Conference Papers

The English Coulee meanders through Grand Forks, North Dakota and has many important uses to the City not only drainage and interior flood protection storage but also pedestrian walking / biking corridor and active recreation opportunities such as ice skating and paddling. Given that the English Coulee serves a watershed over 50 square miles that is dominated by agricultural land use, the coulee has been plagued by issues related to E coli and phosphorous. Further, as Grand Forks continues to grow, urban runoff quality is also providing significant loading. Finally, a significant hydrologic / hydraulic alteration to the English Coulee was made about 20 years following the catastrophic 1997 Red River flood that destroyed much of the City - the English Coulee Diversion was constructed as part of the interior flood protection system that aids in protecting the City from Red River floods. This diversion cuts off much of the agricultural watershed but also reduces the potential for high springtime flows to flush sediment and nutrients that have accumulated in the coulee within the City. The stagnant water conditions throughout much of the summer combined with the likely high nutrient concentrations create severe aesthetic and odor issues related to algal blooms and anoxic conditions. While the coulee is listed as an impaired 303(d) waterway, the City decided to begin their own multi-phase initiative to renew the coulee given its benefit to the community as a recreational resource. The first phase of the project focused on answering the question 'what could be done?'. To answer this question, the first phase involved three key components: 1) public outreach and engagement, 2) water quality monitoring and modeling, and 3) hydrologic / hydraulic monitoring and modeling. A unique approach to public engagement was used with signs along the coulee with QR codes that pedestrians could scan and bring the online survey up on their phones. The public engagement survey received over 500 responses with an overwhelming response that the community wanted to see the Coulee's water quality improved. Water quality monitoring was also completed for numerous parameters that confirmed the community's observations nutrients (namely phosphorous), suspended sediment, and E coli were all very high throughout the year. Water level data was also collected at several locations that indicated that FEMA's hydrologic and hydraulic analysis did not reflect the complexity of the coulee hydraulics, illustrating the need to create a more robust hydrologic / hydraulic model of the coulee system to evaluate potential watershed and channel / dam modifications. The second, ongoing phase of the English Coulee Renewal Plan aims to answer the question 'What should be done?' with subsequent phases aimed at implementing projects to improve water quality in the coulee.

The Southwest Florida Water Management District (SWFWMD) began the watershed initiative program to provide comprehensive understanding of watersheds. The Withlacoochee Watershed Initiative delved into providing an understanding of the complexities of the Withlacoochee River and utilizing a modeling approach which uncovered many of the longstanding uncertainties surrounding the river. The Withlacoochee is a unique riverine system, winding 160 miles northward through eight Central Florida counties before eventually discharging into the Gulf of Mexico. The Withlacoochee River was called by its earliest inhabitants 'We-Thalko-Chee' or 'Little Big Water', characterizing the great fluctuations between drought and flood that are commonly exhibited by the river due to naturally changing hydrologic conditions. This complex system covering over 2000 square miles was one of the least understood in the region and yet because of its beauty, drew homeowners flocking to its banks. While alterations over the past 130 years have attempted to control this natural wonder to suit commercial navigation, industry, and private needs, the river continues to plot its own course. True to its name, homeowners on the Withlacoochee have experienced extreme drought followed by lasting floods, exemplified in Figure 1. In recent decades, public meetings and workshops involving stakeholders, special interest groups and residents identified several critical issues and ideas to either restore or further alter portions of the system. To comprehensively address those concerns, a first of its kind computer model of the entire Withlacoochee River and its surrounding watershed was developed. This included an unprecedented effort to map the entire bottom of the Withlacoochee River from the Green Swamp to the Gulf of Mexico and calibrating the model to the devastating 2004 Hurricane Season.

METHODOLOGY
To address the unique characteristics of the river and watershed, a comprehensive model was developed using the Interconnected Channel and Pond Routing software version 4 (ICPRv4) created by streamline technologies in Orlando, Florida. This computer model can simulate one-dimensional flow in channels as well as two-dimensional flow in wetlands and marsh areas, both of which are prevalent throughout the Withlacoochee River watershed. This flexibility was necessary to account for the river conditions which were alternatively a wide expansive marsh transitioning to a deeply channelized river section. High resolution LiDAR data supplemented with field work was used to characterize the hydraulic parameters in the watershed, exemplified in Figure 2. This detailed data combine with automated techniques for understanding and delineating the watershed boundaries served to guide the model development process. Additionally, the model was able to account for the volume and timing of contributing inflows from the surrounding watershed using dynamic rainfall inputs and varying initial water levels. This was a critical element since water levels and flow along the river are a direct result of spatially varied rainfall and the watershed's antecedent conditions. In the low condition, water is contained within the main channel and rainfall on the surrounding land will infiltrate prior to contributing flows to the river. In the high condition, water levels are higher and the surrounding land is inundated. Subsequently, when rainfall occurs, runoff immediately causes river levels to rise and flows to increase, since the watershed's soils are already saturated. Because the ICPRv4 model simulates hydrology and hydraulic conditions in parallel, these dynamic changes in soil moisture can be accurately simulated.

RESULTS
Calibration The river model was calibrated to over 20 USGS gauging stations over a three month period in 2004, which started in drought conditions until three hurricanes crisscrossed the watershed, sustaining flooding conditions for months. Despite the numerous calibration parameters available in ICPRv4, initial model results would not converge to the measured data. This prompted additional field work and ground truthing of model assumptions. During this process, it was learned that significant portions of the terrain, particularly in marsh area incorrectly depicted ground conditions. It was learned that the model was highly sensitive to storage and overland flow roughness within 2D zones. Correcting the terrain lead to a more accurate flow regime and ultimately a calibrated model. Resulting hydrograph depicting the rise in water level between modeled and measured data is seen in Figure 3. The model accurately depicted the more than two week lag time between headwater and discharge into the Gulf of Mexico. As seen in the graph, following each hurricane, water conditions sharply rise, yet do not fall quickly, rather remain high, setting an inundated condition subsequent storm events. In this watershed, the reality of highly variable initial conditions became a key feature in understanding flood levels throughout the watershed and inflow tributaries. Scenarios Working with SWFWMD staff and stakeholders throughout the watershed, both past and present concerns were documented, ultimately resulting in 19 scenarios as shown in Figure 4. These scenarios are designed to determine what effect historical or future changes might have on water levels and flows throughout the entire river and watershed. Results indicated how management strategies can optimize the balance between retaining water high for recreation, while being able to evacuate it prior to catastrophic events. Results indicated which river alterations would have had a positive impact on flooding conditions during the hurricane events, and which would not.

CONCLUSION AND DISCUSSION
In the initial phases of the project, the public was skeptical of the overall process, accusing the water management district of mismanagement of the resource and being the cause of both extended drought conditions, as well as, the prolonged flooding conditions. Through a series of public meetings, transparency of the modeling approach, and ultimately demonstrating that the calibrated model would accurately predict conditions in the watershed, a trust was built with these concerned citizens. This trust extended to the results of the 19 model scenarios including those demonstrating existing water management procedures and simulations demonstrating proposed alterations to those procedures. The modeling effort and the project itself are a first of its kind floodplain mapping using a 2D model and providing an understanding of a complex river system. But what makes this project truly unique is its ability to transcend the algorithms and modeling complexities and connect with the public. This calibrated model and this project was able to heal the wound of an irate public skeptical of the water management district practices. These results now serve as the best available data in the region and the model approach for large watershed studies in the Water Management District.

Introduction and Background Historically in Georgia, a large proportion of biosolids produced in the state has been disposed of in landfills. This proportion has grown over the last several decades because of the implementation of regulatory changes such as the sanitary sewage sludge incineration rules and landfilling costs have remained relatively flat compared to disposal and beneficial use alternatives. In recent years, landfill disposal of biosolids in Georgia has become much more challenging with landfills either significantly increasing tipping fees or not accepting biosolids. These challenges have been driven by increased regulatory focus on landfill disposal of biosolids following several slope failures that occurred in Georgia, including one at a major landfill in the metro Atlanta region in 2018. The Georgia Environmental Protection Division (EPD) has approved additional legislation (via changes to Georgia's Solid Waste Management Rule 391-3-4) that requires any landfill accepting more than 5 percent high moisture content waste (HMCW) to have a HMCW management plan in place to document mitigation measures for receiving this material. HMCW is classified as anything with a moisture content of greater than 40 percent by weight (i.e., less than 60 percent dry solids). Typical biosolids dewatering installations generate a product with a dry solids content between 15 percent and 25 percent, which is classified as HMCW. While facing challenges with respect to landfill disposal, there are also potential opportunities to make use of biosolids as a resource. Biosolids contain valuable nutrients and organics, presenting potential opportunities for beneficial use as fertilizers, soil amendments, or for energy recovery. Project Details and Outcomes Acknowledging biosolids challenges faced by Georgia wastewater utilities, the Georgia Environmental Finance Authority (GEFA) commissioned Black & Veatch to perform a study to evaluate the challenges and opportunities related to biosolids management in the state and provide recommendations regarding strategies and funding for biosolids management going forward. A summary of the study scope and objectives is provided in Table 1. This presentation will highlight the key project outcomes and opportunities to aid utilities in the State as they pivot towards diversifying biosolids management practices. Key project outcomes that will be presented are listed below. - Results of a statewide survey that captured 80% of the estimated wastewater flow in 2019 and informed the National Biosolids Data Project for Georgia. Survey respondents provided information regarding the costs of biosolids management and end use, interest in partnering with other organizations for regional solutions, and feedback regarding funding mechanisms. See Figures 1 and 2 for more detail. - A gap analysis of current and future biosolids production estimates compared to available landfill capacity to accept high moisture content waste and available outlets for beneficial reuse, e.g., agricultural land area suitable for biosolids land application. See Figure 3. - Opportunities and recommendations to assist utilities with alternative biosolids management strategies. This includes co-processing with municipal solid waste, modifications to GEFA funding initiatives and application criteria, and regional management strategies to capitalize on economies of scale. See Figure 4 listing opportunities and barriers to regionalization. The study produced a regionalization roadmap to guide utilities through potential avenues to regional solutions. Conclusion Although this study is specific to the State of Georgia, utilities across the U.S. may benefit from this presentation and subsequent conversations about biosolids management challenges like increased landfill and tipping fees, organics co-processing, or land application bans due to PFAS concerns. GEFA hopes to build upon the study's findings through programs and projects that are awarded funding soon. The 2022 Call for Projects opened on September 1, 2021.

The wastewater sector's understanding and handling (i.e., treatment and disposal) of biosolids are constantly evolving, as are regulations that seek to safeguard public health and environmental wellbeing against potential risks posed by the nutrient content and other constituents found in biosolids. This abstract offers a review of recently passed biosolids laws and regulations specific to the state of Florida. Biosolids Land Application in Florida In 2018, harmful blue-green cyanobacteria blooms were observed along with the red tide along Florida's coast, resulting in detrimental environmental and economic consequences. Though the exact causes of the algal blooms are still unknown, their origin can be attributed to high nutrient loads. Since then, the state has become increasingly interested in understanding the nutrient impacts that land-applied biosolids have on the environment. To combat, prevent, and remain ahead of algal blooms, Florida's regulatory authorities developed different courses of action to control the high nutrient potential of biosolids. More specifically, FDEP created a technical advisory committee (TAC) to evaluate biosolids management while Florida's governor enacted a Blue-Green Algae Task Force within FDEP. House Bill 712, also known as the Clean Waterways Act, first began with the Blue-Green Algae Task Force; its five members met six times to review nutrient runoff into waterbodies and find alternatives and strategies to reduce nutrient pollution that exacerbates algal blooms. On October 11, 2019, they issued a list of recommendations, some of which were incorporated into House Bill 712. To summarize, House Bill 712 enacted the following biosolids regulations: - By July 1, 2022, all existing site permits for land application must meet the following requirements: - Require permittees of biosolids-land-application sites to enroll in the Department of Agriculture and Consumer Services's best management practices. - Require a minimum unsaturated depth of 2 feet between the biosolids placements depth and the water table for Class A and Class B land application. - Prohibit the application of Class A and Class B biosolids on soils that have seasonal high water tables of less than 6 inches from the soil surface or within 6 inches of the intended depth of biosolids placement, unless nutrient-management plans (NMPs) and water-quality-monitoring plans are developed to provide appropriate assurances that the application will not cause or contribute to water-quality violations. - Local governments are allowed to maintain Class A or Class B biosolids ordinances if adopted before November 1, 2019. - FDEP is required to enact rules for biosolids management once ratified by the Florida Legislature. House Bill 712 underwent the process of being incorporated into regulation as amendments to 62-640, F.A.C., which not only bolsters the Clean Waterways Act but also revises monitoring and permitting criteria for the land application and management of biosolids. FDEP introduced these amendments via a Notice of Rule Development that FDEP issued on April 14, 2020, followed by a Notice of Proposed Rule published December 3, 2020. The revised rule became effective as of June 21, 2021. According to FDEP's statement of estimated regulatory costs (SERC) published on December 3, 2020, the amendments are anticipated to increase regulatory costs in excess of $1 million in the aggregate within five years of their implementation. This cost escalation is largely attributed to the revised rule's reducing land-application rates by an estimated 75 percent & as the sites will be saturated with water &which will likely force a larger portion of Class A and B biosolids to be disposed of in landfills (i.e., increased tipping and hauling costs) or converted to Class AA biosolids (i.e., systems must undergo potentially costly conversions to produce higher-quality biosolids). Note, Class AA biosolids are Class A biosolids that meet state restrictions for certain metals. Class AA are exempt from nutrient restrictions for land application and are classified as a fertilizer. Figure 1 presents the land application sites that could be affected by this change: Many of the permitted land application sites, shown as green circles, will likely disappear in the coming years, especially near the coast, while the number of Class AA facilities, shown as orange circles will continue to grow. As stated in the Florida House of Representative's staff analysis published on March 15, 2021, the amended Chapter 62-640, F.A.C., 'will have a negative fiscal impact on local governments and the private sector who provide wastewater and biosolids treatment, as well as locally and privately owned utilities.' Case Studies: Three Florida Utilities Adapting to Regulatory Change Faced with rapidly changing and intensifying regulations that will likely demand cost-effective investments, three Florida utilities have been proactively evaluating the future of their biosolids programs. JEA, Manatee County, and the City of Cocoa collectively provide wastewater services to more than 1,300,000 people, covering over 1,200 square miles in Florida. These utilities represent different operational scales: JEA is a large utility treating approximately 80 million gallons per day (mgd) in average daily flow (ADF), while Manatee County is considered medium-sized, treating approximately 25-mgd ADF. Finally, the City of Cocoa is a small utility, handling approximately 2-mgd ADF. Between a combined total of 15 water reclamation facilities (WRFs), these entities operate various thickeners, dewatering units, digesters, and thermal dryers to produce approximately 52 dry tons of Class B and Class AA biosolids every day. Between 2020 and 2021, these utilities conducted 20-year planning studies of their biosolids programs using similar criteria (e.g., scale of operations, level of treatment, cost, sustainability, community, proven and established technologies) against which to evaluate viable management strategies. Each utility's size played a notable role in selecting process technologies and deciding the most appropriate overall strategy. For instance, the City of Cocoa's single WRF produces significantly less quantities of biosolids than JEA's 11 facilities; as such, their relatively small-scale system likely does not require sophisticated technologies suited for large-scale operations. Meanwhile, Manatee County must balance strategies meant for both small and large utilities to suit their medium-sized system. Beyond size, Florida's changing regulatory landscape is anticipated to have a considerable and overarching operational impact on all three utilities, regardless of how large or small, complex or straightforward their biosolids handling and processing are. As such, regulatory compliance was a decisive factor in selecting the most effective yet financially and operationally feasible biosolids-management strategies and process technologies. Evaluated alternatives ranged from composting and digestion to thermal and solar drying. Conclusion Biosolids regulations, and effective management efforts to comply with those regulations, will continue to evolve. In Florida, recently passed regulations will likely force utilities and entities who have historically land-applied Class A or B biosolids to seek out other management strategies and alternatives including landfill disposal or converting their systems to those that can produce Class AA biosolids. Indirectly, utilities that are already producing Class AA biosolids may face intensified competition in a changing market that must accommodate the increased availability and variety of Class AA biosolids. This presentation will provide an in-depth yet practical review of the historical context behind biosolids regulations in Florida and discusses the anticipated impacts the new regulations will have on Florida utilities' biosolids programs, including three Florida utilities of varying sizes.

Since 2001, the Metropolitan North Georgia Water Planning District (District) has focused on water supply, wastewater, and watershed planning through an integrated Water Resources Management Plan (Plan) for the 15 counties and 95 cities that make up the Metro Atlanta Region. As part of the watershed planning efforts, the District has coordinated strategies to protect watershed conditions and manage stormwater in conjunction with existing regulatory requirements. However, despite these efforts, urban stormwater runoff remains a leading cause of nonpoint source pollution and flooding in the District, leaving watershed managers with ongoing challenges related to water quality, streambank erosion, and nuisance flooding. Historically, managers have focused on strategies to address water quality rather than water quantity, even though they are fundamentally linked. For these reasons, the District has developed a novel water quantity-based indicator, called the Stormwater Forecast (Forecast), as part of the integrated 2022 Water Resources Management Plan. The Forecast is a planning-level estimate of the total potential runoff management volume from development, calculated at the basin scale using site-scale post-construction stormwater performance standards. The calculation estimates runoff volume in cubic feet for three post-construction stormwater performance standards used in the District: Water Quality Volume (1.2-inch storm event), Channel Protection Volume (1-year, 24-hour storm event) and Overbank Flood Protection Volume (25-year, 24-hour storm event). The Forecast provides a planning-level estimate of runoff volume from all historical and existing development through 2019 (using the most recent USGS land cover data) and calculates future runoff volume through 2040.With this approach, the Forecast represents total potential runoff management volume from development with the potential to be managed by Stormwater Control Measures (e.g., stormwater ponds or bioretention basins) if current post-construction stormwater management standards were fully in place. The goals of the Forecast are to provide additional information for improved decision making at both the site-scale and basin-scale, to support a better understanding of overall needs, and to help generate new solutions and policies that address ongoing stormwater management challenges. Future use of the Forecast is intended to complement and support the implementation of existing water quality and flood reduction goals in the District. This presentation will focus on the basic framework of the Stormwater Forecast as well as an overview of the technical approach and future implementation.

The Westport Regional Business League (WRBL) in conjunction with the City of Kansas City, Missouri (City) are finally addressing frequent and severe flooding within the Westport district of the Brush Creek CSO basin. This project is applying a multi-objective approach to design a more affordable and valuable solution. The overall objective was to significantly reduce flood depths at a more affordable cost within a combined sewer basin. The project team achieved this objective by first developing a detailed 2D stormwater model that accurately simulated historical flood depths and then used that model to inform the city and key stakeholders on the flood reduction benefit for a range of solutions. Overlaying the 2D model results over parcel and street information served as a clear communication tool to demonstrate the flood reduction benefit. Unlike typical stormwater designs the goal was not to eliminate flooding, but to reduce the flooding to a point that property was not damaged, and public roads could be passable. An example of the before and after model results graphics are provided as Figure 1. Westport's flooding problems have gone through numerous studies in the past. These efforts have ultimately resulted in solutions that were held to a traditional stormwater design standard that was not affordable or constructible within this highly developed and utilized area of the city. The City and WRBL are now interested in pursuing stormwater solutions that can improve their frequent flooding problems, outside of a traditional stormwater design standard. The project team approached this effort using available rainfall data for two recent rain events and targeted stormwater improvement solutions that would alleviate flooding for these historical events using a Infoworks ICM 2-Dimensional Model. This tool was developed to accurately reflect observed flooding conditions for the recent rain events to understand how much reduction in flood depth the proposed improvements could provide. While 'solving' flooding problems in Westport for all storm events is not a feasible goal, the project seeks to significantly improve the flooding conditions for the more frequent rainfall events. Reducing flood depths from over 4 feet to less than 6 inches can transform what has historically been expensive flood damage to buildings and vehicles to short-term ponding contained mostly within the street right-of-way. As part of the federal consent decree compliance for CSO control, the City implemented the Smart Sewer Program (SSP) and developed a systemwide hydrologic and hydraulic model of its sanitary and combined system. The SSP model was developed in Innovyze InfoWorks ICM Version 7.5 and is a one-dimensional (1D) model calibrated to simulate the underground combined sewer system and CSO volume. The Brush Creek basin model was used as the starting point to develop the Westport stormwater 2D flood model. The 2D model was invaluable during this project. Because 1D models are limited to showing flood depths only at modeled manholes and inlets, but cannot show how the overland flow travels above ground and the flood depths and extents. The 2D model also better simulates the duration those flood depths and extents are experienced. The 2D model provided a much better understanding of how floodwater traveled and accumulated in the problem sump areas causing flooding of cars and businesses. The model results were confirmed by personal accounts, photos, and videos of simulated historical flood events. The 2D flood model was developed using a digital elevation model (DEM) that was created from the City's latest LiDAR-derived DEM data and updated with the field topographic survey collected as part of the project. A 2D mesh zone, a series of contiguous triangles, was then created in the model. Rainfall data is then directly applied to the 2D mesh zone, and the model routes the simulated runoff to the closest inlet point or lowest depressed area based on the DEM. This more accurate approach for stormwater runoff in Westport, which has a very high amount of directly connected impervious area, proved to be critical in not only defining the flood depths but the significant surface routing through the area. Figure 2 provides an example of the surface routing in the model. The other benefit of using a highly detailed 2D surface mesh was that green infrastructure collection solutions were simulated as depressions in the 2D mesh representing proposed conditions. This approach better represented the stormwater benefit of green infrastructure intercepting surface runoff, storing stormwater runoff, and then metering the storage volume back to the pipe system. The 2D watershed model was then utilized to evaluate both green and gray stormwater improvement solutions. Gray stormwater improvement solutions included curb and grate inlets, collection piping to underground storage, and conveyance piping. Green stormwater improvement solutions included pervious pavements, bioretention, vegetated swales, and tree planters. A combination of green and gray stormwater improvement alternatives were evaluated with the 2D stormwater model for a range of rainfall events. Stormwater improvements were sized and located to align with the Westport District plan which included parking improvements, streetscape enhancements, increased pedestrian safety and connectivity while maintaining the historical significance of the area. Using this multiple objective integrated approach, the design team was able to develop a preferred improvement alternative that provided a flood reduction benefit, addressed the Westport District plan requirements, and was cost-effective. The preferred stormwater alternative is a system solution that collects, stores, and conveys stormwater at multiple locations. Two large underground storage units form the upstream and downstream control points while green infrastructure collection in the form of pervious pavements along with traditional curb inlets provide additional collection and storage. A large stormwater pipe system connects the upstream and downstream storage creating a complete system solution to maximize the stormwater function. At the very downstream point the captured stormwater must be metered back into the combined sewer system. The stormwater solutions were located in areas that also required park amenities, street improvements, and defined parking which maximized the overall restoration benefit. (See Figure 3 for graphic of proposed improvements). The preferred improvement solution is tens of millions of dollars less than previous solutions, which makes this project fundable by the city. The city plans to move this project forward to design and construction to finally solve this frequent and severe flooding in Westport. In addition, this integrated flood reduction project will have a significant impact on reducing the CSO volume discharged downstream to Brush Creek. During the design phase other project performance improvements will be evaluated including real-time controls of the storage volume, stormwater re-use opportunities, and integration of this project with another green infrastructure project downstream to increase the performance and maximize the benefit of both projects. Thinking bigger than just solving the flooding problems has resulted in a project that a broad range of stakeholders can support at a more affordable price.

Water utilities across the nation are facing the challenge of doing much more with fewer resources. Face it, our industry attempts to recover mostly fixed costs from a mostly variable revenue source, and it is becoming increasingly difficult to do so, especially when you factor in affordability concerns. This is why it is so important for utilities to examine their other sources of revenue. System development charges (SDCs), or impact fees, are a common source of non-rate revenues for funding system expansions and/or improvements required to serve new users. An SDC is a one-time charge assessed to new development to pay for the capacity in the system required to serve them. They can also be assessed to existing customers requiring an increase in capacity. AWWA's M1 Manual, Principles of Water Rates, Fees, and Charges, 7th Edition (M1), provides a high-level discussion of SDCs in Chapter VII.2. To address the increasing interest in an expanded discussion of SDCs, AWWA plans to develop a new manual focused on SDCs and with sufficient detail to be truly helpful to a utility without experience implementing or updating SDCs. SDC BASICS Specifically designed to recover an equitable share of the cost of system infrastructure from growth, SDCs provide a source of capital funding along with user rates, debt financing, and up-front reimbursements from developers. SDCs assign the capacity cost of growth to those causing the growth rather than existing ratepayers. In addition, SDCs can recover a portion of the cost of improvements to the existing system if there is existing capacity available to serve new customers. Infrastructure commonly financed with SDCs include water rights, source of supply, treatment plant facilities, pumping, and transmission lines, sometimes collectively referred to as 'backbone' facilities. Water distribution mains are typically constructed by developers and therefore not usually included. A rational nexus must exist between the SDC amount and the costs associated with serving new users, whether or not the system needs to be expanded to serve them. According to the M1 manual, there are three basic methods for calculating SDCs: (1) the buy-in method, (2) the incremental cost method, and (3) the combined approach. Depending on the utility's goals, objectives, legal constraints, and financial circumstances, one method may be more appropriate than another. KEY TOPICS TO EXPAND ON The SDC chapter in M1 addresses several key topics, including the basic approaches to calculating SDCs and methods of fairly administering SDCs to customers with varying capacity requirements, at a very high level. A manual devoted entirely to SDCs will be able to expand on these topics, as well as many others, to give readers the additional detail they need to develop fair and equitable SDCs to enhance their revenue stream. The SDC manual will include additional examples to help readers understand the calculations for all components of the SDC. The new manual will explore eligible costs related to growth or capacity-related improvements to include as part of the capital improvements plan. Such topics as raw water supply capacity costs, regional transmission costs, interest or financing costs of eligible improvements, and debt service costs related to growth/capacity infrastructure for purchased water treatment services will be explored in greater detail. One key topic that the SDC manual will expand upon is the methods of assessing SDCs to different types of customers, particularly the advantages and disadvantages of each method to help a utility determine which method is appropriate for their service area. With development trends evolving to include accessory dwelling units, mixed-use (e.g. apartments above ground-level retail shops), single-resident occupancy units, and green/low-impact development, there is growing interest in standards for assigning equivalent units to these types of properties to ensure that they pay their fair share of system costs. Another key topic to be expanded upon in the new SDC manual will be defining system capacity. Because system capacity is not available in the same proportions throughout the various functional components of the water system (source of supply, treatment, pumping, storage, etc.) care must be taken to calculate the SDC component cost by functional cost component. This allows the utility to recognize variations in system capacity, system value, and customer capacity needs by functional area. The fundamental formula for calculating an SDC is: (System Value/System Capacity) X New customer capacity demands = SDC Summing the SDC functional component costs yields the water system SDC. The new SDC manual will examine some of the ways a utility can accomplish this task. NEW TOPICS TO INCLUDE The new SDC manual will include the following topics: (1) a summary of legislation by state, which varies widely; (2) guidance for SDCs regarding potential challenges and/or litigation; (3) administrative procedures and accounting requirements for SDCs; (4) land use assumption plans; (5) utilization of potential demand (capacity-based) versus estimated/actual demand (usage-based); and (6) incorporating major changes such as SDC process changes and definitions of Equivalent Residential Units (ERUs). In addition, the new SDC manual will contain more step-by-step examples for the reader. OVERVIEW OF PRESENTATION The presentation will provide a summary of SDC basics, including uses and methodologies for calculating them, as well as explaining the drivers behind development of the new manual. The presentation will provide examples of expanded and new topics and introduce the proposed timeline for developing and publishing of the SDC manual.

Background SARS-CoV-2, the virus responsible for COVID-19, is shed in the feces of both symptomatic and asymptomatic individuals and often before the onset of symptoms. Wastewater testing for COVID-19 virus can, therefore, provide population-level information about the circulation of the virus that is not captured by clinical testing. Wastewater testing is a proactive approach to detecting the presence and prevalence of infection and developing public health strategies to mitigate spread of the virus. Missouri's Coronavirus Sewershed Surveillance Project (CSSP) is a collaborative effort to monitor community sewersheds and congregate living facilities for genetic indicators of SARS-CoV-2 in wastewater. At the start of the project in June 2020, CSSP was collecting weekly samples from 12 community wastewater treatment facilities. In subsequent months, community interest in participation in the project grew. Currently, CSSP is collecting samples from 94 community facilities and 36 state congregate facilities, representing over 70% of the state's residents. Methods In CSSP, untreated wastewater (influent) samples are collected weekly or biweekly from select sewersheds and congregate living facilities for detection and analysis of trends of 'true' prevalence of the virus. Twenty-four-hour composite samples of raw influent sewage are collected using auto-sampling devices and shipped on ice to a lab at the University of Missouri-Columbia. The wastewater samples are then filtered, concentrated using polyethylene glycol (PEG) precipitation, and RNA is extracted. Following extraction, SARS-CoV-2 levels are quantitated by qPCR using N1 and N2 primers/probes (CDC). Standard curves are included in every PCR plate so that cycle threshold (Ct) values can be converted to Copy numbers/L from wastewater. In order to account for volumetric dilution that occurs within wastewater systems (e.g. rain fall), RNA concentration (copies/L) are multiplied by facility-specific flow rates (MGD) on the day of sample collection, yielding an estimate of total copies. Samples with high and sufficient viral load are screened for variant mutations using a novel computation workflow based on amplicon sequencing of the SARS-CoV-2 spike N-terminal domain (NTD) and receptor-binding domain (RBD), allowing for detection of variants of concern (VOC) and other lineages within sewersheds. Results Using Spearman's correlation analysis, CSSP found that wastewater concentrations most strongly correlate with positive case counts 4-6 days in the future (Figure 1). In analysis of community sewershed data, the team has found that a ≥45% increase in the exponential weighted moving average (EWMA) of viral genetic fragments in wastewater is proceeded by an increase in clinical cases in the following week approximately 65% of the time. Bland-Altman plots have revealed that wastewater is indeed a reliable proxy marker of current or future clinical cases. Application of Findings CSSP publishes the community sewershed data, including viral load trends and variant mutation detections, in a storymap (https://storymaps.arcgis.com/stories/f7f5492486114da6b5d6fdc07f81aacf) posted on the Missouri Department of Health and Senior Services (MDHSS) website (Figure 3). In addition, CSSP notifies MDHSS staff, local public health agencies (LPHAs), and other stakeholders of significant increases or elevations in viral load and the presence of variant mutations in sewersheds (Figure 4). In April 2021, CSSP began using the wastewater testing results to help identify communities in need of COVID-19 testing. CSSP extends offers for MDHSS to host a free community testing event where sewershed viral load trends are significantly increasing. LPHAs have helped raise awareness of wastewater testing results and interest in testing among their community members by advertising the events, holding meetings, issuing press releases, and conducting interviews. These outreach efforts have been particularly beneficial in rural areas of the state, where vaccination rates are low, COVID-19 testing options are sometimes limited, and, in May and June 2021, mutations of the more transmissible Delta variant were first being detected in the wastewater samples. Conclusions Sewershed surveillance can be utilized to identify potentially high risk communities and assist in data-driven public health efforts/decisions. In the future, sewershed surveillance may be used to better understand the spread of other communicable diseases and possibly even opioid use.

Learning Objectives:
-Application of geoprocessing automation in hydrologic analysis
-Best practices for applying a phased approach to large-scale hydraulic modeling production

Introduction
Current effective FEMA Flood Insurance Rate Maps (FIRMs) were initially developed for Fairfax County, VA in the 1970s. FEMA is currently updating the County's Flood Insurance Rate Maps (FIRMs). FEMA typically maps floodplains of drainage areas one square mile or greater. Fairfax County, however, intends to regulate the floodplains of all stream channels within the county that have drainage areas 70 acres and greater. Atkins is currently working with Fairfax County to develop a separate regulatory floodplain layer (map) for all 70-acre streams by leveraging the terrain and cross sections from the most recent FEMA study and developing flows based on the Anderson Method, which is the Fairfax County's preferred hydrologic method. The final regulatory floodplain layer would be assembled from the more conservative (higher BFE) results between the County and FEMA. Fairfax County plans to fully remap the entire county, which includes 27 watersheds, consisting of about 800 stream miles and 1200 stream crossings.

Methodology
To comply with Fairfax County's Public Facilities Manual (PFM), floodplain studies on areas less than 200 acres are to use the Rational Method or NRCS methodology. An automated ArcGIS-based geoprocessing tool was created to calculate all necessary watershed parameters needed for hydrology calculations, including curve number, drainage area, and longest flow path. The tool requires a shapefile of desired delineation locations as well as several watershed rasters. The output will provide an updated pour point shapefile in which the attributes report drainage area, curve number, slope, longest flow path, and longest flow path elevations (Figure 1). Additionally, longest flow path and pour point watershed shapefiles are generated. Parameters are input into an automated spreadsheet to calculate the Anderson Method discharge and Rational Method discharge. Values are also input into HEC-HMS to calculate the NRCS Method discharge. Updated flows for each watershed are then imported into a HEC-RAS model to simulate the updated flooding extent. The HEC-RAS models are being developed based on Fairfax County's 2018 Lidar data and have cross-sections spaced approximately 300 feet apart. This is a large-scale project with many moving parts, including hydrology development, hydraulic model development, survey collection and implementation, and final flooding extent results for 27 watersheds. Thus, a key component is to plan in phases to handle all data and tasks. Fairfax County watersheds have been split into Phase 1 and Phase 2 and three stages to manage the time requirements for each step (Figure 2). Each phase (group of watersheds) of the work will go through the three stages: preliminary HEC-RAS model development, field surveys of hydraulic structures, and final model development and mapping. Both the hydrologic and hydraulic analyses are being performed in parallel. Production is being done by watershed basis with the hydraulics for a given basin lagging the hydraulics for that basin.

Project Status
The project team has completed the geoprocessing, hydrology calculations, and hydraulic modeling for three watersheds. Figure 3 shows the floodplains generated for one of the watersheds. Development of the preliminary HEC-RAS models for the remaining watersheds within Phase 1 is ongoing. Subsequent stages of the work will include field surveys of hydraulic structures and final HEC-RAS model development and regulatory floodplain mapping.

Conclusions
Current flood maps for Fairfax County are up to 50-years old. Increases in development density within the watershed and climate change are not incorporated in these maps. Updating these maps will allow for reliable data in future developments and improved mitigation and response options. The use of a geoprocessing tool greatly optimizes the development of updated flow data thereby aiding in the completion of this massive undertaking within budget and schedule.

The use of Green Infrastructure (GI) and its addition to stormwater regulatory requirements became widespread with the publication of the USEPA National Pollutant Discharge Elimination System requirements in 2000 (EPA, 2000). In most areas of the United States, this this was addressed with the addition of a volume management criteria to address water quality, recharge, and streambank geomorphology, while maintaining past peak flow requirements. For example, in Pennsylvania, the pre-construction water volume cannot be increased, and water quality cannot be degraded for new development for all storms up to the 2-year/24-hour event (PADEP, 2006). The peak flow restrictions for the 2-, 10-, 50- and 100-year storm remain as well (Pennsylvania Code, 2022). Most applicants have used NRCS techniques based upon the design storm approach (NRCS, 2007). While GI was embraced and brought to the design of stormwater systems, the design storm approach was not rethought. This too often results in the need for a hybrid of two separate stormwater systems - one for small, frequent storms (targeting water quality and geomorphologic concerns) and one for large, infrequent events (such as 50, 100 year storms). The use of continuous simulation was proposed by the USEPA as far back as the 1970's for water quality design (USEPA, 1979). Continuous simulation was proposed as superior to the design storm approach even for peak flow. A major challenge of the mission to use continuous simulation at that time was the lack of available rainfall and climate data with fine intervals. Design storms were intended for designs of structures whose failure would cause catastrophic consequences. The stormwater best management practice design guide from the USEPA expressed concern as to the accumulation effect of peak flows and to the extended peak flow erosion a streambanks (Clar et al., 2004). Pennsylvania and other states combine these two regulations requiring both the pre-construction volume and peak rate to be met. Unfortunately, the design storm approach for long storm events (such as 24-hour durations) artificially concentrate most rainfall volume over a small time interval which occurs at the center of the storm. The statistics used to develop design storm distributions do not separate the high-intensity, small volume thunderstorm from that of the low-intensity, long duration frontal system. Thus, the statistics that create the high-intensity center peak are more consistent with the intensity of short duration thunderstorm than that of a 24-hour rainfall event. An example, a recorded 24-hour storm event is compared the design storm of the same rainfall volume and duration (Figure 1). The graph shows a distinct difference between the design storm and the recorded rainfall event in terms of peak intensities.Vegetated GI design, that utilize infiltration and evapotranspiration, is strongly influenced by the short-duration, high-intensity peaks and as such temporary storage is needed. The additional storage is rarely used but required by the design storm approach. This prejudices the selection of GI towards lesser green solutions (such as underground detention basins), which require more space and typically more maintenance. It is hypothesized that a site tailored to the soil, vegetation, and local rainfall patterns would be more resilient, more appropriate, and more feasible especially in urban areas (Traver and Ebrahimian, 2017). Villanova University was approached by the Commonwealth of Pennsylvania to develop an update to the Stormwater management Manual, which enabled the researchers to implement what has been learned worldwide since the previous manual was published in 2006. Besides the introduction of climate change adaptations, the researchers are proposing parallel paths (continuous simulation or design storm approach) for meeting the 2-year/24-hour volume and water quality requirement as well as for peak flow (using continuous simulation/storm of record approach or design storm approach). Results from model studies used to validate these approaches will be presented. References Environmental Protection Agency (EPA). 2000. 'Proposed Reissuance of National Pollutant Discharge Elimination System (NPDES) Storm Water Multi-Sector General Permit for Industrial Activities.' Federal Register. Accessed January 17, 2023. National Resource Conservation Service (NRCS). (2007). Chapter 7 Hydrologic Soil Groups. Pennsylvania Department of Environmental Protection (PADEP). (2006). Pennsylvania Stormwater Best Management Practices Manual. Pennsylvania Code. 2022. '25 Pa. Code § 102.8. PCSM requirements.' Accessed January 17, 2023. http://www.pacodeandbulletin.gov/Display/pacode?file=/secure/pacode/data/025/chapter102/s102.8.html&d=reduce. United States Environmental Protection Agency (USEPA). 1979. '1978 Needs Survey: Continuous Stormwater Pollution Simulation System - Users Manual.' Office of Water Programs Operations. Clar, M., B. J. Barfield, and T. O'Connor. 2004. Stormwater Best Management Practices Design Guide Volume 1 - General Considerations. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/121. Traver, R. G., and Ebrahimian, A. (2017). 'Dynamic design of green stormwater infrastructure.' Frontiers of Environmental Science & Engineering, 11(4), 15. United States Environmental Protection Agency (USEPA). (2016). Summary of State Post Construction Stormwater Standards. Washington State Department of Ecology. (2012). Stormwater Management Manual for Western Washington (Publication Number 12-10-030).

Background: Wastewater surveillance is an important and emergent public health tool that relies on robust infrastructure to work well including accessible wastewater sampling points, detailed information on sewer system service areas, and trained personnel. Wastewater treatment plants are perhaps the most convenient wastewater sampling points, as they already sample wastewater as part of their environmental safety requirements. To evaluate the capability of treatment plants of different sizes and characteristics to participate in surveillance efforts, we developed and distributed a survey to New York State treatment plant supervisors in the summer and fall of 2021. The goal of the survey is to assess the knowledge, capability, and attitudes toward wastewater surveillance as a public health tool. Objectives: Our objectives are twofold. First, we want to determine what data treatment plants have about their service areas and in what form including physical maps, geospatial information systems (GIS) data, and address lists. Knowledge of the service area (sewershed) is essential for linking wastewater surveillance data back to upstream populations. The second objective is a broader questionnaire to identify the capability and limitations to conduct surveillance across treatment plants of different sizes and in different communities from urban to more rural settings. This second objective also included an evaluation of the knowledge and attitudes that treatment plant supervisors have regarding wastewater surveillance to inform what kind of education and outreach efforts public health departments may have to engage in. Methods: A population of treatment plants was identified using New York State Department of Environmental Conservation information on municipal treatment plant locations. Contact information was obtained from state and regional offices. Of the 638 treatment plants identified, contact information was available for 377 of them. The plants were contacted between July and September of 2021 by email and phone to complete a survey asking about what data they have on their treatment plant service area and what they know about wastewater surveillance. A total of 93 treatment plants participated in the survey representing a 25% response rate and accounting for nearly 15% of all the municipal plants in the state. Summaries of responses were calculated as well as statistical comparisons between plants of different sizes. Results: Data on service areas is not universal with 23% of respondents reporting no data on their service areas. Regarding knowledge of surveillance for public health, 84% of respondents know that wastewater samples can track COVID-19 but only 51% are aware that it can also be used to track opioids. In addition, 39% of respondents agree that wastewater surveillance could be beneficial with their community with most respondents (44%) indicating they are unsure or have no opinion. We find high capacity for treatment plants to collect 24-hour composite samples with 69% of all treatment plants reporting ability to take at least one sample per week. Of the responses, 90% of larger plants surveyed (> 2 mg/d of flow) indicate ability to take one sample per week or more with 55% of smaller plants (< 2mg/d of flow) indicating the same ability. For grab samples, the capability is similar with 67% of respondents indicating ability to take samples at least once per week. For larger plants, 81% of respondents indicate ability to take grab samples at least once per week while 58% of smaller plants indicate the same ability. Discussion: Results suggest diverse capabilities across sewer systems with differences between treatment plants by size. Knowledge about surveillance is also mixed with most supervisors knowing that COVID-19 can be tested in wastewater but having less knowledge about surveillance capabilities for other things like opioids. Findings provide guidance for outreach activities with results suggesting education and communication with treatment plant personnel would be beneficial to increase awareness of what surveillance can do to benefit public health. Results also provide important insight into treatment plant capabilities as they are connected to internal factors such as size, which may help public health departments understand the limitations and ability of future participation. Overall, we find that most treatment plants in New York State, regardless of size, report ability to conduct surveillance at least once per week suggesting that statewide scaleup of surveillance programs could occur with most treatment plants simply needing the knowledge and guidance on what to surveil. Next steps include evaluation for additional patterns across population levels and urban v. rural dynamics to better aid health departments in targeting resources for training, education, and equipment.

Background: Bioinformatic analysis of whole genome sequencing data has played a central role in surveillance throughout the SARS-CoV-2 pandemic by allowing scientists to identify novel variants and to track the proportions of variants across time and geographic location. Because SARS-CoV-2 is shed in fecal material that ends up in wastewater, whole genome sequencing of SARS-CoV-2 from wastewater samples can be an effective method for the surveillance of the virus. Methods: Here, we describe Colorado's wastewater whole genome sequencing and surveillance strategy for SARS-CoV-2. We have been collecting twice weekly samples from March of 2021 to present from 20 wastewater utility sites. After extraction of RNA from wastewater, we perform tiled PCR-amplicon whole genome sequencing for SARS-CoV-2. We also present the bioinformatics workflow that we developed for analyzing whole genome sequencing data from wastewater samples, which determines the variants likely present in a sample based on sets of mutations associated with variants of concern or interest. Variant-associated mutations are determined using the Spike mutations present in known variants of concern (VOC) or variants of interest (VOI) as defined in the outbreak.info database (https://outbreak.info/situation-reports) and are updated regularly. Briefly, this workflow performs quality control and filtering of raw reads, aligns reads to the reference genome, calls single nucleotide polymorphisms (SNPs) using FreeBayes and filters SNPs based on quality. We then use custom scripts to identify the presence and frequency of mutations associated with known VOCs and VOIs and to generate summary files for further analysis and visualization. We have made this workflow a publicly available resource for use on Google Cloud's Terra platform. Results: Using this surveillance and analysis strategy we have been able to determine which SARS-CoV-2 variants are likely present in wastewater samples based on the constellations of VOC/VOI-associated mutations that are present. For example, we observed the rapid transition from Alpha to Delta as the dominant variant circulating in Colorado (Fig. 1A). Furthermore, we can see the emergence of VOCs in CO prior to their emergence in clinical samples sequenced by either the state public health department or a commercial laboratory and reported to the state public health department. As shown in Fig. 1B, in most of the counties for which we have sampling, we identified the mutations associated with the Delta variant in wastewater prior to it being identified in clinical samples. These results also show geographic differences in which variants are present, when they are first detected in wastewater, and when they are first detected in clinical samples. Conclusions: These results demonstrate that SARS-CoV-2 wastewater sequencing can be used to monitor SARS-CoV-2 trends over geographic location and over time. Our ability to detect VOC/VOI-associated mutations prior to the detection of the viral lineages with which they are associated in clinical samples suggests that wastewater whole genome sequencing can be used as an early warning signal. More broadly, these results can inform public health strategies and can be applied to other pathogens of current or future public health concern.