Conference Agenda

Use of these collaborative delivery models is on the rise as Owners realize the potential advantages of quality-based selection, schedule acceleration and performance-based risk transfer of some of their most complex projects. While these models provide benefits, they are not right for every project or every client, and strong execution of any model is key to success.

This presentation will leverage Water Collaborative Delivery Association (WCDA) training materials designed to educate Owners and Practitioners about collaborative delivery models, get beyond the high-level portrayal of the models, and dig into the nitty-gritty of project execution.

The presentation will compare and contrast to following for these two models:

- Fundamental risk allocation differences

- Project progression from selection of a Contractor/Design-Builder to authorization of construction

- How a Guaranteed Maximum Price Proposal is developed and negotiated

- Guaranteed Maximum Price Proposal (GMP) contents – what does it include?

- How Open Book Pricing works in practice

- Utilization of a Risk Register to create risk transparency

- Definition of the Off-ramp and when it is utilized

- Contract Fundamentals

- High level overview of state statues

A more detailed understanding of how these models are executed will help to refine an Owners’ and Practitioners’ understanding of whether these models are appropriate ‘tools in the procurement toolbox’ for a particular organization.

Summary: This presentation will detail the key challenges Jefferson County faced in constructing a completely new wastewater treatment plant and collection system. Attendees will gain knowledge of strategies for implementing a large project involving multiple grant funding agencies, as well as bidding strategies for an inflationary climate.

Abstract:

Jefferson County, Washington, is implementing a new sewer utility and constructing a sewer system in the unincorporated area of Port Hadlock, south of the City of Port Townsend. Port Hadlock is a moderately developed rural area that is currently served by on-site septic systems. Jefferson County has worked diligently with the community and with funding partners to develop an affordable project at a sensible scale to provide a financially sustainable wastewater system that meets community needs.

Topics that will be discussed:

• Value Engineering—This project implemented value engineering recommendations to include updated planning requirements and industry advances in modular MBR treatment processes to accommodate “just-in-time” implementation of current and future treatment capacity.
• Equipment Vendor Selection—Jefferson County pre-selected an MBR vendor and contracted a price in advance of construction. This process included a scope of work for vendor design services, flow and treatment design criteria, system expansion requirements, and pricing.
• Construction Contracting Strategy—Jefferson County broke the work into several contracts and phases to ensure bidding opportunities for contractors, to attract bids from local and regional contractors, to ensure competitive bids, and to track and manage the spending of grant funds from several funding sources more efficiently. The project was divided into four contract bid packages: Treatment Plant Site/Civil, Treatment Plant Construction, Pressure Sewer Collection System, and On-Site Grinder Pump Installation.
• Results—The Treatment Plant Site/Civil contract is bidding in March of 2023 and will be under construction by June 2023. By September of 2023, Jefferson County expects to have the Treatment Plant Construction and Pressure Sewer Collection System contracts bid and construction under way. The presentation will describe the status of construction and lessons learned on the processes to get construction initiated.

As we’ve come out of the COVID era, supply chain shortages for many types of materials, equipment, and labor have persisted, increasing the likelihood that your equipment will be significantly delayed, creating missed deadlines and challenging construction. In order to avoid these pitfalls resulting from expected and unexpected long lead times, early procurement has become more critical than ever. Alternative delivery methods such as design-build and CMGC are one way to perform early procurement. However, many owners are unwilling to go to alternative delivery creating a need for a more aggressive pre-procurement strategy for conventional design and delivery (design-bid-build) process. Pre-purchases under conventional delivery are often more challenging than for alternative delivery, adding risks to owners and design engineers. This presentation will identify some of the issues we currently face when taking on pre-procurement, review lessons learned from the good and bad case studies and propose some strategies to increase certainty, reduce delays, maximize the likelihood of a quality product and minimize the risk of pre-procurement.

As owners small and large grapple with generational infrastructure projects to respond to climate change impacts, deteriorated infrastructure and increasingly stringent regulations, more and more are looking to Progressive Design-Build (PDB) as the delivery model of choice. A well-planned, transparent, and organized procurement process rooted in the owner’s priorities and drivers is critical to setting the stage for successful PDB delivery. For those new to PDB, or those who use it infrequently, getting started is daunting; the need for immediate and practical guidance has never been more important. The Water Collaborative Delivery Association (WCDA, formerly the Water Design Build Council) has recently revamped its PDB Procurement Guide, which provides owners with user-friendly RFQ and RFP templates for use as well as advice on how to procure the right PDB delivery partner.

This presentation will provide an overview of the WCDA PDB Procurement Guide and discuss specific activities and best practices to procure a PDB delivery partner, including:

- Appropriate timing of procurement and market engagement activities

- The importance of early development and disclosure of contract terms and risk allocation and providing opportunities for market feedback

- How to tailor RFQ and RFP requirements to match owner goals and objectives

Learning Objectives:

- Understand how early market engagement, tailored RFQ and RFP requirements and confidential meetings increase the likelihood that owners select the delivery partner best suited to tackle their specific project challenges.

- Define the value of securing proposer input on draft contract and commercial terms in establishing a balanced contract and fair allocation of risk – which is critical to setting the stage for successful PDB execution

- Discuss how to incorporate request for pricing information in a way that produces apples-to-apples submissions from Proposers and supports successful project execution.

- Understand what tools exist to support development of quality RFQ and RFP documents

Anaerobic digesters are typically operated with limited process information and rely on industry standard values and long detention times to minimize the impact of any perturbations. Understanding the risk of failure is particularly important when these are operated under variable loading conditions or close to their design capacity. Our ability to identify the causes of upset events and remedy them, is affected by the limited number of online parameters that can be used to characterize digestion performance, the restricted ability to make visual inspections, and the use of laboratory measurements that can sometimes be unreliable and take time to be completed.

Over the previous years, Clean Water Services has developed and implemented a bioassay to monitor the digesters of the Durham and Rock Creek Water Resource Recovery Facilities to better understand digestion performance and health as it relates to capacity. The bioassay consists of measuring the ability of the microbial communities to use a key intermediate over time, such as acetate, and can help identify conditions of stress caused by organic or hydraulic overloading. The indicators generated can provide a unique insight about operational strategies that help maintain stability. This bioassay has been proven to be reproducible, relatively easy to implement, and it can generate indicators of digestion health within 12 hours.

The experimental development of the bioassay and initial results were presented at the Pacific Northwest Clean Water Association Conference in 2022. This presentation will include an evaluation of the bioassay indicators against conventional full-scale operation metrics and will focus on addressing the following questions:

- What are some of the challenges CWS has had using traditional metrics to identify unstable conditions?

- What are some of the insights that have been generated from using the bioassay over the past year of operation?

- How can these indicators enhance the information provided by conventional metrics?

During water resource recovery, primary and secondary solids are commonly stabilized in anaerobic digesters utilizing bacteria to convert organic materials to biosolids and biogas, both having beneficial uses. The digestion process runs optimally with near uniform conditions, requiring complete mixing of digester contents with minimal short-circuiting and maintaining contact between the tank active biomass and incoming feed. Mixing efficiency is assessed post construction through tracer testing, and measurement of temperature and solids profiles. Industry has reported similar levels of mixing for a wide range of power inputs and types of mixing systems. Oversized mixing systems lead to high construction and operating costs, while under-sized systems lead to subpar performance. Understanding mixing in a more fundamental way can reduce costs while delivering desired performance aiding in design of right-size mixing systems that reduce energy consumption while maximizing biogas production and organics destruction. In addition, newer types of mixers have entered the market that may have high efficiencies. Understanding actual mixing provided by systems allows designers and utilities to compare technologies, determine the limits of mixing innovation, and ultimately select the best solution that balances cost, performance, and risk. A recent new digester installation in South San Francisco used two different mixing technologies in two otherwise similar tanks and included detailed startup testing, providing ideal data for developing computational fluid dynamics (CFD) modeling approaches to study internal mixing details.

CFD is a promising tool to optimize mixing system selection and design, as it allows us to “see” inside the tank, visualize the mixing, identify dead spots or areas of over-mixing, and provide an easy platform to customize and compare different technologies or designs. Development of CFD models for different types of mixing systems and comparison of model outputs to actual field-produced data could allow for refinement of this tool and for expanded use in digester system design and optimization. This talk will focus on the development of CFD modeling approaches for evaluating digester mixing. Key physics will be reviewed. Model results will be presented comparing model simulated mixing with field measurements.

Anaerobic digesters are the most common solids stabilization technology in municipal wastewater treatment facilities. Although they are relatively low maintenance, routine cleaning every 5-10 years helps maximize performance and prolongs the useful life of the tank. However, restarting a digester is a complex process requiring careful oversight and detailed knowledge of the plant processes. This presentation will cover best engineering practices for taking a digester out of service and restarting the process safely and efficiently. Stopping and restarting a digester require careful coordination of digester gas, mechanical processes, solids management protocol, and digester biological health. Specific procedures vary depending on the presence of other operating digesters, fixed vs floating covers, the type and quality of solids produced at the facility, and other factors. Step-by-step instructions for managing digester maintenance will be provided, along with a case study of a recent digester startup.

The Grant’s Pass Wastewater Treatment Plant in Oregon recently restarted their digester using seed sludge from a nearby wastewater treatment facility. The startup presented several challenges, including concurrent upgrades to the digester heating system, cold weather, and a floating cover digester. To maintain safety, a water seal was formed using primary effluent and seed sludge was added to the digester in batches over a two-week period. A temporary recuperative thickening process was installed to expedite the startup process. Key digester health parameters such as digester gas production, digester gas characteristics, volatile acids, alkalinity, etc. were tracked to guide the startup process.

Per- and polyfluoroalkyl substances (PFAS) are a broad class of man-made chemicals known to contaminate thousands of drinking water wells across all 50 US states, and countless more around the world. While previously unregulated, PFAS are now the subject of escalating regulatory action by governments around the world due to mounting evidence of their links to health effects such as cancer, immune dysfunction, developmental delays, and more. PFAS have high chemical stability, and consequently they persist and accumulate in the environment and in humans, causing small amounts to have outsized effects over long periods of time. Regulatory framework is chaging daily both municipally and industrially, touching water, wastewater including reuse, air, manufacturing and the solid waste industries.

The session will cover the history of PFAS and how this emerging contaminant came to be such an important issue. It will explore the ever-changing regulatory framework both at a state and federal level including water, wastewater, solid waste and federal drinking water and CERCLA regulations and how they impact the industries. It will explore the pros and cons of both common and innovative treatment technologies. The session will bring to light the questions that should be asked when faced with a PFAS issue. Case studies on successful treatment technologies for water, wastewater and leachate will be highlighted.

New federal regulatory requirements are driving water providers to provide treatment for PFAS. The US EPA and several states are in the process of setting standards for the two most common PFAS compounds, PFOS and PFOA. This presentation will address critical considerations associated with the planning, designing and construction of PFAS systems including:

• Benefits of Pilot Testing
• Selection of Treatment System Technology including GAC, IX and NF/RO
• Siting Considerations
• Operational Issues with PFAS Treatment Systems
• Design and Construction Schedules
• Capital Costs
• Operating Costs
• Lifecycle Cost of the Project
• Incorporating PFAS Systems into the existing water system

The presentation will include lessons learned on recent projects along with detailed siting, construction and cost data.

This presentation will provide information for administrators, engineers and operators involved in the planning and design of PFAS water treatment systems. The lessons learned during actual PFAS facility design and construction will assist attendees at each stage of their own projects. Attendees will gain a better understanding of the intricacies and implementation of PFAS treatment.

Rising concern of Perfluorinated alkylated substances (PFAS) contamination of our ecosystem has sparked interest in this pollutant as it pertains to water and waste management. While PFAS sources are numerous, it is widely believed that firefighting foam and extensive industrial uses are common pathways for PFAS compounds to proliferate into our ecosystem.

There is a pressing need to develop and validate advanced treatment technologies that can destroy PFAS in a variety of substrates. Supercritical water oxidation or SCWO for short, is one such advanced physical-thermal process that relies on the unique reactivity and transport properties of water above its critical point of 374 °C and 218 atm. At these conditions, organics are fully soluble in supercritical water, and with the addition of oxygen, all organics rapidly and completely oxidized to form carbon dioxide, clean water, and inorganic salts.

In an attempt to better understand the physio-chemical destructive mechanisms, and the fate and transport of PFAS compounds undergoing oxidation, a one (1) wet ton per day scale SCWO system was employed to study the elimination efficiencies of this process treating three distinct PFAS waste substrates from three different sources. The three wastes include (1) lime stabilized sludge from a municipal wastewater resource recovery facility; (2) aqueous film forming foam (AFFF) from a DoD facility; and (3) spent ion exchange resin from a ‘pump and treat’ water treatment facility.

The studies examined both targeted and non-targeted PFAS compounds, including PFOA and PFOS. These two compounds are the most studied PFAS due to their high toxicity and being most prolific in our ecosystem. SCWO, on average, was able to eliminate 99.95% of PFOA and 99.99% of PFOS across all waste substrates, and greater than 99.9% elimination of all other PFAS compounds combined.

Non-targeted PFAS was accounted for using laboratory scale verification of the fluorine mass balance. No hydrogen fluoride was found in the effluent gas, and all the fluorine from the destroyed PFAS was accounted for as fluoride in the effluent water.

The studies produced valuable data and design parameters to support design and deployment of SCWO for real world applications.

Many wastewater agencies are facing the dual challenge of trying to address PFAS within the treatment plant and facing limitations in biosolids disposal options. This presentation will address both of those challenges and give attendees a solid understanding of how PFAS enters wastewater, accumulates in biosolids, and can potentially be destroyed by different techniques that are being evaluated. We will specifically discuss PFAS characterization studies that have been done to-date in wastewater treatment plants and new innovative studies where Brown and Caldwell (BC) is partnering with utilities to better understand PFAS destruction using thermal processes. This presentation will highlight recent work that is underway at Silicon Valley Clean Water (SVCW), which has the only operational large-scale biosolids pyrolysis systems in the country. Because the fate of PFAS through pyrolysis is not well understood, BC has partnered with SVCW to perform special studies aiming to provide a comprehensive picture of the fate of different PFAS species, precursors, and transformation products through the biosolids pyrolysis processes. This work will provide valuable insights into the level of PFAS transformation and/or destruction within the pyrolysis system. Because thermal treatment is the only technology currently available to utilities to destroy PFAS, this research aims to characterize the extent of destruction and support the development of scientific data documenting their positive environmental impact.

For this study, parallel samples will be processed through SVCW’s pyrolysis reactor and a bench-scale pyrolysis reactor coupled with a thermal oxidizer at operating conditions resembling SVCW’s process. Samples of the dewatered biosolids, dried biosolids, biochar, and gas emissions will be collected for PFAS analysis, including targeted, non-targeted, and total organic fluorine to fully characterize PFAS fate through the system. Results of this study will demonstrate whether current sampling and analytical approaches approximate a mass balance for specific compounds while identifying others previously unknown. Testing is scheduled to take place this summer and results from this study may be ready to discuss prior to the presentation.

A digital twin nutrient controller running a hybrid model fed with live and historical data is being developed, piloted and evaluated through The Water Research Foundation (WRF) project 5121: Development of Innovative Predictive Control Strategies for Nutrient Removal. For ease of reference, the project team has named the controller ODIN - Operational Decision-making Intelligence for Nutrient Control.

The hybrid controller combines the strengths of machine learning with mechanistic modelling. It uses both live data from SCADA as well as historical and current laboratory data. Its components include data tools, a raw sewage soft sensor, machine learning based autocalibration of the mechanistic model at its core, machine learning based forecasting, and a machine learning based emulator of the mechanistic model. This generic structure is being used to develop and pilot nutrient controllers for four full-scale facilities in an advisory mode. The research team has been very focused on not only the technical aspects of ODIN, but also the User Interface and User Experience (UI/UX), which Clean Water Services (CWS) has been leading.

The first pilot site (four total) of the ODIN controller will be the CWS Durham facility, located in Tigard, Oregon. Durham (24 MGD average treated flow) must meet a stringent seasonal monthly median effluent phosphorus limit. Primary clarifier alum addition is used to manage phosphorus loads to the aeration basins doing enhanced biological phosphorus removal. Currently, primary clarifier alum feed is controlled to maintain an operator entered mg/L alum dose. Therefore, the phosphorus load to the aeration basins varies day to day. The ODIN controller will recommend a daily alum dosing set point to maintain an operator entered target phosphorus load to the aeration basins. Initial results have so far shown to be promising, as well as providing several potential additional benefits around dynamic flow and COD/TKN 15-minute predictions in the raw sewage.

This presentation will cover both technical and human adoption aspects of the ODIN pilot test at the Durham facility. The design approach of the UI/UX to facilitate adoption of ODIN by Durham staff will be reviewed and lessons learned, both technical and cultural, will be provided.

The Puget Sound Nutrient general permit (PSNGP) requires dischargers to submit a nitrogen optimization plan and nutrient reduction evaluation or AKART evaluation (NRE) to Ecology. Through the Association of Washington Cities, Jacobs is preparing both the NOP and NRE to meet permit requirements for more than 25 dischargers.

This presentation will summarize progress on the work to date, give costs (capital, operation and maintenance and dollars per pound removed) from the discharger community as well as estimated sewer rate and environmental justice impacts for both optimization and nitrogen removal. The presentation will outline the pathway forward to a summary Puget Sound regional nutrient study, provide lessons learned in optimization and nutrient reduction evaluation from the plant assessment performed to date, possible future uses of the data being gathered to support sound decision making on nutrient management going forward.

Clean Water Services (District) provides sanitary and stormwater services to over 600,000 people in Washington County, Oregon. The District owns and operates four water resources recovery facilities (WRRFs) that discharge to the Tualatin River. In 1988, the Tualatin River basin was the subject of one of the Nation’s first basin-scale Total Maximum Daily Loads (TMDL). The TMDL established criteria for ammonia and phosphorus throughout the watershed that were incorporated into permit limits. However, population and industrial growth in the Tualatin River watershed, changes in the water flow management, and adaptive management principles have influenced water quality dynamics and motivated the update of the phosphorus TMDL. In addition, the District uses alum as part of the water treatment process to meet the stringent phosphorus limits, but EPA recently established an aluminum water quality standard for Oregon that makes alum use no longer viable at current levels. Therefore, to continue our mission to protect the Tualatin River and to comply with both aluminum and phosphorus water quality criteria, the TMDL needs to be reviewed. The Oregon DEQ is committed to priorities other than the Tualatin River phosphorus TMDL and ammonia criteria. To respond to this an uncertain compliance conditions the District in collaborations with DEQ in collaboration with DEQ, the District is developing the modeling and scenarios to understand and update the phosphorus TMDL using a highly detailed and well calibrated CE-QUAL-W2 water quality model for nearly 83 miles of the Tualatin River developed by Portland State University and the District. This model simulates a variety of scenarios to understand the assimilative capacity of the river for phosphorus as a function of flow rate, the impacts of various nutrient and temperature management strategies on the water quality of the river, the impacts of changes in dam operations and river flows over the last 30 years, and the potential effects of various changes to the TMDL on Lake Oswego and downstream waterbodies. This presentation will showcase the scenario development and findings as well as the lessons learned to date when working to update an existing TMDL with new data and modeling techniques

Excess nutrient discharge into receiving waters can pose a serious threat to human health and aquatic life. Nutrient enrichment of receiving streams can lead to depletion of dissolved oxygen resulting from eutrophication of the water body. DO deficits reported for portions of the Southern Puget Sound have raised concerns regarding nutrient loads discharged to the water body. While both point- and non-point sources could contribute towards these, domestic effluents, wastewater treated to secondary standards (limited N and P removal) have been identified as significant contributors.

Additionally, as population growth continues to place burdens on our existing water supplies, utilities are forced to cope with poor quality and limited quantity of potable water supplies. Contaminants of emerging concern (CEC) are recalcitrant chemicals that have tendency to bioaccumulate and are not fully removed by conventional treatment. On one hand, WRRFs are being challenged to meet increasingly stricter effluent limits and rely on advanced treatment; in parallel, water scarcity has driven utilities to embrace Integrated One Water Approach to be water-supply resilient. Although treatment technology selection in potable reuse is primarily governed by WRRF’s ability to meet strict nutrient limits (N, P), co-management of nutrients and CECs in water treated across robust multi-barrier treatment schemes can be an added benefit.

This presentation will focus on lessons learnt from two case studies that highlight two different co-management approaches. The first study (WRF 4790) was aimed identifying hotspots for pollutants (conventional and emerging) and implementing holistic co-management approaches to tackle non-point (agricultural run-off and urban stormwater) and point-sources (wastewater treatment) to improve the health of the Potomac River watershed.

The second case study is on HRSD’s Sustainable Water Infrastructure for Tomorrow (SWIFT) program. The drivers for advance treatment in Eastern Virginia include depletion of groundwater resources, water quality concerns in the Chesapeake Bay, sea level rise and wet weather concerns. The benefits of advanced (non-RO based) multi-barrier scheme (ozone-BAC-GAC-UVAOP) to meet strict nutrient limits (TN= 5 mg/L, TOC= 4 mg/L) and treat CECs will be discussed.

Machine learning has been transforming many fields, including water resource management, where it has the potential to revolutionize how we collect, process, and analyze data to inform decisions. However, the field of machine learning can seem intimidating and out of reach for those without programming or data science backgrounds. In this presentation, we aim to demystify machine learning and encourage broader utilization of these tools by water resource professionals.

We will provide a brief overview of machine learning concepts and applications relevant to water resource management. We will also discuss recent developments in automated machine learning tools, which make it easier for people without coding experience to apply machine learning techniques to their data.

We will showcase an example of how machine learning has been used in CWS to generate effluent temperature predictions in the first clarifier process. In addition, we will highlight publicly available machine learning resources, including software packages and online courses, that are useful resources for learning and applying these techniques within the environmental engineering field.

Finally, we will discuss the future of machine learning in the water resource and utility sectors, highlighting the potential for improved accuracy and efficiency in decision-making, cost savings, and increased resilience to climate change and other stressors.

By the end of this presentation, attendees will have a better understanding of what machine learning is, its potential benefits for water resource management, and how they can start learning and applying these techniques to their own data.

High bacterial levels in ambient surface waters or stormwater can be a vexing problem to solve, as the traditional fecal indicators (typically E. coli or Enterococcus) give no indication of their source. Accordingly, many agencies have turned to PCR-based methods to determine the source of fecal pollution in various water matrices, a technique known as microbial source tracking (MST). The Sketa assay has been used in both research and regulatory contexts to quantify nucleic acid extraction recovery and/or environmental matrix inhibition in quantitative PCR water quality studies. The field of MST is moving to digital PCR, in which the variability from sample concentration and nucleic acid extraction exceeds the variability introduced from inhibition. Thus, a total workflow process control with an appropriate surrogate target is a more suitable approach to data quality assurance for digital PCR. Here we present a duplex Surrogate Process Control (SPC) assay for droplet digital PCR using a commercial spike-in whole-cell product at a cost of pennies per sample. This SPC measures the recovery of both gram-positive and gram-negative bacteria, which is important in contexts where both are measured for MST, e.g. Bacteroides and Enterococcus. This SPC was optimized, validated, then compared to the Sketa assay in seawater (n=5), freshwater (n=5), stormwater (n=5) and municipal wastewater influent (n=5) on the basis of percent recovery and percent inhibition. Sketa recovery (when added at the extraction step) ranged from 71- 139 percent for all samples. While inhibition was low (0% samples inhibited), the total SPC recovery varied greatly depending on environmental matrix. Average gram-positive percent recoveries were 22, 12, 9, and 1.6 for freshwater, marine beaches, stormwater, and wastewater, respectively. Average gram-negative percent recoveries were 11, 7, 4.4, and 0.4 for freshwater, marine beaches, stormwater, and wastewater, respectively. Measuring inhibition alone failed to identify samples that lost greater than one-log of material through sample concentration, especially in more challenging environmental matrices. Overall, this SPC is a robust and streamlined approach to quality control for digital PCR MST assays.

Much has been publicized in the industry about the potential for digital or “smart water” technologies to address modern challenges. Some impressive successes have been demonstrated by digital technology providers that are leveraging sensors, data systems and machine learning to optimize systems and backstop operator transitions. A digital roadmap to complement renewal, replacement and upgrade plans for physical infrastructure can help a utility access the value of digital tools, increasing resilience and allowing more to be done with fewer resources. To implement digital technologies, the water utility manager must navigate a myriad of different technology providers and products to evaluate, prioritize and select the right solutions, and then figure out how to implement, integrate, and manage through the associated changes necessary to realize the benefits of the new digital technology products.

This presentation will offer an overview of digital water technologies and their potential benefits, explain the scope and importance of a digital roadmap within the master planning context for utility infrastructure, and review methods for selecting and implementing technologies. Case studies will be reviewed including the following:

1. Deploying sensors in collection systems establishes historical data for use in planning activities while enabling conditions-based maintenance. Olathe, Kansas suffered from high I&I. They needed dependable sensors for data collection backed by software with analytical capabilities so they could assess their basins and determine where to achieve the highest impact in reducing I&I.
2. Leveraging sensors, data and machine learning can help manage collection systems and avoid overflows. Houston, Texas experienced frequent dry weather SSOs due the accumulation of FOG in random locations in their collection system. Sensors, a digital twin and machine learning were utilized to identify forming obstructions prior to overflows occurring so that crews could be dispatched to clear the obstructions.
3. Implementing a digital twin for a WRRF can improve communications between stakeholders and optimize sub-systems for less consumption of energy and chemicals. The utility needed to unify their team around data-driven decision making and capture institutional expertise ahead of expected retirements. A digital dashboard of the 70 MGD CAS WRRF was implemented for these purposes.

The Environmental Protection Agency’s (EPA) Lead and Copper Revision Rule (LCRR) requires utilities to submit a service line inventory for all services including the public and private side of the line in October of 2024. Many water agencies have invested time and resources over the past two years to establish an initial inventory, but many are faced with a daunting number of service lines with unknown materials. Physical inspection is the most reliable way to determine if a service line is lead, but often requires excavation and these inspections can be costly, ranging between $500 - $1,500 or more per property. Many communities are turning to digital methods such as Machine Learning to reduce costs and streamline the removal of lead service lines.

Collaborative Intelligence is a process in which Machine Learning is paired with human intelligence to enhance each other’s capabilities. Models excel at analyzing vast amounts of disparate data and identifying patterns; however, they need to be told which data should be included and how the output can be used.

This presentation will focus on the strategy and approach for training, using, and explaining Machine Learning to predict service line material with the goal of reducing the number of unknowns in the service line inventory in a cost-effective way. An initial model can be built using available field verification data, but if no verifications have taken place (or there are not enough to effectively train a model), data collected from historical records can be used to train the initial model. The initial model will be beneficial for targeting locations to perform further field verifications, and it can then be iteratively improved with additional field data from targeted and opportunistic inspections and replacements. We will look behind the scenes of this collaborative human and machine modeling process, highlighting techniques and approaches that help to boost model performance, ensure model reliability, and explain the outcome in terms homeowners and regulators can understand. We will present two case studies highlighting the differences in outputs due to quality and availability of model features and volume of training data (inspections).

The Southwest portion of the City of Tacoma’s (City) Central Treatment Plant (CTP) collection system is experiencing ongoing redevelopment that includes both large proposed projects and smaller projects from continued steady population growth. This portion of the collection system flows by gravity to the South Tacoma Pump Station (STPS) and is then conveyed to the CTP. STPS is due for rehabilitation based on equipment age in the coming years.

This presentation summarizes updates of Tacoma’s collection system hydraulic model and describes model use to answer questions regarding large redevelopment projects and pump station design optimization. Several possible development scenarios were projected and evaluated in the hydraulic model. A sensitivity analysis for different development types was conducted with respect to system performance criteria balancing flows, piping improvements, pump station capacity and operations.

The City provided the most recent field verified system GIS data, pump station settings, and local flow monitoring in the key basins. This information was added to Tacoma’s CTP model, making the model completely up to date. Projected flow scenarios were developed for an old Airfield that is being re-developed along South Tacoma Way. Re-development of a high density 400-unit development on 6th Avenue, and the Mall at South 48th Street were also included in the analysis. The model was used as a tool to recommend future pipe upsize and help size the new planned conveyance system to meet the City’s performance criteria.

Additionally, the hydraulic model was used to evaluate the STPS operations during both a large rain on snow storm in January 2022 and the City’s collection system design storm. Model results were compared against the system performance criteria when either 4 or 5 pumps are operating at the current STPS. This was completed for the existing system configuration and for the proposed piping changes identified for the Airfield development. Operational changes with the current pumps were tested to improve system performance during storms. Lastly, pumping capacity for pump replacement were recommended that balanced system performance both upstream and downstream of the STPS, based on the recent large January 2022 storm and the City’s design storm.

The Gothenburg region was able to address emerging challenges within its sewerage system by developing a digital twin. Gothenburg, located on Sweden’s west coast, faces many of the same challenges faced in the Pacific Northwest. Gothenburg, one of the rainiest cities in Sweden, experiences heavy rainfall causing large loading variations to its central Rya water resource recovery facility (WRRF). Approximately 25% of the sewers in the City are combined, increasing the risk of flooding and discharge of untreated wastewater into the surrounding ecosystem.

Gryaab AB, the regional wastewater utility serving Gothenburg and surrounding municipalities, owns and operates the Rya WRRF and the tunnel system transporting wastewater to Rya WRRF. Gryaab saw the potential and developed a digital twin to help better manage its sewerage system, including:

• Developing a detailed H&H model of the tunnel system and catchment area
• Incorporating all controllable devices (gates, pump, etc.) in the digital twin
• Incorporating weather forecasting in the simulation
• Development of Forecast-on-Demand features
• Development of operational strategies to mitigate the risk of urban flooding and minimize CSO discharges

Deployment of the digital twin allowed Gryaab to get better real-time information about events in the tunnels and accurate predictions of potential issues and peak pressure on the system. This allowed them to optimize the overall system performance. Simulations indicate that yearly CSOs may, ideally, be reduced by 65%, and bypass volume at the WRRF by 85% through dynamic operation of CSO sites and increased utilization of tunnel volumes. Simulations for years 2035, 2050 with various climate and population scenarios helped understand how and when to plan for expanding WRRF capacity.

The digital twin allows Gryaab to act proactively. Staff can make decisions based on comprehensive, real-time data and prognosis and even allow direct implementation of the digital twin’s suggested setpoints in the SCADA-system. The digital twin is used for training in various scenarios so that staff is better prepared for future critical situations and for making better informed decisions. In short, the digital twin is used for gaining better real-time control and improving the operation of the sewer system, both today and in the future.

Many water resource recovery facilities (WRRFs) in the Chesapeake Bay and mid-Atlantic region have completed improvements to address low effluent nutrient requirements over the last two decades. Many utilities in this region have to meet total nitrogen (TN) below 3 mg/L and total phosphorus (TP) below 0.2 mg/L.

The extensive experience in the Chesapeake Bay and mid-Atlantic regions uniquely positions utilities facing new effluent nutrient limits to learn from their peers’ experiences and adopt best practices and technology advancements for nutrient removal. This presentation will introduce key design considerations and best practices with a focus on nutrient removal experiences and introduce advances in nutrient removal technologies. Specific topics, including actual case studies, will include:

• Optimizing biological nutrient removal (BNR) Reactor Design – Providing flexibility in anaerobic, anoxic, and aerobic zones to address seasonal variations in temperature and loads allows fine-tuning of nutrient removal processes and can reduce overall volume. Providing deoxygenation zones prior to nitrified recycle pumping or unaerated zones optimizes carbon usage for nutrient removal. Proper baffle wall design to allow foam transport and surface wasting.

• Optimized Aeration System Design – Oversized aeration systems increase energy and chemical costs to meet effluent nutrient limits. Aeration systems need to be designed for flexibility over a range of variable load and environmental conditions, with a focus on maximizing turndown to avoid overaerating and allowing adoption of advanced aeration control strategies such as ammonia-based aeration control (ABAC).

• Carbon Management for Chemical Reduction – Providing flexibility in BNR reactor design and low dissolved oxygen operation improves utilization of influent carbon for nutrient removal. Many WRRFs in the region were designed to meet effluent TN limits through both BNR and denitrification filters, which require methanol addition. As WRRFs optimized their BNR processes they have become less reliant on denitrification filters, and many have discontinued methanol feed to filters.

• Next Generation Nutrient Removal – New “intensification technologies” such as aerobic granular sludge (AGS) and densified activated sludge (DAS) reduce footprints and capital costs of nutrient removal improvements. Shortcut nitrogen removal approaches such as deammonification and partial denitrification-anammox (PdNA) to lower the carbon and energy inputs required for nitrogen removal.

Many coastal waters in the US and worldwide are adversely affected by excessive nitrogen loading; however, high costs and scientific uncertainties can impede stakeholder agreement regarding the degree of nitrogen control necessary. This paper presents a case study of how regulatory agencies, utilities, and environmental groups charted a path forward for reduction of nitrogen loads to the Great Bay estuary in New Hampshire. This network of tidal rivers, bays, and harbors has experienced historical declines in seagrass. In the mid 2010s, agencies attempted to impose a nitrogen criterion that would drive stringent limits on municipal wastewater treatment facilities (WWTFs). This attempt stalled after an independent expert panel found insufficient scientific evidence that the proposed criterion would achieve the desired ecological benefits. At this impasse, utilities preferred optimization and voluntary nitrogen reductions, whereas other stakeholders continued to advocate low, enforceable nitrogen limits.

Ultimately, the parties negotiated a resolution that culminated in USEPA’s issuance of the Great Bay Total Nitrogen General Permit in 2020. This permit currently covers thirteen WWTFs, with the option for additional utilities to obtain coverage in the future. The first 5-year permit term includes enforceable nitrogen load caps, intended to limit the aggregate nitrogen loading to 100 kg/year per hectare of estuary surface area. The general permit does not include nitrogen concentration limits, and the load limits are expressed as rolling seasonal averages. This approach provides operational flexibilities to the WWTFs and allows some utilities to postpone upgrades by staying under design flow rates.

A key element of the general permit is a utility-authored adaptive management plan that charts a course for future permit terms. Under this plan, the utilities support regional water quality monitoring and scientific studies to improve our understanding of the role of nitrogen and other stressors in the Great Bay. Brown and Caldwell serves as the technical representative to the municipal alliance, advocating sound science and reasonable regulatory interpretations of the ongoing studies. This paper will describe ongoing nitrogen-seagrass studies and how those results are being considered for future general permit terms.