1-Exhibit 2.pdf

Port Royal Island WRF Improvements PER

Prepared for

Beaufort - Jasper Water & Sewer Author i ty

Okat ie, SC

August 8, 2025 ii

PRIWRF PER_Final

Table of Contents

List of Figures .............................................................................................................................................. iv

List of Tables ................................................................................................................................................ v

List of Abbreviations ................................................................................................................................... vii

Executive Summary ................................................................................................................................... viii

Key Findings and Recommendations ............................................................................................... viii

Cost and Schedule ............................................................................................................................... x

1. Project Background ...........................................................................................................................1-1

1.1 Purpose ...................................................................................................................................1-1

1.2 Facility Background ................................................................................................................1-1

1.3 Facility Evaluation ...................................................................................................................1-2

2. Process Areas and Alternatives Evaluation .....................................................................................2-1

2.1 Headworks Screens (Area 03) ...............................................................................................2-1

2.1.1 HW Screening Existing Conditions...........................................................................2-1

2.1.2 HW Screening Alternatives ......................................................................................2-2

2.1.3 Comparison of HW Screening Alternatives .............................................................2-7

2.1.4 HW Screening Recommendation ............................................................................2-8

2.2 Headworks Grit Removal (Area 03) .......................................................................................2-9

2.2.1 HW Grit Removal Existing Conditions ......................................................................2-9

2.2.2 HW Grit Removal Recommendations ................................................................... 2-10

2.3 Aeration Basins (Area 04) ................................................................................................... 2-11

2.3.1 Aeration Basins Existing Conditions ..................................................................... 2-11

2.3.2 Aeration Basins Recommendations ..................................................................... 2-12

2.4 Secondary Clarifiers (Area 05) ............................................................................................ 2-13

2.4.1 Secondary Clarifier Existing Conditions ............................................................... 2-13

2.4.2 Secondary Clarifier Recommendations ............................................................... 2-14

2.5 RAS/WAS Pump Station (Area 06) ..................................................................................... 2-15

2.5.1 RAS/WAS PS Existing Conditions ......................................................................... 2-15

2.5.2 RAS/WAS Pump Station Recommendations ....................................................... 2-16

2.6 Effluent Filters (Area 07 and 22) ........................................................................................ 2-16

2.6.1 Effluent Filters Existing Conditions ....................................................................... 2-16

2.6.2 Effluent Filters Recommendations ....................................................................... 2-17

2.7 Ultraviolet Disinfection (Area 08) ........................................................................................ 2-17

2.7.1 UV Disinfection Existing Conditions ...................................................................... 2-17

2.7.2 UV Disinfection Recommendations ...................................................................... 2-19

2.8 Utility Water (Area 10) ......................................................................................................... 2-19

2.8.1 Utility Water Existing Conditions ........................................................................... 2-19

BJWSA PRIWRF Improvements Table of Contents iii

2.8.2 Utility Water Recommendations ........................................................................... 2-21

2.9 Dewatering Building (Area 11) ............................................................................................ 2-21

2.9.1 Dewatering Building Existing Conditions ............................................................. 2-21

2.9.2 Dewatering Building Recommendations.............................................................. 2-22

2.10 Liquid Lime System (Area 12) ............................................................................................. 2-22

2.10.1 Liquid Lime System Existing Conditions .............................................................. 2-22

2.10.2 Liquid Lime System Recommendations .............................................................. 2-23

2.11 Process Drain Pump Station and Piping (Area 12) ............................................................ 2-24

2.11.1 Process Drain PS Existing Conditions .................................................................. 2-24

2.11.2 Process Drain PS Recommendations .................................................................. 2-24

2.12 Odor Control System (Area 13) ........................................................................................... 2-25

2.12.1 Odor Control System Existing Conditions ............................................................. 2-26

2.12.2 Odor Control System Recommendations ............................................................. 2-27

2.13 Control Building (Area 16) ................................................................................................... 2-29

2.13.1 Control Building Existing Conditions .................................................................... 2-29

2.13.2 Control Building Recommendations ..................................................................... 2-29

2.14 Electrical Building (Area 17) ................................................................................................ 2-29

2.14.1 Electrical Building Existing Conditions ................................................................. 2-29

2.14.2 Electrical Building Recommendations ................................................................. 2-29

2.15 Electrical Manholes (Area 18) ............................................................................................. 2-29

2.15.1 Electrical Manholes Existing Conditions .............................................................. 2-29

2.15.2 Electrical Manholes Recommendations .............................................................. 2-30

2.16 Equalization (EQ) Tank and Pump Station (Area 23) ......................................................... 2-30

2.16.1 EQ Tank and Pump Station Existing Conditions .................................................. 2-30

2.16.2 EQ Tank and Pump Station Recommendations .................................................. 2-31

2.17 Storage Building (Area 24) .................................................................................................. 2-31

2.17.1 Storage Building Location ..................................................................................... 2-31

2.17.2 Zoning and Code Compliance ............................................................................... 2-32

2.17.3 Site Plan ................................................................................................................. 2-32

2.17.4 Floor Plan ............................................................................................................... 2-33

2.17.5 Elevations and Materials ...................................................................................... 2-33

2.18 Overall Site (Area 00) .......................................................................................................... 2-34

2.18.1 Overall Site Existing Conditions ............................................................................ 2-34

2.18.2 Overall Site Recommendations ............................................................................ 2-34

3. Summary and Cost Estimate ............................................................................................................3-1

4. Permitting ..........................................................................................................................................4-1

5. Grouping of Projects and Schedule .................................................................................................5-1

6. Limitations .........................................................................................................................................6-1

Appendix A: Evaluation Review Meeting Notes, Scoring Table, and Presentation Slides .................... A-1 iv

Appendix B: Vulcan VMR Fixed-Chained Multirake VS Vulcan VKR Flex-Chained Knuckle-Link Screen

............................................................................................................................................................ B-1

Appendix C: Preliminary Opinion of Probable Construction Cost (POPCC) ............................................C-1

Appendix D: Process Drain PS Calculations ........................................................................................... D-1

Appendix E: Odor Control System Recommendations ............................................................................ E-1

Appendix F: Preliminary Architectural Rendering Drawings of Storage Building .................................. F-1

List of Figures

Figure 1-1. Site overview graphic. ............................................................................................................1-2

Figure 2-1. Existing headworks screening equipment. ...........................................................................2-1

Figure 2-2. Screening Alternative 1 – Replace with Multi-Rake Screens ..............................................2-3

Figure 2-3. Screening Alternative 2 – Add Upstream Coarse Screens + Conveyors ............................2-4

Figure 2-4. Screening Alternative 3 – Add Upstream Grinders + Conveyor ..........................................2-6

Figure 2-5. Screening Alternative 4 – Add Upstream Grinders + Conveyor ..........................................2-7

Figure 2-6. Existing headworks grit removal equipment, top plan. .......................................................2-9

Figure 2-7. Existing headworks grit removal equipment, lower plan. ................................................. 2-10

Figure 2-8. Surface aerator motors and gearboxes. ............................................................................ 2-12

Figure 2-9. Guardrail and delaminated concrete at aeration basins. ................................................ 2-13

Figure 2-10. Secondary Clarifier 1 ........................................................................................................ 2-14

Figure 2-11. Secondary clarifier area new access road route. ........................................................... 2-15

Figure 2-12. RAS/WAS pump station. .................................................................................................. 2-16

Figure 2-13. Gravel road near effluent filters. ..................................................................................... 2-17

Figure 2-14. Effluent flume downstream of UV disinfection channels. .............................................. 2-18

Figure 2-15. Settlement of concrete in UV area. ................................................................................. 2-19

Figure 2-16. Utility water piping corrosion............................................................................................ 2-20

Figure 2-17. Utility water hydropneumatic tank. .................................................................................. 2-20

Figure 2-18. Dewatering building BFP and polymer totes. .................................................................. 2-22

Figure 2-19. Liquid lime system tank and pumps. .............................................................................. 2-23

Figure 2-20. Civil utilities drawing markup for process drain pump station. ..................................... 2-25

Figure 2-21. Odor control pad and adjoining sidewalk coating and concrete deterioration ............. 2-26

Figure 2-22. Diagram of approximate locations for new 6-inch foul air pickups, new duct routing, and balanced airflow rates at the HW. .................................................................................................. 2-27

Figure 2-23. Diagram of approximate 18-inch foul air pickups, duct, and balanced airflow rates for the EQ tank. ..................................................................................................................................... 2-28 v

Figure 2-24. Plan view odor control system overall layout of single 6,000 cfm unit......................... 2-28

Figure 2-25. Electrical manhole site view and detail view. ................................................................. 2-30

Figure 2-26. Proposed storage building site location map. ................................................................ 2-32

Figure 2-27. Preliminary Storage Building Rendering– Option 1 ........................................................ 2-33

Figure 2-28. Preliminary Storage Building Rendering– Option 2 with Covered Porch ...................... 2-34

List of Tables

Table ES-1. High Priority Projects (Group 1) and Preliminary Opinion of Probable Construction Costs . x

Table ES-2. Medium Priority Projects (Group 2 – HW and EQ) and Preliminary Opinion of Probable

Construction Costs ................................................................................................................................ xi

Table ES-3. Medium Priority Projects (Group 3 – Buildings) and Preliminary Opinion of Probable

Construction Costs ............................................................................................................................... xii

Table ES-4. Medium Priority Projects (Group 4) and Preliminary Opinion of Probable Construction

Costs ..................................................................................................................................................... xiii

Table 2-1. Headworks Screening Existing Equipment ............................................................................2-2

Table 2-2. Headworks Screening Alternative 1 .......................................................................................2-3

Table 2-3. Headworks Screening Alternative 2 .......................................................................................2-5

Table 2-4. Headworks Screening Alternative 3 .......................................................................................2-6

Table 2-5. Screening Area Alternatives Cost Comparison ......................................................................2-7

Table 2-6. Scoring of Screening Alternatives, Non-Economic Factors ...................................................2-8

Table 2-7. Headworks Grit Removal Existing Equipment .................................................................... 2-10

Table 2-8. Headworks Grit Removal Equipment Costs ........................................................................ 2-11

Table 2-9. Secondary Clarifiers Existing Equipment ............................................................................ 2-13

Table 2-10. RAS/WAS Pump Station Existing Equipment ................................................................... 2-15

Table 2-11. UV Disinfection Existing Equipment – Channel 1 ............................................................ 2-18

Table 2-12. Utility Water Existing Equipment ....................................................................................... 2-21

Table 2-13. Liquid Lime System Existing Equipment .......................................................................... 2-23

Table 2-14. Process Drain Pump Station Existing Equipment ............................................................ 2-24

Table 2-15. Process Drain Pump Station Proposed Equipment ......................................................... 2-25

Table 3-1. Recommended Improvements and Preliminary Opinion of Probable Construction Costs .3-1

Table 4-1. Preliminary Permitting Matrix for PRIWRF Recommendations ............................................4-1

Table 5-1. High Priority Projects (Group 1) and Preliminary Opinion of Probable Construction Costs 5-1

Table 5-2. Medium Priority Projects (Group 2 – HW and EQ) and Preliminary Opinion of Probable

Construction Costs .............................................................................................................................5-2 vi

Table 5-3. Medium Priority Projects (Group 3 – Buildings) and Preliminary Opinion of Probable

Construction Costs .............................................................................................................................5-3

Table 5-4. Medium Priority Projects (Group 4) and Preliminary Opinion of Probable Construction

Costs ....................................................................................................................................................5-3 vii

List of Abbreviations

AB aeration basin

ACH air changes per hour

BC Brown and Caldwell

BFP Belt Filter Press

BJWSA Beaufort-Jasper Water and Sewer Authority

CCTV closed-circuit television

CIP capital improvement project cfm cubic feet per minute

CPE Comprehensive Performance Evaluation

EQ equalization

FRP Fiberglass Reinforced Plastic ft feet gpd gallons per day gpm gallons per minute hp horsepower

H2S hydrogen sulfide

HVAC heating, ventilation, and air conditioning

HW headworks

IBC International Building Code

In. w.c. inches water column

LOR local-off-remote

MCC Motor Control Center

MGD Million Gallons per Day

MSG Main Switchgear

ND Non-Discharge (Permit)

NPDES National Pollutant Discharge Elimination System

NPW non-potable water

OCU Odor and Control Unit

O&M operation and maintenance

PER Preliminary Engineering Report

POPCC Preliminary Opinion of Probable Construction Cost ppm parts per million

PRIWRF Port Royal Island Water Reclamation Facility

PS Pump Station psi pounds per square inch psig pounds per square inch gauge pressure

PW potable water

RAS return activated sludge

SC Secondary Clarifier

SCADA Supervisory Control and Data Acquisition sqft square foot / square feet

SWD Side Water Depth

TDH Total Dynamic Head

TSS total suspended solids

UV ultraviolet

VFD Variable Frequency Drive

WAS waste activated sludge

WRF Water Reclamation Facility viii

Executive Summary

This Preliminary Engineering Report (PER) discusses the improvements needed at the Port Royal

Island Water Reclamation Facility (PRIWRF) following an evaluation conducted by Brown and

Caldwell (BC) for the Beaufort-Jasper Water and Sewer Authority (BJWSA). The purpose of this PER is to present the feasibility, constructability, and prioritization of capital improvement projects necessary to ensure the facility’s long-term performance, regulatory compliance, and operational resilience.

PRIWRF, located in Beaufort County, South Carolina, was originally constructed in 2006 and expanded in 2007 to a permitted capacity of 7.5 million gallons per day (MGD), with provisions for future expansion to 10 MGD. The facility discharges treated effluent under both National Pollutant

Discharge Elimination System (NPDES) and Non-Discharge (ND) permits. Several capital projects had been previously identified to address aging infrastructure and operational challenges.

The PER includes an evaluation of existing infrastructure and identifies previously planned and newly recommended capital improvements across all major process areas. Conceptual design alternatives, and cost estimates are provided for each recommendation. A prioritization matrix and delivery method recommendations are also included to guide the implementation of the recommended improvements.

Key Findings and Recommendations

The evaluation identified critical needs and proposed improvements across the following areas:

Headworks Screens

• Replace the existing flexible-chained multirake screens with fixed-chained multirake screens or add a first stage of coarse screens making the existing screens the second stage.

• Add redundant screening conveyor(s).

• Remove rust and recoat salvageable parts or replace corroded carbon steel metal parts on headworks deck.

• Repair damage at standing seam roof at eave of the electrical enclosure (“bus stop”).

• Take hatches off and visually inspect coating in the headspace of the screen channels.

Headworks Grit Removal

• Replace aging vortex grit chamber mixer, drive, and motor.

• Add baffle to improve capture efficiency.

• Replace grit slurry pump and grit washer and classifier.

Aeration Basins

• Procure spare gearbox.

• Clean aeration basins and remove mixer with snapped cable.

• Replace moisture and temperature alarm panels with NEMA 4X panels (submersible mixers).

• Perform minor structural repairs.

Secondary Clarifiers (SC)

• Replace SC1 internal mechanism and perform repairs in SC2.

• Provide paved access road.

BJWSA PRIWRF Improvements Executive Summary ix

Return Activated Sludge (RAS)/Waste Activated Sludge (WAS) Pump Station

• Remove faulty total suspended solids (TSS) meter and upgrade moisture and temperature monitoring enclosures.

• Replace corroded WAS piping.

Effluent Filters

• Upgrade controls and pave dirt road.

Ultraviolet Disinfection

• Replace the existing ultraviolet (UV) disinfection equipment in Channel 1 with the same Trojan

UV3000Plus technology as planned for Channel 2.

• Add electric actuators to the influent gates.

• Upsize the effluent Parshall flume from 18 inches to 4 feet.

• Perform subgrade improvements around walkways.

Utility Water

• Replace undersized hydropneumatic tank and perform piping modifications.

Dewatering Building

• Refurbish the existing Belt Filter Press No. 2 and unclog process drains.

Liquid Lime System

• Clean and inspect the interior of the liquid lime tank, documenting any refurbishment needs.

• Add access handhole midway on the chemical feed pipeline.

Process Drain Pump Station and Piping

• Replace the existing pump station with a new larger pump station right next to it. Construct a new precast concrete wet well, install new submersible pumps, and install a new 8-inch force main from new wet well to existing discharge locations at the headworks.

• Remove all equipment from existing pump station and convert it to a plant drain manhole.

Odor Control System

• Perform odor sampling prior to detailed design to confirm basis of design.

• Replace existing system with a 6,000 cubic feet per minute (CFM) carbon adsorption unit for combined odor control of the headworks and EQ tank. Having two equally sized odor control units for redundancy whereas one is duty and the other standby is too costly and not a common practice.

• Add foul air pickups and modify ductwork to improve airflow from the headworks structure and equalization tank.

• Repair concrete around the existing odor control system.

Control Building

• Replace leaking roof.

Electrical Building

• Replace leaking roof and construct a new separate storage building.

Electrical Manholes

• Install a small grinder pump to pump out drainage in the appropriate manhole in the six groups of three to four electrical manholes.

x

Equalization (EQ) Tank and EQ Tank Pump Station

• Drain and clean the EQ tank for inspection.

• Replace roof panel of mixing system.

• Replace the EQ pumps and flowmeter in-kind.

• Paint piping and fix pipe supports.

Storage Building

• Construct a new storage building.

Overall Site

• Upgrade site lighting.

• Perform drainage improvements.

• Pave dirt roads and repave existing paved roads.

• Replace isolation gate valves on yard hydrants.

• Replace malfunctioning emergency eyewash and shower stations with new.

• Consideration should be given to supplying tepid water to these stations.

Cost and Schedule

The proposed projects are grouped together to create packages for design and construction.

Because of size (relatively small projects) and nature of the proposed improvements (rehabilitation or replacement) the project delivery method should be the traditional design-build-bid method. A

Class 5 planning-level cost estimate in 2025 dollars was developed for the identified improvements.

The total cost of all projects together is approximately $19.5 million. Groups of projects and their preliminary costs are summarized in tables ES-1 through ES-4.

The projects summarized in Table ES-1 are high priority and should be completed within the next 3 years under a single contract.

Table ES-1. High Priority Projects (Group 1) and Preliminary Opinion of Probable Construction Costs

Area # Description Cost

04 Aeration Basins $586,000

Procure and install spare gearbox. $502,000*

Support middle walkway aluminum grating. $20,000

Clean aeration basins and remove mixer with snapped cable. $25,000

Replace moisture and temperature alarm panels with NEMA 4X panels (submersible mixers). $34,000

Redo guardrail to include EJ or separate guardrail so it is not pulling on walkway. Repair walkway. $5,000

05 Secondary Clarifiers $2,428,000

Replace SC1 mechanism (incl. skimmer arms and scum box flushing). $2,156,000

Repair skimmer arms and scum box flushing in SC2. $60,000

Procure spare drive. $55,000

Construct access/maintenance road. $157,000

06 RAS/WAS Pump Station $38,000

Replace moisture and temperature alarm panels with NEMA 4X panels (submersible RAS and WAS pumps). $28,000 xi

Table ES-1. High Priority Projects (Group 1) and Preliminary Opinion of Probable Construction Costs

Area # Description Cost

Corroded pipe replacement allowance. $10,000

07, 22 Effluent Filters $263,000

Upgrade the controls. $214,000

Pave dirt road. $49,000

10 Utility Water $321,000

Upsize hydropneumatic tank system. $221,000

Simplify utility water piping and connect PW w/ air gap. $100,000

12 Process Drain PS and Piping $1,200,000

Construct new PS off to the side w/ larger pumps and wet well, turn existing wet well into a manhole. Upsize force main from 6" to 8". One-week bypass pumping @ 0.72 MGD. Connect old wet well with new w/ 16" pipe.

$1,155,000

Additive Alternate – Add VFDs. 45,000

00 Overall Site $442,000

Upgrade site lighting. $213,000

Drainage improvements allowance. $100,000

Road pavement and re-pavement allowance. $100,000

Replace isolation gate valves on yard hydrants. $29,000

Eyewash station replacement. In stock

Grand Total $5,278,000

*The spare gearbox for the aeration basins can be procured directly from BJWSA and stored. This will significantly reduce the cost of the overall project since this line item includes procurement and installation. The bare equipment cost for the gearbox is $179,000.

Tables ES-2, ES-3, and ES-4 include three groups of projects that are medium-to-low priority and could be completed within the next six years.

Table ES-2 includes grouped projects located in the general area of the headworks and EQ Tank.

Table ES-2. Medium Priority Projects (Group 2 – HW and EQ) and Preliminary Opinion of Probable Construction Costs

03 Headworks Screening $2,555,000

Alt 0: Add a redundant conveyor to existing screens. $567,000

Alt 1: Replace screens with fixed-chained multirake + redundant conveyor $2,510,000

Alt 2: Leave screens (will become second stage). Add coarse screens upstream + redundant conveyor. $3,208,000

Alt 3: Add grinders upstream + redundant conveyor $2,318,000

Alt 4: Add second stage screens downstream of existing screens + redundant conveyor Did not price

Replace corroded carbon steel metal parts. Remove rust and recoat salvageable parts. $10,000

Replace standing seam roof at electrical enclosure ("bus stop"). $35,000

03 Headworks Grit Removal $878,000

Replace vortex mixer and add baffle to improve efficiency. $495,000

Replace grit pump. $98,000

Replace grit washer and classifier. $285,000 xii

Table ES-2. Medium Priority Projects (Group 2 – HW and EQ) and Preliminary Opinion of Probable Construction Costs

Area # Description Cost

13 Odor Control System $1,588,000

Alt 1: Replace bioscrubber with one new 6,000 cfm activated carbon system (incl. new fan) $1,037,000

Alt 2: Replace bioscrubber with two new activated carbon systems (1,000 cfm plus 5,000 cfm, incl. new fans) $1,486,000

Demolish and remove existing OCU, including vessel, fan, ancillary equipment, 14" FRP duct to EQ tank and ~15ft 18" FRP duct at inlet.

$66,000

Miscellaneous Ductwork. $475,000

Refurbish and repair concrete. $10,000

23 EQ Tank and Pump Station $651,000

Replace roof panel of mixing system compressor canopy. $14,000

Drain and clean tank for inspection. $25,000

Paint piping and restore pipe support. 12,000

Alt 1: Replace EQ pumps and flowmeter. Upgrade panel. $600,000

Alt 2: Procure spare EQ pump. $65,000

Grand Total $5,672,000

Table ES-3 includes grouped projects that are building related and could be pursued by general contractors that do not necessarily specialize in wastewater treatment works.

Table ES-3. Medium Priority Projects (Group 3 – Buildings) and Preliminary Opinion of Probable Construction Costs

16 Control Building $99,000

Replace roof incl. insulation. $99,000

17 Electrical Building $95,000

Replace roof incl. insulation. $95,000

24 New Storage Building $4,281,000

Alt 1: Build new climate-controlled storage building. $4,281,000

Alt 2: Build new climate-controlled storage building. $5,446,000

Grand Total $4,475,000

Table ES-4 includes the remaining medium-to-low priority projects.

Table ES-4. Medium Priority Projects (Group 4) and Preliminary Opinion of Probable Construction Costs

08 Ultraviolet Disinfection $3,093,000

Replace the existing UV system. $2,857,000

Add electric actuators to the influent gates. $139,000

Upsize the Parshall flume (to 4 feet). $47,000 xiii

Table ES-4. Medium Priority Projects (Group 4) and Preliminary Opinion of Probable Construction Costs

Area # Description Cost

Subgrade improvements around walkway. $50,000

11 Dewatering Building $742,000

Refurbish existing BFP. $732,000

Unclog and vent building drains. $10,000

12 Liquid Lime System 15,000

Clean and inspect interior of tank. $10,000

Add handhole midway the hose and carrier pipe run. $5,000

18 Electrical Manholes (e.g. EMH-6) $203,000

New grinder pump for every group of 3-4 manholes as permanent sump pump. $203,000

Grand Total $4,053,000

1-1

Section 1

Project Background

This Preliminary Engineering Report (PER) summarizes the evaluation conducted by Brown and

Caldwell (BC) and provides recommendations for improvements at the Port Royal Island Water

Reclamation Facility (PRIWRF).

1.1 Purpose

The purpose of this PER is to assess the feasibility and constructability of previously identified capital improvement projects and to identify additional projects that may be necessary to support the facility’s long-term performance and regulatory compliance.

As part of this effort, the PER includes a review of existing facility data, infrastructure conditions, and operational performance. Based on this evaluation, all previously identified projects were confirmed as viable. In addition, new capital needs were identified.

This PER also includes the development of conceptual design alternatives, cost estimates, permitting considerations, and construction strategies for each recommended project. A prioritization matrix has been created to support the sequencing of project implementation based on criticality and costs.

The findings and recommendations presented in this PER are intended to guide the phased implementation of capital improvements at PRIWRF.

1.2 Facility Background

The PRIWRF is a regional wastewater treatment facility located in Beaufort County, South Carolina.

Originally constructed in 2006, the facility was designed with a permitted treatment capacity of

4.8 million gallons per day (MGD). A Phase 1 expansion was completed in 2007, increasing the facility’s permitted capacity to 7.5 MGD. The facility has been designed with future growth in mind, and a permit page for a 10 MGD capacity already exists. Expansion to this capacity is considered feasible with relatively minor modifications to the existing infrastructure.

PRIWRF is permitted to discharge treated effluent through two primary pathways:

• The Beaufort River, under a National Pollutant Discharge Elimination System (NPDES) permit.

• The Secession Golf Course, under a Non-Discharge (ND) Land Application Permit. The ND permit allows for seasonal discharge limits of 1.127 MGD during the summer months and 0.451 MGD during the winter.

Several capital improvement projects (CIPs) were previously identified to maintain and enhance the facility’s performance and reliability. These previously identified projects include:

• CIP-1938: PRIWRF Belt Filter Press No. 2 Rehabilitation

• CIP-1941: PRIWRF Equalization Tank Dome Liner

• CIP-2419: PRIWRF UV System Replacement

• CIP-2453: PRIWRF Plant Drain Pump Station

• CIP-2463: PRIWRF Clarifier Gear Box and Motor

• CIP-2466: PRIWRF Plant Storage Building

BJWSA PRIWRF Improvements Section 1

1-2

This PER confirms the need for these projects but as additional projects were identified herein, the criticality and prioritization of previously identified projects has been updated as part of this PER.

1.3 Facility Evaluation

Prior to this PER, BC performed a site visit on February 26, 2025 that included visual observations of the equipment and process areas at the PRIWRF. The methodology and results of this evaluation were presented in a workshop on April 14, 2025. Further information on the evaluation scoring results as well as the meeting slides from the workshop discussion are included in Appendix A. The area numbering used in Appendix A and in this PER is based on the numbering appearing on the facility’s instrumentation record drawings. Figure 1-1 shows the process areas on an aerial view of the plant.

Figure 1-1. Site overview graphic.

2-1

Section 2

Process Areas and Alternatives Evaluation

The following subsections summarize the recommended improvements to address limitations or deficiencies identified at the PRIWRF during the evaluation process.

2.1 Headworks Screens (Area 03)

The sections below summarize the issues identified with the headworks (HW) screening process and discuss recommendations for improvements.

2.1.1 HW Screening Existing Conditions

The existing screening equipment consists of two channels, each with a mechanical flex-chained multirake screen (knuckle-rake VKR-48 as manufactured by Vulcan Industries). Raw wastewater is pumped into a common influent channel that divides into two screen channels, each with an influent and effluent slide gate for isolation. The screenings are transported via a shaftless screw conveyor to a discharge chute and then to a dumpster. Though recently replaced, the existing screening equipment experiences problems with rag accumulation and requires excessive work from operations and maintenance (O&M) staff to keep it in working condition.

Figure 2-1 highlights the major equipment within the headworks screening process area, and

Table 2-1 provides the design criteria of this equipment.

Figure 2-1. Existing headworks screening equipment.

BJWSA PRIWRF Improvements Section 2

2-2

Table 2-1. Headworks Screening Existing Equipment

Parameter Design Value

Number of Screens 2

Type Flex chained multirake bar screen

Screen Motor Horsepower [hp] (each) 0.5 hp

Bar Spacing / Opening Size ¼-inch

Peak Hourly Flow, MGD (each) 18.75

Flow Channel Width, ft 4.0

Flow Channel Depth, ft 7.0

Screen Angle 70 degrees from horizontal

Number of Conveyors 1

Conveyor Motor Horsepower 2.0 hp

Total Installed Motor Horsepower 3.0 hp

In addition to the screening limitations, there have been concerns with hydrogen sulfide (H2S) corrosion in the headspace of the HW channels underneath the covers and with metals above the deck, including gate stems, bases of davit cranes, and other davit crane parts.

The headworks structure is built on piles, but the concrete sidewalks, pipe supports, and equipment pads in the surrounding area show signs of movement due to settlement.

Finally, the standing seam roof of the electrical enclosure (bus stop) has been damaged at the eave.

2.1.2 HW Screening Alternatives

There are four alternatives under consideration for this process area.

2.1.2.1 Alternative 0 –Baseline (Add Redundant Conveyor)

For all proposed alternatives, a redundant screenings conveyor should be installed to convey screenings discharged by the screens into the existing discharge chute. Some additional modifications to the discharge chute of the existing screens will be required to accommodate a redundant screening conveyor, but this would be defined in more detail once an alternative is selected for detailed design. The budgetary equipment cost for one redundant screening conveyor is

$182,000.

In this baseline alternative, no other improvements would be made to the headworks screening system. Doing nothing to the mechanical screens will result in continued O&M issues since rags will continue to accumulate and overload the screens. This is the primary drawback of the baseline alternative.

In the draft PER meeting, the topic of changing the existing screen angle was discussed. The screen manufacturer has indicated that changing the screen angle within the recommended range for the equipment will have little to no impact on the quantity of screenings removed, and thus changing the angle is not expected to provide any benefit. Therefore, it is not recommended to change the screen angle except as discussed in some alternatives below where additional space in the channels is needed.

2-3

2.1.2.2 Alternative 1 –Multi-Rake Screens + Conveyor

In Screening Alternative 1, both existing flex-chained multirake screens would be replaced with fixed-chained multi-rake screens like the screens installed at the Cherry Point WRF. This type of screen is expected to better handle the rags and trash received at the HW. Fixed-chained multirake screens have superior rigidity and durability compared to the existing flex-chained multirake screens and would require less housekeeping from O&M staff as compared to the existing equipment. Appendix B is a document prepared by the screen manufacturer that compares the existing flex-chained

(knuckle-rack) multirake screen with a fixed-chained multirake screen. The differential head loss across a multi-rake screen is comparable with the head loss across the existing screens. A sketch of

Alternative 1 is provided in Figure 2-2.

Figure 2-2. Screening Alternative 1 – Replace with Multi-Rake Screens

Preliminary design criteria and a budgetary equipment cost for these new multi-rake screens and conveyors are provided in Table 2-2.

Table 2-2. Headworks Screening Alternative 1

Parameter Design Value

Number of Screens 2

Type Multi-Rake Bar Screens

Bar Spacing / Opening Size ¼-inch

Peak Hourly Flow, MGD (each) 18.75

Flow Channel Width, ft 4.0

Flow Channel Depth, ft 7.0

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Table 2-2. Headworks Screening Alternative 1

Parameter Design Value

Screen Angle 80 degrees from horizontal

Screen Motor Horsepower (each) 2.0 hp

Number of Screenings Conveyors 2 (1 existing, 1 new)

Conveyor Motor Horsepower (each) 2.0 hp

Total Installed Motor Horsepower 8.0 hp

Budgetary Equipment Cost $781,000

2.1.2.3 Alternative 2 –Two Stages of Screens + Conveyors

In Screening Alternative 2, an additional coarse screen would be installed in each channel upstream of the existing screens, making the existing flex-chained multirake screens the second stage of screening. The exact location to install this first-stage coarse screen would be refined during detailed design if this alternative is selected. The angle of the existing screens may need to be altered to a more upright degree to accommodate space for these upstream coarse screens. Additionally, the isolation gates, upstream and downstream, may need to be slightly moved to create more space in between them. A sketch of Alternative 2 is provided in Figure 2-3.

Figure 2-3. Screening Alternative 2 – Add Upstream Coarse Screens + Conveyors

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Preliminary design criteria for these new coarse screens and conveyors are provided in Table 2-3.

Table 2-3. Headworks Screening Alternative 2

Number of Screens (total) 4

Number of Coarse Screens 2

Type (new screens only) Multi-Rake Bar Screens

Bar Spacing / Opening Size (new screens only) ¾-inch

Peak Hourly Flow, MGD (each) 18.75

Flow Channel Width, ft 4.0

Flow Channel Depth, ft 7.0

Screen Angle (new screens only) 80 degrees from horizontal

Screen Motor Horsepower (each) 2.0 hp

Number of Screenings Conveyors 4 (1 existing, 3 new)

Conveyor Motor Horsepower (each) 2.0 hp

Total Installed Motor Horsepower 13.0 hp

Budgetary Equipment Cost $936,000

This alternative may require more extensive modifications to the screening discharge chute to accommodate a secondary set of screenings conveyors. There would also be more differential head loss accumulated across two sets of screens per channel as compared to the existing conditions.

2.1.2.4 Alternative 3 –Upstream Grinders + Conveyor

In Screening Alternative 3, in-line grinder units would be installed upstream of the existing screens to macerate the rags and other debris that currently cause issues at the screens. Sewage grinders such as these are commonly installed in pump stations serving institutional facilities that produce high amounts of rags and other debris. A sketch of Alternative 3 is provided in Figure 2-4, with preliminary design criteria presented in Table 2-4.

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Figure 2-4. Screening Alternative 3 – Add Upstream Grinders + Conveyor

Table 2-4. Headworks Screening Alternative 3

Number of Grinders (New) 2

Grinder Type ½-inch perforated drum

Head loss across Grinder (each channel) 20 – 40 inches

Grinder Motor Horsepower (each) 10 hp cutter + (2) 1 hp drums

Number of Screenings Conveyors 2

Conveyor Horsepower (each) 2.0 hp

Total Installed Motor Horsepower 29.0 hp

Budgetary Equipment Cost $729,000

While the grinders would be effective at shredding rags and other trash, they would also induce significantly more head loss than the existing screens or multi-rake screens, especially at high flow rates. In the PRIWRF HW, water level is controlled by the hydraulic jump at the Parshall flume downstream of the grit removal unit. When high flows occur, an overflow weir upstream of the screen channels allows for partial bypass of unscreened flow into the common effluent channel towards the aeration basins. With the added head loss of the grinder units, flow would be bypassed over this weir more frequently. If this alternative is selected, additional considerations should be given to hydraulics and the frequency this bypass would occur.

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2.1.2.5 Alternative 4 – Two Stages of Screens (Alternate Location) + Conveyors

In Screening Alternative 4, a second stage of screens would be installed at a different location than

Alternative 2; downstream of grit removal and upstream of the influent Parshall flume. This alternative, as shown in Figure 2-5 with a single screen as a second stage screen, is less reliable than Alternative 2 that includes two screens for each stage. This alternative may require a secondary dumpster location for screenings disposal and could be equipped with a passive bypass as shown in

Figure 2-5. Because of its lower reliability, this alternative has not been priced nor is it compared with the rest of the alternatives.

Figure 2-5. Screening Alternative 4 – Add Upstream Grinders + Conveyor

2.1.3 Comparison of HW Screening Alternatives

A Preliminary Opinion of Probable Construction Cost (POPCC) was developed for each alternative and is included in Appendix C. Based on this information, the capital costs for each alternative are presented for economic comparison in Table 2-5.

Table 2-5. Screening Area Alternatives Cost Comparison

Alternative 0 – Baseline

(Add Conveyor)

1 – Multi-

Rake Screens

+ Conveyor

2 – Two Stages of Screens +

Conveyors

3 – Upstream

Grinders +

Conveyor

Connected Power, HP 5 8 13 29

Equipment Costs, $ 182,000 781,000 936,000 729,000

Capital Costs, $ 567,000 2,510,000 3,208,000 2,318,000

In terms of O&M costs, some differences exist in the connected power, but all alternatives are comparable overall. Adding grinders will add 12 HP of connected load per grinder whereas a new conveyor and a new screen will add 2 and 2 HP of connected load each.

The alternatives were also compared using non-economic factors. A scoring system was developed where each alternative receives a score between 1 and 5 for various metrics, where “1” means the alternative does a poor job of satisfying the criterion and “5” means the alternative completely

2-8 satisfies the criterion. The highest total score represents the most favorable alternative. Scoring of the alternatives is presented in Table 2-6.

Table 2-6. Scoring of Screening Alternatives, Non-Economic Factors

Alternative

0 – Baseline

(Add

Conveyor)

1 – Multi-Rake

Screens +

Conveyor

2 – Two Stages of Screens +

Conveyors

3 – Upstream

Grinders +

Conveyor

Meets Project Objectives 1 4 5 3

Constructability 4 3 2 2

Ability to Operate and Maintain 4 4 3 3

Reliability 2 4 4 2

Total 11 15 14 10

2.1.4 HW Screening Recommendation

Based on cost and non-cost factors, the recommended alternative is Alternative 1 – Multi-Rake

Screens + Conveyor. Replacing the existing flex-chained multirake screens with new fixed-chained multirake screens would provide improved performance. The new screens would not affect the hydraulic grade line of the headworks since the headloss of the new screens would be similar to the headloss of the existing screens.

Alternative 2 – Two Stages of Screens + Conveyors is the second preferred alternative as it would provide the highest amount of trash removal from the wastewater flow. This alternative is the costliest alternative of all and installing one more set of screens may increase the overall headloss of the process. An initial review of the channels’ length suggests that there is sufficient space to install a second set of screens in the existing channels, assuming that the existing and new screens will be installed at the greater allowable angle by the manufacturers (most upright).

Alternative 0 – Baseline (Add Conveyor) only addresses screening conveyance issues by improving the reliability of that process but does nothing to address issues with the screens.

Alternative 3 – Upstream Grinders + Conveyor is the least preferred alternative, since the addition of the grinders will help reduce the size of the trash for the existing screens to more easily remove but would significantly increase the overall headloss of the process. At wet weather conditions (higher flows), there may be significant bypass occurring around the screening process.

Other recommendations for improvements in this area include the following:

• A more detailed field evaluation is necessary to assess the extent of corrosion inside the HW channels before a recommendation can be determined. Such an evaluation will require removing hatches so the channels can be inspected visually.

• Metal components in this area should be scoured of rust and recoated where possible. If excessive corrosion of the component has occurred, that component should be replaced with a stainless-steel equivalent if available.

• The roof of the electrical enclosure should be replaced.

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2.2 Headworks Grit Removal (Area 03)

The sections below summarize the issues identified with the HW grit removal process and discuss recommendations for improvements.

2.2.1 HW Grit Removal Existing Conditions

The existing grit removal equipment consists of a Smith & Loveless Pista-grit apparatus, a Heyward-

Gordon grit slurry pump, and a Wemco washer-compactor unit. This equipment was installed in 2006 and is nearing the end of its useful life.

The existing grit removal equipment consists of one 18-feet diameter vortex grit removal chamber where the flow rotates 270 degrees. The influent flow is then measured in a Parshall flume before flowing by gravity to the aeration bioreactors. BJWSA staff have witnessed the Parshall flume getting submerged on occasion, so staff have been using the equalization (EQ) piping to reduce the level downstream of the flume to keep it free flowing. A grit slurry pump on the lower level of the HW

Building removes the grit-containing underflow from the vortex grit removal chamber and pumps it to a grit classifier which washes and dewaters the grit solids prior to disposal. Figure 2-6 and Figure 2-7 highlight major features of the existing grit removal equipment, and Table 2-7 lists the design criteria of this existing equipment.

Figure 2-6. Existing headworks grit removal equipment, top plan.

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Figure 2-7. Existing headworks grit removal equipment, lower plan.

Table 2-7. Headworks Grit Removal Existing Equipment

Number of Grit Chambers 1

Grit Chambers type Vortex concentrator

Grit Chamber Motor Horsepower 0.5 hp

Size (ft diameter) 18

Grit Pump Flow Rate (gpm) 220

Head (ft) 24

Grit Pump Motor Horsepower 15.0 hp

Grit Washer/Classifier type Inclined screw

Classifier size (in) 12

Classifier Motor Horsepower 0.5 hp

2.2.2 HW Grit Removal Recommendations

The recommendations for improvements in this area are as follows:

• Replace in-kind the grit chamber mechanism/motor and internals. Given the occasion, install baffle inside grit chamber to improve flow conditions for more optimal grit removal.

− The addition of the baffle will prevent short-circuiting, allowing for full 360-degree rotation through the…