Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

 
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Session Overview
Date: Wednesday, 15/Sept/2021
7:00am - 8:30amBreakfast—Wednesday Breakfast
Location: Room 400A
Room 400A 
7:00am - 11:00amSpeaker Ready Room is Open
Location: Room 110C1
Room 110C1 
7:00am - 12:00pmRegistration Desk is Open
Location: Main Lobby
Main Lobby 
8:00am - 10:15amSession 21A: Facility Operations - Livestream
Location: Room 400BC
Room 400BC 
 
8:00am - 8:45am

Exploring an Alternative Alkalinity Source - Full Scale MBR Pilot Using Ultra-Fine Calcium Carbonate

Anthony Benavidez1, Jeremy Weisser2, Stan Heimburger3

1Jacobs, United States of America; 2Columbia River Carbonates, Woodland, WA; 3Heimburger & Company, Blaine, WA; , ,

Jacobs and Columbia River Carbonates worked closely together in 2020 to trial alternative RAS alkalinity and pH control at the 8.0 MGD Spokane County Regional Water Reclamation Facility (SCRWRF) operating in Spokane, WA. Jacobs has had responsibility for operating this facility for Spokane County since its start-up in 2011. Currently, the SCRWRF uses nearly 100% of its Class A reclaimed water for Spokane River streamflow augmentation. The remaining amount is used for process water and irrigation of the facility site. This membrane bioreactor (MBR) facility uses state-of-the-art membrane technology and is designed to meet or exceed Washington State Department of Ecology permitted limits for contaminants in discharged effluent.

In June 2020 Jacobs and Columbia River Carbonates began a full-scale pilot replacing the 25% active sodium hydroxide with MicronaTM Aquacal 70, a 70% active micronized calcium carbonate aqueous slurry, for alkalinity and pH control of mixed liquor in the MBR. At this facility, phosphorous removal from wastewater is achieved by addition of ferric chloride in 1st and 2nd stage treatment. This trial of Aquacal 70 continued for 90 days while closely monitoring wastewater quality and membrane permeability while maintaining standard operating conditions.

Results from the Aquacal 70 operating period that began in late June and continued until the end of September 2020 were found to a) fully replace NaOH in mixed liquor with a significantly lower volume (and operating cost) requirement, b) decrease variability of alkalinity and pH in MBR mixed liquor, c) have no negative impact on membrane functionality during or after the trial d) decrease the requirement for 25% sodium hydroxide added for final effluent pH control, and e) increase solids content of sludge and cake to waste from anaerobic digestion. These will be fully documented and presented.

Additionally, extensive use of a similar product at municipal and industrial wastewater treatment plants in Western Europe – and particularly in Germany, Austria, and Switzerland, built confidence in the trial and use of Aquacal 70 by Jacobs at the SCRWRF.



8:45am - 9:30am

Septage: Regional Water Quality and Practical Considerations in Managing and Treating High-strength Wastes

Patrick Roe

HDR, United States of America;

In Washington State, there are nearly 950,000 individual on-site wastewater disposal systems, primarily septic tanks connected to drain fields. Recommended practice is for the septic tank contents to be removed for disposal every 3 to 4 years. Historically, septage collected from septic tanks has been treated in publically-owned treatment works (POTWs). This presentation will address septage characteristics, water quality objectives, vehicle management, and in-plant handling of septage.

A large number of septic systems exist in the Puget Sound basin in western Washington. On-site sewage system management areas have been formed in basins with critical water quality considerations to ensure the proper management of septic systems to protect water resources. Septage treatment in municipal treatment plants is therefore consistent with regional water quality objectives.

However, there are also drivers away from septage receiving at POTWs. Due to declining water quality in Puget Sound, nutrient loading caps will soon be implemented, and nitrogen limits will follow. An individual utility could chose to restrict septage receiving to meet near-term nutrient discharge loading caps, contrary to regional water objectives. Also, microorganisms in biological nutrient removal systems are sensitive to heavy metals which are typically prevalent in septage. Future restrictions on septage receiving may be necessary to protect biological nutrient removal processes.

Septic tank effluent pump (STEP) collection systems have become common in some areas. The disadvantages and disadvantages to a utility of accommodating STEP systems will be discussed.

The final part of the presentation will review practical considerations for managing vehicles on treatment plant sites and designing septage receiving facilities at municipal wastewater treatment facilities. At many facilities, septage is introduced into influent wastewater, but other facilities have had success with feeding septage into solids handling processes. Alternate methods of introducing the septage into the treatment process will be discussed and examples presented.



9:30am - 10:15am

Return Activated Sludge Rate Impacts to Biological Phosphorus Removal

Brent Deyo1,2, Erik Coats2

1T-O Engineers; 2University of Idaho;

Biological phosphorus removal (BPR) is necessary to realize sustainable recovery of phosphorus from wastewater. In achieving BPR, perhaps the most accepted characteristic of a successful process is the necessary cycling of a mixed microbial consortium through anaerobic and aerobic conditions. Key to the anaerobic state is the absence of nitrate. However, most BPR facilities, which commonly achieve nitrification and operate with pre-anoxic denitrification, have moderate to significant levels of nitrate within their return activated sludge (RAS). It has been suggested that nitrate can be reduced by slowing the RAS rate such that organisms within the secondary clarifier can perform denitrification, thereby reducing the concentration of nitrate within the RAS. Even though RAS is the backbone of all activated sludge treatment, there appears to be little research on the impacts of RAS rate on overall system performance, as well as BPR specifically. There is also limited understanding on the specific impact of nitrate loading on the BPR system and the anaerobic capacity for nitrate. To investigate these topics further, a full-scale water resource recovery facility (WRRF) performing BPR was monitored before and after RAS rate changes to assess and evaluate impacts to the BPR process. Denitrification was assessed in the secondary clarifier, and key anaerobic BPR metabolisms were evaluated. Correlations noticed within the full-scale system were investigated further with batch tests and process modeling software. Data indicates that even low nitrate loads can have a significant impact on the BPR system but may not lead to a noticeable change in effluent phosphorus concentrations until a failure-inducing nitrate load is reached. The findings from this research will help guide WRRF operators to make informed decisions related to adjusting RAS rate to enhance and maintain BPR. Results will also lead to more stable operation and application of BPR.

 
8:00am - 10:15amSession 22A: Innovation & Technology
Location: 110AB
110AB 
 
8:00am - 8:45am

Installation, Startup, and Operation of World’s First Regenerable Resin System for PFAS Removal

Patrick McKeown. PE1, Steve Woodard. PhD1, Tim Gould2

1ECT2; 2Ahtna Engineering Services, LLC;

The United States Air Force Civil Engineering Center (AFCEC) is conducting on-going response activities to remove and remediate groundwater impacted by poly- and perfluoroalkyl substances (PFAS) at the former Pease Air Force Base in New Hampshire.

AFCEC responded by contracting with Wood Group PLC to conduct a side-by-side pilot test in 2016, comparing the performance of Emerging Compound Treatment Technology’s (ECT2) regenerable ion exchange (IX) resin and bituminous granular activated carbon (GAC). The regenerable resin system was selected for full-scale application, based on system performance and a lower overall lifecycle cost than GAC.

A 200-gpm system was provided to meet the primary project objective of producing treated water with combined PFOS plus PFOA concentrations below the 70 ng/l Health Advisory Level (HAL). The full-scale IX resin system was installed from fall 2017 through spring 2018.

The PFAS remediation system has treated more than 31 million gallons of groundwater having a total average influent PFAS concentration of 55 µg/l. The effluent quality from the IX resin system has been consistently non-detect for PFOS and PFOA, readily achieving compliance with the 70 ng/l HAL target.

Five successful resin regenerations have been performed to date. Operational modifications have been made to address and correct minor challenges with the distillation system, and regenerant recovery and super-loading processes have proven successful. The original superloading media is still operational, having removed and concentrated greater than 99.99 percent of the recovered PFAS mass, and therefore no PFAS waste has needed to be hauled off site to date.



8:45am - 9:30am

A Pilot Scale Evaluation of Coagulant Selection and Dose on HF UF Membrane Performance at the West Boise Water Renewal Facility

Dan Hugaboom1, Ryan Anderson2, Brad Jeppson1

1Carollo Engineers Inc, United States of America; 2City of Boise;

In 2019, the City of Boise completed a pilot study of tertiary coagulation and hollow fiber microfiltration and ultrafiltration (MF/UF) membrane technologies at its West Boise Water Renewal Facility (WBWRF) for phosphorus removal. The work was done to support planning for plant improvements required to comply with anticipated reductions in phosphorus discharge limits from the WBWRF.

The pilot study investigated the performance of a wide range of coagulants and membrane technologies to achieve two primary process goals:

  1. Tertiary treatment train effluent total phosphorous of less than 0.1 mg/L TP-P. Five coagulants were tested across a range of doses to meet the TP goal without overloading the membrane process with coagulated solids. Ferric chloride, ferrous chloride, alum, ACH and RE300 (cerium chloride) were evaluated to achieve a treatment goal of reducing TP from approximately 1 mg/L in the secondary effluent to <0.1 mg/L.
  1. Demonstrate reliable membrane performance. Membrane performance was evaluated using quantitative goals for maximum fouling rates, residuals production and off line chemical cleaning frequency. Three different membrane systems, each with unique design and performance characteristics were evaluated for this application. They include pressurized (cartridge style) UF membrane and two submerged (vacuum driven) systems. The experimental matrix allotted significant amount of time for optimizing backwash, air scour, cross flow and chemical cleaning strategies as well as a range of flux rates.

Below doses of about 5 mg/L (as product), membrane fouling was low and chemical cleaning cycles met goals for maximum allowable frequency, however filtered effluent TP did not consistently meet the goal of <0.1 mg/L. As required dosages increased to meet filtrate TP goals, more energetic and frequent cleaning strategies were necessary to meet membrane performance goals. This presentation will include a detailed analysis of phosphorus removal across the range of coagulants, as well as membrane process performance.



9:30am - 10:15am

The Facility of The Future for the Utility of the Future

Layne McWilliams

Cascade Energy, Inc., United States of America;

The “Utility of the Future” program has given a name to the management and organizational principles that will be needed for wastewater organizations to thrive in the years to come. Features include professional training programs, labor recruiting programs, CMMS programs, improved public and customer relations, collaborative working relationships with regulators, resiliency for extreme events, energy management programs, etc.

But, what about the physical plant? In many ways, most of the new plants being built today would look familiar to a time-traveling engineer from the 1950’s. Part of this is expected – for very good reasons, our industry is slow to embrace new ideas until they are proven out through many years of full-scale use.

My hypothesis is that our industry could create some VERY different facilities if the design requirements were changed. I propose to collect, organize, and share ideas from volunteers from at least 10 separate PNCWA-member engineering firms and vendors who will help answer this question: If you were asked to design a 5 MGD, greenfield facility located near Coeur d’Alene, to meet a 5/5/1 standard, year-round, that would minimize the total carbon footprint of its construction and operation over 30 years, what features would you include? You must select from materials, equipment, and processes that are currently commercially available somewhere in the world, though it does not need to be used currently in the wastewater sector. Ideas for collection and disposal alternatives will also be welcomed.

For the conference, we will present a design summary of each major process area and briefly describe the alternatives and the reasoning for them suggested by the survey participants. The calculations and assumptions for embedded and operational CO2e will be summarized along with the pros and cons of each alternative. The names of volunteers will be shared but will not be associated with specific solutions.

The over-arching goal of the presentation is to provide new ideas to the audience and show what might be achieved when efforts are focused not on lowest first cost but on lowest ultimate impact to the environment.

 
8:00am - 10:15amSession 23A: Construction & Alternate Delivery: Collaboration & Communications - Livestream
Location: Room 430AB
Room 430AB 
 
8:00am - 8:45am

Building Resilient Communities Through Building Resilient Teams

Josh Baker1, Jeff Hodson2, Mike Zeltner3, Tyler Resnick4

1City of Boise; 2Jacobs; 3Brown and Caldwell; 4McAlvain Companies, Inc.; , , ,

Four years ago, the Lander Street Water Renewal Facility Phase 1 Improvements project team set out to create a resilient team that could deliver the City of Boise’s largest construction project in recent history. The project was well under way replacing deteriorating infrastructure when the global pandemic hit. This presented many different challenges which have changed the way we all work. Throughout this experience, our patience has been tested, relationships strained, and processes challenged, but the work put into developing the team paid dividends throughout those difficulties.

The City selected the Construction Manager/General Contractor (CM/GC) delivery model for this project and elected to bring the CM/GC into the project at the start of the engineering effort. This allowed for early team chartering and branding to prevent tripartite silos from forming. The project team quickly adapted the mindset of “we are protectors of infrastructure and of the Boise River.”

One of the key attributes of the project team’s approach is their willingness to challenge the status quo and modify a process if it is not working as intended. An example of this is the design coordination log (the process formerly known as requests for information). This use of this log has resulted in issuing early engineering clarifications that have outpaced subcontractor questions and allowed work in the field to progress without delays.

The project team has also enhanced communication by using multiple, real-time methods between engineering and field staff while leveraging asynchronous communication to manage the project narrative with stakeholders. The result has been optimized teamwork and collaboration, better informed management, increased communication with subcontractors, and decreased risk of miscommunication.

The project to date has not lost any schedule (even considering COVID) and has a deductive change order value while being almost halfway complete. This is attributed to the strong relationships that have formed and the resilient team approach that has been taken. The lessons that have been learned are being applied to the next phase of improvements in an effort to continue to overcome difficult situations and create our future.



8:45am - 9:30am

Pumping Up Communication Through Progressive Design Build

Katie Spilker1, Amanda Mesick1, Jessica MacClanahan2

1Kennedy Jenks Consultants; 2City of Bend; ,

The City of Bend’s North Interceptor Sewer Project (NISP), identified in the Collection System Master Plan (CSMP), consists of design and construction of a sewer transmission system to accommodate the City’s growth plans, policies, and incorporate redundancy into the system. Along with serving an expanding UGB, the proposed alignment also allows for the decommissioning of up to ten (10) lift stations as an added benefit.

At the confluence of the existing Plant Interceptor and the newly planned NISP, a critical deficiency in hydraulic capacity for future growth was identified. It required the evaluation of alternatives for pipeline sizing, configuration, and routing, with an overall goal to set the City of Bend up for success long into the future. Through a collaborative decision-making process, our team leveraged a broad range of City stakeholders and arrived at a consensus to add an influent pump station at the Water Reclamation Facility (WRF). As a result, a significant challenge emerged with how to limit impacts on WRF operations during start-up and testing of the pump station.

This presentation will outline the vision and drivers for this project, along with sharing a success story on how utilities can use Progressive Design Build to deliver projects that mitigate impacts on operations. Attendees will learn about developing an integrated team, establishing the correct level of communication, and lessons learned that can be applied to future projects. Finally, the presentation will focus on creating a culture of change in project implementation that emphasizes integration of operations into the decision-making process. Pumping up Communication through Progressive Design Build resulted in a seamless transition from a gravity-fed treatment plant to one supplied by an influent lift station at the City of Bend’s WRF.



9:30am - 10:15am

Going Beyond Expectations: Collaborating to Deliver an Award-Winning Facility

Michael Borrero1, Brett Arvidson2

1Carollo Engineers, United States of America; 2City of Oak Harbor;

The City of Oak Harbor (City) completed construction of its new $125 million Clean Water Facility (CWF) producing Class A reclaimed water quality effluent to the Puget Sound. Two overriding project goals for the City were protecting the environment and constructing a facility that was integrated into the community. With the greenfield CWF located downtown and adjacent to the waterfront Windjammer Park, the City incorporated architectural features and park amenities with the CWF project to become a civic asset woven into the community fabric.

Getting the project permitted and completed on schedule was a complex task due to site constraints, environmental restrictions, and the likelihood of encountering cultural resources. The City became one of Washington State’s first wastewater projects to be delivered under the alternative project delivery approach of a heavy-civil General Contractor/Construction Management (GC/CM). The GC/CM’s suggested approach shortened construction by 2 years from a conventional design-bid-build project by including:

  • Early procurement and segmented work packages proceeding during design
  • Development and timing of design packages to always keep the GC/CM productive

Schedule related challenges were ultimately overcome by developing a genuine partnership with an eye to keeping quality expectations high. Implementation of these early design packages were successful and reinforced positive work relationships with the City, Engineer and GC/CM Contractor.

Presentation will include specifics on:

  • Lessons learned of the project challenges including start-up and commissioning
  • Collaborative efforts examples between the Engineer, City and GC/CM to integrate the CWF into the community
  • Results to the cultural resources approach

The efforts to bring the CWF to life have been recognized by the national American Public Works Association (APWA), American Council of Engineering Consultants (ACEC) and the Engineer-News Record (ENR) Best Projects for the Pacific Northwest region.

 
8:00am - 10:15amSession 24A: Risk Assessment & Emergency Response - Livestream
Location: 120AB
120AB 
 
8:00am - 8:45am

Assessment of Critical Dependencies for Rapid Disaster Recovery

Wayne Gresh1, Dave Breitenstein2, Kent Yu3

1Carollo Engineers; 2City of Eugene, OR; 3SEFT Consulting Group; ,

The Metropolitan Wastewater Management Commission (MWMC) mission is to protect the community’s health and environment by providing high-quality wastewater services to the Eugene-Springfield metropolitan area. In alignment with that mission, MWMC identified and assessed critical dependencies that could impact its ability to respond and recover from a disaster. The effort was part of developing a Disaster Mitigation and Recovery Plan that assessed expected performance of conveyance and treatment facilities and outlined actions and upgrades needed to achieve Oregon Resiliency Plan level of service goals for the Cascadia Subduction Zone earthquake and MWMC’s internal goals for a catastrophic flood adjusted to reflect climate change effects.

To identify critical dependencies, staff used a matrix provided by its consultant team to explore and rank what was most needed for disaster response and recovery. This effort identified employee and family preparedness; City and regional roads; telecommunications; post-event structural assessments; up-to-date Emergency Operations and Continuity of Operations plans; power; data; vendor and shipping services; fuel; and post-event mechanical, electrical, and plumbing assessments as the ten most critical dependencies.

Each of the critical dependencies were assessed by the consultant team in partnership with staff members. This included (a) staff responding to a survey that assessed employee and family preparedness and (b) identifying critical materials and supplies and the respective vendors. The consultant team worked with staff and Eugene and Springfield Emergency Managers to develop actions that could be taken to be better prepared and minimize the potential for cascading failures.

MWMC has found this effort very valuable to gain a better awareness and understanding of the critical dependencies through staff engagement. The effort provided a direct benefit in the effort needed to respond to the COVID-19 pandemic. In March 2020 Eugene updated its continuity of operations plan, one of the dependencies identified. Based on that update they were prepared and successfully implemented procedures to address chain of command, reduced staffing, and accounting procedures needed during the emergency. This presentation will focus on the critical dependencies identified and the actions outlined to better prepare for disaster response and recovery.



8:45am - 9:30am

Seismic Resilience and Implications on Critical Infrastructure

Scott Schlechter, Jason Bock

GRI, United States of America; ,

The Cascadia Subduction Zone (CSZ) located off the coast of Washington, Oregon and California can produce some of the largest earthquakes (magnitude 9.0) in the world. Over the past 10,000 years, this fault has had 41 significant ruptures with the last large event in 1700. This equates to an approximately 30% chance of another major rupture (Mw 8+) in the next 50 years. Oregon legislature recognized the potential hazard and in 2013, the Oregon Seismic Safety Policy Advisory Commission published the Oregon Resilience Plan to determine likely impacts of a CSZ earthquake. The plan addresses acceptable timeframes to restore infrastructure after an earthquake/tsunami event and changes that Oregon can take to reach resilience targets. During the plan’s development, a Water and Wastewater Task Group was created to review vulnerabilities of the state’s pipelines, treatment plants, and pump stations. Per the findings of the plan, drinking water and sewer infrastructure could take up to three years to restore services. Since then it has been left to individual agencies to figure out what to do with aging infrastructure and ways to reduce the damage a CSZ earthquake will have on critical drinking water and sewer systems. Navigating various seismic codes and identifying the right plan is not an easy task. The Oregon Resilience Plan is not specifically tied to design code guidance and therefore there is not a clear approach to seismic resiliency that will be the right fit for every agency. This presentation will focus on how owners and design teams can collaborate to prepare a risk assessment model that will establish how to define resilience, system impacts, and solutions for mitigation. A case study completed at the Port of Portland will demonstrate how to implement a risk assessment model. Through the case study, we will cover the roles of the owner and designer, hazard identification, risks to the economic structure, developing practical mitigation strategies, and cost-benefit analysis. Key takeaways will include steps for understanding state and regional expectations for resilience, demystifying seismic analyses and design, and strategies to prepare infrastructure to be resilient.



9:30am - 10:15am

Regional Water System Risk Analysis and Planning

Jason Hurless1, Byron Smith2

1Stantec Consulting Services Inc., United States of America; 2City of Hermiston, Oregon; ,

The City of Hermiston and the Port of Umatilla are partners in the ownership and management of the Regional Water System (RWS) located in the Greater Hermiston, OR area. The RWS was created in the mid-1990’s to convey up to an ultimate flow of 27,000 gpm of Columbia River water to connected and rate paying users. The water is pulled from just upstream of the McNary Dam by the Intake Pump Station and conveyed through nearly nine miles of 42-inch Ameron pipeline to booster stations, a water treatment plant and the end users. These users range from food processors, power generating facilities, data centers, agricultural growers and the City of Hermiston for potable water treatment. The RWS infrastructure is nearly 30 years old, however, the number of users and the sophistication of the system has expanded greatly since it’s creation. With the aging facilities in mind and overall economic importance of the RWS increasing, the RWS requested that Stantec Consulting Services Inc. perform the RWS’s first facility plan. As part of this facility planning effort, Stantec performed a condition assessment on the RWS facilities and worked closely with the users, City and the Port on a system by system risk evaluation. The risks were assigned occurrence probabilities and associated costs if the risks were realized. The weighted risks were monetized and ranked for prioritization purposes. Three main output were developed resulting from this effort:

  1. Future projects were prioritized and an overall CIP for the system established.
  2. Targeted emergency reserve funds were established to manage the potential risks.
  3. Non-potable and potable water rates were updated to create adequate reserve funds as part of the risk mitigation strategy.

The CIP framework was finalized and communicated to the users with the first year of capital upgrades projects underway.

 
8:00am - 10:15amSession 25A: Collection & Conveyance
Location: Room 420A
Room 420A 
 
8:00am - 8:45am

Corroded Manhole Assessment, Rehabilitation Design, and Construction

Neil Jenkins1, Chris Kossow2

1Jacobs, Boise ID; 2Eagle Sewer District, Eagle ID; ,

Concrete manholes should have more structural strength than peanut butter, but PB-consistency concrete is exactly what Eagle Sewer District found as they conducted their periodic inspection of one section of collection system manholes. The culprit was found to be hydrogen sulfide corrosion from two nearby forcemain discharges. These forcemains, coupled with a very steep sloped pipe (up to 8 percent) down a hillside farther down the main were enough to release H2S that corroded the manholes faster than expected. Compounding the problem was the location of this main, through a high-end neighborhood and adjacent to a golf course. The groundwater up on the hill was not a factor, but the section at the bottom of the hill was in nearly 10-feet of groundwater.

The manholes were assessed first visually and then with a scrape test. From the ground, the 15 to 18-foot deep manholes appeared to be in good to fair condition. The scrape test was performed and the softened concrete sluffed from the wall like tooth paste or soft plaster. The downstream section of the system yielded less than 1-inch of concrete loss. As we worked upstream to the base of the hill and closer to the pump station discharges, up to almost 2-inches was discovered. Next to the pump station discharge, 3 inches of the 5-inch thick manhole wall was missing.

In addition to the condition assessment approach, this presentation will discuss the manhole rehabilitation methods that were considered. These include manhole replacement, liners, inserts, structural coating, and non-structural coatings for corrosion protection. The final design that resulted and the ultimate rehabilitation project will be presented. Lessons learned that will be shared include the how to complete rehabilitation technologies and coordination with neighbors and interested agencies. The manholes were successfully rehabilitated and have performed well for nearly a year and a half.



8:45am - 9:30am

Bringing Spiral Winding Rehabilitation to the Pacific Northwest

Ron Bard1, Yang Zhang2, Angela Richardson1

1Brown and Caldwell, United States of America; 2City of Portland, Bureau of Environmental Services; ,

Virtual Speakers

Spiral Wound Technology TM (SPR) is a pipeline rehabilitation method using strips of PVC or HDPE. Winding machines unroll strips of material that form to the pipe's shape, creating a new lining. The City of Portland Bureau of Environmental Services (BES) will be using the PVC SPR material on the Carolina Trunk rehabilitation project. Utilities across the globe have installed lining using SPR, including a few in the USA, but this is the first application in the Pacific Northwest. BES often uses pipeline rehabilitation on its aging infrastructure to extend the useful life of its sewer pipes. Upon successful completion of this pilot project, BES plans to add SPR to its toolbox of available rehabilitation techniques for future projects.

A significant advantage of SPR is the ability to install the material without flow diversion. With this method, it is possible to install lining with live flow during low flow periods. Since the Carolina Trunk is a combined sewer, we scheduled the work to take place at night during the summer when there are no rain events expected. Due to the Carolina Trunk's location along a busy arterial, being able to rehabilitate the sewer without diverting flow is critical to project success.

Constructed in 1909, the Carolina Trunk is a 51-inch diameter cast-in-place monolithic concrete circular sewer pipe. Several inspections revealed that the pipe is in fair to poor condition and needs rehabilitation. Defects observed throughout the pipe included longitudinal cracking and pipe deterioration with exposed aggregate and pitting. This project will rehabilitate approximately 800-feet of the trunk using SPR rehabilitation.



9:30am - 10:15am

Implementation of Telemetered Water Quality Sensors in the Sanitary Collection System

Scott Mansell, Jason Cook, Greg Arrigotti, Jeff Van Note, Ting Lu, Ken Williamson

Clean Water Services, United States of America;

Collecting continuous, reliable water quality data from the sanitary collection system without an excessive maintenance burden is a serious challenge for utilities, but one that is increasingly necessary for developing enhanced source control programs and protecting treatment plants from potential upsets. For several years, Clean Water Services (CWS) piloted various technologies, implementation methods, installations, and cleaning devices. While none of these pilots were ultimately successful, important lessons were learned in each of them that helped drive CWS towards successful implementation. Over the past two years, CWS has successfully developed and implemented a telemetered, continuous water quality sensing network in its sanitary collection system and has already been successful in tracking down and eliminating a consistent source of problems for one its treatment plants. CWS has developed a unique sensor holder that minimizes ragging and made use of robust sensors that are less sensitive to fats, oil, and grease buildup. To test this technology in addition to future technologies, CWS developed a test flume at its Forest Grove treatment plant that uses post-grit screen influent. This flume can be adjusted to simulate various velocities, depths, and sewer sizes and allows for the study and testing of different sensors, cleaning devices, and containment devices with close observations in a controlled environment that wouldn’t be possible in the sanitary collection system. CWS has conducted various experiments using this flume to study the factors that affect longevity, film buildup, and maintenance frequency for various probes. The lessons learned through CWS’s first few years of unsuccessful pilot studies were presented at PNCWA in 2019. In this talk, CWS will discuss how it finally became successful at developing and implementing a network of water quality sensors in the sanitary collection system, and where it is going from here.

 
8:00am - 10:15amSession 26A: Reuse
Location: Room 410ABC
Room 410ABC 
 
8:00am - 8:45am

Guiding Regional Reuse Options – A Distributed Systems Approach

Melanie Holmer, Jocelyn Lu

California Urban Water Agencies (CUWA);

Water reuse can be achieved through both centralized and onsite systems for non-potable and potable uses. With several reuse options available, utilities can apply a distributed systems approach, defined as a regionally optimized combination of water reuse, to produce an effective “fit-for-community” reuse strategy. The California Urban Water Agencies (CUWA), made up of 11 major water utilities in California, conducted research to understand the compatible system characteristics for reuse strategies. CUWA has led the development of a fact sheet that informs that distributed systems approach, which detail considerations around policy, community, environment, economics, operations, and treatment.

Case studies were conducted to understand the decision-making process of utilities that are evaluating water reuse. For example, San Francisco Public Utilities Commission (SFPUC) optimized their regional reuse through a distributed systems approach. The west side of SF is home to large irrigation customers like the Golden Gate park. To capitalize on economies of scale, SFPUC is building a centralized recycled water plant to serve them. The east side of SF is more densely developed with fewer contiguous areas that could benefit from centralized infrastructure. In 2015, SF passed an ordinance requiring new development with footprints > 25,000 square feet to meet their own non-potable reuse needs through onsite reuse. With much of the City’s development boom captured under the ordinance, SFPUC found that recycled water demands were largely addressed on the east side.

This work also details the importance of expanding green building certification rating systems, like LEED, to include all sustainable reuse options. A building can employ multiple strategies to increase their water efficiency, and developers tend to opt for onsite reuse. However, LEED offers water efficiency credits for any type of alternative water source, including centralized reuse, and clarification of the rating criteria can improve awareness of this opportunity.

This work is intended to start a conversation with utilities, policy makers, and developers on what is considered sustainable in a given community. This presentation will provide an overview of the favorable system characteristics for each reuse strategy and summarize the key takeaways for stakeholders.



8:45am - 9:30am

Formalizing the Role of Urban Water Agencies in Distributed Water Infrastructure

Alexander Fairhart1, Lynn Broaddus2

1Isle Inc.; 2Broadview Collaborative; ,

Virtual Speakers

This submission continues a conversation from the latest edition of WE&T here.

https://www.waterenvironmenttechnology-digital.com/waterenvironmenttechnology/february_2021/MobilePagedReplica.action?utm_source=newsletter&utm_medium=email&utm_campaign=TXWEAT210128002&utm_content=gtxcel&pm=2&folio=64#pg68

Distributed water infrastructure projects, also called decentralized, onsite or hybrid, are emerging across the Pacific Northwest. Development of these systems is driven by private sector interest, but also government agency sustainability initiatives. These systems, designed for household, building or district scale, aim compact the efforts of traditional municipal waterworks to avoid the need for collection and conveyance. Major cities across the Pacific Northwest have projects underway that reuse rainwater and wastewater, and even generate fresh water from alternative sources.

Distributed water infrastructure brings a new paradigm to water system development and planning. The knowledge of local water agencies and professionals is often underutilized among the current stakeholder groups of developers, sustainable building groups, technology vendors and public health departments. The public interest would be better served by further collaboration between Pacific Northwest water agencies and the groups developing these projects. In the few cases where municipalities have taken a bold view of the future and adopted legislation for these systems, collaboration is mandated, and cross-benefits readily found.

Water utility professionals are well-suited for the review and approval of new distributed technologies, with the importance of reliability and safety being elevated beyond standard water infrastructure. Several case studies will be reviewed where such collaboration has been facilitated and prioritized by water agencies, to the benefit of new infrastructure developers, technology vendors, serviced ratepayers, and the public health. By taking an active role on behalf of the public, water agencies ensure a seat at the table in this infrastructure development of the future.



9:30am - 10:15am

Strategically Balancing Effectiveness and Implementation of Water Reuse Options to Manage Water Consumption

Christopher Stoll1, Karen Galt2, Joelle Hammerstad2

1Kennedy Jenks; 2City of Seattle, Seattle Parks and Recreation; , ,

Virtual Speakers

Seattle Parks and Recreation (SPR) operates and maintains around 485 parks over 6,414 acres across the City of Seattle including swimming pools, wading pools, golf courses, spray parks, community centers, and other recreational facilities. SPR was started in 1884 and has continued to increase the open space and facilities available to the public since then. As part of ongoing operations and maintenance, SPR has seen their cost for potable water increase because of three reasons: 1) increase in potable water prices and 2) longer and more intense irrigation seasons due to more frequency drought conditions, and 3) rapid population growth in Seattle since 2010. As SPR desires to continue to use local resources sustainably and reduce long-term operations cost, this Study had three main objectives to help achieve these desires: 1) to assess the effectiveness of SPR’s existing water reuse and conservation systems and 2)to evaluate other reuse and conservation systems that SPR could implement, and 3) to determine a high-level implementation plan for the reuse and conservation systems examined to decrease long-term operations and maintenance cost. This Study analyzed and scored various systems for water reuse and conservation (including recycled water, grey water, stormwater and pool water) based on the systems’ effectiveness (ability to meet the Study objectives such as decreasing water use and decreasing reliance on potable water) and ease of implementation (level of effort needed to implement a specific system). Based on the analysis and evaluation, the water reuse and conservation systems were broken into categories to assist with focusing efforts for implementation.

 
9:00am - 10:30amPNCWA Past Presidents Breakfast
Location: Room 200
Room 200 
10:15am - 10:30amWednesday Morning Break
 
10:30am - 12:00pmSession 21B: Collection & Conveyance: Rehabilitation - Livestream
Location: Room 400BC
Room 400BC 
 
10:30am - 11:15am

Rehabilitation Analysis Of The 100-Year Old Whatcom Creek Trunk Main

Erik Waligorski, Austin Wong

Carollo Engineers, Seattle, WA; ,

The City of Bellingham’s Whatcom Creek Trunk Main was installed in 1909 and consists of large diameter, up to 3-foot wide by 6-foot tall, egg-shaped concrete pipe running along Whatcom Creek and into downtown Bellingham. The existing 6,500 foot-long trunk main includes several sections of pipe which are visible in the creek’s bed and completely exposed during the dry season. Maintenance completed by the City showed structural pipe deficiencies which compelled the City to look at the replacement or rehabilitation of the existing sewer.

Carollo Engineers was hired by the City to complete an alternatives analysis to compare viable replacement or rehabilitation options, which included open cut replacement, cured-in-place pipe (CIPP), sliplining, and epoxy coating. Each alternative was evaluated on criteria which could impact the design and construction of the preferred alternative, including hydraulic capacity, constructability, community and environmental impact, bypassing requirements, and construction costs.

To accomplish the alternatives analysis, a laser profile was performed to provide accurate dimensions, estimates of sedimentation, identification of major structural defects not previously identified, and any infiltration which could impact construction.

Each of the rehabilitation methods identified would also require the pipe to be at least partially bypassed to allow for machinery and workers to perform the pre-cleaning and rehabilitation. A bypass pumping analysis was performed using the historical rain and sewer flow data to size an appropriate temporary bypassing system.

This presentation will look at the construction of the original sewer trunk main and how the design of critical sewer interceptors has changed over time, the data and criteria required to complete the alternatives analysis, and the selected alternative. Attendees will learn what risk management aspects needed to be addressed as part of this analysis including, sewer bypass, construction footprint constraints, traffic impacts, and design requirements for non-circular pipeline rehabilitation.



11:15am - 12:00pm

Planning for Seattle’s Future – The Wastewater System Analysis Episode

Kevin Cook1, Andrew Henson1, Annalisa McDaniel2

1Murraysmith, United States of America; 2Seattle Public Utilities; ,

Seattle Public Utilities (SPU) is currently undertaking an ambitious effort to integrate their wastewater and drainage systems planning efforts, bridging the needs of the wastewater and stormwater systems to achieve greatest environmental and community benefit. Continual growth and development have made providing adequate capacity a challenge throughout Seattle’s history, since it requires addressing challenges such as an aging system, growing population, densification, and climate change.

SPU serves a population of approximately 747,300 spread over 84 sq-miles and operates a complex network comprised of 1,423 miles of sewers, 68 pump stations, and 86 CSO outfalls. A system-wide capacity analysis was conducted using the latest hydraulic/hydrologic (H/H) model; the results were used to identify and prioritize risk areas using input from multiple stakeholders within SPU.

A primary objective of the Wastewater System Analysis (WWSA) was to identify and understand wastewater capacity needs. Performance Thresholds were selected to achieve performance goals of providing adequate capacity in the public wastewater system, minimizing the risk of sewer backups into private property and public right-of-way. Performance parameters of 1-ft pipe surcharge, maintenance hole flooding, and hydraulic capacity limitation of above 100% of existing pipe were used under one, two, and five-year, 24-hour design storms to evaluate system performance.

The modeling results were used in conjunction with community outreach results to identify and prioritize risk areas. 384 risk areas were delineated and categorized into critical, high, medium, medium-low, and low categories. The project team investigated and categorized critical priority risk areas further to identify capacity issues, providing a framework for programmatic solutions like Inflow and Infiltration (I/I) reduction, pipe and pump station replacement, operational and connected sewer agency constraints, and any combination of issues. This presentation will provide a sound approach to future planning efforts by incorporating technical and non-technical challenges in an expanding urban environment.

 
10:30am - 12:00pmSession 22B: Resource Recovery
Location: 110AB
110AB 
 
10:30am - 11:15am

Applied Planning for Pocatello's Biosolids Reuse and Recovery

Nick Smith1, Skyler Allen2

1Stantec Consulting Services Inc., United States of America; 2City of Pocatello, ID; ,

The City of Pocatello, ID has been recovering, land applying and reusing its Class B treated biosolids for decades on nearby agricultural lands. The biosolids treatment and handling system consists of mesophilic anaerobic digestion of thickened primary and secondary sludge, followed by lagoon storage and spring/summer liquid sludge hauling to both City owned and leased land. In the last few years, local growth and associated loading to the Water Pollution Control Facility (WPFC) have increased to the point where the lagoon is often overloaded in late winter through early summer. This situation creates challenges to the operations of the WPCF as the biosolids recirculate back into the liquid stream. This solids overload results in costly and hectic lagoon dewatering efforts, sub-optimal treatment performance and increases the risk of NPDES permit violations. Faced with this challenge, coupled with the desire for long term biosolids planning, the City selected the Stantec/Keller team to address this problem as part of the 2021 Facility Plan update. To properly address the biosolids issue, the team implemented a decision-making process for both solids handling and solids reuse or disposal. The first evaluation included a decision to either expand the biosolids lagoon system or move toward solids dewatering. The second decision determined whether to continue the existing land application of liquid sludge, move to dewatered sludge land application, enhance the biosolids to a Class A through composting, or shift toward landfill application. The results are in, the decisions have been made and the City is moving forward with making the recommended improvements to provide the best solution and end use for this valuable City resource.



11:15am - 12:00pm

Novel Alternative Management of Data Center Industrial Wastewater

Brett Converse1, Shae Talley1, Scott Coleman2

1J-U-B Engineers; 2City of Umatilla Oregon; , ,

Data centers offer economic drivers attractive to communities able to meet utility demands. These industries have large electrical demands to power associated computer equipment which are converted to heat and must be evacuated. Data centers using evaporative cooling require large amounts of water which is evaporated or discharged as industrial wastewater when constituent concentration or temperature prohibits continued use in cooling towers. The volume of water used, the volume of water evaporated, the volume of water discharged, and constituent concentration therein will depend on the quality of source water, climatological conditions and internal management. Water and wastewater service providers must understand the demands of data centers and plan for meeting those demands prior to agreeing to serve. In 2013, the first data center was constructed within city limits at the City of Umatilla, Oregon. After the data center became operational, industrial wastewater was discharged to the City’s wastewater treatment plant when the ambient temperature began to climb in the springtime. When the temperature reached over 100 degrees, the City experienced a 65 percent increase in wastewater flow and corresponding dilution of most influent constituent concentrations. As the industrial development continued, the City had concerns over managing projected flows from future data center expansions and began planning to meet service demand. After investigating alternatives, the City decided to pursue discharging the industrial wastewater directly to a water of the state via a national pollution discharge elimination system (NPDES) permit. The presentation will focus on the City’s experience collecting, treating, permitting and disposing of the data center industrial wastewater and associated benefits: additional irrigation water, lower fees and sustainability.

 
10:30am - 12:00pmSession 23B: Construction & Alternate Delivery - Livestream
Location: Room 430AB
Room 430AB 
 
10:30am - 12:00pm

Outfall Fallout – Using the CM/GC Process for A WRF Outfall Replacement

Chris Horgan1, Jon Baune1, Craig Borrenpohl2, Andrew Arbini2, Curtis Neibaur3

1J-U-B ENGINEERS, Inc.; 2City of Post Falls, Idaho; 3McMillen Jacobs Associates; , , , ,

Have you considered involving a Construction Manager/General Contractor (CM/GC) for your next water resources project? The CM/GC contracting method is a fairly new mechanism available for use by Idaho municipalities compared to the traditional design-bid-build process. This approach can be useful and successful when project complexities necessitate the involvement of a contractor early in the project process.

This presentation will discuss the use of the CM/GC process by the City of Post Falls, Idaho (City) for replacement of their Water Reclamation Facility (WRF) outfall in the Spokane River. Representatives from the City (Owner), J-U-B Engineers, Inc. (J-U-B, Engineer of Record), and McMillen Jacobs Associates (McMillen, CM/GC) will provide a project history and discuss how various project risks evolved a traditional design-bid-build approach to a CM/GC process. The CM/GC procurement approach will then be discussed, followed by the various roles and responsibilities of the City, J-U-B, and McMillen during project design, environmental permitting, bidding, and construction. A panel discussion on lessons learned and future best practices with all three entities will follow the formal presentation.

The goal of this presentation is to discuss the City’s project-specific experience with the Idaho CM/GC process, including why they chose the CM/GC process over traditional design-bid-build and lessons learned for each phase of the process (procurement, design, construction), and then provide a forum for discussion with the City, J-U-B, and McMillen about each party’s general experience with the project and the CM/GC process. This presentation will provide insight for municipalities and engineers on why they might consider an alternate approach to design-bid-build and how they might successfully use the CM/GC process on their next project.

 
10:30am - 12:00pmSession 24B: Utility Planning & Asset Management - Livestream
Location: 120AB
120AB 
 
10:30am - 11:15am

Co-Creating a Combined Sewer Plan – A Tool that Reports Infrastructure Costs and Benefits in Real Time to Facilitate Community Based Planning

Brent Robinson1, Alice Lancaster2, Erik Davido3

1Seattle Public Utilities; 2Herrera Environmental Consultants; 3Davido Consulting Group, Inc.; , ,

Seattle Public Utilities is reimagining the planning process for combined sewer overflows (CSO) and stormwater improvements through the Longfellow Starts Here (LSH) project by endeavoring to make planning accessible and meaningful to the community served by this project. Whereas traditional options analysis has centered on technical feasibility and cost minimization approaches with sparse community engagement on leading options, the LSH team is shifting the planning approach to begin with community and co-create an infrastructure vision through simplified planning tools that demystify drainage and wastewater infrastructure. One tool, the Drainage and Wastewater High Level Planning Tool, is a Microsoft Excel based calculator that reports the cost and water quality performance of various user defined infrastructure scenarios in real time. Specifically, the user selects a suite of CSO reduction and water quality treatment options and the tool reports the planning-level cost, CSO volume reduction and pollutant reduction to Longfellow Creek. The intent of this tool is to facilitate simple, iterative planning so that community can collaborate with SPU to “co-create” the project and engage in dialogue around trade-offs and benefits of various options. The LSH team hopes this tool, through meaningful community engagement, will promote unconstrained creativity and help to elevate optimal strategies by removing the historical bottlenecks in infrastructure planning from modeling and cost analysis given that these calculations are performed automatically by the tool. This presentation will provide a summary of the scenario planning tool’s intended uses, an overview of the back-end calculations and assumptions, and a real time test drive of the tool to showcase its performance.



11:15am - 12:00pm

Asset Management Shifts Utility Management from Reactive to Proactive

Katie Spilker1, Steven Dutschke1, Mia Sabanovic2

1Kennedy Jenks Consultants; 2Portland Bureau of Environmental Services; ,

The City of Portland Bureau of Environmental Services (BES) Columbia Blvd Wastewater Treatment Plant (CBWTP) was first constructed in 1952 and continued to expand in later years​. Many process pipes and plumbing systems are original to the plant’s construction and have often been the forgotten brethren of the CBWTP. The majority of the pipes have not been inspected internally during their lifetime or assessed for their condition and remaining useful life (RUL)​. The CBWTP has experienced an increase in pipe breaks in recent years causing process areas to be taken down and creating a detrimental impact on plants operations and a sharp increase in financial expenditures​. Frequent breaks and leaks also impact operations and maintenance resources as piping systems are continuously patched to ensure reliable operations of the treatment plant.

BES Condition Assessment team has engaged with Kennedy Jenks consultants to prioritize, inspect, and assess plant process piping helping move BES towards proactive management of its pipe assets. The primary goal of this project is to identify BES’s risk exposure due to these aging pipe assets to enable tailored and sustainable long-term replacement/rehabilitation strategies.

This presentation will outline the vision and drivers for this project, along with sharing success stories and how other utilities can adopt similar programs. Attendees will learn about developing a truly integrated asset management solution, from identifying pipe assets, managing these process piping assets in CMMS, bringing GIS tools within the plant fences, developing risk and prioritization tools, using advanced condition assessment technology and conducting this with careful coordination with a busy plant’s scheduling restraints. Finally, the presentation will focus on creating a cultural of change in managing assets, one that proactively inspects piping systems and avoids unforeseen breaks and leaks through effective risk communication long after the team members have moved on.

 
10:30am - 12:00pmSession 25B: Regulatory Challenges: Thermal Compliance
Location: Room 420A
Room 420A 
 
10:30am - 11:15am

A Clean Water Act Approved Strategy for Temperature Compliance: City of Boise Clean Water Act 316(a) Thermal Variance Demonstration Project, V2.

Kate Harris1, Thomas Dupuis2

1City of Boise; 2HDR; ,

Temperature effluent limits are challenging to meet and several alternative compliance strategies have been litigated. Section 316(a) of the Clean Water Act provides that the EPA (and delegated state agencies) may authorize alternate thermal conditions in NPDES permits where the effluent limitation is more stringent than necessary to assure the protection and propagation of a balanced, indigenous community (BIC) of shellfish, fish, and wildlife in and on the receiving waterbody. The City of Boise applied for a 316(a) thermal variance and completed a demonstration project. The initial demonstration strategy and results were presented at a previous PNCWA meeting. The strategy for the demonstration project was modified in coordination with Idaho DEQ as administration of the NPDES permitting program was transferred to the state. The results of the modified demonstration project will be presented.

The city conducted a Type II Demonstration: a predictive demonstration based on literature, laboratory, and field studies conducted to evaluate that proposed alternate thermal effluent limitations (ATELs) will provide adequate protection and propagation of the BIC, as characterized by Representative Important Species (RIS). Near field (mixing zone) and far field analyses were performed separately but considered collectively. The potential for adverse effects was evaluated in terms of temperatures in the context of RIS specific biothermal attributes from the scientific literature, local expertise, and Idaho field data. Results demonstrated that the city’s ATEL’s would assure the protection and propagation of the RIS and maintenance of the BIC in the Lower Boise River. The city’s thermal load does not, and will not, cause lethal or sublethal effects that would affect the protection and propagation of the RIS populations; i.e., not interfering with the RIS’s completion of life history functions of reproduction, spawning, growth, and migration. The city’s IPDES permit is anticipated in fall 2021, therefore the presentation will also include a description of the permitting process and outline implementation planning.



11:15am - 12:00pm

Taking a Watershed-Based Approach to Developing and Optimizing a Thermal Compliance Strategy

Scott Mansell, John Dummer, Bob Baumgartner, Rajeev Kapur, Ken Williamson

Clean Water Services, United States of America;

The Tualatin River is a small river that receives wastewater discharges from over 600,000 residents and many large industries.The river and its tributaries contain salmonids which are impacted by water temperature increases caused by anthropogenic activities. Due to the relatively large discharges of wastewater to the relatively small river, the discharges can have a large effect on the temperature of the river that must be mitigated to protect aquatic life. Even more significant population and economic growth is projected in the watershed over the next 50 years. While Clean Water Services currently mitigates the thermal loads from its discharges through a Themal Management Plan that includes reuse, cogeneration, flow augmentation, and riparian shade projects, the projected growth of the population in the watershed and the expected effects of climate change require that an updated Temperature Compliance Strategy (TCS) be developed that will meet the temperature challenges into the future. However, there are a large number of potential actions that could be taken at the treatment plants and in the watershed to help decrease the temperature of the river and mitigate the effects of the thermal loads from the treatment plant discharges. Each of these actions has different strengths and weakness as well as variable temporal and spatial effectiveness which can often be affected by the other actions being taken. Optimizing which actions to take and when to take them is a difficult process. CWS has developed an updated Thermal Compliance Strategy that includes a suite of actions to be taken over time between 2025 and 2075. A tool was developed that can analyze a large array of potential actions in numerous combinations and predict their effectiveness, costs, benefits, and impacts. The tool relies on complex hydrodynamic and water quality models, data collection, economic analyses, and engineering analyses to compare and contrast the different actions over time, alone and in combination. Using the tool, CWS optimized the suite of actions and the timing of their implementation to maximize benefits to the river while minimizing cost and other impacts. This holistic method provides a much more effective TCS than effluent cooling alone.

 
10:30am - 12:00pmSession 26B: Wastewater Process: Solids
Location: Room 410ABC
Room 410ABC 
 
10:30am - 11:15am

Effect of Fat, Oil and Grease (FOG) on Digested Sludge Dewaterability

Ornella Sosa-Hernandez, Peter Schauer

Clean Water Services, United States of America;

VIrtual Speakers

Clean Water Services investigated the impact that co-digestion with Fat, Oil and Grease (FOG) has on the dewaterability of digested sludge. Over the past 4 years, a deterioration of the dewatering performance has been observed while the volume of FOG that is handled has increased at the Durham Advanced Waste Water Treatment Facility (AWWTF). In addition to a possible decline in centrifuge performance from equipment age, the FOG load and its variable composition had been suspected to cause dewatering issues as the cake solids dryness and solids capture have steadily decreased despite little change to the polymer dosing.

The anaerobic digesters at the Durham AWWTF have independent FOG feed lines allowing for different loadings to either digester. During this 4-month evaluation, more FOG was fed to one of the two anaerobic digesters while both received equivalent indigenous sludge loading which is composed of thickened primary and secondary sludge. The digester feed, FOG stream and digested sludge were characterized by measuring parameters such as proteins, lipids and carbohydrates, orthophosphate, and cations concentrations. Dewaterability was assessed through analysis conducted by Dr. Matthew Higgins at Bucknell University.

This presentation will include an analysis approach that can help recommend FOG management strategies whereas the lessons learned from this evaluation are:

  • FOG addition had no negative impact on digested sludge dewaterability.
  • The polymer demand was more affected by indigenous sludge VS loads than FOG loading.
  • The presence of charged compounds in the digestate such as phosphate and cations impacted some of the dewatering characteristics.
  • Although VS loads above 0.25 lbs/ft3/d and up to 50% FOG were fed for a short period of time, digestion stability was maintained. The time to perceive instability and the impact to other parameters such as alkalinity should be investigated.


11:15am - 12:00pm

The Future of Biosolids Handling

Tanner Hartsock

Biolynceus LLC, United States of America;

Sustainable biosolids handling strategies are becoming increasingly difficult to develop. For land applications, the most common biosolid disposal technique, wastewater facilities (WRRFs) must produce either Class A or Class B biosolids. Even if these requirements are met, some WRRFs are faced with local pressure, forcing them to alter the course of their biosolids handling program. Biosolids regulations have seen little change since the first regulations were established in 1993, and mounting pressure on the Environmental Protection Agency make future changes both likely and imminent. Additionally, contaminants such as per-polyfluoroalkyl substances (PFAS) are sure to complicate regulations moving forward. Even landfill applications are uncertain: recently, the state of California banned the use of biosolids as an alternative landfill cover. Now more than ever, WRRFs are considering innovative, even novel technologies for managing their biosolids. Bioaugmentation can be used to degrade volatile biosolids and should be viewed as a viable approach to reduce the amount of biosolids at WRRFs. Research has shown that microbes capable of producing amylase enzymes can hydrolyze cellulose, a primary component of wastewater sludge, and convert it to glucose, a form of soluble carbonaceous biochemical oxygen demand (cBOD). This soluble glucose is readily available as a food source to both the added microbiology and the existing sludge biomass, reducing sludge volumes by up to 40%. Probiotic additions are common in lagoon systems, reducing costs associated with dredging, dewatering and hauling and recently, biological sludge reduction at mechanical wastewater facilities has received attention as an alternative means to reduce costs associated with dewatering and hauling. As regulations become more stringent, the time to consider new technologies for biosolids reduction is now.

 

 
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