MOUNT SAINT HELENS SEDIMENT RETENTION STRUCTURE CREST RAISE

Description of Requirement: The project purpose is to The U.S. Army Corps of Engineers, Portland District, has a requirement to construct an increased level of sediment retention structure providing additional storage and allowing existing river flows. The work includes mobilization/demobilization, river diversion, rock excavation, rock foundation preparation including placement of dental concrete, placement of roller-compacted concrete, outlet works sealing, and incidental related work. This effort is to include all associated works required and described within this Contract package

Project Background. The Sediment Retention Structure was constructed in the Late 80's to store the sediment coming off the avalanche area so that the sediment does not flow down to the low Cowlitz River. The main objective for the project is to keep the level of Protection on the levee systems from Castle Rock to Lexington. There has already been one crest raise in 2012 and this will be the second of three planned crest raises.

The project purpose is to construct an increased level of sediment retention structure providing additional storage and allowing existing river flows. The work includes mobilization/demobilization, river diversion, rock excavation, rock foundation preparation including placement of dental concrete, placement of roller-compacted concrete, outlet works sealing, and incidental related work. This effort is to include all associated works required and described within this Contract package.

The work will be located at the Sediment Retention Structure on the North Fork Toutle River in Cowlitz County, Washington, off of Highway 504. Contractor access to the work site will be from gravel access roads on the dam site, the gravel roadway on top of the embankment dam, the top of the concrete outlet works structure, and a paved roadway on the spillway approach pier west of the existing spillway crest.

Purpose: The project purpose is to construct an increased level of sediment retention structure providing additional storage and allowing existing river flows. The work includes mobilization/demobilization, river diversion, rock excavation, rock foundation preparation including placement of dental concrete, placement of roller-compacted concrete, outlet works sealing, and incidental related work. This effort is to include all associated works required and described within this Contract package.

The work will be located at the Sediment Retention Structure on the North Fork Toutle River in Cowlitz County, Washington, off of Highway 504. Contractor access to the work site will be from gravel access roads on the dam site, the gravel roadway on top of the embankment dam, the top of the concrete outlet works structure, and a paved roadway on the spillway approach pier west of the existing spillway crest