Naval Air Weapons Station China Lake

IRP Site 1 lies within the former Armitage Field Former Fuel Farm about 3 miles north of the City of Ridgecrest, in the southern portion of NAWS China Lake. The site was constructed in 1945. It is approximately 450 feet by 400 feet and is bordered by parking in the north, undeveloped desert to the east and south, and NAWS facilities to the west. The site included 13 dry wells that were approximately 10 feet deep, used to support operations at the fuel supply area. Aircraft fuels that did not meet military specifications, used engine oils, fuel tank condensate, and excess fuels were disposed of for approximately 40 years by discharging to the dry wells or by direct release to the ground surface. Releases to the dry wells and the surface may have included other liquid wastes such as solvents and degreasers. The historical disposal practices released free product to the subsurface at Armitage Field in the form of light nonaqueous phase liquids that float on the water table and dissolve into the groundwater. These disposal practices were discontinued in 1982 and the dry wells were removed in 1997.

Six underground storage tanks were present when the fuel farm was operating, including two 100,000-gallon and four 50,000-gallon underground storage tanks. Several types of fuel were stored in these tanks, including jet propellant-3, -4, and -5 and aviation gasoline 115/145 and 100/130. In addition, one 4,000-gallon tank was installed for waste oil. In 1997, the Navy closed the underground storage tanks in place and removed the associated piping, transfer stations, and filling stations.

The characteristics and contamination of groundwater and soil were investigated in a remedial investigation in 1998, and additional data were collected in support of the feasibility study in 2003 and 2005. These studies concluded that free product composed of jet propellant and total petroleum hydrocarbons was floating on the water table. The groundwater surrounding the free product was contaminated with volatile organic compounds, semivolatile organic compounds, and polycyclic aromatic hydrocarbons. Surface and subsurface soil was also found to be contaminated with volatile organic compounds and semivolatile organic compounds.

An underground storage tank corrective action plan completed in 2000 resulted in installation of a vacuum-enhanced skimming remedy. The risk assessment results in the 2007 record of decision concluded that soil and groundwater at IRP Site 1 do not pose an unacceptable risk, although the Navy established remedial action objective to remove the free product by continuing and expanding the vacuum-enhanced skimming remedy. The Navy also opted to conduct long-term monitoring and free product removal, both of which are ongoing. The current volume of total petroleum hydrocarbons the system removed is 46,505 gallons as of September 2018.

A draft remedial system evaluation report was submitted in August 2020 to address changes in the nature and extent of contamination at IRP Site 1. The remedial actions for IRP Site 1 and the other Armitage Field OU sites will continue to be evaluated in five-year reviews. The next five-year review is planned for 2022.

IRP Site 2 consisted of a concrete pad and associated drainage culverts and ditches. From 1945 to 1982, wash water and waste fuel drained from the concrete pad into an open ditch that connected to the storm water runoff system for the airfield and ultimately discharged to an open field east of the airfield. Approximately 10,000 to 20,000 gallons of wastewater containing chlorinated solvents (degreasers), industrial detergents, hydraulic fluid, lubricating oil, antifreeze, and jet fuels was discharged into the ditch on a daily basis when the site was in operation.

The characteristics and contamination of the groundwater at IRP Site 2 were investigated in a remedial investigation in 1998, as well in as the basewide hydrogeologic characterization and the groundwater monitoring program under the feasibility study for Armitage Field in 2003. These investigations indicate that groundwater contamination at IRP Site 2 primarily consists of a plume covering 9.9 acres of trichloroethene and tetrachloroethene, along with a few detections of compounds that result from degradation of these volatile organic compounds. The remedial investigation also indicated that surface and subsurface soil at IRP Site 2 contained low levels of volatile organic compounds and semivolatile organic compounds.

The risk assessment in the 2007 record of decision concluded that soil does not pose an unacceptable risk and that further action is not warranted, although a remedial action objective for groundwater was established at the Armitage Field OU to prevent exposure at IRP Site 2. Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022.

IRP Site 3 consists of a treatment plant, a sewage tank, and an unlined leach pond. The treatment plant and sewage tank are located south of Aircraft Range Access Road, and the leach pond is located north of the road. From 1950 to 1981, an estimated 17,000 gallons per day of sanitary and industrial waste was collected in the treatment plant, then discharged to the sewage tank for settlement and finally to the unlined leach pond through a 10-inch-diameter vitrified clay pipe. Most of the waste the system received was domestic sewage, except for about 500 gallons per day of wastewater that contained low concentrations of solvents, detergents, oil, and grease discharged to the sanitary sewer.

A site inspection was completed in 2002. Volatile organic compounds, semivolatile organic compounds, and metals were detected in groundwater but did not exceed maximum contaminant levels. The risk assessment in the 2007 record of decision concluded that soil does not pose an unacceptable risk and that further action is not warranted, although a remedial action objective for groundwater was established at the Armitage Field OU to prevent exposure at IRP Site 3. Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022. An additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 44 is located about 2,500 feet east of the aircraft runways at Armitage Field. From 1945 to 1988, the old firefighting training area pad in the southwestern portion of the site was used as a practice facility for fighting petroleum fires. Unburned gasoline, jet propellent 5, and water would evaporate or flow off the pad and percolate into the surrounding soil. A new pad was installed in 1988 that included containment berms and an oil-water separator to eliminate releases to the soil, and the old IRP Site 44 pad was decommissioned. The new pad is regulated under the Regional Water Quality Control Board’s compliance program for waste discharges to land, which includes a set of waste discharge requirements and groundwater monitoring.

IRP Site 44 also encompasses Point of Interest 197, call the “Water Road Fuel Dump” located 750 feet east of the old firefighting training area. Based on site records and aerial photographs, fuels may have been released at Point of Interest 197 in the 1960s and 1970s.

The characteristics and contamination of groundwater and soil at IRP Site 44 and Point of Interest 197 were investigated in a phase I and phase II remedial investigation completed in 1998 and 2002, as well as the basewide hydrogeologic characterization and groundwater monitoring program as part of the feasibility study in 2003. It was concluded that IRP Site 44 was contaminated with plumes of free product and dissolved-phase total petroleum hydrocarbons that appear to be associated with Point of Interest 197. The remedial investigation also indicated that surface soil was contaminated with semivolatile organic compounds and subsurface soil with total petroleum hydrocarbons.

The risk assessment results in the 2007 record of decision concluded that soil and groundwater at IRP Site 44 and Point of Interest 197 do not pose an unacceptable risk, although the Navy established a remedial action objective for groundwater to remove the free product in the area. Additionally, benzene was identified as a contaminant for groundwater at IRP Site 44. Optimization of the recovery system is ongoing. A draft remedial system evaluation report was submitted in August 2020 to address changes in the nature and extent of contamination at IRP Site 44.

Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022. An additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 45 is located on the northeastern side of the aircraft runways at Armitage Field. IRP Site 45 services ground support equipment and vehicles. Typical activities included routine vehicle maintenance, such as changing oil, brake fluid, and antifreeze, and adding hydraulic oil. From 1945 to 1981, water and other runoff were directed into a tributary of an unlined shallow ditch, with another unlined ditch draining from the aircraft cleaning area. Past activities at the nearby Naval Air Facility Gas Station, south and southwest of the site, may also have contributed to groundwater contamination in the area.

The characteristics and contamination of groundwater and soil at IRP Site 45 were investigated in a phase I and phase II remedial investigation completed in 1996 and 2002, as well as the basewide hydrogeologic characterization and groundwater monitoring program as part of the feasibility study in 2003. These investigations concluded that chlorinated volatile organic compounds are present in groundwater beneath the site. The remedial investigation also indicated that surface soil was contaminated with polycyclic aromatic hydrocarbons at the site.

The risk assessment in the 2007 record of decision concluded that remedial action for the polycyclic aromatic hydrocarbons in surface soil was needed. At the Armitage Field OU, a remedial action objective for groundwater was established to prevent exposure at IRP Site 45.

In 2013, the polycyclic aromatic hydrocarbons contamination was removed from surface soil through remedial action. Because no contaminants of concern remain in soil, no further action is required for soil. Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022.

IRP Site 50 consists of a trench that measures 20 feet wide by 300 feet long adjacent to IRP Site 3. From the mid-1960s to the mid-1970s, waste engine oil from propeller-driven aircrafts was disposed of in this trench. The used oil may have contained heavy metals and polycyclic aromatic hydrocarbons. Liquid and dried waste oil were observed on the surface of the trench in July 1999 during a site inspection.

The Navy completed a removal action for soil at IRP Site 50 in 1999 and a site inspection in 2002. The soils subject to the removal action at IRP Site 50 were contaminated with total petroleum hydrocarbons and polycyclic aromatic hydrocarbons. An extended site inspection completed in 2002 did not find any additional soil contamination but did detect volatile organic compounds, semivolatile organic compounds, and metals in groundwater associated with IRP Site 50. The volatile organic and semivolatile organic compounds detected did not exceed maximum concentration limits, and the metals appeared to be a result of the sampling method used during the investigation.

The 2007 record of decision for IRP Site 50 was published in required no further action for soil. Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022.

IRP Site 58 is currently used as an office and training room. The site also includes several storage sheds, oil drip pans, two portable waste oil containers (bowsers), and a hazardous material storage locker. The site is 160 feet by 120 feet and is located near the runways, northwest of the hangar area. The storage area was used to store engine oil (used and unused), aviation fuel samples, hydraulic fluid, flight line cleaners, and solvents. The sites storage area was also used as a maintenance area for the VX-5 squadron starting in approximately 1956. The area is covered primarily with asphalt and, to a lesser extent, concrete. IRP Site 58 was repaved in 2006.

IRP Site 58 was subject to a removal site evaluation completed in 2000. The investigation concluded there were no chemicals of concern or chemicals of ecological concern at the site for soil or groundwater. The 2007 record of decision further concluded that soil does not pose an unacceptable risk and that further action is not warranted, although a remedial action objective for groundwater was established at the Armitage Field OU to prevent exposure at IRP Site 58. No further action is required for soil. Monitored natural attenuation and institutional controls are in place and functioning as part of the Armitage Field OU groundwater remedy. The fourth five-year review is planned for 2022.

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IRP Site 15 consists of an abandoned on-site wastewater treatment and disposal system that was used to dispose of wastewater from buildings and test sites at the R Range complex. From 1950 until 1984, the R Range leach field at IRP Site 15 received most of the individual and sanitary wastewater from facilities within the R Range complex. Activities at R Range facilities that generated wastewater included cooling tower blowdown, photographic laboratory operations, and operations at various fuze and explosives research laboratories and associated machining shops. In addition, rinse water from activities at the static firing-rocket test stands at IRP Site 56 in the R Range complex was conveyed to the R Range leach field. In 1984, the R Range leach field and the tile leach field were abandoned, and all sanitary and industrial waste was routed to the sanitary sewer parallel to Pole Line Road.

During the 2002 remedial investigation, chlorinated solvents were identified as chemicals of concern in groundwater; no chemicals of concern were identified for soil. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 15.

The anticipated completion date for the data gaps investigation is 2021, followed by completion of the feasibility study addendum in 2022 and the record of decision in 2023. Additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 51 is located on the eastern site of Pole Line Road across the street from IRP Sites 15 and 55. The site previously included an old and newer vehicle maintenance ramp, debris piles, disposal trenches, a former inert materials storage building, a bomb disposal building, and a hazardous materials storage pad. The bomb disposal building, and an inert storage building were constructed in 1945. The hazardous materials storage pad was built between 1949 and 1954. Drums of sodium hydroxide, acetone, and toluene were reportedly stored on the pad. Explosive ordnance disposal personnel contractors used the bomb disposal area from the 1960s through the 1970s for cleaning, disassembling, and deactivating missile, rocket, and torpedo warheads and other explosives. Wastewater drained from the bomb disposal and inert storage buildings discharged to an open ditch and was diverted through a culvert to the North Ditch to IRP Site 15. Waste lines were later connected to the sanitary sewer that was installed along Pole Line Road in 1984.

Risk evaluations from a 2000 removal site evaluation, identified no chemicals of concern for soil or groundwater. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 51.

The anticipated completion date for the data gaps investigation is 2021, followed by completion of the feasibility study addendum in 2022 and the record of decision in 2023.

IRP Site 55 previously contained a 500-gallon solvent rinse tank and a tile leach field in the larger footprint of IRP Site 15. The solvent rinse tank, removed in 1991, was a 500-gallon underground storage tank. IRP Site 55 is entirely within the area of IRP Site 15 and includes a tile leach field that appears to have received effluent associated with solvent rinsing and cleaning. This tile leach field, used from approximately 1952 until 1984, received wastewater from other R Range facilities as well. No records were located to indicate the nature of the industrial wastes discharged to the tank and leach field; however, the waste stream may have included dilute concentrations of solvents.

During the 2002 remedial investigation, chlorinated solvents were identified as chemicals of concern in groundwater; no chemicals of concern or chemicals of environmental concern were identified for soil. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 55.

The anticipated completion date for the data gaps investigation is 2021, followed by completion of the feasibility study addendum in 2022 and the record of decision in 2023.

IRP Site 56 is located in the main complex of the Area R buildings. The site consists of three test stands used to test liquid-propellant rockets. The primary reason for investigating this site was the use and spillage of mercury near one of the test stands. Acids, solvents, and bleaches were reportedly also used at the facilities.

Risk assessments from a 2000 removal site evaluation as well as the subsequent feasibility study at the Area R OU identified no chemicals of concern for soil or groundwater. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 56.

The anticipated completion date for the data gaps investigation is 2021, followed by completion of the feasibility study addendum in 2022 and the record of decision in 2023. Additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 57 is a pit located just south of Water Road and west of Pole Line Road. The site was constructed in 1966, when it was excavated for fill material used in construction of the Warhead Research Laboratory. The pit was later used to dispose of construction debris, including asphalt, concrete, scrap wood, and metal. Investigations have confirmed that only inert wastes were disposed of at the site.

No chemicals of concern were identified for soil or groundwater during the 1997 preliminary assessment. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 57.

The anticipated completion date for the data gaps investigation is 2021, followed by completion of the feasibility study addendum in 2022 and the record of decision in 2023.

IRP Site 64 includes an original leach field, a newer tile leach field and overlying evaporation pond, and an acid waste line. From 1953 until 1969, a single 1,000-gallon septic tank and the original leach field received sanitary and industrial wastes from the Human Factors Laboratory as well as wastewater. In 1969, the septic tank and original leach field associated with the laboratory were abandoned, and a new tile leach field and acid waste line were constructed. A shallow evaporation pond overlies the new tile leach field. In 1984, the facilities served by the evaporation pond and leach field were connected to the main wastewater treatment system at NAWS China Lake. The evaporation pond and leach field were abandoned in place and are currently inactive.

During the 2002 remedial investigation, dioxins and furans were identified as chemicals of concern for soil; no chemicals of concern were identified for groundwater. Groundwater monitoring will continue at the Area R OU and a data gaps investigation will be completed that may include IRP Site 64.

The anticipated completion date for the data gaps investigation is 2021. The feasibility study addendum is anticipated to be completed in 2022 and the record of decision in 2023.

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IRP Site 8 consists of a series of natural and man-made drainages that traverse the hillside of the Propulsion Laboratory Operable Unit. From 1946 to 1981, wastewater from laboratory buildings was discharged through solid separation systems to the IRP Site 8 drainages. The wastewater reportedly contained TNT, plastic bonded explosives, and pressed projectile explosives. Approximately 14,000 gallons of wastewater were discharged to the IRP Site 8 drainage channels each day. In 1981, the drainage channels were replaced with the 21 clay-lined evaporation ponds that constitute IRP Site 49.

Explosives were identified as chemicals of concern for soil in the 2006 remedial investigation report, and tetrachloroethylene and chloroform were identified as chemicals of concern for groundwater at IRP Site 8. A removal action that included IRP Site 8 was completed in 2016. Approximately 7,025 cubic yards of contaminated soil (primarily explosive residues) was removed from six Propulsion Laboratory Operable Unit sites and held at IRP Site 6. Confirmation sampling data from the removal action showed some results above removal action goals.

A work plan for a data gaps investigation, expected to finish in 2021, is being prepared to further assess contamination at the site. In addition, a natural degradation study will be completed in 2020 that will evaluate the contribution of natural abiotic or biotic processes in reducing volatile organic compounds and explosives concentrations in groundwater. Groundwater monitoring at the site is ongoing. The record of decision is anticipated to be available before the end of 2023.

IRP Site 11 consists of a single evaporation pond that received wastewater discharge from a building used to manufacture solid and aerosol propellants and explosives. The unlined evaporation pond was replaced by a clay-lined pond in 1981. This pond was subsequently removed as part of the overall IRP Site 49 removal action.

One type of explosive was identified as a chemical of concern for soil during the 2006 remedial investigation. Groundwater is not present within the unconsolidated soils at IRP Site 11 and no chemicals of environmental concern were identified for the site. A removal action that included IRP Site 8 was completed in 2016. Approximately 7,025 cubic yards of contaminated soil inclusive primarily of explosive residues was removed from six Propulsion Laboratory Operable Unit sites and held at IRP Site 6. Confirmation sampling data from the removal action showed some results above removal action goals.

A work plan for a data gaps investigation, expected to finish in 2021, is being prepared to further assess contamination at the site. In addition, a natural degradation study will be completed in 2020. The record of decision is anticipated to be available before the end of 2023.

IRP Site 46 consists of a drainage that leads away from a currently active fenced area formerly used for cleaning rocket motor casings, a solvent storage shed, and a tank shed. The cleaning facility consisted of two solvent tanks, a concrete drying pad, a solvent storage shed, and two sumps. The drainage that is IRP Site 46 leads east away from the Dunkit facility and historically received discharge of solvent rinse water directly to the ground surface. Rocket motor casings were cleaned at the Dunkit facility starting in 1971. In 1989, the Navy began collecting spent solvents and rinse water in a tank for disposal as hazardous waste.

Chromium and cadmium were identified as chemicals of concern for soil in the 2006 remedial investigation and trichloroethylene was identified as a chemical of concern for groundwater at IRP Site 46. A removal action that included IRP Site 8 was completed in 2016. Approximately 7,025 cubic yards of contaminated soil (primarily explosive residues) was removed from six Propulsion Laboratory Operable Unit sites and held at IRP Site 6. Confirmation sampling data from the removal action showed some results above removal action goals.

A work plan for a data gaps investigation, expected to finish in 2021, is being prepared to further assess contamination at the site. In addition, a natural degradation study is being conducted to evaluate the contribution of natural abiotic or biotic processes in reducing contaminant concentrations in groundwater. Groundwater monitoring at the site is ongoing. The record of decision is anticipated to be available before the end of 2023.

IRP Site 49 consists of numerous surface impoundments spread over the western portion of Salt Wells Valley. From 1946 to 1981, industrial wastewater from laboratories was discharged to open drainage channels that are now designated as IRP Site 8. The open channels were replaced in 1981 with 22 clay-lined ponds designed to collect discharged wastewater. These ponds constitute IRP Site 49. No significant releases were ever documented at the site; however, monthly inspections of the leak detection system in the mid- 1980s revealed that many of the ponds were beginning to leak through the clay liners. As a result, seven of the ponds were reconstructed with a double-layered synthetic liner.

The explosives RDX and TNT were identified as chemicals of concern for soil in the 2006 remedial investigation report, and tetrachloroethylene and chloroform were identified as chemicals of concern for groundwater at IRP Site 49. A removal action that included IRP Site 8 was completed in 2016. Approximately 7,025 cubic yards of contaminated soil (primarily explosive residues) was removed from six Propulsion Laboratory Operable Unit sites and held at IRP Site 6. Confirmation sampling data from the removal action showed some results above removal action goals.

A work plan for a data gaps investigation, expected to finish in 2021, is being prepared to further assess contamination at the site. In addition, a natural degradation study will be completed in 2020. Groundwater monitoring at the site is ongoing. The record of decision is anticipated to be available before the end of 2023.

AOC 79 is located in the Salt Wells Valley, adjacent to a laboratory. AOC 79 consists of a discharge pit adjacent to Buildings 10633 and 10630. A buried metal discharge pipe enters the pit from the south. Historical activities that may have discharged wastewater to this pit are unknown; however, the laboratory was used for mixing and testing explosives in the past.

Analytes that were detected in soil during the remedial investigation include explosive compounds, perchlorate, zinc, and chromium. A removal action that included IRP Site 8 was completed in 2016. Approximately 7,025 cubic yards of contaminated soil (primarily explosive residues) was removed from six Propulsion Laboratory Operable Unit sites and held at IRP Site 6. Confirmation sampling data from the removal action showed some results above removal action goals.

A work plan for a data gaps investigation, expected to finish in 2021, is being prepared to further assess contamination at the site. In addition, a natural degradation study will be completed in 2020. Groundwater monitoring at the site is ongoing. The record of decision is anticipated to be available before the end of 2023.

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IRP Site 7 is located on the northern side of the Michelson Laboratory building. The site consists of two unlined ditches that received liquid wastewater from Michelson Laboratory from 1947 to 1980 via an industrial waste collection system. The estimated maximum flow of the west ditch was 62,000 gallons per day of wastewater containing dilute concentrations of acids, bases, heavy metals, cyanides, photo-processing chemicals, and solvents. The estimated maximum flow of the eastern ditch was 9,400 gallons per day of cooling water containing acids, algaecides, and possibly perchlorate. The total volume of wastewater disposed of into the ditches is unknown.

Metals, pesticides, and polychlorinated biphenyls were identified as chemicals of concern for soil in the remedial investigation report, and volatile organic compounds were identified as chemicals of concern for groundwater at IRP Site 7. The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010.

A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023. Additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 13 consists of two former unlined trenches that received waste oils from 1965 to 1980. Waste oils possibly included motor oils, solvents, and grease from grease traps at NAWS China Lake cafeterias. An estimated 10,000 gallons of waste were disposed of into the trenches during the 15 years that the site was in operation. The trenches were filled in and operations ceased at the site in 1980.

After initial investigations, including a phase I remedial investigation, the trenches were subsequently excavated and backfilled with clean soils during a removal action in 1999. Confirmation soil sampling confirmed that the removal objectives had been met. Evaluation of the site continued after the removal action was completed. A soil removal action was conducted at IRP Site 13 in 2000 to remove waste oil sludge and associated soil.

Polychlorinated biphenyls were identified as chemicals of environmental concern for soil, and vinyl chloride was identified as a contaminant of concern for groundwater at IRP Site 13 in the revised draft feasibility study. The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010.

A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023.

IRP Site 33 consists of four dry wells that received battery acid waste from laboratory auxiliary power rooms from the late 1950s to the 1970s. Research for the initial assessment study did not indicate use of the wells for any other purpose or chemicals. As part of a site reconnaissance in September 1996, the historical plumbing plan for the Michelson Laboratory foundation was reviewed. According to the plans, three darkroom drains, along with auxiliary power room sumps, are connected to individual dry wells that were referenced in the initial study. A fourth dry well shows no connections.

No chemicals of concern or chemicals of environmental concern were identified for soil or groundwater by risk assessments during the remedial investigation. The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010.

A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023.

IRP Site 47 includes the former industrial sewer system, associated lateral piping, leach lines and sumps, and two former industrial wastewater ponds. The public works compound typically contributed dilute mixtures of oil and grease, heavy metals, vehicle wash water, and battery acids to the industrial sewer system. The Michelson Laboratory complex effluent included dilute mixtures of acids, bases, heavy metals, solvents, plating solutions, photographic and circuit-board chemicals, and cooling waters.

Three metals, two pesticides, and polychlorinated biphenyls were identified as chemicals of concern or chemicals of environmental concern for soil, and three volatile organic compounds were identified as chemicals of concern in the 2010 remedial investigation report for groundwater at IRP Site 47.

A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023. Additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 68 was used from 1979 to 1990 to store transformers from throughout NAWS China Lake and nearby complexes. The Public Works Transformer Storage Pit typically held 15 to 20 transformers. Excess transformers were stored north of the pit in the area now known as the New Transformer Storage Yard. Until 1984, transformers were set directly on the ground in the unlined Public Works Transformer Storage Pit. Navy-constructed containment devices (drip pans) were used from 1984 to 1988. Commercial drip pans were used starting in 1988. In 1990, the Public Works Transformer Storage Pit was excavated and partially backfilled. A soil removal action was conducted at IRP Site 68 in 2012. The action removed polychlorinated biphenyl-contaminated soil.

A specific polychlorinated biphenyl was identified as a chemical of concern in the contamination assessment and revised draft feasibility study reports; no chemicals of concern were identified for groundwater.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023.

IRP Site 69 is located on the eastern side of the Public Works compound and contains the Public Works Vehicle Paint Shop, which is currently active. The drainage basin collects surface runoff from the paint shop. The paint shop was built in 1951 and is operated by the Public Works Department. Historical or current activities at the paint shop include painting Navy vehicles, rockets, missile launchers, missiles, and other large equipment. Painting reportedly involved the use of lead- and titanium-based paints, phosphorescent paints, thinners, and solvents. Disposal of materials at the paint shop may have contaminated nearby surface soils and the drainage catch basin across the street. The Hazardous Waste Site Transfer Facility at NAWS China Lake reportedly began to collect waste solvents, thinners, and paint from the facility in 1985. These materials are currently disposed of by an approved waste disposal company. The drainage catch basin reportedly was used for waste disposal prior to 1977. A 55-gallon drum was kept at the paint shop to store waste thinners and unused paint. This drum was reportedly routinely dumped in the catch basin.

No chemicals of concern or chemicals of environmental concern were identified for soil or groundwater by risk assessments during the remedial investigation.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021, followed by the record of decision in 2022 or 2023.

IRP Site 70 is located in the western portion of the Public Works compound and consists of a concrete pad and dry well constructed in 1968. The pad was used to steam-clean tanker trucks and other large equipment; fluids generated during the steam cleaning drained to the dry well. The dry well was used for approximately 7 years, from 1968 until at least 1975. The dry well is no longer active, and the area is currently being used as a parking lot and cable storage area.

Volatile organic compounds and semivolatile organic compounds were identified as chemicals of concern for soil in the remedial investigation report, and volatile organic compounds and the semivolatile organic compound naphthalene were identified as chemicals of concern for groundwater at IRP Site 70. No chemicals of environmental concern were identified by the remedial investigation ecological risk assessments. A pilot study was conducted to evaluate the effectiveness of soil vapor extraction at IRP Site 70 from 2005 to 2006. Accelerated site characterization programs were implemented in 2004 and 2007 to 2008 at IRP Site 70 to further delineate free product and related fuel contamination in soil and groundwater.

Free product has periodically been removed from IRP Site 70 monitoring wells since 2006. Semi-annual groundwater monitoring has also been performed at eight IRP Site 70 wells in 2012 and 2013. These monitoring events have demonstrated that the light nonaqueous phase liquid and dissolved total petroleum hydrocarbon plumes at the site are stable or declining and have further found aerobic conditions in groundwater that are conducive to natural degradation of hydrocarbons.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021. The record of decision is anticipated in 2022 or 2023.

IRP Site 71 is located in the northwestern quarter of the Public Works compound and consists of a storage area near the repair shop where oils, antifreeze, and solvents were reportedly stored in drums before the early 1980s. Currently, the site is paved and used as a parking area for large vehicles.

Volatile organic compounds and semivolatile organic compounds in soil and volatile organic compounds and one semivolatile organic compound were identified as chemicals of concern for groundwater at IRP Site 70. No chemicals of environmental concern were identified by the remedial investigation ecological risk assessments.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021. The record of decision is anticipated in 2022 or 2023.

IRP Site 72 includes the Railroad Engine House and the areas near the facility that were associated with service of the trains until approximately 1980. It was used as a service facility for train engines, where routine maintenance involved draining fluids such as used oil through a floor drain to a dry well. It was also reportedly used to store transformers. File searches conducted during the 1996 preliminary assessment showed that NAWS China Lake owned two diesel electric train engines in the past. During initial site visits, the oil pit was observed to be heavily stained, and other oil spills were observed.

The pesticide Aldrin was identified as a chemical of concern for soil in the remedial investigation report. No chemicals of concern have been identified for groundwater, and no chemicals of environmental concern were identified by the ecological risk assessments.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021. The record of decision is anticipated in 2022 or 2023.

AOC 234 is located in the southern portion of the main base adjacent to Michelson Laboratory. The site was a vehicle maintenance and service station. Archived photographs show the maintenance building and service pit in operation in the 1940s during construction of Michelson Laboratory. The cement slab for the maintenance building is still in place. A service station was previously located at AOC 234; however, there is no evidence of a gas pump island or an underground storage tank.

Total petroleum hydrocarbons and arsenic were identified as chemicals of potential concern for soil in the preliminary assessment report, and volatile organic compounds and metals were identified as chemicals of potential concern for groundwater at AOC 234.

The remedial investigation for the Michelson Laboratory/Public Works Operable Unit was finalized in 2010. A draft feasibility study was prepared in 2008, with a revised draft delivered for agency review in May 2014. A draft final feasibility study was prepared in 2018 but was not accepted based on what was considered an insufficient amount of data. A data gaps investigation is anticipated to be completed in 2021. The record of decision is anticipated in 2022 or 2023.

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IRP Site 9 is located in Salt Wells Valley, east of the Propulsion Laboratory Operable Unit. The site encompasses a 10-acre area where reports state that an estimated 300 cubic yards of waste asbestos-containing material generated at NAWS China Lake was disposed of in three slit trenches from 1979 to 1981. Some of the asbestos-containing material was reportedly discarded in plastic bags, although much of it was reported to have been loose when it was buried.

Arsenic, chromium, and lead were identified as chemicals of concern for soil in the 2004 remedial investigation report, and hexavalent chromium and heptachlor epoxide were identified as chemicals of concern for groundwater at IRP Site 9/10. Additional investigation was completed as part of the 2018 remedial investigation addendum at IRP Site 9 and 10 to accomplish the following: confirm that there were no releases of contaminants to groundwater, provide a more current groundwater dataset, update the previous human health risk assessment, and update previous environmental risk assessments.

Based on the results of the remedial investigation addendum, one additional round of groundwater monitoring was recommended to further evaluate whether concentrations of organic and inorganic compounds in IRP Site 9/10 groundwater are remaining stable or are decreasing. An evaluation of the existing soil cover at both sites was also recommended. Finally, an evaluation and potential removal action was recommended for any surface bulk waste debris at IRP Site 9/10 that is found to contain asbestos.

Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend future actions.

IRP Site 10 is located in Salt Wells Valley, east of the Propulsion Laboratory Operable Unit. The site consists of 10 trenches adjacent to IRP Site 9. From 1960 to 1980, these trenches reportedly received solid wastes as well as some liquid waste from nearby propulsion laboratories.

Arsenic, chromium, and lead were identified as chemicals of concern for soil, and hexavalent chromium and heptachlor epoxide were identified as chemicals of concern for groundwater at IRP Site 9/10. Additional investigation was completed as part of the 2018 remedial investigation addendum at IRP Site 9 and 10 to confirm that there were no releases of contaminants to groundwater, provide a more current groundwater set, and update the previous human health risk assessment and environmental risk assessments.

Based on the results of the remedial investigation addendum, one additional round of groundwater monitoring was recommended to further evaluate whether concentrations of organic and inorganic compounds in IRP Site 9/10 groundwater are remaining stable or are decreasing. An evaluation of the existing soil cover at both sites was also recommended. Finally, an evaluation and potential removal action was recommended for any surface bulk waste debris at IRP Site 9/10 that is found to contain asbestos.

Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend future actions.

IRP Site 19 is located in the northwestern portion of the China Lake Complex in the Indian Wells Valley. The site was an open disposal site from 1944 to 1983 and reportedly received approximately 3,000 cubic yards of solid waste before it was subsequently covered by soil. No hazardous waste disposal was documented at the site.

No chemicals of potential concern were identified in soil or groundwater during the 2006 preliminary assessment and 2012 site inspection. A work plan is being generated for a data gaps study.

Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend future investigations and actions under CERCLA.

IRP Site 20 is located in the Division 36 area of the central China Lake Complex in the Indian Wells Valley. The site was used from 1960 to 1979 for disposal of range and inert ordnance wastes, which were reportedly buried in two trenches. The total volume was estimated to be 600 cubic yards. The locations of the two trenches were never verified during subsequent site visits.

No chemicals of potential concern were identified in soil during the 2006 preliminary assessment and 2012 site inspection. Groundwater at the site was too deep to be evaluated. A geophysical investigation was completed at the site, and the results indicated that no further delineation was required.

IRP Site 20 was removed from the Landfill Operable Unit plans for further investigation based on the results of the geophysical investigation. The Navy will be pursuing no further action based on previous investigations indicating no burial of waste at the site.

IRP Site 21 is located in the CT-4 area in Salt Wells Valley at the end of the CT access road. The site consists of a trench that received approximately 2,000 cubic yards of waste between 1956 and 1979. The disposal area was closed in 1979, all waste was removed, and the area was re-graded. The NAWS China Lake Explosive Ordnance Disposal detachment inspected the material as it was removed. Reports of hazardous material disposal could not be corroborated. During site visits in 1996 and 1999, IRP Site 21 appeared free of debris, and no evidence of hazardous materials was found.

No chemicals of potential concern were identified in soil by the 2002 preliminary assessment. While groundwater was not evaluated, previous data do not confirm that it is even present below the site.

Previous investigations concluded that no further action was warranted at the site because all disposed waste was removed in 1979. No further action was recommended for IRP Site 21 in the 2015 basis for no further action determination report and agency concurrence was received in February 2015. Additional investigation will be completed in 2021 in accordance with the basewide per- and polyfluoroalkyl substances site inspection.

IRP Site 22 is located in the southeastern portion of the China Lake Complex in the Indian Wells Valley. The site was a landfill that received most of the household wastes generated by on-base housing, and small amounts of industrial material, from 1944 to 1965.

No chemicals of concern were identified for soil or groundwater by risk assessments included in the 1996 and 2000 remedial investigations. A data gaps investigation concluded that reduced frequency or reduced monitoring may be pursued based on the lack of site impacts over the last 50 years. Before any monitoring occurs, replacement of dry wells may be necessary because of declining groundwater levels.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend future, additional CERCLA actions.

IRP Site 23 is located in the south-central portion of the China Lake Complex in the Indian Wells Valley, along North Knox Road, south of the Aircraft Survivability area. The site consists of three trenches that received range waste from 1950 until 1981. Unopened 1- and 5-gallon cans of chlordane were reportedly received at this site. Navy personnel interviewed during a 1996 site reconnaissance confirmed that some of the chlordane in the 1- and 5-gallon containers had been placed at IRP Site 23.

Based on the 2006 preliminary assessment and 2012 site inspection report, arsenic, chromium, and polychlorinated biphenyls were identified as chemicals of potential concern for soil, and trichloroethylene was identified as a chemical of potential concern for groundwater. A 2018 data gaps investigation confirmed chlorinated solvent concentrations at the site, indicating a low-level release to groundwater that may require further evaluation and delineation.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 24 is located in the K-2 Range in the northeastern portion of the China Lake Complex, east of the Aircraft Survivability area within the Indian Wells Valley. The site consists of two trenches excavated in a natural drainage that received range waste from 1950 to 1981. Previous reports indicated that at least several 1- and 5-gallon cans of chlordane were emplaced at this site and others in the 1970s. The site received an estimated 500 to 1,000 cubic yards of waste. No chemicals of potential concern were identified for soil by the 2006 preliminary assessment and 2012 site inspection. Groundwater was not evaluated since it is not likely present at the site based on the shallow bedrock nearby. A geophysical investigation at the site found no features that warrant further delineation.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend future, additional CERCLA actions.

IRP Site 25 is located in the G-2 Range in the southern portion of the China Lake Complex, east of G-2 Tower Road within the Indian Wells Valley. The site consists of three trenches that received inert range waste from 1944 to 1958 and is also referred to as AOC 241. An estimated 600 cubic yards of waste were disposed of at the site. No chemicals of potential concern were identified for soil or groundwater by the 2006 preliminary assessment and 2012 site inspection. An ecological risk screening has not yet been completed. A geophysical investigation at the site found no features that warrant further delineation.

The Navy is conducting more work in the area as part of the larger AOC 241. The site is also being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 26 is located in the southern portion of the China Lake Complex south of George Road within the Indian Wells Valley. The site, also known as Point of Interest 110, consists of two trenches that received an estimated 500 cubic yards of inert range waste from 1950 to 1979. No chemicals of potential concern were identified for soil or groundwater by the 2006 preliminary assessment and 2012 site inspection. An ecological risk screening has not yet been performed.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 27 is located northwest of Armitage Field in the Indian Wells Valley. The site is an inactive landfill that received an estimated 2,000 cubic yards of waste materials in five slit trenches between 1945 and 1978. No chemicals of potential concern were identified for groundwater by the site inspection, and soil was assessed not to be of concern because the wastes are buried. Volatile organic compounds and helium were identified as chemicals of potential concern in soil vapor at the site.

The Navy is conducting a site inspection for IRP Site 27, which will summarize the results of surface soil and groundwater sampling and analysis completed in April 2015 and soil gas and groundwater sampling and analysis completed in July 2017. Additional data collection was recommended based on the results of the site inspection.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 29 is situated within the Indian Wells Valley in the northwestern portion of the China Lake Complex. The site is a disposal area where ordnance and other materials were buried from the early 1950s through the late 1970s. Initial investigations documented a possible one-time disposal of chlordane and lead-based paint, although this was not confirmed by subsequent investigations. A 2018 focused feasibility study identified cadmium, lead, and radionuclides as chemicals of concern for soil but identified no chemicals of concern for groundwater.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future, CERCLA actions.

IRP Site 30 is located within the Indian Wells Valley in the southern-central portion of the China Lake Complex. The site is an ordnance landfill thought to have received inert and live ordnance waste from 1950 to 1979. The site contains an area of noticeable disturbance, which is surrounded by signs indicating burial of ordnance. The volume or type of ordnance could not be identified. No chemicals of potential concern were identified for soil or groundwater at IRP Site 30 by the 2006 preliminary assessment and 2012 site inspection.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 34 is a disposal area located east of North Lauritsen Road in the Indian Wells Valley. The site is a relatively large landfill that received solid and liquid wastes from 1944 to 1955. An estimated 2,000 cubic yards of material were disposed of at the site.

Arsenic and manganese were identified as chemicals of potential concern for soil; hexavalent chromium, metals, volatile organic compounds, and one semivolatile organic compound were identified as chemicals of potential concern for groundwater; and chloroform and trichloroethylene were identified as chemicals of potential concern for soil vapor. A geophysical survey was conducted in December 2018 with the goal of delineating the disposal trenches at the site. The results of the survey conclusively identified a significant number of disposal trenches either fully or partially covered.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 37 is located south and east of the golf course and south of Knox Road in the Indian Wells Valley. The site was used from 1945 to 1964 for disposal of general refuse, construction waste, and demolition debris. The 2004 remedial investigation confirmed that waste was primarily dumped on the surface of the ground and was not placed in trenches or buried. An estimated 1,200 cubic yards of waste were deposited in the landfill. No chemicals of concern were identified for soil or groundwater in the 2018 remedial investigation addendum.

The combined remedial investigation and remedial investigation addendum concluded that IRP Site 37 should no longer be considered a landfill because no burial of waste was observed. The geophysical survey did not identify disposal trenches, all waste appears to be limited to surface piles, and some of the construction debris exposed at the surface contains asbestos. There is no indication of a release of contaminants to surface soil, subsurface soil, or groundwater.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 40 is located approximately 1 mile north of the main administration buildings for the Randsburg Wash/Mojave B Complex. The site consists of three open trenches where solid waste from Randsburg Wash operations were reportedly buried from 1950 to 1975. Materials disposed of in the trenches consisted primarily of inert ordnance and range wastes. No chemicals of potential concern were identified for soil by the 2012 site inspection, and groundwater was not evaluated because it is expected to be very deep.

A geophysical survey was conducted between December 2018 and January 2019 that showed that the largest trench, which was partially open, also contains more areas of adjacent buried waste. The survey also found a second area of disposal south of the open trench.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will provide recommendations for future, additional CERCLA actions.

IRP Site 41 is located in Randsburg Wash, north of the main administration buildings. The site contains a trench where waste was reportedly buried in the 1950s and 1960s. The total quantities of waste oil and solvents disposed of were estimated to be 2,000 to 3,000 gallons each.

No chemicals of concern were identified in the 2004 remedial investigation. An attempt was made to install one monitoring well, but no groundwater was encountered to a depth of 275 feet below ground surface, and the borehole was abandoned. The remedial investigation concluded that reports of waste disposal in prior reports for IRP Site 41 were not accurate. Rather, it concluded that these wastes were disposed of in a nearby trench at AOC 154.

A no further action status was finalized in December 2014, and therefore IRP Site 41 is considered closed. Further action is being conducted at AOC 154.

IRP Site 67, the Lane Haven Dump, is located outside of the main China Lake Complex in the Indian Wells Valley. The site was used to dispose of trash from the Lane Haven Trailer Court from 1964 to 1981. The Navy acquired the property in 1981, and the dump may have been used later to dispose of drums of oil. The pit is uncovered, and interviews revealed that unauthorized dumping at the site had been an ongoing problem because the area was unsecured and readily accessible.

No evidence of drum disposal was found on the site during a 2000 site visit. No chemicals of potential concern were identified for soil during the 2012 site inspection. Groundwater was not investigated since it is expected to occur at a depth greater than 250 feet below ground surface. A geophysical survey was conducted in December 2018 with the goal of confirming that the dump was removed or to locate its actual location. The results of the survey showed no areas of significant burial at the site that would indicate a waste disposal trench or dump.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

IRP Site 84 is located in the Salt Wells Valley east of the Propulsion Laboratory. The site is not well documented historically, but it is believed that the area was used to stage and then burn waste materials from explosive tests. The operating dates are unknown. It was originally investigated in July 2003 as part of the remedial investigation conducted at the Propulsion Laboratory Operable Unit. It was subsequently moved to the AOC program for additional studies. Based on the results of the additional work, the Navy converted AOC 235 into IRP Site 84.

During the 2018 site inspection, metals in soil and hexavalent chromium, chlorinated solvents, and molybdenum in groundwater were identified as chemicals of potential concern. The site inspection concluded that further evaluation in the form of an additional remedial investigation or feasibility study is warranted.

The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

AOC 32 was reportedly located directly west of the airfield along Range Access Road. The site is a reported disposal area covered with soil that contains asbestos from demolition materials disposed of in the early 1980s. A December 2000 site reconnaissance discovered that a building and parking lot may be covering the burial area. In April 2005, another potential burial site was discovered but quickly ruled out. No samples have been collected at the AOC. The only remaining suspected location of the disposal area is beneath the building and parking lot.

Based on known information, the site was recommended for low priority for future evaluation. Although the site is currently considered part of the Landfill Operable Unit, the Navy is investigating it as part of a site inspection at IRP Site 80. A geophysical investigation will be conducted at AOC 32 within the parking lot to evaluate whether potential burial trenches or debris are present within the parking lot. If a potential disposal site is identified, then surface and subsurface soil samples will be collected for analysis of asbestos.

The results of the site inspection will inform the next steps at the site. The field activities were planned for 2020, with no reported results yet available.

AOC 59 is located in the North Range area near the western boundary of the base. The site consists of a shallow trench that previously held several 55-gallon drums, most containing fluid that appeared to be motor oil. The Navy removed all drums as part of a range cleanup effort. Additionally, miscellaneous trash was present inside the trench, and there are areas of stained soil. All debris was also removed along with the drums. This area was once believed to be the location of buried trichloroethylene containers.

Total petroleum hydrocarbons, volatile organic compounds, polycyclic aromatic hydrocarbons, and arsenic were identified as chemicals of potential concern in soil in the 2006 preliminary assessment report. An attempt was made at three separate locations to install temporary monitoring wells to collect groundwater samples, but drilling equipment encountered bedrock that it was unable to penetrate before groundwater was encountered during all three attempts.

Based on previous studies, a 2010 report recommended AOC 59 no longer be considered high priority for future investigation. Although the site is currently considered part of the Landfill Operable Unit, the Navy is investigating it as part of a site inspection at IRP Site 80. Surface and subsurface soil and soil gas samples will be collected.

The results of the site inspection will inform the next steps taken at the site. The field activities were planned for 2020, with no reported results yet available.

AOC 64 is located in the central portion of the main base just south of Water Road. The site consists of scattered surface debris and an area of disposal trenches, along with a septic system, associated with Building X in Area ER. Area ER is the self-contained facility constructed in 1945 to develop the atomic bomb fuze and for drop tests. This area was active from 1945 to the 1980s. After World War II, all the buildings were eventually used for other projects.

The chemicals of potential concern identified at the site include total petroleum hydrocarbons, dioxins, pesticides, and radionuclides in soil as well as tetrachloroethene, perchlorate, and radionuclides in groundwater. The geophysical survey indicates that buried debris is still present in the old trenches at the site. The 2010 technical memorandum recommended further investigation, focusing on identifying whether the buried debris is responsible for the localized solvent detections in groundwater.

Although AOC 64 is currently considered part of the Landfill Operable Unit, the Navy planned to investigate AOC 64 as part of a site inspection at IRP Site 80. However, it was removed from the list of AOCs for the site inspection and will be addressed within the framework of the Navy’s radiological program, which is not part of the ERP.

AOC 85 is located in a series of drainages at the edge of a playa in Salt Wells Valley. The site is an abandoned landfill suspected to have received X-ray and photographic chemicals and other industrial wastes in the 1940s and 1950s. No significant burial was apparent during the 2018 site inspection. The chemicals of potential concern identified at the site include metals in soil and total petroleum hydrocarbons, chloroform, and metals in groundwater. Several metals were also identified as chemicals of potential environmental concern in the site inspection report.

A geophysical survey was conducted in December 2018 with the goal of defining any suspected disposal trenches at the site. The results of the survey showed no significant anomalies that would indicate a disposal trench, although some areas of shallow buried waste were identified in areas of surface debris.

The Navy conducted a site inspection for several of the AOCs under the Landfill Operable Unit. It was decided that further evaluation as part of a remedial investigation or feasibility study is warranted for this site. The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

AOC 99 is located near the eastern-central portion of the main base. The site was initially reported as an abandoned dump where debris was exposed at the surface. Dates of waste disposal are unknown. Various metals were identified as both chemicals of potential concern and chemicals of potential environmental concern for soil and groundwater.

AOC 99 is now being used for range operations and no longer falls under the CERCLA guidelines for evaluation. AOC 99 is recommended for removal from the IRP and transfer to the range sustainment program, where further evaluation may be required in the future.

AOC 102 is located in the northern portion of the main base. The site is an asbestos landfill that is well covered with soil and is marked with signs. The cover is a soil mound that directs water away and minimizes potential infiltration. The dates of disposal and the contents of the trench are unknown. An attempt was made to measure the depth to groundwater in a well during the 2005 investigation, but no water was encountered down to a depth of 300 feet. The only chemical of potential concern identified during the preliminary assessment was total petroleum hydrocarbons in soil.

The 2006 preliminary assessment recommended AOC 102 as a low priority for future evaluation. Although AOC 102 is currently considered part of the Landfill Operable Unit, the Navy is investigating AOC 102 as part of a site inspection at IRP Site 80. Further soil sampling will take place to assess potential soil impacts on the site.

The results of the site inspection will inform the next steps taken at the site. The field activities were planned for 2020, with no reported results yet available.

AOC 113 is located in the eastern portion of the main base near the Aircraft Survivability area. The site is a single open trench that was used to bury concrete rubble from demolition in the housing area. Dates of waste disposal are unknown. Various metals were identified as chemicals of potential concern and chemicals of potential environmental concern in soil during the 2018 site inspection. Based on the location of AOC 113, it was concluded that it would be unlikely that groundwater would be encountered in the area.

The Navy conducted a site inspection for several of the AOCs under the Landfill Operable Unit. It was decided that further evaluation as part of a remedial investigation or feasibility study is warranted for this site. The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

AOC 118 is located in the eastern portion of the main base near the Aircraft Survivability area. The site consists of two debris areas with partially buried wastes and an aircraft disposal site. Dates of waste disposal are unknown. Various metals were identified as chemicals of potential concern and chemicals of potential environmental concern in soil during the 2018 site inspection. Based on the location of AOC 118, it was determined that encountering groundwater in the area would be unlikely.

A geophysical survey was conducted in December 2018 with the goal of identifying whether any disposal trenches exist at the site or if the debris is surficial. The results indicated that there are no areas of significant waste burial at AOC 118, which confirms the initial assumptions.

The Navy conducted a site inspection for several of the AOCs under the Landfill Operable Unit. It was determined that further evaluation as part of a remedial investigation or feasibility study is warranted for this site. The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

AOC 122 is an open trench near the live bombing administration area, located in the North Range area. Dates of disposal are unknown. Total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, and acetone were identified as chemicals of potential concern in soil by the 2006 preliminary assessment.

The preliminary assessment recommended that AOC 122 be considered a low priority for future work. Although AOC 122 is currently considered part of the Landfill Operable Unit, the Navy is investigating AOC 122 as part of a site inspection at IRP Site 80. Further soil sampling will occur to evaluate the extent of potential soil impacts.

The results of the site inspection will inform the next steps taken at the site. The field activities were planned for 2020, with no reported results yet available.

AOC 124 consists of an aircraft debris dump within the active live bombing range, located in the North Range area. Dates of disposal are unknown. Cadmium and zinc in soil were identified as chemicals of potential concern during the 2018 site inspection. Groundwater was not evaluated but is expected to be around 50 feet below ground surface. Antimony, cadmium, copper, lead, and zinc were identified as chemicals of potential environmental concern in soil.

A geophysical survey was conducted in December 2018 with the goal of identifying whether any disposal trenches exist at the site or if the debris is only on the surface. The results indicated that areas of waste burial at AOC 124 are both associated with and nearby an observed pile of debris.

The Navy conducted a site inspection for several of the AOCs under the Landfill Operable Unit. It was determined that further evaluation as part of a remedial investigation or feasibility study is warranted for this site. The site is being included in a data gaps work plan for the Landfill Operable Unit sites. Fieldwork will be completed in the winter of 2020 and 2021 and documented in a draft technical memorandum anticipated to be available in the summer of 2021. The technical memorandum will recommend additional, future CERCLA actions.

AOC 131 is reportedly located in Salt Wells Valley, near the CT area. The site was a suspected buried disposal trench. The dates of operation are unknown, but most likely it was operational in the 1940s. No chemicals of potential concern or chemicals of potential environmental concern were identified in soil or groundwater in the 2006 preliminary assessment report.

The reported disposal trench could not be located after multiple interviews, reviews of aerial photographs, a search of documents, and two separate geophysical surveys. Therefore, the preliminary assessment recommended no further action for AOC 131. The site was included in the work plan for IRP Site 80 but will likely not be part of the site inspection because of the lack of evidence that the trench exists. A request for a no further action designation is planned for AOC 131.

AOC 154 is located in Randsburg Wash, northeast of the main administration area. The site consists of two large disposal pits or trenches that were the main disposal site for operations in Randsburg Wash from the early 1950s until use was discontinued in 1980. Approximately 3 cubic yards of waste per week were reportedly disposed of in this area. It was also reported that the waste piles were burned regularly.

More recent investigations have suggested that waste disposal attributed to trenches at IRP Site 41 may actually have occurred at AOC 154 because no evidence of disposal was found during investigation of IRP Site 41. As a result, the Navy, with state concurrence, closed IRP Site 41 and focused on the waste disposal identified at AOC 154. A geophysical survey supported by limited surface and subsurface soil sampling has identified a single, relatively large trench at AOC 154.

Total petroleum hydrocarbons, total cyanide, arsenic, and perchlorate were identified in the 2006 preliminary assessment report as chemicals of potential concern in soil. Assessment of groundwater has been problematic because the depth to groundwater at the site is believed to be up to 500 feet below ground surface. The site was part of a geophysical survey conducted between December 2018 and January 2019 to help with delineating the trench.

The site is being included in a data gap