RFQ_260120_Technical_Attachments.pdf

TUCSON WATER

ADVANCED WATER

PURIFICATION PROGRAM

ATTACHMENT D -

TECHNICAL

ATTACHMENTS

For informational purposes only

PURIFICATION PROGRAM

SITE EVALUATION TECHNICAL

MEMORADUM

Advanced Water Purification Facility Site Evaluation Technical Memorandum

Tucson Water Planning On-Call | Contract No.

226004-02

Owner’s Advisory Services for Tucson Water’s

Advanced Water Purification Program

Revised DRAFT with Portions Redacted

August 11, 2025

Advanced Water Purification Facility Site Evaluation Technical Memorandum

Owner’s Advisory Services for Tucson Water’s Advanced Water Purification Program

August 11, 2025 | i

Contents

Foreword

1 Background

2 Technical Evaluation Criteria

2.1 Conveyance Piping

2.1.1 Effluent and Reclaimed Supply to the AWPF

2.1.2 Connecting AWPF Treated Water to the Potable Water Distribution

System

2.1.3 Wastewater Discharge to Existing Collection System

2.2 Power Supply

2.3 Impact of Floodplain

2.4 Geotechnical

3 Non-Technical Evaluation Criteria

3.1 Site Access

3.2 Boundary Survey Requirements

3.3 Phase I Environmental Site Assessment (ESA)

3.4 Cultural Resources and Historical Clearance

3.5 Native Plant Preservation Requirement

4 Summary and Recommendations

Figures

Figure 1-1. AWPF Site Location

Figure 2-2. Proposed Conveyance Pipeline to AWPF (Option 2)

Figure 2-3. Treated Water Connections to Potable Distribution Lines (Option 2)

Figure 2-4. Wastewater Discharge from AWPF to Gravity Sewer System (Options 2)

Figure 2-5. Potential Overhead Power Supply Source for AWPF at Site Option 2

Figure 2-6. Flood Mapping at Option 2 Location

Figure 3-1. Access to AWPF for Site Option 2

Figure 3-2. Site Option 2 in Pima County

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Foreword

This Draft Technical Memorandum (TM) was originally submitted to Tucson in March 2025 and included a comparison of two site options for the AWPF. Since the development of the

TM, Tucson Water chose to eliminate a site option from consideration. Thus, this TM has been updated with information on Site Option 1 redacted. The purpose of this TM is to relay consideration of the Site Option 2 (the selected site) to interested proposers and provided as supplemental information for RFQ 260120. The information contained herein is provided for informational purposes only and is based on conditions, data, and assumptions available at the time of preparation. No representation or warranty, express or implied, is made as to the accuracy, completeness, or applicability of the information for any purpose other than the stated intent.

1 Background

As part of its Advanced Water Purification (AWP) Program, Tucson Water (TW) intends to receive Class A+ secondary treated effluent from Pima County’s Tres Rios Water

Reclamation Facility (WRF) and implement further advanced treatment for potable distribution. The proposed 2.5 MGD Advanced Water Purification Facility (AWPF) will primarily receive effluent from the Tres Rios WRF, however, Agua Nueva WRF and Tucson

Water’s reclaimed distribution system may be used as alternate sources.

The location (selected Site Option 2) identified for constructing the AWPF (see Figure 1-1) is at the Radio-Controlled Flying Field, located on six adjacent County-owned parcels (Pima

County Parcel Nos. 214-01-0270, 214-01-0260, and 214-01-025A, -025B, -025C, and -

025G), located southeast of Tres Rios WRF. It is conveniently located near a 42-inch potable pipeline (PN# 052-1998) which the AWPF would discharge into TW’s distribution system.

Figure 1-1. AWPF Site Location

The purpose of this technical memorandum (TM) is to present a considerations for the new

AWPF and make recommendations for next steps to support the acquisition of land. The following criteria were evaluated:

260120.

August 11, 2025 | 2

• Technical criteria o Conveyance piping (supply- and discharge-side) o Power supply o Floodplain o Geotechnical

• Non-technical criteria o Site access o Boundary survey o Environmental site assessment o Cultural resources and historical clearances o Native plant preservation requirements

2 Technical Evaluation Criteria

2.1 Conveyance Piping

2.1.1 Effluent and Reclaimed Supply to the AWPF

Tucson Water is actively designing a reclaimed booster pump station at the Tres Rios

WRF effluent chlorine contact basin (referred to as ‘Facility 52’) and a new 24-inch force main which will convey reclaimed water from Facility 52 to an existing 24-inch reclaimed pipeline (PN#031-2014) located along Ina Road. The purpose of that project is to increase reclaimed water supply to Tucson Water’s north and northwest reclaimed customers. Facility 52 is also the proposed primary water source for the AWPF.

HDR recommends the reclaimed booster pump station and force main be used for the water supply to the AWPF. To accomplish that, we propose the addition of a 12-inch tee on the proposed 24-inch reclaimed force main (see Figure 2-1), which could then be used to divert Tres Rios WRF effluent to supply the AWPF as its primary supply. In the event the Tres Rios WRF effluent source were disrupted, reclaimed water from the 24-inch reclaimed pipeline along Ina Road would then be used as the alternate supply. This controlled flow split would include motor operated valves (MOVs), flow meter, pressure reducing valve, check valves located inside a vault.

Figure 2-1 show the proposed pipeline configurations to achieve this diversion. Given the high concentration of cultural/archaeological resources in this general area, pipeline installation for both options has the potential for delays and clearing both alignments may be prudent. The pipeline alignment to the Selected Site Option 2 will parallel an existing buried service water line within a previously disturbed area and may have less potential for encountering cultural/archaeological obstructions.

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Figure 2-1. Proposed Conveyance Pipeline to AWPF (Option 2)

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2.1.2 Connecting AWPF Treated Water to the Potable Water Distribution System

For the Selected Site Option 2, the AWPF is conveniently located nearby an existing 42-inch Zone A1 potable water line (PN# 052-1998), as shown in Figure 2-2.

Overall, considering constructability and future maintenance access, the convenience of

Option 2 tying into the 42-inch line may be considered more favorable. Hydraulic modeling for the tie-in is recommended to understand impacts to the potable distribution system.

Based on information received from Tucson Water, Option 2 has been confirmed to work hydraulically for the connection. The exact location of the tie into the 42-inch line is currently being determined.

Figure 2-2. Treated Water Connections to Potable Distribution Lines

(Option 2)

2.1.3 Wastewater Discharge to Existing Collection System

For site Option 2, emergency overflows and off-spec water from the full-scale plant could be discharged into the existing 42-inch sewer line as shown in Figure 2-3, which is considered generally large enough to accommodate emergency overflows. However, this would need to be confirmed with Pima County.

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Figure 2-3. Wastewater Discharge from AWPF to Gravity Sewer System

(Option 2)

2.2 Power Supply

The proposed AWPF will receive power from Tucson Electric Power (TEP). Based on preliminary analysis, conservatively assuming the new AWPF will involve energy intensive

Reverse Osmosis (RO) treatment, the estimated power consumption is approximately one megawatt. At that magnitude, the power draw will not require a new substation. Instead, the power supply would come from an existing distribution line or dedicated feeder from a substation. The nearest TEP substation is the West Ina Substation, located east of I-10 and south of Ina Road. This substation is not conveniently located for connecting a dedicated feeder to the AWPF at either location and a connection to an overhead power line would be preferred.

TEP has three high voltage lines that parallel I-10 through this general area1, with secondary overhead lines located along the south side of Ina Road, including dedicated overhead lines to the entrance of the Radio Controlled Flying Field parcels (Figure 2-4).

The secondary overhead lines would have to be further evaluated to supply the AWPF, which may entail expanding overhead service to the nearest high voltage line. Further coordination with TEP will be required to determine more specifically how to provide power from their existing system.

1 TEP-Ten-Year-Plan-Transmission-Projects-2023-2032-Maps.pdf

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Figure 2-4. Potential Overhead Power Supply Source for AWPF at Site Option 2

2.3 Impact of Floodplain

Site Option 2 is mainly located in FEMA’s Zone X which is not within any floodplain and is outside the 500-year limits. However, the southwest corner of the site is within FEMA designate Zone AE (see Figure 2-5), which refers to an area located within the 100-year floodplain and subjected to a 1% annual chance of flooding. Additionally, this particular

Zone AE area is integral to the floodway as shown in Figure 2-5.

Based on the information obtained from FEMA’s website, these designated zones were established based on a flood mapping model that was last updated in 2011. Without performing additional floodplain analysis, it is uncertain how accurate these zones are depicted. One potential concern with the Zone AE area is that it is based on an older topography and could possibly be inaccurate. Considering the limitations with the available maps, the facility should be constructed away from Zone AE and the finished elevation should be at least one foot above the 500-year flood elevation. Additional information on the 500-year floodplain has been requested but was not yet received during the update of this TM.

AWPF Site Option

Overhead power

August 11, 2025 | 7

Figure 2-5. Flood Mapping at Option 2 Location

2.4 Geotechnical

Geotechnical evaluations have previously been performed for the Tres Rios WRF and were summarized in Tres Rios Biosolids Solar Dryer Report, 2024 and Interim Biosolids

Facilities, Ina Road WRF report, 2008. These reports stated a potential for hydro-collapse

(settlement upon wetting) of the native site soils. Boring investigations identified potentially collapsible soils occurring in depths from 5- to 10-ft. Depending on the bearing depth of foundation of the new AWPF structures, ground improvement by over-excavation and re-compaction or other method may be needed to reduce potential settlement for structures in particularly with shallow foundation, bearing within the upper 10-ft from existing grade. The reports recommended over-excavation of a minimum depth of 2.0-ft of existing native soils and replacement with compacted engineered fill beneath new facilities. The fact that site

Option 2 is within the vicinity of Zone AE/100-year floodplain and a floodway, potential for hydro-collapse of shallow bearing soils is likely to be more of an issue. Shallow or perched groundwater could be encountered in structure excavations, depending on the time of year. It is recommended to perform a comprehensive geotechnical investigation and consider the following:

• Preliminary investigation for site selection/ “fatal flaw” geotechnical evaluation o Perform one 50-foot deep geotechnical boring at Option 2 site.

o Perform program of soil laboratory tests, including typical classification and soil moisture tests, and consolidation/collapse tests on near-surface samples

(from approximately the upper 10 feet from existing grade) to evaluate hydro-collapse potential.

• Final Design investigation to support design of the new AWPF:

o Sufficient number and depth of borings to cover and support design of the proposed new facility locations.

August 11, 2025 | 8 o For larger size and below-grade structures, depth of the borings should extend to reach an elevation equivalent to approximately 20% of the estimated applied bearing stress.

o Final design investigation should include investigation of foundation conditions and suitability of site soils (from project excavations) for modification of or reconstruction of erosion protection (hardbank or other) along the existing floodway.

o Perform program of soil laboratory tests, including classification and soil moisture tests, and consolidation/collapse tests on near-surface samples

(from the upper 10 feet from existing grade) to confirm the hydro-collapse potential.

The current AWP program master schedule is based on a one-year design phase period. The geotechnical investigation and report is anticipated to take 6 – 8 weeks, which may not be achievable within the expedited design schedule. Tucson Water may want to consider performing the geotechnical investigation prior to selecting the collaborative delivery contractor.

3 Non-Technical Evaluation Criteria

3.1 Site Access

Site Option 2 can be accessed via Walker Road, which is an access road off the I-10 off ramp and is located on Pima County property (Figure 3-1). Tucson Water will need to acquire a right-of-way easement from Pima County to have access to the new AWPF at this location. The requested easement will need to be surveyed to develop a legal description that will need to be incorporated in the easement acquisition documents.

Figure 3-1. Access to AWPF for Site Option 2

3.2 Boundary Survey Requirements

Site Option 2 is entirely located within six different parcels all owned by Pima County (Figure

3-2). Although prior record survey information is available, this survey was conducted in 1987

August 11, 2025 | 9 and would likely need to be updated to facilitate a land sale. Usually, boundary surveys are required only for the area that is partially located with a County owned parcel, in this case

Parcel #214-010-260, since a boundary survey is always required when splitting a parcel.

TW is currently underway completing surveying efforts for this Site.

Figure 3-2. Site Option 2 in Pima County

3.3 Phase I Environmental Site Assessment (ESA)

Site Option 2 will require a Phase I Environmental Site Assessment (ESA) to determine any environmental hazardous materials risks before these parcels are acquired. The ESA would include a record search and site visits to assess the property’s current condition, to determine if there were any previous hazardous materials or environmental incidents on the property or within the surrounding area, or if there is potential contamination to the site from neighboring properties or environmental events. Even if the funding for the purchase was not from a federal agency, it is recommended that an ESA is completed for both sites before acquisition to evaluate the potential environmental risks.

During design and/or construction, projects receiving federal funds may have additional hazardous material requirements in addition to the ESA requirements. Both sites may contain environmental concerns. Option 2 is located near a wastewater facility and may have past environmental concerns associated with it.

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3.4 Cultural Resources and Historical Clearance

Numerous cultural resources investigations, both surface and subsurface, have been performed in the vicinity of both site options, which are encompassed by a large prehistoric village.

Site Option 2, which is not fully paved, was previously surveyed for cultural resources in the 1980s, resulting in the identification of prehistoric surface remains. Because previous surveys were conducted more than 10 years ago, a new pedestrian survey would likely be required; the survey, and archival research that would be required for reporting purposes, would be performed not only to determine whether cultural remains are extant on the site surface but would also allow archaeologists to assess whether subsurface investigations

(archaeological data recovery) are warranted.

Site Option 2 is currently owned by Pima County and was previously developed by them to create the Catalina Radio Control Modelers RC Flying Field. There is evidence that the site was previously subjected to archaeological testing in the 1980s; however, the resulting letter report has yet to be located but, given that the Pima County developed the Flying

Field in 2002 (based on archival aerial photography), it is suspected (not confirmed) that the results of prior archaeological testing were negative. It is possible that Site Option 2 would not require any additional archaeological investigations prior to construction. Since the site is developed, there is also a high likelihood that the area has been disturbed, decreasing the likelihood that intact cultural resources are extant.

The project constitutes a federal undertaking. The U.S. Bureau of Reclamation, as the lead federal agency for Section 106 of the National Historic Preservation Act, will need to consider the effects of the undertaking on cultural resources. Section 106 review is likely to involve consultation with numerous entities including, minimally, Pima County, the Arizona

State Historic Preservation Office, and interested tribes.

3.5 Native Plant Preservation Requirement

Pima County’s Native Plant Preservation Ordinance (NPPO, 18.72) requires a native plant inventory prior to any destruction or removal of native plants “on sites for which a grading plan is required or the total area covered by all grading permits is fourteen thousand

(14,000) square feet or more.”2

Site Option 2 will likely require a NPPO survey as there is vegetation on the western and southern border of the site. As majority of site Option 2 does not have heavy vegetation, it is estimated that the NPPO survey will require minimal effort. The NPPO survey would be conducted prior to vegetation removal and ground-disturbing activities but would not be needed prior to acquisition of the site.

4 Summary and Recommendations

This site evaluation study has identified several tasks that to select the preferred site for the new AWPF. These tasks are described below according to their priority:

1. https://codelibrary.amlegal.com/codes/pimacounty/latest/pimacounty_az/0-0-0-21996

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1. Obtaining Right of Entry (ROE): Tucson Water will need to establish an agreement with Pima County and Radio Control Flying Field (for Option 2) to obtain ROE before performing field investigations including geotech borings, boundary surveys, site and cultural assessments, archaeological and native plant surveys.

2. Fatal Flaw Geotechnical Evaluation: A fatal flaw geotechnical study, comprising borings and soil laboratory tests will need to be completed. Specific items relevant to this evaluation is described in Section 2.4.

3. Coordination with TEP: A preliminary meeting agreement with TEP is recommended to investigate power supply options.

4. Coordination with Pima County Regional Flood Control District: The 100-and 500-year flood elevations will need to be obtained from Pima County

Regional Flood Control District and verified for site Option 2.

SUPPLEMENTAL INFORMATION FOR THE SITE

EVALUATION TECHNICAL MEMORADUM

RECORD DRAWINGS FOR THE CAP

NORTHWEST PHASE 1B TRANSMISSION MAIN

REGULATORY AND PERMITTING MATRIX

Draft Communications

Plan

Submission of AWP

Permit Application

Distribution of AWT

Final

Communications

Plan Submitted at least 30 days prior

Pre-Application

Meeting with

ADEQ

Pilot Plan

Pilot Plan and Report

Initial Source Water

Characterization

Plan

ISWC Plan and Report

Conduct Initial

Source Water

Monitoring

Draft ESCP

Draft TMF

Proposed Pilot Train

NPPs Applicant

Draft

Communications

Plan

Optional to Submit to ADEQ

Initial Source Water

Characterization

Report

Conduct Piloting

APP

Permit

Joint Plan

Plans and Specs

Design Report

Full Scale Verification Plan

Draft Operations Plan

TMF

Initial ESCP Plan

Proposed Action Levels

Final Design & As-builts

Operations Plan

Full-Scale Verification

Report

Vulnerability Assessment

Final Communications

Plan

Final ESC Plan

Engineer’s COC

Department approves all compliance schedule items

Prove Control of Projected Chemical

Treatment List (Tier 1, Tier 2, Pass

Through)

Informs ESC Plan

Not Required to Submit to ADEQ before Permit Application

Not Required to Submit to ADEQ

Prior to Initial Source Water

Monitoring but Recommended

Construction of

AWP Facility

Advanced Water Purification Program

Regulatory and Permitting Matrix for 18 AAC 9, Art 8 as interpreted by HDR as of August 2025

Optional

O p tio n a l

O p tio n a l

TREATMENT FEASIBILITY

WORKSHOP SLIDE DECK

Originally presented to Tucson Water in May

2025 by HDR

© HDR 2024, all rights reserved.© HDR 2024, all rights reserved.

Tucson Water Advanced Water Purification (AWP) Treatment Feasibility Study

May 23, 2025

AGENDA

Treatment Train Selection

Source Water Quality

Finished Water Quality/Goals

Preliminary Site Layouts

Next Steps

Project & Task Background

Team Introduction

01 Team Introduction

01 Project & Task Background

• Key driver - loss of water supply capacity in the NW portion of TW’s service area

• Comparative analysis of AWP trains meeting ADEQ Final AWP Rule requirements

• Carbon (non-RO) based treatment

• RO based treatment

2.5-MGD Advanced Water Purification Facility (AWPF)

AWP Location: Pima

County Property

Tres Rios Water

Reclamation

Facility

Supply Option 1:

TRWRF Effluent

(Class A+)

Supply Option 2:

Reclaimed System

(Class A+)

02 Source Water Quality

Source Water Quality Data Summary

• Tres Rios Final Effluent (2019-2024)

• Reclaimed Water

• Agua Nueva Final Effluent (2019-2024)

• Recovery Well 522 (2019-2024)

• Recovery Well EW-007A (2024)

• Recovery Well TA-030A (2024)

Supply Option 1 – Tres Rios Water Reclamation Facility Effluent

AWP

Location

Tres Rios Water

Reclamation

Facility

EFFLUENT

Supply Option 2

– Reclaimed System Supply

Source Water Quality Recovery Wells

Average

Agua Nueva Final

Effluent Average

Tres Rios Final

Effluent Average LimitUnitContaminant

390.860.6510ng/L Perfluorohexanesulfonic acid

(PFHxS)

135.84.74ng/LPerfluorooctanoic acid (PFOA)

322.02.74ng/L Perfluorooctanesulfonic acid

(PFOS)

758766721

450 (Average Native

Groundwater)

500 (SMCL)

mg/LTotal dissolved solids (TDS)

3.2No dataNo data2 (AWP)mg/LTotal organic carbon (TOC)

0.720.610.580 (TW goal)µg/L1,4-Dioxane

0.010.370.390.2µg/LBenzo(a)pyrene (PAHs)

0.300.070.070.2µg/L 1,2-Dibromo-3-chloropropane

(DBCP)

0.26No dataNo data0.05µg/LEthylene dibromide

0.0381.11.11µg/LPentachlorophenol

No data34350.03ng/LDioxin (2,3,7,8-TCDD)

03 Finished Water Quality/Goals

Existing Water Quality at Proposed Point of Connection

Pressure Zone ZA

• SP-030

• SP-035

5.5 years of data – 2020 to 2025 (inclusive)

Water Quality at Proposed Point of Connection Source

Waters* SP-035SP-030LimitUnit

Water Quality

Parameter

1092729749Noneumhos/cmConductivity

7.27.87.86.5-8.5s.u.pH

184108108Nonemg/L CaCO3Alkalinity

1.080.340.41TTNTUTurbidity

4.70.760.7110mg/L NNitrate

0.140.050.051mg/L NNitrite

3.20.420.452mg/LTOC

282228235Nonemg/L CaCO3Hardness

1376465Nonemg/LSodium

1517276250mg/LChloride

170154162250mg/LSulfate

748570 (other wells)**250mg/LTDS

* Average of Tres Rios effluent, Agua Nueva effluent, and reclaimed water concentrations, if available

** Further evaluation needed.

04 Treatment Train Selection

ADEQ Final AWP Rule - Key Requirements

18 AAC 9, Article 8, F832

• Pathogen Control:

• Standard Approach:

• 13/10/10 log reductions for Virus/Crypto/Giardia

• Site Specific Approach:

• 8/6/5.5 log reductions for Virus/Crypto/Giardia (even if non-detects are demonstrated by the sampling program)

• Site-specific pathogen monitoring for at least 24 months

• Disinfection:

• At least one validated disinfection treatment process targeting each of the three reference pathogens

• UV disinfection with a dose of at least 300 mJ per cm2

ADEQ Final AWP Rule - Key Requirements

18 AAC 9, Article 8, F832

• Chemical Control:

• At least one validated filtration process targeting each of the three reference pathogens

• At least three diverse and separate treatment processes, including, but not limited to Advanced Oxidation Process (AOP) and physical separation process

• AOP to achieve ≥ 0.5 log reduction of 1,4-dioxane and Tucson Water’s operational goal of 0.35 µg/L

• Ozone/BAC processes designed to provide no less than 1.0 log reduction of formaldehyde, acetone, carbamazepine, and sulfamethoxazole

Pathogen Log Reduction Values (LRVs)

• ADEQ AWP TAG Recommendations provided values for illustration and discussion purposes only

• Needs to be validated per established literature and pilot testing.

• Final AWP Rule

• Max 6 credit per each treatment/physical barrier

• Treatment train, cumulatively, shall meet or exceed either the standard (13/10/10) or site-specific (8/6/5.5) log reduction targets

NotesGiardia Crypto Virus Unit Process

*For Crypto- ADEQ TAG mentioned

>2, using 2 here conservatively2.52*2

Coag-Floc-

Sed- Filtration

*For Crypto- ADEQ TAG mentioned up to 1; British Columbia’s

Guidelines for Pathogen Log

Reduction Credit Assignment provides CT needed to reach 2 LRV of crypto.62*6Ozone

000BAC

000GAC

440MF/UF

*Range is 1.5 to 3 (ADEQ TAG);

usually the LRV is 0.5 to 21.5*1.5*1.5*RO

666UV/AOP

*For Virus- ADEQ TAG mentioned up to 6, EPA technical Guidance Manual provides CT requirements up to 4 credit

**For Giardia- ADEQ TAG mentioned up to 6, EPA technical Guidance

Manual provides CT requirements up to 3 credit3**04*Chlorine

Carbon-Based Treatment Train

• Process and chemical dosing pumps are not shown.

• Process and chemical dosing pumps are not shown.

Minimum LRV

Requirement Total LRVChlorineIX GACUV/AOPOzone-BACMF/UFFloc-SedUnit Process

1318.04006602Virus

1014.00006242Crypto

1021.53006642.5Giardia

PFAS (esp.

short-chain)

PFAS, VOCs, SVOCs, TOC/DOC

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, 1,4 –dioxane

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, TOC/DOC

Turbidity

Turbidity

IOCs

TOC/DOC

Chemical Barrier

GAC after UV/AOP serves as quenching agent in addition to adsorber

Minimum LRV

Requirement Total LRVChlorineIX GACUV/AOPOzone-BACMF/UFFloc-SedUnit Process

1318.04006602Virus

1014.00006242Crypto

1021.53006642.5Giardia

PFAS (esp.

short-chain)

PFAS, VOCs, SVOCs, TOC/DOC

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, 1,4 –dioxane

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, TOC/DOC

Turbidity

Turbidity

IOCs

TOC/DOC

Chemical

IX provide chemical barrier for short-chain PFAS

Minimum LRV

Requirement Total LRVChlorineIX GACUV/AOPOzone-BACMF/UFFloc-SedUnit Process

1318.04006602Virus

1014.00006242Crypto

1021.53006642.5Giardia

PFAS (esp.

short-chain)

PFAS, VOCs, SVOCs, TOC/DOC

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, 1,4 –dioxane

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole

Pharmaceuticals, VOCs, SVOCs, TOC/DOC

Turbidity

Turbidity

IOCs

TOC/DOC

Chemical

RO-Based Treatment Train

Minimum LRV

Requirement Total LRVChlorineUV/AOPROMF/UFOzone-BACUnit Process

1317.5461.506Virus

1013.5061.542Crypto

1020.5361.546Giardia

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole, Pharmaceuticals, VOCs, SVOCs, 1,4 – dioxane

Formaldehyde, Acetone, Carbamazepine, Sulfamethoxazole, Pharmaceuticals, Turbidity

1,4-dioxane, VOCs, SVOCs, TOC/DOC, PFAS

TDS

Turbidity

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole, Pharmaceuticals, VOCs, SVOCs, TOC/DOC

Chemical Barrier

Ozone/BAC provides additional chemical barrier and other advantages.

Minimum LRV

Requirement Total LRVChlorineUV/AOPROMF/UFOzone-BACUnit Process

1317.5461.506Virus

1013.5061.542Crypto

1020.5361.546Giardia

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole, Pharmaceuticals, VOCs, SVOCs, 1,4 – dioxane

Formaldehyde, Acetone, Carbamazepine, Sulfamethoxazole, Pharmaceuticals, Turbidity

1,4-dioxane, VOCs, SVOCs, TOC/DOC, PFAS

TDS

Turbidity

Formaldehyde, Acetone

Carbamazepine, Sulfamethoxazole, Pharmaceuticals, VOCs, SVOCs, TOC/DOC

Chemical Barrier

Why Ozone/BAC?

• Additional treatment barrier → process resiliency

• Reduces downstream membrane fouling → operational savings + improved uptime

• Improves RO concentrate quality → easier disposal

• AWPs using/testing ozone/BAC with RO

• Los Angeles

• San Diego

Source:

Trussell and

Pisarenko (2024)

05 Preliminary Site Layouts

Site Layout- Carbon Based

Site Layout- RO Based (With Ozone-BAC)

Site Layout- RO Based (Without Ozone-BAC)

OPEN HOUSE SLIDE

DECK

TUCSON WATER DEPARTMENT

VIRTUAL OPEN HOUSE

ADVANCED WATER PURIFICATION PROJECT

Scott Schladweiler, P.E.

Deputy Director Tucson Water

June 2nd, 2025

Agenda

Project Need & Background

Project Scope

Schedule

Questions

Project Need & Background

Water Production & Rainwater Offset for Tucson Water Service Area (1940-2024)

Colorado River WaterGroundwater Remediated Groundwater Recycled Rainwater Harvesting (Not to Scale)

System Conservation “Bucket 1” System Conservation

- 2023 through 2025

- Total of 110,000 acre-feet left in Lake Mead

- $44M used to enhance long term water supply resiliency projects

- Water quality projects

“Bucket 2” System Conservation

- Proposed a 2.5 MGD Advanced Water

Purification Facility (AWPF)

- Located near the Tres Rios Water

Reclamation Facility

- Total BOR Funding: $86.7M

Tres Rios WRF

Tucson Water Reclaimed Plant

Agua Nueva WRF

One Water 2100 Plan

• Approved by Tucson Mayor and Council in

October 2023

• Comprehensive, long range water resource management plan

• Right water for the right purpose

• Identified key strategies with community and stakeholder input

TucsonOneWater.com

Project Benefits

PORTFOLIO

DIVERSIFICATION

REDUCED

SYSTEM LOSS

REDUCED

DEPENDENCY

ECONOMIC

DEVELOPMEMT

Project Scope RFQ for Progressive Design Builder

• Advanced Water Purification Facility (AWPF) designed for 2.5 MGD capacity

• Primary Source: Tres Rios WRF Effluent

• Secondary Source: TW’s Reclaimed System

• Progressive Design Builder

• Final Treatment Selection

• 1-Year Pilot

• Design & Construction

• GMP Development

• Permitting (AWP & APP)

• Close Coordination with Operations

Manager at Risk

Proposed Scope

AWPF Location:

Pima County Property

Tres Rios Water Reclamation

Facility

Supply Option 1:

TRWRF Effluent (Class A+)

Supply Option 2:

• Operations of the AWPF (future RFQ)

• Public Communications

• Owner’s Advisory Services

• Initial Source Water Characterization

• Enhanced Source Control Plan / Program

• Initial Coordination with Pima County

Scope by Others

AWPF Location:

Pima County Property

Tres Rios Water Reclamation

Facility

Supply Option 1:

TRWRF Effluent (Class A+)

Supply Option 2:

Schedule

Project Completion by Q3 - 2031

Q3/Q4

RFQ for Progressive

Design Builder

Released

Q1/Q2

Progressive Design Builder

Selected and NTP

Q2/Q3

RFQ for Operations

Team Released

Q3/Q4

Operations Team

Selected and NTP

Today

Open House & Market

Sounding

Q3

One-on-One Meetings w/

Potential Proposers

Tentative Schedule (subject to change)

1x1’s

Agenda’s provided by PDB / Operations Firms

Questions submitted ahead of 1x1

Interested in topics that reduce risk, streamline delivery, improve delivery success, foster collaboration and engagement

Subject to additional requirements by TW

Procurement

Questions?