Construction Update 8/12/16

Despite summer rainfall, the project is on schedule. Work on the north setback levee is proceeding well with completion of this element expected by the end of August. This is one of three setback levees designed to keep daily tides off adjoining farm land that is outside the project area. The approximate 2 ½ miles of these levees are specially designed with a clay-type soil core. Once fully dried and compacted, the core will prevent water infiltration through the levee that might otherwise cause erosion and levee failure. The levee core will be capped with a granular material, also available on site, and graded to a 1/5 slope to minimize erosion during overtopping flood events. The three setback levees are in locations that enable efficient flood discharge over the remainder of the overland flow corridor.

The City of Tillamook, one of the many project partners, is presently contemplating an expansion of a planned parking area on the so-called “containment cell” that is being constructed along the north side of Front Street between Douglas Avenue and an old mill pond channel located west of Cedar Avenue. The proposed revision would accommodate parking for 30 vehicles instead of the 14 contemplated in the initial design. The lot will be available for recreational access to Hoquarten Slough and the surrounding area.  A decision by the City on the possible expansion is dependent on a revised bid proposal from the project contractor, Thompson Brothers Excavating, Inc.

In any event, parking atop the containment cell is a creative use for the earthen berm that will be used to encapsulate the slightly contaminated soils that remain on the project site from the two veneer mills that operated from about 1920-1965. The contaminants in the soil consist of remnant motor oil and machine lubricants used at the mills. Although the contamination levels do not pose a risk to humans, the worst of the soils will be transported to a licensed treatment facility in Hillsboro.  The lesser contaminants will be encased within the cell and monitored long term. Currently those contaminants are uncontained at the site and pose a risk to the environment.

Further questions may be directed to Project Manager Paul Levesque at 503 842-1809.

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