HomeMy WebLinkAbout2022 06 13 Public Hearing 402 - Clean Water State Revolving Fund Wastewater Facilities Plan + , PUBLIC HEARINGS AGENDA ITEM 402
CITY COMMISSION AGENDA I JUNE 13, 2022 REGULAR MEETING
TITLE
Clean Water State Revolving Fund Wastewater Facilities Plan
SUMMARY
The Public Works and Utilities Department requests that the City Commission
hold a Public Hearing to consider the Clean Water State Revolving Fund
Wastewater Facilities Plan.
Florida Statutes provide for loans to local government agencies to finance the
design, and construction of wastewater facilities; and the Florida
Administrative Code requires the City Commission to formally adopt a
facilities plan outlining necessary wastewater facility improvements to comply
with State of Florida funding requirements.
The City Commission of the City of Winter Springs, Florida approved
Resolutions 2022-08, 2022-09, and 2022-10 on April 25th 2020, adopting the
Winter Springs Wastewater Master Plan and the Conceptual Design Reports
for the East and West Water Reclamation Facilities, which were intended to
guide the creation and preparation of the more specific Clean Water State
Revolving Fund Wastewater Facilities Plan (hereinafter the "Wastewater
Facilities Plan") adopted in this Resolution and form the conceptual basis for
the design and construction of the facilities.
This plan consists of those necessary plans and studies that directly relate to
the construction of wastewater treatment works, and demonstrates the need
for the proposed facilities. Through a systematic evaluation of feasible
alternatives, this plan also demonstrate that the selected alternative is cost-
effective, while recognizing environmental and social considerations, and
demonstrates the financial capability required for SRF funding.
RECOMMENDATION
The Public Works and Utilities Department requests the City Commission,
consider and recommends approval of Resolution 2022-12, adopting the
Clean Water State Revolving Fund Wastewater Facilities Plan.
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RESOLUTION NUMBER 2022-12
A RESOLUTION OF THE CITY COMMISSION OF THE CITY OF WINTER
SPRINGS, FLORIDA, RELATING TO THE FLORIDA DEPARTMENT OF
ENVIRONMENTAL PROTECTION (FDEP) STATE REVOLVING FUND
(SRF), ADOPTING THE CLEAN WATER STATE REVOLVING FUND
WASTEWATER FACILITIES PLAN FOR THE IMPLEMENTATION OF THE
EAST AND WEST WATER RECLAMATION FACILITY IMPROVEMENTS;
PROVIDING FOR THE REPEAL OF PRIOR INCONSISTENT RESOLUTIONS,
SEVERABILITY,AND AN EFFECTIVE DATE.
WHEREAS, Florida Statutes provide for loans to local government agencies to
finance the design, and construction of wastewater facilities; and the Florida
Administrative Code requires the City Commission to formally adopt a facilities plan
outlining necessary wastewater facility improvements to comply with State of Florida
funding requirements; and
WHEREAS, the City Commission of the City of Winter Springs, Florida
previously approved Resolutions 2022-08, 2022-09, and 2022-10, adopting the Winter
Springs Wastewater Master Plan and the Conceptual Design Reports for the East and West
Water Reclamation Facilities, which were intended to guide the creation and preparation
of the more specific Clean Water State Revolving Fund Wastewater Facilities Plan
(hereinafter the "Wastewater Facilities Plan") adopted in this Resolution and form the
conceptual basis for the design and construction of the facilities; and
WHEREAS, the City Commission of the City of Winter Springs, Florida agrees
with the findings and summary of necessary improvements as outlined in the Wastewater
Facilities Plan for the purpose of designing and constructing Water Reclamation Facilities
to replace the existing East and West Water Reclamation Facilities; and
NOW, THEREFORE, BE IT RESOLVED by the City Commission of the City
of Winter Springs, Florida as follows:
SECTION 1. FINDINGS
The foregoing findings are incorporated herein by reference and made a part hereof.
SECTION 2. ADOPTION OF WASTEWATER FACILITIES PLAN.
The City of Winter Springs Florida, is authorized to and does hereby adopt the proposed
Wastewater Facilities Plan, attached hereto as Exhibit A.
The City Manager is hereby designated as the authorized representative to provide the
assurances and commitments that will be required by the Wastewater Facilities Plan.
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The City Manager is hereby designated as the authorized representative to execute the
Wastewater Facilities Plan which will become the foundation of all activities related to the
wastewater facility improvements. The City Manager is further authorized to represent the
City in carrying out the Wastewater Facilities Plan. The City Manager is authorized to
delegate responsibility to appropriate City Staff to carry out technical, financial, and
administrative activities associated with the Wastewater Facilities Plan.
The legal authority for adoption of this Wastewater Facilities Plan is pursuant to the City
Charter, City Code of Ordinances, and the Laws of the State of Florida.
SECTION 3. REPEAL OF PRIOR INCONSISTENT RESOLUTIONS.
All Resolutions or part of Resolutions in conflict with any of the provisions of this
Resolution are hereby repealed.
SECTION 4. SEVERABILITY.
If any section or portion of a section of this Resolution proves to be invalid, unlawful, or
unconstitutional, it shall not be held to invalidate or impair the validity, force, or effect or
any other section or part of this Resolution.
SECTION 5. EFFECTIVE DATE
This Resolution shall take effect upon its approval and adoption by the City Commission.
APPROVED AND ADOPTION THIS 13TH DAY OF JUNE,2022.
CITY COMMISSION
CITY OF WINTER SPRINGS,FLORIDA
KEVIN MCCANN,MAYOR (SEAL)
ATTEST: APPROVED AS TO FORM:
CHRISTIAN GOWAN, CITY CLERK ANTHONY A.GARGANESE,CITY ATTORNEY
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Clean Water State Revolving Fund
Facilities Plan
for
City of Winter Springs
May 2022
Incorporated
1959
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Certification
I certify that the information contained in this report is true and correct to the best of my knowledge
and that this report has been prepared using sound engineering principles.
Florida Registration No.
Signature of Engineer&Date
Name
Scott Richards, P.E.
Carollo Engineers, Inc.
200 E. Robinson Street, Suite #1400
Orlando, FL 32801
(407) 377-4312
on behalf of
Jason Norberg, Director of Public Works and Utilities
City of Winter Springs
Public Works Office
400 Old Sanford Oviedo Road
Winter Springs, FL 32708
(407) 327-5989
Company, Address, Phone Number, Email
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Acknowledgement
The City of Winter Springs would like to acknowledge the professional work performed by the
Consultants below:
• Carollo Engineers, Inc., for the "East Water Reclamation Facility (WRF) Conceptual
Design Report (CDR)", dated April 2022 (see Appendix A) and the "West Water
Reclamation Facility (WRF) Conceptual Design Report (CDR)", dated April 2022 (see
Appendix S).
• Kimley-Horn for the "2022 Wastewater and Reclaimed Water Master Plan", dated April
2022 (see Appendix Q.
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Table of Contents
Chapter 1.0 Summary of Findings and Recommendations......................................................... 1
Chapter2.0 Introduction ............................................................................................................. 2
2.1 Background....................................................................................................................................................2
2.2 Project Descriptions and Need.......................................................................................................................2
Chapter 3.0 Environmental Impacts............................................................................................ 6
3.1 Environmental Review—Project 41 East WRF Improvements.....................................................................6
3.2 Environmental Review—Project#2 West WRF Improvements....................................................................8
Chapter 4.0 Development of Alternatives................................................................................. 11
4.1 General.........................................................................................................................................................11
4.2 Cost-Effectiveness.......................................................................................................................................11
4.3 East WRF Improvements.............................................................................................................................11
4.3.1 No Action............................................................................................................................................11
4.3.2 Construct a New BNR Facility............................................................................................................11
4.3.3 Construct a New MBR Facility............................................................................................................12
4.4 West WRF Improvements...........................................................................................................................12
4.4.1 No Action ............................................................................................................................................12
4.4.2 Construct a New BNR Facility............................................................................................................12
4.4.3 Construct a New MBR Facility............................................................................................................13
Chapter 5.0 Selected Alternatives............................................................................................. 14
5.1 Description of Proposed Facilities...............................................................................................................14
5.2 East WRF Improvements.............................................................................................................................14
5.3 West WRF Improvements...........................................................................................................................14
5.4 Cost to Construct Facilities..........................................................................................................................15
Chapter 6.0 Implementation and Compliance........................................................................... 16
6.1 Public Hearing/Dedicated Revenue Hearing...............................................................................................16
6.1.1 Financial Planning...............................................................................................................................16
6.1.2 Implementation....................................................................................................................................16
6.1.3 Implementation Schedule....................................................................................................................16
6.1.4 Compliance..........................................................................................................................................16
Figures
Figure 1 Wastewater Utility Service Area'....................................................................................................................5
Figure 2 East WRF Environmental Survey Area(Project#1).......................................................................................8
Figure 3 West WRF Environmental Survey Area(Project#2)....................................................................................10
Appendix
Appendix A City of Winter Springs East WRF Conceptual Design Report
Appendix B City of Winter Springs West WRF Conceptual Design Report
Appendix C 2022 Wastewater and Reclaimed Water Master Plan
Appendix D ESA Environmental Constraints Review and the Florida Natural Area Inventory(FNAI)Tracking
List—East WRF
Appendix E ESA Environmental Constraints Review and the Florida Natural Area Inventory(FNAI)Tracking
List—West WRF
Appendix F Present Worth Cost Analysis
Appendix G Advertisement of Public Meeting
Appendix H Summary of Public/Dedicated Revenue Hearing
Appendix I Capital Financing Plan
Appendix J Current User Rate System
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Chapter 1.0 Summary of Findings and Recommendations
This Facilities Plan was prepared by the City of Winter Springs (City) to meet the requirements
of the Florida Department of Environmental Protection (FDEP) State Revolving Fund(SRF)
program for the funding of wastewater improvement projects. The project areas included in this
Facilities Plan are all within City limits.
This Facilities Plan includes two wastewater treatment plant improvement projects. Project 1
provides improvements to the East Water Reclamation Facility (WRF) and Project 2 provides
improvements to the West Water Reclamation Facility (WRF). These two projects are part of
the City's 2022 Wastewater and Reclaimed Water Master Plan (Appendix C). Please note that it
is the City's intent to fund these projects with a combination of SRF and potential federal
funding (ARPA or similar), as well as direct available City funds. The City is currently
estimating to request$50,000,000 in loans for the construction of the two projects.
Negative environmental impacts are not anticipated from the construction of these projects other
than temporary disturbances associated with construction. These projects are not anticipated to
have adverse effects on flora, fauna, threatened or endangered plant or animal species, surface
water bodies, groundwater, prime agricultural lands, archaeological or historical sites,
floodplains, or air quality. In order to complete construction of the new proposed facilities,
limited impacts on wetlands and undisturbed natural areas are expected to occur, as further noted
in the attached documents. These projects do not have any anticipated adverse human health or
environmental effects on minority or low-income communities. Project descriptions and costs are
provided below:
1. East WRF Improvements: Construction of new replacement of a 1.5 million gallon per
day (MGD) BNR facility to improve effluent quality and build redundancy/resiliency
to the plant. The estimated cost for the selected alternative (in 2022 dollars) is
$34,792,000. This cost estimate includes engineering and construction.
2. West WRF Improvements: Construction of new replacement of a 1.5 million gallon per
day (MGD) BNR facility to improve effluent quality and build redundancy/resiliency
to the plant. The estimated cost for the selected alternative (in 2022 dollars) is
$34,792,000. This cost estimate includes engineering and construction.
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Chapter 2.0 Introduction
2.1 Background
The City of Winter Springs (City) is located within Seminole County in Central Florida. The
City is bordered by the Cities of Oviedo, Maitland, Casselberry, and Longwood. The City of
Winter Springs Public Works Department is responsible for the planning and implementation of
the service area infrastructure needs.
The City owns and operates the East Water Reclamation Facility (WRF) located in the east
portion of the City with a current design capacity of 2.012 million gallons per day (mgd), the
West Water Reclamation Facility (WRF) located in the west portion of the City with a current
design capacity of 2.07 mgd, fifty-one (5 1) lift stations, and approximately 136,000 linear feet
(LF) of force mains. The total City area is approximately 15 square miles, and an estimated
37,291 customers are provided City wastewater services. Figure 1 shows the service area
boundary.
This Facilities Plan was prepared by the City of Winter Springs to meet the requirements of the
Florida Department of Environmental Protection (FDEP) State Revolving Fund (SRF)program
for funding wastewater improvement projects. The project areas included in this Facilities Plan
are all within City limits. The planning period for this Facilities Plan extends through the year
2027. The recommendations of this Facilities Plan are consistent with the City's 2022
Wastewater and Reclaimed Master Plan. The City is also currently updating its Comprehensive
Plan to include the plan for these facilities.
2.2 Project Descriptions and Need
This Facilities Plan includes the wastewater treatment facility improvement projects listed below.
Project 1 provides improvements to the existing East WRF, and Project 2 provides improvements
to the existing West WRF.
1. East WRF Improvements:
Constructed in the mid-1970's, the existing East WRF is comprised of two separate
package treatment plants (circular field erected steel tanks) originally designed to use an
activated sludge process, known as contact stabilization. The facility is permitted for a
flow of 2.012 mgd average annual daily flow (AADF) but currently experiences flows at
approximately half this capacity. The City is consequently paying to operate and maintain
an oversized and outdated facility, which has no built-in reliability/redundancy (i.e., a
single treatment process cannot be taken offline without taking the whole basin/package
plant out of service). Furthermore, the package plants at the East WRY have experienced
numerous challenges and failures, and are currently under consent order issued by the
FDEP (OGC Case #21-0790).
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The City recently contracted with Carollo Engineers, Inc. to complete the conceptual
design for the proposed East WRY as part of the East WRF Conceptual Design Report
(CDR), dated April 2022 (see Appendix A). Carollo Engineers, Inc. and Wekiva
Engineering conducted assessments of the existing East WRF as part of the project and
concluded that no major component has permanent value worth restoring.
Based on the condition of the current facility, the East WRF CDR focuses on the
construction of new replacement of the East WRF. The goal is to conceptualize a new
facility which can meet current and future water quality requirements while planning for
growth over decades to come. This facility should also be built for resiliency and
reliability, such that the City does not experience the current facility challenges again.
The City plans to "right-size" the proposed facility and replace the existing East WRF
with a 1.5 mgd BNR facility. The proposed East WRF will also include new headworks
screening and grit removal, a new odor control facility, new secondary clarifiers, a
chlorine contact basin, new disk filters, pump stations, and electrical, chemical, and
administrative buildings. The estimated conceptual construction cost for this project is
$34,792,000. This cost estimate includes engineering and construction.
2. West WRF Improvements:
Constructed in the late-1980's, the existing West WRF is comprised of two separate
package treatment plants (circular field erected steel tanks) originally designed to use an
activated sludge process, known as contact stabilization. The facility is permitted for a
flow of 2.07 mgd AADF but currently experiences flows at approximately half this
capacity. The City is consequently paying to operate and maintain an oversized and
outdated facility, which has no built-in reliability/redundancy(i.e., a single treatment
process cannot be taken offline without taking the whole basin/package plant out of
service). Furthermore, the package plants at the East WRF have experienced numerous
challenges and failures, and are currently under consent order issued by the FDEP (OGC
Case #21-1055).
The City recently contracted with Carollo Engineers, Inc. to complete the conceptual
design for the proposed West WRF as part of the West WRF Conceptual Design Report
(CDR), dated April 2022 (see Appendix B). Carollo Engineers, Inc. and Wekiva
Engineering conducted assessments of the existing West WRF as part of the project and
concluded that no major component has permanent value worth restoring.
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Based on the condition of the current facility, the West WRF CDR focuses on the
construction of new replacement of the West WRF. The goal is to conceptualize a new
facility which can meet current and future water quality requirements while planning for
growth over decades to come. This facility should also be built for resiliency and
reliability, such that the City does not experience the current facility challenges again.
The City plans to "right-size"the proposed facility and replace the existing West WRF
with a 1.5 mgd BNR facility. The proposed West WRF will also include new headworks
screening and grit removal, a new odor control facility, new secondary clarifiers, a
chlorine contact basin, new disk filters, pump stations, and electrical, chemical and
administrative buildings. The estimated conceptual construction cost for this project is
$34,792,000. This cost estimate includes engineering and construction.
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Chapter 3.0 Environmental Impacts
3.1 Environmental Review—Project#1 East WRF Improvements
An environmental review of the site was completed based on the planned facilities concept.
Environmental Science Associates (ESA) reviewed the environmental constraints associated
with the concept for the area shown in Figure 2. Appendix D includes the ESA environmental
constraints review and the Florida Natural Area Inventory (FNAI) tracking list. Minor site
constraints, including wetland impacts in some areas of construction, will need to be addressed
during design.
The following items are addressed to meet state, federal and potential funding requirements:
• List threatened, endangered,proposed, and candidate species and designated
critical habitats that may be present in the project area (may be obtained from
U.S. Fish and Wildlife Service). A list of potential threatened, endangered, proposed,
and candidate species and designated critical habitats that may be present within the
general area of the proposed Project is attached as Appendix D, Florida Natural Areas
Inventory. Habitat for many of these species, does not exist within the Project review
area, except for the Bald eagle (Haliaeetus leucocephalus) and gopher tortoise (Gopherus
polyphemus), as identified in the General Environmental Constraints Review
(Appendix D). The Audubon Florida EagleWatch Nest Locator database identified no
nest trees within 600-feet (protective nest buffer zone) of the Project review area,
therefore impacts to the bald eagle are not anticipated. Additionally, during the
environmental review, no gopher tortoise burrows were observed within or directly
adjacent to the Project area. However, a 100-percent gopher tortoise burrow survey will
need to be performed within the upland limits of proposed Project footprint, at least
90 days from construction initiation, in accordance with the Florida Fish and Wildlife
Conservation Commission gopher tortoise survey and permitting guidelines (reference in
Rule 68A-27.003, Florida Administrative Code). No other listed species, or critical
habitat was observed or identified within the property limits.
• Discuss any significant adverse effects upon flora, fauna, threatened or endangered
plant or animal species, surface waterbodies, prime agricultural lands,wetlands, or
undisturbed natural areas. No listed flora or faunal species were identified within the
attached Environmental Constraints Review (Appendix D). The proposed Project is
anticipated to impact approximately up to 2 acres of forested wetlands that were
identified as medium quality and jurisdictional to the state and federal agencies. Other
areas that may be impacted from the Project activities include highly disturbed,
maintained upland areas that are inclusive of the treatment facility. No other undisturbed
natural areas exist within the footprint of the proposed Project. The facility is located
within the City of Winter Springs Planned Unit Development(PUD) Zone; therefore,no
prime or unique agricultural lands exist within the proposed Project footprint.
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• List any significant adverse environmental effects and what project features will
mitigate such effects. It is anticipated that the Project activities will impact
approximately up to 2 acres of medium quality forested wetlands. During the final design
phase of the Project, all impacts will be minimized, where feasible, to further reduce the
footprint and the Project impacts. Additionally,preliminary project corridor analysis
indicates that on-site mitigation will be possible. All construction activities will obtain
and comply with National Pollutant Discharge Elimination Systems (NPDES)permits
and employ Best Management Practices to assure no impacts to water resources during
construction. The site development associated with the Project will follow state water
quality and quantity regulations to avoid alteration in drainage patterns, soil erosion or
runoff. The Project will obtain construction and operation phase permits from the
required state and federal agencies and will operate in accordance with all relevant
regulations. In addition, appropriate state and federal permits will be obtained and
mitigation will occur to off-set those impacts. Mitigation options for this area include the
following:
o Utilizing an approved mitigation site within the Lake Jesup Basin.
o Constructing a wetland mitigation site within the Lake Jesup Basin.
o Either enhance and/or preserve City-owned wetlands.
o Utilize land owned or purchased by the City of Winter Springs, or Investigations
with FDEP to utilize an out-of-basin, regionally significant mitigation bank
(within the same watershed— St. Johns River Watershed) with a Cumulative
Impact Analysis.
• Discuss any significant adverse human health or environmental effects on minority
or low-income communities. The East WRF is located in the eastern area of Winter
Springs, primarily surrounded by residential community. Recent data from the
EJSCREEN Census Summary Report(Accessed April 2022) indicated an overall City
population demographic index of 26 percent with 19 percent reported as low-income. For
the immediate area around the East WRF, the demographic index is 16 percent, with
3 percent reported as low-income. All values are under the state and national averages.
Furthermore, this project considers the replacement of an existing WRF with a new
facility. An improved and modernized WRF will benefit the entire community with
improved reliability in wastewater treatment and effluent water quality which meets or
exceeds regulatory requirements. Therefore, disproportionate high or adverse
environmental effects to a minority population are not anticipated.
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EetMR-iew Area
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Figure 2 East WRF Environmental Survey Area (Project#1)
3.2 Environmental Review—Project#2 West WRF Improvements
An environmental review of the site was completed based on the planned facilities concept.
Environmental Science Associates (ESA) reviewed the environmental constraints associated
with the concept for the area shown in Figure 3. Appendix E includes the ESA environmental
constraints review and the Florida Natural Area Inventory(FNAI) tracking list. Minor site
constraints, including wetland impacts in some areas of construction, will need to be addressed
during design.
The following items are addressed to meet state, federal and potential funding requirements:
• List threatened, endangered,proposed, and candidate species and designated
critical habitats that may be present in the project area (may be obtained from
U.S. Fish and Wildlife Service). A list of potential threatened, endangered,proposed,
and candidate species and designated critical habitats that may be present within the
general area of the proposed Project is attached as Appendix E, Florida Natural Areas
Inventory. Habitat for many of these species does not exist within the Project review area,
except for the Bald eagle (Haliaeetus leucocephalus) and gopher tortoise (Gopherus
polyphemus), as identified in the General Environmental Constraints Review
(Appendix E). The Audubon Florida EagleWatch Nest Locator database identified no
nest trees within 600-feet(protective nest buffer zone) of the Project review area,
therefore impacts to the bald eagle are not anticipated. Additionally, during the
environmental review, no gopher tortoise burrows were observed within or directly
adjacent to the Project area. However, a 100-percent gopher tortoise burrow survey will
need to be performed within the upland limits of proposed Project footprint, at least
90 days from construction initiation in accordance with the Florida Fish and Wildlife
Conservation Commission gopher tortoise survey and permitting guidelines (reference in
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Rule 68A-27.003, Florida Administrative Code). No other listed species, or critical
habitat was observed or identified within the property limits.
• Discuss any significant adverse effects upon flora, fauna, threatened or endangered
plant or animal species, surface waterbodies, prime agricultural lands,wetlands, or
undisturbed natural areas. No listed flora or faunal species were identified within the
attached Environmental Constraints Review (Appendix E). The proposed Protect is
anticipated to impact existing parcel area which generally includes primarily disturbed,
maintained upland areas that are inclusive of the treatment facility. No other undisturbed
natural areas exist within the footprint of the proposed Project. The facility is located
within the City of Winter Springs Planned Unit Development(PUD) Zone; therefore, no
prime or unique agricultural lands exist within the proposed Project footprint.
• List any significant adverse environmental effects and what project features will
mitigate such effects. It is anticipated that the Project activities will be located on
primarily existing disturbed, maintained uplands. The parcel is primarily surrounded by
uplands area which consist of residential areas,power easements and previous golf-
course parcel. During the final design phase of the Project, all potential impacts will be
minimized with a site layout which considers use of existing disturbed, maintained parcel
area and minimization to any natural upland areas. All construction activities will obtain
and comply with National Pollutant Discharge Elimination Systems (NPDES)permits
and employ Best Management Practices to assure no impacts to water resources during
construction. The site development associated with the Project will follow state water
quality and quantity regulations to avoid alteration in drainage patterns or soil erosion or
runoff. The Project will obtain construction and operation phase permits from the
required state and federal agencies and will operate in accordance with all relevant
regulations. In addition, appropriate state and federal permits will be obtained where
required.
• Discuss any significant adverse human health or environmental effects on minority
or low-income communities. The West WRF is located in the Western area of Winter
Springs, surrounded by residential community to the North/West and power
easement/vacated golf course property to the South/East. Recent data from the
EJSCREEN Census Summary Report(Accessed April 2022)indicates an overall City
population demographic index of 26 percent with 19 percent reported as low-income. For
the immediate area around the West WRF, the demographic index is 39 percent, with
19 percent reported as low-income. The demographic index is near the state and national
averages, with low income being below average. Furthermore, this project considers the
replacement of an existing WRF with a new facility. An improved and modernized WRF
will benefit the entire community with improved reliability in wastewater treatment and
effluent water quality which meets or exceeds regulatory requirements. Therefore,
disproportionate high or adverse environmental effects to a minority population is not
anticipated.
9
16
t.EGENU _
Wetland Features
OSW Features
Q West WRF Property Boundary/Review Area I__
1• As
17,
Figure 3 West WRF Environmental Survey Area (Project#2)
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Chapter 4.0 Development of Alternatives
4.1 General
An alternatives analysis and cost comparison were performed for each project. The various
factors that affected the decision-making process, which led to each selected alternative and the
rationale for that selection, are discussed in this section.
The options for the East WRF Improvements are:
1. No action.
2. Construct a new BNR facility.
3. Construct a new MBR facility.
The options for West WRF Improvements are:
1. No action.
2. Construct a new BNR facility.
3. Construct a new MBR facility.
4.2 Cost-Effectiveness
Present worth was used to compare the various alternatives developed in this facilities plan. The
capital and O&M costs along with the present worth of all alternatives are presented in
Appendix F.
4.3 East WRF Improvements
4.3.1 No Action
Under this alternative, the City would take no action to replace or address the condition of the
East WRF. In this scenario, the existing ring-steel package plants will continue to deteriorate
until further mechanical, structural and electrical related failures occur, ultimately leading to the
facility's inability to treat wastewater. This would result in negative impacts to the environment
and community. This alternative is, therefore, unviable and was rejected.
4.3.2 Construct a New BNR Facility
Under this alternative, a new BNR facility would be constructed, and the existing treatment
facility will be replaced. The new facility will allow for reliable and effective treatment of
wastewater for the City into the distant future, beyond the 20-year planning horizon. This
alternative also allows for future expansion to meet potential growth and considers future
regulatory changes which may require stricter effluent criteria.
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Furthermore, and as detailed in the attached CDR(Appendix A), the BNR process provides a
proven reliable treatment process which is both common and consistent with the knowledge of
City operational staff. Additionally, this option provides a treatment process which is resilient
and redundant in its ability to meet effluent water quality, and is expected to be lower in both
capital and operational costs compared to the MBR alternative. This alternative was selected as it
aligns with the City's values to provide long-term performance and reliability.
4.3.3 Construct a New MBR Facility
A new MBR facility would be constructed to replace the existing treatment facility under this
alternative, which will allow for reliable and effective treatment of the City's wastewater beyond
the 20-year planning horizon. This alternative also allows for future expansion to meet potential
growth and considers future regulatory changes which may require stricter effluent criteria.
As detailed in the attached CDR(Appendix A), the MBR process provides more advance
technology with a smaller footprint. However, this technology is less popular, as it requires
specialized equipment and training for the City's operational staff.
This option is expected to provide long-term performance and reliability at higher capital and
operational costs compared to the BNR alternative. While this option meets treatment goals, it
does not best align with the City's values and was therefore rejected.
4.4 West WRF Improvements
4.4.1 No Action
Under this alternative, the City would take no action to replace or address the condition of the
West WRF. In this scenario, the existing ring-steel package plants will continue to deteriorate
until further mechanical, structural and electrical related failures occur, ultimately leading to the
facility's inability to treat wastewater. This would result in negative impacts to the environment
and community. This alternative is, therefore, unviable and was rejected.
4.4.2 Construct a New BNR Facility
Under this alternative, a new BNR facility would be constructed, and the existing treatment
facility will be replaced. The new facility will allow for reliable and effective treatment of
wastewater for the City into the distant future, beyond the 20-year planning horizon. This
alternative also allows for future expansion to meet potential growth and considers future
regulatory changes which may require stricter effluent criteria.
Furthermore, and as detailed in the attached CDR(Appendix B), the BNR process provides a
proven reliable treatment process which is both common and consistent with the knowledge of
City operational staff. Additionally, this option provides a treatment process which is resilient
and redundant in its ability to meet effluent water quality, and is expected to be lower in both
capital and operational costs compared to the MBR alternative. This alternative was selected as it
aligns with the City's values to provide long-term performance and reliability.
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4.4.3 Construct a New MBR Facility
A new MBR facility would be constructed to replace the existing treatment facility under this
alternative, which will allow for reliable and effective treatment of the City's wastewater beyond
the 20-year planning horizon. This alternative also allows for future expansion to meet potential
growth and considers future regulatory changes which may require stricter effluent criteria.
As detailed in the attached CDR(Appendix B), the MBR process provides more advance
technology with a smaller footprint. However, this technology is less popular, as it requires
specialized equipment and training for the City's operational staff.
This option is expected to provide long-term performance and reliability at higher capital and
operational costs compared to the BNR alternative. While this option meets treatment goals, it
does not best align with the City's values, and was therefore rejected.
13
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Chapter 5.0 Selected Alternatives
5.1 Description of Proposed Facilities
This section includes a description of the recommended facilities, estimated costs and estimated
operation and maintenance costs. No repair or replacement costs are associated with the
recommended facilities.
5.2 East WRF Improvements
The new East WRF will provide capacity to reliably treat the City's wastewater flows to meet
regulatory requirements through the next 20 years, with the ability to expand to accommodate
future growth. This alternative includes:
• Construction of a new 1.5-mgd BNR facility.
• Construction of new headworks screening and grit removal, odor control facility, primary
treatment basins, secondary clarifiers, a chlorine contact basin, new disk filters,pump
stations, and electrical, chemical, and administrative buildings.
• All ancillary equipment including backup generator, electrical, and SCADA equipment.
• Site, civil and yard piping modifications.
• Demolition and abandonment of existing facilities.
The total estimated combined engineering and construction cost is $34,792,000.
5.3 West WRF Improvements
The new West WRF will provide a facility which is capable of reliably treating the City's
wastewater to meet regulatory requirement. The new facility will provide capacity to treat
anticipated flows through the next 20 years, with the ability to expand the facility where growth
occurs. This alternative includes:
• Construction of new 1.5 mgd BNR facility.
• Construction of new headworks screening and grit removal, a new odor control facility,
primary treatment basins, new secondary clarifiers, a chlorine contact basin, new disk
filters, pump stations, and electrical, chemical, and administrative buildings
• All ancillary equipment including backup generator, electrical, and SCADA equipment.
• Site, civil and yard piping modifications.
• Demolition and abandonment of existing facilities.
The total estimated combined engineering and construction cost is $34,792,000.
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5.4 Cost to Construct Facilities.
The details of construction and the O&M costs for the projects are presented in Appendix F. The
following tabulation presents the total project cost inclusive of the non-construction items.
Please note that it is the City's intent to fund these projects with a combination of SRF and
potential federal funding (ARPA or similar), as well as direct available City funds. The City is
currently estimating to request$50,000,000 in loans for the construction of the two new
wastewater facilities.
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22
Chapter 6.0 Implementation and Compliance
6.1 Public Hearing/Dedicated Revenue Hearing
A public hearing was held on June 13, 2022, to explain the projects and enable public
participation in the final evaluation of project alternatives and costs. Notice of the meeting was
provided in The Orlando Sentinel (Appendix G).
6.1.1 Financial Planning
The Department of Environmental Protection's State Revolving Fund is expected to be the
financing source for these projects. A Capital Financing Plan (CFP)has been prepared to
explain to the public and to the State Agency what the financial impact on the users of the water
system will be. The CFP is shown in Appendix I.
6.1.2 Implementation
The City of Winter Springs has the sole responsibility and authority to implement the
recommended facilities. There are no inter-local agreements necessary for the City to provide
wastewater collection services to the planning area.
6.1.3 Implementation Schedule
The project schedules are listed below:
ACTIVITY ESTIMATED
DATE
Complete design documents July 2023
Obtain permits for construction October 2023
Start construction November 2023
Complete construction November 2026
6.1.4 Compliance
1. Treated wastewater will comply with FDEP standards.
2. The environmental aspects of the proposed facilities are satisfactory.
3. The recommendations of this Facilities Plan are consistent with the City's 2022
Wastewater and Reclaimed Master Plan. The City is also currently updating its
Comprehensive Plan to include the plan for these facilities.
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23
Appendix A
City of Winter Springs East WRF Conceptual Design Report
24
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East Water Reclamation
Incorporated
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V CONCEPTUAL
■ DESIGN REPORT
A•
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Incorporated
1959
City of Winter Springs
East Water Reclamation Facility
CONCEPTUAL DESIGN REPORT
April 2022
This document is released for the
purpose of information exchange review
and planning only under the authority of
Brian J.Graham, April 2022,
State of FL PE No.44683.
26
EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Contents
1.0 Introduction, Summary of Existing Facilities, and Wastewater Flow and
Load Projections 1
1.1 Introduction 1
1.2 Basis for Conceptual Design 1
1.3 Summary of Existing Facility 3
1.3.1 Existing Treatment Process and Effluent Disposal 3
1.3.2 Condition Assessment 5
1.3.3 Site Boundary and Contour Survey 5
1.3.4 Environmental Review 6
1.3.5 Odor Survey 8
1.3.6 Geotechnical Investigation 10
1.3.7 Wastewater Characterization and Population Flow Projections 10
1.3.8 Wastewater Flow and Loading Characterization 10
1.3.9 Population Projections 13
1.3.10 Proposed East WRF Design Capacity 14
2.0 Liquid Stream Alternatives Evaluation
2.1 Evaluation Overview 15
2.2 Selection of Liquid Stream Treatment Alternatives 15
2.2.1 Preliminary List of Potential Process Alternatives 16
2.2.2 Biological Nutrient Removal to Achieve AWT 18
2.2.3 Potential AWT Treatment Alternatives 19
2.3 Descriptions of Proposed AWT-Capable Treatment Alternatives 21
2.3.1 Five-Stage Activated Sludge BNR(5-Stage BNR) 21
2.3.2 Membrane Bioreactor 22
2.3.3 Sequencing Batch Reactor(SBR) 25
2.3.4 Aerobic Granular Sludge—AquaNereda® 27
2.3.5 Ballasted Activated Sludge—NuvodaTM 29
2.3.6 Integrated Fixed-Film Activated Sludge 31
2.4 Structured Decision Analysis 33
2.4.1 Process Evaluation Criteria and Sub-Criteria 33
2.4.2 Paired Comparison Results 35
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
3.0 Shortlisted Alternatives Evaluation 37
3.1 Objectives 37
3.2 Conceptual Design Criteria 37
3.2.1 Influent Flows and Loads 37
3.2.2 Regulatory Requirements 40
3.3 5-Stage BNR Alternative("Buildout"Scenario:2.1 mgd with AWT) 40
3.3.1 Process Design 40
3.3.2 Conceptual Site Layout 45
3.3.3 Hydraulic Considerations 47
3.4 MBR Alternative("Buildout"Scenario: 2.1 mgd with AWT) 49
3.4.1 Process Design 49
3.4.2 Site Layout 54
3.4.3 Hydraulic Considerations 56
3.5 Common Processes and Shared Facilities 56
3.5.1 Odor Control Technology 56
3.5.2 Chemical Systems 56
3.5.3 Reclaimed Water Storage and Reject Storage 59
3.5.4 Solids Handling 60
3.5.5 Potential Industrial Load Influences 61
3.6 Conceptual Level Cost Estimates('Buildout"Scenario) 61
3.6.1 Cost Estimating Accuracy 61
3.6.2 No Action Alternative 61
3.6.3 BNR and MBR Capital Conceptual Cost Estimates 62
3.6.4 Annual O&M Conceptual Cost Estimates 62
4.0 Final Recommendation
4.1 Recommended Alternative 66
4.2 Recommended Plant Capacity and Treatment Standard 66
4.3 Recommended Conceptual Site Layout and Cost Estimate 67
4.4 Funding Considerations 70
4.4.1 SRF Funding 70
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Appendices
AppendixA Existing WRF PFD
Appendix B East WRF Survey
Appendix C Ecological Assessment and FNAI Tracking List
Appendix D Odor Control Assessment
Appendix E CWSRF Planning Document Requirements Checklist
Tables
Table 1 East Permit Renewal Effluent Disposal Site/Water Quality Requirements
Request 4
Table 2 East WRF Hydrogen Sulfide Monitoring Summary 9
Table 3 East WRF Historical Monthly and Annual Average Daily Flows 10
Table 4 East WRF Influent cBOD5 and TSS Concentrations and Loads 12
Table 5 Winter Springs Population and Flow Growth Factors 13
Table 6 5-Stage BNR Fact Sheet 22
Table 7 Membrane Bioreactor(MBR) Fact Sheet 23
Table 8 Sequencing Batch Reactor(SBR)Fact Sheet 26
Table 9 Aerobic Granular Sludge(AGS)Fact Sheet 28
Table 10 Ballasted Activated Sludge(BAS) Fact Sheet 30
Table 11 Integrated Fixed-Film Activated Sludge(IFAS) Fact Sheet 32
Table 12 Major Evaluation Criteria and Corresponding Sub-Criteria 34
Table 13 Major Evaluation Criteria and their Relative Importance 35
Table 14 East WRF Influent Design Flow and Mass Load Peaking Factors 38
Table 15 Conceptual Influent Design Wastewater Flows and Loads 39
Table 16 Headworks Design Criteria for 5-Stage BNR 41
Table 17 Secondary Treatment Design Criteria for 5-Stage BNR 42
Table 18 Filter Design Criteria for 5-Stage BNR 43
Table 19 Chlorine Contact Chamber Design Criteria for 5-Stage BNR 44
Table 20 Headworks Design Criteria for MBR 49
Table 21 Secondary Treatment Design Criteria for MBR 50
Table 22 Chlorine Contact Chamber Design Criteria for MBR 52
Table 23 MBR Chemical Cleaning System 53
Table 24 Supplemental Carbon Storage and Feed Design Criteria 58
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
Table 25 Alum System Design Criteria 58
Table 26 Solids Handling Design Criteria 60
Table 27 AACE International Guidelines for Cost Estimating Accuracy 61
Table 28 5-Stage BNR Conceptual Capital Cost 63
Table 29 MBR Conceptual Capital Cost 64
Table 30 Conceptual Annual O&M Cost Comparison 65
Table 31 1.5 mgd BNR Conceptual Capital Cost 69
Figures
Figure 1 Existing East WRF Process Flow Diagram 3
Figure 2 East WRF Site and Contour Survey 6
Figure 3 East WRF Environmental Survey Area 8
Figure 4 OdaLog Installation Locations at East WRF 9
Figure 5 East WRF Annual Average Daily Flows 11
Figure 6 East WRF Historic Monthly cBOD5 and TSS Loading 12
Figure 7 East WRF Flow Projections 14
Figure 8 Overview of Biological Treatment Technologies for Nitrogen and
Phosphorus Removal from Municipal Wastewater 17
Figure 9 Biological Treatment Technologies for Achieving AWT in Municipal
Wastewater 20
Figure 10 5-Stage BNR Process Flow Diagram 21
Figure 11 Membrane Bioreactor(MBR) Flow Diagram 23
Figure 12 Sequencing Batch Reactor(SBR) Process Flow Diagram 25
Figure 13 Aerobic Granular Sludge(AGS)Process Flow Diagram 27
Figure 14 Ballasted Activated Sludge(BAS) Flow Diagram 29
Figure 15 Integrated Fixed-Film Activated Sludge(IFAS)Flow Diagram 31
Figure 16 Process Alternative Ranking Using Weighted Criteria 36
Figure 17 5-Stage BNR Conceptual Site Layout(2.1 mgd with AWT) 46
Figure 18 Hydraulic Profile for the 5-Stage BNR Alternative 48
Figure 19 MBR Conceptual Site Layout(2.1 mgd with AWT) 55
Figure 20 1.5 mgd Conceptual BNR Site Layout(1.5 mgd) 68
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
Abbreviations
AADF annual average dailyflow
AC acre
AGS aerobic granular sludge
alum aluminum sulfate
AWT advanced wastewater treatment
BAS ballasted activated sludge
BNR biological nutrient-removal
BOD biochemical oxygen demand
Carollo Carollo Engineers, Inc.
CAS conventional activated sludge
CBODS S day carbonaceous biochemical oxygen demand
City City of Winter Springs
cf cubic feet
cfm cubic feet per minute
cfs cubic feet per second
EBPR enhanced biological phosphorus removal
EPA Environmental Protection Agency
EQ equalization
F.A.0 Florida Administrative Code
FDEP Florida Department of Environmental Protection
FOG fats, oils,and grease
ft feet
gpm/ft2 gallons per minute per square foot
HLD high level disinfection
HRT hydraulic retention time
IBC intermediate bulk container
IFAS integrated fixed-film activated sludge
IMLR internal mixed liquor recycle
Ib/d pounds per day
MBR membrane bioreactor
MDF maximum daily flow
MG million gallons
mg/L milligrams per liter
mgd million gallons per day
MLSS mixed liquor suspended solids
MMADF maximum month average dailyflow
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
O&M operations and maintenance
PHF peak hour flow
psig pounds per square inch, gauge
RAS return activated sludge
RFI request for inclusion
rbCOD readily biodegradable chemical oxygen demand
SBR sequencing batch reactor
SCADA supervisory control and data acquisition
Scfm standard cubic feet per minute
SFAS step feed activated sludge
SHT sludge holding tank
SRT sludge retention time
SWD side water depth
TDH total dynamic head
TMP transmembrane pressure
TN total nitrogen
TP total phosphorus
TRC total residual chlorine
TS total solids
TSS total suspended solids
WAS waste activated sludge
WRF water reclamation facility
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
EXECUTIVE SUMMARY
The City of Winter Springs owns and operates the East Water Reclamation Facility(WRF).The
facility is permitted for 2.012 mgd AADF by the Florida Department of Environmental Protection
but currently experiences flows at approximately half this capacity.The East WRF was originally
constructed in the mid-1970s and has consequently reached the end of its useful life, requiring
both replacement and modernization.
Carollo and Wekiva Engineering conducted assessments of the East WRF as part of this project
and the priority repairs projects over the past year and concluded that no major component has
permanent value worth restoring.While some existing infrastructure and minor components
may be rehabilitated and reused,they generally only serve temporary purposes and have no
permanent value.
Based on the condition of the current facility,this CDR focuses on the construction of new
replacement of the East WRF. Specifically,the goal is to conceptualize a new facility which can
meet current and future water quality requirements while planning for growth over decades to
come.This facility should also be built for resiliency and reliability, such that the City does not
experience the current facility challenges again.
To conceptualize the future facility, a boundary survey,ecological assessment,and odor study
were completed as part of this CDR. Carollo then performed an analysis of all liquid treatment
technologies to determine which treatment alternative best suits the City.As part of this
evaluation, Carollo performed the following:
Prepared a working list of liquid-stream technologies proven to meet Advanced
Wastewater Treatment(AWT)standards,
Performed a conceptual-level review of the selected liquid-stream process alternatives,
Developed evaluation criteria to rank each of the process alternatives in terms of their
ability to meet the City's values,
Hosted a paired comparison exercise with a City-appointed selection committee for City
to apply a value(or weight)to each evaluation criterion, and
Shortlisted two alternatives from the working list for further development and in-depth
analysis(i.e., conceptual site layout and capital/operational cost estimate).
The working list of liquid-stream technologies proven to meet AWT included:
Five-stage activated sludge BNR(5-5tage BNR).
Membrane bioreactor(MBR).
Ballasted activated sludge(BAS).
Aerobic granular sludge(AGS).
Sequencing batch reactor(SBR).
Integrated fixed-film activated sludge(IFAS).
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
The paired comparison exercise with the City-appointed selection committee,as well as the
decision analysis, resulted in the list of treatment alternatives below.The alternatives are ranked
from highest to lowest based on the City's applied values:
1. Five-stage activated sludge BNR(5-stage BNR).
2. Membrane bioreactor(MBR).
3. Sequencing batch reactor(SBR).
4. Ballasted activated sludge(BAS).
5. Integrated fixed-film activated sludge(IFAS).
6. Aerobic granular sludge(AGS).
Conceptual designs, site layouts,and capital/O&M cost estimates were developed for the top
two scoring technologies: 5-stage BNR and MBR.The design flows and loads used to compare
the BNR and MBR conceptual designs and costs to provide a final recommendation correspond
to a true"buildout"scenario.This scenario represents what the City may require in the far-term
future, i.e., post-2045, in terms of quantity and quality.These far-term future needs include a
flow of 2.1 mgd AADF, and a production of AWT-quality effluent. However,a final
recommendation for a conceptual East WRF, sized for today's needs, is later provided.
The conceptual capital cost estimates for the 5-stage BNR and MBR alternatives at"buildout"
(2.1 mgd with AWT)are approximately$48,082,000 and $53,922,000, respectively.The MBR
alternative proved slightly more costly than the BNR(as the MBR alternative requires additional
fine screening,flow equalization, increased chemical storage,etc.).An annual O&M comparison
shows that the MBR alternative is also more costly to operate and maintain, costing
approximately$150,000 more than the 5-stage BNR alternative on an annual basis. Class 5
accuracies were used to determine the conceptual cost estimates and have a 20 percent
contingency applied due to the conceptual level of design.
Both BNR and MBR are established technologies in the United States,with a track record of
successfully meeting stringent nutrient discharge limits. However, 5-stage BNR is known as the
"Gold Standard"of CAS technologies and is more highly implemented in Florida,creating a
large, local resource pool for operators to turn to when in-need of support.Additionally,the
5-stage BNR process is similar to current operations and does not require a high degree of
additional operator training. On the other hand,while MBR has a smaller footprint in comparison
to the 5-stage BNR, it requires a higher pumping/energy and chemical use, and more mechanical
equipment,which ultimately creates more required maintenance. Based on these non-economic
factors, as well as the conceptual capital cost estimates, it is recommended that the City select
the 5-stage BNR alternative as the proposed treatment process for the East WRF.
Limited growth is expected within the City of Winter Springs over the next 20 years. Results from
the population analysis indicated that 2045 flows may range anywhere from 1.04 to 1.43 mgd
AADF.Additionally,the"City of Winter Springs 2022 Wastewater and Reclaimed Water Master
Plan"prepared by Kimley-Horn projects that population growth within available parcels and
potential septic to sewer conversions may result in flows up to 1.49 mgd over the next 20 years.
Both projections are far less than the current permitted capacity of 2.012 mgd.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Rather than designing, constructing, and paying for an oversized facility today, and
consequently having to operate and maintain the oversized facility, Carollo recommends that
the City"build for today but plan for tomorrow"(i.e., right-size the WRF for near-term growth).
To elaborate, since flows are not expected to surpass 1.49 mgd AADF in the next 20 years,
Carollo recommends that the proposed East WRF be designed for a capacity 1.5 mgd AADF,
while also allocating space onsite such that the capacity can be readily expanded to meet future
needs.Additionally, because AWT is not required today, it is recommended to phase the
construction process to ensure current treatment standards are being met but allow AWT
build-out to meet future requirements.
A proposed conceptual site layout for this 1.5 mgd scenario(to meet today's treatment
standards)was developed. It is recommended that the City initially construct a facility based off
of this conceptual design and modify as needed to meet future quantity and quality needs,
ultimately to the full buildout scenario of 2.1 mgd with AWT(if required).
The conceptual capital cost estimate forthe recommended 1.5 mgd East WRF is approximately
$34,792,000. By right sizing the East WRF fortoday's needs,the City would save approximately
$13 million dollars,today, on capital costs,with additional savings on annual O&M costs.The
City would also have the flexibility, reliability, and redundancy to take basins offline,while still
operating efficiently and meeting effluent requirements.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.0 Introduction, Summary of Existing Facilities, and
Wastewater Flow and Load Projections
1.1 Introduction
The City of Winter Springs(City)owns and operates two Water Reclamation Facilities(WRF):the
East(FLA011068)and West(FLA011067)WRF.The East WRF consists of two separate package
wastewater treatment plants(WWTPs), known as WWTP No.1 and No. 2.These plants were
constructed in the mid-1970s and early 1990s, respectively,and have a total combined capacity
slightly above 2 mgd.These plants,and the entire east facility, have reached the end of their
useful life and require replacement. Carollo Engineers, Inc.(Carollo) has been tasked with
assessing and summarizing the current facility, and further recommending two treatment
process alternatives for the City to incorporate in the design of their new WRF.
Rather than replacing the East WRF in-kind,the proposed plant process will be planned for the
future ability to meet more stringent treatment requirements and effluent criteria,which will
inevitably be required with future environmental regulations.The purpose of this Conceptual
Design Report(CDR) is to provide the City with two proposed treatment process alternatives for
the new East WRF, and a final recommendation with an associated conceptual design, site
layout,and cost estimate.This CDR will form the basis for the subsequent detailed design,
permitting, bidding, and construction phases of the new facility construction. Overall goals of
this project are to provide a new wastewater facility that is reliable, meets current regulations
with the ability to achieve future regulations,aligns with the City's growth and associated
treatment needs,and emphasizes City values.
1.2 Basis for Conceptual Design
The East WRF currently operates as a secondary wastewater treatment facility under the Florida
Department of Environmental Protection's(FDEP)domestic wastewater facility permit
No. FLA011068.The facility is permitted to treat annual average daily flows(AADF)of up to
2.012 mgd but experiences flows at approximately half of this capacity.
The existing treatment processes at the East facility provide the level of treatment required for
its effluent to meet the following water quality requirements under the current permit:
A 5-day carbonaceous biochemical oxygen demand(cBOD5)concentration of less than
or equal to 20 milligrams per liter(mg/L),when calculated as an annual average.
A total suspended solids(TSS)concentration of less than or equal to 5 mg/L for any
single sample.
A total residual chlorine(TRC)concentration of 1 mg/L, minimum,for any single sample.
A total nitrate, as nitrogen(NO3-—N)concentration of less than or equal to 12 mg/L for
any single sample.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
The FDEP sets forth the regulatory requirements for effluent discharges from wastewater
treatment facilities and addresses end-use effluent water quality standards. Effluent disposed via
public access reuse(PAR) has higher disinfection requirements compared to non-beneficially
discharged effluent. Furthermore, effluent that is discharged for groundwater recharge and
surface water discharges in protected watersheds typically require the achievement of the
highest level of wastewater treatment, known as Advanced Wastewater Treatment(AWT).AWT
is defined in F.S.403.086(4)(a)and requires that wastewater be treated beyond the secondary
state, providing an effluent that has annual average values, including:
A 5-day cBODS concentration of less than or equal to 5 mg/L,
A TSS concentration of less than or equal to 5 mg/L,
A total nitrogen(TN)concentration,expressed as nitrogen, of less than or equal to
3 mg/L,
A total phosphorus(TP)concentration, expressed as phosphorus, of less than or equal to
1 mg/L,and
Received high-level disinfection(HLD)as stated in 62-600.440 Florida Administrative
Code(F.A.C.). HLD requires an effluent which meets the following criteria:
Any single sample shall not exceed 5 mg/L TSS prior to application of a disinfectant.
Any single sample shall not exceed 25 fecal coliform values per 100 mL of sample.
On a monthly basis, 75 percent of the fecal coliform values shall be below the
detection limits.
When chlorine is used for disinfection, a TRC of at least 1 mg/L shall be maintained
at all times and the minimum acceptable contact time shall be 15 minutes at the
peak hourly flow(PHF).
The current East WRF operations do not include disposal of treated effluent via any methods
that require AWT. However,there are strong indications that state regulatory agencies will enact
future regulations that will require the City to treat its effluent to achieve AWT standards. For
example,the City of Winter Springs is surrounded by protected watersheds defined by the
St.John's River Water Management District(SJRWMD).Any treated effluent applied to these
protected watersheds must be treated to a higher standard,with stricter nutrient limits. Over
time as these protected watershed basins are expanded, it is logical to assume that in the
future,the City may be located within a protected watershed and will be required to treat any
site-applied effluent to the higher standard.Additionally, more stringent treatment standards
are required for Surface Water and Backup Discharges,which are application methods not
currently used by the City but may be in the future.
To summarize, while AWT is not required today,there are strong indications that it will be in the
future. It is recommended that when designing the new East WRF,the City plan for a facility that
does not necessarily meet AWT today, but has the foundation in-place to allow for future
modifications to do so. Consequently,the proposed conceptual designs outlined in this report
are intended to meet current effluent requirements with the ability to be readily modified to
achieve AWT, if required in the future.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.3 Summary of Existing Facility
A condition assessment, as well as various surveys and studies,were conducted to gather an
overall understanding of the facility and the condition of the existing components.The following
subsections summarizes the findings of these assessments and the current condition of the East
WRF.
1.3.1 Existing Treatment Process and Effluent Disposal
The East WRF is comprised of two separate package treatment plants(circular field-erected steel
tanks)originally designed to use an activated sludge process, known as contact stabilization, and
a third concrete tank dedicated to sludge thickening and holding (Digester No.3).The treatment
units consist of a surge tank, influent screening, concentric aeration basins(made up of
reaeration and contact tanks),and a clarifier in the center. RAS is also part of the aeration
process and is provided using air lifts.The clarified effluent then flows from the treatment tanks
to the tertiary moving-bed filters(DynaSand®filters),and finally to the chlorine contact
chamber.A 0.18 million-gallon(MG)concrete sludge digester/holding tank,3 MG covered
reclaimed water(RW)storage tank and combined 5.61 MG combined wet weather and reject
storage pond are all onsite components of the East WRF, as well. Solid residuals are stored in a
sludge holding tank(SHT)that is aerated for mixing and preventing septic conditions prior to
dewatering. Stored solids are dewatered using a mobile belt filter press and then hauled offsite
for processing.A process flow diagram (PFD)of the existing East WRF is included in Appendix A,
with a snapshot shown in Figure 1.
o� �a
------------
d a.
a �
Attachment No.2
PROCESS FLOW DIAGRAM
CITY OF WINTER SPRINGS EAST WRF
Figure 1 Existing East WRF Process Flow Diagram
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
The East WRF supplies PAR-quality effluent to the City's reuse service area for irrigation
purposes.To be considered PAR-quality, reclaimed water must have experienced secondary
treatment, contain no more than 5 mg/L total suspended solids(TSS), and achieve HLD. Effluent
that meets PAR quality but is generated in excess of customer demand(e.g.,during heavy rain
events)is stored onsite at the facility in the GST, and combined wet weather/reject storage
pond.The City also has alternate disposal sites, including the Oak Forest Spray Field land
application site and Owasco rapid infiltration basin(RIB)which can accept 0.201 mgd and
0.61 mgd AADF, respectively. However,these alternate disposal sites are permitted under the
same reuse system, ultimately requiring the same effluent requirements as their primary PAR
disposal method (R-001).Therefore, any effluent that does not meet PAR quality is diverted to
the onsite reject pond—of which 2 MG of the total 5.61 MG is dedicated reject storage.
The current East WRF permit(No. FLA011068)expires in March 2022, and Carollo recently
supported the City on the completion and submission of the facility permit renewal.With the
renewal,the City requested the State to designate the Owasco RIB as a R-003 discharge location
and change the water quality/effluent requirements for discharge to this location. In doing so,
this site(R-003)would be permitted under a separate reuse system and used for disposal of
non-spec effluent which does not meet PAR standards.The East Permit would then match the
permit conditions for non-PAR discharges in the City's West WRF Permit(FLA011067).These
non-par discharge quality requirements are shown below in Table 1.
fable 1 East Permit Renewal Effluent Disposal Site/Water Quality Requirements Request
Site ID Location Effluent Quality Requirement
[cBOD5]<30 mg/L(l)
[TSS]<5 mg/L(l)
R-001 PAR System [TN]—Report
[TP]—Report
Fecal Coliform<25#/100 mL(l)
[cBODS]<30 mg/L(l)
R-002 N/A(5) [TSS]<5 mg/L(2)
Fecal Coliform<200#/100 mL(4)
[cBOD5]<30 mg/L(l)
R-003 Owasco RIBS [TSS]<30 mg/L(2)
[NO3-- N]<12 mg/L(2)
Fecal Coliform<200#/100 mL(4)
Notes:
(1) Monthly Average.
(2) Single Sample Maximum.
(3) Single Sample Maximum(Samples Collected 7 days/week).
(4) Monthly Geometric Mean(Samples Collected Weekly).
(5) The Oak Forest Spray Field has potable wells located within a 500-foot buffer surrounding the site,and consequently,
cannot accept non-PAR quality effluent(FDEP Rule 62-610.421 F.A.C.).
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.3.2 Condition Assessment
Over the past year, Carollo has visited the East WRF numerous times,through which a condition
assessment of the existing unit processes was completed. Part of this assessment has also
included priority repairs to the current facility in order to maintain operation until the facilities
are permanently replaced. Since the facility was originally constructed in the mid-1970s(with an
expansion in the early-1990s),a majority of its components have reached the end of their useful
life and are visibly degraded/corroded.As a subconsultant to Carollo,Wekiva Engineering also
performed a structural assessment of the primary assets at the East WRF in December 2021 and
concluded that no major component at this facility has permanent value worth restoring.While
some existing infrastructure and minor components may be rehabilitated and reused,they may
only serve temporary purposes and have no permanent value. One exception to this is the
existing chlorine contact chamber. Structurally,the chlorine contact chamber is in acceptable
condition and could be rehabilitated to lower construction costs, including new repumping
equipment costs. Some components still require replacement,such as the effluent gates.
However,the existing chlorine contact chamber may not fit into the hydraulic profile of the new
East WRF.This must be further analyzed during subsequent design stages.
The existing electrical equipment is also outdated and does not meet current National
Electric Code(NEC).As such,for conceptual design purposes, no unit process equipment
(e.g., mechanical, structural, or electrical assets)will be preserved for the new East WRF.
There are, however,some non-unit process items which have the possibility of being maintained
for storage purposes, including the reuse GST, onsite storage/reject pond,and one of the
three circular steel structures.The GST and storage/reject pond are in good condition overall and
can continue to store treated effluent for the new WRF.One of the three steel structures may
also be repaired or rehabilitated and temporarily used to store solid residuals from the new
treatment scheme,allowing the City time to plan and design for a permanent solids handling
facility. Like the chlorine contact chamber,the feasibility of reusing these existing assets must
be further assessed during later design stages.
1.3.3 Site Boundary and Contour Survey
L&S Diversified(L&S)completed a conceptual-level boundary and topographic survey to
facilitate the planning stages of the project.The established boundary of the East WRF totals
approximately 50.6 acres, although this includes a number of trees and wetlands which have
been preliminarily identified. Figure 2 shows the limits of the site boundary and contour survey.
In addition to displaying boundary lines, easement information, and contour lines,the attached
survey(included in Appendix B), also displays existing buried mains, as well as the elevations of
key hydraulic infrastructure.
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
-4N 2d
Figure 2 East WRF Site and Contour Survey
1.3.4 Environmental Review
An environmental review was completed of the site based on the planned concept facilities.
Environmental Science Associates(ESA)completed an environmental constraints review within
the review area shown in Figure 3.Appendix C includes the ESA environmental constraints
review and the Florida Natural Area Inventory(FNAI)tracking list. In general,and as further
described below,there are minor site constraints which will need to be addressed in design,
primarily including wetland impacts in some areas of construction.
The following items are addressed to meet state,federal and potential funding requirements:
List threatened,endangered, proposed,and candidate species and designated
critical habitats that may be present in the project area(may be obtained from
U.S. Fish and Wildlife Service).A list of potential threatened,endangered, proposed,
and candidate species and designated critical habitats that may be present within the
general area ofthe proposed Project is attached as Appendix C, Florida Natural Areas
Inventory. Habitat does not exist within the Project review area for a majority of these
species, with the exception ofthe Bald eagle(Haliaeetus leucocephalus)and gopher
tortoise(Gopherus polyphemus), as identified in the General Environmental Constraints
Review(Appendix Q.The Audubon Florida EagleWatch Nest Locator database was
reviewed,and no nest trees were identified within 600-feet(protective nest buffer zone)
ofthe Project review area,therefore impacts to the bald eagle are not anticipated.
Additionally, during the environmental review, no gopher tortoise burrows were
observed within or directly adjacent to the Project area. However,a 100-percent gopher
tortoise burrow survey will need to be performed within the upland limits of proposed
Project footprint, at least 90 days from construction initiation in accordance with the
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Florida Fish and Wildlife Conservation Commission gopher tortoise survey and
permitting guidelines(reference in Rule 68A-27.003, Florida Administrative Code).
No other listed Species, or critical habitat was observed or identified within the property
limits.
Discuss any significant adverse effects upon flora,fauna,threatened or endangered
plant or animal species,surface waterbodies, prime agricultural lands,wetlands,or
undisturbed natural areas. No listed flora or faunal species were identified within the
attached Environmental Constraints Review(Appendix Q.The proposed Protect is
anticipated to impact approximately up to 2 acres of forested wetlands that were
identified as medium quality and jurisdictional to the state and federal agencies.Other
areas that may be impacted from the Project activities include highly disturbed,
maintained upland areas that are inclusive of the treatment facility. No other
undisturbed natural areas exist within the footprint of the proposed Project.The facility
is located within the City of Winter Springs Planned Unit Development(PUD)Zone;
therefore, no prime or unique agricultural lands exist within the proposed Project
footprint.
List any significant adverse environmental effects and what project features will
mitigate such effects. It is anticipated that the Project activities will impact
approximately up to 2 acres of medium quality forested wetlands. During the final
design phase of the Project,all impacts will be minimized,where feasible,to further
reduce the footprint and the Project impacts.All construction activities will obtain and
comply with National Pollutant Discharge Elimination Systems(NPDES)permits and
employ Best Management Practices to assure no impacts to water resources during
construction.The site development associated with the Project will follow state water
quality and quantity regulations to avoid alteration in drainage patterns or soil erosion or
runoff.The Project will obtain construction and operation phase permits from the
required state and federal agencies and will operate in accordance with all relevant
regulations. In addition, appropriate state and federal permits will be obtained and
mitigation will occurto off-set those impacts. Mitigation options for this area include:
— Utilization of an approved mitigation site within the Lake Jesup Basin,
— Construction of a wetland mitigation site within the Lake Jesup Basin,either
utilizing land owned or purchased by the City of Winter Springs, or
— Investigations with FDEP to utilize an out-of-basin, regionally significant mitigation
bank(within the same watershed—St.Johns River Watershed)with a Cumulative
Impact Analysis.
Discuss any significant adverse human health or environmental effects on minority
or low-income communities.The East WRF is located in the eastern area of Winter
Springs, primarily surrounding by residential community. Recent data from the
EJSCREEN Census Summary Report(Accessed April 2022) indicates an overall City
population demographic index of 26 percent with low income being 19 percent. Forthe
immediate area around the East WRF,the demographic index is 16 percent,with low
income being 3 percent.All values are under the state and national averages.
Furthermore,this project considers the replacement of an existing WRF with a new
facility.An improved and modernized WRF will benefit the entire community with
improved reliability in wastewater treatment and effluent water quality which meets or
APRIL 2022 17
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
exceeds regulatory requirements.Therefore, disproportionate high or adverse
environmental effects to a minority population is not anticipated.
NReview Area
c GPS Locations ""'`-'�' e,I
Delineated WetlandlOSW Limits
_,I:]Wetland Features •� �,- �- I
•IM OSW Features ! i_:wllc 4 o a
QEast WRF Property Boundary
1 'Jv ° a8 0 ! L
1 - - •�,�+
:. ...._ yiv. ..._ du. : be
4- _ .. ;
-. :!"l ft'.::..l--__`:,:1.'':9"�:�:�•.:::�....9-'MCC:::_:Ir .::_:•:9'llllf._:�:.
,w..>i 300
Feet
Figure 3 East WRF Environmental Survey Area
1.3.5 Odor Survey
Webster Environmental Associates, Inc. (Webster)completed an odor survey at the East WRF in
November 2021.This study was done to assess the Hydrogen sulfide(H2S)gas odor impact on
the local area,for consideration with the design and construction of a new treatment facility.
Hydrogen sulfide occurs naturally in sewers, manure pits,well water,oil and gas wells, and
volcanoes.The health effects of hydrogen sulfide depend on how much H2S a worker breathes
and for how long.The odor threshold for hydrogen sulfide gas falls in the 0.01 to 1.5 ppm range
and some will begin to notice the"rotten egg smell"at these concentrations.The odor becomes
more offensive at 3 to 5 ppm. Prolonged exposure in confined areas at these concentrations may
cause nausea,tearing of the eyes, headaches,or loss of sleep. However, because wastewater
facilities are mainly open to the atmosphere, operators and visitors are generally not at risk for
negative health effects from H2S during routine operation.
Six OdaLogT"' units were installed around the facility and recorded Hydrogen sulfide(H2S)gas
concentrations for nine days.These 0daLogT1 units measure H2S in the range of+/-300 ppb and
were installed at the following locations:flow splitter box/headworks, surge tanks, SHT,
digester,and belt filter press.The sixth OdaLOgT"' unit was installed on a tree outside of the WRF
property, near the public park entrance,to understand how odors may disperse from the
treatment site and migrate to the park area.The locations of each logger are shown graphically
in Figure 4.
APRIL 2022 18
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
East WRF T
Odor Logger Locations --I
=A.
oe eg.
�i 'I OOaL gp5 -Oe L 9Y3 Sug B h Y "
+J '1 -Belt FII %eas Salltl X 1e1 g
/ POtla Leg k6.
h
Figure 4 OdaLog Installation Locations at East WRF
The OdaLogT"' data from the nine-day monitoring period is included in Table 2.All locations
were found to have low to moderate concentrations of H2S(with an average of 0 to 3 ppm),
apart from the surge tank which had very high, brief spikes each day.These spikes then quickly
dispersed,only lasting approximately 5 minutes.They would occur daily between Ilam and 2pm
and range from 100 to 1,200 ppm.While it is not confirmed,one potential cause ofthese brief
spikes could be attributed to the master lift stations experiencing peak flows.A number of
wastewater lift stations discharge directly into the surge tank at the East WRF and because they
likely turn on at the same time during peak flows, high loads will be discharged into the surge
tank at these times.Webster noted that these concentrations are likely to also cause offsite odor
detections.
The park entrance instrument surprisingly recorded two brief spikes of 0.1 ppm,also lasting
approximately 5 minutes,which may be the result of the high H2S coming from the surge tank.A
full copy of the Odor Study report can be found in Appendix D.
Table 2 East WRF Hydrogen Sulfide Monitoring Summary
Instrument Location Instrument ... Duration H2S Av e H2S Peak
Range .. .. ..
Influent Splitter Box 0-1,000 11/10/21 to 11/19/21 0.12 2
Surge Tank 0-1,000 11/10/21 to 11/19/21 3 1201
Thickener Tank 0-1,000 11/10/21 to 11/19/21 0 0
Aerobic Digester Tank 0-1,000 11/10/21 to 11/19/21 0 1
Belt Press 0-200 11/10/21 to 11/19/21 0 7
Park Entrance 0-50 11/10/21 to 11/19/21 0 0.1
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.3.6 Geotechnical Investigation
At the time of this report, no geotechnical investigation has been conducted at the East WRF.
This information will be needed prior to the design stages but is not necessary within conceptual
design.A complete geotechnical survey and determination of structure locations should
therefore be performed as part of the final design.
1.3.7 Wastewater Characterization and Population Flow Projections
Based on the identified service area, population growth,and historical facility flows, a projected
flow was developed for the East WRF to use when sizing the new facility.The following
subsections summarize the existing historical water quality and quantity data,as well as
population projections,to develop design criteria for the future facility, including flows, loads,
and peaking factors.
1.3.8 Wastewater Flow and Loading Characterization
Historical flow data was gathered and analyzed as part of the recently completed East WRF
permit renewal.Table 3 provides historical monthly flows observed at the facility over the past
10 years,as well as minimum, maximum and annual average flows.All data was obtained from
Discharge Monitoring Reports(DMR)submitted by the City to FDEP.
Table 3 East WRF Historical Monthly and Annual Average Daily Flows(')
•nth/Year 2011 20121 114 2015 20161 1 1 • 2020 2021
January 0.99 0.80 1.03 1.10 1.03 0.99 1.02 1.00 1.04 0.97 1.03
February 0.95 0.85 1.00 0.98 0.98 1.03 0.95 0.96 1.10 1.00 1.00
March 0.95 1.03 1.07 1.01 1.05 1.01 0.91 0.96 1.05 1.04 0.97
April 0.91 1.02 1.04 1.00 1.02 1.11 0.98 0.96 1.10 1.05 1.04
May 0.84 0.99 1.08 1.00 1.01 1.05 0.96 0.96 0.99 1.02 0.95
June 0.83 1.05 1.05 0.98 0.92 1.07 0.95 1.06 1.04 0.96 0.94
July 0.90 1.12 1.21 1.01 0.98 0.96 1.10 1.07 1.07 0.90 0.97
August 0.91 1.08 1.17 1.03 1.04 0.96 1.07 1.07 1.05 0.98 1.11
September 0.84 1.17 1.06 1.07 1.13 1.05 1.35 1.04 0.97 1.09 1.13
October 0.96 1.21 1.03 1.12 1.02 1.13 1.16 0.88 1.00 1.03 1.01
November 0.88 1.06 1.10 1.03 1.08 0.99 0.94 1.03 1.00 1.06
December 0.88 1.13 0.98 1.06 1.02 0.99 1.16 1.07 1.00 1.01
Minimum 0.83 0.80 0.98 0.98 0.92 0.96 0.91 0.88 0.97 0.90 0.94
Maximum 0.99 1.21 1.21 1.12 1.13 1.13 1.35 1.07 1.10 1.09 1.13
AADF(2) 0.90 1.04 1.07 1.03 1.02 1.03 1.05 1.01 1.03 1.01 1.01
Notes:
(1) All units offlow are in mgd.
(2) AADF for 2021 is the average from January to October.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Figure 5 is a plot of AADF, long-term average flow, and the permitted capacity at the East WRF.
This figure shows that the yearly AADF never exceeded the permitted capacity of 2.012 mgd
between 2011 and 2021.Additionally,the long-term average flow was 1.02 mgd AADF and the
maximum monthly flow observed was 1.35 mgd over this 10-year period, indicating that East
WRF has operated at roughly half of its permitted capacity.
East WRF
t AA D F ---Long-Term Average - - Perm itted Capacity
2.2
2.0 _ _ _ _ _ _ _ _ _ _ * _ _ _ _ - _ _ _ _ r _ _
1.81.6 - -- -- - - --- I I
Permitted Capacity=2.012 mgd
1.4 - -
E 1.2
c1.0 --- ---- ---
LL0.8 ------- ------------------------------------ ------------------------------- -------------------------------
0.6 Long-Term Average Flow=2.02 mgd ----------------- ------------------------------- -------------------------------
0.4 --------- -------------------------------- ------------------------------- ------------------------------ -------------------------------
0.2 - -
0.0
`lo�yN
Figure 5 East WRF Annual Average Daily Flows
In addition to flows, historical loading information over the past year was compiled for the East
WRF.Table 4 and Figure 6 present average monthly influent cBOD5 and TSS concentrations and
loadings observed at East WRF between October 2020 and October 2021. No influent TN and TP
data was available as these parameters are not required to be monitored in the facility's influent
under its current permit. Consequently, industry standard ratios of 1:5 and 1:11 were used for
TKN:cBOD5 and TP:cBODS, respectively. It should be emphasized that these factors should be
refined during later design stages following a detailed influent sampling campaign.
Influent TSS and cBOD5 both exhibited similar trends, with maximum loads observed in
February 2021 and average annual loads of 1,970 and 1,980 Ib/d, respectively. Minimum loads
were observed in October 2020 and May 2021.Additionally, a statistical analysis was performed
to remove data outliers prior to calculating the relevant design peaking factors-results of this
analysis are presented in Section 3.2.1 Influent Wastewater Flows and Loads.
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EAST WRF CONCEPTUAL DESIGN REPORT CITY OF WINTER SPRINGS
Table 4 East WRF Influent cBOD5 and TSS Concentrations and Loads
Influent :ODcBC)D5 Influent TSS InfluentTSS
Month/YearConcentration ... . Concentration Loading
lb/day . lb/day
Oct-20 122 1,043 130 1,111
Nov-20 126 1,110 180 1,585
Dec-20 182 1,538 296 2,501
Jan-21 212 1,821 292 2,508
Feb-21 341 2,838 452 3,762
Mar-21 341 2,753 254 2,051
Apr-21 275 2,374 220 1,899
May-21 213 1,682 125 987
Jun-21 322 2,522 260 2,036
Jul-21 276 2,224 266 2,143
Aug-21 228 2,118 266 2,471
Sep-21 188 1,693 61 549
Oct-21 201 1,695 135 1,138
Average 230 1,960 230 1,900
Minimum 122 1,043 61 573
Maximum 341 2,838 452 3,762
East WRF
flnf cBOD5 Load -a-Inf TSS Load
4,000
3,500
3,000
�2,500
02,000
1,500
= 1,000 ---
500
0
Figure 6 East WRF Historic Monthly cBODs and TSS Loading
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.3.9 Population Projections
Population data and projections for Winter Springs were obtained from a combination of reports
prepared by the U.S. Census Bureau and the Bureau of Economic and Business Research(BEBR).
Because the U.S.Census reports current populations on a city-basis,while the BEBR report lists
population projections on a county-basis,a number of assumptions were applied for this analysis
to draw meaningful conclusions from the data available. However,these assumptions were
verified with the analyzed data made by Kimley-Horn in the"City of Winter Springs 2022
Wastewater and Reclaimed Water Master Plan"for consistency and accuracy.Additionally,
internal meetings were held with the City Plannerto gain an understanding of future potential
growth or other wastewater contributors that may impact the East WRF's future wastewater
flows.
One assumption made is that the City of Winter Springs will experience the same growth
projected for Seminole county through 2045, and that wastewater flows would increase
proportional to this population growth.Another assumption was that all of the citizens reported
by the U.S. Census were connected to the City's sewer system, and that the City's wastewater
service area exhibits an even split between East and West WRFs.This even-split assumption is
consistent with the analyzed data within the"City of Winter Springs 2022 Wastewater and
Reclaimed Water Master Plan"prepared by Kimley-Horn.
Based on these assumptions,the growth factors listed in Table 5 were developed and used to
project wastewater flows through 2045. Discussions with the City Planner revealed that
generally limited growth is expected in the near future since no large, new developments within
the City's wastewater service area are currently planned.Additionally, a majority of City property
has been developed and the City does not plan to acquire any considerable portion of additional
land.
Table 5 Winter Springs Population and Flow Growth Factors
Projection Type(')(') 1 1 1 2035 2040 2045
Low Series -1.2% 0.8% 2.3% 3.1% 3.2%
Medium Series 6.0% 10.9% 15.0% 18.5% 21.5%
High Series 12.8% 21.3% 28.9% 35.9% 42.3%
Notes:
(1) All factors shown in the table above correspond to population growth relative to the current Winter Springs population.
(2) Sources:U.S.Census Bureau(2020),Winter5prings population estimates base and BEBR(2020),Projections of Florida
Population by County,2025-2045.
In addition to the factors provided above,an average 2020 wastewater generation rate of
65 gallons per capita per day(gpcd)was calculated for Winter Springs, based on the`even split'
assumption between the East and West WRF.The 65 gpcd is also consistent with the per capita
rates used within the"City of Winter Springs 2022 Wastewater and Reclaimed Water Master
Plan"prepared by Kimley-Horn.The calculated per capita wastewater generation rate is slightly
less than the typical industry standard range of 70 to 80 gpcd for residential communities but
aligns with the City's development projections.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
1.3.10 Proposed East WRF Design Capacity
Figure 7 displays the resulting flow projections for East WRF after synthesizing population data
for Winter Springs from the 2020 BEBR and U.S. Census reports(i.e.,Table 5). Results from this
analysis indicate that 2045 flows may range anywhere from 1.04 to 1.43 mgd AADF,which are
less than the current permitted capacity of 2.012 mgd.Additionally,the"City of Winter Springs
2022 Wastewater and Reclaimed Water Master Plan"prepared by Kimley-Horn projects that if
growth were to occur with available parcels,along with potential septic to sewer conversions,
flow may reach 1.49 mgd over the next 20 years.This CDR considers replacement of the facility
at its current capacity, evaluating a WRF at 2.1 mgd AADF. However, right-sizing the facility to
account for near-term growth will be evaluated in Section 4,the Final Recommendation section.
Low Medium -- High 0 Current AADF
1.5
1.4
1.3
1.2
1.1
1.03
0.9
0.8
0.7
0.6
0.5
2025 2030 2035 2040 2045
Figure 7 East WRF Flow Projections
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.0 Liquid Stream Alternatives Evaluation
2.1 Evaluation Overview
The conversion of the East WRF to an AWT-capable facility requires modernization all of its
existing liquid treatment processes.To determine which treatment alternative best suits the
City, an analysis of all available liquid treatment technologies was completed by the project
team, as well as a thorough and well-vetted selection process based on City values.As part of
this evaluation, Carollo performed the following:
Prepared a working list of liquid-stream technologies proven to meet AWT standards,
Performed a conceptual-level review of the selected liquid-stream process alternatives,
Developed evaluation criteria to rank each of the process alternatives in terms of their
ability to meet the City's values,
Hosted a paired comparison exercise with a City-appointed selection committee for City
to apply a value(or weight)to each evaluation criterion, and
• Shortlisted two alternatives from the working list for further development and in-depth
analysis(i.e., conceptual site layout and capital/operational cost estimate).
It is important to note that the removal of key constituents from domestic wastewater
(i.e., BOD,TSS,TN, and TP)is achieved primarily during a wastewater treatment facility's
secondary treatment process.While an overall,conceptual-level recommendation is provided
within this CDR for the entire East WRF,the paired comparison exercise focused only on the
alternatives for secondary treatment processes and did not compare alternatives for preliminary
treatment, secondary clarification, biosolids handling, odor control, and pumping requirements.
These processes have been analyzed by Carollo and subconsultants,with recommendations
provided in Sections 3 and 4.
2.2 Selection of Liquid Stream Treatment Alternatives
Municipal wastewater treatment plants in Florida rely on a relatively low number of treatment
processes to remove nutrients(e.g., nitrogen and phosphorus). Most of these processes are
variations of the conventional activated sludge(CAS)process, often incorporating different
sequencing and configurations of process tanks with anaerobic, anoxic,and aerobic zones.
However,from a global perspective,a larger number of process configurations for nutrient
removal have been developed and many of these configurations are currently in-service at
municipal wastewater treatment facilities abroad.
When compared to physical or chemical processes, biological processes have generally been
proven to be more economically efficient in removing nitrogen and phosphorus from municipal
wastewater.Additionally, land-based technologies, such as natural or constructed wetlands and
algae scrubbers,are not typically used to remove nutrients from municipal wastewater due to
their very large land requirements and limited operating capacity. Consequently,only biological
treatment-based technologies have been considered in these evaluations.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Biological treatment uses either suspended-or attached-growth processes to maintain biological
activity.These are defined as:
Suspended-growth: Processes that use biomass suspended in wastewater(activated
sludge)to perform the required biochemical transformations. Examples are sequencing
batch reactors using in-basin clarification and continuous-flow reactors using separate
clarifiers or membranes for solids separation.
Attached-growth: Processes that use biomass that attaches to, and forms a film on,
media(i.e., biofilm). Examples are trickling filters, rotating biological contactors,and
packed bed reactors.
Biological processes typically operate in a continuous-flow mode of operation but can also be
operated in a batch-process mode.A recycle stream is typically used to maintain the
microorganism population within the treatment process.The solids retention time(SRT)and
hydraulic retention time(HRT)of the biological processes are critical to achieving the required
secondary treatment.
It should be highlighted that not all biological treatment processes can remove nutrients from
domestic wastewater.To do so, a biological treatment process must foster the growth of certain
microorganism communities.These microorganisms help remove nitrogen through the two-step
process of nitrification and subsequent denitrification:
1. Nitrification: Oxidation of ammonia(NH3)to nitrite(NO2)and then to nitrate(NO3).
2. Denitrification: Reduction of nitrate to nitrite and then to nitrogen gas(1\12).
Biological phosphorus removal, on the other hand, is accomplished through an enhanced
biological process that encourages certain microorganisms to uptake phosphorus in greater
(stoichiometric)quantities than required for their normal growth.When these microorganisms
are wasted from the system, phosphorus removal is achieved, and the overall process is termed
enhanced biological phosphorus removal (EBPR).
2.2.1 Preliminary List of Potential Process Alternatives
To begin, Carollo created an extensive list of biological wastewater treatment technologies
capable of achieving some degree of nutrient removal.This list is referred to as"The Universe of
Alternatives", and includes a broad spectrum of proven technologies that can be grouped
according to the following physical characteristics:
The use of microorganism communities(i.e., suspended growth or attached growth),
The physical configurations of the treatment processes(i.e., land-based,aquatic, or
mechanical facilities),
The location of the solids-separation/clarification unit process,which further categorizes
suspended-growth processes into single-sludge and multiple-sludge systems,
The physical configuration of single-sludge systems distinguished as processes with
multiple stages or phases,and Concentrations of nutrients in sidestreams with separate
sidestream treatment processes required for facilities with significantly elevated
concentrations of nitrogen and phosphorus in their sidestreams.
Figure 8 shows a graphical representation of these groupings.
APRIL 2022 1 16
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.2.2 Biological Nutrient Removal to Achieve AWT
To achieve an AWT-quality effluent, a biological nutrient removal (BNR)process must be
configured with different sequencing and configurations of process tanks with anaerobic(no free
oxygen or nitrate), anoxic(no free oxygen), and aerobic(oxygen rich)zones.These zones create
various degrees of oxidation and reduction potential which favor the growth of specific bacteria
with different capabilities of metabolizing cBOD5, nitrogen,and phosphorus.The primary
purpose of each zone is briefly summarized below:
Anaerobic Zone:Wastewater enters this zone and is depleted of oxygen or oxidized
nitrogen (i.e., nitrate),which allows both the uptake of readily biodegradable organic
material and the release of soluble orthophosphate from by certain microorganisms into
the wastewater.This zone significantly reduces cBOD5 and, in terms of nutrient
removal, mainly serves the purpose of increasing enhanced biological phosphorus
removal(EBPR)efficiency in 02.
Pre-Anoxic Zone:This zone consists of internal mixing to maintain anoxic conditions
and not introduce dissolved oxygen. Mixed liquor from the anaerobic reactor and recycle
flows from the aerobic zone enter this zone while heterotrophic bacteria use the cBOD5
in the wastewater to reduce nitrates recycled back from the aerobic zone to nitrogen
gas.The lack of dissolved oxygen in this zone encourages the biomass to use
chemically-bound oxygen in nitrate for growth,thus removing nitrogen from the system
(i.e.,denitrification).
Aerobic Zone: Following the pre-anoxic zone,the mixed liquor enters the third zone,
which uses supplemental aeration to provide dissolved oxygen to organisms that oxidize
nitrogen in the wastewater from ammonia to nitrites and nitrates(i.e., nitrification).An
internal recycle pump sends a portion of the flow, rich in nitrates and nitrites,to the
pre-anoxic zone for denitrification.This zone also oxidizes any remaining cBOD5 and
removes phosphorus by absorbing orthophosphate in the biomass in excess which is
later wasted as sludge.
Post-Anoxic Zone:This zone further reduces nitrogen in the effluent.Any unreduced
nitrate that was not recycled to the pre-anoxic zone is reduced to nitrogen gas here.
Compared to the first anoxic zone,the denitrification reaction rate within this second
anoxic zone is generally endogenous and slower because of a lower`driving force'due to
the reduced cBODS concentration compared to pre-anoxic zones(most cBODS is
removed in the aeration zone). However,the size of the second anoxic zone can be
reduced by adding an external carbon source such as glycerol or otherforms of
supplemental carbon.
Reaeration Zone:This final zone is a small aeration step that strips nitrogen gas and
inhibits phosphorus release.To remove phosphorus,sludge must be wasted from the
process,typically from the clarifier underflow(i.e.,from the RAS)or in the membrane
tank when membranes are used for solids separation.
As discussed above,the process basins for a BNR configuration have anaerobic zones to
facilitate phosphorus removal,anoxic zones to achieve denitrification, and aerobic zones to
achieve nitrification, phosphorus, and cBOD5 removal.The effluent from the process basins
consists of treated wastewater and suspended solids,which are composed of microorganisms,
biodegradable, and non-biodegradable(inert)matter.These microorganisms consume organics
in the wastewater during their growth process and need to be periodically wasted from the
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
system to maintain a stable biological community in the BNR process.To accomplish this
wasting,effluent is transferred to a subsequent solids separation system(e.g.,secondary
clarifiers or membrane bioreactors)to separate the suspended material from the treated
wastewater. Most of the separated suspended solids are then recycled back to the BNR process
to maintain the desired concentration of microorganisms in the treatment process,while the
remaining suspended solids are wasted from the system via a sludge stream for subsequent
treatment.
There are many process variations to achieve an AWT-quality effluent, each with slight changes
to the arrangement of the process basin zones and the type of solids-liquid separation
employed. However, not all variations can meet the strict effluent limits required for AWT.The
following subsections detail a number of technologies that have proven success with
consistently achieving AWT.
2.2.3 Potential AWT Treatment Alternatives
To prepare a working list of technologies for further evaluations, Carollo refined the initial list of
all available nutrient removal processes shown in Figure 8.As noted in this figure, not all
processes shown are capable of achieving both nitrogen and phosphorus removal. Hence,this
extensive list was shortened to Figure 9 to produce a refined list of technologies that can
consistently meet AWT standards using BNR.
The 5-stage BNR process configuration is the most commonly used technology for achieving
AWT, and was thus selected as the first, baseline alternative for further review.The remaining
alternatives were then selected on the following basis:
National experience and use of the process.
Record of performance for full scale installations.
Representation of viable forms of emerging treatment processes or technologies.
In addition to the 5-stage activated sludge BNR process, Carollo selected viable candidate
processes from Figure 9 that represented processes from the following categories:
Single Sludge: Multiple Stages.
Single Sludge: Multiple Phases.
Ballasted Activated Sludge:Aerobic Granular Sludge.
Ballasted Activated Sludge: Ballasted Activated Sludge.
Attached Growth: Moving Bed.
According to this selection process, Carollo chose the following technologies for further analysis:
Five-stage activated sludge BNR(5-stage BNR).
Membrane bioreactor(M BR).
Ballasted activated sludge(BAS).
Aerobic granular sludge(AGS).
Sequencing batch reactor(SBR).
Integrated fixed-film activated sludge(IFAS).
APRIL 2022 1 19
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.3 Descriptions of Proposed AWT-Capable Treatment Alternatives
This section presents technology fact sheets for each of the six process configurations on
Carollo's working list. Each fact sheet includes the following information:
A brief description of the process.
A simplified process flow schematic that shows the general arrangement of various
secondary-and tertiary-treatment unit processes including recycle streams.
A table of basic facts about the technology, i.e., perceived process reliability, major
advantages and disadvantages, operational considerations, relative energy usage,
footprint,sludge production,chemicals used, and impact on neighbors.
Because it is the most common process for achieving AWT effluent quality and because of the
large number of installations of the 5-stage BNR process, it will be used as a baseline process
that the other process configurations will be compared against.
2.3.1 Five-Stage Activated Sludge BNR(5-Stage BNR)
The 5-stage BNR process is a conventional activated sludge BNR process which is configured
with the five zones as described in Section 2.2.2 and has proven to achieve the strict AWT
effluent requirements. Figure 10 shows the 5-stage BNR process flow configuration while Table 6
outlines additional considerations and information concerning this technology.
IMLR(2Q—4Q) Secondary
Clarifier
Screened,
Degritted,and
Equalized -
Influent(Q)
Anaerobic Pre-Anoxic Aerobic Zone Post-Anoxic Re-air
Zone Zone Zone Zone WAS to Biosolids
Handling Processes
RAS(0)
v
Effluent(Q)to
Disinfection
Deep-bed Filter
Figure 10 5-Stage BNR Process Flow Diagram
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Table 6 5-Stage BNR Fact Sheet
Description
Proprietary Process/Equipment None known. No sole-sourced or proprietary equipment
required.
National Experience/Success Successfully used at many plants in Florida and elsewhere.
Process Reliability Reliable and well-proven in the U.S.
• Consistently meets AWT effluent quality.
• Operational familiarity that does not require additional
Major Advantages training.
• Large local and national peer communities available for
operations to reach out to for troubleshooting.
Major Drawbacks Requires a larger footprint than the other alternatives.
Pre-Treatment Requirements Single-stage screening and grit-removal.
Operational Considerations Similar to current operations.
Possible use of alum or ferric chloride for phosphorus
Chemical Requirements removal during process upsets.
Possible use of supplemental carbon depending on
carbon to nitrogen ratio in the influent wastewater.
Footprint
Larger footprint than those of other alternative
configurations.
Increased WAS production due to nitrogen and phosphorus
Residuals Management removal.This increase is comparable to other treatment
configurations.
Energy Use Moderate energy use compared to other technologies.
Ease of Expansion/Upgrade Expansion requires additional parallel trains.
Impact on Neighbors Noise and odor comparable to those of other configurations.
2.3.2 Membrane Bioreactor
Membrane Bioreactor(MBR) is a variation of BNR in which MBR tanks and equipment replace
secondary clarifiers and tertiary filters. Compared to what is achieved in conventional
clarification processes, an MBR provides a high degree of solids separation and can operate with
much higher MLSS concentrations while also producing effluent with low suspended solids(TSS
<1 mg/L). Unlike activated sludge processes which rely on secondary clarifiers for suspended
solids separation, MBR process basins can operate at significantly higher MLSS concentrations
(6,500 to 7,500 mg/L compared to 2,000 to 4,000 mg/L for CAS systems)and are therefore much
smaller.
Plants operating MBR processes require two-stage screening typically using coarse screens
followed by 2 mm perforated secondary screens to protect the membranes.The membrane
causes a significant head-loss on the forward flows,which requires an additional set of permeate
pumps to convey flows from the membrane tank to the downstream disinfection process.
Figure 11 shows the MBR process flow configuration.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
IMLR(1Q—2Q) Alum or Iron Salt
(As Needed)
Clean in
Ili(2Q-4Q) Place Chemicals
Backpulse and
Screened. _ _
CIP Pumps
Degritted.and - v Effluent(Q)to
Equalized -
Influent(Q) Disinfection
Secondary-Stage Anaerobic Pre-Anoxic Aerobic Zone Post-Anoxic MBR
Screen Zone Zone Zone
d screen)
(2 mm perforate
WAS to Biosolids
Handling Processes
RAS(3Q—SQ)
Figure 11 Membrane Bioreactor(MBR)Flow Diagram
Table 7 outlines additional considerations and information concerning MBR.
Table 7 Membrane Bioreactor(MBR)Fact Sheet
Parameters . •
Each membrane system is unique and proprietary.Over recent years,competition has
increased with multiple manufacturers entering the field,which has driven innovation,
Proprietary changed perceptions,and closed gaps in costs with conventional technologies.
Process/Equipment Hollow-fiber and flat-plate configurations available.
Early selection and procurement are recommended.
National • Well-established and largely successful technology with approximately 500
Experience/Success installations nationally and thousands of installations worldwide.
Process Reliability • Very reliable.
• Consistently produces effluent of very high quality meeting AWT requirements.
• Smallest footprint of all the alternatives.
• Volume of the process basins is relatively small since they can be operated at higher
MLSS concentrations.
Eliminates secondary clarifiers and filtration processes.
Major Advantages Highly automated process.
Helps pre-position future potable reuse options.
Membrane systems have a positive public perception since they are state-of-the-art
technologies.
Improves disinfection efficiency, because of the very low TSS and turbidity in the
effluent.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Parameters Description
More mechanical equipment and maintenance than required for five-stage BNR.
Higher energy use than what's required the five-stage BNR process since the aeration
basins operate with higher MLSS concentrations and have a higher aeration demand.
• Chemical and scouring equipment required to maintain membranes increases energy
costs.
• Higher chemical usage to keep membranes clean.
Major Drawbacks
• Higher pumping than required for five-stage BNR process.
• Flow equalization required to attenuate flow and minimize membrane cost.
• Physical-hydraulic barrier at the membranes can cause hydraulic bottlenecks during
wet weather flows, making flow equalization or membrane redundancy critical.
• Shifts in operational strategies(e.g.,towards automation,analyzers,sensors)can
challenge operations staff.
Fine screenings may result in cBOD5 loss in primary treatment while also requiring
additional screenings-material handling.
Pre-Treatment Two-staged screenings with perforated fine screens(152 mm)to remove fine solids such as
Requirements hair and fibers.
• More mechanical equipment to maintain.
Operational • Automated membrane process.
Considerations Periodic membrane cleaning required.
• Reliable access to the membranes is key.
• Higher chemical use than five-stage BNR process since sodium hypochlorite and citric
Chemical acid are needed to chemically clean membranes.
Requirements
As-needed use of alum or ferric chloride to trim phosphorus.
Footprint Smallest footprint of the configurations or any other proven full-scale biological treatment
technology.
Residuals WAS produced comparable to that of five-stage BNR process.
Management ® Total quantity of solids produced is moderately higherthan that of BNR since
additional screenings material is produced from fine screenings.
Energy Use Higher energy consumption than the five-stage BNR process.
• Expansion requires constructing additional process trains and membrane units.
Ease of P Depending on the initial design of process trains, upgrade,and expansion of the MBRs
Expansion/Upgrade can be modular and may only consist of adding additional membrane units or
cassettes.
Impact on • Noise and odor comparable to those of the five-stage BNR process.
Neighbors Smaller footprint can allow MBRs to be enclosed.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.3.3 Sequencing Batch Reactor(SBR)
SBR is another variation of BNR that accomplishes the 5-stage BNR process through a series of
time steps in a single reactor.Typically, a single cycle for each SBR reactor consists of five steps:
Step 1, Fill: Influent raw wastewater is added to the reactor, and anoxic and anaerobic
conditions are created.
Step 2, React: Influent flow is continuous with aeration applied continuously or
intermittently.
Step 3, Settle:Aeration is stopped, and solids/liquids separation occurs.
Step 4, Draw/Decant: Clarified effluent is withdrawn from the top of the reactor via a
decanting mechanism.
Step 5, Idle: Sludge is wasted.
Figure 12 shows SBR's process flow configuration.Activated sludge aeration and liquid solids
separation occur in the same tank,thus RAS or secondary clarifiers and their associated pumps
are not required. Under SBR,flexibility is allowed in the duration of aerobic and anaerobic phases
to encourage optimum nitrogen and phosphorus removal rates.
Alum or Iron Salt
(As Needed)
Screened,
Degritted,and
Equalized o
Influent(Q) _
Effluent(Q)to
Disinfection
SBR Equalization Deep-bed Filter
Tank
WAS to Biosolids
Handling Processes Surplus Sludge
Figure 12 Sequencing Batch Reactor(SBR)Process Flow Diagram
Table 8 outlines additional considerations and information concerning SBR.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Table 8 Sequencing Batch Reactor(SBR)Fact Sheet
Parameters Descriptio
Proprietary Several SBR equipment manufacturers exist. Process tanks are customizable,
Process/Equipment although some configurations are proprietary.
National More than 1,300 facilities in the U.S., Canada,and Europe employ SBRs.
Experience/Success
Process Reliability Handful of plants in Florida use SBRs and successfully produce effluent
meeting AWT quality.
• Biological treatment and secondary clarification can be achieved in a
single reactor vessel.
Major Advantages SBR processes can handle large seasonal variations in flow and loads.
Process modification is flexible.
No internal MLSS or RAS recycle required so less pumping energy
required than what BNR uses.
• SBR processes are more commonly used at facilities with flowrates of
S mgd or less in the U.S.
• Requires larger-sized blowers than what's used for the five-stage BNR
process.
• Requires flow equalization downstream of the process tanks and
upstream of filters.Without equalization before tertiary filtration,the
filters must be"oversized"to accommodate extremely high peak flows.
Major Drawbacks Sludge settleability can create adverse process conditions.
• Greater operator involvement than what's required for the five-stage
BNR process.
• Some SBR equipment and control systems are proprietary making
repair, replacement,and troubleshooting of control systems difficult
without involving the equipment manufacturer.
• Equipment failure(e.g.,decanter, mixer, aeration systems,etc.)requires
taking the entire SBR process-train offline,affecting redundancy and
available capacity.
Pre-Treatment Traditional screening and grit-removal.
Requirements
Operational Requires a sophisticated system of units and controls,as well as a higher level
of maintenance for controls,switches,and valves, compared to what's
Considerations required for BNR.
Chemical Similar to BNR with as-needed use of alum or ferric chloride for phosphorus
Requirements removal.
Slightly smaller compared to the five-stage BNR process. Secondary clarifiers
Footprint can be removed but footprint is still required for multiple SBR basins.
Residuals WAS produced similar to that of five-stage BNR process.
Management
Energy Use Low to moderate energy use compared to five-stage BNR process.
f o
Ease
Ease of on/Upgrade Fairly modular construction is possible.
Impact on Neighbors Noise and odor comparable to those of five-stage BNR process.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.3.4 Aerobic Granular Sludge—AquaNeredaO
Aerobic Granular Sludge(AGS) is a novel method to remove carbon, nitrogen, and phosphorus in
a single bioreactor.Aerobic granular sludge itself consists of dense granules of mixed microbial
communities that do not coagulate and,therefore,settle much faster than activated sludge
flocs.
The AGS treatment process is similar to that of SBR but operates in three steps:1)fill and draw,
2)react, and 3)settle. Similar to SBR,separate secondary clarifiers or recycling of RAS is not
required.
Compared to the 5-stage BNR process activated sludge,AGS granules settle very rapidly so
process basins can be much smaller.The granules'high settling velocities allow bioreactor
operation at very high MLSS concentrations(8,000 to 12,000 mg/L),thereby reducing the overall
footprint of the process tanks.
The outer layers of the granule are aerobic and support nitrifier growth,while anoxic and
anaerobic zones occur in the center or the granule.As such,AGS can perform carbon removal,
nitrification, denitrification, and phosphorus removal all in one bioreactor.There is currently only
one operating AGS facility in the United States, but there are several operating throughout the
world.
Figure 13 shows the AGS process flow configuration.
Alum or Iron Salt
(As Needed)
Screened,
Degritted,and
Equalized
Influent(Q) -
Effluent(Q)to
c Disinfection
m
io
c
N
3 AGS Reactor Equalization Deep-bed Filter
v
Tank
WAS to Biosolids
Handling Processes
Buffer Tank
Figure 13 Aerobic Granular Sludge(AGS)Process Flow Diagram
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Table 9 outlines additional considerations and information concerning AGS.
Aerobic Granular Sludge(AGS)Fact Sheet
Paramete Description
Proprietary Process/Equipment Limited providers of AGS systems for municipal wastewater
treatment in North America.
National Experience/Success In the U.S,one full-scale AGS facility is in in operation.As of
January 2020,there were over 75 installations worldwide.
Largely unknown.At the time this report was written,there
Process Reliability were no full-scale operating plants in the U.S.that were
treating to AWT standards.
• AGS granules settle faster than five-stage BNR process
sludge,thus requires less reactor volume.
E Process train can be operated at a higher MLSS
Major Advantages concentration than what can be done with five-stage
BNR process without affecting performance.
Requires no internal MLSS or RAS recycle so demands
less pumping energythan what five-stage BNR process
uses.
• Local and national peer communities not available for
operations to reach out to for troubleshooting.
Proprietary dependence to operate and troubleshoot
equipment.
Limited national presence.
Major Drawbacks Largely unknown process.
Multiple means for a single point of failure with higher
consequences of failure.
Process failure requires taking the entire AGS process-
train offline,affecting redundancy and available
capacity.
Pre-Treatment Requirements Single-stage screening and grit-removal.
Operational Considerations Largely unknown process. Operational requirements were
unknown when this report was written.
Chemical Requirements Similarto those of BNR with as-needed use of alum orferric
chloride for phosphorus removal.
Footprint
Slightly smaller compared to that of five-stage BNR Modified
BardenphoT" process.
Residuals Management WAS produced similar to that of five-stage BNR process.
Energy Use Slightly less energy use compared to what five-stage BNR
process uses due to reduced pumping requirements.
Ease of Expansion/Upgrade Fairly modular construction is possible.
Impact on Neighbors Similarto those of five-stage BNR process.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.3.5 Ballasted Activated Sludge—NuvodaTM
Ballasted Activated Sludge(BAS)is based on BNR with one variation:the addition of ballasting
material to the process tanks.The ballast material supplements BNR by significantly improving
the settleability of MLSS in the secondary clarifiers,which allows for higher operational MLSS
concentrations in the process tanks without stressing the secondary clarifiers.
There are several types of ballast material, ranging from the traditional material Magnetite to
more novel organic media like Kenaf. Magnetite is an inert,fully-oxidized, and very fine
magnetic iron material that requires intense mechanical equipment to separate the ballast
media from the waste stream. Kenaf, on the other hand, is a naturally occurring lignocellulosic
material harvested from the rapid-growing Kenaf plant(Hibiscus Cannabinus)that is recycled
with less energy-intensive equipment from the waste stream compared to Magnetite. New
ballast is introduced to the system via a ballast-mixing tank and is recovered from the WAS
streams using recovery drums,which then feed the recovered material back into the
ballast-mixing tank. New ballast is reintroduced to the process stream with the RAS flow to
compensate for any ballast lost through the wasting process since the ballast recovery is not
100 percent efficient. Because BAS can improve the capacity of existing process tanks without
modifying its footprint, it is highly suited as a retrofit process.
Figure 14 shows BAS'S process flow configuration.
MOB"Media WAS Screens
(as needed)
—4
Ultimate
IMLR(2Q-4Q) WAS Disposal
Screened,
Degritted,and Clarifier
Equalized Effluent(Q)to
Influent(Q) Filtration
Anaerobic Pre-Anoxic Post-Anoxic Re-air
Zone Zone Aerobic Zone Zone Zone
RAS WAS
Figure 14 Ballasted Activated Sludge(BAS)Flow Diagram
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Table 10 outlines additional considerations and information concerning BAS.
Table 10 Ballasted Activated Sludge(BAS)Fact Sheet
Parameters Description
BAS sidestream includes the ballast-mixing tank,dispersion mills,and recovery
Proprietary
Process/Equipment drums,which are proprietary equipment.Some examples of ballast material are
magnetite and kenaf.
National Experience/Success No BAS plants in Florida but there are several successful BAS plants across the US.
Process Reliability Comparable to the five-stage BNR process.
• BAS process can meet AWT effluent water quality goals.
Major Advantages Volume of the process basins is reduced when compared to that of BNR since
the basins can be operated at higher MLSS concentrations.
• Local and national peer communities not available for operations to reach out
to for troubleshooting.
Shift in operational strategies and additional operations training required to
operate the ballast-recovery equipment.
Proprietary dependence to operate and troubleshoot equipment.
Limited national presence.
Major Drawbacks Ballast recovery rates are not 100 percent,so new ballasts are required on an
on-going basis to replenish the wasted amounts. Depending on recovery rates,
sizing of the system,and shipment availability, ballast replenishment can be
an expensive O&M item.
More mechanical equipment and maintenance needed than what's required
for BNR.
• More pumping than what's required for the five-stage BNR process.
Single-stage screening and grit-removal.Second stage(fine screening)is
Pre Treatment
Requirements preferred. In the absence of fine screening upstream of the WAS,dedicated WAS
screening may be required.
• Proprietary dependence to operate and troubleshoot equipment.
Operational Considerations - Ballast and MLSS concentrations must be monitored to schedule ballast
shipments.
Chemical Requirements Similartothe five-stage BNR process.
Comparable to BNR. Process basins are smaller than what's used for BNR, but the
Footprint reduced footprint is Offset by the space needed for ballast-recovery equipment
and ballast-storage areas.
Residuals Management WAS contains irrecoverable ballasts,which may help with thickening. However,
total solids produced will be higher compared to what's produced in BNR.
Energy Use Higher energy consumption than what's consumed for the five-stage BNR process
due to the ballast-recovery equipment.
• Expansion requires additional parallel trains.
Compared to the five-stage BNR process,additional considerations are
Ease of Expansion/Upgrade required due to the use of ballast-recovery equipment(shear mills, larger and
additional magnetic drums, larger and additional ballast tanks,and additional
pumps).
Noise and odor comparable to those of the five-stage BNR process.
Impact on Neighbors Ballast system equipment can be contained in a building but will result in
additional truck traffic to the facility.
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
2.3.6 Integrated Fixed-Film Activated Sludge
Attached-growth processes,when coupled with suspended-growth processes, provide enhanced
nutrient removal. Integrated fixed-film activated sludge(IFAS)is one such process in which
attached-and suspended-growth biomass is combined within the same reactor.
In IFAS,floating or fixed media is introduced inside the aeration tanks.The combination of
suspended and attached biomass results in a concentration of biomass that is significantly higher
than what can be expected in a suspended-growth process alone.This provides two important
benefits. First,the required volume of the aeration tank is substantially reduced. Second,the
attached biomass places no additional load on the final clarifiers, so the solids loading to the
clarifiers is substantially reduced when compared to what's imposed by a suspended-growth
process with the same SRT.
Figure 15 shows the IFAS process flow configuration.
Screen Wall to Retain Media in Aerobic Zone
IMLR(2Q—4Q) Alum or Iron Salt
(As Needed) Aerobic Reactor with IFAS Media
Screened,
Degritted,and
Equalized -
Influent(Q) ti
Anaerobic Pre-Anoxic Aerobic Zone Post-Anoxic Re-air
Zone Zone Zone Zone
v
Effluent(Q)to ��,��,��,��,��,��,�,,��,��,��,��, Secondary
Disinfection Clarifier
Deep-bed Filter WAS to Biosolids
Handling Processes
RAS(Q)
Figure 15 Integrated Fixed-Film Activated Sludge(IFAS)Flow Diagram
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EAST WRF CONCEPTUAL DESIGN REPORT I CITY OF WINTER SPRINGS
Table 11 outlines additional considerations and information concerning IFAS.
Table 11 Integrated Fixed-Film Activated Sludge(IFAS)Fact Sheet
Parameters Description
Proprietary There are several WAS media and equipment manufacturers, but most are
Process/Equipment unique and proprietary.Available types of media include rope,sponge carriers,
hard plastic carriers,trickling filter media, kenaf, and flat sheets.
National
Experience/Success Many installations in the US with more widespread use in Europe.
Process Reliability Comparable to that of five-stage BNR process.
• Reduced solids loading to clarifiers due to retained biomass in aeration
Major Advantages basins.
Volume of process basins is reduced compared to that of five-stage BNR
process since the basins can be operated at higher MLSS concentrations.
• Higher dissolved-oxygen concentrations are required in the aerobic tanks
resulting in higher energy usage than what five-stage BNR Uses.
Additional screens are required in the process tanks to retain media in the
tanks.Additional pumping within the process tanks may be required to
move any media clogged on the screens.
Major Drawbacks Forward flow velocity through the process tanks is critical to prevent
unequal distribution of media within the tanks.
Proprietary dependence to replace the media and troubleshoot.
Taking basins offline for maintenance is problematic since media must be
removed.
Pre-Treatment Single-stage screening and grit-removal is adequate. Screening size depends on
Requirements
the type of media used. Fine screening may be necessary to prevent blinding of
media-retaining screens.
• Normal life-expectancy of the media is 10 to 30 years depending on the
media.
Proprietary dependence to replace the media and troubleshoot.
Operational Considerations Media retaining screens affect additional hydraulic losses.
Potential for plugging and media-clogging in the media-retaining screens
thus requiring more maintenance.
• Maintaining the aeration system requires media to be removed and
displaced.
Chemical Requirements Similartothoseoffive-stage BNR process.
Footprint Smaller than that of the five-stage BNR process but larger than that of MBR.
Residuals Management Similar to that of five-stage BNR process.
Higher energy consumption than that of the five-stage BNR process.The
Energy Use attached biomass requires higher dissolved-oxygen concentrations,thus
lowering the field-oxygen transfer efficiency.Additional pumping inside the
process basins may result in higher energy demand.
Ease of Expansion/Upgrade Expansion requires additional parallel trains.The capacity of the existing
tankage could be increased to a certain point by introducing additional media.
Impact on Neighbors Similarto those of five-stage BNR process.
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2.4 Structured Decision Analysis
A structured decision analysis was used to characterize the AWT-capable treatment process
alternatives and rank them according to their ability to meet a prioritized set of evaluation
criteria established by the City and Carollo.These five evaluation criteria include:
1. Established Technology,
2. Treatment Effectiveness,
3. Operability,
4. Constructability and Sequencing (Implementability), and
5. Footprint and Flexibility for Future Upgrade.
The City selected a committee to participate in a paired comparison exercise where values(or
weights)were applied to each of the evaluation criterion.These weights ultimately established
the relative importance of each criterion to use in evaluating and comparing the liquid stream
process alternatives.The weighted scores developed by the selection committee were combined
with technical criteria developed by Carollo(representing each alternative's ability to satisfy the
criteria/sub-criteria)in a decision model.The decision model calculated a unitless"decision
score"and the alternative that best satisfies the most valued criteria(according to the City's
selection committee)received the highest score.The top two alternatives are further evaluated
in Section 3 of this CDR and include conceptual site layouts and cost estimates(including present
worth).
The evaluation criteria set did not include any economic factors such as capital and operating
costs.Although these costs will be evaluated for the two shortlisted technologies(in Section 3 of
the report), it was intentional to exclude these from the evaluation criteria. Doing so eliminated
any financial bias or appeal for the City to select the"cheapest"alternative.
2.4.1 Process Evaluation Criteria and Sub-Criteria
To effectively measure the performance of each alternative against the five established criteria,
additional sub-criteria were developed to provide a further breakdown for evaluation.The
importance of each sub-criterion was assigned a numerical value by a team of senior wastewater
process specialists within Carollo according to understanding of key project drivers and industry
standards.The sub-criteria were presented to the City's appointed scoring committee and
given as a rubric to follow when the committee completed the paired comparison exercise in
January 2022.Table 12 lists the five major evaluation criteria,along with their corresponding
sub-criteria.
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Table 12 Major Evaluation Criteria and Corresponding Sub-Criteria
Major Criteria Sub-Criteria
1. Established a. Number of installations in the U.S. of similar capacity.
Technology b. Number of installations in Florida of similar capacity.
c. Maturity of process technology.
a. Proven processes and technologies for meeting Florida's AWT
limits.
2. Treatment
Effectiveness b. Robustness of treatment(e.g.,ability to handle a range of influent
conditions;ease of recovery from upset).
c. Redundancy and reliability.
a. Safe work environment,operational flexibility,complexity of
operation,staffing requirements(e.g.,special skills or training),
residuals/process additives production.
b. Process monitoring and control effectiveness(including
industry-recognized process control methods,accessible peers to
3. Operability discuss process control options,and effective troubleshooting
methods established).
c. Chemical requirements.
d. Maintenance requirements(number and complexity of process
equipment components and required frequency of maintenance,
storage requirements(e.g.,for media),special maintenance
equipment).
a. Safe construction.
b. Maintained plant operations, minimize shutdowns
4. Constructability and (phasing/sequencing).
Sequencing C. Potential schedule impacts(e.g., equipment manufacturing and
(Implementability) delivery timeframes).
d. Space requirements for construction.
e. Permitting.
f. OSHA/NFPA requirements.
a. Footprint required.
5. Footprint and b. Expandability.
Flexibility for Future c. Adaptability for potential future regulations or effluent uses.
Upgrades d. Truck traffic impacts.
e. Sustainability(energy use,solids handling).
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2.4.2 Paired Comparison Results
The City formed a selection committee(made up of four City employees of various departments)
to participate in a paired comparison exercise in January 2022. During this exercise,the criteria
were weighted against one another using a paired comparison method. Members of the
selection committee individually and privately scored each of the five criteria against each other
in terms of highest value/prioritization.This ultimately developed the average weight for each
criterion. Results of this exercise are presented in Table 13.
Table 13 Major Evaluation Criteria and their Relative Importance
AverageMajor Criteria Weight(Percent)
1: Established Technology 18
2:Treatment Effectiveness 23
3:Operability 30
4: Constructability&Sequencing(Implementability) 17
5: Footprint&Flexibility for Future Upgrades 12
The City placed the highest value on Operability,followed by Treatment Effectiveness,
Established Technology, Constructability and Sequencing(Implementability), and lastly
Footprint and Flexibility for Future Upgrade. Footprint and size of the plant is not a concern for
the City since the new WRF will be built on the existing plant site and sufficient area is available,
explaining why that criterion has a lower average weight. By placing the highest average weight
on Operability,the City is emphasizing their value in constructing a WRF that is easy and safe for
operators to operate with minimal additional training.
The unweighted scores from Carollo's alternative scoring matrix were then combined with the
weights established by the selection committee and inputted into a decision model.The decision
model calculated a unitless"decision score"and the alternative that best met the most valued
criteria (according to the City's selection committee)received the highest score.
Figure 16 shows the results of the structured decision analysis. Based on the City's applied values
established by the selection committee, 5-stage BNR and MBR were the top two scoring
technologies. Both of these processes are mature,with a track record of successfully meeting
stringent nutrient discharge limits. BNR was considered to be preferable to MBR in terms of
Operability,which is the most important criterion to the City(average weight of 30 percent).
This is partly attributed to the number and complexity of process equipment components
associated with MBR. On the other hand, MBR scored better than BNR in terms of Footprint and
Flexibility for Future Upgrades.AGS(Nereda)and BAS(Nuvoda)were ranked lower than the
other processes, largely because they did not score well relative to Treatment Effectiveness and
Established Technology.
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