PORTLAND HARBOR COMPARATIVE SAMPLING subsurface sediment sampling of the Willamette River Post Office Bar in Portland, Oregon. The sampling was conducted in support of a comparative sampling study being spearheaded by the U.S. Army Corps of Engineers (USACE), in which two methods of characterizing potential dredge material were contrasted. Sediment cores were collected using a vibra-core sampler. Discrete samples (A and Z layers) from 30 sample locations were collected and submitted for analysis. In addition, sediment was composited across all discrete samples (for both layers) to generate site-wide composite samples, which were also submitted for analysis. Results between the discrete and composite samples were compared.