Clackamette Cove / Clackamas River Bank Stabilization Client: City of Oregon City; Oregon City, Oregon Completed: 2002 In April 2000, the City of Oregon City contracted with a multi-disciplinary team led by PWR to analyze and develop a design solution for a severely eroding riverbank along the Clackamas River near Clackamette Cove. Serious erosion started in November 1996 and threatened to breach the peninsula that separates the river from a large local fisheries and recreational cove. The objective of the project was to identify the cause of the problem and develop the most cost-effective, environmentally friendly and constructable solution. The project was divided into phases. The first phase was the analysis that involved a hydrographic survey, the development and use of a two dimensional hydraulic model, a geotechnical analysis, an alternative analysis and an analysis of both the environmental and construction-related permits. The second phase included the final design and permitting. The two-dimensional finite element surface water hydraulic model (FESWMS) with an after market graphical interface (SMS 6.0) was used to predict flow velocity magnitudes and patterns needed to better understand the severe riverbank erosion problem. Significant field data was collected including bathymetry, flow, velocity, topography, surface water elevations, and aerial information throughout the reach which was used to calibrate the model. The calibrated model provided critical information regarding the specific areas of concern and, equal in importance, the overall river and cove dynamics. The stabilization involved a 350-foot reach which consisted of nearly 30 vertical feet of riverbank using a combination of a rock toe and geosynthetic / bioengineering bank stabilization techniques. It also incorporated large boulders and root wads as significant habitat features. The construction of the project, which was overseen by PWR staff, occurred during the summer of 2002.   McCormick Levee Stabilization Client: Yakima County Public Works; Yakima County, Washington Completed: 2001 The upstream end of McCormick Levee on the Naches River in Yakima County, Washington is failing. Erosion at the toe is causing over-steepening of the bank and slope failure against the river. Continued erosion will eventually remove enough material to compromise the levee's structural integrity. Under extreme stress (for example a flood) the levee could breach, threatening life and property. Phil Pommier, currently at PWR, developed engineering designs for stabilizing the bank erosion.

Phase 1 involved design and construction of four stream barbs for diverting the channel thalweg away from the bank and an irrigation inlet. The project also involved biotechnical bank treatments for mitigation of bank plantings disturbed by construction. Phase 2 involved a conceptual reach study to outline an environmentally beneficial approach to bank and flood protection issues within this 5000 foot reach. Future phases are anticipated for designing and implementing the conceptual solutions proposed in Phase 2.     Metzger Park Apartments Stream Bank Stabilization Client: Clean Water Services, Washington County, Oregon Completed: 1999 The foundation of an existing building in the Metzger Park Apartments was threatened by stream bank erosion of Ash Creek. PWR as subconsultant to KAI conducted a detailed hydraulic and scour analysis for both existing and proposed conditions at the site. PWR developed a bank stabilization design to protect the existing structures. The design included a stone toe and bioengineered erosion control for the eroded bank. Armed with the model data PWR developed several design alternatives for stabilizing this 320-ft. reach.   The work involved stream assessment, wetland delineation, preliminary and final design drawings, biotechnical bank stabilization, permit applications and submittals, and County land use submittal. In addition, the project required a 'no-rise' certification as all improvements were within the regulatory floodway of Ash Creek. All design elements considered the no-rise requirement and ultimate conditions modeling assumed fully mature vegetation and its associated roughness characteristics. The final design incorporated 180 linear feet of coir lifts, 140 feet of bank regrading, and rock riprap interplanted with live willow stakes.       Regional Stormwater Quality Projects Client: Clean Water Services, Washington County, Oregon; Completed 1996 PWR staff, while working at KAI, led a team of hydrologists, hydraulic engineers, water quality experts, designers and environmental scientists to design three regional facilities on Beaverton's Butternut Creek, Johnson Creek, and Hedges Creek. The Butternut Creek Water Quality and Detention Facility was constructed in the summer of 1996. The facility serves to reduce historical flooding along Butternut Creek by temporarily storing and very slowly releasing storm water runoff. It will also improve the water quality of the creek through sedimentation, biofiltration, and bio-accumulation. This project was identified as a top priority in CWS' Butternut Creek Subbasin Strategy Plan (developed several years earlier by PWR staff) to help reduce flooding and improve water quality in the creek. This project received the 1997 Honor Award in the 1997 Portland/Vancouver Metropolitan Area Storm Water Design Award Competition. In addition to the surface water management benefits, construction of the Butternut Creek facility enhanced the natural resource value of the site by replacing mono-typic stands of Reed Canarygrass and Himalayan Blackberry with native upland and wetland vegetation. The site contains a diversity of wetland communities with regions of open water, emergent wetland, wet meadow, and forested wetland that enhance the wildlife habitat functions of an area that has been identified as a Significant Natural Resource in the Aloha-Reedville-Cooper Mountain Community Plan. The Brookhaven project on Beaverton's Johnson Creek (South) was constructed as part of the Davis Road improvements. The project involved the removal of an old beaver dam that had been reinforced by human intervention. The concern for water temperature violations in this water quality-limited waterway led to a unique pocket pond design that required significant regrading and sediment removal. In addition, an old dry detention basin was retrofitted to act as an active sediment removal facility for the creek. As part of the project, the severely eroding stream bank of a major tributary to Johnson Creek that flowed through the site was stabilized and restored using bio-engineering techniques. A severely silted culvert on this tributary was also replaced by a bridge to relieve local flooding and improve fish passage. The Hedges Creek project involved a significant amount of stream bank stabilization using bio-engineering and the retrofit of a large culvert inlet to provide flood reduction and sediment removal upstream of the well-known Hedges Creek Marsh. This facility has not been constructed due to a property dispute with an adjacent business.