Waste Programs Division: Hazardous Waste Management: U.S. Army Garrison Yuma Proving Ground

U.S. Army Garrison Yuma Proving Ground (USAGYPG)
EPA ID NO. AZ5 213 820 991

Facility Location and Description

The USAGYPG installation is located in a remote area of southwestern Arizona, bordered on the west by the Colorado River. It lies 23 miles northeast of the city of Yuma along the U.S. Highway 95, between Interstate Highways 8 and 10. USAGYPG is one of Department of Defense's (DoD's) largest installations, and encompasses an area of approximately 1300 square miles. The global position of the facility is latitude 32° 57' 12-22" North and longitude 114°15'40-51" West.

USAGYPG is involved in testing weapon systems of all types and sizes. Equipment and munitions evaluated at the installation consist of medium and long-range artillery; aircraft target acquisition equipment and armament, armored and wheeled vehicles, a variety of munitions, and personnel and supply parachute systems. Testing programs are conducted for all U.S. military services, friendly foreign nations, and private industry. USAGYPG is also the Army's center for desert natural environment testing, and the management center of cold weather testing at the Cold Regions Test Center (Alaska).

USAGYPG operates a munitions treatment facility (MTF) in accordance with a hazardous waste treatment permit issued by ADEQ in 2007. The facility is used for the destruction of unserviceable, outdated, or obsolete munitions generated at USAGYPG. The explosive ordnance treated at the MTF is categorized as reactive and ignitable hazardous waste. The methods of treatment are Open Burning (OB) and Open Detonation (OD), OB & OD are conducted within the Munitions Treatment Facility on OB pads and in OD pits. USAGYPG is a large quantity generator of hazardous waste.

Corrective Action Activities at USAGYPG

In accordance with Part IV.C of its hazardous waste permit, USAGYPG is required to address corrective action as necessary to protect public health and the environment from releases of hazardous waste, including hazardous constituents, from any solid waste management unit (SWMU) at the facility. ADEQ is currently managing USAGYPG's corrective action activities at the:

  • Kofa MTF Inactive Hazardous Waste Treatment Units
  • Muggins Mountain Former OB/OD Facility
  • Six Inactive Landfills

Kofa MTF Inactive Hazardous Waste Treatment Units

The four inactive SWMUs located on the Kofa MTF which are undergoing closure are:

  • Burn on Ground Area
  • Abandoned South Pad
  • Abandoned North Pad
  • Trash Trench Area

Site Characterization History

Site characterization of the inactive units was initially performed in 2006. It involved collection of surface and sub-surface soil samples at 425 locations, and characterization of these samples for metals, SVOCs, perchlorates and explosives. A second round of sampling was performed in 2012 to identify the horizontal and vertical extent of contamination. It involved collection and characterization of 81 soil samples.

Solid Waste Management Units at KOFA

  • Burn on Ground (BOG) Area
    The BOG area was used for open burning on the ground from 1974 to 1986. In 1986, open burning operations were transferred to the newly constructed North and South Pads and all treatment operations at the BOG area were discontinued. Site characterization identified lead and beryllium as contaminants of concern. Lead exceeded its remediation goal (RG) at 15 locations with a maximum recorded concentration of 6360 mg/kg. Beryllium exceeded its RG at one location where its concentration was 81 mg/kg.
  • Abandoned South Pad (ASP)
    The ASP is a concrete burn pad constructed in 1986 to allow open burning in steel pans. It is roughly 50 feet in length and 15 feet in width with a short concrete berm around its edges. ASP was damaged in 1987 due to an accidental detonation and its use for open burning was terminated. Site characterization demonstrated exceedances of lead, 1,3-dinitrobenzene, and perchlorate. Lead exceeded its RG at 18 locations with a maximum concentration of 6,790 mg/kg, while 1,3-dinitrobenzene exceeded its RG at one location at which its concentration was 68 mg/kg. Perchlorate concentrations were more than its RG at 2 locations. The maximum perchlorate concentration recorded was 2020 mg/kg.
  • Abandoned North Pad (ANP)
    The ANP is a concrete burn pad constructed in 1986 to support open burning in steel pans. It is roughly 50 feet long and 15 feet wide. Use of this pad was discontinued in 2000 because it was considered too small for handling the volumes of explosives planned for open burns. Site characterization revealed lead as the only contaminant of concern at this site. The remediation goal for lead was exceeded at 21 locations with the maximum lead concentration being 5,770 mg/kg.
  • Trash Trench Area
    The trash trench is an excavated area roughly 280 feet in length, 30 feet in width, and approximately 12 to 15 feet in depth. It was used for burning ammunition boxes and explosives. Wood shipping containers, treated with pentachlorophenol, were also burned at this location in 1984. Site characterization yielded two locations at which soil RDX concentrations exceeded the remediation goal. The maximum RDX concentration was 1,300 mg/kg.

Closure of the Inactive Hazardous Waste Treatment Units

ADEQ is currently reviewing USAGYPG's Closure Plan for the Kofa MTF inactive units. Clean closure of the SWMUs will be a two-step process. The first phase will involve excavation and disposal of contaminated soil and concrete pads. The second step will involve confirmatory sampling to ensure that the concentrations of COCs in the remaining soil does not exceed the RGs.

Muggins Mountain Former Open Burn/Open Detonation (OB/OD) Facility

Muggins Mountain OB/OD facility was operated by USAGYPG during two time periods. From 1952 to 1974, it served as the primary OB/OD facility for USAGYPG. From 1985 to the late 1990s, USAGYPG initiated a munitions recovery program to uncover and demolish munitions that were buried on-site during the 1952 to 1974 period. The facility is comprised of three SWMUs:
  • YPG-35a - General Muggins Mountain Open Burn/Open Detonation Area
  • YPG-35b - Burial Trenches Area
  • YPG-35c - Open Burn/Open Detonation Area

Corrective Measures Study (CMS)

Upon completion of the RFI, USAGYPG will perform a CMS. The CMS will compare various remedial alternatives based on effectiveness, implementability and cost in order to identify the best alternative for protection of human health and environment from contamination at the Muggins Mountain Former OB/OD Facility.

Solid Waste Management Units at Muggins Mountain

  • YPG-35a - General Muggins Mountain Open Burn/Open Detonation Area
    The YPG-35a site encompasses the former OB/OD facility area with exception of the Burial Trenches Area (YPG-35b) and the OB/OD Area (YPG-35c). It is approximately 360 acres in size. The RFI identified widespread presence of munitions debris (MD) and munitions and explosives of concern (MEC) at YPG-35a. No burial trenches were detected at YPG-35a.

  • YPG -35b - Burial Trenches Area
    The Burial Trench Area encompasses approximately 12 acres. Site characterization identified one large open trench and ten burial trenches. The areas of the anomalies suspected to be burial trenches cover approximately 50-percent of the 12 acres. The large open trench at the site is approximately 300 feet in length, 25 feet in width, and 30 feet in depth, and is located in the northwestern portion of YPG-35b. Miscellaneous MEC/MD items are currently present within the trench. The trench may also include non-MEC related scrap such as non-explosive wax and fillers, wooden boxes, banding, nails, scrap metal, wire, and municipal waste. A berm on the northwest side of the trench, constructed in 2006, partially surrounds the trench and prevents rainwater runoff from entering the trench The ten suspected burial trenches are located to the northwest and southeast of the large open trench. Due to the risk of explosion the contents of these 10 trenches were not sampled and are unknown.
  • YPG-35c - Open Burn/Open Detonation Area
    The YPG-35c site includes open detonation pits, buried trenches, burn on ground (BOG) Area, and the white phosphorus (WP) area. The open detonation pits area is approximately 7.5 acres in size, and contains numerous small detonation pits. Two buried trenches are possible dunnage pits, and a third dunnage pit remains open and is relatively empty. The BOG Area was used for burning loose propellant. The WP Area consists of five square metal pads (4 feet by 4 feet in dimension), with a thickness of 6-8 inches. The visual WP residue present on the ground covers an area of approximately 40,000 square feet. Based on the site characterization, the COCs at YPG-35c include 2,4-Dinitrotoluene, 2, 6-Dinitrotoluene, nitroglycerine, and lead.

Inactive Landfills at USAGYPG

USAGYPG is currently investigating six landfills:

  • YPG-27
  • YPG-28
  • YPG-29
  • YPG-141
  • YPG-143
  • YPG-178

The RFI activities at YPG-27, -28, -29, -141, and -178 involved removal of surface debris, followed by a geophysical survey, excavation of test pits, drilling of soil borings, and collection and characterization of surface and sub-surface soil samples. The soil samples were analyzed for VOCs, SVOCs, metals and explosives.

  • Inactive Landfill YPG-27
    The YPG-27 site is located approximately 3 miles south-southeast of the Main Administrative Area, and south of Laguna Dam Road. It covers an area of approximately 5 acres. Disposal activities at this landfill occurred between 1950 and 1964. During the RFI 16 test pits were excavated and 26 surface and sub-surface soil samples were collected and analyzed. Four pits contained solid waste comprised of wood, glass, rusted metal, cinder block, wire, pipe, bottles, and rusted metal debris. Waste depths range from four to twelve feet. Although lead, and arsenic were above their RGs at two pits, there was no evidence of hazardous waste disposal at this landfill. USAGYPG will be performing a corrective measures study to identify a remedial option which ensures that the solid waste contamination at YPG-27 does not pose a threat to human health and the environment.
  • Inactive Landfill YPG-28
    The YPG-28 site is located approximately half- mile north of the Main Administrative Area, and is southeast of the Imperial Dam. The site is approximately 2,500 square feet in size. Disposal activities at this landfill reportedly occurred in the late 1940s. During the RFI 5 test pits were excavated and seven surface and sub-surface soil samples were collected and analyzed. One pit contained solid waste comprised of broken glass, decomposed aluminum, and pieces of concrete. Waste depth in the pit was four feet. There was no evidence of hazardous waste disposal at this landfill. USAGYPG is in the process of implement remedial action at YPG-28 which will involve removing the contaminated waste from the site, and disposing it of at the USAGYPG solid waste landfill.
  • Inactive Landfill YPG-29
    The YPG-29 site is located on the Kofa Firing Range east of US Highway 95, approximately 1.25 miles south-southeast of the Kofa Fire station, and within 200 yards of the new Kofa sewage lagoon. The site encompasses an area of roughly 5 acres. Disposal activities at the site occurred during the late 1960s. During the RFI 22 test pits were excavated and 38 surface and sub-surface soil samples were collected and analyzed. Seven pits contained solid waste comprised of glass and plastic bottles, wood, metal banding, small pieces of tar, metal pipe, aluminum cans, Styrofoam cups, food packaging, children's toys, and clothing items. Waste depths range from one to five feet. The RFI confirmed that hazardous waste disposal did not occur at this landfill. USAGYPG is currently performing a CMS to identify a remedial alternative that ensures that the solid waste at the landfill does not pose a threat to human health and the environment.
  • Inactive Landfill YPG-141
    YPG-141 is located approximately 1 mile northeast of the Main Administrative Area. It is north of Barranca Road and west of the Laguna Army Airfield. The site is roughly 4 acres in size. Disposal activities reportedly occurred at the site between 1964 and 1967. During the RFI fifteen test pits were excavated and 32 surface and sub-surface soil samples were collected and analyzed. Seven pits contained solid waste comprised of glass and plastic bottles, burned paper and wood, rusted metal objects, pipe, partially decomposed aluminum cans, Styrofoam cups, food packaging, fabric, and ceramics. Waste depths range from seven to ten feet. Although lead and arsenic were detected above their RGs at three pits, there was no evidence of hazardous waste disposal at this landfill. USAGYPG is currently performing a CMS for YPG-141 to identify a remedial alternative that ensures that the solid waste at the landfill does not pose a threat to human health and the environment.
  • Inactive Landfill YPG-143
    The RFI at YPG-143 confirmed that the site was not a landfill since solid waste, hazardous waste, hazardous constituents, or hazardous waste degradation products were not found on site. Consequently, no further corrective action is required. ADEQ requested USAGYPG to submit a Class 1 Permit modification request (requiring prior Director approval) modifying Part VI of the Permit to reflect that YPG-143 has been investigated and that ADEQ has acknowledged the completion of corrective action at this SWMU.
  • Inactive Landfill YPG-178
    The YPG-178 site is located approximately 2 miles south-southeast of the Main Administrative Area. It consists of multiple surface and shallow subsurface disposal sites located approximately 200 feet apart. These areas have been designated YPG-178a and YPG-178b. The YPG-178a site is approximately 1.68 acres in size, and YPG-178b is roughly 0.76 acres. Disposal activities at the landfill reportedly occurred during the 1960s and1970s. During the RFI 10 test pits were excavated and 31 surface and sub-surface soil samples were collected and analyzed. Six pits contained ash with wood, glass, wire, bottles, burnt paper and rusted metal debris with waste zone depths ranging from 3 to 4.5 feet. There was no hazardous waste disposal at this landfill. USAGYPG will be performing a corrective measures study in order to identify a remedial alternative which ensures that the contamination at YPG-178 does not pose a threat to human health and the environment.

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