Stantec_Attachment_L_-_Method_of_Approach (2).pdf

Request for Proposal

Solicitation No. BPM005664 Advanced Water Purification Technical Support

Arizona Department of Environmental Quality - Procurement Office

1110 W. Washington St.

Phoenix, AZ 85007

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

Attachment L – Method of Approach

The Offeror shall provide a narrative response to each section that demonstrates their understanding of the Scope of Work requirements and describes the company’s overall method of approach for providing the Service(s) stated in this Solicitation.

Responses for each question shall not exceed two (2) pages in length with size ten (10) font.

Offeror shall provide a response either after each section or in a separate document entitled: “Attachment L - Method of Approach.” If a separate document is used, please clearly designate each section and double-check to ensure that each question has been answered. If any information provided is considered CONFIDENTIAL by Offeror, the information must be specifically included in the Confidential Information Designation Attachment and related documentation to be assessed for confidential treatment under A.A.C. R2-7-103.

1. Explain how to establish the minimum number of diverse mechanisms that are needed to control pathogens without being prescriptive of the technology.

2. Explain how to establish the number of diverse mechanisms that are needed to control chemicals without being prescriptive of the technology.

3. What are the minimum number of barriers needed to control pathogens without being prescriptive of the technology?

Provide rationale for the choice.

4. What are the minimum number of barriers needed to control chemicals without being prescriptive of the technology?

Provide rationale for the choice.

5. Describe the challenges if any associated with assigning credits to a WWTP via sampling of the treated wastewater and how that can be addressed.

6. Provide a table of content for an Operations and Maintenance Manual for an Advanced Water Purification System.

7. Describe how you would approach Enhanced Source Control for an AWP project.

8. How should failure response be managed in a direct to distribution and in raw water augmentation project?

9. Describe how you would approach the Operator Certification requirements for the AWP program.

10. Describe what AOP addresses and why it is necessary in an AWP project. Address what is enough AOP.

11. Describe how low molecular weight compounds should be addressed in a carbon train an in an RO train within an AWP project.

Request for Proposal

Solicitation No. BPM005664 Advanced Water Purification Technical Support

Arizona Department of Environmental Quality - Procurement Office

1110 W. Washington St.

Phoenix, AZ 85007

Solicitation Attachment – Method of Approach | Revision No. 1 | Revised 11-22

12. What is enough treatment for ozone/BAC and should it be required as part of RO trains? Explain why or why not.

Attachment L - Method of Approach

ADEQ is leading the State of Arizona into a new era of water resource management following the revision of Reclaimed Water Rules in 2018.

Members of our team, Rob McCandless and Sandeep Sathyamoorthy, were honored to be part of the Technical Advisory Group working closely with ADEQ staff to develop recommendations for Advanced Water Purification Facilities (AWPFs). Now, our team is excited to continue collaborating with ADEQ staff through the State’s AWPF program.

Our team members have extensive experience in potable reuse research and design projects. We provide comprehensive support for the testing, operation, and optimization of demonstration facilities, as well as guidance in the design, startup, and ongoing operations of full-scale potable reuse facilities around the world. We are confident that our team brings world-class expertise and experience to support ADEQ.

We have provided detailed responses to each of the twelve questions posed by ADEQ staff in this attachment. These critical questions posed by ADEQ staff highlight the seven key areas germane to successful implementation of potable reuse projects. Our experience highlights our ability to support ADEQ to successfully build efficacious potable reuse programs across the state.

1. Source Water Management, Monitoring and Control

A robust and enhanced source control program is an essential part of a multi-barrier integrated risk management strategy for potable reuse implementation. Our team members have been involved in the evaluation and implementation of source monitoring and control planning in California and Singapore.

2. AWPF Process Configurations, Multi-barrier, Multiple mechanisms approach

As potable reuse implementation grows in Arizona, the flavors of process flowsheets, unit operations employed, and configurations will continue to expand. Our team has worked on a range of RO-based and non-RO based potable reuse facilities across the globe and can support ADEQ in carefully and methodically evaluating projects.

3. Removal of Pathogens The acute risks posed by pathogen breakthrough is of paramount consideration in potable reuse implementation. Our team has worked on evaluating pathogen log removal values (LRVs) in potable reuse pilots and worked with regulators across the globe to establish and validate pathogen LRVs in full-scale AWPFs.

4. Elimination of Chemical Constituents In concert with pathogen removal, the attenuation, and destruction of chemical constituents, particularly smaller molecules, which are often poorly removed across AWPF unit operations, require particular attention in potable reuse.

5. AWPF Operations and Maintenance Requirements and Certification

Operator certification requirements have been an important aspect of the evolving potable reuse landscape in California, Georgia, and Colorado.

Our professionals have been engaged in projects implemented prior to the formalization of these frameworks and have the expertise to support ADEQ in developing the requirements.

6. O&M and Contingency Planning Our experience strongly motivates collaboration between the utility and the regulators around O&M and contingency planning. It is essential that there is sufficient regulatory oversight around the O&M strategies and contingency plans to ensure that no water that is not purified to the target level enters the water distribution system.

7. Technical, Managerial and Financial Capacity

In addition to technical requirements essential for successful potable reuse implementation, it is important that all agencies involved in the implementation of a potable reuse project (from source management to water distribution) have the TFM capability to implement the program. At Stantec, we have a team of experts dedicated to supporting public agencies’ capital, applied technology, and operations expenditure planning.

Our unique value for ADEQ is highlighted in our ability to bring this team of financial experts in concert with our world-class technical expertise.

Question 1: Explain how to establish the minimum number of diverse mechanisms needed to control pathogens without being prescriptive of the technology.

Introduction to Pathogen Control

To safeguard against the transmission of pathogens in drinking water derived from advanced water purification (AWP) and direct potable reuse (DPR), it is imperative to establish precise criteria for removing or inactivating microorganisms during the treatment process. Pathogen control approaches include:

Log reduction values: a factor of 10 reduction in concentration for a microorganism or a contaminant1.

Treatment mechanisms: can encompass physical, biological, or chemical actions aimed at reducing the concentration of pathogens or chemicals2.

Critical control points: a treatment barrier that can be controlled and monitored such that log reduction values are correlated with treatment performance3.

Given the diversity of the characteristics of pathogenic organisms (e.g., size, hydrophobicity/philicity, surface charge), employing a range of treatment mechanisms is essential to achieve comprehensive protection against pathogens breakthrough. The regulatory framework must balance providing safe and reliable finished water to ensure public protection and promote DPR without being prescriptive of the specific technology employed for treatment. Successful implementation of AWP programs and projects necessitates flexibility to adapt to the water quality conditions of an individual utility and leverage existing assets.

Prescribed Technology vs Minimum Number of Mechanisms

Pathogen control through prescribed technology simplifies regulatory compliance and consistently ensures pathogen removal rates across all facilities. This approach streamlines the facility design and reduces the amount of equipment that operators must be proficient in maintaining and operating. The issue for many states is that with the prescribed technology approach, the regulations become rigid and incapable of flexibility for site-specific challenges. This approach may cause multiple revisions to the regulations as new treatment technology emerges. The regulations are less adaptive to changing conditions and emerging challenges.

Controlling pathogens by establishing a minimum number of diverse treatment mechanisms creates flexibility in selecting treatment mechanisms based on the specific characteristics of the water source and pathogen profile. This approach does not require the use of specific technologies but rather directs how desired water quality and pathogen goals are achieved. Similar to the way that existing wastewater treatment facilities and drinking water treatment facilities are allowed to select the best available control technologies or leverage treatment techniques for maintaining compliance with pathogen removal, an AWP can achieve a suitable endpoint by various means with adequate guidance on cumulative treatment across the purified water lifecycle. Although beneficial for public utilities, this approach creates a heavier workload for the regulators if they were to review and approve site-specific mechanisms.

Examples from Other States

Specific regulations and requirements for reuse programs can vary from state to state. Some states have more flexible approaches with minimum treatment mechanisms, while others prescribe specific technologies. California’s draft DPR regulations are centered around prescribed treatment sequences, similar to their existing indirect potable reuse (IPR) regulations, which include full-flow reverse osmosis (RO) treatment units. This approach is advantageous since most California (CA) cities are coastal, offering brine waste disposal into the ocean. Texas (TX), acknowledging its geographical diversity within the state, implemented a more adaptable approach in its DPR guidelines/framework by incorporating minimum treatment mechanisms. Most recently, Colorado’s (CO) final DPR regulations adhere to either prescribed treatment methods or minimum treatment requirements. This dual approach promotes project consistency while accommodating the geographical and climate diversity that characterizes the state.

Table 1: Examples of minimum treatment mechanisms

State Application Rules Minimum Treatment Mechanisms

Prescribed Technology

CA DPR DRAFT X

CO DPR Final X X TX DPR Framework/Guidelines X

Recommendation for ADEQ

In summary, having an established number of diverse treatment mechanisms prioritizes achieving water quality and pathogen control goals while allowing for customization and adaptability. Determining the number of diverse treatment mechanisms required for pathogen control in DPR involves a basis for the water sources' pathogen profile, conducting risk assessments, and employing a combination of treatment processes proven effective against the identified pathogens. Requiring diversity of treatment mechanisms provides robustness of the entire process to address multiple pathogens. Each treatment barrier for pathogen control must provide not less than 0.5 log reduction or inactivation and may not be granted more than 6 log reduction or inactivation.5 By following these steps, an effective pathogen control strategy for DPR can be established without prescribing specific technologies.

References

1. ADEQ AWP: Technical Advisory Group. 2023. “Advanced Water Purification (AWP): Technical Advisory Group (TAG) Recommendations”

2. SWRCB. 2021. “A Proposed Framework of Regulating Direct Potable Reuse in California Addendum.Version 8-17-2021. DPR Framework 2nd Edition Addendum - Early Draft of Anticipated Criteria for Direct Potable Reuse.”

3. Tchobanoglous et al. 2015. “Framework for Direct Potable Reuse.”

4. SWRCB. 2019. “A PROPOSED FRAMEWORK FOR REGULATING DIRECT POTABLE REUSE

IN CALIFORNIA.”

https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/direct _potable_reuse/dprframewkseced.pdf.

5. WRF 11-02-01. 2013. “Examining Criteria for Direct Potable Reuse.”

Question 2: Explain how to establish the number of diverse mechanisms needed to control chemicals without being prescriptive of the technology.

Introduction to Chemical Control

To protect against chemical contaminants in drinking water derived from direct potable reuse (DPR), it is imperative to establish detailed criteria for the removal of monitored chemicals during the treatment process. Chemical control approaches include types of treatment mechanisms and the number of treatment barriers.

Treatment mechanisms: can encompass physical, biological, or chemical actions aimed at reducing the concentration of pathogens or chemicals1.

Critical control points: a treatment barrier that can be controlled and monitored such that log reduction values are correlated with treatment performance2.

Given the large amount of monitored chemicals, employing a range of treatment mechanisms becomes essential to protect against chemical contaminants. A challenge when establishing requirements for chemical control is being rigid enough for public protection without being prescriptive of the technology.

Prescribed Technology vs Minimum Number of Mechanisms

Chemical control through prescribed technology simplifies regulatory compliance and consistently ensures chemical removal rates across all facilities. This approach streamlines the facility design and reduces the amount of equipment that operators must be proficient in maintaining and operating. The issue for many states is that with the prescribed technology approach the regulations become rigid and incapable of flexibility for site-specific challenges while resulting in overly conservative designs and thus more costly AWP projects. This approach may cause multiple revisions to the regulations as new treatment technology emerges. The regulations are less adaptive to changing conditions and emerging challenges because the goal is a sequence in lieu of a potable water quality standard.

Controlling chemicals through the establishment of a minimum number of diverse treatment mechanisms creates flexibility in selecting treatment mechanisms based on the specific characteristics of the water source and chemical type. This approach does not require the use of specific technologies but rather directs the route in which desired water quality and pathogen goals are achieved.

Examples from other states

Specific regulations and requirements for reuse programs can vary from state to state. Some states have more flexible approaches with minimum treatment mechanisms, while others prescribe specific technologies. California’s draft DPR regulations are centered around prescribed treatment sequences, similar to their existing indirect potable reuse (IPR) regulations, which include full-flow reverse osmosis (RO) treatment units. This approach is advantageous since most California (CA) cities are coastal, offering brine waste disposal into the ocean. CA also has prescribed ozone/BAC for chemical control but has left it open for agencies to use other processes if they can demonstrate equivalency (alternative clause). The draft DPR regulations prescribe certain desired removal of four different chemicals, that are known to have broken through IPR facilities. Texas (TX), acknowledging its geographical diversity within the state, implemented a more adaptable approach in its DPR guidelines/framework by incorporating minimum treatment mechanisms. Most recently, Colorado’s (CO) final DPR regulations adhere to either prescribed treatment methods or minimum treatment requirements. This dual approach promotes project consistency while accommodating the geographical and climate diversity that characterizes the state.

Table 2: Examples of minimum treatment mechanisms

State Application Rules Minimum Treatment

Mechanisms Prescribed Technology

CA DPR DRAFT X

CO DPR Final X X

TX DPR X

In summary, having an established number of diverse treatment mechanisms prioritizes achieving water quality and chemical control goals while allowing for customization and adaptability. Determining the number of diverse treatment mechanisms required for chemical control in DPR requires a thorough understanding of the risks posed by a very large array of chemicals, the occurrence and concentration of those chemicals, the properties of those chemicals, and employing a combination of treatment processes proven effective against the identified chemicals. By following these steps, an effective chemical control strategy for direct potable reuse can be established without prescribing specific technologies. In Arizona, where a wide range of potable water source supplies and chemistries exist, narrowing advanced water purification (AWP) to a prescriptive standard may inadvertently produce water that is not palatable without extensive reconditioning; this would also impact existing infrastructure (e.g., scouring) if AWP potable water is not well matched to existing supplies.

References

1. SWRCB. 2021. “A Proposed Framework of Regulating Direct Potable Reuse in California Addendum.Version 8-17-2021. DPR Framework 2nd Edition Addendum - Early Draft of Anticipated Criteria for Direct Potable Reuse.”

2. Tchobanoglous et al. 2015. “Framework for Direct Potable Reuse.”

3. SWRCB. 2019. “A PROPOSED FRAMEWORK FOR REGULATING DIRECT POTABLE REUSE

IN CALIFORNIA.”

https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/documents/direct _potable_reuse/dprframewkseced.pdf.

4. ADEQ AWP: Technical Advisory Group. 2023. “Advanced Water Purification (AWP): Technical Advisory Group (TAG) Recommendations”

5. WRF 11-02-01. 2013. “Examining Criteria for Direct Potable Reuse.”

Question 3: What are the minimum number of barriers (treatment units) needed to control pathogens without being prescriptive of the technology? Provide a rationale for the choice.

Approach to Establishing Pathogen Barriers

Pathogens are currently regulated based on best available control technologies in wastewater, through measurement of disinfectant contact time (or ultraviolet dose) in drinking water and log-removal credits per treatment unit for surface water supplies. Surrogates, such as turbidity, are used to provide online monitoring of water prior to distribution. Real-time in-line or online monitoring of pathogens is a growing area of technology innovation, however, there are no readily applicable technologies currently on the market. Indeed, our research team at Stantec is actively working with technology developers to evaluate some of these technologies at the pilot scale. Sanitary surveys are completed by public water systems to determine vulnerable areas within the water supply and distribution systems, and similar approaches could be implemented for advanced water purification (AWP) projects as a parallel effort to treatment unit barriers for pathogen control.

Existing pathogen regulations for potable water are the LT1ESWTR (Conventional), which requires fecal coliform density of <20/100mL or total coliform density <100/100mL of source water prior to the first point of disinfectant application. Many Arizona (AZ) water reclamation facility (WRF) discharge or recharge limits are currently permitted at or below these coliform metrics; which could, in theory, qualify them as viable source water for drinking water supply. However, the standards for protecting public health from any risks posed by drinking water purified through advanced water purification (AWP) are widely regarded to require more stringent pathogens. This is primarily due to the higher concentration of pathogenic microorganisms and more variable nature of wastewater effluent (AWPF feed water) compared to surface water supplies.

Sampling frequency for coliforms is dependent on system size, ranging between 1-5 samples/week on a recurring basis and a sample for each day filtered turbidity is more than 1 NTU. The LT1ESWTR requirements for pathogen log-removal (LRV) are 3-log for Giardia, 4-log virus inactivation, and 2-log cryptosporidium (watershed control) and turbidity below 5 NTU. A combination of treatment methods and disinfection contact time credits with proofing in the full-scale system are required to receive full credit for pathogen removal. These metrics were developed based on a 1/10,000 risk of illness based on the assumption of non-impaired water supply sources; wastewater effluent would qualify as an impaired water supply, justifying more rigorous treatment standards to protect public health. The AWP community has long held 12 (virus) / 10 (crypto) / 10 Giardia) as the minimum log10 removal criterion required to protect public health. The Technical Advisory Group for Arizona’s DPR rule framework has proposed 13/10/10 for the minimum log removal criterion for AWP facilities.

Treatment Barriers as a Means of Pathogen Control

Treatment barriers are meant to reduce risks and protect public health. The LRV numbers assume treatment from raw sewage to potable water, with a minimum cumulative LRV required to protect public health. This can be achieved through a combination of the wastewater treatment facility, the advanced water purification facility, and the drinking water treatment facility. Different technologies are effective at pathogen inactivation and control, as shown in the table below. To achieve a cumulative total of 13 / 10 / 10, a minimum of three barriers are required based on the currently accepted values for LRV for each process. If in the future, a process could be rated for greater than 6-log removal, a minimum of two barriers would then be required assuming the appropriate combination of technologies. For reference, California requires up to four barriers for pathogen control, Colorado requires three barriers for pathogen control, and Florida currently proposes two barriers as the minimum.

The quality and performance of individual barriers vary substantially, so the aggregate log reduction values (LRV) of the barriers are essential to evaluate in lieu of the number of barriers. Physical barriers (e.g., filtration or UV-D) and chemical barriers (chlorine or UV-AOP) for pathogen management vary in efficacy, and encouraging combinations of barriers while facilitating adequate redundancy and reliability should be considered to appropriately protect public health. The following table presents an example of log reduction values for typical AWP processes.

Technology Mechanism LRV (V/G/C) Ozone (O3) Oxidation 6 / 6 / 1 Granular media filtration Separation 1 / 2 / 2 Ultrafiltration/Microfiltration/Nanofiltration (UF/MF/NF) Separation 0 / 4 / 4 Ultraviolet Advanced Oxidation Process (UV-AOP) Photolysis & Oxidation 6 / 6 / 6 Ultraviolet Disinfection (UV-D), minimum dose 276 mJ/cm2 Photolysis 6 / 6 / 6

Reverse Osmosis (RO) Separation 2 / 2 / 2 Membrane Bioreactor (MBR) Predation, Adsorption and Separation 1 / 2.5 / 2.5

Chlorination Oxidation 4 / 0 / 0

References

1. ADEQ AWP: Technical Advisory Group. 2023. “Advanced Water Purification (AWP): Technical Advisory Group (TAG) Recommendations”

2. WRF 11-02-01. 2013. “Examining Criteria for Direct Potable Reuse.”

3. WRF 11-02-04. 2016. “Equivalency of Advanced Treatment Trains for Potable Reuse.”

Question 4: What are the minimum number of barriers needed to control chemicals without being prescriptive of the technology? Provide a rationale for the choice.

Approach to Establishing Barriers for Chemicals

An advanced water purification facility must be capable of controlling a wide array of inorganic and synthetic organic chemicals and radionuclides. The chemicals present in untreated and treated wastewater can include both regulated and unregulated chemicals.

Developing a treatment scheme to address such a wide array of chemicals must consider the capabilities (and limitations) of each unit process to remove or destroy a particular chemical or family of chemicals with similar properties. For example, reverse osmosis can remove a wide range of chemicals with a wide range of properties but does a poor job at removing low molecular weight, non-polar organic chemicals.

For this reason, an additional process is required as a barrier for these chemicals.

The number of barriers required depends on the capabilities of each process to adequately reduce chemical concentrations for the broad array of chemical types that occur in wastewater.

Barriers as a Means of Chemical Control

California has required up to three barriers for chemical control and Colorado requires two barriers for chemical control if reverse osmosis is part of the process. California’s 3 barriers for chemicals were driven by low molecular weight organic breakthrough at reverse osmosis and UV-AOP, both prescribed processes in IPR and DPR. The basis for California’s requirement was occurrence of acetone at Orange County's wastewater treatment (biodegradation) and advanced water treatment (filtration) when high concentrations were dumped into the sewer by an industrial discharger. Reverse osmosis and UV-AOP were not able to control the acetone spike; therefore, initiating the stipulation of three mechanisms.

Similar risks may not exist with all utilities; advanced water purification (AWP) for bedroom communities may not have the same risks as large municipalities with multiple industrial users. Dilution through attenuation of chemical spikes can be used in lieu of a third treatment mechanism for chemical spikes.

PFAS has been demonstrated to occur in many wastewaters even where none occurs in the drinking water source. PFAS have a wide range of properties but share one common trait in that they are quite recalcitrant and resistant to oxidation, photolysis, and biological transformation. Addressing PFAS requires either a separation process (reverse osmosis) or adsorption as best available demonstrated control technologies at the current time.

Barriers to chemical control vary in efficacy, and encouraging combinations of dissimilar barriers while facilitating adequate redundancy and reliability should be considered to appropriately protect public health while not being prescriptive in technology. The following table presents the treatment mechanisms of several treatment processes for chemical control commonly associated with AWPs.

Technology Mechanism Coagulant Flocculant and Sedimentation (CFS) Adsorption & Separation Ozone (O3) Oxidation Biologically Activated Filtration/Carbon (BAF/BAC) Biological transforma�on Granular Activated Carbon (GAC) Adsorption Ultraviolet Advanced Oxidation Process (UV-AOP) Photolysis & Oxidation Reverse Osmosis (RO) Separation

It is recommended that the Colorado framework be the basis for Arizona’s chemical control requirements with provisions for attenuation or dilution of chemical spikes such as low molecular weight organics. The standard should be for all AWPs to include advanced oxidation and either reverse osmosis or AOP and a combination of adsorption and another process approved by ADEQ.

1. ADEQ AWP: Technical Advisory Group. 2023. “Advanced Water Purification (AWP): Technical Advisory Group (TAG) Recommendations”

2. WRF 11-02-01. 2013. “Examining Criteria for Direct Potable Reuse.”

3. Code of Colorado Regulations, Department of Public Health and Environment, Water Quality

Control Commission, Regulation No. 11 Colorado Primary Drinking Water Regulations 11.14 Direct Potable Reuse Rule, 2022

Question 5: Describe the challenges if any associated with assigning credits to a WWTP via sampling of the treated wastewater and how that can be addressed.

Challenges Assigning Disinfection Credits to a WWTP

An ongoing debate surrounding direct potable reuse (DPR) disinfection credits is whether disinfection credits should be awarded at the wastewater treatment plant (WWTP) that supplies secondary or tertiary effluent to the advanced water treatment (AWT) facility. The primary challenge in assigning disinfection credits at WWTPs for DPR is the inherent flow variability at WWTPs, influenced by both diurnal and seasonal factors. WWTPs face the demanding task of treating varying inflows, sometimes unpredictable in composition and volume. To gain disinfection credits for DPR, operators must maintain specific operating parameters within a defined range, which is difficult.

This challenge is compounded by the limited credits awarded to conventional WWTPs, which can make the effort of establishing and adhering to such an operating envelope, often requiring extensive sampling and monitoring, seem unwarranted. The risk of operations falling outside this specified range further discourages the pursuit of these credits. Balancing the need for consistent water quality standards in DPR with the practical challenges posed by variable WWTP flows remains a critical issue in the industry.

Secondary challenges include:

- Pathogen Concentration Variability – Pathogen concentrations in wastewater can vary widely based on factors such as influent sources, weather conditions, and seasonality. This variability makes it challenging to consistently achieve and measure specific LRVs for pathogens1.

- Diverse Pathogen Types – Wastewater contains a range of pathogens, each with varying disinfection resistance. Some pathogens may require more extensive treatment, and quantifying log reduction values (LRVs) for this diverse microbial population is complicated2.

- Detection limits – precisely detecting low pathogen levels in treated effluent necessitates highly sensitive analytical techniques. Sampling and detection limits must be finely tuned to ensure accurate LRV measurements2. In practice, large volumes of effluent samples are filtered to capture microorganisms at detectable levels. This requires significant time, effort, and cost.

- Inadequate Monitoring and Sampling – Monitoring the effluent to determine LRVs requires frequent and precise sampling. Inadequate or inconsistent sampling can lead to inaccurate assessments of treatment effectiveness3.

- Lack of Correlation in Monitoring – there is limited documented evidence correlating effluent quality to parameters that can be monitored on typical WWTP effluents. Parameters typically monitored for WWTP effluents include turbidity and disinfectant residual.

- Laboratory Analysis Turnaround Time – The analytical methods used for determining microbiological constituents requires significantly longer time than would be useful for monitoring treatment performance in a DPR facility.

- Monitoring Frequency – Effective LRV assessment requires frequent and accurate sampling of treated effluent. Inadequate or inconsistent sampling can lead to misleading disinfection performance assessments3.

- Adverse Events and Upsets – WWTPs may face upsets, such as equipment malfunctions or power outages, which can affect the treatment process and compromise LRVs.

- Operator Expertise – Ensuring WWTP operators are well-trained and capable of consistently achieving specified LRVs is essential and challenging.

Addressing Challenges

To address the primary challenge of inherent flow variability in assigning disinfection credits at WWTPs for DPR, equalization basins can be used. By evenly distributing and storing influent wastewater flows, equalization tanks allow for more consistent and controlled treatment processes. This stability is vital for achieving reliable disinfection outcomes, as it enables the precise dosing of disinfectants and ensures the treatment conditions, such as contact time and chemical dosage, remain constant. The equalization of primary effluent over the plant influent with result in less maintenance and odor concerns.

Addressing secondary challenges requires a combination of analytical techniques not typically practiced for WW treatment rigorous monitoring and sampling protocols, consistent treatment performance, and well-trained operators.

References

1. WRF 04-12-01. 2009. “Collecting, Exploring, and Interpreting Microbiological Data Associated with Reclaimed Water Systems.”

2. WRF 4760. 2023. “Establishing Additional Log Reduction Credits for WWTPs.”

3. WRF 5047. 2023. “Pathogen Removal Credits for Wastewater Treatment: Guidance for Study

Plans and Reporting.”

4. WRF 4989. 2021. “Pathogen Monitoring in Untreated Wastewater.”

Question 6: Provide a table of contents for an Operations and Maintenance Manual for an Advanced Water Purification System.

The following outline is an example of an Operations and Maintenance Manual for an Advanced Water Purification System in California.

1. Introduction

a. Purpose

b. Organization of the Manual

c. Abbreviations, Acronyms, and Symbols

d. Acknowledgments

2. Regulatory Overview – IPR/DPR Requirements

3. Staffing Plan

4. Interagency agreements and communications plan

5. Facility Overview

a. Influent Characteristics and Effluent Water Quality Goals

b. Facility Description

c. Process Design Criteria

d. Process and Flow Control

6. Advanced Water Purification and Associated Process Equipment

a. Treatment Overview

b. Unit Operations (each below will have subsections of: Process Description and Objective, Process Components, Process Control Philosophy and Monitoring, Alarms and troubleshooting)

i. Influent Pump Station

ii. Fine Screens

iii. CFS

iv. Biological Reactors for Membrane Bioreactor

v. Membrane Systems for Membrane Bioreactor

vi. Micro and Ultrafiltration

vii. Reverse Osmosis System

viii. Ozone

ix. BAC

x. UV and UVAOP

xi. Chlorination

7. Critical Control Points

a. Filtrate Turbidity - MBR

b. Pressure Decay Test – Micro and Ultrafiltration, MBR

c. Online Conductivity and TOC monitoring - Reverse Osmosis

d. UVT, Dose and EED/RED - UV and UVAOP

e. Effluent TOC – BAC

f. Ozone/TOC ratio and Ozone residual - Ozone

g. Free or Total Chorine Residual – Chlorination

8. Ancillary Equipment

a. Chemical Dosing Systems

i. Chemicals

ii. Application

iii. Components

iv. Control Philosophy and Operating Setpoints

b. Auxiliary Systems

i. Compressed Air Systems

ii. Potable Water System

iii. Utility Water System

iv. Plant Drain Pump Station

9. Plant Control System

a. System Architecture

b. I&C System Description

c. System Security

10. Facility Interlocks and Critical Alarms

a. PLC Interlocks

b. Critical Alarms and Associated Corrective Actions

11. Electrical System and Operation and Control

12. Water Quality Monitoring

a. Sampling Locations and Online Analyzers

b. Critical Control Points

c. Reporting

13. Operations Building

a. Layout

b. Utilities

c. Safety

14. Facility Monitoring and Communications

a. Remote Dialer

b. Remote Monitoring and Control

c. Data Extraction

15. Emergency Response Plans

a. Emergency Assistance Information

b. Response to Spills

c. Response to Off-spec Water

d. Response to Power Failure

e. Response to Chemical Spills

f. Response to Overflow

g. Evacuation Plans and Procedure

16. Start-Up and Shutdown Procedures

17. Standard Operating Procedures

18. Membrane Cleaning Procedures and Storage

19. Equipment Maintenance Schedules

20. Chemical Product Safety Data Sheets

Question 7: Describe how you would approach Enhanced Source Control for an AWP project.

Introduction to Enhanced Source Control?

Enhanced source control is one of the critical risk mitigation components of an advanced water purification (AWP) project/program. The requirement for new water supplies and sources to complete “New Source Approval” testing which can range from a single comprehensive water quality sample during the development of a groundwater supply to a multi-year sampling campaign for surface water supplies is fundamental to the development of an AWP project, and in particular, requirements for enhanced source control. Though conventional water supply sources such as groundwater or surface water typically have reliable patterns, both related to flow or seasonality, the diversity of users in the water-shed is substantially higher, with different risk portfolios for each downstream AWP facility. As such, the approach for enhanced source control must be site-specific, with defined goals and required reporting of certain constituents but agile to adapt to both existing and future changes to the upstream source supplies and water quality regulations.

Protection of public health is the utmost priority for the execution of any water project, whether related to potable supply, reuse, or wastewater treatment.

Potable water supplies are regulated under the Clean Water Act (CWA), which is the “primary regulatory tool for protecting source water quality”, protecting public health through watershed-based source protection planning. The Safe Drinking Water Act (SDWA) requires an assessment of source water quality but does not mandate or prescribe “comprehensive source water protection”.

Protecting the AWP from damage or pass-through of contaminants is another priority objective of an enhanced source control program.

Existing Mechanisms to be Leveraged

Implementation of an enhanced source control program to manage compliance of upstream dischargers requires additional planning and compliance requirements but can leverage existing mechanisms to provide benefits both to the regulators and AWP project owners. Existing pre-treatment programs (regulated under Title 40 Part 403 under EPA’s National Pretreatment Program) for industrial (Categorical or Significant Industrial Users, 40 CFR 405-471) and commercial dischargers broadly target biological oxygen demand (BOD) or chemical oxygen demand (COD), total suspended solids (TSS), nutrients, fats oils and grease (FOG), with certain chemical constituents more deliberately limited based on the discharging entity. Individual utilities can develop pretreatment programs and more stringently regulate upstream dischargers; typically, pretreatment programs establish effluent limitations for pollutant concentrations, require best management practices or pretreatment requirements, detail requirements for sampling and reporting, and outline civil or criminal penalties for non-compliance.

Process compliance at the wastewater treatment facility is a critical component of an AWP-enhanced source control program. Improved understanding of effluent quality through longitudinal sampling to track both fluctuations and trends in effluent constituents is important to developing a “New Source” of potable water supply and developing a strategy to provide adequate treatment of all regulated constituents (National Primary Drinking Water Standards and additional as utilities deem appropriate).

Salient elements of a successful enhanced source control program (adapted from

WRF 13-12).

Industrial Outreach/

Coordination Multi-jurisdiction coordination

Monitoring

Enforcement

Legal Authority

Management

Public Outreach

Enhanced Source Control

Program Elements

Chemical Inventory Program Industrial monitoring Industry assistance Pretreatment & Spill management

Examples from Other States

Advanced water purification programs, whether for indirect or direct potable reuse, require enhanced source control programs. California, Colorado, and Florida (draft) specifically require enhanced source control programs, while Texas requires federal pretreatment standards with local limits. California requires quantitative risk assessment and third-party auditing on a five-year cycle, with online monitoring of surrogates (e.g., TOC); California also requires monthly sampling for maximum contaminant levels (MCLs), notification limit (NLs), toxics, and disinfection byproducts (DBP) precursors at the wastewater plant. Colorado requires annual reporting and a three-year cycle of updates to enhance the source program along with requiring minimum secondary treatment for wastewater and continuous monitoring of ammonia, conductivity, pH, turbidity, and total organic carbon (TOC) with periodic monitoring of nitrate, nitrite, and MCLs. Texas requires a minimum of secondary treated wastewater with recommendations to optimize for direct potable reuse (DPR) with flow equalization, improved primary treatment, improved secondary treatment with nitrification and denitrification, and enhanced secondary clarification. Florida (draft) requires annual reporting and real-time monitoring for an early warning system and a high level of disinfection for wastewater effluent with monitoring and shutdown provisions for off-spec effluent.

Outside the AWP Inside the AWP Pretreatment Program (Dischargers) Collection System Monitoring Upstream Hazard & Risk Identification (Type, Volume) Wastewater Treatment Plant Influent Monitoring Wastewater Treatment Process Analysis (Constituent Attenuation Modeling) Hazard & Risk Mitigation Protocols

Influent Process Monitoring Off-Spec Influent Alarms Online Treatment Process Monitoring Treatment Efficacy Alarms Diversion Protocols

Recommendation for ADEQ

Enhanced source control for an AWP project should be managed on a case-by-case basis with a framework and requirements for documentation and reporting based on the utility’s existing understanding of water quality conditions; process reliability and redundancy, and the portfolio of users discharging into the purified watershed. Conceptually, a programmatic approach similar to the revised Lead and Copper Rule would allow science-based testing protocols to identify types of contamination in source supplies;

establish criteria to ramp up mitigation efforts as needed, either through source controls or treatment mitigations; pinpoint treatment process single points of failure and diversion mechanisms upstream of the AWP facility and document protocols for managing off-spec source water.

In advance of engineering design and construction of an AWP facility, a reasonable database of water quality conditions must be established to be able to develop constraints for engineered controls for source water and engineered treatment mechanisms to manage source water constituents and provide potable quality drinking water. Both periodic and continuous monitoring should be implemented on an ongoing basis as part of an AWP facility permitting, in addition to a combination of approaches from the Aquifer Protection Permitting program (e.g., Financial Capacity, Contingency Plan/Emergency Response Plan) and Safe Drinking Water program (e.g., Drinking Water Capacity Development – Technical Managerial Financial, Monitoring Assistance Program).

References

1. CDPHE. 2023. “Direct Potable Reuse Policy.”

2. California Addendum. 2021. “A Proposed Framework of Regulating Direct Potable Reuse.”

3. WRF 13-12. 2017. “Guidelines for Source Water Control Options and the Impact of Selected

Strategies on Direct Potable Reuse.”

4. WRF 4960. 2023. “An Enhanced Source Control Framework for Industrial Contaminants in

Potable Reuse.”

Question 8: How should failure response be managed in a direct-to-distribution and in raw water augmentation project?

Introduction to Failure Response Plans

The development and implementation of a comprehensive failure response plan in a water treatment facility are of paramount importance. This plan is a crucial component of ensuring the consistent delivery of safe water. If off-spec water is produced, having a response plan is indispensable. This plan acts to safeguard against potential disruptions caused by equipment malfunctions, process deviations, or unforeseen incidents. It outlines a systematic course of action, delineating responsibilities, procedures, and protocols to swiftly identify, rectify, and mitigate the issues. By addressing off-spec water promptly and effectively, the response plan helps protect public health, maintain regulatory compliance, and uphold the trust and confidence of the customers.

Failure Response Plans for Indirect Potable Reuse

The objective of having a failure response plan for a potable reuse facility is to prevent the distribution of non-compliant water. In the context of indirect potable reuse, an essential layer of protection is provided by the environmental buffer, which offers attenuation, dilution, and extended response times. Therefore, indirect potable reuse (IPR) facilities possess more flexibility and security when it comes to addressing off-spec water since all IPR applications have an environmental buffer. A direct potable reuse facility doesn’t have the flexibility of an IPR facility since it doesn’t have an environmental buffer and its product water is directly conveyed into the front of the water treatment plant (WTP) or into the distribution system.

Failure Response Plans for Direct Potable Reuse

Direct potable reuse (DPR) systems include direct-to-distribution and raw water augmentation program configurations. There are several critical components and strategies that can be employed to ensure the safety and reliability of the water supply. An effective approach typically encompasses engineered storage buffers, redundancy in treatment processes, or diversion of non-compliant water. This multifaceted approach is vital for safeguarding the provision of safe and clean drinking water to the community.

Engineered Storage Buffers: Incorporating engineered storage buffers is a fundamental aspect of a DPR system. These buffers serve as a crucial line of defense against any fluctuations in water quality. By providing a reservoir of treated water that can be drawn upon in times of need, it acts as a safety net to prevent the distribution of non-compliant water. However, to be effective, engineered storage buffers must be quite large, which can add significant cost to the DPR system.

Redundancy in Treatment Process: Redundancy in treatment processes and equipment is another key element in ensuring the reliability of DPR systems. By having multiple treatment stages in place, the system becomes more resilient to variations in water quality. This redundancy can include various filtration methods, advanced oxidation processes, and biological treatment to effectively remove contaminants. Redundancy by parallel treatment units and equipment provides additional uptime but will not address the inability of a specific process to meet treatment goals. Providing additional treatment processes in series adds significant robustness to pathogen and chemical removal but at additional capital and operating costs.

Diversion of Non-Compliant Water: The automatic diversion of non-compliant water is a critical safety measure. It is, in our view, the most practical approach to prevent substandard water from entering the distribution system or mixing with raw water supplies for augmentation. Automated systems, integrated with Supervisory Control and Data Acquisition (SCADA) technology, can swiftly detect any deviations in water quality and redirect it away from the main supply. Failure responses will be different for short-term (15 minute) vs long-term (>24 hrs) cases.

It is our opinion that the most economical and practical approach is to automatically divert non-compliant water before it passes the point of entry into the distribution system for direct distribution or before the surface water treatment plant in the case of raw water augmentation. To accomplish this, facilities must rely on:

Automation and SCADA Systems: To implement automated diversion effectively, the reliability and responsiveness of automation technology and SCADA systems are paramount. These systems should be capable of quickly and accurately identifying water quality issues and triggering the necessary diversion protocols.

Calibration and Sampling Checks: Regular calibration and sampling checks are essential to validate the performance of the treatment and automation systems. By conducting routine quality checks, any deviations or malfunctions can be promptly addressed.

Periodic Tests of Automated Diversion: Periodic testing of the automated diversion process should be integrated into the operations plan. This proactive measure ensures that the diversion system remains effective and responsive, even under unexpected challenges or system upgrades.

These actions will serve to safeguard the resilience and reliability of the direct potable reuse facility, ensuring that even unexpected challenges will not impact the provision of safe and clean drinking water.

In addition, there should be an AWP finished water clearwell upstream of the diversion point with sufficient retention time to allow detection and response of non-compliant treatment performance. By incorporating these measures, a DPR facility can fortify its resilience and reliability, guaranteeing that the provision of safe and clean drinking water remains uninterrupted, even in the face of unforeseen challenges.

References

1. NRWI. 2021. “Implementation of Direct Potable Reuse a Guide for California Water Utilities.”

2. TAG. 2023. “Advanced Water Purification (AWP): Technical Advisory Group (TAG)

Recommendations”

Question 9: Describe how you would approach the Operator Certification requirements for the AWP program.

Introduction to Operation Certifications

To ensure the safe and efficient management of water and wastewater systems, the state of Arizona has established a system of certifications for water/wastewater operators. These certifications encompass a range of categories, from water treatment and distribution to wastewater treatment and collection.

Obtaining these certifications illustrates an operator's expertise and is a legal requirement to manage public water and wastewater systems.