Conference Papers

INTRODUCTION The City of Chattanooga (the City) owns and operates the 870-megaliter per day (ML/d) Moccasin Bend Wastewater Treatment Plant (MBWWTP) that discharges treated effluent to the Tennessee River. Over the last 20 years, the City has been making strategic investments in planning level studies and innovative technologies to engage in the circular economy. Recently, site constraints and a limited capital improvements budget drove the City to investigate how thermal hydrolysis (TH) pre-treatment paired with intensified anaerobic digestion could optimize the capacity of existing assets thus avoiding costly anaerobic digestion (AD) expansion work in the future with potential economic paybacks through resource recovery. A previous investigation of TH+AD versus conventional AD indicated a narrow margin in capital and annual operating costs, however conservative planning criteria resulted in a recommendation to forego TH and expand the existing digester complex. Preliminary calculations suggested more aggressive planning criteria for a TH+AD alternative could result in a more favorable 20-year life cycle cost and opportunity for long-term return on investment through resource recovery. However, limited full-scale proof of such aggressive criteria presented unacceptable risk and required application of uncertainty factors that would again render TH+AD economically unfavorable. Therefore, the City elected to make a small ($500,000) investment in a pilot-scale demonstration study to generate site-specific data and a comprehensive life cycle cost evaluation. The objective of this paper is to discuss how the City used the pilot-scale study to de-risk a conceptual level life cycle cost evaluation and avoid approximately $50,000,000 in capital and operational expenditure over a 20-year planning period. METHODS The City completed a TH+AD pilot study to inform cost-estimating efforts associated with implementation of TH+AD at the MBWWTP. The results of this pilot study were used together with analysis of historical operating data, previous planning efforts, and industry experience to conduct a comprehensive, life cycle cost-based business case evaluation (BCE). The primary components of the BCE included flow and load projections, conceptual design of alternatives, pilot-scale testing to empirically verify the potential benefits to anaerobic digestion and sludge dewaterability, detailed capacity analysis of the existing facilities, and calculation of the 20-year life cycle cost of alternatives. The evaluation proposed and compared three alternatives: Alternative 1: Conventional Anaerobic Digestion Alternative 2: Partial-Plant TH and Intensified Anaerobic Digestion Alternative 3: Full-Plant TH and Intensified Anaerobic Digestion Site-specific operating data derived through the pilot evaluation are summarized in Table 1 and were supplemented with additional vendor testing, literature, and industry experience. These data were used to develop conceptual designs for the three alternatives including major equipment size, type, quantity, configuration, and performance. Table 1: Summary of Pilot-Derived Data Cost estimators developed a Class 5 Opinion of Probable Construction Cost (OPCC) based on the conceptual designs and price information provided by equipment vendors. The Class 5 OPCC included construction costs (direct costs and general costs), taxes, bonds, insurance, and 25 percent construction contingency and is summarized in Table 2. Escalation, estimate contingency (2.5 percent), engineering, and administrative costs are not included in the OPCC but are included in the Total Project Cost Estimate (TPCE) used in the value business case evaluation. Table 2: Capital Cost Estimates Annual O&M costs were estimated assuming 2034 annual average flow conditions (Table 3). Electricity costs were based on the number of duty units in operation at 2034 annual average solids loading conditions. Chemical costs included pre-THP dewatering polymer and biosolids dewatering polymer. Operational and maintenance labor costs were based on experience at other THP facilities and the City's hourly wage rates. Biosolids hauling costs were estimated based on the projected wet tons produced annually and vendor quoted costs for handling Class A and B biosolids. Table 3: Annual Operating Cost Estimates Finally, results were incorporated into a qualitative alternatives assessment to incorporate non-monetary considerations associated with the triple bottom line into the decision-making process. The team worked collaboratively with multiple City stakeholders to evaluate and rank each alternative under 11 criteria (Table 4). Table 4: Qualitative Evaluation Matrix RESULTS 20-year life cycle costs were prepared assuming design and construction of all alternatives occur over four years, beginning in 2020. The cumulative annual life cycle cost of each alternative was calculated (Figure 1). The estimated annual expenditure was similar for each alternative, with TH-based alternatives being slightly less due to significant savings in biosolids hauling costs. Alternative 2 was shown to have the lowest life cycle cost. However, concerns with partial-plant TH were identified early in the evaluation including inability to achieve Class A biosolids. As a result, Alternative 2 was eliminated. Alternative 3 had a lower life cycle-cost than Alternative 1 and a more favorable score in the categorical comparison. Therefore, Alternative 3 was selected as the recommended alternative. Figure 1: Cumulative Life Cycle Cost CONCLUSIONS The City's small investment in a pilot-scale demonstration study resulted in meaningful, site-specific data that increased confidence in planning criteria and life cycle cost estimates that were ultimately used to make important capital planning decisions. As a result, the City anticipates approximately $50M in capital and annual operating cost avoidance over the 20-year planning period. Several additional recommendations were proposed based on findings made throughout the evaluation. Recommendations are summarized in chronological order below. 1. Further de-risk planning and budgeting efforts by conducting a solids sampling campaign confirm or revise the blended sludge assumptions made under this evaluation. 2. Review and update flow and load projections and re-evaluate facility build-out capacity. 3. Progress Alternative 3: Full-Plant TH+AD to Preliminary Design (30 percent). Conduct value engineering, a Class 3 cost estimate, and an alternative delivery method evaluation. 4. Evaluate secondary treatment capacity considering current performance, future performance under projected flows and loads, current and future nutrient regulations, and opportunities to retrofit existing infrastructure for sidestream treatment. 5. Design and construct full-plant THP and intensified anaerobic digestion incorporating findings from recommendations 1 through 4. 6. Design and construct sidestream treatment (likely in conjunction with TH project). 7. Evaluate energy management alternatives in a small study after TH and digester system commissioning. 8. Implement selected energy recovery based on results of evaluation and available funding.

According to an October 2022 article published by the National Oceanic and Atmospheric Administration (NOAA), the year had below average precipitation, but by the end of September, the country had sustained 15 separate billion-dollar weather and climate disasters, including several significant rainfall events. In the first nine months of 2023, the National Centers for Environmental Information reported 24 such events, of which included 18 severe storms, two floods, and one tropical cyclone. As of October 10, 2023, these weather events caused 373 deaths across the country, with unprecedented economic impact in the Northeast and southern California. It is clear to weather experts that the increased occurrence and severity of rain-related events are no longer a future problem but are happening now. Significant rainfall events are more intense and occurring more frequently than before, taxing infrastructure systems in a myriad of ways. Communities across the country often designed infrastructure planned for less severe storms, if they planned at all. Capacity limitations and aging infrastructure have resulted in floods that wreak havoc on roads, buildings, and other utilities. Furthermore, many communities lack the stormwater funding resources to rebuild resilient infrastructure needed to limit further impact of future severe weather events. Moreover, National Pollutant Discharge Elimination System (NPDES) regulatory requirements continue to increase, necessitating additional investments in stormwater treatment and other clean water initiatives. It is apparent that creative approaches to funding the future of stormwater will be necessary. The Massachusetts Clean Water State Revolving Fund (SRF) has a unique grant program designed to fund asset inventory and management planning projects. Historically, these funds were used to develop conventional asset management plans for wastewater and stormwater systems, with a focus on condition assessment. Increasingly, these funds are being used for stormwater systems and include stormwater capacity analysis as a primary component of risk assessment. This is a relatively new development for the program. The state expects this grant money will help establish current conditions of stormwater systems and drive more funds in the SRF to finance stormwater infrastructure. In addition to the SRF program, Massachusetts Municipal Vulnerability Preparedness (MVP) program provides grants to fund the identification of climate hazards and infrastructure vulnerabilities, including water quality vulnerabilities, as well as the development and prioritization of action plans to improve resilience to climate change, building climate resilience, equity, and climate justice. In 2021, Senate Bill 1954 was signed into law, establishing the Resilient Florida Program for a coordinated approach to the state's coastal and inland resilience. The legislation funnels a significant investment toward protecting inland waterways, coastlines, and shores, and provides aid to communities that want to prepare for the impacts of sea level rise, intensified storms, and flooding. In February 2023, the state's governor announced more than $275 million in grants was being awarded to 75 resilience projects, which will help safeguard homes, businesses, and critical infrastructure from damages incurred by storm surge and flooding. While California has experienced significant drought conditions over the past decade, the state's Department of Water Resources (DWR) released $9.2 million in grants in 2023 to fund five projects aimed at restoring streams and creeks to more natural environmental conditions, which will help reduce flood risk in several communities. This funding is part of DWR's Riverine Stewardship and Urban Stream Restoration programs designed to protect listed fish species, while also addressing flood risk reduction and ecosystem enhancement of urban streams. State experts are anticipating 2024 will be another wet year with strong El Nino conditions. The state government has earmarked more than $430 million in its recent budget for flood response and projects designed to mitigate future flood damage. Furthermore, municipalities and county governments can leverage financial assistance under the California Disaster Assistance Act when natural disasters occur. Funds through this program can cover up to 75 percent of cost for activities, such as basic engineering for construction projects, repair, permanent restoration, and replacement of public facilities. This presentation will examine each state's unique approach to accessing regional and federal funding resources that enable projects aimed at improving infrastructure resiliency, addressing water quality, and mitigating damage caused by heavy rain and flooding events. Presenters will provide case studies from communities that have already applied for and receive funding for risk and vulnerability assessments, as well as the resulting projects prioritized during the evaluation process. Attendees will learn how this work goes hand in hand with the regulatory framework of Municipal Separate Storm Sewer System (MS4) and NPDES permitting.

Whether we need to address underlying industry needs such as funding aging infrastructure, or other critical issues like water affordability, the need to develop an effective financial strategy is as relevant as ever before. This panel discussion will explore the building block of a sound financial strategy, bringing perspectives from both, a large and a mid-size water utility, as well as from industry practitioners that will be able to share traditional and emerging tools available to the industry.

KEYWORDS Sludge dewatering, data collection, screw press, meta-analysis BACKGROUND Performance estimation for Biosolids dewatering is of great importance for project planning and dewatering system design. Given the cost implications associated with dewatered solids hauling, polymer consumption, and capture rate efficiency, identifying accurate ranges for predicted equipment performance is advantageous to facilities that produce and process biosolids. Equipment manufacturers are able to collect data from existing installations and pilot scale testing for utilization in large scale meta-analysis. This analysis increases predictive capability as it yields insight into how upstream processes and sludge composition influence dewatering performance. Bench scale testing can also be utilized, however should be viewed with more scrutiny, as it cannot exactly replicate onsite performance. METHODS Bench, Pilot, and Full Scale installation testing data was collected from hundreds of facilities across the United States, during a period of time between 2014 and 2022. A Screw Press dewatering device was used on all tests. Figure 1 below shows the number of data points for each type of testing: Bench Scale Testing Pilot Scale Testing Full Scale Installation Testing ~360 ~200 ~100 Table 1: Number of data points for each type of testing conducted in this analysis Figure 1. Dewatered Cake Solids from Screw Press Equipment To assist in the statistical analysis of performance data, multiple descriptive 'tags' were created and assigned to various parameters of the sludge being tested. These tags allowed for the storage, categorization, and comparison of performance data between similar sludges. Each parameter used in the meta-analysis was obtained from a questionnaire filled out by the facility contact, and is one of the 23 following: Sludge Parameter Tags 1. Cake Solids (%) 2. Polymer Dose (lb active/DT) 3. Capture Rate (%) 4. Feed Solids Concentration (%) 5. Throughput (gpm) 6. Solids loading (lb/hr) 7. Machine Size 8. Facility Flow (MGD) 9. Waste Sludge Flow (GPD) 10. Sludge Age (days) 11. Sludge Type (WAS, Primary, Blend) 12. Volatile Solids Ratio (%) 13. Digestion Type (Aerobic, Anaerobic) 14. Total Dissolved Solids (mg/L) 15. Sludge pH 16. Chloride Value (mg/L) 17. Phosphate Value (mg/L) 18. Nitrate/Nitrite (mg/L) 19. Sludge Temp (F) 20. Bench Cake/Bench Polymer Dose (For comparison to field values) 21. Biological Process Type 22. Type of sludge storage (Day tank, Holding tank, Lagoon) 23. Digestion temperature range (Mesophilic, Thermophilic, TPAD, None) Table 2: Sludge Parameter Tags Recorded parameters were tabulated and analyzed using Microsoft Excel, as this provided the easiest means for exporting data collected from online forms. The programming language Visual Basic was utilized as a tool to filter and plot all of the data, allowing for comparison and determination of trends between two different sludge parameters. RESULTS The operator of this analysis tool is able to define X-axis and Y-axis parameters for comparison. Once selected, data points will be plotted along with a trend line to describe the behavior of the data set. Any additional filters applied to the data will further narrow the data set, allowing the operator to view only those data points which fall within a desired range of sludge characteristics. Figure 2. Data Analysis Main Page Further analysis employing the use of standard deviations for each data set allowed for the creation of statistically derived ranges that aid in estimating performance to a more accurate degree than sludge type alone. One such example is shown below in Figure 3, where Cake Solids (%) is compared with Volatile Solids Ratio (%). This search is further refined by only looking at Waste Activated Sludges (no primary component) with Aerobic Digestion. This returns a truncated list that provides a clear relation between Cake Solids and VSS for the sludge type specified. Figure 3. Cake Solids vs. VSS Ratio for Aerobically Digested WAS Sludges Another example of this can be found in Figure 4, which shows a trend of polymer dose compared to feed solids. This is further filtered by looking only at anaerobically digested sludges which fall within the mesophilic temperature range. Figure 4. Polymer Dose vs. Feed Solids for Anaerobically Digested Sludges in the Mesophilic Temperature Range DISCUSSION The tool shown above is useful in making performance determinations and estimations for new and existing projects by leveraging past data from multiple sources. The accuracy of this tool will continue to increase as the data set becomes more robust, meaning that the usefulness of this meta-analysis for project planning will continue to increase. Cooperation between manufacturers, consultants, municipalities, and academia in combination with tools similar to the one described herein has the potential to bridge the gap between dewatering system expectation and actual performance, as each party is able to bring unique contributions to the discussion. The intent of this project was to continue the conversation on ways to create more accurate projections for municipal sludge dewatering performance. Further, this project aimed to explore and qualify the intricacies that are inherent in the municipal wastewater treatment process, and provide a way to identify the factors that can positively or negatively affect dewatering system performance. It should be noted that while this project aimed to be as thorough as possible in terms of data collection and analysis, the study of sludge Dewaterability is ongoing, and as such some factors which influence dewaterability were not included at the time of writing. SIGNIFICANCE/IMPLICATIONS Manufacturers typically have the greatest access to large quantities of data, due to the many projects that they entertain. Through coordinated efforts between all involved parties, a qualitative approach to data analysis can allow for a better understanding of how to estimate performance, especially at new facilities where sludge is not available for testing. Statistical meta-analysis can provide a higher degree of certainty regarding performance expectations as compared to traditional estimations based on sludge type alone.

Stated Purpose: The propose of this presentation is to summarize the planning approach for replacing and upgrading one of the Metropolitan Sewer District of Greater Cincinnati's (MSDGC) critical collection system assets – the Pleasant Run Force Main (FM) system. This presentation will provide an inside look at MSDGC's innovative planning approach for replacing the Pleasant Run FM system, the various alignment and coordination challenges, and the use of FLAMROC as MSDGC's planning tool for evaluation and final selection of alternatives. Benefits of Presentation: Several large cities have critical aging assets in heavily urban locations. Replacement and upgrades to these critical assets present various planning, design, and construction challenges. The Pleasant Run FM upgrades project is one such example of a planning challenge. The Pleasant Run FM's were originally constructed in the 1970's, have historically been maintenance intensive, and are considered to be among the most critical assets maintained by MSDGC due to the significant consequence of failure and large number of customers served. Sections of the force mains have been replaced and/or repaired frequently, and the lack of redundancy in the system presents one of the most significant environmental risks to MSDGC. There is currently no contingency plan to address failures which would result in large quantities of sewage overflowing into local streams or residential neighborhoods. The planning goal is to develop innovative cost feasible solutions that offer operational redundancy, 50-year asset life, and can be constructed with minimal interference to the existing system operation. Key take-aways from this presentation will include the development of alternatives through alignment challenges (such as avoiding a cemetery, crossing County boundaries, I-275 highway crossing, etc), coordination challenges of working with multiple local city governments and townships and their associated existing infrastructure (such as water main, storm sewers etc.) and the use of FLAMROC planning methodology for screening and final selection of alternatives. Project Description: This project is located in the Mill Creek sewer shed in Hamilton County, Ohio, between John Gray Road on the north, just south of Waycross Road on the south, the Pleasant Run West Pump Station (WPS) on the west, and the Pleasant Run East Pump Station (EPS) on the east. The EPS FM discharges to a 3,000-feet (ft) long, 16-inch diameter FM which runs along Hazelgrove Drive to Mill Road and discharges into the Central Pump Station (CPS). The WPS discharges into a 5,500-ft long, 24-inch diameter force main which runs under John Gray and Mill Roads to the CPS. The CPS repumps flow from the EPS and WPS into a 24-inch diameter force main which runs 7,000 feet under and along Mill Road to Gravity Sewer Manhole 30811002. Planning Approach Summary: Thirteen conveyance alternatives, and several sub-alternatives were evaluated to determine the best combination to convey wastewater from the Pleasant Run FM's to the downstream gravity sewer system. After narrowing down the alternatives into four options, the FLAMROC analysis evaluated alternatives on their Flexibility, Land Availability, Adaptability, Maintainability, Reliability, Operability, and Constructability (FLAMROC). The four alternatives listed below were found to be the most feasible and beneficial to MSDGC. 1. Alternative 1 (EPS to CPS, WPS to CPS, CPS to MH NO. 30811002) - One new FM from EPS to CPS (utilize existing force main) - Two new FM's from WPS to CPS - Two new FM's from CPS to MH - Rehab EPS, WPS and CPS - Equalization at WPS 2. Alternative 2 (EPS to WPS via force main, WPS to MH NO. 30811002) - Two new FM's from EPS to WPS - Two new FM's from WPS to MH - Rehab EPS - New WPS (demolish existing WPS) - Eliminate (demolish) CPS - Equalization at WPS 3. Alternative 3 (EPS to WPS via force main and gravity sewer, WPS to MH No. 30811002) - Two new FM's from EPS to high pt., 1 new dedicated gravity sewer from high pt. to WPS or upsize lower reach of existing downstream sewer to WPS to accommodate the added flow - Two new FM's from WPS to MH - Rehab EPS - New WPS (demolish existing WPS) - Eliminate (demolish) CPS - Equalization at WPS 4. Alternative 4 (EPS to WPS via deep gravity sewer, WPS to MH No. 30811002) - One new dedicated deep gravity sewer from the existing EPS site to WPS, including a majority of the gravity sewer installed via trenchless technology Two new FM's from WPS to MH - New WPS (and demolish existing WPS) - Eliminate (demolish) EPS - Eliminate (demolish) CPS - Eliminate (demolish) Kemper Mill Village Pump Station (KMPS) - Equalization at WPS. Based on FLAMROC scoring analysis, Alterative 2 (Figure 2) was eventually selected as the recommended alternative. This alternative includes the following components: - Rehabilitate the existing EPS - Install new dual FM from the existing EPS to the new WPS - Abandon in place the existing EPS FM - Construct new WPS - Demolish the existing WPS - Abandon in place the existing WPS FM - Construct new 300,000-gallon EQ Tank at WPS. - Install new dual FM from the new WPS to existing MH 30811002 - Demolish the existing CPS - Abandon in place the existing CPS FM The projected costs are as follows: - Total Construction Cost: $27,2,000,000 - Total Budgetary Cost: $49,308,000 - Net Present Value (NPV) / Life Cycle Cost: $39,400,000 - Equivalent Annual Life Cycle Cost: $2,500,000 Project Status of Completion: The planning phase was completed in the summer of 2021. The project is anticipated to take over five years from design through construction, with Design of Alternative 2 beginning in August 2021. Originality: This project had several creative and innovative solutions evaluated as part of alternative development. Alterative 4 proposed to build a deep gravity tunnel and install dual FM's in the same casing pipe as that of the gravity sewer. Alternative 2 proposed redundant force mains with cross over vaults to switch flows between dual force mains when needed. MSDGC's FLAMROC analysis was used to develop weighted scoring criteria for non-cost factors that were important to MSDGC. 

As technology advances water systems are creating more and more data. However, data management practices have not kept pace, often leaving information siloed amongst various groups within a utility's organization and requiring additional steps for analysis. As an industry, we are often information rich, but knowledge poor. Smart Utility concepts include leveraging technology to empower a utility's workforce. Smart Utility technology components collect data, provide understanding and meaning of data, embed operational goals and requirements with historical context and performance targets to help operators understand how complex systems will react in future scenarios-in other words, they help you go from data, which means very little to knowledge which allows for real time informed decision making . This unlocks a wide range of opportunities to optimize performance targets, staff time, consumable cost (energy and chemical usage) and assess system performance at a glance. Looking to the future, PWB made the decision to embed Smart Utility concepts in the design of their new Bull Run Filtration Facility. Working with Brown and Caldwell they developed a Smart Utility implementation plan. A series of data dashboards were developed for plant operations optimization. These included managing complex source water decisions, monitoring and controlling process operations (coagulation/flocculation/sedimentation, filtration, disinfection), solids management, tracking the water balance, and maintaining distribution system water quality. These reporting and advisory tools can be used to provide guidance to inform staff of changing conditions in the system (source, plant and distribution). Developing these dashboards positions PWB to efficiently implement the final in-plant smart utility system, incorporate the needed monitoring requirements into the facility design, easily train new operations staff by using these new tools, and position them to plan for learning tool options to incorporate in the next phase of system development. This presentation will start by describing the initial challenges of getting alignment at the initial planning phase from the director level and the staff level to understand how each of the tools and solutions need to perform to meet the goals of the Bureau. Based on these initial performance metrics, we will visualize the dashboarding tools to describe the concepts and the process used to create the dashboards what the end use actions are that can be taken by operations due to the use of these advanced tools and then describe why these operator advisory dashboards provide a greater degree of operational knowledge compared to a typical SCADA system screen and how these benefits are aligned with the goals of the utility.

The purpose of this abstract is to provide engineers and utility owners with valuable design and construction considerations for connecting to and working with existing, large-diameter (LD), pressurized concrete pipe – which in the context of this presentation includes asbestos cement (AC) and prestressed concrete cylinder pipe (PCCP). Risk exposure increases exponentially when working with LD pipe and working with older, susceptible, cementitious pipe materials can exasperate construction challenges. The Hampton Roads Sanitation District (HRSD) recently completed a project with an unusual amount of work with and connections to AC and LD PCCP force main (FM). Located along the eastern region of Virginia, HRSD owns and maintains more than 500 miles of pipelines, most of which is LD, pressure FM. Although HRSD has developed detailed design and construction standards for working with these pipe materials, this project included additional, innovative design and risk-mitigation elements to achieve success. The Western Trunk FM Replacement project, located in Virginia Beach, VA, was an US Environmental Protection Agency Consent Order (EPA CO) Rehabilitation Action Plan required project with associated deadline of May 5, 2021. The EPA CO required abandonment of a 6,000 linear foot (LF) section of 20-inch AC FM and transfer of flows to a parallel section of 1970's-era, 48-inch PCCP FM. The project scope also included (non-EPA CO requirement) installation of two 'valve complexes' along the 48-inch PCCP FM. This project carried substantial risks to regional sewer operations, property damage, and public safety if a failure were to occur. Therefore, this presentation will focus on identifying risks during planning, mitigation through design and results and lessons learned during construction. Topics include: - Proper design and execution for approximately 17 planned connections to LD FM - Structural considerations and mitigation to reduce failure of existing pipelines - Corrosion mitigation - Contractor/Subcontractor prequalifications Connections: To meet the project scope, the temporary and permanent work included: - Over 700 LF of new 8-, 12-, 16-, 42- and 48-inch FM - Three FM reconnections from the 20' AC FM to the 48-inch PCCP FM - Installation of two 'valve complexes', each consisting of an inline, emergency 48-inch isolation plug valve and branch 42-inch isolation plug valve (for future connection) and associated LD appurtenances - Two 48-inch by 36-inch dual line-stop and bypass systems To execute the above tasks, the project included two connections to the existing AC FM (including one impromptu connection due to a faulty valve) and 15 connections to the existing 48-inch PCCP FM. For each connection, the design had to evaluate a multitude of failure mechanisms and proper mitigation efforts. Another important factor to consider was the requirement to maintain system flow during construction. The presentation will detail the planning, design and construction of these connections and elaborate on the critical components, including: - Risks of pipe failure, property damage, public safety, - Use of HRSD standards and what additional provisions, design elements were included, - Development of a very complex and ultimately successful sequence of construction, - Results during construction, how design standards and construction checklists added value, - and improvements to design/HRSD standards based on lessons learned. Structural Considerations: Every connection required special attention to newly applied hydraulic, weight loading and stress to the existing pipelines, regardless of size. To minimize risks of settlement and corresponding pipe failures through joints or other means, the design needed to include specific measures, materials and structural designs to ensure the proposed improvements did not cause failure to the existing, active FMs. The massive weight of each 'valve complex' would place stress on the existing 48-inch PCCP joints if not supported properly. The design had to consider provisions to minimize potential for settlement and reduce risks to the existing 48-inch PCCP including detailed bedding design, interior and exterior welds, concrete support pads and testing during construction. The presentation will detail the design and construction of the structural elements of this project and elaborate on challenges and lessons learned during construction. Corrosion Protection: The piping design had to consider exterior corrosion from corrosive soils, internal corrosion from sulfuric acid buildup and galvanic corrosion due to material electrode potential differences. Local soil corrosivity was a major concern with soil resistivity readings below 5,000-ohm/cm and potential for aggressive exterior corrosion to DIP. Although HDPE was considered, certain constraints ultimately led the engineer to select DIP. To protect the new pipe, a complex system of protection was designed including special interior and exterior coatings, cathodic protection system and simple, yet innovative approaches to isolate galvanic corrosion between differing metals. The presentation will cover the design elements included to protect the pipe and the specialized work, including: - system design and innovative approaches to limiting corrosion migration - specialized construction and how systems were inspected - challenges during construction, lessons learned and any improvements to design standards Contractor Prequalification: Due to the high-risk, critical nature of LD FM work and specialized experience for tapping and line-stop work, rigorous qualifications were required of the general contractor and subcontractors to ensure success and timely execution of the work. HRSD's frequent need for pipe tapping and line-stop activities for work on active LD FMs has led them to develop very detailed subcontractor qualifications for both specialties, which were utilized for this project. Ultimately, an experienced contractor, teamed up with a well-known reputable subcontractor to perform both specialties. This presentation will touch on the value of the prequalification requirements, how these impacted bidding and award of the project and contractor/subcontractor performance during construction. Conclusions: On paper, these connections can often appear very simple. However, without proper consideration of historical installation techniques, material properties, construction methods and site specific and locational challenges, reduced service life and/or catastrophic failures can occur. At the time of this abstract submittal, the project has achieved substantial completion and met the Consent Order deadline. Given the location of this project within a busy, multi-lane corridor, any damage to existing FMs could have been catastrophic. However, based on a robust design and an experienced contractor adhering to HRSD's PCCP and AC pipe handling and tapping protocols, zero pipe failures occurred. Engineers and utilities that work with critical, LD pressurized AC and PCCP pipelines, will find value from this presentation with new insights and valuable tools to help during their next project. The presentation will explore the success of HRSD's standards and construction checklists used, additional design provisions for risk mitigation, lessons learned during construction and what improvements could be made in the future. Attendees will enjoy a summary of unexpected issues incurred during construction and how they were resolved without missing contract or Consent Order deadlines.

Just over 10 years ago, the Minnehaha Creek Watershed District (MCWD) recognized an opportunity with a 17-acre aging industrial site bordering their Creek. The property was a missing link in the Minnehaha Creek Greenway, borders a popular regional trail system, is located next to a planned METRO Green Line station, and has two urban stormwater discharge points that drain 270 acres directly into Minnehaha Creek. Inquiries were made with the property owner, and MCWD purchased the 325 Blake Road site in 2011. Following several years of site preparation and community outreach, MCWD and the City of Hopkins developed an innovative vision for the site centered around MCWD's ethos of 'balanced urban ecology.' The Minnehaha Creek Watershed District spans 178 square miles, including prominent waterbodies such as Lake Minnetonka, the Minneapolis Chain of Lakes, Minnehaha Creek, and Minnehaha Falls. The watershed includes eight major creeks, 129 lakes, and thousands of wetlands. The MCWD includes all or part of 27 cities and two townships in Hennepin and Carver counties. The concept for 325 Blake Road involved having MCWD retain a 4-acre portion of the site for regional stormwater treatment, riparian preservation, and public amenities; while fostering development of the remaining 13 acres of the parcel with transit-oriented, water-centric residential, commercial, and public spaces that would complement and enhance the MCWD site. In 2020, MCWD selected an HDR team as the designer for their project. In 2021, Alatus Development was selected as the developer for the remaining parcel and began advancing towards construction with an extensive range of stakeholders, including: -City of Hopkins (Public roads/utilities/parks and Tax Increment Financing) -MetroTransit (Nearby light rail corridor/station and station access Three Rivers Park District (Shared trails and access) -Hennepin County (grant funding and parcel development) -Neighborhood residents and business owners (amenities and impacts); and -MN Public Facilities Authority ($4.5M grant for stormwater treatment) MCWD and the design team understood the importance of transforming MCWD's original vision into a shared vision amongst the stakeholders to successfully advance the project. Several public listening sessions were held to establish public priorities. These priorities were carried into a design charrette with public and private partners including elected officials, planners, designers, developers, architects, and engineers. Over two days, approximately 30 participants engaged in a creative and collaborative process to refine and establish concurrence on the site layout and objectives. With the community, developer, designers, and agencies on board, the project design is approaching 100% with a portion of construction already underway. The design continues to follow the charrette concept very closely. To compensate for design constraints, an innovative treatment train was established that includes a pumped and filtered stormwater cascade. This process is embraced by MCWD and the developer, anticipated to remove nearly 100% of TSS and 74% of TP on an average annual basis. Stormwater treatment also serves as a feature for the thriving development and public realm amenities. The extensive stormwater treatment train concept includes underground pre-treatment vaults that are in line with the regional storm sewer, extended detention basins separated by a weir wall for aesthetics and long-term maintenance, a pump that conveys detained stormwater through manufactured treatment devices, and a stormwater cascade that manages hydraulics and provides filtration throughout the vegetated channel. Ultimately, regional stormwater is discharged back into an extended detention basin for a constant cycle of stormwater treatment through the system. Elsewhere on the site, green infrastructure practices including permeable pavement, rain gardens, tree trenches, and stormwater cisterns are planned for site stormwater management. This presentation focuses on reviewing key elements of project planning, stakeholder coordination, and the design charrette collaboration that helped establish consensus with key project partners and enhance the project design. The anticipated benefits of the project will be reviewed, including water quality and conservation, which was the genesis for MCWD's initial curiosity about the site, carried through to a collaborative vision of a balanced urban ecology at 325 Blake Road.

SUMMARY
Pima County's unique landscape includes climate temperatures ranging from the low 60's in winter months to the 100's during the spring and summer. Vast coverage areas include urban and suburban populations with numerous mountain ranges resulting in large elevation swings. Due to the extensive network of sewer lines and manholes, Pima County experienced high hydrogen sulfide (H2S) amounts throughout their collection system. The Odor Control Conveyance team wanted to monitor problematic sites to validate known issues and discover any unknown issues which could cause potential health hazards to employees and the public; nuisance due to smell; and pipe corrosion/damaged infrastructure, leading to lowered asset life and possible SSO's due to potential pipe/manhole collapse. KEYWORDS: hydrogen sulfide, odors, SSO, smart sewer, smart water, automation, smart city, smart infrastructure, remote sewer monitoring

INTRODUCTION A UNIQUE CLIMATE LANDSCAPE
Pima County Regional Wastewater Reclamation Department (RWRD) serves 280,000 customers across the Tucson area, covering 420 square miles, 5 jurisdictions, and 2 tribal nations. Vast coverage areas include urban and suburban populations with numerous mountain ranges resulting in large elevation swings. RWRD maintains and operates 3,500 miles of sanitary sewer lines, 67,000 manholes and 8,400 public cleanouts. Pima County's unique landscape includes climate temperatures ranging from the low 60's in winter months to the 100's during the spring and summer. During rain events, data collection from sensors provides flow level data alongside 8 rain collection sites. GPS sensor monitoring provides RWRD with not only sanitary sewer system capacity in monitored areas, but also the amount of Inflow & Infiltration (I&I) entering the collection system that ultimately goes towards the Agua Nueva & Tres Rios Treatment Facilities for treatment.

THE CHALLENGE WHAT'S THAT SMELL?
Due to the extensive network of sewer lines and manholes, Pima County experienced high hydrogen sulfide (H2S) amounts throughout their collection system. The Odor Control Conveyance team wanted to monitor problematic sites to validate known issues and discover any unknown issues which could lead to potential health hazards to employees and the public; nuisance due to smell; and pipe corrosion and damaged infrastructure causing lower asset life and a threat to the Sanitary Sewer System environment (i.e. possible SSO's due to potential pipe/manhole collapse). Prior to deploying smart sewer technology, reactive dosage amount performed at Chemical Dosing Units (CDU) were based on odor complaints within odor loggers capturing H2S PPM data for analysis. Both Liquid Phase and Vapor Phase Treatment were used which increased chemical and labor costs and created greater inefficiencies.

THE SOLUTION: SMART SEWER H2S MONITORING TECHNOLOGY
In order to take a more proactive approach, Pima County deployed 44 real-time satellite monitoring H2S units to provide real-time, low-cost hydrogen sulfide (H2S) monitoring at problematic sites across the collection system. Large amounts of data collected from the units allowed Pima County to better understand their system, pinpoint problem areas and fine tune chemical dosage, in turn, optimizing resources to prevent asset degradation. Pima County was then able to integrate H2S data with their asset management system which gave them the ability to monitor CDU dosing changes and, within an hour or two, see the H2S level change based upon the dosing values applied; reduce chemical dosing based on live trend H2S values; and determine the required usage based on CDU tank level volume to not only extend chemical usage, but to also use the chemical more efficiently. With the API integration, approximately 25,000 data points were pulled into the MS Power BI platform for evaluation along with the Asset Management system (Infor IPS). Numerous sensors monitor mid-large size interceptors and other problematic areas and the sensor data capture allows the department to look at the Conveyance system and more efficiently visualize the data through dashboards, analyze collected sensor data and work orders, and use those dynamic measures to understand the collection system status.

THE PROOF: PINPOINTING HOTSPOTS LEADS TO IMMEDIATE ROI
In addition to a better overall understanding of the system, Pima County has been able to quickly identify and address problematic areas, including CDU site dosing, H2S PPM values, and areas where flow monitoring is needed. Smart sewer technology has allowed them to better allocate resources (staff and vehicle travel costs) based on work order evaluations in comparison with unneeded site visits. The County has gained improved visualization of site conditions leading to a more proactive versus reactive decision-making process. The creation of visual baselines and development of KPIs has minimized issues and alleviated known odors. And, the 24/7/365 eyes and ears of the sewer allow real-time evaluation of any changes in the system, making chemical dosing dynamic, thus allowing for reduction in chemical costs and/or allocation of saved chemicals for timeframes when chemical is needed.

INTRODUCTION AND PURPOSE The Great Lakes Water Authority (GLWA) is Michigan's largest regional wastewater collection and treatment system encompassing eighty-six wholesale customer collection systems across three counties and 944 square miles in southeast Michigan. The regional collection system serves approximately three million people, representing one third of the state's population. GLWA operates the regional collection system and Water Resource Recovery Facility (WRRF) through a lease from the City of Detroit. The leased facilities include 183 miles of trunk sewer, interceptors, and outfalls; 6 pumping stations, 16 in-system storage devices, 8 retention treatment basins and screening and disinfection facilities, the WRRF and associated metering and control facilities. The City of Detroit Water and Sewerage Department (DWSD) owns and maintains the wastewater collection system and water distribution system within the City of Detroit. GLWA Member collection systems include 77 untreated CSOs, several points of SSO during large weather events, 12 CSO retention and treatment facilities, and 14 sanitary retention basins, and an estimated 3,000 MS4 separate stormwater outfalls. A high degree of structural optimization has already been achieved through local water quality improvement initiatives, NPDES permit compliance, and operating protocols developed over more than 30 years of combined sewer overflow (CSO) control. The Regional Operating Plan (ROP) is intended to further optimize operations by analyzing the detailed system response to storm events, including expanded sharing of real time SCADA data. This presentation describes the development and integration of GLWA's regional collection system model with a GIS-based digital twin platform that integrates near real time data from SCADA, radar rainfall, and overflow reports with the collection system model. The digital twin is a key element of GLWA's ROP, which was developed to optimize wet weather operational performance across six major wastewater utilities that are wholesale customers to GLWA's regional collection system. This close integration of model and data in the digital twin allows for rapid post-event monitoring and near-real-time analysis of collection system performance during wet weather, facilitating continuous optimization of wet weather operations by GLWA and its Members. BUILDING THE REGIONAL WASTEWATER COLLECTION SYSTEM MODEL AND THE DIGITAL TWIN GLWA developed a new Regional Wastewater Collection System model using EPA's Stormwater Management Model (SWMM) as part of its Wastewater Master Plan project from 2017 to 2020. The collection system model consists of over 4,400 individual model subcatchments and 16,000 pipes covering the entire GLWA service area, including detailed operating rules to represent dry and wet weather operations at key facilities. The model was calibrated to metering data to meet the calibration metrics issued by the Chartered Institution of Water and Environmental Management (CIWEM) Code of Practice for the Hydraulic Modelling of Urban Drainage Systems. The digital twin builds upon the collection system model, and integrates the following elements (Figure 1): - The calibrated and validated collection system model - Gage-adjusted radar rainfall data from Vieux and Associates at a 1-kilometer grid cell resolution adjusted to 36 regional rain gages. The radar rainfall data are sent daily at 5-minute increments and applied to all 4,400 model subcatchments - 540 individual measurement points at 5-minute intervals sent daily from GLWA's Ovation SCADA system. These points represent river stage, pump and gate operating records, and flow metering. - Post Event Reports generated after significant storms to document combined sewer overflow events. The digital twin was built in PipeCAST, a web-based GIS platform that integrates monitoring data and modeling results to facilitate decision-making and post-event analysis in near real time. Its foundation is built upon the concept of the digital twin, which is a virtual copy of the collection system that is used to generate real-time simulations from current weather and precipitation conditions (Figure 2). The PipeCAST system automatically receives data from the radar rainfall grid, climate data from NOAA, and SCADA data through a secure application programming interface (API) connection and runs the collection system model for the previous day. The direct connection to SCADA allows the model to simulate dynamic backwater conditions at each CSO outfall and actual pump station operations. The PipeCAST interface provides a GIS-based visualization of metered and modeled flow, depth, and velocity in the collection system, rainfall statistics, and a dashboard that shows key statistics related to overflow frequency and duration. The GIS-based interface can also provide high-level statistics on system performance, such as pipe capacity during wet weather (Figure 3), which can be used to identify potential locations for additional in-system storage. Since the digital twin integrates data and runs the collection system model daily, GLWA can quickly review system performance after storm events and compare model simulations to observed measurements to use as the basis for ongoing model and measurement improvements. APPLYING THE DIGITAL TWIN GLWA is using the PipeCAST digital twin for post-event analyses, where users review wet weather performance relative to the ROP goals. As an example, GLWA used PipeCAST to evaluate system performance for a recent wet weather event in July 2020. This event was 2.05 inches in 10 hours at the Wayne County Metropolitan Airport, and was approximately a 2-year, 1-hour event. The rainfall was most intense north of Detroit, as seen in the color-coded radar rainfall map in Figure 4. GLWA used the digital twin to evaluate how in-system storage and CSO control facilities conveyed flows from the Conant-Mt. Elliott Sewer that serves Oakland County and central Detroit (Figure 5). Flow and system performance were monitored during this event using the digital twin by reviewing incoming flow from Oakland County, in system storage, and performance at the Leib Screening and Disinfection Facility (SDF) (Figure 6). During this event, the incoming flow from meter SE-S-1, (blue line) peaked at approximately 245 cfs, followed by a short-duration peak from the local combined sewer drainage system in the DWSD collection system (meter DT-S-11, orange line). The in-system storage device, controlled by an inflatable dam, was activated, and no discharge occurred from the Leib SDF facility. Based on the review of data using the PipeCAST digital twin, GLWA was able to conclude that the system performed well during this large event, maximizing in-system storage, and minimizing discharges to the Detroit River. CONCLUSIONS GLWA developed a digital twin of its regional collection system to enable post-event analysis to support the ROP. The digital twin was developed using PipeCAST, a GIS-based tool that integrates metering data and modeling data into a platform that allows for rapid review and assessment of system performance during wet weather. The digital twin is being used to complete post-event analyses following significant precipitation events to further optimize wet weather operations, reducing CSO to receiving waters and maximizing secondary treatment at the WRRF.

Many communities across the U.S. suffer from routine and often severe flooding due to a combination of riverine impacts and old, undersized stormwater collection systems. But how many communities have the opportunity to develop detailed hydrologic and hydraulic models of both systems on a watershed scale? The City of Fayetteville NC had the vision and financial commitment to analyze drainage issues across all 12 of its watersheds. With its 12.0 square mile area and a stream length of 9.5 river miles, the Blounts Creek Watershed is the largest and most developed of the City's watersheds. A Master Plan was prepared for this watershed that included developing detailed 1D and 2D hydrologic and hydraulic models using HEC-HMS/HEC-RAS for the primary (riverine) system and ICM for the secondary (collection) system; performing a field assessment of high priority stream reaches; and identifying issues and problem areas using the modeling and field assessment results to inform required mitigation with new drainage solutions. The primary collection system was modeled using HEC-HMS and HEC-RAS modeling platforms. Local county pre-preliminary HEC-RAS models developed under a Countywide Flood Insurance Study (FIS) report update were used. The base models were reviewed in detail and updated to include new survey. A combination of 1D and 2D modeling techniques were used to represent the primary system operation. The secondary system was modeled using InfoWorks ICM. To improve project efficiency and best use resources, hands-on practices were coupled with automated methods to streamline hydrologic parameter and hydraulic network development. The project team created multiple ESRI based innovations including tools that identified the longest flow path and calculated the time of concentration for the surface runoff within each subcatchment as well as a tool that used model status codes within the GIS data to build InfoWorks ICM compatible model networks. The primary and secondary system models were run under several design storms and the model results were analyzed to define current levels of service as defined by the City. The primary and secondary system model results were mapped together to enable the City to fully understand how the systems impact each other and identify areas of significant surface flooding and structure impacts (Concern Areas). The results indicated that 135 locations experience significant flooding impacts, where the stormwater infrastructure (pipe, inlet, channel) does not meet the City's defined level of service. Specifically, flooding impacts were shown to significantly affect 47.2 miles of roadway, 13 road crossings, and 471 structures, as well as prevent accessibility to 328 structures. From the erosion assessment, four areas were identified as erosion concerns. These 135 areas were assessed, scored, and ranked based on severity of the flood or erosion risk. From this prioritization exercise, 101 areas were selected for further analysis to include developing proposed solutions and evaluating their ability to mitigate the flooding and erosion impacts. The selection of areas for development of proposed solutions was primarily oriented around mitigation of flooding in the public right-of-way. Structural flooding mitigation was evaluated as an auxiliary benefit to right-of-way improvements. Potential downstream impacts were also evaluated. Proposed solution conditions were then incorporated into the watershed models and flood risks were re-evaluated under future rainfall conditions. These proposed solutions range in size and complexity, from simple culvert upgrades to bridge refurbishments and floodplain development. The planning level estimated cost for design and construction of all 100 proposed solutions is $277,552,400. The proposed solutions were prioritized and one of them, totaling just over $20M, was selected to move forward to the current Capital Improvement Plan (CIP). The remaining proposed solutions are considered backlog for future years. This presentation will step through the overall program and vision of the City in establishing and implementing the watershed master plan program and the process of developing, validating, and integrating the 1D and 2D riverine and collection system models with several project innovations to efficiently and cost effectively develop a CIP program to mitigate stormwater flooding.

Bacteria impairments remain one of the most challenging water quality issues to address in Southern California, resulting in beach closures and unsafe conditions for recreators. The Upper Los Angeles River Watershed is pursuing an innovative method to address the Los Angeles River Bacteria Total Maximum Daily Load (TMDL) requirements. When the Bacteria TMDL was developed in 2010, a pathway towards compliance was established based on outfall monitoring data collected at the time to identify priority outfalls (consistently high E. coli loading rates) and outlier outfalls (episodically high E. coli loading rates) and a Load Reduction Strategy (LRS) to implement control measures to address. However, following years of implementation challenges and evolving understanding of human health impacts and risks related to bacteria impairments, an adapted, data-driven approach is now being used to reprioritize effort to focus on more feasible and effective strategies. Specifically, efforts are refocused on the highest risk source of illness-causing pathogens (i.e., human waste) and the highest risk areas of the watershed, where it is more likely illness-causing pathogens are present. A renewed emphasis is placed on targeted source control in management strategies. Recent studies demonstrate that human waste source control is a more cost-effective long-term approach to reducing pathogens associated with bacteria. Human waste typically contains a higher concentration of pathogens, thereby increasing the risk of gastrointestinal illness through recreational exposure. In response, the adapted approach in the Upper Los Angeles River expands on previous efforts with on-the-ground understanding of potential bacteria sources and the relation to public health risk. Human waste source control is a more cost-effective long-term approach to reducing pathogens relative to typical structural BMPs. Further, advancements in human marker tools-such as HF183-can better identify conditions under which pathogens are contributing to downstream impaired receiving waters. The Upper Los Angeles River Watershed is implementing this innovative risk-based prioritization, using advancements in source investigation tools, robust data collection and processing, and a newly developed human waste source identification and tracking toolbox to conduct human waste source investigations to reduce public health risks and help restore the beneficial uses of the iconic LA River. Robust data collection and processing was conducted across agency departments to shine a new light on potential dry weather flows and pathogen sources in the watershed and prioritization results used to delineate areas of investigation (AOIs), focusing limited management resources in areas posing the greatest risk. Human waste source investigations are being conducted in the top priority AOIs to isolate the contributing sources for targeted abatement strategies. This presentation will discuss the data-driven prioritization approach and selection of areas of investigation, the strategic risk-based monitoring being implemented, and the results and lessons learned from the human waste source investigations performed as part of the special study. The methods developed and employed in this watershed promise to materially improve bacteria management success in Southern California and beyond, available online as a template and for communicating progress through the Upper Los Angeles River: Load Reduction Strategy Adaptation Story Map (https://storymaps.arcgis.com/stories/466afe14077a436aabd8f072ed20ee2e).