Location: Room 400BC |
|8:30am - 10:00am||00B Opening: Keynote Presentation - Livestream|
Location: Room 400BC
Dr. Dan Prinzing, Executive Director of the Wassmuth Center for Human Rights & Tai Simpson, Organizer for the Indigenous Idaho Alliance
The Wassmuth Center for Human Rights was founded for the purpose of constructing a memorial to human rights in Idaho’s capital city. That vision became a reality when the Idaho Anne Frank Human Rights Memorial was dedicated to the public in 2002. The site is the only memorial to Anne Frank in the United States, is one of the few places in the world in which the full text of the Universal Declaration of Human Rights is on public display, and is recognized as an international Site of Conscious.
Identified as the educational arm of the Memorial, the Center provides programming and resource onsite in the Memorial, offsite in classrooms and communities throughout Idaho, and online reaching national and international audiences.
We envision an inclusive society where Idahoans take responsibility for promoting and protecting human rights; where everyone is valued and treated with equal dignity and respect; and where everyone’s human rights are a lived reality.
As an education center, the goal is to empower others to be upstanders in the classroom, community and country.
"The Storyteller" is Tai Simpson's name in the Indigenous language of the Nimiipuu nation (Nez Perce Tribe of Idaho). As a direct descendant of Chief Redheart, Tai takes great pride in serving her community as an organizer, activist, and advocate. Tai catalyzed her racial and social justice activism while studying Sociology and Political Philosophy & Public Law at Boise State University. Her experience at Boise State prepared her for the work she does in the community today. .
Tai is an organizer for the Indigenous Idaho Alliance. In 2018 and 2019, the Indigenous Idaho Alliance drafted the proclamations for Indigenous Peoples Day for the State of Idaho and the city of Boise. In 2020, the Alliance helped to draft HCR033 Concurrent Resolution acknowledging Missing & Murdered Indigenous Peoples Day that passed in the Idaho legislature in March.
As a Social Change Associate with the Idaho Coalition Against Sexual & Domestic Violence, Tai focuses on violence prevention and response within Idaho’s tribal communities. In 2019, Tai gave a TEDxBoise talk exploring the belief that Indigenous “old ways” need to come back in style, made new. The old ways are principles on which many Indigenous communities build their social and political narratives. As an antiracism activist and community leader, she uses contemporary and traditional Indigenous storytelling to depict the lens of “old ways” and how they protect the sacred, builds strength in the community, and keeps nature in balance; these principles support her work to champion radical inclusion, equity, and liberation.
|10:30am - 12:00pm||Session 01A: Planning & Regulatory - Livestream|
Location: Room 400BC
10:30am - 11:15am
One Doesn’t Just Walk into a Proactive Rehabilitation Program: SPU’s Strategic Quest.
1Seattle Public Utilities; 2Blue Cypress Consulting, LLC; ,
Seattle Public Utilities (SPU) entered into a Consent Decree in 2013 to reduce combined sewer overflows and work towards eliminating sanitary sewer overflows. A major cause of sewer overflows in Seattle is structural failure. It is also a growing concern given that the City’s 1,420 miles of sewer pipes have an average age over 80 years and pipe rehabilitation has been historically underfunded. SPU increased pipe inspection and rehabilitation funding upon signing the Consent Decree, but recognized that there would need to be a holistic look at pipe rehabilitation to ensure long-term system reliability.
This presentation walks through SPU’s work to develop and secure funding of a long-term rehabilitation plan for its aging sewer system. This planning effort was not a single event, but a concerted effort through a series of strategic projects over four years; with each strategy building on one another. Participants will learn about SPU’s strategies for pipe inspection, condition evaluation, risk assessment, capital investment, and implementation planning. Particular focus will be spent on key aspects of the process such as incorporating service equity, increasing efficiencies, securing staffing for implementation, and preparing for adaptive management. This presentation will leave participants with a roadmap for how to move from a reactive to proactive rehabilitation program. It was not a simple and quick solution, but has set SPU up for reliable and sustainable long-term sewer service.
11:15am - 12:00pm
Klamath Falls Evaluates What to Do With Its Final Effluent
Carollo Engineers, Inc., United States of America; ,
In response to lower nutrient and temperature limits for continued river discharge, the City of Klamath Falls evaluated 100% reuse against continue river discharge. The City is looking for economical, long-term strategies that beneficially uses City’s final effluent, offers some regulatory certainty and promotes partnerships in addressing Upper Klamath River water supply and water quality concerns. This presentation will discuss reuse to augment agricultural irrigation needs involving the US Bureau of Reclamation, the Klamath Drainage District and the Lower Klamath National Wildlife Refuge. Under this reuse alternative, the City would divert its final effluent over the entire year to the Klamath Drainage District who in turn would beneficially use and manage the final effluent to meet irrigation demands of local growers and to help the Lower Klamath National Wildlife Refuge maintain habitat for migrating waterfowl. Reuse water management plans, permitting strategies and needed improvements to the City’s existing Spring Street Wastewater Treatment Plant to support a 100% reuse option will be reviewed and compared to a continued river discharge alternative. Critical factors in alternative selection will be discussed so other Cities facing similar water quality challenges may benefit from City of Klamath Fall’s experience.
|1:15pm - 2:45pm||Session 01B: Risk Assessment/Stormwater - Livestream|
Location: Room 400BC
1:15pm - 2:00pm
Boise’s SARS-CoV-2 Wastewater Dataset and the Future of PCR Testing at WRFs
1City of Boise; 2HDR; ,
Viewing wastewater as a resource opened pathways of innovation previously unforeseen. The SARS-CoV-2 pandemic amplified a similar paradigm of innovation in the science of Wastewater-Based Epidemiology (WBE). In May of 2020, the City of Boise began sampling wastewater at both of its Water Renewal Facilities (WRFs) to test for SARS-CoV-2 virus using quantitative polymerase chain reaction (qPCR). On June 17th the City began daily sampling and continued through two infection peaks. The City’s dataset is one of the most robust datasets in the country for WBE.
RT-qPCR quantifies copies of virus RNA in the wastewater matrix. The City contracted with the University of Missouri to perform qPCR. Virus quantities in the wastewater ranged from 50,000 to 1,395,000 copies per liter. Puro virus recovery was used as a proxy indicator of the relative amount of virus recovered through the qPCR method and ranged widely from 2 to 82 percent, with an average of 11 percent. Genetic sequencing was also used to perform early screening to detect if SARS-CoV-2 variants were present.
Visualizations of the data show clear correlation with number of confirmed cases in Ada County. Numerical correlations were weak because of daily variability, however the visual correlation revealed that during periods of infection rate increases the wastewater signal provided four to seven days advanced notice prior to case report date. The City coordinated with Centers for Disease Control, Central District Health, and St. Luke’s Hospital to maximize the benefit of WBE.
Laboratory layouts and equipment specifications were evaluated for conducting qPCR molecular testing at WRF lab facilities. Experience designing 26 public health labs in the United States was leveraged to customize the “unidirectional flow of sample” design approach within the WRF laboratory context.
Using qPCR at WRFs will continue to expand the paradigm of wastewater as a resource. The current application of qPCR for SARS-CoV-2 testing reveals that indicator virus testing for disinfection (such as adenovirus and norovirus), identification of specific organisms for biological nutrient removal within WRFs, and early detection of future diseases in wastewater are destined to become integral parts of ongoing WRF operations in the modern era.
2:00pm - 2:45pm
Beavers Improve Water Quality in an Urban Watershed
City of Gresham, Oregon, United States of America;
Beaver populations have been returning to urban watersheds in the Pacific Northwest, bringing with them both benefits and challenges. To better understand the effects on local watersheds, we conducted several studies of beaver activities within the city of Gresham, Oregon. We looked at pollutant removal efficiencies in a large stormwater treatment wetland with and without beaver activity, assessed the effect of beaver dams on stream temperatures, and documented the physical and biological changes to stream channels near dams. We found that pollutants of concern were generally removed more efficiently when beaver dams were present in the treatment wetlands. This is likely due to the water being filtered through the dams which are repaired after each storm. The effects of dams on stream temperatures varied depending on site characteristics, but all dams created ponds with temperature heterogeneity and stratification. Dams on higher order streams sometimes reduced overall stream temperature by pulling water from the entire stratified water column and increasing hyporheic flow. Within just a few years of beaver activity, several sites experienced increased stream complexity with new gravel bars, side channels, and braided streams. We also found increased macroinvertebrate diversity in the relatively sediment-free cobbles downstream of dams. These findings demonstrate multiple benefits of beavers in urban watersheds. After communicating these benefits to stakeholders, we have been working with beaver experts to adapt our systems to find ways to protect infrastructure while coexisting with beavers through targeted use of technologies such as pond levelers, culvert fencing, and tree protection.
|3:00pm - 5:15pm||Session 01C: Alternate Delivery/Leadership/Wastewater - Livestream|
Location: Room 400BC
3:00pm - 3:45pm
Transforming Design-Bid-Build to Improve Collaboration and Teamwork
Keller Associates, Inc., United States of America; ,
The design-bid-build procurement process can limit the chance for collaboration between the owner, engineer, and contractor. This drawback has been a driving force toward non-traditional delivery methods such as design-build, construction manager-at-risk, and progressive design-build. However, there are tools to improve collaboration, which can make the design-bid-build process remain the best option. Some of these tools include prequalifying contractors and providing a detailed construction constraint specification. The construction constraints section of bidding documents offers engineers a unique way to communicate challenging project aspects to contractors. When well thought out and detailed, construction constraints can help contractors understand anticipated shutdowns, required bypass pumping provisions, and limitations in the existing equipment’s operational capabilities.
Utilizing these and other tools to improve collaboration can also lead to an aggressive competitive bidding process. Recently, the City of Lewiston awarded a contract for the construction of wastewater treatment plant upgrades. The majority of their existing processes were being upgraded and expanded, which created an immensely complex project. Using collaborative tools, the contractors understood the project and had greater confidence in their costs, such that all bids were within ~5% on this $34M project. This presentation will introduce and discuss collaborative methods for improving the design-bid-build procurement process.
3:45pm - 4:30pm
Panel Discussion: Leadership Perspectives from the Future Workforce
1HDR, United States of America; 2Carollo; 3City of Meridian, Idaho; 4Jacobs Engineering Group; 5CivilWest Engineering Group; 6HDR; 7University of Idaho; , , , , , ,
A diverse panel of active, local leaders with vast combined experience in water issues will share insight and their vision of the future workforce. In 2019, the Diversity and Leadership Track focused on leadership success and challenges associated with a diverse workforce from the point of view of those in the later stage of their career. In 2021, we will pose similar questions to a panel who are in the first half of their career looking forward. The panel will answer questions on their vision for future leadership based on tomorrow’s workforce, diversity and technology.
A panel of 5 will be developed with Conference Committee and Leadership Committee. Anticipate it will include diverse gender and age leaders at both private and public agencies from Washington, Oregon and Idaho.
4:30pm - 5:15pm
Screen Capture Efficiency Sampling & Testing Protocol for Waste Water Treatment Plant Screens at Start-up
Ovivo USA, LLC, United States of America;
For approximately two decades, consulting engineers have asked screen manufacturers to provide third party, independent test results documenting the capture ratios of their screen’s debris removal efficiency. Have these results truly been reproducible at your wastewater plant?
Decades of third-party capture testing of screens in the UK have been a good thing. However, the screenings capture data proved only the “Capability” of that particular screen tested and under those specific UK flow conditions. Expecting identical capture results from the same manufacture’s screen at wastewater facilities with differing hydraulics, variable wastewater velocities, TSS & FOG loading characteristics, let alone up-front grinders is neither practical thinking or proven in the field to be true for 40%-45% of the current installation history in the US. Why? It is the very subject of this paper & conference presentation. There are definite wastewater similarities from site to site; however, there are also many dissimilarities that require screening equipment modifications to achieve the true screenings capture capability of any manufacturer’s screen. This presentation will discuss an inexpensive upstream and downstream on-site sampling method & procedure, as well as a protocol and accepted test methodology that can be performed at any municipal wastewater treatment facility or local third party laboratory to measure solids capture efficiency of any newly installed screen(s) at startup, including older screen installations that have fallen short of owner expectations.
This presentation will reveal standardized sampling hardware, process & procedure, as well as simple bench-top test method for determining the screenings capture of any headworks or membrane protection screen. A single day sampling method & protocol will be described in detail that will provide a screen’s site-specific debris capture efficiency. This standardized sampling and testing protocol can be performed by screen manufacturers, plant operators, and/or third party laboratory technicians.When incorporated into a consulting engineer’s screen specifications it will require all bidding manufacturers to meet a desired screen capture efficiency (±X%) in the bid spec. The awarded manufacturer will be responsible for meeting the specified screenings capture.
|8:00am - 9:30am||Session 07A: Construction & Alternate Delivery/Risk Assessment & Resiliency - Livestream|
Location: Room 400BC
8:00am - 8:45am
Changing the Airplane Engine Mid-flight: Best Practices to Manage Construction at Operational Facilities.
Jacobs, United States of America;
Keeping existing wastewater systems running during invasive construction projects requires precise planning and significant collaboration between designers, contractors and O&M staff. Ignoring the practical realities of system operational constraints and requirements can create headaches for O&M staff, increases the potential for contractor claims and schedule delays and heightens risk of discharge permit violations. Successful projects avoid or minimize operations disruptions and carefully manage critical shutdowns.
A diverse panel of agency staff, engineers and contractors experienced in construction at operating facilities will share insights and experience from their careers. The panel will discuss best practices during both design and construction to prepare for interruptions and interface with existing facilities. Common challenges will be highlighted along with specific activities to avoid gaps and hiccups. Potential topics include:
- Early identification of process constraints
- Successful engagement of O&M staff during design
- Incorporating requirements into contract documents
- Structured processes during construction
- Communication strategies to align parties
8:45am - 9:30am
Assessing Future Coastal Flood Hazards to Water Infrastructure with the Puget Sound Coastal Storm Modeling System (PS-CoSMoS)
1United States Geological Survey; 2Brown & Caldwell; 3City of Bellingham Public Works; ,
The combination of rising sea levels, changing storm patterns, and greater rainfall intensity in the coming decades is expected to increase the magnitude and frequency of coastal flooding across the Pacific Northwest. Flood hazards and associated impacts are of concern to many coastal utilities who are engaged in planning efforts to protect infrastructure and ensure resilient operations in the future. The City of Bellingham (City) owns and operates the Post Point Resource Recovery Plant (Post Point), which is located on the coast of Bellingham Bay. The City has partnered with the U.S. Geological Survey (USGS) to implement the Puget Sound Coastal Storm Modeling System (PS-CoSMoS) to help evaluate risks of storm induced flooding in combination with sea level rise, and to evaluate opportunities for increasing infrastructure resiliency. An initial application of the model is to evaluate potential impacts to the City’s Post Point facility and guide its planning and design.
PS-CoSMoS is developed to evaluate extreme water level recurrence to help federal, tribal, state and local agencies and communities identify impending hazards and inform coastal planning efforts across the Salish Sea into the next century. Flood hazards associated with sea level rise and climate change effects to river floods and storms are computed across the region at 1-meter resolution integrating regionally downscaled global climate models. PS-CoSMoS predicts tides and storm surge with a mean absolute error of 10 cm across 13 tide gages over the period 2018-2019. The model resolves the relative contributions and projected changes of atmospheric pressure anomalies, outer shelf wind effects, interannual ocean dynamics like the El Nino-Southern Oscillation, and local wind setup to extreme water level. Overland flooding and wave setup are modeled with a rapid 2D flow solver and flood extent, depth, duration, and velocities are mapped for several sea level rise scenarios. This presentation will describe the model and its application to the Post Point facility planning and design update.
|10:30am - 12:00pm||Session 07B Planning|
Location: Room 400BC
10:30am - 11:15am
City and County Collaboration – Solving Wastewater Concerns Together
1Keller Associates, Inc., United States of America; 2Boundary County, United States of America; , ,
11:15am - 12:00pm
Investigating Nitrogen Removal Strategies to Reduce Carbon Footprint
University of Idaho, United States of America;
|12:00pm - 1:15pm||Lunch—Tuesday Business Luncheon|
Location: Room 400BC
|1:15pm - 2:45pm||Session 14A: Resource Recovery/Collection & Conveyance - Livestream|
Location: Room 400BC
1:15pm - 2:00pm
Full-scale Digester Micro-Aeration Study to Reduce Hydrogen Sulfide in Biogas
1JACOBS, United States of America; 2LOTT Clean Water Alliance, United States of America;
Biogas generated from anaerobic digestion typically requires gas conditioning before it is used to generate energy. The H2S concentrations in the digester gas at the Budd Inlet Treatment Plant typically range from 950 to 1,050 ppmv, which is approximately double the average inlet design concentration of the existing H2S removal system, resulting in increased O&M costs.
Full-scale piloting of micro-aeration technology (MA) was undertaken to test its feasibility to reduce H2S from the biogas, as limited experience is available of this new technology in full-scale digesters at wastewater resource recovery facilities (WRRF). The full-scale tests were undertaken during a one-year period under different configurations and generated the following findings:
In summary, the full-scale pilot tests showed that this new process-integrated MA technology has potential using minimum plant upgrading while contributing to the sustainability and economic efficiency of the energy recovery process of waste sludge digestion at WRRFs.
2:00pm - 2:45pm
Clackamas Water Environment Services and the City of Gladstone Oregon – Joining Forces in the Fight Against I/I
Clackamas Water Environment Services, United States of America;
Clackamas Water Environment Services (WES) completed a collection system master plan (CSMP) in 2019. One of the findings of the CSMP is that it is more cost effective system wide over the next 20 years to reduce I/I in 19 key basins rather than increase the conveyance and treatment capacity of the system to accommodate the extraneous wet weather flows. The collection system is comprised of multiple jurisdictions or member communities as well as WES owned infrastructure. Every jurisdiction contains a basin in which it was found to be more cost effective to reduce I/I rather than increase the downstream system capacity.
WES and the City of Gladstone (City) both have jurisdiction over portions of the collection system within the 19 key basins, and have immediate capacity needs to reduce the I/I. The good working relationship between WES and the City made it possible for the two entities to establish an IGA and enter into a contract with a consulting engineering firm to address the I/I in both jurisdictions simultaneously. The consulting contract will identify the sources of the I/I and design rehabilitation projects to remove it.
The joint project provides efficiency and cost savings to both of the partner entities. Project management costs are reduced since there is only one project not two. There is economy of scale and reduced mobilization costs when combining the field investigation activities. There are cost savings in the designs when applying the same standards across multiple sets of construction documents. These are just a few of the financial benefits of working together for a common goal.
The I/I identification activities are currently underway and should be completed in June 2021. At that time, the project will move into the phase of designing rehabilitation projects to remove the I/I identified. It is anticipated upon completion of the designs each partner will bid out their own construction projects.
|3:00pm - 4:30pm||Session 14B: Pump Performance/Wastewater Treatment - Livestream|
Location: Room 400BC
3:00pm - 3:45pm
Pump Performance Assessment; A Panacea for Predictive Maintenance?
Parametrix, United States of America; ,
Assessing the condition of pump stations can be a significant undertaking for many utilities, and the specific approaches and techniques of assessment can vary widely. Among the many working components within the pump station its namesake, the pump, is often a key focus. Significantly reduced capacity or excessive vibration are easily identifiable signs of a failed pump; however, quantifying the specific degradation of an individual pump can be difficult. If accurate quantitative data is available the useful life of a pump can be prolonged by targeted maintenance, and premature rebuild or replacement can be avoided.
Methodology for field testing pumps and the differing approaches in testing both flood control and wastewater pumps will be presented. The technical requirements and constraints and opportunities of instruments and data logging equipment will be reviewed. Some of the common and uncommon insights into centrifugal pump performance, implications for the health of the force main, and specific indicators of wear on various components will be discussed.
Two client case studies will be presented detailing how results from pump testing can be applied to assess equipment condition as well as make predictive maintenance and capital improvement decisions. The City of Spokane, WA, tested pumps at five wastewater pump stations to confirm condition and capacity. Multnomah County Drainage District in Portland, OR, has conducted a variety of condition assessments for its 13 flood control pump stations and has performed testing to confirm the flood control pumping capacities and remaining useful life of most of the pumps it maintains. The specifics of testing wastewater and flood control pumps will be covered, in addition to how the resulting test data, in combination with operational data, can be used to perform targeted rebuilds and prioritize replacements.
3:45pm - 4:30pm
CFD in Wastewater Treatment: A Useful Design Tool or Design Dollars Down the Drain
Osborn Consulting, Inc., United States of America;
With continual improvement of computer processing and software algorithms, there is an ever-growing number of applications for computational fluid dynamics (CFD) to improve the design operation of wastewater treatment facilities. However, the costs of CFD modeling studies are significant, not all applications warrant a detailed study, and some studies are not realistic in addition to being unwarranted.
CFD studies are warranted when 1) their cost can be recovered by savings in capital or operations and maintenance 2) an overall reduction in project risk can be achieved 3) the added benefit of flow visualization warrants the added expense. An example is the utilization of CFD studies for contact tanks. These studies can provide an accurate estimate of baffle factor and result in tanks with smaller footprints than would be allowed using empirical equations or design charts. Reduced footprint size and/or reduced disinfection byproducts justify the cost of CFD studies for contact tanks, storage tanks, settling basins, etc.
CFD studies of pump stations that do not require physical models can be used to evaluate pre-swirl and velocity distribution in the pump throat and develop modifications to improve approach conditions to the pumps. However, CFD has yet to advance to where it can be used to evaluate the potential for vortices or for accurate estimation of turbulence entering the pump. Some consultants and software providers may claim that they can, but buyer beware.
Successful studies require proper application and experienced CFD consultants who can both properly execute a model study and interpret/present the results to design engineers and stakeholders. Attendees will gain an understanding of CFD as a tool that can be useful when properly applied and when the design team understands how close to reality the results are.
|6:30pm - 8:30pm||Dinner—Tuesday Night Awards Banquet|
Location: Room 400BC
The livestreaming of the awards ceremony will begin at 7:15pm MT.
|8:00am - 10:15am||Session 21A: Facility Operations - Livestream|
Location: Room 400BC
8:00am - 8:45am
Exploring an Alternative Alkalinity Source - Full Scale MBR Pilot Using Ultra-Fine Calcium Carbonate
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
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
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.
|10:30am - 12:00pm||Session 21B: Collection & Conveyance: Rehabilitation - Livestream|
Location: Room 400BC
10:30am - 11:15am
Rehabilitation Analysis Of The 100-Year Old Whatcom Creek Trunk Main
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
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.