Results

The purpose of this presentation is to describe how a Great Lakes community is addressing its goals of reducing overflows and basement flooding while enabling real time control of its wastewater system. Peel Region believes it will require best in class measured and predictive rainfall data, to create efficiencies for conveyance and treatment, that will allow the Region to face the unique challenges of climate change, population growth, and aging infrastructure. Peel has implemented the program described in this abstract, in its 2020 Water and Wastewater Master Plan for the Lake-Based Systems. The Region of Peel, Ontario (Peel or Region) is responsible for the operation and maintenance of the sanitary sewer network, pumping stations, and wastewater treatment plants within its collection system. Peel is composed of the Cities of Brampton and Mississauga and the Town of Caledon that drain a combined surface area of 1,246 km2 to Lake Ontario. Wastewater services are also provided by Peel to neighboring Toronto and York through inter-regional servicing strategies, thus making accurate rainfall over Peel and for neighboring jurisdictions of increasing importance for managing wastewater flows. Wastewater is conveyed by gravity, generally from north to south through the collection system to the wastewater treatment facilities at Lake Ontario. Peel provides wastewater system services to Mississauga, Brampton and parts of Caledon. Demands are placed on the wastewater system because Peel is one of the fastest growing municipalities in Ontario, in excess of 1.4 million people. The Region's wastewater system comprises two principal trunk systems: the west trunk system that conveys flows along and near the Credit Valley to the Clarkson Wastewater Treatment Plant, and the east trunk system that conveys flows along and near the Etobicoke Creek Valley to the GE Booth Wastewater Treatment Plant. Planned construction of a 11-km of the East to West Diversion Trunk Sewer will require RTC and forecast precipitation. There are over 3,600 km of wastewater pipes in Peel, with 300 km of trunk sewers consisting of pipes ranging from 750 mm to 3,150 mm in diameter, servicing 294,000 customer accounts. Climate change and population growth continue to put pressure on the wastewater system. Recently, a climate change mitigation strategy was endorsed by the Region of Peel Council to reduce basement flooding due to sewer backups. Understanding system response to rainfall and taking proactive measures to reduce I/I are strategic actions aimed at reducing flooding issues region wide, and to maintain wastewater treatment capacity in the long-term. The flash flood that occurred on July 8, 2013, had a larger impact on the Region of Peel and City of Toronto than any storm since Hurricane Hazel (1954), and reinforced the need for better preparation and operation of the wastewater system. The Region is seeking to improve the wastewater system for future growth, achieve cost efficiencies, derive environmental benefits, and to lower the risks to human health. Improved rainfall monitoring, both current and forecast, are key to achieving these goals: increasing volume of wastewater treated; reducing incidents of overflows/basement flooding; and achieving effective operation of real-time controls. These goals can be more efficiently achieved through accurate and representative rainfall monitoring. This is achieved through the combination of weather radar and rain gauges. Radar-based precipitation measurement that relies on both gauges and radar is called GARR, or gauge adjusted radar rainfall. The target region and neighboring weather radars (both Canada and US) are shown in Figure 1 with range rings indicating coverage distance. Current and forecast rainfall is needed to meet the Region's objectives. Technical details on forecast rainfall is not discussed here but will be presented along with GARR during the presentation. The GARR system embodies both near-real-time (NRT) and End-of-Month (EOM). During EOM, Quality Control (QC) of rain gauges and radar removes or mitigates radar anomalies and erroneous or inconsistent gauge measurements. Gauges identified as consistent are used to bias -correct the radar precipitation rates. Thus, GARR is the combination of two sensor systems that results in better maps of rainfall than either sensor system could produce alone. GARR provides coverage of targeted areas at spatial and temporal resolutions commensurate with the sewer catchments. GARR is needed for better understanding and modeling of:

-- Basement flooding from both Sanitary Sewer Overflows (SSO) and Combined Sewer Overflow (CSO), and Facility By-Pass
-- Inflow and Infiltration Calculations
-- Hydraulic model calibration
-- Stormwater flood modelling

To illustrate the properties of GARR required by the Region, we summarize the characteristics of the extreme event, July 8, 2013. GARR was produced with weather radar and rain gauges from multiple networks from Region of Peel (29), City of Mississauga (14), and Credit Valley Conservation (13). Figure 2 depicts the spatial distribution of rainfall depth depicted by the color scale ranging 11.9 - 138.3 mm with a mean of 65.3 mm over the target area. Rain gauges are shown by black triangles with depths in mm. The scatter plot in Figure 3 shows bias-corrected radar (note 1:1 line) versus rain gauge depths for a selected period. Gauges excluded are shown in red, whereas rain gauges that pass QC (included) are shown in blue. Quality control removes bias in the GARR rainfall estimates, and generally improves accuracy from more than ± 20% to less than ± 5%.

Benefits of Presentation
This presentation should be selected because it shares the experience and challenges faced in characterizing rainfall. While GARR is an accepted technology in wastewater, the needs in the Great Lakes Region are unique and would benefit other communities with similar climate and population/development pressures.
Status of Completion
At the time of submittal this project is complete in terms of setup and operations. Historic data analysis was completed for requested storm events in March 2019. End-of Month quality-controlled GARR for all storms in May to November 2019, was completed in April 2020. Continuous production of Forecast and NRT GARR is operational beginning April 2020, and EOM GARR production continues.

Conclusion
Besides climate change, growth will continue to place pressure on water and wastewater infrastructure in Ontario. GARR is fit-for-purpose and helps address objectives of the 2020 Water and Wastewater Master Plan for the Lake-Based Systems.

OVERVIEW A major US water utility director was recently quoted saying that 'Every 10 years or so we're having a 100-year storm' (Boston Globe, July 23, 2021). While this statement reflects a reasonable perception that the frequency of intense rainfall is increasing across much of the United States and worldwide, it misleadingly suggests that existing precipitation frequency estimates have little value, potentially sowing distrust in engineering methods used to assess infrastructure performance. The precipitation frequency statistics that steer collection system assessment and design should be transparent, defensible, and accessible. CDM Smith's NetSTORM software (Heineman, 2004) and companion precipitation statistics website (http://dynsystem.com/netstorm/IDFStats.htm) provide data and analysis tools to efficiently analyze rainfall data and develop intensity and duration statistics to compare with those published by agencies such as the National Oceanographic and Atmospheric Administration (NOAA). Because rainfall intensity varies spatially and temporally, a single storm may cause extreme rainfall at one location over a certain duration, lesser rainfall at another location over a different duration, and yield ordinary accumulations elsewhere. In assessing rainfall across a metropolitan area, it is thus reasonable to expect numerous '100-year storms' over a decade. The readily available and up-to-date statistics for principal rain gages that NetSTORM offers can help dispel mistrust of rainfall frequency statistics based on historical data. This paper will present the existing industry standard source of precipitation statistics and its limitations, then discuss how NetSTORM can lift those constraints as well as streamline the process of general rainfall data acquisition, QAQC, and analysis. LIMITATIONS OF THE CURRENT INDUSTRY STANDARD PRECIPITATION STATISTICS NOAA's Atlas 14 precipitation frequency estimates (Perica et al., 2018) serve as standards for a wide variety of design and planning activities and regulations across the US. Its Precipitation Frequency Data Server (PFDS) provides online access to the frequency estimates presented in the atlas. However, the PFDS is lacking in several areas: 1. NOAA PFDS datasets are only as recent as the data used to develop Atlas 14, which has no data after 2000 for the 17 states analyzed in its first two volumes, and lacks coverage for five northwestern states, 2. The NOAA PFDS provides statistics for only a select set of durations and average recurrence intervals (ARI), limiting a user's ability to easily quantify ARIs outside of or between those values; and 3. While NOAA's PFDS provides the information necessary to evaluate the significance of historical rainstorms, it does not provide software tools for quickly and easily applying its statistics to timeseries data. NETSTORM: A COMPLEMENTARY TOOL TO ATLAS 14 AND A DATA PROCESSING POWERHOUSE Over the course of its 30-year history, NetSTORM has been continuously refined to meet these needs of (1) providing statistics on the latest data, (2) identifying storms with an ARI of less than one year, and (3) streamlining the process of precipitation data acquisition, QAQC, and analysis. The NetSTORM Precipitation Frequency Statistics website includes up-to-date statistics for 100 cities across the United States. The free NetSTORM software package can produce statistics from any dataset available to a user and provides a wider range of frequency estimates than the NOAA PFDS. NetSTORM can estimate storm ARIs on a continuous scale that extends below one year (the lower limit of the NOAA PFDS). Additionally, ARIs estimated by NetSTORM are presented alongside interpolated ARIs from Atlas 14. Given a lengthy rainfall dataset with thousands of records, any NetSTORM user can quickly produce a rich and portable html report. Its rainfall statistics reports provide tabular and graphic displays for each major historic storm at various durations, giving users easy access to frequency statistics for individual storms. Annual maximum series graphs (Figure 1) allow users to visually assess heavy rainfall frequency across historic records. CASE STUDY: RAPID ANALYSIS AND CONTEXTUALIZATION OF TROPICAL STORM FRED AND HURRICANE IDA NetSTORM was used to rapidly contextualize the impacts from both Tropical Storm Fred (8/19/2021) as well as Hurricane Ida (9/1/2021) for both Hartford's Metropolitan District (MDC) and the Town of West Hartford. Both storms caused significant flooding in the Hartford metropolitan area. Immediately after both storms, the latest rainfall data from multiple local rain gages in the area were consolidated and processed with NetSTORM, identifying rainfall and ARIs at various durations. The data output from NetSTORM were further processed to produce subplots comparing the hyetographs, peak hourly intensities, and maximum ARIs with those of Fred and Ida (Figure 2). NetSTORM's calculations show how the two storms over 24 hours are similar, averaging about 5.25 inches, which amounts to an ARI of about 12 years. However, Fred was actually a much rarer event, with a peak intensity exceeding 3 inches per hour and a peak ARI approaching 300 years based on 4.76 inches of rain over its most intense 3 hours. NetSTORM enables these kinds of rapid analyses that better contextualize real world conditions with historical data, a service that is becoming ever more critical with evolving global climate patterns in an increasingly data-driven regulatory landscape. CONCLUSION Precipitation frequency estimates presented on the NetSTORM website use methods that are largely compatible with Atlas 14. NetSTORM is available for download from the website (dynsystem.com/netstorm), allowing users to perform comparable calculations for other locations or develop custom analyses. The website and the software can help inform public understanding of extreme rainfall frequency and streamline the otherwise arduous process of precipitation timeseries data acquisition, QAQC, and analysis. While non-stationarity of rainfall now and in the future means that precipitation frequency estimates are subject to change, the statistics published in Atlas 14 and elsewhere are generally valid for understanding historic rainfall, and likely only warrant modest adjustment for assessing extreme rainfall over the next few decades. NetSTORM is an ideal choice for rainfall data processing and analysis, providing a concise interface, practical and portable report, and extended statistics when compared with Atlas 14.

The Chicago Public Schools, Chicago Department of Water Management (DWM), the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC), Openlands Project, and the Healthy Schools Campaign have partnered to bring much needed improvements to Chicago's elementary school sites, many within underserved neighborhoods. The goal of the project was to combine both the resources and goals of the sponsoring organizations to provide needed landscape and play space to dilapidated asphalt covered school yards while also greatly reducing stormwater runoff volumes and rates. The projects address neighborhood flooding issues, help to reduce combined sewer overflows, and reduce the load to MWRDGC's water reclamation facilities. In 2014, Environmental Consulting & Technology (ECT) was selected to design and engineer the improvements for two of the first four school sites and has continued providing design services through 2020. The projects integrate green infrastructure throughout the improvements to address runoff from the project areas as well as the entire school sites. Improvements have included pervious asphalt basketball courts, pervious rubber and artificial turf play surfaces, permeable paving parking, bioretention landscapes, and raised planters to grow edibles. Prior to beginning the design process, DWM conducted an analysis to identify areas of the City in need of runoff reduction. This analysis was overlaid on the Chicago Public School's (CPS) needs for playground upgrades. To address DWM's need to reduce runoff, the projects were designed to meet the standards of MWRDGC's stormwater ordinance for greenfield development. The integrated systems, native landscapes, and raised planters for edibles provide a broad range of learning experiences for young elementary school minds. The project has won a number of awards and recognitions including: US Green Building Council's 2016 Best of Green Schools Illinois Association for Floodplain and Stormwater Management's 2015 Sustainability Project Award Featured on Green Schools National Network.

Introduction: The Truckee Meadows Water Reclamation Facility (TMWRF), serving the cities of Reno and Sparks, Nevada, has had historic difficulty of their dewatering operation with their biosolids averaging just over 16% total solids (TS). This poor performance is largely the result of TMWRF running an enhanced biological phosphorus removal (EBPR) process, which has limited their maximum mechanical dewaterability due to the large amount of dissolved phosphate and volatile solids in their centrifuge feed. Centrifuge replacement in 2015 further exacerbated the dewatering performance with the newer machines requiring high polymer dosages and delivering consistently poor centrate quality. Since June of 2020, TMWRF has carried out an alternative strategy to their dewatering operation by sending the thickened waste activated sludge (TWAS) produced in their EBPR process directly into their centrifuges, bypassing all digestion. The impacts of this change have been major and wide-reaching with effects on biosolids character and volume, chemical usage, plant wide nutrient removal, biogas production and quality, and centrate treatment. This presentation will discuss the background of the facility including their historically low-quality performance as well as the many facets that have been positively impacted by carrying out this change to direct TWAS dewatering, This presentation will also examine the role of this operating strategy in the long-range planning of the facility. Dewatering Background: TMWRF, a 30 million gallon per day (MGD) facility, had operated the same three centrifuges since 1983, producing just over 15% TS biosolids with a centrate quality of slightly over 400 mg/L total suspended solids (TSS). To improve both process parameters and energy demand, a centrifuge replacement took place in 2015. While the centrifuges were specified to produce a 22% TS biosolid from a polymer input of 23 active pounds per dry ton of solids, these machines have averaged 16% TS biosolids with a typical dosage of 44 active pounds per dry ton of polymer. While some marginal improvement occurred in the biosolids, the centrate produced from these machines worsened, averaging approximately 1,100 mg/L TSS which has burdened downstream centrate handling processes. With continued struggles to produce a higher solids content product from the centrifuges, in August of 2019 TMWRF submitted their sludge for further laboratory analysis to determine the maximum mechanical dewaterability. The results indicated that the sludge grab sample had a maximum achievable TS content of 15.8%. Also noted was the high phosphate concentration (292 mg/L) and volatile solids content (73.8%) present in the sludge liquor. Streaming current detector measurements were carried out to quantify polymer demand and indicated an optimal polymer dosage of 40 active pounds per dry ton. Direct TWAS Dewatering Study and Results: Given that many of the factors negatively affecting dewaterability stemmed from the TWAS sludge and were independent of the centrifuge, a study commenced to determine to what extent this sludge could be dewatered directly. With no beneficial reuse customers, the only standard to meet for TWAS biosolids was to pass a Paint Filter Liquids Test in order to be landfill compliant. After several discrete trials demonstrating this was possible, full-scale direct TWAS dewatering was implemented on June 9, 2020. After the passing of several detention times within the digesters, TWMRF experienced marked improvement in sludge dewaterability of their digested sludge with it being solely comprised of primary sludge. This digested primary sludge demonstrated the ability to consistently produce over 20% total solid biosolids with the highest achieved solids content of 28%. The waste activated sludge has shown to have nearly the same level of dewaterability as the historic sludge, averaging near 15% total solids without presenting any disposal concerns. In the time since beginning the experiment, there have been profound impacts throughout the treatment plant. The centrate, which had historically provided nearly 30% of the ammonia loading to the facility, saw a rapid and sustained decrease of 47%. This has significantly improved the nitrification and denitrification operations present at TMWRF as well as enabled more capacity for their nitrifying trickling filters. This reduction in ammonia translates to a lower loading into the denitrification process, resulting in an annual methanol savings over $200,000. Through the direct dewatering of the TWAS, a sharp decline in concentration of orthophosphate within the centrate has also been observed. This concentration has reduced from approximately 250 mg/L to less than 100 mg/L and as a result has removed the need for centrate sidestream phosphorus removal. The decommissioning of this additional treatment and associated chemical consumption has created a benefit of nearly $250,000 per year. The other large impact to chemical usage that TMWRF has experienced is a reduction in polymer usage. Waste activated sludge is thickened in a dissolved air flotation thickener and had previously utilized polymer to maximize TWAS total solids. This dosing has since been discontinued since the centrifuge design parameters require a lower feed solids content. Overall, this has led to a 20% reduction in polymer use, creating an annual savings of approximately $170,000. The continued duration of this project has identified other numerous benefits such as a 26% reduction in the hydrogen sulfide of the digester biogas, consistent phosphorus loading reducing aluminum sulfate demand, ability to achieve higher centrifuge hydraulic loads, and realized capacity of the digestion process. The demonstrated benefits of this full-scale experiment have resulted in its recommended implementation in TMWRF's latest facility plan, prompting an addition to TMWRFs Capital Improvement Program to begin analysis for making it a permanent process. This paper will outline the common challenges that EBPR sludge has on dewatering and the historical poor performance solids processing of TMWRF. Insight will be provided on a variety of operating configurations such as pure TWAS dewatering versus TWAS/digested primary sludge blended centrifuge feeds and the impacts of these on centrifuge outputs and total biosolids volumes produced. Detailed discussion will occur on the utilization of direct TWAS dewatering as an effective nutrient removal process not only for ammonia and phosphorus, but also for organic nitrogen.

Introduction In recent years, several regions of the country have experienced skyrocketing biosolids management costs. Though the triggers may be unique to each region, management capacity constraints are at the heart of these trends. Additional factors, such as concerns over PFAS in states like New Hampshire and Maine, have placed additional pressures on an already tight market. As utilities in regions like New England, Metro Atlanta, and the New York-New Jersey metro area are experiencing increases of 50-100% in biosolids management costs, the option of thermal drying may be a logical solution with respect to volume reduction and improved product quality. In several recent projects, Brown and Caldwell has integrated local market analysis, particularly trends in biosolids management costs, with traditional life cycle cost analysis in order to assist utilities in determining whether thermal drying could be a solution to mitigate risk around biosolids management. While no single answer applies, there are markets for which drying simply for volume reduction can curb rapid cost increases today, while other markets (particularly where natural gas costs are high and end use costs are not rising at as rapidly) would not necessarily trigger the need for such an upgrade. We will present an overview of the factors that go into such an analysis, as well as two recently completed case studies with different outcomes. Methodology The analysis begins with the end in mind, by assessing the regional market pricing trends for biosolids management. Opportunities for use of thermally dried products were also assessed at this point, to understand whether market capacity exists regionally for product acceptance. When coupled with costs associated with the current operation, this constitutes the baseline and provides some boundary conditions for a sensitivity analysis around end use costs. Alternatives were then built to incorporate both capital and life cycle costs including additional labor, chemicals, natural gas, and end use costs. Sensitivity analyses were then run live in a workshop setting around areas of risk, including end use and energy costs. Results and Discussion In the first case study, the cost of continued landfill disposal of unstabilized solids was compared against installation of a thermal dryer. Given regional market volatility and shrinking landfill capacity, landfill disposal cost projections were escalated at current (10%) and historic (5%) annual trends. A conceptual dryer design was developed to identify realistic capital and annual operating and maintenance expenditures and assessed over a range of end use scenarios from landfill disposal, contracted land application, sale to specialty markets, and onsite dried product pyrolysis. The lifecycle cost assessment, displayed in Figure 1, demonstrated that (1) thermal drying provided a strong economic benefit at the current rate of landfill disposal cost escalation, (2) thermal drying was economically viable even if landfill tipping fees returned to more steady, historic escalation rates and (3) the resulting volume of dried product did not provide the cost differential required to justify the additional capital expenditure for pyrolysis or added operational and maintenance complexity for pelletizing and bagging operations to sell to specialty markets. In the second case study, solids are already digested to Class B, and management costs are approximately $50/wet ton. When compared against other Class A alternatives, thermal drying was the preferred alternative on a life cycle cost basis. However, with multiple capital upgrades necessary, this utility wanted to assess when the best time — purely from a cost standpoint — would be to upgrade to Class A. Market analysis was used to predict possible cost trends for biosolids management over the next twenty years. Looking at a range of scenarios, shown in Figure 2, the BC team assessed the possibility of constructing a thermal dryer near term, 10 years out, or 20 years out. Given the anticipated rate of change of end use management fees, it was determined that building the project immediately was not necessary. Given the great degree of fluctuation in the regional biosolids market, it was preferred to monitor market trends and plan for a thermal drying facility as tip fees approached $150/wet ton. While it is anticipated that tip fees will rise that high within the 20 year planning period, it is unlikely to occur within the next 10 years, thus allowing this utility to prioritize other necessary projects. Conclusions The economic justification for installation and operation of a dryer is based on its resulting cost differential in residuals management. Emerging trends such as potential PFAS regulations and shrinking disposal outlets bring uncertainty to planning projections, but economic assessment tools that incorporate market fluctuations can be used to characterize a targeted set of future scenarios to provide a transparent and defensible basis for dryer feasibility. In comparing thermal drying against multiple scenarios for landfill tipping fee escalation, the utility in the first case study developed a clear understanding of the dryer's economic viability and the relative value of additional investments (e.g. pelletizer or pyrolysis). Market assessment can also bring greater certainty to economic evaluations by identifying target markets for dried product distribution and future trends within those markets. The second case study highlighted that understanding the market's anticipated rate of change can help pinpoint when installation of a dryer will be most effective in achieving cost control compared to alternative management options to assist with capital planning. Given that biosolids management costs are expected to continue to pose a threat to multiple US geographies, these case studies provide a valuable framework for the utilities assessing thermal drying to deploy the most viable solution given their local conditions.

Clayton County Water Authority (CCWA) provides clean, quality drinking water and wastewater collection and treatment to its estimated 275,000 residential, commercial, and industrial customers in Clayton County, GA as well as portions of Fulton County and Henry County. CCWA recently developed a performance management model that identifies strategic and operational metrics aligned with its strategic goals for each department. To effectively track and communicate organizational performance against these metrics to stakeholders, CCWA sought to select an enterprise business intelligence (BI) software to be deployed across the organization. The first step to successful selection and implementation of an enterprise BI software was to develop a robust understanding of CCWA's existing software architecture. Data characterization workshops were held to identify software systems and databases used by each department and distinguish them by hosting environment, user groups, integration with other databases or software systems, general functions, workflows, and reporting needs. This information served as the basis for creating a detailed software architecture map, which provides CCWA with valuable insight into their existing system and a vision for how an enterprise BI software would tie into their existing infrastructure. Information gathered during the data characterization workshops was also critical in defining the BI software evaluation criteria. An initial list of performance criteria was developed based on industry experience and narrowed to focus on key areas of interest for each department within CCWA. The final criteria included a variety of attributes for enterprise BI software including: - Compatibility, which focuses on the ability of the software to integrate with CCWA's existing system and transform data into the correct structure required for creating dashboards. - Development and Maintainability, which includes support for a mature formula language, a scalable and flexible data model structure, integrated metadata capabilities, and consideration for staff resiliency. - User Interface, which centers on the ability of the software to create compelling, easily understood, interactive visualizations of CCWA's strategic and operational metrics. - Ecosystem Capabilities, which considers the ability of the software to enable platform security, administration, and sharing in cloud-based and on-premises environments, and the ability of the software to integrate machine learning techniques. - Market Stability, which focuses on how well the company that owns the BI software has supported its development and innovation in the past and the company's vision for the future. Taking time to gather input from a variety of stakeholders including Board members, general management, department directors, and CCWA staff was critical to the successful selection and implementation of the enterprise BI software. Clearly demonstrating how stakeholder input from the data characterization workshops was incorporated into the BI software evaluation criteria promoted interest, buy-in, and trust across the organization. This presentation will discuss the collaborative approach used to evaluate and select an enterprise BI software including data characterization, development of selection criteria, software evaluation and testing, selection of a final enterprise BI software, and development of a roadmap to ensure successful implementation.

INTRODUCTION
The Albuquerque Bernalillo County Water Utility Authority (Water Authority) owns and maintains over 2,000 miles of pipes in the collection system to convey approximately 50 MGD wastewater from the service area to the Southside Water Reclamation Plant (SWRP). The Water Authority has implemented a range of methods and technologies for controlling odors and corrosion in the collection system, resulting in significant institutional knowledge and experience of this branch of engineering science. Nevertheless, the sewer network still faces corrosion challenges due to sulfide generation with numerous pipes that are at risk of collapse. Comprehensive analysis of a complex collection system to allow for the optimization of sulfide control relies on the understanding and quantification of the processes impacting sulfide production and release (Revilla et al, 2016). To facilitate this intricated task, properly implemented sewer process models become a valuable tool. This implementation could also support the evaluation of the impacts of the sulfide control strategy on the SWRP process performance. The objective of this project was to marshal and organize the resource expenditure on odor and corrosion control so that it is optimized, coordinated across the collection system, and harmonized with the pipe rehabilitation program and the identified operational constrains of the SWRP. A novel approach using sewer process model (the WATS model) was implemented to develop a comprehensive sulfide control strategy, and to empower the Water Utility with a tool to support the migration from a reactive to a proactive approach on asset management while being able to communicate to SWRP staff the potential impacts in the treatment process.

METHODOLOGY
The study area for the Water Authority collection system included approximately 250 miles of pipe with a minimum diameter of 15 inch in four main interceptors (plus tributaries). A sewer process model was used to apprehend the study area as a whole and analyze physical, biological and chemical processes bearing on odor and sulfide corrosion. Data Collection. The Water Authority collected data on several parameters as part of the regular monitoring program for the collection system in 17 locations and the influent to the WWTP. These included grabs samples for wastewater temperature, pH, total and dissolved sulfide, total iron and continuous monitoring of headspace hydrogen sulfide. Additional monitoring at each of the most downstream location in the four interceptors was performed. Sewer Process Modelling. The WATS model (Hvitved-Jacobsen et al, 2013) was selected as the most appropriate software tool for this purpose. WATS is currently the most rigorous and complete sewer process model in the world and is well suited to assessing the Water Authority sewerage. The model was set up using the existing hydraulic model of the system and considering the operation of the collection system at the time of the selected calibration period in terms of flow diversions and chemical addition. Considerations for the optimization strategy in the collection system were in place to prevent negative impacts in the SWRP: 1) a minimum pH of 7 in the plant influent needed to meet the permitted effluent pH; 2) a maximum magnesium concentration in the influent to prevent formation of nuisance struvite (impacts use of magnesium hydroxide); 3) a limit in the use of solids produced in the potable water treatment plant that have the potential to be used for sulfide control if discharged to the collection system.

RESULTS AND DISCUSSION
Model Calibration The WATS model for the Water Authority collection system was calibrated to dissolved sulfide and headspace hydrogen sulfide in the 17 monitoring locations throughout the four interceptors. In addition, diurnal pH data was available to refine model calibration. Data for winter and summer were available and seasonal models were developed to allow for a more detailed strategy for optimizing sulfide control. Stochastic simulations (n=100) were run and the results compared to the complete data set for the calibration period. Figure 2 shows measurement-model agreement for station 10. Alternatives analysis for sulfide control optimization The calibrated WATS model allowed for the screening of a wide range of alternatives, including chemical dosing at various dose rates using different chemicals at various locations, and assisted in the prioritization of pipe rehabilitation given the relative cost of on-going chemical treatment versus rehabilitation. The screening resulted in novel and the most cost-effective strategies with potential to be implemented in each of the four major interceptors. Some of this approaches include: Addition of iron-rich water treatment plant solids. The San Juan Chama Water Treatment Plant can discharge residual sludge containing high levels of iron for sulfide control in the collection system. Bench-scale testing provided the input to the WATS model in terms of sulfide removal efficiency. It was determined that the amount of solids the SJCWTP was limited to discharge to prevent negative impacts at the SWRP was enough to provide comprehensive treatment for the Edith Interceptor and partial treatment at the Valley Interceptor. Comprehensive treatment at the Valley Interceptor was achieved by dosing Iron for the upstream end and by applying PRI-SC to reach sulfide control at the downstream end of it, providing the most cost effective approach. Iron addition with pH adjustment and Peroxide Regenerated Iron for Sulfide Control (PRI-SC). An evaluation was performed using the WATS model combining chemical dosing for a synergistic and cost-effective interaction between Mg(OH)2, ferric and PRISC. As shown in Figure 2, the Westside Interceptor relies on iron addition in the upstream end of the system with pH adjustment using Mg(OH)2, recognizing that sulfide precipitation rate increases as pH approaches 8 units (Hvitved-Jacobsen et al, 2013). This treatment targeted Station 64 where the PRISC process allowed for a more cost-effective solution to achieve comprehensive treatment to the nearest pump station. In addition to considering the limitations set by the SWRP influent characteristics to protect plant operation, a qualitative assessment of the impacts of the optimized strategy on the performance of the SWRP resulted in potential benefits to sulfide control in the solids train; SWRP better prepared for potential stricter phosphorus limits; and) an increase in soluble substrate for enhanced BNR. The optimization routine using WATS resulted in chemical selection and dosing maximizing existing infrastructure while maintaining wastewater characteristics in the SWRP influent within the constrains identified by plant operations.

CONCLUSION
The careful implementation of the WATS process model to the Water Authority collection system allowed for the understanding of the processes bearing in sulfide production and release, and for the screening and identification of alternatives for controlling sulfide in the system as a whole and in an optimized manner. The results confirmed that the presented methodology allows for the incorporation of modelling tools in the decision making for management of collection systems.

Steep Slopes, Odors and Corrosion Flow Together Richard J. Pope, P.E., BCEE Vice President - Hazen and Sawyer For over 100+ years sewer designs have maximized gravity in pipes/conduits to convey wastewater to the treatment facility. Unfortunately, land contours and obstructions require that pumps be used to lift and/or convey the wastewater vertically through force mains to reach a point where the wastewater can again run by gravity. This process is repeated as many times as it takes until reaching the treatment facility. The point where the force main ends and the wastewater flow turns back to gravity is commonly at a high point in relationship to the surrounding landscape to again take advantage of gravity. Sometimes the slope of this force main discharge is steep enough to create a negative air pressure in the pipe headspace, as the drag from the downward movement of the wastewater sucks air in. In many cases this force main discharge connects with another downstream sewer/interceptor line that has a flatter slope. The pipe intersection of a steep slope with a flatter slope, is known to create a hydraulic jump as the faster moving wastewater from the steeper slope pipe tries to overrun the slower moving wastewater. This causes a 'jump like' action in the flatter slope pipe. These features associated with force mains have been recognized and understood since the initial designs of collection systems. But it has taken decades for the engineering community to observe and understand the odor release and corrosion potential of these features. For too long our sewers have suffered from being out of sight and out of mind, and generally ignored. The recent heightened focus on wastewater facility and collection system asset condition and management, helped to open our collective industry eyes on the potentially devastating impact that these features can impart. Regarding these physical layout features, it is not clear that engineers have always anticipated the ramifications of their designs and how the physical layout of the sewer pipe network can exacerbate both odor formation and release. Odor release encompasses stripping from the wastewater into the headspace of the sewer where it travels through laterals and house connections, as well as escaping the confines of the sewer headspace into the ambient atmosphere where it can impact communities, properties and homes. This paper focuses on a typical physical sewer layout that has been designed by engineers for years and is common to many collection systems: the fast-moving wastewater flow of a steep slope pipe and the intersection where it meets a flatter slope pipe. These physical layout features occur quite often, particularly at the discharge end of a force main where it breaks to a gravity line. Our discussion is not intended to direct engineers to avoid these situations, that is likely impossible given local topography issues, but to recognize these transition zones for what they are, understand how the wastewater and airspace within the sewer will react and protect against their potential impacts. A few of the key issues with the steep slope and transition zone where steep and flat slopes intersect include: Steep slope sections of pipe create a negative air pressure along that line as the wastewater drags the headspace air with it as it accelerates downward. That vacuum can create a positive impact as it draws outside air into the system to replace the air it is dragging downstream. It can create a negative impact if the vacuum is strong enough to drain the water out of lateral and house traps that are in place to keep sewer gases out of upstream lines/homes. Hydraulic jumps occur at the transition zone, which means an area of high turbulence. Turbulence is directly related to stripping odors from the wastewater. The intersection of fast-moving water meeting slow moving water also creates a positive air pressure shock wave that radiates out and away in both directions from the transition zone. These are real problems facing many communities across the country. Four different case histories will chronicle the impact that these physical layout features, steep slope and intersecting steep and flat slope sewer pipes, had on the surrounding communities and the steps that were taken to address it. The four case histories represent: California creating nuisance odor problems for a downtown community New York intersecting steep and flat slope sewer odor release was followed and aggravated by an inverted siphon Kentucky a simple solution to odors released from intersecting steep and flat sewers saved a lot of money, capital and operating Kentucky house traps connected to a steep slope sewer were emptied, and odors were found in the homes. A background will be presented along with the approach taken and the solutions implemented for each of these case histories. In the bigger picture, practical examples like these should remind engineers that their designs need to consider the potential odor and infrastructure corrosion conditions that they may cause and include ways to address them.

PURPOSE
The Kenosha Water Utility (KWU) provides wastewater service to more than 100,000. Rising Lake Michigan water level put the wet weather capacity of the KWU Water Reclamation Facility (WRF) and collection system at risk. The collection system includes multiple wet weather control elements. Rapidly rising water level in 2019 rendered one critical control element in the collection system unusable. This abstract details the response to protect the property and citizens of Kenosha which resulted in an operational 70 MGD pump station just 7 months after the initial concept.

COLLECTION SYSTEM
KWU's collection system is a separated sewer system with significant infiltration and inflow during storm events. The WRF operates up to 100 MGD peak day flow. However, the collection system can experience flow in excess of 200 MGD during extreme storm events. The collection system has two significant flow control elements when unusually high peak flows are experienced: 1. Equalization (EQ) Basin rated for an influent flow of 136 MGD 2. 3rd Avenue overflow structure for conveying excess system flows to Lake Michigan via a 99-inch storm sewer, after the Equalization Basin is full During short term storm events, water in the EQ basin is drained back into the collection system to the WRF headworks. In an extended storm event, the EQ basin fills and water overflows to the WRF chlorine contact tanks. The EQ basin overflow is limited to around 30 MGD. If the storm event continues, the collection system continues to back up and water begins overflowing at the 3rd Avenue structure. The structure has a gravity overflow weir; overflow is combined with storm water and flows by gravity to Lake Michigan. The overflow is typically used once every few years; however, the frequency has increased in the past decade. Flow is highly variable by storm event. During a major storm in July 2017, the estimated peak overflow was 80 MGD. The July 2017 event resulted in multiple basement sanitary sewer backups.

LAKE LEVEL
Lake Michigan water level has risen from around 576.00 ft in 2013 to 580.50 ft in 2018. Lake Michigan water level varies during any given year; see Figure 1. Due to rising water level, the 3rd Avenue overflow weir was raised to prevent lake water from back-flowing into the collection system. This change reduced the overflow capacity and increased the overall hydraulic profile in the collection system. As a result, the risk of basement backups has increased.

PLANNING
KWU recognized that it was time for planning and action in late 2018. At that time, a system wide study was completed to evaluate wet weather protection alternatives for the WRF and collection system. The alternatives included variations of these improvements: two WRF outfalls, WRF effluent pump station, WRF hydraulic modifications, 3rd avenue excess flow pump station, excess flow treatment, and separate EQ basin flow treatment and discharge. The alternatives provided varying degrees of wet weather treatment, but all achieved management of 220 MGD collection system flow at the 100-year flood elevation. The projects ranged in cost from $10M for the excess flow pump station and two WRF outfalls to $25M for full flow disinfection and WRF effluent pumping.

DESIGN
By the time planning was completed, Lake Michigan was near record water level. Excess flow could not be conveyed by gravity through the overflow structure; see Figure 2 for a hydraulic elevation diagram. KWU needed a fast response; however, the projects proposed in planning would take 2 to 3 years to design, permit and construct. Emergency pumping options were explored. Diesel driven centrifugal pumps were considered; however, six large pumps are needed for 50 MGD capacity and space was limited. The vendor offered diesel powered, hydraulically driven submersible axial flow pumps. Two axial flow pumps could achieve 70 MGD. The cost of the axial flow pumps was about $1M compared to $2M for the centrifugal pumps. Axial flow pumps were preferred because they provided more flow, could be placed in the existing storm water outfall and were lower cost. Due to the configuration of the outfall, one axial flow pump was located in the 99-inch storm sewer and one located in the outfall structure. Passive overflow at the 3rd Ave structure from the sanitary sewer to the 99-inch storm sewer continues via a flow control weir. Pumps transfer excess flow from the storm sewer to Lake Michigan.

CONSTRUCTION
KWU purchased the axial flow pumps and power packs in August 2019. The Contractor began construction of the pump station in September 2019 and completed the work in December 2019. In January 2020, the pump station was tested using water from Lake Michigan. See photos of the submersible pumps and pump station attached. OPERATION On May 17, 2020, the emergency pumps got their first real test. Kenosha received 3-1/2 inches of rain just days after previous rainfalls. The collection system flow was estimated at 200 MGD. The Lake Michigan water level near 583.00 ft, a record high elevation. The WRF was operating at 100 MGD with the influent wet well 10 ft above normal operating level. The EQ basin was full, 2 EQ basin pumps were operating, and EQ flow was traveling to the WRF. The 2 emergency pumps at 3rd Avenue were operating during the event. In the beginning, at a low overflow rate, the pumps operated intermittently as needed. As the overflow rate reached up to 70 MGD, the pumps operated more frequently. The entire system was able to handle the 200 MGD event.

CONCLUSIONS
The submersible, hydraulically driven pumps in an existing structure provided a unique and much needed solution to an emergency situation caused by rising Lake Michigan water levels. The pumps successfully protected properties and the citizens of Kenosha. Without this unique solution, wet weather flows would not have been managed in May 2020 leading to widespread basement flooding. KWU continues to pursue wet weather management work to maintain or increase the collection system and WRF capacity. Ongoing work includes chlorine contact tank hydraulic modifications, WRF outfall modifications and disinfection expansion.

Introduction The Dry Creek Water Reclamation Facility (DCWRF), owned by the Cheyenne Board of Public Utilities (BOARD), is located in Cheyenne, Wyoming. Thickened waste activated sludge and primary sludge are anaerobically digested and the digested biosolids are pumped to high solids centrifuges for dewatering. The biosolids are transported across the site to air drying-beds for storage and supplemental air drying prior to offsite transport for beneficial use land application. A site map of the existing DCWRF biosolids processing sites are shown in Figure 1. DCWRF generates approximately 1,600 metric tons per year of primarily Class B biosolids. Some Class A biosolids product is produced by complying with the 'two-summer method' as allowed by the United States Environmental Protection Agency (USEPA). The air-dried Class A and Class B biosolids are land applied by the DCWRF staff at private ranches. Much of the soil in the region has low organic content and it is a challenge to successfully grow native grasses and crops without a significant amount of fertilizer. Therefore, the ranches benefit from the application of the organically-rich biosolids material. Challenges with the Existing Solids Processing Facilities The utility is currently facing numerous solids processing challenges including aging equipment as well as a potential loss of nearby ranch sites that had been used for land application. The uncertainty in the continued acceptance of Class B biosolids, due to change in ownership of the ranch sites currently accepting biosolids, will result in lower reliability and flexibility for solids beneficial use for the plant in the future. Faced with this potential future challenge, the BOARD selected Jacobs Engineering Group to evaluate Class A stabilization technologies that are appropriate for the needs of the utility. The production of Class A biosolids material that has multiple end-use markets would give the BOARD more reliability and flexibility to land apply in locations such as the City of Cheyenne's parks, open spaces, golf courses and sporting fields which would reduce hauling cost and the reliance on private farmers and ranchers. Ranchers would also be more receptive to land application of Class A biosolids. Objectives of the Evaluation The objective of this study was to compare the suitability and applicability of three different Class A drying alternatives including belt drying, solar greenhouse drying and hybrid drying (solar greenhouse and air drying) to DCWRF. The three alternatives were evaluated based on capital cost, operations and maintenance (O&M) cost as well as life cycle cost considerations. Additionally, a combined financial and non-monetary ranking and sensitivity analysis was performed. The advantages and disadvantages of each drying alternative, considering the plant's geographical constraints, were outlined. Alternatives Evaluation The thermal drying and solar drying equipment preliminary design criteria is shown in Table 1. The three alternatives evaluated are summarized below and a screw press was assumed to be the selected dewatering technology. The process schematic for Alternatives 1, 2 and 3 are shown in Figures 2, 3 and 4. The advantages and disadvantages of each alternative will be described in detail in the paper and presentation. The proposed solar greenhouse configuration location on the existing air-drying beds is shown in Figure 5. The proposed configuration of the hybrid solar greenhouse structure solar greenhouse located adjacent to the existing air-drying pads is shown in Figure 6. Results of the Evaluation Non-Monetary Evaluation Several non-monetary evaluation criteria were used in the assessment of the three drying alternatives. The results of the weighted benefit scores based on the DCWRF staff input are summarized in Table 2. Based on non-monetary considerations, belt drying and solar drying were shown to be the most beneficial to DCWRF, with essentially the same score, with solar drying being slightly better, while the hybrid alternative represented the least non-monetary benefits. The belt dryer ranked significantly higher in the product end use flexibility criterion. The hybrid and solar drying alternatives had lower scores for the odor generation criterion because operators are exposed to these odors for extended periods of time compared to belt drying odor exposure. Based on non-monetary considerations only, solar drying is the best alternative for the DCWRF, but belt drying is ranked approximately the same. Life Cycle Cost Evaluation In addition to non-monetary considerations, opinions of probable construction cost, annual O&M cost and net present worth costs were estimated for the three drying alternatives. Life cycle costs comparison are summarized in Table 3. The solar drying alternative had the highest life cycle cost followed by the belt drying alternative; while the hybrid drying alternative had the lowest life cycle cost. Based on relative cost ranking, the solar drying option is approximately 40 percent higher than the other two options. Combined Ranking and Sensitivity Analysis The cost rankings and non-monetary rankings for the different alternatives were combined and the total weighting rank was used to determine the best overall drying alterative. The combined ranking included the following three monetary to non-monetary ratios: 1. 30 percent weighting for cost and 70 percent weighting for non-monetary criteria 2. 50 percent weighting for cost and 50 percent weighting for non-monetary criteria 3. 70 percent weighting for cost and 30 percent weighting for non-monetary criteria The belt drying option ranked highest against all three weighing ratios and is therefore the preferred option. Conclusion The belt drying option ranked highest on all three weighting ratios, had the highest non-monetary ranking and the most advantages and was therefore the preferred option for the DCWRF. This presentation will be valuable to owners, operators and consultants that want to consider Class A drying alternatives. In addition to presenting the results of the study, advantages and disadvantages, preliminary and final design criteria, equipment layouts and cost estimates will be presented for the three drying alternatives.

Manatee County Utilities (MCU) recently completed a strategic enhancement to their decades long commitment to be a good neighbor to those in close proximity to wastewater collection system lift stations and treatment facilities. Historically a variety of liquid and vapor phase treatment approaches were utilized to prevent nuisance odor complaints. In 2018, MCU embarked on implementation of an enhancement to their successful odor control program that targeted reducing the hydrogen sulfide (H2S) related corrosive conditions in much of their collection system. As MCU operates an expansive collection system involving an extensive (over 700) lift station (LS) network with many long retention time force mains, achieving significantly lower H2S in the head spaces within lift stations and gravity sectors downstream of force main discharges was a major challenge. This paper provides further perspective gained with longer term operating experience and full system implementation. The collection system conveys 22 Million Gallons per Day (MGD) of flow across three service areas to a corresponding wastewater reclamation facility for each service area. The North Service Area (NSA), Southeast Service Area (SESA), and Southwest Service Area (SWSA) are comprised of many outlying lift stations (LS) with manifolded force main networks that feed re-pump stations. Some re-lift stations are known as master lift stations (MLS), which receive wastewater that in some cases is repumped four times; such as MLS 1M. Figures 1 and 2 provide perspective on the geographic expanse and force main network complexity. As MCU was experiencing significant corrosion of concrete and metallic components of the gravity system upstream of the MLSs and in the MLS wet wells while successfully preventing public odor complaints with a combination of chemical liquid phase treatment applied at key upstream LSs and biological vapor phase treatment with biofilters an enhancement to H2S treatment goals began in 2018. To significantly reduce corrosive conditions MCU set a target MLS atmospheric H2S control objective of 20 ppm average and 50 ppm peak. In most cases historical levels were five to twenty times these target values, so accomplishing these odor and corrosion (O&C) control targets required incorporating new treatment and operational strategies. By targeting such lower MLS H2S levels it was expected that corrosive conditions in upstream re-pump stations/gravity sectors and related downstream WWRF headworks would also be reduced. Based on a 2017 engineering study report, one key new liquid phase treatment approach implemented was to raise the wastewater pH from the typical 6.8-7.4 range into the 8.0-8.5 range. This was done in order to significantly increase the percentage of dissolved sulfide (DS) in the nonvolatile HS- and S2- forms rather than volatile H2S. Due to extremely long retention times generating very high DS levels (10-40 mg/L) in some force main networks upstream of most MLSs it was anticipated a combination of chemical treatments targeting pH elevation along with DS reduction could achieve MLS H2S control objective at many locations without a major increase in historical H2S treatment expense. Implementation started in the NSA, then moved to the SWSA, and finally the SESA. Continuous H2S monitoring of the MLS wet wells, provided by MCU's vapor phase treatment provider, was critical to evaluating impacts of introducing upstream magnesium (mag) hydroxide chemical treatment to raise the wastewater pH and optimize dose requirement of calcium nitrate at higher pH conditions. Ability to access web-based data on nearly a real time basis facilitated a highly data driven implementation approach on a MLS by MLS basin basis. Figure 3 shows an example of post implementation online H2S data for Heritage Harbour MLS, which is the result of two upstream mag dose locations to raise wastewater pH, two upstream nitrate dose locations to reduce DS, raised MLS wet well level to reduce turbulence, and MLS wet well ventilation to historical onsite biofilter. The technical paper will summarize significant H2S performance improvement achieved and enumerate lessons learned from the implementation periods and subsequent ongoing operation timeframes across sixteen MLS basins. While utilization of pH elevation was generally effective in reducing H2S release from wastewater received by the MLSs, practical limitations experienced due to the complex upstream manifolded force main networks, significant DS levels, and degree of wastewater turbulence will be covered. Ultimately a blend of wastewater pH elevation, DS reduction and turbulence reduction along with MLS biofilter ventilation adjustments unique to each MLS basin has resulted in dramatic reduction in H2S induced corrosive conditions within MLS wet wells, upstream LSs and gravity systems. Adjusting chemical dosing to reflect individual MLS basin sulfide generation dynamics related to seasonal flow/wastewater temperature changes, significant storm events, addition of new LS & MLSs, altering existing LS force mains, and collection system maintenance activity is an ongoing operational goal/challenge for MCU staff, their consultants, and O&C service providers. Tools and processes developed to facilitate ongoing optimization of the O&C program will also be presented.

Collection systems and treatment facilities serve as an important environmental line of defense against wastewater contamination of groundwater and coastal embayments. With more intense and frequent storm events and rising sea levels, many communities are facing an increased risk to critical wastewater infrastructure from flooding and storm damage affecting critical wastewater infrastructure (Figure 1). This presentation will use case studies for collection system infrastructure along multiple types of waterbodies to discuss flood resilience measures being evaluated and implemented in Southeastern Massachusetts. The case studies discuss collection system infrastructure along:
Complex coastal estuarine shorelines
Open ocean
Tidally influenced coastal ponds
Inland river flood plains
The presentation will also focus on how these communities are incorporating accommodations for projected changes in storm intensity and frequency into flood resilience evaluation, design and construction. A brief description of each case study is summarized below. Town of Wareham (complex coastal estuarine shorelines) - The Town of Wareham is a coastal community with over 54 miles of coastline. Hydraulic constrictions caused by the complex coastal estuarine system results in high anticipated flood levels, up to 21 feet above mean sea level. The Town recently completed a 'Risk and Vulnerability Assessment', which provided them with a valuable tool to quantify the anticipated costs borne to the Town and its citizens if any vulnerable pump station failed during a 100-year storm event. The assessment allowed the Town to prioritize which of its many competing coastal resilience wastewater infrastructure needs to address first. Building on the findings of the Assessment, the Town is proceeding with the design of coastal resilience mitigation measures for three pump stations which were among the highest priority stations because they serve critical infrastructure (a hospital, fire department and police department). Coastal resilience measures incorporated into the design include the use of flood planks, structural reinforcement of existing structures (Figure 2), sealing potential water entry points and installation of emergency bypass connections (Figure 3). Additionally, following multiple Nor'easter storms in 2018 that exceeded the regional 40-year flood stage record, the Town conducted an evaluation of the impact of anticipated increased rainfall from more frequent and intense storms on the infiltration/inflow entering its collection system. The repetitive, consecutive nature of the 2018 storms elevated the groundwater table, producing more head pressure in the gravity collection system and dramatically increasing infiltration rates entering the collection system and being conveyed to the Wareham Water Pollution Control Facility. The Town is currently completing final design of retrofit measures recommended by the I/I projections evaluation (Figure 4). Town of Oak Bluffs (infrastructure exposed to the open ocean) -The Town of Oak Bluffs is a coastal community on the island of Martha's Vineyard. Its three vulnerable stations serve over 90% of the Town's sewered population, including many residences and the Town's primary commercial district (Figure 5). The Town recently completed the construction of mitigation measures to increase the coastal resilience of the stations through installation of a new emergency generator on a raised platform (Figure 6) and relocation of critical pump station equipment outside of the flood zone. Town of Chatham (tidally influenced coastal pond) - The Town of Chatham is a coastal community on Cape Cod. One of the Town's wet pit/dry pit pumping stations (Mill Pond) is located at the base of a tidally influenced coastal pond; updated FEMA flood maps show that the location is vulnerable to storm surges and flood events. During the Mill Pond Pumping Station Upgrade design, multiple flood protection measures were incorporated to increase the coastal resilience of the station. These measures include the establishment of a design flood elevation for the project which incorporates anticipated effects of sea level rise, installation of hydrophilic water stops and a flood proof entry door with stop blocks to provide flood mitigation measures (Figure 7). Town of Uxbridge (inland river flood plain). The Town of Uxbridge is an inland community in Central Massachusetts. Since construction of its centralized collection system the Blackstone River flood plain maps have changed and recent storm events have indicated that one of the Town's major pump stations is now vulnerable to the 100 year flood storm. During one storm event water was observed entering the station's wet well through conduits and rising within a couple inches of the top of the entrance tube (Figure 8). Additionally, the existing generator room was flooded, rendering equipment in the room inoperable during the storm event. The Town is currently constructing mitigation measures to increase the flood resilience of this equipment, including raising vulnerable infrastructure above flood levels.