Just like Camp Lejeune and many other bases that have been listed on the EPA Superfund site list, this base also has groundwater contamination and soil vapor plume issues from the presence of TCE, PCE and DCE.
Marine Corps Air Station Yuma (MCAS Yuma) occupies approximately 3,000 acres within the City and County of Yuma, Arizona. The City of Yuma, the nearest municipality, is located approximately one mile northwest of the Station. Both the City and the Station obtain their drinking water from the Colorado River through an irrigation canal. The City does not use groundwater for drinking water purposes. The nearest domestic groundwater well is approximately 0.8 mile downgradient from the Station.
MCAS Yuma’s mission is to provide services and materials support operations to the Marine Aircraft Wing and its subordinate units. In 1990, MCAS Yuma was placed on the Superfund National Priorities List after chlorinated solvents were detected in a groundwater monitoring well on the Station.
Starting in the mid-1940s, waste fuels and solvents from the refueling and servicing of airplanes were reportedly disposed of directly onto the ground or into unlined pits at the Station site. In addition, combustible materials such as fuel oil and organic solvents were deposited on the ground or burned during fire training exercises. Approximately 5,700 people live on-site. In the past, during maintenance work on the Colorado River irrigation canal which took place for two weeks each year, drinking water was supplemented using an on-station well. However, this practice was stopped in August 1995. The City of Yuma has a summer population of 60,000 and a winter population of 100,000.
- Soil contamination – Asbestos in the form of non-friable asbestos containing material (ACM). The ACM is scattered on top of and buried in the surface soil. Cleanup complete according to EPA.
- Groundwater contamination – Chlorinated solvents (TCE, DCE and PCE). The groundwater is being remediated by two treatment systems which have significantly lowered contaminant levels nearly to the MCLs. The main base system is an air-sparging/pump and treat system which attacks the main plume and the Leading Edge Plume Area system (LEPA) remediates contaminants which were beyond the main base system at the time of construction. The base has produced a third 5-Year review which shows the remediation to be protective.
The main groundwater plume is approximately 1 mile long and 500 feet wide, and has reached the downgradient edge of the base. The maximum concentration of total solvents is approximately 500 parts per billion (ppb). All of the groundwater contamination has been detected downgradient of the old on-station drinking water well. However, the on-station drinking water well is no longer used and none of the groundwater is used elsewhere on the base. If left untreated, the plume could potentially impact private groundwater wells downgradient from the Station.
Risks and pathways addressed by the cleanup include health risks from people ingesting or touching contaminants in soil and groundwater.
1928 – 1959: YMCAS began as a county airfield in 1928, and was leased to the U.S. Army for pilot training and bomber crew training from 1941 to 1946. The U.S. Air Force reactivated the station as a Weapons Proficiency Center for fighter interceptor units in 1951, and it became an Air Force installation in 1954. YMCAS and associated range facilities were transferred to the U.S. Navy in 1959 to provide services and materials to support the operations of the Marine Aircraft Wing and its subordinate units. Today, YMCAS is the busiest air station in the Marine Corps and the third busiest in the Naval Service.
During its 70 years of operation, YMCAS generated industrial wastes such as used oil, solvents, paint residues, battery acid, pesticides, herbicides, polychlorinated biphenyls, asbestos in the form of non-friable asbestos containing material (ACM) and petroleum hydrocarbons from a jet fuel leak. The ACM was scattered on top of and buried in the surface soil, and remediated in 1999.
1985 – 1991: An initial environmental assessment of YMCAS was completed in 1985, and the site was placed on the National Priorities List (NPL) on February 21, 1990. The federal facilities agreement and assessment program, established in 1991, identified three operable units (OUs):
OU1 contained contaminated groundwater and soil deeper than 10 feet below ground surface (bgs).
OU2 contained contaminated soil from ground surface to 10 feet bgs.
OU3 did not identify any specific Comprehensive Environmental Response Compensation and Liability Act (CERCLA) sites, and was intended to be used for future sites if required.
1993: The remedial investigation/ feasibility study (RI/FS) was completed. The RI identified 18 CERCLA areas of concern; 12 sites required no further action and six sites (1, 4, 7, 8A, 9 and 10) were recommended for remedial action.
1996: A source treatment/reduction alternatives plan was implemented.
1997: The final Record of Decision (ROD) for OU2 was signed and assessed the impact on human health and the environment of hazardous substances released to the soil. Institutional controls were selected as remedy for sites 1, 8A, and 10.
1999: The Air Sparge/Soil Vapor Extraction (AS/SVE) system became operational for Area 1 Hot Spot. Removal of ACM and ACM-contained surface soil was completed in 1999 for sites 4, 7, and 9.
2000: The final ROD for OU1 was signed in April and included areas of contaminated groundwater underlying the station and the associated soil at depths greater than ten feet bgs. Also, the Vertical Circulation Treatment system was operational for Area 1 LEPA.
2002: The first FYR report was completed.
2007: ADEQ, EPA and the Navy continued to monitor the site semi-annually to ensure that concentration levels remained stable. .
2008 – 2009: ADEQ, EPA and the Navy continued to monitor the site semi-annually to ensure that concentrations levels remained stable and no migration off-site occurred.
2010: In order to protect human health and the environment and to ensure continued progress in environmental remediation at YMCAS, ADEQ, EPA and the Navy continue to work together to implement recommendations of the third FYR, including vapor intrusion pathway, updating the LUCIP as needed, reconciling any discrepancies in LUCIP figures, reevaluating dioxin risk based upon EPA dioxin reassessment, and resolving any other environmental issues as YMCAS continues to grow and change in their military service.
2011 – 2012: In 2011 and 2012, ADEQ worked with EPA and YMCAS to: Characterize Volatile Organic Compound (VOC) concentrations in soil gas at OU 1; Characterize dioxin/furan concentrations in soil at OU 2 CAOCs 8A and 8B; Evaluate remedies at OU 1 Areas 1 and 3; and OU 2 Areas of Concern 1, 8A, 8B, and 10. ADEQ and EPA continued work with YMCAS on the remedial investigation/feasibility study (RI/FS) process at MRP sites 1, 2, 4, 5, and 6; the operations of the VCT system at the Leading Edge of the Plume (LEPA) at OU 1, Area 1; and conduct groundwater monitoring, data gap sampling and Land Use Control Implementation Plan activities for OU 1.
2013: The VCT system at the LEPA, OU1, Area 1 and the AS/SVE, Area 1 Hot Spot are both back online. RI/FS work continues on the MRP sites 1, 2, 4, 5 and 6. The Land Use Control Implementation Plan for OU1 is expected to be finalized by end of year. Subsurface remedial investigations in several MRP sites were implemented to assess whether additional investigation of these sites is required and determine if there is a risk to human health and the environment. LUCs were implemented in OU1 and OU2 as designated by the ROD.
The most complete collection of documents is the official EPA site file, maintained at the following location:
Superfund Records Center
Mail Stop SFD-7C
95 Hawthorne Street, Room 403
San Francisco, CA 94105
EPA Site Manager
EPA Community Involvement Coordinator
Karin Harker, Arizona DEQ
*Note – We’ve posted, verbatim, the information from the EPA on MCAS Yuma on this page rather than simply sharing a link. This is to maintain an ongoing record of the information to the date of publication, in the event it is edited or removed from their site in the future. Any and all excerpts above are courtesy of sites such as EPA, DOD and VA. You can view the link to the EPA page here: EPA Superfund Site – MCAS Yuma or EPA Superfund Site Profile – MCAS Yuma
Other Relevant Research Links
- Arizona State Info Site: http://legacy.azdeq.gov/environ/waste/sps/Yuma_Marine_Corps_Air_Station.html
- Scorecard Page on MCAS Yuma: http://scorecard.goodguide.com/env-releases/land/site.tcl?epa_id=AZ0971590062
- Arizona Water Site: http://www.azwater.gov/azdwr/StatewidePlanning/WaterAtlas/LowerColoradoRiver/PlanningAreaOverview/WaterSupply-Groundwater.htm
- Public Health Assessment: https://www.atsdr.cdc.gov/hac/pha/pha.asp?docid=929&pg=0