WCW24

More stringent effluent requirements for BOD, TSS, ammonia and phosphorus are being mandated at lagoon facilities across Canada. Add in a cold climate that adversely affects winter treatment performance, and many lagoons struggle to stay in compliance with their current permit or meet the challenges of new regulations. Lemna Environmental Technologies (LET) will present an updated approach for lagoon based wastewater treatment including a brief comparison of past design standards with current methods, an overview of lagoon technologies used for advanced treatment including nutrient removal, and in-depth review of several cold weather case studies demonstrating how lagoons are being successfully updated in order to meet the challenges of present and future effluent requirements. Using wastewater treatment process design modeling software, which models biological, chemical, and physical treatment processes, LET has optimized the design, performance and reliability of lagoon based treatment systems. Using historical DMR data from an installation base of over 500 facilities, LET created a unique software model of its LemTec Biological Treatment Process, which utilizes a combination of aerated and settling lagoon cells for biochemical oxygen demand (BOD) and total suspended solids (TSS) removal, and the Lemna Polishing Reactor (LPR) for nitrification. The model enables LET to consider the effects of non-steady state factors such as peak flows, constituent loading, and ambient air and water temperatures on treatment performance, improving upon traditional steady state wastewater treatment process design methodology. The discussion will provide data and specific case studies demonstrating the predicted performance vs. actual data, using the calibrated model. Regional case studies will be used to demonstrate the benefits of modeling practices for lagoon design.

While popular as a source of renewable energy, traditional Anaerobic Digestion (AD) processes can create undesirable challenges at WWRFs. These problems increase chemical and energy costs and create many operational challenges. By adding an Acid Digester before and an Aerobic Reactor after AD, some significant improvements in plant, digester and dewatering performance can be realized. These proven processes are well-established but, when they are used in concert with an innovative recycle loop, the solids process is enhanced in many ways while providing nutrient control to benefit the liquid stream. The denitrification step inhibits H2S and Struvite Production and produces more and cleaner gas, reduces odor and ensures robust digester performance. This can be accomplished without addition of FeCl, adding further savings and optimization.

Situated in Northern Manitoba, Barren Lands First Nation (BLFN) is home to approximately 520 people. The First Nation initially operated a two-cell facultative lagoon to treat wastewater from both Barren Lands First Nation and the neighbouring community of Brochet. The lagoon was initially constructed in 2006 and although plenty of capacity remained, the lagoon was in need of several major repairs. The liner had floated in multiple locations forming pockets of gas which breached the surface of the lagoon. Adding to that, the berm had also collapsed in several locations and previous attempts to repair only achieved moderate levels of improvement. The First Nation's confidence in the lagoon had waned and a new aerated lagoon was selected as a replacement. Stantec Consulting Ltd. was retained to provide design and engineering services for a new sewage lagoon, lift station upgrades, along with repairs and upgrades to the existing sewage collection system. Several of the lift stations were experiencing operational issues which causes upstream manholes to overflow at times. All 5 of the existing lift stations received new pumps while three lift stations needed control system upgrades. A forcemain flushing and CCTV camera program was included to clean the forcemain and locate areas in need of repair. With a goal of simplicity and ease of operation, a new HDPE lined two-cell aerated lagoon using high efficiency fine bubble diffusers was selected for its smaller footprint versus a facultative lagoon. Following the lagoon and two cell Submerged Attached Growth Reactor was designed to provide nitrification for removal of ammonia. The new lagoon cells were constructed with self-draining under drains and vent pipes, which combined with a layer of sand covering the HDPE liner will prevent the liner from floating. The second lagoon cell was designed to be 1.4m lower than the first cell following the profile of bedrock encountered onsite and allowing the entire system to be designed to flow by gravity through all stages before discharge into the nearby lake.

Fats, Oil and Grease (FOG) is the number one cause of blockage in the City of Calgary wastewater system. It is estimated that about half is contributed by Food Services Establishments (FSE), despite this category accounting for only two to three per cent of Industrial, Commercial, and Institutional (ICI) customers. Currently, Calgary has more than 7000 FSE's. To protect the wastewater system from FOG buildup and blockages, the City Wastewater Bylaw 14M2012 has specific regulations for FSEs, with requirements for proper installation, regular maintenance and record keeping of their pre-treatment systems, mainly grease interceptors. Starting in 2012, a pilot project with 144 FSEs was conducted, with the intention to develop a FOG compliance program, FSE inspections tools and to determine if the Wastewater Bylaw requirements related to grease interceptors were being complied with by these customers. Later a FOG education campaign was launched which included creating a slogan (Stop and Think! Not down the Sink!), educational material (posters, stickers, BMPs and handouts) and a FOG program video as well as updating the FOG program landing webpages. In January 2022, The City initiated a customer education-first approach using Water Educators. Educators audited more than 7000 FSE's sites with the objectives to educate customers on FOG onsite management practices using educational materials developed during the FOG campaign and to determine the state of compliance and the level of risk associated with each FSE. Following the audit each business was categorized by risk for further enforcement or follow up from the compliance team. So far, this approach is working very effectively, within a short two year's period, the compliance team was able to work with the businesses to install XX new grease interceptors, which are estimated to prevent more than 170,000 lbs/year of FOG from entering the city wastewater system. Success and challenges experienced throughout the FOG program journey and statistical outcome as well as our next steps for achieving sustainability of the program will be presented.

A major current industry challenge is critical aging infrastructure being put under increasing pressure from growth through densification and catchment expansion, whilst also being asked to provide more for less with respect to capital and operational expenditure, without compromising mitigation of environmental and social impacts. This context creates unique and complex engineering problems like those presented on the Port Coquitlam Pump Station project. The pump station is the single point of collection and outlet for the City of Port Coquitlam with a catchment of 30 km2, a population of over 60,000, and bordered by federally protected salmonid and other fish bearing rivers. The station was constructed in 1976 along with the original forcemain, with a second larger forcemain built 30 years ago. The forcemains have significantly different hydraulic characteristics and profiles, including size, material, intermediate high points, and inverted siphon sections. Both forcemains discharge to an interceptor that experiences varying degrees of surcharge. The required capacity upgrade to address the projected growth exceeds the design of the current system, and as such the combination of these conditions lead to exceptionally complex system hydraulics. Jacobs was engaged to complete the engineering analysis and design for the system upgrade, whereby a combination of the existing forcemains are required to be used to obtain the necessary hydraulic capacity as the pipelines pass through sensitive environments and impacts must be limited. This task was further complicated as the original forcemain had been condemned due to poor condition and associated failures. Jacobs approached the problem incrementally: investigating and recommending specific rehabilitation for the original forcemain, completing field data sampling to establish the actual hydraulic characteristics of elements, hydraulic modelling to validate the field data and enable it to be extrapolated for the entire system, and complex holistic system hydraulics to determine possible system capacities under the wide range of operational and hydraulic scenarios. The complex hydraulics were key to understanding the problem and the solution. Analysis was completed via multiple methods to establish the steady-state upper and lower bound hydraulic conditions, the hydraulic envelope, and identifying hydraulic control points and transition regions. These envelopes and transition zones confirmed how the system could operate so the design could be completed to optimize system performance and assess how the system would respond under unplanned events such as hydraulic transients during a station power failure and what mitigation measures should be incorporated. This paper will present the engineering analysis completed by Jacobs with focus on the development and solution of the complex hydraulic evaluations associated with existing aging infrastructure. The analysis enabled Jacobs to select new pumps, design station upgrades and reliably recommend a system solution that provided exceeded the required capacity increase for the specified design horizon, but also future proofed the system for future capacity increases. This solution provided the optimal long-term solution considering capital and operational cost, adaptability for future changes and longevity of infrastructure, and mitigated environmental and social impacts, which is needed to address our industries aging infrastructure in the current climate.

This project replaced a failing system to ensure the safe, daily conveyance of over 2.3 million litres of wastewater across the Red River in Winnipeg. The existing crossing was installed along the river bottom in 1978 and was connected to lands that became densely urbanized limiting replacement solutions. An alternate solution was developed to both reroute the force main and install it safely within the bedrock strata below the river. The solution required 780 metres of new force main including a 466-metre-long river crossing installed using horizontal direction drilling. The selected alignment considered several environmental, infrastructure and social issues and included both horizontal and vertical curves (a first for Manitoba). The project was commissioned safely, and the crossing is now effectively supporting the wastewater flows across the Red River in Winnipeg.

The purpose of this presentation is to clearly answer the question “Do I Need Grit Removal?” This will be accomplished in a straightforward, easy to understand manner with references to widely known and commonly used literature in the wastewater industry. The information presented will be backed up with clear and simple photos which put the values into real and tangible sizes which we are all familiar with. Grit in wastewater is often thought of as a necessary evil as it settles throughout the treatment plant. Cleaning of grit-laden basins and repair of rotating equipment due to grit wear are commonly seen as routine maintenance. As wastewater technology progresses and the processes used to treat wastewater become more complex, the need for grit removal will increase to protect these processes. This presentation will also outline the cost of such grit related maintenance items so the attendee can clearly understand the true cost of grit in their plant and decide if grit removal will save enough money in repairs to offset the initial purchase and installation costs of a grit removal system. However, we acknowledge that every plant is different and as such, the amount of grit related maintenance varies widely. It is not every plant which has the need for grit removal because some can simply store it in their lagoons or dispose of it in their sludge. This presentation is intended to help each plant engineer, owner, or operator know what information they need to gather so they can decide for themselves if their plant has reached the point of needing grit removal.

Gold Bar Wastewater Treatment Plant (GBWWTP) operated by EPCOR in Edmonton, Alberta has a limited footprint for expansion. To meet the treatment demand for population growth and regulatory requirement in the future, EPCOR strives to improve the treatment efficiency by intensifying the existing process. One of those efforts was to improve the settling performance by improving the hydraulic condition of secondary clarifiers. The purpose of this presentation is to share some of the experiences learned from this journey with others. The GBWWTP currently has 11 biological nutrient removal (BNR) bioreactors, each followed by a rectangular secondary clarifier. Mixed liquor from each BNR bioreactor is distributed to its secondary clarifier via a mixed liquor channel (MLC) through 10 distribution ports. Each secondary train is designed for a maximum flow of 42 million liters/day (MLD) and average of 28 MLD. In 2018, a dye test was completed in selected secondary clarifiers. During the test it was noticed that dye added at the end of the bioreactor was almost immediately visible in one front corner of the secondary clarifier. It was concluded that the MLC was not evenly distributing the mixed liquor into the secondary clarifier and density currents were causing short circuiting within the clarifier. In 2019, further field testing was completed to better understand flow patterns in the clarifier. Multiple measurements were taken using a portable flowmeter at each MLC distribution port into the clarifier, at both 28 and 42 MLD. The results confirmed the short circuiting when the mixed liquor was distributed to the secondary clarifiers. The amount of mixed liquor distributed through the distribution ports of the MLC varied from -8 to 248% of the average. In 2020, baffles were designed and installed based on computer fluid dynamic (CFD) modelling of the MLC and two full-width baffles were installed in the clarifier. Access and maintainability were strong drivers in the design. Baffles were hinged or removable to allow access, materials were chosen to reduce maintenance, and spacing was designed to reduce solids build-up With the MLC baffles, modelling predicted the amount of mixed liquor distributed through each distribution port in the range of 90% to 107% of the average flow. To validate the actual effects of the baffles, additional dye testing and field measurements were performed in 2023. In general, the dye test indicated that the baffles provided a 20% improvement on overall hydraulic retention time in secondary clarifiers. The field flow measurements showed that the MLC baffles significantly improved the distribution of mixed liquor to secondary clarifiers. The amount of mixed liquor through each distribution port is about 69% to 180% of the average flow, which presents a significant improvement and provides validation of the CFD model. Although baffles are a relatively simple means of improving clarifier hydraulics, this study took a systematic approach in design and validation of in-tank and MLC baffles. Unique challenges were experienced throughout this study, especially during performance validation, and learnings from these challenges could be helpful for other utilities undergoing this journey.

Mobile Organic Biofilm (MOB) technology has been implemented at several sites throughout North America to increase the settling characteristics of Wastewater Treatment Plant Biomass. The increase in settling allows for increased biomass capacity resulting in the ability to achieve greater Biological Nutrient Removal (ie. in cold conditions). Currently, the H. McIvor Weir Wastewater Treatment Plant in Saskatoon does not achieve cold weather nitrification due to a combination of the slower biological activity at cold temperatures, the Hydraulic Retention Time (HRT) of the aerobic zones within the Bioreactors and the design solids loading rate of the secondary clarifiers under conventional conditions. Pilot implementation of the MOB technology will be used to increase the mixed liquor suspended solids and biological activity within the constrained aerobic HRT, while using the increased settling characteristics to increase the design solids loading rate of the secondary clarifiers and protect final effluent quality. The increased settling characteristics of MOB also allow for peak flows to be better handled while minimizing the risk of biomass washout. Pilot implementation to MOB technology will also be used to simulate storm flows to determine allowable peak flow loading that can be encountered at the H. McIvor Weir Wastewater Treatment Plant without affecting final effluent quality. This presentation will provide a background on MOB technology and its purpose for being trialed at the plant, the process of trial implementation, the validation of trial success and the lab data obtained to date on pilot progress.

PUMP SELECTION AT THE WINNIPEG PERIMETER ROAD PUMP STATION
The Perimeter Road Pump Station (PRPS) acts as the headworks for the West End Water Pollution Control Centre (WEWPCC), conveying wastewater from western Winnipeg to the influent screen channel at the plant. The PRPS has four different pumps in parallel, each with a unique suction and discharge piping arrangement. The PRPS also uses a branching force main system, with two force mains of different sizes and different lengths which separate from each other at the PRPS and rejoin in the WEWPCC just upstream of the discharge into the screen channel. The force mains and pipe network have changed since construction, but the pumps are mostly original, meaning they no longer operate in their original design conditions, and they require a specialized control strategy to keep pumps maximally operating in their allowable ranges.
The pumping system is also subject to a large set of operational constraints. Neither the PRPS or the WEWPCC are supplied with potable water services. The process water at the WEWPCC is supplied by the incoming wastewater from the PRPS. Therefore at least one pump at the PRPS is required to be running at any given time. The wet well is also relatively small for the flows to the station so the pumping system is required to precisely match their discharge rate to the incoming flow. The incoming flows vary widely, therefore, the pumps are required to cover a very wide range of flows by varying their speed.
Therefore, pumps with large and specific allowable operating regions were required. The smaller of the two pumps was required to meet the minimum measured dry weather flow during nighttime operation. The larger of the two pumps was required to achieve a maximum of almost 8 times the minimum flow. Finally, the two pumps were required to have ranges significantly overlapping each other and the ranges of the other two dissimilar pumps in order to smoothly stage one pump to the next in many possibly scenarios.
Finally, valuable operator insight into historic performance demanded additional constraints on the pump speed and impeller free channel size. Meeting all of these constraints simultaneously required many hours of precise hydraulic modelling and coordination with many pump vendors in order to identify a set of two ideal pumps.
Precise modelling of a relatively complex system was required. Two complementary models – one in Bentley WaterCAD, and the other an internally-designed program based on the Darcy Weisbach formula – were created. These models were calibrated with the help of City operators, and were then used to complement each other in the precise prediction of pump performance in a wide array of possible combinations of running pumps, pump speeds, and open force mains, and thereby develop a control strategy complementing the four pumps in the station.

ARROW Utilities (formerly Alberta Capital Region Wastewater Commission) serves a large geographical area surrounding Edmonton. It operates the 3rd largest WWTP in Alberta, serving 400,000 residents in 13 municipalities with a conveyance system including 138 km of gravity sewers and 58 km of forcemains. ARROW identified 3.2 km of 1350 mm diameter concrete pipe in need of repair or replacement. A design/build request for proposal was issued, and CIPP lining was selected as the rehabilitation method. The pipe alignment runs through an environmentally sensitive area and is close proximity to residences in other areas. The project was planned to minimize liner installations to reduce impacts to these areas while optimizing cost effectiveness. The project was installed in five segments, with the longest over 700 m. The liners required for these long installations far exceeded the allowable transport weight. The project was only feasible using a unique process, over the hole wetout (OTHW). For the vast majority of CIPP lining projects, the dry liner is shipped from manufacturing to a regional wetout facility where it is impregnated with resin. For the OTH process, the dry tube is transported to installation site, where a mobile wet out facility is constructed, and the resin is introduced. This is one of few OTH installations in Western Canada. This presentation describes the project background, design and tendering, and installation with the OTH system. It discusses key considerations including environmental impact mitigation, site for curing equipment and resin tankers, and the overall OTH process.