Sediment Cap at McCormick and Baxter - Portland, OR

The McCormick and Baxter site is presently listed as a Superfund site under the Comprehensive Environmental Response, Compensation, and Liability Act. Over the past several years, a number of inspections, investigations, and remedial actions have been performed at the site. Most notably, in 2003 work on a subsurface barrier wall was completed, surrounding the primary waste areas within the upland portion of the 43-acre property.

In July of 2004 work on this contract, named as the McCormick and Baxter Sediment Cap project, which consisted of site cleanup and the installation of a sediment cap for the McCormick and Baxter Superfund Site in Portland, Oregon.

Included within the scope of work for this project was the creation of a sediment cap, installation of 1.2 million pounds of organophyllic clay over 21 acres, armoring and turf reinforcement, and demolition of various materials throughout the site. Demolition and cleanup included removal of over 750 pilings and dolphins spread throughout the site, demolition of a 180' creosoting dock, and removal of all associated dock supports and bulkhead. In Willamette cove to the northwest, a partially submerged wooden barge was removed, demolished and disposed of, and nearby concrete structures and debris were demolished and removed.

The sediment cap is approximately 25 acres in size; 13.5 acres of this is armored by articulated concrete block, and the remaining 11.5 acres of this are armored with 6-inch minus rock. Any existing non-aqueous phase liquid (NAPL) migration seeps have been covered with organophyllic clay, a material design to adsorb these compunds. The river banks are now upsloped with clean soil fill and topsoil placed to support plantings, reinforced by a turf reinforcement mat between the soil layers.

Project Performance

Although an extremely large and complex project which involved extensive in-water as well as upland work, the project and the numerous large additions to the scope of work were completed in just over 4 months.