Conference Papers

APPLICABILITY The objective of this work is to develop an anomaly detection approach for biogas blowers using nonintrusive vibration sensors for machine conditions and health management. High-frequency vibration signals are collected from a tri-axial accelerometer installed on the exterior of the biogas blower casing. Long short-term memory (LSTM) artificial neural network algorithm is applied for signal classification. The proposed condition-based monitoring approach could provide a low-cost non-intrusive solution for asset management of compressors at water resource recovery facilities. INTRODUCTION Predictive maintenance (PdM) organizes maintenance activities according to the actual health state of machine tools, equipment, and systems [1]. Diagnostic PdM detect detects faults, determines root causes of operation anomalies, and estimates the current health state of a system under investigation to prevent unexpected failures. Condition-based monitoring is an approach for realizing diagnostic PdM as standardized by ISO 17359:2018. Condition-based monitoring can provide significant advantages in relation to product quality, safety, availability, and cost reduction in industrial applications. The recent advent of information and communication technologies and artificial intelligence presents a great opportunity to enhance the practice of data-driven assessment of the operation and maintenance of wastewater infrastructure [2, 3]. The objective of this study is to develop an anomaly detection approach for biogas compressors through vibration analysis for predictive maintenance. To achieve this goal, piezoelectric sensors and edge computing platforms (Raspberry Pi and Arduino board) are deployed on the biogas compressors. Machine learning algorithms are applied for classifying the collected vibration data for anomaly pattern recognition. METHODS The vibration monitoring in this study is implemented for compressor Unit 1 (KAESER) and compressor Unit 2 (SIEMENS) in a biogas facility. A low-power tri-axial accelerometer (model# ADXL345, Analog Devices, Wilmington, MA) is used with serial data communication devices such as Raspberry Pi and Arduino boards to collect vibration data from compressors. The data collection was initiated from the point of time when the compressor operated in normal condition and continued to the occurrence of any failures. The sampling frequency of the accelerometer is 1k Hz for each axis with a measurement interval of 30 minutes. Data are measured and obtained via Inter-Integrated-Circuit (I2C) bus. During the measurement, the sensor collects 10000 data points for each axis, which would take approximately 10 seconds, and is set to idle until the next measurement. The structure of the implemented condition-based monitoring is shown in Figure 1. The raw data includes the time stamp and acceleration data for the x, y, z-axis, and the sampled time for the corresponding sample. Sample x-axis vibration signals are visualized in Figure 2. The machine diagnosis is realized by scoring the anomaly levels of the vibration data, which will increase as failure approaches. Hence, an anomaly scoring model is tested to characterize the different levels of anomalies and provide an informative interpretation of forthcoming failures. The implemented model is inspired by dilated RNN network and Temporal Hierarchical One Class (THOC) network, which contributed to solving complex dependencies and vanishing gradients problems in layers. The THOC network is adopted and modified to develop the anomaly scoring model. The model consists of 3 long-short term memory (LSTM) layers with dilated skip connections. Details of the method implementation could be found elsewhere [6]. The sequential length of the transformed data is 36, and the input batch size is set to 128. In Fig. 3, each node represents a hidden RNN cell. The number of input nodes highlighted as green is determined by the sequential length of input data, which is 36. Similarity score obtained from the score function is translated to loss using the following equation that will be optimized through a training process. Adaptive Moment Estimation (Adam) optimizer is employed as it is known to have good capabilities of reaching global minimum with a high dimensional dataset. The structure of the implemented condition-based monitoring is shown in Figure 1. RESULTS The results of the model are shown in Figure 3. The input data (time-frequency domain) is visualized using power spectrum analysis. It is important to be noted that the Euclidean distance returns the length of a line segment between two vectors. Thus, the test data with a larger distance from the centers in each layer are expected to be assigned higher anomaly scores. As shown in Figure 3, anomaly points are captured when the power spectrum has abnormal patterns or when a peak value pops out from the power spectrum. Also, data points with small anomaly scores are not identified as anomalies, which might be sound as not all anomalies cause machine failures. Thus, a threshold should be carefully determined as it plays a critical role in linking such anomaly information with maintenance strategies. In this study, the threshold value is selected based on the 99.9 percentile in the anomaly scores. Different threshold values are used with an optimal threshold that prevents generating excessive false positives. The results may need to be compared to the actual machine condition such as whether abnormal operations were present while it was monitored. Since Euclidean distance may not be intuitive on a high dimensional dataset, different scoring functions are also tested for comparison. Chebyshev scoring function is adopted and the result is visualized in Figure 4. Chebyshev distance provides the greatest differences between two different vectors along any coordinate dimension. Hence, input data with the highest variance and difference are likely to obtain higher anomaly scores. As shown in Figure 4, the power spectrum with peak values tends to be identified as anomalies. In this case, the warning stage depicted with the orange line was applied with an additional threshold (99 percentile) to demonstrate a warning system that may be applicable to the data-driven maintenance strategy. In this study, the anomaly scoring model has been utilized to detect the abnormal vibration patterns and interpret them into anomaly scores. Based on the results from the proposed anomaly scoring model, a notification strategy can be established for further maintenance scheduling. The operation and maintenance manual or guidelines are provided by manufacturers of the machines. An example of the operation and maintenance manual of a compressor is shown in Table 1. Proper maintenance requires timely tracking of operation hours followed by appropriate actions such as checking oil levels, changing filters, and grease bearings. CONCLUSIONS AND RELEVANCE This study presents a condition-based monitoring approach for biogas compressors as an example of data-driven asset assessment. The test anomaly scores were calculated based on a similarity between unseen data and clusters that are learnable by machine learning algorithms. The study shows that condition-based monitoring using nonintrusive vibration sensors could be a useful asset management tool and providing early failing alarms of equipment embedded in WRRFs. The result of this study suggests that the operator's supervisory control and condition-based monitoring could be integrated for asset management (Figure 5). A combination of preventative maintenance following manufacturer's O&M manual and predictive maintenance guided by condition-based monitoring could lead to adaptive asset management program. Meanwhile, deploying condition-based monitoring solution at WRRFs may add additional responsibilities to the maintenance crew at WRRFs. Future studies are required to understand the operator demand, capital investment, and cybersecurity implications of condition-based monitoring for WRRFs. Attendance at this presentation will benefit operators and design engineers who are interested in data-driven asset management through condition based-monitoring. This study presented a novel application of deploying nonintrusive vibration sensors and edge computing for anomaly detection of biogas compressors. The method developed in this study could be applied in asset monitoring of other rotary equipment in WRRFs.

Introduction
Our urban centers are plagued by a variety of concrete storm water conveyance structures. Originally intended for flood control, they have simply moved the flooding to downstream areas while degrading natural stream habitat. It's well documented that nature-based solutions mitigate stream habitat degradation, but can they also perform a vital flood risk reduction purpose in our urbanized neighborhoods?

General Project Information
As part of a larger master plan for the Springfield Art Museum, Fassnight Creek was restored to a naturalized channel for flood mitigation, water quality, and wildlife habitat improvement. The Springfield Art Museum is located in the heart of Springfield, just south of Missouri State University. Adjacent to the museum is the historic Phelps Grove Park which is beloved by the community for its mature trees and pedestrian trails. The museum and Phelps Grove Park are surrounded by well-established residential neighborhoods and a high-level of pedestrian activity, which made this project an impactful addition to the urban greenspaces in the area. Before the capital improvement project, Fassnight Creek was confined in a narrow concrete channel with insufficient hydraulic conveyance. The Fassnight Creek Improvements widened the channel cross section significantly and naturalized approximately 1,000 linear feet of creek channel, encompassing 1.5 acres of newly re-stablished riparian area, that serves as an urban wildlife corridor and extension of the Phelps Grove Park greenspace. The restored channel contributes to the overall quality of place and helps to further integrate Phelps Grove and the Art Museum grounds. Key components of the natural channel design include use of void-filled native rock materials to emulate the natural stream bottom of local streams and extensive native plants. Construction included excavation of approximately 16,000 CY of soils, removal of 900 feet of concrete channel lining, removal of a public street crossing, installation of over 250 linear feet of 21-inch sanitary sewer main, two new pedestrian bridges, creating a natural pool and riffle stream, mitigating culvert erosion and re-alignment and narrowing of Brookside Drive centerline to give additional area for channel improvements. Channel Naturalization Details Native plantings provide multiple benefits including creation of habitat to support pollinators, aquatic species, and other wildlife. The native landscaping included planting of over 25 native trees and over 200 native shrubs. Missouri native plantings obtained from regional sources. In addition, City urban forestry crews carefully excavated and rehabilitated a small sycamore tree known to the local residents as the 'child sycamore' and this tree was successfully re-planted in the center of the creek corridor after the grading was completed. The plantings are integral to the project's goals to improve water quality and reduce flooding through filtration and uptake of common pollutants and absorption of stormwater runoff. The project also will increase awareness and acceptance of native plants due to its visibility by local and regional Art Museum visitors. The project will also enhance the Art Museum as a local field trip destination for Science, Technology, Art & Math (STEAM) programs. The Art Museum currently partners with the non-profit Watershed Committee of the Ozarks on the Placeworks STEAM Residency that uses journaling to connect science and art and includes field trips to the Art Museum. There is also a desire for the Art Museum to serve as a monarch way station to tie in with butterfly habitat efforts at the Botanical Center on the south side of Springfield. On this project, the channel slope and shear stress exceed a fine grain channel bottom or a fully vegetated solution which is likely why a concrete liner was used in the past. Fortunately, many local streams are predominately bedrock influenced gravel bed streams. We were able to mimic the natural stream bottom utilizing void-filled rock. Void-filled rock mimics local natural stream bottom where native graded cobbles, boulders, and small aggregates are mixed form a densely packed heterogeneous mixture. For the Fassnight Creek restoration project, the concrete was removed and the rock mixture used to create a stable natural channel bottom. The engineered mixture of stones and smaller sized river gravel aggregates compacted in layers ranging from approximately 2 to 4 feet thick. Selected areas of the void-filled riprap are planted with native grass plugs to add aquatic habitat value but also reinforce overbank areas of the channel with rooted plantings. Void-filled stone structures have been placed along the channel alignment to form riffles and pools seen natural streams alignments. These pools and riffles are the foundations for aquatic habitat in the creek.

Floodplain Information
A central project objective was to reduce base flood elevation (BFE) and mitigate flood risk for the Springfield Art Museum and surrounding residential properties in this area. Based on revised, preliminary 2019 FEMA maps, portions of the Springfield Art Museum and surrounding residential properties are within the 1% and 0.2% SFHA. Flood Insurance Rate Maps (FIRMs) and Flood Insurance Study (FIS) for Springfield are currently being updated to provide more accurate depiction of flood risk for the community but have not yet been formally adopted at this time. The City of Springfield's proactive approach now has the Art Museum and residential properties well positioned for the formal adoption of the revised preliminary FEMA floodplain maps. The improvements lowered the 1% BFE approximately feet. Following the Improvements to Fassnight Creek at the Springfield Art Museum, the surrounded properties finished floor elevations have a much lower flood inundation residual risk. Construction and Funding Fassnight Creek at the Springfield Art Museum was substantially completed May 31, 2022. The construction began in Spring 2021 and took slightly longer than 1 year to complete. Construction involved complicated sanitary by-pass pump around for sanitary sewer main relocations, and constant vigilance on the part of the general contractor to maintain erosion and sediment control best management practices during active construction within the creek. Following construction, the ribbon cutting grand opening occurred October 15, 2022 with the Mayor, City Administrator, three Councilmen, the Art Museum director and the Art Museum board of directors presiding. Fassnight was recently recognized as an APWA Missouri Chapter Public Works Project of the Year because it demonstrated a functional solution to flood risk reduction which can serve many other beneficial purposes for the community. The naturalized channel is the new grand entrance to the Museum, an inspirational functional piece of living art. The overall construction costs for the project were approximately $2.3 Million. The Project was partially funded by grant funding from the Missouri Department of Natural Resources, EPA Section 319 grant funding Administered by the non-profit James River Basin Partnership, and grant funding for native plantings from the Missouri Department of Conservation. The local funding share was provided by the City's ¼ cent capital improvement sales tax.

INTRODUCTION The Metropolitan St. Louis Sewer District (MSD) is undertaking a long-term program called 'MSD Project Clear' to improve water quality for the St. Louis region by reducing the occurrence of basement backups and overflows caused by excessive wet weather sanitary and combined sewage flows. One of the approaches MSD is taking to meet this goal is constructing new infrastructure to increase the capacity of their existing sewer collection system, including new relief sewers, wet weather storage facilities, and tunnels to store and transport wet weather sanitary and combined sewer flows. This presentation will describe how wet weather storage technology was applied to attenuate excess flows and eliminate wet weather sanitary sewer overflows (SSOs) and backups in a portion of MSD's collection system. This approach has been used elsewhere in MSD's system and has potential application to other similar wastewater systems through the United States. PROJECT BACKGROUND In 2014, MSD, in association with engineering consultants Burns & McDonnell Engineering Company, Inc. and Wade Trim, Inc. began planning the Gravois Trunk Sanitary Storage Facility in Crestwood, Missouri. This facility is located along the 54-inch diameter Gravois Trunk Sewer, within the Gravois Creek watershed and the sanitary sewer service area of MSD's Lemay Wastewater Treatment Facility. Multiple sites were reviewed for location of the storage tank(s) based on a series of criteria, including operational flexibility, land needed and availability, location within the watershed and ability to meet hydraulic and flow reduction requirements, maintainability, reliability, operability, constructability, and environmental considerations. All sites evaluated were required to accommodate the preliminary storage requirement of 9.25 million gallons (MG). The site of an existing City of Crestwood public works maintenance facility was selected, which is located on Pardee Lane adjacent to the Gravois Trunk Sewer and Gravois Creek. HYDRAULIC MODELING Hydraulic modeling evaluations were performed to assess the capability of the facility to achieve two (2) goals: 1) the removal of two (2) Constructed Sanitary Sewer Overflow (SSO) Outfalls; and 2) limiting the hydraulic grade line (HGL) within the Gravois Trunk Sewer to a minimum of 8 feet below grade for a 10-year return period, except in areas where the sewer is less than 8 feet deep or in areas where basements will not be impacted. Meeting these goals will provide a 10-year Level of Service (LOS) for the Gravois Trunk Sewer. A calibrated XPSWMM model of the Gravois Creek watershed was used to verify that the required 10-year LOS is being provided for three different conditions, including for the 10-year 24-hour synoptic and 10-year 3-hour cloudburst design storms, as well as for a continuous simulation using 64 years of historical rainfall data to evaluate the long-term performance using real rainfall events. The 3-hour cloudburst event represents a high-intensity lower volume rainfall event, in comparison to the lower intensity, higher volume 24-hour synoptic rainfall event. The required storage volume to provide the 10-year LOS was determined using two methods: 1) Log Person method to determine probability of recurrence of exceeding required volume, and 2) meeting HGL limitation criteria for the downstream trunk sewer. The model was also run for the full rainfall data for the years 2000 and 2008 ('Typical' and 'Wettest' years, respectively) to evaluate the expected frequency that the storage facility would be in operation. Final design sizing concluded that the following minimum storage volumes would be required to provide a 10-year LOS: Synoptic: 7.97-MG; Cloudburst: 4-MG, and Continuous Simulations: 7.85-MG. Based on these results, a total storage volume of 8.0-MG was used for design. Modeling efforts also included development of a HEC RAS model to evaluate hydraulic conditions in the sewer downstream of the diversion structure for the purpose of optimally locating level measurement instrumentation to be used in process control of the facility. DESIGN CONFIGURATION Due to the site configuration, two (2) sanitary storage tanks with a storage volume of 4.0-MG each were planned rather than a single 8-0-MG storage tank. Above-ground storage tanks were designed using the AWWA D-110 Type III standard for Wire- and Strand-Wound, Circular, Prestressed Concrete Water Tanks. Tanks are 150-feet in interior diameter, with a maximum height above ground of 45-feet, in compliance with local ordinance. Tank floors are sloped to the center at a depth of approximately 8 feet below grade, and drained by gravity back to the trunk sewer. An aesthetics committee comprised of representatives of MSD, the design team, and public stakeholders was convened during design for the purpose of soliciting feedback on such features as tank façade, landscaping, and fencing. Other facility features included: - Non-staffed and fully automated - Diversion structure - Consolidation sewers - 54-MGD influent submersible pumping station - Granular activated carbon odor control system - Vertical turbine pumping system and rainwater harvesting system - Tank and wet well cleaning systems - Gravity dewatering sewers and control valves - Site paving, lighting, and landscaping including stormwater BMPs - Instrumentation and controls - SCADA system for centralized remote control - Control Building - Electrical Primary and Secondary Power - Miscellaneous Improvements POST-DESIGN ASSESSMENT Design was completed in 2018, and a construction contract in the amount of approximately $24 Million was awarded, after competitive bidding with four responsive bids received, to Plocher Construction Co. Inc. of Highland, Illinois. Construction began in 2019 and was completed in 2021. The Gravois Trunk Sanitary Storage Facility has been in successful operation by MSD since January 2021. CONCLUSIONS - AWWA D-110 tanks provide cost-effective above-ground storage - Above-ground wet weather sanitary storage requires extensive public outreach - Hydraulic analysis needs to consider future pipe lining, as well as potential for rapidly varied flow and/or backwater conditions in locations used for flow or level measurement - Need to build flexibility and operational feedback into facility design and process flow control strategies Refer to Picture 1 below for an aerial photo taken of the completed facility.

The Allegheny County Sanitary Authority (ALCOSAN) serves an area that spans approximately 310 square miles across 83 municipalities, including the City of Pittsburgh, Pennsylvania. ALCOSAN recently adopted a Clean Water Plan (CWP) to improve and protect the water quality of the region's streams and rivers by controlling combined sewer overflows (CSOs) and eliminating sanitary sewer overflows (SSOs). The CWP is part of a Federal Consent Decree (CD) to comply with the United States Environmental Protection Agency's CSO Control Policy. The CWP is made up of several components including preventing excess water from entering the sewer systems. As part of its green stormwater infrastructure (GSI) and source control (SC) program, ALCOSAN released Controlling the Source that lays out a consistent framework for evaluating GSI/SC in the Pittsburgh region. A key component involves identifying cost€effective and impactful GSI/SC projects capable of reducing sewer overflows to improve water quality. Overflow reduction efficiencies (OREs) were developed throughout the service area using automated modeling techniques to represent different GSI/SC techniques, varying implementation levels, and different system conditions. OREs provide a hydraulically-informed estimate of the relative overflow impacts of projects in different areas, so that effort and attention can be focused in those areas with the greatest potential overflow benefits. To complement the OREs, a GIS-based constraints analysis was performed to provide a geospatially-informed estimate of areas where GSI potential may be limited and/or costlier based on mapped physical and environmental constraints. Individual constraints such as shallow bedrock and slopes were assigned a range of constraint scores based the relative impact to GSI and then overlaid and summed. By targeting areas/sites with high OREs and lower levels of constraints, practitioners have powerful planning-level tools to identify projects most likely to be feasible, cost-effective, and impactful. Using these tools, ALCOSAN identified and evaluated almost 200 potential GSI opportunities. The opportunities were ranked and prioritized based on capture potential and implementation feasibility. Detailed concept plans for 60 of the higher ranked sites were developed and incorporated in discussions with municipalities as a tool to incentivize GSI project implementation in response to public comments received during the development of the CWP. This presentation will describe the development and application of the ORE modeling and the constraint scores as well as the results of the opportunity analysis and will discuss lessons learned for applicability in helping to address wet weather issues in other communities.

This abstract summarizes recent design and construction efforts undertaken by the Great Lakes Water Authority (GLWA) to repair and increase the level of service of the 90- to 100-year-old brick and concrete Detroit River Interceptor Sewer (DRI) in the City of Detroit, Michigan. The sewer is 8 to 16-feet in diameter, approximately 65,000 linear feet long, and serves as one of GLWA's primary interceptors. The work involved a full engineering inspection, including portions that had not been inspected since their construction in the 1930s. Because of the lack of redundancy in the system as well as high flows and lack of flow controls, a major challenge was gaining access for the inspection and repairs. Ultimately, the design-build team selected by GLWA devised a unique flow control system involving in-system storage and diversion structures, that are allowing for detailed inspection and controlled repairs of the system. This paper will describe development of the flow control system, together with the construction that was substantially completed in August 2021. Background As large sewers in major cities across the country begin to exceed their design lives, the need for creative flow control facilities will only increase as these aging assets require repair. These permanent facilities provide long term benefits over the use of temporary bypass pumping that is expensive and require large set up and piping areas. The DRI is one of the major interceptor sewers in the GLWA sewage conveyance system, serving hundreds of thousands of residents and businesses in the northeast Detroit area and suberbs. Between 2012 and 2016, an inspection was completed of the DRI that revealed significant distress in some sections. The main challenge in conducting the rehabilitation of the DRI was the lack of flow control facilities to reduce/eliminate flow within the tunnel to allow for manned entry to conduct the repairs. The upstream reaches of the tunnel could be accessed after draining these sections via a series of pump station shutdowns that gave crews a relatively normal working day during dry weather conditions. However, the downstream three quarters of the DRI did not benefit from this approach enough to allow for manned entry, and certainly not for conducting repairs. In order to accomplish flow control, the winning design build team of Jay Dee Contractors (Jay Dee), design engineer FK Engineering Associates (FKE), and specialized subconsultant's Applied Science (ASI) and Anderson, Eckstein and Westrick (AEW) proposed the construction of two flow control gate shafts, a diversion chamber with a connecting tunnel to the North Interceptor East Arm (NIEA), and two diversion drop shafts on the Morrell Sewer and Livernois Relief Sewer. These facilities, along with temporary pumping at the WRRF Pump Station No. 1 (PS-1) allow for wastewater levels low enough for manned entry and repairs within the entire DRI during dry weather conditions. Flow Controls Development and Design Hydraulic analysis was performed using existing flow meter data, the GDRSS model, and previous studies. The detailed flow control study involved inspecting existing regulators, determining bypass pumping arrangements at pump stations, investigating diversion locations, making flow measurements on numerous trunk sewers and the DRI, confirmation of the storage times with updated flow rate information, and determining the procedures for gradually releasing the stored wastewater. On this basis, a flow control system was devised consisting of two in-system flow control gates, a 1000-foot ling 9'-2' tunnel diverting flow to the adjacent NIEA Interceptor, and four flow diversion structures. A detailed operation protocol was also developed to allow for safe operation of the system, while maintaining sewer service to all upstream customers. Following the hydraulic analysis of the in-system storage gates, flow diversion structures, and the NIEA diversion Tunnel; there were a number of challenges in design of these structures. Each of these structures was located in heavily urban areas, with a myriad of utilities, and critical infrastructure that needed to be protected. Design of each structure had to consider relocation of existing sewers as large as 60 inch diameter, high pressure gas mains, water transmission mains as large as 42 inch, and various other utilities. An addition, geotechnical conditions that involved miscellaneous urban fill required special provisions to safely construct the new underground facilities. And in all cases, structures and utilities immediately adjacent to the new structures and tunnel were protected through incorporation of a robust geotechnical instrumentation program. Construction The in-system storage gate shafts were constructed first, each consisting of a temporary earth retention structure (TERS) that encompassed the existing tunnel, each about 15-feet in diameter and up to about 30 feet deep. Within each shaft, the existing DRI was exposed to below springline and the top half of the tunnel was removed via wire saw. Permanent reinforced concrete gate shafts were constructed on top of the existing tunnels, bearing on the tunnel at springline. Stainless steel gates and rolled angle gate guides were installed to hold flow within the existing tunnel upstream of the gate, allowing for approximately 8 to 12 hours of storage time and man access downstream. Following completion of the flow control shafts, work began on the DRI diversion chamber and crossover tunnel to the NIEA, see Figure 2 below. The diversion chamber consists of a similar set up to the flow control shafts, however, it included the 9-feet 2-inch diameter crossover tunnel that allows for all upstream flow to be diverted to the parallel NIEA tunnel. The tunnel was mined with an open face tunnel boring machine utilizing a rib and lagging primary liner and a glass fiber reinforced polymer mortar pipe (GFRPMP) finished liner to reduce corrosion impacts. Construction of two drop shaft diversions were constructed on the Morrell Sewer (see Figure 3 below) and Livernois Relief Sewer, both tributary to the DRI, to divert flow to the NIEA downstream of the crossover tunnel, thereby reducing flow into the downstream DRI. The drop shafts consisted of TERS constructed over the existing NIEA tunnel to allow for the construction of finished concrete gate structures and hand mined lateral tunnel connections to the existing sewers. With the completion of the described flow control facilities, flow depths and velocities can now be controlled within the entire DRI during dry weather allowing for manned entry inspection and tunnel repairs, which are ongoing.

Since 1998, Seattle Public Utilities (SPU) has innovated with retrofits of public right-of-way to improve stormwater using natural drainage systems (NDS). Based on lessons learned from prior projects and to address regulatory commitments, SPU launched the NDS Partnering program in 2017 to develop retrofits in the three major creek watersheds within the City: Longfellow Creek, Thornton Creek and Piper's Creek, see Figure 1. Due to topography, historical development patterns and standards and economic considerations much of this part of the city consists of informally developed right-of-way without curb or formal drainage infrastructure. This presentation will share the program goals, a summary of the site selection process and more importantly lessons learned in addressing the challenges and opportunities of partnering to retrofit underdeveloped urban right-of-way. The Plan to Protect Seattle's Waterways is a comprehensive strategy that embodies SPU's commitments that were documented in the July 2013 Consent Decree to address combined sewer overflows. It meets Seattle's federal commitments to create a Long-Term Control Plan (LTCP) that will make water quality improvements to Seattle's receiving waters, e.g., Puget Sound, Lake Washington, and the urban creeks that feed them. The final Plan received final approval in August 2015. Within the Plan to Protect Seattle's Waterways, SPU recommended the Integrated Plan (IP) alternative, which addresses water pollution from both combined sewer overflows and stormwater-only runoff into waterways. As part of the IP, SPU is committed to deliver high-value stormwater-only projects/programs ahead of a set of smaller-volume combined sewer overflow (CSO) projects for a greater overall water quality benefit. NDS Partnering is one of the three stormwater-only projects/programs recommended in the IP for pollutant reductions. In addition, the NDS Partnering program fits within SPU's Strategic Business Plan Focus Area No. 1, 'Better Protecting Your Health and Environment.' The mission of the NDS Partnering Program is to achieve the water quality goals identified in the City's Plan to Protect Seattle's Waterways. The NDS Partnering program emphasizes working with sister agencies, concurrent SPU programs and community partners to deliver high-value neighborhood improvements, including bioretention systems that will capture and treat stormwater before it drains to creeks feeding Puget Sound and Lake Washington. The purpose of the partnering in the NDS program is to develop shared projects within Seattle Public Utilities (SPU) programs and between SPU and other City agencies, such as Seattle Department of Transportation (SDOT), to offer multiple benefits to neighborhoods and ecosystems, including: greener, more attractive neighborhoods, lower risk of flooding, additional natural habitat for native plants and animal species, healthier creek ecosystems, calmer traffic patterns, and more street trees. For SPU, the NDS projects provide water quality treatment for street runoff that drains to urban creeks by retrofitting the roadsides with NDS (also referred to as bioretention cells) and addressing localized flooding issues. The City of Seattle has a long history in developing retrofits of right-of-way in urban creek basins beginning with the SEA Streets project in 1998. This presentation will focus on the current NDS program consisting of the Longfellow Creek Basin (due to be complete with construction in 2023), South Thornton Basin (due to begin construction in Spring 2023) and North Thornton and Pipers Creek Basins (under development and design). This program leverages innovations developed under some of the most recently constructed retrofit projects including the Delridge, Ballard (Phases 1 and 2) and Venema NDS projects to enhance the viability of green infrastructure in challenging site constraints and soils. These innovations include the use of weirs, underdrains, structural soil cells and underground injection control (UIC) wells. Working in underdeveloped or informally-drained right-of-way presents opportunities to address infrastructure gaps that will benefit the local community, specifically providing traffic calming, improving pedestrian access, and correcting nuisance drainage. This presentation will share the approach and response to community outreach to communicate impacts and receive feedback on tradeoffs on design of improvements. Additionally, the co-location of improvements with partner agencies presents opportunities to reduce overall project cost for the City balanced with increased coordination needs. Key issues addressed by the project include how to negotiate space constraints to co-locate new sidewalks with bioretention facilities in existing right-of-way. Another key issue commonly expressed by the community is minimizing impacts to automobile access and parking where historical use is informal and haphazard and existing driveways do not conform to code. Public investment in infrastructure presents the opportunity to improve community spaces and services. In addition to considering equity and deep connection with the community through the design process, the program also has had opportunities to incorporate art and create community spaces. This presentation will include examples where the projects have included a range of scale of art from small touches to enhance the individual elements of the green infrastructure to more significant efforts to incorporate public art in new pocket community spaces that are co-located and funded with the NDS projects. The project also specifically targets addressing local drainage issues where informal drainage is inadequate to collect and convey runoff from the neighborhood streets creating nuisance flooding. While addressing these local drainage issues is a significant benefit for the neighboring property owners, SPU was also challenged to incorporate NDS and drainage improvements in a manner to avoid conveying the additional runoff to create or aggravate existing issues downstream. The program addressed these challenges by evaluating the downstream system capacity, maximizing stormwater retention within the project and providing compensatory storage where required to minimized downstream impacts. In summary, this presentation will provide the opportunity to share lessons learned at a unique point in time that represents past, present and future of a program that is delivering green infrastructure improvements to over 60 blocks of neighborhood streets in the City of Seattle's urban creek watersheds. This program and presentation deliver unique and innovative techniques to balance the needs of the right-of-way to improve the quality of stormwater runoff. SPU strives for continual program improvement and delivering community-centered projects that achieve improved service with reduced costs.

SUMMARY The cost and complexity of projects implementing thermal hydrolysis pretreatment (THP) at municipal water resource recovery facilities (WRRFs) has led many utilities to utilize alternative delivery approaches. Raleigh Water selected Construction Manager At Risk (CMAR) to deliver its Bioenergy Recovery Project at the Neuse River Resource Recover Facility (NRRRF). WSSC Water utilized Progressive Design Build (PDB) to deliver the Bio-Energy Project at the Piscataway WRRF. The benefits of THP-enhanced digestion are many, from increased volatile solids reduction and biogas production to higher digester loading and therefore less required digestion volume. Some of the considerations involved with implementing THP include sludge preconditioning and treatment of high-strength post-digestion recycle streams. The cost and constructability feedback made possible with alternative delivery helped the design teams for the Raleigh Water and WSSC Water projects identify the optimal solution for each project, with a collaborative approach to the site-specific benefits and challenges associated with THP implementation. This 'case study' provides a summary of these two projects from design, through construction, and commissioning. It will focus on the unique aspects of each project, highlighting the role that alternative delivery played in influencing the design and start-up of these projects. BACKGROUND & Raleigh Water's Bioenergy Recovery Project Raleigh Water is implementing a Bioenergy Recovery Project to produce green energy and a Class A biosolids product, demonstrating the City of Raleigh's commitment to sustainable local government operations. By transitioning to THP and anaerobic digestion, Raleigh Water can convert the methane generated in the process to renewable natural gas (RNG) to fuel the City's bus fleet. Using RNG for vehicle fuel will offset greenhouse gas (GHG) emissions, supporting the City's aggressive community-wide goal of an 80-percent reduction in GHG emissions by 2050. The Bioenergy Recovery Project will be net energy producing, qualifying Raleigh Water for a $50M zero percent interest loan under the Clean Water State Revolving Fund (CWSRF) Green Project Reserve. The project was recognized nationally as Exceptional under CWSRF's Performance and Innovation in the SRF Creating Environmental Success (PISCES) program. Raleigh Water manages residuals from all three of its wastewater treatment plants at the Neuse River Resource Recovery Facility (NRRRF), the largest permitted treatment works in North Carolina with a rated capacity of 75 mgd. Current biosolids management includes lime stabilization, aerobic digestion, and off-site composting. As the existing solids handling equipment neared the end of its useful life, the utility was motivated to explore alternative biosolids management strategies, specifically those that maximize the potential for resource recovery and minimize GHG production. The Bioenergy Recovery Project will use THP to maximize the efficiency of new anaerobic digesters, achieving a nearly 50-percent reduction in mass and generating enough RNG to fuel 50 City buses. €ƒ BACKGROUND & WSSC Water's Bio-Energy Project The WSSC Bio-Energy project centralizes biosolids processing from WSSC Water's five WRRFs at the 30 mgd Piscataway WRRF to produce a Class A biosolids product. In addition to the THP and anaerobic digestion processes, the overall project also includes cake receiving, solids screening, pre-dewatering, cake pumping, pre-THP cake storage, post-dewatering, cake conveyance, Class A cake storage, sidestream nitrogen removal, odor control, renewable natural gas production, gas storage, combined heat and power generation and steam boilers. The Bio-Energy project will fundamentally change how WSSC produces biosolids, allowing a focus on long-term sustainable end products with a Class A dewatered cake biosolids and renewable natural gas suitable for pipeline injection and vehicle fuel. The project will overall reduce the greenhouse gas emissions from WSSC by 15% and result in nearly $3 million per year in operation cost savings. COLLABORATIVE DELIVERY DURING DESIGN Some of the biggest benefits of alternative delivery include quick cost and constructability feedback during design. After the CMAR came onboard the Raleigh Water Bioenergy Recovery Project, cost estimates were provided at the 60-percent design level to inform value engineering for the project. Cost feedback continued throughout design, which progressed to 100-percent completion level for Guaranteed Maximum Price (GMP) development. At the beginning of the detailed design process of WSSC Water Bio-Energy Project, the PDB team considered how best to approach a series of critical decisions related to the digestion process to provide the best long-term solution for process performance, energy efficiency, and accommodation of potentially high volume expansion considerations while balancing capital costs. The critical decision areas that needed review and discussion included: digester construction method; digester mixing approach; digester volume/dimensions; rapid volume expansion containment approach; and digested sludge storage approach. These five decision areas were considered individually and collectively to understand the range of advantages and disadvantages that each would have on the overall project. SUCCESSFUL COMMISIONING Commissioning new equipment and processes can be challenging, especially when facilities must maintain operations and compliance with treatment standards. Discussions began during design to identify the optimal start-up and commissioning approach for each project. The different alternative delivery methods employed led to different roles, responsibilities, and contractual requirements for each project. This paper will review the start-up and commissioning plan for both projects.

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.

Wastewater intermittently enters our rivers, lakes and oceans via storm overflows at an alarming volume and frequency. This is a problem we face all around the world, for example in the UK only 14% of rivers meet good environmental standards. Significant investment is being made to tackle this issue, as a result of public and or regulatory pressure, and because we all know that we need to do better. However, to really make an impact and improve performance, wastewater collection system operators need to understand what is happening within their networks. Not just at sewer outflows or every 1km or so where a discrete monitor is placed, usually only providing a low frequency measurement of either flow or depth. If operators know what is happening throughout their system in real time they can learn to predict and optimize in real time. Creating a continually accurate digital twin of existing wastewater infrastructure makes this possible. Such 'Digital twins' enabled by the ability to rapidly monitor what is currently occurring in the system and predict what will happen. Having both capabilities allows for the smart allocation of resources and minimizes the risk of undesirable events. To produce and maintain an accurate data-driven digital twin requires dense (spatial and temporal) data about the network are required to drive and enable the smart networks. Such data is not currently available to sewer network operators but if available could unlock substantial savings and performance improvements. In this presentation we will cover the two main options for increasing the density of in-sewer monitoring to the level required for a digital twin to provide reliable information: 1. discrete sensors, and 2. distributed sensors. A comparison between these two types of sensors will be provided to highlight the benefits of the distributed sensor approach. Results from a case study utilizing a distributed sensor to monitor the conditions in a sewer will also then be discussed. Telemetered discrete sensors as mentioned above are able to monitor at a single location only, generally access chambers, providing information about limited parameters at that location. In gravity fed sewer networks this leaves the rest of the network unmonitored. Most discrete sensors measure only depth whilst a few measure flow. A reasonably low-cost option to purchase if only a few sensors are required, although the need for regular maintenance visits confirm that is actually a false economy. Discrete sensors can become very expensive when deployed for scale solutions. Equally, the communication and data management infrastructure required to operate the network of sensors quickly becomes unwieldly as each sensor is a separate object. For example, each sensor would need its own power supply, which would need replacing periodically, and would transmit data back independently requiring a separate correlation process to reveal the full picture. Even so, as the data points are isolated and local, in a gravity fed sewer the majority of the monitored network will still be invisible, thus requiring inference from nearby sensors which will then reduce the overall accuracy of the systems as a whole. Distributed sensors in contrast are continuous and in pipe, and therefore able to monitor the entirety of the network they cover. This means that the need for inference in the system is minimized as the sensor is providing information everywhere. A single data acquisition hub is able to monitor over 100km. Equally the acquisition infrastructure is located at a single point above ground. This means power only needs to be provided at one location rather than hundreds or thousands of separate ones. Data is then also transmitted from that single point making it easy to correlate results and gain insight from the acquired data. As the power requirements are easier to meet, the data is able to be transmitted continuously allowing for real time monitoring. Such systems can also provide other benefits. For example, the distributed measurement system developed by nuron has a dual purpose to provide fibre networking for broadband and 5G connectivity. Distributed fibre optic sensors operate by sending laser pulses down the length of the contained fibre. These pulses interact with natural imperfections in the fibre to produce backscatter whose properties such as amplitude, frequency and phase are affected by the temperature and strain experienced by the fibre. By measuring the properties of the backscatter, the conditions around the fibre can be measured and, by time of flight, the location of each measurement point can be found. This potentially provides a map of the flow conditions experienced within the entire collection network. One of the most useful outcomes of a distributed sensing system is to continuously validate and drive a digital twin such as that described above. For example, in this presentation we demonstrate the detection of high pipe occupancy and a blockage, both key to prevention of CSO spill events. Figure 1 shows the measured flow rate in a real sewer environment over the course of a single day. Normal nighttime behaviour of the network can first be observed consisting of almost no flow. As people begin to wake up at 6.30 this transitions to normal daytime flows. A heavy rainfall event occurs at about 15:00 leading to a sharp increase in flow rate which could lead to a CSO spill event. Figure 2. shows a web interface used to alert users to the presence of a blockage in the system which could also lead to CSO spill event. To simulate blockage situations a sensor was installed into the ICAIR test facility operated by the University of Sheffield. This allows us to conduct experiments that wouldn't be possible to do in active sewer environment. Such a system can be used to produce the required high quality dense data that a smart city needs to develop a digital twin. As the wastewater network is not an isolated system, other data sources, such as rainfall, are integrated into the algorithms to produce accurate predictions of the behaviour and needs of the wastewater network. By using historic data, the predictions of the system can be validated to ensure their accuracy. Equally, underlying trends of the system can be identified and accounted for. Machine learning and AI are used to interpret the large data volumes such a system produces to provide meaningful and actionable insights that customers require.

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.

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.