City of Bradenton City Centre – Capacity Analysis for Sanitary Sewer and Water Systems – Final

Document no: 241112003914_ae2e7fe0 Revision: 01

City of Bradenton

December 2, 2024

City of Bradenton City Centre – Capacity Analysis for Sanitary Sewer and Water Systems – Final

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Contents Acronyms and abbreviations ......................................................................................................................................... iv

1. Background and Understanding

1.1 Project Overview and Drivers

1.2 Site Location and Constraints

1.3 Land Use and Population Projections

1.3.1 Existing Land Use

1.3.2 Future Land Use and Population Forecast

2. Proposed Development and Demands/Flows

2.1 Water and Wastewater Demand/Flow Criteria

2.1.1 Unit Water Demands and Sanitary Flows

2.1.2 Sanitary Sewer Inflow and Infiltration

2.1.3 Peaking Factors

2.2 Calculated Water Demands and Sanitary Sewer Flows

2.2.1 Fire Flows

3. Existing System Capacity Analysis

3.1 Capacity Analysis Criteria (Water and Sanitary Sewer)

3.2 Potable Water Distribution System

3.2.1 Existing Potable Water System

3.2.2 Water Demand Calculations and Capacity Requirements

3.2.3 Potable Water Capacity Analysis

3.3 Wastewater Collection System

3.3.1 Existing Wastewater System

3.3.2 Wastewater Flows Calculations and Capacity Requirements

3.3.3 Wastewater Collection System Capacity Analysis

3.3.4 Wastewater Lift Station and Rising Main Evaluation

3.4 Potable Water and Wastewater System Vulnerabilities to Natural Hazards

3.4.1 Coastal Flooding

3.4.2 Sea-Level Rise

3.4.3 Wastewater System Infiltration and Inflow

3.4.4 Saltwater/Air Corrosion

4. Proposed Improvements

4.1 Potable Water

4.1.1 Potable Water Proposed Improvements

4.1.2 Potable Water System Natural Hazard Resilience

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4.2 Wastewater Collection System

4.2.1 Wastewater Collection System Proposed Improvements

4.2.2 Wastewater Lift Station Proposed Improvements

4.2.3 Wastewater Collection System Natural Hazard Resilience

4.3 Other Resilience and Reliability Considerations

4.3.1 Minimum Design Elevation (for Flood Mitigation)

4.3.2 Backup Electric Power and Communications / Redundancy

4.3.3 Vehicular and Operator Access

4.3.4 Stormwater Management

4.3.5 High Wind Concerns with Trees and Flying Debris

4.3.6 Emergency Response Planning

4.4 Assumptions and Further Verification

5. Engineer’s Opinion of Probable Construction Cost for Infrastructure Improvements

5.1 Cost Estimate Basis

5.2 Cost Estimate Assumptions

5.3 Cost Estimate

6. References

Appendices Appendix A. Scope of Work

Appendix B. City Centre and Parking Garage Site Survey

Appendix C. Population, Water and Wastewater Projections

Appendix D. FAC 62-6.008 for Wastewater Discharge Rates

Appendix E. Water Demand Distribution Calculations

Appendix F. Cost Estimates

Tables Table 1. Proposed Development Water Demand and Sewage Discharge Assumptions and Calculations

Table 2. Water and Wastewater Analysis Criteria

Table 3. Estimated Pump Flows and Head for Existing, Planned Development, and Buildout Conditions ... 33

Table 4. Cost Estimate Summary

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Figures Figure 1. Capacity Analysis Limit of Work per Scope of Work Figure 2. Required Fire Flow within Project Limits Figure 3. Existing Water System – Analysis Area based on Skeletonized Network Figure 4. Velocity and Pressure Output for Existing Conditions Figure 5. MDD and Fire Flow Scenario Output for Existing Conditions Figure 6. Velocity and Pressure Output for Existing Conditions with Proposed Development Figure 7. PDD and Fire Flow Scenario Output for Existing Conditions with Proposed Development Figure 8. Velocity and Pressure Output for Existing Network, Build and Proposed Development Figure 9. PDD and Fire Flow Scenario Output for Existing Conditions plus Build-out with Proposed Development Figure 10. Assumed and Interpolated Pipe Diameters for Continuity in Wastewater Network Analysis Figure 11. Existing Wastewater Network and LS08 Collection Area Figure 12. Existing Rising Mains Arrangement for LS08 and Downstream System Figure 13. Maximum Depth in Pipes % for Existing Customers Figure 14. Maximum Depth in Pipes % for Existing Customers and Proposed Development Figure 15. Maximum Depth in Pipes % for Buildout and Proposed Development Figure 16. Lift Station Relocation Resilience versus Infrastructure Requirements Figure 17. Proposed Lift Station Locations In Relation To Flood Zones Figure 18. Proposed Lift Station Selected Location 3 Required Rerouting for Pipes Figure 19. Proposed Lift station Selected Location 3 Network Output and Depths Figure 20. Flow and Pressure Requirements for Existing, Proposed Development, and Buildout Scenarios Figure 21. Effective FEMA FIRM Panel Figure 22. National Oceanic and Atmospheric Administration 2017 Regional Sea-Level Rise Projection Curves Figure 23. Flow and Pressure Requirements for Existing, Proposed Development, and Buildout Scenarios Figure 24. Proposed Wastewater Network Upgrade Adjacent to Proposed Development Figure 25. Proposed Relocation for Lift Station and Associated Network Figure 26. Proposed Relocation for Lift Station and Associated Network

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Acronyms and abbreviations ADD average daily demand

ASCE American Society of Civil Engineers

ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning Engineers

City City of Bradenton

FAC Florida Administrative Code

FEMA Federal Emergency Management Agency

FIRM Flood Insurance Rate Maps ft² square foot gal/in-mi gallon(s) per inches per mile of pipe (used for I&I)

GIS geographic information system gpcd gallon(s) per capita per day gpd gallon(s) per day gpm gallon(s) per minute

I&C instrumentation and controls

I&I infiltration and inflow

LS0X Lift Station with Reference Number

MDD maximum daily demand

NAVD North American Vertical Datum

PDD peak daily demand

PHD peak hourly demand psi pound(s) per square inch

PVC polyvinyl chloride

SCADA Supervisory Control and Data Acquisition

VC vitrified clay

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1. Background and Understanding

1.1 Project Overview and Drivers

The City of Bradenton (City) is considering redevelopment of a portion of its City Centre property located at 101 Old Main Street in Bradenton, FL 34205 and has tasked Jacobs to prepare an engineering evaluation to assess the sanitary sewer and potable water infrastructure currently providing service to the site. The proposed developments include ground floor retail space, hotel, ballroom, rooftop restaurant with a bar and swimming pool, public green space, and rental apartments and condominiums. The results of the evaluation will be incorporated into the final deliverable referred to as the Capacity Analysis Report.

The project also involved evaluating the relocation of the existing lift station, which is currently situated northwest of the site area, adjacent to the Manatee River on 1st Avenue W Road, to a more resilient location outside the flood zone, while meeting or exceeding the capacity concerns. The scope of work is attached in Appendix A.

1.2 Site Location and Constraints

The project is located at 101 Old Main Street (12th Street West) in Bradenton, Florida. The site encompasses approximately 5.71 acres and is bounded by Barcarrota Boulevard to the north, 3rd Avenue West to the south, 10th Street West to the east, and 12th Street West to the west.

To determine the capacity of the surrounding water and wastewater infrastructure, it was necessary to consider the site’s physical boundaries from 9th Street West to 15th Street West, between Barcarrota Boulevard (1st Avenue West) and Manatee Avenue West. Figure 1 shows the current location and land use within the proposed capacity analysis area.

1.3 Land Use and Population Projections

The following subsections discuss land use and population projections in the project area.

1.3.1 Existing Land Use

The existing and future land use conditions are based on parcel data from the respective Manatee County Property Appraiser and the Manatee County Geographic Information System (GIS) Interactive Map. The Property Appraiser provided detailed information on land use, built-up areas, residential plot types, vacant plots, and other critical data relevant to water demand and wastewater discharge flows for both current conditions and future projections.

According to the site survey and the provided project site information for the proposed development (refer to Appendix B), the site encompasses 5.71 acres and includes one governmental administrative activity center, one municipal law enforcement activity center, one municipal parking lot, and one public parking garage.

Figure 1 illustrates the existing land use for the redevelopment plots and the site boundary as identifed in the scope of work (Appendix A) .

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Figure 1. Capacity Analysis Limit of Work per Scope of Work

As shown in Figure 1, the predominant land use for the site is non-residential. Therefore, estimating demand and sewage discharge based on population count would not provide an accurate tool for capacity analysis. A different approach was followed as explained in Section 2.

Appendix C.1 contains the overall Parcels calculations, while Appendix C.2 contains the current land use schedule and population count for the project site.

1.3.2 Future Land Use and Population Forecast

As outlined in the scope of work, the following activity centers are proposed for the project area parcels, replacing the current land use:

30,000 square feet (ft²) of ground floor retail space

One 130-room hotel

One 10,000-ft² ballroom

One 4,000- to 5,000-ft² rooftop restaurant, including a bar and swimming pool

Public green space (dimensions unknown)

350 rental apartments

95 condominiums

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For other parcels, future population and land use data were extracted from the following sources:

Residential population projections per parcel up to 2040 were obtained from the Online Mapping and Data for Southwest Florida Water Management District.

Manatee County Property Appraisal, referencing land marked as vacant with assigned land use that would require water demand and sewage discharge.

Appendix C.3 contains the future land use schedule and population forecast for the project site limit.

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2. Proposed Development and Demands/Flows

2.1 Water and Wastewater Demand/Flow Criteria

This section provides the criteria and methodology followed for water and wastewater flows calculations, and the proposed development demand and flows.

2.1.1 Unit Water Demands and Sanitary Flows

The site is predominantly categorized as non-residential, necessitating the estimation of water demands and sewage discharge based on land use categories. The Comprehensive Plan of Manatee County, Florida (Municipal Code Corporation and Manatee County, Florida. 2017), Policy 9.5.1.1, adopts an infrastructure standard for an average daily flow of 110 gallons of potable water per capita per day (gpcd), distributed as follows:

65 gpcd for residential users

30 gpcd for all business, industrial, and institutional users

15 gpcd for all miscellaneous and unaccounted users

The 65-gpcd criterion was applied exclusively to residential population projections. For other land uses, demand rates were applied from Table 1 in Florida Administrative Code (FAC) 62-6.008 System Size Determinations (provided in Appendix D), assuming a sewage-to-water ratio of 90%.

2.1.2 Sanitary Sewer Inflow and Infiltration

The infiltration and inflow (I&I) rates for the sanitary sewer gravity collection system were extracted from the City of Bradenton Inflow and Infiltration Analysis Plan (2021).

Based on the data, the rainfall per sewershed was analyzed using the wet season event from June 3 and 4, 2020, which resulted in a total rainfall of 22,301,242 gallons. This event is comparable to 3-inch and 4-inch rainfall events, with an average rainfall of 3.54 inches. The data indicate that there are 17 days annually with rainfall events exceeding 1 inch.

A storm with a 2-year return period in this region typically results in approximately 4.5 inches of rainfall within 24 hours. This suggests that the return period for the selected event is shorter, classifying it as an annual occurrence. The estimated percentage of rainfall entering the wastewater collection system was calculated to be 12.18%.

The estimated I&I for the project site area, falling under the LS08 sewershed, is 47,754 gallons per inch-mile.

2.1.3 Peaking Factors

The peaking factor for water demand used for the system capacity analysis was considered as per the “Manatee County Public Works Standards, Part 1” as follows:

Maximum/Peak Daily Demand: 1.5 × average daily demand (ADD)

Peak Hourly Demand: 2.2 x ADD

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The peaking factor for sewage flows was also adopted from the same reference, as follows:

Peaking Factor:

18+√𝑃 4+√𝑃

, where P is population in thousands (peak factor not to exceed 4)

2.2 Calculated Water Demands and Sanitary Sewer Flows

Table 1 presents the anticipated water demand and sanitary sewer flow calculations associated with the proposed development. The ADD for potable water and sewage discharge for the proposed development are 140,627 gallons per day (gpd) and 126,565 gpd, respectively.

2.2.1 Fire Flows

The required fire flows were considered as provided in the scope of work document and are presented in Figure 2.

Figure 2. Required Fire Flow within Project Limits

Based on the site classification, the required fire flow is predominantly 1,500 gpm.

City of Bradenton City Centre – Capacity Analysis for Sanitary Sewer and Water Systems – Final

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Table 1. Proposed Development Water Demand and Sewage Discharge Assumptions and Calculations

Item Land Use Count/ Area

Unit Discharge Unit for Discharge Rate

Land Usage Rate

Occupancy where applicable*

Unit Total Discharge (gpd)

Reference

A Retail 30,000 ft2 10 per 100 ft2 gpd NA 3,000 FAC 62-6.008

B.1 Hotel 130 Rooms 100 gpd per room 13,000 FAC 62-6.008

B.2 2 Laundry 750 gpd 1,500 FAC 62-6.008

C Ballroom 10,000 ft2 40 gpd per visitor 50% 17 ft2/ person

11,765 ASHRAE and FAC 62-6.008

D.1 Rooftop Restaurant, including a Bar and Swimming Pool

5,000 ft2 40 gpd per seat 60% 15 ft2/ seat 8,000 ASHRAE and FAC 62-6.008

D.2 1 Swimming Pool

10 gpd per visitor 30 visitor 300 FAC 62-6.008

F Rental Apartments

350 Apartments 200 gpd per apartment

70,000 FAC 62-6.008 considering 2-bedroom apartments

G Condos 95 Condos 200 gpd per unit 19,000 FAC 62-6.008 considering 2-bedroom apartments

Total Sewage Discharge (gpd) 126,565

Total Water Demand (gpd) 140,627 Calculated as 111% of sanitary sewer flows

ASHRAE = American Society of Heating, Refrigerating, and Air-Conditioning Engineers

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3. Existing System Capacity Analysis

3.1 Capacity Analysis Criteria (Water and Sanitary Sewer)

Table 2 summarizes the demand and flow analysis criteria for water and wastewater systems.

Table 2. Water and Wastewater Analysis Criteria

No. Parameter Criteria Reference

Water Demands

1 Population Projections The land use and population projections are detailed in Section 1.3 of this report

Section 1.3 of this report

2 Classification of Water Demands

Average Daily Demand (ADD) = ADD (potable water)

Maximum/Peak daily demand (PDD) =1.5 x ADD

Peak hourly demand (PHD) = 2.2 x ADD

Manatee County, Public Works Utilities Standards Manual, September 2023

3 Fire Suppression Water Demand

Fire flow requirement is 1,500+ gpm Attachment D to the Scope of Work Document

4 Analysis Scenarios Scenario 1: MDD + Fire Demand – Maintain Pressure as stated in item No 7 Scenario 2: PHD - Maintain Pressure as stated in item No. 7

Manatee County, Public Works Utilities Standards Manual, September 2023

5 Applicable Hydraulic Equation

Hazen Williams Equation Manatee County, Public Works Utilities Standards Manual, September 2023

6 Roughness Coefficient 130 Manatee County, Public Works Utilities Standards Manual, September 2023

7 Minimum Residual Pressure for Fire Flows

PDD+Fire Scenario:

20 psi

Manatee County, Public Works Utilities Standards Manual, September 2023

8 Minimum Residual Pressure at PHD

The value varies from reference to reference:

Manatee Public Works, American Water Works Association: 20 psi Water System Design Manual: 30 psi GLUMRB Recommended Standards for Water Works: 35 psi

Manatee County, Public Works Utilities Standards Manual, September 2023 Washington State Department of Health, Water System Design Manual, June 2020 GLUMRB Recommended Standards for Water Works, 2012

9 Velocity 5 fps at peak-hour flow conditions and no greater than 10 fps at MDD plus needed fire flow conditions

Manatee County, Public Works Utilities Standards Manual, September 2023

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No. Parameter Criteria Reference

Water Demands

10 Water Storage Requirements

25% of the system’s maximum-day water demand + fire storage requirements Storage shall maintain pressure of 35 psi at minimum water level

FAC 62-555.320 Design and Construction of Public Water Systems

Sanitary Sewerage Flows

1 Population projections The land use and population projections are detailed in Section 1.3

Section 1.3 of this report

2 Peak Factor Peaking Factor = 18+√P4+√P , where P is population in thousands (peak factor not to exceed 4).

Manatee County, Public Works Utilities Standards Manual, September 2023

3 Inflow and Infiltration 47,754 gal/in-mi City of Bradenton Inflow and Infiltration Analysis Plan, 2021

(Table 6-2 )

4 Maximum Percent Full of Pipe at Peak Flow (d/D ratio)

80% Manatee County, Public Works Utilities Standards Manual, September 2023

5 Applicable Hydraulic Equation

Manning’s Equation for gravity networks Hazen Williams for rising mains

GLUMRB Recommended Standards for Water Works, 2012 Manatee County, Public Works Utilities Standards Manual, September 2023

6 Coefficient of Roughness n = 0.013 for Manning Equation - Gravity Networks C= 120 for Hazen William - Rising Mains

7 Velocity Gravity Networks at PHD Minimum design velocity of 2 fps Maximum design velocity of 10 fps Rising Mains at PHD Minimum design velocity of 2 fps Maximum design velocity of 6 fps

Manatee County, Public Works Utilities Standards Manual, September 2023

8 Pipe Slopes As per Manatee County Public Works Standards, minimum slope for 8-inch pipe should be 0.42 foot per 100 feet

GLUMRB Recommended Standards for Water Works, 2012 Manatee County, Public Works Utilities Standards Manual, September 2023 fps = feet per second gal/in-mi gallon(s) per inches per mile of pipe GLUMRB = Great Lakes – Upper Mississippi River Board (also known as “10 States Standards”) MDD = maximum daily demand PDD = peak daily demand PHD = peak hourly demand psi = pound(s) per square inch

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3.2 Potable Water Distribution System

3.2.1 Existing Potable Water System

The existing water system data were provided in GIS format, with additional details in Figure 2 illustrating the pipe arrangement within the project limits.

As part of the capacity analysis for the designated project area, it is essential to note that this area receives its water supply from the City of Bradenton’s ground storage tanks, pumping station, water tower, and distribution lines. These facilities service multiple regions within the city through a hydraulically connected looped network.

For this analysis, the focus was confined to the project phase. To accurately simulate the velocity and head loss along common distribution lines, demand points were incorporated along the skeletonized sections to represent hydraulic losses along the pipeline. This methodology provides a more precise representation of system pressure.

Figure 3 illustrates the selected distribution network for analysis, along with the distribution of demand points at the synchronized network connections.

Figure 3. Existing Water System – Analysis Area based on Skeletonized Network

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The pumping station data were not provided. It was assumed that the discharge pressure from the pump station would be sufficient to fill the water towers. Therefore, the base water elevation of the water in the water tower was used as the starting point to determine the available network pressure values.

The water levels for the elevated tank were assumed as follows:

Elevation (Base): 131 feet

Elevation (Minimum): 132 feet

Elevation (Initial): 132.8 feet

Elevation (Maximum): 163 feet

3.2.2 Water Demand Calculations and Capacity Requirements

Water demands were calculated for existing customers, proposed development, and buildout conditions as explained in the following subsections.

3.2.2.1 Water Demand for Existing Customers

The distribution network for the project area is supplied directly from the City of Bradenton pumping station and water tower. Therefore, it was not possible to identify the capacity needs in isolation from the sitewide area. Section 3.2.1 discusses the identified parcels served by the existing water loop and the connection points representing the skeletonized sitewide network.

The average water demand for existing customers was calculated based on the criteria defined in Section 2.1.1. The total demand for the distribution area amounted to 253,876 gpd. Detailed calculations per parcel are included in Appendix C.4. The sheet was prepared for wastewater in compliance with FAC 62-6.008 (Appendix D), considering that wastewater discharge is 90% of the water demands, as per the Recommended Standards for Wastewater Facilities (GLUMRB 2014).

Demand at the skeletonized sections was calculated proportionally based on pipe section areas and the remaining city water demand. This approach allows for simulating the headloss in the pipeline serving the project area. Appendix E provides calculations for demand distribution at the connections to the sitewide network.

3.2.2.2 Water Demand for Proposed Development

The water demand and wastewater discharge for the proposed development were calculated explicitly, considering the provided land use per the scope of work detailed in Section 2.2. Table 1 shows the estimated water demand for proposed development.

3.2.2.3 Water Demand for Buildout Conditions

Section 2 summarizes the methodology used to estimate the requirements of future customers.

Appendix C.5 contains the water-demand calculations, differentiating between existing and future land use per parcel, as well as the buildout population for each parcel. The total demand for buildout conditions, including the proposed development, is 417,547 gpd.

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3.2.3 Potable Water Capacity Analysis

The analysis for the water network was carried out considering the calculated demands and confirming compliance with the design criteria summarized in Section 3.1

The key performance factors for the water system evaluation are velocity in pipes (which often correlates with headloss) and pressure.

3.2.3.1 Peak Hourly Demand Scenario for Existing System and Customers

Figure 4 shows the output for the peak hourly demand scenario for existing conditions.

Figure 4. Velocity and Pressure Output for Existing Conditions

The velocity in the main distribution line from the water tower was found to be higher than 5 fps; however, the pressure throughout the network meets the criteria during the PHD scenario. The high velocity in the main distribution pipeline section from the water tower can be attributed to the assumptions made regarding the water head in the water tower, which provided the available starting pressure in the network in the absence of main pump station data, and the skeletonization of the sitewide network demands.

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3.2.3.2 Maximum Daily Demand and Fire Scenario for Existing System and Customers

Figure 5 shows the model output for the MDD and fire flow scenario for existing conditions.

Figure 5. MDD and Fire Flow Scenario Output for Existing Conditions

Several hydrants within the network failed to provide the required flow of 1,500 gpm in compliance with the design criteria. Even when disregarding the velocity constraint of 10 fps, four hydrants were still unable to supply the required fire flow due to the headloss in the pipes during this scenario.

3.2.3.3 Peak Hourly Demand Scenario for Existing System and Customers with Proposed Development

Figure 6 shows the output for the peak hourly demand scenario for existing conditions, including the estimated water demand for the proposed development.

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Figure 6. Velocity and Pressure Output for Existing Conditions with Proposed Development

The analysis indicated a slight pressure reduction in the network, which remained within the acceptable criteria. The velocity in the main distribution line from the water tower increased slightly and exceeded the acceptable velocity threshold of 5 feet per second.

3.2.3.4 Peak Daily Demand and Fire Scenario for Existing System and Customers with Proposed Development

Figure 7 shows the model output for the PDD plus fire flow scenario for existing conditions with estimated proposed development demands.

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Figure 7. PDD and Fire Flow Scenario Output for Existing Conditions with Proposed Development

Several hydrants within the network failed to provide the required flow of 1,500 gpm in compliance with the design criteria. Even when disregarding the velocity constraint of 10 fps, five hydrants were still unable to supply the required fire flow due to the headloss in the pipes during this scenario.

3.2.3.5 Peak Hourly Demand Scenario for Existing System and Customers with Proposed Development

Figure 8 shows the output for the peak hourly demand scenario for existing conditions with estimated water demand for the proposed development.

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Figure 8. Velocity and Pressure Output for Existing Network, Build and Proposed Development

The analysis indicated a pressure reduction in the network, which remained within the acceptable criteria.

The velocity in the main distribution line from the water tower increased slightly and exceeded the acceptable velocity threshold of 5 fps compared to the baseline conditions.

3.2.3.6 Peak Daily Demand and Fire Scenario for Existing System, Buildout and Proposed Development

Figure 9 shows the model output for the PDD and fire flow scenario for existing conditions plus buildout with the estimated proposed development demands.

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Figure 9. PDD and Fire Flow Scenario Output for Existing Conditions plus Build-out with Proposed Development

In the initial run, considering the velocity and pressure constraints as per the design criteria, none of the fire hydrants were able to supply the required fire flow. Even when disregarding the velocity constraint, five hydrants still failed due to pressure constraints, with pressures falling below 20 psi.

3.2.3.7 Water Storage Analysis

The water storage requirement depends on the available storage, primarily in the water towers, which can maintain supply during peak hourly demand, fire scenarios, or emergencies, with the capacity to supply water at 35 psi.

Additional water storage would be recommended if the storage within the existing system is insufficient to meet the needs of existing customers and the proposed developments. The water storage was calculated as 25% of the MDD, per the FAC 62-555.320 requirements, amouting to 47,462 gallons, excluding fire storage requirements. The total storage requirements for the proposed project site area, considering 4 hours of storage for fire at 1,500 gpm, is 407,462 gallons.

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3.3 Wastewater Collection System

3.3.1 Existing Wastewater System

GIS and PDF layouts of the wastewater network were collected for the analysis. The data included the network layout, pipe diameters, and materials, as well as information on lift stations and rising mains.

Certain pipe diameters were either missing or appeared to be out of range. To address this, interpolations were made based on the upstream and downstream pipes to ensure continuity in analysis. Additionally, the invert levels for manholes were not included in the provided data; therefore, minimum pipe cover and minimum slopes were used to calculate the invert levels for the network.

Figure 10 shows main updated pipes and the assumed reasonable diameters.

Figure 10. Assumed and Interpolated Pipe Diameters for Continuity in Wastewater Network Analysis

The project area is located within the collection area of LS08. According to the scope of work, a capacity analysis was required for LS08. Consequently, the analysis limit was extended to include all plots within the LS08 collection area. This approach was essential because the project area contains the main collection pipes and the inlet pipe to the lift station, necessitating an analysis of sewage discharge from the various plots and parcels within the collection area.

Figure 11 shows the final existing wastewater network and the contributory area considered as part of the analysis (wastewater discharge quantities).

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Figure 11. Existing Wastewater Network and LS08 Collection Area

Existing data for the rising main from LS08 and downstream system were extracted from the GIS data and are presented in Figure 12.

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Figure 12. Existing Rising Mains Arrangement for LS08 and Downstream System

As shown in Figure 12, the rising mains from LS08 and LS07 combine into a single 18-inch-diameter rising main, which extends to the existing gravity network. The collected flow is then pumped through LS17 to the Sewage Treatment Plant.

No data were available for the lift stations; therefore, the existing sewage flow rates were used to establish a baseline condition for the lift station. However, this still requires verification against the lift stations’ actual flow-head curves.

3.3.2 Wastewater Flows Calculations and Capacity Requirements

Wastewater flows were calculated for existing customers, proposed development, and buildout conditions as explained in this section.

The wastewater discharge calculations were performed for the lift station collection area, as explained in Section 3.3.1.

An additional I&I rate of 477.54 gallons per inch-mile was added to the pipes, as provided in Table 6-2 of the I&I report.

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3.3.2.1 Wastewater Flows for Existing Customers

The project area is located within the collection area of LS08; therefore, the analysis limit was extended to include all plots within the LS08 collection area.

Calculations for existing customers within the LS08 collection area amounted to 380,901 gpd (Appendix C.6).

3.3.2.2 Wastewater Flows for Proposed Development

The wastewater flow for the proposed development was calculated explicitly, considering the provided land use as per the scope of work detailed in Section 2.2. Table 1 shows the estimated water demand for proposed development.

3.3.2.3 Wastewater Flows for Build Out Conditions

Section 2.1.1 summarizes the adopted methodology for estimating the requirements of future customers.

Appendix C.7 contains the wastewater calculations, differentiating between existing and future land use per parcel, as well as the buildout population for each parcel. The total flow for buildout conditions, including the proposed development, amounted to 606,061 gpd.

3.3.3 Wastewater Collection System Capacity Analysis

The evaluation of the wastewater system was conducted for the proposed project site area and its physical limits, while considering the overall LS08 collection area flow. This analysis aimed to evaluate the capacity of the collection mains within the project site, as well as the capacity of the lift station and associated rising main.

This section provides an evaluation of the wastewater system, taking into account the discharge from existing customers, proposed development, and buildout conditions. The provided data for the sewerage network did not include invert levels for manholes; therefore, to carry out the analysis, minimum pipe covers and slopes were assumed.

The primary parameter selected for evaluating the wastewater system capacity was the percent usage of the pipe, which should not exceed 80%. The wastewater network was tested against the discharge from existing customers, additional development flows, and buildout conditions.

3.3.3.1 Existing Network Analysis for Existing Customers

Figure 13 shows maximum depth/percent usage of the existing network for existing customers. Percent usage remained below 80% in all pipes.

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Figure 13. Maximum Depth in Pipes % for Existing Customers

3.3.3.2 Existing Network Analysis for Existing Customers and Proposed Development

Figure 14 shows maximum depth/percent usage of the existing network for existing customers and proposed development. Percent usage remained below 80% in all pipes. The existing 8-inch vitrified clay (VC) pipe adjacent to the development site reached a depth/rise percentage of 79.4%, closely approaching the allowable limit. Given the assumptions made and the early stage of the planned development, it is recommended to upgrade this pipe to a 12-inch polyvinyl chloride (PVC) pipe. This upgrade would also help reduce I&I, as the I&I rate in PVC pipes is significantly lower than in VC pipes, according to the I&I report.

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Figure 14. Maximum Depth in Pipes % for Existing Customers and Proposed Development

Existing Network Analysis for Build Out Conditions

As shown in Figure 15, the percent usage remained below 80% in all pipes. Several pipes’ maximum percentage use increased but remained within acceptable range. The pipeline section adjacent to the development showed the same close-to-limit high-percent usage as concluded from the proposed development analysis.

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Figure 15. Maximum Depth in Pipes % for Buildout and Proposed Development

3.3.4 Wastewater Lift Station and Rising Main Evaluation

The following subsections evaluate the existing lift station and rerouting options and present the rising main capacity analysis.

3.3.4.1 Wastewater Lift Station Relocation Evaluation

The selection of the pump station location requires a tradeoff between cost and resilience. A higher targeted elevation for the lift station enhances resilience but necessitates reversing the mainlines against gravity. This leads to longer and deeper rerouting of pipes, as well as an increased length of the rising main.

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Figure 16. Lift Station Relocation Resilience versus Infrastructure Requirements

Figure 17 shows the proposed locations for lift station relocation.

Figure 17. Proposed Lift Station Locations In Relation To Flood Zones

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The proposed locations were discussed with the City, and it was agreed to consider Location 3, next to Wilcox Property, because this land is available for the City to use for the lift station and complies with the resilience requirements.

Figure 18 shows the rerouted network considering the selected location within the greater-than-10.5-foot elevation zone next to Wilcox Property, to provide background on the overall requirements for the lift station relocation.

Figure 18. Proposed Lift Station Selected Location 3 Required Rerouting for Pipes

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Figure 19. Proposed Lift station Selected Location 3 Network Output and Depths

3.3.4.2 Lift Station and Rising Main Hydraulic Evaluation

The capacity analysis for the rising main was conducted considering various flow scenarios: existing conditions, existing conditions with proposed development, and buildout with proposed development scenarios. The as-built documentation for the lift station was not available for this analysis; therefore, the existing conditions were used to establish the baseline for the rising main evaluation.

Figure 20 shows the flow and pressure requirements for each scenario.

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Figure 20. Flow and Pressure Requirements for Existing, Proposed Development, and Buildout Scenarios

The estimated flow and head for the lift station should be compared against the current lift station capacity. Additionally, the LS07 rising main is connected to the rising main from LS08, making them interdependent. Further analysis is required for the downstream system, starting from the discharge line of the combined rising mains for LS07 and LS08 to the 24-inch gravity main and continuing to LS17 and its associated rising main up to the STP.

The velocity in the rising main exceeds 5 feet per second, and the head required increases by nearly 40% due to the proposed development and up to 60% under buildout conditions. Although the buildout conditions for LS07 are not within the scope of this study, it is anticipated that they will align with normal population growth.

To account for the buildout conditions for both lift stations, it is proposed to upgrade the rising main from LS08 from 10 to 12 inches and extend the LS08 rising main to the existing discharge manhole. This will prevent any impact from one lift station's rising main on the other.

3.4 Potable Water and Wastewater System Vulnerabilities to Natural Hazards

Due to the coastal location of the project site, components of the water and wastewater systems may be vulnerable to saltwater corrosion from high-chloride groundwater and salt air and from coastal flooding resulting from extreme tides and storm surge, which are anticipated to increase with sea-level rise over the service life of the assets. While buried piping or structures may not be directly affected by flooding, supporting electrical and mechanical equipment that are sensitive to flooding may be impacted by flooding resulting in service disruptions. In addition, flood impacts to operator access to the equipment may result in service disruptions before, during, or after a flood and should be evaluated.

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3.4.1 Coastal Flooding

The existing sanitary lift station is within the current 100-year floodplain, zone AE with a base flood elevation of 8 feet North American Vertical Datum (NAVD), as mapped in the effective Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRM) panel (Figure 21). Coastal flooding may result during extreme tides or from a storm-surge event. A closer look at the FEMA Flood Insurance Study is recommended to better understand the actual flood elevation and how it may change with sea-level rise over the asset’s service life.

Figure 21. Effective FEMA FIRM Panel

3.4.2 Sea-Level Rise

Sea-level rise alone is not expected to cause flooding to the proposed lift station locations. However, when coupled with extreme tides and storm surge, higher sea levels can increase the flood depths and duration of these flood events. Over the anticipated 20- to 30-year service life of the proposed sanitary lift station, approximately 1.0 to 1.5 feet of Sea Level Rise is anticipated. Figure 22 depicts the anticipated sea-level rise curves for the St. Petersburg Tide Gauge, from a year 2000 baseline.

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Figure 22. National Oceanic and Atmospheric Administration 2017 Regional Sea-Level Rise Projection Curves

3.4.3 Wastewater System Infiltration and Inflow

Climate change is expected to increase the frequency and intensity of extreme rainfall events and the elevation of groundwater resulting from sea-level rise., which can lead to increased sanitary flows from I&I and overwhelm wastewater collection and treatment systems. Increased I&I in the coastal environment can not only increase the base flows during rainfall and high-tide events but can also increase the chloride levels in the influent flows, which can adversely affect the type and level of treatment of the wastewater.

A detailed characterization of I&I can be helpful to better understand the location, type, and volumes of I&I within the collection system. This can be used to guide adaptation actions to mitigate this issue.

3.4.4 Saltwater/Air Corrosion

Corrosion from exposure of ferrous metals to salt water or salt air is a common threat that can shorten asset service life, increase maintenance costs, and reduce system reliability.

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4. Proposed Improvements

4.1 Potable Water

The results indicate that the water system has sufficient capacity to meet the required demands during peak-hour conditions. However, it fails to provide the required fire flows at several points. It is proposed to install 10- or 12-inch pipelines to create a supply loop, routed through the high-density areas of downtown. These proposed improvements are designed with sufficient capacity to accommodate both the proposed development and buildout conditions.

4.1.1 Potable Water Proposed Improvements

Figure 23 show the recommended improvements for the water supply network. The proposed improvements are sized to accommodate the proposed development and buildout conditions.

Figure 23. Flow and Pressure Requirements for Existing, Proposed Development, and Buildout Scenarios

According to the model output, the proposed upgrades provide sufficient capacity to deliver the required fire flow and PDD simultaneously, in compliance with the design criteria.

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4.1.2 Potable Water System Natural Hazard Resilience

Identifying threats and taking proactive action to mitigate these threats as potential points of failure, including both shocks and stressors, is key to enhancing system reliability and building resilience. This includes avoiding all single points of failure, where feasible, and enhancing system redundancies or backup systems.

Key considerations:

Elevating critical flood-sensitive water system components (e.g., pumps, electrical equipment) relative to projected flood levels (including sea-level rise) over the service life of the asset, including the latest industry guidance on freeboard (e.g., American Society of Civil Engineers [ASCE] 24-14).

Assessing the integrity of salt-sensitive equipment to combat corrosion.

Identifying backup power sources for pumps and treatment facilities to maintain reliable operations and a safe water supply before, during, and after extreme weather events.

Identifying backup communications for operators and emergency personnel, system Supervisory Control and Data Acquisition (SCADA), and two-way communication with power supply, including remote start and monitoring.

Developing contingency plans for alternative water sources if primary sources are compromised by flooding or contamination.

Develop interconnections with neighboring water systems for emergency supply.

4.2 Wastewater Collection System

The proposed improvements for the wastewater collection system are divided into two distinct sections.

The first section addresses the necessary enhancements for the existing system, excluding any modifications related to the lift station relocation. The second section considers the comprehensive changes required for the relocation of the wastewater lift station, including the associated network and rising main adjustments. This approach provides flexibility for the City, allowing to prioritize and implement improvements based on the immediate needs and long-term plans.

4.2.1 Wastewater Collection System Proposed Improvements

Figure 24 shows the proposed system improvements to wastewater collection network, mainly to account for the proposed development.

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Figure 24. Proposed Wastewater Network Upgrade Adjacent to Proposed Development

4.2.2 Wastewater Lift Station Proposed Improvements

As discussed in Section 3.3.4, the selection of the pump station location involves balancing cost and resilience. Higher elevations for the lift station improve resilience but require reversing the mainlines against gravity, leading to longer and deeper rerouting of pipes and an increased length of the rising main.

The proposed location was discussed with the City, and it was agreed to consider Location 3, as presented in Section 3.3.4

Figure 25 shows the proposed relocation for the lift station and the proposed rerouting for the collection network towards the new location.

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Figure 25. Proposed Relocation for Lift Station and Associated Network

Table 3 shows the estimated flows for the lift station. The proposed lift station should be designed with sufficient capacity to accommodate the buildout and proposed development.

Table 3. Estimated Pump Flows and Head for Existing, Planned Development, and Buildout Conditions

Scenario Estimated Flow (gpm)

Estimated Pump Head (feet)

Existing Customers 1,067 40

Existing Customers with Planned Development 1,325 57

Build out with Development 1,438 64

The as-built documentation for the lift station, mainly the pump curves, was not available for this analysis.

The proposed development increases the velocity and head requirements in the rising main. To accommodate future buildout conditions, it is recommended to upgrade the LS08 rising main from 10 to 12 inches and extend it to the existing discharge manhole. This upgrade will ensure that the rising mains of LS07 and LS08 do not interfere with each other.

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The proposed pipeline route avoids routing the pipeline along the Florida Department of Transportation highways.

Figure 26. Proposed Relocation for Lift Station and Associated Network

4.2.3 Wastewater Collection System Natural Hazard Resilience

Identifying threats and taking proactive action to mitigate these threats as potential points of failure, including both shocks and stressors, is key to enhancing system reliability and building resilience. This includes avoiding all single points of failure, where feasible, and enhancing system redundancies or backup systems.

Key considerations:

Elevating critical flood-sensitive water system components (e.g., pumps, electrical equipment) relative to projected flood levels (including sea-level rise) over the service life of the asset, including the latest industry guidance on freeboard (e.g., ASCE 24-14).

Elevate electrical power supply (e.g., ground mounted transformer) above anticipated flood stage, in concert with other critical equipment.

Flood-harden or elevate vents, hatches, and access points above flood levels.

Assessing the integrity of salt-sensitive equipment to combat corrosion.

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Evaluate the capacity of the existing collection system, lift stations, and treatment plant to handle projected increases in peak flows during intense storms.

Addressing I&I to reduce excessive flows that could lead to a wastewater overflow/spill.

Identifying backup power sources for pumps and treatment facilities to maintain reliable operations and a safe water supply before, during, and after extreme weather events.

Identifying backup communications for operators and emergency personnel, system SCADA, and two-way communication with power supply, including remote start and monitoring.

Developing contingency plans for alternative water sources if primary sources are compromised by flooding or contamination.

Use corrosion-resistant materials like stainless steel or fiberglass for wet well structures and components.

Install energy-efficient (e.g., variable speed) pumps and equipment to reduce vulnerability to extreme heat.

System redundancy:

Use redundant pumps that allow jockeying to avoid overheating or premature pump wear.

Upsize pumps and force mains to handle projected future peak flows.

Expand wet well storage volume to provide additional emergency holding time.

Consider parallel force mains for redundancy on critical stations.

4.3 Other Resilience and Reliability Considerations

The recommendations in the following subsections are intended to mitigate risk and enhance service reliability of the proposed lift station, potable water distribution system, and associated improvements against natural hazards today and over the service life of the assets.

4.3.1 Minimum Design Elevation (for Flood Mitigation)

The minimum design elevations assume a 30-year service life and a designation of the sanitary lift station as a critical asset.

The specific elevations may vary depending on specific location. Validation and refinement of these minimum design elevations is needed once a site is selected for the lift station.

4.3.1.1 Electrical and Mechanical Equipment

The following minimum design elevations are for flood-sensitive electrical and mechanical equipment, at the lowest point of failure of each piece of equipment. This includes the bottom of electrical panels or junction boxes; electrical transformers; heating, ventilation, and air conditioning; and supporting equipment.

Minimum Design Elevation: 11.5 feet NAVD

FEMA FIRM base flood elevation 8 feet + 1.5 feet of sea level rise + 2-foot freeboard (ASCE 24-14)

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4.3.1.2 Alternative Flood Proofing Methods

Where elevating equipment is not possible or poses operational challenges, implement the following:

Use elevated platforms with ramps or lifts.

Design modular, easily replaceable components for infrastructure below the design flood elevation.

Create redundant systems at different elevations to ensure continued operation during various flood scenarios.

Installing flood panels over building openings and vents.

Sealing pipe penetrations and building envelopes.

4.3.2 Backup Electric Power and Communications / Redundancy

Redundant Electric Supply:

Provide redundant power feeds from separate electrical grids (substations) where possible.

Backup Power:

Install permanent backup generators sized to run all critical equipment.

Elevate fuel tanks and provide 72-hour minimum fuel storage capacity.

Establish redundant vendor contracts for fueling lift station.

Consider solar panels with battery storage as supplemental power.

Improved Monitoring and Controls:

Install flood level sensors and alarms.

Upgrade to SCADA systems with remote monitoring and control capabilities.

Implement smart pump controls to optimize efficiency and reduce wear.

4.3.3 Vehicular and Operator Access

Maintain a form of safe access to critical equipment for operators. Include Standard Operating

Procedures for access during, before, and after a flood event to determine when and how to access equipment safely.

Specify concrete or polymer-modified asphalt for road surfaces in flood-prone areas to enhance durability.

Ensure access routes have a minimum 12-foot width for single-lane and 24-foot width for two-lane emergency…