14-Attachment F SC Hillsborough County Potable Water Modeling TM Final (1).pdf

SOUTH-CENTRAL POTABLE WATER

SYSTEM HYDRAULIC MODELING

BLACK & VEATCH PROJECT NO.417207

PREPARED FOR

HILLSBOROUGH COUNTY

14 NOVEMBER 2024

HILLSBOROUGH COUNTY | SOUTH-CENTRAL POTABLE WATER SYSTEM HYDRAULIC MODELING

BLACK & VEATCH

Professional Engineer: 14 Nov 2024 Signature Date

Amanda Schwerman Printed Name

70751 License No.

BLACK & VEATCH | Table of Contents i

Table of Contents

1.0 Introduction

2.0 Hydraulic Model Review and Updates

2.1 Existing System Summary

2.1.1 Central Hillsborough Water Treatment Facility

2.1.2 Lithia Water Treatment Facility

2.1.3 South County Booster Pump Station

2.1.4 South County Repump Station

2.2 Existing System Model Updates

2.2.1 Pipeline Improvement Projects

2.2.2 Water Campus

2.2.3 Palm River Service Area

3.0 Population and Demand Projections

3.1 Population Projections

3.2 Average Day Demand Projections

3.2.1 Peaking Factors and Diurnal Demand Patterns

3.3 Spatial Allocation of System Demands

3.4 Operational Targets

4.0 Hydraulic Modeling Scenarios and Results

4.1 Improvements Required for Palm River Acquisition

4.2 Improvements Required for Year 2050

4.2.1 Operational Target 40 - 100 psi

4.2.2 Operational Target 45 - 90 psi

4.3 Improvements Required for Year 2035

4.3.1 Operational Target 40 - 100 psi

4.3.2 Operational Target 45 - 90 psi

5.0 Conclusions and Recommendations

Appendix A. 3/7/2024 Meeting Minutes and Slides

Appendix B. 5/2/2024 Meeting Minutes and Slides

Appendix C. 5/16/2024 Meeting Minutes and Slides

Appendix D. 5/30/2024 Meeting Minutes and Slides

BLACK & VEATCH | Table of Contents i

LIST OF TABLES

Table 1 Functional Population Projections

Table 2 Projected Average Day Demands for Service Areas

Table 3 Demand Projection Summary for the Combined South-Central and Palm River Service Area

Table 4 Recommendations for future planning years

LIST OF FIGURES

Figure 1 Existing South-Central Water Distribution System

Figure 2 Updated South-Central Potable Water Distribution System

Figure 3 Diurnal Demand Patterns for Select Dates in 2023 (Data Provided by County)

Figure 4 Adjusted Diurnal Demand Pattern

Figure 5 Parcel Demand for 2025 Average Day Demand (ADD)

Figure 6 Parcel Demand for 2035 Average Day Demand (ADD)

Figure 7 Parcel Demand for 2050 Average Day Demand (ADD)

Figure 8 Palm River Interconnects, Existing (Green) and Proposed (Orange)

Figure 9 Palm River Service Area with and without Pipe Closure at US 41

Figure 10 Baseline Results for 2050 MDD, 40 – 100 psi

Figure 11 Results with Additional Improvements including Repump Pipeline and POC, 2050 MDD, 40 – 100 psi

Figure 16 Proposed improvements for 40 – 100 psi

Figure 12 Baseline Results for 2050 MDD, 45 – 90 psi

Figure 13 Results with Additional Improvements including Repump Pipeline and POC, 2050 MDD, 45 – 90 psi

Figure 14 Baseline Results for 2035 MDD, 40 – 100 psi

Figure 15 Baseline Results, 2035 MDD, 45 – 90 psi

Figure 17 Proposed improvements for 45 – 90 psi

BLACK & VEATCH | Introduction 1

1.0 Introduction

In 2023, Hillsborough County retained Black & Veatch (BV) to perform hydraulic modeling for their potable and reclaimed water systems. To date, the County has requested no work on the reclaimed water system.

The County identified two topics for evaluation for the South-Central Potable Water System service area, including the acquisition and integration of the Palm River Service Area and the selection of operational pressure targets, or levels of service, while considering impacts on future system improvements.

BV has had multiple meetings with the County to determine modeling scenarios and to review model evaluation results. This Technical Memorandum (TM) serves to document major updates and findings from these meetings to date. This TM includes the following:

Hydraulic Model Review and Updates

Population and Demand Projections

Hydraulic Modeling for Years 2025, 2035, and 2050

Recommendations to meet Operational Targets

The intent of this TM is to provide a high-level summary of the results and discussions from the various meetings held. Detailed meeting minutes and slide decks are attached to this TM as appendices to provide more detail.

BLACK & VEATCH | Hydraulic Model Review and Updates 2

2.0 Hydraulic Model Review and Updates

2.1 Existing System Summary

The Hillsborough County South-Central Potable Water System currently consists of two water treatment facilities (the Central Hillsborough Water Treatment Facility (CHWTF) and Lithia Water Treatment Facility (Lithia WTF)), the South County Repump Station (SCRS), the South County Booster Pump Station (SCBPS), and the distribution system consisting of approximately 2,000 miles of transmission and distribution piping ranging from 1 inch to 54 inches in diameter. Figure 1 shows the existing system with water treatment facilities, repump station, and booster pump station.

2.1.1 Central Hillsborough Water Treatment Facility

The CHWTF supplies potable water to the northwest part of the South-Central distribution system and is permitted for 25 million gallons per day (MGD) maximum day flow. The CHWTF consists of four (4) pumps operated on variable frequency drives (VFDs) with space for two additional future pumps.

2.1.2 Lithia Water Treatment Facility

The Lithia WTF operates with five (5) VFD pumps capable of pumping to separate discharge headers (north and south). The north discharge header supplies water to the northeast portion of the distribution system. The south discharge header is currently the primary source of water for the southern part of the South-Central distribution system. The Lithia WTF is permitted for 73 MGD maximum day flow.

2.1.3 South County Booster Pump Station

The SCBPS facility is designed as an in-line booster pump station to increase the pressure from the Lithia south discharge header and supply water to the southern part of the South-Central distribution system.

The SCBPS consists of two (2) VFD pumps.

2.1.4 South County Repump Station

The SCRS consists of two 3 million-gallon (MG) ground-level storage tanks and five (5) VFD pumps in the southwest part of the South-Central distribution system. The SCRS provides storage that facilitates meeting peak demands and boosts pressure to the southwestern portion of the distribution system.

2.2 Existing System Model Updates

The existing South-Central potable water distribution system model was updated with pipeline improvements, the Water Campus (a new water treatment facility), and the Palm River service area. These updates are described below.

2.2.1 Pipeline Improvement Projects

The Big Bend Pipeline is a 36-inch transmission main which begins at the intersection of US Highway 301 South and Big Bend Road and ties into an existing 24-inch water main at the intersection of Big Bend Road and North US Highway 41. The Big Bend Pipeline was incorporated into the model based on design drawings provided by the County.

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Figure 1 Existing South-Central Water Distribution System

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The South County Potable Water Transmission Main includes a combination of 42-inch and 48-inch pipeline that begins at the SCBPS and ties into an existing 36-inch water main at the South US Highway 301. Its primary purpose is to convey water to the southern area of the distribution system. This pipeline will be the primary transmission pipeline for the new water treatment facility (described below). The South County Potable Water Transmission Main was incorporated into the model based on information provided by the County.

The 19th Avenue Pipeline is a proposed future 36-inch pipeline that would convey water from the 48-inch South County Potable Water Transmission Main at W. Lake Drive to the 30-inch pipe at 19th Avenue NE (the 30-inch pipe that turns south to the SCRS). The 19th Avenue Pipeline was required for all 2050 model scenarios.

Development pipes were added to the model based on information provided by the County. These pipe improvements included:

o A 12-inch main that connects from the South County Potable Water Transmission Main near County Road 672 and terminates at Berry Grove Road to the south. This pipeline includes a 12-inch connection to the existing piping near Bishop Road and Lagoon Shore Boulevard and extends until S. U.S. Highway 301.

o Two 12-inch pipelines were added to connect existing pipes in the Waterset development to the 24-inch pipeline along 19th Avenue NE.

2.2.2 Water Campus

The Water Campus is a new water treatment facility (WTF) which is anticipated to be completed in 2028.

This WTF will be supplied by the Balm Point of Connection (POC) on the new Tampa Bay Water (TBW) South Hillsborough Pipeline (SHP). The Water Campus will add a new water supply point to the southeast portion of the South-Central potable water distribution system, discharging through two headers (north and south) into the South County Potable Water Transmission Main. The capacity of the plant has not been established; the plant was limited to 50 MGD daily capacity for this analysis based on a preliminary recommendation by the County.

2.2.3 Palm River Service Area

The Palm River service area is about 35 square miles and currently includes over 10,500 single- and multi-family residential units. The Palm River area is adjacent to the South-Central distribution system west and south of the CHWTF. It is currently being served by the City of Tampa’s distribution system. Hillsborough County is in the process of acquiring the Palm River service area from the City of Tampa.

To incorporate this change, the South-Central distribution system model was updated with the Palm River service area’s pipes based on the service area polygon that was obtained by Palm River Final Valuation report provided by the County. Pipes and junctions for this area were imported from the City of Tampa’s distribution system model using InfoWater’s GIS Gateway tool.

The Palm River Service Area, Big Bend Pipeline, South County Potable Water Transmission Main, Development Pipe and Water Campus will be referred to as County-proposed improvements in this memorandum.

Figure 2 shows the updated system with existing and proposed pipeline improvements, the Palm River service area, and the Water Campus.

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Figure 2 Updated South-Central Potable Water Distribution System

BLACK & VEATCH | Population and Demand Projections 6

3.0 Population and Demand Projections

This section provides information on the methodology used to compute the overall system demands for different planning scenarios (2025, 2028, 2030, 2040, 2045, and 2050), as well as the procedure in which those demands are allocated spatially across the distribution system.

3.1 Population Projections

Parcel-level population estimates from SWFWMD (Southwest Florida Water Management District), based on 2022 estimates from the University of Florida Bureau of Economic and Business Research (BEBR), were analyzed to project the population within the South-Central service area for the years 2025 through 2050.

The BEBR functional population, which is obtained by adding the seasonal population to the residential population, was used to compute the projected population estimates. Table 1 provides a summary of the functional population projections for the South-Central service area.

It was noted in meetings with the County that potential future growth areas along the I-4 corridor and south of the Little Manatee River are not included in this study. Once more information is available regarding these future growth areas, additional modeling is recommended to identify the impact on the improvements proposed in this report.

Table 1 Functional Population Projections

Year of Projection South-Central Hillsborough

Service Area Palm River

Service Area Combined (Total)

2025 576,380 40,570 616,950

2028 606,947 45,013 651,960

2030 627,325 47,974 675,299

2035 669,146 47,171 716,317

2040 706,305 47,419 753,724

2045 734,071 47,617 781,688

2050 744,018 47,812 791,830

3.2 Average Day Demand Projections

Demands projections for future years were calculated using 2021 base year demands plus 150 gallons per capita per day (GPCD) for the projected change in functional population for both South-Central Hillsborough and Palm River Service Areas. Table 2 summarizes the projected Average Day Demands for the two service areas. These demand projections are a combination of customer consumption, non-revenue water (NRW), and wholesale demands. Note that flushing demands are not included in the model.

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Table 2 Projected Average Day Demands for Service Areas

Year of Projection

Average Day Demand (ADD)

Hillsborough Service Area

Palm River Service Area

Total Demand ADD (mgd)

2025 59.4 4.2 63.6

2028 63.9 4.8 68.7

2030 67.1 5.2 72.3

2035 73.8 5.4 79.2

2040 79.4 5.4 84.8

2045 83.6 5.4 89.0

2050 85.1 5.5 90.6

3.2.1 Peaking Factors and Diurnal Demand Patterns

The Average Day Demand (ADD) for each planning year was computed as described above. However, water distribution piping and facilities are typically designed to meet pressure and/or flow criteria for maximum day demand (MDD) and peak hour demand (PHD). Peaking factors, also known as demand ratios, can be utilized in the hydraulic model to increase or decrease system demands to match the different demand scenarios. Peaking factors for the South-Central system were developed based on SCADA data in order to convert ADD projections to MDD and PHD. A peaking factor of 1.4 was applied for MDD to ADD, while 1.65 was used for PHD to MDD. The peaking factors were applied to the ADD projections to obtain the demand projections summarized in Table 3.

A diurnal pattern was established in order to run extended period simulations (EPS) in the hydraulic model. The normalized diurnal patterns for different dates were compared, and May 19th was identified as the maximum day demand for the year 2023 (see Figure 3). The normalized pattern for May 19th, 2023, was then compared to the pattern in the existing model provided by the County (see Figure 4) which includes a PHD factor of 1.65. This existing pattern was ultimately selected for use in this study.

Table 3 Demand Projection Summary for the Combined South-Central and Palm River Service Area

Year

Average Day Demand

(ADD) MDD/ADD

Maximum Day Demand

(MDD) PHD/MDD

Peak Hour Demand

(PHD)

2025 63.6 1.4 89 1.65 146.8

2028 68.7 1.4 96.2 1.65 158.7

2030 72.3 1.4 101.2 1.65 166.9

2035 79.2 1.4 110.8 1.65 182.8

2040 84.8 1.4 118.7 1.65 195.8

2045 89 1.4 124.6 1.65 205.5

2050 90.6 1.4 126.8 1.65 209.2

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Figure 3 Diurnal Demand Patterns for Select Dates in 2023 (Data Provided by County)

Figure 4 Adjusted Diurnal Demand Pattern

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3.3 Spatial Allocation of System Demands

The spatial allocation of demands within a distribution system is important for making planning decisions regarding future infrastructure improvements. To accurately model the existing and future demands, and their impacts on the distribution system, it is important to know where those demands are located.

To spatially allocate current and future demand within the South-Central service area, parcel-level demand projections were calculated using the SWFWMD data described in Section 3.1. For each planning year and for each parcel, the ADD was calculated as the 2021 demand plus the projected future increase in consumption (projected functional population increase * 150 GPCD).

The total planning year demand was divided into three demand categories for application in the hydraulic model. Demand 1 consisted of the existing 2021 demands and was allocated to the nearest model junction, regardless of pipe size. Small future growth (< 10 gpm growth from 2021 to 2050) was also assigned to the nearest junction as Demand 2. Large future growth (>= 10 gpm from 2021 to 2050) was allocated as Demand 3 to junctions that are connected to a pipe with diameter greater than or equal to 12 inches. This allocation method acknowledges that future developments (with large demand growth) will likely require localized improvements to the distribution system. This allocation process was repeated for all of the planning years. Figure 5, Figure 6 and Figure 7 show the demands allocated for planning years 2025, 2035, and 2050.

3.4 Operational Targets

Two sets of operational targets were considered for hydraulic evaluations in this TM:

Operational Target 40 – 100 pounds per square inch (psi):

o Minimum Pressure = 40 psi o Maximum Pressure = 100 psi

Operational Target 45 – 90 psi:

o Minimum Pressure = 45 psi o Maximum Pressure = 90 psi

Both sets of operational targets were evaluated for planning years 2035 and 2050 to establish infrastructure improvements that would be required to meet the targets.

BLACK & VEATCH | Population and Demand Projections 10

Figure 5 Parcel Demand for 2025 Average Day Demand (ADD)

BLACK & VEATCH | Population and Demand Projections 11

Figure 6 Parcel Demand for 2035 Average Day Demand (ADD)

BLACK & VEATCH | Population and Demand Projections 12

Figure 7 Parcel Demand for 2050 Average Day Demand (ADD)

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 13

4.0 Hydraulic Modeling Scenarios and Results

The outline of this section follows the timeline of model evaluations and meetings with the County.

Section 4.1 identifies improvements required for the acquisition and integration of the Palm River Service area. This evaluation was conducted using a 2025 MDD scenario with the operational target of 40 – 100 psi. Results for this section were initially shared at the 3/7/2024 meeting (meeting minutes and slides in Appendix A).

Section 4.2 presents evaluations of 2050 MDD conditions for both sets of operational targets (40

– 100 psi and 45 – 90 psi). These evaluations identified multiple future improvement projects to address areas of low and high pressure. This section identifies a few key infrastructure improvements for the southern portion of the system and presents a range of potential solutions to address low pressure areas in the northern portion of the system. Results for this section were initially shared at the 5/2/2024 and 5/16/2024 meetings (minutes and slides in Appendix B and Appendix C, respectively).

Section 4.3 presents evaluations of 2035 MDD conditions for both sets of operational targets (40

– 100 psi and 45 – 90 psi). The focus of this evaluation was to identify which of the improvements identified for 2050 MDD would be required by 2035. The focus of this evaluation was on the key improvements identified for the southern portion of the system. Results for this section were initially shared at the 5/30/2024 meeting (minutes and slides in Appendix D).

4.1 Improvements Required for Palm River Acquisition

Improvements required for integration of the Palm River service area were evaluated for the 2025 Maximum Day Demand (MDD) scenario for the operational target of 40 – 100 psi. The Palm River service area was disconnected from the City of Tampa’s (COT) distribution system and connected to County’s distribution system via existing and proposed interconnects. The model included County-proposed improvements, existing and proposed interconnects, and a pressure reducing valve (PRV) with a setting of 75 psi on the proposed 36-inch transmission main near CHWTF. The pressure setting of 75 psi was identified in order to maintain pressures in the Palm River service area similar to pressures currently served by the COT.

Figure 8 shows the existing (green) and proposed (orange) interconnections between the Palm River service area and the South-Central distribution system. More detailed maps of the interconnections are provided in the 3/7/2024 meeting slides (Appendix A).

Figure 9 shows the minimum pressures with and without a proposed pipe closure on the 14-inch diameter pipe along US 41 near the Alafia River crossing. This closure (proposed by the County) resulted in small decreases in minimum pressures in the Palm River Service area and small increases in minimum pressures in the southern part of the system. The pipe on US 41 was modeled as closed for all other scenarios presented in this TM.

Additional system modifications were evaluated for the 2025 scenario, including a pipe closure on Bloomingdale Avenue and a proposed new point of connection (POC) with TBW SHP project Segment A (referred to in this TM as the Segment A POC). Results for these evaluations can be found in the slide deck for the 3/7/2024 meeting (Appendix A).

Table 4, included in Section 5.0, provides a list of improvements required for each scenario documented in this TM.

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 14

Figure 8 Palm River Interconnects, Existing (Green) and Proposed (Orange)

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 15

Figure 9 Palm River Service Area with and without Pipe Closure at US 41

4.2 Improvements Required for Year 2050

Modeling was performed for both sets of operational targets (40 – 100 psi and 45 – 90 psi) for the 2050 MDD scenario. The goal of this evaluation was to establish the infrastructure improvements that would be required to meet the targets for 2050 demands. The baseline model for this scenario includes the following County-proposed projects:

The new Water Treatment Facility (WTF) with dual discharge headers, north and south

The Big Bend Pipeline

Development pipes in the southeastern portion of the system, as described in Section 2.2.

The South County Potable Water Transmission Main

The 19th Avenue Pipeline, modified to terminate near the intersection of 19th Avenue NE and Cypress Village Boulevard with a connection to the existing 30-inch pipeline on 19th Avenue NE

A small booster pump station (BPS) southeast of the Water Campus to serve future growth in the area of higher elevations along and south of County Road 672 (see Figure 10)

Controls for the pump stations (PSs) at the WTFs, the SCRS, and the SCBPS were adjusted to limit the daily average flow from the Water Campus to less than 50 MGD (see Section 2.2.2) while maintaining discharge pressures below the maximum pressure criterion for each operational target. For each scenario, considerable effort was made to adjust the PS controls to maintain pressures within the identified target range.

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 16

4.2.1 Operational Target 40 - 100 psi

Figure 10 shows the minimum and maximum pressure results for the 2050 MDD without additional improvements for the 40 – 100 psi operational target. Low pressures (below 40 psi) were observed in the north, central, southwest, and northeast portions of the system. Figure 11 shows minimum and maximum pressure results for the 2050 MDD scenario including the repump pipeline in the south, the proposed Segment A POC in the central portion of the system, and the Williams Road and Lithia North pipelines to address low pressure areas in the north.

Various alternatives were evaluated and presented at the 5/16/2024 meeting (Appendix C), including:

South portion of the system: Pressure results were evaluated for the south portion of the system to compare the BV-proposed Repump Pipeline with the Ruskin Pipeline, previously identified by the County. Both pipeline alternatives provide the ability to maintain pressures > 40 psi in the southern portion of the system. The Repump Pipeline would reduce diurnal pressure fluctuations near the SCRS. Selection of a pipeline alternative for the south portion of the system should take into account potential expansion of the Urban Service Area south of the Little Manatee River. In addition, selection of the pipeline alignment should consider the selection of alignment for a future pipeline for the reclaimed water system in this area.

Central portion of the system: Pressure results were evaluated for the central portion of the system with the proposed Segment A POC and with an alternative pipeline that would extend from the SCBPS along Balm River View Road and McMullen Road to the north. Both alternatives were able to maintain minimum pressures > 40 psi.

North portion of the system: Pressure results were evaluated for the proposed Williams Road and Lithia North pipelines. Alternatives to the Lithia North pipeline were discussed in conjunction with the 45 – 90 psi operational target and would include booster pumping stations, potentially coupled with new (possibly smaller diameter and/or shorter) pipelines. A potential new POC with TBW near the Brandon BPS was also discussed. Improvements on the northeast side of the system should consider potential expansion of the Urban Service Area along the I-4 corridor (to the northeast of the existing service area).

The slides and minutes for the 5/16/2024 meeting include additional results for and discussion of these improvements (Appendix C). Table 4 in Section 5.0 summarizes improvements proposed to meet the 40

– 100 psi operational target. Figure 12 shows the locations of these proposed improvements.

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Figure 10 Baseline Results for 2050 MDD, 40 – 100 psi

Figure 11 Results with Additional Improvements including Repump Pipeline and POC, 2050 MDD, 40 – 100 psi

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Figure 12 Proposed Improvements for the 40 – 100 psi Operational Target

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 19

4.2.2 Operational Target 45 - 90 psi

Figure 13 shows the minimum and maximum pressures for the 2050 MDD scenario without additional improvements for the 45 – 90 psi operational target. Low pressures (< 45 psi) were observed in the north, northeast, central, southeast, and southwest portions of the system. High pressures (> 90 psi) were observed in the lower-lying portions of the system in the Apollo Beach area and near the Lithia WTF and CHWTF discharge headers. Due to the range in elevations across the service area, the operational target of 45 – 90 psi would require the establishment of pressure zones to maintain target pressures in areas of higher and lower elevation.

Pressure zones (high and low) were established in the model to increase minimum pressures in the north and northeast portions of the system, while simultaneously decreasing maximum pressures in the Apollo Beach area in the southwest.

Table 4 in Section 5 lists the improvements proposed to meet the 45 – 90 psi operational target for the 2050 MDD. Figure 14 shows the minimum and maximum pressure values with the proposed improvements, including the Repump Pipeline alternative and the proposed Segment A POC in the central portion of the service area. Figure 15 shows the locations of the proposed improvements.

Various alternatives were evaluated and presented at the 5/16/2024 meeting (Appendix C), including:

South portion of the system: Figure 14 shows results with the BV-proposed Repump Pipeline. An evaluation was also conducted with the Ruskin Pipeline, previously identified by the County. Both pipeline alternatives provide the ability to maintain pressures > 45 psi in the southern portion of the system. The Repump Pipeline would reduce pressure fluctuations near the SCRS. Selection of a pipeline alternative for the south portion of the system should take into account potential expansion of the Urban Service Area south of the Little Manatee River. In addition, selection of the pipeline alignment should consider the alignment for a future pipeline for the reclaimed water system in this area.

Central portion of the system: Figure 14 shows results including the Segment A POC with TBW along Segment A of the SHP. Results were also evaluated with an alternative pipeline that would extend from the SCBPS along Balm River View Road and McMullen Road to the north. Both alternatives were able to maintain minimum pressures > 45 psi.

Apollo Beach area: multiple larger-diameter PRVs (approximately 10) would be required to reduce pressure into the low-lying areas in the southwest portion of the system.

North portion of the system: Figure 14 includes the Williams Road pipeline, a 35 MGD BPS in the Bloomingdale area, and at least one large-diameter PRV, located on a 24-inch pipe near the intersection of S. King Avenue and W. Lumsden Road. Even with these improvements, there are multiple areas of low pressure (< 45 psi) still shown in Figure 14. Alternative improvements were introduced and discussed at the 5/16/2024 (Appendix C) meeting and include various combinations of new transmission pipelines and booster pumping stations. A potential new POC with TBW near the Brandon BPS was also discussed but not evaluated in the model.

Improvements in the northeast portion the system should consider potential expansion of the Urban Service Area in the I-4 corridor (to the northeast of the existing service area).

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Figure 13 Baseline Results for 2050 MDD, 45 – 90 psi

Figure 14 Results with Additional Improvements including Repump Pipeline and POC, 2050 MDD, 45 – 90 psi

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Figure 15 Proposed Improvements for 45 – 90 psi Operational Target

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4.3 Improvements Required for Year 2035

The focus of this evaluation was to identify which of the improvements identified for 2050 MDD would be required by 2035. Modeling was performed for the 2035 MDD scenario for both sets of operational targets (40 – 100 psi and 45 – 90 psi). The baseline model for this scenario includes the following County-proposed projects:

The new Water Treatment Facility (WTF) with dual discharge headers, north and south

The Big Bend Pipeline

Development pipes in the southeastern portion of the system, as described in Section 2.2

The South County Potable Water Transmission Main

A small booster pump station (BPS) southeast of the Water Campus to serve future growth in the area of higher elevations along and south of County Road 672 (see Figure 16)

Controls for the pump stations (PSs) at the WTFs, the SCRS, and the SCBPS were adjusted to limit the daily average flow from the Water Campus to less than 50 MGD (see Section 2.2.2) while maintaining discharge pressures below the maximum pressure criterion for each operational target. For each scenario, considerable effort was made to adjust the PS controls to maintain pressures within the identified target range.

4.3.1 Operational Target 40 - 100 psi

Figure 16 shows the minimum and maximum pressures for the operational target of 40 - 100 psi without additional improvements. Areas of low pressure (less than 40 psi) are observed in the north and northeast parts of the system. Improvements to address these areas of low pressure could include the Williams Road Pipeline and Lithia North Pipeline discussed in Section 4.2.1. These improvements were not modeled for the 2035 MDD scenario, pending additional information regarding potential expansion of the Urban Service Area to the northeast, but are included as recommended improvements in Table 4 in Section 5. Based on model results, no additional improvements are needed in the south portion of the service area to meet the 40 – 100 psi operational target.

4.3.2 Operational Target 45 - 90 psi

Figure 17 shows the minimum and maximum pressures for operational target of 45 – 90 psi without additional improvements. Areas of low pressure (less than 45 psi) are observed in the south, central, north, and northeast parts of the system.

During the meeting on 5/30/2024 (Appendix D), results were compared for the Repump Pipeline and Ruskin Pipeline to improve pressures in the south. Both alternatives were able to address low pressures in the extreme southwest portion of the service area. Considerations for these pipeline alternatives are discussed in Section 4.2.

Even with the Repump Pipeline or Ruskin Pipeline, there are still wide-spread areas of pressures that fall outside of the 45 – 90 psi operational target. In order to meet the 45 – 90 psi target by 2035, the County would need to establish high and low pressure zones as discussed in Section 4.2.2. Table 4 in Section 5 provides a summary of improvements that would likely be required to meet the 45 – 90 psi target by 2035; however, these improvements have not yet been modeled for the 2035 MDD scenario. Additional modeling would be required to confirm the list of improvements, pending additional information regarding expansion of the Urban Service Area to the northeast.

BLACK & VEATCH | Hydraulic Modeling Scenarios and Results 23

Figure 16 Baseline Results for 2035 MDD, 40 – 100 psi

Figure 17 Baseline Results, 2035 MDD, 45 – 90 psi

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5.0 Conclusions and Recommendations

This TM summarizes hydraulic modeling evaluations for the Hillsborough County South-Central Potable Water System. Evaluations focused on three different demand scenarios (2025 MDD, 2050 MDD and 2035 MDD). The purpose of each evaluation, along with findings and recommendations, are summarized below.

2025 MDD Scenario:

o What improvements would be required to incorporate the Palm River service area into the South-Central Potable Water System?

Hydraulic evaluations identified three proposed interconnections to the Palm River service area to fully integrate this area into the South-Central Potable Water System (in addition to the four existing interconnections). These interconnections are listed in Table 4.

A PRV is required on the proposed 36-inch transmission pipeline in order to maintain pressures in the Palm River service area that are similar to existing pressures in the area as currently served by the City of Tampa.

2050 MDD Scenario:

o What improvements would be required by 2050 to meet the 40 – 100 psi operational target during an MDD condition?

Table 4 lists improvements required to meet the 40 – 100 psi operational target for the 2050 MDD. These improvements include major infrastructure projects:

The 19th Avenue Pipeline, modified to terminate near the intersection of 19th Avenue NE and Cypress Village Boulevard with a connection to the existing 30-inch pipeline on 19th Avenue NE.

Either the Repump or Ruskin Pipeline in the southern portion of the service area. Selection of this pipeline alternative depends on multiple factors, including potential expansion of the Urban Service Area to the south of the Little Manatee River and potential co-location with a pipeline improvement for the reclaimed water system.

Either the proposed Segment A POC or a pipeline improvement along Balm Riverview Road and McMullen Road

The Williams Road Pipeline in the northern portion of the service area

Either the Lithia North Pipeline or some combination of new pipelines and BPSs to deliver water to the northeast portion of the service area. Selection of these improvements would depend on potential expansion of the Urban Service Area along the I-4 corridor.

o What improvements would be required by 2050 to meet the 45 – 90 psi operational target during an MDD condition?

Table 4 lists improvements required to meet the 45 – 90 psi operational target for the 2050 MDD. These improvements include major infrastructure projects:

BLACK & VEATCH | 25

A low-pressure zone would need to be established in the Apollo Beach area to maintain pressures < 90 psi.

o Multiple large PRVs (~10) would be required to establish this low pressure zone.

o Additional small PRVs would be required in other areas to limit maximum pressures.

A high-pressure zone would need to be established in the north and northeast portions of the service area. Improvement alternatives for establishing this high-pressure zone are listed below. Note that not all of these alternatives have been modeled. Selection of improvements in this area should account for potential expansion of the Urban Service Area along the I-4 corridor.

o A large BPS (~35 MGD) in the Bloomingdale area o At least one large-diameter PRV, located on a 24-inch pipe near the intersection of S. King Avenue and W. Lumsden Road o Additional transmission pipelines and BPSs o A potential new POC with TBW near the Brandon BPS

The Williams Road Pipeline in the northern portion of the service area.

The 19th Avenue Pipeline, modified to terminate near the intersection of 19th Avenue NE and Cypress Village Boulevard with a connection to the existing 30-inch pipeline on 19th Avenue NE.

Either the Repump or Ruskin Pipeline in the southern portion of the service area. Selection of this pipeline alternative depends on multiple factors, including potential expansion of the Urban Service Area to the south of the Little Manatee River and potential co-location with a pipeline improvement for the reclaimed water system.

Either the proposed Segment A POC with TBW on the SHP Segment A or a pipeline improvement along Balm Riverview Road and McMullen Road.

2035 MDD Scenario:

o What improvements would be required by 2035 to meet the 40 – 100 psi operational target during an MDD condition?

No additional improvements would be required in the south portion of the service area.

Additional improvements would be required to meet minimum pressures in the north portion of the service area. These improvements could include the Williams Road Pipeline and the Lithia North Pipeline, or alternative improvements in the northeast portion of the service area. These improvements have not been modeled for the 2035 MDD and selection of these improvements should take into consideration potential expansion of the Urban Service Area along the I-4 corridor.

o What improvements would be required by 2035 to meet the 45 – 90 psi operational target during an MDD condition?

BLACK & VEATCH | 26

Pressure zones would need to be established in order to meet the 45 – 90 psi operational target for the 2035 MDD.

The improvements required to establish pressure zones and meet the minimum and maximum pressure criteria would be similar to the improvements identified for the 2050 MDD scenario.

Improvements to address low pressure areas in the north and northeast have not been modeled for the 2035 MDD scenario. Selection of improvements in this area should consider potential expansion of the Urban Service Area along the I-4 corridor.

Improvements discussed in this TM were identified based on planning-level evaluations. For each improvement, further evaluation would be required to finalize sizing and to evaluate the impact and performance for other operating conditions, including fire flow and water quality.

BV recommends updating the modeling results from this study once more information is available regarding potential future growth along the I-4 corridor and south of the Little Manatee River (Section 3.1). Growth in these areas could affect the improvements recommended in this report.

BLACK & VEATCH | 27

Table 4 Recommendations for future planning years

# Improvement Description

2025 MDD 2035 MDD 2050 MDD

IMPROVEMENT LOCATION AND DESCRIPTION

Operational Range

40 - 100 psi Operational Range

40 - 100 psi Operational Range

45 - 90 psi Operational Range

40 - 100 psi Operational Range

45 - 90 psi

1 Big Bend Pipeline County Project

Yes Yes Yes Yes Yes 36-inch pipe that connects 36-inch pipe at S US Highway 301 and 24-inch pipe at Big Bend Road.

2 South County Potable Water

Transmission Main County Project

Yes Yes Yes Yes Yes 42-inch and 48-inch pipe that connects 36-inch pipe at Big Bend Rd and 36-inch pipe at S Highway US 301.

3 Developer Pipe County Project

Yes Yes Yes Yes Yes 12-inch pipe that connects 48-inch pipe at County Road 672 and 12-inch pipe at Juniper Cove St.

4 19th Avenue Pipeline County Project

No No No Yes Yes 36-inch pipe that connects 48-inch pipe South County Potable Water Transmission Main at W Lake Dr and 24-inch pipe at Teco Rd.

5 Columbus Dr to US

Proposed Interconnect

Yes Yes Yes Yes Yes 36-inch pipe that connects 42-inch pipe at E Columbus Dr

6 Progress Blvd Proposed Interconnect

Yes Yes Yes Yes Yes 12-inch pipe that connects 16-inch pipe at Madison Ave

7 78th St and Flower Ave

Proposed Interconnect

Yes Yes Yes Yes Yes 16-inch pipe that connects 16-inch pipe at S 78th St Blvd

8 36-inch PRV Proposed PRV

Yes Yes Yes Yes Yes 36-inch PRV set to 75 psi which is present on the 36-inch proposed interconnect at Columbus Dr

9 Segment A POC ~15 mgd PS with storage & treatment

No No Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

~15 mgd PS with storage & treatment at the intersection of McMullen Rd and Boyette Rd.

10 Balm Riverview / McMullen Road

Pipeline

No No Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

Either Segment A POC or Balm

Riverview/McMullen Road Pipeline

30-inch (11,500 ft) and 24-inch (9,500 ft) pipe that connects 42-inch pipe at the intersection of Big Bend Rd and Balm Riverview Rd and 12-inch pipe at McMullen Rd and Boyette Rd.

11 Symmes Rd Pipeline

No No If Balm Riverview/McMullen

Road Pipeline selected

No If Balm Riverview/McMullen

Road Pipeline selected

16-in (9,500 ft) pipeline along Symmes Rd, would connect to the Balm Riverview Rd & McMullen Rd pipeline (above).

BLACK & VEATCH | 28

# Improvement Description

2025 MDD 2035 MDD 2050 MDD

IMPROVEMENT LOCATION AND DESCRIPTION

Operational Range

40 - 100 psi Operational Range

40 - 100 psi Operational Range

45 - 90 psi Operational Range

40 - 100 psi Operational Range

45 - 90 psi

12 Williams Rd Pipeline

No Yes Yes Yes Yes 16-inch (11,600 ft) and 12-inch (16,000 ft) pipeline that connects 42-inch pipe at Columbus Dr and 12- inch pipe at Joe Ebert Rd.

13 Lithia North Pipeline

-OR-

BPS(s)

No Yes Yes Yes Yes 24-inch (37,000 ft) pipe that connects 48-inch pipe at Lithia Pinecrest Rd and 8-inch pipe at Lacewing Pl.

Alternative could include new transmission mains coupled with one or more BPSs.

14 South Repump Pipeline

-OR-

Ruskin Pipeline

No No Yes Yes Yes South Repump Pipeline: 20-inch (17,700 ft) and 16-inch (13,500 ft) pipe that connects 30-inch pipe at SCRS and 16-inch pipe at 7th St SW.

Ruskin Pipeline: 20-inch (14,700 ft) pipe that connects from the 24-inch pipe on 19th Ave NE near N. U.S. Highway 41 to distribution piping near 1st Street SW and 21st Avenue SE.

15 Pradera Reserve Connector

No No Yes Yes Yes 12-inch (50 ft) pipe that connects 42-inch pipe at Balm Riverview Rd and 12-inch pipe at Ambleside Blvd.

16 W Lake Dr Connector

No No Yes Yes, without Segment

A POC

Yes 12-inch (30 ft) pipe that connects the 42-inch pipe at Big Bend Rd and 12-inch pipe at State Road 674.

17 Pipeline on 674 (at Wimauma)

No No Yes No Yes 12-inch (1,600 ft) pipe that connects 12-inch pipe at State Rd 674 and 8-inch pipe at Wimauma

18 Low Zone PRVs

No No Yes No Yes 10 larger-diameter PRVs to reduce pressure to the Apollo Beach area plus multiple smaller-diameter PRVs to reduce pressure to other low-lying areas.

High Zone BPS and

PRV(s)

No No Yes No Yes 35 mgd BPS + 24-inch PRV

20 Additional improvements required for high zone

No No Yes No Yes Additional BPSs and Transmission

BLACK & VEATCH | 29

Appendix A. 3/7/2024 Meeting Minutes and Slides

Meeting Minutes

Project Name: Project No: County PN:

Hillsborough County Hydraulic Modeling - Potable and Reclaimed Water System 417207

Subject: Meeting No:

Update Meeting 4

Location: Date: Time:

Teams Virtual Meeting 03/07/2024 1:00 PM to 2:00 PM

Recorded By:

Anusha Kadudula

Participants: Title: Organization:

John McCary Project Manager Hillsborough County Xiongfei Xie Hydraulic Engineer Hillsborough County Smith, Michael Staff Engineer Hillsborough County Amanda Schwerman Technical Lead BV Joel Kelsey Project Manager BV Bryan Young Lead Modeler BV Anusha Kadudula Planning Engineer BV Distribution:

All participants

Action Items:

No. Item Assigned To Status

1 BV will modify the symbology for change in pressure maps BV Included in this attachment

BV will model the 2050 scenario and provide the County with results during the update meeting scheduled for 03/28/2024.

BV

Both Hillsborough County and BV will let TBW know the County is investigating an additional POC.

HC/BV

Minutes:

Project Updates

BV presented an overview of the project work that has been completed so far, with the aim of maintaining an accurate record of the tasks that have been accomplished.

BV shared that the overall project budget through Friday, March 1 was 42% expended and that Task 300 was 55% expended. BV will provide an update in the slide deck for each progress meeting.

Model Updates BV added the South County Potable Water Transmission main and the new 12-inch pipe connecting County Road 672 and Balm River Road to the model. Additionally, BV reallocated the 2025 MDD demands.

Results for Scenarios from Feb 23rd Meeting BV presented the minimum pressures and change in minimum pressures for four different scenarios for 2025 MDD Demand Scenario.

Scenario 1 was considered as a base scenario with a PRV setting on the 36-inch interconnection at 75 psi:

o Both the existing and proposed interconnects were presented o BV stated that the Palm River pipes were imported into the Hillsborough model using

GIS Gateway and the service area was confirmed using Palm River valuation report provided by the County o The model is set so that the South County Repump Station valve only fills during off-peak hours to maximize Lithia South flow (valve is closed for 5-6 hours) o The Repump Station is simulated similarly to the existing mode of operation (fill from north, pump to south)

Scenario 2 involved closing the 14-inch diameter pipe along US 41 that crosses the Alafia River, while keeping the pipe open on US 301 that crosses the Alafia River to the east:

o This closure schema resulted in small decreases in minimum pressures in the Palm River area and small increases in minimum pressures in the southern part of the system

Scenario 3 involved closing the 14-inch diameter pipe along US 41 that crosses the Alafia River and a 16-inch pipe on Bloomingdale Avenue, while keeping the pipe open on US 301 that crosses the Alafia River to the east:

o This resulted in a further decrease in pressures in the southern part of the system, and that Lithia North was not able to support pressures the Palm River area o The maximum pressure drop for this scenario was 17 psi o County requested adding one more division to the change in pressure symbology to provide additional clarity o County mentioned that older pipes in the vicinity of the US 41 crossing could be replaced soon. County would like to evaluate the impact of decreasing the pipe diameter on system pressures and on circulation

Scenario 4 involved closing the 14-inch diameter pipe along US 41 that crosses the Alafia River and adding a proposed point of connection (POC) along the Tampa Bay Water (TBW) South Hillsborough Pipeline (SHP) project - Segment A.

o After viewing the results, the County agreed that the proposed location was a good spot for a new POC and would inform TBW about their desire to further evaluate the location for a new POC

Detailed, zoomed-in locations and connections for the existing and proposed interconnects in Palm River were included in the slide deck for Hillsborough County to review

County also mentioned that there is no clarity on who owns the 36-inch pipe along Columbus Dr. to US 301 at Central Hillsborough WTF, and that there might be a possibility reducing the pipe length of the proposed 36-inch connection from the WTF. County acknowledged that the location of this connection would not affect the hydraulics for 2050 scenario runs.

Next Steps BV will model the 2050 MDD Demand Scenario, incorporating both the existing and proposed interconnects as follows:

o The 14-inch diameter pipe at the US 41 / Alafia River crossing remains closed and both new water campus and Big Bend pipes are included o Identify projects with and without new POC to achieve operational targets o Evaluate the as-needed pipe along 19th Avenue o The first results will focus on operational targets of 40 psi minimum pressures and 100 psi maximum pressures An update meeting will be scheduled on 03/28/2024 to present the results to the County

Hillsborough South-Central Potable System Analysis

Update 4 03/07/2024

Agenda

• Project Updates

• Model Updates

• Results for Scenarios from February 23rd Meeting

• Palm River Interconnects

• Next Steps

Project Updates

Kickoff Meeting – 9/11/2023 Data Request

Update Meeting – 11/17/2023 Demand Projections

• Projected 2025 - 2050 Demands Model Updates

• Big Bend Project Pipes

• Palm River Pipes and Junctions with Existing

Interconnects

• South County Potable Water Transmission Main

Update Meeting – 02/09/2023 Model Update

• New Water Campus WTF

• Allocated Future Demands to Junctions

Existing System Review

• Reviewed Existing Model Controls

• Existing System Analysis

• Operational Target Evaluations

Update Meeting – 02/23/2023 Demands

• Established Maximum Day / Average Day Demand Multiplier

• Established Diurnal Pattern Model Evaluations

• Developed 2025 MDD Scenario

• Interconnect Evaluations for Palm River Area

• PRV Evaluations for Palm River Area

Update Meeting – 03/07/2023 Model Updates

• New 12-inch Pipe

• South County Potable Water Transmission Main

• Demand Re-allocation

Model Evaluations

• Potential Pipe Closures (Hwy 41 and

Bloomingdale Avenue)

• New Point of Connection near Balm River Road

Evaluation

© Black & Veatch Corporation, 2023. All Rights Reserved. The Black & Veatch name and logo are registered trademarks of Black & Veatch Corporation.

Updates

12”

42”

48”

42”

Model Updates

• Added 12-inch Pipe

• Added South County

Potable Water Transmission Main

• Re-allocated 2025 Demands (MDD Scenario)

© Black & Veatch Corporation, 2023. All Rights Reserved. The Black & Veatch name and logo are registered trademarks of Black & Veatch Corporation.

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