Coastal Remedial Design and Shoreline Restoration
Client: USACE Kansas City District
CTI provided remedial design services at the Manchester Annex Superfund Site located in Kitsap County, Washington, on the shore of the Puget Sound. The former landfill portion of the site, historically owned and operated by the U.S. Navy for submarine net maintenance, fire training, and waste disposal activities had eroded into the adjacent intertidal lagoon area. Under this Task Order, CTI completed remedial design modifications and construction to address erosion damage to the Landfill Shoreline Protection System (SPS) which protects the landfill cap and cover system from wave action, prevents tidal flushing, and provides fish spawning habitat. Remedial design modifications and construction work included:
- Detailed engineering survey and analysis of current conditions and tidal erosion;
- SPS design modifications including restoration of 1,050 lf of beach to original as-built design vertical elevations and slopes including rock revetment taper and gravel/cobble beach nourishment during dry conditions at low tide;
- Drainage system upgrades including culverts and manholes to promote positive landfill surface water drainage;
- Landfill cover vegetation, perimeter fence, and road pavement improvements;
- Culvert collapse feature inspection; and
- Land and aerial surveys to document as-built location and elevation details for SPS repair work.
Collaboration with USACE Kansas City and Seattle Districts, USEPA, and NOAA focused on key areas of coastal shoreline processes, potential contaminant migration pathways, drainage, sustainability, and the landfill cover system. Based on the successful completion of this TO for landfill SPS modifications, CTI was awarded design and construction of additional shoreline features and realignments to restore the shoreline to pre-existing conditions.