Final record of decision for munitions response program

Naval Facilities Engineering Command Southwest San Diego, CA

Final Record of Decision for Munitions Response Program Site 5

Marine Corps Air Station Yuma, Yuma, Arizona

March 2019

Approved for public release; distribution is unlimited

DCN: MMEC-2405-4267-0003

SEMS-RM DOCID # 100018577

MMEC-2405-4267-0003 March 2019

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Naval Facilities Engineering Command Southwest San Diego, CA

Final Record of Decision for Munitions Response Program Site 5


March 2019

Prepared for:

Department of the Navy Naval Facilities Engineering Command Southwest 1220 Pacific Highway San Diego, CA 92132

Prepared by: Multi-Media Environmental Compliance Group

9177 Sky Park Court San Diego, CA 92123-4341

Contract Number: N62473-16-D-2405; Task Order No. N6247318F4267 DCN: MMEC-2405-4267-0003

■ Naval Faoltbes Engineenng Command

I lilEC Multi•Medla Envil'Ot"lmenU'II Compliance Group

MMEC-2405-4267-0003 March 2019


Record of Decision for Munitions Response Program Site 5 Marine Corps Air Station Yuma, Arizona

Instructions

MMEC-2405-4267-0003 i March 2019

Instructions:

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Instructions

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Table of Contents

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Table of Contents

Page

Acronyms and Abbreviations ....................................................................................................... v

Declaration ................................................................................................................................. 1

Site Name and Location ..................................................................................................... 1

Statement of Basis and Purpose ........................................................................................ 3

Description of Selected Remedy ........................................................................................ 3

Statutory Determinations .................................................................................................... 3

Authorizing Signatures ............................................................................................................... 5

Decision Summary ..................................................................................................................... 7

1.0 Site Name, Location, and Brief Description .............................................................. 7

2.0 Site History and Enforcement Activities .................................................................... 7

3.0 Community Participation .......................................................................................... 9

4.0 Scope and Role of Response Action ........................................................................ 9

5.0 Site Characteristics ................................................................................................ 10

6.0 Current and Potential Future Land Use .................................................................. 16

7.0 Summary of Site Risks ........................................................................................... 16

Responsiveness Summary........................................................................................................19

List of Figures

Page

Figure 1 MCAS Yuma Location Map ........................................................................................... 2

Figure 2 MRP Site 5 Location Map.............................................................................................. 2

Table

Page

Table 1 Summary of Previous Studies and Investigations.............................................. 12

List of Attachments

Attachment 1 References .................................................................................................... A1-1

Attachment 2 Responsiveness Summary ............................................................................ A2-1


Table of Contents

MMEC-2405-4267-0003 iv March 2019



Acronyms and Abbreviations

MMEC-2405-4267-0003 v March 2019


ºF ....................................................................................................... degrees Fahrenheit

§ ........................................................................................................................... Section

ADEQ ........................................................ Arizona Department of Environmental Quality

API ........................................................................................... armor-piercing incendiary

ARAR ............................................... applicable or relevant and appropriate requirement

ASR .............................................................................................. Archive Search Report

bgs ................................................................................................. below ground surface

BRAC .............................................................................. Base Realignment and Closure

CALA .................................................................................... combat aircraft loading area

CERCLA ..... Comprehensive Environmental Response, Compensation, and Liability Act

CERCLIS .......... Comprehensive Environmental Response, Compensation, and Liability

Information System

CFR ..................................................................................... Code of Federal Regulations

COPEC......................................................... contaminant of potential ecological concern

DERP ........................................................ Defense Environmental Restoration Program

DGM ..................................................................................... digital geophysical mapping

DMM ..................................................................................... discarded military munitions

DoD ....................................................................... United States Department of Defense

DON ..................................................................... United States Department of the Navy

ERN .............................................................................. Environmental Restoration, Navy

ESL ................................................................................. Environmental Screening Level

FFA ........................................................................................ Federal Facility Agreement

HHRA ............................................................................... human health risk assessment

IRP ................................................................................ Installation Restoration Program

LANL ............................................................................. Los Alamos National Laboratory

LOAEL ................................................................... lowest observed adverse effects level

Marine Corps ........................................................................ United States Marine Corps

MC ................................................................................................... munitions constituent

MCAS ........................................................................................ Marine Corps Air Station

MDAS ................................................................................. material documented as safe

MEC ........................................................................ munitions and explosives of concern

mm ................................................................................................................ millimeter(s)

MPPEH............................................. material potentially presenting an explosive hazard

MRP .................................................................................. Munitions Response Program

msl ............................................................................................................ mean sea level

NA ...................................................................................................................... no action

NAVFAC SW ..................................... Naval Facilities Engineering Command Southwest

NCP ....................... National Oil and Hazardous Substances Pollution Contingency Plan



MMEC-2405-4267-0003 vi March 2019

NOAEL ........................................................................ no observed adverse effects level

NPL ................................................................................................ National Priorities List

RI .................................................................................................. Remedial Investigation

ROD ................................................................................................... Record of Decision

SARA................................................... Superfund Amendments and Reauthorization Act

SI ........................................................................................................... Site Investigation

SLERA........................................................... screening level ecological risk assessment

TNT ............................................................................................................. trinitrotoluene

TOI ......................................................................................................... target of interest

UCL ............................................................................................... upper confidence limit

USACE ............................................................... United States Army Corps of Engineers

USC .................................................................................................. United States Code

USEPA .................................................. United States Environmental Protection Agency

UXO ............................................................................................. Unexploded Ordnance


Declaration

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Declaration

Munitions Response Program Site 5


This Record of Decision (ROD) presents the basis for the no action (NA) decision for Munitions Response Program (MRP) Site 5 at Marine Corps Air Station (MCAS) Yuma in Yuma, Arizona (Figure 1 and Figure 2). The United States Environmental Protection Agency (USEPA) Comprehensive Environmental Response, Compensation, and Liability Information System (CERCLIS) identification number for MCAS Yuma is AZ0971590062. The NA decision was selected in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, Title 42 United States Code (USC) Section (§) 9601, et seq., and in accordance with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations (CFR) Part 300, et seq.

Site Name and Location

MCAS Yuma is an active military installation that occupies approximately 4,800 acres southeast of the city of Yuma, Arizona (Figure 1). The Yuma International Airport Terminal shares runway privileges and is situated along the northernmost east-west runway. MCAS Yuma is located in the southwestern corner of Arizona near the California border, and is approximately 8 miles east and 4 miles south of the Colorado River, and southeast of the city of Yuma. MCAS Yuma facilities include hangars, warehouses, administrative buildings, barracks, residential housing, and numerous other structures that date from World War II to the present. Runways and taxiways are located in a triangular-shaped area to the north and west of the station’s main buildings. The facility, which is used by MCAS Yuma for military operations and training, is a joint-use facility that includes commercial, general aviation, and aircraft manufacturer facilities and operations under agreement with the Yuma County Airport Authority. The civilian airport terminal is at the north end of the facility. The southern portion of MCAS Yuma is mostly open space and includes an ordnance storage area[1]. MCAS Yuma was added to the USEPA Superfund National Priorities List (NPL) on February 21, 1990.


Declaration

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Figure 1 MCAS Yuma Location Map

MRP Site 5 was formerly firing-in butt Range 1294. This firing-in butt range was built prior to 1952 and removed in 1955. The former firing-in butt was used to zero-in fixed aircraft guns. Ammunition used included 0.50 caliber and 20-millimeter (mm) projectiles, which were the typical munitions for the types of military aircraft operated at MCAS Yuma at the time the firing butt was in use. However, practice munitions, which do not contain explosives before being fired, are used to zero-in aircraft guns. MRP Site 5, a relatively, flat, unpaved area with sparse vegetation, is located south of and adjacent to a combat aircraft loading area (CALA) and is less than 1 acre in size (Figure 2). It is bounded to the north by the CALA, to the west by an active firing-in butt berm, and to the south and east by roadways.

Figure 2 MRP Site 5 Location Map

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COMBAT AIRCRAFT LOADING AREA

(CAL.A)


Declaration

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Statement of Basis and Purpose

The NA decision was selected in accordance with CERCLA of 1980, as amended by SARA of 1986, Title 42 USC § 9601, et seq., and in accordance with the NCP, 40 CFR Part 300, et seq. This decision document explains the factual and legal basis of NA for MRP Site 5. This decision is based on information contained in the Administrative Record file, as well as on extensive field investigations, laboratory analyses, interpretation of the data, evaluation of current and future conditions, and thorough assessment of the potential human health and ecological risks.

The United States Department of Defense (DoD) has the authority to undertake CERCLA response actions under Title 42 USC § 9620, Title 10 USC § 2708, and Federal Executive Order 12580. Munitions response actions are conducted under the NCP, as authorized by CERCLA.

MCAS Yuma, an active military installation, was placed on the NPL. For federal facilities on the NPL list, CERCLA requires that USEPA and the responsible federal department enter into an interagency agreement—a Federal Facility Agreement (FFA)—to govern the cleanup (Title 42 USC § 9620). The FFA for MCAS Yuma entered into by the United States Department of the Navy (DON), USEPA, and State of Arizona (represented by the Arizona Department of Environmental Quality [ADEQ]) was signed in 1992. DON is the lead agency for MCAS Yuma, USEPA is lead federal regulatory agency, and ADEQ is the lead state regulatory agency.

DON and USEPA jointly selected NA for MRP Site 5 with the concurrence of ADEQ.

Description of Selected Remedy

The remedy selected for MRP Site 5 is NA. Selection of NA is based on the findings of extensive environmental investigations completed at MRP Site 5. These investigations did not detect any munitions and explosives of concern (MEC) or material potentially presenting an explosive hazard (MPPEH). The only potential munitions constituents (MCs) detected in soil are metals, which were detected at concentrations within the range of background. Explosives have not been detected in any soil samples from MRP Site 5. Furthermore, other hazardous substances, pollutants, or contaminants at concentrations above residential use levels have not been detected in any soil samples from MRP Site 5. Therefore, there is no unacceptable risk to human health or the environment under the current (industrial) use or a potential future use requiring unrestricted use and unrestricted exposure. Based on these results, NA is selected for MRP Site 5.

Statutory Determinations

Investigations, cleanup actions, and assessments at MRP Site 5 are complete. Based on these findings, the DON, USEPA and ADEQ believe that MRP Site 5 may be used as is without restrictions and that NA is required to protect human health and the environment. Because no remedial action is selected, the statutory determinations normally included in ROD documents pursuant to CERCLA § 121 are not required for MRP Site 5, including the provisions of CERCLA § 121 (d)(2) concerning applicable or


Declaration

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relevant and appropriate requirements (ARARs). Because the selection of NA will not result in hazardous substances, pollutants, or contaminants remaining onsite at concentrations above those that would prevent current or future site users from unlimited use and unrestricted exposure, MRP Site 5 will not be subject to the five-year review process.

Record of Decision for Munitions Response Program Site 5

Marine Corps Air Station Yuma, Arizona

Authorizing s;gnatures

Authorizing Signatures

Record of Decision



This signature sheet documents the United States Department of the Navy and United States Environmental Protection Agency co-selection of the No Action remedy described in this Record of Decision for Munition� Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. This signature sheet also documents concurrence with the No Action decision in this Record of Decision by the State of Arizona by and through the Arizona Department of Environmental Quality.

Approved by:

S ggs, Commanding Officer Marine orps Air Station Yuma United_ States Department of the Navy

Angeles errera, Assistant Director Superfund Division Federal Facilities and Site Cleanup Branch United States Environmental Protection Agency Region 9

Concurrence by:

Tina LePage, Manager Remedial Projects Section Waste Programs Division Arizona Department of Environmental Quality

MMEC-2405-4267-0003 5

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TT Date

March 2019


Authorizing Signatures

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Decision Summary

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Decision Summary

Record of Decision



1.0 Site Name, Location, and Brief Description

MCAS Yuma is an active United States Marine Corps (Marine Corps) military installation that occupies approximately 4,800 acres southeast of the city of Yuma, Arizona (Figure 1). The Yuma International Airport Terminal shares runway privileges and is situated along the northernmost east–west runway. The flight line support facilities are located along the southern edge of the runway area. A residential housing area is located southeast of the flight line. The southern portion of MCAS Yuma is mostly open space and includes an ordnance storage area[1].

MCAS Yuma serves as an aviation training facility for approximately 5,000 active marines and sailors. It is the busiest Marine Corps air station and the third busiest in naval service. Its primary mission is to support aerial weapons training for the Atlantic and Pacific Fleet Marine Forces and DON. MCAS Yuma facilities include hangars, warehouses, administrative buildings, barracks, residential housing, and numerous other structures that date from World War II to the present.

Runways and taxiways are located in a triangular-shaped area to the north and west of the station’s main buildings. The facility, which is used by MCAS Yuma for military operations and training, is a joint-use facility that includes commercial, general aviation, and aircraft manufacturer facilities and operations under agreement with the Yuma County Airport Authority. The civilian airport terminal is at the northern end of the facility.

MRP Site 5 was formerly firing-in butt Range 1294. This firing-in butt range was built prior to 1952 and removed in 1955. The former firing-in butt was used to zero-in fixed aircraft guns. Ammunition used included 0.50 caliber and 20-mm projectiles, which were the typical munitions for the types of military aircraft operated at MCAS Yuma at the time the firing butt was in use. However, practice munitions, which do not contain explosives before being fired, are used to zero-in aircraft guns. MRP Site 5 is approximately 1 acre and is currently in the flight line restricted area (Figure 2). The relatively flat, unpaved site is not being used. MRP Site 5 is adjacent to and south of the CALA and adjacent to and west of an airplane parking apron. There is no record of how the firing-in butt was removed.

2.0 Site History and Enforcement Activities

CERCLA and SARA of 1986 established a series of nationwide federal programs to identify, characterize, and clean up or control contamination from hazardous waste disposal and spill sites. One of these programs, the Defense Environmental Restoration Program (DERP), is codified in SARA Section 21 (10 USC § 2701). The DERP specifies DON personnel responsibilities, describes the various steps of the process, and


Decision Summary

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ensures consistency with regulatory guidelines for evaluation and remediation of hazardous waste site conditions.

Under DERP, the DoD developed the Installation Restoration Program (IRP) to identify, assess, characterize, and clean up or control contamination from past hazardous waste disposal operations and hazardous materials spills at DON and Marine Corps installations. IRP activities under DERP adhere to CERCLA’s implementing regulation, the NCP. The MRP is implemented under the DERP; therefore, the response actions follow the CERCLA response process described in the NCP. MCAS Yuma was placed on the NPL in 1990. DON entered into a FFA with USEPA and ADEQ in 1992. The FFA provides a procedural framework and schedule for developing, implementing, and monitoring appropriate response actions at MCAS Yuma. DON is the lead agency for MRP Site 5, and is responsible for implementing the CERCLA process at the site. USEPA reviews and approves, and ADEQ reviews and concurs with, all CERCLA documents and activities associated with the sites.

NA set forth in this ROD has been selected by DON and USEPA, and concurrence is provided by ADEQ. Funding for environmental investigations, remedial actions, and preparation of supporting documents, including the remedial investigations for MRP Site 5 and this ROD, is provided by DERP Environmental Restoration, Navy (ERN).

The MCAS Yuma facility originated in 1928 when the United States Government leased 640 acres of land from the County of Yuma for use as an airfield. During World War II, the land was leased to the War Department for use as an Army Air Station. Since that time, the facility has been used for a variety of DoD missions. The current air station was established in January 1959 to operate and maintain facilities and to provide services to support operations of the Marine Corps Aircraft Wing.

MRP Site 5 was formerly firing-in butt Range 1294. The former firing-in butt range was used to zero-in fixed aircraft guns. Practice munitions, which do not contain explosives, are used to zero-in aircraft guns. Base personnel have suggested that airplanes with malfunctioning weapons could have aimed their weapons at the firing-in butt as a safety precaution in the event that their weapons discharged. No records were located regarding instances of that type of live firing at the site and use of the firing-in butt in that manner was not the intended use of the site. If that use did occur, as suggested by anecdotal information, it is expected to have been quite infrequent. Ammunition used included 0.50 caliber and 20-millimeter (mm) projectiles, which are typical munitions for the types of military aircraft operating at MCAS Yuma during the time that the firing-in butt was in use. However, extensive investigations have been conducted over time, including removal of the berm, site excavation to 16 inches below ground surface (bgs) to remove all metallic debris observed at the surface during the original remedial investigation, digital geophysical mapping (DGM) of the entire site after removal of the top 16 inches of soil, and 100 percent identification and removal of the targets of interest identified by DGM. No MEC or MPPEH items were found during the intrusive investigations.

This ROD selects NA for MRP Site 5.


Decision Summary

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3.0 Community Participation

Documents and relevant information used during the NA selection process are made available for public review in the two information repositories established by MCAS Yuma as follows: (1) Yuma County Main Library located at 2951 South 21st Drive, Yuma, Arizona 85364; and (2) MCAS Yuma Library at Galbreath Avenue Building 633, MCAS Yuma, Arizona 85365.

The official Administrative Record File[2] is compiled and maintained by DON at Naval Facilities Engineering Command Southwest (NAVFAC SW) in San Diego, California. For access to the Administrative Record File[2], contact:

Ms. Diane Silva, Records Manager Naval Base San Diego, Building 3519 2965 Mole Road San Diego, California 921325190 (619) 556-1280

4.0 Scope and Role of Response Action

The investigations at MRP Site 5 did not detect any MEC, MPPEH, or MCs, including metals and explosives, or other hazardous substances, pollutants, or contaminants at concentrations above residential use levels in any soil samples. The resultant risk assessment concluded no unacceptable risk to human health or the environment under unrestricted use and unrestricted exposure. As a result, this ROD selects NA for MCs and MEC at MRP Site 5.

In this document, MEC describes specific categories of military munitions that may pose unique explosives safety hazard/risks, including unexploded ordnance (UXO), discarded military munitions (DMM), or MCs (such as trinitrotoluene [TNT], RDX) present in concentrations high enough to pose an explosive hazard. Similarly, MPPEH describes material owned or controlled by the DoD that, prior to determination of its explosives safety status, potentially contains explosive or munitions (for example, munitions containers and packaging material; munitions debris remaining after munitions use, demilitarization, or disposal; and range-related debris) or potentially contains explosives at concentrations high enough that the material presents an explosive hazard (for example, equipment, drainage systems, holding tanks, piping, or ventilation ducts that were associated with munitions production, demilitarization, or disposal operations). Excluded from MPPEH are military munitions within the DoD’s established munitions management system and other hazardous items that may present explosion hazards (such as gasoline cans, compressed gas cylinders) that are not munitions and are not intended for use as munitions.


Decision Summary

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5.0 Site Characteristics

This section provides an overview of the previous investigations, topography, climate, geology, surface water hydrology and hydrogeology, land and groundwater use, biological setting, cultural resources, and conceptual site models for MRP Site 5 as presented in the Remedial Investigation (RI) and additional RI.

Site History

MRP Site 5 was formerly firing-in butt Range 1294, which was built prior to 1952 and removed in 1955[3]. The range was used to zero-in fixed aircraft guns. In addition, anecdotal information indicates that airplanes with malfunctioning weapons aimed their weapons at the firing-in butt as a safety precaution in case their weapons discharged. MRP Site 5 was first identified in the United States Army Corps of Engineers (USACE) 2001 MCAS Yuma Archive Search Report (ASR). The report identified potential munitions types used at the site as “Cartridge, Ball 0.50 caliber, M2; Tracer, 0.50 caliber, M1; 20-mm, armor-piercing incendiary (API) and API-T M53 and M52 cartridge; 20mm target practice M5; and 20mm high-explosives incendiary.” The munitions quantity, density, and depth were listed as unknown quantity, low-density, and surface depth, respectively[4]. It is expected that practice rounds were used to zero-in fixed aircraft guns. It is unlikely that more costly rounds containing energetic materials would have been used in this process[5]. There is no record of how the firing-in butt was removed.

Previous Investigations

In 2010, a Site Investigation (SI) was conducted at MRP Site 5. The SI consisted of collecting surface soil samples across the site and analyzing the soil samples for MC consisting of metals associated with munitions use (antimony, arsenic, cadmium, copper, lead, and zinc) and a nitroamine panel of 14 explosive constituents. No metals were detected in soil at concentrations exceeding project screening guidelines and no nitroamine explosives were detected at concentrations above regulatory screening levels[6]. A spent 0.50 caliber cartridge, which is classified as small arms, was observed at MRP Site 5 during the SI. The spent cartridge was classified as material documented as safe (MDAS). No geophysical investigation for MEC was conducted during the SI.

An RI was conducted at MRP Site 5 in 2013. As part of the RI, a DGM survey and intrusive investigation were performed across 100 percent of MRP Site 5 to assess whether MEC items were present in subsurface soil. The MEC geophysical investigation identified 271 anomalies as targets of interest (TOIs). Ten percent of these anomalies (27), as well as three anomalies from within the metallic debris zones, were intrusively investigated [7]. The intrusive investigation identified three 0.50 caliber small arm projectiles. However, these items did not contain energetic material and were classified as MDAS [8]. The Final 2013 Army Position Paper on Small Arms Ammunition states that small arms ammunition do not pose the same explosives safety risk as other military munitions because small arms ammunition contains a small amount of propellant that burns and may only have localized consequences for initiation outside a weapon, which is an unlikely initiation[9]. The presence of 0.50 caliber small arms projectiles at the site is consistent with the historical use of the site as a firing-in butt range to zero-in fixed


Decision Summary

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aircraft guns. An HHRA and SLERA were performed as part of the RI to evaluate potential risk and hazards associated with metals detected at the site. Results indicated that MC in soil does not pose an unacceptable risk to human health or the environment. The RI recommended no further action for MC, depending on the outcome of further MEC investigation[10].

The additional RI, conducted in February and May 2016, investigated and removed TOI and metallic debris identified in the initial RI. Metallic debris was removed and recycled to a depth of approximately 3 feet bgs through a combination of excavation/screening to a depth of 16 inches followed by DGM survey, and TOI investigation/removal to a depth of 18 inches. The excavated soil was sieved through a series of screens and inspected for MEC and MPPEH. After the soil was removed, DGM was performed over the entire site. The DGM revealed 124 targets for intrusive investigation. All targets were removed, and all locations were checked for remaining metallic debris and cleared prior to backfilling. Soil samples were also collected from beneath the TOIs for analysis of explosives and metals. None of the targets encountered down to a depth of approximately 3 feet bgs were identified as MEC or MPPEH[11]. Two expended 20-mm practice projectiles, which did not contain explosives prior to being fired, were detected and classified as MDAS, and expended small arms that were also classified as MDAS were recovered as a result of screening the top 16 inches of soil, and/or intrusive investigation. All other metallic items found during the additional RI were identified as construction debris (i.e., metal banding, nails, rebar). The results of updated HHRA and SLERA conducted using data from this additional RI and previously collected data indicate that the metals present in the site soils at MRP Site 5 do not pose an unacceptable risk to human health or the environment. Explosives have not been detected in any soil samples from MRP Site 5[12]. The additional RI concluded that no further action is recommended for MEC and MC at MRP Site 5[13].

Table 1 summarizes the previous investigations conducted at MCAS Yuma that are pertinent to MRP Site 5.


Decision Summary

MMEC-2405-4267-0003 12 March 2019

Table 1 Summary of Previous Studies and Investigations

Previous Study/Investigation Date Investigation Activities

Archive Search Report (ASR) Marine Corps Air Station Yuma, Arizona

2001 Identified eight former areas that were used as military ranges.

Final Site Investigation (SI) Report Munitions Response Sites 1, 2, 3, 4, 5, and 6, Marine Corps Air Station Yuma, Arizona

2011 Site inspections with respect to historical use of military munitions at MRP Sites 1, 2, 4, 5, and 6.

Final Remedial Investigation Report, Munitions Response Program Site Unexploded Ordnance 5, Marine Corps Air Station Yuma, Yuma, Arizona

2014 The objective of the RI was to collect sufficient data to characterize the nature and extent of MEC and MC in soil at MRP Site 5. The nature and extent of MC at MRP Site 5 were sufficiently characterized. Results of the HHRA and SLERA indicated that no further action is required to protect human health or the environment from MC in site soil. The RI recommended further action for MEC at MRP Site 5.

Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Arizona

2017 The findings of the additional RI indicated that MEC and MC do not pose an unacceptable risk to human health or the environment. Risk assessment results indicate that metals in soil do not pose a risk to human health or the environment. Explosives have not been detected in any soil sample collected at MRP Site 5. No MEC or MPPEH have been found in extensive investigations. Based on these results, no further action is recommended for MEC and MC at MRP Site 5.

Topography and Vegetation

Elevations at MCAS Yuma range from 140 to 290 feet above mean sea level (msl), with a total relief of 150 feet. The ground surface over most of MCAS Yuma slopes slightly to the west toward the depression in the area of the runways. Surface elevations in this area range from approximately 185 to 210 feet above msl, except in the vicinity of the hill near the center of the base, which rises approximately 90 feet higher than the general air station ground level. The topography of MRP Site 5 is relatively flat. Currently, MRP Site 5 is unpaved with sparse vegetation and is not used.

The land within and near MCAS Yuma contains gently rolling terrain consisting of flat mesas and drainage ways. This area has been mostly disturbed with agricultural, commercial, and industrial activities supporting farming, MCAS Yuma, and the airport. The general plant communities at MCAS Yuma include Arizona lupin, burro bush, coldenia, creosote bush, desert calico, desert san verbena, dune ephedra, Spanish needles, spectacle pod, and wolfberry.

Climate

The Yuma area has an arid climate with mild winters and hot summers. The average temperature is 55 degrees Fahrenheit (°F) in winter and 87°F in summer.


Decision Summary

MMEC-2405-4267-0003 13 March 2019

Total annual precipitation in the Yuma area is approximately 2 to 3 inches. Half of this total usually falls between April and September. Average relative humidity is approximately 20 percent.

Geology

Yuma is on the northern portion of Yuma Mesa, approximately 60 to 70 feet above the adjacent Colorado River Valley and approximately 190 feet above msl. Yuma Mesa is separated from the Colorado River Valley by a north-trending bluff approximately 5 miles west of MCAS Yuma.

Sedimentary deposits on Yuma Mesa are predominantly fluvial (river) deposits with minor eolian (windblown) deposits in the upper 180 to 200 feet. The interbedded deposits consist of alluvium from Colorado River deposition that has been reworked by local ephemeral streams and sheet flow. The alluvium is highly variable and ranges in grain size from silt and fine sand to very coarse gravel. Locally at MCAS Yuma, silt and clay deposits form small discontinuous lenses that retard the vertical migration of groundwater. The horizontal and vertical extent of these lenses is not well understood.

The bottom of the alluvial deposits may extend more than 2,000 feet below the surface. These alluvial deposits appear to directly overlie pre-Tertiary bedrock at MCAS Yuma. Outcrops of pre-Tertiary granitic bedrock occur in a series of low hills in the Yuma Hills area, which rise to 150 feet above the surrounding lowlands. Outcrops on and adjacent to MCAS Yuma trend north to northwest and are surrounded by alluvial deposits, indicating that relatively shallow bedrock zones exist in this part of the Yuma Mesa. Bedrock on MCAS Yuma is a porphyritic hornblende granodiorite.

Soils and lithologic features encountered during previous investigations performed on MCAS Yuma consisted of fine to coarse sand with interbeds of clay, silt, and gravel. In many borings, clay or silt lenses of varying thicknesses were encountered. These lithologic units are often discontinuous from one boring to another.

Soil

According to the Yuma Office of the United States Soil Conservation Service, the principal soil type is Superstition Sand, a deep and somewhat excessively drained soil found locally on the Yuma Mesa, which forms nearly level to undulating surfaces. The surface layer is light brown sand about 5 inches thick; the underlying material is light brown and pink sand to a depth of 60 inches or more. This underlying material contains soft lime masses. In some places, the surface layer is loamy sand. Permeability of the Superstition Sand is high, and the available water capacity is low to moderate. Surface runoff on the sand is very slow. Most of the area covered with this soil type is rangeland. However, several areas adjacent to the south and east of MCAS Yuma are used for irrigated crops, such as citrus and alfalfa. Light commercial developments exist to the east and north of MCAS Yuma.

Hydrology and Hydrogeology

Principal stratigraphic units containing groundwater usable for agricultural and domestic applications are the alluvial deposits. The crystalline bedrock is uniformly devoid of sizable supplies of groundwater.


Decision Summary

MMEC-2405-4267-0003 14 March 2019

Two northwesterly trending, subparallel, high-angle faults that could affect the movement of groundwater are believed to exist beneath MCAS Yuma. These faults appear to have been inactive since the Pleistocene epoch and show no evidence of surface displacement. The effect of these faults on groundwater movement is not presently known.

Groundwater and Surface Water

Groundwater near MCAS Yuma generally flows within the unconsolidated alluvial sand in a northwesterly direction and is approximately 65 to 140 feet below grade level. The hydraulic gradient is approximately 15 to 20 feet per mile. Irrigation activities south of MCAS Yuma have affected the groundwater levels and direction. Water applied intermittently (i.e., precipitation) is unlikely to exceed evapotranspiration.

The Yuma area receives little annual rainfall, and evapotranspiration rates are far in excess of available precipitation. These conditions, combined with the flat-lying topography and presence of highly permeable surface soils, have produced no significant drainage features on the Yuma Mesa. Drainage in the surrounding area is generally confined to localized depressions and subdued topographic lows. Some gullies exist near the southwestern end of the runways, indicating that runoff occurs from this area during storms. Because of the large amount of concrete in the area, local flooding sometimes results after heavy rainfall. Floodwaters may remain for several days in areas such as the flight line and the main portion of the station. MCAS Yuma has installed 51 dry wells throughout the station that are registered with the State of Arizona. These wells are designed to receive stormwater from precipitation events and allow it to infiltrate the ground.

No large surface-water bodies are present near MCAS Yuma because of the small amount of annual precipitation, high evaporation rates created by warm temperatures, and relatively high permeability of the alluvium. The Colorado River is the closest major surface-water feature. It lies approximately 8 miles west and 4 miles north of MCAS Yuma. The Resource Conservation and Recovery Act Part B Permit Application for the Defense Reutilization Marketing Organization Hazardous Waste Storage Yard states that MCAS Yuma is not within the 100-year floodplain of the river.

Biological Habitat

The land within MCAS Yuma and in the immediate vicinity contains gently rolling terrain consisting of flat mesa and drainage ways. This area has been mostly disturbed with agricultural, commercial, and industrial activities supporting MCAS Yuma, the airport, and farming.

The general plant communities at MCAS Yuma include the following: Arizona lupine, burro bush, creosote bush, coldenia, desert calico, desert sandverbena, dune ephedra, Spanish needles, spectacle pod, villosa, and wolfberry.

The desert wildlife in the immediate vicinity of MCAS Yuma includes various mammals (mostly rodents), birds, reptiles, and amphibians. An endangered species survey conducted in 1990 found no federally listed threatened or endangered flora or fauna within MCAS Yuma’s boundary. The following species have special recognition status


Decision Summary

MMEC-2405-4267-0003 15 March 2019

from federal, state, and local conservation agencies: desert tortoise, flat-tailed horned lizard, and Yuma clapper rail.

MRP Site 5 occupies approximately 1 acre and is in the flight line restricted area (Figure 2). Given its small size (1 acre), the proximity to existing taxiways and service areas at MCAS Yuma, and the lack of vegetation, MRP Site 5 was determined to provide no significant value as wildlife habitat. The MCAS Yuma biologist inspected MRP Site 5 on June 12, 2016 and found no natural resources issues. MRP Site 5 is unpaved and relatively flat, with sparse vegetation, similar to the surrounding area.

Cultural Features

MRP Site 5 was surveyed in 2006 for cultural resources. No cultural resources were recorded within or near the site.

Conceptual Site Model

The conceptual site model[14] for MRP Site 5 summarizes the current understanding of physical site conditions, MC and MEC sources and release and transport mechanisms, receptors, and affected media.

Physical Site Conditions

MRP Site 5 is a relatively flat, 1-acre unpaved area with sparse vegetation located adjacent to a CALA. MRP Site 5 is bounded to the north by the CALA, to the west by an active firing-in butt berm, and to the south and east by roadways. MRP Site 5 is in the restricted area just south of a concrete CALA and is used in support of munitions operations, and as a parking apron for military aircraft. The MCAS Yuma boundary is secured by guards, fencing, and other security measures. Entry to the MRP Site 5 location requires access through the flight line (controlled by the airfield and patrolled) or through a locked gate (controlled by military police).

MC and MEC Sources and Release Mechanisms

Characterization of the nature and extent of MC and MEC at the site have been completed and no MEC or MPPEH have been found at MRP Site 5. Munitions used at the site, which was formerly a firing-in butt used to zero-in fixed aircraft guns, would be found on the surface or in shallow subsurface soil, if present. Metallic debris present at the surface and in the subsurface has been removed from MRP Site 5. Following excavation and screening of soil to a depth of 16 inches bgs, a geophysical investigation was conducted across the entire footprint of MRP Site 5. This survey was designed to detect 20mm projectiles in the subsurface to a depth of 18 inches bgs[15]. The total depth of the assessment between the excavation and the geophysical investigation is thus approximately 3 feet below the original ground surface. The only potential MC-related constituents detected in soil are metals, most of which were detected at concentrations consistent with site-specific background[16]. Explosives have not been detected in any soil samples collected from MRP Site 5[12].

Potential Release and Transport Mechanisms

Potential release and transport mechanisms for metals in soil include wind dispersion from exposed surface soils, mechanical distribution during future construction activities,


Decision Summary

MMEC-2405-4267-0003 16 March 2019

possible transport in surface water runoff, or potential leaching to groundwater. The very dry climate combined with the flat topography of the site results in very little potential for surface water runoff.

Similarly, the combination of little annual rainfall with significant evapotranspiration rates along with the small site footprint and depth to groundwater (65 to 140 feet bgs) suggests that site-related impacts to groundwater quality are unlikely. Furthermore, groundwater at MRP Site 5 is not a current source of drinking water, and groundwater impacts from MRP Site 5 are not expected based upon groundwater sampling previously conducted as part of the Operable Unit 1 RI. Groundwater impacts from the site are also not expected based upon the minimal detections of metals in soil at concentrations above background thresholds.

Receptors

Current potentially exposed human receptors are limited to individuals with access through the flight line[17]. There are no plans for future use of MRP Site 5 except for possible expansion of the airfield, which would result in similar access limitations. Although the plans for future site use would not entail significant excavation activities, construction/excavation workers may be a potential future receptor group relative to the soil.

MRP Site 5 does not represent nor afford significant habitat for ecological receptors[18] given its small size (1 acre), proximity to existing taxiways and service areas at MCAS Yuma, and lack of vegetation.

6.0 Current and Potential Future Land Use

MCAS Yuma is a critical aviation training facility for the Marine Corps, and its mission will not change in the foreseeable future. Currently, MRP Site 5 is vacant land. The presence of the adjacent CALA, runways, and airfield operations limits the future use of the site. Potential future use of MRP Site 5 could consist of expansion of the airfield. The MCAS Yuma aviation training mission and current land use practices are expected to remain the same in the future.

7.0 Summary of Site Risks

No hazardous substances have been found during the investigations and concentrations of metals detected in soil at MRP Site 5 are within the range of background concentrations.

Cancer risk is expressed in terms of the probability that an individual or a particular group of individuals would have an increased chance of contracting cancer over a lifetime period of 70 years. For example, a cancer risk of 1 x 10-4 refers to an increased chance of one in ten thousand that individuals exposed could develop cancer over a lifetime. In the National Oil and Hazardous Substances Pollution Contingency Plan (NCP; Title 40 Code of Federal Regulations [40 CFR] Part 300 et seq., as amended), USEPA (1990) states that: "For known or suspected carcinogens, acceptable exposure levels are generally concentration levels that represent an excess upper bound lifetime cancer risk to an individual between 10-4 and 10-6." This range is often referred to as the


Decision Summary

MMEC-2405-4267-0003 17 March 2019

"risk management range" for which mitigation may not necessarily be required. Cancer risks less than 10-6 are generally considered de minimis (inconsequential), representing acceptable health risk and not requiring further action. The noncancer health effects are evaluated in terms of a hazard index (HI) that determines negative health effects caused by specific chemicals. If the HI is above 1, then there is a possibility that there might be negative health concerns caused by the site.

Updated HHRA results concluded that incremental risk for each receptor (including current workers, construction workers, and hypothetical future residents) at MRP Site 5 is less than 1x10-6, well below the upper end of the acceptable cancer risk range[19]. The incremental hazard indices are less than 1 for all receptors, indicating that there is little potential for a noncancer systemic effect. No metal was recommended to be carried forward as a human health chemical of concern for the site[20].

A conservative SLERA using the maximum detected concentrations of metals in the soil interval (0–3.5 feet) revealed exceedances of conservative Los Alamos National Laboratory (LANL) Environmental Screening Levels (ESLs) for antimony, barium, cadmium, copper, lead, manganese, nickel, thallium, vanadium, and zinc. These metals were moved forward into a refined screening-level evaluation to assess exposure and risk to specific assessment endpoints.

The refined screening-level assessment was performed using the 95 percent upper confidence limit (UCL) for the soil interval (0–3.5 feet bgs). The 95 percent UCL of detected metal concentrations were below their corresponding 95 percent UCL of background concentrations, except for a single detection of silver. However, both the maximum and 95 percent UCL concentrations of silver were below screening values for all receptor groups. Based on the refined exposure assessment and risk characterization, no risks to the preliminary assessment endpoints were identified for the total soil evaluation. While some no observed adverse effects level (NOAEL) values and one lowest observed adverse effects level (LOAEL) value were exceeded for vanadium for an avian receptor, comparability to background concentration ranges identified these exceedances as not being significant relative to ambient background exposures and the product of conservatively derived ESLs. No contaminants of potential ecological concern (COPECs) were identified on the basis of the updated SLERA[21].

In summary, the nature and extent of MC at MRP Site 5 have been sufficiently characterized. No explosives have been detected in any soil samples collected from MRP Site 5. No MEC or MPPEH have been found at MRP Site 5, which surveyed using 100 percent DGM and cleared to a depth of 34 inches bgs. Results of the HHRA and SLERA indicate that MRP Site 5 does not pose an unacceptable risk to human health (including hypothetical future resident) or the environment. Environmental investigations completed at MRP Site 5 did not detect MEC, MPPEH, or MCs, including metals and explosives, or other hazardous substances, pollutants, or contaminants at concentrations above residential use levels in any soil samples collected from MRP Site 5. Therefore, no action is recommended for MCs and MEC at MRP Site 5.

While land use restrictions are not included as part of the NA remedy for MRP Site 5, from a practical standpoint, the operational features that are immediately adjacent to the


Decision Summary

MMEC-2405-4267-0003 18 March 2019

site (i.e., runways, current firing-in butt, and Combat Aircraft Loading Area [CALA] where weapons are loaded on aircraft) do not allow for residential use of the site. As required by the DoD Base Redevelopment and Realignment Manual (DoD 4165.66-M [DON, 2006]), an “Environmental Condition of Property“ (ECP) will be prepared if MCAS Yuma is ever subject to Base Realignment and Closure. The ECP will note the presence of the operational features, the status of environmental restoration sites, and will provide the DoD with information to make disposal decisions regarding the property and assist in planning for reuse of the property.


Responsiveness Summary

MMEC-2405-4267-0003 19 March 2019


Record of Decision



Comments from the supporting regulatory agencies and DON responses to the comments received are included in the Responsiveness Summary of the Final NA ROD (Attachment 2).



MMEC-2405-4267-0003 20 March 2019



Attachment 1: References

MMEC-2405-4267-0003 A1-1 March 2019

Attachment 1 References



MMEC-2405-4267-0003 A1-2 March 2019




MMEC-2405-4267-0003 A1-3 March 2019

Item

Key Word of Reference

Phrases in ROD

Section in ROD Where Reference

First Appears Identification of Referenced Document in the

Administrative Record

[1] includes an ordnance storage area

Declaration, Site Name and Location

Trevet. 2014. Final Remedial Investigation Report Munitions Response Program Site Unexploded Ordnance 5, Marine Corps Air Station Yuma, Yuma, Arizona. September 4. Page 2-1

[2] Administrative Record

Decision Summary, Section 3.0

Administrative Record Index for MRP Site 5.

[3] removed in 1955 Decision Summary, Section 5.0

The Alliance Compliance Group Joint Venture. 2011. Final Site Inspection Report Munitions Response Sites 1, 2, 3, 4, 5, and 6. Marine Corps Air Station Yuma, Arizona. May. Page 11.

[4] The munitions quantity, density, and depth were listed as unknown quantity, low-density, and surface depth, respectively


U.S. Army Corps of Engineers. 2001. Archive Search Report, MCAS Yuma. December. To view a copy of this report, please contact:

Ms. Diana Silva, Records Manager

Naval Base San Diego, Building 3519

2965 Mole Road

San Diego, California 92132-5190

Telephone: (619) 556-1280

[5] It is unlikely that more costly rounds containing energetic materials would have been used in this process



[6] No metals were detected in soil at concentrations exceeding project screening guidelines and no nitroamine explosives were detected at concentrations above regulatory screening levels


The Alliance Compliance Group Joint Venture. 2011. Final Site Inspection Report Munitions Response Sites 1, 2, 3, 4, 5, and 6. Marine Corps Air Station Yuma, Arizona. May. Pages 36 - 40



MMEC-2405-4267-0003 A1-4 March 2019

Item


Phrases in ROD




[7] The MEC geophysical investigation identified 271 anomalies as targets of interest (TOIs). Ten percent of these anomalies (27), as well as three anomalies from within the metallic debris zones, were intrusively investigated


Trevet. 2014. Final Remedial Investigation Report Munitions Response Program Site Unexploded Ordnance 5, Marine Corps Air Station Yuma, Yuma, Arizona. September 4. Page 8-3, Figures 4-1 through 4-4 and Table 4-4.

[8] However, these items did not contain energetic material and were classified as MDAS



[9] do not pose the same explosives safety risk as other military munitions because small arms ammunition contains a small amount of propellant that burns and may only have localized consequences for initiation outside a weapon, which is an unlikely initiation



[10] The RI recommended no further action for MC, depending on the outcome of further MEC investigation


Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Page 1-4.

[11] None of the targets encountered to a depth of approximately 3 feet bgs were identified as MEC or MPPEH


Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Page 6-1, Table 2-1.



MMEC-2405-4267-0003 A1-5 March 2019

Item


Phrases in ROD




[12] Explosives have not been detected in any soil samples collected from MRP Site 5



[13] additional RI

concluded that no further action is recommended for MEC and MC at MRP Site 5



[14] conceptual site model


Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Figure 4-1, Figure 5-1.

[15] Following excavation and screening of soil to a depth of 16 inches bgs, a geophysical investigation was conducted across the entire footprint of MRP Site 5. This survey was designed to detect 20mm projectiles in the subsurface to a depth of 18 inches bgs



[16] potential MC-related constituents detected in soil are metals, most of which were detected at concentrations consistent with site-specific background



[17] Current potentially exposed human receptors are limited to individuals with access through the flight line





MMEC-2405-4267-0003 A1-6 March 2019

Item


Phrases in ROD




[18] MRP Site 5 does not represent nor afford significant habitat for ecological receptors



[19] Updated HHRA results concluded that incremental risk for each receptor (including current workers, construction workers, and hypothetical future residents) at MRP Site 5 is less than 1x10-6, well below the upper end of the acceptable cancer risk range


Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Pages 4-12,-13.

[20] No metal was recommended to be carried forward as a human health chemical of concern for the site



[21] No contaminants of potential ecological concern (COPECs) were identified on the basis of the updated SLERA



Item

[1]

Key Word of Reference Phrases in ROD includes an ordnance storage area

Section in ROD Where Reference First Appears Declaration, Site Name and Location

Identification of Referenced Document in the Administrative Record Trevet. 2014. Final Remedial Investigation Report Munitions Response Program Site Unexploded Ordinance 5, Marine Corps Air Station Yuma, Yuma, Arizona. September 4. Page 2-1

Section 2 Site Description

This section discusses the location and history of MCAS Yuma and MRP Site 5, physical

characteristics, and natural resources of MRP Site 5.

2.1 Location and History of MCAS Yuma

MCAS Yuma is an active military installation that occupies approximately 4,800 acres southeast

of the city of Yuma, Arizona (Figure 2-1). The Yuma International Airport Terminal shares

runway privileges and is situated along the northernmost east–west runway. The flightline

support facilities are along the southern edge of the runway area. A residential housing area is

located southeast of the flight line. The southern portion of MCAS Yuma is mostly open space

and includes an ordnance storage area.

MCAS Yuma serves as an aviation training facility for approximately 5,000 active Marines and

Sailors. It is the busiest air station in the Marine Corps and the third busiest in Naval service.

MCAS Yuma’s primary mission is to support aerial weapons training for the Atlantic and Pacific

Fleet Marine Forces and Navy. Located in the southwestern corner of Arizona near the

California border (Figure 2-1), the MCAS Yuma Main Station occupies approximately 4,716

acres of desert land in the southeastern section of Yuma, Arizona (Alliance 2010).

MCAS Yuma facilities include hangars, warehouses, administrative buildings, barracks,

residential housing, and numerous other structures that date from World War II to the present.

Runways and taxiways are located in a triangular-shaped area to the north and west of the

station’s main buildings. The facility, which is used by MCAS Yuma for military operations and

training, is a joint-use facility that includes commercial, general aviation, and aircraft

manufacturer facilities and operations under agreement with the Yuma County Airport

Authority. The civilian airport terminal is at the north end of the facility (Alliance 2010).

The MCAS Yuma facility originated in 1928 when the U.S. Government leased 640 acres of

land from the County of Yuma for use as an airfield. During World War II, the land was leased

to the War Department for use as an Army Air Station (Yuma Army Air Station) and was used to

train pilots. Following World War II, all flight-related activities ceased until July 7, 1951 when

the United States Air Force reinstated the base as the Yuma Airfield. The current MCAS was

established in January 1959 to operate and maintain facilities and to provide services to support

operations of a U.S. Marine Corps Aircraft Wing.

2.2 MRP Site 5

MRP Site 5 was formerly firing- in butt Range 1294. The former firing- in butt range was used to

zero-in fixed aircraft guns. In addition, anecdotal information indicates that airplanes with

malfunctioning weapons aimed their weapons at the firing- in butt as a safety precaution in the

FINAL RI 2-1 September 2014 MRP Site 5, MCAS Yuma

A1-7MMEC-2405-4267-0003 March 2019

1-1

Item

[3]

Key Word of Reference Phrases in ROD removed in 1955

Section in ROD Where Reference First Appears Decision Summary Section 5.0

Identification of Referenced Document in the Administrative Record The Alliance Compliance Group Joint Venture. 2011. Final Site Inspection Report Munitions Response Sites 1, 2, 3, 4, 5, and 6. Marine Corps Air Station Yuma, Arizona. May. Page 11.

•

•

•

SITE BACKGROUND (CONTINUED)

2.4 MRS-4

MRS-4 consists of the Arizona Militia Target Range, as identified on Figure 2.3. The Arizona

Militia Target Range was established in 1910 and was abandoned before 1942. Based on historical

documents and aerial photographs, the 2001 ASR concluded that no fixed firing facilities were

established on this range, which occupied approximately 240 acres. Most of this site has been

developed as part of the current runway and plane parking apron. The site is co located within

the flightline area, which was designated as the CAOC 1. CAOC 1 has undergone an extensive

Remedial Investigation (RI), which was documented in the RI report (JEG, 1996a and b). As part

of the RI, CAOC 1 was investigated for the presence of petroleum hydrocarbons; volatile organic

compounds; polychlorinated hydrocarbons; polycyclic aromatic hydrocarbons (PAHs); ethylene

glycol; organic lead phenols; metals; and benzene, toluene, ethylene, and xylene (BTEX). Based

on the RI results, the project team (USEPA, NAVFAC SW, MCAS Yuma, and ADEQ) concluded

that the 0- to 10-foot soils at CAOC 1 do not pose an unacceptable risk to human health or the

environment under the industrial use scenario. On the basis of this conclusion, land use control

was recommended, restricting CAOC 1to industrial use.

2.5 MRS-5

MRS-5 consists of the Firing-in Butt Range 1294, as identified on Figure 2.4. This Firing-in Butt

Range was built prior to 1952 and removed in 1955. The range is in the restricted area, just south

of a concrete parking apron for military aircraft. It was used for zero-fixed aircraft guns. Ammunit ion

used included .50-cal and 20mm projectiles, which are the typical munitions for the types of militar y

aircraft operated at MCAS Yuma. This range occupied approximately one acre. Currently, the

unpaved site is not being used and relatively flat, similar to surrounding area.

2.6 MRS-6

MRS-6 consists of the Firing-in Butt Range 1295, as identified on Figure 2.4. This range was

built prior to 1955 and removed prior to 1985. It was used for zero-fixed aircraft guns.

Ammunition used included 20mm and 25mm projectiles and .50-cal munitions. This range

occupied approximately one acre. Currently the site consists of large dirt mounds with

construction and concrete debris approximately 15 to 18 ft high...

2.7 PHYSICAL SETTING

This section summarizes the physical setting, including regional geology, hydrogeology, topography,

sites soils, groundwater, surface water, biota, and demographics.

2.7.1 Geology

The Yuma area lies along the northeastern edge of the Salton Trough and is surrounded by dense

pre-Tertiary crystalline rocks and volcanic rocks of Tertiary age. The Salton Trough is a

geologically active area that has resulted from the spreading or rifting of the earth's crust. MCAS

S/ Report, MRS- 1, 2, 4, 5 and 6, MCAS Yuma

FINAL

11 ALNC-2206-0049-0006

A1-8

MMEC-2405-4267-0003 March 2019

1-1

Item

[5]

Key Word of Reference Phrases in ROD It is unlikely that more costly rounds

containing energetic materials would

hav e been used in this process

Section in ROD Where Reference First Appears Decision Summary

Section 5.0

Identification of Referenced Document in the Administrative Record Trev et. 2014. Final Remedial Inv estigation Report Munitions Response

Program Site Unexploded Ordinance 5, Marine Corps Air Station Yuma, Yuma,

Arizona. September 4. Page 2-3

and depth were listed as unknown quantity, low-density, and surface depth (USACE 2001). It is

expected that practice rounds were used to zero-in fixed aircraft guns. It is unlikely that more

costly rounds containing energetic materials would have been used for this process.

In 2010, an SI was conducted at MRP Site 5 (Alliance 2010). The SI consisted of collecting

surface soil samples across the site and analyzing the soil samples for MC including metals

associated with munitions use (antimony, arsenic, cadmium, copper, lead, and zinc) and a

nitroamine panel of 14 explosive constituents. No metals were detected in soil at concentrations

exceeding project-screening guidelines. No nitroamine explosive constituents were detected. A

spent .50 caliber cartridge was observed at MRP Site 5 during the SI and was classified as

munitions debris and explosively non-hazardous. No geophysical investigation for MEC was

conducted during the SI.

Arsenic concentrations in soil did not exceed project-screening guidelines consisting of the

previously developed site-specific background concentration of 18 milligrams per kilogram

(mg/kg) or the Arizona soil remediation level for arsenic (10 mg/kg). The SI deemed the site

arsenic concentrations to be representative of background levels. However, the USEPA

expressed concern that the background data were from depths greater than surface depth and

might not be comparable to the surface soil data collected from MRP Site 5. The maximum

detected concentration of arsenic of 5.52 mg/kg exceeded risk-based regulatory screening levels.

Based on the need for further investigation of MC and the need for MEC investigation, the site

moved to the RI phase. A background study was performed to further evaluate arsenic (and

other inorganic MC) at the site.

2.3 Physical Site Characteristics

MRP Site 5 is relatively flat with sparse vegetation, and the surface elevation is generally

consistent with the surrounding area. The site is approximately 1 acre and is adjacent to an

aircraft parking apron. Currently MRP Site 5 is unpaved and not used.

The following sections present the site-specific topography, vegetation, geology, hydrogeology,

soil type, climate, groundwater, surface water, and land use.

2.3.1 Topography and Vegetation

The elevations of MCAS Yuma range from 140 feet to 290 feet above mean sea level (msl), with

a total relief of 150 feet. The ground surface over most of MCAS Yuma slopes slightly to the

west toward a large depression near the runways. Surface elevations in this area range from

about 185 feet to 210 feet above msl, except near a hill near the center of the base, which is about

90 feet higher than the general air station ground level. This hill and four others in the city of

Yuma collectively cover approximately 50 acres and are commonly referred to as the “Yuma

Hills” (Alliance 2010).


A1-9 March 2019MMEC-2405-4267-0003

I- I

INVESTIGATION AND FINDINGS (CONTINUED)

Item

[6]

Key Word of Reference Phrases in ROD No metals were detected in soil at concentrations exceeding project screening guidelines and no nitroamine explosives were detected at concentrations above regulatory screening levels


Identification of Referenced Document in the Administrative Record The Alliance Compliance Group Joint Venture. 2011. Final Site Inspection Report Munitions Response Sites 1, 2, 3, 4, 5, and 6. Marine Corps Air Station Yuma, Arizona. May. Pages 36 - 40

Units mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Screening Level 35 10 29 2800 290 310,000

Sam le ID MRS2-1 ND (<10.1) U 2.55J 0.124 J 6.14 8.60 25.6

MRS2-2 ND (<10.1) U 2.08 J 0.152 J 5.98 7.65 27.9

MRS2-3 ND (<10.1) U 2.46J 0.106 J 5.67 5.66 19.7

MRS2-4 ND (<10.1) U 1.65 J 0.121 J 4.57 34.3 19.6

MRS2-5 ND (<10.1) U 1.87 J 0.335 J 6.72 13.0 52.3

MRS2-6 ND (<10.1) U 1.87 J 0.130 J 4.55 5.60 19.0

MRS2-7 ND (<10.1) U 1.41 J 0.183 J 4.29 5.76 18.5

MRS2-8 ND (<10.1) U 3.25J 0.512 J 3.73 7.04 16.4

MRS2-9 ND (<10.1) U 3.34J 0.377 J 4.36 6.74 20.1

•

•

4.4.1.2 MRS-2

Eight soil samples and one field duplicate were taken at the Western Small Arms Range, MRS-2

. (Figure 4.2). The soil samples were analyzed for a metal panel of antimony, arsenic, cadmium, copper, lead, and zinc. No concentrations from these samples exceeded project screening

guidelines. The results are presented in Table 4.2.

TABLE 4.2 MRS-2 SUMMARY OF SOIL ANALYTICAL RESULTS FOR METALS

Antimon Arsenic Cadmium Co er Lead , Zinc

Notes: • J: The associated numerical value is an estimated quantity. mglkg: mill igrams per kilogram .

ND: nondetect;

U= The compounds/analyte were analyzed for, but not detected ..

UJ = The compound/analyte were analyzed for, but not detected. The sample quantification limit is an estimated quantity.

4.4.1.3 MRS-5

MRS-5 is relatively flat, and the surface elevation is generally consistent with· the surrounding

area. Sixteen soil samples and two field duplicates were collected at MRS-5 (Figure 4.3). These samples were analyzed for a panel of six metals (Sb, As, Cd, Cu, Pb, Zn) and a nitroamine panel

of 14 explosive constituents. No soil samples exceeded project screening guidelines, and no nitroamine explosive constituents were detected above regulatory screening levels. The results

are presented in Table 4.3.A. for metals and Table 4.3.B. for nitroamine compounds.

S/ Report, MRS- 1, 2, 4, 5, and 6, MCAS Yuma FINAL

36 ALNC-2206-0049-0006

A1-10MMEC-2405-4267-0003 March 2019

MRS5-1 ND (<10.1) U 4.93 J 0.209 J 9.59 8.99 31.3

MRS5-2 ND (<10.1) U 4.66J 0.220 J 8.90 9.04 29.5

MRS5-3 ND (<10.1) U 3.76J 0.200 J 8.36 13.0 29.7

MRS5-4 ND (<10.1) U 2.44J 0.172 J 6.39 7.74 22.0

MRS5-5 ND (<10.1) U 4.76J 0.158 J 8.37 7.98 32.0

MRS5-6 ND (<10.1) U 2.52J 0.217 J 9.94 7.70 27.4

MRS5-7 ND (<10.1) U 2.23J 0.148 J 6.52 7.54 21.6

MRS5-8 ND (<10.1) U 3.58 J 0.219 J 9.85 7.26 27.9

MRS5-9 ND (<10.1) U 3.11 J 0.365 J 11.9 15.6 31.3

MRS5-10 ND (<10.1) U 3.13 J 0.150 J 9.67 6.50 24.7

MRS5-11 ND (<10.2) U 4.58J 0.267 J 12.0 9.15 36.7

MRS5-12 ND (<10.1) U 3.60J 0.193 J 9.29 7.78 30.7 J

MRS5-13 ND (<10.2) U 5.10 J 0.524 J 15.7 17.0 62.4J

MRS5-14 ND (<10.1) U 3.17 J 0.235 J 7.83 7.34 27.3J

MRS5-15 ND (<10.2) U 5.52J 0.450 J 21.4 11.2 60.1 J

MRS5-16

MRS5-17

ND (<10.2) U

ND (<10.8) U

4.11 J

2.96J

0.273 J

ND (<1.08) U

11.8

27.5

8.51

4.53

34.3 J

19.8 J

MRS5-18 ND (<10.4) U 2.87 J 0.494 J 6.51 4.77 18.8 J

Notes: mg/kg: mill igrams per kilogram

• TABLE 4.3.A. MRS-5 SUMMARY OF SOIL ANALYTICAL RESULTS FOR METALS

Antimon Arsenic Cadmium coeeer Lead Zinc Units Mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Screening Level 35 10 29 2,800 290 310,000

SameleiD

• ND: nondetect;

• Sf Report, MRS-1, 2, 4, 5, and 6, MCAS Yuma FINAL

37 ALNC-2206-0049-0006

A1-11MMEC-2405-4267-0003 March 2019

A1-12MMEC-2405-4267-0003 March 2019


TABLE 4.3.8. MRS-5 SUMMARY OF SOIL ANALYTICAL RESULTS FOR NITROAMINE COMPOUNDS

Cl) C Cl) ::I 0 -0 Cl) ..

C Cl) -·c Cl) C N Cl)

=ii C ::I I Cl) 0 co .c

'1' -0 e .. 0 - -C ·c ·c ·e c c 1

I I

C'?. -.:I' N .... ci

Units mg/kg mg/kg mg/kg mg/kg

Screening Level 1,900 2,000 62 5.5

Sam le ID ND U NDU NDU NDU

MRS5-1 (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU NDU NDU MRS5-2 (<0.40) (<0.40) (<0.40) (<0.40)







S/ Report, MRS- 1, 2, 4, 5, and 6, MCAS Yuma FINAL •

Cl) C Cl) ::I 0 -0 .. -·2 c

I

co ci

mg/kg

620

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

NDU (<0.40)

I It)

cw,: .... I e -·c

·;:: -I It)

cw,: Cl) C

Cl) .... Cl) Cl) C

I C Cl) 0 Cl) ::I ::I .. N 0 0 "C C ->, Cl) Cl) 0 -.C C .c .. 0 - .. 111 ·- >< 0 z ->< N

::iE .. z Cl).! - I z 0 :c .= :c E

mg/kg mg/kg mg/kg mg/kg mg/kg

NA 49,000 24 NA NA

NDU NDU NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)




NDU NDU NDU ND U ND U (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU NDU NDU ND U (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)



38

•

Cl) C ·e Ill .. -·c

Cl) C >, Cl)

Cl) .c C N - Cl)

Cl) C E ::I Cl) 0 Cl) .c >, -C e C 0 Cl) ..

::I - Cl) -·c .c ·c 0 ·;:: 0. ·;:: - 0 0 '7 .. '7 .. -- It) "i: co z cw,: ,..£ ·;:: I

0. .... I- ci

mg/kg mg/kg mg/kg mg/kg

NA 27,000 NA 79

NDU NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U 'NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

ALNC-2206-0049-0006

•

A1-13MMEC-2405-4267-0003 March 2019

1-TIGATION AND FINDINGS (CONTINUED) • TABLE 4.3.8. MRS-5 SUMMARY OF SOIL ANALYTICAL RESULTS FOR NITROAMINE COMPOUNDS

a, C a, ::, 0 -0 a, ..

C a, -'i: a, C N a, :a C ::,

I a, 0 co .c -"f 0 0 .. .. 0 - -C :s 'i: ·e C c 1

I I

CW?. 'Sf' N .... N

Units mg/kg mg/kg mg/kg mg/kg

Screening 1,900 2,000 62 5.5 Level

Sam le ID NDU NDU ND U NDU

MRS5-9 (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU ND U NDU MRS5-10 (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU ND U ND U MRS5-11 (<0.40) (<0.40) (<0.40) (<0.40)


NDU NDU ND U NDU MRS5-13 (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU NDU NDU MRS5-14 (<0.40) (<0.40) (<0.40) (<0.40)


NDU NDU ND U ND U MRS5-16 (<0.40) (<0.40) (<0.40) (<0.40)

SI Report, MRS- 1, 2, 4, 5, and 6, MCAS Yuma FINAL

a, C a, ::, 0 -0 .. ~ C c cl, N

mg/kg

620

NDU (<0.40)

ND U (<0.40)

NDU (<0.40)

NDU (<0.40)

ND U (<0.40)

NDU (<0.40)

NDU (<0.40)

ND U (<0.40)

I It)

r,; ....

I

0 .. -'i: ·;: +t It)

cw€ a, C

a, a, C .... C a, a, I ::, 0 a, ::, .. N 0 0 "C C ->, a, a, 0 -.C C .c .. 0

"'·- ~ .. >< 0 -)( N :ii:

.. z z a, .!!! - e z I

:I:.::: :I: 0

mg/kg mg/kg mg/kg mg/kg mg/kg

NA 49,000 24 NA NA

ND U NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU ND U NDU NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)

ND U ND U NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)



ND U NDU NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU NDU (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)


39

• a, C

E "' .. -'i: a,

C >, a, a, .c C N - a, a, C E

::, a, 0 a, .c >, C -a, 0 C 0 .. a, .. ::, - -0 'i: .c 'i: Q, - ·;:

0 ·;:

0 I-; .. I-; .. ~ ~ It) co z cw€ C .,f ·;: I

Q, .... I- N

mg/kg mg/kg mg/kg mg/kg

NA 27,000 NA 79

NDU ND U ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

ND U NDU NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U ND U (<0.40) (<0.40) (<0.40) (<0.40)

NDU ND U NDU NDU (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU ND U ND U (<0.40) (<0.40) (<0.40) (<0.40)

NDU ND U ND U NDU (<0.40) (<0.40) (<0.40) (<0.40)

ALNC-2206-0049-0006

A1-14MMEC-2405-4267-0003 March 2019


TABLE 4.3.8. MRS-5 SUMMARY OF SOIL ANALYTICAL RESULTS FOR NITROAMINE COMPOUNDS

I It)

Cl) c-€ C .... Cl) I e ::s 0 -- ·2 0 Cl) ·;:: ...

C Cl) Cl) +: -·2 Cl) C C It) N Cl) Cl)

c-€ Cl) =c C :I ::s Cl) Cl) Cl) C C C cl, Cl) 0 0 .... Cl) .a I C Cl) Cl)

'f - - 0 Cl) ::s ::s ::s 0 0 0 ... N 0 0 0 ... ... ... 0 - - - 'C C -·2 ·2 ·2 >- Cl) Cl) 0 - -C

.C: C .a ... 0 0 ·e 2i 2i 2i :: ... ... ca·- >< 0 - -I I I >< l;t ... z z z <f. CW?. "it CCI Cl)·- :iE :: I

0 C. N .... c-i c-i :c ~ :c z E

Units mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

Screening Level 1,900 2,000 62 5.5 620 NA 49,000 24 NA NA NA

Sam le ID NDU NDU NDU ND U NDU NDU NDU NDU NDU NDU NDU

MRS5-17 (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40)

NDU NDU NDU NDU NDU NDU NDU NDU NDU NDU ND U MRS5-18 (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) (<0.40) .(<0.40) (<0.40) (<0.40) (<0.40)

Notes: J: The associated numerical value is an estimated quantity. mg/kg: milligrams per kilogram NA: Not Applicable/ not a regulated compound ND: nondetect; U: The compounds/analyte were analyzed for, but not detected. The associated numerical value is the sample quantification limit. UJ: The compound/analyte were analyzed for, but not detected. The sample quantification limit is an estimated quantity.

SI Report, MRS- 1, 2, 4, 5, and 6, MCAS Yuma FINAL

• 40

•

Cl) C ·e ca ... -·2

Cl) C >, Cl) Cl) .c: C N - Cl) Cl) C E ::s Cl) 0 .a >, -0 C 0 ... ... - Cl) -·2 .c: ·2

·;:: C. ·;:: 0 I-;- ... I-;-:: It) CCI C

c-€ ·;:: "it-.... I- c-i

mg/kg mg/kg mg/kg

27,000 NA 79

ND U ND U ND U (<0.40) (<0.40) (<0.40)

ND U ND U ND U (<0.40) (<0.40) (<0.40)

ALNC-2206-0049-0006

•

effect endpoints). The SLERA did not recommend cadmium as an ecological COC for the site,

as it is unlikely to cause adverse effects to local populations of wildlife.

8.4 Conclusions and Recommendations

The nature and extent of MC at the site has been sufficiently characterized. Results of the

HHRA and SLERA indicate that further action is not required to protect human health or the

environment from exposure to MC in site soils.

The MEC geophysical investigation identified 271 anomalies as TOIs. Ten percent of these

anomalies (27), as well as three anomalies from within the metallic debris zones were intrusively

investigated. The intrusive investigation identified three .50 caliber small arm projectiles;

however, these items did not contain energetic material and were classified as MDAS. In the

Final 2013 Army Position Paper on Small Arms Ammunition, it is stated that small arms

ammunition do not pose the same explosives safety risk as other military munitions because

small arms ammunition contain a small amount of propellant that burn and may only have

localized consequences for initiation outside a weapon which is an unlikely initiation

(OASA(I&E) 2013). Other metallic anomalies detected at the site with similar geophysical

signatures were not intrusively investigated, and it is possible that these items are similar to the

.50 caliber small arms projectiles found during this RI. Furthermore, the presence of .50 caliber

small arms projectiles at the site is consistent with the past use of the site as a firing- in butt range

to zero-in fixed aircraft guns. Further action for MEC is recommended to ensure that the site

does not present excess risk to human health or the environment from MEC.

Based on the results of this RI, MC in site soils at MRP Site 5 does not pose an unacceptable risk

to human health or the environment. Therefore, no further action is recommended for MC.

Further action is recommended for MEC at MRP Site 5 (i.e., additional intrusive investigation of

anomalies using a statistical evaluation to select the number of anomalies). If results of the

additional intrusive investigation support the absence of explosive hazards, then no further action

will be recommended for MEC.

Based on the results of this RI, further action is recommended for MEC at MRP Site 5. The

details of future action will be developed based upon discussions with the Installation, USEPA,

and ADEQ.

RI results indicate that MC in site soils at MRP Site 5 does not appear to pose an unacceptable

risk to human health or the environment. However, further evaluation of MC may be warranted

pending the results of future MEC action. If no further action is recommended for MEC, then no

further action will be recommended for MC.


Item

[7]

Key Word of Reference Phrases in ROD The MEC geophysical investigation identified 271 anomalies as targets of interest (TOIs). Ten percent of these anomalies (27), as well as threeanomalies from within the metallic debris zones, were intrusively investigated

Section in ROD Where Reference First Appears

Decision Summary Section 5.0

Identification of Referenced Document in the Administrative Record Trevet. 2014. Final Remedial Investigation Report Munitions Response Program Site Unexploded Ordinance 5, Marine Corps Air Station Yuma, Yuma, Arizona. September 4. Page 8-3, Figures 4-1 through 4-4 and Table 4-4.

A1-15MMEC-2405-4267-0003 March 2019

Record of Decision for Munitions Response Program Site 5 Marine Corps Air Station Yuma, Arizona Attachment 1: References

A1-16 March 2019


MMEC-2405-4267-0003

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NOTE: DGM - DIGITAL GEOPHYSICAL MAPPING

SOURCE:

ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE (ESRI) USA SPATIAL FEATURE CLASSES

GRAPHIC SCALE

0 25 50 100

( IN FEET )

1 INCH = 50 FEET

DEPARTMENT OF THE NAVY SAN DIEGO, CALIFORNIA

NAVAL FACILITIES

ENGINEERING COMMAND

REMEDIAL INVESTIGATION MRP SITE 5

MARINE CORPS AIR STATION YUMA YUMA, ARIZONA

FIGURE 4-1 DGM RESULTS

DATE: APRIL 2014

CONTRACT NO.: N62473-10-D-4009

TASK ORDER NO.: 0049

A1-17MMEC-2405-4267-0003 March 2019

. I I_. METAL POST

,- • i l

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- 53 .0 - 22.2 -7.7 2 .0 9.8 17.6 29.4 47.6 T T . •

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TARGET CLASS

GF 0 BELOW THRESHOLD TARGETS (33)

GF 1 PRIMARY LEVEL TARGETS (187)

F 2 SECONDARY LEVEL TARGETS (51)

GF 4 DEBRIS ZONE TARGETS (19)

GF METAL POST (1)

DEBRIS ZONE

MRP SITE 5

SOURCE: ENVIRONMENTAL SYSTEMS RESEARCH INSTITUTE (ESRI) USA SPATIAL FEATURE CLASSES

GRAPHIC SCALE

0 25 50 100

( IN FEET )

1 INCH = 50 FEET


NAVAL FACILITIES

ENGINEERING COMMAND


MARINE CORPS AIR STATION YUMA YUMA, ARIZONA

FIGURE 4-2 TARGET DISTRIBUTION MAP

A1-18MMEC-2405-4267-0003 March 2019

◊

◊~ <}Ca

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METAL POST

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TARGET CLASS

GF 0 BELOW THRESHOLD TARGETS (3 TOIs)

GF 1 PRIMARY LEVEL TARGETS (24 TOIs)

GF 4 DEBRIS ZONE TARGETS (3 TOIs)

DEBRIS ZONE

MRP SITE 5

NOTE: TOIs - TARGET OF INTEREST SOURCE:


GRAPHIC SCALE

0 25 50 100

( IN FEET ) 1 INCH = 50 FEET


NAVAL FACILITIES

ENGINEERING COMMAND


MARINE CORPS AIR STATION YUMA

YUMA, ARIZONA

FIGURE 4-3 SELECTED TOIs FOR INTRUSIVE INVESTIGATION

A1-19MMEC-2405-4267-0003 March 2019

i 25 • ---------------------------------------------------

: ~ i ! I I '31 46 ,s.209 : ' I I M : ' I ' '

4 1,,,30 288 ! ~ 339 !

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MEC Related Debris Target ID Class ID Anomaly Description Anomaly Depth (inches bgs) Quantity Weight MDAS or MPPEH? Identified as Incendary/High Explosive?

47 1 .50 Caliber Small Arms Projectile 6 inches bgs 1 0.1 MDAS No



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TARGET CLASS

FG .50 CALIBER SMALL ARMS AMMUNITION PROJECTILE (3)

FG NON-MUNITIONS RELATED DEBRIS (25)

FG NO CONTACT (2)

DEBRIS ZONE

MRP SITE 5

NOTES : BGS - BELOW GROUND SURFACE ID - IDENTIFICATION

MDAS - MATERIAL DOCUMENTED AS SAFE

MEC - MUNITIONS AND EXPLOSIVES OF CONCERN MPPEH - MATERIAL POTENTIALLY PRESENTING AN

EXPLOSIVE HAZARD

SOU R C E :


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( IN FEET )

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NAVAL FACILITIES

ENGINEERING COMMAND

REMEDIAL INVESTIGATION MRP SITE 5 MARINE CORPS AIR STATION YUMA

YUMA, ARIZONA

FIGURE 4-4 RESULTS OF INTRUSIVE INVESTIGATION

A1-20MMEC-2405-4267-0003 March 2019

! ◊ 2G • ··-··-··-··-··-··-··-··-··-··-··-··-·I

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Table 4-4. Intrusive Investigation Results

Remedial Investigation MRP Site 5

MCAS Yuma, Arizona

Target ID Class ID Anomaly Description

Anomaly Depth

(inches bgs) Quantity Weight

MDAS or

MPPEH?

Identified as Incendary/High

Explosive?

Photo ID (from

photo log)

25 1 Copper fitting 6 1 0.1 MDAS No --

46 1 Aluminum debris 4 inches by 18

inches 6 1 2 MDAS No --

47 1 .50 Caliber Small Arms Ammunitions

Projectile 6 1 0.1 MDAS No 026



69 1 Steel rod 12 inches long 6 1 0.25 MDAS No --

77 1 Large bolt 1 1 0.25 MDAS No --

84 1 Metal rod 8 inches long by .5 inches

diameter 12 1 2 MDAS No --

100 4 Steel plate 15 inches by 24 inches by

.25 inches 4 1 25 MDAS No 023

108 4

Concrete block 3 feet by 4 feet / large

bolt pieces 6 inches long by 2 inches

diameter / assorted metal debris

12 10 Unknown

Left in Place MDAS No 024

118 1 Steel rod 18 inches long 12 1 0.25 MDAS No --

125 1 Concrete with rebar 6 2 Unknown

Left in Place MDAS No 025

131 4 Steel boxes 12 inches by 12 inches

concrete-filled 8 2

Unknown

Left in Place MDAS No --

141 1 Nail 1 1 0.1 MDAS No --

146 1 Braided wire 12 inches long 1 1 0.5 MDAS No --

157 1 Metal debris 1 1 0.1 MDAS No --

174 1 Metal debris 6 1 1 MDAS No --

177 1 Metal debris 12 inches long 6 1 2 MDAS No --

184 1 Metal debris 6 1 0.1 MDAS No --

187 1 No Contact - - - MDAS No --

189 0 No Contact - - - MDAS No --

A1-21MMEC-2405-4267-0003 March 2019

Table 4-4. Intrusive Investigation Results

Remedial Investigation MRP Site 5

MCAS Yuma, Arizona

Target ID Class ID Anomaly Description

Anomaly Depth

(inches bgs) Quantity Weight

MDAS or

MPPEH?

Identified as Incendary/High

Explosive?

Photo ID (from

photo log)

209 1 Metal rod 8 inches long 3 1 0.2 MDAS No --

210 1 Chain 12 inches long 4 1 0.5 MDAS No --

218 1 Nail 4 2 0.1 MDAS No --

222 1 Large bolt 6 1 0.1 MDAS No --

230 0 Aluminum debris 1 1 0.1 MDAS No --

256 1 Steel plate 14 inches by 4 inches by .25

inches 2 1 3 MDAS No --

282 1 Rebar 6 inches long 3 1 0.25 MDAS No --

288 1 Metal debris and heavy wire 2 feet long 1 8 2 MDAS No --



339 1 Large nail 3 1 0.1 MDAS No --

Note:

Dashed lines (--) indicate no photo available

bgs - below ground surface

MDAS - material documented as safe

MPPEH - material potentially presenting an explosive hazard

A1-22MMEC-2405-4267-0003 March 2019





























and ADEQ.





FINAL RI 8-3 September 2014

MRP Site 5, MCAS Yuma

Item

[8]


Phrases in ROD

However, these items did

not contain energetic

material and were

classified as MDAS

Section in ROD Where

Reference First Appears

Decision Summary

Section 5.0

Identification of Referenced Document in

the Administrative Record

Trevet. 2014. Final Remedial Investigation

Report Munitions Response Program Site

Unexploded Ordinance 5, Marine Corps Air

Station Yuma, Yuma, Arizona. September 4.

Page 8-3

A1-23MMEC-2405-4267-0003 March 2019

Item

[9]

Key Word of Reference Phrases in ROD

do not pose the same explosives safety risk as other military munitions because small arms ammunition contains a small amount of propellant that burns and may only have localized consequences for initiation outside a weapon, which is an unlikely initiation



Identification of Referenced Document in the Administrative Record

Trevet. 2014. Final Remedial Investigation Report Munitions Response Program Site Unexploded Ordinance 5, Marine Corps Air Station Yuma, Yuma, Arizona. September 4. Page 8-3.





























and ADEQ.





FINAL RI 8-3 September 2014 MRP Site 5, MCAS Yuma A1-24MMEC-2405-4267-0003 March 2019

Item

[10]


The RI recommended no further action for MC, depending on the outcome of further MEC investigation

Section in ROD Where References First Appears Decision Summary,

Section 5.0

Identif ication of Referenced Document in the Administrative Record

Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program

Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Page 1-4.

During the MEC intrusive investigation, 20 soil samples were collected from 10 locations at

the site. Two soil samples were collected at each location: one from the surface and another

from approximately 3 to 3.5 feet below ground surface (bgs). Six soil samples were collected

adjacent to and below the MEC-related debris (.50 caliber small arms projectiles) encountered

at three TOI locations. Four samples were collected adjacent to and below non-MEC-related

debris, and 10 samples were collected randomly throughout the site.

Soil samples were analyzed for MC consisting of metals and explosives. Samples were

also analyzed for the full suite of target analyte list (TAL) metals and mercury to provide

additional information about the site. Explosives were not detected in any of the soil samples.

All 23 TAL metals were detected in one or more of the soil samples. Mercury was not detected

in any of the soil samples. Metals detected in site soils that were identified as potential risk or

hazard drivers to humans and ecological receptors were further evaluated for background

contributions using site- to-background statistical and geochemical techniques.

An HHRA and SLERA were performed as part of the RI to evaluate potential risk and hazards

associated with metals detected at the site. Results indicated that MC in soil does not pose

an unacceptable risk to human health or the environment. The RI recommended no further

action for MC, depending on the outcome of further MEC investigation.

1.3 REGULATORY FRAMEWORK

The U.S. Department of Defense (DoD) has the authority to undertake Comprehensive

Environmental Response, Compensation, and Liability Act (CERCLA) response actions

under Title 42 United States Code (USC) §9604, Title 10 USC §2708, and Federal Executive

Order 12580. Munitions response actions are conducted under the process outlined in the

National Contingency Plan, as authorized by CERCLA.

MCAS Yuma is the federal facility under the Defense Environmental Restoration Program.

The U.S. Department of the Navy (Navy) is the lead agency and the EPA is the lead regulatory

agency responsible for the MCAS Yuma Installation Restoration Program (IRP) and MRP. The

Arizona Department of Environmental Quality (ADEQ) is the state regulatory agency

overseeing IRP and MRP activities.

Because MCAS Yuma is listed on the National Priorities List, the Navy follows EPA RI and

feasibility study protocols for site characterization and cleanup (EPA 1988). The

aforementioned agencies comprise the Federal Facility Agreement Team that governs the

MCAS Yuma IRP and MRP.

UMAC-2006-0009-0010 Fnl Add RI Rpt 1-4 Final Additional Remedial Investigation Report MRP

Site 5, MCAS Yuma, Yuma, Arizona DCN:

UMAC-2006-009-010 CTO

No. 0009

A1-25MMEC-2405-4267-0003 March 2019


A1-26 March 2019


MMEC-2405-4267-0003

Item

(11)


None of the targets encountered to a depth of approximately 3 feet bgs were identified as MEC or MPPEH




Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Page 6-1, Table 2-1.

6.0 CONCLUSIONS AND RECOMMENDATIONS

An extensive investigation designed to characterize the nature and extent of MEC at the site have

been completed and no MEC or MPPEH have been found at MRP Site 5. Munitions used at the

site, which was formerly a firing- in butt used to zero-in fixed aircraft guns, would be found on the

surface or in the shallow subsurface soil, if present. Metallic debris present at the surface and in

the subsurface has been removed from MRP Site 5. Following excavation and screening of soil to

a depth of 16 inches bgs, a geophysical investigation was conducted across the entire footprint of

MRP Site 5. This survey was designed to detect 20mm projectiles in the subsurface to a depth of

18 inches bgs. The DGM revealed 124 targets for intrusive investigation. All targets were

removed, and all locations were checked for remaining metallic debris and cleared prior to

backfilling. None of the targets were identified as MEC or MPPEH. Two expended 20mm

practice projectiles, which did not contain explosives prior to being fired, were detected and

classified as MDAS, and expended small arms that were also classified as MDAS were recovered

as a result of screening the top 16 inches of soil, and/or intrusive investigation. All other metallic

items found during the Additional RI were identified as construction debris. The results of updated

HHRA and SLERA conducted using data from this additional RI and previously collected data

indicate that the metals present in the site soils at MRP Site 5 do not pose an unacceptable risk to

human health or the environment. This conclusion is consistent with previous conclusions

regarding MC in soil at the site. Explosives have not been detected in any soil samples from MRP

Site 5.

Based on the results of the additional RI, no further action is recommended for MEC and MC at

MRP Site 5.

UMAC-2006-0009-0010 Fnl Add RI Rpt 6-1 Final Additional Remedial Investigation Report

MRP Site 5, MCAS Yuma, Yuma, Arizona

DCN: UMAC-2006-0009-0010 CTO No. 0009

A1-27MMEC-2405-4267-0003 March 2019


A1-28


MMEC-2405-4267-0003 March 2019

TABLE 2-1 INTRUSIVE RESULTS

Page 2 of 3

Final Additional Remedial Investigation Report


DCN: UMAC-2006-0009-0010

CTO No. 0009

Target ID Dig Date Easting Northing Description

Depth below

excavation

surface (in)

Depth below pre-

excavation

surface (in)

MC Soil

Sample ID

45 02/06/16 438679.9 600505.9 2x2" scrap 0 16 --

46 02/06/16 438596 600505.9 Grid nail 0 16 --

47 02/08/16 438577.6 600507.8 5x8" scrap 14 30 --

48 02/06/16 438715.8 600509.4 8" rod 14 30 --

49 02/06/16 438727.1 600512.4 2 lb. sledge hammer 24 40 --

50 02/06/16 438560.1 600514.2 4" wire 1 17 --

51 02/06/16 438513.6 600517 8" scrap 8 24 --

52 02/06/16 438557.5 600517.8 4x4" plate 10 26 --

53 02/06/16 438548.1 600517.8 14" wire 6 22 --

54 02/06/16 438586.4 600519.4 4x4" scrap 6 22 --

55 02/06/16 438534.3 600519.5 5" rod 14 30 --

56 02/06/16 438708.5 600520.9 6" wire 6 22 --

57 02/06/16 438543 600522.3 3" bolt 10 26 --

58 02/06/16 438650.3 600522.6 QA seed 002 3 19 --

59 02/06/16 438535.2 600522.8 4" nail 10 26 --

60 02/06/16 438570.6 600523.5 3" bolt 11 27 --

61 02/08/16 438739.3 600528.9 4" nail 3 19 --

62 02/06/16 438691 600528.9 1x2" scrap 0 16 --

63 02/06/16 438574.6 600530.3 (2) cans 8 24 --

64 02/08/16 438565.6 600530.7 3" washer 4 20 TOI-8

65 02/06/16 438508 600531 8" rod 6 22 --

66 02/06/16 438555.3 600531.6 12" bolt 6 22 --

67 02/06/16 438705.8 600532.4 5" nail 6 22 --

68 02/06/16 438513.3 600533.1 6" bar stock 6 22 --

69 02/06/16 438558.4 600534.2 3" bolt 3 19 --

70 02/06/16 438567.1 600534.5 3x6" scrap 6 22 --

71 02/06/16 438583.6 600534.5 Can 6 22 --

72 02/06/16 438657.8 600535.3 24" rebar 12 28 --

73 02/06/16 438587.2 600536.1 3" bolt 3 19 --

74 02/06/16 438655.3 600538 24" rebar 12 28 --

75 02/08/16 438638.4 600538.9 3" scrap 0 16 --

76 02/08/16 438606.9 600540.2 24" rebar 8 24 --

77 02/08/16 438515.3 600540.8 3x3" plate 3 19 --

78 02/08/16 438561.9 600544 Can 3 19 --

79 02/08/16 438572 600544 20mm practice 6 22 TOI-1

80 02/08/16 438585 600544.3 8" rod 4 20 --

81 02/08/16 438713.1 600544.6 8" j bolt 10 26 --

82 02/08/16 438737.6 600545.4 Can 14 30 --

83 02/08/16 438741.1 600547.7 24" t post 16 32 --

84 02/08/16 438735.7 600548.7 5x5" scrap 0 16 --

85 02/08/16 438666.9 600551 13" rod 8 24 --

86 02/08/16 438543.7 600551.3 Can 4 20 --

87 02/08/16 438685.8 600552.9 6" rod 4 20 --

88 02/08/16 438676.7 600553.1 5" rod 3 19 --

89 02/08/16 438613.7 600553.1 3" nail 0 16 --

90 02/08/16 438604.6 600557.6 10" rod 6 22 --

91 02/08/16 438642.8 600560.1 Asphalt 12 28 --

A1-29MMEC-2405-4267-0003 March 2019


Page 1 of 3



DCN: UMAC-2006-0009-0010

CTO No. 0009


Depth below

excavation

surface (in)

Depth below pre-

excavation

surface (in)

MC Soil

Sample ID

1 02/06/16 438695.7 600406.2 Grid nail 0 16 --

2 02/06/16 438559.4 600407.1 No find 0 NA --

3 02/06/16 438595.8 600407.5 Grid nail 0 16 --

4 02/06/16 438496.4 600407.5 Corner nail and 6" nail 2.5"

north at 1" 0 16

--

5 02/06/16 438496.4 600412 Nail 1 17 --

6 02/06/16 438506.9 600412 No find 0 NA --

7 02/06/16 438617.5 600413.8 3" scrap 0 16 --

8 02/06/16 438632.6 600418.3 2" nail 0 16 --

9 02/06/16 438672.5 600420.4 No find 0 NA --

10 02/06/16 438531.1 600421.1 2.5" scrap and 50 cal bullet 6 22 TOI-3

11 02/06/16 438714.6 600422.9 No find 0 NA --

12 02/06/16 438581.1 600423.3 18" reinforced hose 28 44 --

13 02/06/16 438629.6 600431.3 4x7" scrap 12 28 --

14 02/06/16 438535.3 600432 QA seed 001 4 20 --

15 02/06/16 438707.1 600432.3 50 cal bullet 1 17 TOI-2

16 02/06/16 438712.4 600433.2 QA seed 003 3 19 --

17 02/06/16 438608.8 600433.4 3" bolt 1 17 --

18 02/06/16 438726.8 600433.8 10" rod 14 30 --

19 02/08/16 438627 600437.8 18" cable& 3" bolt 10 26 --

20 02/06/16 438565.9 600440.8 Washer and scrap 5 21 --

21 02/06/16 438510.8 600443.5 No find 0 NA --

22 02/06/16 438529.3 600445.2 3" bolt 4 20 --

23 02/08/16 438593.1 600452.1 (2) 2" washers 2 18 --

24 02/06/16 438606.7 600454.8 50 cal bullet 4 20 TOI -4

25 02/06/16 438574.8 600456.5 2" bolt 2 18 --

26 02/06/16 438587.2 600458.7 2" bolt 1 17 --

27 02/06/16 438633.6 600467 3x3" scrap 6 22 --

28 02/06/16 438611.3 600467.7 Reinforced concrete slab Left

in place 2 18

--

29 02/06/16 438616 600469.3 1" nut 0 16 --

30 02/06/16 438608.5 600472.8 Reinforced concrete slab Left

in place 2 18

--

31 02/06/16 438654.6 600479.9 License plate 8 24 --

32 02/06/16 438518.5 600482.4 2.5" bolt 2 18 TOI-9

33 02/06/16 438497.8 600483.1 (8) 2.5" bolts 14 30 --

34 02/06/16 438549.6 600487.4 4" bolt 4 20 --

35 02/06/16 438659.5 600490.1 4" scrap 0 16 --

36 02/06/16 438712.4 600493.9 2" nail 1 17 --

37 02/06/16 438504.3 600494.8 12" metal rod 8 24 --

38 02/08/16 438655.6 600497.5 10" rod 14 30 TOI-7

39 02/06/16 438542.6 600500.6 2" scrap 4 20 --

40 02/06/16 438497.5 600501.3 4" bolt 18 34 --

41 02/06/16 438524.4 600502.8 10" rod 3 19 --

42 02/06/16 438566.9 600503.3 3" scrap 4 20 --

43 02/06/16 438745.6 600505.5 Grid nail 0 16 --

44 02/06/16 438695.9 600505.8 Grid nail 0 16 --

A1-30MMEC-2405-4267-0003 March 2019


Page 3 of 3



DCN: UMAC-2006-0009-0010

CTO No. 0009


Depth below

excavation

surface (in)

Depth below pre-

excavation

surface (in)

MC Soil

Sample ID

92 02/08/16 438715.3 600563.5 3x3" scrap 1 17 --

93 02/08/16 438637.5 600566 1x1" scrap 3 19 --

94 02/08/16 438744.3 600567.8 Can 1 17 --

95 02/08/16 438495.8 600571.3 50 cal bullet 2 18 TOI-6

96 02/08/16 438507.7 600573.2 50 cal bullet 2 18 TOI-5

97 02/08/16 438694.9 600573.4 3" nail 8 24 --

98 02/08/16 438596.6 600579.1 Grid nail 0 16 --

99 02/08/16 438695.6 600579.3 Grid nail 0 16 --

CA1 02/08/16 438504 600539.5 (2) 50 cal bullet 10 26 TOI-10

CA2 02/08/16 438515 600539.5 4" scrap 5 21 --

CA3 02/08/16 438544.7 600539.5 12" wire 4 20 --

CA4 02/08/16 438626.1 600553.8 6" wire 2 18 --

CA5 02/08/16 438743.8 600552.7 can/8" rebar 10 26 --

100 05/12/16 438564.3 600482.39 Steel 6 30 TOI-11

101 05/12/16 438567.23 600477.07 Wire 3 27 --

102 05/12/16 438567.37 600471.44 Rebar 12 36 --

103 05/12/16 438569.54 600472.74 Wire 3 27 --

104 05/12/16 438572.21 600472.31 Wire 1 25 --

105 05/12/16 438572.54 600480.69 Nut 2 26 --

106 05/12/16 438576.4 600468.91 Wire 1 25 --

107 05/12/16 438577.9 600474.41 Rebar 6 30 --

108 05/12/16 438578.28 600467.54 Bolt 8 32 --

109 05/12/16 438580.16 600467.61 Bolt/Nail 3 27 --

110 05/12/16 438581.17 600489.39 Bolt 4 28 --

111 05/12/16 438581.46 600465.95 Bolt/Wire 10 34 --

112 05/12/16 438581.69 600474.67 Rebar 6 30 --

113 05/12/16 438586.95 600473.46 Bolt 4 28 --

114 05/12/16 438587.46 600489.43 Wire 2 26 --

115 05/12/16 438588.25 600486.61 Rebar 6 30 --

116 05/12/16 438591.72 600483.87 Bolt 8 32 --

117 05/12/16 438592.04 600493.45 Rebar 6 30 --

118 05/12/16 438593.45 600481.34 Nut 2 26 TOI-12

119 05/12/16 438595.95 600484.35 No find NA NA --

Note: Depth below pre-excavation surface is based on an excavation depth of 16 inches below the original surface for

locations 1 through CA-5 and an excavation depth of 24 inches below the original surface for locations 100-119.

A1-31MMEC-2405-4267-0003 March 2019


MMEC-2405-4267-0003 A1-32 March 2019


Item

[12]


Explosives have not been detected in any soil samples collected from MRP Site 5
























Site 5.


MRP Site 5.



DCN: UMAC-2006-0009-0010

CTO No. 0009

A1-33MMEC-2405-4267-0003 March 2019

Item

[13]


additional RI concluded that NFA is recommended for MEC and MC at MRP Site 5
























Site 5.


MRP Site 5.



DCN: UMAC-2006-0009-0010

CTO No. 0009

A1-34MMEC-2405-4267-0003 March 2019

Figure 4-1

Human Health Conceptual Site Exposure Model(1)

Item

[14]


conceptual site model



Identification of Referenced Document in the Administrative Record Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Figure 4-1, Figure 5-1.

Occu

pati

on

al

Wo

rker

[C/F

] (2

)

Co

nstr

ucti

on

Wo

rker

[F]

Hyp

oth

eti

cal

Resid

en

t [F

]

SOURCE INTERACTION HUMAN RECEPTORS

(Current [C] and Future [F])

PRIMARY

SOURCE

PRIMARY RELEASE

MECHANISMS

SECONDARY

SOURCE

RELEASE

MECHANISMS

EXPOSURE

MEDIA EXPOSURE

ROUTE

EXPOSURE PATHWAYS KEY Complete pathw ay

Potentially complete pathw ay Incomplete pathw ay

Complete component or linkage

Potentially complete component or linkage Entrainment /

Dispersion Outdoor Air Inhalation (Particulates)

Munitions

Constituents

Infiltration

Through Soil Soil

Mechanical

Redistribution

Erosion/Runoff

Surface Soil (3) Incidental Ingestion

Dermal Absorption

Infiltration/ Percolation

Subsurface Soil (3) Incidental Ingestion

Dermal Absorption

MEC at

Surface (4) Incidental Surface

MEC in

Subsurface (4) Intrusive

Subsurface

Access

Available

No Access

ACTIV ITY ACCESS

NOTES: 1) Groundwater, surf ace water, and sediment sampling not perf ormed.

2) Current occupational worker conserv atively used to assess inf requent v isits to Site by Base Env ironmental Staf f.

3) Site prov ides no signif icant habitat to ecological receptors at this time.

4) All potential targets identif ied during the two DGM portions of the f ield inv estigations were intrusiv ely inv estigated. These inv estigations covered 100% of the area of MRP Site 5, and no MEC

was f ound. Two pieces of MPPEH, determined to be MDAS, were remov ed f rom the site. As such, it is determined that MEC is no longer present to 3.5 f eet bgs at MRP Site 5.

A1-35MMEC-2405-4267-0003 March 2019

1-1

----. I I

,- : I I I I I I I I I I I I I I I I I I : -----+ : l_ ---► ------------------------------------------ 1 I I I

EEE

Figure 5-1

Preliminary Ecological Conceptual Site Exposure Model

Terr

estr

ial

Pla

nts

/ S

oil In

vert

eb

rate

s

[C/F

]

Mam

malian

/ A

via

n R

ecep

tors

[C

/F]

SOURCE INTERACTION

ECOLOGICAL

RECEPTORS (3,4)

(Current [C] and Future [F])

PRIMARY

SOURCE

PRIMARY

RELEASE MECHANISMS

SECONDARY SOURCE (1)

RELEASE

MECHANISMS

EXPOSURE

MEDIA EXPOSURE

ROUTE

EXPOSURE PATHWAYS KEY

Complete pathw ay

Potentially complete pathw ay

Incomplete pathw ay Complete component or linkage Potentially complete component or linkage

Incidental Ingestion

Mechanical Redistribution

Surface Soil (2) Dermal Absorption

Munitions

Constituents

Infiltration Through Soil

Deposit onto

Soil Surface

Soil (Shallow and Subsurface)

Erosion/Runoff

Infiltration/ Percolation

Subsurface Soil (2)

Direct Contact

Incidental Ingestion

Dermal Absorption

Direct Contact

NOTES: 1) Groundwater, surf ace water, and sediment sampling not perf ormed as no aquatic habitat is present.

2) Surf ace Soil is 0-1.0 f eet bgs; Total Soil interv al is def ined as 0 to 3.5 f eet bgs.

3) Site prov ides no signif icant habitat to ecological receptors at this time.

4) Potential f uture use of the Site could consist of a parking lot or an extension of the aircraf t parking apron.

A1-36

MMEC-2405-4267-0003 March 2019

i--I I I I I I I I I

----

: ---+ : ---► I

L-----

----------------:

----

I I I I I I I I I I I I I ----

Item

[15]

Key Word of Reference Phrases in ROD Following excavation and screening of soil to a depth of 16 inches bgs, a geophysical investigation was conducted across the entire footprint of MRP Site 5. This survey was designed to detect 20mm projectiles in the subsurface to a depth of 18 inches bgs


Identification of Referenced Document in the Administrative Record Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. March. Page 6-1.


An extensive investigation designed to characterize the nature and extent of MEC at the site have been completed and no MEC or MPPEH have been found at MRP Site 5. Munitions used at the site, which was formerly a firing- in butt used to zero-in fixed aircraft guns, would be found on the surface or in the shallow subsurface soil, if present. Metallic debris present at the surface and in the subsurface has been removed from MRP Site 5. Following excavation and screening of soil to a depth of 16 inches bgs, a geophysical investigation was conducted across the entire footprint of MRP Site 5. This survey was designed to detect 20mm projectiles in the subsurface to a depth of 18 inches bgs. The DGM revealed 124 targets for intrusive investigation. All targets were removed, and all locations were checked for remaining metallic debris and cleared prior to backfilling. None of the targets were identified as MEC or MPPEH. Two expended 20mm practice projectiles, which did not contain explosives prior to being fired, were detected and classified as MDAS, and expended small arms that were also classified as MDAS were recovered as a result of screening the top 16 inches of soil, and/or intrusive investigation. All other metallic items found during the Additional RI were identified as construction debris. The results of updated HHRA and SLERA conducted using data from this additional RI and previously collected data indicate that the metals present in the site soils at MRP Site 5 do not pose an unacceptable risk to human health or the environment. This conclusion is consistent with previous conclusio ns regarding MC in soil at the site. Explosives have not been detected in any soil samples from MRP Site 5.

Based on the results of the additional RI, no further action is recommended for MEC and MC at MRP Site 5.

UMAC-2006-0009-0010 Fnl Add RI Rpt 6-1 Final Additional Remedial InvestigationReport MRP Site 5, MCAS Yuma, Yuma, Arizona

DCN: UMAC-2006-0009-0010 CTO No. 0009

A1-37MMEC-2405-4267-0003 March 2019

Item

[16]

Key Word of Reference Phrases in ROD potential MC-related constituents detected in soil are metals, most of w hich

w ere detected at concentrations consistent w ith site-specific background


Identification of Referenced Document in the Administrative Record Tetra Tech EC, Inc. 2017. Final Additional Remedial Investigation Report, Munitions Response Program Site 5, Marine Corps Air

Station Yuma, Yuma, Arizona. March. Page 4-3.

Based on the results of the site investigations, soil is the exposure medium of concern. The only

potential MC-related constituents detected in soil are metals, most of which were detected at

concentrations consistent with site-specific background. No explosives have been detected in the

soil. Potential release and transport mechanisms for metals in soil include: wind dispersion from

exposed surface soils, mechanical distribution during future construction activities, possible

transport in surface water runoff, or potential leaching to groundwater. The very dry climate

combined with the flat topography of the site result in very little potential for surface water runoff.

Similarly, the combination of little annual rainfall with significant evapotranspiration rates along

with the small site footprint and depth to groundwater (65 to 140 feet bgs) suggest that site-related

impacts to groundwater quality are unlikely. Furthermore, groundwater at MRP Site 5 is not a

current source of drinking water, and groundwater impacts from MRP Site 5 are not expected

based upon groundwater sampling previously conducted as part of the Operable Unit 1 RI.

Groundwater impacts from the site are also not expected based upon the minimal detections of

metals above background threshold concentrations. Consequently, groundwater sampling was not

performed during the Additional RI.

Current potentially exposed human receptors are limited to individuals with access through the

flight line. There are no plans for future use of MRP Site 5. However, the site could be re-purposed

as an aircraft loading area and/or extension of the aircraft parking apron, which would result in

similar access limitations. Although the plans for future site use would not entail significant

excavation activities, construction/excavation workers may be a potential future receptor group

relative to the soil.

In addition to current and future site workers (occupational workers) and possible future

construction workers, the preliminary CSM presented in the original HHRA considered

maintenance workers, possible trespassers, and hypothetical future residential site users. Of these

potential human receptors, only the following were quantitatively evaluated in the original HHRA,

as the other receptors would have less intensive or shorter exposure to site soils:

• Current and future base staff (occupational workers);

• Future construction workers; and

• Hypothetical future adult and child residents.

No reasonably anticipated additional receptors have been identified.

4.3 DATA EVALUATION UPDATE AND SELECTION OF COPCS

The data set for this update to the HHRA consisted of samples from the 2010 SI and 2014 RI, as

well as samples collected for the 2016 Additional RI. Only metals were evaluated as part of the

HHRA, as explosives were not detected at the site during the SI, RI, or Additional RI.

The complete data tables for detected analytes are provided in Table 3-1.



DCN: UMAC-2006-0009-0010

CTO No. 0009 A1-38MMEC-2405-4267-0003 March 2019

1-1

Item

[17]

Key Word of Reference Phrases in ROD Current potentially exposed human receptors are limited to individuals with access through the flight line



Based on the results of the site investigations, soil is the exposure medium of concern. The only potential MC-related constituents detected in soil are metals, most of which were detected at concentrations consistent with site-specific background. No explosives have been detected in the soil. Potential release and transport mechanisms for metals in soil include: wind dispersion from exposed surface soils, mechanical distribution during future construction activities, possible transport in surface water runoff, or potential leaching to groundwater. The very dry climate combined with the flat topography of the site result in very little potential for surface water runoff. Similarly, the combination of little annual rainfall with significant evapotranspiration rates along with the small site footprint and depth to groundwater (65 to 140 feet bgs) suggest that site-related impacts to groundwater quality are unlikely. Furthermore, groundwater at MRP Site 5 is not a current source of drinking water, and groundwater impacts from MRP Site 5 are not expected based upon groundwater sampling previously conducted as part of the Operable Unit 1 RI. Groundwater impacts from the site are also not expected based upon the minimal detections of metals above background threshold concentrations. Consequently, groundwater sampling was not performed during the Additional RI.

Current potentially exposed human receptors are limited to individuals with access through the flight line. There are no plans for future use of MRP Site 5. However, the site could be re-purposed as an aircraft loading area and/or extension of the aircraft parking apron, which would result in similar access limitations. Although the plans for future site use would not entail significa nt excavation activities, construction/excavation workers may be a potential future receptor group relative to the soil.

In addition to current and future site workers (occupational workers) and possible future construction workers, the preliminary CSM presented in the original HHRA considered maintenance workers, possible trespassers, and hypothetical future residential site users. Of these potential human receptors, only the following were quantitatively evaluated in the original HHRA, as the other receptors would have less intensive or shorter exposure to site soils:

• Current and future base staff (occupational workers);

• Future construction workers; and

• Hypothetical future adult and child residents.

No reasonably anticipated additional receptors have been identified.

4.3 DATA EVALUATION UPDATE AND SELECTION OF COPCS

The data set for this update to the HHRA consisted of samples from the 2010 SI and 2014 RI, as well as samples collected for the 2016 Additional RI. Only metals were evaluated as part of the HHRA, as explosives were not detected at the site during the SI, RI, or Additional RI.

The complete data tables for detected analytes are provided in Table 3-1. UMAC-2006-0009-0010 Fnl Add RI Rpt 4-3 Final Additional Remedial Investigation Report

MRP Site 5, MCAS Yuma, Yuma, Arizona DCN: UMAC-2006-0009-0010


1-1

Item

[18]

Key Word of Reference Phrases in ROD MRP Site 5 does not represent nor afford significant habitat for ecological receptors



visited by a MCAS Yuma biologist prior to intrusive activities being performed at the site, and no

wildlife issues were identified. Given its small size (1 acre), the close proximity to existing

taxiways and service areas at MCAS Yuma, and lack of vegetation, the site was determined to not

provide significant value as wildlife habitat. Current conditions at the site are shown in

photographs included in Appendix B, and depict a graded, highly disturbed environment with no

vegetation present.

While MRP Site 5 does not represent nor afford significant habitat for ecological receptors, this

condition does not exclude the potential for opportunistic growth of terrestrial plants or occasional

transient occurrence of wildlife species either within MCAS Yuma or MRP Site 5. For purposes

of the SLERA, ecological receptors, including terrestrial plants, soil invertebrates, and wildlife

species (i.e., birds and mammals), were assumed to have the opportunity to become established or

occur on site should it remain vacant.

5.2 EXPOSURE PATHWAYS AND PECSM

5.2.1 Environmental Media of Concern and Migration Pathways

The pathways analysis describes the potential migration pathways and exposure routes by which

ecological receptors could come into contact with site-related chemical constituents. If the

migration pathway and exposure routes to environmental media are accessible by ecological

receptors, the exposure pathway/route is deemed complete. A complete migration pathway and

exposure route indicates that potential exposure to site-related constituents by ecological receptors

is possible. If the exposure pathways or routes are deemed incomplete, or if no ecological receptors

or populations are present, little or no risk to such resources can be inferred.

Chemicals associated with historical munitions used on the site are MC consisting of metals and

explosives. Sampling data from the SI, 2014 RI, and the Additional RI have confirmed that no

nitro-aromatic organic compounds related to the historical use of the range have been detected.

Therefore, the only chemical constituents detected at the site that are related to the historical use

of the range are limited to metals.

The primary environmental media affected by constituent releases from historical range uses

include shallow surface soils and subsurface soils. No aquatic habitats are associated with MRP

Site 5, and, therefore, sediment or surface water samples were not collected. Groundwater beneath

MCAS is approximately 65 to 140 feet below ground level. Generally, groundwater flow is in a

northwest direction. No areas of groundwater discharge to surface water were identified on or

near MRP Site 5. Therefore, the potential for contact between groundwater and ecological

receptors at the Site is considered an incomplete pathway, and was not considered further in the

exposure assessment and risk characterization.

Typically for EPA risk assessments, shallow surface soils are generally defined as soils occurring

within the 0-1 foot interval. Historical investigations at MRP Site 5 included the collection of soil



DCN: UMAC-2006-0009-0010

CTO No. 0009 A1-40MMEC-2405-4267-0003

March 2019

1-1

Item

[19]


Updated HHRA results concluded that incremental risk for each receptor (including current workers, construction workers, and hypothetical future residents) at MRP Site 5 is less than 1x10-6, well below the upper end of the acceptable cancer risk range





and well below the upper end of the acceptable cancer risk range. In addition, the incrementa l

hazard indices are less than 1 for all receptors, indicating that there is little potential for a non-

cancer systemic effect. No metal was recommended to be carried forward as a human health

chemical of concern for the site. In fact, all four metals identified as COPCs (aluminum, iron,

manganese, and vanadium), based on a comparison to PALs (i.e., modified SRLs or RSLs for 1.0

x10-6 cancer risk or HI = 0.1), were detected at concentrations consistent with natural soils, and,

therefore, could have been eliminated as potential COPCs using ADHS criteria. This conclusion

corroborates results of the SI and 2014 RI HHRA, which concluded that there was no excess risk

to human health and recommended no further action for MCs pending completion of the MEC

investigation. Results of the 2016 Additional RI support a finding of no further action for MC in

site soil.

Based on a comparison of the updated HHRA to the original HHRA, the only notable change was

with respect to construction workers potentially exposed to manganese bound to particulate s

generated during construction, but the updated total HI for construction workers was still less

than 1. Although this HI was based on chronic toxicity values even though the exposure duration

for construction was only 1 year, no subchronic toxicity values for manganese were availab le.

Furthermore, the concentrations of manganese detected in MRP Site 5 soils were not significant ly

different, statistically, than background concentrations.



DCN: UMAC-2006-0009-0010


Item

[20]


No metal was recommended to be carried forward as a human health chemical of concern for the site


Decision Summary

Section 7.0



and well below the upper end of the acceptable cancer risk range. In addition, the incrementa l

hazard indices are less than 1 for all receptors, indicating that there is little potential for a non-

cancer systemic effect. No metal was recommended to be carried forward as a human health

chemical of concern for the site. In fact, all four metals identified as COPCs (aluminum, iron,

manganese, and vanadium), based on a comparison to PALs (i.e., modified SRLs or RSLs for 1.0

x10-6 cancer risk or HI = 0.1), were detected at concentrations consistent with natural soils, and,

therefore, could have been eliminated as potential COPCs using ADHS criteria. This conclusion

corroborates results of the SI and 2014 RI HHRA, which concluded that there was no excess risk

to human health and recommended no further action for MCs pending completion of the MEC

investigation. Results of the 2016 Additional RI support a finding of no further action for MC in

site soil.

Based on a comparison of the updated HHRA to the original HHRA, the only notable change was

with respect to construction workers potentially exposed to manganese bound to particulate s

generated during construction, but the updated total HI for construction workers was still less

than 1. Although this HI was based on chronic toxicity values even though the exposure duration

for construction was only 1 year, no subchronic toxicity values for manganese were availab le.

Furthermore, the concentrations of manganese detected in MRP Site 5 soils were not significant ly

different, statistically, than background concentrations.



DCN: UMAC-2006-0009-0010 CTO No. 0009 A1-42MMEC-2405-4267-0003 March 2019

Item

[21]


No contaminants of potentialecological concern (COPECs) were identified on the basis of the updated SLERA




This physiological mechanism can assist in reducing exposure to these metals. The

exposure assessment and risk characterization assumed that all exposures were to be

associated, without considering metabolic mechanisms that would reduce potential

exposure once ingested.

• The ESLs are based on studies with test species that are highly sensitive to chemical

stressors and provide a basis for defining similar effects endpoints to the wildlife receptors

being evaluated.

5.5.3 Analytical Data Distribution and Coverage

There is uncertainty associated with how the spatial coverage of collected incremental sampling

methodology sample data is representative of existing site conditions. Samples were collected

from areas where observed activity or concentrated metallic anomalies had occurred. This resulted

in collection of soils data in close proximity to where metal debris had been located. This may

have resulted in an overestimate of 95% UCL applied in the refined exposure assessment.

5.6 SUMMARY AND CONCLUSIONS

An update to the original SLERA (Trevet 2014a) was performed based on the collection of

additional soil samples from the subsurface interval of the MRP Site 5 area. As no shallow soil

samples were collected, the existing conclusions of the original SLERA (Trevet 2014a) for shallow

soils of no risk to ecological receptors remains consistent and valid. A conservative screening-

level assessment using the maximum detected concentrations of metals in the total soils interva l

(0-3.5 feet) revealed exceedances of conservative LANL ESLs for antimony, barium, cadmium,

copper, lead, manganese, nickel, thallium, vanadium, and zinc. These metals were moved forward

into a refined screening- level evaluation to assess exposure and risk to specific assessment

endpoints.

A refined screening- level assessment was performed, using the 95% UCL, which represents a more

realistic EPC comparison to receptor-specific ESLs for the total soil interval (0-3.5 feet bgs). All

detected metal 95% UCL concentrations remained below their corresponding background

concentrations, except for a single detection of silver. Maximum and 95% UCL concentrations of

silver remained below screening values for all receptor groups. Based on the refined exposure

assessment and risk characterization, no risks to the preliminary assessment endpoints were

identified for the total soil evaluation. While some NOAEL values and one LOAEL value were

exceeded for vanadium for an avian receptor, comparability to background concentration ranges

identified these exceedances as not being significant relative to ambient background exposures and

the product of conservatively derived ESLs. No COPECs were identified based on the updated

SLERA.

Based on the SLERA, no further ecological investigation is recommended for MRP Site 5.


MRP Site 5, MCAS Yuma, Yuma, Arizona DCN: UMAC-2006-0009-0010

CTO No. 0009 A1-43MMEC-2405-4267-0003

March 2019


A1-44 March 2019


MMEC-2405-4267-0003


Attachment 2: Responsiveness Summary

A2-1 March 2019

Attachment 2 Responsiveness Summary

MMEC-2405-4267-0003

Record of Decision for Munitions Response Program Site 5 Marine Corps Air Station Yuma, Arizona Attachment 2: Responsiveness Summary

A2-2


MMEC-2405-4267-0003 March 2019

Douglas A. Ducey

Governor

Via Email and U.S. Mail

September 28, 2018 FPU 19-066

Ms. Angela Patterson

ARIZONA DEPARTMENT OF

ENVIRONMENTAL QUALITY

Naval Facilities Engineering Command Southwest Marine Corps Integrated Product Team 1220 Pacific Highway San Diego, CA 92132-5190

Misael Cabrera

Director

Re: Response to Comments on the Draft Record of Decision for Munitions Response

Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona, July 2018.

Dear Ms. Patterson:

The Arizona Department of Environmental Quality (ADEQ) reviewed the Navy's response to ADEQ comments regarding the above-referenced document. The response-to-comments are acceptable and ADEQ has no additional comments.

If you have any questions or need additional information, please contact me at 602-771-2234 or p ter [email protected].

Sincerely,

Jcf:::� Project Manager Federal Programs Unit

cc: Mark Ripperda, U.S. EPA Region IX (email) Steve Willis, UXO Pro (email)

Main Office

1110 W. Washington Street• Phoenix, AZ 85007

(602) 771-2300

Southern Regional Office

400 W. Congress Street• Suite 433 • Tucson, AZ 85701

(520) 628-6733

www.azdeq.gov

printed on recycled paper

A2-3MMEC-2405-4267-0003 March 2019

s

Responses to Comments on Draft Record of Decision for Munitions Response Program Site 5 Marine Corps Air Station Yuma, Yuma, Arizona

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Comment Section Comment Response

Comments received from: John Peterson, Project Manager, Federal Programs Unit, Arizona Department of Environmental Quality, September 18, 2018

1. General Concurrence is based on the following Remedial Investigation results: a. Soil was excavated to a depth of 16 inches below ground surface

(bgs).b. Screening of the excavated soil for munitions and explosive of

concern (MEC) and Munitions Potentially Presenting an ExplosiveHazard (MPPEH) was performed.

c. Digital Geophysical Mapping (DGM) was performed over 100% of thesite.

d. Intrusive investigation of 100% of the identified anomalies wasconducted after excavation.

e. No MEC was found at the site.f. The site is located in close proximity to the Combat Aircraft Loading

Area, runways, and the current firing-in buttress. As such, the currentand foreseeable future use of the site is restricted to non-residentialmilitary-related activities.

Comment and Concurrence acknowledged.

2. General To further support the NFA decision, please include in the Description of the Selected Remedy text similar to that provided in the Department of the Navy’s response to ADEQ’s Comment 1 dated December 20, 2017 as follows: “Residential use is prohibited at the site and surrounding area due to the presence of operational features immediately adjacent to the site (i.e., Combat Aircraft Loading Apron [CALA] where weapons are loaded on planes, runways, and the current firing-in butt which replaced the MRP Site 5 firing-in butt) as long as MCAS Yuma is an active facility. If MCAS Yuma is ever subject to Base Realignment and Closure (BRAC), performance of an Environmental Condition of Property is required which would note the presence of the CALA, runways, current firing-in butt, and MRP Site 5 and make recommendations for actions needed to ensure the area is suitable for post-BRAC planned uses.”

The Navy disagrees with adding the text to the Description of the Selected Remedy. However, the following text has been added as the last paragraph of Section 7 Summary of Site Risks on Page 17:“While land use restrictions are not included as part of the NA remedy for MRP Site 5, from a practical standpoint, the operational features that are immediately adjacent to the site (i.e., runways, current firing-in butt, and Combat Aircraft Loading Area [CALA] where weapons are loaded on aircraft) do not allow for residential use of the site. As required by the DoD Base Redevelopment and Realignment Manual (DoD 4165.66-M [DON, 2006]), an "Environmental Condition of Property" (ECP) will be prepared if MCAS Yuma is ever subject to Base Realignment and Closure. The ECP will note the presence of the operational features, the status of environmental restoration sites, and will provide the DoD with information to make disposal decisions regarding the property and assist in planning for reuse of the property.”

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Responses to Comments on Draft Record of Decision for Munitions Response Program Site 5


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Comment Page Section Comment Response

Comments received from Mark Ripperda, Project Manager, United States Environmental Protection Agency Region IX on October 23, 2018

General Comments

1. Please explain the basis for characterizing the decision document as a “No Further Action” ROD, rather than as a “No Action” ROD. See EPA’s ROD Guidance, Section 8, which distinguishes between a situation such as seems to be described here “[w]here the baseline risk assessment concludes that current or potential future site conditions pose no unacceptable risks to human health or to the environment” (see Highlight 8-4; “Action Not Necessary For Protection”), and a situation “[w]here a previous removal or remedial action eliminates existing and potential risks to human health and the environment so that no further action is necessary” (see Highlight 8-6; “No Further Action Necessary”).

The document will be revised as a “No Action” ROD. The previous investigations concluded that current and potential future site conditions pose no unacceptable risk to human health or the environment.

Specific Comments

1. 1 Title “Declaration For The Record Of Decision:” Please revise the title to reflect the standard title of this section of a no action ROD, “Declaration.”

The title has been revised from “Declaration for the Record of Decision” to “Declaration.”

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2. 1 “Declaration”, 1st paragraph, last sentence and Page 2, “Statement of Basis and Purpose”, 1st paragraph, 1st sentence

Please revise the text to eliminate the discrepancy between the descriptions in the referenced sentences regarding the role of the NCP; on Page 2, the qualifying text “to the extent practicable” is used, whereas it is not used on Page 1.

The Declaration (first paragraph, last sentence) was revised as follows:

“The NA decision was selected in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, Title 42 United States Code (USC) Section (§) 9601, et seq., and in accordance with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations (CFR) Part 300, et seq.”

The Statement of Basis of Purpose (first paragraph, first sentence) was revised as follows:

“The NA decision was selected in accordance with CERCLA of 1980, as amended by SARA of 1986, Title 42 USC § 9601, et seq., and in accordance with the NCP, 40 CFR Part 300, et seq.”

3. 2 Statement of Basis and

Purpose 2nd paragraph 1st

sentence

Please explain why the text does not reference CERCLA Section 9620 or else provide the appropriate reference.

The text has been revised as follows:

“The United States Department of Defense (DoD) has the authority to undertake CERCLA response actions under Title 42 USC § 9620, Title 10 USC § 2708, and Federal Executive Order 12580.Munitions response actions are conducted underthe NCP, as authorized by CERCLA.”

4. 2 Statement of Basis and

Purpose 3rd paragraph

2nd sentence

Please explain why the text does not cite to the provision requiring an FFA or provide the cite in the text.


“For federal facilities on the NPL list, CERCLA requires that USEPA and the responsible federal department enter into an interagency agreement—a Federal Facility Agreement (FFA)—to govern the cleanup (Title 42 USC § 9620).”

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5. 3 Description of Remedial

Action

For clarity, please revise the section as, or close to, the following-

“The remedy selected for MRP Site 5 is NFA. NFA is selected based on the findings of extensive environmental investigations completed at MRP Site 5. These investigations did not detect any munitions and explosives of concern (MEC), material potentially presenting an explosives hazard (MPPEH), munitions constituents (MC), including metals and explosives, or other hazardous substances, pollutants, or contaminants at concentrations above residential use levels in any soil samples from MRP Site 5. Therefore, there is no unacceptable risk to human health or the environment under the current [industrial] use or a potential future site use requiring unrestricted use and unrestricted exposure.”

The text of the section “Description of Selected Remedy” has been replaced with the following text:

“The remedy selected for MRP Site 5 is NA. Selection of NA is based on the findings of extensive environmental investigations completed at MRP Site 5. These investigations did not detect any munitions and explosives of concern (MEC) or material potentially presenting an explosive hazard (MPPEH). The only potential munitions constituents (MC)-related constituents detected in soil are metals, which were detected at concentrations within the range of background. Explosives have not been detected in any soil samples from MRP Site 5. Furthermore, other hazardous substances, pollutants, or contaminants at concentrations above residential use levels have not been detected in any soil samples from MRP Site 5. Therefore, there is no unacceptable risk to human health or the environment under the current (industrial) use or a potential future use requiring unrestricted use and unrestricted exposure. Based on these results, NA is selected for MRP Site 5.”

6. 3 Statutory Determinatio

ns 2nd sentence

For clarity, please revise the sentence as follows-

“Based on these findings, DON, USEPA and ADEQ, believe that MRP Site 5 may be used as is without restrictions and that NFA is required to protect human health and the environment.”


“Based on these findings, the DON, USEPA, and ADEQ believe that MRP Site 5 may be used as is without restrictions and that NA is required to protect human health and the environment.”

7. 3 Statutory Determinations last clause

of last sentence

For clarity, please revise the clause as follows-

“MRP Site 5 will not be subject to the five-year reviews process.”

The text “… a five-year review will not be required for MRP Site 5” has been replaced with the following recommended text:

“MRP Site 5 will not be subject to the five-year review process.”

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8. 5 Authorizing Signatures 1st and 2nd sentences

For clarity as to the remedy selection process, please revise the two referenced sentences as, or close to, the following-

“This signature sheet documents the Navy’s and EPA’s co-selection of the No Further Action remedy described in this ROD for MRP Site 5, Marine Corps Air Station Yuma, Yuma, Arizona.”


“This signature sheet documents United States Department of the Navy and United States Environmental Protection Agency co-selection of the No Action remedy described in this Record of Decision for Munitions Response Program Site 5, Marine Corps Air Station Yuma, Yuma, Arizona. This signature sheet also documents concurrence with the No Action decision in this Record of Decision by the State of Arizona by and through the Arizona Department of Environmental Quality.”

9. 5 Authorizing Signatures

3rd sentence

Please consider whether the reference should be to the “State of Arizona by and through the Arizona Department of Environmental Quality” or something similar rather than simply the “Arizona Department of Environmental Quality.”

See the response to Specific Comment #8.

10. 8 Carry-over paragraph

from Page 7, 1st full

sentence

Please revise the sentence to eliminate the suggestion that FFA and the relations of the signatory parties is managed under the DERP. Although the Navy’s participation in the FFA may be managed under the DERP, EPA’s participation is not.


“The FFA provides a procedural framework and schedule for developing, implementing, and monitoring appropriate response actions at MCAS Yuma.”

11. 8 3rd full paragraph 3rd

sentence

Here the text suggests that live ammunition may have been discharged at MRP Site 5 (“airplanes with malfunctioning weapons aimed their weapons at the firing-in butt as a safety precaution in case their weapons discharged”), whereas the text for the most part emphasizes that the “zeroing in” process used practice ammunition thereby minimizing the chance that MPPEH may be present. Please explain why the potential for the prior use of live fire ammunition at MRP Site 5 does not affect the Navy’s evaluation of risk at Site 5, notwithstanding the fact that, per the Draft ROD,

The documented use of the firing-in butt was for the zeroing in process. During a meeting, base personnel suggested that airplanes with malfunctioning weapons could have aimed their weapons at the firing-in butt as a safety precaution in the event that their weapons discharged. No records were located regarding that potential use and, as stated in the text, the potential for that use is based on anecdotal information. Use of the firing-in butt in that manner was not the intended use of the site and, if that use did occur, is expected to have been

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the MRP Site 5 environmental investigations did not “detect any munitions and explosives of concern (MEC), material potentially presenting an explosives hazard (MPPEH).”

Also, please explain the relationship of the categories MEC and MPPEH (which the ORC attorney understands to be that MPPEH includes MEC (and MDAS) and MEC in turn includes other categories such as UXO and MC), so that the meaning of statements that no MEC or MPPEH was found at MRP Site 5 is clear.

quite infrequent. Furthermore, extensive investigations have been conducted over time, including the following:

• The berm has been removed.

• The site was excavated to 16 inchesbelow ground surface to remove allmetallic debris observed at the surfaceduring the original remedial investigation.

• The excavated soil was screened andinspected for MEC/MPPEH.

• Digital geophysical mapping (DGM) of theentire site was conducted after removal ofthe top 16 inches of soil.

• 100 percent of the targets of interestidentified by DGM were identified andremoved.

No MEC or MPPEH items were found during the intrusive investigations. The collective findings of the historical review and the MEC field investigations indicate that MEC are not present at the site and no further action relative to MEC is necessary.

MEC and MPPEH are defined as follows by NAVSEA OP-5 Volume 1, Revision 7, Change 13:

MEC distinguish specific categories of military munitions that may pose unique explosives safety hazard/risks and means unexploded ordnance (UXO), discarded military munitions (DMM), or munitions constituents (MCs) (such as TNT, RDX) present in concentrations high enough to pose an explosive hazard.

MPPEH is material owned or controlled by the DoD that, prior to determination of its explosives safety status, potentially contains explosive or munitions (for example, munitions containers and

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packaging material; munitions debris remaining after munitions use, demilitarization, or disposal; and range-related debris) or potentially contains a concentration of explosives high enough that the material presents an explosive hazard (for example, equipment, drainage systems, holding tanks, piping, or ventilation ducts that were associated with munitions production, demilitarization, or disposal operations). Excluded from MPPEH are military munitions within the DoD’s established munitions management system and other hazardous items that may present explosion hazards (such as gasoline cans, compressed gas cylinders) that are not munitions and are not intended for use as munitions.

12. 8 Section 3.0 Community Participation

2nd paragraph

The text here refers to the “Administrative Record” (including in footnote 2), whereas earlier in the document the text correctly refers to “Administrative Record file,” the term of art used to refer an administrative record prior to issuance of the ROD related to it. Please explain why the term “Administrative Record” is the proper term here, rather than “Administrative Record file.” (See EPA’s Administrative Record Guidance.)

“Administrative Record” has been revised to “Administrative Record File.”

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13. 8 Section 4.0 Scope and

Role of Response

Action

Please explain why the text in this section doesn’t refer to “hazardous substances, pollutants, or contaminants at concentrations,” as does the text on Page 3, in the section “Description of Remedial Action.”


“The investigations at MRP Site 5 did not detect any MEC, MPPEH, or MCs, including metals and explosives, or other hazardous substances, pollutants, or contaminants at concentrations above residential use levels in any soil samples. The resultant risk assessment concluded no unacceptable risk to human health or the environment under unrestricted use and unrestricted exposure. As a result, this ROD selects NA for MCs and MEC at MRP Site 5.”

14. 15 2nd paragraph

last sentence

“Ditto” the preceding comment in terms of the last sentence.


“Environmental investigations completed at MRP Site 5 did not detect MEC, MPPEH, or MCs, including metals and explosives, or other hazardous substances, pollutants, or contaminants at concentrations above residential use levels in any soil samples collected from MRP Site 5. Therefore, no action is recommended for MCs and MEC at MRP Site 5.”

15. 13 MC and MEC Sources

The parenthetical phrase (approximately 3 feet) applies to the combination of the 16 inches of excavation plus the 18 inches into the subsurface assessed by the geophysical survey. However, that isn’t completely clear the way the paragraph is presented. Please delete the parenthetical phrase and add a sentence stating something like:

“The total depth of the assessment between the excavation and the geophysical investigation is thus approximately 3 feet below the original ground surface”.


“The total depth of the assessment between the excavation and the geophysical investigation is thus approximately 3 feet below the original ground surface.”

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16. 14 7.0 Summary of Site Risks

The first two paragraphs of this section discuss cancer and non-cancer risks, but there has not been any previous introduction of COCs. The entire ROD to this point has focused only on MEC and no detections for MPPEH. The following paragraph on eco-risk states that the detected metals are within the range of background. We suggest starting this section with an explanation that no hazardous substances were found during the investigations and that the metals at the site are within the range of background.

The following text has been added as the first sentence of Section 7.0, Summary of Site Risks:

“No hazardous substances have been found during the investigations and concentrations of metals detected in soil at MRP Site 5 are within the range of background concentrations.”

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Comments received from Eric Esler, Legal Counsel, United States Environmental Protection Agency Region IX on January 29, 2019

General Comments

1. First, with regard to the RTC to comment 5, please ask the Navy to confirm that the text “potential munitions constituents (MC)-related constituents” is correct.

The sentence has been revised to eliminate the redundant use of the word “constituent” as follows:

“The only potential munitions constituents (MCs) -related constituents detected in soil are metals, which were detected at concentrations within the range of background.”

2. Second, regarding RTC 11, comment 11 was a request for clarifying language to be added to the ROD, but it doesn’t appear that the ROD language was modified, just that an explanation was added to the RTC. Please confirm whether or not the Navy added clarifying language to the ROD.

The third full paragraph on page 8 has been revised as follows:

“MRP Site 5 was formerly firing-in butt Range 1294. The former firing-in butt range was used to zero-in fixed aircraft guns. Practice munitions, which do not contain explosives, are used to zero-in aircraft guns. Base personnel have suggested that airplanes with malfunctioning weapons could have aimed their weapons at the firing-in butt as a safety precaution in the event that their weapons discharged. No records were located regarding instances of that type of live firing at the site and use of the firing-in butt in that manner was not the intended use of the site. If that use did occur, as suggested by anecdotal information, it is expected to have been quite infrequent. Ammunition used included 0.50 caliber and 20-millimeter (mm) projectiles, which are typical munitions for the types of military aircraft operating at MCAS Yuma during the time that the firing-in butt was in use. However, extensive investigations have been conducted over time, including removal of the berm, site excavation to 16 inches below ground surface (bgs) to remove all metallic debris observed at the surface during the original remedial investigation, digital geophysical mapping (DGM) of the entire site after removal of the top 16 inches of

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soil, and 100 percent identification and removal of the targets of interest identified by DGM. No MEC or MPPEH items were found during the intrusive investigations.”

Clarification text for MEC and MPPEH has been added at the end of Section 4 on page 9 as follows:

“In this document, MEC describes specific categories of military munitions that may pose unique explosives safety hazard/risks, including unexploded ordnance (UXO), discarded military munitions (DMM), or MCs (such as trinitrotoluene [TNT], RDX) present in concentrations high enough to pose an explosive hazard. Similarly, MPPEH describes material owned or controlled by the DoD that, prior to determination of its explosives safety status, potentially contains explosive or munitions (for example, munitions containers and packaging material; munitions debris remaining after munitions use, demilitarization, or disposal; and range-related debris) or potentially contains explosives at concentrations high enough that the material presents an explosive hazard (for example, equipment, drainage systems, holding tanks, piping, or ventilation ducts that were associated with munitions production, demilitarization, or disposal operations). Excluded from MPPEH are military munitions within the DoD’s established munitions management system and other hazardous items that may present explosion hazards (such as gasoline cans, compressed gas cylinders) that are not munitions and are not intended for use as munitions.”

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