TM-Northwest_Area_Wells_Alternatives_Evaluation_Dec_2020.pdf

TUCSON WATER DEPARTMENT

Impacts of Targeted Emerging Contaminants on Water Supplies and Capital Assets

Technical Memorandum

NORTHWEST AREA WELLS

ALTERNATIVES EVALUATION

FINAL | December 2020

TUCSON WATER DEPARTMENT

Impacts of Targeted Emerging Contaminants on Water Supplies and Capital Assets

Technical Memorandum

NORTHWEST AREA WELLS ALTERNATIVES

EVALUATION

FINAL | December 2020

NMaze Marron_seal

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | i pw://Carollo/Documents/Client/AZ/Tucson Water/11364A00/Deliverables/TM02/TM02

Contents Technical Memorandum 1

1.0 Introduction 1

1.1 Project Background 1

1.2 Purpose 1

1.3 Technical Memorandum Organization 2

2.0 Water Quality and Infrastructure 2

2.1 EPA Guidance Background and Tucson Potable Water Quality Operational Targets 2

2.2 Groundwater Quality Data 4

2.3 Existing Potable Water Infrastructure 7

2.3.1 Age and Condition of Wells 8

3.0 Blending Alternatives 9

4.0 Treatment Technologies 11

4.1 Granular Activated Carbon Adsorption for PFAS Removal 11

4.2 UV AOP for 1,4-dioxane Removal 12

4.3 Pretreatment for Solids Removal 12

4.4 Treatment Technology Benefits and Challenges 13

4.5 Treatment Alternatives 13

5.0 Evaluation of Alternatives 14

5.1 Conceptual Design Criteria 14

5.2 Simplified Process Schematics 15

5.3 Conceptual Site Layouts 15

5.4 Conceptual Replacement Well and Treatment Cost Opinions 16

5.5 Economic Analysis of Cost Opinions 16

6.0 Summary 19

Appendices Appendix A Historical Water Quality Data

Appendix B Simplified Process Schematic

Appendix C Conceptual SIte Layouts

Appendix D Conceptual Capital and Annual Operations and Maintenance Cost Opinions

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Tables Table 1 Federal Guidelines for PFOS, PFOA, 1,4-dioxane, and TCE 3

Table 2 Treated Water Quality Operational Targets 3

Table 3 Ground Water Quality Data 5

Table 4 Existing Potable Water Infrastructure 8

Table 5 Age and Condition of Wells 8

Table 6 Average concentration of individual wellheads and the blends 10

Table 7 Benefits and Challenges of Feasible Treatment Technologies 13

Table 8 Treatment Alternatives Matrix 13

Table 9 Design Capacities 14

Table 10 GAC Adsorption Conceptual Design Criteria 14

Table 11 UV AOP System Conceptual Design Criteria 15

Table 12 Conceptual Centralized Wellhead 1,4-dioxane and PFAS Treatment Cost Opinions 17

Figures Figure 1 PFAS Speciation for NW Area Wells Removed from Service 4

Figure 2 1,4-dioxane Concentrations for NW Area Wells Removed from Service 6

Figure 3 NW Area PFOA+PFOS, 1,4-dioxane and TCE Results 7

Figure 4 Example GAC Adsorption Pressure Vessels 11

Figure 5 Example LPHO UV Reactors 12

Figure 6 Centralized Wellhead 1,4-dioxane and PFAS Treatment Conceptual Cost Opinion 18

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Abbreviations AACE Association for the Advancement of Cost Engineering

ADR Arizona Department of Water Resources

AFFF aqueous film-forming foams

Carollo Carollo Engineers, Inc.

EBCT Empty bed contact time

EPA U.S. Environmental Protection Agency

GAC granular activated carbon gpm gallons per minute

HA Health Advisory hp horsepower

LPHO low pressure high output

MCL maximum contaminant level mg/L milligrams per liter µg/L micrograms per liter

MRL Method Reporting Limit

NW Northwest

O&M operations and maintenance

PFAS perfluoroalkyl

PFBS perfluorobutanesulfonic acid

PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctane sulfonic acid ppb parts per billion ppm parts per million ppt parts per trillion

SCADA supervisory control and data acquisition

SDWA Safe Drinking Water Act

TCE Trichloroethylene

Tucson Water City of Tucson Water Department

UV AOP ultraviolet light-hydrogen peroxide advanced oxidation process

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Technical Memorandum

NORTHWEST AREA WELLS ALTERNATIVES

EVALUATION

1.0 Introduction

The following sections review the project background, purpose, and the report organization.

1.1 Project Background

The City of Tucson Water Department (Tucson Water) supplies water to about 731,000 people over a service area of nearly 400 square miles in Tucson, Arizona. The utility maintains approximately 200 active production or standby wells and hundreds of monitoring wells used to measure groundwater levels and test groundwater quality.

Groundwater quality monitoring results indicated the presence of 1,4-dioxane and perfluoroalkyl substances (PFAS), particularly perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), in wells in the Northwest (NW) area exceeding Safe Drinking Water Act (SDWA) Health Advisory (HA) levels published by the U.S. Environmental Protection Agency (EPA).

Trichloroethylene (TCE), a regulated compound with a maximum contaminant level (MCL), was detected in one of the production wells in the NW area.

1,4-dioxane is a synthetic chemical used as a stabilizer for chlorinated solvents (particularly 1,1,1 TCE) and is used in products such as paint strippers, greases, and waxes. PFAS are fluorinated organic chemicals, which among consumer product applications, are also part of aqueous film-forming foams (AFFF), that are or were commonly used for suppressing aircraft fires and for training to fight such fires. TCE is used as a solvent for degreasing metals in manufacturing processes, in addition to a variety of consumer applications. EPA's Drinking Water Health Advisory levels are not enforceable standards but are included among the factors EPA considers when setting new or revised SDWA MCLs, which are enforceable standards.

1.2 Purpose

Tucson Water commissioned an evaluation of the potential impacts of targeted emerging contaminants on water supplies and capital assets including developing blending approaches and alternative treatment process technologies to reduce concentrations of TCE, PFAS, and 1,4-dioxane at specific potable production wells. The evaluation includes preliminary engineering information necessary for comparison of the blending and treatment alternatives and for advancing the implementation of groundwater quality improvements as a pro-active public health measure.

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1.3 Technical Memorandum Organization

This technical memorandum is organized into the following sections and appendices.

• Section 1.0 - Introduction

• Section 2.0 - Water Quality and Infrastructure

• Section 3.0 - Blending Alternatives

• Section 4.0 - Treatment Technologies

• Section 5.0 - Evaluation of Alternatives

• Section 6.0 - Summary

• Appendix A - Historical Water Quality Data

• Appendix B - Simplified Process Schematics

• Appendix C - Conceptual Site Layouts

• Appendix D - Conceptual Capital and Annual Operations and Maintenance Cost

Opinions

2.0 Water Quality and Infrastructure

The following sections review regulatory background, Tucson’s water quality operational targets, current water quality, and the existing infrastructure in place for the water systems considered in this study. Due to age of wells in the project area, Tucson Water asked Carollo Engineers, Inc. (Carollo) to investigate which of the project wells are approaching the end of their service life and may need to be replaced.

2.1 EPA Guidance Background and Tucson Potable Water Quality Operational Targets

PFAS are not currently regulated by EPA, but there is a non-enforceable HA of 70 parts per trillion (ppt) for PFOA and PFOS, combined. EPA set this HA in May of 2016, updating the guidance from the earlier 2009 provisional HAs of 400 ppt for PFOA and 200 ppt for PFOS. EPA has not published drinking water HAs for any PFAS other than PFOA and PFOS. Table 1 summarizes the Federal guidance values.

Although 1,4-dioxane is not currently regulated by EPA under the SDWA, EPA set a Drinking Water Health Advisory level of 35 parts per billion (ppb) in 2011 based on an excess estimated lifetime cancer risk of 1 x 10-4 (2011 Edition of the Drinking Water Standards and Health Advisories). The corresponding drinking water concentration representing a 1 x 10-6 cancer risk level (one in one million) for 1,4-dioxane is 0.35 ppb. EPA established an MCL of 5 ppb for TCE in 1985.

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Table 1 Federal Guidelines for PFOS, PFOA, 1,4-dioxane, and TCE

Parameter Units Value (1), (2), (3)

PFOA ppt 70

PFOS ppt 70

PFOS + PFOA ppt 70

1,4-dioxane ppb 0.35

TCE ppb 5.0 Notes:

(1) EPA's health advisories for PFOA and PFOS (May 19, 2016).

(2) EPA risk assessments indicate that the drinking water concentration representing a 1 x 10-6 cancer risk level for

1,4-dioxane is 0.35 µg/L (2011 Edition of the Drinking Water Standards and Health Advisories).

(3) EPA’s MCL for TCE.

Abbreviations:

PFOA = perfluorooctanoic acid PFOS = perfluorooctanesulfonic acid TCE = Trichloroethylene

MCLs are legally enforceable drinking water standards, while HAs serve as informal technical guidance to assist Federal, state, and local officials, as well as managers of public or community water systems, in protecting health. HAs are not legally enforceable Federal standards and may change if new toxicological assessments from EPA become available. In the absence of enforceable Federal drinking water standards, Tucson Water recently established operational water quality targets for the potable water system. Table 2 summarizes the current Tucson potable water quality operational targets for PFAS, 1,4-dioxane, and TCE.

Table 2 Treated Water Quality Operational Targets

Parameter Units Value

PFOS ppt 7

PFOA ppt 11

PFHxS ppt 7

PFOS + PFOA + PFHxS + PFHpA(1) ppt 18

PFHxA ppt 200,000

PFBS ppt 420

1,4-dioxane ppb 0.35

TCE ppb 1.5 Notes:

(1) When PFOS, PFOA, PFHxS, and PFHpA are present, combined concentrations should not exceed the operational target.

Abbreviations:

PFOA = perfluorooctanoic acid PFOS = perfluorooctanesulfonic acid PFHxS = perfluorohexanesulfonic acid PFHpA = perfluoroheptanoic acid PFHxA = perfluorohexanoic acid PFBS = perfluorobutanesulfonic acid TCE = Trichloroethylene ppt = parts per trillion ppb = parts per billion

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2.2 Groundwater Quality Data

Tucson Water owns several potable production wells in the NW area. During 2018-2019, nine of the wells in this area were taken out of service due to detections of PFAS, 1,4-dioxane, and TCE.

Table 3 shows the water quality results from the most recent sampling done at these nine production wells.

Figure 1 shows the PFAS speciation from the most recent sampling event and Figure 2 shows 1,4-dioxane speciation from all the sampling events. Wells A-053A and A-057B were most recently sampled for PFAS and 1,4-dioxane on June 3, 2019 and July 26, 2016, respectively. Wells Y-001B, Y-004A, and Z-103A were most recently sampled for PFAS and 1,4-dioxane on October 15, 2018. Wells Z-014B and Z-015A were sampled for PFAS and 1,4-dioxane on October 16, 2018. Appendix A shows a detailed summary of all historical PFAS and 1,4-dioxane data for all the nine wells. TCE was found only in Well Z-002A at a concentration of 2.5 ppb.

Figure 1 PFAS Speciation for NW Area Wells Removed from Service

Co nc en tr at io n (n g/ L)

Well

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

Method Reporting Limit (MRL) = 2 ppt

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Table 3 Ground Water Quality Data

Parameter Units Well

Y-001B(1) Well

Y-004A(1) Well

Z-013A(1) Well

Z-014B(4) Well

Z-015A(2) Well

A-053A(3) Well

A-057B(3) Well

Z-002A(4) Well

Z-005A(5)

PFOS(6) ppt 90 63 120 <2 78 <2 15 <2 <2

PFOA(6) ppt 18 19 28 <2 15 <2 0 <2 <2

PFHxS(6) ppt 58 32 60 <2 110 4 9.5 <2

PFHpA(6) ppt 5.3 4.4 7.6 <2 5 <2 0 <2

PFOS + PFOA

+ PFHxS + PFHpA(6) ppt 171.3 118.4 215.6 <2 208 4 24.5 <2 <2

PFHxA(6) ppt 5.6 7.6 9 <2 7.7 <2 3.1 <2

PFBS(6) ppt 11 11 13 <2 13 <2 <2 <2

1,4-dioxane(7) ppb 0.66 0.71 1.26 <0.1 0.32 <0.1 <0.1 <0.1 0.19

TCE(8) ppb <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 2.5 <0.5 Notes:

(1) Data from sampling conducted on 10/15/2018.

(2) Data from sampling conducted on 10/16/2018.

(3) PFAS data from sampling conducted on 03/06/2019 and 1,4-dioxane data from sampling conducted on 07/26/2016.

(4) Data from sampling conducted on 10/30/2018.

(5) Data from sampling conducted on 03/06/2018.

(6) MRL for PFAS is 2 ppt.

(7) MRL for 1,4-dioxane is 0.1 ppb.

(8) MRL for TCE is 0.5 ppb.

Abbreviations:

PFOA = perfluorooctanoic acid PFOS = perfluorooctanesulfonic acid PFHxS = perfluorohexanesulfonic acid PFHpA = perfluoroheptanaonic aid PFHxA = perfluorohexanoic acid PFBS = perfluorobutanesulfonic acid TCE = Trichloroethylene MRL = Method Reporting Limit

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Figure 2 1,4-dioxane Concentrations for NW Area Wells Removed from Service

Figure 3 shows the testing results for 1,4-dioxane and the combined concentration of PFOS and PFOA in the nine production wells removed from service and the TCE result for Well Z-002A. The wells were taken out of service on the following dates:

• Wells Z-002A on March 9, 2016.

• Wells Z-014B and Y-001B on September 22, 2016.

• Wells Z-005A, Z-015A and Z-013A on September 19, 2016.

• Wells A-053A and A-057B on July 18, 2018.

0.0

0.5

1.0

1.5

2.0

2.5

Co nc en tr at io n (p pb

Date Sampled

Y-001B

Y-004A

Z-013A

Z-014B

Z-015A

A-053A

A-057B

Z-002A

Z-005A

Method Reporting Limit (MRL) = 0.1 ppb

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Figure 3 NW Area PFOA+PFOS, 1,4-dioxane and TCE Results

2.3 Existing Potable Water Infrastructure

Table 4 summarizes key information for the NW area wells affected by 1,4-dioxane, PFAS, and TCE. Duty cycles are assumed to be 100 percent for the purpose of this study.

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Table 4 Existing Potable Water Infrastructure

Well Name Actual Pumping Capacity

(gpm) ADWR Permitted Pumping Capacity

Motor Horsepower (hp)

Y-001B 740 720 50

Y-004A 935 2000 125

Z-013A 477 680 125

Z-014B 814 485 150

Z-015A 801 640 125

A-053A 243 244 100

A-057B 558 575 100

Z-002A 389 558 50

Z-005A 315 372 75 Abbreviations:

gpm = gallons per minute ADWR = Arizona Department of Water Resources hp = horsepower

2.3.1 Age and Condition of Wells

Due to age of wells in the project area, Tucson Water asked Carollo to investigate which of the project wells are approaching the end of their service life and may need to be replaced. Table 5 shows the age and condition of the project wells classified as “good”, “fair”, or “poor” by Tucson Water based upon operations and maintenance experience.

Table 5 Age and Condition of Wells

Well Date Drilled Deepening Date Condition

Y-004A 1982 Fair

Y-001B 2007 Good

Z-013A 1972 1983 Poor

Z-014B 1983 Fair

Z-015A 1974(1) Poor

A-053A 1959 1976 Poor

A-057B 1998 Fair

Z-002A 1952 1975 Poor

Z-005A 1942 1947, 1978 Poor Notes:

(1) Repaired in 2019.

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3.0 Blending Alternatives

These nine wells were grouped into three clusters: Northern (Y-004A and Y-001B), Central (Z-013A, Z-014B and Z-015A) and Southern (A-053A, A-057B, Z-002A and Z-005A) clusters.

Figure 3 shows the clustering based upon geographical location of these wells and feasibility of centralized treatment.

One strategy for meeting water quality operational targets is to blend water from alternative groundwater sources with water from the study area’s affected wells. Due to the differences in contaminant concentration among different wells of the area and relatively low concentration in the southern cluster wells, blending wells of the same cluster was evaluated. Table 6 shows the concentration of the contaminants (PFAS, 1,4-dioxane, and TCE) in the individual well and the blend of each cluster. The southern cluster well blended water meets all Tucson Water operational targets for PFAS, 1,4-dioxane, and TCE. The Northern and Central cluster wells don’t meet the operational target for PFAS and 1,4-dioxane after blending. Table 12 shows the conceptual cost opinion for blending the southern cluster wells.

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Table 6 Average concentration of individual wellheads and the blends

Cluster Well/Blend Flow

(gpm)

PFOS+PFOA

(ppt)

PFOS + PFOA +

PFHxS + PFHpA

(ppt)(1)

1,4-dioxane (ppb) (2)

TCE

(ppb) (3)

Northern Y-004A 935 122.6 110.2 0.78 <0.5

Y-001B 740 86.4 96.0 0.76 <0.5

Blend 1,505 77.6 102.3 0.77 <0.5

Central Z-013A 477 122.6 162.3 1.52 <0.5

Z-014B 814 8.8 8.8 0.05 <0.5

Z-015A 801 87.4 98.9 0.50 <0.5

Blend 2,092 64.8 78.3 0.56 <0.5

Southern A-053A 243 5.9 5.0 <0.1 <0.5

A-057B 558 12.5 17.3 <0.1 <0.5

Z-002A 389 <2.0 <2.0 <0.1 2.5

Z-005A 315 3.2 3.2 0.20 <0.5

Blend 1,675 6.3 7.9 0.04 0.65 Notes:

(1) MRL for PFAS.

(2) MRL for 1,4-dioxane.

(3) MRL for TCE.

Abbreviations:

PFOA = perfluorooctanoic acid PFOS = perfluorooctanesulfonic acid PFHxS = perfluorohexanesulfonic acid PFHpA = perfluoroheptanaonic aid TCE = Trichloroethylene MRL= Method Reporting LImit

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4.0 Treatment Technologies

Both PFAS and 1,4-dioxane can be treated by several different treatment technologies. The following sections provide an overview and review the benefits and challenges of each treatment technology considered in the study.

4.1 Granular Activated Carbon Adsorption for PFAS Removal

Granular activated carbon (GAC) is a porous material with a very high volumetric surface area that is effective for adsorption of many contaminants. Studies and full-scale installations have shown GAC adsorption to be effective at removing PFAS from contaminated water. However, once active adsorption sites have been loaded, the GAC media must be replaced with new carbon and sent for off-site disposal or regeneration. The carbon life for PFAS removal can vary widely depending on carbon type, target contaminant concentrations, background water quality, and PFAS carbon chain length. In general, GAC adsorbs longer-chain PFAS (e.g., PFOS and PFOA) better than shorter-chain PFAS (e.g., PFHxA and PFBS). When ultraviolet light-hydrogen peroxide advanced oxidation process (UV AOP) is used, GAC can be installed for hydrogen peroxide quenching as well. Bed life for GAC used just for hydrogen peroxide quenching will exceed the bed life for PFAS removal. GAC adsorption systems can be configured with reversible lead-lag pressure vessels in series to monitor contaminant breakthrough between the vessel pairs and increase efficient utilization of media capacity by replacing media in lead vessels first and switching lag vessels to lead service. Carbon particle degradation can occur during initial loading and normal operation, resulting in carbon fines that require periodic backwashing to reduce pressure loss through the vessels. Carbon bed compression during normal operation and sediment commonly produced by wells, particularly as they age, also contribute to the need for periodic backwashing of GAC media, typically at lower rates than after initial media installation. Backwash supply and backwash waste equalization and settling provisions would be provided for GAC adsorption systems. Figure 4 shows a typical example of a full-scale GAC adsorption lead/lag pressure vessel system in southern Arizona.

Figure 4 Example GAC Adsorption Pressure Vessels

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4.2 UV AOP for 1,4-dioxane Removal

UV AOP can be used to destruct specific trace level contaminants in water, such as 1,4-dioxane.

The UV light and hydrogen peroxide will form hydroxyl radicals that oxidize the contaminants. In AOP treatment, excess hydrogen peroxide is fed to the system leading to hydrogen peroxide leaving the UV reactors. Both GAC, as mentioned in Section 4.1, and sodium hypochlorite addition can be used to quench (or neutralize) the excess hydrogen peroxide. Sodium hypochlorite addition will require chemical feed pumps to be paced off the hydrogen peroxide feed rate. With varying sodium hypochlorite feed rates, there is an increased risk of exceeding the maximum residual disinfection level of 4 mg/L for chlorine. For this study, low pressure high output (LPHO) UV lamp system in series with GAC pressure contactors was considered. LPHO lamps have low UV intensities and are more energy efficient compared to medium pressure lamps, resulting in lower power costs. Figure 5 shows an example of installed LPHO UV AOP reactors.

Figure 5 Example LPHO UV Reactors

4.3 Pretreatment for Solids Removal

Pretreatment removal of solids typically produced by wells is prudent for all groundwater treatment systems to protect downstream process equipment. In the event of a well casing failure, or if sand, gravel, or other sediment are present in the well discharge flow, pretreatment will mitigate potentially damaging effects of sediment. For example, if sediment is deposited in ultraviolet light advanced oxidation process reactor vessels, UV lamp sleeves can begin to foul or potentially break. If sediment gathers on top of granular activated carbon media beds, differential pressure across the media will increase, leading to additional backwash requirements. For the purposes of this evaluation, duplex bag filter units are assumed to be included for the influent stream of all groundwater treatment systems.

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4.4 Treatment Technology Benefits and Challenges

Table 7 summarizes benefits and challenges for each of the PFAS and 1,4-dioxane treatment technologies considered in this study.

Table 7 Benefits and Challenges of Feasible Treatment Technologies

Treatment Technology Benefits Challenges

GAC Adsorption • Effective in removing PFAS.

• Well-established technology with multiple sources of media and equipment.

• Mechanically simple and low O&M requirements.

• Lower media unit costs compared to ion exchange resins.

• Relatively low power requirements to overcome additional headloss through contactors.

• Uncertainty in media replacement frequency must be addressed through testing and may vary over time.

• May be less effective in removing short-chain PFASs according to literature and full-scale operations.

• Periodic backwashing is typically required for removal of carbon fines, sediment produced by wells, and to reverse GAC bed compression during normal operation. Therefore, backwash supply and spent washwater management features are required.

UV AOP • Well-established technology currently utilized for full-scale 1,4-dioxane treatment.

• Local full-scale facility in operation.

• Primarily automated process operation.

• Peroxide chemical storage/feed system necessary.

• Peroxide does not readily absorb UV light, so the peroxide residual must be quenched for a free chlorine residual to be maintained in the distribution system.

• Peroxide scavenges hydroxyl radicals, which impacts the efficacy of the AOP.

4.5 Treatment Alternatives

Carollo identified three well sites as potential locations for PFAS, 1,4-dioxane, and TCE treatment facilities. Table 8 summarizes the treatment techniques evaluated at each well site.

Table 8 Treatment Alternatives Matrix

Location PFAS + 1,4-dioxane Treatment 1,4-dioxane

New site (Northern Cluster)

GAC Pressure Contactors UV-H2O2 AOP

Z-013A (Central Cluster)

GAC Pressure Contactors UV-H2O2 AOP

A-057B (Southern Cluster)

Blending Blending

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5.0 Evaluation of Alternatives

The following sections review the recommended treatment alternatives for the NW area production well sites. The following sections include conceptual design criteria, simplified process schematics, conceptual site layouts, and conceptual cost estimates at each cluster.

5.1 Conceptual Design Criteria

All the wells under consideration were grouped to form a cluster based upon their geospatial location, and each cluster was evaluated for centralized well treatment for removal of the targeted contaminants. Due to the poor condition of some of the project wells shown in Table 5, Carollo evaluated the cost of adding onsite replacement wells (with existing flow capacity) at the sites with wells in “poor” condition and treatment facilities. Table 9 shows the assumed design capacities which forms the fundamental basis of process equipment sizing for alternative treatment systems.

Table 9 Design Capacities

Cluster Units Combined Design Capacity

Northern Cluster at New Site gpm 1,675

Central Cluster at Z-013A gpm 2,092

Southern Cluster at A-057B gpm 1,505

Table 10 shows conceptual design criteria assumed for GAC adsorption systems at the two well clusters. GAC treatment systems would be configured as lead/lag contactors in series to extend the empty bed contact time and overall carbon bed life.

Table 10 GAC Adsorption Conceptual Design Criteria

Parameter Units Northern Cluster at New Site Central Cluster at Well Z-013A

Configuration - Lead-lag series operation Lead-lag series operation

Number of treatment trains No. 2 3

Number of contactors per train

No. 2 2

No. of Contactors No. 4 6

Design Flow gpm 1,675 2,092

Design Flow/Train gpm 838 697

Design Liquid Loading Rate gpm/sf 7.4 6.2

Media size mesh 12 x 40 12 x 40

Carbon type Re-agglomerated bituminous coal-derived

Re-agglomerated bituminous coal-derived

Dry weight of carbon/ contactor lb 20,000 20,000

Carbon bed depth ft 5.9 5.9

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Parameter Units Northern Cluster at New Site Central Cluster at Well Z-013A

Empty Bed Contact Time

(EBCT)

min 6.0 7.2

Backwash flow rate per contactor @ approx. 30% bed expansion gpm 1,244 1,244

Backwash equalization tank active volume gal 18,661 18,661

Backwash equalization tank diameter ft 15.5 15.5

Table 11 shows the conceptual design criteria for the UV AOP system for 1,4-dioxane removal considered in this study.

Table 11 UV AOP System Conceptual Design Criteria

Parameter Units Northern Cluster at New Site

Central Cluster at Well Z-013A

Design Capacity gpm 1,675 2,092

Target Contaminant -- 1,4-dioxane 1,4-dioxane

Log Reduction -- 1.25 1.25

Lamp Fouling Factor -- 0.9 0.9

UVT % 97 97

Reactor Model -- TrojanUVFlex™48SL TrojanUVFlex™48SL

Number of Duty Trains -- 1 1

Flow per Train gpm 1,675 2,092

Reactors per Train -- 1 1

Number of Lamps per Train -- 96 96

Lamp Technology -- LPHO LPHO

Flange Connection Size in 24 24

Peroxide Dose ppm 7.9 9.2

Peroxide Concentration % 35% 35%

Peroxide 30-day Storage gallons 3,000 3,000

5.2 Simplified Process Schematics

Simplified process schematics in Appendix B show the treatment strategies considered for the three NW area well site clusters evaluated. The simplified process schematics shows UV AOP in series with GAC contactors as lead/lag vessel systems.

5.3 Conceptual Site Layouts

Appendix C shows example conceptual centralized wellhead treatment layouts for each cluster at different sites: Northern at New Site, Central at Z-013A, and Southern at A-057B. The illustrated treatment systems include solids pretreatment using desanders and bag filters, UV AOP, and GAC contactors based on site-specific requirements. The Northern and Central

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | 16

cluster site layouts also show a backwash waste equalization tank used for settling carbon fines and solids from periodic GAC contactor backwashing. The Southern cluster shows the blending reservoir.

5.4 Conceptual Replacement Well and Treatment Cost Opinions

Carollo developed conceptual-level capital and annual operations and maintenance cost opinions for the blending and treatment alternatives. The cost opinion tables appear in Appendix D. Tucson Water provided costs for well drilling and equipping in the 2018 Tucson Water technical memorandum Cost Estimate to Replace Potable Production Lost due to PFAS Detections.

The capital cost opinions are expressed in July 2020 dollars (corresponding 20-Cities Average Engineering News Record Construction Cost Index = 11,439). Cost opinions are consistent with Class 4 Estimates as defined by the Association for the Advancement of Cost Engineering (AACE) International. This level of engineering cost estimating is generally made with limited information, including process block diagrams, preliminary equipment lists, and conceptual layouts. Typical accuracy for Class 4 Estimates is expected to be in the range of -30 to +50 percent.

The cost opinions do not include any costs for adding additional Supervisory Control and Data Acquisition (SCADA)/communications equipment. Tucson Water would coordinate alignment of SCADA/communications hardware and software at sites as part of any treatment facility implementation.

5.5 Economic Analysis of Cost Opinions

Carollo prepared economic analyses for all treatment alternatives evaluated. These values represent the sum of capital cost opinions and the present worth of annual operations and maintenance cost projections, assuming a discount rate of 4 percent and term of 20 years.

Table 12 shows the economic analysis for all conceptual-level costs. Figure 6 shows a comparison of capital costs, annual operations and maintenance costs, total present worth, and equivalent annual and unit treatment costs for all treatment alternatives.

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | 17

Table 12 Conceptual Centralized Wellhead 1,4-dioxane and PFAS Treatment Cost Opinions

Cost Opinions Southern Cluster at

Well A-057B Site Blending Only

Central Cluster at Well Z-013A Site GAC Adsorption

Northern Cluster at New Site

GAC Adsorption

Capital cost $12,250,000 $21,150,000 $13,850,000

Annual O&M cost $80,000 $690,000 $630,000

Present Worth

Present worth of annual O&M (1) $1,087,000 $9,377,000 $8,562,000

Total present worth $13,340,000 $30,530,000 $22,410,000

Equivalent Annual and Unit Treatment Cost

Annualized capital cost (1) $902,000 $1,557,000 $1,020,000

Total equivalent annual cost $982,000 $2,247,000 $1,650,000

Cost per 1,000 gallons treated $1.24 $2.84 $2.09

Notes:

(1) Assuming a discount rate of 4% annually and a term of 20 years.

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | 18

Figure 6 Centralized Wellhead 1,4-dioxane and PFAS Treatment Conceptual Cost Opinion

$12.25

$21.15

$13.85

$0.08 $0.69 $0.63

$13.34

$30.53

$22.41

$0

$5

$10

$15

$20

$25

$30

$35

Well A-057B Site- Blending Well Z-013A Site - UV AOP + GAC Adsorption

New Site - UV AOP + GAC Adsorption

Co st

M ill io ns

Capital Cost Annual O&M Cost Present Worth

Southern Cluster Central Cluster Northern Cluster

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | 19

6.0 Summary

1. EPA has published Drinking Water Health Advisories for PFOA/PFOS (combined) at

70 ppt and for 1,4-dioxane at 0.35 ppb. EPA has an MCL of 5 µg/L for TCE. While Drinking Water Health Advisories are not enforceable standards, they represent EPA’s recommendations for public water systems and will be taken under consideration in any forthcoming EPA rulemaking that may result in enforceable MCLs.

2. Tucson Water removed nine wells in the NW area from service due to detections of PFAS, 1,4-dioxane, and TCE. All the wells with PFAS detections have been taken out of service:

a. Wells Z-002A on March 9, 2016,

b. Wells Z-014B and Y-001B on September 22, 2016,

c. Wells Z-005A, Z-015A and Z-013A on September 19, 2016,

d. Wells A-053A and A-057B on July 18, 2018.

3. Wells Y-004A, Y-001B, Z-013A, Z-014B, Z-015A, A-053A, A-057B, Z-002A and Z-005A would require water quality improvements to meet Tucson Water’s potable water system operational targets for PFAS, 1-4 dioxane, and TCE (or for alternate end uses).

4. The nine wells were grouped into three clusters for centralized well treatment: Northern (Y-004A and Y-001B), Central (Z-013A, Z-014B and Z-015A) and Southern (A-053A, A-057B, Z-002A and Z-005A) clusters. The clustering was based upon geographic location of these wells and feasibility of centralized well treatment.

5. The southern cluster wells can meet Tucson Water operation targets for all PFAS, 1,4-dioxane, and TCE by blending while the Northern and Central cluster wells don’t meet the operational target for both PFAS and 1,4-dioxane after blending.

6. Effective treatment technologies are available to reduce PFAS and 1,4-dioxane concentrations to reliably meet Tucson Water’s operational targets. UV AOP and GAC are well-established and demonstrated for municipal water treatment.

7. Centralized well treatment for each cluster was evaluated at different sites: Northern at New Site, Central at Z-013A, and Southern at A-057B. All three well sites studied can accommodate the full range of treatment facility alternatives evaluated in this study.

8. Wells Z-013A, Z-015A, A-053A, Z-002A and Z-005A are on the order of 20-80 years old and in poor condition, indicating the need for replacement wells to re-activate sustained pumping activities at the sites. Replacement wells would have same design capacity as the current wells.

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020

Appendix A

HISTORICAL WATER QUALITY DATA

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-1

Table A1 Historical 1,4-dioxane and PFAS Water Quality Data

Parameter Sample Date Units A-053A A-057B Y-001B Y-004A Z-002A Z-005A Z-013A Z-014B Z-015A

1,4-Dioxane(1) 10/17/13 ppb <0.1

07/25/16 ppb 0.17 0.4

07/26/16 ppb <0.1 <0.1

09/06/16 ppb <0.1 0.18 1.63 <0.1 0.75 12/08/16 ppb 0.84 0.91

12/15/16 ppb <0.1

02/27/17 ppb 0.86 0.89 0.23

02/28/17 ppb 1.76 0.12 0.57 05/08/17 ppb 0.72

05/09/17 ppb <0.1

06/21/17 ppb 0.21

09/18/17 ppb 0.79 0.74 <0.1

12/27/17 ppb 0.73 0.78

12/28/17 ppb <0.1

03/05/18 ppb 0.79 0.82

03/06/18 ppb 0.19 <0.1

05/16/18 ppb 0.7 0.73

05/17/18 ppb <0.1

07/17/18 ppb 0.7 0.68 1.41

07/18/18 ppb 0.36 07/31/18 ppb <0.1

10/15/18 ppb 0.66 0.71 1.26

10/16/18 ppb <0.1 0.32 10/30/18 ppb <0.1

PFOS(2) 07/29/13 ppt 66 140

10/17/13 ppt <2

07/17/14 ppt 66 78

07/30/15 ppt 11 9.2 15

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FINAL | DECEMBER 2020 | A-2

Parameter Sample Date Units A-053A A-057B Y-001B Y-004A Z-002A Z-005A Z-013A Z-014B Z-015A 07/26/16 ppt 3.2 30 97 07/27/16 ppt 78 83 150

12/08/16 ppt 76 65

12/15/16 ppt 95 5.5 72 02/27/17 ppt 72 61 <2

02/28/17 ppt 96 7.9 78 05/08/17 ppt 51 100

05/09/17 ppt 4.2 75 06/21/17 ppt <2

07/18/17 ppt 100 76 150

09/18/17 ppt 74 55 4.4

09/19/17 ppt 96 68 10/05/17 ppt 5.9 10

12/27/17 ppt 72 25 97

12/28/17 ppt 3 64 03/05/18 ppt 75 60 110

03/06/18 ppt <2 3.6 74 05/16/18 ppt 76 51 100

05/17/18 ppt <2 70 07/17/18 ppt 58 36 72

07/18/18 ppt 68 07/31/18 ppt <2

10/15/18 ppt 90 63 120

10/16/18 ppt <2 78 10/30/18 ppt <2

03/06/19 ppt <2 15

PFOA(2) 07/29/13 ppt 13 16

10/17/13 ppt <2

07/17/14 ppt 9.4 12

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FINAL | DECEMBER 2020 | A-3

Parameter Sample Date Units A-053A A-057B Y-001B Y-004A Z-002A Z-005A Z-013A Z-014B Z-015A 07/30/15 ppt <2 <2 <2

07/26/16 ppt <2 2.8 12 07/27/16 ppt 19 21 28

12/08/16 ppt 15 15

12/15/16 ppt 22 <2 12 02/27/17 ppt 14 17 <2

02/28/17 ppt 22 <2 13 05/08/17 ppt 15 19

05/09/17 ppt <2 13 06/21/17 ppt <2

07/18/17 ppt 24 24 30

09/18/17 ppt 15 15 <2

09/19/17 ppt 19 12 10/05/17 ppt <2 <2

12/27/17 ppt 13 15 21

12/28/17 ppt <2 10 03/05/18 ppt 17 20 26

03/06/18 ppt <2 <2 14 05/16/18 ppt 17 20 28

05/17/18 ppt <2 15 07/17/18 ppt 16 18 26

07/18/18 ppt 14 07/31/18 ppt <2

10/15/18 ppt 18 19 28

10/16/18 ppt <2 15 10/30/18 ppt <2

PFHxS(2) 07/29/13 ppt 41 53

10/17/13 ppt <2

07/17/14 ppt 25 32

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FINAL | DECEMBER 2020 | A-4

Parameter Sample Date Units A-053A A-057B Y-001B Y-004A Z-002A Z-005A Z-013A Z-014B Z-015A 07/30/15 ppt 7.6 6.6 11

07/27/16 ppt 53 58 70

07/18/17 ppt 63 37 61

07/17/18 ppt 56 38 66

07/31/18 ppt <2

10/15/18 ppt 58 32 60

10/16/18 ppt <2 110 10/30/18 ppt <2

03/06/19 ppt 4 9.5

PFHpA(2) 07/29/13 ppt <2 <2

10/17/13 ppt <2

07/17/14 ppt <2 5

07/30/15 ppt <2 <2 <2

07/27/16 ppt 7.6 5.9 13

07/18/17 ppt 5.7 5.9 8.3

07/17/18 ppt 6.1 5.4 7.5

07/31/18 ppt <2

10/15/18 ppt 5.3 4.4 7.6

10/16/18 ppt <2 5 10/30/18 ppt <2

03/06/19 ppt <2 <2

PFHxA(2) 07/29/13 ppt 8.1 12

07/17/14 ppt <2 <2

07/30/15 ppt <2 <2 <2

07/27/16 ppt 18 14 16

07/18/17 ppt 13 13 14

07/17/18 ppt 11 15 13

10/15/18 ppt <2

10/15/18 ppt 11 11 13

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FINAL | DECEMBER 2020 | A-5

Parameter Sample Date Units A-053A A-057B Y-001B Y-004A Z-002A Z-005A Z-013A Z-014B Z-015A 10/16/18 ppt <2 13 03/06/19 ppt <2

03/06/19 ppt <2 <2

PFBS(2) 07/29/13 ppt 5.3 7.7

10/17/13 ppt <2

07/17/14 ppt <2 <2

07/30/15 ppt <2 <2 <2

07/27/16 ppt 11 6.3 35

07/18/17 ppt 7.5 8.3 9.7

07/17/18 ppt 5.1 7.2 7.5

07/31/18 ppt <2

10/15/18 ppt 5.6 7.6 9

10/16/18 ppt <2 7.7

10/30/18 ppt <2

03/06/19 ppt <2 3.1 Notes:

(1) MRL for 1,4-dioxane is 0.1 ppb.

(2) MRL for PFAS is 2 ppt.

Abbreviations:

PFOA = perfluorooctanoic acid PFOS = perfluorooctanesulfonic acid PFHxS = perfluorohexanesulfonic acid PFHpA = perfluoroheptanesulfonic aid PFHxA = perfluorohexanoic acid PFBS = perfluorobutanesulfonic acid MRL = Method Reporting Limit

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-6

Figure A1 PFAS Speciation at Well Y-001B

Figure A2 PFAS Speciation at Well Y-004A

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-7

Figure A3 PFAS Speciation at Well Z-013A

Figure A4 PFAS Speciation at Well Z-014B

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

Method Reporting Limit (MRL) = 2 ppt

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-8

Figure A5 PFAS Speciation at Well Z-015A

Figure A6 PFAS Speciation at Well A-053A

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

Method Reporting Limit (MRL) = 2 ppt

10/17/2013 10/5/2017 3/6/2019

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-9

Figure A7 PFAS Speciation at Well A-057B

Figure A8 PFAS Speciation at Well Z-002A

10/5/2017 3/6/2019

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

MRL

Method Reporting Limit (MRL) = 2 ppt

10/30/2018 10/30/2018

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

FINAL | DECEMBER 2020 | A-10

Figure A9 PFAS Speciation at Well Z-005A

7/26/2016 2/27/2017 6/21/2017 3/6/2018

C o n ce n tr at io n (p p t)

Date Sampled

PFBS

PFHxA

PFHxS

PFHpA

PFOA

PFOS

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

Appendix B

SIMPLIFIED PROCESS SCHEMATIC

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FINAL | DECEMBER 2020 | B-1

Figure B1 UV AOP and GAC Process Flow Diagram

NORTHWEST AREA WELLS ALTERNATIVES EVALUATION | IMPACTS OF TARGETED EMERGING CONTAMINANTS | TUCSON WATER

Appendix C

CONCEPTUAL SITE LAYOUTS

This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map are subject to Pima County's ITD GIS disclaimer and use restrictions.

Notes:

Legend

2550 0

Feet 12/2020 dswartzendruber PolyLine dswartzendruber PolyLine dswartzendruber Callout

PROPERTY BOUNDARY

dswartzendruber Callout

EXISTING WALL

dswartzendruber Polygon dswartzendruber Callout

EXISTING WELL PUMP

dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Callout

EXISTING GATE

dswartzendruber Angle dswartzendruber Angle dswartzendruber Rectangle dswartzendruber Text Box

TO DISTRIBUTION SYSTEM

dswartzendruber Arrow dswartzendruber Text Box

FROM WELL SITES Z-005A & Z-002A

dswartzendruber Text Box

FROM WELL SITE A-053A

dswartzendruber Arrow dswartzendruber Arrow dswartzendruber Line dswartzendruber Line dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Polygon dswartzendruber Line dswartzendruber Line dswartzendruber Text Box Parcels

Blending Reservoir

New Raw Water Pipeline

Blended Water dswartzendruber Ellipse dswartzendruber Rectangle dswartzendruber Text Box A-057B Blending dswartzendruber Line dswartzendruber Line dswartzendruber PolyLine dswartzendruber Image dswartzendruber Rectangle dswartzendruber Text Box

W RIVER ROAD

dswartzendruber Rectangle dswartzendruber Ellipse dswartzendruber Callout

HYDRO PNUEMATIC TANK

dswartzendruber Callout

68,000 GAL BLENDING RESERVOIR

(Dia = 25 ft) (H = 18.5 ft) kvenkatesh Callout

BAG FILTER

kvenkatesh Callout

12-FT DIAMETER GAC CONTACTOR (4)

kvenkatesh Line kvenkatesh Text Box

FROM WELL SITE Y-004A

kvenkatesh Text Box

FROM WELL SITE Y-001B

kvenkatesh Arrow kvenkatesh Arrow kvenkatesh Rectangle kvenkatesh Arrow kvenkatesh Callout

BACKWASH SUPPLY

kvenkatesh Rectangle kvenkatesh Arrow kvenkatesh Text Box

TO DISTRIBUTION SYSTEM

kvenkatesh Image kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Oval kvenkatesh Oval kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Oval kvenkatesh Oval kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Text Box

UVAOP TREATMENT BUILDING

kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Ellipse kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Callout

DESANDER

kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Text Box

10' X 73' TRAILER + TRUCK

kvenkatesh Rectangle kvenkatesh Callout

TREATED WATER

kvenkatesh Rectangle kvenkatesh Ellipse kvenkatesh Rectangle kvenkatesh Arrow kvenkatesh Callout

22,000 GAL BACKWASH TANK

(Dia = 16 ft) (H = 15 ft) kvenkatesh Rectangle kvenkatesh Line kvenkatesh Callout

BACKWASH RECYCLE PUMPS

kvenkatesh Callout

BACKWASH RECYCLE

kvenkatesh Text Box kvenkatesh Line kvenkatesh

SUBMERSIBLE

kvenkatesh Ellipse kvenkatesh Line kvenkatesh Line kvenkatesh Line kvenkatesh

SUBMERSIBLE

kvenkatesh Ellipse kvenkatesh Line kvenkatesh Line kvenkatesh Line kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Line kvenkatesh Line kvenkatesh Line kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Line kvenkatesh Rectangle kvenkatesh Text Box

BACKWASH WASTE TO SANITARY SEWER

kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle kvenkatesh Line kvenkatesh Rectangle kvenkatesh Text Box Scale: 2 in = 100 ft (approx.)

kvenkatesh Text Box

NORTH CLUSTER

UV AOP + GAC LEAD/LAG

kvenkatesh Text Box 12/2020 kvenkatesh Arc kvenkatesh Arc kvenkatesh Rectangle kvenkatesh Rectangle

This map is a user generated static output from an Internet mapping site and is for reference only. Data layers that appear on this map are subject to Pima County's ITD GIS disclaimer and use restrictions.

Notes:

Legend

2550 0

Feet 12/2020 dswartzendruber Callout PROPERTY BOUNDARY and PROPOSED NEW FENCE dswartzendruber Callout

EXISTING WELL PUMP

dswartzendruber Rectangle dswartzendruber Arrow dswartzendruber Callout

BACKWASH SUPPLY

dswartzendruber Rectangle dswartzendruber Arrow dswartzendruber Text Box

TO DISTRIBUTION SYSTEM

dswartzendruber Image dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Oval dswartzendruber Oval dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Oval dswartzendruber Oval dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Oval dswartzendruber Oval dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Text Box

UVAOP TREATMENT BUILDING

dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Ellipse dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Callout

BAG FILTER

dswartzendruber Callout

DESANDER

dswartzendruber Ellipse dswartzendruber Callout

RELOCATE?

dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Callout

12-FT DIAMETER GAC CONTACTOR (6)

dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Line dswartzendruber Line dswartzendruber Callout

EXISTING FENCE

dswartzendruber Line dswartzendruber Text Box

10' X 73' TRAILER + TRUCK

dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Callout

TREATED WATER

dswartzendruber Text Box

FROM WELL SITES Z-014B &Z-015A

dswartzendruber Line dswartzendruber Arrow dswartzendruber Rectangle dswartzendruber Ellipse dswartzendruber Rectangle dswartzendruber Arrow dswartzendruber Text Box

BACKWASH WASTE TO SANITARY SEWER

dswartzendruber Callout

22,000 GAL BACKWASH TANK

(Dia = 16 ft) (H = 15 ft) dswartzendruber Rectangle dswartzendruber Line dswartzendruber Callout

BACKWASH RECYCLE PUMPS

dswartzendruber Callout

BACKWASH RECYCLE

dswartzendruber Text Box dswartzendruber Line dswartzendruber

SUBMERSIBLE

dswartzendruber Ellipse dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber

SUBMERSIBLE

dswartzendruber Ellipse dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber Arc dswartzendruber Arc dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Rectangle dswartzendruber Line dswartzendruber Angle dswartzendruber Angle dswartzendruber Callout

EXISTING GATE

dswartzendruber Angle dswartzendruber Angle dswartzendruber Callout

EXISTING GATE

dswartzendruber Line dswartzendruber Line dswartzendruber Callout

NEW GATE

dswartzendruber Angle dswartzendruber Angle dswartzendruber Text Box

Z-013A UV AOP + GAC LEAD/LAG

dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber Line dswartzendruber Text Box Parcels

GAC Pressure Contactor Footprint

UVAOP Building

Bag Filter Footprint

Desanders

GAC Backwash Tank

New Raw Water Pipeline

GAC Contacted Water

GAC Backwash

Backwash Recycle dswartzendruber Rectangle dswartzendruber Ellipse dswartzendruber Rectangle dswartzendruber Ellipse dswartzendruber Ellipse dswartzendruber Image dswartzendruber Rectangle dswartzendruber Text Box

INA RD

dswartzendruber Callout

HYDROPNEUMATIC TANK

dswartzendruber Rectangle…