Conference Papers

The sewer collection system is an important infrastructure that protects the public health by safe disposal of wastewater. Sewer lines are designed for a certain carrying capacity, which is reduced by blockages, resulting in the risk of flooding and the occurrence of Sanitary Sewer Overflows (SSOs) that release raw contaminated sewage. According to the US Environmental Protection Agency, around 25% of the 23,000 to 75,000 SSOs are due to sewer line blockages related to fat, oil, and grease (FOG) deposits. Research studies have been conducted to understand the FOG deposit formation mechanism, sources of chemical constituents involved in FOG deposit formation, and engineering solutions to overcome the FOG-related SSO problems (He et al. 2017). These studies have shown that the long-chain free fatty acids (LCFFAs) from FOG discharge undergo a saponification reaction with calcium ion present in wastewater to form insoluble calcium soap known as FOG deposits that can adhere to sewer line surfaces to reduce its carrying capacity. The primary sources of FOG discharge are the food service establishments and domestic kitchen sinks, whereas sources of calcium can be attributed to the background wastewater as well as concrete structure corrosion. Previous research suggests that calcium released from concrete corrosion may have a more adverse impact on the FOG deposits accumulation on sewer line surfaces (Iasmin et al., 2014). The main contributor of calcium from concrete is the cement used as a binder. Research shows that the substitution of Portland cement by Supplementary Cementitious Materials (SCMs) such as Fly Ash (FA) reduces the calcium leaching potential of concrete exposed to corrosive media (Rozière et al. 2009). In the research discussed in this presentation, we will evaluate the use of FA to replace a large volume of cement to produce an alternative binder material for sewer line construction that reduces the calcium leaching from concrete corrosion, therefore, reducing the FOG deposit formation. We will also explore different factors such as- porosity and pore size, surface roughness, and surface pH of different sewer line construction materials to understand the FOG deposits adhesion mechanism. In our study, two High Volume Fly Ash (HVFA) concrete materials, Concrete-50 and Concrete-75, were produced by keeping the water to cementitious material ratio at 0.42 using 50% and 75% replacement of cement by FA, respectively. Additionally, control samples, Concrete-0, were cast with no FA replacement and used as a standard to study the effect of FA replacement. HVFA samples were tested for compressive strength (ASTM C39-15) and chemical durability (ASTM C267) to check their suitability as sewer line construction materials. Concrete samples were also tested for their calcium leaching potential at pH 5 and 7 by submerging them into Deionized Water (DI) for 90 days. The FOG deposit formation test was performed at pH 7 for a 30 days testing period by submerging concrete samples in synthetic wastewater prepared by mixing oleic acid as the LCFFA source, canola oil, distilled water, and calcium chloride as a background calcium source. The compressive strength test results show that after 90 days of sealed curing, Concrete-50 is well above 4 ksi; a threshold compressive strength used for sewer line construction materials. The chemical durability test results showed that 50% FA replacement enhanced the durability of concrete against corrosive media. After 90 days of leaching under corrosive conditions, Concrete-50 and Concrete-75 samples showed 75% and 86% reduction in calcium leaching, respectively, when compared with the standard Concrete-0 sample. The calcium leaching potential from HVFA samples also revealed that the calcium ion diffusion flux of the HVFA samples was almost similar and lower than the Concrete-0 samples. This observation suggests that FA replacement can reduce the porosity of concrete; thereby, reduce the calcium leaching potential from sewer lines under corrosive media. In addition to the calcium leaching potential, HVFA samples were also tested for heavy metals such as Arsenic (As), Cadmium (Cd), Chromium (Cr), Selenium (Se), Mercury (Hg), and Lead (Pb) leaching potential. After 90 days of leaching test, the cumulative toxic ion concentration for Concrete-50 and Concrete-75 samples did not exceed the pollutant discharge limit provided by USEPA clean water act. FOG deposition formation test results showed that 50% and 75% FA replacement can reduce FOG deposit formation by 55% and 67%, respectively. Therefore, results from this study suggests that a significant decrease in calcium release can be achieved through the use of FA as a cement replacement, which can eventually reduce the FOG deposit formation. To understand the FOG deposits adhesion mechanism on different sewer line surfaces, a combined FOG deposit formation test was conducted by submerging Concrete-0, Concrete-50, Concrete-75, Vitrified Clay Pipe, and PVC pipe into the synthetic wastewater for 30 days of the testing period. This test results revealed a similar FOG deposit formation trend (highest FOG deposition on Concrete-0 samples and lowest FOG deposition on Concrete-75 samples); however, no FOG deposits were found on PVC and Vitrified clay pipes surfaces. Hence, we hypothesize that the FOG deposit adhesion phenomena are primarily controlled by the sewer line material's surface properties in addition to the availability of calcium and LCFFAs. In the next phase of this study, to understand the effect of porosity, pore size, and surface pH on FOG deposit adhesion mechanism, porous ceramic materials with controlled pore size will be used for the FOG deposit formation test. Whereas, to study the effect of surface roughness on FOG deposits adhesion phenomena, HVFA and PVC samples will be prepared at different surface roughness and tested for the FOG deposition test. Results from these tests will be able to identify the key factors that affect the FOG deposits adhesion mechanism. According to Clean Watershed Needs Survey (USEPA, 2016), the total need for replacing sewer lines is $42 billion on top of $25 billion and $18 billion in the new collector and new inceptor sewers, respectively. Therefore, the present study will reduce the future sewer line construction and maintenance cost by reusing FA as an alternative sewer line construction material. Additionally, by studying the FOG deposit adhesion mechanism, this research will provide wastewater collection system utilities with strategies to develop new construction materials or potentially design future coatings that can enhance existing alternative materials to limit or reduce the FOG deposit accumulation on the sewer surface.

We invite water utility managers and professionals to join us at the upcoming Utility Management Conference for a presentation that promises to impact the future of the water industry. In 2022-23, a monumental job analysis survey was conducted, involving over 15,000 dedicated industry personnel across water, wastewater, wastewater collection, and water distribution domains. This unprecedented participation underscores the collective commitment to advancing our industry and is the foundation for certification standards in North America and globally. The outcomes of these extensive job analysis surveys, coupled with rigorous psychometric analysis, will serve as the cornerstone for developing the water industry's only standardized certification exams. This pivotal development will transform operator training, industry resource materials, and the content of certification exams. Behind this groundbreaking initiative are more than five dozen dedicated volunteers, who have invested hundreds, if not thousands, of hours in meticulously analyzing survey findings and identifying emerging trends. Our presentation will unveil the draft Need-to-Know Criteria documents derived from these findings, providing an exclusive preview of the future certification landscape. But that's not all. We encourage active audience participation and critique during the presentation. Your invaluable insights will assist the Certification Commission for Environmental Professionals in shaping relevant, robust, and legally defensible certification exams. Remember, water environment operators are the bedrock of our public health systems, and these surveys form the foundation for determining the criteria for operator competence. The Utility Management Conference offers a unique opportunity for participants to contribute to the Commission's final reports before they are released to the public and adopted by state and provincial jurisdictions. Be part of this transformative journey, and help us secure a safer, more efficient, and sustainable future for the water industry. Together, we can ensure that our operators are equipped with the knowledge and skills needed to protect public health and preserve our precious water resources. Join us in shaping the future of water operator certification.

This paper and presentation will survey and analyze the latest lawsuits and regulatory developments affecting the beneficial use of biosolids to provide wastewater and residuals professionals current information that will help inform their decisions on risk, liability, management, and planning. Slaughter and Silton regularly defend land application in litigation, and they are currently working on behalf of a major land application contractor-and its farm partners-to challenge a Pennsylvania locality's attempt to restrict land application. The speakers will discuss the challenges posed by local ordinances, tort litigation, and the ongoing campaign to regulate per- and polyfluoroalkyl substances (PFAS). This talk will outline potential risks, while also highlighting potential strategies for managing land application and discouraging attacks on beneficial use in the face of a changing legal environment and local communities that may be hostile to land application. Slaughter and Silton will first address the interplay between state and local regulation by exploring several case studies involving local attempts to restrict or ban land application. Their discussion will cover California, where decade-long litigation over a local biosolids ban resulted in a trial and settlement striking down the ban. City of Los Angeles v. Kern County, 2017 WL 1292822 (Tulare Co. Super. Ct. Mar. 14, 2017). Among other things, the Kern trial resulted in findings that land application poses few risks after hearing evidence concerning minimal concentrations of PFAS in soil and groundwater beneath a farm where biosolids had been land applied for decades. The speakers will also address recent developments in other states, including Pennsylvania, where the speakers are currently challenging application of a local waste ordinance to land application. Second, the speakers will survey risks to land application posed by tort law suits. Cases in which plaintiffs' lawyers have alleged nuisance conditions caused by land application will be discussed, including the important decision of the Pennsylvania Supreme Court in Gilbert v. Synagro Central, LLC, 131 A.3d 1, which ruled that farming with biosolids is a normal agricultural operation entitled to protection under Pennsylvania's Right to Farm Act. The speakers will also discuss a case brought in Maine, Stoneridge Farms v. 3M, in which a dairy farmer alleges that land application resulted PFAS contaminating his land, groundwater, and dairy cows. This case was voluntarily dismissed but portends a new generation of tort litigation seeking to challenge land application. Third, the talk will assess the regulatory landscape for land application. Legislators and regulators, at the behest of many advocacy groups, have turned their focus to trace chemicals that may be found in biosolids, including PFAS. Silton and Slaughter will highlight recently regulatory developments and their implications for POTWs, biosolids service providers, and farmers. The presentation will conclude with how stakeholders in land application-POTWs, contractors, and farmers-can collaborate to reduce their risks and navigate a challenging, dynamic legal and regulatory landscape.

In July 2019, a summer thunderstorm dropped up to 5.3 inches of rain in one hour over some parts of Fairfax County (up to a 1,000-year storm event), causing a reported 149 house flooding and at least $15M in damages. Studies continually show that these high intensity, short duration storms will become more frequent with climate change. The County had also recently enacted the One Fairfax policy, which states that departments must consider equity in the decision-making, development, and delivery of future policies, programs, and services. To comprehensively address flooding concerns, build resiliency into the stormwater network, and further the One Fairfax policy, the County pursued a more objective and equitable approach to flood mitigation by focusing on risk. At the time, Fairfax County's approach to flood mitigation was largely reactive. Flooding was identified through reported complaints. The County prioritized structural flooding adjacent to county easements and infrastructure and public flood mitigation projects were mostly at the individual lot level. The County recognized there were challenges with this method- residents did not always report flooding, older neighborhoods that developed prior to stormwater management standards often lacked public stormwater infrastructure or easements, and the approach offered few options for residents living in the floodplain. The County wanted to be more proactive and ideally address drainage issues before they caused flooding. Staff sought to develop a Geographic Information Systems (GIS) based flood risk map to meet multiple County needs. The map would help staff to select and prioritize capital improvement projects based on the frequency and impact of flooding. Regulators could utilize the data to inform plan review and code requirements. A public facing component could educate both residents and developers on a property's flood risk and an associated dashboard could track flood mitigation and resiliency metrics. Finally, the map would also build the foundation for a comprehensive flood risk reduction plan by helping County leadership and elected officials visualize the scope, cost, and timeline, to mitigate flood risk at a countywide scale. Fairfax County covers 395 square miles and does not have a comprehensive stormwater pipe capacity model. Staff recognized, however, that many of the conditions that make properties more vulnerable to flooding could be identified through existing GIS data. Stormwater management engineers worked together with GIS staff to develop a map to assess flood risk. The first version of the map used a parcel's location and proximity to ten potential flood hazard conditions to evaluate flood risk. Criteria included the following: structures within 30 feet of a FEMA floodplain, structures within 30 feet of a County recorded floodplain, structures in a 25-foot stream buffer, parcels with flooding or drainage-related complaints, parcels located in sumps, structures located in sumps, parcels in a subdivision older than 1972 (the year the County enacted stormwater management standards), residential infill lots (where older homes were torn down and replaced with much larger homes often lacking stormwater management), parcels located in subdivisions without stormwater quantity control facilities, and parcels located in subdivisions outside of stormwater facility drainage areas. Each criterion earned a parcel a score of one, with a total maximum score of ten. Over 350,000 parcels went through the selection process and were scored. Scores for each criterion were available at the parcel level, while total scores were available at the district or county scale as a heat map where the brighter color represented a higher flood risk. After reviewing the results, staff recognized some challenges with this first version of the map. The scoring double counted some of the risk factors. For example, a structure located in the FEMA floodplain, often also received points for being located in a County recorded floodplain and within the stream buffer. The scoring method also lumped fluvial and pluvial flooding together, making it difficult to evaluate the scope and cost of potential flood mitigation solutions. Perhaps most importantly, the map did not clearly and concisely convey flood risk to a lay audience, including both residents and county officials. A revised map narrowed the risk factors to the three main causes of flooding in Fairfax County- proximity to a floodplain, located in a sump condition, and the lack of overland relief. To identify these conditions, staff developed two flood risk analysis tools. The Potential Sump Conditions and Overland Relief Flow Accumulation Layers are the result of analysis performed on a Light Detention and Ranging (LiDAR) derived Bare Earth Digital Elevation Model. The Potential Sump Conditions layer highlights locations of sumps, or bowl-shaped depressions, where water pools and is unable to drain without flooding a structure. Flooding can also occur when there is a stormwater inlet in the sump, but it is overwhelmed due to the magnitude of incoming flows. The layer includes the volume and three-dimensional surface area of the sump. The Overland Relief Flow Accumulation Layer helps to visualize the natural overland runoff flow paths, including paths into and out of sumps. The flow path is strictly based on the bare earth elevation. This provides a clear picture of where the water flows when there is no stormwater management in place, or the infrastructure is overwhelmed. Using these tools, staff developed a revised flood risk map that analyzed four flood risk scenarios. Scenario One established a baseline by identifying all existing reported structural flooding. The second scenario highlighted structures in or within 15 feet of a mapped FEMA or County floodplain. Scenario three noted structures that intersected with or were fully contained within the Potential Sump Conditions Layer, where the sump depth was greater or equal to a foot and the overland relief drainage areas was greater than an acre. The final scenario noted structures that intersected the Overland Relief Flow Accumulation Layer where the drainage area was ten acres or greater. Staff then used the Fairfax County Vulnerability Index to apply an equity lens to flood risk. The Vulnerability Index is comprised of scores from several indicators from the American Community Survey data and ranks vulnerability low to very high on a census block scale. By overlaying the Vulnerability Index, staff identified the most vulnerable communities that were also more susceptible to flooding. Upon identifying these flood-prone neighborhoods, staff wanted to engage with the community to better understand their flood risk. Additionally, staff sought to increase resident awareness of its programs and services in these historically underrepresented communities. To do so, staff worked with a consultant to produce an Equitable Stormwater Management Engagement Framework (Framework) that outlines a systematic process for gathering input on flood mitigation needs and establishing new community relationships. The Framework's purpose was to create more inclusive, equitable, and authentic community engagement to ensure all voices are welcome in the County's planning and decision-making process. The document established a roadmap to achieve the following objectives- equitable consideration of flooding concerns without favoring one population over another, consideration of the vulnerability index and other factors, learning community issues and priorities, building trust with the community so residents feel comfortable contacting the County when issues arise, and understanding community values and priorities as they relate to stormwater and flooding. The Framework is intended to be living document that is updated as the County gathers lessons learned from its collective community of practice. In Spring 2023, the County plans to embark on the next phase of their flood risk reduction strategy. An interdepartmental workgroup will begin outlining a comprehensive flood mitigation plan that will include recommendations for a proposed Capital Improvement Plan project prioritization methodology, updated regulations for development and redevelopment, and programmatic solutions that will lead to a safer community and minimize property damage. Staff will also pilot the Framework guidelines by spearheading a targeted flood risk community outreach and engagement campaign in a highly vulnerable and potentially flood-prone neighborhood. Staff will continue to coordinate flood risk reduction strategies with Resilient Fairfax, a program to help County residents become more resilient to changing conditions and climate change-related hazards. This shift to a more objective and equitable flood risk approach will set the County up for a safe and more resilient future.

Purpose of the research and key message and knowledge transfer In summary, the key message from this work is two-fold: Close collaboration with industry enabled the design of a scientifically rigorous and highly focused experimental program in live sewers. The latter provided conclusive answers within four months and identified a way forward leading to technology implementation and identification of researchable gaps needed to make the technology more widely usable. The specific knowledge that this paper will transfer is that reliable humidity sensors to measure relative humidity >98% in gravity sewers can be achieved. This is a tool that will help the water industry to improve the management of its concrete gravity sewers and other infrastructure that is in contact with high concentrations of gaseous H2S in humid air. No commercially available technology can do this. In this work, the authors have demonstrated experimentally, building upon advanced design work, that optical fibre sensor systems represent an innovative, versatile and affordable technology that can be brought to bear very effectively on key monitoring problems in the water industry's infrastructure. Through the work reported and results demonstrated in this paper, the research has very successfully created a synergy of the skills of an academic group and a major water utility to identify, tackle and solve key problems in sewers -- problems that impact directly on consumers and are seen world-wide in the industry. In doing so, in an effective way like this, the paper demonstrates the benefits to be gained from a close collaboration between the two groups. Above all new knowledge has been transferred -- in both directions -- and through that new and more effective approaches to problem solving developed. Specifically, the project is based on new technology for humidity measurement -- this is an essential parameter that needs to be monitored to minimize corrosion of concrete gravity sewers. No humidity sensors that last longer than ~1 week in the aggressive gaseous atmosphere of gravity sewers and can reliably measure humidity above 98% relative humidity are available. Thus supporting better predictive maintenance, in situ monitoring of a sewer and an anaerobic digester is undertaken using innovative optical fiber-based sensor systems: these being chosen because of their inherent safety in the potentially methane rich environment, their ability to be protected against biofouling, their light weight, low power consumption (or battery powered), 4G compatible and ease of use over the long lengths (up to kilometers) needed for some applications. The multi-parameter sensors systems designed and evaluated are also well suited to use with the high levels of hydrogen sulfide, coupled with high humidity seen in sewers and biogas rich environments -- environments where conventional electronic-based sensor systems regularly fail due to acid attack. Benefits of Presentation and why this presentation should be selected and will provide a benefit to our industry Sydney Water's current management strategy relies on reducing gas phase H2S by the addition of chemicals (ferrous chloride, magnesium hydroxide and calcium nitrate) to the waste water. This strategy, implemented in a number of waste-water systems in Sydney, is costly (about $4M p.a.) and its effectiveness in reducing corrosion is unknown, due to an inability to directly measure concrete corrosion and deterioration of rehabilitation materials. No matter how effective this program is in slowing the corrosion rate, there will always be concrete corrosion and a method for prediction and detection of imminent pipe failure is needed because of the enormous costs of such failures. In particular, it is necessary to determine how much of the ubiquitous H2S and H2O can be left in the air in order to reduce corrosion rates to less than what Sydney Water defines as a sustainable 0.5 mm/year. Gravity sewers are buried infrastructures that undergo chemical deterioration because of microbiological induced corrosion (MIC). Microbiologically induced oxidation (MIC) of gaseous H2S into sulfuric acid results in concrete sewer corrosion. MIC costs billions of dollars annually to the water industry and has been identified as a main cause of global sewer deterioration. Sydney Water spends about A$60-80M annually repairing and protecting concrete gravity sewers and has a regular sewer inspection program. Currently, sewer condition is determined by man entry which is inconvenient and hazardous, has major safety issues and is expensive and so there is a need to minimize man entry by reducing damage from MIC, which can be reduced by controlling moisture in the gravity sewers to values approximately below 85% RH. No conventional humidity sensors that can last longer than one week exist under these aggressive conditions. Tackling this, this work describes the first and successful attempt to use optical fiber-based photonics sensors to monitor humidity in the range >98%RH in the overhead space in gravity sewers. This information is fundamental to develop reliable models that can predict the end-of-service life (EOSL) of concrete sewers. With the ageing of an asset, there is a point in its life, termed the End of Service Life (EOSL) and by doing so, it will be possible to save hundreds of millions of dollars that would have to be spent if collapses occur or premature repairs carried out to prevent a potential collapse. The approach developed together thus supports Sydney Water's corrosion management strategy, which has been created as an outcome of over $3M in research projects striving to better understand the processes that lead to the formation of H2S dissolved in the waste-water. Status of Completion The work done together by the authors has enabled the project to reach a high level of completion and results of the use of the systems in sewers and biodigesters have been reported in the major international media. Thus to date, three trials of tailor-made fiber optic-based sensor systems to monitor humidity in the range >98% RH in sewer air that contains high gaseous H2S concentrations of up to around 400 ppnv have been successfully completed. Based on this Sydney Water is implementing the photonic sensors technology in small catchments. For extensive implementation, Sydney Water is supporting extra research to develop 'low cost' interrogators that would make the technology more cost effective, well suited to long term, in-the-field research. Conclusion and take-away message The key 'take-away' message is that this is a significant innovation in optical fiber and photonic sensors that they can now be used in these 'dirty' environments. This has also allowed in-situ long-term monitoring under conditions where current technology fails. The major outcomes of the series of experiments carried out over the last five years is clear; fiber optic sensors systems can operate effectively, in the long term, in remote locations under battery power, saving of millions of dollars.

While achieving water resiliency and sustainability in the semi-arid climate of Southern California is of great importance, a large portion of stormwater runoff that picks up pollutants along the way is directed and discharged into the Pacific Ocean. Capturing and treating such runoff not only can help address water quality objectives in a watershed, it also is a huge untapped potential for providing local water supply and diversifying the water supply portfolio in a region that imports over 50% of its water supply. The imported water is mainly sourced from the State Water Project, Los Angeles Aqueduct, and Colorado River (Figure 1). All these sources have been affected by recent droughts and increasing water demands. Yet, more water supply interruptions are anticipated in the future, accentuating the need for increasing the resiliency and sustainability of local water supply. On the other hand, the existing stormwater infrastructure in Southern California has been built approximately 100 years ago with the main objective of addressing concerns about flooding impacts by channelizing main rivers, creeks, and other waterways to convey stormwater runoff to the Ocean faster. However, today's water supply deficit in the presence of infrequent and intense precipitation patterns is dictating a dual mission for water resources managers/decision-makers to create flood protection, while supporting local water supply. In 2018, Los Angeles County residents voted for passage of Measure W, which is a multi-benefit measure that provides cities and watershed areas within the County with funds to capture, treat, and recycle stormwater. Funding is provided through a parcel tax of 2.5 cents per square foot of impermeable land area, which provides approximately $280 million per year for multi-benefit stormwater capture projects. These projects are planned to enhance water supply, water quality, and community investment benefits through nature-based solutions such as installation of bioswales, native vegetation, constructed wetlands, etc. Additionally, projects funded by Measure W usually support addressing a major river's Total Maximum Daily Load objectives, while providing local water supply. These projects also require development and implementation of a Community Outreach and Engagement Program for the public, community, and key stakeholders to maintain awareness of project development and to gather their input in key design elements from the beginning of the pre-design phase to the end of the construction. This presentation will highlight two projects with objectives aligned with or funded by Measure W. Westwood Neighborhood Greenway Project: This project provides for urban runoff treatment, green space, access to public transit, and educational and recreational needs. The design treats dry- and wet-weather stormwater flows from drainage areas surrounding the project site. Dry-weather flow is diverted from the stormdrain to capture runoff from 2,400 acres of drainage area. The runoff flow is then captured and lifted to the simulated stream for treatment by flowing through plant communities, soil medium, and exposure to sunlight. The flow is diverted through an existing culvert and transported via a lift station and finally back to the stormdrain system. The main challenge during the project design phase achieving consensus among several stakeholders. The project team conducted frequent workshops to involve neighborhood and tribal communities, stakeholders, and the public to help them understand the benefits of the project's implementation and the beautification of the site that over time led to a consensus. Wilmington Q Street Local Area Urban Flow Management Project: This Measure W-funded project will use BMPs to capture the 85th percentile, 24-hour storm event runoff and treat it using flowthrough infiltration systems to improve water quality, remove pollutants affecting local water bodies, and modernize stormwater infrastructure. To capture and infiltrate approximately 17.2 acre-feet (AF) of runoff per year, various new nature-based stormwater infrastructure improvement BMPs will be installed. These include installation of drywells to capture stormwater flow, catch basins with diversion structures, permeable concrete sidewalks, and infiltration planters (Figure 2). These BMPs could remove pollutants of concern while providing a beneficial water supply to the local groundwater basin. The Project also incorporates drought-tolerant landscaping into stormwater treatment processes and reduces heat island effect. One of the main challenges we have anticipated through our initial investigations to be encountered during the design phase is that the soil infiltration rate assumed in the project's feasibility study might not be confirmed through further geotechnical analysis. This could highly influence the total load of pollutants removed, volume of captured stormwater, and consequently groundwater recharge volume that augments local water supply. In this case, we will modify the number, size, and/or depth of the drywells to ensure adequate stormwater is captured. Through this presentation, we will provide further details about these projects and share challenges and opportunities our investigators faced, solutions we found, and lessons learned.

1.0 Purpose Wastewater sludges that contain more than 1.5 to 2 percent solids have fluid characteristics that are different than clean water. The complex non-Newtonian behavior of sludges requires more in-depth hydraulic analyses, especially when there is variability in solids concentrations. These complexities can be quantified using rheology, the study of the deformation and flow of matter. Rheology is required to appropriately design systems for non-Newtonian fluids such as primary sludge, waste-activated sludge, combined undigested sludge, thickened sludge, digester recirculation, and dewatering feed sludge. The primary goal of measuring and representing these rheological characteristics is to achieve a higher precision in hydraulic design. Rheological data was gathered for a solids improvement project at Kitsap County's Central Treatment Plant to develop hydraulic model inputs in AFT Fathom„¢ to then determine thickened sludge process design criteria. Measured rheological characteristics and updated design method findings were compared to typical rheological values and historical design methods to inform final design criteria for the thickened sludge process improvements. The measured rheological data and alternative design approach can be applied to future projects by leveraging a growing data base of rheological characteristics and alternative design approach performance data. 2.0 Rheological History and Historical Design Approaches There are typically two approaches to sizing sludge pumps. When plant data cannot be collected, it is common to use standard rheological values. A downside to this approach is that it is typically only recommended for pumping lengths of less than 100 feet. Alternatively, pump testing can be used to determine rheological characteristics but it requires a pump to already be installed and, in many situations, hydraulic analysis and design must be conducted prior to testing. It can also be difficult to estimate the pressure spike associated with pump startup to initiate sludge movement. 3.0 Rheological Experimentation An alternative approach to estimate sludge pumping hydraulics is to test plant sludge with a rotational rheometer and use that data as an input to a non-Newtonian hydraulic model. Through the use of a Brookfield DVNext rotational rheometer, rheological sampling and analysis for pumped sludges can be conducted (Ametek Brookfield Inc., 2019). This piece of equipment applies a shear force and torque to a fluid using a rotating spindle. It records the shear rate, which is a function of the spindle speed, the shear force, torque, and viscosity. Testing these values by varying the spindle speed creates a viscosity and shear stress profile for each sample. This profile characterizes the rheological properties of the fluid. The samples are also tested to determine the solids concentration so a relationship between the rheological profile and percent solids can be defined. 4.0 Application of Rheology to Modified Design Approach The purpose of these plant-specific studies is to improve hydraulic calculations using the observed rheological properties of the sludge to then establish design criteria for sludge pumping applications. AFT Fathom„¢ is a hydraulic modeling software that has capabilities to input observed rheological data and compare it with various non-Newtonian fit models to estimate the hydraulic impact of a given sludge. Such models include the standard Power Law, Bingham Plastic, and the Herschel-Buckley fits (Water Environment Federation and the American Society of Civil Engineers, 2010). AFT Fathom can then use these characteristics and fit models, along with other information such as preliminary pipe lengths and fittings, to determine the total dynamic head and other hydraulic design criteria (AFT Fathom 2023). To further improve the analysis, AFT Impulse„¢ can be used to estimate transient pressure spikes that may occur during pump startup The Fundamentals of Unfamiliar Fluids (Clark, 2021), (AFT Impulse 2023). 5.0 Case Study HDR is designing improvements for various solids treatment processes at Kitsap County's Central Treatment Plant. Amongst other miscellaneous solids improvements, new primary sludge, septage, and WAS thickening equipment and two new digesters will be designed. Equipment to support these process improvements such as thickened sludge pumps, process piping, meters, etc. are included in the design. Rheological data was collected from the plant to design new sludge pumps and ensure adequacy of existing sludge pumps for process modifications. 5.1 Experimental Approach Data was collected over four sampling events, two different seasons, and varied operational scenarios to determine a modeling and design basis for different sludge streams. Co-thickened primary sludge and septage, digested sludge, and thickened WAS samples were collected and analyzed with the rotational rheometer on site. Triplicate runs were conducted for a wide range of shear rates to collect each stream's rheological properties per testing methods recommended by the rheometer manufacturer (Ametek-Brookfield, Inc., 2017). Once trials were complete, onsite laboratory staff used standard methods to determine each sample's percent total solids and total volatile solids. 5.2 Experiment Results and Data Evaluation Test results revealed that shear stress values are, generally, positively correlated with the total solids of the samples. As anticipated, seasonal temperature impacted viscosity measurements with the colder conditions prompting more conservative design values. For each stream, shear stress and shear rate data were evaluated using the Bingham Plastic, Hershel-Buckley, and Power Law rheological fit models. Tested samples had a lower percent solids (4-6%) than the anticipated design condition after the thickener (5-8%). To address this discrepancy, measured rheological fit curves were extrapolated to estimate the properties of thickened sludge with a higher percent solids concentration than what was tested. This approach required multiple hydraulic model runs using each rheological fit model to determine the most reasonable design conditions and to avoid oversizing of the pumps. In summary, measured data for each sludge was input into the hydraulic model for each rheological fit and compared to typical design approaches to estimate the total dynamic head (TDH) that the thickened sludge pumps would experience. In some cases, typical design approaches provided more conservative TDH values as compared to the alternative design approach using measured rheological characteristics. Figure 1 depicts one example of testing results for thickened waste activated sludge (TWAS), thickened primary sludge and septage (TPSS), and digester sludge. Figure 2 depicts the rheometer on-site during a sampling event. Comparison of TDH for typical design approaches and alternative modeled design approaches based on measured data are compared in Table 1. Another rheological sampling event will be conducted in January 2024 to measure additional characteristics and seasonal variability for the sludges in question. These additional results will be compared to summer sampling data to finalize elected design criteria for the thickened sludge process improvements. 6.0 Future Development of Rheology In preparation of the aforementioned rheological testing, an internal best practice document was developed in collaboration with Matt Higgins at Bucknell University to define appropriate rheological testing criteria, data analysis methods, and design approaches using measured data. It is expected that this document will continue to be refined as more sampling events are conducted. Upon construction of each project, performance data will be evaluated to calibrate and improve the experimental criteria and alternative design approach. Rheological data sets from sludges tested at various plants can be compiled into a database to evaluate trends and consistencies in different sludges. Depending on the depth and breadth of data available and resulting findings, this comprehensive dataset may ultimately be used as a standard reference for design.

The intern program at South Platte Renew was formalized in 2019 to highlight the work of professional engineers in the water/wastewater field. Over the last four years, the program has evolved into a comprehensive experience for junior to senior level university and college engineering students to showcase the diverse engineering and problem-solving opportunities available within a professional setting. Experiences range from construction inspection, design and planning, budgeting, technical and process optimization, lab work, and piloting treatment technologies. In providing several resources and contacts, students can explore different facets of the wastewater field and experience the unique offerings from a public entity. Along with classic engineering technical skills, interns are shown the political drivers and challenges that must be considered when working as a government agency. Students are also given the opportunity to grow their professional networks, complete vital trainings, and build resumes with applicable experience. The main goal of the SPR Intern Program is to engage young engineers in the diverse work of wastewater in hopes to inspire them to join the workforce in the public sector. This presentation highlights the efforts and methods by SPR to build and maintain an intern program and how others can benefit from a university-to-organization pipeline. The framework and planning documents can be customized for the 3-month internship based on the organization's needs and focuses for that year.

Green infrastructure and source control technologies are increasingly accepted as a best practice for reducing stormwater impacts on water quality and aquatic habitat in urban areas. However, impacts continue to grow in many watersheds within the United States even as progress is being made on other sources of water pollution (NRC, 2009). Stormwater management practices have been improved at the site level, but they are not being implemented on a large enough scale to offset water quality degradation caused by urban and suburban land use trends (WEF Stormwater Institute, 2015). Philadelphia is one city implementing green infrastructure on a large scale as a key component of its approach to manage urban stormwater and combined sewer overflows. The Philadelphia Water Department will complete its tenth year of program implementation in 2021. This paper will cover the status of the program, provide statistics on the types and locations of green infrastructure that have been implemented, and summarize performance monitoring data collected from systems operating in the field. PWD submitted its Combined Sewer Overflow Long Term Control Plan Update in 2009, as required by its National Pollutant Discharge Elimination System permits. In 2011, a modified version of that plan was approved for implementation through a Consent Order and Agreement (COA) with the Pennsylvania Department of Environmental Protection. The COA specifies combined sewer overflow reductions, pollutant load reductions, and implementation of green stormwater infrastructure targets intended to improve water quality in local watersheds and the Delaware tidal estuary. As the program approaches the ten-year milestone, it has implemented stormwater management features managing surface runoff generated by approximately 1,100 acres of impervious urban surfaces (Figure 1). Stormwater management features have been implemented through a variety of programs and on a variety of land uses (Figure 2). These include projects on private property initiated by code requirements governing redevelopment. Projects have been implemented on public property, including streets, sidewalks, and public facilities. Finally, projects have been implemented through incentives for private property. Post-construction monitoring data from selected sites indicate that systems are generally meeting or exceeding design performance expectations (Figure 3).

This paper and presentation will survey and analyze the latest lawsuits and regulatory developments affecting the beneficial use of biosolids, including compost, to provide wastewater and residuals professionals current information that will help inform their decisions on risk, liability, management, and planning. Slaughter and Silton regularly defend land application in litigation, and counsel both POTWs and biosolids service providers on regulatory issues. The speakers will discuss the challenges posed by local ordinances, tort litigation, and the ongoing campaign to regulate per- and polyfluoroalkyl substances (PFAS) in biosolids and groundwater. This talk will outline potential risks, while also highlighting strategies for managing land application and discouraging attacks on beneficial use in the face of a changing legal environment and local communities that may be hostile to land application. Slaughter and Silton will first address the dynamic and problematic regulatory landscape for land application, highlighted by Maine's ban on land application because of trace PFAS. Federal, state and local legislators and regulators, at the behest of many advocacy groups, have turned their focus to PFAS and other trace chemicals that may be found in biosolids. These efforts have spurred regulators to take a variety of actions, including EPA's September 2022 proposal to designate two PFAS-PFOA and PFOS-as hazardous substances under the federal Superfund statute. If the proposal is adopted as a final rule, it could pose risks to land appliers and POTWs. Silton and Slaughter will survey recently regulatory developments and their implications for POTWs, biosolids service providers, and farmers, including ongoing litigation challenging some of the stringent PFAS regulations. Slaughter and Silton will also address the interplay between state and local regulation by exploring several case studies involving local attempts to restrict or ban land application. Their discussion will cover California, where decade-long litigation over a local biosolids ban resulted in a trial and settlement striking down the ban. City of Los Angeles v. Kern County, 2017 WL 1292822 (Tulare Co. Super. Ct. Mar. 14, 2017). Notably, the Kern trial resulted in findings that land application poses few risks after hearing evidence concerning minimal concentrations of PFAS in soil and groundwater beneath a farm where biosolids had been land applied for decades. The speakers will also address recent developments in other states, including Pennsylvania, where the speakers recently challenged enforcement of a local waste ordinance against land application. Second, the speakers will survey risks to land application posed by tort lawsuits. The risk of tort lawsuits based on trace PFAS in biosolids, soil, and groundwater will be examined. Cases in which plaintiffs' lawyers have alleged nuisance conditions caused by land application will be discussed, including the important decision of the Pennsylvania Supreme Court in Gilbert v. Synagro Central, LLC, 131 A.3d 1, which ruled that farming with biosolids is a normal agricultural operation entitled to protection under Pennsylvania's Right to Farm Act. The presentation will conclude with how stakeholders in land application-POTWs, contractors, and farmers-can collaborate to reduce their risks and navigate a challenging, dynamic legal and regulatory landscape.

This presentation will showcase the different strategies MS4 municipalities in Lancaster County, Pennsylvania, are taking to implement stormwater projects to achieve required pollutant reductions as cost-effectively as possible. Some of the methods include securing grant funding, using municipal public works staff to implement projects, establishing Municipal Authorities and enacting stormwater fees, working with private landowners, and partnering with the agriculture community. In September, 2017, the Pennsylvania Department of Environmental Protection (PADEP) required Municipal MS4 Permittees to prepare and submit pollutant reduction plans (PRPs) for locally impaired waters and for the Chesapeake Bay. Municipalities are required to demonstrate pollutant reductions, measured in pounds per year as follows: 10% sediment; 5% phosphorus, and 3% nitrogen. These reductions must be achieved within 5-years of the PRP approval, which ranges from June 2023 through August 2024. PADEP selected sediment as the primary target for pollutant reductions and indicated that if municipalities achieved required sediment reductions then the phosphorus and nitrogen loads were assumed to be met. In Lancaster County, municipalities planned to implement the following projects: 17.13 acres of urban riparian buffer (24 projects) 59,105 linear feet of stream restoration (63 projects) 37 bioswales/bioswale retrofits 60 detention basin retrofits 10 raingardens When implemented, these projects will achieve 5,211 tons/year sediment reduction (10,423,460 lbs) at an expected cost of more than $50 million (based on $5.00 per lb of sediment reduction). While several municipalities worked together to implement joint projects within the same watershed, the majority are working individually on projects within their own jurisdiction — which places a heavy financial hardship on the community. For many, the expected costs to fund stormwater projects to comply with the PRP exceeds $500,000. This presentation will summarize the strategies that five municipalities, West Hempfield, Paradise, Rapho, Ephrata, and Manor Townships, are taking to achieve required pollutant reductions as cost-effectively as possible. Participants will learn the benefits and challenges of each strategy through case-studies and project analysis.

ABSTRACT British Columbia (BC) is 1.4 times the size of Texas. While only 1% of its land base is native grassland, these areas have been historically prized for homesteading and early agriculture. Today they are mainly used for ranching, but over a century of use has left many BC grasslands in a degraded state. These grasslands support more threatened and endangered species of birds, animals, and vegetation than any other terrestrial biome in the province. The OK Ranch is a 15,000 acre cow-calf operation located in the interior of BC, and was emblematic of these challenges. The upland grasslands of the OK Ranch experienced a decrease in productivity over the last century due to long-term agricultural and grazing practices, now compounded due to climate change. First Nations oral histories tell of tall grasses 'belly high to a horse' flowing with the upland winds, but due to historic homesteading and more recent attempts at cereal production in this dry, high-altitude area, soils were exposed to harsh elements and the natural forage was unable to return to previous production levels. In 2013, SYLVIS partnered with the OK Ranch's landowner to emphasize grassland restoration using biosolids to achieve effective stewardship as well as productivity for the ranch operation. Since that time, SYLVIS and Metro Vancouver, together with several research partners, have sought to understand and quantify the benefits conferred to the site through the careful use of biosolids as a soil amendment tool. This presentation will share the unprecedented understanding of what can happen for a degraded ecosystem when provision of critical soil conditioning supports rehabilitation. Specifically, we will discuss how: -Soils have been protected through the growth and expansion of a thatch layer, and reduction of bare soil and crusting throughout the site. -Grasses have recovered and now grow with vigour, producing up to 400% more biomass, while also being more nutritious for cattle and ungulates. -The changes in biomass and resilience have resulted in significant carbon capture on the landscape, both in short-term annual carbon through above ground biomass, but also in long-term belowground carbon capture and storage in soils and roots. -The improved grass structure has resulted in favorable habitat development for endangered or threatened insects, which in turn support threatened bird species, which has become a major research focus at the OK Ranch through a partnership with the University of British Columbia. -Mammals, large ungulates, and predators appear to spend more time in the grasslands. -The productivity has resulted in increased employment at the OK Ranch, with more cattle and more hands hired to help manage those cattle. -A desktop analysis of climate change mitigation and ultimate benefits to the environment provides a compelling case for the economic, environmental and societal value of grasslands restoration. The OK Ranch grasslands restoration project is more than just land application of biosolids. It demonstrates the layers of co-benefits provided through the restoration of semi-arid grasslands of not just soil improvement, but of carbon capture, habitat recovery, and economic development. . The presentation will conclude with a discussion of what levels of awareness and information sharing might be required, and what innovative strategies are available to increase uptake of beneficial use messages to achieve this kind of scale for grassland restoration in North America.