River Infrastructure Locating and Assessment

Pierce County is seeking a Geotechnical Engineering firm that demonstrates knowledge and expertise in locating hidden, obscured, and buried flood risk reduction assets, such as revetments and levee features, for Phase 1 of a "State of the System" study. The Consultant will use repeatable, scalable, and defensible methods that can be applied to similar flood risk reduction assets along the managed river system. The proposed work will be conducted along selected segments of the Puyallup and White Rivers.

Pierce County Planning and Public Works is responsible for the ownership, operation, and maintenance of over 70 miles of riverine flood risk reduction infrastructure in the form of levees and revetments. The majority of the infrastructure was constructed between 1915 and the mid-1960’s. The levee prisms or levee core were constructed of earthen materials. The earthen materials primarily consisted of in-situ river-wash silts and gravels. The levee prism was then typically armored with concrete panels to protect the levee prism. Revetment were constructed by shaping the bank line and armoring with concrete panels. The concrete may or may not contain steel reinforcement. Over time portions of the infrastructure have become hidden, obscured or buried due to natural river processes such as vegetation growth and sediment deposition. Other causes may be attributed to encroachments from development activities.

Pierce County Planning and Public Works is starting a process to initiate a “State of the System” study to better understand flood risk reduction infrastructure condition and performance along the managed riverine system. A critical dependency of that effort is accurate knowledge of the location of the existing flood risk reduction assets. Several segments of the flood risk reduction assets are currently hidden, buried, undocumented, or poorly represented in existing records. Without first locating, documenting, and assessing these assets, a “State of the System” effort cannot be successful or credible.