Addendum to the Baseline Risk Assessment, Umatilla Depot Activity, Hermiston, Oregon.

The Addendum to the Baseline Risk Assessment (RA) has been prepared for the U.S. Army Environmental Center (USAEC), to discuss the results of additional investigations at existing RI study sites at Umatilla Depot Activity (UMDA), Hermiston, Oregon. The Addendum to the Baseline RA is prepared in support of the Remedial Investigation/Feasibility Study (RI/FS) of the follow-up field program at 16 UMDA RI/FS study sites to verify and characterize environmental contamination at the study sites in terms of potential impacts on human health under current and future land use conditions. This addendum assesses the potential present and future health risks and hazards posed by contaminants in soil and groundwater in the absence of remediation, and develops preliminary remediation goals for these media if remediation is determined to be required.