acre
Basin 1
Total Area
Land Use:
Residential
Low Density
Medium Density
High Density
Commercial/Industrial
Public/Parks
Open Space
Large Lot
Basin 2
Total Area
Land Use:
Residential
Low Density
Medium Density
High Density
Commercial/Industrial
Public/Parks
Open Space
Large Lot
Basin 3
Total Area
Land Use:
Residential
Low Density
Medium Density
High Density
CommerciaVlndustrial
Public/Parks
Open Space
Large Lot
2.60
104.00 gallons /day (Includes I/I)
800.00 gallons /day (CommerciaVlndustrial)
Households Total
Acres per Acre Households
349.5
349.5
623.4
623.4
235.5
0.7
234.8
4.00
8.00
12.00
0.00
0.00
0.00
Projected
Wastewater
Flow
(mgd)
0.000
0.000
0.000
0.000
Basin 1 Wastewater Flow 0.000
4.00
8.00
12.00
0.00
0.00
0.00
0.000
0.000
0.000
0.000
Basin 2 Wastewater Flow 0.000
4.00
8.00
12.00
0.00
0.00
0.00
0.000
0.000
0.000
0.000
Basin 3 Wastewater Flow 0.000
PIE VANSMP'DOQTM9. DOC
TM9-7
970563
TABLE 9-4 (continued)
Acres
Basin 4
Total Area 857.2
Land Use:
Residential
Low Density 209.0
Medium Density
High Density
Commercial/Industrial
Public/Parks
Open Space 35.1
Large Lot 613.1
Basin 5
Total Area 698.8
Land Use:
Residential
Low Density 352.5
Medium Density
High Density 17.0
Commercial/Industrial
Public/Parks
Open Space 193.4
Large Lot 135.9
Basin 6
Total Area 2527.1
Land Use:
Residential
Low Density 272.4
Medium Density 293.4
High Density
Commercial/Industrial 48.4
Public/Parks
Open Space 277.8
Large Lot 1635.2
Households Total
per Acre Households
4.00
8.00
12.00
835.9
0.00
0.00
Projected
Wastewater
Flow
(mgd)
0.226
0.000
0.000
0.000
Basin 4 Wastewater Flow 0.226
4.00
8.00
12.00
1410.0
0.00
204.0
0.381
0.000
0.055
0.000
Basin 5 Wastewater Flow 0.436
4.00
8.00
12.00
1089.4
2347.0
0.00
0.295
0.635
0.000
0.039
Basin 6 Wastewater Flow 0.968
P]EVANSMPDOC\TM9 DDC
TM9-8
970563
TABLE 9-4 (continued)
Acres
Basin 7
Total Area 440.6
Land Use:
Residential
Low Density
Medium Density 99.2
High Density
Commercial/Industrial 142.1
Public/Parks 121.9
Open Space
Large Lot 77.4
Basin 8
Total Area 943.7
Land Use:
Residential
Low Density 163.6
Medium Density 255.9
High Density 82.9
Commercial/Industrial 241.9
Public/Parks
Open Space 154.0
Large Lot 45.4
Households Total
per Acre Households
4.00
8.00
12.00
0.00
793.8
0.00
Projected
Wastewater
Flow
(mgd)
0.000
0.215
0.000
0.114
Basin 7 Wastewater Flow 0.328
4.00
8.00
12.00
654.5
2047.3
994.8
Basin 8 Wastewater Flow
Urban Growth Area Projected Average Daily Wastewater Flow
Undeveloped Areas Inside Existing City Limits Contributing to Basin 8
Total Area
Land Use:
Residential
Low Density
Medium Density
High Density
Commercial/Industrial
Public/Parks
Open Space
Large Lot
679.0
140.0
71.0
7.0
393.0
68.0
4.00
8.00
12.00
560.0
568.0
84.0
0.177
0.554
0.269
0.194
1.193
3.152
0.151
0.154
0.023
0.314
Subtotal Wastewater Flow 0.642
Total Average Daily Projected Wastewater Flow 3.794
P kEVANS\IPDOQTS19. pOC
TM9-9
970563
TABLE 9-5
Projected Wastewater Flows For Ten Year Growth Areas
People per Household
Unit Wastewater Flow per Capita
Unit Wastewater Flow per Acre
Peaking Factor
Total Area
Land Use:
Residential
Low Density
Medium Density
High Density
Commercial/Industrial
Public/Parks
Open Space
Large Lot
Acres
317.0
156.0
51.0
6.0
104.0
2.60
104.00 gallons /day (Includes I/I)
800.00 gallons /day (Commercial/Industrial)
1.50
Households Total
per Acre Households
4.00
8.00
12.00
624.0
408.0
72.0
Projected
Wastewater
Flow
(mgd)
0.169
0.110
0.019
0.083
Average Daily Wastewater Flow 0.382
Maximum Daily Wastewater Flow 0.531
3.2 Summary of Existing and Projected Estimated Wastewater Flows
Table 9-6 presents a summary of estimated wastewater flows by basin.
TABLE 9-6
Existing And Projected Estimated Wastewater Flows
Peaking Factor
1.5
Wastewater Flow (mgd)
Existing
Ten Year (2005)
Ultimate
Description
Ave
Max
Ave Max Ave
Max
Within City Limits
0.79
1.19
0.87 1.31 1.17
1.76
Basin 1
0.00
0.00
0.00 0.00 0.00
0.00
Basin 2
0.00
0.00
0.00 0.00 0.00
0.00
Basin 3
0.00
0.00
0.00 0.00 0.00
0.00
Basin 4
0.00
0.00
0.00 0.00 0.23
0.34
Basin 5
0.07
0.11
0,07 0.11 0.44
0.65
Basin 6
0.16
0.24
0.42 0.63 0.97
1.45
Basin 7
0.00
0.00
0.00 0.00 0.33
0.49
Basin 8
0.13
0.20
0.34 0.50 1.19
1.79
Totals
1.15
1.73
- 1.70 2.54 4.32
6.48
P^.EVANSMP\D0OTM9D0C
TM9-10
970563
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TM No. 10 Wastewater Collection System Evaluation
970563
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO. 10
To: City of Evans, Colorado
From: HDR Engineering, Inc.
Date: February 26, 1996
Revised June 12, 1996
Subject: Wastewater Collection System Evaluation
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Purpose of Memorandum
The purpose of this Technical Memorandum (TM) is to discuss results of the wastewater
collection system evaluation and recommendations for existing and future system improvements.
1.2 Description of Evaluation
The City of Evans wastewater collection system has been evaluated under three scenarios:
Existing conditions
Ten year growth conditions
Ultimate conditions
Wastewater flows estimated in TM 9 were used to develop a spreadsheet model for each
condition outlined above. An electronic copy of the model, a printout of each model, and a
description of how the model can be modified is included in Appendix 10-A.
2.0 WASTEWATER COLLECTION SYSTEM EVALUATION
2.1 General
The existing wastewater collection system has been modeled using a spreadsheet created in
Microsoft® Excel. Estimated maximum daily wastewater flow from contributing areas have
been assigned to design points, which represent the most likely location that wastewater flow
enters the system, identified along existing interceptors. These flows are accumulated at each
design point and carried to the next downstream design point where additional flows are added.
This provides a conservative estimate of the actual flow that is conveyed by each reach of
P \EVANS\IPNOC\TMI0DOC
TM 10-1
970563
interceptor and is justified by the relatively short wastewater travel time from each contributing
area.
The spreadsheet then analyses the capacity of each reach of pipe bounded by neighboring design
points using Mannings equation for gravity flow. The nominal diameter of each reach was
provided by the City and the slope of each reach was determined using manhole rim and invert
elevations collected at various locations in the field. The cumulative actual peak flow at each
design point is then divided by the calculated theoretical flow to estimate the percent capacity
utilized. If the capacity is 95 percent or greater, the spreadsheet displays the theoretical and
nominal new or replacement pipe size required.
2.2 Existing Wastewater Collection System
The existing wastewater collection system has two main interceptors which carry flow to the City
of Evans Wastewater Treatment Plant (WWTP). The north interceptor begins just east of 23rd
Avenue and runs east along 37th Street to the WWTP. Pipe diameters include 8 -inch, 10 -inch,
and 12 -inch. The south interceptor begins just east of 17th Avenue and runs east on 42nd Street
to Industrial Parkway where it turns south to 43rd Street, then east on 43rd Street to Brantner
Road. The interceptor then runs northeast on Brantner Road, heads east crossing US Highway
85 and the Union Pacific Railroad (UPRR), and continues east along 42nd Street to Central
Street. The pipeline then runs north on Central Street to 40th Street, east on 40th Street to
Pueblo Street, north on Pueblo Street to 37th Street, and east on 37th Street to the WWTP. Pipe
diameters include 12 -inch, 15 -inch, and 24 -inch.
'The existing wastewater collection system model was developed by dividing existing areas
according to landuse, calculating the estimated wastewater flow for each area, and assigning the
corresponding wastewater flow to the design point at which the flow is likely to enter the system.
Figure 10-1, shows the existing system layout and model information.
2.2.1 Existing Model Results. Based on the spreadsheet analysis described in Section 2.1
of this TM, the existing interceptors appear to have sufficient capacity. The reach
between design points 10 and 11, which is a 12 -inch segment of the north interceptor,
running east on 37th Street between Empire Street and the WWTP, has a calculated
capacity utilized of approximately 81 percent, indicating this segment is reaching the
limit of useful capacity. Useful capacity is defined as the point at which the ratio of
actual flow to theoretical full flow reaches approximately 95 percent.
2.2.2 Reported System Deficiencies. The City has expressed concerns regarding a
segment of the existing wastewater collection system crossing U.S. Highway No. 85 at
35th Street. The pipeline connecting City manholes numbered 209, 210, and 211 appears
to have a depressed section resulting in a standing sewerage. Four options have been
evaluated to alleviate the problem:
1) Reconstruct the segments of pipeline in question.
2) Route flow from City manhole number 211 to City manhole number 187.
P\EVANSMPVHKttM 10. DOC
TM 10-2
970563
3) Route flow from City manhole number 211 to City manhole number 178.
4) Use pipe bursting techniques to reconstruct the segment.
Option No. 1 requires replacement of approximately 300 LF of 8 -inch pipeline, 200 LF of
which will require construction of a bored crossing at U.S. Highway No. 85.
Construction of this option will be difficult as the replacement sections must follow lines
and grades of the original alignment requiring by-pass pumping. Table 10-1 presents
estimated planning phase costs to implement Option No. 1.
TABLE 10-1
Existing Wastewater Collection System Improvements
(HWY 85 at 35th Street)
Option No. 1- Estimated Costs
Description
Estimated Unit
Quantity Unit Cost
Total
Cost
Sanitary Sewer Pipeline:
8 inch PVC (in trench) 100 LF $27.00 $2,700.00
8 inch PVC (bored crossing) 200 LF $250.00 $50,000.00
By-pass Pumping 40 HR $30.00 $1,200.00
Connection to Existing System 4 EA $500.00 $2,000.00
Pavement Removal and Replacement 45 SY $40.00 $1,800.00
Remove Existing Pipe 300 LF $5.00 $1,500.00
Traffic Control 40 HR $25.00 $1,000.00
Mobilization 1 LS $2,000.00 $2,000.00
Subtotal $62,200
Contingency 15%
Engineering 10%
$9,330.00
S6,220.00
Planning Phase Estimated Construction Costs $77,750.00
Note: All costs are based on 1995 costs and an ENR index of 5518.70
Option No. 2 requires construction of approximately 2100 LF of 8 -inch sanitary sewer
pipeline between City manholes 211 and 184. This option will be somewhat easier to
construct than Option No. 1 although, it requires a significantly longer section of pipeline
which would be installed within existing pavement. Estimated planning phase costs for
Option No. 2 are presented in Table 10-2.
P-kE V ANSMPIDOCRM 10. DOC
TM10-4
970563
TABLE 10-2
Existing Wastewater Collection System Improvements
(HWY 85 at 35th Street)
Option No. 2 - Estimated Costs
Description
Estimated Unit
Quantity Unit Cost
Total
Cost
Sanitary Sewer Pipeline:
8 inch PVC 2100 LF $27.00 $56,700.00
Sanitary Sewer Manhole
0-10 feet deep 4 EA $2,500.00 $10,000.00
11-20 feet deep 3 EA $3,000.00 $9,000.00
Connection to Existing System 2 EA $500.00 $1,000.00
Pavement Removal and Replacement 900 SY $40.00 $36,000.00
Mobilization 1 LS $11,500.00 $11,500.00
Subtotal $124,200.00
Contingency 15% $18,630.00
Engineering 10% $12,420.00
Planning Phase Estimated Construction Costs $155,250.00
Note: All costs are based on 1995 costs and an ENR index of 5518.70
The third option investigated involves construction of approximately 2900 LF of 8 -inch
sanitary sewer pipeline between City manhole numbers 211 and 178. This option is
slightly longer than Option No. 2 and would also be installed entirely within paved areas
however, the available scope of Option No. 3 provides approximately 50 percent more
capacity than Option No. 2. Table 10-3 indicates planning phase estimated construction
costs.
P'\EVANSMPJ)OCITM I0,DOC
TM 10-5
970533
TABLE 10-3
Existing Wastewater Collection System Improvements
(HWY 85 at 35th Street)
Option No. 3 - Estimated Costs
Description
Estimated
Quantity Unit
Unit
Cost
Total
Cost
Sanitary Sewer Pipeline:
8 inch PVC
Sanitary Sewer Manhole
0-10 feet deep
11-20 feet deep
Connection to Existing System
Pavement Removal and Replacement
Mobilization
2900 LF
5
4
2
1280
1
EA
EA
EA
SY
LS
Subtotal
$27.00 $78,300.00
$2,500.00
$3,000.00
$500.00
$40.00
$15,700.00
Contingency 15%
Engineering 10%
Planning Phase Estimated Construction Costs
Note: All costs are based on 1995 costs and an ENR index of 5518.70
$12,500.00
$12,000.00
$1,000.00
$51,200.00
$15,700.00
$170,700.00
$25,605.00
$17,070.00
$213,375.00
Option No. 4 considers use of pipe bursting techniques to replace the section of pipeline
contained between City manhole numbers 209, 210, and 211. This method of pipe replacement
is a trenchless technology which involves pulling a mandrel and new pipe through the existing
pipeline. The mandrel has a slightly larger diameter than the pipe which it is being drawn
through which results in a "bursting" of the existing pipeline. The burst pipe is replaced with the
new pipe attached to the mandrel. This procedure works particularly well when the existing pipe
material is clay, as is the case here. Planning phase estimated costs are presented in Table 10-4.
TABLE 10-4
Existing Wastewater Collection System Improvements
(HWY 85 at 35th Street)
Option No. 4 - Estimated Costs
Description
Estimated Unit
Quantity Unit Cost
Total
Cost
Sanitary Sewer Pipeline:
8 inch HDPE
Connection to Existing
Mobilization
300
4
1
LF
EA
LS
Subtotal
$140.00
$500.00
$5,000.00
Contingency 15%
Engineering 10%
Planning Phase Estimated Construction Costs
$42,000.00
$2,000.00
$5,000.00
$49,000.00
$7,350.00
$-1,900.00
$61,250.00
P\E\'ANSMP\DOC TMI0.IIOC
TM 10-6
970563
2.3 2005 Wastewater Collection System
Additional wastewater flows, to be generated by projected growth over the next ten years
(1996-2005), were added to the existing model to examine the effects on existing interceptors.
Considering the percent capacity utilized calculated in the north interceptor, most of the 2005
wastewater flow was directed to the south interceptor. Only areas to be developed directly north
of the north interceptor were added to this pipeline. Table 10-5 outlines specific recommended
improvements necessary to convey projected 2005 wastewater flows.
2.3.1 2005 Model Results. Estimated wastewater flow contributions due to future growth
areas are indicated on the 2005 model printout in the appendix to this master plan.
Additional anticipated capacity for the north interceptor is estimated at 0.12 million
gallons per day (mgd). This increases the capacity utilized to approximately 91 percent
between design points 10 and 11 and approximately 87 percent between design points 9
and 10. Further increases in flow through these reaches will require interceptor
improvements such as installing larger diameter pipe, installing parallel pipe, cross
connection to the existing 24 -inch segment of the south interceptor, or slip -lining.
The remainder of estimated 2005 wastewater flows, approximately 0.29 mgd, were added
to the existing system at the west end of the south interceptor. With these additional
wastewater flows, the south interceptor has one reach between design points 21 and 22
with a utilized capacity of approximately 31 percent, indicating that the south interceptor
can easily handle additional wastewater flows projected for the current ten year (1996-
2005) growth areas.
TABLE 10-5
Recommended System Improvements
2005 Wastewater Collection System
Improvement
Implementation Years: 1996 - 2000
Gravity Interceptor 1320
Gravity Interceptor 2640
Length Diameter
(FT) (IN) Description
Gravity Interceptor
2640
12 East along 37th Street to 23rd Avenue.
12 South along 23rd Avenue between
37th Street and 42nd Street.
12 East along 42nd Street between 23rd
Avenue and 17th Avenue (connect to
existing south interceptor).
Table 10-6 outlines estimated planning phase costs for implementation of ten year
improvements in 1995 dollars.
P IEVANSAIPNOQTM I0,DOC
TM 10-7
9i70Ss3
TABLE 10-6
2005 Wastewater Collection System
Projected Costs
Description
Estimated Unit
Quantity Unit Cost
Total
Cost
Sanitary Sewer Pipeline:
12 inch PVC 6600 LF $35.00 $231,000.00
Sanitary Sewer Manhole
0 - 10 feet deep 5 EA $2,500.00 $12,500.00
11 - 20 feet deep 5 EA $3,000.00 $15,000.00
Connection to existing system 1 EA $1,500.00 $1,500.00
Pavement removal and replacement 4500 SY $40.00 $180,000.00
Mobilization 1 LS $65,000.00 $65,000.00
Subtotal $505,000.00
Contingency 15%
Engineering 10%
$75,750.00
$50,500.00
Planning Phase Estimated Construction Costs $631,250.00
Note: All costs are based on 1995 costs and an ENR index of 5518.70
2.4 Ultimate Wastewater Collection System
The ultimate wastewater collection system includes portions of the existing collection system,
segments added to accommodate the ten year (1996-2005) growth areas, and areas within the
urban growth boundary to be served by other than septic systems. The approach taken in
developing collection system alternatives was to provide gravity service to as much of the
planned growth area as possible. Consideration was also given to maintaining the option of
utilizing both the City of Evans WWTP and the Hill -n -Park WWTP.
After consideration of various gravity and combined gravity/pumped options, two alternatives for
wastewater collection warranted further evaluation. Alternative No. 1 combines a gravity
interceptor, pumping, and improvements to the existing system and Alternative No. 2 is a gravity
interceptor. Both alternatives take advantage of the naturally occurring drainage toward the
South Platte River. Each alternative is described in detail below.
2.4.1 Alternative No. 1. Alternative No. 1, shown in Figure 10-2, begins approximately
1.75 miles east of the western boundary of the urban growth area. The interceptor runs
east following the north edge of the planned open space area along the South Platte River
to just west of the Hill -n -Park WWTP. At this point, the interceptor generally follows the
Evans Ditch to the intersection of Industrial Parkway and 44th Street where it connects to
P k EVANSMPNDOCATAI IQ DOC
TM 10-8
970563
the existing collection system. This entire reach is capable of conveying projected
wastewater flows, approximately 3.80 mgd, by gravity from planned ultimate growth
areas. However, based on the fact that a portion of the interceptor parallels the Evans
Ditch, two sanitary sewer lift stations would be required to serve areas south and east of
the ditch.
Alternative No. 1 also includes improvements to the existing collection system due to
insufficient capacity to handle projected wastewater flows. Generally, all of the 15 -inch
diameter pipe making -up the south interceptor will require either replacement or a
parallel pipeline. Required improvements are outlined in Table 10-7.
TABLE 10-7
Alternative No. 1- Required Existing Wastewater Collection System Improvements
To Accommodate Ultimate Projected Flows
Improvement
Gravity Interceptor
Gravity Interceptor
Gravity Interceptor
Gravity Interceptor
Gravity Interceptor
Gravity Interceptor
Lengt
h (FT)
Existing
Diameter
(IN)
Calculated
Proposed
Replacement
Diameter
(IN)
Description
Along 43rd Street to Brantner Road and US Highway 85.
Brantner Road and US Highway 85 to 42nd Street and
Central Avenue.
42nd Street and Central Avenue to 40th Street and
Golden Avenue.
40th Street and Golden Avenue to 37th Street and Pueblo
Avenue.
37th Street and Pueblo Avenue to just west of the City of
Evans WWTP.
Replace existing gravity interceptor.
1000
1500
1900
2300
400
750
15 24
15 24
15 24
15 24
I5 *20
15 *20
*Greater available slope allows for smaller diameter
Table 10-8 outlines estimated planning phase costs for implementation of Alternative No.
1 based in 1995 dollars.
2.4.2 Alternative No. 2. Alternative No. 2, shown in Figure 10-2, begins approximately
1.75 miles east of the western boundary of the urban growth area. The interceptor runs
east following the north edge of the planned open space area along the South Platte River
to a point just south of the intersection of 17th Avenue and Brantner Road. The proposed
alignment then follows the city limit line to the northeast paralleling Brantner Road to a
point just south of 44th Street. The interceptor then runs east crossing US Highway 85
and the UPRR tracks to a point just north of the city limit line where it turns northeast
prior to turning north to the WWTP.
A definite advantage to Alternative No. 2 is the fact that pumping is not required to serve
the southern most areas of development. Initial construction of the interceptor would be
somewhat more difficult than Alternative No. 1 due to greater length and the crossings of
P'\EVANs]1%DOQTMI0.DOC
TM 10-9
970563
US Highway 85 and the UPRR track, both requiring permitting, agency review, and
boring.
Table 10-9 outlines estimated planning phase costs for implementation of Alternative No.
2 based on 1995 dollars.
TABLE 10-8
Ultimate Wastewater Collection System
Alternative No. I - Estimated Costs
Description
Estimated
Quantity
Unit
Unit
Cost
Total
Cost
Alternative No. 1
Sanitary Sewer Pipeline:
12 inch PVC 3000 LF $35.00 $105,000.00
15 inch PVC 3900 LF $50.00 $195,000.00
20 inch PVC 3950 LF $65.00 $256,750.00
24 inch PVC 9900 LF $75.00 $742,500.00
27 inch PVC 6400 LF $80.00 $512,000.00
Sanitary Sewer Manhole
0 - 10 feet deep 20 EA $2,500.00 $50,000.00
11 - 20 feet deep 20 EA $3,000.00 $60,000.00
Sanitary Lift Station 2 LS $20,000.00 $40,000.00
Sanitary Force Main
6 inch PVC 7000 LF $25.00 $175,000.00
Connection to existing system I EA $1,500.00 $1,500.00
Pavement removal and replacement 14000 SY $40.00 $560,000.00
Mobilization 1 LS $150,000.00 $150,000.00
Subtotal $2,847,750.00
Contingency 15% $427,162.50
Engineering 10% $284,775.00
Planning Phase Estimated Construction Costs $3,559,687.50
Note: All costs are based on 1995 costs and an ENR index of 5518.70
P ,EVANSMPWOC TMIO. DOC
TM 10-10
970563
TABLE 10-9
Ultimate Wastewater Collection System
Alternative No. 2 - Estimated Costs
Description
Estimated Unit Total
Quantity Unit Cost Cost
Alternative No. 2
Sanitary Sewer Pipeline:
12 inch PVC
15 inch PVC
20 inch PVC
24 inch PVC
27 inch PVC
Sanitary Sewer Manhole
0 - 10 feet deep
11 - 20 feet deep
Connection to existing system
Pavement removal and replacement
Bored Crossings
US Highway 85
Railroad
Mobilization
3000 LF
3900 LF
3000 . LF
4100 LF
15500 LF
$35.00
$50.00
$65.00
$75.00
$80.00
$105,000.00
$195,000.00
$195,000.00
$307,500.00
$1,240,000.00
30 EA $2,500.00 $75,000.00
30 EA $3,000.00 $90,000.00
1 EA $1,500.00 $1,500.00
5000 SY $40.00 $200,000.00
300 LF $400.00 $120,000.00
200 LF $ 400.00 $80,000.00
1 LS
Subtotal
$150,000.00
$150,000.00
$2,759,000.00
Contingency 15% $413,850.00
Engineering 10% $275,900.00
Planning Phase Estimated Construction Costs $3,448,750.00
Note: All costs are based on 1995 costs and an ENR index of 5518.70
3.0 CONCLUSIONS
3.1 Existing Wastewater Collection System
The existing wastewater collection system has two main interceptors which convey flow to the
City of Evans WWTP. The north interceptor, as defined in Section 2.2 of this TM, is currently
approaching its capacity in various reaches and adding flow beyond projected ten year
(1996-2005) growth projections is not recommended.
The south interceptor, also defined in Section 2.2 of this TM, currently has a majority of its
usable capacity available. This interceptor has the capability of conveying approximately 1.06
mgd and is currently carrying approximately 0.035 mgd, leaving an estimated 1.025 mgd of
available capacity.
The wastewater collection system is experiencing surcharge problems at the approximate
intersection of 35th Street and U.S. Highway No. 85 which require immediate attention.
P \EVANSMP\DOCUTMIO.DOC
TM 10-11
9'705'33
3.2 2005 Wastewater Collection System
Improvements to the existing wastewater collection system to convey estimated 2005 wastewater
flows are defined in Section 2.3 of this TM. The objective of these improvements is to carry
wastewater flows to the existing south interceptor with the exception of a small portion of the
projected flows expected to be generated north of the north interceptor. The south interceptor
has sufficient capacity to carry the projected ten year (1996-2005) wastewater flows of 0.29 mgd
anticipated to be routed to the south interceptor.
3.3 Ultimate Wastewater Collection System.
Alternatives for the ultimate wastewater collection system have been conceived with the
intention of taking advantage of gravity drainage within the proposed urban growth boundary.
Each drainage basin, as defined in TM No. 9, Wastewater Flows, will naturally drain toward the
South Platte River. Therefore, Alternatives No. 1 and No. 2 each have an interceptor which runs
generally west to east along the southern portion of the urban growth area.
4.0 RECOMMENDATIONS
4.1 Existing Wastewater Collection System
The recommendation for existing wastewater collection system improvements is based on
providing the City with a long-term, dependable solution to the depressed pipe segment at the
31st Street crossing of U.S. Highway No. 85. Option No. 4, is recommended for implementation
for the following reasons:
Least expensive option.
Rehabilitation is accomplished without excavation.
Does not require pavement removal and replacement.
One drawback to Option No. 4 is that neither the horizontal nor the vertical alignment can be
significantly altered. Depressions greater than 1 to 2 inches may be improved although, greater
variations in alignment will not be remedied. In the event that Option No. 4 cannot be
implemented, Option No. 1 should be considered due to nominal estimated cost.
4.2 2005 Wastewater Collection System
The recommendation for 2005 wastewater collection system improvements is based on an effort
to utilize available capacity in the City's existing south interceptor. It is recommended that flows
from areas developing west of the existing service area be directed to the south interceptor to
avoid exceeding capacity of the north interceptor.
P \EV'ANSMP\DOC\TMIQDOC
TM 10-12
970563
4.3 Ultimate Wastewater Collection System
The recommendation for the ultimate wastewater collection system is based on the following
criteria:
Meeting projected wastewater collection needs
Initial construction costs
Operation and maintenance costs
Both alternatives discussed will serve wastewater collection needs within the proposed urban
growth area and based on planning phase estimated construction costs, each is financially
comparable to the other.
The notable difference between the ultimate wastewater collection system alternatives evaluated
is the operation and maintenance (O&M) costs. Obviously, O&M costs will be somewhat higher
for a collection system with lift stations, even though the stations will be relatively low capacity
and most likely low maintenance facilities. Gravity systems do require routine maintenance to
assure optimal performance, although O&M costs are nominal. Taking into account the factors
listed above, it is recommended that the City of Evans consider likely growth areas as
development continues and implement the alternative which best serves growth.
P'\EVANSMKDOOTM IO.000
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970563
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TM No. 11 Wastewater Treatment Evaluation
970563
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO. 11
To: City of Evans, Colorado
From: HDR Engineering, Inc.
Date: March 7, 1996
Revised June 12, 1996
Subject: Wastewater Treatment Evaluation
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Purpose of Memorandum
The purpose of this Technical Memorandum (TM) is to examine existing wastewater facility's
ability to meet current and future wastewater flows and regulatory requirements for the
previously described urban growth area (UGA). Based on this analysis, long term and ultimate
development plant improvements will be identified and recommended to meet immediate as well
as long-term needs.
1.2 Background
The UGA identified in TM No. 2 contains two separate aerated lagoon type wastewater treatment
facilities along with individual septic systems. One of the aerated lagoon facilities is operated by
the City of Evans and the second is owned and operated by the Hill -N -Park subdivision
developer. This TM examines both facilities and considers the potential for the City of Evans to
eventually take over and operate the Hill -N -Park plant
1.3 Service Area
The existing and future service area for the City of Evans is described and shown in TM No. 2.
The future service area, extending as far west as 77th Avenue, will contain some areas of land
use requiring wastewater collection and treatment, while other areas will have individual
treatment units. Options for collection and conveyance were discussed in TM No. 10. The
feasibility of providing collection and conveyance systems to the west is related to the potential
for expansion or re -rating plant capacity and permit requirements of both the Evans WWTP and
the Hill -N -Park WWTP.
P'E VANSMPIDOC\TM I I.DOC
TM11-1
970563
2.0 EXISTING WASTEWATER FACILITIES
2.1 Evans WWTP
The Evans WWTP is located in northeast Evans at the corner of 37th Street and 1st Avenue as
shown in Figure 10-2. The plant has a rated annual average day capacity of 0.9 mgd. The
WWTP was built in 1961 as a two -cell aerated lagoon and later modified by breaking up the
south lagoon into an aerated lagoon and rock filter. Disinfection using chlorine gas was
subsequently added and dechlorination using sulfur dioxide was added in 1985. See Figure 11-1
for relative location of the treatment units.
2.1.1 Preliminary Treatment/Pumping - Wastewater flows by gravity via a 24 -inch
interceptor into the wetwell of the Influent Pump Station located in the southwest corner
of the WWTP site. Three non -clog single stage centrifugal pumps are located in a dry
well adjacent to the wetwell and pump the wastewater normally to Cell No. I. The flow
is measured by an ultrasonic doppler meter located on the discharge header just north of
the Influent Lift Station. The 20 Hp pumps each have a capacity of 1,100 gpm at 47 feet
of total dynamic head (TDH). The firm capacity of the pump station is unknown, but will
be less than 2,200 gpm and the total capacity with all three pumps running will be less
than 3,300 gpm. No testing has been done to determine actual pump capacities. The
pumps control system is designed to turn pumps on and off in sequence based on level in
the wet well determined by a float control system. The pumps are approximately 20
years old.
The wet well has a volume of approximately 6,500 gallons which by itself results in a
pump cycle time of about 6 minutes. However, the wastewater tends to back up into the
incoming interceptor at the high wet well level resulting in an increased pump cycle time.
The high level in the wet well is low enough though to prevent wastewater backup in to
nearby homes and businesses.
No screenings, grit removal, or primary clarification is provided, however, no significant
accumulation of grit, rags or other screenable material has been observed in the lagoons
or on the aeration equipment. In the past, sludge has accumulated near the influent pipe
to Cell No. 1 but has recently been removed.
The main concerns with the Influent Lift Station include: the small wetwell, surcharging
the influent sewer, the age of the pumps, and the lack of a screening and grit removal.
2.1.2 Aerated Lagoons - The aerated lagoons consist of two cells. Wastewater from the
Influent Pump Station is normally pumped to the center of Cell No. 1 (it can also be
pumped to the center of Cell No. 2). Cell No. 1 is a complete mix type system with
mixing and oxygen transfer provided by aerators. From Cell No. 1 the flow goes by
gravity to Cell No. 2. Cell No. 2 is partially mixed with a quiescent zone near the
effluent pipes. One effluent pipe goes to the Chlorine. Contact Chamber and a second
effluent pipe goes to the Rock Filter. See Figure 11-2 for a process schematic.
P.\EVANSMP\DOC \TM I .DOC
TM11-2
970563
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VALVE NO. 7
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CHLORINATION BUILDING
CHLORINE CONTACT
CHAMBER
FLOW MONITORING
BUILDING AND
DECHLORINATION
BUILDING
City of Evans, Colorado
Water/Wastewater Master Plan
EXISTING CITY OF EVANS
WWTP SITE PLAN
Figure 11-1
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970563
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Water/Wastewater Master
EXISTING CITY OF EVANS
WWTP PROCESS SCHEMATIC
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Cell No. 1 covers 6.64 acres at a normal operating depth of six ft resulting in a volume of
12.3 million gallons. Cell No. 2 covers 4.57 acres with a normal operating depth of six ft
and a volume of 8.25 million gallons. The lagoons have a 1:3 side slope and are lined
with asphalt. Currently, Cell No. 1 has four 15 Hp aerators each with a design capacity of
transferring 16 pounds of oxygen per hour at standard conditions. Cell No. 2 has one
aerator also with a design capacity of transferring 16 pounds of oxygen per hour. The
plant personnel have had substantial problems in keeping the aerators operating. As a
result the City has purchased 10 aspirating units each with a combined oxygen transfer
capacity of 1.9 pounds per hp -hr or 19.0 pounds of oxygen per hour. The aerators that are
still operational from Cell No. 1 will then be available for use in Cell No. 2.
The lagoons have been adequate for carbonaceous BOD removal when the aerators are
consistently operating. Some of the problems that have been experienced include: a
build up of sludge at the influent pipe and as mentioned before, mechanical problems
with the aging aerators.
2.1.3 Rock Filter - Influent flow to the Rock Filter enters at the northwest corner into a
unmixed zone of approximately two-thirds the volume of the basin. From this zone the
flow moves through the rocks and into another unmixed zone making up the remaining
portion of the filter basin. The band of rock making up the filter is about twenty feet
wide and contains 1 1/2" to 2" rock. The design loading for the filters is three
gallons/cubic foot/day.
The overall basin size is about 0.79 acres with an operating depth ahead of the filter of
about seven ft. The filter basin is also asphalt lined and has side slopes of 1:3. The
discharge of the rock filter basin goes to the Chlorine Contact Basin.
The Rock Filter is currently only used for emergency service at times of high suspended
solids. Past experience with the filter has shown anaerobic conditions and high odor
problems associated with the initial layers of the filter plugging with solids.
2.1.4 Disinfection/Dechlorination - Effluent from Cell No. 2 or the Rock Filter flows
through the serpentine type Chlorine Contact Chamber. The contact chamber has a
operating volume of about 33,000 gallons resulting in a contact time of approximately 53
minutes at the 0.9 mgd design flow. Chlorine is added at the head of the chamber
through a diffuser system. The chlorine is drawn through a chlorinator by an ejector.
The chlorinator is manually controlled. The chlorine supply is stored in 150 pound
cylinders. The cylinders, chlorinator, ejector, and booster pump are located in a small
building east of the Rock Filter. The chlorinator has a capacity of 100 pounds per day.
The effluent of the Chlorine Contact Chamber is dechlorinated with sulfur dioxide. The
sulfur dioxide is also drawn through a sulfonator using a ejector. The sulfur dioxide is
stored in 150 pound cylinders. The cylinders, sulfonator, ejector and booster pump are
PE V AN$AIPIIJO(lTM I I. DOC
TM11-3
970563
located in a separate room in a small building also located east of the Rock Filter. The
sulfonator also has a capacity of 100 pounds per day.
No significant problems have been noted to date associated with the contact chamber, the
chlorine feed system or the dechlorination system. Sludge buildup has been noted in the
contact chamber. However, there has been some concern about the safety issues in
regards to the storage and handling of the chlorine and sulfur dioxide.
2.1.5 Outfall - From the Chlorine Contact Chamber flow goes through a Parshall flume
located in a room adjacent to the dechlorination room. The Parshall flume has a six-inch
throat. After the flume, effluent flows through an eight -inch pipe to a diversion structure
located south of the Rock Filter. From the diversion structure flow goes through a 24 -
inch pipe, east to the South Platte River. The pipe is PVC except for the undercrossing at
First Avenue where the material is ductile iron.
The 24 -inch outfall was recently constructed in 1993. The only problems related to the
outfall is at extremely high water levels (as experienced in the summer of 1995) in the
South Platte, the river backs up into the outfall and effluent cannot discharge from the
plant through the 24 -inch line.
2.1.6 Miscellaneous - The 1993 update of Area wide Water Quality Management Plan
for the North Front Range Water Quality Planning Association includes the Evans
WWTP. The estimated 5 -year construction needs listed in the update were obtained from
the "Evaluation of Wastewater Treatment Facilities and Related Investigations"
completed by Rocky Mountain Consultants in March 1993. The construction
improvements listed include:
• Continue monitoring collection system to identify infiltration problems and
repair/replace lines as funds allow.
• Replace the effluent discharge line to the South Platte.
• Remove accumulated sludge from the lagoons.
• Install baffles to increase the treatment capacity to 1.17 mgd.
• Install a new influent measuring device.
The infiltration problems are continuing to be looked at including this study, the
discharge line has been replaced, and sludge has been removed from the lagoons. The
addition of the baffles has not been done nor has the influent measuring device been
changed. The addition of baffles in itself will not increase capacity. Other things would
need to be considered such as adequate oxygen transfer. Also, an increased capacity
would have to be justified to the Colorado Department of Public Health and Environment
and receive their approval. Current and future improvements will be discussed later in
the TM.
PAEVANSMPNOC TMI I: OOC
TMI1-4
970563
2.2 Hill -N -Park WWTP
The Hill -N -Park WWTP is located southeast of the intersection of County Roads 35 and 52 and
is shown in Figure 10-2. The service area for the plant includes the Hill -N -Park, Country
Estates, and Carriage Estate developments. The plant has a rated average day capacity of 0.336
mgd and was originally constructed as stabilization ponds with aeration and chlorination added
in 1975.
2.2.1 Aerated Lagoon - Flow enters the plant by gravity into a distribution box located
between the aerated lagoon and the stilling pond. The flow is measured in the
distribution box using a V -notch weir and a level recorder. The wastewater goes from the
distribution box to the aerated lagoon (the western of the two ponds) entering near the
west aerator. The lagoon covers approximately 3.5 acres with an operating depth of
about 10.0 ft., resulting in a volume of 1,525,000 gallons. The lagoon has two 15 Hp
aerators, it is not known whether the lagoons are lined or not.
Several problems have been realized by the plant operator including:
• Influent flow meter needs to be replaced.
• Aerators have never been serviced.
• There is a sludge build up in the west lagoon that needs to be removed.
• The influent line to the west lagoon regularly plugs most likely due to the sludge.
• Seepage has been noted to be occurring on the south side.
2.2.2 Stilling Lagoon - The flow from the aerated lagoon normally overflows into the
distribution box from which it goes to the center of the Stilling Lagoon. The purpose of
the stilling lagoon is to allow settling of solids and prevent carryover to the discharge.
The lagoon has a surface area of about 2.34 acres, an operating depth of 5.0 ft, and a
volume of 510,000 gallons. Beginning in August and continuing into October the lagoons
experience a severe duck weed problem especially east of the inlet. The weed plugs lines
weekly and fills the distribution box which has to be cleaned out daily.
2.2.3 Disinfection/Outfall - Flow from the outlet structure on the west end of the
Stilling Lagoon goes south to the Chlorine Contact Chamber. The chamber has a
serpentine flow directed by wood baffles with an overflow pipe at the end feeding a 10 -
inch line that connects into the 8 -inch outfall pipe which goes to an unnamed ditch, then
to Ashcroft Draw which is a tributary to the South Platte River.
The Chlorine Contact Chamber volume is about 7,400 gallons resulting in a contact time
of about 32 minutes at design flow. A chlorinator, scale, and 150 pound cylinders are
located at small building adjacent to the contact chamber. Chlorine is added by a diffuser
in the influent pipe ahead of the contact basin. Flow is measured using a float in a stand
pipe and an associated level controller.
PAE VANSM%DOQTM I I.D0C
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The previously mentioned duck weed problem is extremely bad at the contact chamber
with a regularly occurring build up on the surface which has to be cleaned out daily.
2.2.4 Miscellaneous - The 208 Facility Plan mentioned above also recognizes the Hill -
N -Park treatment system, but list no 5 -year construction needs. In the previously
mentioned study by Rocky Mountain Consultants it was stated that the facility was
located in the flood plain. However, the treatment plant is bermed up around the lagoons
and the chlorine facilities allowing the plant to be above the 100 -year flood plain.
Whether or not the facilities are actually above the flood plain needs verification.
3.0 PERMIT REQUIREMENTS
3.1 Existing Permit Requirements
3.1.1 Evans - The current Evans Discharge permit was issued in August 1994 and
expires in September 1999. The following summarizes the effluent limitations:
Parameter
Flow, mgd
BOD5, mg/L (lb/d)
TSS, mg/L (lb/d)
Fecal Coliform, #/100 ml
Total Residual
Chlorine, mg/L
Limit
0.9, (30 day average)
30/45 (225/338), (30 day average/7 day average)
75/110 (563/826), (30 day average/7 day average)
2000/4000, (30 day geometric mean/7 day
geometric mean)
0.37, (daily maximum)
0.21, (30 day)
pH 6.5-9.0, (minimum -maximum)
Oil and Grease, mg/L 10, (daily maximum)
The permit also required the City to perform weekly pH and temperature monitoring of
the effluent and of the South Platte River at a location above the discharge. These were
used to run models for determining ammonia limitations which, if necessary, would be
assigned in the next permit. The results of the model will be discussed later.
3.1.2 Hill -N -Park - The Hill -N -Park current permit was issued in May 1994 and will
expire on April 30, 1999. The permit lists the following effluent limitations:
PIEVANSMP\DOC\TM I I,DOC
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Parametcr
Flow, mgd
BOD5, mg/L (lb/d)
TSS, mg/L (lb/d)
Fecal Coliform, #1100 ml
Limit
0.336, (30 day average)
30/45 (225/338), (30 day average/7 day average)
75/110 (563/826), (30 day average/7 day average)
2000/4000, (30 day geometric mean/7 day
geometric mean)
Total Residual 0.5, (daily maximum)
Chlorine, mg/L
pH
Oil and Grease, mg/L
3.2 Future Permit Requirements
6.5-9.0, (minimum -maximum)
10, (daily maximum)
3.2.1 Evans - The Colorado Department of Public Health and Environment (CDPHE)
used the South Platte River pH, temperature, and ammonia data collected and reported by
the City, to run the Colorado Ammonia Model. The model determines, by month,
maximum allowable ammonia concentrations permitted in the plant effluent such that
there would be no significant impact on the river. The model was run for flows of 1.2
mgd and 1.4 mgd. The monthly ammonia limitation results for each flow, are shown
below.
1.2 mgd Flow
Chronic Effluent
Total Ammonia
Month (mg/L)
1.4 mgd Flow
Chronic Effluent
Total Ammonia
(mg/L)
Jan 161.4
Feb 194.8
Mar 104.6
Apr 114.8
May 178.5
Jun 102.0
Jul 62.5
Aug 67.2
Sep 58.1
Oct 71.2
Nov 108.5
Dec 253.5
P'\ EVANSIIPNOQTM I I,DOC
TM11-7
145.7
177.8
95.1
101.8
156.0
89.5
54.3
58.2
52.2
61.7
94.9
228.7
970563
As a result of the above modeled limits, CDPHE stated in a letter to HDR, that "...there
will not be any ammonia limitations required if the City decides to expand the current
facility to either of the proposed capacities." As potential plant capacities get higher than
the 1.4 mgd value, the allowable limits will decrease significantly. Roughly, when doing
a straight line proportion on the critical July month, the plant capacity would be around
2.4 mgd before the ammonia limit starts to get below 30 mg/L. Thirty mg/L is the
highest recorded effluent ammonia nitrogen value indicated in the discharge monitoring
reports.
3.2.2 Hill -N -Park - There are no indications that the Hill -N -Park permit will change
significantly when it is renewed in 1999. The modeling for the Evans facility would also
indicate that there is little chance of ammonia limits being assigned to Hill -N -Park since
it has a substantially lower flow.
4.0 WASTEWATER FLOWS AND PLANT CAPACITIES
4.1 Existing Flow
4.1.1 Evans - Figures 11-3, 11-4, and 11-5 show the Evans WWTP monthly effluent
flows, influent and effluent BOD5 and influent and effluent TSS values for about the last
four years. As can be seen in the figures the plant has consistently met the TSS limits
described above. The BOD5 effluent values occasionally exceed the 30 mg/L limit.
However, this can generally be related to poor aerator performance. The flow is
beginning to approach the design capacity of 0.9 mgd. The current average day effluent
flow is approximately 0.79 mgd with peak months occasionally exceeding the 0.9 mgd
30 -day average. The effluent values have been used for evaluation because of the
unreliability of the influent meter.
The 0.79 mgd flow is 88% of the design capacity. Language spelled out in the discharge
permit requires ignition of engineering and financial planning for expansion at 80% of the
design capacity. Once 95% of the design capacity is reached, the permittee must
commence construction of proposed facilities.
Although strictly speaking the plant has already reached the design capacity based on the
30 -day average and not the annual average, the CDPHE historically has paid more
attention to the annual average flow, especially when the plant is meeting the other
criteria of the permit. However, recently the CDPHE indicated they are going to pay
closer attention to the months average day flow as compared to the permits design
average day.
Except for unusually high values at the end of 1994 and beginning of 1995 the influent
carbonaceous values have been averaging 177 mg/L. This number appears to be adequate
as a concentration at all flows and could therefore be used for future design values at
higher flows.
P',EV.ANSMP\DOCITM I I.DOC
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Total suspended solids values are similarly consistent with representative average
concentration being 172 mg/L.
4.1.2 Hill -N -Park - Figures 11-6, 11-7, and 11-8 show the Hill -N -Park monthly effluent
flows, influent and effluent BOD5, influent and effluent TSS values about the last four
years. As indicated, Hill -N -Park consistently meets the BOD5 and TSS limits. Its
annual average flow is about 0.26 mgd which is 77% of its design flow of 0.336 mgd.
Influent carbonaceous BOD5 and TSS values have averaged 210 and 198 mg/L
respectively.
4.2 Future Flows
4.2.1 Long Term - The future flows to both the Evans and the Hill -N -Park plants are
directly related to the overall recommendations for collection and treatment in the UGA.
Flow increases over the next ten years are identified in TM No. 9 and occur in Basins 6
and 8 as well as within the Evans City Limits. Currently the flow from Basins 5, 6 and a
small portion of 8 go to the Hill -N -Park WWTP. The rest of the flows from Basin 8 and
within the City limits go to the Evans WWTP.
4.2.2 Ultimate - Ultimate flows for the UGA will be from all the basins except Basins
1, 2, and 3, which will utilize individual treatment systems. The ultimate flow that must
be treated is estimated from TM No. 9 to be 4.3 mgd annual average.
5.0 TREATMENT OPTIONS
5.1 General
Since ammonia limits will not be instituted on the new discharge permit and there are no major
concerns with the existing plant, a new plant option will not be considered. Treatment options
considered include: treating additional flow at the Evans WWTP, treating additional flow at the
Hill -N -Park WWTP, sending all or some of the flows to the City of Greeley, and combinations
of all three.
5.2 Ten Year Requirements
For the next ten year period recommendations are based on the Hill -N -Park plant being able to
treat the flows from the Hill -N -Park development which is in Basins 5 and 6. The remaining
flows in the UGA and the City are projected to be about 1.1 mgd.
5.2.1 Increase Capacity of Evans WWTP - The most logical and simplest method to
handle the need for additional capacity is to re -rate the Evans WWTP. Brief discussions
with the CDPHE indicate that they are acceptable to the plant being re -rated as discussed
in the 1993 plant evaluation. A 30% increase in capacity was suggested, resulting in a
design capacity of 1.17 mgd. This would cover the 1.1 mgd estimated flow. A new
P \EVANSMPNOCUM I I,DOC
TM11-9
970563
design study would then be required at 0.94 (80% of capacity) mgd and construction at
1.1 mgd.
The re -rating process with the CDPHE requires a new Site Application. As part of the
Site Application, a design report is required to show that the plant is capable of handling
the higher flows. The site application and new permit could potentially need to have
design flow rates that are maximum month values instead of annual average flow.
5.2.2 Send flow so Greeley - A second option is to send all or some of the flow to the
Greeley WWTP. This would require about a 1400 -foot long 15 -inch diameter gravity
connection from the Evans WWTP to the existing Greeley interceptor. Greeley would
require a continuous base flow and would possibly require capital improvements to their
facilities to accommodate the flow.
5.3 Ultimate Development
Several treatment options can be considered to treat the estimated 4.3 mgd annual average flow
for the UGA. The most feasible options are to:
Option 1 - Expand the Evans WWTP, take over operation and expand the Hill -N -Park
W WTP.
Option 2 - Expand only the Evans WWTP.
Option 3 - Leave the Evans and Hill -N -Park WWTPs at there current capacity and send a
base flow to Greeley.
Option 4 - Operate and expand the Hill -N -Park WWTP for flows in Basins 4 through 7.
Send remaining flows to Greeley from Basin 8 and the flow to the existing Evans WWTP.
Option 5 - Deliver all flows in the UGA to Greeley.
Key concerns regarding the above options include:
• As the treatment facilities are expanded, the likelihood of ammonia limits being imposed
becomes more likely.
• If ammonia limits are imposed, the aerated lagoon systems may need to become
mechanical plants to provide adequate treatment.
• Operation and expansion of the Hill -N -Park WWTP would require plant upgrades and
additional land area.
• Delivering a base flow to Greeley would result in a variable flow at the other treatment
plants.
• Contractual requirements and future costs of treatment by Greeley are unknown at this
time.
A present worth analysis was conducted to compare the above options for treatment to serve the
future growth area. Annual O&M costs and capital costs of treatment and conveyance were
PIE V ANSMPIDOCITM 11. DOC
TM11-10
970$£3
compared for a project life of 30 years and a real discount rate (interest rate minus inflation) of
3.5 percent. The analysis calculations are included in Appendix 11 B.
Based on the analysis, the lowest long-term cost is Option 1 to expand the Evans WWTP and
eventually operate and expand the Hill -n -Park WWTP to treat all flows in the future UGA.
Expansion of Hill -n -Park is dependent upon obtaining additional land and upgrading the existing
facilities. If additional land is not available or an agreement cannot be reached to operate the
plant, then the next lowest cost option would be to expand Evans WWTP to handle all flows with
a new interceptor constructed to deliver flows from the Hill -n -Park facility and future growth
area.
The cost analysis indicated that facility expansion costs would have to exceed approximately
$4,000,000 before the option to send all flows to Greeley becomes cost effective. On -going
discussions with Greeley are recommended, however, regarding the possibility of Greeley
eventually treating Evans' wastewater flows.
6.0 EVANS WWTP IMPROVEMENTS
6.1 Plant Re -Rating
The main requirement for getting the plant re -rated will be to provide a more efficient aeration
system The City has purchased ten new aspirating units which will provide increased aeration
capacity and more reliability. Also the flow regime might need to be altered to provide a plug
flow system which is more efficient than a complete mix system. In plug flow, the wastewater is
routed through a series of baffles in the lagoon instead of being immediately mixed throughout
the entire basin. This may require some minor piping changes and baffles.
The disinfection system and plant hydraulics will need to be analyzed to make sure they are
sufficient for the higher flows. These types of plant reviews will be necessary as part of the Site
Application process.
6.2 Headworks
Small wetwell capacity, poor accessibility, and no screening provisions are the major concern
with the existing influent pump station. Therefore it is recommended to replace the existing
pump station with a new headworks and influent pump station. The new facility might be
located northwest of the existing lagoon Cell No. 1. The headworks would include a mechanical
bar screen and relocation of the existing emergency generator. Some possible options that could
be included in the headworks would be grit removal and screenings dewatering. The costs in TM
No. 12 however, only include estimates for a new pump station and a mechanical screen. The
existing lift station and headworks building should remain for potential future use as a chemical
feed station or storage. All of the headworks improvements could be implemented without
shutting down the plant during construction.
P,EVANSMPVJOQTM I I DOC
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6.3 Disinfection
The current disinfection system utilizes chlorine gas/solution. The system is currently operating
satisfactorily and can be easily modified to meet increase flows. Any improvements to the
disinfection system would be based on either increasing safety or reducing operating costs or
both. Chlorine is an extremely dangerous chemical even at low concentrations. The following
evaluates different potential disinfection systems.
6.3.1 Chlorine - Chlorine has the cheapest operating costs in terms of chemical costs
and energy costs. However, it is the most dangerous. One solution to increasing the
safety aspect is to install a chlorine scrubber. A chlorine scrubber automatically starts up
on the detection of chlorine gas. The scrubber draws the chlorine gas into the enclosure
where it reacts with caustic soda to neutralize the chlorine gas. A scrubber for a system
utilizing 150 pound cylinders costs approximately $35,000-$40,000 for the equipment
only.
A chlorine scrubber is not mandatory. HDR's general practice is to install scrubbers
when there is modifications to any of the chlorine facilities. The ultimate decision on the
requirement for a scrubber in existing facilities belongs to the Fire Marshall. Discussions
with the Evans Fire Marshall, is that a scrubber is not currently necessary.
6.3.2 Sodium Hypochlorite - Sodium Hypochlorite is a liquid that is normally fed with
chemical metering pumps into a water stream. Sodium Hypochlorite also is a dangerous
chemical from contact but not from a breathing standpoint. For hypochlorite, chemical
metering pumps and a bulk storage tank would be required. These additional capital
costs and the higher chemical cost result in an advantage to chlorine only in terms of
increased safety.
6.3.3 Ultraviolet Light - Ultraviolet light (UV) is the safest of the disinfection options.
Another advantage is that UV does not require dechlorination. The UV destroys the
anatomy of the microorganisms to provide a kill or disinfection. Normally UV is used in
water streams where the suspended solids is less than 10 mg/L. The more solids in the
stream the more banks•of UV lights that are required. A UV system is designed based on
the instantaneous peak flow.
Looking at plant peak flows and adding 25 percent additional light banks for higher
suspended solids, results in capital and construction costs of about $300,000 and annual
power costs of $30,000. These are large amounts of money that are needed to eliminate
the small risk potential associated with chlorine and the abandonment of the
dechlorination system.
6.3.4 Ozone - Ozone is a relatively new type of disinfection for wastewater, however it
also has the advantage of not needing the dechlorination. Ozone can be delivered to the
plant or as some plants do, generate their own ozone. In either case it is quite costly.
P1EV.ANSMP\DOC\TM I I, DOC
TM11-12
970563
6.4 Dechlorination
6.4.1 Sulfur Dioxide - The plant currently uses sulfur dioxide to dechlorinate the
effluent of the chlorine contact basin. As with chlorine, sulfur dioxide is a dangerous gas.
Again, a scrubber can be used to remove the gas in the event of a gas leak and in some
instances the same scrubber is used for both chlorine and sulfur dioxide. The system is
currently operating adequately and is fully capable of being expanded.
6.4.2 Sodium Bisulfate - Sodium bisulfate is a liquid and normally fed using chemical
metering pumps. The chemical price is higher than sulfur dioxide, however it is more
safe to handle and be around. Capital costs include a bulk storage tank and chemical
metering pumps.
6.5 Recommendations
Recommendations concerning improvements to the Evans WWTP include:
• Installation of new aspirating equipment
• A new combined influent pump station and headworks
• Develop and submit a Site Application to the CDPHE to re -rate the plant to 1.17 mgd.
• Modify process flow to obtain a plug flow system.
• Leave disinfection system as is, unless future modifications occur. At which time a
scrubber could be added. Another trigger point would be a change in philosophy in terms
of the Fire Marshall requiring installation.
7.0 HILL- N -PARK WWTP POTENTIAL
7.1 Long -Term Improvements
Regardless of who is operating the Hill -N -Park plant several modifications could be made to
improve the operation of the plant including the following:
• Modify the flow regime from complete mix to plug flow operation
• Add aeration on half of the stilling pond
• Build new chlorine housing and contact tank
7.2 Ultimate Expansion Potential
The Hill -N -Park plant has the some potential for getting re -rated similar to the Evans WWTP. A
more effective aeration system and efficient flow regime could result in the plant being re -rated.
Beyond this, the plant might be expanded by acquiring the land on the north side of the Evans'
Ditch. If expanded, the plant could most efficiently handle all the flows west of Basin No. 8
which amounts to about 2.0 mgd. This is over five times the current capacity, so a substantial
increase in capacity would be required, which may or may not fit in the area.
P:\EVANSMPDOC\TM I CDOC
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7.3 Recommendations
With the implementation of the re-routing of flows generated at the Carriage and Country estates,
the Hill -N -Park plant capacity will be adequate for the next ten years. As its capacity is reached,
the first option would be to re -rate the plant and then begin expansion as necessary and acquiring
land as needed.
Taking over the Hill -N -Park plant by the City of Evans does not seem advantageous until flows
begin to generate in various parts of the western portion of the UGA. At this time is assumed the
Hill -N -Park developer would not be interested in taking on the task of upgrading, re -rating and
expanded the plant. Based on the current analysis, Evans would not want to take over the plant
until substantial flows develop west of Basin 8.
8.0 RECOMMENDATIONS
8.1 General
A capital improvements cost analysis and comparison is presented in TM No. 12. The following
recommendations summarize the findings of this TM which could be modified later based on the
costs indicated in No. 12.
8.2 Short Term
• Re -rate the plant capacity of the Evans WWTP immediately.
• Implement process improvements associated with re -rating.
• Construct a new influent pump station, screening facilities, and laboratory at the Evans
WWTP.
• Do not take over operation of the Hill -N -Park WWTP at this time.
• Construct a gate and pump pit at the end of the WWTP outfall to prevent high river flows
from surcharging the outfall.
• Begin discussions with Greeley regarding treatment options (flow volumes) and cost of
treatment (volume and capital improvements).
8.3 Long Term
• Begin design for expansion of the Evans WWTP in about three to four years.
• Consider taking over operation of the Hill -N -Park Plant depending on wastewater flows
west of Basin 8.
8.4 Ultimate
• Expand Evans WWTP to treat 2.4 mgd of flows within the City limits and from Basin
No. 8. First expansion may be required in about eight to ten years. As capacity
P:\EVANSMPDOC\TM I I. DOC
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approaches 2.4 mgd, it may require nitrification and potentially a new or substantially
modified plant.
• Take over operation of the Hill -N -Park plant.
• Re -rate, expand and modify the Hill -N -Park plant as much as possible to treat the flows
from Basins No. 4 through 7.
P\EVANSMPDOC TM I L. DOC
TM11-15
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TM No. 12 Wastewater 10 -Year Capital Improvements Plan (CIP)
970563
To:
From:
EVANS WATER/WASTEWATER MASTER PLAN
TECHNICAL MEMORANDUM NO. 12
City of Evans, Colorado
HDR Engineering, Inc.
Date: March 7, 1996
Revised June 12, 1996
Subject: Wastewater 10 -Year Capital Improvements Plan (CIP)
Project No. 06923-003-050
1.0 INTRODUCTION
1.1 Purpose of Memorandum
The purpose of this technical memorandum is to summarize the recommended 10 -year (1996-
2005) capital improvement plan (CIP) for the wastewater treatment and collection facilities.
2.0 ANALYSIS
2.1 Water and Wastewater Staffing Requirements
An evaluation was performed to review the water and wastewater staffing requirements for
Evans. Currently the City of Evans employs the following utilities department staff:
Water Department
1 - Supervisor
5 - Tech II personnel
2 - Tech I personnel
Varies - Seasonal Employees
Wastewater Department
1 - Supervisor
1 - Operator
1 - Tech I
The water staff also maintains the streets in addition to water maintenance duties.
The staffing evaluation included reviewing EPA recommendations based on the document
"Estimating Staffing for Municipal Wastewater Treatment Facilities", EPA MO -1, March, 1973.
TM 12-1
970563
In addition, several front range and Colorado communities similar in size to Evans were
contacted regarding current staffing levels.
Based on the evaluation, it is concluded that Evans has adequate staffing for the next ten years.
Most similar communities questioned utilize a combined water and wastewater staff with shared
responsibilities. It is recommended that Evans employ this policy whenever possible.
2.2 Financing Sources
The intention of this section is to identify project financing needs and funding options available
for meeting these needs. In addition, a cursory evaluation of the options is presented for
purposes of estimating overall financing costs, water rate impacts, and wastewater rate impacts.
2.2.1 Financing Requirements
Based upon improvements and costs identified in the technical memoranda 7 and 12,
Table 12-1 summarizes capital needs for the water and wastewater systems and whether
they will be financed by annual revenues or debt. It should be noted that cost estimates
shown in Table 12-1 include the effects of 3 percent annual inflation. In addition, future
water right purchases for new customers, which will be financed in advance by
developers, are not included in Table 12-1.
2 .2.2 Financing Sources
Several sources are available for financing these capital improvements, including private,
state, and Federal sources.
Private Sources of Financing
Private sources consist primarily of bonding, such as General Obligation (GO) bonds and
Revenue bonds. The City is currently in the process of issuing GO bonds for
construction of municipal facilities. The water and wastewater capital improvements
identified in Table 1 are not included in this bond issuance. Revenue bonds are a more
likely source of private financing for the water and wastewater enterprises. Revenue
bonds will carry a slightly higher interest rate than GO bonds but only require City
Council approval, rather than voter approval, before issuance.
State Sources of Financing
State sources include grant programs, revolving fund programs, and other programs.
Grant programs consist of Energy and Mineral Impact Assistance Funds, which Evans
has applied for, and Community Development Block Grants. Loan funds are available
from the Impact Assistance fund but are limited in size of issuance and carry a minimum
interest rate of 5 percent.
TM 12-2
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970563
The source of revolving funds for wastewater system improvements is the Water
Pollution Control Revolving Fund (WPCRF), administered jointly by the Department of
Local Affairs (Division of Local Government), Colorado Dept. of Health (Water Quality
Control Division), and the Colorado Water Resources and Power Development
Authority. Federal EPA funds are channeled through this program. The WPCRF is a
relatively well known and well -used program in Colorado and may be a viable source of
financing for Evans' wastewater system improvements.
The Colorado Water Resources and Power Development Authority (CWR&PDA or
Authority) administers the Domestic Water Supply Project Revolving Fund. Funds for
these loans are limited and capped at $500,000 per project.
Other state programs include the Colorado Water Conservation Board Construction Fund
and the CWR&PDA Small Water Resources Projects Program. Funds for both programs
are also limited and neither source will fund the purchase of water rights.
Federal Sources of Financing
The Rural Economic and Community Development Administration (Rural Development),
the former Farmers Home Administration, is the primary source of Federal funds under
the Water and Waste Disposal Loans and Grants Program. Like other Rural
Development borrowers, the City of Evans would need to demonstrate that other sources
of private or public financing are either unavailable or only available under terms that
would cause undue hardship to the City residents.
All of Evans' identified improvements would be eligible for financing under the Rural
Development Program. Grant funds are generally targeted to cities with greatest financial
needs, especially those currently not in compliance with discharge permits or water
quality standards. Loan funds are also limited by availability. However, local Rural
Development officials have indicated that additional funds may be available from their
Washington DC headquarters.
In addition to Rural Development financing, the City is on the priority list for a 1996
Federal Construction Grant. If available, this would offset wastewater capital costs by
$200,000.
Table 12-2 summarizes the sources of financing identified above in the context of type of
loan, loan terms, special requirements, and other information relevant to selection of a
preferred financing source or sources.
P \EVANSMP\DOC\TM I 2.DOC
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2.2.3 Analysis of Financing Alternatives
Rather than directly recommending a single financing alternative for the water and
wastewater projects, this section develops 3 financing alternatives for consideration.
These alternatives are general in nature and represent the local, state, and Federal sources
discussed above.
The alternatives consider financing requirements for the years 1996-98. This is about the
period of time the City would be allowed to spend proceeds on a bond issued in 1996. It
should also be noted that public funds would likely be issued on an annual basis, rather
than in a single issuance like a bond. However, for analysis purposes it is assumed that
all proceeds are obtained in 1996.
The alternatives are as follows:
1. Private financing. This alternative assumes that revenue bonds exclusively used for
financing the water and wastewater projects. The assumptions used in the analysis,
the annual debt service obligation, and total financing costs are summarized in Table
12-3.
2. State/private financing. This assumes that the State programs are used to the extent
possible, with the balance of the financing (for water rights) provided by a revenue
bond. Table 12-4 summarizes the analysis of this alternative.
3. Federal financing. This assumes that Rural Development funds are available and are
used for financing the entire project. Table 12-5 summarizes this alternative.
P'1E VANSMPU)OC\TM I:.D0C
TM 125
970563
Other considerations
Special requirements
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970563
Table 12-3
City of Evans, Colorado
Financing With Revenue Bonds
Average interest rate
Term
Reserve requirement:
Issuance costs: /1
Interest rate on reserves:
Capital needs, 1996-98
Total issuance
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
Totals
6.50%
20
Equal to annual debt service
3.50%
5.00%
$ 2,004,420
$ 2,284,575
Total financing costs are the sum of issuance costs
plus interest costs, less the value of the required
reserve at the end of the repayment period.
L
Total financing costs: $ 1,517,696
Annual debt
service Interest Principal
103,670
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
207,340
103,670
74,249
146,585
142,636
138,430
133,951
129,181
124,100
118,690
112,928
106,791
100,255
93,295
85,882
77,987
69,579
60,625
51,088
40,932
30,115
18,596
6,327
29,421
60,755
64,704
68,910
73,389
78,159
83,239
88,650
94,412
100,549
107,085
114,045
121,458
129,353
137,761
146,715
156,252
166,408
177,225
188,744
97,343
Remaining
balance
$ 2,284,575
2,255,153
2,194, 399
2,129,695
2,060,785
1,987,397
1,909,238
1,825,998
1,737,348
1,642,936
1,542,387
1,435,303
1,321,258
1,199,800
1,070,447
932,686
785,971
629,719
463,311
286,087
97,343
(0)
Interest
income on
reserve
$ 5,183
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
10,367
5,183
1,862,221 2,284,575 207,340
Value of reserve > 414,680
P:‘EVANSMP\D0OTM 12,DOC
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970563
Table 12.4
City of Evans, Colorado
Financing With State Funds, with Revenue Bonds for Water Rights Purchase
Revenue Bond Component
Average interest rate
Term
Reserve requirement (%)
Issuance costs (%):
Interest rate on reserves:
6.50%
20
Equal to annual debt service
3.50%
5.00%
Water rights expenditures, 1996-98 E 833,800
Total issuance $ 949,983
Totals
Annual debt
service
Total financing costs are the sum of issuance costs plus
interest costs, less the value of the required reserve at
the end of the repayment period
Total financing costs: E 631,107
Interest Principal
Remaining income on
balance reserve
1997 43,109 30,874 12,234 937,749 $ 2,155
1998 66,217 60,954 25,263 912,486 4,311
1999 86,217 59,312 26,905 885,580 4,311
2000 86.217 57,563 28,654 856,926 4,311
2001 86.217 55,700 30,517 826,409 4,311
2002 86.217 53,717 32,500 793.908 4,311
2003 86,217 51,604 34,613 759,295 4,311
2004 86,217 49,354 36,863 722,433 4,311
2005 86.217 46,958 39,259 683.174 4,311
2006 86,217 44,406 41,811 641363 4,311
2007 86.217 41,689 44,528 596,835 4,311
2008 86,217 38,794 47,423 549.412 4,311
2009 86,217 35,712 50,505 498,907 4,311
2010 86,217 32,429 53,788 445,118 4,311
2011 86,217 28.933 57,284 387834 4,311
2012 86.217 25,209 61008 326.826 4,311
2013 86.217 21,244 64,973 261.853 4,311
2014 86,217 17,020 69,197 192.656 4,311
2015 86,217 12.523 73,694 118.962 4,311
2016 86,217 7,733 75,485 40.477 4,311
2017 43,109 2,631 40,477 (0) 2,155
774,358 949,983 86,217
Value of reserve > 172,434
State Revolving Fund Component
P IEVANSMP
Average interest rate
Term
Reserve requirement (%)
Issuance costs (%):
Interest rate on reserves:
All other capital expenditures
Total issuance
Totals
DOCfTM 13,000
4.58%
20
0.00%
2.50%
0.00%
E 1,373,313
$ 1,407,646
Annual debt
service
Total financing costs ere the sum of issuance costs plus
interest costs, less the value of the required reserve at
the end of the repayment period
Total financing costs: $ 806,004
Interest Principal
Remaining income on
balance reserve
E 1,407,646
1996 54,483 32,235 22,248 1,385,398
1997 108,966 63,451 45.515 1639,884
1998 108,966 61,367 47,599 1,292,285
1999 108,966 59.187 49,779 1,242,505
2000 108,966 56,907 52,059 1,190,446
2001 108,966 54,522 54,443 1,136,003
2002 108,966 52.029 56,937 1,079,066
2003 108,966 49,421 59,545 1,019,521
2004 108,966 46,694 62,272 957,249
2005 108,966 43,542 65,124 892.126
2006 108,966 40,859 68.107 824,019
2007 108,966 37,740 71,226 752,793
2008 108,966 34,478 74,488 678,305
2009 108,966 31,066 77,899 600,406
2010 108,966 - 27,499 81.467 516939
2011 108,966 23,767 85,198 433,740
2012 108,966 19,865 89,101 344,640
2013 108,966 15,784 93,181 251,458
2014 108,966 11,517 97,449 154,009
2015 108,966 7.054 101,912 52,097
2016 54,483 2,386 52,097 0
TM 1 28
771.671
1,407,646
Value of reserve >
970563
Table 12.5
City of Evans, Colorado
Financing With Rural Development Administration
P:\EVANSMP
Average interest rate
Term
Reserve requirement (%)
Issuance costs (%):
Interest rate on reserves:
Capital needs, 1996-98
Total issuance
Totals
DOQTM p.. nOC
5.00%
40
0.00%
2.50%
0.00%
$ 1,968,830
$ 2,018,051
Annual debt
service
Total financing costs are the sum of issuance costs
plus interest costs, less the value of any required
reserve at the end of the repayment
period
i
Total financing costs: $2,735,501
Interest Principal
1997 58,804 50,451
1998 117,608 100,485
1999 117,608 99,629
2000 117,608 98,730
2001 117,608 97,786
2002 117,608 96,795
2003 117,608 95,754
2004 117,608 94,661
2005 117,608 93,514
2006 117,608 92,309
2007 117,608 91,044
2008 117,608 89,716
2009 117,608 88,321
2010 117,608 86,857
2011 117,608 85,320
2012 117,608 83,705
2013 117,608 82,010
2014 117,608 80,230
2015 117,608 78,361
2016 117,608 76,399
2017 117,608 74,338
2018 117,608 72,175
2019 117,608 69,903
2020 117,608 67,518
2021 117,608 65,013
2022 117,608 62,384
2023 117,608 59,622
2024 117,608 56,723
2025 117,608 53,679
2026 117,608 50,482
2027 117,608 47,126
2028 117,608 43,602
2029 117,608 39,902
2030 117,608 36,016
2031 117,608 31,937
2032 117,608 27,653
2033 117,608 23,155
2034 117,608 18,433
2035 117,608 13,474
2036 117,608 8,267
2037 58,804 2,800
TM 12.9
8,353
17,123
17,980
18,879
19,822
20,814
21,854
22,947
24,094
25,299
26,564
27,892
29,287
30,751
32,289
33,903
35,598
37,378
39,247
41,209
43,270
45,433
47,705
50,090
52,595
55,225
57,986
60,885
63,929
67,126
70,482
74,006
77,707
81,592
85,672
89,955
94,453
99,176
104,134
109,341
56,004
2,686,281 2,018,051
Remaining
balance
$ 2,018,051
2,009,698
1,992,574
1,974,595
1,955,716
1,935,894
1,915,080
1,893,226
1,870,279
1,846,185
1,820,886
1,794,322
1,766,429
1,737,143
1,706,392
1,674,103
1,640,200
1,604,601
1,567,223
1,527,976
1,486,767
1,443,497
1,398,063
1,350,358
1,300,268
1,247,673
1,192,448
1,134,462
1,073,577
1,009,647
942,522
872,039
798,033
720,326
638,734
553,063
463,108
368,655
269,479
165,345
56,004
(0)
Value of reserve >
Interest
income on
reserve
97
tl
563
In terms of total finance costs, the Rural Development alternative is the most expensive
when total interest payments over the term of the loan are summed. Revenue bonds are
the second most costly source of funds, with the State Revolving Funds being the least
expensive.
Table 12-6 shows that the rate impacts associated with the Rural Development alternative
are the least among the financing alternatives considered. This is because the debt is
financed over 40 years, rather than the 20 year terms associated with Revenue Bonds and
State funds, resulting in lower annual debt service.
3.0 RECOMMENDATIONS
3.1 Recommended Capital Improvement Plan (1996-2005)
Table 12-7 summarizes the recommended wastewater treatment and collection system CIP. All
costs are in 1996 dollars. Costs are categorized by wastewater collection (upgrade and growth
related improvements) and water treatment improvements.
Table 12-6
City of Evans, Colorado
Water and Wastewater Impacts of the Financing Alternatives
Single family residential equivalents: 2,580
Rate impacts, $/month
per single family
residence
Water rate impacts
Wastewater rate impacts
Combined impact
Rural
State Revolving Development
Revenue bonds Funds Administration
$ 4.08 $ 3.84 $ 2.31
$ 2.62 $ 2.47 $ 1.49
6.70 $
6.30 $ 3.80
P:\E V ANSNIPIDOQTM I:, DOC
TM1210
970563
lABLE 11-7
Recommended Wastewater 10 -Year Capital Improvement Plan
Estimated Project Cost by Year'
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A. Wastewater Collection
No— Sae Length (It) Location
}1-17100 — Reh biIitate existing sewer on 3)11St. ICHWy S5
B Wastewater Treatment
r2 Apply to CDPAE to rerate capacity of WWTP from 0.9 mgd to 1.2 mgd
}3 Construct new Influent Pump Station/Screening Factltry/Lab ncy Generator
_ }4 Constrate at End of WWTP Oatfall
Subtotal
Developpme�rowthZmprovemenls D Improvements)
CWIlieraterrdllection
Length It) Location
Dl 12 6160 Colony Plaza Interceptor.
B. astewatcr reatment
H3
UL Aerator blectrical Modifications
D3 Jet -Vac Sewer Truck
4 Expand WWfP capacity to 2 d (serve growt�hrough year 2025)
a. Planning at 80°paa2)J
b. Lonstmction at 93° capacity
D5 Add chlorination scrubber
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'All costs are in 19963ollars
Costs inc ude }5°7 engmttring and70tingency allowances
'mod of 12 mg rd� capacity and -COME criteria
'ToTaF oject os-any participation is approximately 580,000
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970561
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FIGURE 12-1
CDPHE LETTER
970563
STATE OF COLORADO
Roy Romer, Governor
Patti Shwayder, Acting Executive Director
Dedicated to protecting and improving the health and environment of the people of Colorado
4300 Cherry Creek Dr. S.
Denver, Colorado 80222-1530
Phone (303) 692-2000
January 9, 1996
Laboratory Building
4210 E. 11th Avenue
Denver, Colorado 80220-3716
(303) 691-4700
Craig Hobben
HDR Engineering, Inc.
303 E. 17th Ave., Suite 300
Denver, CO 80203
RE7'ED
!JAN 12 S5
HDR E':C_ :._....
Colorado Department
of Public Health
and Environment
RE: Preliminary Effluent Limits for City of Evans, Permit No. CO -0020508, Weld County
Dear Mr. Hobben:
Please find enclosed the Colorado Ammonia Model results for design capacities of 1.2 MGD and 1.4 MGD.
As I stated in our phone conversation of today, there will not be any ammonia limitations required if the City
decides to expand the current facility to either of the two proposed capacities.
If you have any questions regarding this matter, please contact me at 692-3614.
Sincerely,
Karen Young
Environmental Protection Specialist
Permits and Enforcement Section
Water Quality Control Division
Enclosure
x.: Local Health Department
Victor Sainz, District Engineer, Denver Office
Tom Bennett, Groundwater and Standards Section
9'70563
STREAM CONDITIONS AND EFFLUENT LIMITS TO MEET CHRONIC STANDARD
-ns
CHRONIC STANDARD ANALYSIS
UPSTREAM CONDITIONS SETPOINT MIXED CONDITIONS
cfs PH TEMP NHTOT pH TEMP cfs PH TEMP
JAN 26.0 NA NA 2.3 7.9 4.6 27.9 7.7 4.5
FEB 26.0 NA NA 2.4 7.8 4.6 27.9 7.6 4.5
MAR 26.0 NA NA 1.7 7.9 9.8 27.9 7.8 9.8
APR 26.0 NA NA 0.8 7.9 9.6 27.9 7.8 9.6
MAY 26.0 NA NA 0.2 7.7 11.4 27.9 7.6 11.5
JUN 26.0 NA NA 0.3 7.7 16.8 27.9 7.7 16.9
JUL 26.0 NA NA 0.6 7.8 20.1 27.9 7.7 20.3
AUG 26.0 NA NA 0.3 7.9 18.5 27.9 7.8 18.8
SEP 26.0 NA NA 0.4 7.9 17.8 27.9 7.8 18.0
OCT 26.0 NA NA 0.8 8.0 12.9 27.9 7.8 12.8
NOV 26.0 NA NA 1.0 7.9 9.4 27.9 7.8 9.2
DEC 26.0 NA NA 2.1 7.8 3.0 27.9 7.6 2.9
SCALAR 1.0 :CHRONIC FLOW
STREAM CONDITIONS AND EFFLUENT LIMITS TO MEET CHRONIC STANDARD
Evans
CHRONIC STANDARD ANALYSIS CHRONIC
EFFLUENT
CRITICAL POINT CONDITIONS NHTOT
cfs MILES PH TEMP %_UNION NHTOT mg/1
JAN 27.9 0.5 7.8 4.6 0.84% 11.8 161.4
FEB 27.9 1.0 7.8 4.6 0.78% 12.9 194.8
MAR 27.9 0.5 7.9 9.8 1.30% 7.7 104.6
APR 27.9 0.5 7.9 9.6 1.33% 7.5 114.8
MAY 27.9 0.5 7.7 11.4 0.93% 10.7 178.5
JUN 27.9 0.0 7.7 16.9 1.41% 7.1 102.0
JUL 27.9 0.0 7.7 20.3 2.12% 4.7 62.5
AUG 27.9 1.0 7.9 18.5 2.89% 3.5 67.2
SEP 27.9 0.5 7.9 17.8 2.77% 3.6 58.1
OCT 27.9 1.0 8.0 12.9 2.32% 4.3 71.2
NOV 27.9 0.5 7.9 9.4 1.36% 7.3 108.5
DEC 27.9 0.5 7.7 3.0 0.57% 17.4 253.5
LAR
970563
-e AM CONDITIONS AND EFFLUENT LIMITS TO MEET CHRONIC STANDARD
c[
.ins
CHRONIC STANDARD ANALYSIS
UPSTREAM CONDITIONS SETPOINT MIXED CONDITIONS
cfs PH TEMP NHTOT pH TEMP cfs PH TEMP
JAN 26.0 NA NA 2.3 7.9 4.6 28.2 7.7 4.4
FEB 26.0 NA NA 2.4 7.8 4.6 28.2 7.6 4.5
MAR 26.0 NA NA 1.7 7.9 9.8 28.2 7.7 9.8
APR 26.0 NA NA 0.8 7.9 9.6 28.2 7.8 9.6
MAY 26.0 NA NA 0.2 7.7 11.4 28.2 7.6 11.5
JUN 26.0 NA NA 0.3 7.7 16.8 28.2 7.7 16.9
JUL 26.0 NA NA 0.6 7.8 20.1 28.2 7.7 20.4
AUG 26.0 NA NA 0.3 7.9 18.5 28.2 7.7 18.9
SEP 26.0 NA NA 0.4 7.9 17.8 28.2 7.8 18.0
OCT 26.0 NA NA 0.8 8.0 12.9 28.2 7.8 12.8
NOV 26.0 NA NA 1.0 7.9 9.4 28.2 7.8 9.2
DEC 26.0 NA NA 2.1 7.8 3.0 28.2 7.6 2.9
SCALAR 1.0 :CHRONIC FLOW
STREAM CONDITIONS AND EFFLUENT LIMITS TO MEET CHRONIC STANDARD
Evans
CHRONIC STANDARD ANALYSIS CHRONIC
--N\
CRITICAL POINT CONDITIONS NHTOT
cfs MILES PH TEMP %_UNION NHTOT mg/1
JAN 28.2 1.0 7.9 4.6 0.89% 11.3 145.7
FEB 28.2 1.5 7.8 4.6 0.81% 12.4 177.8
MAR 28.2 0.5 7.8 9.8 1.25% 8.0 95.1
APR 28.2 0.5 7.9 9.6 1.30% 7.7 101.8
MAY 28.2 0.5 7.7 11.4 0.92% 10.8 156.0
JUN 28.2 0.0 7.7 16.9 1.39% 7.2 89.5
JUL 28.2 0.5 7.8 20.1 2.51% 4.0 54.3
AUG 28.2 1.0 7.9 18.5 2.89% 3.5 58.2
SEP 28.2 0.5 7.9 17.8 2.68% 3.7 52.2
OCT 28.2 1.0 8.0 12.9 2.32% 4.3 61.7
NOV 28.2 1.0 7.9 9.4 1.50% 6.7 94.9
DEC 28.2 0.5 7.7 3.0 0.55% 18.0 228.7
ALAR
9705f33
Ownership Deeds
970563
LEGAL DESCHIPTION
A parcel of land be lag Lots 3 through 10
A
6666 and the adfacent East Half of ',sleeted .,
it Cannon Street 1.0.W., subdivision of the
utheemt Quarter of Section 20, located 'j
the Southeast Quarter of Section 20, Vearted Cans St ROW
nthlp 5 North, Range 65 West of the,.— —
y .ch Principal Meridian, City of Evans, �� h,
i County of Weld, State of Colorado, being
S
more particularly described as follows: al sae Ilslba-
I d drat Cep /t' �5 eb em4dlr tram env''
(TYPE
Commencing at the Southeast corner of said
Section 20 and considering. the South line
of said Southeast Quarter of said Section.
-20 to bear North 90.00'00" 541st and all
bearings herein relative thsreto;• thence
'North 00.12'27" Best along the East line
of said 'Southeast Quarter a distance of
40.00 feet, thence North 90.00'0(1" West — -17 — 7
a distance of 30.00 feet io thetrue Point
of Beginning„ thence North' 90'00'00" West
a distance of 548.54 feat, thence North
00'07'49" West a distance of 2,048.00
feet, thence South 89°59'57" East a dis-
tance of 545.73/feet, thence South 00'12'27"
East a distance of .2,048.00' feet to the True
Point of beginning.. Said described parcel
contains 25.S99•ecres of land.
Y
CERTIFICATION f e47.7,!-,-5 L T�
This is to certify that on the 7th day of ,.
March 1985 a survey was lode under I Xi
cel of land and ghis'
and accurate to chic h
•
my supervision of the above described par.• 1
tat of vane is true
at of my know dge.
�'i)
011184
ch Rah[ P.E.-L.S.
Er
=a' 13184 y'.
Jfv .
Mar M l!w '
970563
DAVID 3. MILLER
ATTORNEY AND COUNSELOR AT LAW
xlvwoMR uu
O REELEv. COLORADO
March 6, 1961
Evans Sanitation District
Evans Town Hall
Evans, Colorado
Gentlemen:
We have examined abstract of title covering the following described prop-
erty:
All that part of the East Half of the Southeast Quarter
(E 1/2 SE 1/4) of Section Twenty (20), Township Five
(5) North, Range Sixty-five (65) West of the Sixth
Principal Meridian, more fully described as follows:
Beginning at the Southeast corner of said Section
Twenty (20); thence West 580 feet; thence North
2048 feet; thence East 580 feet; thence South 2048
feet along the East lines of Lots Three (3), Four (4),
Five (5), Six (6), Seven (7), Eight (8), Nine (9) and
Ten (10) of the said Southeast Quarter (SE 1/4) of
Section Twenty (20), to the point of beginning, Weld
County, Colorado.
We have made a supplemental examination of the above described property
consisting of sheets numbered 203 to 213, last continued on the 23rd day of
February, 1961 at 1:05 P.M. under certificate No. 125, 650 of the Weld
County Abstract and Investment Company.
TITLE:
RIGHTS OF WAY:
Based upon this supplemental examination, we find
fee simple title to be in Evans Sanitation District
under Warranty Deed dated February 7, 1961, re-
corded in Book 1577 at page 131 of the Weld County
records (sheet 203).
1. Ordinance No. 132 of the Town of Evans, recorded
in Book 1577 at page 512 of the Weld County records
(sheet 209) vacates all streets or roads located within
the boundaries of the above described property.
• r ,M
r•
rr
Evans Sanitation District March 6, 1961
All other items not inconsistent with this supplemental opinion enumerated
in our original opinion dated February 6, 1961 are hereby incorporated by
reference and made a part of this supplemental examination.
Very truly yours,
Robert
RR:ih
4g
ry
970563
City Ordinances
970563
CITY OF EVANS, COLORADO
RESOLUTION NO. 36-1996
A RESOLUTION INCREASING SEWER SYSTEM DEW OPMENT FEES AND
SEWER RATES FOR USE OF THE SANITARY SEWER SYSTEM OF THE
CITY OF EVANS, COLORADO
WHEREAS, the City Council is authorized to set, by Resolution, rates for the use of the
Evans' Sanitary Sewer System; and
WHEREAS, the Water and Sewer Board has reviewed the costs of operation, repairs and
replacements, capital improvements, and future plant expansion; and
WHEREAS, the Water and Sewer Board found that existing sewer usage rates are not
sufficient to cover current costs of operations and necessary capital improvements; and
WHEREAS, Sewer Development Fees have not been adjusted since 1993; and
WHEREAS, the Water and Sewer Board has recommended increases to sewer usage rates
and Sewer System Development fees.
NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF
EVANS, COLORADO:
Section 1. Sewer Usage Rates.
A. Effective October 1, 1996, the sewer rates for the use of the City of Evans Sanitary
Sewer shall be as follows:
Class I. Residential Sanitary Sewer Rates. Single family units, multi -family units, and
mobile home parks connected on one sewer service tap shall be assessed $7.00 per residential living
unit per month.
Class II. Commercial Rates. Applicable to schools, churches, warehouses, and offices shall
be assessed $3.05 per water tap per month plus $.77 per 1,000 gallons of water used per month It
the commercial customer waters a lawn of 18,000 square feet or more using metered water, the sewer
charge to that customer shall be calculated on the current year's first quarter water usage.
Class III. Commercial Rates. Applicable to beauty shops, barber shops, bars/tavems,
service stations (excluding wash racks), vehicle and equipment repair facilities, and motels without
dining facilities shall be assessed $3.05 per water tap per month plus $21 per 1,000 gallons of water
used per month If the commercial customer owns and waters a lawn of 18,000 square feet or more
using metered water, the sewer charge to that customer shall be calculated on the current year's first
quarter water usage.
970563
Class IV. Commercial Rates. Applicable to restaurants, motels/hotels with dining facilities,
office buildings with dining facilities, grocery stores with food processing, Laundromats (excluding
dry cleaning) carwashes and truck washes shall be assessed $3.05 per water tap per month plus $1.60
per 1,000 gallons of water used per month. If the commercial customer owns and waters a lawn of
18,000 square feet or more using metered water, the sewer charge to that customer shall be
calculated on the current year's first quarter water usage.
Class V. Commercial Rates. Any other facility or commercial use not listed or with special
and unique types of discharge shall have their rates set by the Water and Sewer Board with final
approval by the City Council.
Class VI. Non -Resident Rates. The rates for service to properties outside the Evans City
Limits shall be 150% of the appropriate rate provided for Class I through IV.
B. Multiple User Tap
Any tap providing multiple usage shall be billed for all usage at the rate applicable to the
highest class of user.
Section 2. Sewer System Development Fees
A. Effective January 1, 1997, Sewer System Development Fees are hereby fixed,
imposed, and levied upon any owner, lessee or user of the sanitary sewer within the limits of the City
of Evans except where more than one residential living unit will be served by the tap. The fees
imposed shall be computed by reference to the diameter of the water tap used to provide water
service.
Water Tap
Size
Meter
Equivalent
Inside City Sewer
System Development Fee
Outside City Sewer
System Development Fee
3/4"
1.00
$1,250
$1,875
1"
1.67
$2,088
$3,131
1'/z"
3.33
$4,163
$6,244
2"
5.33
$6,663
$9,994
3"
11.67
$14,588
$21,881
4"
20.00
$25,000
$37,500
6"
41.67
$52,500
$78,131
8"
60.00
$75,000
$112,500
10"
96.67
$120,838
$181,256
B. Where more than one residential living unit is proposed to be served by a single tap,
the system development fee inside City limits shall be based on the number of living units multiplied
by $870 or the system development fee as provided in Subsection A for this section, whit/863
oreater �,//
Where more than one residential living unit is proposed to be served by a single tap the system
development fee outside City limits shall be based on the number of living units multiplied by $1,305
or the system development fee as provided in Subsection A for this section, whichever is greater.
C. If the primary or only purpose of a water tap is to provide protection from fire, the
diameter of that tap shall not be considered in fixing the system development fee for sanitary sewer
service, but rather the fee shall be set by reference to the diameter of any separate water tap which
is used to provide regular domestic water service to the parcel, or if no such separate tap exists, then
by reference to the diameter that the water tap would have been had there been no oversizing because
of fire protection requirements.
PASSED, APPROVED AND ADOPTED at a regular meeting of the City Council of the
City of Evans on this Ird day of December , 1996.
CITY OF EVANS, COLORADO
ATTEST:
970563
Chapter 13.20
SEWER SYSTEM
Sections:
13.20.010 Definitions.
13.20.020 Utilities department.
13.20.030 Use of public sewers required.
13.20.040 Private sewage disposal.
13.20.050 Building sewers and connections.
13.20.060 Use of the public sewers.
13.20.070 Protection from damage.
13.20.080 Powers and authority of inspectors.
169 (Evans 5/87)
970563
13.20.010
13.20.090 Rates.
13.20.100 Violation --Penalties.
13.20.010 Definitions. Unless the context specifi-
cally indicates otherwise, the meaning of the terms used in
this chapter shall be as follows:
A. "BOD" (denoting biochemical oxygen demand) means the
quantity of oxygen utilized in the biochemical oxidation of
organic matter under standard laboratory procedure in five
days at twenty degrees Centigrade, expressed in milligrams
per liter.
B. "Building drain" means that part of the lowest
horizontal piping of a drainage system which receives the
discharge from soil, waste and other drainage pipes inside
the walls of the building and conveys it to the building
sewer, beginning five feet (1.5) meters) outside the inner
face of the building wall.
C. "Building sewer" means the extension from the build-
ing drain to the public sewer or other place of disposal.
D. "City" means the city of Evans, Colorado.
E. "City manager" means the city manager or acting city
manager of the city.
F. "Combined sewer" means a sewer receiving both sur-
face runoff and sewage.
G. "Director" means the director or acting directortof
the utilities department.
H. "Garbage" means solid wastes from the domestic and
commercial preparation, cooking and dispensing of food, and
from the handling, storage and sale of produce.
I. "Industrial wastes" means the liquid wastes from
industrial manufacturing processes, trade or business, as
distinct from sanitary sewage.
J. "Natural outlet" means any outlet into a water-
course, pond, ditch, lake or other body of surface water or
groundwater.
K. "Person" means any individual, firm, company, assoc-
iation, society, corporation or group.
L. "pH" means the logarithm of the reciprocal of the
weight of hydrogen ions in grams per liter of solution.
M. "Properly shredded garbage" means the wastes from
the preparation, cooking and dispensing of food that have
been shredded to such a degree that all particles will be
carried freely under the flow conditions normally prevailing
in public sewers, with no particle greater than one-half inch
(1.27 centimeters) in any dimension.
N. "Public sewer" means a sewer in which all owners of
abutting properties have equal rights, and which is control-
led by public authority.
O. "Sanitary sewer" means a sewer which carries sewage
and to which stormwaters, surface waters and groundwaters are
not intentionally admitted.
P. "Sewage" means a combination of the water -carried
169-1
(Evans 6/86)
970563
13.20.020--13.20.030
wastes from residences, business buildings, institutions and
industrial establishments, together with such groundwaters,
surface waters and stormwaters as may be present.
Q. "Sewage treatment plant" means any arrangement of
devices and structures used for treating sewage.
R. "Sewage works" means all facilities for collecting,
pumping, treating and disposing of sewage.
S. "Sewer" means a pipe or conduit for carrying sewage.
T. "Shall" is mandatory; "may" is permissive
U. "Slug" means any discharge of water, sewage or in-
dustrial waste which, in concentration of any given constitu-
tent or quantity of flow exceeds for any period of duration
longer than fifteen minutes more than five times the average
twenty -four-hour concentration or flows during normal opera-
tion.
V. "Storm drain" (sometimes termed "storm sewer") means
a sewer which carries stormwaters, surface waters and drain-
age, but excludes sewage and industrial wastes, other than
unpolluted cooling water.
W. "Suspended solids" means solids that either float on
the surface of, or are in suspension in water, sewage or
other liquids, and which are removable by laboratory filter-
ing.
X. "Watercourse" means a channel in which a flow of
water occurs, either continuously or intermittently.
(Ord. 609-85 Sec. 1 (part), 1985)
13.20.020 Utilities department. The sewer system and
sewer facilities of the city shall be operated by the utili-
ties department. (Ord. 609-85 Sec. 1 (part), 1985)
13.20.030 Use of public sewers required. A. It is
unlawful for any person to place, deposit or permit to be
deposited in any unsanitary manner on public or private prop-
erty within the city, or in any area under the jurisdiction
of the city, any human or animal excrement, garbage, or other
objectionable waste.
B. It is unlawful to discharge to any natural outlet
within the city, or in any area under the jurisdiction of the
city, any sewage or other polluted waters, except where
suitable treatment has been provided in accordance with
subsequent provisions of this chapter.
C. Expect as hereinafter provided, it is unlawful to
construct or maintain any privy, privy vault, septic tank
cesspool, or other facility intended or used for the dis-
posal of sewage.
D. The owner of all houses, buildings or properties
used for human occupancy, employment, recreation or other
purposes, situated within the city and abutting on any
street, alley or right-of-way in which there is now located
or may in the future be located a public sanitary or com-
bined sewer of the city, is required at his expense to
169-2
(Evans 036 U70363
13.20.040
install suitable toilet facilities therein, and to connect
such facilities directly with the proper public sewer, in
accordance with the provisions of this chapter, within ninety
days after the date of official notice to do so, provided
that the public sewer is within one hundred feet (30.5
meters) of the property line. (Ord. 609-85 Sec. 1 (part),
1985)
13.20.040 Private sewage disposal. A. Where a public
sanitary or combined sewer is not available under the pro-
visions of subsection D of Section 13.20.030, the building
sewer shall be connected to a private sewage disposal system
complying with the provisions of this section.
B. Before commencement of construction of a private
sewage disposal system, the owner shall first obtain a writ-
ten permit signed by the city clerk, after first being ap-
proved by the city council. The application for such permit
shall be made on a form furnished by the city, which the ap-
plicant shall supplement by any plans, specifications and
other information as are deemed necessary by the city
council. A permit and inspection fee of -0- dollars shall
be paid to the city at the time the application is filed.
C. A permit for a private sewage disposal system shall
not become effective until the installation is completed to
the satisfaction of the utilities department. The utilities
department shall be allowed to inspect the work at any stage
of construction and, in any event, the applicant for the
permit shall notify the utilities department when the work is
ready for final inspection, and before any underground
portions are covered. The inspection shall be made within
seventy-two hours of the receipt of notice by the utilities
department.
D. The type, capacities, location and layout of a pri-
vate sewage disposal system shall comply with all recommenda-
tions of the State Department of Public Health. No permit
shall be issued for any private sewage disposal system em-
ploying subsurface soil -absorption facilities where the area
of the lot is less than required by the State Department of
Public Health and the Weld County health department. No
septic tank or cesspool shall be permitted to discharge to
any natural outlet.
E. At such time as a public sewer becomes available to
a property served by a private sewage system, as provided in
subsection D of this section, a direct connection shall be
made to the public sewer, in compliance with this chapter,
and any septic tanks, cesspools and similar private sewage
disposal facilities shall be abandoned and filled with
suitable material.
F. The owner shall operate and maintain the private
sewage disposal facilities in a sanitary manner at all times
at no expense to the city.
169-3 (Evans
13.20.050
G. No statement contained in this section shall be
construed to interfere with any additional requirements that
may be imposed by the State or county Department of Health.
H. When a public sewer becomes available, the building
sewer shall be connected to such sewer within sixty days, and
the private sewage disposal system shall be cleaned of sludge
and filled with clean, bank -run gravel or dirt. (Ord. 609-85
Sec. 1 (part), 1985)
13.20.050 Building sewers and connections. A. No
unauthorized person shall uncover, make any connections with
or opening into, use, alter, or disturb any public sewer or
appurtenance thereof without first obtaining a written permit
from the director.
B. There shall be two classes of building sewer per-
mits: (1) for residential and commercial service, and (2)
for service to establishments producing industrial wastes.
In either case, the owner or his agent shall make applica-
tion on a special form furnished by the city. The permit
application shall be supplemented by any plans, specifica-
tions or other information considered pertinent in the
judgment of the director. A permit and inspection fee of
-0- for a residential or commercial building sewer permit,
and -0- dollars for an industrial building sewer permit
shall be paid to the city at the time the application is '
filed.
C. All costs and expense incident to the installation
and connection of the building sewer shall be borne by the
owner. The owner shall indemnify the city from any loss or
damage that may directly or indirectly be occasioned by the
installation of the building sewer.
D. A separate and independent building sewer shall be
provided for every building; except, where one building
stands at the rear of another on an interior lot and no
public sewer is available or can be constructed to the rear
building through an adjoining alley, court, yard or driveway,
the building sewer from the front building may be extended to
the rear building and the whole considered as one building
sewer.
E. Old building sewers may be used in connection with
new buildings only when they are found, on examination and
test by the director, to meet all requirements of this chap-
ter.
F. The size, slope, alignment, materials of construc-
tion of a building sewer, and the methods to be used in
excavating, placing of the pipe, jointing, testing, and
backfilling the trench, shall all conform to the require-
ments of the building and plumbing code, or other applicable
rules and regulations of the city. In the absence of code
provisions or in amplification thereof, the materials and
procedures set forth in appropriate specifications of the
A.S.T.M. and W.P.C.F. Manual of Practice No. 9 shall apply.
169-4
(Evans 6/86)
970563
13.20.060
G. Whenever possible, the building sewer shall be
brought to the building at an elevation below the basement
floor. In all buildings in which any building drain is too
low to permit gravity flow to the public sewer, sanitary
sewage carried by such building drain shall be lifted by an
approved means and discharged to the building sewer.
H. No person shall make connection of roof downspouts,
exterior foundation drains, areaway drains, or other sources
of surface runoff or groundwater to a building sewer or
building drain which in turn is connected directly or in-
directly to a public sanitary sewer.
I. The connection of the building sewer into the public
sewer shall conform to the requirements of the building and
plumbing code, or other applicable rules and regulations of
the city, or the procedures set forth in appropriate speci-
fications of the A.S.T.M. and the W.P.C.F. Manual of Prac-
tice No. 9. All such connections shall be made gastight and
watertight. Any deviation from the prescribed procedures and
materials must be approved by the director before
installation.
J. The applicant for the building sewer permit shall
notify the director when the building sewer is ready for
inspection and connection to the public sewer. The connec-
tion shall be made under the supervision of the director or
his representative.
K. All excavations for building sewer installation
shall be adequately guarded with barricades and lights so as
to protect the public from hazard. Streets, sidewalks, park-
ways and other public property disturbed in the course of the
work shall be restored in a manner satisfactory to the city.
(Ord. 609-85 Sec. 1 (part), 1985)
13.20.060 Use of the public sewers. A. No person
shall discharge or cause to be discharged any stormwater,
surface water, groundwater, roof runoff, subsurface drainage,
uncontaminated cooling water or unpolluted industrial pro-
cess waters to any sanitary sewer.
B. Stormwater and all other unpolluted drainage shall
be discharged to such sewers as are specifically designated
as combined sewers or storm sewers, or to a natural outlet
approved by the director. Industrial cooling water or
unpolluted process waters may be discharged, on approval of
the superintendent, to a storm sewer, combined sewer, or
natural outlet.
C. No person shall discharge or cause to be discharged
any of the following described waters or wastes to any public
sewers:
1. Any gasoline, benzene, naphtha, fuel oil, or
other flammable or explosive liquid, solid or gas;
2. Any waters or wastes containing toxic or
poisonous soils, liquids or gases in sufficient quantity,
either singly or by interaction with other wastes, to injure
or
169-5
(Evans 6u-ru56a
13.20.060
interfere with any sewage treatment process, institute a
hazard to humans or animals, create a public nuisance, or
create any hazard in the receiving waters of the sewage
treatment plant, including but not limited to cyanides in
excess of two mg/1 as CN in the wastes discharged to the
public sewer;
3. Any waters or wastes having a pH lower than
5.5, or having any other corrosive property capable of
causing damage or hazard to structures, equipment and
personnel of the sewage works;
4. Solid or viscous substances in quantities or of
such size capable of causing obstruction to the flow in
sewers, or other interference with the proper operation of
the sewage works, such as, but not limited to ashes, cinders,
sand, mud, straw, shavings, metal, glass, rags, feathers,
manure, hair and fleshings, entrails, and paper dishes, cups,
milk containers, etc., either whole or ground by garbage
grinders.
D. No person shall discharge or cause to be discharged
the following described substances, materials, waters or
wastes if it appears likely, in the opinion of the director,
that such wastes can harm either the sewers, sewage treatment
process or equipment, have an adverse effect on the receiv-
ing stream, or can otherwise endanger life, limb, public
property, or constitute a nuisance. In forming his opinion
as to the acceptability of these wastes, the director will
give consideration to such factors as the quantities of sub-
ject wastes in relation to flows and velocities in the
sewers, materials of construction of the sewers, nature of
the sewage treatment process, capacity of the sewage treat-
ment plant, degree of treatability of wastes in the sewage
treatment plant, and other pertinent factors. The substances
prohibited are:
1. Any liquid or vapor having a temperature higher
than one hundred fifty degrees Fahrenheit (sixty-five degrees
Centigrade);
2. Any water or waste containing fats, wax, grease
or oils, whether emulsified or not, in excess of one hundred
mg/1 or containing substances which may solidify or become
viscous at temperatures between thirty-two and one hundred
fifty degrees Fahrenheit (zero and sixty-five degrees
Centigrade);
3. Any garbage that has not been properly shred-
ded; the installation and operation of any garbage grinder
equipped with a motor of three -fourths horsepower (0.76 hp
metric) or greater shall be subject to the review and ap-
proval of the director;
4. Any waters or wastes containing strong acid,
iron pickling wastes, or concentrated plating solutions,
whether neutralized or not;
5. Any waters or wastes containing iron, chromium,
copper, zinc and similar objectionable or toxic substances,
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13.20.060
or waster exerting an excessive chlorine requirement, to such
degree that any such material received in the composite
sewage at the sewage treatment works exceeds the limits es-
tablished by the director for such materials;
6. Any waters or wastes containing phenols or
other taste- or odor -producing substances, in such concen-
trations necessary, after treatment of the composite sewage,
to meet the requirements of the state, federal or other
public agencies having jurisdiction for such discharge to the
receiving waters;
7. Any radioactive wastes or isotopes of such
half-life or concentration as may exceed limits established
by the director in compliance with applicable state or
federal regulations;
8. Any waters or wastes having a pH in excess of
9.5;
9. Materials which exert or cause:
a. Unusual concentrations of inert suspended
solids, such as, but not limited to Fullers earth, lime slur-
ries and lime residues, or of dissolved solids such as but
not limited to sodium chlorine and sodium sulfate,
b. Excessive discoloration, such as, but not
limited to dye wastes and vegetable tanning solutions,
c. Unusual BOD, chemical oxygen demand, or
chlorine requirements in such quantities as to constitute a
significant load in the sewage treatment works,
d. Unusual volume of flow or concentration of
wastes constituting slugs, as defined in this chapter;
10. Waters or wasters containing substances which
are not amenable to treatment or reduction by the sewage
treatment processes employed, or are amenable to treatment
only to such degree that the sewage treatment plant effluent
cannot meet the requirements of other agencies having juris-
diction over discharge to the receiving waters.
E. If any waters or wastes are discharged, or are pro-
posed to be discharged to the public sewers, which waters
contain the substances or possess the characteristics enum-
erated in subsection D of this section, and which in the
judgment of the director may have a deleterious effect upon
the sewage works, processes, equipment or receiving waters,
or which otherwise crease a hazard to life or constitute a
public nuisance, the director may:
1. Reject the wastes;
2. Require pretreatment to an acceptable condition
for discharge to the public sewers;
3. Require control over the quantities and rates
of discharge; and/or
4. Require payment to cover the added cost of
handling and treating the wastes not covered by existing
taxes or sewer charges under the provisions of subsection J
of this section.
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13.20.060
If the director permits the pretreatment or equalization
of waste flows, the design and installation of the plants and
equipment shall be subject to the review and approval of
director, and subject to the requirements of all applicable
codes, ordinances and laws.
F. Grease, oil and sand interceptors shall be provided
when, in the opinion of the director, they are necessary for
the proper handling of liquid wastes containing grease in
excessive amounts, or any flammable wastes, sand, or other
harmful ingredients; except that such interceptors shall not
be required for private living quarters or dwelling units.
All interceptors shall be of a type and capacity approved by
the director, and shall be located as to be readily and
easily accessible for cleaning and inspection.
G. Where preliminary treatment or flow -equalizing
facilities are provided for any waters or wastes, they shall
be maintained continuously in satisfactory and effective
cooperation by the owner at his expense.
H. When required by the director, the owner of any
property serviced by a building sewer carrying industrial
wastes shall install a suitable control manhole, together
with such necessary meters and other appurtenances, in the
building sewer to facilitate observation, sampling and
measurement of the wastes. Such manhole, when required,
shall be accessibly and safely located, and shall be con-'
structed in accordance with plans approved by the director.
The manhole shall be installed by the owner at his expense,
and shall be maintained by him so as to be safe and access-
ible at all times.
I. All measurements, tests and analyses of the charac-
teristics of waters and wastes to which reference is made in
this chapter shall be determined in accordance with the
latest edition of "Standard Methods for the Examination of
Water and Wastewater," published by the American Public
Health Association, and shall be determined at the control
manhole provided or upon suitable samples taken at such
control manhole. In the event that no special manhole has
been required the control manhole shall be considered to be
the nearest downstream manhole in the public sewer to the
point at which the building sewer is connected. Sampling
shall be carried out by customarily accepted methods to
reflect the effect of constituents upon the sewage works and
to determine the existence of hazards to life, limb and
property. The particular analyses involved will determine
whether a twenty -four-hour composite if all outfalls of a
premises is appropriate, or whether a grab sample or samples
should be taken. Normally, but not always, BOD and suspended
solids analyses are obtained from twenty -four-hour composites
of all outfalls, whereas pH's are determined from periodic
grab samples.
J. No statement contained in this section shall be
construed as preventing any special agreement between the
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13.20.070--13.20.090
city and any industrial concern whereby an industrial waste
of unusual strength or character may be accepted by the city
for treatment, subject to payment therefor by the industrial
concern. (Ord. 609-85 Sec. 1 (part), 1985)
13.20.070 Protection from damage. No unauthorized
person shall maliciously, wilfully or negligently break,
damage, destroy, uncover, deface or tamper with any struc-
ture, appurtenance or equipment which is a part of the sewage
works. Any person violating this provision is guilty of a
misdemeanor. (Ord. 609-85 Sec. 1 (part), 1985)
11.20.080 Powers and authority of inspectors. A. The
director and other duly authorized employees of the city,
bearing proper credentials and identification, shall be per-
mitted to enter all properties for the purposes of inspec-
tion, observation, measurement, sampling and testing, in
accordance with the provisions of this chapter. The director
or his representatives shall have no authority to inquire
into any processes, including metallurgical, chemical, oil,
refining, ceramic, paper or other industries, beyond that
point having a direct bearing on the kind and source od dis-
charge to the sewers of waterways or facilities for waste
treatment.
B. While performing the necessary work on private prop-
erties referred to in subsection A of this section, the di-
rector or duly authorized employees of the city shall observe
all safety rules applicable to the premises established by
the company, and the company shall be held harmless for in-
jury or death to the city employees, and the city shall
indemnify the company against loss or damage to its property
by city employees and against liability claims and demands
for personal injury or property damages asserted against the
company and growing out of the gauging and sampling opera-
tion, except as such may be caused by negligence or failure
of the company to maintain safe conditions as required in
subsection H of Section 13.20.060.
C. The director and other duly authorized employees of
the city, bearing proper credentials and identification,
shall be permitted to enter all private properties through
which the city holds an easement, for the purposes of, but
not limited to, inspection, observation, measurement, samp-
ling, repair and maintenance of any portion of the sewage
works lying within such easement. All entry and subsequent
work, if any, on the easement shall be done in full accord-
ance with the terms of the easement pertaining to the private
property involved. (Ord. 609-85 Sec. 1 (part), 1985)
13.20.090 Rates. A. The rates and charges and the
manner of payment of such rates and charges for the use of
the sanitary sewers and sewage system of the city, for prop-
erty located both within and without the corporate limits of
169-9 (Eva ga,dgti 3
13.20.100
the city shall be as adopted by resolution by the city coun-
cil. Such rates may be amended from time to time as the city
council determines necessary.
B. Each industry creating a special or unusual treat-
ing or handling problem, in the opinion of the city council,
will be charged in accordance with the costs of handling and
treating the actual waste load, at such rates and charges to
be established through contract with the individual industry
and/or resolution of the city council.
C. For property other than residence property situated
without the limits of the city, the user shall make applica-
tion to the council for such use, and a rate shall be es-
tablished by resolution of the city council.
D. Sewer rates and charges shall be due and payable and
shall be collected at the time and in the manner in which
water rates are due and collected.
E. All rates and charges for use of the sewer system of
the city shall constitute a lien upon the land, buildings and
premises served, and in the event such charges shall not be
paid when due, the city treasurer shall certify delinquent
charges to the county treasurer, and the same shall be
collected and paid over to the city in the same manner as
other taxes, and all laws of the state for the collection of
general taxes shall apply, including the laws for the sale of
property for taxes and redemption of same.
F. All revenue derived from the rates and charges im-
posed by this chapter shall be deposited in a special sewer
fund in accordance with the laws of the state, and paid out
only in accordance with such laws. (Ord. 779-90 Sec. 1,
1990; Ord. 609-85 Sec. 1 (part), 1985)
13.20.100 Violation --Penalties. A. Any person found
to be violating any provision of this chapter, except Section
13.20.070, shall be served by the city with written notice
stating the nature of the violation and providing a reason-
able time limit for the satisfactory correction thereof. The
offender shall, within the period of time stated in such
notice, permanently cease all violations.
B. Any person who shall continue any violation beyond
the time limit provided for in subsection 13.20.070, shall be
guilty of a misdemeanor, and on conviction thereof shall be
fined in an amount not exceeding one thousand dollars
($1,000.00) for each violation. Each day in which any such
violation shall continue shall be deemed a separate offense.
C. Any person violating any of the provisions of this
chapter shall become liable to the city for any expense, loss
or damage occasioned the city by reason of such violation.
(Ord. 842-92 Sec. 1, 1992: Ord. 609-85 Sec. 1 (part), 1985)
169-10
(Evans 8/92)
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