HomeMy WebLinkAbout02-2022 MWMC Monthly ReportMWMC Communication Packet
March 22, 2022
Aeration System Study (Project P80100) Memo
Attachment 1—Business Case Evaluation (Executive Summary)
Attachment 2—FY 22-23 Project Sheet P80113 - Aeration System Upgrades (2023-2026)
Regional Wastewater Program Monthly Report— February 2022
The next meeting will be Friday, April 8, 2022 at 7:30 a.m.
Photo by Jim Wilcox
______________________________________________________________________________
M E M O R A N D U M
DATE: March 16, 2022
TO: Metropolitan Wastewater Management Commission (MWMC)
FROM: Barry Mays, Design and Construction Coordinator
SUBJECT: Aeration System Study (Project P80100)
ACTION
REQUESTED: Communication Packet
ISSUE
This P80100 memo with attachments is to provide additional information as requested by the
Commission on January 14, 2022.
BACKGROUND
As set forth in the 2004 MWMC Facilities Plan, the Aeration Basin Improvements was planned to be
completed in two phases. The Phase 1 of design and construction was completed in 2009, this
upgraded the four easterly basins (out of the eight existing basins). Phase 2 was to upgrade the
remaining four westerly basins.
Phase 2 has been changed into more steps:
Step 1 (2020 to 2022) - Evaluation, modeling and optimization of the existing Aeration Systems
based on consultant analysis and recommendations to improve the aeration old/new systems.
Step 2 (2022 to present) – Update the Commission regarding the consultant findings and
recommendations in Step 1.
Step 3 (2022 and 2023) – Begin design phase.
Step 1 of Phase 2 began with the execution of a consultant contract on April 14, 2020, with Brown
and Caldwell after approval of Resolution 20-02. The consultant team has completed their evaluation
of the existing aeration systems and provided consultant recommendations.
Brown and Caldwell provided three alternatives to the project team and answered questions at the
MWMC meeting on January 14, 2022. The three alternatives are as follows:
Memo: Aeration System Study (Project P80100)
March 16, 2022
Page 2 of 3
Alternative 1 (Aeration System Improvements)
Alternative 1 consists of two construction packages:
The first construction package, the Condition Based Rehab Work and
Replacement of substation TU-3 and TU-4, installation second turbo blower, and
various electrical system upgrades to start 2024 and completed by late 2026.
The second construction package, the upgrade of two additional aeration basins
and completed by late 2035.
Alternative 2 (Aeration System Improvements)
Alternative 2 consists of two construction packages:
The first construction package, the Condition Based Rehab Work to start in early
2024 and completed by late 2026. Operate and maintain existing turbo and
centrifugal blowers, and various electrical systems until 2032. This choice is
beyond consultant recommended replacement date.
The second construction package, the upgrade of two additional aeration basins.
The replacement of substation TU-3 and TU-4, installation of a second turbo
blower, and various electrical systems to start early 2032 and completed by 2035.
Alternative 3 (Aeration System Improvements)
Alternative 3 consists of three construction packages:
The first construction package, the Condition Based Rehab Work to start in early
2024 and completed by late 2026.
The second construction package, replacement of substation TU-3 and TU-4,
installation of a second turbo blower, and various electrical systems to start
upgrades sometime after 2027 and be completed before 2032.
The third construction package, the upgrade of two additional aeration basins
and completed by late 2035.
The Commission has received three previous staff memos related to project P80100. The first memo
(February 6, 2020) was for approval of Resolution 20-02 to proceed with the consultant evaluation.
The second memo dated February 4, 2021, was an update regarding the consultant’s preliminary
findings of the aeration system evaluation. The third staff memo for the January 14, 2022 meeting
provided a project update. During the MWMC January meeting staff discussed three alternatives,
cost estimates for each alternative, and consultant recommendations.
DISCUSSION
At the MWMC meeting on January 14, 2022, staff presented Brown and Caldwell’s three alternatives
for improving the existing aeration system. The Commission requested additional information
regarding the project needs, findings and more refined cost estimating of the three alternatives.
Memo: Aeration System Study (Project P80100)
March 16, 2022
Page 3 of 3
Brown and Caldwell submitted the attached Executive Summary with Class 4 cost estimating. This
Executive Summary is from the draft Business Case Evaluation report and should provide a more
detailed understanding of scope of work, associated costs and reasoning for Brown and Caldwell’s
recommendation of Alternative 1 for MWMC consideration. Brown and Caldwell’s evaluation of the
Aeration Basin System resulted in ten Technical Memo submittals. The data from five of the Technical
Memos was used to develop the Business Case Evaluation as noted in the Table of Contents, Section
1.3 of the Executive Summary Attachment.
ACTION REQUESTED
No action requested. Staff plans to seek MWMC upcoming approval to finalize consultant contract
negotiations for design and construction support services related to the attached project sheet
P80113.
ATTACHMENTS
Business Case Evaluation (Executive Summary) – draft dated February 25, 2022
FY 22-23 Project Sheet P80113 - Aeration System Upgrades (2023-2026)
DRAFT REPORT | Prepared for
Metropolitan Wastewater Management Commission
Springfield, Oregon
Aeration Improvements Project-
Business Case Evaluation
February 25, 2022
Attachment 1 - Business Case Evaluation (Executive Summary)
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6500 S Macadam Avenue, Suite 200
Portland, OR 97239-3552
T: 503.244.7005
Aeration Improvements Project–
Business Case Evaluation
Prepared for
Metropolitan Wastewater Management Commission
Springfield, Oregon
February 25, 2022
This is a draft and is not intended to be a final representation
of the work done or recommendations made by Brown and Caldwell.
It should not be relied upon; consult the final report.
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Table of Contents
Executive Summary .................................................................................................................................... vii
1. Introduction and Summary of Previous Work ....................................... Error! Bookmark not defined.
1.1 Project Objectives ....................................................................... Error! Bookmark not defined.
1.2 Report Organization .................................................................... Error! Bookmark not defined.
1.3 Project Work Components .......................................................... Error! Bookmark not defined.
1.3.1 Condition Assessment .................................................. Error! Bookmark not defined.
1.3.2 Process Evaluation and Modeling ............................... Error! Bookmark not defined.
1.3.3 Channel Mixing Evaluation .......................................... Error! Bookmark not defined.
1.3.4 Blower Evaluation ......................................................... Error! Bookmark not defined.
1.3.5 Thermal Load Mitigation .............................................. Error! Bookmark not defined.
1.4 Business Case Evaluation Process and Recommendations .... Error! Bookmark not defined.
2. Condition of Existing Systems ................................................................ Error! Bookmark not defined.
2.1 Biological Process and Aeration Basins .................................... Error! Bookmark not defined.
2.2 Mechanical System .................................................................... Error! Bookmark not defined.
2.2.1 Process Aeration System ............................................. Error! Bookmark not defined.
2.2.2 Channel and Tank Mixing ............................................ Error! Bookmark not defined.
2.2.3 Gates and Actuators ..................................................... Error! Bookmark not defined.
2.2.4 Instrument Air Compressors, Piping, and Valves ....... Error! Bookmark not defined.
2.2.5 RAS Pumps, Piping, and Valves ................................... Error! Bookmark not defined.
2.2.6 HVAC Equipment .......................................................... Error! Bookmark not defined.
2.3 Electrical System ........................................................................ Error! Bookmark not defined.
2.3.1 Electrical Service, ATS, and Medium Voltage Switchgear ......... Error! Bookmark not
defined.
2.3.2 Unit Substation 3 .......................................................... Error! Bookmark not defined.
2.3.3 Unit Substation 4 .......................................................... Error! Bookmark not defined.
2.3.4 MCCs and Other Aeration Related Electrical Equipment .......... Error! Bookmark not
defined.
2.3.5 Motors and Variable Frequency Drives ....................... Error! Bookmark not defined.
2.4 Process Communications, Instrumentation, and Integration .. Error! Bookmark not defined.
2.4.1 Aeration Basin Instruments ......................................... Error! Bookmark not defined.
2.4.2 Network Communication for Actuators and Instruments ......... Error! Bookmark not
defined.
3. Evaluation of Condition-Based Replacement Alternatives .................. Error! Bookmark not defined.
3.1 Unit Substations ......................................................................... Error! Bookmark not defined.
3.1.1 TU-3 Substation ............................................................ Error! Bookmark not defined.
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3.1.2 TU-4 Substation (Secondary Main Supply Transformer Unit) ... Error! Bookmark not
defined.
3.1.3 Key Issues ..................................................................... Error! Bookmark not defined.
3.1.4 Development of Alternatives ....................................... Error! Bookmark not defined.
3.1.5 Recommendations ....................................................... Error! Bookmark not defined.
3.2 Process Communications ........................................................... Error! Bookmark not defined.
3.2.1 Key Issues ..................................................................... Error! Bookmark not defined.
3.2.2 Alternatives ................................................................... Error! Bookmark not defined.
3.2.3 Costs.............................................................................. Error! Bookmark not defined.
3.2.4 Recommended Alternative .......................................... Error! Bookmark not defined.
4. Project Recommendations ..................................................................... Error! Bookmark not defined.
4.1 Biological Process Enhancements ............................................. Error! Bookmark not defined.
4.2 Air Delivery Optimization ............................................................ Error! Bookmark not defined.
4.2.1 Main Aeration Blowers ................................................. Error! Bookmark not defined.
4.2.2 Channel Mixing ............................................................. Error! Bookmark not defined.
4.3 Rehabilitation and Modernization of Existing Equipment ........ Error! Bookmark not defined.
4.3.1 Mechanical ................................................................... Error! Bookmark not defined.
4.3.2 Electrical Systems ........................................................ Error! Bookmark not defined.
4.3.3 Process Control Network, Actuators, and Instruments ............. Error! Bookmark not
defined.
4.4 Summary of Recommended Improvements ............................. Error! Bookmark not defined.
5. Future Work ............................................................................................ Error! Bookmark not defined.
5.1 Flow and Load Projections ......................................................... Error! Bookmark not defined.
5.2 Ammonia Limit Evaluation ......................................................... Error! Bookmark not defined.
5.3 Seismic Resiliency ...................................................................... Error! Bookmark not defined.
6. Conclusions ............................................................................................. Error! Bookmark not defined.
7. Limitations .............................................................................................. Error! Bookmark not defined.
8. References ............................................................................................................................................. 1
Appendix A: Electrical Substation Quote ................................................................................................. A-1
Appendix B: Actuator Quote and Schematic Wiring Diagram ................................................................ B-1
Appendix C: Opinion of Probably Cost for Project ...................................................................................C-1
List of Figures
Figure 2-1. MWMC WPCF aerial view ........................................................... Error! Bookmark not defined.
Figure 2-2. Aeration basin layout and current flow path ............................ Error! Bookmark not defined.
Figure 2-3. 1200A, 540MVA primary power distribution system .............. Error! Bookmark not defined.
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Figure 2-4. Unit substation 3 with transformers TU-3A, TU-3B, and 4160V switchgear Error! Bookmark
not defined.
Figure 2-5. Unit substation 4 ........................................................................ Error! Bookmark not defined.
Figure 2-6. MCCs 04MCC43-04 and 04MCC43-05.................................... Error! Bookmark not defined.
Figure 2-7. MCCs 04MCC42-01 and 04MCC42-02.................................... Error! Bookmark not defined.
Figure 2-8. MCCs 04MCC43-01 and 04MCC43-02.................................... Error! Bookmark not defined.
Figure 2-9. RAS Pump VFD enclosures ........................................................ Error! Bookmark not defined.
Figure 2-10. Secondary #2 Switchboard (04SWB01) ................................ Error! Bookmark not defined.
Figure 2-11. Secondary #6 blower switchboard and active harmonic filter ............ Error! Bookmark not
defined.
Figure 2-12. Secondary aeration blower motor exhaust fans control panel (04PNL43) ................. Error!
Bookmark not defined.
Figure 2-13. Secondary #6 AB blower supply transformer (04XFM06-01 [T1]) ...... Error! Bookmark not
defined.
Figure 2-14. Transformer 43IT1 .................................................................. Error! Bookmark not defined.
Figure 2-15. Transformers 43T1 and 43T2 ................................................ Error! Bookmark not defined.
Figure 2-16. Secondary lighting breaker panel 43LA (04LP43-01) .......... Error! Bookmark not defined.
Figure 2-17. Manual transfer switches 04MTS01-01 and 04MTS01-02 . Error! Bookmark not defined.
Figure 2-18. Five capacitors in the Electrical Room ................................... Error! Bookmark not defined.
Figure 2-19. Two air flow sensors and anoxic cell air flow transmitter ..... Error! Bookmark not defined.
Figure 2-20. Air flow element and air flow transmitter ............................... Error! Bookmark not defined.
Figure 2-21. Two thermal mass flow transmitter panels ............................ Error! Bookmark not defined.
Figure 2-22. Conduit and PROFIBUS DP cables for thermal mass flow transmitter Error! Bookmark not
defined.
Figure 2-23. 04LIT20-01 secondary AB west PE channel level transmitter ............ Error! Bookmark not
defined.
Figure 4-1. PE channel section and photo .................................................. Error! Bookmark not defined.
Figure 4-2. Mixed Liquor channel that feeds the secondary clarifiers ...... Error! Bookmark not defined.
Figure 4-3. Difficult to access and/or broken valves .................................. Error! Bookmark not defined.
Figure 4-4. Duckweed accumulation in mixed liquor channel with difficult to access valve ........... Error!
Bookmark not defined.
Figure 4-5. Primary diversion line/fill supply valve (04WT51-01) ............. Error! Bookmark not defined.
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List of Tables
Table 1-1. Equipment Findings Summary ................................................... Error! Bookmark not defined.
Table 1-2. Channel Aeration and Mixing Alternatives 20-year Life-cycle Cost Evaluation ............... Error!
Bookmark not defined.
Table 1-3. Process Blower Alternatives 20-year Life-cycle Cost Evaluation (2023–2043) ............. Error!
Bookmark not defined.
Table 1-4. Thermal Load Reduction Cost Comparison ............................... Error! Bookmark not defined.
Table 2-1. Major Equipment Design Data for Secondary Process ............. Error! Bookmark not defined.
Table 2-2. MWMC 2006 NPDES Requirements .......................................... Error! Bookmark not defined.
Table 2-4. Valves and Actuators .................................................................. Error! Bookmark not defined.
Table 2-5. Channel Aeration Blowers .......................................................... Error! Bookmark not defined.
Table 2-6. Gates and Actuators Equipment ................................................ Error! Bookmark not defined.
Table 2-7. Motor Control Centers ................................................................. Error! Bookmark not defined.
Table 2-8. Switchboards ............................................................................... Error! Bookmark not defined.
Table 2-9. Harmonic Filter ............................................................................ Error! Bookmark not defined.
Table 2-10. Transformers ............................................................................. Error! Bookmark not defined.
Table 2-11. Manual Transfer Switches ........................................................ Error! Bookmark not defined.
Table 2-12. Motors........................................................................................ Error! Bookmark not defined.
Table 2-13. Variable Frequency Drives ........................................................ Error! Bookmark not defined.
Table 2-14. Thermal Flow Mass Elements .................................................. Error! Bookmark not defined.
Table 2-15. Thermal Flow Mass Transmitters ............................................. Error! Bookmark not defined.
Table 2-16. DO Sensors (Probes) ................................................................. Error! Bookmark not defined.
Table 2-17. DO Sensor with Transmitter ..................................................... Error! Bookmark not defined.
Table 2-18. Universal Transmittals .............................................................. Error! Bookmark not defined.
Table 2-19. Level Transmitters .................................................................... Error! Bookmark not defined.
Table 3-1. TU-3 Replacement Costs ............................................................ Error! Bookmark not defined.
Table 3-2. TU-3 Replacement Costs ............................................................ Error! Bookmark not defined.
Table 3-3. Gate Actuator and Instrument Replacement Costs .................. Error! Bookmark not defined.
Table 4-1. Process Blower Alternatives 20-year Life-cycle Cost Evaluation (2023–2043) ............. Error!
Bookmark not defined.
Table 4-2. Channel Aeration and Mixing Alternatives 20-year Life-cycle Cost Evaluation ............... Error!
Bookmark not defined.
Table 4-3. Motor Control Centers ................................................................. Error! Bookmark not defined.
Table 4-4. Recommended Improvements ................................................... Error! Bookmark not defined.
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List of Abbreviations
AT automatic transfer switch
BC Brown and Caldwell
BCE Business Case Evaluation
BOD biochemical oxygen demand
BTU British thermal units
CAR Condition Assessment Report
CBOD5 5-day carbonaceous biochemical oxygen
demand
cfm cubic feet per minute
CMMS computerized maintenance management
system
DCS Distributed Control System
DO dissolved oxygen
ETI Electrical Testing Incorporated
FCU Field Control Unit
hp horsepower
HVAC heating, ventilation and air conditioning
I&C instrumentation and controls
I/O input/output
kVA kilovolt-amps
lb/d pounds per day
mA milliamp
MCC Motor Control Center
MG million gallons
mgd million gallons per day
mg/L milligrams per liter
mL milliliter
mL/g milliliters per gram
MLSS mixed liquor suspended solids
MV medium voltage
MWMC Metropolitan Wastewater Management
Commission
NEMA National Electric Manufacturers
Association
NOB nitrite-oxidizing bacteria
NPDES National Pollutant Discharge Elimination
System
PE primary effluent
psi pounds per square inch
OPCC opinion of probable construction cost
psig pounds per square inch gage
R&R repair and replacement
RAS return activated sludge
rpm revolutions per minute
SCADA Supervisory Control and Data Acquisition
scfm standard cubic feet per minute
SND simultaneous nitrification and
denitrification
SRT solids retention time
TM technical memorandum
TSS total suspended solids
UIT Universal Indicating Transmitter
VFD variable frequency drive
W2 utility water system
WAS waste activated sludge
WPCF water pollution control facility
yr/yrs year/years
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Executive Summary
Objectives and Introduction
The objectives of the Aeration Improvements Project (Project P80100) were designed to enable the
Metropolitan Wastewater Management Commission (MWMC) to identify and implement projects to
enhance operability and increase the energy efficiency of the Water Pollution Control Facility’s
(WPCF’s or Plant’s) aeration system. The project was organized to enable a systematic and targeted
approach of the condition, performance, efficiency, and reliability of individual systems, as well as
overall impact of proposed improvements to the aeration system. The project recommendations are
intended to help establish the basis for design and construction of future projects.
This Aeration Improvements Project-Business Case Evaluation Report (Report) is intended to be the
final deliverable under the original scope of Aeration Improvements. The Aeration Improvements
Project was organized into the following five phases:
Phase 1: Project Management
Phase 2: Engineering Assessments
Phase 3: Optimization
Phase 4: Workshops.
Phase 5: Alternatives Development
Phase 6: Optional Tasks
This Report summarizes the project, including work documented in detail in previous reports and
technical memoranda (TMs). Workshops were held with MWMC staff during the execution of each
technical phase of the project to present preliminary findings and get input from MWMC. Other
reports and TMs submitted for the project are summarized in Table ES-1.
Table ES-1.
Project
Phase Deliverable Key Findings or Recommendations Date Status
2
Wastewater
Characterization
Sampling and Analysis
Plan
Sampling and analysis for biological process assessment July 2020 Final
2
Aeration Basins and Air
Delivery System
Condition Assessment
Condition and performance ratings for all aeration system assets. November
2020 Final
2 WPCF Aeration System
Assessment
Review of the aeration system and historical data. Key findings:
- WPCF aeration system already operates very efficiently.
- Largest opportunity for improved efficiency is channel mixing.
- Diffusers found to be in good condition with 8-10 years of remaining
service life.
- Some opportunities to improve control system stability.
December
2020 Draft
2 WPCF Simulator
Evaluation Recommendation to use BioWin for process simulation. January
2021 Final
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3
MWMC WPCF Historical
Performance and Dry
Weather Process
Simulator Calibration
Documented historical data review and setup and calibration of BioWin
model.
January
2021 Draft
3
Rehabilitation and
Modernization of
Existing Systems
Replacement recommendations for key aeration system assets based on
condition. June 2021 Draft
6 Effluent Thermal Load
Reduction
Modifications to the aeration system are not a significant opportunity to
reduce the effluent thermal load. July 2021 Draft
3
Secondary System
Process Assessment
and Modeling
Modeling and scenario testing of the aeration system biological model. Key
findings:
- The existing step feed configuration is air efficient and effective. There
is limited benefit to changing the process configuration, and benefits
are not offset by the costs.
- Based on projected future loading, a third treatment train may be
needed by 2035.
- There are some differences in the recent historical loading rates and
the rates assumed in the 2014 Master Plan.
August
2021 Draft
3 Process Blowers
Alternatives Evaluation
Compared alternatives for blowers, including the status quo, the addition of
a new turbo blower, and augmenting the existing centrifugal blowers with
VFDs. The report concluded that the status quo was the most cost effective.
Note: this conclusion was revisited based on comments received in a
workshop with plant staff. BC has revised costs based on electrical
considerations and operating cost assumptions. Updated conclusions are
presented in this report and result in a second turbo blower as the favored
alternative.
September
2021 Draft
3 Channel Aeration and
Mixing Alternatives
Concluded channel air mixing could be improved by replacing the channel
mixing system with a compressed gas mixing system.
September
2021 Draft
This Report uses the findings of work completed during Phases 2, 3 and 4 to develop and
recommend project alternatives to address needs identified under the condition, process evaluation
and modeling, and air delivery assessments. These alternatives reflect condition-based as well as
process and equipment efficiency recommendations. Estimated costs are included with the
recommendations.
Evaluation of Condition-Based Replacement Alternatives
A Business Case Evaluation (BCE) decision-making framework was applied to evaluation of selected
condition-based replacement alternatives that were developed as part of this project, based on the
condition assessment completed in Phases 2 and 3 of the project. Replacement of electrical
substations TU-3 and TU-4, and replacement of the PROFIBUS network communication system with
associated actuators and instruments are condition-based projects were evaluated. Further evaluation
of these alternatives was needed to develop recommendations to be incorporated into the overall
project alternatives presented in this Report. The recommendations are dependent upon decisions
made regarding other proposed improvements, such as upgrades to the blower system. Substation
size for medium voltage and 480-volt equipment should be align with blower replacement.
Inputs to the BCE process are cost estimates for capital improvements, O&M, repair and replacement
(R&R) of assets, and potential risks and benefits applicable for alternatives under consideration. These
evaluations incorporated costs but also considered R&R as well as risks and benefits in a qualitative
manner.
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Unit Substations
There are two-unit substations that feed the Secondary Control Complex, TU-3 and TU-4, as
described below. Both substations were installed as part of the original secondary treatment
construction and put into service in 1984.
TU-3 is dual-ended with each side consisting of an incoming 12.47kV primary switch, a 3000kVA,
12.47kV/4.16kV liquid filled, delta-wye transformer and a secondary 4.16kV fused switch. The two
sides were designed to be interconnected via a 4160V tie switch installed in the middle of the lineup.
However, the tie switch has been taken out of service due to damage incurred during a fault in July
2018. Normal configuration is for side A (transformer TU-3A) to feed blower motor control center
43MCC-04 and for side B (transformer TU-3B) to feed blower motor control center 43MCC-05.
As described in the Process Blowers Alternatives Evaluation TM (BC, 2021), the existing Neuros
blower is powered from a 480 V transformer with a capacity of 1,000 kVA. This transformer is fed
from the compartment at motor control center 04MCC43-05 that previously housed the 4160 V
starter for Hoffman blower 6. As such, the feed to the existing Neuros blower is from the B bus of the
double-ended, medium voltage unit substation TU3 and undergoes two transformations: 12.47 kV to
4160 V at TU3 and 4160 V to 480 V at the 1,000 kVA transformer. The blower draws approximately
625 kVA at full load, therefore a second Neuros blower could not be powered from the existing
1,000 kVA transformer.
The Secondary Main Supply Transformer TU-4 is an outdoor, liquid filled transformer that was
installed in 1984. This substation supplies 480V power to 04MCC42-01 & -02 that feed the
secondary clarifier process, and 04MCC43-01 & -02 that feed the Channel Aeration Blowers and
RAS pumps.
The Secondary Main Transformer Unit TU-4 is not double-ended and therefore lacks redundancy. The
substation includes a generator outlet and manual transfer switch to make provisions for supplying
backup power to Switchboard 43SB.
The report recommends replacement of this equipment. The capacity of a replacement substation for
TU-3 could be reduced if additional medium voltage blowers are replaced with 480V blowers. Based on
the decisions made regarding blower replacement, TU-4 could be replaced with a double-ended
transformer with larger capacity to supply power to one or more future 480V turbo blowers similar to
existing Aeration Blower 6.
Process Communications
MWMC has a Yokogawa Distributed Control System (DCS) that includes the PROFIBUS DP network
communication protocol to interface with equipment such as actuators and instruments. There is
additional equipment that relies on 4-20 mA current loops for process control.
Many gate actuators and process instruments at the aeration basins incorporate PROFIBUS DP
network communication. Gate actuators installed as part of the Phase 1 project in 2008 and the
Peak Flow Management Improvements project in 2010 are approaching the end of their typical
service life. As noted in the Aeration Basins and Air Delivery System Condition Assessment (BC,
2020), there have been issues with the PROFIBUS network as reported by Plant staff and
documented in related work orders. Root cause of PROFIBUS network problems is not entirely clear
and appears to be related to failures of PROFIBUS communication cards installed at the Rotork
actuators as well as moisture ingress at the Turck connectors for termination of the network cables.
Most of the valve actuators are Rotork IQ, Mark 2 series. Production of the Mark 2 series ceased
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around 2012, and the manufacturer will reportedly stop the supply of spare parts in another year or
two.
The automatic diversion gates are associated with the peak flow management system including
primary diversion gate isolation, primary diversion influent, and secondary diversion gates. These
gates typically operate only a few times per year but are critical and must function when called.
Options have been developed to replace existing networked equipment including actuators and
instruments to enable a transition to an Ethernet-based communication protocol such as PROFINET.
BC staff met with MWMC staff on April 8, 2021, to discuss replacement of PROFIBUS DP
communications as part of the aeration basin upgrades. The group also discussed the potential
replacement of existing actuators, instruments and MCCs and other power distribution gear.
Replacement of actuators and instruments needs to be coordinated with upgrades to the network
communication system because different manufacturers have different product offerings. It may be
possible to provide conversion for selected actuators, but that adds complexity and cost to the new
system and is not recommended. There is limited availability of instruments that are PROFINET
compatible. Accordingly, it is assumed that existing PROFIBUS instruments would be replaced with 4-
20 milliamp (mA), hard-wired current loop options if the existing PROFIBUS DP network was replaced
with PROFINET. The availability of instruments that are PROFINET compatible should be reviewed at
the time preliminary engineering starts.
BC recommends that network communication loops be replaced in phases, as currently suggested
by MWMC. It is assumed that loops can be taken out of service one at a time and that existing
conduit could be reused for new cabling to actuators and instruments. Gates with actuators would
need to be operated manually during the construction period. These gates are not operated
frequently. Replacement of actuators for critical gates such as those used for primary and secondary
diversion during periods of high flow should be done during the dry weather flow period.
Recommendations
Based on a condition assessment, BC developed options and recommendations for existing
mechanical, electrical, and instrumentations and control systems, as documented in the
Rehabilitation and Modernization of Existing Systems TM (BC 2021). This section describes the
project components that are included in the project recommendations.
This section also summarizes BC’s overall recommendations from other project reports and TMs.
Additional systems were evaluated and recommendations were considered as part of separate
evaluations for the air delivery system and biological process. Finally, recommendations and costs
for seismic resiliency projects associated with the aeration system and for the DCS upgrade were
drawn from other sources.
Recommendations are grouped into a series of projects. Costs are summarized in Table ES-2.
Rehabilitation Projects
This group of projects includes a series of projects to replace air and W2 piping that is in poor
condition, replace the channel mixing system, and replace the instrument air compressor.
Air and W2 Piping
Significant portions of the air and utility piping and associated valves were installed as part of the
original secondary treatment construction that was put into service in about 1984.
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As discussed at the September 15, 2020, Condition Assessment and Optimization Concept meeting,
corroded steel and ductile iron air and W2 piping and valves require replacement. Additionally, there
are a number of valves controlling channel mixing air that are damaged, or placed in inaccessible
locations. Stainless steel would provide longer service life and is recommended for replacement
piping.
The Rehabilitation and Modernization of Existing Systems TM (BC 2021) recommended replacement
of corroded and damaged piping and valves.
Channel Mixing
Channel mixing was estimated to use approximately 30% of the plants air, and is the single best
opportunity to improve aeration efficiency. The Channel Aeration and Mixing Alternatives TM (BC
2021) evaluated channel mixing alternatives and recommended a pulsed air mixing system. This
system requires less energy, and uses smaller diameter piping, reducing the cost of air piping
required compared to other alternatives.
Instrument Air Compressor
The instrument air compressor is located in the SCC. Replacement of the compressor was included
in the rehabilitation project package.
Process Control Network, Actuators, and Instruments
The Aeration Basins and Air Delivery System Condition Assessment (BC, 2020) notes that most of
the electric actuators on the aeration basin gates as well as instruments in the aeration basins
instruments are reaching the end of their anticipated service life.
As part of a process communications network upgrade, BC recommends that PROFIBUS networked
actuators be replaced with electric actuators compatible with an industrial ethernet network such as
PROFINET. MWMC is planning a phased upgrade to its DCS from Yokogawa Centum 3000 to
Yokogawa Centum VP as part of a separate project that will be coordinated with capital upgrades.
AUMA makes an electrical actuator that is configured for PROFINET and can also be matched with a
Yokogawa Centum VP without a separate gateway.
BC also recommends that existing PROFIBUS networked instruments be replaced with instruments
configured for 4 to 20 mA hardwired control because there is limited availability of some type of
instruments configured for PROFINET. When preliminary design of this upgrade is being performed,
the availability of PROFINET compatible instruments should be evaluated.
SCC HVAC Upgrades
The SCC contains sensitive electrical equipment and is heated but not air conditioned. Staff have
noted the roll-up door is often left open in the summer to promote air circulation and cooling. BC
recommends upgrading the building HVAC system to add air conditioning.
MCC and VFD Replacement
In addition to the aeration system, the Secondary Control Complex (SCC) controls and distributes
power to the secondary clarifiers and RAS pumps. While these unit processes are not part of the
aeration system, modifying the SCC power distribution will necessitate modifications to the MCCs
and VFDs for these systems as well.
Although components of the MCCs were replaced 13 to 14 years ago, the MCC cabinets and other
components date from original construction. Based on the age of some components, and
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obsolescence of the equipment, BC recommends that these MCCs be replaced in coordination with
substations TU-3 and TU-4.
RAS pumps are now fed and controlled by separately enclosed VFDs rather than the original starters
located in motor controls centers 04MCC43-01 and 02. These MCCs have been extensively
modified, are near the end of their service lives and are obsolete. Accordingly, BC recommends
replacement of 04MCC43-01 and 02 with modern units that have smaller footprints and enhanced
networking and power monitoring capabilities.
Air Delivery Optimization and Electrical Distribution Upgrades
The Process Alternatives Evaluation TM (BC 2021) summarized a BCE for the main aeration blowers.
This evaluation considered three alternatives for providing secondary process air for MWMC’s WPCF.
The three alternatives considered were:
1. Status quo. Continue using one Neuros blower for demands up to 16,000 scfm and one or more
Hoffman multi-stage blowers when flow exceeds 16,000 scfm.
2. Install and use a second Neuros blower. All air would be provided by the two Neuros blowers with
the Hoffman blowers being used as standby blowers only.
3. Implement variable-speed controls on the Hoffman multi-stage blowers. This alternative would
still use the Neuros blower at low flow rates but would make the Hoffman blowers more efficient
when they are operated.
The 20-year NPC of the three alternatives, considering equipment, construction, and annual
electricity costs, was calculated. Based on age and condition of equipment that were discussed in
Section 2 of this Report, continued use of existing equipment such as the Hoffman multi-stage
centrifugal blowers assumed rehabilitation of key components to achieve an extended life.
Alternative 1 was projected to have the lowest lifecycle cost.
Findings of this evaluation were presented at a workshop with plant staff on November 30, 2021.
Staff noted that the analysis appeared to underestimate the frequency of operation of the Hoffman
blowers. In reality, plant staff select a blower that can cover peak air demands, and reduces air flow
or throttles during diurnal peaks. Staff noted they ran one Hoffman blower for the duration the
summer of 2020, and required two Hoffman blowers during peak periods. Staff also noted that the
lifecycle cost as structured appeared to overly penalize Alternative 2 by including electrical
distribution upgrade costs only for that alternative. In reality, those upgrades would be required for
all alternatives.
BC reevaluated costs based on these comments. Updated costs are included in the capital cost
summary below. The cost summary also includes replacement costs for substations TU-3 and TU-4.
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Seismic Resiliency
A seismic resiliency assessment was not a part of the Aeration Improvements project, However,
seismic resiliency of aeration system components, including the aeration basins and SCC, was
evaluated in the Disaster Mitigation and Recovery Plan (Carollo, 2020). The evaluation
recommended improvements to the baffle walls within the aeration basins. The evaluation also
recommended improvements to the SCC building. For constructability, the basin upgrades should be
coordinated with rehabilitation projects in the basins. The SCC upgrades may be sequenced
separately.
Biological Process Enhancements
As described in the Secondary Process Assessment and Modeling Technical Memorandum (BC,
2021), results of the alternative operating scenario analysis demonstrate that there are minimal
benefits in changing the current step-feed configuration to other operating configurations. This
conclusion is consistent with the recent benchmarking study conducted by BC, where MWMC was
found to be one of the top wastewater treatment plants in the United States in terms of aeration
system efficiency (WPCF Aeration System Assessment [BC 2020]).
BC estimated, using the BioWin model developed for the project and data reviewed from 2017-
2019, that a third aeration train would be required by 2035. This date is dependent on actual future
flows and loads. It was noted in the assessment that the real plant data from 2017-2020 differs
from the assumed flows and loads in the 2014 MWMC Facilities Plan. Biochemical Oxygen Demand
(BOD) influent loads have been 25% to 45% higher than projected in the plan, and dry weather total
suspended solids (TSS) loads have also been 30% higher than expected. Flows have been slightly
lower than expected, and wet weather peaking factors have been less than expected.
BC estimated the cost of a future third treatment train using the contractor’s schedule of values from
the 2008 Aeration Improvements project, with costs escalated to 2022 dollars based on the
Engineering News-Record construction cost index. The cost for a third treatment train was estimated
to be $10,130,000. This also includes allied costs (engineering, legal, administrative, permitting,
and construction management) and a 40% contingency for undesigned and undeveloped elements.
This is an Association for the Advancement of Cost Engineering (AACE) Class 5 estimate, with an
accuracy of -50% to +100%.
Summary of Recommended Improvements Capital Costs
Recommend improvements and estimates of probable capital cost are summarized in
Error! Reference source not found.. Escalation to the mid-point of construction is not included. The
Basis of Estimate of Probable Construction Cost that provides the markups and estimating detail is
included as Appendix C. Estimates prepared by BC are AACE Class 4, with a range of -30%/+50%.
Estimates for seismic retrofits and the DCS upgrade were prepared by others. Estimates for the
process expansion were
Capital costs were estimated by adding the following allied costs (as a percentage of the
construction cost) to the raw construction cost:
Engineering: 20%
Administrative: 5%
Legal: 2%
Permitting: 3%
Construction Management: 8%
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AACE classes and estimate ranges are as noted. Except where noted, capital costs include a 40%
contingency for undesigned and undeveloped elements.
Table ES-2. Capital Cost Summaries.
Project Component
Capital Cost AACE
Estimate
Class a
Estimate Basis Purpose Report
Section Low Range Estimate High Range
Combined Rehabilitation
Projects $7,670,000 $10,957,000 $16,435,000 4 BC Estimate Condition
Air and W2 piping
replacement, pulsed air
mixing, instrument air
compressor
$2,449,000 $3,499,000 $5,248,000 4 BC Estimate Condition
4.3,
4.2.2,
and
2.2.4
Instrument and actuator
replacement including
ProfiNET
$2,993,000 $4,276,000 $6,414,000 4 BC Estimate Condition 4.3.3
SCC HVAC upgrades $367,000 $525,000 $787,000 4 BC Estimate Condition 2.2.6
MCC and VFD
replacement $1,860,000 $2,657,000 $3,985,000 4 BC Estimate Condition 4.3.2
Blower and Substation
Improvements $9,537,000 $11,036,000 $16,554,000 4 BC Estimate
Condition /
optimization
/ capacity
Add 2nd Turbo Blower $1,812,000 $2,589,000 $3,884,000 4 BC Estimate
Condition /
optimization
/ capacity
4.3.2
TU-3 and TU-4
Substation Upgrades $7,725,000 $11,036,000 $16,554,000 4 BC Estimate
Condition /
optimization
/ capacity
3.1.5
Yokogawa DCS Upgrade b $1,380,000 $2,760,000 $5,520,000 5 MWMC Condition 4.3.3
Basin Seismic Retrofits
b,c $370,000 $740,000 $1,480,000 5
Disaster Mitigation and
Recovery Plan (Carollo,
2020)
Resiliency 4.4
SCC Seismic Retrofits b,c $1,970,000 $3,940,000 $7,880,000 5
Disaster Mitigation and
Recovery Plan (Carollo,
2020)
Resiliency 4.4
Add 3rd Treatment Train $5,065,000 $10,130,000 $20,261,000 5
Based on contractor
schedule of values for
Aeration Basin Phase 1
project, with costs escalated
to current dollars.
Capacity 4.5
a. AACE Class 4 estimates: -30%/+50%. AACE Class 5 estimates: -50%/+100%.
b. Does not include 40% contingency for undesigned and undeveloped elements.
c. As presented in Carollo, 2020 – no allied costs have been added.
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Lifecycle Costs
20-year lifecycle costs for the recommended improvements were estimated by calculating annual
power use and annual power costs for blowers, at a power cost of $0.065/kW-h. Due to the
increased efficiency of turbo blowers when operating at less than full capacity, turbo blowers
consume less power when turned down. Centrifugal blowers consume approximately the same
power regardless of airflow.
Three phasing alternatives where developed for the recommended improvements, as well as the
demand-driven aeration process expansion:
Alternative 1. Make all recommended improvements, including an additional turbo blower
and substation upgrades, during the period from 2022-2025. Add the third aeration process
train during the period from 2032-2035.
Alternative 2. Make all recommended improvements, except the additional turbo blower and
substation upgrades, during the period from 2022-2025. Add the third aeration process train
during the period from 2032-2035. Replace the centrifugal blowers with a turbo blower and
upgrade substations at this time. Additionally, this alternative includes a rebuild and motor
replacement for the centrifugal blowers to extend their service life.
Alternative 3. Make all recommended improvements, except the additional turbo blower and
substation upgrades, during the period from 2022-2025. Replace the centrifugal blowers
with a turbo blower and upgrade substations during the period from 2027-2030. Add the
third aeration process train during the period from 2032-2035. Replace the centrifugal
blowers with a turbo blower at this time. Additionally, this alternative includes a rebuild and
motor replacement for the centrifugal blowers to extend their service life.
Lifecycle costs can be regarded as the amount of capital that should be reserved at the time of
investment to cover all future costs. Table ES-3 summarizes the results of the lifecycle cost
calculation for the three phasing alternatives. These values are determined by discounting the flows
at a specific rate, shown in the following equation:
= (1 + )
(1 + )
where:
An = the non-adjusted annual total costs
n = number of years in the future when the cost will be incurred
f= the inflation or escalation rate
d = is the discount rate
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Table ES-3. Lifecycle Cost Summaries.
Alternative Description Range
Capital Costs, 2022 dollars a Average
annual
operating
cost,
2022
dollars
20-year lifecycle
cost, 2022
dollars b
Phase 1
Years 2022-
2025
Phase 2
Years 2027-
2030
Phase 3
Years 2032-
2035
Total
Alternative 1
Initial upgrade
to turbo
blower
Low range $20,927,000 $0 $5,065,000 $25,992,000
$383,000
$29,200,000
Estimate $32,022,000 $0 $10,130,000 $42,152,000 $50,400,000
High range $51,753,000 $0 $20,261,000 $72,014,000 $92,700,000
Alternative 2
Upgrade to
turbo blower
with basin
expansion
Low range $10,126,000 $0 $16,573,000 $26,699,000
$423,000
$29,600,000
Estimate $15,466,000 $0 $27,695,000 $43,161,000 $50,300,000
High range $24,949,000 $0 $48,578,000 $73,527,000 $91,800,000
Alternative 3
Upgrade to
turbo blower
at midpoint
Low range $9,420,000 $11,508,000 $5,065,000 $25,993,000
$410,000
$30,000,000
Estimate $14,457,000 $17,565,000 $10,130,000 $42,152,000 $51,400,000
High range $23,435,000 $28,318,000 $20,261,000 $72,014,000 $94,200,000
d. See Table ES-2 for estimate ranges and contingency assumptions. Capital costs include administrative, legal, permitting,
and construction management allied costs.
e. An escalation rate of 3% and discount rate of 2.5% were used to calculate lifecycle cost.
An escalation rate of 3 percent and discount rate of 2.5 percent were used in the above calculation.
The escalation rate was chosen based on the Engineering News-Record Construction Cost Index
average annual rate of increase corresponding roughly to the economic recovery period following the
2007-2009 economic downturn. The discount rate was chosen based on recent public works project
construction bond rates, as published by the Oregon State Treasury.
While not monetized in the lifecycle cost calculation, staff have noted that a disadvantage of
Alternative 2 is the increased disruption to regular plant operations and additional effort for project
management, as this alternative requires five years of construction within a twelve year period.
Future Work
Several areas for future work were identified. BC recommends these be completed either separately
or as part of preliminary design. These include:
Flow and Load Projection Updates. In the Secondary System Process Assessment and Modeling TM
(BC, 2021) it was noted that the real plant data from 2017-2020 differs from the assumed flows and
loads in the 2014 MWMC Facilities Plan. Biochemical Oxygen Demand (BOD) influent loads have
been 25% to 45% higher than projected in the plan, and dry weather total suspended solids (TSS)
loads have also been 30% higher than expected. Flows have been slightly lower than expected, and
wet weather peaking factors have been less than expected. A flow and load update may be
warranted to refine design criteria for the aeration system.
Ammonia Limit Evaluation. At the present time, MWMC is expecting a permittee review draft of its
upcoming National Pollutant Discharge Elimination System (NPDES) permit. Based on discussions
with the Oregon Department of Environmental Quality (DEQ), the upcoming permit may include a
year-round ammonia limit. When available, the review draft should be evaluated using the BioWin
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model to confirm whether compliance with the ammonia limit presents and issue and to determine
whether the air flow demand design basis needs to be adjusted.
Seismic Resiliency Assessment. Seismic resiliency improvements to the SCC were recommended in
the Disaster Mitigation and Recovery Plan (Carollo, 2020). BC recommends an ASCE Tier 2 seismic
evaluation to further refine the scope of potential improvements.
Construction Sequencing. The Secondary System Process Assessment and Modeling TM (BC, 2021)
determined that the WPCF can operate with one aeration train during the summer. One potential
construction sequence for improvements involves taking one train offline for construction during a
summer period, and taking the other train offline the next summer. This allows plant staff to operate
the plant in a normal manner during construction. An alternate sequence would involve plant staff
using the west aeration basins, which are not normally used during construction. This may allow for
continuous construction outside of the summer low-flow period, but would require changes to the
way the staff typically operate the WPCF. Pros and cons of each approach and the ability of the plant
to meet any new permit requirements during construction should be assessed.
Procurement. Procurement strategies for turbo blower equipment, such as pre-purchase and pre-
negotiation, should be evaluated. Additionally, future work should include an evaluation of sole-
sourcing Neuros to match the existing blower equipment versus opening procurement to other
candidate manufactures. Also, the availability of PROFINET compatible actuators and instruments
should be evaluated to identify any sole sourcing requirements.
Conclusions
BC recommends Alternative 1, consisting of:
A new turbo blower
Upgrades to substations TU-3 and TU-4
Rehabilitation projects including air piping, W2 piping, a compressed air channel mixing system,
replacement of PROFIBUS with PROFINET, including required upgrades to actuators and
instruments, HVAC upgrades, and associated electrical upgrades.
Seismic resiliency upgrades to the basins and SCC.
This work should be coordinated with the scheduled DCS upgrade planned by the plant.
Expansion of the aeration process to a third treatment train is not required at this time. BC estimates
a third train will be required by 2035.
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References
Bach, R, Fault Inspection Report, EPC Services Company, 2018.
Behnke, Q. Effluent Thermal Load Reduction Technical Memorandum, Brown and Caldwell 2021.
Molseed, A, Aeration Basins and Air Delivery System Condition Assessment Report, Brown and
Caldwell, 2020.
Molseed, A, Rehabilitation and Modernization of Existing Systems Technical Memorandum, Brown
and Caldwell 2021.
Noesen, M. MWMC Facilities Plan for the Eugene-Springfield Regional Wastewater Treatment
Facilities, CH2MHill 2014.
Tam, P. Secondary System Process Assessment and Modeling Technical Memorandum, Brown and
Caldwell 2021.
Zemke, P. Process Blowers Alternatives Evaluation Technical Memorandum, Brown and Caldwell
2021.
Zemke, P. WPCF Aeration System Assessment Technical Memorandum, Brown and Caldwell 2020.
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Appendix A: Electrical Substation Quote
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Appendix B: Actuator Quote and Schematic Wiring
Diagram
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Appendix C: Opinion of Probably Cost for Project
Metropolitan Wastewater Management Commission Capital Improvement Program
FY 22-23 BUDGET AND CIP
AERATION SYSTEM UPGRADES [2023-2026] (P80113)
Description: In 2020 and 2021, Brown and Caldwell evaluated the existing aeration systems and
provided recommendations in January 2022 via project P80100. The P80113 project will
implement the design and construction of additional upgrades/changes to the existing
aeration systems by year 2026. Upgrades to the westerly existing aeration basins are
anticipated after year 2031.
Status: As of January 2022: Brown and Caldwell provided consultant recommendation to
upgrade the existing aeration system/equipment. The Commission was updated about the
consultant recommendations at the January 14, 2022 meeting and the Commission
requested some additional 2022 information from the MWMC project team.
Justification: Update aging (1984) existing equipment/systems such as piping, electrical,
communication technology, blower, HVAC, and other components related to the aeration
system which is part of the MWMC secondary treatment process.
Project Driver: Ongoing efforts to keep existing systems reliable and achieve required performance
outcomes to address the National Pollution Discharge Elimination System (NPDES)
permit.
Project Trigger: Need to address aging aeration systems for reliability and performance upgrades.
Estimated Project Cost: $30,000,000 (revised cost estimating during the design development phase)
Estimated Cash Flow: FY 22-23 = $4,000,000; FY 23-24 = $10,500,000; FY 24-25 = $10,300,000;
FY 25-26 = $5,200,000
Expenditure/Category:
Prior
Years
2021-22
Est. Act.2022-23 2023-24 2024-25 2025-26 2026-27 Total
Design/Construction $0 $0 $5,000,000 $25,000,000 $0 $0 $0 $30,000,000
Other $0 $0 $0 $0 $0 $0 $0 $0
Total Cost $0 $0 $5,000,000 $25,000,000 $0 $0 $0 $30,000,000
Attachment 2 - FY 22-23 Project Sheet P80113 - Aeration System Upgrades (2023-2026)
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