Plant_City_Condition_Assessment_Report_Final.pdf

Hazen and Sawyer

1000 N Ashley Dr., Suite 1000

Tampa, FL 33602

City of Plant City

Water Reclamation Facility

Condition Assessment Report

FINAL Report Work Order No. 21-020-06G-05 Hazen Project No. 40653-008 April 12th, 2024

City of Plant City April 12th, 2024

WRF Condition Assessment

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Table of Contents

Executive Summary

1. Introduction

1.1 Plant City Water Reclamation Facility Description

2. Project Approach

3. Asset Identification and Classification

3.1 ESRI Survey123 Paperless Data Collection

4. Risk Assessment Framework

4.1 Condition Assessment Framework

4.1.1 Likelihood of Failure (LOF)

4.1.1.1 Physical Condition Assessment Scores

4.1.1.2 Performance Condition Assessment Scores

4.1.1.3 Likelihood of Failure Score

4.2 Consequence of Failure (COF)

4.3 Risk Score

4.4 Risk Score and Prioritization of Capital Improvements Plan

4.5 Risk Score and Best Management Approach for Assets

5. Condition Assessment Results

5.1 Overview

5.2 Physical Assessment Results

5.3 Risk Assessment Results – General

5.4 Group A: Preliminary Treatment

5.4.1 Headworks

5.4.2 Odor Control

5.4.3 Master Pump Station (MPS)

5.4.4 Group A Summary

5.5 Group B: Secondary Treatment

5.5.1 Anoxic Process

5.5.2 Aerobic Process

5.5.3 Clarification Process

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5.5.4 RAS/WAS Process

5.5.5 Group B Summary

5.6 Group C: Tertiary Filtration

5.6.1 Tertiary Treatment (Filtration)

5.6.2 Group C Summary

5.7 Group D: Disinfection

5.7.1 Disinfection

5.7.2 Group D Summary

5.8 Group E: Reclaimed Storage and Effluent

5.8.1 High Service Pump Station

5.8.2 Pond Transfer Pump Station

5.8.3 Drain Pump Station

5.8.4 Dechlorination/Reaeration Facility

5.8.5 Group E Summary

5.9 Group F: Solids Handling

5.9.1 Digesters

5.9.2 Belt Filter Process

5.9.3 Other (Drying Beds, Truck Washing Station)

5.9.4 Group F Summary

5.10 Group G: Backup Power

5.10.1 Group G Summary

5.11 Risk Score Summary

6. Budgetary Rehabilitation Considerations

6.1 Belt Filter Press

6.2 Aeration Basin Mixer Replacement

6.2.1 Axial Flow Propeller Mixing

6.3 Digester Mixing Replacement

6.3.1 Nozzle Mixing

6.3.2 Large Bubble Mixing

6.4 Anoxic Basin Mixer Replacement

6.4.1 Hyperbolic Mixers

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6.4.2 Large Bubble Mixers

6.5 Odor Control System Replacement

6.5.1 Biofilters

6.5.2 Biological Trickling Filters

6.6 Sand Filter Replacement

6.7 High Service Pump Replacement

6.8 DRF Structure Improvements

6.9 Clarifier Scum Pump Replacement

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List of Tables

Table ES-1: Asset Replacement Budgetary Cost Summary Table 4-1. Physical Condition Scoring Guidelines Table 4-2. Discipline Parameters for Asset Evaluation Table 4-3: Performance Condition Scoring Criteria Table 4-4. Likelihood of Failure Score Calculation Table 4-5. Consequence of Failure (COF) Evaluation Criteria Table 4-6. Expected Useful Life by Asset Type (Years) Table 4-7: Risk Factor Adjustments Table 4-8: Risk Score Categories Table 4-9. Asset Risk Quadrant and Maintenance and Replacement Strategy Table 5-1: Asset Risk Score Summary Table 5-2: Average Risk Score per Process Group Table 5-3: Asset Groups (Group A) Table 5-4: Asset Groups (Group B) Table 5-5: Asset Groups (Group C) Table 5-6: Asset Groups (Group D) Table 5-7: Asset Groups (Group E) Table 5-8: Asset Groups (Group F) Table 5-9: Asset Groups (Group G) Table 6-1: Assets with highest risk scores Table 6-2: Cost Factors Added to Base Equipment Cost Table 6-3: Plant City WRF High Service Pumps Table 6-4: Asset Replacement Budgetary Cost Summary

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List of Figures

Figure ES-1: Risk Score Summary Figure 1-1: Plant City Water Reclamation Facility Process Flow Diagram Figure 1-2: Plant City Water Reclamation Facility Solids Handling Process Flow Diagram Figure 1-3: Aerial of Plant City WRF with Major Treatment Areas Figure 3-1: Asset Hierarchy Figure 4-1: Likelihood of Failure Figure 4-2: Example Risk Score Matrix Figure 5-1: Physical Assessment Score Distribution Figure 5-2: Physical Assessment Word Cloud Figure 5-3: Risk Assessment Metric Distribution Figure 5-4: Asset Estimated Useful Life Spent Distribution Figure 5-5: Risk Score Summary Figure 5-6: Aerial Image of Plant City WRF – Group A Figure 5-7: Odor control chemical pumps, control panel, chemical secondary containment Figure 5-8: MPS instrumentation Figure 5-9: Group A Asset Risk Matrix Figure 5-10: Aerial Image of Plant City WRF – Group B Figure 5-11: Anoxic mixer with air vortex, anoxic basin structure Figure 5-12: Clarifier scum pump, pressure gage, oil leak Figure 5-13: Group B Asset Risk Matrix Figure 5-14: Aerial Image of Plant City WRF – Group C Figure 5-15: Tertiary filtration filter cell, control panel, and air filter Figure 5-16: Tertiary filtration filter structure Figure 5-17: Group C Asset Risk Matrix Figure 5-18: Aerial Image of Plant City WRF – Group D Figure 5-19: Disinfection chemical pumps, sodium hypo. storage tank, secondary containment, control panel Figure 5-20: Chlorine contact chamber, transfer pump, valve Figure 5-21: Group D Asset Risk Matrix Figure 5-22. Aerial Image of Plant City WRF - Group E Figure 5-23: Reclaimed ground storage tank Figure 5-24: Corrosion on pump no. 3, growth and corrosion on pump no. 4 Figure 5-25: Old Air Bay No. 2 Figure 5-26: Pond transfer pump station concrete slab, pumps and piping Figure 5-27: DRF chemical metering pump, chemical instrumentation, aerators Figure 5-28: DRF PLC, MCC, aerator instrumentation Figure 5-29: Effluent outfall Figure 5-30: Group E Risk Assessment Matrix Figure 5-31: Aerial Image of Plant City WRF – Group F Figure 5-32: Cracking on the interior of Digester 1 Figure 5-33: Rusting and corrosion on the digester decant valves Figure 5-34: Belt Filter Press No. 1 Figure 5-35: Polymer piping, polymer mixing tank

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Figure 5-36: Group F Asset Risk Matrix Figure 5-37: Aerial Image of Plant City WRF – Group G Figure 5-38: Generator within an enclosure, fuel tanks Figure 5-39: Group G Asset Risk Matrix Figure 6-1: Belt Filter Press Process Illustration (Source: Alfa Vaval AS-H Belt Press KPZ) Figure 6-2: Axial Flow Propeller Mixing System (Source: Vaughan) Figure 6-3: Nozzle Mixing System (Source: Vaughn Rotamix) Figure 6-4: Hyperboloid Mixer (Source: Invent) Figure 6-5: Large Bubble Mixing Orientation Figure 6-6: Cloth Media Filter – Plan View (Source: Aqua MegaDisk, Aqua-Aerobics) Figure 6-7: Cloth Media Filter – Section View (Source: Aqua MegaDisk, Aqua-Aerobics) Figure 6-8: DRF aerator structure (Source: Google Earth)

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List of Appendices

Appendix A: Plant City WRF Condition Assessment Survey123 Form

Appendix B: Risk Assessment Scores

Appendix C: Budgetary Replacement Quotes

List of Acronyms

Abbreviation Definition

AADF average annual daily flow

AM asset management

BRE business risk exposure

BTF Biological trickling filter

CCC chlorine contact chamber

CIP capital improvement program

City City of Plant City

COF consequence of failure

DRF dechlorination/reaeration facility

EUL effective useful life

ESRI Environmental Systems Research Institute

FCA facility condition assessment

FDEP Florida Department of Environmental Protection

H2S hydrogen sulfide

LOF likelihood of failure

MG million gallon

MGD million gallons per day

MCC motor control center

MPS master pump station

O&M operations and maintenance

PAR public access reuse

PLC programmable logic controller

R&R renewal and replacement

RAS return activated sludge

RUL remaining useful life

VFD variable frequency drive

WAS waste activated sludge

WRF water reclamation facility

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Executive Summary

The City of Plant City (City) owns and operates its Water Reclamation Facility (WRF) for the treatment and disposal of domestic and industrial wastewater. The original WRF was constructed in 1951, with subsequent expansions and upgrades over the years. Due to age and normal wear and tear, multiple facility components are approaching the end of their typical service life.

The City conducted a facility condition assessment (FCA) of assets at the WRF to develop criticality and risk scores of existing infrastructure. The goal of the FCA is to better understand asset age and condition to estimate performance, serviceability, and remaining useful life while proactively reducing overall infrastructure risk. Assets with high risks would be identified, documented, and include a budgetary-level estimate cost for replacement. The FCA was conducted for asset groups within preliminary treatment, secondary treatment, tertiary treatment, disinfection, reclaimed storage and effluent, solids handling, and backup power. The evaluation included all major mechanical, structural, electrical, and instrumentation and control assets.

The risk assessment framework included a physical condition assessment, performance condition assessment, and criticality of failure from a likelihood of failure (LOF) and consequence of failure (COF) perspective. In preparation for the physical condition assessment, an online field data collection form was developed using Environmental Systems Research Institute (ESRI) ArcGIS Survey123. The virtual survey forms were filled out via tablet for each individual asset, and included condition assessment scoring for each asset, an area for notes and comments, and area to take images. The physical condition assessment was coupled with performance condition metrics including the ability to meet design capacities, ability to meet current and future regulations, average time equipment is readily available, frequency of operations and maintenance (O&M) issues, and obsolescence of equipment technology.

Together, results from the physical and performance assessments yielded the LOF metric. The COF metric was determined by ranking each asset in terms of the consequence of failure from safety, level of service, regulatory compliance, and O&M requirements. The LOF was adjusted for the remaining useful life of each asset, and incorporated to yield an overall adjusted risk score, which ranged from ‘low’ to

‘very high’.

Results of the physical assessment yielded a majority of assets to the in the 3 – average condition ranking.

Primary physical concerns were corrosion, discoloration, cracking, and general wear and tear. Assets were then put into groups and evaluated for a risk score based on LOF and COF metrics. Issues with

O&M and regulatory compliance in a failure scenario yielded the greatest quantity of asset group scoring a 4 and 5, indicating a major impact in the event of an asset failure. Over 40 percent of assets have exceeded useful life, which increased their total risk score.

A risk matrix was developed for each process group, which visually shows where each asset lies as a function of the LOF and COF. The matrix shows the spread of assets and categorizes them into various risk ranges, with the highest risk assets represented in red and lowest risk assets in green. The risk matrix for the assets in this FCA is shown in Figure ES-1. Each asset also has a total summary risk score that can range from 1 to 25. For this effort, the generated risk scores ranged from 3.07 to 16.6. Per the condition

FINAL Report analysis, 52 percent of assets received scores in the high or very high risk category, whereas 48 percent of assets received scores in the medium, low, or very low risk category.

Figure ES-1: Risk Score Summary

Assets with the highest adjusted risk scores were deemed a priority to be rehabilitated or replaced in the near future. From the condition assessment, a budgetary asset replacement cost analysis was conducted for the ten assets with the highest risk scores. The assets with the highest risk scores are listed in Table

ES-1, along with the proposed alternative technology that was used to determine a conceptual cost estimate. Several assets in the belt filter press, tertiary filtration, odor control, and digester areas received high risk scores, so it is assumed that the entire process would be replaced. It should be noted that the grit chamber also received a high risk score but was not included in the budgetary rehabilitation considerations as the City is currently in the process of maintaining and rebuilding the equipment. Other assets on the list individually received high asset scores, such as the aeration basin mixers, anoxic basin mixers, high service pumps, and clarifier scum pumps, and therefore it is assumed that the solitary asset would be replaced. Budgetary replacement costs were derived either from direct quotes with vendors or from recent quotes for other projects. Costs include the base equipment price along with installation cost which includes electrical, instrumentation and controls, mobilization, demobilization, permitting, general requirements, contractor overhead and profit, and contingency. Costs are presented in 2023 dollars, and thus are not escalated for construction at a future date. Costs also do not reflect additional markup or escalation for cost uncertainty, especially during the current market conditions. Costs also do not reflect any O&M requirements of assets after installation.

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Table ES-1: Asset Replacement Budgetary Cost Summary

No. Asset Risk Score

Alternative technology?

Budgetary

Replacement Cost

1 Belt Filter Press 16.6 New Belt Filter Press $3,120,000

2 Aeration Basin Mixers 16.0 Axial Flow Propeller Pumps $1,361,000

3 Sand Filters 15.9 Cloth Media Filtration $3,990,000

4 Digester Mixers 14.6 Nozzle Mixing

Large Bubble Mixing $2,192,000 $3,500,000

5 Anoxic Basin Mixers 13.9 Invent Mixing $1,296,000

6 Odor Control System 13.5 Biofilter

BTF

$1,620,000 $1,820,000

8 High service pumps 11.7 Replacement in kind $2,080,000

9 DRF Structure 11.6 New Structural Stairway $86,400

10 Clarifier scum pumps 10.1 Double Disc Pumps $221,000

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1. Introduction

The City of Plant City (City) owns and operates its Water Reclamation Facility (WRF) for the treatment and disposal of domestic and industrial wastewater. The original WRF was constructed in 1951, with subsequent expansions and upgrades over the years, and multiple facility components are approaching the end of their typical service life.

The City conducted a facility condition assessment (FCA) of assets at the WRF to develop criticality and risk scores of existing infrastructure. The goal of the FCA is to better understand asset age and condition to estimate performance, serviceability, and remaining useful life while proactively reducing overall infrastructure risk. The results of this project will identify assets to be prioritized for replacement and/or rehabilitation in future improvement projects at the City. The FCA was conducted for several groups identified at the WRF, including preliminary treatment, secondary treatment, tertiary treatment, disinfection, reclaimed storage and effluent, solids handling, and backup power. This report describes the methodology and results of the asset evaluation which includes all major mechanical, structural, electrical, and instrumentation and control assets.

1.1 Plant City Water Reclamation Facility Description

The Plant City WRF was originally constructed in 1951 with trickling filtration as the secondary treatment process. The plant was upgraded and expanded in the 1970’s by replacing the fixed-film process with aerated lagoons and a polishing pond. The WRF was upgraded in 1997 to provide public access reuse (PAR) via reclaimed effluent to City residents and industries. The most recent facility upgrade occurred in 2008, which included the construction of anoxic basins upstream of new aeration basins, secondary clarifiers, and additional tertiary filtration, shown in Figure 1-1 and Figure 1-2. The current capacity of the WRF is 10 million gallons per day (MGD) annual average daily flow (AADF) and utilizes the following treatment processes in series: headworks with a mechanically cleaned bar screen, Pista grit removal system, a master pumping station, an anoxic tank subdivided into three parallel trains, three oxidation ditches for biological treatment, a splitter box for flow distribution to three clarifiers, continuous backwash upflow tertiary sand filters, a disinfection chlorine contact chamber (CCC), three reclaimed groundwater storage tanks and one reclaimed high service pumping station. Solids treatment consists of four aerobic sludge digesters and two belt filter presses that yield stabilized biosolids for land application. The primary effluent disposal method is through reclaimed use. Excess effluent is sent to an offsite dechlorination/reaeration facility prior to discharge to Itchepackesassa Creek through the East

Canal. If needed, old air bays and polishing ponds serve as storage for reject events. An aerial image of the WRF with major process areas is shown in Figure 1-3.

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Figure 1-1: Plant City Water Reclamation Facility Process Flow Diagram

Figure 1-2: Plant City Water Reclamation Facility Solids Handling Process Flow Diagram

Figure 1-3: Aerial of Plant City WRF with Major Treatment Areas

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2. Project Approach

The approach to the FCA included desktop assessment, field inspections, and workshops between Hazen

(Engineer) and the City’s Operations staff to develop risk scores at the asset group level. Prior to conducting field inspections, assets within each process were identified for assessment from current record drawings and conversations with City staff. Field inspections were conducted to determine the physical condition of each asset. A workshop was held with City staff to determine weightings for criteria associated with the condition assessment. An interview was also conducted with City staff to identify operational or performance challenges with current assets at the WRF. The following summarizes the overall project approach:

1. Asset Identification and Classification

a. Development of Survey123 field assessment form

b. Execution of field assessment form via physical inspections

2. Risk Assessment

a. Initial workshop to determine criteria weightings for likelihood of failure, consequence of failure

b. Likelihood of failure: on-site physical condition assessment with Survey123 field assessment form and performance condition

c. Consequence of failure analysis

d. Subsequent workshop to review initial LOF and COF scores.

e. Determination of initial risk assessment using LOF and COF scores

3. Estimate effective useful life (EUL) and remaining useful life (RUL) of assets

a. Review adjusted risk score considering EUL/RUL in a workshop setting

4. Condition Assessment Results

5. Risk Score Summary

The framework for the FCA approach is detailed in Chapter 3 and 4 herein.

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3. Asset Identification and Classification

The FCA approach included a risk-based framework for scoring the physical and performance condition of each asset. The individual asset scores under each treatment process were combined and an overall risk score was developed at the asset group level to inform long-term capital investments and project decision making. A simplified diagram of the asset hierarchy that was used is presented in Figure 3-1.

Figure 3-1: Asset Hierarchy

3.1 ESRI Survey123 Paperless Data Collection

An electronic condition assessment form was developed using ESRI Survey123 software. Forms were used in the field to record an asset's physical condition. Each new form allowed for easy selection of an asset through drop-down menu options that filtered the existing assets by location and specific discipline.

Survey123 is an ESRI mobile application that is used extensively by Hazen for condition assessments across the country. The assessment is performed on a smartphone or tablet, eliminating the need for printing forms and manual data entry, which decreases the level of effort and data entry errors. A wireless internet connection is not required for Survey123 while performing the condition assessment, as the forms and data are loaded and stored locally onto the smartphone or tablet. Once a wireless internet connection is established, the phone or tablet will sync with the database and transfer the data. Survey123 allows photos of the assets to be taken and linked to the asset being analyzed. A copy of the Survey123 form can be found in Appendix A.

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4. Risk Assessment Framework

The recommended risk assessment framework includes condition assessment framework, criticality framework, and overall risk score for each asset. Results from the risk score analysis will assist the City in prioritizing replacement, renewal, and O&M needs uniformly for assets at the Plant City WRF.

The condition assessment framework included likelihood of failure (LOF) scores based on physical and performance condition assessment of the assets. The criticality framework included consequence of failure (COF) scores. The overall risk score for each asset was calculated based on the product of the LOF and COF scores. The risk score was then adjusted based on the estimated remaining useful life of each individual asset.

4.1 Condition Assessment Framework

4.1.1 Likelihood of Failure (LOF)

Likelihood of Failure (LOF) measures an asset’s likelihood of, or timing to, failure. LOF accounts for both the physical condition and performance condition of the asset as shown in Figure 4-1.

Figure 4-1: Likelihood of Failure

4.1.1.1 Physical Condition Assessment Scores

Physical condition is a critical factor in determining the likelihood of an asset failing. As the condition of an asset deteriorates, it will become more likely to fail. The physical condition of the asset is typically assessed via visual inspection and is an evaluation of the current state of the asset. Each asset can be rated on a scale of 1 to 5 (1 being the best and 5 being the worst) for physical condition. The general descriptions for the scoring criteria to evaluate physical condition of each asset are included in Table 4-1.

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Table 4-1. Physical Condition Scoring Guidelines

Score

Overall

Condition Performance Condition Guidelines

1 – Like New Very Good Fully operable, well maintained, and consistent with current standards. Little wear shown and no further action required.

2 – Good Good

Sound and well maintained but may be showing slight signs of early wear.

Delivering full efficiency with little or no performance deterioration. Only minor renewal or rehabilitation may be needed in the near term.

3 – Minor

Defects Fair

Functionally sound and acceptable and showing normal signs of wear. May have minor failures or diminished efficiency with some performance deterioration or increase in maintenance cost. Moderate renewal or rehabilitation needed in near term.

4 – Major

Defects Poor

Functions but require a high level of maintenance to remain operational.

Shows abnormal wear and is likely to cause significant performance deterioration in the near term. Replacement or major rehabilitation needed in the near term.

5 – Imminent

Failure/Failed Failing

Effective life exceeded and/or excessive maintenance cost incurred. A high risk of breakdown or imminent failure with serious impact on performance.

No additional life expectancy with immediate replacement needed.

Assets can be grouped into one of the following disciplines:

• Mechanical, which includes assets such as pumps, tanks, mixers, piping, compressors, blowers, backflow preventors, valves, and actuators.

• Electrical/Instrumentation, which includes assets such as level sensors, control panels, switchgear, motor control centers (MCCs), flow meters, valve actuators, and power supply units.

• Structural, which includes assets such as reinforced concrete tanks, metals, buildings, and vaults.

On a scale of 1 to 5 (1 being the best and 5 being the worst), assets under each discipline were assessed for parameters included in Table 4-2.

Table 4-2. Discipline Parameters for Asset Evaluation

Discipline Parameters

Mechanical

External Corrosion/ Coatings

Leakage

Vibration/Noise

Heat/Odor

Supports / Anchors/Ancillary Equipment (piping, valves, appurtenances)

Physical Damage

Electrical/I&C

Heat/Odor

Nameplates

Wiring

Conduits and Support Brackets

Indicator Lights

Push Buttons

Doors/Seals

Vibration/Noise

Physical Damage

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Discipline Parameters

Display Screen

Pests/Critters

Electrical Controls

Motors

Structural

Foundation

Walkways/Platforms / Ladders / Railings

Roof

Railings

Drainage

Exterior Coatings including Insulation

Interior Coatings

Structural Damage for different materials

By considering the scores of each parameter within a discipline, an overall physical condition score on a scale of 1 to 5 (1 being the best and 5 being the worst) was assigned to each asset. Physical condition assessments were evaluated over multiple days for the WRF’s major process areas, including preliminary treatment, secondary treatment, tertiary filtration, disinfection, reclaimed storage and effluent, solids handling, and backup power. Physical condition assessments were carried out between May and June of

2023. Assessment of infrastructure assets located underground and/or submerged were not accessible for visual inspection and are noted herein. The physical condition assessment findings are described in detail in Chapter 5.

4.1.1.2 Performance Condition Assessment Scores

The performance condition of each asset was also evaluated. The performance condition metric considers the ability of the asset to fulfill its function and considers the following metrics:

• Capacity: Does the asset have sufficient capacity to perform its intended function?

• Regulatory: Does the asset enable or impact the City’s ability to meet permit requirements and by how much?

• Reliability: How often is the asset available for use?

• O&M issues: What is the frequency of O&M work outside of breakdowns?

• Obsolescence: Is the technology or equipment state-of-the-art or out-of-date, which impacts the

City’s ability to maintain equipment and obtain spare parts?

The asset’s performance condition provides critical information necessary to evaluate an asset’s overall condition and subsequent LOF. For each performance condition criterion, each asset was assigned a raw performance condition score from 1 to 5 (1 being the best and 5 being the worst) and each performance condition criterion was assigned a weighting (%) factor that defined the typical relative importance of each criterion to the overall performance condition score. A total performance condition score was then estimated based on the raw performance condition score for each criterion and the corresponding weighting factor as shown in Table 4-3.

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Table 4-3: Performance Condition Scoring Criteria

Criteria Condition 1 2 3 4 5 Weight

Capacity

Ability to meet current capacity

Avg – Yes*

Peak – Yes*

Avg – Yes*

Peak – Yes*

Avg – Yes*

Peak – No**

Avg – Yes**

Peak – No**

Avg – No**

Peak – No**

15 Ability to meet future capacity

Avg – Yes*

Peak – Yes*

Avg – Yes*

Peak – No*

Avg – Yes*

Peak – No*

Avg – No*

Peak – No**

Avg – No**

Peak – No**

Regulatory meet current regulations

Yes – Greatly

Exceeds

Yes-

Acceptable

Factor of Safety

Yes- Minimal

Factor of

Safety

No-Minor modifications required

No meet current regulations

Yes – Greatly

Exceeds

Yes –

Acceptable

Factor of Safety

No – Minor modifications required

No – Major modifications required

No

Reliability

Avg. time equipment is available when needed

99-100%

95-99% (up to

18 days O/S)

90-94% (up to 36 days

O/S)

85-89% (up to

55 days O/S)

<84% (over

55 days O/S)

O&M Issues

Frequency of

O&M issues

(Excluding

Checks and Breakdowns)

None

Very

Infrequently

(Bi-Annually)

Infrequently

(Quarterly)

Frequently

(Monthly)

Very

Frequently

(Weekly/Daily

Obsolescence

Equipment

Technology

Technology

Best

Available/State of the Art

Technology

Industry

Standard/”Tried and True”

Technology considered

Appropriate

Technology nearing

Obsolescence

Technology

Obsolete/Ou t of Date

*With One Unit Out of Service **With All Units in Service O/S – Out of Service

Recommendations were developed for the performance condition criteria and weighting factors based on the Engineering team’s asset management experience with other similar utilities across the country, project-specific drivers, and input from City O&M staff and upper management.

The performance condition assessment was performed on July 19th, 2023, in a workshop setting for the assets for which physical condition assessment was conducted. The performance condition assessment findings are described in detail in Chapter 5.

4.1.1.3 Likelihood of Failure Score

The Likelihood of Failure (LOF) metric is developed from an assessment of an asset’s physical condition and performance condition. Per discussions and input from the City team, a weighting factor of 40% was applied to the physical condition score and 60% was applied to the performance condition score. After the weighting factors were applied, the LOF score for each asset was quantified by adding the overall weighted physical condition score and the overall weighted performance condition score, as shown in

Table 4-4.

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Table 4-4. Likelihood of Failure Score Calculation

Likelihood of Failure Score

Physical Condition Score x 40% = _______________

Performance Condition Score x 60% = _______________

Likelihood of Failure Score =

Sum Above

4.2 Consequence of Failure (COF)

An asset’s criticality is identified by the Consequence of Failure (COF) and measures the direct and indirect implications and costs associated with asset failure. When assets fail, the corresponding consequences depend on the failure mode and level of redundancy. The consequences of failure can vary from a minor inconvenience to a major disruption of customer service, inability to comply with an operating permit, and possible endangerment of personnel and public health. As an example, the failure of the hypochlorite feed system would have significant consequences, including potential inability to meet disinfection requirements, while the consequence due to failure of a sludge transfer pump with a redundant standby pump would not be nearly as significant.

Per discussion and input from the City O&M team, the COF was determined based on the following four criteria:

• Safety

• Level of Service

• Regulatory Compliance

• O&M Impacts

Each COF criterion can be assigned a score from 1 to 5 (1 being the best and 5 being the worst) to describe the impact of failure, ranging from no impact to major impact. Additionally, each criterion can be assigned a weighting that defines the typical relative importance of each criterion to the overall COF.

The criteria to evaluate the COF score and the corresponding weighting factors are shown in Table 4-5.

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Table 4-5. Consequence of Failure (COF) Evaluation Criteria

Criteria Scoring Criteria Weighting

Factor

Safety 1- No Impact

15%

3- Failure creates potential for potential damage to surrounding equipment.

5- Failure creates potential for injury to staff or the public (i.e., significant bodily injury or may damage equipment or environment such as chemical leak/fire/explosion)

Level of

Service

1- No Impact

30%

2- Eventual impact if no response (typical response time is expected to be adequate to avoid possible localized service interruption and reduce operational flexibility)

3- Impact if no response (typical response time is expected to be adequate to avoid possible significant capacity reduction, service interruption and reduce operational flexibility). Potential localized impact to surrounding/ downstream equipment.

4- Immediate localized impact before response (typical response time would not be adequate to avoid possible significant capacity reduction, can meet average daily flows but not peak flow, service interruption, reduce operational flexibility). Localized impact to surrounding/ downstream equipment.

5- Immediate widespread impact before response (typical response time would not be adequate to avoid significant capacity reduction (cannot meet peak flow), service interruption, reduced operational flexibility).

Impact to surrounding/ downstream equipment.

Regulatory Compliance

1- No Impact

20%

2- Eventual non-compliance event if no response (typical response time would be adequate to avoid significant, water quality violations). Non-compliance would have no repercussions.

3- Non-compliance event if no response (typical response time would be adequate to avoid significant water quality violations). Non-compliance would result in fines from regulatory agencies.

4- Immediate localized impact before response (typical response time may or may not be adequate to avoid significant water quality violations). Non-compliance would result in fines from regulatory agencies.

5- Immediate widespread impact before response (typical response time would not be adequate to avoid significant overflow or violations)

Non-compliance would result in extensive fines from regulatory agencies and long-term impact.

O&M

Impacts

1- No Impact

35%

2- Short repair duration, low-cost impact and can be repaired by in-house staff. No loss in redundancy

3- Long repair duration, moderate cost impact and can be repaired by in-house staff. No loss in redundancy)

4- Short repair duration, high-cost impact and requires outside expertise in addition to in-house staff. Limited redundancy (redundancy for average flows, not peak flow)

5- Long repair duration, high-cost impact and requires expertise in addition to in-house staff. No redundancy

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In addition to the performance condition and LOF assessment, the Engineering team conducted the COF assessment for the same assets at the City WRF via desktop analysis. The COF criteria and weighting factors included in Table 4-5 were utilized for the COF assessment and a COF score was developed for each asset.

4.3 Risk Score

Risk scores provide an overall view of the risk that each asset presents in its current state with respect to operations. Risk scores were calculated as the product of the LOF and COF scores as shown below:

Initial Risk Score = LOF x COF

The age of an asset is another key factor for assessing a replacement timeframe. For example, two pumps with similar condition scores may require replacement at different times if one pump is older than another. Therefore, asset age was used to determine final adjusted risk scores and the recommended replacement timeframe of assets. The value used for the age of existing assets was based upon available records, review of record drawings, and input from City staff. Table 4-6 presents the expected useful life

(EUL) for assets common at wastewater treatment facilities. This table was developed based on typical industry practices, engineering experience and judgement, and input from the City.

Table 4-6. Expected Useful Life by Asset Type (Years)

Asset Expected Useful Life

Process Equipment

Process Equipment (general) 20

Aeration Equipment (Blowers, Mixers) 25

Chemical Storage Tanks 15

Sludge Collectors 25

Compressors 20

Process Structures

Process Structures (general) 35

Concrete Structures (Sedimentation basins, Filter Basins, Sludge Holding, Clear Wells) 40

Steel Structures 35

Reject Pond 50

Ground Storage Tank 50

Pumps

Pumps (general) 20

Liquid Service Pumps and Motors (e.g., Centrifugal) 20

Chemical Dosing Pumps (e.g., Diaphragm, Peristaltic) 10

Submersible Solids Transfer Pumps 15

Piping and Valves

Piping and Valves (general) 40

Valves and Gates, Liquid 25

Valve Actuators 15

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Asset Expected Useful Life

Valves and Gates and Process Piping, Solids 18

Valves and Gates Air 25

Process Piping and Valves (Other) 40

Electrical

Electrical (general) 25

Switchgear 40

Transformers and Electrical Distribution 40

Motor Control Centers 40

Motors, Motor Starters, VDFs, etc 20

Generators 25

Fuel Tanks 50

Instrumentation & Controls / SCADA

Instrumentation & Controls / SCADA (general) 20

SCADA Equipment 15

Controls (DCU’s, PLC’s, HMI’s, Cabinets) 18

Field Instruments (Analyzers, Sensors, Probes, Meters) 15

The remaining useful life (RUL) can be defined as the time remaining until an asset ceases to provide its required use in the context of design, physical, service, and economic life. For assets without any available condition information, RUL can typically be determined based on EUL and asset age. EUL presented in Table 4-6 in conjunction with the install date, was used to estimate the RUL of each asset using the following equation:

RUL = EUL – Age (years)

Where:

RUL = Remaining useful life (years)

EUL = Effective useful life (years)

Age (years) = Current year – Install year

A risk factor adjustment was added to the risk scores based on the percentage of useful life spent on that asset. The percentage of useful life spent is defined as the ratio of the assets age and the EUL as follows:

% Useful Life Spent = (EUL – RUL)/ EUL

Table 4-7 presents risk factor adjustments based on the percentage of useful life spent for each asset.

Table 4-7: Risk Factor Adjustments

% Useful Life Spent Risk Factor Adjustment

0 to 25% No Adjustment

>25% - 50% +1

>50% - 75% +2

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>75% - 100% +3

>100% +4

The risk factor adjustment was added to the Risk Score to yield the adjusted risk score as follows:

Adjusted Risk Score = Risk Score + Risk Factor Adjustment

Older assets in poor condition pose the greatest risk. Newer assets with a low LOF score (i.e. good condition) and a low COF score post the lowest risk. Based upon the risk score, assets were categorized as very low, low, medium, high, or very high as defined in Table 4-8.

Table 4-8: Risk Score Categories

Risk Category Adjusted Risk Score Risk Color Code

Very Low ≤2

Low >2 ≤ 5

Medium >5 ≤ 9

High >9 ≤ 16

Very High >16 ≤ 25

Asset scores are presented in Appendix B and include discipline specific LOF scores, COF scores, risk scores, adjusted risk scores, and the associated risk category for each asset. The age and EUL of each asset is also presented.

The adjusted risk score can also be used to determine an adjusted LOF, per the following equation:

Adjusted Risk Score / COF = Adjusted LOF

4.4 Risk Score and Prioritization of Capital Improvements Plan

The risk score can be used to help guide and justify Capital Improvement Program (CIP) projects at the

Plant City WRF.

As shown in Figure 4-2, the top right corner categorizes assets as a very high risk (red zone), and the bottom left corner categorizes assets as low risk (green zone). Assets with moderate and high-risk scores fall in yellow and orange zones between the red and green zones, respectively.

Figure 4-2: Example Risk Score Matrix

Within a facility, the CIP should be focused on replacing the assets that have the highest risk scores (red and orange zones). By replacing these high-risk assets, the asset’s physical and performance condition score would improve, thereby lowering the asset’s risk score, and in turn lowering the overall risk of the

WRF. Replacing high-risk assets would also potentially reduce emergency maintenance activities over time and allow the plant’s maintenance team to focus more on preventive maintenance activities.

The risk score can also help prioritize CIP projects between different facilities. With standardized LOF and COF metrics, assets can be directly compared based on the overall risk score. With limited capital funding, the risk score will allow the City to make risk-based decisions to determine which assets to replace and which assets can have replacement postponed until funds are available. Having a data-driven

CIP provides greater support and justification for budgets and spending.

Quadrant I Quadrant III

Quadrant II Quadrant IV

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4.5 Risk Score and Best Management Approach for Assets

Risk score components (LOF and COF) plotted on a risk matrix can provide indication of the best management approach for a facility’s assets and can be used to guide and prioritize O&M activities. As shown in Figure 4-2, assets can be divided into four quadrants based on their LOF and COF scores.

Assets with both high LOF and COF scores will have high-risk scores, will fall under quadrant I, and will most likely have a high priority for replacement (with highest priority for the assets in the red zone, followed by the orange zone). Assets in this quadrant should have focused preventive maintenance strategies to keep these assets operational while being scheduled for replacement.

Assets with low LOF and COF scores will fall under quadrant IV and will have little impact on plant operations when they fail. For these assets, the City staff may consider limited preventive maintenance and a run-to-failure approach. Assets with high COF but low LOF will fall under quadrant II. Frequent inspection may be the best management approach for these assets (with higher priority for the assets in the orange and yellow zone, followed by the green zone) to ensure that the critical assets do not degrade at an unexpectedly rapid rate. Assets with low COF but high LOF will fall under Quadrant III. For these assets, priority may be placed on renewal versus continued maintenance, depending on which approach provides the highest level of service at the lowest lifecycle cost to the City. The description of each maintenance and renewal and replacement (R&R) strategy for each quadrant is presented in Table 4-9.

Table 4-9. Asset Risk Quadrant and Maintenance and Replacement Strategy

Quadrant

Likelihood of

Failure

(LOF) Score

Consequence of Failure

(COF) Score Maintenance and R&R Strategy

I ≥2.5 (High) ≥3.5 (High)

Visual inspections and performance testing with advanced equipment (as necessary) at more frequent intervals (quarterly or bi-annually), aggressive PM schedule based on run-time hours and asset condition, and capital R&R in immediate future

II <2.5 (Low) ≥3.5 (High)

Visual inspections and performance testing with advanced equipment (as necessary) at longer intervals (annually), moderately aggressive PM schedule based on run-time hours and asset condition, and capital R&R planned for projected end of useful life

III ≥2.5 (High) <3.5 (Low)

Visual inspection at regular intervals (bi-annually or annually), PMs scheduled based on time/calendar and potential run-to-failure capital R&R strategy

IV <2.5 (Low) <3.5 (Low)

Visual inspection at longer intervals (triennially), PMs scheduled based on time/calendar and potential run-to-failure capital R&R strategy

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5. Condition Assessment Results

5.1 Overview

A summary of the physical condition scores, performance condition scores, and subsequent LOF, COF and risk scores are presented by process/sub-process in this Section. For the purposes of this project, ancillary assets of nominal value (approximately less than $1,000) were not assessed. Examples include sample pumps, pH probes, solenoid valves, etc. It is assumed these components are easily replaced by plant maintenance staff and have minimal impact on the overall corresponding unit process. Assets that were located underground or submerged were also not able to be physically assessed, such as underwater concrete structures, mixers, diffusers, valves, and some instrumentation. The physical condition score of such assets was omitted from the analysis, however the performance condition and LOF scores were still developed. COF, LOF, EUL, and overall risk scores identified for each asset can be found in Appendix B.

5.2 Physical Assessment Results

The physical assessment was carried out in the field using virtual Survey123 forms. Each asset was ranked based on their physical condition on a 1 to 5 scale, where 1 was excellent and 5 was poor. In total, 366 assets were evaluated. Out of the assets, a majority (60 percent) were identified in as average condition, as seen in Figure 5-1. Approximately 25 percent of assets were identified as in fair condition. It should be noted that this distribution aligns with other facilities in operation for 20+ years.

Figure 5-1: Physical Assessment Score Distribution

A catalog of notes written about each asset was compiled within the Survey123 results. The compiled word cloud from the physical assessment is shown in Figure 5-2. The most common comment during the physical condition assessment was ‘corrosion’ which was mentioned over 50 times indicating that

17 19

1 2 3 4 5

N u m b e r o f A s s e ts

Asset Rating

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The note ‘cracking’ was also mentioned over 10 times, which indicates that some of the structures were observed to have cracks.

Figure 5-2: Physical Assessment Word Cloud

5.3 Risk Assessment Results – General

Individual assets from the physical condition assessment were averaged to asset groups, which were ranked for performance condition, LOF, and COF metrics. Asset groups were then evaluated to determine the LOF and COF metrics. The LOF metric evaluates an asset’s ability to meet current and future capacities with redundancy, ability to meet current and future regulations, average time equipment is available when needed, frequency of O&M issues, and equipment obsolescence. The COF metric analyzes an assets risk to safety, level of service, regulatory compliance, and O&M impacts in the event of a failure. A ranking of 1 indicates little to no issue, whereas a ranking of 5 indicates a major impact if an asset was to fail.

Figure 5-3 illustrates the distribution of results for the different performance metrics. Specifically, the figure shows the percentage of the assets that were ranked 1 to 5 for each metric. Like the physical assessment, the majority of assets ranked as a 3 for many of the metrics, indicated by the yellow portion of each bar. Most assets ranked as a 2 or 3 in the capacity category, meaning that the assets were able to meet current and future capacities, but unable to meet peak future capacity with one unit out of service.

Assets also ranked as a 2 or 3 in the regulatory category, meaning that assets were able to contribute to meeting current and future regulations with some safety factor. More than 50 percent of the assets scored a 1 in the reliability and safety metrics, meaning the equipment is usually available when needed, and failure would not prompt a large safety hazard. The majority of the high scores was found in the COF compliance and O&M categories, meaning if there was an asset failure, there could be implications in terms of potential fines, and lengthy, costly repair durations.

Figure 5-3: Risk Assessment Metric Distribution

The assets were also assigned an installation year based on available records, review of record drawings, and input from City staff. Some assets were installed with the WRF expansion in 2008, some were installed with the conversion to a reclaimed system in 1997, and other assets were original with the initial iteration of the City WRF (e.g. digesters). The estimated install year was used in conjunction with conservative asset lifespan approximations (found in Table 4-6) to determine the useful life spent. Figure

5-4 illustrates the distribution of the estimated useful life of each asset group. From the figure, 50 of the asset groups (approximately 44 percent) have been in operation longer than the recommended lifespan.

Although many assets have exceeded the approximated lifespan, it does not mean that assets need to be replaced immediately. However, the age of the assets was incorporated to increase the overall risk score.

Frequent preventative maintenance on assets can extend lifespan, however the risk that the asset may fail becomes higher with age.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

P e rc e n ta g e o f

A s s e t G ro u p s

Metric

1 > 1, < 2 > 2, < 3 > 3, < 4 > 4, < 5 5

Figure 5-4: Asset Estimated Useful Life Spent Distribution

The risk matrix presented in Figure 5-5 provides a summary of the overall risk assessment scope results for all assets evaluated at the Plant City WRF. The matrix demonstrates the spread of assets into various risk ranges, with the highest risk assets represented in red and lowest risk assets in green.

Per Section 4.4, assets that were assigned a LOF greater than 3.5 and COF greater than 2.5 are located in

Quadrant I of the risk matrix. Per the Figure, approximately 16 percent of assets were listed in this category. Recommendations regarding assets in this quadrant include visual inspections and performance testing with advanced equipment (as necessary) at more frequent intervals (quarterly or bi-annually), aggressive PM schedule based on run-time hours and asset condition, and capital R&R in the immediate future. Assets in this quadrant warrant initial attention and should be considered for replacement or rehabilitation in a future CIP.

Approximately 23 percent of assets reside in Quadrant II, which is representative of a low LOF but high

COF. These assets require replacement, rehabilitation, additional monitoring, or other proactive risk reduction strategies over the next 5 to 15 years. Approximately 49 percent of assets were evaluated in

Quadrant III, which corresponds to a high LOF but low COF. These assets have moderate risk scores and require visual inspection at regular intervals (bi-annually or annually). Approximately 12 percent of assets landed in Quadrant IV, which is representative of a low COF and low LOF. Assets in this Quadrant do not require immediate action; however it may still be cost-effective for some assets to be monitored and tracked on a limited or infrequent basis to determine the condition over time. Non-critical assets in

Quadrant IV can often be replaced at or close to the time of failure without impacting overall operations.

Results show a reasonable overall risk profile based on the age, and condition of the Plant City WRF.

< 20% > 20%, < 40% > 40%, < 60% > 60%, < 80% > 80%, < 100% > 100%

N u m b e r o f A s s e t G ro u p s

Estimated Useful Life Spent

Figure 5-5: Risk Score Summary

Each asset also has a total summary risk score that can range from 1 to 25. For this effort, the generated risk scores ranged from 3.07 to 16.6. The percentage of assets in each risk category is summarized in

Table 5-1. Per the condition analysis, 52 percent of assets received scores in the ‘high’ or ‘very high’ risk category, whereas 48 percent of assets received scores in the ‘medium’, ‘low’, or ‘very low’ risk category.

Table 5-1: Asset Risk Score Summary

Risk Category Adjusted Risk Score Percentage of Assets

Very Low ≤2 1%

Low >2 ≤ 5 5%

Medium >5 ≤ 9 42%

High >9 ≤ 16 50%

Very High >16 ≤ 25 2%

When reviewing and interpreting the final scores and outcomes, there are several elements to consider:

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