The Coast Guard proposes the establishment of two Regulated Navigation Areas (RNA) at the Port of Portland Terminal 4 on the Willamette River in Portland, Oregon. The RNAs are necessary to preserve the integrity of engineered sediment caps placed within Slip 3 and Wheeler Bay at the Portland Harbor Superfund Site as part of a removal action at that site. The RNAs will do so by prohibiting activities that could disturb or damage the engineered sediment caps in that area.
See http://www.fedthread.org/fr/document/E9-30935/