McClellan Air Force Base (Groundwater Contamination)

Description and History

The 3,452-acre McClellan Air Force Base (AFB) site was established in 1936 and operated as an Air Force Logistics Command Base with a primary mission of management, maintenance, and repair of aircraft, electronics, and communication equipment. The operation and maintenance of aircraft have involved the use, storage, and disposal of hazardous materials including industrial solvents, caustic cleansers, paints, metal plating wastes, low-level radioactive wastes, and a variety of fuel oils and lubricants. The Air Force has identified 326 waste areas of known and suspected contamination. Under BRAC IV, McClellan AFB closed as an active military base in July 2001.

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Contaminants and Risks

The primary contaminants in groundwater are volatile organic compounds (VOCs). Contaminants detected in soil include PCBs, heavy metals, and several non-VOCs. Radionuclides have also been identified in surface soil and in former disposal pits. People may face a health risk if they accidentally ingest or come into direct contact with contaminants. People also may be at risk if they eat foods containing accumulated contaminants or if they inhale contaminated dust or soil vapors. Risks to wildlife and their habitat may occur on and adjacent to the former Base in some areas of the creeks, vernal pools, and other parts of the flood plain.

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Who is Involved

This site is being addressed primarily through federal actions directed by the Air Force Real Property Agency (formerly known
as the Air Force Force Base Conversion Agency) and overseen by US EPA Region 9, California State Department of Toxic Substances
Control (DTSC), and California Regional Water Quality Control Board (RWQCB). The Air Force, EPA, and State work together under the terms
of a Federal Facilities Agreement (FFA) signed in 1990.

As part of the “Privatized” Cleanup Approach (see below), the 1990 FFA was amended in June 2007 to allow McClellan Business Park LLC (MBP) to assume responsibility for cleanup at a 62-acre portion of McClellan AFB known as Parcel C6. MBP will conduct the cleanup actions at Parcel C6 under the oversight of EPA, DTSC and RWQCB, as with other areas of McClellan AFB. The 2007 FFA Amendment further provides that EPA alone will select the response actions for Parcel C6 and that if MBP should fail to perform their cleanup responsibilities, the Air Force will resume their responsibilities under the original 1990 FFA.

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Investigation and Cleanup Activities

Overall Approach: Two different approaches are currently being undertaken to address the contamination at McClellan AFB: the traditional CERCLA approach and the privatized cleanup approach.
The traditional CERCLA approach at McClellan AFB involves the Air Force investigating the sites, determining the nature and extent of contamination in soil and groundwater, evaluating the risk, preparing a Record of Decision (ROD) to document the selected remedial action and then designing and conducting the remedial actions. Most sites are following this approach.

The privatized cleanup approach was undertaken for the first time in August 2007 at Parcel C-6, a 62-acre site contaminated with PCBs. The privatized cleanup approach involves deeding the land to a private party before cleanup of contamination is complete. The private party will use money provided by the Air Force to complete site investigation and cleanup under the direction of EPA and state regulators. Privatization combines redevelopment needs with environmental cleanup efforts and will help accelerate the reuse of the sites.

The initial strategy at McClellan AFB was to investigate and cleanup soil sites by geographic areas. The Air Force divided McClellan AFB into a number of operable units (OUs), OUs A through H and a groundwater OU to facilitate geographically organized cleanup but this process has been abandoned. Currently, site cleanup is organized according to similar cleanup approaches or type of contamination.

A number of remedial actions have been taken at the facility. Early actions addressed some soil and landfill sites with removals and caps, while other early actions addressed groundwater plumes with a gradually expanding groundwater extraction and treatment system enhanced by numerous soil vapor extraction (SVE) systems.

Immediate Actions: In 1984-1989, the Air Force removed contaminated soil and constructed an 11-acre cap (OU D1 cap) in the northwestern portion of the Base. In the central portion of the Base, a groundwater treatment plant was constructed to treat extracted groundwater and an alternative water supply was provided to local residences.

Interim Actions: In the mid 1990s, two interim actions were initiated to remove solvents from the subsurface and to minimize further migration of the solvents away from their source areas. These included a 1993 removal action to install a number of SVE systems and a 1995 Groundwater Interim ROD (IROD) to install extraction wells on and off-base to contain VOC-contaminated groundwater plumes. In 1993, the Air Force also conducted an interim action to address PCB contamination in soil in a former transformer storage area through the construction of a 5-acre cap (OU B1 cap).

CS 010 Removal Actions: In August 2000, a Non-Time Critical Removal Action was begun at CS010, a waste disposal pit. This removal action was initiated after the Air Force determined that radioactive contamination in the soil at this site exceeded "acceptable" risk criteria. In addition, buried 55-gallon drums at the site were to be removed because radioactive contents within the drums posed a risk if the drums leaked or were ruptured. The removal action included excavation of 109, 55-gallon drums, one (1) 20-gallon drum, excavation of 480 cubic yards of soil, and laboratory wastes. Contents of one drum were labeled as containing plutonium. As a result, excavation activities were stopped on September 6, 2000.

The Air Force subsequently initiated a Time-Critical Removal Action which was intended to remove all contamination at the site that posed excess risks to human health and the environment. A total of 533 drums and 27,409 cubic yards of soil were removed. However, due to mounting soil disposal costs, the remaining 23,409 cubic yards of soil still remain stored under a weatherized tent at CS 010.
In June 2003, the Air Force incorporated a special treatment system to remove hexavalent chromium from treated groundwater before it is discharged to a nearby creek. The long-term remedy to address hexavalent chromium will be determined in the Non-VOC Groundwater ROD Amendment.

As stated above, the final cleanup decisions for sites at McClellan AFB are being organized according to similar cleanup approaches or type of contamination under a number of RODs.

LIST OF COMPLETED AND PLANNED RODS:

1) No Further Action
2) Initial Parcel #1
3) Basewide VOC Groundwater
4) Initial Parcel #2
5) Focused Strategic Sites
6) Initial Parcel #3
7) Non-VOC Groundwater (Amendment to Basewide VOC Groundwater ROD)
8) Follow-on Strategic Sites
9) Small Volume Sites
10) Building 252
11) Ecological




The following four RODs have been finalized to date. The remaining RODs are planned for 2009 through 2011 and will address surface soils, landfills, structures, radiation, ecological areas of concern, and non-VOCs in groundwater.

[1] No Further Action ROD (signed February 2003; AR# 4502 ): This ROD addressed six sites (PRLB-004, SA 064, SA 039, SA 050, PRL 035, and SA 017) that contained no soil contamination. By stating this conclusion in a ROD, these sites became available for property transfer and removal from the Air Force site tracking system.

[2] Initial Parcel #1 ROD (signed June 2004; AR# 5488): This ROD addresses non-VOC contamination in soil at seven sites (SA 003, PRL S-014, SA 035, PRL S-040, PRL S-033, SA 041, SA 091). As a result of this ROD, approximately 2,600 cubic yards of contaminated soil were removed from SA 003 and approximately 300 cubic yards of contaminated soil were removed from PRL S-014. No further action was required for non-VOCs in soils at the 5 remaining sites. PRL S-040 did require additional action on state requirements to address fuel-related contamination which is not covered by CERCLA requirements.

[3] Basewide VOC Groundwater ROD and ROD Amendment (signed August 2007 and amended in August 2009; AR# 6475): This ROD (as amended) addresses VOC and non-VOC contamination in all portions of groundwater plumes regardless of whether they are located within or outside of the Base boundaries. The selected remedy requires extraction and treatment of groundwater, along with soil vapor extraction (SVE) and institutional controls. Institutional controls are non-engineering, non-technical mechanisms used to reduce or prevent human exposure to contaminants. Preventing extraction of the groundwater for any purpose other than remediation or monitoring is one example of an institutional control. Air stripping and SVE address VOC contamination. Ion exchange is applied to hexavalent chromium.

[4] Initial Parcel #2 ROD (signed September 2008; AR #6504): This ROD addresses contamination associated with 23 sites within the Base (AOC H-1, AOC H-2, AOC H-3, AOC H-8, AOC H-13, PRL S-033, PRL S-040, PRL S047, SA 003, SA 035, SA 041, SA 091, Tank 783, Tank 788, AOC G-2, AOC H-12, CS S-049, AOC H-14, SA 105, and PRL S-014). These sites are considered most desirable by the county and developer for redevelopment. Actions for these sites range from soil excavation to institutional controls.

Strategy for Remaining Soil-ROD Related Decisions:

[1] Focused Strategic Sites ROD: This ROD will address contamination associated with the Air Force’s former waste disposal pits and large volume sites that are the most technically challenging. The Air Force prepared an FS and selected a preferred alternative in the PP. The Air Force proposes to cap waste disposal pits CS 011, CS 012, CS 013, CS 014, CS 022, CS 024, AOC 313 and PRL 008 and the Vadose Zone Site, and use the open excavation at one of the excavated disposal pits (CS 010) to contain contaminated soils from CS 010 and the Small Arms Firing Range site. The California Department of Public Health expressed that the pits are not adequately characterized. EPA requested that the team take a step back to review/reassess the alternatives that were proposed by Air Force in the FS. This will delay the Record of Decision.

[2] Initial Parcel ROD #3: This ROD will address contamination associated with 50 sites within the southwestern and western portion of the Base. These sites are the second set of sites identified by the County and developer for redevelopment and are currently in the Remedial Investigation/Feasibility Study phase of the CERCLA process.

[3] AOC G-1 ROD: This ROD will address contamination at one site, a former debris pit. The site is located on a 25-acre parcel at the intersection of Freedom Park Drive and Perrin Ave. The parcel includes a museum and a recreational complex with softball fields and a playground.

[4] Small Volume Sites ROD: This ROD addresses larger areas of contamination in the southeastern portion of the Base. The sites to be included under this ROD are expected to involve small volumes of contamination. Most of the actions are likely to be similar to the action undertaken for sites in the IP#2 ROD.

[5] Follow-on Strategic Sites ROD: This ROD addresses areas of the Base that contain landfills and disposal pits that were not addressed in the Focused Strategic Sites ROD. The plan is to apply the results of the Focused Strategic Sites RODs to facilitate actions at these sites.

[6] Building 252 ROD: This ROD covers Building 252 and six former solvents USTs adjacent to Building 252. Building 252 is a complex radiological site with mixed waste. Because of these unique issues, Building 252 has been separated into its own ROD.

[7] Ecological Sites ROD: This ROD will address contaminated sites impacting creeks, flood plains, vernal pools and other ecological areas. The feasibility study to evaluate alternatives for the site is planned for early 2009.

Ongoing Cleanup

Groundwater extraction and treatment continues at the former Base. Groundwater is extracted and treated at the groundwater treatment plant (GWTP) in the central portion of the facility. With the installation of the Phase 3 on-base groundwater extraction wells in September 2005, fewer than 2000 gallons per minute (gpm) of extracted groundwater are treated (via air stripping and ion exchange) before being discharged to Magpie Creek. Groundwater cleanup is expected to continue for many decades until clean-up is attained. The Fate, Flow and Transport Model that was developed in 2004 predicted that TCE could be below its maximum contaminant level (MCL, 5 ug/L) in 55 years.

Currently, 15 separate SVE systems are addressing solvents beneath 91 sites. A large majority of the 1.3 million pounds of solvents removed to date from the groundwater and soil have been extracted by these SVE systems. SVE is used to remove and treat VOC sources in the vadose zone with the potential to migrate to groundwater. Additional systems may be added to complete the network that protects groundwater from VOCs in the vadose zone. SVE is a component of the VOC groundwater remedy.

Site Completions: Actions (administrative and remedial) have been completed for the sites covered under the No Action ROD and the IP#1 ROD described above.

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Cleanup Results to Date

Cleanup Progress: The removal and disposal of some contaminated soil and underground tanks, the capping of the northwestern area of the Base, and the installation and operation of a groundwater extraction system and 15 soil vapor extraction systems have reduced the potential for exposure to contaminants at the former McClellan AFB site. From the mid-1980s through 2004, these extraction systems have removed over 1.3 million pounds of VOCs. Providing an alternate water supply has eliminated the potential for exposure to contaminated drinking water and continues to protect area residents until final site cleanup is complete. At disposal pit CS 010, over 60% of the contaminated soils and all of the drums have been removed as part of the removal action.

In addition, the Air Force completed the removal a total of 2,900 cubic yards of soil from sites PRL S-014 and SA003 under the Initial Parcel #1 ROD.
Finally, 62-acres within Parcel C6 were transferred as part of the privatized cleanup approach, discussed above. This privatized cleanup was the first in the country at a Superfund site and is expected to accelerate cleanup.

Restoration and Reuse Progress: Most of the former Base has been approved for leasing. The County of Sacramento leases these areas from the Air Force until the property can be transferred by deed to new owners. MBP is Sacramento County’s development partner. The County of Sacramento MBP and the Air Force have leased about 60% of the leasable building space to a variety of businesses and organizations that are now part of a corporate community called McClellan Business Park. All leases and subleases have appropriate use restrictions to maintain protection of human health and the environment during the ongoing investigation and cleanup activities.

In addition to privatized cleanup, the Air Force is also looking at packaging several more large geographic areas of the former Base into large groups of properties to facilitate property transfer through, Findings of Suitability for Early Transfer (FOSETs). The Air Force would subsequently offer to deed parcels to entities willing to own them with conservative land use controls and institutional controls in place until cleanups can be conducted in the future by either the Air Force or private parties.

Transfer Progress: Approximately 389 acres or 11% of the 3,452 total acres of the former Base have been transferred. Areas that have transferred are listed below.

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Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

At McClellan AFB, Air Force activities resulted in contamination at the site; therefore, the Air Force is considered the responsible party.

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Documents and Reports

Administrative Records
		Privatization Parcel C-6
		Remedial Privatization Parcel C-6, Update #1
Fact Sheets
	09/17/08	EPA Prepares for Cleanup of Parcel C-6
	10/20/08	Proposed Plan for Soil Cleanup
Maps
		McClellan AFB Aerial Photo 1997, Control Sites, Cleanup Plan

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Community Involvement

Public Meetings: Parcel C-6 Proposed Plan Public Meeting: EPA hosted the Proposed Plan public meeting for Parcel C-6 on Wednesday, November 5, 2008 at the Lions Gate Hotel in McClellan, CA. EPA will consider public comments when selecting remedies for the sites.

McClellan AFB typically schedules various types of public meetings four to eight times a year. They are held at various locations surrounding the former base.

Restoration Advisory Board: Once every quarter, McClellan holds a public meeting that features the Restoration Advisory Board (RAB). The most recent RAB meeting was held on September 15, 2009. The RAB is composed of community members and offers unsolicited and solicited advice to the Air Force and other government representatives concerning cleanup and reuse of former McClellan AFB.

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Public Information Repositories

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Additional Links

http://www.safie.hq.af.mil/afrpa/index.asp

The Air Force maintains the administrative record (AR) for the site. Documents are available via the Air Force Real Property Agency (AFRPA) Web Site.
(https://afrpaar.lackland.af.mil/ar/docsearch.aspx)

Newsletters and fact sheets are available on the AFRPA McClellan website.
(http://www.safie.hq.af.mil/afrpa/legacybrac/formermcclellan.asp

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Contacts

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