Conference Papers

This presentation will describe how Palmdale Water District is successfully navigating the federal and California funding landscape to secure capital for an innovative, regional recycled water program. Content will cover the funding approach, coordination between key stakeholders and team members, integrating compliance into project delivery, and lessons learned. The Pure Water Antelope Valley program is a regional recycled water program to improve water supply resiliency for a large, disadvantaged community of over 125,000 people in Los Angeles County. Securing external funding is critical for the implementation of Pure Water Antelope Valley, as affordability is a top concern for PWD's low-income customer base. To continue to meet current capital and operational needs, Palmdale Water District (PWD) has raised water rates by 5.5% annually from 2014 to 2019 and by 8.1% annually from 2020 through 2024. PWD has been proactive in securing external capital for this critical project. The team has reviewed viable funding opportunities, analyzed trends in funding priorities and strategized how multiple opportunities could be phased together to fund the planning, design, and construction of the various components for the Pure Water Antelope Valley program. The Infrastructure Investment and Jobs Act, Inflation Reduction Act, California AB 179, and other recent federal and state policies were integrated into the analysis, including weighing the pros and cons of federalizing the program to be able to leverage federal funds. PWD met with funding program administrators to review upcoming funding sources and discuss the competitiveness of the project. To increase project competitiveness, PWD's funding team provided the mapping materials and census data needed by the California State Water Board to secure disadvantaged status for the program for a period of three years. Other differentiators of the project were also identified by the team, such as its use of natural infrastructure, multi-stakeholder partnerships, and ties to decarbonization and climate change resilience. As a result of the analysis, Pure Water Antelope Valley has a plan for building a capital stack for 100% of capital expenditures through a combination of grants, subsidized loans, and revenue bonds. Since 2022, the PWD funding team has developed and submitted five grant applications and an EPA WIFIA loan application and worked with the engineering team to integrate federal compliance requirements into design and bid documents. Making sure that PWD has the latest information related to funding, the team also tracks funding-related legislation such as the federal Inflation Reduction Act tax credits and the California climate bond. The funding team is largely successful because they have the technical and financial expertise to smoothly coordinate across engineering and finance teams alike including PWD's financial advisor and bond counsel. To date, PWD has been offered more than $20 million in grants and up to 49% of total project costs in low-interest loan financing that will save PWD ratepayers millions of dollars. By the end of this presentation, attendees will be able to: Evaluate their priority projects' competitiveness and key differentiators for federal and state funding programs Strategize ways to combine multiple federal and state grant programs to build a capital stack for a project Discuss the technical and financial expertise required to compile competitive grant applications

Industrial activities have created many brownfields throughout the Chicago metropolitan area. Brownfields are generally associated with poor soil health, inferior nutrient cycling, and attenuated soil ecosystem services, as demonstrated in low primary production and carbon (C) sequestration, low diversity of soil biota and plants, and high runoff with impaired water quality. Thus, restoration of brownfield sites not only increases the economic value of the sites, but also increases the ecosystem services the land provides. A research and demonstration site for brownfield restoration was established on Metropolitan Water Reclamation District of Greater Chicago (MWRD) land along the Chicago Sanitary and Ship Canal, which has been classified as a brownfield site due to prior use of the site for storage of petroleum and chemicals and destruction of soil horizons. Due to their physical, chemical, and biological properties, biosolids, which contain high amounts of organic matter, are an ideal soil amendment for degraded and contaminated soils. In addition to C and nutrients, biosolids contribute to an active microbial community, which is a critical component of soil ecosystem function, including nutrient cycling, C sequestration, plant symbiosis, and contaminant degradation. Research plots were established in October-November 2021 using Split Plot design with four replications. The main treatments were 1) control (no amendments to the existing soil), 2) air-dried biosolids at one-half rate (air-dried biosolids applied at 2.5 cm depth or 130 Mg ha-1), 3) air-dried biosolids (air-dried biosolids applied at 5 cm or 260 Mg ha-1), 4) composted biosolids (woodchips composted with biosolids-3:1 at 5 cm depth or 185 Mg ha-1), and 5) a blend of biochar and air-dried biosolids (pyrolyzed biosolids at 1.25 cm depth and air-dried biosolids at 3.75 cm depth or 105 Mg ha-1 pyrolyzed biosolids mixed with 195 Mg ha-1 air-dried biosolids). For the same thickness (5 cm) of soil amendment applied, the loading rate in weight basis was lower in composted than air-dried biosolids due to the lower bulk density for composted biosolids. Since composted biosolids contained more organic C (25.8%) than air-dried biosolids (19.8%) by mass, the C input from the two amendments applied in 5-cm treatments were comparable. The biochar/air-dried biosolids blend also leads to a similar C input to the 5 cm air-dried biosolids treatment, as biochar contained 21.5% of organic C, just slightly higher than that for air-dried biosolids. Subtreatments are two prairie plant communities with C4 grasses for subtreatment 1 and C3 grasses and forbs for subtreatment 2. The subplot size was 4.5 m x 5 m. The plots were hydro-seeded with native plants in November 2021. Additional seeding by drilling is still needed due to the poor germination during the first year, which is common for establishing native plants. This report will focus on assessing the impacts of biosolids on soil health in degraded urban soil, which supports plant establishment. We sampled soil in April 2022 at 010 cm depth and analyzed the key parameters for soil health, including soil organic C (SOC), nitrogen (N) mineralization potential (NMP), microbial basal respiration, microbial biomass C (MBC), and water-holding capacity (WHC). Due to the high gravel content of the brownfield soil, all results except for soil WHC are presented as 'stock' in 010 cm soil depth by using bulk density of soil materials (< 2mm). Results for two subtreatments within a main plot are pooled for this report of the soil measurement. All soil amendments drastically increased soil WHC from 53% to 100121% (dry soil weight basis), which is associated with the increase in SOC (Table 1). Soil organic C in the control plots had a mean of 17.4 kg ha-1 in the top 10 cm (Table 1) with a range of 10.026.0 kg ha-1). The C-rich soil amendments considerably increased SOC, leading to higher than 30 kg ha-1 in soil for all four amendments. Microbial biomass C measurement indicated that microbial populations were more abundant in plots with the soil amendments than the control: however, it varied depending on the amendment type (Table 1). Microbial biomass C was highest under the air-dried biosolids, followed by air-dried biosolids at one-half rate, composted biosolids, and the biochar-biosolids blend, and lowest in the unamended control soil. Microbial respiration, the CO2 output of the microbial community, reflects microbial quantity and activities and the utilization of substrates by microbes. We found that the soil microbial basal respiration in the control plots was low relative to the treatment plots (Table 1). The high biosolids rate had a higher basal respiration rate than the other treatments. The microbial metabolic quotient (qCO2), the respiration rate per day per unit microbial biomass, helps us understand the environmental stress level for microbes in the soil. High qCO2 indicates greater environmental stress for soil microbial communities. The full rate of air-dried biosolids reduced the qCO2 compared to the control, though the other soil amendment treatments had a similar qCO2 to the control (Fig. 1), indicating that air-dried biosolids can provide a less stressful habitat for microbial communities. Nitrogen mineralizing potential is important for evaluating N accessibility to soil microorganisms and plants. For the sampling period, approximately six months after plot establishment, control plots reflecting the degraded conditions of the site had a very low NMP of only 0.01 kg ha-1, compared to a range of 2.584.2 kg ha-1 in the treatment plots (Table 1). All three treatments that received air-dried biosolids had a higher NMP than composted biosolids. The results presented here showed that the use of biosolids as a soil amendment gave rise to significant improvement in the health of degraded urban soil, which will facilitate plant establishment and possibly drive interactions among microorganisms, plants, and soil components for restoring ecosystem services of the brownfield.

From June to August 2021, the U.S. Department of Health and Human Services, in collaboration with the Centers for Disease Control and Prevention, conducted the second phase of a national Covid-19 wastewater monitoring program. Through this program, >6,000 wastewater samples were collected from over 362 municipal wastewater treatment facilities across all 50 states, the District of Columbia, and 2 US territories, covering 98 million people, or 30% of all Americans. Concerns for equity guided onboarding goals, and participating plants included rural and urban communities as well as 9 tribal Indian territories. Collected samples were processed by a commercial vendor. Measured SARS-CoV-2 concentrations were uploaded into the HHS Protect and CDC NWSS databases. A subset of samples were sequenced, and viral RNA sequences were uploaded to NCBI. In multiple cases, wastewater facilities split samples, sending one aliquot to the national program vendor and another to a local university or research group, allowing for multiple real-world methodology comparison studies. Over the course of the program, key lessons about program logistics, data sharing, data quality, and data interpretation were learned. These findings and lessons should inform the design and implementation of future large-scale wastewater monitoring programs.

BACKGROUND
The Oakland-Macomb Interceptor Drain (OMID) is the main wastewater interceptor that serves nearly 850,000 customers in 25 municipalities in Oakland and Macomb Counties north of Detroit, MI, USA. The Oakland-Macomb Interceptor Drain Drainage District (OMIDDD) operates the approximately 22-mile (35.4-km) unreinforced concrete interceptor that includes piping from 3 feet (0.3 meters) to 12.75 feet (3.9 meters) in diameter, 10 metering facilities receiving flow from contributing community sewers, and the 273-MGD (1,033-MLD) rated capacity Northeast Sewage Pumping Station (NESPS). Upstream of the NESPS, the OMID also receives flow from the Macomb Interceptor Drain (MID) that collects flow from suburbs to the east and is operated by the Macomb Interceptor Drain Drainage District (MIDDD). The MID portion includes about 26 miles (41.8 km) of large-diameter unreinforced concrete interceptor piping, 23 metering facilities, and 2 pump stations. There is corrosion in some locations of the OMID due to sulfuric acid (H2SO4) formed from hydrogen sulfide (H2S). The H2S released from the sewer also results in recurring odor complaints. Hydrogen sulfide release is greatest at turbulent vertical drop manholes where community sewers at higher elevations discharge into the deeper OMID and when control gates are operated during the OMID's unique 'storage and release' practice of flow control. Odor and corrosion issues extend back to the 1970s when the OMID was constructed. Since 2011, the OMIDDD has taken steps to study these issues and initiate mitigative improvements on behalf of ratepayers.

OBJECTIVES
Through both comprehensive studies and mitigation strategies, the OMIDDD seeks to accomplish the following key objectives for the interceptor: -Reduce the rates of corrosion -Cost-effectively extend its operating life -Minimize odor complaints throughout the system Though this paper focuses on the efforts of the OMIDDD, the MIDDD maintains similar objectives with their interceptor. Together, both Districts are working toward complete odor and corrosion control coverage of their combined systems. The Districts currently have active interceptor grouting and lining operations; however, the size of the interceptors makes Contractor mobilization, access, and liner installation a costly effort. With appropriate odor and corrosion control, these lining operations could potentially be limited to specific problematic segments and result in a significant cost savings.

METHODOLOGY
Characterizing the impact of sulfide generation, H2S release, and sewer corrosion required a comprehensive approach. This included reviewing past studies and completing field sampling, sewer process modeling, air dispersion modeling, and fan testing. The extensive data collection program at 17 locations throughout the OMID included liquid-phase dissolved sulfide grab samples and about four weeks of continuous monitoring of sewer differential pressure and vapor-phase H2S concentration using digital monitors. The same sampling effort was completed at 19 locations in the MID; thus, allowing for complete characterization of the large diameter tunnel network. Field sampling, wastewater quality, and hydraulic modeling data were used to develop and calibrate a complete system sewer process model. With this model, multiple conditions that might influence odor generation and sewer corrosion were evaluated: -Dry weather (low flow), -Wet weather from inflow and infiltration (high flow), -'Storage and release' operations -Future phased rehabilitation (e.g., adjusting gate operation frequency/duration for routine Contractor access) -OMID realignment Rates of concrete corrosion predicted by the sewer process model were correlated to prior condition assessments completed using the Pipeline Assessment Certification Program (PACP) ratings and used to approximate remaining pipe life based on the long-term operating strategy of the system up to a maximum allowable concrete loss of 1 inch (25 mm). Concrete loss plots (see example, Figure 1) for the various conditions were created to identify locations along the interceptor alignment most susceptible to deterioration. Process modeling also accounted for 'storage and release' operation, where wastewater is stored in the OMID using flow control (gate) structures. Storing wastewater either for flow management or downstream maintenance access increases detention time, thus generating sulfide. When released either by raising the low-flow sluice gates or overtopping the divider walls in the flow control structures turbulence results in H2S stripping (Figure 2). This pressurizes the H2S-containing odorous air in the interceptor headspace, often leading to off-gassing through ground-level manhole cover pick holes. Sensitivity of ground-level receptors to sewer off-gassing under average dry weather flow and at drop connection manholes was evaluated through air dispersion modeling. The OMID system has relatively few venting locations. Manholes along the interceptors that are spaced relatively far apart (about 1,000 feet, or 300 m) result in low natural ventilation rates. Assuming that the ambient odor impact criteria should be at or below a 7-D/T for 1-hour of community impact 99.5% of the time, air dispersion modeling results characterized the likelihood that an odor control strategy would affect ground-level impacts through management of sewer pressure, H2S, or both. Finally, once the most appropriate odor and corrosion mitigation locations and vapor-phase treatment technologies were identified, field fan testing with sewer pressure monitoring was completed to right-size the future odor control system (Figure 3).

RESULTS AND CONCLUSIONS
This comprehensive approach to evaluating OMID-specific operating conditions enabled the design team to identify the most effective locations and methods to address odor and corrosion. Both liquid-phase and vapor-phase technologies were evaluated through sewer process modeling. Three locations for activated carbon vapor-phase odor control systems were identified. Two systems one actively ventilated and the other passively will be located at flow control gate structures. The third system will be actively ventilated and located at the drop manhole downstream of a community sewer metering facility. Together these systems are expected to address odors and corrosion across most of the OMID. During storage conditions, the vapor-phase systems will not provide continuous control due to headspace constrictions. Likewise, the sizes of the recommended vapor-phase devices will not be large enough to depressurize the sewers for some storage and release events when the release rates are relatively fast and the stored wastewater volumes are relatively high. Process modeling showed that if storage and release events were to be conducted frequently-such as every day-the pipe life could be significantly reduced. However, under normal dry weather conditions, these systems will effectively depressurize the sewers and odors will be effectively mitigated. Corrosion will also be greatly reduced in the main interceptor but may persist at some locations lacking continuously wetted surfaces. These areas may be appropriate candidates for lining. Design has begun at each location, providing unique challenges related to aesthetics, visibility, and site constraints for which unique solutions are being pursued. For example, the community metering station is surrounded by residential homes, therefore requiring concealment that closely reflects the neighborhood (Figure 4). Facility designs will be completed in 2023.

Often the mesh resolution used in a 2D model comes down to reasonable run times, but what impact does that have on the analysis and ultimately the results? In this presentation we'll take a look at the results of a fully 2D hydraulic model with varying levels of mesh resolution and see how calibration was also impacted. In 2008, Iowa City, IA experienced a catastrophic flood event. Soon after the event, 23 high water marks were collected throughout the city for the purpose of building and calibrating a hydraulic model. Along with as-built plans for the bridges, land use, and DEM, a fully 2D hydraulic model was built and calibrated. Four copies of the model were made in order to build different models with varying levels of detail and ranged from having ~1.5 million cell elements to ~75k cell elements. Results from each model were compared to each other at each of the high water marks to highlight differences and statistical error between each one. Additionally, the four copies were then re-calibrated to try to reduce the amount of difference and error which ultimately resulted unrealistic modeling parameters. As 2D hydraulic modeling becomes more prevalent in the stormwater industry, its important to understand how some of the fundamental and initial decisions when beginning a 2D hydraulic analysis will impact the results. This presentation is designed to highlight why mesh resolution is such an important decision and should be given a higher level of attention beyond just a consideration for run times.

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

Information is power. Advances within molecular biology and analytical chemistry enable environmental engineers, public health officials, and regulators to transform wastes, such as municipal solid waste and wastewaters, into quantifiable and actionable data. Monitoring campaigns have been successfully established characterizing a variety of targets including pathogens, pharmaceuticals, and illicit substances across communities, within sewer-sheds, and at buildings. These campaigns have been increasingly reported in literature, with terms such as 'wastewater-based epidemiology' expanding near seven-fold in article usage from 101 articles in all of 2018 to 746 in 2021 (to date). Additionally, with the formulization of support and resources through the establishment of government programs such as the National Wastewater Surveillance System (NWSS) at the Centers for Disease Control in the United States and the proposed Sentinel Sewage Surveillance Program in the European Union, the field is maturing rapidly and achieving regulatory framework. This advancement, however, utilizes an evolutionary shift in our domestic materials management that has ethical ramifications that must be considered: waste as a material to treat and dispose versus waste as a diagnostic and informative signal. Therefore, this paper reviews ethical frameworks previously described for monitoring either municipal solid waste streams or wastewaters, utilizes these frameworks in a metanalysis to score reported SARS-CoV-2 monitoring campaigns, and provides suggestions of best practices to tackle areas that are identified as of common ethical concern. Two main ethical guidelines are considered in this analysis: the Canadian Water Network's interpretation of the 2017 World Health Organization surveillance guidelines (CWN; Hudley et al., 2021) and the framework proposed by Marx for new surveillance (MNS; Marx 1998). CWN provides a broader framework, comprising 14 high-level metrics that focus on the need, equity, and proper implementation of the monitoring programs. MNS, however, breaks the interpretation into 29 specific points details the means, context, and uses of the data collection effort. Additionally, CWN distinguishes itself from MNS by focusing on the ethical imperative for participation in public health crisis, whereas MNS highlights the inherit expectation to privacy to waste streams. Previous sampling campaigns are interpreted utilizing these 43 combined metrics. Overall, at least 50 reported sampling campaigns with peer-reviewed publications are considered within this analysis. These articles are binned into the following scales: building (20), collection system (10), and community (20). An additional split is made between the selected building-scale studies between primarily residential (15) or non (5). A score is applied for each of the analyzed metrics based on a four-tier system: violating (2), potentially violating/passing (1), passing (0), and not applicable. The mean scores (not applicable scores are masked from this analysis) are analyzed for each category for all sites to highlight areas of general concern for wastewater surveillance. Additionally, differences are determined between scales to identify scale-driven ethical considerations. This analysis highlighted several areas of concern. At the building scale in which direct actions are taken with increased viral concentrations, the monitored populations primarily lack the ability to appeal against the data, a problematic implementation when considering fair review of the data. Across scales, care must be taken in directly utilizing wastewater information to account for the potential intentional or accidental contamination of a publicly accessible signal. Finally, a conceptual concern highlighted within these studies was the repercussions from opening a new objective for monitoring. Surveillance systems targeting SARS-CoV-2 advanced wastewater monitoring from a concept of surveying the wastewater to treat to quantifying a signal to diagnose the connected population. A diagnosis mindset adds to an already wide range of applications for wastewater surveillance, with the ethical considerations driven by the specific context. Expanding beyond the demonstrated SARS-CoV-2 analysis, the ethical framework is applied to five potential monitoring scenarios: (1) virus tracking within a pandemic, (2) virus tracking when at or below seasonal baseline values, (3) bacterial tracking of an infrastructure related pathogen (e.g., Legionella), (4) small molecule tracking of a consumed product (e.g., pharmaceuticals, illicit substances), and (5) small molecule tracking of a human metabolite. Within this analysis, a respiratory pandemic in the United States is considered as when the percent of all deaths that result from pneumonia, influenza, and COVID-19 (PIC) exceeds a seasonally adjusted threshold of approximately 6-8%, as tabulated and reported by the National Center for Health Statistics. These scenarios challenge both the CWN and MNS framework uniquely. For example, monitoring outside of a pandemic potentially removes the ethical imperative of participation highlighted by the CWN (scenarios (2), (3), and (4)). However, monitoring for human exposure to air, water, or soil contaminants (scenario (5)) may provide a necessary tool to assess non-pathogenic community exposure hazards and inequality. Uniquely, scenario (3) underscores an ethical imperative within water distribution and wastewater collection services: ensuring the safety and reliability of the infrastructure. Finally, each of these contexts have nuanced considerations, for example whether the virus being tracked has associated historical stigma, the small molecule is classified as an illicit substance, or that the small molecule can be directly associated with the consumption behavior of a subset of the monitored community. With the rapidly advancing wastewater surveillance field, this ethical analysis highlights areas that should be further considered when designing and implementing a monitoring campaign. Overall, equal access to sanitation cannot be impeded by public health data collection. Therefore, each campaign must carefully consider not only the engineered approach but also the ethical framework to ensure the power obtained from wastewater monitoring is used as a public health tool and not an invasive weapon.

In order for stormwater control measures (SCMs) to achieve the required removal they must be sized properly. In many cases sizing involves literally choosing the physical size of the SCM. Sizing an SCM is complicated and there is no standard process. This makes it difficult for stormwater managers to know if the size they have chosen is appropriate. The effects of climate change further increase the uncertainty. The goal of this presentation is to provide stormwater managers with an overview of existing sizing methods so that they can be sure the method they are using is state of the art. It will also present recent thinking on adapting the process to improve resiliency. Stormwater control measures (SCMs) have two basic mechanisms: gravity settling and filtration. These two mechanisms operate differently but they are both less effective at higher flow rates. This means that detailed sizing depends on the specific product or practice but the general sizing process is the same regardless of the SCM. Sizing SCMs is fundamentally a three-part problem: 1.Determine how much rainfall needs to be treated, particularly the maximum expected intensity 2.Determine how much flow will be generated by the expected rainfall 3.Determine how much removal can be expected for the given flows In most cases at least one of these parts, and perhaps all of them, are a black box. Assuming the boxes are functioning properly, which seems to be the case most of the time, this has not necessarily created a problem for stormwater managers in the past. Now that rainfall is known to be changing it is a problem because an unknown process cannot be modified to account for future rainfall. A system sized for today will be undersized in a few years, well before the end of its service life. This presentation will crack the lid on all three boxes and at least partially illuminate them. A detailed discussion could fill a university course but a basic understanding can be achieved in 20 minutes. Different ways to model each aspect will be discussed, along with the strengths and weaknesses of the different options. How models can be adapted to create resilient infrastructure will then be discussed. Section 1: Rainfall will address design storms, using existing rainfall data from the National Oceanic and Atmospheric Association (NOAA) Precipitation Frequency Data (PFD) Server and, finally, modelling rainfall data. Since rainfall data is typically shown as a frequency distribution (see Figure 1) fitting it requires complex mathematics. The model will be based on the generalized extreme value (GEV) family of curves. The presentation will not get into the detailed mathematics but it will describe the thought process. It will also present a basic goodness of fit test, the chi square test. Section 2: Runoff will address the rational method and the probabilistic rational method. The probabilistic rational method has the runoff coefficient, C, as a function of intensity. There is no consensus yet on what this function should be so a few options will be discussed. Section 3: Removal will discuss available removal data, particularly that published by the New Jersey Department of Environmental Protection (NJDEP). The Critical Particle Size Theory (CPST) will be introduced as a way to estimate performance of a system for different particle size distributions (PSDs) based on data from the NJDEP PSD. An example of how to use CPST will be shown. Section 4: Resilience will discuss ways to adapt sizing models to account for recognized changes in rainfall will look at building resilience through the use of climate change models and through different interpretations of NOAA rainfall data. Again there is no consensus on a correct approach, indeed there may be no 'correct' approach, so the focus will be on possible options and their implications.

Introduction: An open channel is a concrete waterway that is widely used in many regions. Like other concrete structures, open channels suffer from many deficiencies, such as scour, cracking, spalling, and tilting. Inspections need to be performed on a regular basis aimed at identifying and rating deficiencies. Ratings represent the severities of a deficiency, which are often associated with descriptions and suggested actions. Table 1 shows an example of spall rating classification. Manually classifying deficiency ratings is often difficult, since it requires both expertise and extensive physical inspection. Therefore, automating deficiency rating work has been an industry challenge. Machine learning (ML) is a type of artificial intelligence (AI) that can learn from various data, identify patterns, and make decisions. In this study, we are interested in evaluating the power of ML on providing accurate rating classifications of channel deficiencies without human intervention. The developed ML model is described in Methodology and followed by preliminary Model Results and Conclusion. Methodology: Since the goal is to rate defects or deficiencies, a supervised ML model is selected. Specially, we train a convolutional neural network (CNN) on 80% of the total available data, then validate & test model results on the remaining 20%. For each deficiency, the total available data consists of thousands of pre-labeled deficiency photos. Table 2 lists the total available photos for each test deficiency. Figure 1 provides a proposed modelling flowchart. Convolutional neural network (CNN) is one of the most popular neural networks in computer vision. Compared with traditional neural networks, CNN consists of not only fully connected layers, but also convolutional layers and pooling layers. This structure allows CNN to utilize spatial pixel interaction information as well as reduce model complexity, which makes CNN especially suitable for image classification. The convolutional layer is used for parsing the input photo. Three brightness intensity values (red, green, and blue, or 'RGB' channels) are assigned to each pixel on a color photo. Figure 2 gives an illustrative example using a tree photo. After parsing a photo into its RGB channels, the convolutional layer employs several 'filters' that contain trainable weights to apply convolution operations on these channels. These filters move over the input layer until all pixels have been covered. The dimensions of input layer will be reduced after the convolution. A pooling layer typically follows a convolutional layer, which further decreases the input layer dimension. The pooling layer also summarizes the regional pixels information so that the model becomes robust against objective position variations. Figure 3 demonstrates a CNN example that is used to predict if a photo is a tree, streetlamp, or a stop sign. In this study, we further adopt a 'transfer learning' technique: A pre-trained CNN, ResNet-50, is used and followed by a trainable fully connected layer to yield deficiency rating predictions. Our model is developed based on open-source software libraries: TensorFlow and Keras frameworks. Model Results: Results are briefly discussed in this abstract. Figure 4 show both the loss and accuracy curves against 70 epochs for cracking as an example, with class weight considered in training. As the training proceeds, in general, the validation loss is decreasing and the validation accuracy is increasing before reaching a relative stable condition, which indicates the convergence of the model. Figure 5 plots the confusion matrix of cracking based on the cracking test data. There are three ratings for cracking (R1, R2, and R3). Each row represents the model prediction while each column is the true label. For example, there are 333 photos with the true R2 labels that are also predicted as R2. Based on the confusion matrix, the model accuracy, precision, and recall are calculated. In this study, we select accuracy and macro-averaged F1 score as two evaluation metrics. Accuracy is defined as the number of correct predictions divided by the total number of predictions, and it assumes that all the classes are equally important. Macro-averaged F1 score is a harmonic mean (tradeoff) between precision and recall, which is useful when the false negatives and false positives are essential. For some deficiencies, rating classes can be imbalanced, where one rating class only has several photos while another rating class has thousands of photos. In this case, F1 score is a preferred over accuracy since it accounts for the model ability to predict the minority class. One way to increase F1 score is to incorporate class weight into loss function, where class weight is the inverse data ratio among different rating classes. Table 3 shows the class weight information for each deficiency. Based on the class weights, Table 4 shows the test results for all four deficiencies, where 60%-70% accuracy can be generally achieved. The accuracy is generally lowered by 2% in exchange for 0.02 increase of F1 score, when comparing the no-class-weight model to the class-weight model. Due to the limited data (Table 2), tilting has the least accuracy performance. Also, because of the relatively balanced classes (Table 3), F1 score does not increase for tilting when transiting from the no-class-weight to the class-weight model. Conclusion: This abstract presents the method used to develop a machine learning model based on CNN, with the objective of assigning open-channel deficiency ratings. Four deficiencies were selected (cracking, spalling, tilting, and vegetation), and the preliminary results indicate a general 60%-70% accuracy and 0.4-0.5 F1 score. In general, the achieved accuracy performance is positively related to the number of training data. Adding class weights into the model can increase F1 score, if the deficiency rating classes are imbalanced. More discussions will be provided in the following paper.

Since the 1990s, the City of Portland, Maine has made significant strides in mitigating combined sewer overflow (CSO) volumes. The City's next important step is the creation of the 3.5 million-gallon (MG), off-line Back Cove South Storage Facility (BCSSF), which broke ground in July 2020. This facility is designed to capture the first flush of CSO from approximately 1,435 acres within the City, reducing the annual CSO volume at outfalls 016, 017, and 018 from 150 MG to 18 MG. These outfalls account for about half of the City's and about one quarter of Maine's annual CSO volume. To ensure the best return on its substantial investment in the BCSSF, the City opted to advance the project under a design-build contract that facilitates a collaborative approach between the City, the City's Owner Project Manager (OPM), and design-build team. The purpose of this presentation is to share information on the hydraulic design approach successfully applied and the challenges, considerations, findings, and lessons learned along the way. Advanced modeling, pairing 1-D collection system and storage models with 3-D computational fluid dynamics (CFD) models of key structures, informed the hydraulic design of a combined sewer overflow (CSO) control facility to fulfill regulatory, owner, and design-build delivery requirements. This approach instilled confidence in all project stakeholders that the hydraulic design addresses CSO control requirements while preserving the operation and service level of the existing collection system. The BCSSF concept design for this storage project began as a box conduit under a major thoroughfare and active business district. This idea evolved into installing a single, large tank below a public soccer field, which mitigated traffic and business impact, but posed its own logistical problems. The field's proximity to a tidal mudflat and elevated interstate highway created significant geotechnical and structural concerns. To address the differential settlement concerns born from the one large tank concept, the idea of four interconnected tanks designed to fill sequentially was proposed by the design-build team and accepted by the project partners. Additionally, installing the tanks in two sequential phases ensures the stability of the site and adjacent features during construction. Each phase consists of excavating an area 500-feet long by 75-feet wide by 30-feet deep, installing two cast-in-place tanks, and backfilling. This approach reduces the risk of rotational slope failure related to the elevated highway and allows the construction crews more space on the field to work without disrupting traffic or the nearby public trails. In addition to protecting the integrity of adjacent areas, the project team also had to address the fundamental challenge of capturing inflow from three separate, tidally-influenced CSOs. With a diurnal tidal range of 10 feet (greater during king tides and storm surge events) and the existing pipe elevations four to five feet below mean sea level, the system hydraulics dictated that the bases of the storage tanks would need to be at least 30 feet below ground surface or around 20 feet below sea level. The design team used a dynamic stormwater management model (SWMM) to account for the tidal cycles, interconnecting outfalls, backflow prevention, storage tank connections, as well as the losses imparted by diversion and access structures. This modeling helped confirm that the flow diversion and storage is passive at all tidal stages and that interactions and flow redistribution resulting from hydraulic connection of three CSO outfalls will not negatively impact the upstream collection system. The impact of independent connections between the four tanks was incorporated into the hydraulic model. Connection elevations were based on a cumulative distribution function of recent CSO events and were designed to minimize tank cleaning frequency without sacrificing the overall project goal of storage. Additionally, the team used state-of-the-art 3-D modelling methods to confirm that the hydraulic design of CSO diversion structures meets the City's CSO control requirements. This included computational fluid dynamics (CFD) modeling of diversion structures using FLOW-3D to understand internal flow regimes during typical year peak and extreme precipitation flows. CFD modeling results were used to quantify head losses associated with diversion structures independent of tidal stage. These results were used in conjunction with the system wide SWMM model to assess impacts to upstream collection systems and set design elevations for the storage facility. Once a design water surface elevation within the tanks of -6.50 feet was established, system performance was simulated with dynamic routing under steady peak design inflows to confirm design flows would be fully intercepted, even as tanks approach full storage capacity. System performance was also evaluated under unsteady flow conditions to account for interactions between upstream collection system volume and tidal stage during precipitation events. By pairing 1-D and 3-D modeling for analysis, the team arrived at a comprehensive design, instilling confidence in the proposed approach and final design. The 1-D and 3-D model analysis indicates that the CSO diversion structures impart reasonably low head loss, even at high design flows with surcharged pipes, comparable to a typical access manhole. The most dramatic hydraulic impact was created by the proposed replacement of rectangular tide gates with inline, elastomeric backflow preventers, which impart an order of magnitude greater head loss. In addition, connecting the three CSO outfalls shifted the flow balance between the outfalls during heavy precipitation events. Left unaddressed, this would negatively impact the system upstream in a densely developed area. This required additional design modifications downstream of one diversion structure to accommodate the redistribution of flows. The passive capture of CSO flows means water surface elevation within the tanks is controlled by the tide during heavy precipitation events. The BCSSF is the latest phase of the City's Long-Term Control Plan (LTCP), which has required extensive planning, collaboration, and detailed analysis. The completion of this project will provide dramatic and immediate improvements to the water quality of Back Cove and Casco Bay, which are vital to the identity and economy of the area. The hydraulic analysis and design for this project are complete. Experience gained through the hydraulic design of this off-line CSO storage system is highly transferable and will benefit those designing similar projects that impact the hydraulics within a CSO system.

Introduction The U.S. EPA estimates that water resource recovery facilities (WRRFs) emit nearly 40 million metric tons of carbon dioxide equivalent (CO2eq) greenhouse gas (GHG) each year, representing nearly 1% of all domestic emissions sources. Landfills, which are interlinked with WRRFs by residuals management especially for small to moderate WRRFs, represent an additional 1.5% of all U.S. GHG emissions. WRRFs and landfills may also represent the single largest sources of GHGs in municipalities that own and operate these systems. To mitigate concerns about the long-term economic and environmental sustainability of landfill disposal, WRRFs are investigating technologies that reduce the mass and volume of biosolids before end-use. Mass reduction, such as anaerobic digestion or thermal drying, is a strategy to lower hauling and disposal costs, which typically are the largest line items in a WRRF's biosolids management budget. Several moderately sized WRRFs (<10 million gallon per day [MGD]) are considering thermal drying systems that use heat to remove moisture from dewatered sludge and can represent a 70-80% decrease in the mass of material hauled. Though capitally intensive, the process can represent a significant reduction in operating costs due to the mass reduction and the higher quality biosolids product (Class A) produced. The process is especially economically attractive in areas where natural gas prices are low and biosolids are hauled long distances, such as Ohio. Widespread adoption of sludge drying can potentially impact the GHG footprint of WRRFs and the municipalities that own them. Increased use of natural gas will undoubtedly raise direct GHG emissions at the facilities. However, dried biosolids will require fewer trucks, reducing fossil fuel demands associated with truck traffic. Additionally, high quality biosolids have been shown to improve soil health upon land application and contribute to carbon sequestration. It is currently unclear what net impact sludge drying will have on GHG emissions. Quantification of these emissions is critical to better understand the environmental impacts of the technology. Study Objectives The goal of this study was to quantify impacts of sludge drying technology and anaerobic digestion on greenhouse gas emissions at WRRFs. The goal was met by completing the following objectives: - Develop a mass and energy balance model to quantify direct and indirect GHG emissions for sludge treatment and disposal at a moderate sized (<10MGD) WRRF. - Compare GHG emissions profiles for the following sludge treatment trains: 1.Sludge Dewatering with Landfilling of Undigested Sludge 2. Sludge Dewatering with Drying and Land Application of Class A biosolids 3. Sludge Thickening, Mesophilic Anaerobic Digestion, Digestate Dewatering, and Land Application of Class B Biosolids. Biogas combusted at combined heat and power (CHP) for renewable electricity and heat generation. 4. Sludge Thickening, Mesophilic Anaerobic Digestion, Digestate Dewatering, Drying, and Land Application of Class A Biosolids. Biogas combusted at CHP for renewable electricity and heat generation. Heat requirements not met by CHP fueled by Natural Gas. Scenario 1 was considered a baseline condition because it is a common procedure for small to moderate size biological nutrient removal (BNR) WRRFs in Western Ohio. Scenarios 2 through 4 are common treatment trains evaluated during biosolids master planning efforts at moderate size facilities. Methodology The mass and energy balance model (Microsoft Excel based) allows users to input facility sludge flow data and select common sludge handling unit operations such as sludge thickening, dewatering, digestion, drying, and others. Mass flows are resolved around the whole process and individual unit operations. Energy requirements (electricity and heat) are calculated based on typical parameters provided by equipment vendors. The baseline model was developed around a ~10 MGD BNR WRRF that does not include primary treatment and produces a waste activated sludge (WAS) flow of 100,000 gpd with 10,000 lb/d of total suspended solids (TSS). This treatment train is common to many small to moderate sized WRRFs in the state of Ohio. The boundary of the analysis only includes sludge treatment operations, residuals transportation (via diesel truck) and end-use (e.g., landfill, land application). Emissions for unit processes outside of the solids treatment and end-use boundary were not included (e.g. liquid train treatment). Direct GHG emissions were quantified by multiplying modeled utility consumption (kWh/yr; MMBTU/yr) by US EPA and USEIA emissions factors for the region of interest. Indirect GHG emissions were primarily attributed to the residuals end-use method. End use emissions were quantified using the Biosolids Emissions Assessment Model (BEAM) model version 1.1 from the Canadian Council of Ministers of the Environment (CCME). Total GHG emissions for a particular case were calculated as the sum of net direct (consumption - production) and indirect GHG emissions (residuals end use). Results and Discussion Figure 1 shows the impact of sludge treatment train and residuals end-use on GHG emissions. The results show that sludge dewatering and landfilling was associated with the most GHG emissions (>5,000 T CO2eq/yr), mostly from uncaptured methane emissions at landfills. The integration of sludge drying, and Class A land application reduced GHG emissions by nearly 80% compared to dewatering and landfilling. This is attributed primarily to limited methane release in farm fields (due to low moisture content coupled with aerobic oxidation) and somewhat to net negative emissions from Class A land application GHG emissions were lowest for Scenario 3 (anaerobic digestion, Class B land application option) because of the potential to recover renewable power and heat. In fact, more heat and power is produced than needed, resulting in negative emissions for Scenarios 3 and 4. Scenario 4 (anaerobic digestion with drying, Class A land application) was comparable to Scenario 2 (Sludge Dryer Only). Figure 1 clearly shows that technologies for mass and volume reduction are likely to reduce GHG emissions associated with sludge treatment and end-use. However, many WRRFs typically make technology decisions based on a cost-benefit analysis. Table 1 summarizes approximate capital expenditures and GHG emissions offsets compared to Scenario 1. The results show that Scenario 2 & Sludge Drying provides the greatest net reduction in GHG emissions normalized to spent capital. This indicates that sludge drying may provide a cost-effective means to improve the GHG emissions profile at small to moderately sized WRRFs. Conclusions and Future Work WRRFs require cost-effective and environmentally sustainable solutions for sludge treatment and end-use. The results from this work show that technologies for mass and volume reduction are likely to reduce GHG emissions associated with sludge handling. This modeling work showed that land application of Class A and Class B biosolids provides significant benefits including soil carbon sequestration and fertilizer offsets compared to landfilling. Sludge drying was shown to provide the most greenhouse gas emissions offsets per unit of capital expenditure, indicating the technology may be a cost-effective method to improve the environmental footprint of municipalities that own and operate small to moderate sized WRRFs. This is significant because sludge drying may become a technology to prepare for higher cost end-use outlets caused by emerging contaminant regulations (e.g. PFAS). Sludge drying is also a potential precursor process to PFAS destruction technologies such as high-temperature incineration, gasification, and pyrolysis. Future applications of this work include an evaluation of the GHG emissions profile of PFAS destruction technologies and more sustainable landfilling practices, such as enhanced methane capture for renewable natural gas (RNG).

Phase II of the Lower Meramec River System Improvements Project, also known as the Lower Meramec Tunnel (LMT), consists of a 6.8-mile-long, 14.5-foot excavated diameter, 78 to 286-foot-deep sanitary sewer tunnel. The project is located in south St. Louis County and traverses' portions of unincorporated St. Louis County, City of Sunset Hills and the City of Fenton. The LMT is part of Metropolitan St. Louis Sewer District's (MSD) Project Clear; a program planned to span 23 years to improve water quality throughout MSD's service area. The tunnel's main objective is to intercept flows and to take offline the interim Fenton Wastewater Treatment Facility (WWTF). This project is currently under construction and our presentation will discuss project details, including planning, detailed design, hydrogeologic challenges, use of hydraulically driven Milwaukee H4 vortex drop shafts, lessons learned from Phase I (Baumgartner Tunnel), procurement and the current status of construction. The project was originally envisioned in 1979 as part of regional treatment plan for pollution abatement within the Meramec River Basin. Previous investigations concluded that a regional concept involving a major interceptor sewer conveying flow to a single treatment facility that would discharge its effluent to the Mississippi River, was the most cost-effective scheme for the area. The Meramec River, one of the longest free-flowing waterways in Missouri, is widely used for recreational boating, fishing, canoeing and floating and is the central natural element for a series of parks located along the river's banks. Between 2005 and 2012, alternatives for expanding the Lower Meramec WWTF were evaluated through MSD's program management contract. This work included an alignment study for Phases II and III of the LMT project. In 2014, MSD awarded a design services contract to HDR Engineering, Inc. and, as a sub-consultant, WSP USA, Inc. who is serving as the lead design firm. The project received bids for construction on July 22, 2020. The tunnel will be constructed entirely in rock with an invert elevation of 255.1 feet NAVD88 where it connects with the Baumgartner Tunnel and at elevation 291.1 feet where it terminates near the Fenton WWTF. The proposed tunnel is anticipated to operate under both open channel and submerged flow conditions. Dry weather flow velocities of the Phase I and Phase II portions of the tunnel are anticipated to range from 2.5 feet per second. to 4.9 feet per second, which provides sufficient velocity between the minimum (2 feet per second) and maximum (10 feet per second) flow velocities as identified in the Recommended Standards for Wastewater Facilities for grit and solids suspension. Drop structures have been spaced along the alignment to accommodate as much gravity flow from MSD's collection system to the tunnel as practical and economical. Selection of the drop structure type has considered technical and functional criteria that influence the capital and life-cycle costs associated with constructing and operating the drop structures for the duration of their intended 100-year service life. Four types of drop structures were considered for the project, including: tangential vortex, vortex with helical ramps, plunge inlet and baffle type drop structures. Both plunge and tangential vortex drop structures were considered suitable. For locations where the design flow rate was expected to exceed 10 cubic feet per second, tangential vortex drop structures were recommended. Smaller plunge style drop structures were utilized elsewhere. During construction of the Baumgartner Tunnel (Phase I), which concluded in 2007 forethought was considered and the receiving shaft, the Baumgartner Shaft, was built to facilitate construction of LMT. The existing Baumgartner Shaft is located on MSD property at a formerly decommissioned sludge lagoon facility. The shaft is approximately 190 feet deep with the upper 130 feet constructed as a slurry wall which was keyed four feet into bedrock where supplemental grouting was performed. The lower 60 feet of the shaft was constructed through limestone bedrock. The shaft is currently unlined and is serving as LMT's tunnel boring machine (TBM) launch shaft. Up to 27 acres have been made available to the Contractor at the Baumgartner Shaft site to utilize as the contractor's primary work/staging area. Additionally, a unique reuse of a decommissioned lagoon located on the site will be used for muck disposal which greatly reduces the project's carbon footprint by eliminating haul traffic and disposal requirements. Three shafts will be provided near the Fenton WWTF, with the following key functions: - Accommodate tunnel construction for TBM retrieval and the ability to launch a TBM for the Grand Glaize Tunnel (Phase III), if required; - Intercept the Fenton WWTF flows via drop structure, deaeration chamber and connection adit to the LMT; and - Provide adequate venting at the upstream terminus of the LMT to mitigate potential surge and transient flow conditions. The Fenton Construction Shaft is located on property owned by MSD near the Fenton WWTF and the site is approximately eight acres. The shaft is anticipated to be approximately 136 feet deep with a depth to bedrock of approximately 63 feet. A slurry or secant pile wall will be constructed for initial support in overburden with supplemental grouting at the bedrock-soil interface. The site is located within the 100-year floodplain and significant flooding has been experienced, including recent historic flood events in December 2015 and May 2017. A portion of the site will be raised for flood protection and resiliency purposes above the recently revised 500-year flood elevation. Given that LMT is an extension of the Baumgartner Tunnel, design has taken an approach to focus on lessons learned from previous tunnel construction in similar geologic conditions. From the onset of the design, risk management has been implemented to mitigate known challenges as previously encountered, including risk mitigation as it relates to water-bearing zones within the rock formations; the presence of hydrogen sulfide and methane gas; and abrasive chert. The project has been delivered utilizing a traditional design-bid-build approach with contractor prequalification a part of the selection process. A comprehensive Geotechnical Data Report (GDR) and a Geotechnical Baseline Report (GBR) were prepared for the project to mitigate risk on behalf of the Owner.