Department of Defense (DOD) Sites

U.S. Army Yuma Proving Grounds

Community Involvement Activities Public Health Impact Site Hydrogeology
Contacts Public Meeting Calendar Site Map
Contaminants Public Notice Calendar Site Status Update
Information Repository Site History

Yuma Proving Grounds Bunker

The Yuma Proving Ground (YPG) is located 23 miles northeast of Yuma, Arizona, and occupies approximately 870,000 acres in Yuma and La Paz counties. The YPG (site) is bounded on the west by the Colorado River and on the south by the Gila River. The U-shaped site is approximately 1,309 square miles in area and extends approximately 60 miles north-south and 50 miles east-west.

Site Status Update:

ADEQ approved the “No Further Action” Final Decision Documents for YPG sites: 13b-e, 23, 25, 26 and 45.

Discussions between ADEQ and YPG regarding the Chemical Waste Holding Tank Near Building 2060 (YPG-02) site resulted in the determination for the need of an additional boring in the area of the former UST to delineate impacts to soil in the subsurface. A Technical Memo work plan describing the soil boring at the site was approved, and field work to determine subsurface lithology and collect soil samples took place in July 2014. ADEQ will make a decision on the “No Further Action” request based on the results of the soil sampling.

A Confirmation Soil Sampling report describing the results of soil sampling and a summary of groundwater monitoring activities was submitted to ADEQ for YPG-10, Fuel Bladder Test Site. A Feasibility Study will be created to present various remediation options in order to address the remaining fuel-impacted soils and groundwater at the site.

In February 2014 ADEQ met with US Army YPG representatives and the US Army Corps of Engineers (USACE) for a site visit and meeting to discuss the West Environmental Test Area (YPG-31) and Former Waste Disposal Area (YPG-32) sites. USACE indicated that they will take the lead on the RI/FS for both of the sites with input from ADEQ.

Community Involvement Activities:

In their commitment to involve the community in the restoration process, the U.S. Army Garrison, YPG, (USAGYPG) formed a Restoration Advisory Board (RAB), with the first RAB meeting held on June 7, 2010. The meeting was attended by community members, city and county officials and other stakeholders. The RAB meets on a regular basis. The USAGYPG provides a notice of availability with a 30-day public comment period for proposed DDs for YPG sites. The notice, along with a brief analysis of the document, is published in the major local newspaper of general circulation and on the internet site This is done in accordance with Comprehensive Environmental Response Compensation and Liability Act (CERCLA) regulations that require public participation opportunities prior to the completion of the DD (40 CFR 300.430[f][3]), which, if appropriate, may cause the proposed remedy for the DD to be modified prior to the signing of the final DD. 

Site History:

1942 - 1943: The YPG was first used by the military in 1942 for training desert troops. The mission changed in January 1943, when the site began to be used as a testing ground for bridges and river crossing equipment, boats, vehicles, and well drilling equipment under the designation of Yuma Test Branch, Corps of Engineers.

Aircraft Armament System Testing

1947 - 1950: In October 1947, the site was but was later deactivated in January 1950 because of the military austerity program.

1951 - 1962: The YPG was again reactivated in April 1951 as Yuma Test Station for desert environmental testing of equipment ranging from tanks to water purification units, and was assigned to the U.S. Army Material Command and renamed YPG in 1962. YPG’s current mission is to use advanced technology to carry out sophisticated tests of aircraft armament systems, air delivery systems, and tank-automotive equipment.

1965 - 1975: Several removal actions have been conducted at YPG, as well as interim remedial action involving Soil Vapor Extraction (SVE) at Building 506 underground storage tank release, and at the Fuel Bladder Test Site (FBTS). This site was designated for immediate investigation by YPG due to the determination that up to 500,000 gallons of fuel may have been released at the site between 1965 and 1975. Analyses of groundwater samples from monitor wells installed during ongoing investigation of the site have shown evidence of petroleum and petroleum by-products.

1980 - 1988: In 1980, YPG submitted an application to the Arizona Department of Health Services (ADHS) for a Resource Conservation and Recovery Act (RCRA) permit as a treatment, storage and disposal facility, with subsequent amendments in 1986 and 1988. Several SWMUs were operated under the permit.

1993 - 1996: In July 1993, YPG initiated discussions with ADEQ with regards to the investigation of YPG’s top ten SWMUs. In 1996, ADEQ and YPG agreed on the management strategy for the SWMU’s which will involve investigation and cleanup under the CERCLA.

1997: The U.S. Environmental Protection Agency (EPA) conducted a RCRA facility assessment site inspection of the SWMUs at YPG and recommended response action for 51 SWMUs and six areas of concern, including 14 of the 19 SWMUs.

1998 - 2002: The U.S. Army initiated a remedial investigation (RI) of YPG sites in 1998 as part of the DoD Installation Restoration Program (IRP) and identified 19 units for investigation under the RI/feasibility study (FS) CERCLA process. The sites were organized into four operable units based on their proximity to the main post at YPG and/or opportunities for rapid and similarity for cleanup. The RI report was finalized in July 2002.

The YPG did not qualify for placement in the National Priorities List, but regulatory oversight is provided by ADEQ under the IRP.

2000 - 2006: Environmental investigations and cleanup continued at YPG under the auspices of the Army's IRP.  At the Former Waste Disposal Area (FWDA), a fence to limit access to the site was erected as an engineering control/interim remedial action for the site. SVE technology has been ongoing at the FBTS since July 2000. 

2004: Reports for the implementation of lab and feasibility testing of in-situ ozone treatment of petroleum hydrocarbons for Building 560, RI for selected sites, as well as the quality assurance project plan addendum No. 4 have been reviewed and approved by ADEQ.

2005:ADEQ approved a DD proposing remedial action for vadose zone treatment at the FBTS.

Aerial View of Yuma Proving Grounds

2007: ADEQ and the Army began negotiations to address ADEQ’s concerns about remedial action DDs for several of the SWMUs at YPG. For some sites at YPG, data was sufficient to indicate that a remedial response was warranted. 

Groundwater monitoring continued at the FBTS, the Old Chemical Laboratory building (Building 2500), Building 506, the West Environmental Test Area, and the FWDA.

At the FBTS remedial construction was completed, an Air Quality Permit was finalized, and in late August full-scale SVE using Internal Combustion Engine (ICE) technology was initiated. The system operated for approximately six weeks before it was turned off in early October.

A full-scale SVE system utilizing three dual ICE units has operated at the site intermittently since January 2007.

2008: The ICE SVE system at the FBTS was restarted in April. With the estimated 52,000 gallons of fuel removed during the pilot study/interim remediation (prior to August 2007 when the full-scale system came on-line), the total volume of fuel removed from beneath the site as of September 18th, was approximately 104,500 gallons.

2009: From April 2008, when the soil remediation work started, until June 2009, there were 132,000 gallons of fuel removed from the FBTS. Also, the final DD for site YPG-11 (the Former Pesticide Mix/Storage Facility at Building T-430) was submitted to ADEQ for approval and signature.

2010: From April 2008, when the soil remediation work started, until June 30th, there were 155,773 gallons of fuel removed from the FBTS. The final DD for site YPG-11 was approved and signed by ADEQ. The final DD for site YPG-11 (the former Pesticide Mix/Storage Facility at building T-430) was approved and signed by ADEQ. The remedy is capping with asphalt paving and institutional controls.

2011 - 2012: The final DD for site YPG-03 (Septic Tank/Leach Field near Building 2060) and YPG-13f (Septic Tank/Leach Field near Laguna Army Airfield and Building 3021) was signed by ADEQ on December 22, 2011. A five year review (FYR) was conducted March 2012 for YPG-10 and YPG-11. ADEQ submitted comments to DD for YPG-45; YPG-13b-e, -23, -25, & -26; and YPG-02. ADEQ is working with the U.S. Army, YPG on the Removal Action and Land Use Controls Project at the Military Munitions Response Program site (YPG-002-R-01, aka. Easter Services Hill). Projection completion date is November 2014.

2013: ADEQ submitted comments on the work plan and final interim remedial action completion report for the Fuel Bladder Test Site (YPG-10). The final draft supplemental investigation report for Building 506 Underground Storage Tanks (YPG45) was approved by ADEQ on Oct. 23, 2012. A final supplemental investigation report was provided to ADEQ for the West Environmental Test Area (YPG-31) for comment. Recommendations included a work plan to implement field activities.

As a part of the Military Munitions Response Program, two reports were submitted to ADEQ for the Mortar Impact Area (YPG-002-R-01) to assess actions concerning the non-time critical removal actions and land use controls for this site. ADEQ had several comments on both documents. Recommendations are expected to be implemented in the future.

2014: Planned RI activities for YPG-32 include characterizing the trenches and assessing subsurface soil conditions at the site. The RI for YPG-31 will be extensive due to the historical usage of the site and the storage of Chemical Warfare Agents (CWA) and CWA-related munitions. One or more burial trenches are potentially located on the site which will need to be sampled and possibly excavated. A bunker with unknown contents will also require investigation and possible inventory of its contents.


The current contaminants of concern at the site include petroleum hydrocarbons, volatile organic compounds (VOCs), semi-VOCs, and metals, in addition to propellants, explosives, and pyrotechnics (PEP), CWA and CWA-related munitions. Contaminants of concern at the site may change as new data become available.

Public Health Impact:

Most of the contaminated sites are fenced and public access is prohibited. Contaminated groundwater is limited to the site boundaries. There is no risk to the public drinking water supply wells of Yuma.

Site Hydrogeology:

The geology of YPG is characterized by wide, gently sloping plains formed by late Tertiary and Quaternary age basin-fill deposits broken by sharply rising mountain ranges composed mainly of Cretaceous and Quaternary age intrusives and volcanics.

Groundwater exists in two aquifers beneath YPG; a shallow unconfined aquifer in alluvial deposits, and a deep aquifer in consolidated volcanic rocks. The depth to groundwater ranged from 30 feet below ground surface (bgs) in Well X, which is adjacent to the Colorado River near the main administration area, to 750 feet bgs in Well M at the Castle Dome Heliport. Potentiometric surface maps indicate the direction of groundwater flow is southwest to the Colorado and Gila Rivers. The groundwater gradient (i.e., change in water level with respect to distance) is about four to five feet per mile (ft/mi) upgradient of the major pumping wells, and less than about four ft/mi near the rivers. Near the rivers the groundwater elevation becomes shallower, merging with subflow of the rivers, and may be within ten feet of the surface in flood plain deposits.

Hydraulic conductivity ranges from 83 to 902 gallons per day per square foot (gpd/ft2) for the alluvial wells, 56 gpd/ft2 for the consolidated rock, and 1,245 gpd/ft2 for the floodplain deposits. Reasonable values for the storage coefficient ranged from ten to 15% for the alluvium, 20 to 30% for the flood plain deposits, and one to 5% for the consolidated rock.


Name Phone/Fax E-mail
Sara Benovic, ADEQ Project Manager (602) 771-4248*/ (602) 771-4138 fax

*In Arizona, but outside the Phoenix area, call toll-free at (800) 234-5677.

Information Repository:

Interested parties can review site information here on this page and at the ADEQ Record Center located at 1110 W. Washington Street, Phoenix, Arizona. Please contact (602) 771-4380 or (800) 234-5677 ext. 6027714380 for hours of operation and to schedule an appointment.

Site Map

Community Relations Plan (CRP)