Congressional District # 01
WURTSMITH AIR FORCE BASEEPA ID# MI5570024278
Last Updated: February, 2012
Site DescriptionWurtsmith Air Force Base (Wurtsmith) is a 5,223 acre site, located on the northeastern part of Michigan's lower peninsula about two miles west of Lake Huron. To the north and northeast of the site is Van Etten Lake, to the southwest is Allen Lake, and to the southeast and east is the village of Oscoda. Of the 5,223 acres, 1,943 acres are owned by the U.S. Air Force. The rest of the facility consists of 2,466 acres that are leased primarily from the state and 814 acres that are registered as easement tracts.
Wurtsmith has operated since 1923 under several different names, beginning as a subsidiary of Selfridge Field, called Camp Skeel. Until World War II, Camp Skeel was used for gunnery practice, winter maneuvers, and aircraft landings. According to The Emergency War Order, the primary mission of the base was to maintain full readiness to conduct strategic bombing operations worldwide. Support activities at the base included aircraft and vehicle maintenance, bombardment crew and unit training, and air refueling support. The base was renamed Oscoda Army Air Field when the Continental Air Command began using it as a transient aircraft stopover. In 1953, the base was renamed back to Wurtsmith Air Force Base, and the present runway and taxiway configurations were established in 1959. In 1960, Wurtsmith AFB came under the command of the U.S. Air Force Strategic Air Command, and several air refueling squadrons were established. In 1977, the base mission was expanded to include the B-52 heavy, long-range bomber. Wurtsmith AFB was officially closed on June 30, 1993 under the Base Realignment and Closure Act (BRAC).
In November 1977, while collecting groundwater samples, the Air Force detected trichloroethylene (TCE) in three of the seven drinking water wells on the base. Additional samples collected in 1979 and 1980 also detected TCE. In 1985 during the early stages of base closure, the Installation Restoration Program (IRP) Phase I records search for Wurtsmith identified 29 sources of concern including the Weapons Storage Area (WSA), two former 6,000-gallon tank trailers buried in the Northern Landfill Area (LF-30/31), the Building 43 Area, and the Building 5098 Jet Engine Test Area. During the 1950s and early 1960s, the Air Force used the Weapons Storage Area as a jet fighter maintenance area, possibly using TCE for degreasing and deicing the jets. The U.S. Geological Survey (USGS) subsequently identified a TCE-contaminated groundwater plume that appeared to be emanating from this area. In 1971, two 6,000-gallon tank trailers were buried in the center of the Northern Landfill Area to create a central depository for waste solvents. The tanks were removed in 1979. The Northern Landfill Area served as a disposal pit from 1960 to 1979 into which the Air Force disposed of domestic and industrial wastes, including solvents, metals, and paints. In 1987, the USGS sampled monitoring wells downgradient of the Northern Landfill area and identified TCE, 1,1-dichloroethane, 1,1,1- trichloroethane, and vinyl chloride. The Air Force used a 500-gallon underground storage tank in the Building 43 Area from 1962 to 1977 to store waste TCE, which it used as a degreaser for the maintenance of fire control equipment in the Building 5098 Area. After removing the tank, a leak was discovered near the fill pipe on the top of the tank. In addition, the Air Force apparently dumped solvents, including TCE, near buildings in the Building 5098 Area for weed control. Pumping drinking water wells in this area caused the contaminants to be drawn toward these wells, resulting in the contamination of additional drinking water wells with TCE.
Site ResponsibilityThe site is being addressed through federal actions. The Air Force has the lead responsibility at the site. Primary oversight of the cleanup actions at Wurtsmith AFB is provided by the Michigan Department of Environmental Quality (MDEQ), with US EPA providing support.
Threats and Contaminants
Groundwater quality at Wurtsmith AFB has been affected primarily by previous releases of fuels or solvents, such tetrachloroethylene (PCE) and trichloroethylene (TCE), to subsurface soils, or releases associated with waste disposal in several landfills as part of normal historical base operations. Dissolved TCE was first detected in base water supply wells in 1979.
Wurtsmith AFB was propossed for inclusion on EPA's National Priorities List (NPL) of Superfund sites, but the listing was never finalized. Therefore, Wurtsmith AFB is not on the NPL.
The site contamination is being addressed by several long-term remedial actions:
A groundwater pump and treat system was installed in 1981 to clean up a TCE spill near Building 43 and to halt its movement offsite. This system is referred to as the Arrow Street Pump and Treat System (ASPTS). The Arrow Street P&T System became operational in December 1981, and was installed to treat groundwater contamination within the Arrow Street plume, which includes IRP Sites SS-17, SS-21, and SS-47. Trichloroethene (TCE) is the primary groundwater contaminant of concern (COC). Secondary contaminants include tetrachloroethene (PCE), and benzene, toluene, ethylbenzene, and xylenes (BTEX). Site SS-17 is located at a former above ground storage tank (AST) site on the south side of Building 25. In 1987, approximately 100 gallons of heating oil were spilled from the AST and were absorbed directly into the ground. Site SS-21 is located at a former underground storage tank (UST), near Building 43. The UST was installed in 1962 to serve as a temporary storage tank for waste oils and spent TCE generated from the wash room in Building 43. The tank was operational until 1977, when the tank and 245 cubic yards of impacted soil were removed and properly disposed of following the detection of TCE in the groundwater at the Base’s potable water supply wells AF1 and AF3. It was suspected that the leaks were occurring at the fill pipe of the UST when the tank was filled or emptied. Therefore, it is suspected that the source was not continuous, but sporadic. This may have resulted in several smaller plumes, which eventually merged into a single plume.
The Arrow Street P&T System consists of two active purge wells, AS-PW4 and AS-PW5. Purge well AS-PW1 has been off-line since June 02, 2004, AS-PW3 discontinued pumping in December 2009, and AS-PW2 discontinued pumping in July 2010. AS-PW5 was installed in October 2009 and brought online on 23 November 2009. All of the purge wells are 12 inches in diameter except for AS-PW4 which is 10 inches in diameter. The total depth of the five purge wells ranges from 64 to 70 feet below ground surface (bgs). The length of the screened interval for each well is approximately 30 feet. The purge wells pump groundwater into an underground force main which conveys the extracted groundwater to an air stripping treatment system. The air stripping system consists of two packed-column air stripping towers (Tower Nos. 1 and 2). Currently, only one tower is utilized because both extraction rates and influent concentrations have significantly decreased, while the other tower serves as a backup.
A second pump and treat system, the Mission Street Pump and Treat System, was installed in 1987 to clean up TCE and fuel spills originating near the operational apron and Building 5098. The system first became operational in June 1987 and was designed to treat groundwater contamination primarily within the Site OT-24 area. In November 1977, TCE was detected in Wurtsmith AFB water supply wells (AF18A and AF19) north of Perimeter Road and west of Mission Drive. Through subsequent investigations, two distinct groundwater plumes (Plume A and Plume B) were identified. Plume A was characterized by two areas of high TCE concentrations: one centered near the middle of the Mission Street P&T System well field, and a second located west of the extraction wells near Three-Pipes Drainage Ditch. Plume B was generally defined as an area surrounding Duell Lake to the south. Remedial actions at Site OT-24 include operation of the Mission Street P&T System, and monitored natural attenuation (MNA) for the southern portion of the plume (Plume B) outside the system capture zone.
The Mission Street P&T System consists of five 8-inch diameter active purge wells: MS-PW1A through MS-PW3A, MS-PW6A and MS-PW7A. Subsequent basewide optimization activities modified the system pumping configuration from the original four purge well system to the current five well purge system. The total depths of the wells range from 57 to 74 feet below grade. Prior to 2001, the system consisted of four purge wells (MS-PW-1 through MS-PW-4) which are no longer utilized. MS-PW5A was removed from operation in September 2004, and MS-PW4A was removed from operation in May 2007. The wells pump groundwater from Site OT-24 to a treatment system consisting of two packed-column air stripping towers (Tower Nos. 1 and 2). After exiting the towers, the treated groundwater is discharged to the Au Sable River via the Base storm sewer system to Outfall 002A. Additional details of the system are available in the Operations and Maintenance Manual (Addendum), Mission Street, Groundwater Pump and Treat System (TolTest, 2009b).
A third pump and treat system, the Benzene Plant Pump and Treat System, began operation in 1992 to clean up spills at the POL Bulk Storage Area, which includes IRP Sites SS-06, SS-13, ST-40 and ST-46. The apparent principal source of contamination at Site SS-06 was the AST 7000, a former 1.2 million gallon JP-4 Aboveground Storage Tank which experienced unaccounted losses resulting in groundwater contamination in the subsurface. AST 7000 was removed in 1992. A smaller underground storage tank (UST) at Site ST-40 is also a suspected source of contamination in the area of Site SS-06.
The Benzene Plant P&T System consists of two active purge wells (BZ-PW5 and BZ-PW6) which extract contaminated groundwater and deliver it to two packed-column air stripping towers. The total depth of the two purge wells ranges from 50 to 64 feet. The length of the screened intervals is approximately 30 feet. The wells are 8 inches in diameter. Purge wells BZ-PW1 through 4 operated from 1992 to 2005, and were removed from service due to historically low or non-detectable concentrations of COCs. The air stripping towers, named Tower Nos. 1 and 2, operate one at a time. After the water exits the tower, it is discharged to Van Etten Creek via Outfall 001A. Initially, free-product in the form of light non-aqueous phase liquid (LNAPL), if present, was periodically removed via recovery pumps contained within purge wells BZ-PW1 through 4, then later from BZ-PW3 through 6. However, these recovery pumps have been removed from all of the wells due to free product no longer being present. Effluent sampling was reduced originally from weekly to monthly, then monthly to quarterly over the years by the AF with the concurrence of the MDEQ.
The soils at and near the petroleum, oil, and lubricant bulk storage yard are currently undergoing remediation through soil vapor extraction (SVE) and bioventing to remove organics. The SVE and bioventing systems were installed in November 1999. A biosparging system, installed to cleanup residual fuel from the groundwater in this area, also began operating in 1999. The air sparging/SVE systems were installed at the Strategic Air Command (SAC) Operational Apron area in November 1999 to treat groundwater contaminated with volatile organics. The system was shut down in November 2001 when cleanup objectives were met. Post-closure monitoring is being conducted to ensure the treatment remains effective.
Northern Landfill (LF-30/31) Area
LF-30 is a 27-acre domestic and industrial waste landfill that operated from 1960 to 1973. LF-31 is a 74-acre landfill that operated between 1973 and 1979. In 1971, two 6,000-gallon tank trailers were buried in the center of LF-30 and used for the temporary storage of JP-4, oils, solvents, thinners, and lubricants. In 1973, LF-30 was closed and capped with pervious fill material and vegetated, in accordance with regulations existing at the time. During the operation of LF-31, the dumping of sewage, drums, solvents, oils and metal was banned. Approximately 10 acres of the landfill were used for the disposal of municipal waste, and the remainder reportedly received only demolition debris-such as concrete rubble, asphalt, lumber and paint. In 1979, LF-31 was closed for non-compliance with the Michigan Solid Waste Management Act of 1978 due to its location in permeable sandy soils, and the two tank trailers were excavated and removed from LF-30. In 1981, the portion of the landfill that received municipal/sanitary waste was capped using sand and a polyvinyl chloride (PVC) geomembrane. The cap was extended in 1983.
Currently the shallow aquifer underlying the site is not used as a drinking water supply. Groundwater contaminated in the Northern Landfill Area discharges into Van Etten Lake. En route to the lake, groundwater flows beneath Camp Nissokone, a summer recreational camp operated by the YMCA.
Three contaminated groundwater plumes have been identified as emanating from the LF-30/31 area, including a northern and southern VOC plume and a central BTEX plume. An 80-well barrier air sparging curtain was installed at the base boundary downgradient of the landfills and commenced full-time operations in May 2002. The primary intent of the system is to inject/add oxygen to the subsurface as a means to help restore the groundwater aquifer. In-situ stripping of VOCs is a secondary outcome of air sparging operations. A small groundwater and extraction treatment system was also installed at the base boundary north of the air sparging curtain to capture groundwater contaminated with chlorinated solvents in a narrow plume originating at the landfills that is traveling offsite. Monitoring is being conducted to measure the performance of the systems.
Groundwater from the Northern Landfill area discharging to Van Etten Lake at the YMCA beachfront has caused aesthetic impacts (iron staining) at the beach. Remedial actions performed at the YMCA beach include one sand removal/replacement (April 1999), and three sand placements (January 2001, January 2002, and January 2003). Oxygen Release Compound (ORC) was injected slightly upgradient of the beach to increase the dissolved oxygen levels in the aquifer so that staining would not occur. 4,770 pounds of ORC were injected through 97 points in February 2001 and 4,860 pounds of ORC were injected through 109 points near the beach in October 2001. Monitoring is being conducted to determine the impacts of the ORC application.
The Air Force has evaluated options for closure of the Landfill 30/Landfill 31 areas and is working with U.S. EPA and the Michigan DEQ on closure requirements. The Air Force has constructed an Engineered Wetland Groundwater Treatment System that began operation in 2011. The Air Force is currently working with EPA and MDEQ to develop an effective groundwater monitoring plan to assess the effectiveness of this remedy for the LF-30/31 area.
Landfill 27 (LF-27)
LF-27 is a 6.5-acre former landfill area located adjacent to a wetland (Clark's Marsh) near the southwest corner of the base. The site is located on and adjacent to the Au Sable River floodplain, which is adjacent to the upland area known as FT-02. From 1950 to 1972, the site received coal bottom ash, concrete, asphalt and metals. The Air Force is currently investigating groundwater contamination associated with the LF-27 area. The MDEQ is concerned that low-level metal contamination, especially manganese, in groundwater could pose a threat at the groundwater discharge point in Clark’s Marsh. MDEQ is also concerned about aesthetic impacts from “yellow boy” staining from elevated iron concentrations. A remedial investigation is planned for LF-27 in 2012.
Evaluation of Groundwater Treatment Systems
The Air Force is currently evaluating the groundwater “pump and treat” systems in operation (Arrow Street, Mission Street, and Benzene Plant) to ensure that the systems are capturing plume areas and operating efficiently. Phase I of the evaluation was completed in 2011, and Phase II is planned for 2012.
Future Site Reviews
A base-wide five-year review was completed in September 2004. A second base-wide five-year review was planned for 2009. Due to Air Force funding and contracting issues, this review was not completed until 2011. EPA has provided comments on the draft review and the MDEQ should provide comments by April 2012. A final report will then be generated by the Air Force. The result of the review was that the site is protective of human health and the environment because all remedies are operating as expected and appropriate institutional controls are in place at the base to prevent exposures to site contaminants.
Studies of the nature and extent of contamination at a few sites are still underway, such as LF-27. These investigations will result in the selection of remedies for final cleanup of these sites. Cleanup actions, including the operation of groundwater pump and treat systems, the connection to the potable water supply, the operation of the hydrocarbon skimmer, and the ex-situ bioremediation of the soil, have reduced the threat to human health and the environment while site investigations are underway. In addition, institutional controls are in place to prevent exposures to site contaminants.
Public meetings are occasionally held by the Air Force to provide updates on site cleanup to the surrounding community.
Property ReuseThe site is gradually being turned over from the Air Force to the Oscoda Airport Authority for reuse as an industrial park and airfield. Uses include cargo shipment and maintenance of jumbo jet aircraft by a private company on-site.
ContactsRemedial Project Manager, U.S. EPA
owen thompson (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA
AliasesWURTSMITH USAF BASE
US AIR FORCE WURTSMITH AFB