Groundwater: High Risk

Contamination in the groundwater has migrated over 500 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration under the dry lake bed and then into the drinking water aquifer. Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source. Connectivity exists with the South Base production wells.

Contaminants: 1,3-Dichlorobenzene 1.2 ug/L Dibromochloromethane 2.5 ug/L 1,4-Dichlorobenzene 3.6 ug/L 1,2-Dichlorobenzene 3.8 ug/L Toluene 5.0 ug/L Bromodichloromethane 6.2 ug/L Chloroform 8.7 ug/L Xylene (Mixed) 9.4 ug/L Benzene 11.0 ug/L Bis(2-Ethylhexyl)Phthalate 13.0 ug/L 1,1-Dichloroethylene 24.0 ug/L n-Propylbenzene 28.0 ug/L sec-Butylbenzene 34.0 ug/L iso-Propylbenzene 35.0 ug/L 1,3,5-Trimethylbenzene 53.0 ug/L Naphthalene 68.0 ug/L 1,2,4-Trimethylbenzene 120.0 ug/L Trichloroethylene (TCE) 140.0 ug/L Tetrachloroethylene 180.0 ug/L 1,2-Dichloroethylene (cis) 180.0 ug/L

Groundwater: High Risk

Contamination in the groundwater has migrated over 300 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration into the drinking water aquifer. Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source. Connectivity exists with the South Base production wells.

Contaminants: cis-1,2-Dichloroethylene 1.0 ug/L Tetrachloroethylene 5.5 ug/L Xylene (Mixed) 6.2 ug/L Lead 7.6 ug/L Toluene 8.3 ug/L Copper and compounds 80.0 ug/L Trichloroethylene (TCE) 120.0 ug/L Zinc 220.0 ug/L Iron 33800.0 ug/L

Groundwater: High Risk

Contamination in the groundwater has migrated over 300 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migrating under the dry lake bed and then into the drinking water aquifer. Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source. Connectivity exists with the South Base production wells.

Contaminants: Arsenic 12.0 ug/L Benzyl Alcohol 20.0 ug/L Anthracene 20.0 ug/L Benzo(b)Fluoranthene 21.0 ug/L Chrysene 26.0 ug/L 2-Methylphenol (o-Cresol) 32.0 ug/L Trichloroethylene (TCE) 43.0 ug/L Methylene Chloride 50.0 ug/L Pyrene 73.0 ug/L Fluoranthene 75.0 ug/L cis-1,2-Dichloroethylene 92.0 ug/L Cumene 110.0 ug/L Manganese and compounds 120.0 ug/L Nickel (soluble salts) 160.0 ug/L 1,3,5-Trimethylbenzene 230.0 ug/L Chromium 390.0 ug/L Naphthalene 520.0 ug/L 1,2,4-Trimethylbenzene 800.0 ug/L Ethyl benzene 1500.0 ug/L Aluminum 1900.0 ug/L Benzene 3200.0 ug/L Iron 3500.0 ug/L Xylene (Mixed) 5900.0 ug/L Toluene 7600.0 ug/L

Groundwater: High Risk

Contamination in the groundwater has migrated over 300 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration under the dry lake bed and then into the drinking water aquifer. Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source. Connectivity exists with the South Base production wells.

Contaminants: Ethylene Dibromide 0.02 ug/L 1,1,1-Trichloroethane 1.2 ug/L 1,2-Dichloroethane (EDC) 1.8 ug/L Methylene Chloride 3.5 ug/L Diethyl Phthalate 5.0 ug/L sec-Butylbenzene 6.1 ug/L 1,1-Dichloroethylene 9.6 ug/L Bis(2-Ethylhexyl)Phthalate 11.0 ug/L Dimethyl Phthalate 20.0 ug/L 1,3,5-Trimethylbenzene 31.0 ug/L Cumene 31.0 ug/L cis-1,2-Dichloroethylene 33.0 ug/L 1,1-Dichloroethane 40.0 ug/L 1,2,4-Trimethylbenzene 100.0 ug/L Ethyl benzene 410.0 ug/L Trichloroethylene (TCE) 490.0 ug/L Naphthalene 620.0 ug/L Toluene 2200.0 ug/L Benzene 2400.0 ug/L Xylene (Mixed) 2720.0 ug/L

Groundwater: Medium Risk

The contamination is in the groundwater beneath the site, there is a potential connection to drinking water aquifer. Since the State of california considers all groundwater to be a source for domestic and agricultural purposes, there is a risk to human health.

Contaminants: Arsenic 190.0 ug/L

Soil: Medium Risk

Potential exists for the perchlorate to migrate to the groundwater. Potential exists for the constructrion workers exposed to the contaminated soil.

Contaminants: Arsenic 0.10934 mg/kg

Groundwater: Medium Risk

While contamination in the groundwater has migrated beyond the edge of the source further migration is unlikely. The plume is at the low point of the lake bed and there is no gradient to move the plume any further. Contamination is not expected to impact a beneficial source within five years. There is no threat to any existing drinking water well. California EPA considers all groundwater to be a potential domestic or agricultural source.

Contaminants: Zinc 210.0 ug/L cis-1,2-Dichloroethylene 290.0 ug/L Barium 580.0 ug/L Ethyl benzene 640.0 ug/L Manganese and compounds 870.0 ug/L Molybdenum 1300.0 ug/L Toluene 1400.0 ug/L Xylene (Mixed) 3200.0 ug/L Trichloroethylene (TCE) 3400.0 ug/L Benzene 4400.0 ug/L Aluminum 37300.0 ug/L Iron 61900.0 ug/L

Soil: Low Risk

Soil contamination is limited. No significant contaminants exist in the surface soils. There are no significant contamints to be exposed to.

Contaminants: Silver and compounds 0.001 mg/kg Selenium 0.001 mg/kg Antimony and compounds 0.0085 mg/kg Molybdenum 0.0088 mg/kg Copper and compounds 0.0394 mg/kg Aluminum 29.7 mg/kg

Groundwater: Medium Risk

Contamination in the groundwater has migrated beyond the edge of the source, however migration has essentially ceased. The potential of migrating under the dry lake bed and then into the drinking water aquifer is limited. Contamination is not expected to impact a beneficial source. The potential of migrating under the dry lake bed and then into the drinking water aquifer is limited. The nearest well field is 6 miles away crossgradient.

Contaminants: Trichloroethylene (TCE) 32000.0 ug/L

Soil: Low Risk

Contaminants are likely representative of dissolved contaminants in the groundwater. Concentrations are low enough to have limited receptor factors.

Contaminants: Benzene 3.0e-05 mg/kg Trichloroethylene (TCE) 4.0e-05 mg/kg Toluene 0.00024 mg/kg

Soil: Low Risk

Contaminants: Chromium (VI) 0.014 mg/kg

Groundwater: Medium Risk

Contamination has been observed in downgradient monitoring wells located more than 100 feet from the source area. There are no threatened water supply wells; modeling has shown contamination will not reach the wells for >500 yrs. Concentrations of arsenic are below background levels, but above drinking water standards. Groundwater is of limited beneficial use.

Contaminants: Carbon tetrachloride 1.2 ug/L Toluene 1.7 ug/L Chloroform 3.5 ug/L 1,2-Dichloroethane (EDC) 16.0 ug/L 1,2-Dichloroethylene (cis) 130.0 ug/L Trichloroethylene (TCE) 680.0 ug/L Tetrachloroethylene 790.0 ug/L

Soil: Low Risk

Contaminants: Chromium (VI) 0.014 mg/kg

Groundwater: Medium Risk

Contaminants have been observed in downgradient wells greater than 100 feet beyond the source. It is not known at this time whether the drinking water aquifer beneath the communitiy of Boron will be impacted within five years.

Contaminants: Chloroform 1.3 ug/L 1,2-Dichloroethane (EDC) 2.6 ug/L Carbon tetrachloride 3.5 ug/L Bis(2-Ethylhexyl)Phthalate 15.0 ug/L Trichloroethylene (TCE) 180.0 ug/L Tetrachloroethylene 2200.0 ug/L

Soil: Low Risk

Contaminants were not detected in concentrations which pose a significant health threat.

Contaminants: Acetone 1.3e-05 mg/kg

Soil: Medium Risk

Contaminants exist in concentrations sufficient for downward migration. Note that the constituent 1,3-xylene is a substitute contaminant for TPH which is not included as a Relative Risk Contaminant but is mandated by California Law. Receptors may be exposed during excavation activities or if contamination migrates into groundwater.

Contaminants: 1,3-Xylene 3.14 mg/kg

Groundwater: Medium Risk

Contaminated groundwater can be seen seeping out of rock formation below the test stand. Groundwater wells greater than 100 feet from source have been impacted with similar contaminants. There are no threatened water supply wells; modeling has shown contamination will not reach the wells for >500 yrs. Concentrations of arsenic are below background levels, but above drinking water standards. Groundwater is of limited beneficial use.

Contaminants: Trichloroethylene (TCE) 4300.0 ug/L

Sediment (Fresh): Low Risk

Contamination is at a point of exposure.

Contaminants: cis-1,2-Dichloroethylene 4.6e-06 mg/kg Trichloroethylene (TCE) 8.6e-06 mg/kg

Sediment (Human): Low Risk

Contamination is at a point of exposure. Workers from Test Stand 1-A have direct access to contaminated sediments at the base of the test stand.

Contaminants: cis-1,2-Dichloroethylene 4.6e-06 mg/kg Trichloroethylene (TCE) 8.6e-06 mg/kg

Groundwater: Medium Risk

Contamination in groundwater has migrated over 100 feet beyond the source. However, a leading edge pump and treat containment system implemented as an IRA in November 2001 is successfully preventing further migration of the plume leading edge. Groundwater contamination has not impacted a production well or other beneficial source and is not expected to impact one within five years.

Contaminants: Vinyl Chloride 2.4 ug/L N-Nitrosodimethylamine 5.09 ug/L 1,4-Dioxane 5.42 ug/L Tetrachloroethylene 330.0 ug/L Trichloroethylene (TCE) 210000.0 ug/L

Groundwater: Medium Risk

Due to groundwater pumping from the treatment system, contaminants in the groundwater have little potential to migrate downgradient of the source. Contamination is not expected to impact a beneficial source or production well within five years. Cal EPA considers all groundwater to be a potential domestic or agricultural source.

Contaminants: 1,1-Dichloroethane 15.0 ug/L Naphthalene 210.0 ug/L o-Xylene 920.0 ug/L Toluene 1400.0 ug/L 1,2-Dichloroethylene (cis) 2600.0 ug/L Benzene 9300.0 ug/L Trichloroethylene (TCE) 96000.0 ug/L

Soil: Medium Risk

Surface soil contamination may migrate to a point of exposure. If contamination reaches the bare topsoil, it would be exposed to frequent high winds resulting in the inhalation of contaminated fugitive dust by receptors. Potential exposure to off-site workers, 487 on-site workers, and future construction workers consists of soil contact and inhalation of fugitive dust and VOCs. Ecological receptors include plants, and primary and secondary mammalian consumers.

Contaminants: Methylene Chloride 1.3e-05 mg/kg Beryllium and compounds 0.00051 mg/kg Cadmium and compounds 0.00063 mg/kg Benzene 0.005 mg/kg Lead 0.0050999999999999995 mg/kg Arsenic 0.0228 mg/kg Barium 0.599 mg/kg Manganese and compounds 10.6 mg/kg Aluminum 18.7 mg/kg

Soil: Medium Risk

PCB and Dioxin impacts to soil are limited to the upper 2.5 feet, with the deepest impact occuring in the immediate vicinity of the transformer pad (inside perimeter fence). Outside the perimeter fence, PCB and Dioxin impacts are limited to the surface. S There is a potential for Civil Engineering maintenance crews to be exposed to contaminated soil while working in and around the former transformer location.

Contaminants: Dioxin (2,3,7,8-TCDD) 2.48e-05 mg/kg PCBs 0.05 mg/kg

Soil: Medium Risk

Potential contaminants near the surface can migrate via airborne soils or via the movement of moisture through the landfill. The landfill is adjacent to an access road to the former base sewage plant and effluent evaporation ponds. The access road is occasionally traveled by base personnel. There are no direct means for receptors to have access to surface soil contamination.

Contaminants: Beryllium and compounds 0.0017 mg/kg Molybdenum 0.0083 mg/kg Antimony and compounds 0.0109 mg/kg Cadmium and compounds 0.018600000000000002 mg/kg Arsenic 0.0325 mg/kg Chromium 0.0412 mg/kg Silver and compounds 0.0497 mg/kg Copper and compounds 0.113 mg/kg Vanadium 0.117 mg/kg Zinc 0.341 mg/kg Barium 0.394 mg/kg Lead 0.784 mg/kg Aluminum 48.1 mg/kg Iron 146.0 mg/kg

Groundwater: Low Risk

No groundwater contamination

Contaminants: Trichloroethylene (TCE) 0.0 ug/L

Groundwater: Medium Risk

Currently, information is not available to support an MPF of evident or confined. Further sampling is necessary to assess the extent of organic contaminants and to further characterize the organic compounds present. There is no threatened water supply well down gradient from the source and the groundwater is potentially usable for drinking water, irrigation, or agriculture.

Contaminants: Benzene 1.2 ug/L 1,2-Dichloroethane (EDC) 49.0 ug/L

Soil: Low Risk

There is no surface soil contamination

Contaminants: Zinc 0.159 mg/kg

Groundwater: Low Risk

Contamination in the groundwater has migrated over 100 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration into the drinking water aquifer. Groundwater contamination has not yet impacted a production well or other beneficial source and is not expected to impact one within five years.

Contaminants: Trichloroethylene (TCE) 21.0 ug/L

Groundwater: Low Risk

Contamination in the groundwater has migrated over 1,200 feet beyond the edge of the source and there are no known barriers to contaminant migration. Groundwater contamination will not impact a production well or other drinking water sources.

Contaminants: 1,3,5-Trimethylbenzene 1.2 ug/L Tetrachloroethylene 2.7 ug/L 1,2,4-Trimethylbenzene 3.6 ug/L Benzene 4.2 ug/L Toluene 19.0 ug/L Xylene (Mixed) 22.0 ug/L Trichloroethylene (TCE) 60.0 ug/L

Groundwater: Low Risk

The landfill is unlined, contamination has impacted groundwater. Contaminants have migrated downward toward groundwater or moved upward as gas. Volatile organic compounds, halogenated volatiles, pesticides, and metals are present in the groundwater above This aquifer is located within the Lancaster Groundwater Basin. California EPA considers all groundwater to be a potential domestic or agricultural source.

Contaminants: Heptachlor 0.27 ug/L Mercury (Methyl) 2.5 ug/L 1,1-Dichloroethylene 5.2 ug/L Benzene 5.8 ug/L Vinyl Chloride 13.0 ug/L Perchloroethylene (PCE) 21.0 ug/L Trichloroethylene (TCE) 25.0 ug/L Methylene Chloride 220.0 ug/L

Soil: Low Risk

Semivolatile organic compounds (SVOCs) and lead concentrations exceeding USEPA residential Preliminary Remediation Goals (PRGs) were detected in the near surface soil. Lead also exceeded background concentration. Low concentrations of unknown extractable Recreational horse stables used by base personnel are located 800 feet southwest of the Site. Main Base housing area is located approximately 1,500 feet south of the inactive landfill.

Contaminants: Benzo(a)Pyrene 0.0006 mg/kg Benz(a)Anthracene 0.00096 mg/kg Lead 0.194 mg/kg

Groundwater: Low Risk

There is very little potential for migration because: groundwater is very deep, there is no hydraulic gradient, there is no continuing source of contamination, and modelling indicates it would take at least 100 years for contamination to reach any wells. There are no threatened water supply wells downgradient from the source, but the groundwater is potentially usable for drinking water, irrigation, or agriculture.

Contaminants: Benzene 130.0 ug/L

Soil: Low Risk

There is no evidence of movement from the unconconfined source. Civil Engineering maintenance crews and hangar personnel have a possibility of coming into either skin and inhalation contact with the fuel hydrocarbon contamination.

Contaminants: Benzene 0.0 mg/kg

Soil: Low Risk

Limited site assessment activities have been performed. Additional assessment activities are believed to reveal more extensive contamination at the site.

Contaminants: 1,2-Dichloroethane (EDC) 3.0e-05 mg/kg

Soil: Low Risk

The berm's lead bullet/material contaminated soil has a potential pathway through both the subsurface (leading to the groundwater) and exists on the surface of the terrain. Eleven bullets per cubic foot of soil found in one sample. Humans rarely frequent the site. The potential for inhalation of contaminated fugitive dust emissions during frequent high wind conditions exists.

Contaminants: Lead 0.052000000000000005 mg/kg

Groundwater: Low Risk

Although contamination has migrated more than 100 feet from the source, further migration is limited due to downgradient treatment systems at OU1 Contamination will never reach any receptors due to geology and downgradient treatment systems at OU1.

Contaminants: Benzene 9.0 ug/L cis-1,2-Dichloroethylene 19.0 ug/L Tetrachloroethylene 59.0 ug/L Trichloroethylene (TCE) 370.0 ug/L

Soil: Low Risk

There are no known barriers to suface soil contaminant migration. Contaminated soil may be transported by frequent high winds. The site is currently vacant land. Future construction workers may potentially be exposed to contaminated soil or contaminated dust in the air from Site 299.

Contaminants: Lead 0.396 mg/kg

Soil: Low Risk

Potential contaminants may be a source of exposure for airborne contamination as well as penetrating into groundwater. Note that the constituent 1,3-xylene is a substitute contaminant for TPH which is not included as a RR list contaminant but is mandated Potential contaminants may be a source of exposure for workers

Contaminants: 1,3-Xylene 0.21 mg/kg

Groundwater: Low Risk

Currently, information is not available to support an MPF of evident or confined. Further sampling is necessary to further delinieate the downgradient extent of the TCE amd perchlorate groundwater plumes. There is no threatened water supply well down gradient from the source and the groundwater is potentially usable for drinking water, irrigation, or agriculture.

Contaminants: Perchlorate 5.0 ug/L cis-1,2-Dichloroethylene 11.0 ug/L Trichloroethylene (TCE) 23.0 ug/L

Soil: Low Risk

Lead bullets are concentrated in the upper 1.5 feet of soil in the berms. TCLP and synthetic leaching potential indicate lead is unlikely to migrate below 5 feet bgs (Site 294 & 296 data). Six bullets per cubic foot of soil was found in one sample collect Humans rarely frequent the site. The potential for inhalation of contaminated fugitive dust emissions during frequent high wind conditions exists.

Contaminants: Lead 0.963 mg/kg

Surface Water: Low Risk

Surface water is contained in bermed areas. A full time individual from RKO occupies the site during working hours but is not expected to contact the surface water.

Contaminants: Dibromochloromethane 1.6 ug/L Chloroform 1.6 ug/L Bromodichloromethane 2.0 ug/L Tetrachloroethylene 2.1 ug/L

Surface Water (Fresh): Low Risk

Surface water is contained in bermed areas. A full time individual from RKO occupies the site during working hours but is not expected to contact surface water.

Contaminants: Dibromochloromethane 1.6 ug/L Chloroform 1.6 ug/L Bromodichloromethane 2.0 ug/L Tetrachloroethylene 2.1 ug/L

Soil: Low Risk

A soil sample was collected 6 inches below the surface within the stained soils adjacent to the concrete slab and analyzed for TPH and PCB. A concrete grab sample of the stained pad was submitted for PCB analysis. The soil sample TPH concentration was rep Connectivity exists between the groundwater in OU-10 and the base drinking water wells located in the North Base area.

Contaminants: PCB 0.0009000000000000001 mg/kg

Soil: Low Risk

Soil contaminants are not mobile and cannot migrate to groundwater Contamination is below where any regular activity would result in exposure. Site controls prevent exposure without PPE

Contaminants: Silver and compounds 5.139 mg/kg

Soil: Low Risk

Contaminants: Lead 0.034 mg/kg

Soil: Low Risk

Contamination is not on the surface so inhalation is not a factor Receptor access to the site is limited.

Contaminants: Trichloroethylene (TCE) 0.082 mg/kg

Groundwater: Low Risk

Additional groundwater monitoring wells are required to determine whether migration greater than 100 feet from the source has occurred. Contaminated groundwater has a potential to migrate towards North Base drinking water wells.

Contaminants: Tetrachloroethylene 0.4 ug/L Carbon tetrachloride 4.8 ug/L Chloroform 5.4 ug/L

Soil: Low Risk

Surface soil contamination can migrate to a point of exposure. Contamination in the bare topsoil is exposed to frequent high winds resulting in the inhalation of contaminated fugitive dust by receptors. There is no direct means for receptors to have access to surface soil contamination, however potential receptors are currently being evaluated..

Contaminants: Carbon tetrachloride 0.023 mg/kg

Groundwater: Low Risk

Although contamination has migrated more than 100 feet from the source, further migration is limited due to downgradient treatment systems at OU1 Contamination will never reach any receptors due to geology and downgradient treatment systems at OU1.

Contaminants: cis-1,2-Dichloroethylene 12.0 ug/L 1,2-Dichloroethane (EDC) 40.0 ug/L Toluene 41.0 ug/L Naphthalene 65.0 ug/L Trichloroethylene (TCE) 130.0 ug/L Xylene (Mixed) 550.0 ug/L 1,2,4-Trimethylbenzene 620.0 ug/L Ethyl benzene 650.0 ug/L Benzene 1200.0 ug/L

Soil: Low Risk

There is the potential for the inhalation of airborne contaminated soil during frequent high wind. Receptor access to the site is limited.

Contaminants: Arsenic 0.042 mg/kg

Groundwater: Low Risk

The Soil Vapor Extraction remediation system that is currently operating at the site will ensure that the contaminants in the groundwater have little potential to migrate downgradient of the source. The groundwater contamination is not expected to impact a benificial source.

Contaminants: 1,2-Dichloroethylene (cis) 6.3 ug/L 1,2-Dichloroethane (EDC) 18.0 ug/L Trichloroethylene (TCE) 55.0 ug/L Benzene 100.0 ug/L Ethyl benzene 440.0 ug/L

Groundwater: Low Risk

Source control provided by the existing DES system eliminates any potential further migration of plume. Source control and institutional controls eliminate potential recepter impacts.

Contaminants: Toluene 96.0 ug/L Benzene 260.0 ug/L 1,2-Dichloroethane (EDC) 440.0 ug/L Xylene (Mixed) 810.0 ug/L Trichloroethylene (TCE) 16000.0 ug/L

Soil: Low Risk

Surface soil contamination can migrate to a point of exposure to due poor containment of soils. Site is located in a remote area inhabited by wildlife.

Contaminants: Cadmium and compounds 0.01 mg/kg Lead 0.22219999999999998 mg/kg

Groundwater: Low Risk

Although contamination has migrated more than 100 feet from the source, further migration is limited due to downgradient treatment systems at OU1 Contamination will never reach any receptors due to geology and downgradient treatment systems at OU1.

Contaminants: Benzene 9500.0 ug/L

Soil: Low Risk

There is relatively minor soil contamination in a couple of areas where the pipeline leaked, however, the contamination is located 56 inches under the ground surface. There is no expected future receptor access to soil contamination.

Contaminants: Benzene 0.054 mg/kg

Groundwater: Low Risk

Contamination in the groundwater has migrated over 100 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration into the drinking water aquifer. Groundwater contamination has not yet impacted a production well or other beneficial source and is not expected to impact one within five years.

Contaminants: Trichloroethylene (TCE) 1.9 ug/L

Soil: Low Risk

The areas where the drums are located contain potential pathways through both the subsurface (leading to the groundwater) and on the surface of the terrain. No detected concentrations of TPH, or volatile or semi-volatile organics in soil samples. Off-base housing development within several hundred feet of site. There is the potential for the inhalation of contaminated fugitive dust emissions during periods of frequent high winds.

Contaminants: Benzo(a)Pyrene 0.001 mg/kg

Groundwater: Low Risk

Although contamination has migrated more than 100 feet from the source, further migration is limited due to downgradient treatment systems at OU1 Contamination will never reach any receptors due to geology and downgradient treatment systems at OU1.

Contaminants: Xylene (Mixed) 3.1 ug/L 1,1-Dichloroethylene 4.4 ug/L Toluene 9.5 ug/L Benzene 17.0 ug/L 1,1-Dichloroethane 17.0 ug/L cis-1,2-Dichloroethylene 24.0 ug/L Perchloroethylene (PCE) 29.0 ug/L Chloroform 51.0 ug/L Trichloroethylene (TCE) 1600.0 ug/L

Soil: Low Risk

Limited site assessment activities have been performed. Additional assessment activities are believed to reveal more extensive contamination at the site. Potential receptors are currently being evaluated.

Contaminants: Xylene (Mixed) 6.6e-06 mg/kg Tetrachloroethylene 1.9e-05 mg/kg Toluene 2.7e-05 mg/kg Naphthalene 0.00054 mg/kg Benzo(a)Pyrene 0.00091 mg/kg Chrysene 0.0015 mg/kg Benzo(b)Fluoranthene 0.0016 mg/kg Fluoranthene 0.0027 mg/kg Pyrene 0.0028 mg/kg

Groundwater: Low Risk

Installed groundwater and vadose zone treatment system confines contaminants. Installed groundwater and vadose zone treatment system controls exposure to potential receptors.

Contaminants: 1,1-Dichloroethylene 1.2 ug/L 4-Methylphenol (p-Cresol) 18.0 ug/L 1,2-Dichloroethane (EDC) 20.0 ug/L Cumene 190.0 ug/L 1,1,1-Trichloroethane 250.0 ug/L Ethylene Dibromide 360.0 ug/L 1,3,5-Trimethylbenzene 430.0 ug/L Naphthalene 1400.0 ug/L Methylene Chloride 2300.0 ug/L Trichloroethylene (TCE) 2500.0 ug/L 1,2,4-Trimethylbenzene 3300.0 ug/L Xylene (Mixed) 6100.0 ug/L Benzene 6500.0 ug/L Toluene 8700.0 ug/L

Soil: Low Risk

There is the potential for the inhalation of airborne contaminated soil during frequent high wind. Furan is not soluble in water so there is no potential for migration to groundwater. Arsenic concentations are below background. Groundwater is not impacted Potential receptors include populations of numerous waterfowl in the area, and animals throughout the region are attracted to this abundant source of water.

Contaminants: Furan 0.0106 mg/kg

Groundwater: Low Risk

The contamination in the groundwater has migrated up to 100 feet beyond the edge of the source and there are no known barriers to contaminant migration. The hydrologic regime in the vicinity of the site has not been characterized and it is not known whether a current benficial groundwater source will be impacted within the next 5 years from contamination beneath the site.

Contaminants: Trichloroethylene (TCE) 17.0 ug/L

Soil: Low Risk

The suspected UST and grease pit contain potential pathways through both the subsurface (leading to the groundwater) and on the surface of the terrain. Humans rarely frequent the site, however wildlife frequent the area. Populations of federally protected desert tortoise are in the vicinity. The potential for inhalation of contaminated fugitive dust emissions during frequent high wind conditions exists.

Contaminants: Chrysene 0.0001 mg/kg

Soil: Low Risk

Contaminants: Chromium (VI) 0.032 mg/kg

Groundwater: Low Risk

TCE concentration is 3.6 ppb, below its MCL, and appears to originate from Site 18. A Site 18 IRA will remove the TCE in FY 99. Since the source is outside the site, and the site concentration is below MCLs, contaminant migration is confined. Since the source of the contamination is another site which is scheduled for remediation, there is no expected future receptor access to groundwater contamination from this site.

Contaminants: Trichloroethylene (TCE) 3.6 ug/L

Soil: Low Risk

There is no surface soil contamination. The area is on the flightline and there are human, plant and animal receptors, however, lack of surface contamination limits potential exposure.

Contaminants: Lead 0.002968 mg/kg Toluene 0.04913000000000001 mg/kg Ethyl benzene 0.0522 mg/kg

Groundwater: Low Risk

The extent of the groundwater contamination has remained stable for the past 15 years and no further migration is anticipated. Groundwater contamination has not yet impacted and is not likely to.

Contaminants: cis-1,2-Dichloroethylene 1.4 ug/L Trichloroethylene (TCE) 85.0 ug/L Naphthalene 230.0 ug/L Toluene 1800.0 ug/L Xylene (Mixed) 2700.0 ug/L Benzene 8700.0 ug/L

Soil: Low Risk

No Soil contamination - so no migration

Contaminants: Benzene 0.0 mg/kg

Soil: Low Risk

The supply yard was paved in 1980, preventing migration of the impacted soil. Humans work on-site, but should not come in contact with contaminated surface soil due to the asphalt paving that covers the supply yard. Future construction workers may potentially be exposed to contaminated soil and inhalation of contaminants in air.

Contaminants: Benzene 0.4 mg/kg Arsenic 1.1500000000000001 mg/kg

Soil: Low Risk

None of the metals leached at significant concentrations below 5 feet BGS - indicating no potential impact to groundwater (> 100 feet BGS). PAH analyses showed only Benzo(a)pyrene exceeded the residential PRG in samples from 5 feet BGS. Remote area inhibited by wildlife. Populations of federally protected desert tortoise have been spotted in the area. There is the potential for the inhalation of contaminated fugitive dust emissions during periods of frequent high wind activity.

Contaminants: Dibenz[ah]anthracene 7.4e-05 mg/kg Benz(a)Anthracene 0.0067 mg/kg Benzo(b)Fluoranthene 0.006900000000000001 mg/kg Benzo(a)Pyrene 0.015 mg/kg Lead 0.165 mg/kg

Groundwater: Low Risk

Contamination in the groundwater has migrated over 200 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration under the dry lake bed and then into the drinking water aquifer. Risk is Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source. Connectivity exists with the South Base production wells.

Contaminants: 1,1,1-Trichloroethane 0.5 ug/L Ethyl benzene 1.2 ug/L 1,2,4-Trimethylbenzene 1.3 ug/L cis-1,2-Dichloroethylene 2.8 ug/L Benzene 3.2 ug/L Toluene 4.2 ug/L Tetrachloroethylene 4.2 ug/L Xylene (Mixed) 4.4 ug/L 1,1-Dichloroethylene 5.0 ug/L Bis(2-Ethylhexyl)Phthalate 9.0 ug/L Trichloroethylene (TCE) 61.0 ug/L

Groundwater: Low Risk

Groundwater not currently used. TDS too high for normal drinking water

Contaminants: Thallium Chloride 6.0 ug/L

Groundwater: Low Risk

Additional groundwater monitoring wells are required to determine whether migration has or is occurring.

Contaminants: Trichloroethylene (TCE) 1.2 ug/L Benzoic Acid 80.0 ug/L 4-Methylphenol (p-Cresol) 190.0 ug/L

Groundwater: Low Risk

The contamination has migrated, however, there is very little potential for additional migration since the groundwater is very deep, no hydraulic gradient no continuing source and modelling indicates at least 100 years to reach any wells. Connectivity may exist between groundwater in OU-5 and the base drinking water wells located in the nearby North Base area, however, modelling indicates a very long time to reach them

Contaminants: Carbon tetrachloride 24.0 ug/L Trichloroethylene (TCE) 150.0 ug/L

Soil: Low Risk

Very low concentrations of contaminants were detected at 52-54 ft bgs. Due to the depth, pathways are determined confined for all condition except excavation in the defined area. Depth to contamination in soil is beyond the exposure potential for receptors from the surface and still an estimated 5 years from contaminating a beneficial groundwater source.

Contaminants: Indeno(1,2,3-cd)Pyrene 0.00067 mg/kg Benzo(k)Fluoranthene 0.0014 mg/kg Benzo(a)Pyrene 0.0016 mg/kg

Groundwater: Medium Risk

TCE contamination in the groundwater has migrated over 100 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration under the dry lake bed and then into the drinking water aquifer. South Base potable water supply wells are located approximately 3.2 miles southwest. Contamination is not expected to impact a beneficial source within five years.

Contaminants: Chloroform 0.52 ug/L Xylene (Mixed) 1.1 ug/L 1,2,4-Trimethylbenzene 1.1 ug/L Bromodichloromethane 1.4 ug/L Bromoform 3.8 ug/L Dibromochloromethane 4.1 ug/L Trichloroethylene (TCE) 13.0 ug/L

Soil: Medium Risk

PCB's in soil around transformer Workers may be exposed through direct contact with the contamination.

Contaminants: PCBs 0.17 mg/kg

Groundwater: Risk Not Evaluated

Sediment (Ecological): Risk Not Evaluated

Sediment (Human): Risk Not Evaluated

Soil: Risk Not Evaluated

Surface Water: Risk Not Evaluated

Surface Water (Ecological): Risk Not Evaluated

Groundwater: Medium Risk

Contaminants have been observed in downgradient wells at distances greater than 100 feet from suspected source area. At this time, groundwater beneath the site has been classified as part of the contaminated aquifer beneath Site 133 and any risk are assoc The Phillips Laboratory Wellfield is located downgradient of site. However, it is not known at this time whether the wellfield will be impacted within 5 years. Risk is associated with Site 133.

Contaminants: Trichlorofluoromethane 2.1 ug/L Toluene 3.5 ug/L Chloroform 9.4 ug/L Tetrachloroethylene 36.0 ug/L Acetone 37.0 ug/L cis-1,2-Dichloroethylene 120.0 ug/L Trichloroethylene (TCE) 3300.0 ug/L

Groundwater: Medium Risk

Based on the results of the conceptual site model in the FS and contaminante transport modeling, there is little risk with the plume reaching the receptor. Contaminants have been found in downgradient wells in distances ranging from adjactent to the sourc Groundwater flow appears to take an eventual path toward the Phillips Laboratory wellfield. However, it is not known at this time whether the wellfield will be impacted within the next 5 years.

Contaminants: Trichloroethylene (TCE) 920.0 ug/L Tetrachloroethylene 46000.0 ug/L

Soil: Low Risk

Per the FS findings, there is no soil contamination at site 37. Contaminats in the subsurface soil may reach the underlying groundwater and/or act as a continuing source of groundwater contamination.

Contaminants: Perchloroethylene (PCE) 0.37 mg/kg

Groundwater: Low Risk

Based on the results of the conceptual site model in the FS and contaminante transport modeling, there is little risk with the plume reaching the receptor. Contamination has migrated over 100 feet beyond the edge of the source and there are no known barri The Site is upgradient of the Phillips Laboratory Well Field and North Muroc Sub Basins, however, communication between the contaminant plume and the aquifer has not been established.

Contaminants: Trichloroethylene (TCE) 16.0 ug/L cis-1,2-Dichloroethylene 400.0 ug/L Tetrachloroethylene 550.0 ug/L

Surface Water: Risk Not Evaluated

Contaminants: cis-1,2-Dichloroethylene 9.2 ug/L

Surface Water (Fresh): Risk Not Evaluated

Contaminants: cis-1,2-Dichloroethylene 9.2 ug/L

Soil: Low Risk

There is the potential for inhalation of contaminated soil during frequent dust storms. Receptors have limited access to the site.

Contaminants: Arsenic 0.05 mg/kg

Groundwater: Low Risk

Additional groundwater monitoring wells are required to determine whether migration has or is occurring.

Contaminants: Chloroform 2.1 ug/L Tetrachloroethylene 2.2 ug/L Trichloroethylene (TCE) 18.0 ug/L

Groundwater: Medium Risk

Contamination in the groundwater has migrated over 500 feet beyond the edge of the source and there are no known barriers to contaminant migration. The potential exists of migration into the drinking water aquifer. Groundwater contamination has not yet impacted a production well or other beneficial source and is not expected to impact one within five years.

Contaminants: Trichloroethylene (TCE) 47.0 ug/L

Soil: Low Risk

Surface soil contamination can migrated to a point of exposure. Contamination in the bare topsoil is exposed to frequent high winds resulting in the inhalation of contaminated fugitive dust by receptors. There is no direct means for receptors to have access to surface soil contamination, however potential receptors are currently being evaluated.

Contaminants: 1,3-Xylene 0.233 mg/kg

Groundwater: Medium Risk

Groundwater monitoring investigations indicate that the contaminant plume has migrated greater than 100 feet beyond the edge of the source and there are no known barriers to contaminant migration. South Base water supply wells are located approximately 2-miles south of Site 14. Contamination is not expected to impact a beneficial source within five years. California EPA considers all groundwater to be a potential domestic or agricultural source.

Contaminants: Bis(2-Ethylhexyl)Phthalate 18.0 ug/L Iron 61.0 ug/L Nickel (soluble salts) 72.0 ug/L 4-Chloroaniline 74.0 ug/L Trichloroethylene (TCE) 200.0 ug/L

Soil: Medium Risk

Surface soil contamination has migrated to a point of exposure. Contamination in the bare topsoil is exposed to frequent high winds resulting in the inhalation of contaminated fugitive dust by receptors. Trainees periodically practice fire fighting techniques and drills in the area.

Contaminants: Cadmium and compounds 7.200000000000001e-07 mg/kg Methyl Chloride 7.2e-06 mg/kg Acetone 0.00012 mg/kg Antimony and compounds 0.0063 mg/kg Nickel (soluble salts) 0.019100000000000002 mg/kg

Groundwater: High Risk

Contaminants found in downgradient wells ranging from adjactent to source area to over 2500 feet from the source area. Groundwater underlying the site may be a recharge source for the Lancaster Groundwater Basin. 3 water supply wells are located approx. 2 miles south of the contaminant plume, however it is not known if the wells will be impacted within the next 5 years.

Contaminants: Chloroform 3.5 ug/L cis-1,2-Dichloroethylene 5.4 ug/L Tetrachloroethylene 10.0 ug/L Naphthalene 18.0 ug/L Trichloroethylene (TCE) 6700.0 ug/L