Conference Papers

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. 

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.

Introduction Affinity Laws for pumps and fans are commonly known but why aren't they commonly known for decanter centrifuges? Dewatering performance has a large impact on overall wastewater treatment operations and understanding how modern decanter centrifuge technology has evolved is critical to selecting the correctly sized equipment. The optimized selection of a decanter centrifuge and its performance plays an important role in the cost of returned solids (solids recovery) and the cost of disposal (dryness of solids). The scaling methodology (Affinity Laws for Decanter Centrifuges) of capacity and performance becomes a crucial activity. The inner diameter of the bowl has historically been one of the main criteria for comparing decanter centrifuges. However, this approach has not been sufficiently accurate for the prediction of capacity or performance. The holding volume, geometry, and operating speeds all need to be compared. For this purpose, GEA has developed and validated a theoretical model by performing side-by-side field trials. The validation of the G x Volume affinity law (See Figure 1) demonstrates that G force combined with volume are reliable criteria for the scaling of capacity and performance of decanter centrifuges for dewatering in wastewater treatment plants. Hypotheses 1. Comparing geometrically similar decanter centrifuges with an equivalent volume with a higher G force would result in either a higher cake dryness or a greater capacity. See figure 2 2. Comparing decanters with a different bowl diameter but with the same G volume, the performance and capacity would be the same. See figure 3 Methodology 1. Side-by-side operation with two equivalent bowl diameter decanter centrifuges with different G-volume was performed at WWTP Langenberg, Germany, keeping other parameters such as sludge characteristics, concentration of infeed sludge and solids recovery identical. 2. Side-by-side operation with two different bowl diameter decanter centrifuges with an equivalent G volume was performed at WWTP Oldenburg, Germany, keeping other parameters like sludge characteristics, concentration of infeed sludge and solids recovery identical. 3. In both trials, the services of KBKopp (Dr. Julia Kopp) were utilized to determine the maximum sludge dewaterability. See figure 4 for photos of the test equipment and site Results The research establishes that centrifuges with an equivalent bowl geometry, but having different G volume owing to rotational speeds, will have an equivalent capacity at the same performance level or a different performance at the same capacity. The capacity and performance is directly proportional to the G volume difference, and only indirectly related to the bowl diameter. See figures 5, 6, 7 Implications The study brings forward 'G x Volume' as reliable criteria for scaling and selection of decanter centrifuges in wastewater treatment plant design and also brings a paradigm shift from conventional wisdom of bowl diameter as the comparative driver. The research helps in selection of centrifuges that get higher capacity per square meter space or significant reduction in cost of operation (disposal and polymer consumption) per cubic meter of sludge handled. In either of the cases, 'G x Volume' based selection drives towards optimized scaling for reduction in CO2 footprint and an efficient circular economy. The Future The development and use of Affinity Laws for Decanter Centrifuges is on-going and is expected to result in more economically efficient and environmentally friendly operations.

ABSTRACT A brewery wastewater treatment plant (WWTP) experienced high hydrogen sulfide (H2S) concentrations in and around the biosolids handling building which led to concerns around worker safety, overloading of the existing odor scrubber, and odor complaints from the surrounding neighborhoods. The Brewery WWTP dewaters a total of 250,000 300,000 gallons per day of mixed primary and waste activated sludge (biosolids). Of the total flow to the dewatering presses, 80% is from the brewery and the remaining 20% from a nearby municipal wastewater treatment plant. Historically, the brewery fed sodium permanganate ahead of the belt filter press in an effort to reduce H2S odors in and around the biosolids dewatering area. A second permanganate dosing point of was added in 2021 to address the continued odor complaints. Later in 2021, both permanganate injection points were decommissioned due to operational concerns. Permanganate was also suspected of contributing to elevated manganese levels at the effluent due to release of manganese in the filtrate. In early 2022, the brewery WWTP embarked on a 90-day field trial of Peroxide Regenerated Iron Technology (PRI-TECH ®) to address H2S odors generated in the biosolids dewatering facility and also eliminate a source of manganese in the final effluent. For H2S control, PRI-TECH ® functions in two ways: 1) Direct oxidation of H2S by hydrogen peroxide (H2O2) and 2) regeneration of bound iron (e.g, FeS) in-situ, yielding either free ferrous (Fe2+) or ferric (Fe3+) iron and colloidal sulfur. This regenerated iron is now available to bind additional H2S in the biosolids handling process, functioning the same as if fresh iron salts were being added. Pre-trial laboratory testing showed that there were already significant levels of total available iron present in the brewery biosolids (15 25 mg/L total Fe). This equates to 35 40 lbs. per day of iron that was available for regeneration. In this case, the iron needed for PRI-TECH ® was already present in the biosolids and could be used for the benefit of H2S control in the belt filter press area. For the PRI-TECH ® trial, hydrogen peroxide was fed into the combined biosolids line upstream of the belt filter presses to oxidize H2S and regenerate free iron (Fe+2, Fe+3). Baseline (untreated) H2S levels at the belt press ranged from 5 90 ppm with an average above 10 ppm. The brewery safety committee set the H2S compliance target below an average of 10 ppm during dewatering operations to ensure worker safety and to reduce complaints from surrounding neighborhoods. Trial results showed that PRI-TECH ® reduced the sulfide levels by >95% with operational vapor level averages <1ppm inside the belt filter press room. Operations noticed a substantial reduction in local and personal H2S alarms (alarm at 10 ppm) in and around the dewatering building, local odor complaints also decreased, and there were no effluent manganese violations since beginning the PRI-TECH ® program, supporting compliance with metal discharge limits. Based on the successful trial results, the brewery WWTP will continue utilizing PRI-TECH ® to maintain effective H2S control in the dewatering facility to ensure worker safety and maintain effective H2S odor. Future work is planned to further optimize PRI-TECH ® program, with additional investigation into the improvement in critical metals reduction.

A 'cloudburst' is a sudden, heavy downpour that can overwhelm sewer systems and result in flash floods. These intense rainfalls are becoming more frequent, disruptive, and damaging in New York City (NYC); devastating residents, destroying homes, and disrupting businesses. On September 1, 2021, Hurricane Ida shattered the record for the highest single-hour rainfall in NYC, set only two weeks earlier by another extreme storm, Tropical Storm Henri. Both storms caused flooding, damaged property, disrupted critical infrastructure, and polluted New York's rivers and Harbor. NYC's Cloudburst Program will protect vulnerable communities, mitigate flood damage, and improve water quality. Historical data measuring which neighborhoods were hit hardest by Hurricane Ida were used to identify cloudburst planning areas, including flood extents with sea level rise, structural damage reports, sewer backups, and social vulnerability index. All the recommended Cloudburst projects are in flood-prone environmental justice areas. This project redefines stormwater management in the built environment by transforming streets, parks, and other open public areas into multi-functional community assets for recreational use and flood mitigation. Stormwater runoff from sidewalks and streets is absorbed by porous parking lanes, bike lanes, or medians and then transferred into redesigned public spaces that safely accommodate flood waters. After a storm has passed and sewers have regained capacity, the water drains back into sewer systems. This project is the first large-scale innovative application of interconnected green infrastructure for cloudburst management. NYC's ultra-dense built environment is congested and presents complex challenges that require meticulous coordination among multiple private and public agencies. Further, the complex drainage network requires careful consideration to maintain gravity flow. These challenges were addressed through interagency partnerships, stakeholder consensus building, sewer system modeling, and developing cost-effective integrated solutions. Cloudburst stormwater management integrates flood-protection solutions into public spaces, instilling a positive public perception of how engineering solutions can complement community goals. Integrating public amenities and open spaces with stormwater management solutions, such as sunken basketball courts, water squares, and playgrounds with subsurface storage, transforms these public spaces into multi-beneficial community assets. Based on recommendations from this project, the city announced $400 million in the construction of Cloudburst Resiliency Projects to better manage intense rainfall events in flood-prone neighborhoods. This presentation will cover: 1) NYC Cloudburst Program Goals 2) Social and Physical Vulnerability Assessment 3) Opportunity Screening and Adaptation Analysis 4) Cloudburst Adaptation Toolbox 5) Social, Economic, and Sustainable Design Considerations.

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.

PURPOSE
The presentation will provide an overview of the City of Raleigh's Public Utilities Department, Raleigh Water (Raleigh Water) complex collection system odor and corrosion challenges, current approach to treating and handling odor and corrosion, and how modeling was used to evaluate hotspots and optimize treatment. The presentation will benefit the industry by providing integrated approaches to collection system odor and corrosion control assessment, design criteria, planning, and detailed treatment solutions through advanced sewer modeling.

PROBLEM STATEMENT
Raleigh Water is grappling with a complex and rapidly growing collection system with interceptors of varying age and materials, both concrete and inert. Due to the complexity and frequent changes, the system has areas at high risk of high hydrogen sulfide, potential odor nuisance, and corrosion. Raleigh Water maintains an active odor control program with the goal of addressing elevated and consistent odors within the wastewater collection system. The odor control program includes a liquid chemical feed program in which different odor control chemicals (ferrous sulfate, hydrogen peroxide, and calcium nitrate) are added to the wastewater at different strategic points within the collection system to reduce and/or suppress the formation of hydrogen sulfide. Routine monitoring of liquid and gaseous hydrogen sulfide levels is conducted to assess performance at the different dosage locations and to identify any needed adjustment to chemical feed rates. In addition to the chemical dosage program, Raleigh Water also has vapor phase odor treatment systems at several of its regional pump stations to treat the odorous air collected at the pump station. Raleigh Water's strives to build a programmatic system approach for odor and corrosion. Although the Raleigh Water has an expansive chemical dosing system in place that has had success, there are still gaps and areas in need of improvement. Raleigh Water recognizes these gaps and has a goal to optimize their system both for treatment and cost efficiency, while also minimizing elevated and consistent odors system wide.

BACKGROUND AND METHODOLOGY
Raleigh Water operates a collection system that spans over 2,500 miles of pipe, both gravity and forcemain, and conveys wastewater to one of three resource recovery facilities. Figure 1 shows Raleigh Water's collection system, locations of pump stations, dosing stations, and resource recovery facilities. The odor control treatment program is comprised of liquid treatment at more than 20 chemical dosing stations (varying chemical usage) and several vapor phase systems throughout the collection system. The chemical dosing stations throughout the collection system treat the system with different chemicals depending on the location. Calcium nitrate, iron, and peroxide are used throughout the system. In 2017, Raleigh Water completed an odor and corrosion control master plan that evaluated the ongoing treatment program for areas of improvement and potential areas in need of treatment. This was completed through extensive sampling, both liquid and gas phase, and collection system modeling. In 2022, HDR, The WATS Guys, and Raleigh Water worked together to build upon the findings from the previous master plan and assess Raleigh Water's collection system for odor and corrosion control using the Wastewater Aerobic/Anaerobic Transformation in Sewers (Mega-WATS) model. The Mega-WATS model was used for the project because it analyzes and solves complex in-sewer transformations including microbial-induced concrete corrosion, odor formation, and potential for nuisance risk caused by hydrogen sulfide air emissions from pressurized sections of the sewer. Additionally, the model can predict anticipated effects and results of utilizing hydrogen sulfide control strategies, both liquid phase and vapor phase throughout a collection system. The model was used as a key tool in an integrated master planning effort that began in January 2022 and will be completed in December 2022, providing integrated approaches to collection system odor and corrosion control assessment, design criteria, planning, and detailed treatment solutions through advanced sewer modeling. The analysis was done using two modeling scenarios:
1. 2022 average weather and flow conditions
2. 2025 projected average weather and flow conditions

The 2022 model was calibrated using 2015 sampling data as well as updated sampling data completed in June 2022. The model input parameters incorporated existing chemical dosing and vapor phase treatment information to represent field conditions and predict the level of hydrogen sulfide control within the system. The 2022 model findings were evaluated for corrosion risk and areas with high concentrations of hydrogen sulfide in comparison with known odor complaint locations.

RESULTS AND FINDINGS
The 2022 model results were used to determine odor and corrosion hotspots throughout the entire collection system. These hotspots were detected by assessing areas with model predicted hydrogen sulfide presence, known odor complaints, and/or model predicted corrosion. Plots similar to Figure 2 were used to define the hotspot areas and prioritize them based on parameters such as: hydrogen sulfide presence, odor complaints in the area, known high risk asset, high predicted corrosion rate, and known planned monitoring or replacement. The presentation will provide a more detailed assessment of the hotspots and how they were evaluated and prioritized from the modeling results. The 2022 odor and corrosion hotspots were used to develop over ten capital improvements solutions as well as potential operational changes. The developed solutions were primarily related to adding chemical dosing sites in areas with hydrogen sulfide hotspots that were not already being treated, as well as pilot testing different chemicals and combinations of chemicals along flow paths to assess for improved and optimized treatment. One specific flow path evaluated is made up of several oversized forcemains and has an overall detention time of more than 60 hours. The flow path currently has three chemical dosing sites that treat the line with calcium nitrate upstream and iron followed by peroxide downstream. Although his treatment combination has helped mitigate some of the hydrogen sulfide formation, there is still concern for corrosion and odor along the flow path. The project team completed a desktop evaluation on the flow path and found that the addition of a pH adjustment (to a pH between 8-9), such as magnesium hydroxide, upstream of the iron dosing improved the iron's precipitation capabilities with dissolved sulfide. The combination of pH adjustment followed by iron was predicted to be an effective chemical optimization strategy on other flow paths in the system as well. The model also predicted downstream pH with these chemical combinations matched would not adversely impact the resource recovery facility. The team has recommended pilot testing in various locations in the collection system to validate the treatment combination. This presentation will provide the detailed flow path findings, results, evaluation (economic and non-economic benefits), and recommendations that evolved throughout the project. The presentation will provide insight and potential mitigation solutions for other utilities experiencing problematic hydrogen sulfide levels, odorous air, ineffective chemical treatment or corrosion throughout their collection systems.

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.

The City of Modesto, California had a problem: 17.3 million gallons per year of stormwater flows in its Emerald Sewer Trunk Line meant potential big-ticket upgrades to both the Trunk and the City's Sutter Avenue Wastewater Treatment Plant. But the City saw an opportunity for a better approach. Like many arid parts of the Country, Modesto has been looking for ways to capture and reuse wet weather runoff, given periods of sometimes extended drought and increased demand on both surface and overdrafted groundwater. The City's bright idea was an ambitious new $30 million dollar capture, treatment, and groundwater recharge system at its 6-acre J. M. Pike Park. The project, currently in construction, is the largest of four sites being re-imagined in order to remove stormwater cross connections to the sanitary sewer and non-functioning dry-wells that have historically contributed to significant wet weather flows to the Plant, avoiding future costly capital improvements to the Plant and reducing localized neighborhood flooding, while refreshing the Park. The Project's objectives are being achieved through the construction of 11,700 feet of new storm drain collection, designed to convey stormwater from 9 cross connections and 36 rock wells to JM Pike Park (Park). A subterranean retention system located under the Park will hold 21.3 acre-feet of runoff from over 100 acres and infiltrate into the underlying soils within 24 hours. Stormwater will be pre-treated in two locations to remove trash, sediment, oils, greases, and other substances prior to entering the retention system. While the Park has recently upgraded play areas, this project provides an extensive rehabilitation to improve operations and maintenance, accessibility, and aesthetics. Existing turf and irrigation systems are being replaced with more water efficient turf varieties and drought tolerant trees and plantings. The irrigation system for trees is being separated from turf irrigation to allow turf to dry while trees remain watered, which enhances conservation during droughts. Rain gardens are being constructed to capture and treat runoff from the impervious surfaces in the Park. New walking paths, lighting and seating are being added, and all facilities are being reconstructed to satisfy the Americans with Disabilities Act (ADA). The City is also capitalizing on the construction within its rights-of-way to replace 23,500 feet of under-sized, low-pressure water mains in neighborhoods around the Park. Existing steel pipes are being replaced with PVC mains and relocated from alleys into public rights-of-way to facilitate future access and maintenance, improve system reliability, flows, and pressures. Fire hydrants, meters, and system appurtenances are also being replaced to City standards. This project's design is complete, and construction is expected to be complete by October of 2024. The Park's reimagining represents a true multi-objective stormwater capture and re-use project: eliminating wet weather flows to the Plant, reducing neighborhood flooding, enhancing public recreational space, improving the resiliency of the public water supply and making public rights-of-way more accessible to the Community. This presentation will highlight a successful approach for reducing wet weather flows at scale. The audience will benefit from learning about the development and implementation of one of the largest public projects of its kind. The presenters will focus on sharing design and construction lessons learned, as well as the City's strategy to leverage available funding to achieve broad public benefits to the local community, including funding and partnership strategies that can help communities across the nation remove roadblocks to cost saving implementation. Audience participation will be encouraged through engaging question and answer periods throughout the presentation, allowing for discussion of specific challenges and opportunities of these types of projects.

This presentation will demonstrate how Goleta Sanitary District (GSD) benefited from having a flexible bioenergy recovery plan and analytical tools to adapt to changing external factors such as funding availability, capital costs, biosolids hauling costs and evolving emission regulations. Attendees will learn the value of revisiting previous decisions when new data becomes available or conditions change and the advantage of having an analysis tool to visualize new outcomes. GSD developed a Biosolids and Energy Strategic Plan (BESP) in 2019 to better capitalize on the energy available from gas produced by their anaerobic digesters at the Goleta Water Resource Recovery Facility (WRRF). The project team used an interactive energy, mass, and financial balance tool (Energy Balance and Analysis Tool - EBAT) to evaluate the benefit from multiple bioenergy recovery alternatives including a combined heat and power (CHP) system, renewable natural gas and sludge drying. Digestion expansion, gas storage and CHP were recommended for the near team. Construction of a biosolids dryer was recommended for solids management about 10 years after digestion expansion to reduce hauling costs and produce a Class A product. GSD began preliminary design work in 2020 to implement the recommendations from the strategic plan. The design included a CHP system with a 450kW digester gas fueled engine generator, digester gas treatment, emissions controls to meet the regional emission limit rules, and a gas storage sphere to provide a consistent gas supply and operational flexibility for the CHP engine. The CHP system would initially operate at 75 percent of its rated output, increasing to full output upon implementation of the planned fats, oils, and greases (FOG) co-digestion program. During the preliminary design phases several external factors changed that extended the payback period of the recommended bioenergy recovery strategy (CHP), including: 1.Capital costs of the CHP engine increased 5-10 percent due to the increasing costs of raw materials. 2. Dialog with the Santa Barbara County Air Pollution Control Department (SBCAPCD) indicated that the 450kW engine would fall under the 'Best Achievable Control Technology' (BACT), requiring continuous emissions monitoring system (CEMS) and a higher level of emission reduction equipment which would increase operating costs. 3. Biosolids disposal and hauling costs increased at a higher rate than expected and could justify expediting the sludge dryer installation. As these conditions evolved, the EBAT model was used to re-examine the long-term bioenergy recovery strategy to determine if an alternative strategy would provide a higher level of value. The team tested many different energy scenarios simultaneously. Scenarios were various combinations of one 450 kW engine generator, one or two 160 kW engine generators, SCR and CMS, and funding received from the Self Generation Incentive Program (SGIP). GSD and the design team discussed the risks and benefits of moving forward with a larger system compared to a smaller system such as availability of grants to fund the project, capital at risk, disruption to operations during construction and adaptability to capitalize on future plant modifications such as co-digestion. As demonstrated in Figure 1, the analysis found that the 160kW CHP system provided a shorter payback period than the 450kW system (13 years vs 22 years) primarily due to the lower capital costs per kW, which was achieved by removing the need for digester gas storage and the continuous emissions monitoring system. While the smaller CHP system would not use all the digester gas produced, the addition of a thermal dryer in the near term (at about 5 years) could provide a means to beneficially utilize the digester gas volume that exceeds the CHP capacity. To test this idea, the team again returned to the EBAT model, incorporating the dryer into the financial and energy balance calculations. The adjustable inputs within the model such as dryer uptime, dryer installation year, FOG co-digestion volume and revenue from FOG tipping fees were varied to understand the individual and cumulative impact on the financial outcome of installing a dryer in the near term. GSD used the interactive, Power-BI based dashboard to experiment independently with CHP sizes, dryer installation years and capital cost reductions from funding opportunities. Figure 2 is a screen shot of the EBAT dashboard. Ultimately, the EBAT model guided GSD to select the smaller CHP system as the bioenergy recovery strategy that provides them higher value with less capital risk. The installation year for a thermal dryer is still under evaluation. This case study illustrates the importance of continuously evaluating and comparing different bioenergy alternatives as conditions such as capital costs, emission regulations, hauling costs, market conditions and other variables evolve during the development of a bioenergy recovery project. The development of a flexible long term bioenergy recovery plan as well as an interactive bioenergy recovery analytical tool provided GSD a means to easily navigate changing conditions and ensure the optimal solution in implemented.

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.

The Western Virginia Water Authority (Authority) is completing a two-phase project at the Roanoke Regional Water Pollution Control Plant (WPCP) to rehabilitate and upgrade the existing anaerobic digestion system and implement a new digester gas conditioning system (DGCS) to produce renewable natural gas (RNG). The RNG will be injected into the local gas utility's (Roanoke Gas Company, RGC) nearby distribution system to generate and sell Renewable Identification Numbers (RINs). Upon its completion, the facility will be the first biogas to pipeline process of its kind in the Commonwealth of Virginia. The first phase of the project includes structural, process mechanical and electrical improvements to five 1.1-MG primary digesters. The digesters are of concrete construction and were originally built in the 1950s & 1970s. Drone technology was used to inspect and assess structural defects within the five digester tanks. Three concrete covers are being replaced with new concrete covers and an elastomeric coating system to improve the capture efficiency of biogas. The second phase of the project would not have been possible without the close collaboration between the Authority and RGC. A feasibility study was conducted to assess overall project economics and gauge RGC's interest in accepting RNG/ partnering on the project. Membrane separation was selected as the preferred technology for carbon dioxide removal and RGC provided minimum RNG quality specifications (higher heating value, carbon dioxide, oxygen, hydrogen sulfide, moisture, pressure, etc.) required for injection. A life cycle cost evaluation considered two methods of tail gas treatment and several DGCS manufacturers. Tail gas treatment methods included a regenerative thermal oxidizer (RTO) and a third membrane pass to reduce methane discharge to less than 1.5%. Although the third membrane unit carried a greater capital cost, it had a similar life cycle cost due to additional methane recovery and RIN revenue (due to greater methane capture). A third membrane pass was selected since it can be provided within the DGCS enclosure, avoiding the need for a separate piece of equipment that must communicate with the DGCS. A sensitivity analysis was performed to assess the risk of variable D-3 RIN prices and operation and maintenance (O&M) costs. As shown in Table 1, this analysis found that the pipeline injection system would generate revenue over a 20-year period if the average RIN value is maintained above $1.35. Once the digester upgrade (phase 1) is complete, average biogas production is estimated to range from 300,000 & 320,000 cubic feet per day. The DGCS manufacturer was pre-selected concurrently with the final design phase through an evaluated bidding process. Technical and cost proposals were solicited from three DGCS manufacturers. The manufacturers were scored based on: 1. Quality of Proposal 2. Cost 3. Experience and Qualifications 4. Warranty 5. Service Capability 6. Installed Horsepower References from a total of six operating utilities were contacted to support the Experience and Qualifications scoring. The overall highest ranked manufacturer was selected unanimously and was not the lowest cost. The selected manufacturer worked closely with the project team to create shop drawings in conjunction with final design efforts. The Authority and RGC came to an agreement that RGC would own and operate the DGCS and interconnect facility, and purchase raw biogas from the Authority. Although the Authority initiated the DGCS equipment procurement, RGC purchased the equipment shortly after the change in ownership was confirmed. Once all operating and maintenance expenses and RIN revenues are quantified after the first year of operation, the Authority and RGC will mutually agree to a division of profits. RGC continues to evaluate the following options for selling RINs; 1) selling RNG directly to an end user capable of utilizing the gas for transportation fuel, 2) solicit a third-party carbon broker to sell the RNG and environmental attributes to generate, document, register, market and monetize RINs, 3) sell the RNG themselves and manage the offtake agreements, tariffs, provisions and all other accounting aspects. The project is on schedule to start injecting RNG into the natural gas grid in Fall 2022. This paper will present the life cycle cost evaluation, provide insights on the design-concurrent best value manufacturer selection, and discuss the arrangement between the Authority and RGC to share in project costs and revenues.