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Appendix A - On-Station Description of Sites

The information presented in this Appendix was collected from Marine Corps Air Station, El Toro, Installation Restoration Program, Draft Final Remedial Investigation and Feasibility Study Work Plan, 28 April 1991.

Operable Unit - 2

Site 2 - Magazine Road Landfill (OU-2)

Site 2 is located between the Borrego Canyon Wash, one of its tributaries, and a man-made unlined drainage channel. The site occupies an estimated 22 acres. The site was used as a landfill from the late 1960s to 1980, accepting all waste generated at that time from the air station including waste oils, hydraulic fluids, paint residues, transformers, solvents, construction debris, batteries and municipal waste.

Originally, the landfill was a gravel borrow pit. Material was placed in the borrow pit and backfilled. The landfill is completely filled with dirt and the surface supports the growth of grass. At the time of the site visit a corner of the area was covered with sand and used as a volleyball court.

Air and soil gas samples were taken between April and June 1990 at several locations on Site 2 by Strata Technologies, Inc., contractors for the Marine Corps (3).

Access to Site 2 is restricted by fence. Only authorized personnel are permitted to access the site.

Site 3 - Original Landfill (OU-2)

Site 3 is located between Perimeter Road and North Marine Way, and comprises six trenches covering over a total of 20 acres. The landfill was used from 1943 to 1955 as a cut-and-fill facility in conjunction with frequent burning to reduce the waste volume. Any wastes that were generated on the facility during that time would have been disposed in the Original Landfill. Wastes that could potentially be found in this landfill include metals, incinerator ash, solvents, paint residues, hydraulic fluids, engine coolants, construction debris, oily wastes, municipal solid wastes, and various inert solid wastes. Buried wastes probably consist of ash and other combustion wastes since standard practice was to burn the waste prior to burial to reduce volume (1). Reports indicate that in the past, black stains were visible in the sediments of Agua Chinon Wash that runs along the landfill area (1). That was not observed on the ATSDR site visit. The landfill is currently not in use; however, two of the trenches (one acre each) were uncovered during excavation for Building 746 and a parking area north of Building 380. Those buildings do not have basements. The parking lot and several buildings are adjacent to the landfill. Site access is not restricted other than those restrictions to gain admittance to the air station. Air and soil gas samples were taken between April and June 1990 at several locations on Site 3 by Strata Technologies, Inc., contractors for the Marine Corps (3).

Site 5 - Perimeter Road Landfill (OU-2)

Site 5 is next to the golf course along the MCAS boundary. The landfill consists of a buried trench 1200 feet long, 60 feet wide, and 20 feet deep. The landfill operated from 1955 until late 1960s receiving all types of waste generated at the station including burnable trash, municipal solid waste, unspecified fuels, oils, and solvents, cleaning fluids, scrap metals, paint residues, and other materials. Burning was performed to reduce waste volume (1). Approximately 500 feet away, outside the station boundary fence, the Borrego Canyon Wash crosses outside the station perimeter next to fields of strawberries where an estimated 60 farm workers were seen by ATSDR personnel. Currently, the landfill is covered with dirt. The flat ground surface supports the growth of grass and serves as an outer boundary for the golf course. Site access is not restricted other than those restrictions to gain admittance to the station.

Air and soil gas samples were taken between April and June 1990 at several locations on Site 5 by Strata Technologies, Inc., contractors for the Marine Corps (3).

Site 10 - Petroleum Disposal Area (OU-2)

Site 10 is located between Buildings 435 and 369, and is approximately 1200 feet long and 800 feet wide. Activities between 1952 and mid-1960s included the application of waste oils directly to the ground for dust control (1). An estimated 52,000 gallons of waste crankcase oil, antifreeze, hydraulic and transmission fluids, motor oils, and solvents were used for this practice (1). The area has been excavated and currently is covered by aircraft matting and a concrete apron. Site access is controlled by a guarded gate and fence. Only authorized personnel are permitted to access the site.

Site 17 - Communications Station Landfill (OU-2)

Site 17 covers 26 acres and is in a small canyon in the foothills of the Santa Ana Mountains. The landfill operated from 1981 through 1983 and received all station-wide waste. Couches, washing machines, refrigerators, sinks, and old tires were seen during the site visit. Reported waste include cooking grease, oils, fuels from sumps, and drums (1). It is estimated that the landfill received 36,000 gallons of liquid waste during its operation (1). Currently the site is not in use. Access to the site is not restricted. Children were seen on-station walking down a hill less than one-half mile away.

Air and soil gas samples are taken between April and June 1990 at several locations on Site 17 by Strata Technologies, Inc., contractors for the Marine Corps (3).

Operable Unit - 3

Site 1 - Explosive Ordnance Disposal Range - (EOD) (OU-3)

The EOD Range is at an elevation of 700 feet above mean sea level at the foothills of the Santa Ana Mountains. The range is next to a tributary of the Borrego Canyon Wash in the extreme northeastern section of MCAS. The site is used for the detonation and disposal of small munitions. However, it is not known if some material remains undetonated. Explosives are ignited in a 10 foot pit then covered with dirt. It is not known how long this site has been used for explosive ordnance disposal operations (1). In 1982, approximately 2000 gallons of sulfur trioxide chlorosulfonic acid (FS smoke) were disposed in trenches at the northern part of the site. Drums containing the chemicals were partially buried, then rupture with small explosive charges. FS smoke is a water-reactive compound that degrades to an acidic compound upon contact with water. Unsubstantiated reports indicate that a portion of the site was used to dispose of low-level radioactive material (1).

The potential contaminants from munitions disposal operations would be metals and nitrated toluenes from explosive ordnance disposal, sulfates and acidic wastes from the FS smoke disposal operations, and radioactive isotopes from the reported low-level radioactive materials disposal (1). Site access is controlled by a series of guarded gates and fences. This area represents a physical hazard due to the possible unexploded ordnance.

Site 4 - Ferrocene Spill Area (OU-3)

Site 4 is in the northeastern portion of the main station next to Site 3, at the southeastern side of Building 658 (engine testing facility). A dirt-lined drainage ditch along the spill site empties into the Agua Chinon Wash. In 1983, five gallons of ferrocene, a fuel additive, and hydrocarbon carrier solution were spilled on the ground. Reports indicate that the solution drained into the nearby drainage ditch leading to a catch basin for the Agua Chinon Wash (1). Site access is not restricted other than those restrictions to gain admittance to the station.

Site 6 - Drop Tank Drainage Area No. 1 (OU-3)

Site 6 is in a grass-covered area near Building 727, in the southern end of the hangar buildings. Nearby runoff empties into a dirt-lined ditch that flows along a catch basin eventually entering the Agua Chinon Wash. Past area use included draining JP-5 fuel from aircraft drop tanks and rinsing those tanks on the adjacent concrete apron that drains into the grassy area. It was estimated that 50 gallons per month were spilled on this area from 1969 to 1983 (1). Site access is controlled by fence and a guarded gate.

Site 7 - Drop Tank Drainage Area No.2 (OU-3)

Site 7 is between the runway and the concrete apron in an unpaved area covered with aircraft matting. A catch basin that discharges into the Agua Chinon and San Diego Creek is next to the spill area. From 1969 to 1983 this area was used to drain and wash aircraft drop tanks. Waste lubrication oils from nearby maintenance buildings were also disposed in this area (1). Reports indicate that many oil and fuel spills occurred over the years (1). Site access is restricted to authorized personnel.

Site 8 - Defense Reutilization and Marketing Office (DRMO) Storage Yard (OU-3)

Site 8 is approximately 1000 feet from the MCAS boundary in the southeastern portion of the station, at the intersection of Marine Way and R Street. In 1984, a polychlorinated biphenyl (PCB) spill from a leaking electrical console contaminated the soil. Much of the soil has been excavated to one foot below grade and transported by contractors to an off-site hazardous waste facility. Currently, the area is used as a storage yard for scrap and salvage materials, electrical components and drums of unknown liquids (2). The unpaved area is surrounded by a six-foot, barbed-wire topped fence.

Site 9 - Crash Crew Pit (OU-3)

The Crash Crew Pit is located in the western quadrant of the facility, just west of Building 435. However, the exact location of Site 9 is unknown (1). Historical records, aerial photos, and geophysical techniques will be used to determine the crash crew pit's location. From 1965 through 1971, the unlined crash crew pit was used as a fire training pit that was filled with water then layered with hundreds of gallons of oil-contaminated JP-5 fuel, gasoline, and other waste flammable liquids, then ignited. Fire fighting trainees then practiced quenching the fires. It has been estimated that 500 gallons of flammable waste liquids were used in each fire-training session with four practice sessions taking place per week during four months of the year (1). Of that amount, approximately 12,000 gallons may have percolated into the ground (1). The area is currently buried underneath a grassy area next to aviation matting (steel mesh).

Site 11 - Transformer Storage Area (OU-3)

This area is a 30-foot square concrete pad located next to Building 369. A catch basin and an asphalt-lined ditch catches the runoff from the concrete pad and areas near Building 369. A dirt area extends the entire width of the concrete pad. It is estimated that 50 to 75 transformers containing PCBs were stored there from 1968 to 1983. Reports stated that there have been leaks from five transformers and one transformer spill of PCB oil (1). Approximately 60 gallons of PCB oil drained from the concrete pads into the drainage ditch and surrounding soils (1). In 1983, the transformers were removed and transported off station. Current use includes temporary storage and holding of drums and transformers. The entire area is surrounded by a six-foot chain-link fence topped with three strands of barbed wire.

Site 12 - Sludge Drying Beds (OU-3)

Site 12 is in the southwestern corner of the Marine Corps Air Station approximately 300 feet from the station boundary. The sludge drying beds were used to remove water from municipal sludge and industrial sludge created from the on-station secondary wastewater treatment plant that operated from 1943 to 1972. Common contaminants from these type of sludges include heavy metals, pesticides, and hydrocarbons. The total area of approximately 880 cubic yards was plowed under when the wastewater treatment facility was closed. Approximately 150 feet away is a grass covered picnic area with several picnic tables. Next to the site is Building 307, a trailer used as an office. Bee Canyon Wash is approximately 250 feet from Site 12. Site access is not restricted other than those restrictions to gain admittance to the station.

Site 13 - Oil Change Area (OU-3)

Site 13 is in a grass-covered area next to Building 242 at the southwest corner of the facility. Past investigations indicated that from 1977 through 1983, 7000 gallons of crank case oils were drained from heavy equipment directly onto the ground at this site (1). Currently, the area is not in use and is surrounded by a six-foot chain-link fence with three strands of barbed wire on top.

Site 14 - Battery Acid Disposal Area (OU-3)

The battery acid disposal area is a grass-covered L-shaped strip of land approximately 75 feet long on one leg by 50 feet long on the other leg, and 3 feet wide approximately 50 feet from the former heavy equipment maintenance shop. A catch basin west of this patch of land receives drainage water from Site 14. The drainage then discharges into Bee Canyon Wash. Past disposal activities from 1977 through 1983 included the drainage of batteries directly onto the soil. The site is currently not in use. Site access is not restricted other than those restrictions to gain admittance to the station. During the site visit, ATSDR personnel noted a yellow patch of grass about 5 feet square within the lush green grass area of the site possibly indicating signs of stress.

Site 15 - Suspended Fuel Tanks (OU-3)

Site 15 is in a grass-covered area between Buildings 29 and 31, and consists of two investigation areas beneath elevated fuel tanks where stained soils were reported (1). From 1979 through 1984, two 500-gallon elevated diesel tanks were located there. Operations ceased in 1984 and the tanks were removed from the site. Reports state that two diesel tanks constantly leaked fuel from hoses and nozzles onto the soil beneath them (1). The heavy staining covered 750 square-feet. Currently, the area is not in use. Site access is restricted to authorized personnel by a six-foot chain-link fence.

Site 16 - Crash Crew Pit No. 2 (OU-3)

Site 16 is in the central runway area along El Toro Boulevard. The crash crew pit is a dirt area where fire training exercises were held. From 1972 to 1985 this area consisted of three pits. The largest pit, 50 feet in diameter and three feet deep was connected to a secondary pit 40 feet away by a drain pipe. The secondary pit was 12 feet by 35 feet wide and four feet deep. The third pit, ten feet long by three feet wide was used for practice with hand-held fire extinguishers. Parts of aircraft, jeeps, or machinery were placed in the pits, covered with waste fuels or oils, and then ignited. Trainees practiced putting out the fires. Reports state that small quantities of napalm, white phosphorus, and magnesium phosphate were also burned at this site (1). Today, the area is not in use. An old, charred helicopter still sits in the large pit. The secondary pit, at the time of the site visit, contained standing water from the recent rain. The Fire Training Area that is currently used is 200 feet away. It consists of two concrete pits: one circular pit and one Z-shaped pit each with built-in drainage channels. The entire Fire Training Area sits on a concrete pad surrounded by a 6-inch high concrete curb. Access to the site is prohibited due to its location within the flightline area.

Site 19 - ACER Site - (OU-3)

Site 19 is in a grass-covered area in the central flightline. The ACER site contained six 20,000-gallon bladder tanks for storage of JP-5 fuel. A 1600 square foot area with 4-foot high berm enclosed the tanks. From 1964 to 1987, leaks from fuel transfers, hoses, and couplings, in addition to a major spill in 1986 by a ruptured bladder tank, caused the contamination of soil. A 42-inch diameter subsurface storm channel runs to the east of Site 19 and drains to the Agua Chinon Wash. The tanks were removed and the soil was excavated to a depth of 15 feet. The soil was disposed of into a permitted hazardous chemical landfill. During the site visit, ATSDR personnel noted a 10-foot deep area containing standing water and several piles of "clean dirt". Access to the site is prohibited due to its location within the flightline area.

Site 20 - Hobby Shop (OU-3)

Site 20 is in Building 626 in the northwestern section of the facility. Since 1967, military personnel have used the hobby shop to service their privately-owned vehicles. A 600-gallon waste oil tank, located 10 feet underground, is routinely emptied by a private contractor. The soil area around the tank is stained black from oil. Additionally, three 700-gallon oil-water separators are around the shop area. Oil from those separators is emptied periodically by contractors. Water drains from the separators into a black soil-lined ditch that runs along the front gate. There are also three 50-gallon solvent tanks at the Hobby Shop. Sludge from those tanks is disposed of in the separators, while waste solvents is disposed of in drums. Prior to 1976, kerosene was used to wash down the asphalt at the site. Since 1976, biodegradable soap has been used for washing the pavement. The liquid wash then drain into the separators. Site access is restricted to military personnel.

Site 21 - Material Management Group (OU-3)

Site 21 is in an asphalt-covered area outside Building 320, surrounded by a six-foot chain-link fence with three strands of barbed wire at the top. The area has been included in the RI/FS by recommendation from EPA due to the large numbers of stored drums that may have leaked. In 1964, approximately 1000 drums were stored there; by 1986 only 100-125 drums were stored at the site. However, no leaks or spills have been reported. Site access is restricted to authorized personnel.

Site 22 - Tactical Air Fuel Dispensing System (OU-3)

Site 22 is between Buildings 435 and 369 directly next to Site 10. The site has a history of petroleum-based fuel spills and leaks (1). Clean-up activities have occurred although the quantity of the spills was unspecified, as was the exact remedial activity that took place. Site access is restricted to authorized military personnel by a guarded gate/fence.

Appendix B - Comments on El Toro Marine Corps Air Station

Comments were received by ATSDR during the public comment period for the El Toro Marine Corps Air Station public health assessment. All comments received by ATSDR were editorial in nature and corrected as appropriate.

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