Conference Papers

Hydraulic models are used throughout the United States and worldwide to plan sewer infrastructure improvements and evaluate system operations. Increasingly, utilities include force mains and pump stations in the hydraulic model and use them to evaluate upgrades for existing pump stations and development of new pump stations. Modeling force mains that can be intermittently under pressure, half full, or in vacuum in the sewer system is a challenging aspect of the model build process with various modeling applications. Orange County Sanitation District (OC San) provides wastewater collection, treatment, and recycling for approximately 2.6 million people in central and northwest Orange County, CA. OC San owns, operates, and maintains 4 wastewater pump stations which are interconnected via 2 parallel force mains (Newport Force Main, NFM) along the Pacific Coast Highway (PCH) in the City of Newport Beach, CA. The NFM network, shown in Figure 1, consists of three-manifold pump stations, Bay bridge Pump Station, Rocky Point Pump Station, Lido Pump station, and parallel force mains that convey wastewater to the Bitter Point Pump Station. The Bay Bridge Pump Station (BBPS), the farthest upstream pump station of the NFM network, is currently in design for its replacement. As part of the Bay Bridge Pump Station replacement project, OC San and Arcadis (OC San's engineering consultant for this project) developed a new hydraulic model of the NFM network using InfoWorks ICM (10.0) software to select new pumps at the pump station. The Infoworks ICM modeling application has two modeling options for modeling sewer force mains. Both of these options, listed below, can result in different hydraulic profiles, which can affect the pump selection for the BBPS. - Pressure Solution: The 'Pressure' solution model uses pressurized pipe equations when the pipe is fully pressurized. The model reverts to the gravity solution whenever the pipe is not full during low flow conditions and subsequently uses gravity solution for the rest of the simulation. - Force Main Solution: The 'Force Main' model is an advanced solution to model pressurized pipes, which assumes the pipe is always full and uses the pressurized pipe equations for all flow regimes during the simulation. Thus, the 'Force Main' solution model allows suction pressures to develop in the pipes and accounts for siphoning effect during the simulation. The NFM network is relatively flat with local high points and minimal air release. Therefore the total dynamic head for pumps at BBPS is primarily correlated to headloss and can be subject to localized siphons and changes to gravity flow. To determine the potential affects of siphons and flow regime changes, OC San analyzed the NFM hydraulics using both the Pressure Solution and Force Main Solution under low flow and high flow conditions to determine most accurate representation of the NFM network. The results are shown in Figures 2 and 3. - The Force Main solution results in the lowest hydraulic grade line (HGL) during the low flow conditions (Figure 2) because Force Main Solution accounts for a siphoning effect that can happen when pipelines with local high points have HGL below the crown of the pipe. The siphon pulls the water over the high point, resulting in a lower grade line for points upstream of the high point. - The Pressure Solution results in a low HGL compared to the ForceMain solution during the high flow conditions. The Pressure Solution reverted to a gravity solution during the simulation that can happen when the pipe is not fully pressurized. The gravity solution underpredicted flow attenuation and a low flow velocity, resulting in lower head-loss and low HGL. OS San selected the Force Main Solution to model the NFM network for the Bay bridge Pump Station design. The Force Main Solution is expected to provide the most accurate model of the NFM network and is the most conservative, requiring a lower total dynamic head (TDH) for consideration during pump selection.

INTRODUCTION The Town of Cary, NC Utilities Department serves a population of roughly 175,000. Cary is a regional leader in sustainability and climate change mitigation with an ambitious goal of reducing town wide GHG emissions by 25 percent by 2025 and by 100 percent by 2040. A high-level study conducted in 2011 showed water and wastewater services account for approximately 60 percent of Cary's municipal GHG emissions. More recently, in conjunction with GHG emission accounting research led by the Stantec Institute for Water Technology and Policy, Cary developed a comprehensive emissions inventory for their three water reclamation facilities (WRF), one water treatment facility (WTF), and one major pump station to both measure progress related to emission reduction activities and to incorporate GHG impact analyses in alternative selection processes. One of the WRFs included in the inventory is the 18 million gallon per day (MGD) Western Wake Regional Water Reclamation Facility (WWRWRF), commissioned in 2014 and discharging to the Cape Fear River. The WWRWRF solids handling facility includes belt filter press thickening of waste activated sludge (WAS) and thermal drying via two BioCon dryers with a combined capacity of 1,489 wet pounds per hour. The dried biosolids are processed through a pelletizer and distributed as a Class A product for land application. The facility's original design included an energy recovery system (ERS) that would combust dried biosolids to generate heat for the drying process, thereby offsetting natural gas consumption. The ERS was removed from the design with the intent to revisit installation in the future. In October 2022, Cary commissioned Stantec to assess the GHG emissions impact of installing an ERS using the newly developed GHG inventory tool. The purpose of this paper is to provide an overview of Cary's GHG emission inventory tool, understand is applicability for utilities of all sizes and treatment technologies, present the results of the GHG emission impact analysis and provide considerations for incorporating GHG evaluations in facility planning and alternative selection processes. METHODOLOGY Cary's GHG was developed for a baseline year of 2021 and is an Excel-based calculator specifically focused on water and wastewater facility emissions. The calculator sources reference data and equations from the Local Government Operations Protocol, IPCC Guidelines, EPA GHG Emission Factors Hub, EPA Waste Reduction Model, and the Biosolids Emissions Assessment Model (BEAM). The tool was developed with a user-friendly interface and can be quickly updated annually to monitor emissions over time or applied as a decision-making tool by comparing capital improvement or operational optimization alternatives. Energy recovery systems accept and combust dried biosolids from a dryer and recover the waste heat from the combustion process for dryer operation. The end product is ash, which can either be disposed via a landfill or beneficially reused as a construction material amendment. The heat produced by the ERS offsets the natural gas required to heat the dryer. WWRWRF's 2021 GHG inventory was used to assess the theoretical GHG impact of installing an ERS. Installation of an ERS is anticipated to impact GHG emissions in five areas: 1.Reduced natural gas combustion by the dryer 2.Reduced GHG offset from biosolid land application 3.Reduced end-product hauling 4.Increased electricity consumption from ERS equipment motors 5.Increased direct emissions from combustion processes There are several energy recovery technologies available to WRFs. However, this evaluation assumed the Veolia ERS system would be installed as it is designed to integrate with the BioCon dryers already in operation at the WWRWRF. The design criteria assumed a throughput of 1,489 lb/hr, consistent with the existing dryer system nameplate capacity and energy consumption estimates were provided for the full system capacity and are summarized in Table 1. The GHG impact from the ERS was assessed for 2021 only and during that year the WWRWRF dryer throughput averaged 636 lb/hr. Electricity consumed by the ERS system was estimated by multiplying the expected energy draw at design capacity by the ratio of the actual and design loads. The ash production rate is approximately 40 percent of 2021 dried biosolids production rate and the average hauled distance for ash disposal was assumed to be 30 percent of that of biosolids land application. Based on Veolia-reported values, the ERS is assumed to provide 68 percent of the dryer's heat demand and the remaining is provided by natural gas combustion. While the ERS does require some consumables for flue gas treatment such as urea, emissions associated with its transport were not included as consumption is estimated at less than one tote per year. In addition, no changes in facility or administrative costs were assumed. There is not current guidance on GHG emission estimates from an ERS. Therefore, solids combustion emissions were calculated using the 'Combustion' tab in BEAM, which is specifically intended for solids incinerators. BEAM calculates Scope 1 emissions from solids combustion as well as the biogenic CO ‚‚ emissions that arise from the conversion of the organic matter in the solids to CO ‚‚. Per LGOP and IPCC guidance, biogenic emissions can be estimated and monitored but do not need to be included in a facility's inventory. RESULTS Results of the analysis are presented in Table 2 and Figure 1 and show the existing and theoretical (with ERS) emissions in 2021. The results of this analysis show that installation and operation of the ERS system would have increased 2021 solids handling related GHG emissions by 36 percent. Nearly all of the ERS combustion emissions are as nitrous oxide, which is particularly difficult to estimate, with significant variability in emission factors. As such, actual emissions may vary based on how well the energy recovery system is maintained and operated. The difference in GHG emissions is also heavily influenced by the elimination of land application practices, which currently provide Cary with a significant emission offset. This is demonstrated in Figure 1, which shows there would not be any 'negative' emissions without land application practices. As previously mentioned, Cary may beneficially reuse the ash product for construction materials, but this practice is not expected to provide the same magnitude of offset since it does not directly increase carbon sequestered biomass. While a more complete evaluation of all financial, environmental, and social impacts of the technology alternative is recommended, this work demonstrated Cary's ability to quickly and effectively quantify the GHG emission impact of a technology alternative. In addition, this evaluation revealed the tradeoffs within the circular economy as an alternative intended to reduce reliance on fossil fuels may result in reduced production of value beneficially reused biosolids.

Vapor-phase odor control systems are often comprised of one or more cylindrical tower scrubbers, ductwork, mist/grease eliminators, fans, pumps, ladders, platforms, instrumentation & custom control panels. As these systems get larger and the layout more complicated; design engineers should be aware of the adaptability of the system, the materials they're working with, and how to improve their design for the people who will be tasked with its long-term successful operation. Functional design is crucial in tying these components together, ensuring that the end-user will work in harmony with the equipment and not against it. Consider the 'payback' in time & safety of a few hours spent optimizing the footpath of an operator when the equipment will be in use for 25 or more years. The following should be a priority of an odor control system design once the basic equipment selection, sizing and placement has been determined: 1.Receiving feedback from the end users, operators, and maintenance staff, understanding the feedback, and representing their needs & concerns in the design. 2.Identifying safety concerns (e.g., tripping hazards, head injuries, falls, chemical exposure or access to safety showers, confined space entry) within either planned pathways or 'desire paths' for improved accessibility, and lower O&M risk and effort level. 3.Evaluating the equipment location, orientation, points of operator or maintenance interaction in a 3D environment and identify and design the efficient pathway through these points. 4.Updating standard equipment specifications with these features to form lasting improvements as well as emphasizing the latest in robust & low-maintenance instrumentation. This presentation will provide a methodology for improving O&M in our odor control systems, specification suggestions as well as compilations of WWTP staff experiences from a few large wastewater treatment plants in Southern California. Namely, Orange County Sanitation District, whose employees possess a treasure trove of experience in operating and maintaining large scale odor control systems and their design with the operator's safety and accessibility in mind.

Odor Control Technology isn't Enough Without Effective Capture Effective odor control is not just about the technology, it is also about the capture and containment of the odor. Choosing and sizing a wet scrubber or any odor control technology is critical, however the best technologies are insignificant if nuisance odors continue to escape before they can be treated. Such issues with capture and containment of odor were present at Orange County Sanitation District (OC San) Plant No. 2 biosolids Truck Loading facility. OC San Plant No. 2 is located in Huntington Beach, California, along the Santa Ana River (which has a raised walking/bike path) and is located near residences, Huntington State Beach, a few parks, and some commercial properties. The Plant is currently treating an average wastewater flow of approximately 60 million gallons per day (MGD). The function of the Truck Loading facility is to store the dewatered biosolids and to load to the hauling trucks for offsite beneficial reuse. Newly installed centrifuges, which improved biosolids dewatering, increased odor generation at the storage and Truck Loading facilities and triggered complaints by plant personnel and community members. To address these nuisance odors, a scientific approach was implemented that consisted of four main parts: gathering data, targeted sampling, air movement monitoring, and designing a custom air capture system based on the information collected in the previous steps. This paper will provide an overview of the approach utilized and highlight key elements that aided in understanding and solving the problem. Gathering Data: A series of questions were asked to find where and when the problem was occurring. To understand and solve the problem, collaboration with the OC San Maintenance, Operations, and engineering staff was crucial. Through this collaboration, it was determined that the odor in the Truck Loading bays was caused by the centrifuge-dewatered biosolids in the truck loading operation. Odors were released when the biosolids dropped through the storage silo knife gate valves and filled the truck trailers. Odors continued to be released from the accumulation of biosolids on surfaces of the truck and Truck Loading bays from the loading process. Minor system contributors included fugitive odors where biosolids accumulate but were difficult to clean, including the floor grates associated with the truck scales, which trap biosolids from washdowns. This information determined that the central issue surrounding the Truck Loading facility was the lack of containment infrastructure. Continuous dataloggers were installed to identify the pattern of hydrogen sulfide and ammonia occurrence throughout normal operations for several weeks. Trucks generally drove into the loading bay from the north, where a door closed behind it, to prevent the wind from blowing the odor out through the facility. The original design of the building assumed that winds would dominate from the south side, and that thus air would be sufficiently contained by the door on the north while ventilation drew out the foul air. The presence of odors indicated that this design was less effective than anticipated in capturing the stronger lingering odor, and further analysis was needed to determine the best containment and ventilation approach. Targeted Sampling: Next targeted sampling was conducted to quantify the odor by pinpointing the constituents of the odor, and their concentrations so that effective capture and containment can be customized. This sampling and analysis measured a complete set of odor-causing constituents such as hydrogen sulfide and ammonia on a continuous basis as well as grab samples for other speciated reduced sulfur compounds/VOCs during the most concentrated periods of Truck Loading, at the higher areas of the loading bay, as well lower regions of the bays (Understanding that the mix of compounds present consisted of both heavier and lighter than air compounds). Air Movement Monitoring: Air movement in the Truck Loading bays was simulated using a series of smoke tests for both existing and considered future conditions. The smoke tests were conducted with smoke candles that released a large amount of smoke (up to 40,000 cubic feet) within a small period of time, to simulate the sudden release of odor while the trucks were being loaded. Each test simulated either existing or potential ventilation conditions. Potential conditions included simulating the presence of a door on the south side of the building, differing ventilation rates, and differing quantities of supply air provided. By observing the movement of the smoke during this array of conditions, conclusions were drawn about the movement of odor throughout the truck bay, including the locations of dead zones, the effectiveness of an additional door on the south side for containment, and the effectiveness of the existing ventilation system at clearing air through each region of the truck bay. The smoke tests made it clear that a second door was necessary to contain the smoke within each bay. Tests which simulated a door made clear other weaknesses with the existing ventilation system's layout, including dead zones near the ceiling. Design of a custom system: The above tests and observations indicated the specific problems that were causing issues with odor control at this particular facility. Alternatives evaluation and conceptual design of improvements to the system were entirely customized to the height and length of the building. First, a door was recommended on the south side of the Truck Loading facility, to contain the odors within the building. Positive air supply was recommended at low and high heights to move foul air with odorants heavier than air observed in step 2, and sweep dead zones found near the ceiling in step 3. A U-shaped exhaust duct layout at ceiling level was recommended to capture the most concentrated foul air on both sides, where the smoke tests indicated most of the smoke was accumulating. The above method of identification of the distinct contributors to the odor control issue at this facility was instrumental in creating a custom design to address the concerns thoroughly and efficiently. Without the observations and collaboration in the earlier steps, the conclusions that allowed for a custom solution would not have been possible.

With five municipalities Burlov, Eslov, Lomma, Lund and Malmo and half a million customers, VA SYD is one of Sweden's largest agencies for water distribution and sewage collection and treatment. VA SYD need a digital solution to minimize the impact of flow variations due to extreme weather events, improve water quality in receiving water bodies, attenuate flows to the wastewater treatment plant, and reduce sewer overflows. Also, if sewer overflows could not be avoided, the agency needed to control where the sewer overflows occur in order to minimize environmental impacts. VA SYD implemented a digital twin hydrologic and hydraulic model in the city of Lund, covering the entire service area draining to the Källby wastewater treatment plant. The digital twin was developed to allow for on-line simulation and forecasting capabilities with weather adaptive control to meet the goals and objectives of VA SYD. Phase 1 of the project included implementation of the digital twin with a data connection to existing meters and gauges, SCADA system and weather forecasts. The existing collection systems model was calibrated against flow measurements both in terms of inflow components in connection to rainfall events and infiltration from groundwater. Phase 1 included forecast calculations for the upcoming 24 hours. The forecasts were carried out automatically once an hour. The digital twin system displayed measured flows and levels as well as calculated flows and levels at selected points along the collection system. The system displayed actual and calculated sewer overflow volumes, as well as water volume in the network and basins All displays were both hindcast and forecast. Finally the digital twin user interface also displayed estimated run-off from each sub-area from each type of flow components, i.e. inflow versus infiltration. Data assimilation, detailed weather forecasts and control strategies were developed and implemented during Phase 2 of the project. Data assimilation was applied to the calibrated collection systems model to deal with residual anomalies. This means the digital twin continuously analyses the deviations between measured and calculated values and compensates for them up to the time of the forecast. The deviations are interpreted and can then be used during the forecast calculation via an 'error forecast'. In this way, the digital twin model calculation is corrected both in the historical part and in the forecast. The digital twin model's weather forecasts were upgraded to include a hybrid between C-band radar and several weather models, where the most likely forecast is selected. The forecast horizon is 36 hours with hourly resolution and spatial resolution of 2 km. A new forecast is produced every hour. During the first few hours, primary radar data is used while the weather model gradually takes over. The data grid over the City of Lund was interpolated into each sub-catchment of the collection system model. This allows each catchment to get its own unique rain series in the forecast horizon, which is combined with measured rainfall data. Within the City of Lund, there are two major basins and a basin at the pumping station in Dalby. How and when to use these basins most efficiently was evaluated based on what to achieve. Based on these evaluations, decisions were made on what type of control strategies VA SYD wanted to deploy and what conditions that were available with the current control measures in place. The selected control strategies and conditions for automated selection between were programmed into Future City Flow as a scheduled separate forecast calculation. The results of these calculations were then used as setpoints in the operative control of available control equipment. Procedures for extracting setpoints and transmitting them to both VA SYD's SCADA system and directly to the PLC via OPC UA was implemented.

This presentation will detail how the investment in new monitoring technology gave Minnesota Utility Western Lake Superior Sanitary District data and analysis to allow them to make informed decisions concerning capital planning, plus the confidence to plan specific asset repairs amid wastewater network vulnerability. Background to the Problem Western Lake Superior Sanitary District (WLSSD) provides wastewater treatment for seventeen communities and three large industrial facilities in a 530 square mile region in the Duluth-Cloquet (MN) area. While treating about 14 billion gallons of municipal and industrial sewage annually, WLSSD is committed to protecting the environment, including the region's most precious resource -- Lake Superior. Preventing sewer overflows and leaks into the watershed is a top priority; pump stations and force mains serve as an effective way to control sewer overflows. The Challenge Force mains by their nature are not accessible by camera and therefore they can be notoriously difficult to evaluate. It was necessary for the utility to hire an external consulting firm to help overcome this, to spot and discover where network frailty lay and make suggestions to ultimately formulate an all encompassing asset management plan. Once appointed, the external consultants conducted measurements and modeling on three force mains with the sole purpose of identifying locations of greatest risk and making recommended improvements to reduce that risk. Based on this analysis, this presentation will detail the consultant-provided recommendations (which were very much) based on worst-case scenarios, ranging in cost from $185,000 to a $1 million in capital improvements. Obviously with a vast differentiation in the amount of capital spend required and looking down the barrel at significantly increasing costs, WLSSD wished to obtain additional data to verify the model results prior to making any decisions about planning capital improvements. The Technology Solution WLSSD came to Syrinix and specifically adopted their relatively new solution for Wastewater monitoring, which had seen excellent results and significant adoption at UK Utility - Anglian Water. PIPEMINDER-C (now known as PIPEMINDER ONE EXTERNAL) and it's analysis platform RADAR provides pressure transient detection, burst alarming and intelligent asset performance analysis to alert scenarios such as high/low delivery pressures, blocked pipes, trapped air and failing pumps or valves. This presentation will detail how in wastewater, unlike potable water, the impetus stops being on transient detection so much, and more on trend spotting. Subtle changes in the size or shape of transients, or the mean pressure being higher, lower or changing over time can be symptoms of an ongoing maintenance requirement or a break. RADAR has systems built in to automatically alert on these symptoms, especially when spotting a break, or analysts can use more subtle and complex knowledge and understanding to tease out the cause of these symptoms. Breaks, on rising mains, can go for months without being known about, due to their remoteness and that their effectiveness is measured by how well the main manages to shift it's wet well's contents. A break makes the main less restrictive to flow and so the main will often appear to be operating better than usual. Due to the nature of what they are moving however, this can cause untold damage to wildlife and habitats and the water companies will be expected to clean up the affected area. This presentation concentrates on maintenance events. Pumps operating poorly and NRV/Check Valves passing will cost the water company huge amount in energy costs alone, since every litre of water is now taking so much more energy to get from point A to B. Spotting entrapped air or the effects of poorly performing air-valves also can lead to a reduction in breaks throughout an asset's life. To summarize, pressure logging provides critical burst alarms on pumped mains alongside invaluable asset performance analysis and alerting, to prevent breaks and increase asset lifetimes. Results WLSSD installed the PIPEMINDER technology system in January 2020. Analyzing multiple locations, it was found that the data generated during normal operations lined up reasonably well with the models but in addition, the technology and analysis enabled the WLSSD team to verify or identify specific problem areas. This presentation will detail three examples of discoveries via the data that informed capital decision making. 1. A Welded Air Release Valve Wasn't Demonstrating Benefit. The modelled data revealed a specific valve was providing limited air transfer to and from the pipe. The installed technology allowed WLSSD to confirm that this component was not critical to force main operation and the risk of an emergency repair from this connection could be eliminated without detriment to the operation of the system. 2. An Ineffective Air Release Valve Manhole. At one station, WLSSD had planned to vent an air release valve manhole to improve conditions. Data revealed that this change would not benefit pressures at the station or in the pipeline. This finding surprised the WLSSD team. Additional work took place to evaluate whether reinstating a former air release valve location would improve pressures. 3. Transient Events Due To Power Outages. The devices captured four significant transient events when pumps shut down due to power failure. Transients were documented and showed significant additional pressure on the pipes that could cause a failure if they were not addressed. This data enabled the analysis team to highlight the importance of determining the cause of the outages and to work with the utility to identify the cause and mitigate the problem Cost Savings Data provided by PIPEMINDER now informs capital planning work to improve conditions of WLSSD's force mains. While modelling is important, the results may not reflect actual conditions. The utility has learnt that modelling that is too conservative can lead to unnecessary capital expenditures. Having accurate monitoring data helps WLSSD identify smaller capital projects that extend pipeline life-and to see where additional protection is warranted. Improved System Availability Industrial and residential customers rely on WLSSD's systems 24/7. Shutting down a pipeline due to transient events or component failures is not an option. By proactively identifying potential problem areas using data generated, WLSSD can take steps to reduce the risk of operational interruptions. Informed Decisions WLSSD improved its ability to make decisions regarding capital investments and operations backed by accurate data. They now have the information needed to invest resources where there is the greatest risk and the greatest potential benefit.

The design and implementation of stormwater best management practices (BMPs) is based on regulations and guidance that tries to anticipate and model the impacts of each system. The deployment of in-situ sensors along with stormwater BMPs has allowed communities to more accurately understand BMP performance before, during, and after rain events. This has led to a more accurate accounting of BMP performance and reduced costs by municipalities in complying with their MS4 permits and TMDL compliance goals. Our research has specifically focused on documenting the performance of permeable pavement systems, which are often governed in their implementation by the soil on which they are installed. The permeable pavement system chosen for this work is PaveDrain, a system comprised of permeable articulating concrete blocks (P-ACBs). P-ACB systems differ from traditional permeable pavers because they have 1) open joints and 2) are able to handle heavy traffic loads. The open joints means this system handles more rain water, and is easier to maintain (cleaning process is required less frequently and is easier to perform). The suitability to handle heavy traffic loads means that PaveDrain can be used in additional applications like roadways, traffic aisles, and truck stops. For this work, the following sites were studied: Table 1. Studied Sites The sensor system monitors water level in the stone base, with a nearby weather station monitoring rainfall, temperature, barometric pressure and relative humidity. As can be seen in the figures below, water enters the base quickly during rainfall events, and over time exfiltrates from the stone base into the soil [where present, the height of internal drainage structures is notated]. Figure 1 Measured rainfall and water level with corresponding subgrade infiltration rates. In both sites, most runoff draining into the BMP has exfiltrated into the soil, reentering the natural water cycle in a decentralized fashion within 24 hours of the end of a rainfall event. Instantaneous rates of exfiltration with high hydrostatic head pressure reached close to 1.00 in/hr. Average rates of exfiltration over the first 48 hours are 0.40 in/hr0.50 in/hr. For most jurisdictions stormwater designs would expect clay soil to infiltrate at 0.04 in/hr, a full order of magnitude less than the rates being measured in the field. The discrepancy between observed and expected values is attributable to the heterogenous nature of soil. While clay soil is present, so are more permeable soils which form 3-dimensional networks and paths for water to exit the BMP system leading to significantly elevated performance. Furthermore, based upon these values, modeling was done to understand the value of TSS and TP removal beyond what is typically credited to a permeable pavement system. Source loading and management modeling software (WinSLAMM) was used to reevaluate the installed system in Cudahy, utilizing site-specific parameters including measured subgrade infiltration rate and product-specific performance properties representative of the P-ACB system (PaveDrain) [Figure 2]. It was determined that pollutant removal costs required to close compliance gaps can be reduced by a factor of 12 when modeling implements measured data and parameter definitions that reflect system capabilities. [Table 2] Figure 2. Subgrade sediment accumulation impact on pollutant removal. Table 2. Economic impact of SLAMM enhancement and in-situ sensor system. In communities that have high percentages of impermeable cover (e.g., urban cores), the use of low-maintenance, high-performing BMPs like P-ACBs, would allow all communities to more effectively address stormwater challenges, especially in the face of more extreme rainfall events.

Introduction Sludge generated from wastewater treatment typically goes through a series of handling processes such as thickening, stabilization and dewatering, before its final use or disposal. Anaerobic digestion is widely applied in medium to large water resource recovery facilities (WRRFs) for sludge stabilization. In anaerobic sludge treatment, fugitive methane emissions can occur from digesters (due to aging infrastructure), downstream storage, from associated pressure relief valves and pipework, and also due to methane slip through combined heat and power (CHP) engines and biogas upgrading. For example, work in Denmark over the past few years has quantified methane emissions at 69 biogas facilities and shows methane emissions account for up to 7.5 percent of the gas production at WRRFs (Fredenslund, A.M et al., 2021; Scheutz & Fredebslund, 2019). Large leakage of methane may negate the positive climate impact from biogas energy recovery and contribute significantly to the facility's operational carbon footprint. A portion of the methane generated is dissolved in the digestate, which can also be released during the downstream dewatering or sidestream treatment processes. In addition, long-term sludge drying (e.g., in lagoons) is commonly applied in many countries, such as Australia, due to its ease of operation and low operational costs. Methane generated from sludge drying lagoons is typically not captured and can be a significant greenhouse gas (GHG) emission source. In the US, a country-wide standard methodology for quantifying GHG emissions from the wastewater sector does not exist. Among the available reporting protocols, methodologies for quantifying fugitive methane emissions from sludge treatment and biogas handling are limited to combustion of biomass and biogas, which essentially assumes zero methane emissions from anaerobic digestion and biosolids dewatering processes. The latest Biosolids Emissions Assessment Model (BEAM 2022) has recommended a minimum of 1 percent of methane in biogas as fugitive emission and allows a user-input value if site-specific data are available. The lack of consistent methodology and lack of facility level measurement result in significant risk to facilities in the estimation of their fugitive methane emissions through the sludge treatment and biogas handling processes. This paper presents an overview of challenges and issues in quantifying fugitive methane emissions from sludge treatment and biogas handling, impacts on GHG inventory and practical tips for reducing methane emissions based on global experience to date across a growing number of case studies. Benchmarking Fugitive Methane Emissions Methodologies and Key Considerations In the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, a three-tier method is described for quantification of methane emissions from WRRFs. Tier 1 provides global activity and emission factors; Tier 2 provides for local in-country activity factors and/or emission factors and Tier 3 methods require facility level monitoring. Accurately quantifying fugitive methane emissions requires Tier 3 facility level measurement using methods such as differential absorption lidar (DIAL), tracer gas dispersion (TDM) and inverse dispersion modelling (IDM), which may be combined with point source leak detection or other process unit methods to determine location of leaks. This practice remains emerging with significant work ongoing in Europe to provide facility level quantification and mitigation at WRRFs. Elsewhere, Tier 2 methods are common. The UK Carbon Accounting Workbook is used by Utilities to report on operational emissions and includes country-specific (Tier 2) theoretical emission factors associated with the most common sludge and biosolids processes in the UK, with emissions based on mass of methane per unit of tonnes dry solids of raw sewage sludge (UKWIR, 2020). In the Australian National Greenhouse and Energy Reporting (NGER) framework, methane process emissions are indirectly estimated using sampled influent and/or effluent streams and application of assumed biogas generation and percentage biogas utilization to calculate the net tonnes of CO2 equivalent released to the atmosphere. This approach considers facility level data but does not require direct measurement of the GHG, hence still considered Tier 2. Emissions from biogas flaring is based on best practice flow rate measurements of the flared biogas and its methane concentration. Different facilities may have a range of approaches to sampling process streams for operational, planning or reporting requirements. Sampling locations, frequencies and methodologies can result in inaccuracies in estimating the fugitive methane emissions. The recently published IWA book 'Quantification and Modelling of Fugitive Greenhouse Gas Emissions from Urban Water Systems' includes additional information on fugitive methane emissions from a range of wastewater treatment, sludge and biogas handling processes, estimated through facility level monitoring (IWA, 2022). Table 1 provides a summary of key methane emissions from global case studies including both those which directly monitor methane emissions and those which use various alternative GHG accounting methodologies, generally aligned with Tier 2 level approaches. A more complete table will be provided in the full paper. In the absence of global full scale monitoring data to estimate fugitive methane emissions, existing methodology estimates may be beneficial for benchmarking emissions from sludge treatment and biogas handling processes however, Tier 3 level facility monitoring is required to accurately estimate methane emissions and to validate any mitigation efforts. Monitoring and Reducing Fugitive Methane Emissions Whilst published literature studies of methane mitigation are limited, practical examples of programs for monitoring and mitigation across European countries show the criticality of direct methane emissions monitoring, and operational approaches to mitigate methane emissions through regular survey, proactive leak detection and repair and independent certification. Table 2 summarizes some of the key sources and (limited) mitigation approaches from work to date; further details to be provided in the full paper. In future planning, it is critical that decisions regarding anaerobic versus aerobic sludge digestion consider fugitive emissions from existing and proposed assets. Conclusions Fugitive methane emissions from sludge treatment and biogas handling processes are a significant source of GHG emissions which must be monitored and mitigated by utilities taking action to reduce their carbon footprint. These emissions are particularly critical for WRRFs with anaerobic digestion and open anaerobic systems such as sludge drying ponds. There is lack of consistent methodology for quantifying and monitoring these emissions in North America, which could lead to over- or (more likely) underestimation of their contributions to the overall GHG footprint for the WRRFs. As shown by ongoing work in Europe, facility level measurement is critical in quantifying the fugitive methane emissions. This paper will provide practical recommendations to WRRF operators to guide best practices for methane monitoring and mitigation throughout the facility life cycle.

In 2016, Hazen and Sawyer (Hazen) was hired to design and provide construction services for the complete replacement of the HVAC and Odor Control systems at the Massachusetts Water Resources Authority's (MWRA) Nut Island Headworks facility in Quincy, Massachusetts. The existing facility includes more than 65,000 square feet of operating space over 4 above and below grade floors, including a completely buried odor control facility, and removes screenings and grit from the MWRA's western sewage collections system before sending the flow via a tunnel under Boston Harbor to the Deer Island Wastewater Treatment Facility for final treatment. To further add to construction challenges, the Nut Island facility sits in the middle of a heavily trafficked public park, with sweeping views of Boston's harbor and skyline. Upon initial review it was clear that trying to remove and replace all of the existing duct work, air handlers, fans, scrubbers and adsorbers based on as built drawings and field measurements could result in significant issues during construction, so our first step in the design process was to complete a detailed laser scan of the entire operating area of the facility, and use that data to build a 3 dimensional Revit model. The resulting model and point cloud located equipment and appurtenances within the existing facility with millimeter accuracy. Once detailed design commenced, maintenance of plant operation (MOPO) during construction was seen as critical to ensuring a safe working environment for those inside the facility. At the same time, it was critical that MWRA maintain treated air discharge to allow the public to continue to enjoy the surrounding park, while continuing to meet their discharge permit. The Hazen team used 4-dimensional design techniques to create a detailed, timeline based design with more than 75 staging drawings, showing how the contractor could construct the upgrades while maintaining ventilation and odorous air treatment, and meeting the contract constraints. The result is an ongoing, $58 million construction contract, with all submitted bids within less than 0.5% of the accepted bid price. In addition, while the contractor has proposed and executed different methods for MOPO than those shown in the design documents, the detailed staging and constraints, as well as the accurate laser scan and model, have resulted in a project that is tracking for less than 6% change orders at project completion. In addition, during startup testing of the wet scrubber system the Hazen team utilized historian data and BI dashboards to provide real time data analytics to evaluate wet scrubber operation, chemical use and control strategy integration to optimize scrubber controls. This presentation/conversation will detail how the Hazen team utilized 4D design to zero in on construction constraints that were reasonable and achievable, while limiting system downtime and allowing for continuous operation of the building's ventilation and odor control systems. It will also present design and construction success stories and lessons learned, and demonstrate how utilizing 4D design, with a focus on constructability and MOPO, led to consistent bids and helped to minimize project change orders, and show how PowerBI can be used to present tens of thousands of pieces of data in a way that is easy to share, evaluate and react to.

Purpose: Share the background and successful implementation of a multi-phase force main isolation, condition assessment and rehabilitation project in a congested urban corridor in southeast Virginia. Abstract: HRSD committed to replace air vents with galvanized riser pipes vulnerable as a material risk of failure. An air vent was discovered directly tapped into a pressurized in-line concrete vault located on a low-pressure 36-inch diameter reinforced concrete interceptor force main serving the City of Portsmouth and the Norfolk Naval Shipyard. The vault was installed as part of a 1950s force main relocation project to facilitate force main diversion/relocation required to construct Interstate 264 and the Downtown Tunnel connecting the Cities of Portsmouth and Norfolk. The newly found vault and associated force main provided over 60 years of service in a likely corrosive environment raising concerns of the vault's condition as a high point in the system as well as the interceptor force main it serves. Project challenges included discovery of an inaccessible in-line pressurized concrete vault beneath a heavily traveled roadway near an interstate interchange and a second inaccessible vault at the other end of the relocation, a lack of operational isolation valves along the force main, seasonally high flows received from the Naval Shipyard, force main isolation pump and haul requiring over 100 trucks strategically staged and hauling from multiple locations, and potentially encountering heavy metals contaminated soils associated with a nearby superfund site. Alternatives to remove the air vent and vaults were evaluated including isolation of the vaults with line stops, bag stops, pump and haul, and an above ground HDPE bypass force main. Trenchless force main rehabilitation methods considered included CIPP Liner, compression fit pipe and slip lining. Installation of a new force main parallel to the existing force main and a new force main located on CSX railroad property along with abandonment of the existing force main were also evaluated. Projects costs were estimated between $1,800,00 and $4,700,000. Results of a triple bottom line feasibility analysis suggested a two-phase project approach featuring Phase 1 force main improvements, isolation by construction of a temporary force main diverting flows to another force main and condition assessment followed by Phase 2 force main condition-based rehabilitation. The primary benefit of this approach was to confirm candidacy for force main rehabilitation and as-built construction conditions for trenchless technology suitability assessments and, if possible, competitive bidding of rehabilitation methods. The Phase 1 project included certain alternate bid items to facilitate continued construction activities to accommodate a Phase 2 rehabilitation contractor. This presentation will highlight coordination efforts required for preparation of the alignment study, construction of the Phase 1 force main isolation improvements and condition assessment results, the trenchless technologies considered, and the Phase 2 rehabilitation approach. Construction of the Phase 1 isolation improvements is progressing with isolation scheduled for completion in January of 2023, followed by condition assessment including cleaning, CCTV inspection and laser pipeline profiling and mapping in February of 2023. Dependent on the condition assessment results, HRSD's plans to award a force main rehabilitation contract by the summer of 2023. Isolation of the force main will remain in place for removal by the Phase 2 contractor upon successful completion of the interceptor force main rehabilitation improvements. The in-line 1956 vintage in-line sewage diversion vaults will ultimately be dismantled/abandoned.

Introduction: The water and wastewater industry is facing new challenges in the chemical supply chain due to recent pandemic conditions, hurricanes, and wildfires. As a result, Water Resource Recovery Facilities (WRRFs) are looking ways to improve the chemical resiliency of their facilities during chemical shortages, emergencies, or any disruption in chemical supply chain. The main objective of this paper is to assess the risk from chemical shortages, and present strategies to WRRF's to mitigate risk through consequence and vulnerability reduction. Background: Recently, Hazen has teamed with Orange County Sanitation District (OCSan) to conduct the Chemical Resilience Study for their Plant 1 and Plant 2. The approach to quantitatively assessing and managing risk is based on the ANSI/AWWA J100 Standard: Risk and Resilience Management of Water and Wastewater Systems. The J100 standard provides the framework for assessing baseline conditions as well as improvements following the implementation of risk mitigation. Risk is defined as follows: RISK = Consequence X Vulnerability X Likelihood Table 1 summarizes the approach to reduce consequence and vulnerability for OCSan. This approach will allow to assess baseline risk for WRRFS, as well as provides clear path to reduce the risk, either by reducing the consequences of supply disruption or improving system resilience (i.e., reducing vulnerability). Table 1: Approach Adopted to Reduce Risk for OCSan Methodology: The following methodology was developed to reduce the risk of WRRFs to chemical shortages and disruptions - Chemical Risk Analysis: Estimating the likelihood of chemical shortage requires understanding the chemical supply chain and availability of substitutes. Industry trade groups and chemical suppliers were contacted to understand manufacturing locations and the sources of raw materials. - Vendor Alternatives. Alternative vendors were identified using information from industry trade groups, as well as reviewing chemical bids from OCSan and similar utilities. The use of chemicals in other industries which might be supplied by alternate vendors was also reviewed. - Delivery Alternatives. Alternative forms of deliveries including bulk liquid, totes, and dry chemical delivery with onsite dilution were also investigated - Chemical Alternatives. Alternative chemicals were identified to existing chemicals Findings The chemicals evaluated in OC San Chemical Resilience Study are grouped under four main categories and listed in Table 2. These chemicals are used in the following plant process areas: preliminary treatment, primary treatment, secondary treatment, odor control, effluent disposal, solids handling, and power generation. Table 2: Chemicals Evaluated at OCSan Chemical Resilience Study Chemical interruption to facilities could result from the following conditions: - Lack of delivery access due to a natural disaster - Interruptions from manufacturers and/or vendors - Chemical shortages - Increased cost of chemicals - Increased demand in other industries - Delays in deliveries - Regulatory changes Evaluation of the baseline conditions for OCSan's chemicals identified that most chemicals used have over two weeks of storage available in the event of interruption. The only chemical with less than a week of storage capacity was ferric chloride at Plant 1. Ferric chloride is the mostly used and frequently delivered chemical at Plant 1 and Plant 2 with less than 3 days between deliveries. Bleach was also identified as a chemical with frequent deliveries at Plant 1. Both ferric chloride and bleach are critical chemicals in order for OC San to meet permit requirements in their air quality and discharge permits. Table 3 was developed for OCSan to highlight the criticality (based on consequence score), average chemical use, and consequences of chemical interruption for chemicals used at Plant 2. Table 3: Summary of Chemicals Used at Plant 2 Figure 1 shows the overall risk score calculated for the chemicals used at OCSan. The score brings together the consequence, vulnerability and likelihood assessments. As can be seen in Figure 1, Bleach and Ferric chloride have the highest risk for chemical disruptions. Our full paper will include more details about the consequence, vulnerability and likelihood assessments and will provide a list of alternative chemicals that could be used to replace existing chemicals. Figure 1: Risk score for chemicals used at OCSan

Executive Summary: The GLWA (Detroit) and NEORSD (Cleveland) are two large regional wastewater utilities that face similar challenges (e.g. funding/rates, aging infrastructure, CSOs, employee turnover) and have recently initiated innovation programs to help address these issues. Innovation is critical to current and future operations within their organizations. Both organizations have 'formal' innovation programs, but they are different stages of maturity. This paper (and presentation) will compare the GLWA Innovation Programs and the NEORSD Innovation Program — from inception through launch through current day to day operations. The goal of this paper is to provide some key insights to other water and wastewater utilities that may be considering implementing an innovation program or those that may need to take a 'step back' and look at their current innovation program frameworks. Innovation Programs — 2 Different Utilities - 2 Different Approaches Based on recent Water Research Foundation studies, a vast majority (>90%) of utilities surveyed believe that innovation is critical to their future. Additionally, 70% of the utilities participating in the research have developed formal innovation programs within the last 10 years. The GLWA and NEORSD have formal innovation programs in their organizations — but the journey they have taken has been different and they are at differing stages of maturity and have different approaches to various innovation program components. GLWA Launch — The GLWA 'Innovation Program' launch was initiated to help motivate and retain staff engagement, track ideas related to efficiency and operational improvements, and to help provide an assessment point for reviewing and screening external technologies. The GLWA launch benefitted from already having a successful research program, due to existing relationships and collaborations, but also experienced challenges from those same relationships due to the differences between research (narrow focus on a small subject) and innovation (broad focus on many subjects). GLWA initiated it's innovation program with two primary components: a quarterly workshop which focused on assessing external technologies via a series of vender presentations and developing an internal GLWA idea management software platform. This paper focuses on the idea management aspect of the GLWA innovation program. NEORSD Launch — NEORSD launched their initial Innovation Program framework in 2018 — utilizing a fairly 'informal/voluntary' administrative approach with a 'Big Bang' communication mode (1 organization wide email announcing idea submission form is available). As time passed, it was quickly realized that this approach did not achieve the desired goal of 'develop, encourage and sustain a culture of innovation' with NEORSD. Subsequently, NEORSD changed its approach to innovation program management, dedicating resources and designing a new innovation program framework — with the original program goal continuing to be a driving principle. In February 2020, NEORSD started the evolution of their innovation program framework — with a comprehensive relaunch strategy developed. Many challenges have been encountered and many lessons have been learned on this journey. See Figure 1 for a visual summary of the NEORSD Innovation Program framework - detailing the three primary components - communication, process and administration. Idea Management - 2 Different Approaches Ideas (like water lines, pumps, sewers and manholes and other equipment we use) should be considered as assets — and managed accordingly. Not all ideas will get implemented, and not all implemented ideas will be implemented right away. Sometimes an idea must be postponed, or slowly grown, until the timing is right, and resources are allocated for implementation. A key component of an innovation program is idea management and GLWA and NEORSD have taken different approaches in managing their ideas. GLWA Approach — GLWA approaches idea management as somewhat of a 'free for all' of good ideas and community engagement. However, those ideas must be managed within a structure of submission, commentary, review, and engagement with potential implementers. Idea management must have three specific components: 1) idea tracking, 2) feedback to the ideator, and 3) database of idea submissions, as shown in Figure 2. GLWA chose to implement a third party vendor software provide this structure. NEORSD Approach — The NEORSD idea management approach is less formal and structured when compared to GLWA and it has been recognized as a key area as part the NEORSD innovation program relaunch activities. Ideas that are managed by paper lists/post-its, emails and spreadsheets are not conducive to being able to be accessed, analyzed, reported or managed. A comprehensive idea management approach is being developed at NEORSD in 2021-2022. Steps that NEORSD is taking to develop this approach will be shared in the paper/presentation. Summary — Lessons Learned The GLWA and NEORSD have taken different approaches in their development and administration of their innovation programs. Many challenges and successes have been achieved along the way for both organizations — and there are lessons learned to share with other water and wastewater utilities that may be considering developing or revamping an innovation program. Innovation at a water or wastewater utility are not typically encouraged. The water sector must produce via a series of specific tasks to meet a set of specific requirements. Novelty is not beneficial or necessarily even useful. As a result, when trying to engage and develop your workforce innovation, there are often roadblocks preventing clear discussion, and clear understanding, of what might be gained. As each of us have developed our utility's respective innovation programs, we have encountered different aspects of institutional resistance or indifference. At the same time, we have also encountered various pockets of unexpected creativity. Some of these issues are listed below. 1.Communication differences 2.Rigid thinking versus 'free form' innovation 3.Team engagement and marketing the program 4.Differences of opinions 5.Differences in expectations We summarize our presentation and paper with the discussion of these challenges and some of the remedies we have used to circumvent them.