Department of Environmental Quality

DEQ Home/ Land Quality/ Environmental Cleanup/ ECSI/ Site Summary

Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 514, Umatilla Army Depot Activity

This report shows data entered as of September 19, 2021 at 7:11:59 AM

This report contains site details, organized into the following sections: 1) Site Photos (appears only if the site has photos); 2) General Site Information; 3) Site Characteristics; 4) Substance Contamination Information; 5) Investigative, Remedial and Administrative Actions; and 6) Site Environmental Controls (i.e., institutional or engineering controls; appears only if DEQ has applied one or more such controls to the site).  A key to certain acronyms and terms used in the report appears at the bottom of the page.

Note: DEQ may have posted online documents related to this site. If so, they would be available for viewing or downloading on ECSI Summary Page

Go to DEQ's Facility Profiler to see a site map as well is information on what other DEQ programs may be active at this site.

Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 514, Umatilla Army Depot Activity

Site Photos
Click to View Photo Picture Date Caption Size
View Photo 06/24/2001 ECSI 514 609 Kb
View Photo 06/24/2001 ECSI 514 523 Kb
View Photo 06/24/2001 ECSI 514 539 Kb
View Photo 06/24/2001 ECSI 514 503 Kb
View Photo 06/24/2001 ECSI 514 512 Kb
View Photo 06/24/2001 ECSI 514 571 Kb
View Photo 06/24/2001 ECSI 514 490 Kb
View Photo 06/24/2001 ECSI 514 526 Kb
View Photo 06/24/2001 ECSI 514 615 Kb
View Photo 06/24/2001 ECSI 514 578 Kb
View Photo 06/24/2001 ECSI 514 550 Kb
View Photo 06/24/2001 ECSI 514 608 Kb

General Site Information

Site ID: 514 Site Name: Umatilla Army Depot Activity CERCLIS No: 6213820917
Address: I-84 & Exit 178 Hermiston 97838
  County: Umatilla Region: Eastern
Other location information: The site is nearly divided in half by Umatilla and Morrow Counties and includes multiple sections.
Investigation Status: Listed on CRL or Inventory
Brownfield Site: No NPL Site: Yes Orphan Site: No Study Area: Yes
Property: Twnshp/Range/Sect: 4N , 27E , 16 Tax Lots:
  Latitude: 45.8287 deg. Longitude: -119.4274 deg.  Site Size: 19,728 acres
Other Site Names:
  see also ECSI# 3265, 5791, 5792, 5793, 5794, 5865
  US Army Depot - Umatilla Lagoons
  FUDS #F10OR0231

Site Characteristics

General Site Description:
Site History:
Contamination Information: (11/15/2002 BM/SRS) The Umatilla Army Depot Activity is a 19,728-acre facility formerly used for the storage, maintenance, and demilitarization (deactivation and/or disposal) of conventional munitions and weapons of various types. Currently, the Depot (now known as the Umatilla Chemical Depot) is used only for the storage of chemical weapons (i.e., nerve agent and mustard gas). The Depot opened in 1941. From the 1950s to 1965, approximately 85 million gallons of explosives-contaminated wastewater was discharged into two unlined lagoons. Soil and groundwater beneath the lagoons were contaminated. Explosives residues and lead were found in surface and subsurface soils at other locations throughout the Depot, from past disposal practices. In one 1,750-acre area, unexploded ordnance (bombs, mines, grenades, etc.) was on the surface and in subsurface soil. No contaminants migrated off the Depot property. In July 1987, EPA placed the site on the National Priorities List. In October 1989, a Federal Facilities Agreement was signed by EPA, DEQ and the Army. The agreement required the Army to investigate and clean up the site in accordance with CERCLA and with DEQ's Environmental Cleanup Rules. Eight operable units (study areas) were designated. Units 1 and 2 consisted of the soil and groundwater, respectively, beneath the Explosive Washout Lagoons. Unit 3 was the Explosives Washout Plant. Unit 4 was the soil around the former small arms Deactivation Furnace. Units 5 and 6 consisted of one active and several inactive landfills, respectively. Unit 7 was the 1,750-acre Ammunition Demolition Activity (ADA) Area. Unit 8 was a catch-all unit consisting of 32 distinct sites where hazardous substances may have been disposed of or released.
Manner and Time of Release: Munitions detonation, open burning, and burial. Discharges of wastewater to unlined lagoons. On-site disposal of various wastes in landfills. Time of release 1941 to present.
Hazardous Substances/Waste Types: Explosives (TNT, DNT and RDX), lead, unexploded ordnance (UXO), pesticides, and nitrates.
Pathways: The groundwater contamination plume from the explosive washout lagoons initially covered about 350 acres, but was contained entirely within the boundaries of the Depot. Also, the plume was present only in a shallow, unconfined aquifer about 45 feet below the surface. A deeper, confined aquifer is the primary source of domestic water in the region. Approximately 1,500 wells are within a 4-mile radius of the Depot. There are areas of surface soil contamination within the Depot, but access is controlled by a security fence and 24-hour-a-day guards. Unexploded ordnance is known to exist in a portion of the Depot, and poses a significant safety threat to users of the area and to trespassers.
Environmental/Health Threats: Contaminated soils and groundwater on-site. Also, unexploded ordnance exists in a portion of the site. However, access is strictly controlled by fences and armed guards.
Status of Investigative or Remedial Action: (11/15/2002 BM/SRS) Records of Decision (RODs) have been signed for all eight operable units. The explosives-contaminated soils of Unit 1 (15,000 tons) was excavated, biologically treated to remove TNT and RDX, and placed back into the excavation. The cleanup was completed in 1996. For Unit 2, three extraction wells were installed to pump 1,500 gallons of contaminated groundwater per minute through a granular activated carbon treatment system. Treated groundwater is reinjected into the ground. The groundwater treatment system began operating in 1997 and is expected to operate for up to 30 years (i.e. until 2027). For Unit 3, the Explosives Washout Plant was steam cleaned to remove residues of explosives, then demolished in 1996. No further action is necessary. For Units 4, 7, and 8, the selected remedy was excavation of the contaminated soil, solidification/stabilization of the excavated soil with cement, and placement of the treated soil in the on-site active landfill (Unit 5). In addition, for Unit 7, unexploded ordnance (UXO) was removed from the surface. These cleanups were completed in early 1997. No further remedial action was determined to be necessary for Units 5 and 6. Subsurface clearance of UXO from Unit 7 has not yet been conducted due to a dispute between the Army and EPA. Pumping of contaminated groundwater beneath Unit 2 has reduced the size of the groundwater plume from 350 to 180 acres.
Data Sources:

Substance Contamination Information

Substance Media Contaminated Concentration Level Date Recorded
CYCLOTRIMETHYLENETRINITRAMINE Groundwater 6800 ppb (up to)  
DINITROTOLUENE,2,6- Groundwater 5.3 ppb (up to)  
LEAD Soil 7300 ppm (up to)  
TRINITROTOLUENE,2,4,6- Groundwater 3900 ppb (up to)  
TRINITROTOLUENE,2,4,6- Soil 88000 ppm (up to)  

Investigative, Remedial and Administrative Actions

Action Start Date Compl. Date Resp. Staff Lead Pgm
REMEDIAL ACTION  (Primary Action) 06/20/1994   SRS
View Full Report Showing Action History

Key to Certain Acronyms and Terms in this Report:

For more information on this site contact the Eastern regional office.