Over the past five years, the demand for engineers has surged across public and private sectors. Yet, recent graduates and early-career engineers often favor private roles, overlooking the contributions of public sector engineering. In response, the South Platte Renew (SPR) Engineering Division initiated an intern program to bridge this gap and highlight the rewards of public sector work. The SPR Engineering Intern Program aims to broaden budding engineers' horizons, providing hands-on experience in real-world problems within the public sector. The program emphasizes the Owner's viewpoint, addressing fiscal responsibility, direct impacts on waterways, political drivers, and purpose-driven leadership. Crafted over three to four months, the internship allows students to explore operations, facility maintenance, construction inspection, project management, and the multifaceted nature of engineering roles. The methodology involves insights from former interns, workshops aligning needs, and strategic scheduling connected to SPR's Vision, Mission, and Values. The internship includes technical projects, communication-focused activities, and emphasizes professionalism. Feedback sessions and dialogues with recent graduates contribute to continuous improvement, ensuring the program meets interns' expectations. To boost interns' profiles, the program includes resume-building opportunities. This not only enhances immediate job prospects but empowers interns to navigate future careers successfully. Training sessions cover treatment, communications, safety, and construction practices, aligning with SPR's specific needs. The program's success is evident in tangible job placements within the water renewal sector, addressing the need for new talent as professionals retire. The growth in interns and partnerships with universities signify the program's positive reputation. The internship's strategic alignment with SPR's mission ensures lasting contributions. Interns engage in tasks beyond the internship, such as asset management data analysis, construction inspection, and sustainability analyses, aligning with SPR's long-term goals. In the broader context, the SPR Engineering Division's internship program serves as a model for integrating academia and industry, addressing the growing demand for engineering talent in the public sector. The program's evolution reflects adaptability, ensuring continuous improvement in shaping the next generation of engineers. Looking ahead, the SPR team aims to refine and expand the internship program. By fostering partnerships, enhancing the curriculum, and incorporating feedback, SPR aims to sustain the positive impact of its internship initiative. The program not only contributes to individual engineers' growth but plays a pivotal role in advancing SPR's mission and vision. The SPR Engineering Intern Program serves as a beacon for integrating academia and industry, a catalyst for developing future engineers, and a testament to the enduring value of public sector contributions in engineering.

Introduction Nashville Metro Water Services' (MWS) Central Water Reclamation Facility (WRF) has disinfected its treated plant effluent using gaseous chlorine since the facility was originally commissioned in 1958. Sixty-five years later, after 10+ years of planning, design, and construction, a new 350 MGD ultraviolet (UV) disinfection facility is online, and the last 90-ton rail cars were removed from the site. As of January 2024, the new UV facility has been operating as expected for six months, with E.coli values well within permit limits. The new UV facility is one of largest UV disinfection installation in the United States. Planning Driven by its Consent Decree, MWS commissioned the Central WRF Optimization Study (COPT Study) which recommended improvements to cost-effectively and reliably increase the peak wet weather capacity of its largest treatment facility from 220 MGD to 350 MGD via optimization; rather than by adding expensive new process tankage (Yarosz and Taylor, 2015). Figure 1 is an aerial photo of the Central WRF, which is located less than 2 miles from the heart of downtown Nashville. Since the Central WRF's existing gaseous chlorine disinfection system was unable to treat the large increase in capacity and MWS continued to have concerns with transporting, storing, and handling gaseous chemicals, MWS decided to evaluate alternative disinfection technologies as part of the COPT Study. The Central WRF also had two disinfection locations and desired to simplify operations by disinfecting optimized plant secondary effluent flows in a single location. A business case evaluation of multiple disinfection technologies was performed using both cost and non-cost considerations to determine the most beneficial long-term solution for MWS (BC, 2014). Capital costs, 15-year net present values (NPV) and 20-year NPVs were developed Non-cost factors include constructability, operability, reliability, safety, impact to traffic, and impact of potential future regulatory issues. UV disinfection was selected over sodium hypochlorite (bulk and onsite generation), peracetic acid (PAA), ozone. Table 1 includes the final results of this business case evaluation. Design of UV Facility Consistent with the project's goal to utilize existing structures, the design team determined it was feasible to construct the new UV disinfection facility within the footprint of the existing north chlorine contact tanks (CCT), which were designed to facilitate chlorine disinfection of 150 MGD. The following bullets briefly discuss some of the key design considerations. These and many other design considerations will be fully detailed in the full technical paper, if selected. The existing pile foundation of the CCTs was sufficient to support the new UV facility. The addition of concrete was offset by the reduction in water volume. The existing piles could also accommodate an enclosed pre-engineered metal building for shelter. CFD modeling was performed to confirm there was adequate mixing of north and south secondary effluent flows and determine a UV channel configuration that would not require flow straightening baffles as MWS has experienced algae issues with them at another WRF. Figure 2 shows output from the CFD model, which indicated that the flow split was within 2% of ideal at peak flow. There was limited headloss available to fit the UV facility into the Central WRFs hydraulic profile. Piping modifications upstream of the facility were required to reduce headloss. UV equipment O&M features were developed collaboratively in workshops with O&M staff where the engineers could listen, understand, and incorporate MWS' ideas and preferences into the design. The UV facility was designed around Trojan Technologies UVSigna(R) equipment because Trojan was able to propose multiple configurations that fit within the limited footprint of the existing chlorine contact tank structure, whereas several other leading UV manufacturers could not. Tables 2 and 3 include Design Flows and Permit Values and UV System Design Parameters, respectively. Additional discussion and supporting data related to the parameters in these tables will be included in the full technical paper, if selected. Construction Sequencing The UV facility layout and structural design had to facilitate construction sequencing that maintained plant effluent disinfection with flow routed through the structure throughout the duration of construction, except for several 2-to-5-day long shutdowns that generally occurred between different phases of construction. With the assistance of the Construction Manager at Risk (CMAR), a sequencing plan was developed in which the existing CCT structure was converted to the UV facility one half at a time. Figures 3 through 7 illustrate the sequence of construction, which was completed in approximately 3 years. Figures 8 is a photo from inside the UV facility. Status of Project/Significance of the Investigation All phases of this 10+ year long project are complete and the $35 million UV facility has been operating successfully for 6 months. This technical paper will include performance data, O&M experience, and 'if we could do it over again' insight from the Central WRF plant manager and the design engineer. Utilities, consultants, contractors, and others who are preparing to upgrade their water resource recovery facility (WRRF) disinfection systems can greatly benefit from this project's experience.

Introduction At WEFTEC 2019, data from one year of operation of a newly built sidestream fermenter for a biological phosphorus removal (BPR) system was presented. This paper covers the first 5 years of operation of the Wakarusa River wastewater treatment plant (WWTP) at Lawrence, Kansas. New processes are always scrutinized by the industry. Was the pilot operation a fluke? Can its performance be repeated? Is the system lightly loaded? Is the process resilient and reliable? Data from the last 5 years shows that sidestream fermentation is reliable, but there were periods of degraded performance. The Wakarusa River WWTP was designed to treat 2.5 mgd (9 500 m3 /d) annual average flow of domestic sewage. The Wakarusa facility is essentially a new train located at another site for the Kansas River WWTP. Flow to Wakarusa has averaged about 2 mgd over the 5-year period (80 percent of the design capacity). The Wakarusa Facility is a 3-stage Bardenpho process with a flow-through anaerobic zone, an anoxic zone, and an oxidation ditch for aerobic treatment plus a sidestream fermenter for enhanced biological phosphorus removal (EBPR). The raw influent to Wakarusa is fairly 'fresh' with a little VFA (12 mg/L) and a low rbCOD to TP ratio (50% of the time less than 13.5). Not enough rbCOD was available for good BPR performance. The Bad: Impact of Return Flows on EBPR Performance Figure 1 shows the effluent orthophosphate (OP) concentrations from an online analyzer, and effluent total phosphorus (TP) concentrations from operator collected data and 24-hour composites for 2019. This graph contains over 150,000 data points from the on-line analyzer. Figure 2 shows the 30,000 points spanning from Nov 2019 to Sept 2020 and it is much easier to see the periods of good effluent from the not so good effluent quality. The permit limit is 1 mg/L TP on a 365-day rolling average. The Figure 1 graph show periods, highlighted by the pink transparent boxes, of high effluent P coinciding with periods when biosolids land application was delayed by excessively wet fields. This pattern repeats each year. Solids build up in the plant MLSS (or system increased SRT) and the basin MLSS concentration rises significantly which interferes with sidestream fermentation efficiency. A process model was developed in SUMO (Dynamita) to simulate the plant performance at increasing SRT conditions. Model simulations indicated that the VFA production in the fermenter decreased as the SRT in the activated sludge basin increased while maintaining a constant flow to the fermenter. Model simulations are continued to further explore this phenomenon to determine if operational conditions can improve fermenter performance. In 2022 there was an upset between Sept and Nov in system performance. The centrifuges had been in operation for 4 years and erosion/ wear of internals resulted in poor solids capture. The net result was poor BPR performance in Sept through Nov of 2022, highlighted on Figure 1. Poor solids capture resulted in the recycling of high concentrations of BOD, TSS and TP to the plant influent (Figure 3). Once the centrifuges were repaired and solids capture was under control, the effluent OP and TP returned to very low concentrations. After 5 years of operation, no ferric chloride has been added nor has there been any supplemental addition of a carbon source. After the high inventory of MLSS was reduced, the fermenter bounced back and produced a very low effluent OP concentration. The Good: Impact of Low DO Operation on TN and TP Removal Performance and Microbial Ecology Figure 4 shows the nitrogen profile in the system during the summer of 2022. The abrupt decline in the effluent nitrate concentration was intentional. The facility has two online DO probes located in the outer curve and the inner curve of the ditch system. The DO setpoints were initially set at 0.8 mg/L and 0.5 mg/L during start-up and during the summer of 2022 plant staff lowered the DO setpoints to around 0.2-0.3 mg/L. Effluent nitrate concentrations dropped to below 1 mg N/L. The effluent phosphorus concentration remained very low (Figure 1). During the July — August 2022 timeframe, the effluent OP and TP concentrations remained very low. Near the end of this trial period, centrifuge performance began to deteriorate and excessive solids in the system interfered with good BPR. These results indicate that low DO operation did not have a negative impact on phosphorus uptake as well as nitrification. As the DO setpoints were lowered, the AOB (ammonia oxidizing bacteria) population declined and the population of Commamox increased. Recent studies demonstrated the prevalence of Comammox Nitrospira can be dominant ammonia oxidizers in a mainstream low DO nitrification reactor. The Good: Impact of Fermenter SRT on VFA Species and PAO/GAO Population A study performed by University of Kansas on fermenter SRT and operating parameters showed the impact of SRT on the quantity of VFA formed and the diversity of VFA species (Figure 5). Acetic acid is still the predominant VFA present in the fermenter effluent. Figure 6 shows the PAO versus GAO as a fraction of the overall microbial population in the anaerobic zone. Very few GAOs were present in the system. Summary The sidestream fermentation process has been reliable and consistent in producing a low effluent OP concentration while at plant loading of 80% of design capacity

A twin outfall relief sewer system for a major municipality is comprised of twin box structures approximately 11 LF in height and 10-12 LF in width, with average flows of 200-700 MGD. This sewer system is located below a military facility, making all inspections and repairs demand additional security considerations. During recent inspections of the twin outfall relief sewer system, CCTV footage showed areas of the sewer structure with extensive corrosion damage from microbial hydrogen sulfide (H2S). The damage caused by the H2S was so severe that the center wall between the twin box structures was missing for approximately 75 LF and much of the inner layer of reinforcement was also missing. The Owner's engineer performed structural analysis and determined the degraded portion of this structure was near collapse. Based on the as-found conditions and analysis performed, emergency remediation of approximately 910 LF of rectangular box structure was deemed necessary. The next step to minimize risk of collapse involved removal of the soil overburden in the region where the sewer system showed severe distress. The project team worked to develop a bypass system to reroute flows so permanent repairs could take place. Given the live flows within the structure, rehabilitation options needed to be selected prior to the bypass system being in place and the structure dewatered. This uncertainty regarding the condition of the structure required the repair system selected to be flexible to accommodate varying degrees of degradation. An innovative sewer rehabilitation technology was selected which involves installation of custom fabricated steel rings, HDPE interior protective layer, and a flowable grout to fill the space between the HDPE and the host structure. The design of the rehabilitation system can be adjusted based on as-found conditions, giving the project team the flexibility needed to move forward with repair design in parallel to installing the bypass and performing a more thorough condition assessment of the structure. This technology has a history of over 20 years of successful implementation in Japan with over 250,000 LF of successful pipeline repairs. This extended history along with extensive technical vetting allowed the project team to feel confident moving forward with a first-of-a-kind application in the United States. This paper will highlight the investigation, analysis, design, and emergent repair of this critical structure. Perspectives from the Owner, Engineer, and Contractor will be provided, along with insight on the options analysis process, and lessons learned throughout.

Introduction Alternative delivery methods in the water and wastewater market are proven to provide owners with value added and risk reducing approaches for executing capital projects. These delivery approaches are often associated with large utilities completing projects with hefty budgets. However, the same approaches can have equal, if not greater, advantages to small utilities providing resources for limited staff, minimizing design changes, and saving time and money. Objectives The primary objective of this case study is to investigate the benefits and challenges of alternative delivery implementation at two small wastewater utilities. The City of Fruita, Colorado (Fruita) conducted two construction manager at risk (CMAR) projects on their wastewater system in 2023 for a total construction budget of approximately $3.0M. The City of Laramie, Wyoming (Laramie) is currently conducting their first CMAR project for their wastewater utility. Both utilities struggle with similar issues complimentary of the CMAR approach: 1) Technically understaffed for wastewater capital project execution 2) Budgetary victims of ever climbing cost of work, 3) Location and project size limit contractor interest in open bid opportunities Status Fruita took a unique approach to alternative delivery. Located approximately four hours from any major metropolitan area, Fruita found it difficult to entice contractors to pursue projects delivered with a traditional design bid build (DBB) method. As such, Fruita selects an on-call CMAR firm every five years and issues work packages with negotiated guaranteed maximum prices (GMPs) to address their on-going capital improvements program. In 2023, Fruita conducted two CMAR work packages — replacement of their oxidation ditch aeration grids and collection system improvements to mitigate hydrogen sulfide (H2S) generation (H2S project). The on-call CMAR contractor commenced work with a pre-construction contract at, or around the 30% design level to provide value engineering, constructability review, cost estimating, and scheduling. Both projects included critical construction sequencing operations with significant cost ramifications. For example, the H2S project included significant bypass pumping associated with manhole replacement. The engineer, CMAR contractor, and Fruita collaborated early to determine exact manhole designs and construction sequence of operations to minimize bypass pumping time. The resulting construction was completed approximately 25% ahead of schedule and under the GMP. Cumulatively, Fruita was returned approximate $400k in deductive change orders from the CMAR contractor from the $3M GMPs. Laramie has traditionally delivered their capital projects in a DBB method — selecting the low price bidder without direct attention to qualifications. Like Fruita, Laramie is understaffed and has budgetary restrictions. Low bid DBB projects were found to be taxing the already overstretch engineering staff to their limits on ability to deliver projects on time and under budget. Laramie's first CMAR project is the West Laramie Main Lift Station Replacement with construction anticipated to begin in the summer of 2024. Originally budgeted for a mere $2.0M, Laramie realized the breadth of their project goals could not be accomplished with their budget. As such, the engineer, selected CMAR, and Laramie began the value engineering process early in the design phase to find options to meet Laramie's goals within an attainable budget. This started with a 'wants, needs, and must haves' workshop identifying scope elements to be included in the project. Considerations on phasing, alternate materials of construction, and facility location adjustments led the team to lock in on an overall design meeting Laramie's goals and budgetary restrictions. Findings and Significance Several key takeaways will be discussed for session attendees. 1) Partnerships between contractor, engineer, and owner are key. While alternative delivery is an excellent approach to delivering projects for small communities, effective working relationships are vital. A healthy balance of support and doubt between the engineer and contractor allow for best value approaches to emerge successfully. Similarly, owner trust in the design process allows for vetting of many options providing value. 2) Contractor and engineer experience in alternative delivery is vital to success of the project. Limited owner staff with limited alternative delivery experience requires more attention to the design and construction process from trusted engineering and contractor teammates. Ideally, engineer and contractor have past relationships (for CMAR delivery). 3) Begin GMP development early to mitigate late-stage design modifications. Regular cost model check-ins are helpful to make sure the project is keeping within budget. Laramie's pause and realignment happened following 30%, minimizing design changes and extra project cost.

Many jurisdictions across the US incentivize or require private developments to implement green infrastructure (GI) as part of their stormwater management. More recently, municipalities themselves are beginning to explore how GI can be integrated into public stormwater systems, and are seeking to understand the implications and benefits of GI in the context of their distributed, predominantly 'gray' subsurface stormwater assets. In communities where the 'low-hanging fruit' opportunities (such as integrating GI into public parks and other discrete open spaces) have been largely seized, the value of GI integration into the broader public streetscape is being recognized as a potentially significant source of further benefits. Advantages of utilizing GI include enhanced pollutant removal, reduction of stormwater runoff, climate resiliency, recreational and health benefits, and the provision of ecosystem services. The implementation of GI to achieve these outcomes for discrete project sites, be they public or private, is commonplace in many urban centers. However, there exist challenges to the effective implementation of GI practices more broadly throughout the network of stormwater collection and conveyance infrastructure that cities rely on to keep their streets functioning during significant rainfall events. These include concerns about space constraints, provision of appropriate pre-treatment, maintenance requirements, jurisdictional issues between municipal departments, treatment capacity and performance during large storms. The objective of this presentation is to provide the audience with a real-world example of a practical approach to fully integrating GI components within an urban stormwater system that addresses many of the challenges noted above. The case study at the center of this presentation is part of a roadway utility and stormwater system design (see Figure 1) that WSP developed and is overseeing the construction of in Boston MA. Construction of the design is partially complete, with the urban redevelopment project currently securing final permit approvals for the remaining phases of construction. Like many urban redevelopment sites, the case study project involved overcoming some site-specific challenges, such as a relatively high groundwater table (which can make infiltration challenging), and the desire to minimize excavation given the need to treat all in-situ material as potentially contaminated. Along with these considerations, the development of the GI-integrated stormwater design to service the proposed roadways focused on three principles: 1.Treat inflows early and don't rely on the subsurface infiltration capacity of the underlying soils; 2.Provide high-flow treatment and bypass capacity in a small footprint; and 3.Make maintenance simple! A key feature of the proposed design is that catch basins are eliminated from the new streets in favor of high-flow biofiltration cells (BFCs) which are supported by pretreatment inlets that screen out trash, debris and other coarse sediments and floatables. The BFCs were intentionally utilized as inlets so as to remove upwards of 90% of the sediment from runoff before it reaches the proposed subsurface infiltration trenches, enhancing and prolonging their functionality, and thereby minimizing maintenance and the potential need for future renewal. The treatment train proposed for the roadways achieves 98% total suspended solids (TSS) removal and 95% total phosphorous (TP) removal for a 1.25-inch 'first flush' rainfall event. This is a significant runoff water quality improvement compared to the 25% TSS and 0% TP removal typically credited to standard deep sump catch basins which are commonly the only form of treatment present in municipal stormwater systems (see schematic comparison in Figure 2). Utilizing the project case study, this presentation will provide a GI implementation template and lessons learned for integrating GI components into typical urban streetscapes with approaches that maximize benefits and minimize long-term maintenance costs.

Potable water reuse typically relies on treated wastewater from a conventional water resource recovery facility (WRRF) with further treatment through an advanced water treatment facility with chemical oxidation followed by membrane filtration. Conventional activated sludge (CAS) is used at WRRFs for bulk chemical oxygen demand (COD) and nutrient removal. Chemical oxidation and membrane filtration are employed to remove micropollutants and achieve additional pathogen inactivation. Although CAS is commonly used, it is not without challenges, such as sludge production, long detention times, susceptibility to treatment upsets, and lack of complete micropollutant removal2. In contrast, chemical oxidation can remove COD, making it suitable not only for advanced water treatment, but possibly for bulk COD removal as well1,3,5,6. It would be beneficial to evaluate the efficacy of replacing a sequence of CAS, chemical oxidation and membrane treatment with a simpler sequence of chemical oxidation (i.e., ozonation) followed by membrane treatment (i.e., reverse osmosis (RO)). This proposed system may achieve secondary treatment goals while also providing micropollutant removal and pathogen inactivation for potable reuse in a simpler process. However, no R&D reports were found that advance the proof-of-concept to eliminate CAS when chemical oxidation and membrane treatment are employed for municipal wastewater reuse. Currently, the scenario to eliminate CAS is at technology readiness level (TLR) 2 (concept and/or application formulated), whereas more work remains to move to TLR 3 (invention and research moving to proof of concept) and beyond4. In this study, bench-scale research was performed to prove the concept of ozonation followed by RO as a technology for municipal wastewater reuse (ozone-RO). Municipal wastewater primary effluent COD removal kinetics during ozonation were determined and compared to removal observed from CAS at a full-scale WRRF. Additionally, COD removal and nutrient fate and removal across ozone-RO were determined. Results were compared to COD and nutrient removal values achieved at a full-scale CAS followed by RO (CAS-RO). To determine ozonation COD removal kinetics, municipal primary effluent (PE) 24-h composite samples were collected from a WRRF (Fox River WRRF, Brookfield, WI). The CAS system fully nitrifies, with alum added to the secondary clarifiers for phosphorus removal. PE was ozonated in a 3-L batch ozone contactor at three different temperatures (7 degrees C, 22 degrees C and 34 degrees C). Ozonated gas was generated using a nozone generator (TG-10 Ozone Generator, Ozone Solutions, Hull, IA). A total applied ozone dose of 33 g O3/LWater over 3 h was used (45 g/m3 ozone gas with a 184 mg/L-min ozone application rate). To determine nutrient fate and removal, experiments were carried out using PE in the ozone contactor at 22 degrees C for 3 h. After ozonation, the water was sparged with nitrogen gas to remove residual ozone before a flat sheet RO membrane (FilmTec BW30XFRLE brackish water membrane) held in a cross-flow membrane cell (CF-106, Sterlitech). Pressure was held constant at 250 psi for 24 h. The RO process was then repeated with the same operating parameters but treating a 24-h composite sample of CAS effluent. COD, total and reactive phosphorus, total nitrogen, ammonia, nitrate, nitrite, and organic nitrogen concentrations were determined using commercial kits (Hach Company). Batch COD removal curves were fitted to the data using a first-order model with respect to COD concentration (Fig. 1) and the first-order rate constant (k) values were 0.0043 + 0.00037, 0.0046 + 0.00042, and 0.0067 + 0.0011 at 7 degrees C, 22 degrees C and 34 degrees C respectively. An ANNOVA test indicated that these k values were statistically different (p=0.0126). The resulting Arrhenius temperature coefficient value ( was 1.077. The CAS system had a 7-h average hydraulic residence time (HRT) before 1-hr secondary clarification compared to the ozone HRT of 3-h. Both COD and sCOD removal values with ozone and CAS were similar, and both treatment systems resulted in final effluent COD <5mg/L after RO treatment. Ozonation removed some phosphorus and converted some nonreactive phosphorus to reactive. It is hypothesized that phosphorus removal occurred by precipitation since a white precipitate was observed in the ozone contactor. Precipitation may have occurred due to a pH increased from 7.7 to 8.4 during ozone contact. Future experiments are planned to determine if this is the case. Final phosphorus and nitrogen concentrations from ozone-RO and CAS-RO systems were relatively low and similar. For example, total phosphorus concentrations for both effluents were below detection (<0.15 mg/L PO43--P) after RO. Although ozonation did not result in nitrogen removal, it did oxidize ammonia to nitrate (Fig, 4), which was subsequently removed by RO. This is significant since ammonia is not effectively removed by RO. No nitrite was detected (<0.6 mg/L NO2--N) in any samples. The concept of ozonation followed by membrane treatment was verified for municipal wastewater potable reuse and advanced from TLR 2 to TLR 3. Ozone rapidly oxidized PE COD under the conditions studied. In addition, quasi first-order kinetic constants and an Arrhenius temperature coefficient was established for ozonation of PE. Additionally, ozone-RO achieved final COD and nutrient concentrations similar to CAS-RO treatment. These data can inform system scale-up for R&D.

Silicon Valley Clean Water (SVCW), a water resource recovery agency in California, is nearly complete with its major infrastructure and conveyance upgrade program that used the progressive design-build (PDB) delivery for three interrelated projects valued at $569MM USD. This program, the Regional Environmental Sewer Conveyance Upgrade (RESCU), was implemented to replace SVCW's aging conveyance system and improve preliminary treatment facilities. Since 2016 when the program was initiated, SVCW has been an early adopter of PDB delivery for major wastewater infrastructure and has been focused on learning and sharing lessons learned to improve PDB delivery for the wastewater industry. This paper/presentation is intended to continue the sharing of lessons learned about PDB delivery for water/wastewater infrastructure projects throughout design, construction, startup and commissioning to better educate others who are considering and/or implementing PDB delivery for similar projects and programs. RESCU Overview: SVCW's RESCU program consists of numerous projects; however, the following three large CIP projects are at the heart of the program and account for over $569MM USD of construction cost:

*The Gravity Pipeline Project constructed a new gravity sewer pipeline [approximately 5,200 meters (17,000 linear feet) and 3.4-meter (11-foot) inside diameter], using a tunnel boring machine, that will serve as the main wastewater conveyance system to the treatment plant. Approximate project value is $264MM USD.

*The Front-of-Plant project constructed a new deep influent lift station [approximately 27.5-meter (90-feet) deep, 300,000 m3/d (80 mgd) capacity], located at the terminus of the Gravity Pipeline, and preliminary treatment facilities and connection piping to SVCW's main WRRF. Approximate project value is $169MM USD.

*The Pump Station Improvements Project is rehabilitating three of SVCW's conveyance pumping stations and portions of force main that contribute the flow to Gravity Pipeline. Approximate project value is $136MM USD. See Figure 1: RESCU Overview; Figure 2: Front-of-Plant. RESCU Program Timeline and Highlights: In 2016, SVCW began exploring PDB delivery as a viable approach for these three critical projects due to schedule extensions related to the overall program implementation approach. Like many other agencies, SVCW had to learn a lot about collaborative delivery prior to initiating these projects and talked with other agencies nationwide, attended Design-Build Institute of America (DBIA) conferences, and received guidance from Owner's Advisors. In 2017 through 2019, SVCW worked through a rigorous procurement process to select PDB teams for each of the three projects. The process included a Request-for-Qualifications (RFQ) stage, qualification interviews, reference checking, short-listing of selected firms, a Request-for-Proposals (RFP) stage, a proposal process, additional proposal interviews, confidential meetings and reference site visits to previous projects. From 2019 through present, the PDB teams have been working through individual project designs (BODR, 30%, 60%), final cost negotiation, and construction processes, but were coordinated as a program. Because the same PDB team was selected for both the FoP and PSI project, coordination was simpler between those projects. When the COVID pandemic began, SVCW had already implemented MS Teams for the RESCU Program and quickly to remote meetings with minimal delays. Early work packages were used to accelerate critical elements of work or equipment (such as the tunnel boring machine), which proved to be advantageous just before the pandemic began. As construction progressed through final completion, it became evident that startup of facilities with overlapping responsibility (e.g. Gravity Pipeline and Front-of-Plant) would require careful coordination between PDB teams, which is currently underway. Learning Objectives: The primary learning objectives for the paper are to educate attendees on the 'real life' implementation of PDB process, with particular emphasis on programs that include multiple interrelated projects. Because many agencies still have limited knowledge of collaborative delivery, it is important for our industry to share knowledge from those who have recently implemented this type of project delivery. Although some elements of the RESCU program were presented at WEFTEC 2019, those lessons shared were primarily about procurement and pre-design phases. Now that the program is nearly complete five years later, this paper will focus on lessons learned through the entire PDB process, with particular emphasis on the recent construction and close-out phases (2019-2024) that have not been described yet. Lessons learned will be broken into the following main categories:

*Procurement Process

*PDB team procurement and selection

*Co-location of teams

*Collaborative design processes

*Negotiating lump sum pricing and cost validations

*Benefit of early work packages for construction and critical equipment/material procurement

*Agency involvement during construction (submittals, etc.)

*Equipment selection and procurement using best value

*Design, construction and startup of projects with 'overlapping responsibility'

*Planning for outreach/permitting

*Equipment and/or design issues during startup

*Navigating the COVID pandemic/supply chain issues

Introduction The application of the AquaNereda® process, were aerobic granular sludge (AGS) is applied in a sequencing reactor, is often seen as a replacement for the conventional activated sludge process. AquaNereda(R) is a sequencing process that utilizes a single tank for react and settle phases, and therefore is often not compatible as a retrofit with existing activated sludge systems that utilize separate tanks for reaction (aeration basins) and settle (final clarifiers). While this can be seen as a limitation for the application of AquaNereda(R), there is an opportunity to construct an expansion of facilities with AquaNereda(R), and then integrate the AquaNereda(R) in parallel to a conventional activated sludge plant. Four Rivers Sanitation Authority (FRSA), located in Rockford, Illinois, is currently working towards this integrated overall facility. While maintaining 40 mgd of average day flow capacity in a more conventional biological nutrient removal (BNR) activated sludge facility, FRSA is adding an additional 10 mgd of average day flow capacity with a new AquaNereda(R) AGS facility. The AGS facility will be operational in 2025, with the BNR upgrades being completed in 2026. During design of the new facilities at FRSA, the largest question for integration of the processes became how to manage the waste activated granular sludge (WAGS). Given the characteristics of WAGS in terms of percent solids as well as the sequencing wasting schedule from AquaNereda(R), it was decided to send the WAGS into the activated sludge system and then to waste to solids handling (see Figure 1 for a process flow diagram). The waste activated sludge (WAS) would then contain flocs from the activated sludge process as well as WAGS. This simplified operation, but there were major questions related to the impact of WAGS on the activated sludge process. Potential oxygen demand impacts, nitrification rates, and settling rates were all of interest to FRSA to understand the impact of WAGS. While most facilities would rely solely on process modelling to assess these impacts, FRSA has access to WAGS for testing. The AquaNereda(R) demonstration facility is on site and operating with FRSA wastewater. This facility (treating 200,000 gpd) generates WAGS that can be utilized for testing. Approach and Methodology To help understand the impacts and strategies to manage WAGS from the AGS facility, a series of bench scale tests were completed using WAGS from the AquaNereda(R) demonstration facility and WAS from the existing FRSA aeration basins. Three sets of bench scale tests were completed:

*Settling rate testing to identify potential enhanced settling, as outlined by Daigger, Redmond, and Downing (2017)

*Specific oxygen uptake rate (SOUR) measurement, utilizing standard methods, to assess the oxygen demand of the WAGS. The WAGS have the potential to exert a significant oxygen demand, as past work has shown a biomethane production potential of WAGS that is similar to primary sludge (Guo et al., Digestibility of waste aerobic granular sludge from a full-scale municipal wastewater treatment system, 2020).

*Nitrification rate testing, as outlined by Melcer et al (2003), to identify any potential seeding effect from WAGS. Results and Outcomes To evaluate the effect of WAGS on the settling characteristics of the existing waste activated sludge (WAS), batch settling experiments were performed using WAS and a mixture of WAGS-WAS at various dilution ratios to generate settling curves. The WAGS-WAS mixture proportions were calculated based on the predicted WAGS flows from the new AGS facilities. Figure 2 provides the settling rate impacts. Addition of WAGS increased the settling rate of the activated sludge biomass. The effect on settling rate would increase the peak flow capacity of the activated sludge facilities from 110 mgd to 130 mgd. SOUR testing indicated that the WAGS would have a 25% higher oxygen uptake rate than WAS (Figure 3). This indicates that there will be an oxygen demand associated with either particulate COD bound in the WAGS or potentially stored carbon. This oxygen demand is considered during aeration operation in the activated sludge system. The nitrification rate of WAGS (4 mgN/gVSS-hr) was similar to the nitrification rate of WAS (3.9 mgN/gVSS-hr). This was an unexpected result, as the WAGS likely contains a high VSS content of particulate COD from the influent. The benefit is that the WAGS will be adding a significant load of nitrifiers into the activated sludge system, increasing system resilience. The outcomes from this testing highlight how construction of an AquaNereda(R) facility in parallel to an activated sludge facility can provide a net benefit to the activated sludge facility. Applicability AquaNereda(R) has been sold as the evolution of activated sludge, but the requirement for a sequencing reactor can been seen as a limitation. The work completed highlights how an AquaNereda(R) process can be constructed in parallel to an activated sludge system, with positive impacts on the activated sludge facility. Audience Appeal Anyone looking at process expansion, nutrient removal requirements, and aging infrastructure would benefit from this presentation.

Background: KC Water is Kansas City, Missouri's Water Services Department, serving over 650,000 residents. KC Water contracted with a firm to lead communications and business engagement for a major water, sewer, and storm sewer upgrades project - spanning nearly four miles along a heavily traveled corridor in the heart of Kansas City, MO (KCMO). This project caused daily disruptions to over 200 businesses, more than a dozen neighborhood groups, drivers, residents and the general public. The consultant branded the project Upgrades on Main. The Upgrades on Main project replaced century-old infrastructure and paved the way for the first phase of construction-related activity for the KC Streetcar Main Street Extension. KC Water replaced approximately 23,227 linear feet of water mains and 17,532 linear feet of sewer mains, installed 67 new fire hydrants, 70 new manholes and new water services for 135 locations. This project took over two years to complete, with construction taking place on a highly-trafficked corridor. The team proposed and executed a very proactive approach, focusing on 'early and often' communications with more than 200 businesses and residents along the corridor. Planning: We determined three primary goals for this project: Inform the public/stakeholders of construction impacts and educate them about the project process from beginning to end. Manage expectations and mitigate issues raised by the public/stakeholders. Provide a high level of customer service to stakeholders along the Main Street corridor. Our team then created 11 primary strategies to meet our goals. Each strategy included an objective that detailed how we would get the work done. Implementation: The team performed the following tasks throughout the two-year project to ensure the public was as informed as possible about construction in their area: 48-hour notice for any water shut offs via calls, emails and door hangers. Met on-site directly with stakeholders with contractors to coordinate phasing of work, delivery schedules, garbage truck schedules, etc. to limit the impact as much as possible. Created and sent detour maps emailed directly to impacted stakeholders that could be forwarded to customers/residents. Created 'Businesses Open During Construction' signage that was placed throughout the project corridor in order to support businesses during the construction period. Facilitated a 'bus tour' halfway through the project for city officials, business owners, and other key stakeholders to share the 'behind the scenes' aspects of the project and communicate the high-level of coordination taking place Captured drone footage to create photos and videos showing what progress had been made across the corridor. Managed a project hotline phone & email that was a direct line for the public to our project team. The consultant maintained a list of all foreman working across the corridor so when an issue did pop up, we were able to offer a high-level of service and fix the issue quickly. Attended weekly calls with all contractors working on the corridor Handled media requests, including meeting media on the corridor Launched a 'Drive Safe on Main' campaign - videos, graphics and social media campaign encouraging drivers to slow down on Main by highlighting some of the workers who are constructing the new infrastructure Created and maintained an interactive map Created progress graphics Regularly attended community/business/neighborhood meetings to provide updates on the project and answer questions. Planned a 'Community-Completion Event ' that celebrated the end of work with family-friendly activities and a short program featuring the Mayor, City Manager, city council members, KC Water and local business leaders.Through sponsorships P+A raised over $8,500 for the event to: Purchase $2,000 in gift cards from local businesses along the corridor Provide food and drinks from local businesses along the corridor Book activities and games such as a dunk tank, face painter and bubble artist Create signage showing all of the successes Go door to door to every business on Main Street to personally hand out invitations Evaluation: While there were still frustrations that come with the nature of construction, qualitative findings indicate that those impacted were pleased with the level and quality of communications provided throughout Upgrades on Main The Weekly Construction Update email list started at zero and by the project conclusion grew to 693 subscribers The team produced 92 Weekly Construction email updates with an average open rate of 45 percent (23 percent higher than the average email open rate for construction industries according to MailChimp) Team facilitated 15 media interviews throughout the life of the project Tehosted three virtual public meetings, totaling 124 attendees Team presented project progress/updates to 18 different neighborhood/business groups - some groups more than once Staff attended 95 weeks of a weekly coordination call with as many as 20 different contractors throughout the life of the project The team coordinated at least 40 different water shut-offs with business owners and residents (including phone calls, emails, and door hangers for each individual shut) An estimated 80-100 community people attend our community-completion event. The mayor of KCMO, city manager, and 2 City Council representatives attended the event and made remarks.

BACKGROUND Recently, every industry has been striving to enhance their carbon management strategies, and the wastewater sector is no different. The pressing need for effective carbon and nutrient management plus compliance with stringent regulatory limits has prompted the need to explore innovative and intensified processes [1]. Anammox is a cost-effective and efficient microbial process that offers a shortcut for nitrogen removal in the nitrogen cycle. When combined with partial nitrification, the PNA process has the potential to achieve complete autotrophic nitrogen removal [2]. PNA has been considered to be an effective and cost saving alternative to conventional biological nitrogen removal, for the treatment of ammonia-rich wastewater [3]. Despite being introduced as an innovative method for nitrogen removal, PNA is not widely used for full-scale mainstream treatment. The primary challenges in applying PNA to mainstream treatment are associated with the unstable selection of nitrite oxidizing bacteria (NOB), mutual inhibition, and competition for the substrates involved in the combined processes [4]. With significant PNA engineering challenges, hindering large-scale mainstream application, the newly developed partial-denitrification (PD) process presents a more promising solution, offering emerging opportunities for a more flexible anammox-based operation [5]. Even with ongoing research, the underlying principles of nitrite accumulation remain incompletely understood and there is still a lack of insight on the mechanisms involved in the nitrite accumulation process. Based on a recent review article by [8], it was determined that nitrite accumulation in denitrification processes can occur through various mechanisms, including ecology shift, carbon type, feast and famine, etc. This study presents a comprehensive approach to assessing nitrite accumulation, taking into account factors such as microbial ecological shifts, alternative carbon sources, feast-famine and carbon internalization, and the effects of COD/N in kinetics. METHODOLOGY The study was carried out using a 10-liter bench-scale Sequential Batch Reactor (SBR) at Toronto Metropolitan University, with operational conditions based on prior batch testing results. The lab-scale SBR aimed to determine the denitrifying kinetics of the biomass, utilizing primary effluent from the Ashbridges Bay Wastewater Treatment Plant in Toronto as the primary carbon source. Batch tests were conducted during the acclimatization period and after full acclimation to assess denitrification rates and kinetics. Additionally, Nitrate/nitrite Utilization Rate (NUR) tests were performed in-situ at low and high F/M ratios. RESULTS The initial carbon used for the partial denitrification assessment was acetate, and the Figure 1-A depicts the peaks of nitrite accumulation over a 57-day period of reactor acclimatization. Batch activity tests were conducted every five to seven days, revealing a noticeable shift in the occurrence of nitrite peaks. During the first 30 days, nitrite peaks were observed 30-60 minutes after test initiation, but after this period, a distinct shift occurred, with most peaks occurring 10-15 minutes after commencement, suggesting potential microbial transformation. Additionally, a correlation was observed in tests conducted after 30 days between the nitrite peak level and the COD/N ratio, although not clearly depicted in the figure. Furthermore, during literature review, studies were found mentioning the significance of specific partial denitrifying microorganisms, which only reduce nitrate to nitrite. The data presented contradicts the theory of the absence of nitrite reductase in some bacterial populations, as nearly all tests resulted in complete nitrite depletion by the end of the test. A similar trend to acetate was observed during the acclimatization with methanol as the second carbon source (Figure 1-B). During the initial methanol-based test, an intriguing observation was made: a nitrite accumulation peak was detected in the system, albeit lower, and it took approximately 60-75 minutes to appear. Given the absence of methylotrophs in the system, efforts are underway to comprehend the reason behind this peak. It is theorized that the available internalized carbon within the system might have been the source of this peak occurrence. One of the key observations made during these tests was the correlation between COD/N and the level of nitrite accumulation, which is considered very important and interesting for practical applications of PD. As depicted in Figure 2, the initial peak within the range of 1.5-2.5 may potentially be attributed to a shortage of electron donors, leading to an imbalance in the system's redox potential. A decline around 4.5-5 was noted, which corresponds well with the stoichiometric demand for complete denitrification. Once again, a peak within the range of 7.5-9 was indicated, suggesting an excessive amount of carbon beyond the half saturation coefficient (ks), creating an imbalance. These observations are considered very important and interesting for practical applications of PD. CONCLUSION This study aims to bridge the existing knowledge gap by elucidating the operational factors that significantly impact the stability and performance of the PD process. The findings will contribute to the development of efficient operational strategies for mainstream PDNA systems.

Introduction: Ultraviolet LED technologies have progressed to the point where full-scale implementation is now on the horizon. The work outlined in this study is part of WRF project 5173 which investigates the feasibility of UV LEDs at different magnitudes of flow and water qualities. A 280nm, 100 GPM, closed-channel UV LED unit was installed in a wastewater facility in Nova Scotia, Canada to compare to a conventional open-channel UV disinfection system. This project represents the first ever installation of UV LEDs for wastewater disinfection at this scale and provides foundational data for understanding how UV LEDs scale as a technology. In addition, the practical experience gained during the installation process of this technology is valuable to consultants and utilities who may be considering the use of UV LEDs in the future. Project Background: Data was collected over a 4-month period before the installation of the full-scale UV LED system using the UV auditing approach. The UV auditing approach has been developed by Dalhousie University and provides an understanding of the delivered fluence for full-scale UV disinfection by leveraging bench-scale inactivation curves (Rauch et al., 2022). This approach has successfully demonstrated that UV LEDs can outperform conventional, mercury-based 254nm disinfection for some wastewater matrices (MacIsaac et al., 2023). UV auditing is also useful for utilities in understanding how LEDs will perform when considering mercury-free disinfection technologies. The LED reactor used for this work (shown in Figure 1) was manufactured by AquiSense Technologies and is a closed channel design with a 100 gallon per minute (GPM) capacity and was conducted over the Fall of 2023. The flow capacity of the LED unit represents approximately 10% of the average daily flow of the wastewater facility that it has been installed at. This installation marks the largest commissioning of a UV LED wastewater disinfection reactor anywhere in the world. Pre-installation data is shown in Figure 2 and was collected during the Summer of 2023. The average UV transmittance measured at the facility during this sampling period was 53% with an average power consumption of 35 KW. The disinfection results indicate that 280nm UV LEDs performed comparably to conventional 254nm low-pressure system and can provide sufficient pathogen inactivation when used at the full-scale. Additional Project Phases: The second phase of this work involves stress testing the UV LED reactor to define the range of performance in terms of power output, flow rate and UV transmittance. This work was conducted over a 4-week period in early 2024 and involved operating the reactor at a flow rate of 100 and 200 GPM, as well as power outputs ranging from 50-100%, and variable UVT during the sampling period. The final phase of this work involves the comparison between the UV LED reactor with the conventional, open channel, low-pressure UV system that is already installed at the facility. This work covers a 6-month period with twice weekly sampling of the inlet and outlet of both treatment trains. A scale analysis concludes this work by collecting samples of internal surfaces at the end of the six-month sampling period. This work identifies the differences in fouling mechanisms between each of the UV light sources. UV LEDs do not generate heat on the emitting side of the light source and therefore, are not expected to form inorganic scales in the same way that conventional mercury lamps do. This work provides foundational information for both consultants and utilities when considering approaches for testing the feasibility of using UV LEDs in wastewater facilities. UV LEDs have shown to be comparable in performance to conventional systems while avoiding several of the environmental, human health, and safety issues related to mercury-based UV disinfection. In closing, the tasks conducted in this work help achieve the goals in understanding UV LED implementation as defined in WRF 5173.