FINAL

INVESTIGATORY

REPORT

CONSTRUCT WASTEWATER

TREATMENT FACILITY AT THE

MEMORIAL UNIT IN ROSHARON,

TEXAS

MWR #00722020

January 27, 2026

TEXAS BOARD OF PROFESSIONAL

ENGINEERS FIRM REGISTRATION F-754

7 NOV2627 January 2026

Attachment E - Master Plan

696-FD-26-Q035

Investigatory Report TDCJ Memorial Unit Construct Wastewater Treatment Facility, Rosharon, Texas

MWR #00722020

I

This page is intentionally left blank

MWR #00722020

Revision 1, noted on Page 2 of the enclosed report, was prepared under the direction of Joel R.

Cantwell, Texas P.E. No. 86209. The remainder of the report was prepared under the direction of Todd C. Warrix, Texas P.E. No. 106812.

II

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY

2 FLOW AND LOADINGS

2.1 INTRODUCTION

2.2 EXISTING FLOW AND LOADS

2.2.1 PROBABILITY ANALYSIS

2.2.2 EXPECTED FLOW AND POTENTIAL INFLOW AND INFILTRATION (I/I)

2.3 FUTURE FLOW AND LOADS

2.3.1 RECOMMENDATIONS

2.3.1.1 FLOWS

2.3.1.2 LOADS

2.3.1.3 ADDITIONAL FLOW METERING

3 WASTEWATER TREATMENT PLANT (WWTP) CONDITION ASSESSMENT ..16

3.1 INTRODUCTION

3.2 HEADWORKS ASSESSMENT

3.3 AERATION BASINS ASSESSMENT

3.4 AEROBIC DIGESTERS ASSESSMENT

3.5 CLARIFIER ASSESSMENT

3.6 CHLORINATION SYSTEM/ CHLORINE CONTACT BASIN ASSESSMENT

3.7 SOLIDS HANDLING AND PROCESSING

3.8 ELECTRICAL SERVICE

4 TCEQ GUIDANCE FOR FUTURE EFFLUENT DISCHARGE LIMIT

4.1 INTRODUCTION

4.2 TCEQ GUIDANCE

4.3 RECOMMENDATION / CONCLUSIONS

5 UNIT TREATMENT PROCESS DEVELOPMENT

5.1 INTRODUCTION

5.2 UNIT TREATMENT PROCESS EQUIPMENT

5.2.1 COARSE SCREENING

5.2.2 CLIMBER BAR SCREEN

5.2.3 FINE SCREENING

5.2.4 INFLUENT PUMP STATION

III

5.2.5 AERATION BASIN

5.2.6 SECONDARY CLARIFIER

5.2.7 TERTIARY FILTRATION

5.2.8 DISINFECTION

5.2.9 SLUDGE STORAGE

5.2.10 DEWATERING

5.2.11 NON-POTABLE WATER

6 CIVIL SITE WORK RATIONALE

6.1 INTRODUCTION

6.2 PURPOSE

6.3 SITE SELECTION

6.4 SITE CHARACTERISTICS

6.5 ACCESS AND PAVEMENT

6.6 DRAINAGE

6.7 UTILITIES

6.8 SURFACE RESTORATION

6.9 CONCLUSIONS

7 OPERATIONS BUILDING SPACE PLANNING AND DESIGN RATIONALE

7.1 INTRODUCTION

7.1.1 CONTROL ROOM (ESTIMATED: 12’ X 20’, 240 SQ. FT.)

7.1.2 CHLORINE ROOM (ESTIMATED: 12’ X 12’, 144 SQ. FT.)

7.1.3 MECHANICAL ROOM (ESTIMATED: 6’ X 12’, 72 SQ. FT.)

7.1.4 ELECTRICAL ROOM (ESTIMATED: 12’ X 36’, 432 SQ. FT.)

7.1.5 RESTROOM (ESTIMATED: 8’ X 8’, 64 SQ. FT.)

7.1.6 OTHER SPACES

7.2 BUILDING STRUCTURE

7.3 BUILDING MECHANICAL SYSTEMS

7.4 COST ESTIMATE

8 GEOTECH INVESTIGATION

8.1 INTRODUCTION

8.2 PUBLICLY AVAILABLE GEOTECHNICAL INFORMATION REVIEWED

8.3 SITE DESCRIPTION

8.4 SOIL SURVEY

IV

8.5 SITE GEOLOGY

8.6 INFORMATION FROM TEXAS WATER DEVELOPMENT BOARD

8.7 SUMMARY OF ANTICIPATED SUBSURFACE CONDITIONS

(EXPANSIVE SOIL) ....................... ……………………. 73

8.8 DEPTH-TO-WATER CONSIDERATIONS

8.9 ACTIVE SURFACE GEOLOGIC FAULTS

8.10 SUBSIDENCE

8.11 POTENTIAL STRUCTURE TYPES

8.12 ANTICIPATED FOUNDATION TYPES

8.13 FUTURE GEOTECHNICAL STUDIES

8.14 LIMITATIONS

9 ENVIRONMENTAL CONSTRAINTS AND PERMITTING ANALYSIS

9.1 SUMMARY

9.2 PROJECT DESCRIPTION

9.3 DESKTOP ANALYSIS

9.4 EXISTING SITE CONDITIONS

9.5 WATER RESOURCES

9.5.1 POTENTIAL AQUATIC FEATURES

9.5.2 FLOODPLAINS

9.5.3 WATER QUALITY

9.6 PROTECTED SPECIES

9.6.1 FEDERAL AND STATE LISTED SPECIES

9.6.2 THE MIGRATORY BIRD TREATY ACT

9.6.3 THE BALD AND GOLDEN EAGLE PROTECTION ACT

9.7 CULTURAL RESOURCES

9.8 ENVIRONMENTAL/CULTURAL REGULATORY PERMITTING ANALYSIS

9.8.1 LOCAL PERMITTING REQUIREMENTS

9.8.2 STATE PERMITTING REQUIREMENTS

9.8.3 FEDERAL PERMITTING REQUIREMENTS

9.9 LIMITATIONS

9.10 REFERENCES

10 OPINIONS OF PROBABLE CONSTRUCTION COST (OPCC)

10.1 INTRODUCTION

V

APPENDIX-A FLOW AND LOAD DISCUSSION MEETING MINUTES 10/1/2025

APPENDIX-B UNIT TREATMENT PROCESS ALTERNATIVES MEETING MINUTES AND

SLIDES

APPENDIX-C FIGURES-GEOTECHNICAL INVESTIGATION

APPENDIX-D ENVIRONMENTAL FIGURES

APPENDIX-E FLOOD INSURANCE RATE MAP

APPENDIX-F USFWS IPAC RESOURCE LIST

APPENDIX-G TPWD ANNOTATED COUNTY LIST OF RARE, THREATENED, AND

ENDANGERED SPECIES FOR BRAZORIA COUNTY

APPENDIX-H ENVIRONMENTAL PERMITTING TABLE

APPENDIX-I ENVIRONMENTAL AND CULTURAL RESOURCE REFERENCE

APPENDIX-J PRELIMINARY WASTEWATER TREATMENT PLANT SITE LAYOUT

VI

LIST OF TABLES

TABLE 1 EXISTING INFLUENT FLOW, LOAD AND PEAKING FACTOR (PF)

TABLE 2 MAXIMUM MONTH AND MAXIMUM DAY TO AVERAGE FLOW AND LOAD

PEAKING FACTORS

TABLE 3 FUTURE INFLUENT FLOW, LOAD AND PEAKING FACTOR

TABLE 4 EXISTING CONDITIONS AND RECOMMENDATION FOR THE

HEADWORKS AREA

TABLE 5 EXISTING CONDITIONS AND RECOMMENDATION FOR THE AERATION

BASINS

TABLE 6 EXISTING CONDITIONS AND RECOMMENDATION FOR THE AEROBIC

DIGESTERS

TABLE 7 EXISTING CONDITIONS AND RECOMMENDATION FOR THE CLARIFIER

TABLE 8 EXISTING CONDITIONS AND RECOMMENDATION FOR THE

CHLORINATION SYSTEM/BASIN

TABLE 9 EXISTING CONDITIONS AND RECOMMENDATION FOR THE SLUDGE

DEWATERING BOX

TABLE 10 EXISTING CONDITIONS AND RECOMMENDATION FOR THE SLUDGE

DEWATERING BOX

TABLE 11 DESIGN CRITERIA FOR COARSE SCREENING

TABLE 12 DESIGN CRITERIA FOR FINE SCREENING

TABLE 13 SYSTEM HEAD CURVE INPUT PARAMETERS AND RESULTS

TABLE 14 AERATION BASIN DESIGN CRITERIA

TABLE 15 SECONDARY CLARIFIER DESIGN CRITERIA

TABLE 16 DESIGN CRITERIA FOR TERTIARY DISK CLOTH MEDIA FILTER

TABLE 17 CHLORINE GAS DISINFECTION DESIGN CRITERIA

TABLE 18 SULFUR DIOXIDE DECHLORINATION DESIGN CRITERIA

TABLE 19 150 LB. AND 1-TON CHLORINE CYLINDER COMPARISON

TABLE 20 PRELIMINARY DESIGN CRITERIA FOR SLUDGE STORAGE TANK (SST)

TABLE 21 TCEQ REQUIREMENTS FOR SLUDGE DEWATERING

TABLE 22 SLUDGE PRODUCTION RATE FOR DEWATERING

TABLE 23 COMPARISON OF BELT FILTER PRESS AND SCREW PRESS

DEWATERING UNIT

TABLE 24 CAPITAL COSTS FOR THE DEWATERING UNITS

TABLE 25 SOIL TYPES WITHIN THE PROJECT AREA

TABLE 26 FEDERAL AND STATE-LISTED THREATENED AND ENDANGERED

SPECIES

TABLE 27 ENR CONSTRUCTION COST INDEX BASE

TABLE 28 CONSTRUCTION ADDITIONS AND CONTINGENCY MULTIPLIERS

TABLE 29 SUMMARY OF CLASS 4 OPCC FOR MEMORIAL WWTP

TABLE 30 ITEMIZED SUMMARY OF UNIT PROCESS FOR MEMORIAL WWTP

VII

LIST OF FIGURES

FIGURE 1 PROCESS FLOW DIAGRAM FOR NEW MEMORIAL UNIT WWTP

FIGURE 2 FLOW AT TDCJ MEMORIAL WWTP BETWEEN AUG 2024 - JULY 2025

FIGURE 3 BOD5 AND TSS CONCENTRATION AUG 2024 - JULY 2025

FIGURE 4 BOD5 AND TSS LOADS AUG 2024 - JULY 2025

FIGURE 5 AMMONIA-NITROGEN CONCENTRATION AUG 2024 - JULY 2025

FIGURE 6 AMMONIA-NITROGEN LOADS AUG 2024 - JULY 2025

FIGURE 7 EXISTING AA FLOW COMPARED TO EXPECTED AA FLOW

FIGURE 8 EXISTING WATER PRODUCTION AND WASTEWATER GENERATION

FLOWRATE AT TDCJ MEMORIAL UNIT

FIGURE 9 HEADWORKS SUCTION LIFT PUMP MISSING BELT DRIVE GUARDS

FIGURE 10 CORROSION OF THE PUMP DISCHARGE AND BYPASS PIPING

FIGURE 11 VISIBLE DISCOLORATION ON THE INFLUENT WET-WELL WALL

FIGURE 12 CRACK ON THE CONCRETE SLAB BENEATH THE SUCTION LIFT

PUMP

FIGURE 13 EXISTING PUMPING EQUIPMENT SUPPORT STRUCTURE

FIGURE 14 EXISTING HEADWORKS BUILDING

FIGURE 15 HEADWORK PUMP ELECTRICAL CONTROL PANEL

FIGURE 16 FOAMING IN THE AERATION BASINS. SOME “BOILS” INDICATING

ISSUE WITH DIFFUSERS

FIGURE 17 DAMAGE TO THE CONCRETE SURFACE INSIDE THE AERATION

BASIN

FIGURE 18 ELECTRICAL BOX PANEL FOR THE WWTP. CONCERNS OF SAFETY

AND ADHERENCE WITH ELECTRICAL CODES

FIGURE 19 ELECTRICAL BOX PANEL FOR THE WWTP. CONCERNS OF SAFETY

AND ADHERENCE WITH ELECTRICAL CODES

FIGURE 20 NORTHERN AEROBIC DIGESTER BASINS RECEIVING SCUM FROM

THE CLARIFIER

FIGURE 21 CONCRETE SURFACE CORROSION INSIDE THE AERATION BASIN

(SOUTH)

FIGURE 22 HANDRAIL SUPPORT STRUCTURE FOR THE AEROBIC DIGESTER

BASIN

FIGURE 23 RUST DEVELOPED AROUND THE MOTOR HEADER

FIGURE 24 CLARIFIER RAKE MECHANISM

FIGURE 25 CLARIFIER ELECTRICAL CONTROL PANEL

FIGURE 26 EXISTING CHLORINE GAS CYLINDER STORAGE STRUCTURE

FIGURE 27 EXISTING CHLORINE GAS FEED SYSTEM

FIGURE 28 CHLORINE GAS FEED SYSTEM BUILDING, DAMAGE SEEN TO THE

ROOF AND WALLS

FIGURE 29 CONCRETE CRACK NEAR THE CHLORINE CONTACT BASIN

VIII

FIGURE 30 ELECTRICAL SOCKET AND CONDUITS SEVERELY DAMAGED INSIDE

CHLORINE FEED SYSTEM BUILDING

FIGURE 31 EXISTING SLUDGE DEWATERING BOX

FIGURE 32 CLIMBER-TYPE BAR SCREEN

FIGURE 33 PERFORATED PLATE FINE SCREEN

FIGURE 34 INFLUENT PUMP SYSTEM HEAD CURVES

FIGURE 35 FINE BUBBLE CERAMIC DISC DIFFUSER

FIGURE 36 MULTI-STAGE CENTRIFUGAL BLOWER

FIGURE 37 SECTIONAL VIEW OF A SECONDARY CLARIFIER

FIGURE 38 CLOTH MEDIA DISK FILTER

FIGURE 39 FIBERGLASS EMERGENCY GAS SCRUBBER FOR 1-TON Cl2

CYLINDERS

FIGURE 40 FIBERGLASS EMERGENCY GAS SCRUBBER FOR 150 LB. Cl2

CYLINDERS

FIGURE 41 DUCKBILL-TYPE COARSE BUBBLE DIFFUSER

FIGURE 42 BELT FILTER PRESS FOR DEWATERING

FIGURE 43 SCREW PRESS FOR DEWATERING

FIGURE 44 PROPOSED SITE ALTERNATIVES FOR MEMORIAL WWTP EXPANSION

IX

1 EXECUTIVE SUMMARY

FINAL

INVESTIGATORY

REPORT

CONSTRUCT WASTEWATER

TREATMENT FACILITY AT THE

MEMORIAL UNIT IN ROSHARON,

TEXAS

January 26, 2026

TEXAS BOARD OF PROFESSIONAL

ENGINEERS FIRM REGISTRATION F-754

II

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY

2 FLOW AND LOADINGS

2.1 INTRODUCTION

2.2 EXISTING FLOW AND LOADS

2.2.1 PROBABILITY ANALYSIS

2.2.2 EXPECTED FLOW AND POTENTIAL INFLOW AND INFILTRATION (I/I)

2.3 FUTURE FLOW AND LOADS

2.3.1 RECOMMENDATIONS

2.3.1.1 FLOWS

2.3.1.2 LOADS

2.3.1.3 ADDITIONAL FLOW METERING

3 WASTEWATER TREATMENT PLANT (WWTP) CONDITION ASSESSMENT ..16

3.1 INTRODUCTION

3.2 HEADWORKS ASSESSMENT

3.3 AERATION BASINS ASSESSMENT

3.4 AEROBIC DIGESTERS ASSESSMENT

3.5 CLARIFIER ASSESSMENT

3.6 CHLORINATION SYSTEM/ CHLORINE CONTACT BASIN ASSESSMENT

3.7 SOLIDS HANDLING AND PROCESSING

3.8 ELECTRICAL SERVICE

4 TCEQ GUIDANCE FOR FUTURE EFFLUENT DISCHARGE LIMIT

4.1 INTRODUCTION

4.2 TCEQ GUIDANCE

4.3 RECOMMENDATION / CONCLUSIONS

5 UNIT TREATMENT PROCESS DEVELOPMENT

5.1 INTRODUCTION

5.2 UNIT TREATMENT PROCESS EQUIPMENT

5.2.1 COARSE SCREENING

5.2.2 CLIMBER BAR SCREEN

5.2.3 FINE SCREENING

5.2.4 INFLUENT PUMP STATION

III

5.2.5 AERATION BASIN

5.2.6 SECONDARY CLARIFIER

5.2.7 TERTIARY FILTRATION

5.2.8 DISINFECTION

5.2.9 SLUDGE STORAGE

5.2.10 DEWATERING

5.2.11 NON-POTABLE WATER

6 CIVIL SITE WORK RATIONALE

6.1 INTRODUCTION

6.2 PURPOSE

6.3 SITE SELECTION

6.4 SITE CHARACTERISTICS

6.5 ACCESS AND PAVEMENT

6.6 DRAINAGE

6.7 UTILITIES

6.8 SURFACE RESTORATION

6.9 CONCLUSIONS

7 OPERATIONS BUILDING SPACE PLANNING AND DESIGN RATIONALE

7.1 INTRODUCTION

7.1.1 CONTROL ROOM (ESTIMATED: 12’ X 20’, 240 SQ. FT.)

7.1.2 CHLORINE ROOM (ESTIMATED: 12’ X 12’, 144 SQ. FT.)

7.1.3 MECHANICAL ROOM (ESTIMATED: 6’ X 12’, 72 SQ. FT.)

7.1.4 ELECTRICAL ROOM (ESTIMATED: 12’ X 36’, 432 SQ. FT.)

7.1.5 RESTROOM (ESTIMATED: 8’ X 8’, 64 SQ. FT.)

7.1.6 OTHER SPACES

7.2 BUILDING STRUCTURE

7.3 BUILDING MECHANICAL SYSTEMS

7.4 COST ESTIMATE

8 GEOTECH INVESTIGATION

8.1 INTRODUCTION

8.2 PUBLICLY AVAILABLE GEOTECHNICAL INFORMATION REVIEWED

8.3 SITE DESCRIPTION

8.4 SOIL SURVEY

IV

8.5 SITE GEOLOGY

8.6 INFORMATION FROM TEXAS WATER DEVELOPMENT BOARD

8.7 SUMMARY OF ANTICIPATED SUBSURFACE CONDITIONS

(EXPANSIVE SOIL) ....................... ……………………. 73

8.8 DEPTH-TO-WATER CONSIDERATIONS

8.9 ACTIVE SURFACE GEOLOGIC FAULTS

8.10 SUBSIDENCE

8.11 POTENTIAL STRUCTURE TYPES

8.12 ANTICIPATED FOUNDATION TYPES

8.13 FUTURE GEOTECHNICAL STUDIES

8.14 LIMITATIONS

9 ENVIRONMENTAL CONSTRAINTS AND PERMITTING ANALYSIS

9.1 SUMMARY

9.2 PROJECT DESCRIPTION

9.3 DESKTOP ANALYSIS

9.4 EXISTING SITE CONDITIONS

9.5 WATER RESOURCES

9.5.1 POTENTIAL AQUATIC FEATURES

9.5.2 FLOODPLAINS

9.5.3 WATER QUALITY

9.6 PROTECTED SPECIES

9.6.1 FEDERAL AND STATE LISTED SPECIES

9.6.2 THE MIGRATORY BIRD TREATY ACT

9.6.3 THE BALD AND GOLDEN EAGLE PROTECTION ACT

9.7 CULTURAL RESOURCES

9.8 ENVIRONMENTAL/CULTURAL REGULATORY PERMITTING ANALYSIS

9.8.1 LOCAL PERMITTING REQUIREMENTS

9.8.2 STATE PERMITTING REQUIREMENTS

9.8.3 FEDERAL PERMITTING REQUIREMENTS

9.9 LIMITATIONS

9.10 REFERENCES

10 OPINIONS OF PROBABLE CONSTRUCTION COST (OPCC)

10.1 INTRODUCTION

V

APPENDIX-A FLOW AND LOAD DISCUSSION MEETING MINUTES 10/1/2025

APPENDIX-B UNIT TREATMENT PROCESS ALTERNATIVES MEETING MINUTES AND

SLIDES

APPENDIX-C FIGURES-GEOTECHNICAL INVESTIGATION

APPENDIX-D ENVIRONMENTAL FIGURES

APPENDIX-E FLOOD INSURANCE RATE MAP

APPENDIX-F USFWS IPAC RESOURCE LIST

APPENDIX-G TPWD ANNOTATED COUNTY LIST OF RARE, THREATENED, AND

ENDANGERED SPECIES FOR BRAZORIA COUNTY

APPENDIX-H ENVIRONMENTAL PERMITTING TABLE

APPENDIX-I ENVIRONMENTAL AND CULTURAL RESOURCE REFERENCE

APPENDIX-J PRELIMINARY WASTEWATER TREATMENT PLANT SITE LAYOUT

VI

LIST OF TABLES

TABLE 1 EXISTING INFLUENT FLOW, LOAD AND PEAKING FACTOR (PF)

TABLE 2 MAXIMUM MONTH AND MAXIMUM DAY TO AVERAGE FLOW AND LOAD

PEAKING FACTORS

TABLE 3 FUTURE INFLUENT FLOW, LOAD AND PEAKING FACTOR

TABLE 4 EXISTING CONDITIONS AND RECOMMENDATION FOR THE

HEADWORKS AREA

TABLE 5 EXISTING CONDITIONS AND RECOMMENDATION FOR THE AERATION

BASINS

TABLE 6 EXISTING CONDITIONS AND RECOMMENDATION FOR THE AEROBIC

DIGESTERS

TABLE 7 EXISTING CONDITIONS AND RECOMMENDATION FOR THE CLARIFIER

TABLE 8 EXISTING CONDITIONS AND RECOMMENDATION FOR THE

CHLORINATION SYSTEM/BASIN

TABLE 9 EXISTING CONDITIONS AND RECOMMENDATION FOR THE SLUDGE

DEWATERING BOX

TABLE 10 EXISTING CONDITIONS AND RECOMMENDATION FOR THE SLUDGE

DEWATERING BOX

TABLE 11 DESIGN CRITERIA FOR COARSE SCREENING

TABLE 12 DESIGN CRITERIA FOR FINE SCREENING

TABLE 13 SYSTEM HEAD CURVE INPUT PARAMETERS AND RESULTS

TABLE 14 AERATION BASIN DESIGN CRITERIA

TABLE 15 SECONDARY CLARIFIER DESIGN CRITERIA

TABLE 16 DESIGN CRITERIA FOR TERTIARY DISK CLOTH MEDIA FILTER

TABLE 17 CHLORINE GAS DISINFECTION DESIGN CRITERIA

TABLE 18 SULFUR DIOXIDE DECHLORINATION DESIGN CRITERIA

TABLE 19 150 LB. AND 1-TON CHLORINE CYLINDER COMPARISON

TABLE 20 PRELIMINARY DESIGN CRITERIA FOR SLUDGE STORAGE TANK (SST)

TABLE 21 TCEQ REQUIREMENTS FOR SLUDGE DEWATERING

TABLE 22 SLUDGE PRODUCTION RATE FOR DEWATERING

TABLE 23 COMPARISON OF BELT FILTER PRESS AND SCREW PRESS

DEWATERING UNIT

TABLE 24 CAPITAL COSTS FOR THE DEWATERING UNITS

TABLE 25 SOIL TYPES WITHIN THE PROJECT AREA

TABLE 26 FEDERAL AND STATE-LISTED THREATENED AND ENDANGERED

SPECIES

TABLE 27 ENR CONSTRUCTION COST INDEX BASE

TABLE 28 CONSTRUCTION ADDITIONS AND CONTINGENCY MULTIPLIERS

TABLE 29 SUMMARY OF CLASS 4 OPCC FOR MEMORIAL WWTP

TABLE 30 ITEMIZED SUMMARY OF UNIT PROCESS FOR MEMORIAL WWTP

VII

LIST OF FIGURES

FIGURE 1 PROCESS FLOW DIAGRAM FOR NEW MEMORIAL UNIT WWTP

FIGURE 2 FLOW AT TDCJ MEMORIAL WWTP BETWEEN AUG 2024 - JULY 2025

FIGURE 3 BOD5 AND TSS CONCENTRATION AUG 2024 - JULY 2025

FIGURE 4 BOD5 AND TSS LOADS AUG 2024 - JULY 2025

FIGURE 5 AMMONIA-NITROGEN CONCENTRATION AUG 2024 - JULY 2025

FIGURE 6 AMMONIA-NITROGEN LOADS AUG 2024 - JULY 2025

FIGURE 7 EXISTING AA FLOW COMPARED TO EXPECTED AA FLOW

FIGURE 8 EXISTING WATER PRODUCTION AND WASTEWATER GENERATION

FLOWRATE AT TDCJ MEMORIAL UNIT

FIGURE 9 HEADWORKS SUCTION LIFT PUMP MISSING BELT DRIVE GUARDS

FIGURE 10 CORROSION OF THE PUMP DISCHARGE AND BYPASS PIPING

FIGURE 11 VISIBLE DISCOLORATION ON THE INFLUENT WET-WELL WALL

FIGURE 12 CRACK ON THE CONCRETE SLAB BENEATH THE SUCTION LIFT

PUMP

FIGURE 13 EXISTING PUMPING EQUIPMENT SUPPORT STRUCTURE

FIGURE 14 EXISTING HEADWORKS BUILDING

FIGURE 15 HEADWORK PUMP ELECTRICAL CONTROL PANEL

FIGURE 16 FOAMING IN THE AERATION BASINS. SOME “BOILS” INDICATING

ISSUE WITH DIFFUSERS

FIGURE 17 DAMAGE TO THE CONCRETE SURFACE INSIDE THE AERATION

BASIN

FIGURE 18 ELECTRICAL BOX PANEL FOR THE WWTP. CONCERNS OF SAFETY

AND ADHERENCE WITH ELECTRICAL CODES

FIGURE 19 ELECTRICAL BOX PANEL FOR THE WWTP. CONCERNS OF SAFETY

AND ADHERENCE WITH ELECTRICAL CODES

FIGURE 20 NORTHERN AEROBIC DIGESTER BASINS RECEIVING SCUM FROM

THE CLARIFIER

FIGURE 21 CONCRETE SURFACE CORROSION INSIDE THE AERATION BASIN

(SOUTH)

FIGURE 22 HANDRAIL SUPPORT STRUCTURE FOR THE AEROBIC DIGESTER

BASIN

FIGURE 23 RUST DEVELOPED AROUND THE MOTOR HEADER

FIGURE 24 CLARIFIER RAKE MECHANISM

FIGURE 25 CLARIFIER ELECTRICAL CONTROL PANEL

FIGURE 26 EXISTING CHLORINE GAS CYLINDER STORAGE STRUCTURE

FIGURE 27 EXISTING CHLORINE GAS FEED SYSTEM

FIGURE 28 CHLORINE GAS FEED SYSTEM BUILDING, DAMAGE SEEN TO THE

ROOF AND WALLS

FIGURE 29 CONCRETE CRACK NEAR THE CHLORINE CONTACT BASIN

VIII

FIGURE 30 ELECTRICAL SOCKET AND CONDUITS SEVERELY DAMAGED INSIDE

CHLORINE FEED SYSTEM BUILDING

FIGURE 31 EXISTING SLUDGE DEWATERING BOX

FIGURE 32 CLIMBER-TYPE BAR SCREEN

FIGURE 33 PERFORATED PLATE FINE SCREEN

FIGURE 34 INFLUENT PUMP SYSTEM HEAD CURVES

FIGURE 35 FINE BUBBLE CERAMIC DISC DIFFUSER

FIGURE 36 MULTI-STAGE CENTRIFUGAL BLOWER

FIGURE 37 SECTIONAL VIEW OF A SECONDARY CLARIFIER

FIGURE 38 CLOTH MEDIA DISK FILTER

FIGURE 39 FIBERGLASS EMERGENCY GAS SCRUBBER FOR 1-TON Cl2

CYLINDERS

FIGURE 40 FIBERGLASS EMERGENCY GAS SCRUBBER FOR 150 LB. Cl2

CYLINDERS

FIGURE 41 DUCKBILL-TYPE COARSE BUBBLE DIFFUSER

FIGURE 42 BELT FILTER PRESS FOR DEWATERING

FIGURE 43 SCREW PRESS FOR DEWATERING

FIGURE 44 PROPOSED SITE ALTERNATIVES FOR MEMORIAL WWTP EXPANSION

IX

1 EXECUTIVE SUMMARY

HDR contracted with the Texas Department of Criminal Justice (TDCJ) on August 2025 to provide investigatory services and report for the planned expansion of the existing 0.8 million-gallon-per-day

(MGD) wastewater treatment plant (WWTP) serving the Memorial Unit (Unit) located in Rosharon, Texas. The expansion is necessary to accommodate TDCJ’s planned addition of approximately 400 beds at the Memorial Unit and an additional 100 beds for the Texas Juvenile Justice Department’s

(TJJD) new facility on an adjacent site, along with related support infrastructure. The study assesses the existing WWTP’s capacity, condition, and regulatory requirements, and to develop a preliminary basis for design and cost estimation to develop a facility which is able to treat the future wastewater flows at the Unit WWTP. HDR initially investigated two strategies to develop a WWTP with sufficient capacity to treat the future wastewater flows. First strategy (Strategy 1) was to design the rehabilitation of the existing treatment process Units and expand the existing Unit WWTP. The second strategy (Strategy 2) included the design of a new WWTP to replace the existing WWTP completely.

Among the two options, Strategy 2 has been selected for this project1.

As part of this investigatory study, HDR confirmed projected future flows and loads by analyzing current and historical WWTP operating data in conjunction with existing and future population estimates provided by TDCJ. The existing average annual daily flow (AADF) was determined to be

0.7 MGD and the future AADF was determined to be 1.6 MGD based on the historical data and expected population growth. Further, the wastewater collection system coming into the Unit WWTP was identified to have a high inflow & infiltration (I/I) issue, with I/I flow approximately 47 percent of the existing AADF, details provided in the Section 2 Flow and Loadings.

The study also includes a brief assessment of existing WWTP Unit processes based on a site walkthrough conducted jointly with TCEQ representatives and plant operators to evaluate equipment condition and recommend necessary rehabilitation or replacement. Most of the existing WWTP Unit processes are old and difficult to rehabilitate and expand for the future 1.6 MGD AADF. Therefore, due to the aged condition of the existing Unit WWTP and the challenges during its expansion to meet the future flow capacity, Strategy 1 was determined to be unfeasible and was ruled out by

TDCJ from further evaluation. The details of the condition assessment of the existing WWTP are provided in the Section 3 Wastewater Treatment Plant (WWTP) – Condition Assessment.

HDR coordinated with the Texas Commission on Environmental Quality (TCEQ) to identify preliminary future effluent discharge limits applicable to the expanded WWTP. TCEQ informed that the receiving waterbody (Oyster Creek) is impaired for dissolved oxygen (DO). This impairment will likely restrict the future loading (e.g., pounds per day) into Oyster Creek to current permitted load limits; thus, the future effluent concentrations will be halved from the existing effluent concentrations.

Therefore, the expected effluent concentrations are cBOD- 3.5 mg/l, TSS- 7.5 mg/l and NH3-N- 1 mg/l. Further details are provided in the Section 4 TCEQ Guidance for Future Effluent Discharge

Limit.

1 Revision 1

HDR used the expected limits for the preliminary design of the treatment process alternatives. The new Unit WWTP will be an activated sludge treatment system with nitrification. The new WWTP will have a tertiary filter to treat the effluent to meet the effluent limit, and a sludge holding tank and dewatering Unit to process sludge. A process flow diagram of the future WWTP is illustrated in

Figure 1 below.

HDR presented Unit treatment process configuration options for both liquid and solid streams for the new WWTP to TDCJ in a workshop, and evaluated their technical viability, regulatory compliance, risk factors, and relative costs. Based on this presentation, TDCJ selected preferred Unit treatment processes, with HDR’s concurrence, to be included in the new WWTP. The details regarding the selected Unit treatment process systems are presented in Section 5 Unit Treatment Process

Development.

HDR prepared a preliminary site plan including all the treatment process basins, equipment and operational and administrative building (see Appendix-J). The new WWTP was proposed on the vacant site located southeast of the existing WWTP. The rationale for the site selection and sizing of the administrative and operational building structures is discussed in Section 6 Civil

Site Work Rationale and Section 7 Operational Building Space Planning and Design

Rationale.

Figure 1 Process Flow Diagram for New Memorial Unit WWTP

HDR conducted a desktop study including a review of available geotechnical and geological information to assess potential subsurface conditions affecting design, and an environmental and permitting review to identify potential regulatory constraints, including Waters of the U.S.

and U.S. Army Corps of Engineers (USACE) permitting, endangered species considerations, and cultural resource impacts. Findings from both reviews are summarized in the following sections: Section 8 Geotech Investigation and Section 9 Environmental Constraints and

Permitting Analysis.

Finally, HDR prepared an Opinion of Probable Construction Cost (OPCC) consistent with an AACE

Class 4 cost estimate to provide a preliminary construction cost for the new WWTP construction.

The Class 4 OPCC is approximately $40,000,000 but could range from $32,000,000 to $56,000,000

(i.e., -20% to +40% variance per Class 4 OPCC). Further details regarding OPCC development process are summarized in Section 10 Opinion of Probable Construction Cost (OPCC).

2 FLOW AND LOADINGS

2.1 INTRODUCTION

The Memorial Unit wastewater treatment plant (WWTP) treats the wastewater flow generated from the Memorial facility under jurisdiction of the Texas Department of Criminal Justice (TDCJ). The

Memorial Unit WWTP is currently permitted by TCEQ to treat an annual average daily flow (AADF) of 0.8 MGD with a two hour peak (P2H) flow of 1,666 gallons per minute (GPM), or 2.4 MGD. TDCJ is expanding the Memorial facility to include an additional 400 beds for TDCJ and another approximately 100 beds for Texas Juvenile Justice Department (TJJD), which will increase the future wastewater flow to the WWTP.

TDCJ hired HDR in August 2025 to perform an investigatory study for the existing WWTP and determine the existing and future wastewater flows, loadings and the peaking factors (PFs) and provide recommendations for expansion of the WWTP capacity. The existing wastewater flows, loads and PFs were then used to determine the future flows and loadings at WWTP based on the expected population growth.

This study provides summary of the results from the analysis of the existing flow and loads data, as provided by TDCJ, for the Memorial Unit WWTP. The results from this analysis will be used as a basis of design to develop preliminary treatment processes for the future condition.

2.2 EXISTING FLOW AND LOADS

HDR analyzed the weekly flow and load data for the existing wastewater treatment plant (WWTP) provided by TDCJ for the period between August 2024 until July 2025. TDCJ provided the total suspended solids (TSS), 5-day biochemical oxygen demand (BOD5) and ammonia nitrogen (NH3-N) as the influent constituent data.

TDCJ also provided the weekly average effluent flow data for the period between August 2024 until

July 2025. Memorial Unit WWTP does not have a flowmeter at the influent. A flowmeter is installed at the effluent channel near the chlorine contact basin. The flow data recorded by this flowmeter was used as the WWTP influent flow data. However, by measuring only the effluent flow, influent peak flows will be attenuated by the existing basins of the WWTP and may not fully reflect influent peak flows. Further, TCEQ recommends analyzing five years of daily historical plant data to determine the existing average, monthly, peak flow and load values along with the peaking factors. However, in the absence of a comprehensive influent dataset, HDR performed the analysis on the limited dataset provided.

The flow and loadings data are presented in the following figures:

• Figure 2- Weekly average effluent flow

• Figure 3- Weekly BOD5 and TSS concentration, mg/l

• Figure 4- Weekly BOD5 and TSS loadings, lbs./ day

• Figure 5- Weekly ammonia nitrogen concentration, mg/l

• Figure 6- Weekly ammonia nitrogen loadings, lbs./day

Figure 2 illustrates the average weekly effluent flow at the Memorial Unit WWTP from the period of

8/1/2024 and 7/31/2025.

The historical flow data from Figure 2 shows the average flow is approximately 0.6 - 0.7 million gallons per day (MGD). As seen in Figure 2, during the week of 6/5/2025 and 6/13/2025 the flowrate is approximately 0.1 MGD, which is significantly lower than the average. HDR consulted with the

Memorial Unit WWTP operations staff regarding the recorded low flow conditions observed during the weeks of 6/5/2025 and 6/13/2025 to discuss the potential causes. According to staff, the flowmeter is calibrated, so a potential error from flowmeter calibration was ruled out. However, the operators were uncertain about other reasons for the reduced flow relative to the average. To avoid these two weeks of outliers, skewing the data analysis, the flow datapoints from the week of

6/5/2025 and 6/13/2025 were omitted from the analysis.

Figure 2 Flow at TDCJ Memorial WWTP between Aug 2024 - July 2025.

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Date

TDCJ Memorial WWTP Effluent Flow

Figure 3 illustrates the average weekly influent BOD5 and TSS concentration (mg/l) at the Memorial

Unit WWTP from the period of 8/1/2024 and 7/31/2025.

Figure 4 illustrates the average weekly influent BOD5 and TSS loading (lbs. per day) at the Memorial

Unit WWTP from the period of 8/1/2024 and 7/31/2025.

Figure 3 BOD5 and TSS Concentration Aug 2024 - July 2025.

Figure 4 BOD5 and TSS Loads Aug 2024 - July 2025.

7/27/2024 9/15/2024 11/4/2024 12/24/2024 2/12/2025 4/3/2025 5/23/2025 7/12/2025

C o n c e n tr a ti o n m g /l

Date

Influent BOD Influent TSS

7/27/2024 9/15/2024 11/4/2024 12/24/2024 2/12/2025 4/3/2025 5/23/2025 7/12/2025

L o a d lb s p e r d a y

Date

Influent BOD Load Influent TSS Load

The average influent BOD5 and TSS concentrations are below 100 mg/l as seen in Figure 3, which is low compared to expected domestic wastewater constituents from Metcalf & Eddy wastewater engineering textbook(2) and TCEQ planning recommendations. However, the high TSS concentration of 420 mg/l during the week of 6/13/2025 was likely due to recycling of sludge from the digester to the headworks during maintenance activities on the aerobic digesters. Therefore, the outlier TSS datapoints from the week of 6/5/2025 and 6/13/2025 were omitted from the analysis.

Figure 5 illustrates the average weekly influent ammonia nitrogen (NH3-N) concentration (mg/l) at the Memorial Unit WWTP from the period of 8/1/2024 and 7/31/2025.

The average influent NH3-N concentrations illustrated in Figure 5 are under 15 mg/l which is below the expected NH3-N concentration for domestic wastewater. A localized spike was recorded in late

December 2024, coinciding with the aforementioned digester cleaning. This spike was omitted from the analysis

2 Reference: Metcalf & Eddy Inc., Tchobanoglous, G., Burton, F. L., Tsuchihashi, R., & Stensel, H. D. (2013). Wastewater engineering: Treatment and resource recovery (5th ed.). McGraw-Hill Professional.

Figure 5 Ammonia-Nitrogen Concentration Aug 2024 - July 2025.

7/27/2024 9/15/2024 11/4/2024 12/24/2024 2/12/2025 4/3/2025 5/23/2025 7/12/2025

C o n c e n tr a ti o n m g /l

Date

Influent Ammonia Nitrogen

Figure 6 illustrates the average weekly influent ammonia nitrogen (NH3-N) loading (lbs. per day) at the Memorial Unit WWTP from the period of 8/1/2024 and 7/31/2025

2.2.1 PROBABILITY ANALYSIS

HDR performed a statistical probability analysis on the available historical data to determine the annual average (AA), maximum month (MM), and maximum day (MD) values for influent flow rate, BOD5, TSS, and ammonia-nitrogen, loadings. These values are summarized in Table 1 and will be used as the basis of design for expanding the WWTP treatment process.

• Annual Average values represent a 50th percentile non-exceedance probability of occurrence (% = 1 - 6/12).

• Maximum Month values represent a 92nd percentile non-exceedance probability of occurrence (% = 1 - 1/12). Maximum Month conditions were developed to assist in evaluating the impact of peaking conditions on the system.

• Maximum Day values represent a 99.7th percentile non-exceedance probability of occurrence (% = 1 - 1/365).

The BOD5, TSS, and ammonia-nitrogen influent loads were based on mass loading values, and corresponding concentrations were calculated based on the flow rates for average, maximum month, and maximum day.

Figure 6 Ammonia-Nitrogen Loads Aug 2024 - July 2025.

7/27/2024 9/15/2024 11/4/2024 12/24/2024 2/12/2025 4/3/2025 5/23/2025 7/12/2025

L o a d lb s p e r d a y

Date

Influent Ammonia-Nitrogen Load

Table 1 Existing Influent Flow, Load and Peaking Factor (PF).

Table 2 summarizes the typical peaking factors from HDR’s historical WWTP project dataset (1) and

WEF Design of Water Resource Recovery Facilities, MOP 8, 7th Edition, Table 2.9 (2). The Water

Environment Federation’s (WEF) Manual of Practice No. 8 (MOP 8) is the principle technical reference guide utilized by wastewater engineers which provides industry-standard guidance for the planning, design, operation, and maintenance of wastewater treatment facilities. The peaking factors for the Memorial Unit WWTP (summarized in Table 1) determined were then compared with the peaking factors from Table 2.

Table 2 Maximum Month and Maximum Day to Average Flow and Load Peaking Factors

Parameter Maximum Month to Annual Average (MM/AA)

Maximum Day to Annual Average

(MD/AA)

HDR WWTP Data 3 WEF MOP 8 4 HDR WWTP Data 1 WEF MOP 8 2

Flow (MGD) - 1.3 - 1.45 - 1.4 - 2.6

BOD5 (mg/l) 1.1 - 1.4 1.3 - 1.45 1.2 - 1.7 1.52 - 2.86

TSS (mg/l) 1.1 - 1.6 1.3 - 1.53 1.2 - 2.2 1.64 - 3.86

NH3-N (mg/l) 1.1 - 1.4 1.21 - 1.3 1.2 - 1.7 1.32 - 2.09

The existing MM/AA and MD/AA peaking factors for the flow are within the MOP 8 standard peaking factor range. However, the existing MM/AA and MD/AA peaking factors for BOD5 and NH3-N are higher compared to the standard range from Table 2. The existing TSS MM/AA peaking factor is higher than the standard ranges from Table 2, but the MD/AA is within the allowable range by

MOP 8.

Although the existing MM/AA and MD/AA peaking factor for the Memorial Unit WWTP summarized in Table 1 are based on the provided dataset, HDR recommends using these peaking factors for the preliminary design since peaking factors are within or above the standard peaking factor ranges.

HDR recommends TDCJ to record daily influent data, if feasible, to develop a more extensive dataset for the design of the WWTP expansion.

1 Based on historical HDR projects.

2 The Water Environment Federation (WEF). 2018. Design of Water Resource Recovery Facilities. 6th ed. McGraw-Hill Education:

New York, Chicago, San Francisco, Athens, London, Madrid, Mexico City, Milan, New Delhi, Singapore, Sydney, Toronto.

https://www.accessengineeringlibrary.com/content/book/9781260031188.

Parameter Unit Average Annual

(AA)

Maximum Month

(MM)

Maximum Week

(MW)

Maximum Day (MD)

MM/AA

PF

MW/AA

PF

MD/AA

PF

Flow MGD 0.70 0.85 0.93 1.03 1.21 1.33 1.47

BOD5 mg/l 72.53 111.37 148.12 198.42 1.85 2.71 4.02

TSS mg/l 99.15 143.06 181.45 231.31 1.74 2.43 3.43

NH3-N mg/l 10.21 13.67 16.39 19.73 1.61 2.13 2.84

2.2.2 EXPECTED FLOW AND POTENTIAL INFLOW AND

INFILTRATION (I/I)

HDR estimated the expected average daily wastewater flow at the Memorial WWTP using the current Memorial Unit population and standard domestic per capita wastewater generation rates.

The TDCJ Memorial Unit currently has a population of approximately 2,252 inmates, 93 residential employees and 504 day-shift employees. A flowrate of 150 gallons per capita per day (gpcd) was applied for the inmates and residential employees, and a flowrate of 35 gpcd was used for the day-shift employees.

These per capita flowrates for the inmates and the employes are based on the project scope and are slightly higher than the wastewater flowrate mentioned in TAC §217.32 and Metcalf & Eddy wastewater engineering textbook for residential and correctional facility.

The estimated flow was then compared with the observed annual average daily flow (AADF) at the existing WWTP as shown in Figure 7. Based on the current population and the per capita wastewater generation rate, the expected AADF at the Memorial Unit WWTP would be expected to be approximately 0.37 MGD as shown in Figure 7.

Based on data illustrated on Figure 7, TDCJ Memorial WWTP’s annual average influent flow rate is significantly higher than expected based on standard planning per capita flows. These higher influent flows could potentially be caused by inflow and infiltration (I/I) within the wastewater collection system. The additional wastewater flow potentially attributed from I/I is 0.33 MGD, or 47 percent of the current influent AADF (i.e., 0.7 MGD).

Figure 7 Existing AA Flow Compared to Expected AA Flow

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0.37

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M G

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Average Annual Flow Based on Existing Flow Expected Average Annual Flow

HDR’s assumption of potential I/I is additionally supported by a comparison of the historical monthly water production rates at the TDCJ Memorial Unit. Figure 8 illustrates the average monthly water production volumes and monthly wastewater volumes over a five-year period at the TDCJ Memorial

Unit.

The treated wastewater volume during the months of April to July and from November to December is higher than the water production volume at the Unit. It is unlikely for the monthly water production volume to be lower than the monthly treated wastewater volume. During the months with higher wastewater flow, the data would suggest that more wastewater volume is treated than water is produced – further suggesting that I/I is a likely source of the high AADF at the WWTP.

The results and observations from the Existing Flow and Loads data from the Memorial WWTP along with the information from Expected Flow and Potential Inflow and Infiltration (I/I), illustrated in

Figure 7 and Figure 8 regarding the potential I/I issue at the existing WWTP were presented to

TDCJ during a meeting on 10/01/2025 (see Appendix-A for meeting details).

TDCJ acknowledged the potential presence of I/I in the existing wastewater collection system. The collection system was built more than 90 years ago, therefore, based on the age and expected materials (vitrified clay pipe without gaskets), significant I/I could be entering the collection system.

TDCJ further highlighted frequent plumbing fixture leaks and higher than average water per capita use patterns among the inmates as possible additional reasons for the high AADF and diluted loads seen at the WWTP.

HDR recommended TDCJ to visually inspect the ground surface over the collection system to look for possible direction surface-to-pipe connections to identify the I/I source. The details for the meeting between HDR and TDCJ on 10/01/2025 can be found in Appendix-A.

Figure 8 Existing Water Production and Wastewater Generation Flowrate at TDCJ Memorial Unit

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Average Water Production Average Wastewater Flow

2.3 FUTURE FLOW AND LOADS

During the virtual meeting between HDR and TDCJ on 10/01/2025 (see Appendix-A for meeting details), TDCJ emphasized the need to have an operational WWTP with sufficient capacity to treat existing flows plus the additional flows from the expansion at the Memorial Unit and construction of a new TJJD facility by the end of 2028.

TDCJ is expecting to add additional 400 inmate capacity at the Memorial Unit. The new TJJD will have capacity for 100 juveniles, and approximate 200 additional employees will be required to support both facilities. This population growth will contribute to additional influent wastewater flow at the WWTP.

The observed AADF and the permitted daily average flow at the Memorial Unit WWTP are 0.7 MGD and 0.8 MGD, respectively. The current WWTP AADF is at 87.5 percent of permitted daily average flow. TAC Rule §305.126 requires that whenever AADF at the WWTP reaches 75 percent of its permitted daily average flow for three consecutive months, the permittee must initiate engineering and financial planning for expansion or upgrade of the WWTP, and the WWTP shall be ready to commence construction by the time the AADF reaches 90 percent of the permitted daily flow. The additional population growth at the Memorial facility will add approximately 0.165 MGD (115 gpm), and the new TJJD facility will add approximately 0.035 MGD (24 gpm), altogether additional wastewater flow of 0.2 MGD (139 gpm). The population growth will increase the future AADF beyond the permitted daily average flow capacity of 0.8 MGD at the Memorial Unit WWTP. Therefore, to comply with TAC Rule §305.126, the expanded or new WWTP will be required to treat the future wastewater flow.

To have an operational WWTP before the completion of the future expansions at the Memorial Unit, TDCJ will need to expedite the design and construction of a new WWTP with a permitted daily average flow of 1.6 MGD. This will provide capacity to treat the current AADF (i.e., 0.7 MGD) plus the expected flow due to population growth (i.e., 0.2 MGD) without exceeding the WWTP future permitted flow. The benefit of this will be that the Memorial Unit will have a new WWTP that should reliably provide treatment for the next 30-40 years with operational redundancy.

Given the timing of the expanded or new WWTP and commitments by TDCJ, TDCJ will postpone a full scale investigation into the identification and elimination of the potential I/I sources into collection system, which may potentially reduce the daily influent flow.

2.3.1 RECOMMENDATIONS

HDR suggests the following flow and loading criteria for the preliminary design of the new WWTP.

Additionally, HDR provides a few recommendations to improve the flow and load influent dataset before beginning the Design Phase for the new WWTP.

2.3.1.1 FLOWS

HDR will utilize the design AADF of 1.6 MGD provided by TDCJ along with the MM/AA and MD/AA peaking factors from Table 1 for the preliminary design of the new WWTP.

The future peak two-hour flow (P2H) will be 4.8 MGD with a peaking factor of 3.0. The P2H peaking factor is similar to current peak two hour peaking factor for the existing WWTP.

This assumption was necessary due to the absence of hourly flow data required to determine the existing peak hour flows at the WWTP. TCEQ Rule §217.32 recommends a P2H peaking factor of

4.0 in the absence of hourly flow data, which leads to a P2H flow of 6.4 MGD. However, P2H flow of

6.4 MGD seems significantly high and unlikely for Memorial WWTP based on flow data illustrated in

Figure 2. Therefore, HDR recommends a P2H flow of 4.8 MGD and an hourly peaking factor of 3 for the preliminary design of the new WWTP.

HDR recommends TDCJ record daily influent data, if feasible, to help refine and confirm peak hourly flow data. This sampling would help confirm the recommended peaking factor during detailed design.

2.3.1.2 LOADS

Since the influent concentrations at the existing WWTP are diluted compared to typical domestic

WWTP concentrations, HDR recommended using standard TCEQ BOD5, TSS and NH3-N influent concentrations of 200 mg/l, 200 mg/l and 23 mg/l, respectively, for the preliminary design of the expanded or new WWTP.

Table 3 summarizes the future Average Annual (AA), Maximum Month (MM), Maximum Week (MW) and Maximum Day (MD) flow and loading values along with the peaking factors.

Table 3 Future Influent Flow, Load and Peaking Factor.

Influent

Parameter

Unit Average

Annual (AA)

Maximum

Month (MM)

Maximum

Week (MW)

Maximum

Day (MD)

MM/AA MW/AA MD/AA

Flow MGD 1.60 1.93 2.12 2.35 1.21 1.33 1.47

NH3-N mg/l 23.00 30.79 36.92 44.45 1.61 2.13 2.84

BOD5 mg/l 200.00 307.11 408.43 547.15 1.85 2.71 4.02

TSS mg/l 200.00 288.56 365.99 466.55 1.74 2.43 3.43

2.3.1.3 ADDITIONAL FLOW METERING

However, the future flow and load values summarized in Table 3 should not be considered as final at this time. During the meeting on 10/01/2025, TDCJ was amenable to install an influent flowmeter and a rain gauge upstream of the existing WWTP as a continuation of the investigation to potentially identify the potential I/I sources and quantify peaking factors. HDR will revisit the final flow and load values based on the analysis of further data provided by the TDCJ while the Investigatory Study

Phase progresses.

HDR recommended TDCJ to continue to measure flows and loadings, so that comprehensive dataset is available as the Design Phase commences in early 2026. Generally, HDR and TDCJ expect the new WWTP to be rated at 1.6 AADF unless significant I/I can be removed from the system in a timely and cost-effective manner.

3 WASTEWATER TREATMENT

PLANT (WWTP) CONDITION

ASSESSMENT

3.1 INTRODUCTION

On August 29th, 2025, HDR visited the TDCJ Memorial Unit Wastewater Treatment Plant (WWTP) to conduct a site assessment for the individual processes and support systems. The goal of the assessment was to observe the condition of the existing treatment Unit process and evaluate their observable condition and assign Good, Fair or Poor rating.

The evaluation and recommendation for the existing WWTP processes was determined based on the visual inspection of the facility/equipment age, discussion with the TDCJ operational staff. The evaluation was limited to the observable conditions, equipment and features readily accessible and visible and did not include testing, sampling or any other methods (e.g., non-destructive or performance testing).

After the August 29th, 2025 site visit, during a meeting on October 1st, 2025 with TDCJ staff, HDR was directed that TDCJ desires to proceed with the design of a new 1.6 MGD WWTP due to schedule concerns related to additional inmates and facilities in design (see Appendix-A for details). With this guidance, the existing WWTP will need to remain operational during the design of the new WWTP. Therefore, HDR’s assessment and recommendation is based on activities and improvements necessary to keep the existing WWTP functioning for 3 years and to minimize capital expenditures on the existing WWTP.

Based on this assessment and the direction to keep the existing WWTP operating, HDR will recommend the following dispositions: Maintain, Refurbish, Improve, Replace or No Action.

The WWTP condition assessment along with recommendations for the existing facility are summarized in the tables below by wastewater treatment process area.

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