The Portland Water Bureau is the municipal water department for the city of Portland in the U.S. state of Oregon. The bureau manages a water supply that comes mainly from the Bull Run River in the foothills of the Cascade Range east of the city and secondarily from the Columbia South Shore Well Field near the Columbia River. As of 2015, Nick Fish was the city commissioner in charge of the bureau, and the chief administrator is Michael Stuhr. Budgeted departmental revenues for fiscal year 2015–16 included about $157 million for charges for services.S.S.S.S.
Portland, Oregon, is located in the heart of the Cascadia Subduction Zone and is expected to experience devastating impacts after an earthquake along this fault. In an effort to mitigate the impacts and improve system resiliency, the Portland Water Bureau needs a seismically resilient water pipeline across the Willamette River, as all of the six existing crossing are expected to be severely damaged due to liquefaction and strength loss of the loose riverbank soils. The proposed crossing is located in the Portland downtown core, which is a complex place with a wide array of existing utilities, multiple property owners, transportation corridors, and highly variable geology. This complex location requires design and construction methods to accommodate all the project constraints. Key to managing these constraints is using an appropriate trenchless construction technology. This Design-Build project evaluated multiple trenchless technologies, including horizontal directional drilling, microtunneling, and direct steerable pipe thrusting to install the more than 4,000 ft of 48-in. diameter welded steel pipeline needed for the project. Several unique shaft and pit configurations were needed to accommodate these various trenchless installations in a complicated urban area. This paper focuses on several design and construction method challenges unique to this project and the trenchless industry. Key among these challenges was determining how to accommodate up to 20 ft of lateral spreading of the riverbank ground surface, where a 36-ft diameter shaft will be sunk to accommodate a connection between two trenchless alignments. This paper discusses the comprehensive geotechnical design and analysis efforts to study the anticipated soil loading to the pipe and resulting pipe strains modeled using FLAC and ABAQUS computer software. These analyses were used to demonstrate pipeline performance at varying depths using different pipe wall thicknesses, steel pipe yield strengths, and cased/uncased pipe sections.
Water is often referred to as our most precious resource, and for a good reason – drinking water and wastewater services sustain core functions of the critical infrastructure, communities, and human life itself. Our water systems are threatened by aging infrastructure, floods, drought, storms, earthquakes, sea level rise, population growth, cyber-security breaches, and pollution, often in combination. Marginalized communities inevitably feel the worst impacts, and our response continues to be hampered by fragmented and antiquated governance and management practices. This paper focuses on the resilience of water sector (drinking water, wastewater, and stormwater [DWS]) to three major hazards (Sea-Level Rise, Earthquake, and Cyberattack). The purpose of this paper is to provide information useful for creating and maintaining resilient water system services. The term resilience describes the ability to adapt to changing conditions and to withstand and recover from disruptions. The resilience of DWS systems is of utmost importance to modern societies that are highly dependent on continued access to these water sector services. This review covers the terminology on water sector resilience and the assessment of a broad landscape of threats mapped with the proposed framework. A more detailed discussion on two areas of resilience is given: Physical Resilience, which is currently a major factor influencing disruptions and failures in DWS systems, and Digital Resilience, which is a rapidly increasing concern for modern infrastructure systems. The resilience of DWS systems should be considered holistically, inclusive of social, digital, and physical systems. The framework integrates various perspectives on water system threats by showcasing interactions between the parts of the DWS systems and their environment. While the challenges of change, shock and stresses are inevitable, embracing a social–ecological–technical system-of-systems and whole-life approach will allow us to better understand and operationalize resilience.
Pipelines in regions with moderate and high seismic hazard may be at risk of structural damage and service disruption due to permanent ground deformations (PGD), including earthquake-triggered landslides and liquefaction-induced lateral spread and settlement. Efficient methods of reliability assessment may be required when finite element soil-structure interaction and detailed fragility-based analyses are not possible. This study presents such methods based on a seismic reliability assessment study of large diameter buried pipelines as part of a comprehensive water system seismic study for the Portland Water Bureau (Portland, Oregon). The target audience for this study is engineers as well as water system owners and operators. A case study is presented of three approximately 20 mile long steel pipelines ranging in size from 44 to 66 in. that transport water to East Portland from the Bull Run watershed, and five Willamette River crossings that transport water from East to West Portland. The river crossings include 30 to 60-in. diameter buried pipelines of material types ranging from cast iron and ductile iron to welded steel and bar-wrapped concrete cylinder pipes with welded joints. Segments of these pipelines are subject to as much as 10 ft of combined landslide and lateral spread permanent ground deformations for an M9 scenario earthquake on the Cascadia Subduction Zone. The locations, widths, and magnitudes of the PGD demands on the pipelines were calculated in a GIS framework at the intersection of the pipelines with locations susceptible to landslides and liquefaction. Using available information on the pipeline size, internal pressure, and nominal wall thickness, a simplified analytical analysis was performed to compute maximum strains in the pipelines resulting from transverse PGD. Analytical analysis results were confirmed using nonlinear finite element analyses for representative pipeline segments. Uncertainties in the PGD estimates, width of PGD zones, analytical procedures, and peak ground acceleration were used to perform Monte Carlo simulations to compute individual and joint failure probabilities for the pipelines. Reasonable parameter distributions and values for the analytical pipeline strain and Monte Carlo simulation analyses are provided. The methodology presented in this study uses analytical procedures to assess pipeline vulnerability and provides likely locations of damage compared to more general evaluations typically performed using empirical pipeline fragilities. This approach can be used by engineers performing similar studies to better quantify pipeline vulnerability and provide a more realistic assessment to the owners.
Alameda County Water District has observed increased biofilter effluent manganese concentrations during winter operations. To investigate manganese removal across surface water biofilters during cold‐water conditions, trends were analyzed between water temperature and manganese removal across multiple testing scales, multiple biofilter influent water qualities, and both anthracite and GAC media. During acclimation of new biofilters, 100% removal of manganese was observed sooner across both anthracite and GAC biofilters brought online at 20°C compared to 12°C. Acclimation at 12°C required 18 extra days for the GAC biofilters and 48 additional days for the anthracite biofilters. For fully acclimated biofilters, a decrease in manganese removal across both GAC and anthracite biofilters at temperatures below 15°C was observed. However, greater and more consistent manganese removal was observed across GAC compared to anthracite biofilters. Performance differences between locations also suggest that operational and water quality conditions also likely affect manganese removal.
The City of Portland’s water system is the largest in the state of Oregon covering an area of approximately 225 square miles and serving almost one-quarter of the population of the state. The water system services 165 pressure zones and has over 2,000 miles of pipelines, two major dams, 38 pump stations, 59 distribution system tanks, and 10 terminal storage reservoirs. Some of the oldest components of the system are over 100 years old. In 2009 dollars, the replacement value of the system was estimated to be $6.7 billion. A comprehensive seismic study of the Portland’s water system was completed to assess its performance in an M9 earthquake on the Cascadia Subduction Zone. A long-term system improvement plan was developed to meet the stated recovery goals in the Oregon Resilience Plan, a plan developed under the direction of Oregon House of Representatives to protect lives and maintain economic activity following an M9 earthquake.
