Waste Programs Division: Hazardous Waste Management: U.S.M.C. Barry M. Goldwater Range, West Segment

Barry M. Goldwater Range, West - Munitions Treatment Range
U.S. EPA ID No: AZR 000 037 382

Facility Location

Section 33, Township 10 South, Range 22 West of the Gila and Salt River Meridian, Maricopa County, Arizona.
Lattitude 32° 31' 09" North, 114° 32' 14" West
12 miles southwest of Marine Corps Air Station main base

Facility

The Barry M Goldwater Range (BMGR) consists of a wedge-shaped area in the extreme southwestern corner of Arizona and lies within southern Yuma County and extends eastward into Maricopa and Pima counties in southwestern Arizona (see Figures 1 and 2, below). The BMGR has been used for training pilots in aerial and air-to-ground combat since 1941. It is highly valued for its year-round flying weather and expansive, unencumbered air and land space that can accommodate a variety of military training needs. The west portion of the BMGR is operated by the Marine Corps Air Station Yuma (MCAS Yuma).

The Munitions Treatment Range (MTR) is located approximately 12 miles southeast of the MCAS Yuma Main Base. The MTR, accessed by an unimproved road approximately one-mile long, consists of a reserved area, 1,000 meters on each side, located approximately three miles inside the western boundary of the BMGR. Three-strand barbed wire and razor wire coils surround the perimeter of the MTR. The access road divides the MTR into east and west portions.

  • Figure 1 - Area Location Map -- (PDF)
  • Figure 2 - Site Map -- (PDF)

Current Waste Management Activities on BMGR

Inventories of military ordnance items are maintained at various military installations. Because ordnance items held in military readiness stockpiles are subject to deterioration and obsolescence, action is required to safely remove and thermally treat these items. Other explosive wastes may be generated from training operations on the BMGR or at manufacturing facilities under contract to the United States Government. The terms of the contract may provide for the disposal of explosive items that do not meet performance specifications, are obsolete, or simply excess product. These unusable munitions contain the same explosives as functional munitions and must be treated and disposed of accordingly. If these various items cannot be reworked, then they must be demilitarized, which means to render the items no longer functional for their intended military use and to free them of hazard (e.g., explosive, reactive) to the point that salvageable parts may be sold to the public or recycled.

Demilitarization of unserviceable, outdated, or obsolete munitions is part of proper munitions stockpile management. This is performed at the MTR through open detonation (OD). In addition to treating ordnance stockpiled at MCAS Yuma, the MTR is used to treat ordnance and explosive end items from other military bases and bombing ranges, from local government-owned manufacturing facilities, and from local manufacturers under contract to the United States government located in Arizona and California. No explosives are received from private industry for disposal. Currently, inert scrap metal is removed from the MTR during clearing operations and recycled. Neither chemical agent nor chemical or nuclear munitions are used or treated on the BMGR.

The OD area encompasses the east portion of the MTR (east of the access road). Currently, there are two main OD areas: the fragmentation area and the White Phosphorous detonation area (See Figure 3, below). Each OD area includes several shotholes or pits. The shotholes are created by the detonation of unexploded ordnance. The detonation of a bomb creates a pit and subsequent detonation of bombs increases the pit radius and depth. The detonation pits are inspected weekly, after each detonation, and after storm events or high winds. The pits are inspected for integrity, depth, and metal fragments (kickouts). If an inspection indicates a detonation pit is unusable, for example, when the pit becomes too deep (i.e., it is unsafe to roll a bomb into, 10 feet or deeper) the pit is backfilled; and a new detonation pit shothole is developed.

  • Figure 3 - Munitions Treatment Range -- (PDF)

The MTR is located within the boundaries of the BMGR and meets minimum protective distance standards required by AAC R18-8-264.A (40 CFR 264, Subpart EE) and the Department of Defense Explosive Safety Board (DDESB) Standards. These standards require that detonation of waste explosives ranging from 1,001-10,000 pounds must be conducted at least 530 meters (1,730 feet) away from the property of others.

Former Waste Management Activities on BMGR

The former open burn (OB) area is located in the northwest corner of the MTR and consists of clean-closed OB trenches formerly used for small caliber munitions. ADEQ approved the closure of the trenches in 1998. They were clean-closed in accordance with federal and state regulations (CDM 2001). A former munitions wash area (for pink water treatment) was located just south of the former OB area. The munitions wash area operations ceased and the area was disassembled when the OB area was closed. A proposed munitions wash area (for pink water treatment) in the southwest corner of the MTR was assembled, but never used. This area will remain closed and will not be used for munitions treatment.

Hydrogeological Characteristics of the Site

There are no injection wells or groundwater withdrawal wells within close proximity to the MTR. Groundwater flow direction is predominantly to the south and southeast in the MTR vicinity. The United States Bureau of Reclamation collects groundwater elevation data from several piezometers in the BMGR (the nearest one is approximately five miles from the MTR). In addition to these piezometers, numerous well locations and natural water catchments are located elsewhere on and near the BMGR.

Numerous groundwater studies have been conducted on surrounding perimeter areas of the BMGR.The three largest and deepest basins are Lechuguilla, Mohawk-Tule, and San Cristobal. The major water-bearing units in the perimeter areas are found above and below thick lacustrine clay layers.

The San Cristobal Valley contains at least three aquifers. The first is an unconfined, shallow, fine sand aquifer in the north that extends from approximately 20 feet below land surface (bls) to approximately 120 feet bls. The second aquifer is a confined sand and gravel aquifer beneath the Gila River Terrace in the Dateland area, and may receive recharge from the Gila River Valley. The third known aquifer is a narrow, sand and gravel aquifer, located in the bajada sediments bordering the northeast flank of the Mohawk Mountains. It sits above bedrock and is found at increasing depth with increasing distance from the mountain. Water can be encountered at depths between 110 and 190 feet bls.

Studies done of the Lechuguilla Desert and Mohawk-Tule Valley indicate a shallow unconfined aquifer at depths ranging from 125 feet bls in the east-central portion of the Valley to 366 feet bls in the west-central area. A sand and gravel aquifer is suspected to exist beneath the lacustrine clay deposit that is found at depths ranging from 600 to 1500 feet bls.

Near the northern boundary of the BMGR, water was found in a well near the Gila River at a depth of 184 feet bls. The well probably was drawing water from an aquifer in the upper stratigraphic unit hydrologically connected to the aquifer underlying the Gila River corridor. Along the northwestern flank of the Copper Mountains, water was found at a considerably deeper depth of 482 feet. This water may have come from the deeper gravelly portions of the lacustrine deposits.

Summary of Corrective Action Activities

In accordance with Part IV.C of its hazardous waste permit, the Permittee was required to perform a RCRA Facility Investigation (RFI) of the following four Solid Waste Management Units (SWMU) areas. (Locations are shown in Figure 2 - Site Map) -- (PDF)

  1. SWMU-2, the Munitions Wash Area
  2. SWMU-5, Auxiliary Air Field 2 Debris Piles
  3. SWMU-9, Former Accumulation Area for Burn Residue
  4. SWMU-11, Former EOD Range

Soil concentrations from these investigations were compared to the pre-determined remediation standards found in the Arizona Administrative Code, Title 18, Chapter 7, Article 2, and are referred to as the "remediation goals". Details on the investigations at the SWMUs can be found in the following report: Revised Final RCRA Facility Investigation Report for SWMU 2, SWMU 5, SWMU 9, and SWMU 11, Marine Corps Air Station Yuma, Yuma, Arizona. CDM Federal Programs Corporation. December 2007 -- (PDF).

SWMU-2, Munitions Wash Area (MWA)

A munitions wash area was formerly located south of the closed open burn trenches in the northwest quadrant of the MTR. This self-contained unit, 200 square feet in area, was used infrequently from approximately 1988 until 1993 for the treatment of residue (pink/red water) from 2,4,6-trinitrotoluene (TNT) washing operations.

During the 2004 RFI surface and subsurface soil samples were collected from SWMU-2. The samples were characterized for volatile organic compounds (VOCs) including toluene and benzene. The concentrations of these contaminants of concern (COCs) were below the remediation goals.

SWMU-5, Auxiliary Air Field 2 Debris Piles

SWMU-5 is approximately 1.5 acres in size and is located west of Auxiliary Air Field 2. This site is currently used to stockpile scrap metal from spent ordnance and jet-assisted take off canisters. The site was also used as a temporary storage location for refuse items in the 1940s and 1950s. The debris pile reportedly contained lumber, tires, old vehicle parts, paint cans, and construction materials.

During the 2004 RFI, and a subsequent investigation in 2007, surface and subsurface soil samples were collected from SWMU-5. The samples were characterized for explosives, metals, perchlorate, and semi-volatile organic compounds (SVOCs). The concentrations of all COCs were below the remediation goals.

SWMU-9, Former Accumulation Area for Burn Residue

The area designated as SWMU-9 is located 1 mile north of the MTR on the Aux II access road. From 1988 until 1993, open burning of munitions was conducted at the MTR (the open burn trenches were clean-closed in 1998). During open burning operations, large pieces of scrap metal were removed from the trenches after open burn events and accumulated on the ground for disposal or recycling.

During the 2004 RFI surface and subsurface soil samples were collected from SWMU-9. The samples were characterized for explosives, metals, perchlorate, VOCs (including benzene), SVOCs, and white phosphorus. The concentrations of all COCs were below the remediation goals.

The table below summarizes the maximum contaminant concentrations and the remediation goals or selected contaminants at SWMUs -2, -5 and -9. The remediation goals shown are the lower of the residential soil remediation levels (SRL) or the groundwater protection levels (GPL) for that COC.

Summary of Contaminant Concentrations at Solid Waste Management Units (SWMU) 2, 5, and 9
SWMU Name Contaminant Maximum Concentration (mg/kg) Remediation Goal (mg/kg)
SWMU-2 Toluene 0.0027 400a
  Benzene ND 0.65b
  Methylene chloride 0.013 93b
SWMU-5 Perchlorate 3.2 55b
  Lead 13.4 290a
  RDX ND 50b
SWMU-9 Benzene 0.002 0.65b
  Lead 4.1 290a
  RDX ND 50b
  Perchlorate ND 55
ND = Not Detected
a = Remediation goal derived from groundwater protection levels (GPLs)
b = Remediation goal based on residential soil remediation levels (SRLs)

Corrective actions at SWMUs -2, -5, and -9 have been completed since concentrations of all COCs were below the remediation goals.

SWMU-11, Former EOD Range

SWMU-11, the former EOD Range is approximately 6.5 miles south east of Yuma (see Figure 2). It includes a trench and a dighole. The site was used in the past for open burning, detonation and disposal of spent ordnance. Features at SWMU-11 consist of a trench (approximately 2 feet deep, 14 feet wide, and 50 feet long) and a dighole (approximately 2 feet deep, and 21 feet in diameter).

The RFI at SWMU-11 involved excavation to determine if open burning and burying of munitions occurred at the trench or dighole. The RFI provided evidence that open burning and burying of munitions had occurred at the dighole. The dighole contents included black ash and burned munitions. Based on these findings, ADEQ required the Permittee to perform further corrective measures at SWMU-11.

Results of the Corrective Measures Implementation at SWMU-11 Dighole

In 2006, the Corrective Measures Study (CMS) and Corrective Measures Implementation (CMI) Plan were finalized for SWMU-11, the former EOD Range. The selected remedy was excavation of the buried munitions and ash followed by confirmatory sampling of the bottom and sides of the dighole. The analytes addressed in confirmatory sampling included VOCs, SVOCs, explosives, perchlorate and metals. The selected remedy was implemented in 2007. The CMI Report was submitted in 2007 (Draft Corrective Measures Implementation Report for SWMU 11 Dighole, Marine Corps Air Station Yuma, Yuma, Arizona. CDM Federal Programs Corporation. July 2007). The report showed that concentrations of COCs were below the pre-determined soil remediation levels. However, the report did not address the potential impact to groundwater of the remaining contamination.

No Further Action (NFA) Determination at SWMUs -2, -5, AND -9 and Schedule of Compliance for Corrective Action at SWMU-11

In accordance with the Part IV.A.3(b) of the hazardous waste Permit, The Permittee must modify the Permit to incorporate the results of the corrective actions at SWMUs -2, -5, -9, and -11.

  • ADEQ proposes to update Part IV.C of the Permit to present a brief summary of the RFI completed in 2007 at SWMUs -2, -5, -9 and -11.
  • ADEQ proposes to update Part IV.C of the Permit to note that no further action (NFA) is needed at SWMUs -2, -5 and -9 based on the sampling results from the RFI.
  • ADEQ proposes to update Part IV.C of the Permit to reference the Corrective Measures Study (CMS) and Corrective Measures Implementation (CMI) at SWMU-11; list the selected remedy of excavation followed by confirmatory sampling; and report that MCAS Yuma has not addressed groundwater protection in the CMI Report, and that there is need to include a schedule of compliance in the permit.
  • ADEQ proposes to insert a Schedule of Compliance Permit Condition at Permit Part IV.C.4 of the hazardous waste Permit to include a schedule for further corrective action at SWMU-11. The Schedule of Compliance requires the following:
    • The Permittee performed a site remedy and must therefore demonstrate that resulting concentrations of COCs in soil do not exceed GPLs.
    • The Permittee must submit the revised CMI Report by December 31, 2011.
    • Based on the results of the above demonstration, the Permittee must complete any remaining corrective measures at SWMU-11 and submit the final CMI report within 90 days of ADEQ acceptance of the revised CMI report.

Hazardous Waste Treatment Permit (2004)

On June 25, 2004, MCAS Yuma (the Permittee) was issued a hazardous waste permit to operate the MTR in accordance with hazardous waste regulations. The explosive ordnance treated at the MTR is categorized as reactive and ignitable hazardous waste. It includes Class A and B explosives (e.g., bomb and rocket fuzes, projectiles, missiles, bombs), and white phosphorus. The ordnance is treated in the Class A and B Detonation Area and the White Phosphorus Detonation Area (see Figure 3).

Class 3 Permit Modification Request

On May 14, 2008, the Permittee submitted to ADEQ a Class 3 Permit Modification request to incorporate into the Permit the results of its Corrective Action investigations. The hazardous waste rules required the applicant to hold a public meeting and to solicit public comment concerning the modification request. On May 27, 2009, the Permittee published a Public Notice in the Yuma Daily Sun, announcing the public comment period, which ran from May 28, 2009 to July 26, 2009. On June 17, 2009, the Permittee held a public meeting in the Algodones Room at the Yuma Civic Center, 1440 S. Desert Hills Dr., Yuma, Arizona 85364. No objections to the proposed Class 3 permit modification were received by MCAS Yuma.

On September 12, 2011, ADEQ proposed to approve the Permittee's Class 3 Permit Modification request. The 45-day public comment period on the proposed decision ran from September 12, 2011 to October 27, 2011. No comments were received from the public, and the Permit Modification was approved on November 04, 2011. The fact sheet and the final decision are shown below.

  • Fact Sheet -- (PDF)
  • Class 3 Permit Modification -- (PDF)

Renewal of Hazardous Waste Treatment Permit

On April 26, 2015, ADEQ announced the start of the 45-day public comment period for the BMGR-West MTR permit renewal. The comment period for the draft permit ended on June 11, 2015. There was one comment in support of the facility and no other comments were submitted by the general public during the public comment period.

The renewal Permit for the BMGR-West MTR was issued to MCAS Yuma on August 4, 2015. All permit conditions are based on the permit application, with supplements and updates submitted by the applicant on and after December 30, 2013.

Permit and Contents:

  • Arizona Hazardous Waste Management Act Permit -- (PDF)
    • Part I - General Permit Conditions
    • Part II - General Facility Conditions
    • Part III - Treatment of Energetic Wastes
    • Part IV - Corrective Action for Solid Waste Management Units Schedule of Compliance
    • Part V - Groundwater Monitoring

Permit Attachments:

  • Attachment A - Facility Description -- (PDF)
  • Attachment B - Waste Analysis Plan -- (PDF)
  • Attachment C - Process Information -- (PDF)
  • Attachment D - Soil and Groundwater Monitoring -- (PDF)
  • Attachment E - Procedures to Prevent Hazards -- (PDF)
  • Attachment F - Contingency Plan -- (PDF)
  • Attachment G - Personnel Training -- (PDF)
  • Attachment H - Closure Plan -- (PDF)
  • Attachment I - Record Keeping and Reporting -- (PDF)
  • Attachment J - Corrective Action Schedule of Compliance (CASOC) – Approved Work Plans and Reports -- (PDF)
  • Attachment K - Arizona Administrative Code -- (PDF)