Naval Amphibious Base Coronado

IR Site 1 is located along the shore in the northwestern corner of NAB Coronado between the Pacific Ocean and State Highway 75. The site includes four areas of concern, identified as the Building 603 Disposal Pit, the former vehicle maintenance pits, and Areas 1 and 2.

From 1969 to 1982, an estimated 1,100 to 3,800 gallons of waste lubrication oils, paint wastes, and thinners were discharged inside floor drains in Building 603. The floor drains emptied into an outside sandpit located about 60 feet north of the building.

The former vehicle maintenance pits were approximately 90 feet northwest of Building 603 and were each approximately 50 by 15 feet with concrete walls and sand bottoms. Dark coloration seen in the pit bottoms in a 1956 aerial photograph suggests that motor oil was drained into the maintenance pits.

Area 1 is on the southeast side of Building 603. Area 2 is in beach sand, 150 feet southwest of Building 1017 and 125 feet from the Pacific Ocean. Hydrocarbon contamination of an unknown source and extent was discovered during excavation at both areas.

A 1986 initial assessment study identified the site as potentially contaminated and recommended that an additional study be performed. Soil samples collected in the vicinity of the Building 603 disposal pit during a 1990 preliminary site investigation contained low concentrations of various contaminants. A 1993 site inspection included soil and groundwater sampling in all four areas of concern, resulting in a recommendation that additional sampling for petroleum hydrocarbons and metals be conducted. An extended site inspection was conducted in 1996 to sample soil and groundwater. Based on the results, no further action was recommended for IR Site 1.

The Department of Toxic Substances Control approved a no further action determination for IR Site 1 In 1997 because the risk to human health was found to be below the level requiring further remedial action. The Water Board and the US Fish and Wildlife Service concurred with the no further action decision and the site was closed.

IR Site 2 is near the bay-side shore of main base NAB Coronado. This site was used as a burn and disposal area from the mid-1940s to the early 1970s. Waste motor oils, solvents, and possibly small arms ammunition were identified as wastes burned or disposed of in the disposal area, which comprises a total volume of approximately 40,000 cubic yards.

A 1986 initial assessment study estimated that 120,000 gallons of hazardous waste could have been transported to the site for disposal or burning and recommended that additional study be performed. Seeps of oily substance rising to the surface offshore were occasionally observed during the 1986 study, possibly from rusty drums uncovered around the disposal area in the mid-1970s by Navy divers.

Soil, groundwater, and offshore sediments were sampled during a 1992 site inspection and additional sampling was conducted during a 1998 extended site inspection. Based on the results of prior investigations, a 2001 screening-level ecological risk assessment prepared by the Navy for IR Site 2 shoreline sediments indicated a need for further evaluation, primarily because of the presence of low concentrations of chemical of concern including some metals and organic compounds.

A 2008 remedial investigation concluded that risks to human and ecological receptors associated with sediment-bound contaminants of potential concern were acceptable. Based on the results of previous investigations at IR Site 2, groundwater, soil vapor, and offshore sediments were not found to pose an unacceptable risk to human health and the environment under current or potential future site uses, and the selected remedy for these media was no further action.

A 2015 focused feasibility study evaluated no further action and institutional controls as remedies that address the need to prevent land uses that may result in exposure risks to soils impacted by metals. The 2016 record of decision selected institutional controls as the remedy for soil, which consist of administrative and proprietary controls developed and implemented to minimize the potential for human exposure to remaining contamination at IR Site 2.

A 2019 final land use control implementation plan for NAB Coronado provides a framework for the implementation and monitoring of the IR Site 2 institutional control remedy. The first CERCLA five-year review performed at IR Site 2 in October 2020 in accordance with the plan, found the institutional control remedy to be protective of human health and the environment as intended in the 2016 record of decision.

IR Site 3 is near the northern boundary of NAB Coronado. Fuel oil or diesel fuel was discovered in soil during 1985 new paint shop excavation operations north of Building 103. A 1986 initial assessment study reported that between the mid-1950s to the early 1980s, a half-buried 55-gallon drum with holes at the bottom was used for disposal of waste materials including diesel fuel and solvents from the fueling facility and shops. Approximately 200 gallons per year of waste were disposed of in the drum.

Soil, groundwater, and offshore sediments were sampled during a 1992 site inspection and analyzed for organic compounds, metals, and other chemicals of concern. Follow-on sampling was conducted during a 1998 extended site inspection. Based on the results from these investigations, no further action was recommended for IR Site 3. The land portion of IR Site 3 was closed in 1998 with concurrence from the Department of Toxic Substances Control.

A 1998 site assessment and emergency response near Fuel Pier No. 1, adjacent to IR Site 3, resulted in the removal of about 122 tons of petroleum-impacted soil encountered in an excavation along the bay side of the quay wall. A 2002 risk assessment concluded that there were no unacceptable risks or hazards to the most relevant human receptor, the industrial/commercial worker.

A 2013 site assessment was conducted at IR Site 3 to characterize current conditions and facilitate the completion of a human health risk assessment. Results from analysis of soil, soil vapor, and groundwater samples identified petroleum-impacted soil in three historical areas and petroleum hydrocarbons in groundwater. The site assessment concluded that concentrations of petroleum hydrocarbons in soil and groundwater had significantly attenuated since 1995.

A 2016 corrective action plan described a remedial strategy for IR Site 3 consisting of land use controls for soil and monitored natural attenuation for groundwater. Three subsequent sampling events in 2016 indicated that key contaminants in groundwater were below screening levels, and no further action for groundwater was proposed. The Water Board concurred with the no further action recommendation in 2017, and groundwater at IR Site 3 was closed. Unacceptable risks under unrestricted land use for the hypothetical resident child remain because of petroleum contamination in soil, and a land use control implementation plan was developed.

A 2019 final Land Use Control Implementation Plan for NAB Coronado provides a framework for the implementation and monitoring of the IR Site 3 land use control remedy for soil. The first CERCLA five-year review performed at IR Site 3 in October 2020 in accordance with the plan found the land use control remedy to be protective of human health and the environment as intended.

IR Site 4 is near the bay-side shore of main base NAB Coronado and geographically overlaps IR Site 2. The approximately 60,000 square foot site was used from the early 1960s until 1981 as a disposal area for sandblast grit and paint wastes. Paint chips in the grit material consist of lead oxide, zinc chromate, and arsenates. A 1986 initial assessment study estimated that between 200,000 and 600,000 cubic feet of sandblast grit could be at the site.

Soil, groundwater, and offshore sediments were sampled during a 1992 site inspection and additional sampling was conducted during a 1998 extended site inspection. Based on the results of prior investigations, a 2001 screening-level ecological risk assessment prepared by the Navy for IR Site 4 shoreline sediments indicated a need for further evaluation, primarily because of the presence of low concentrations of chemicals of concern including some metals and organic compounds.

A 2008 remedial investigation concluded that risks to human and ecological receptors associated with sediment-bound contaminants of potential concern were acceptable. Based on the results of previous investigations at IR Site 4, groundwater, soil vapor, and offshore sediments were not found to pose an unacceptable risk to human health and the environment under current or potential future site uses, and selected remedy for these media is no further action.

A 2015 focused feasibility study evaluated no further action and institutional controls as remedies that address the need to prevent land uses that may result in exposure risks to soils impacted by metals. The 2016 record of decision selected institutional controls as the remedy for soil, which consist of administrative and proprietary controls developed and implemented to minimize the potential for human exposure to remaining contamination at IR Site 4.

A 2019 final Land Use Control Implementation Plan for NAB Coronado provides a framework for the implementation and monitoring of the IR Site 4 institutional control remedy. The first CERCLA five-year review performed at IR Site 4 in October 2020 in accordance with the plan found the institutional control remedy to be protective of human health and the environment as intended in the 2016 record of decision.

IR Site 5 is in the central portion of NAB Coronado. This 36-acre site, commonly referred to as “South Delta,” was a disposal area for dredge spoils from a 1966 dredging project. A 5-inch projectile picked up near the completion of dredging exploded inside the dredge, leading to the identification of buried ordnance in the deposited dredge spoils. A magnetic survey conducted in 1966 delineated areas of “clean” and “contaminated” material. In early 1969, 5 to 7 feet of clean fill was deposited on top of the contaminated fill.

In 1984, the Navy and the US Fish and Wildlife Service signed a formal agreement that set aside a 78-acre area inclusive of South Delta and an area north of IR Site 5 referred to as “North Delta” as a California least tern preserve. The site is fenced and inaccessible to the public.

Because UXO was buried and the site access is restricted, a 1986 initial assessment study concluded that the presence of UXO at IR Site 5 did pose a threat to human health and the environment if future site development were undertaken, but that no additional confirmation study was recommended. IR Site 5 was subsequently excluded from further investigation under the Navy’s IRP.

IR Site 5 was transferred to the Munitions Response Program at NAB Coronado. A site inspection was performed in 2009 for MRP Site 5, which is inclusive of IR Site 5 or South Delta and portions of North Delta. An overview of past and current environmental investigations and cleanup activities is presented in the MRP Site 5 site description.

IR Site 6 is in the southern portion of NAB Coronado at the Navy’s Morale, Welfare, and Recreation Marina. Boats were reportedly maintained at the site from 1972 to 1991. In 1991, the San Diego County Department of Health Services observed that maintenance of recreational boats, including sanding and painting operations, was being performed on the beach sand. Marine boat-cleaning operations ceased at the site in July 1991. This site was added as an IR Program site in 1995 after sampling indicated that soil contamination had resulted from the release of paint chips and other waste from sanding operations.

Soil sampling in 1994 indicated that the chemicals of concern were copper, arsenic, lead, and tributyltin (TBT). Groundwater samples exceeded the project action limit established for copper, and three of the samples exceeded the project action limit for TBT. A removal action conducted in 1998 resulted in the excavation of 1,002 tons of contaminated soil. Four groundwater monitoring wells were installed and sampled. Copper was reported in groundwater samples at concentrations exceeding the project action limit.

In the 2000s supplemental data was collected at the site and in 2008, a site inspection was conducted to determine whether the removal action was adequate and if IR Site 6 is protective of human health and the environment. Soil, sediment, and groundwater data from all previous studies were evaluated and the 2011 site inspection report found that site conditions do not pose unacceptable risks. All necessary remediation was accomplished to remove the past potential source of contamination and was effective in minimizing residual contamination in site media. No further action was recommended, the Water Board concurred in 2011, and IR Site 6 is closed.

MRP Site 5 consists of approximately 36 acres on the east side of the Silver Strand, east of California State Highway 75, in the central portion of NAB Coronado, formerly known as IR Site 5.

After transfer to the Munitions Response Program, a 2009 site inspection was performed at MRP Site 5, which included South Delta and portions of North Delta. Sampling, geophysical surveys, and visual reconnaissance did not detect explosive compounds but found that subsurface targets of interest remained in soil.

A 2013 remedial investigation was conducted at MRP Site 5 to characterize the nature and extent of potential munitions and explosives of concern (MEC) and munitions constituents (MC) in soil and groundwater. Beneficial uses defined for the bay were not found to be impacted by groundwater quality and no explosives were detected in soil. The results of geophysical and intrusive investigations found no unacceptable human health or ecological risks from MC under current and near future land use and exposure scenarios, although the potential for exposure to MEC hazards exists.

A 2015 focused feasibility study evaluated no action and land use control as remedial action alternatives to mitigate potential human health risks associated with MEC hazards at MRP Site 5. The 2016 record of decision documented selection of land use controls designed to control access and use of the site. Annual inspection and maintenance are performed to identify areas of erosion or potential MEC items and to inspect fencing. Based on the results of previous investigations, the selected remedy for groundwater is no action.

A 2019 final Land Use Control Implementation Plan for NAB Coronado provides a framework for the implementation and monitoring of the MRP Site 5 land use control remedy. The first CERCLA five-year review performed at IR Site 4 in October 2020, in accordance with the plan, found the land use control remedy to be protective of human health and the environment as intended in the 2016 record of decision.

The Disposal Area South site is on the eastern coastline of the Silver Strand peninsula in the southern portion of NAB Coronado. This approximately 99-acre site is occupied primarily by installation housing as well as a school and a small portion of a recreational marina at Fiddler’s Cove. Most of Disposal Area South area of concern (AOC) was historically located in the San Diego Bay but as the coastline has extended further east into the bay with filling operations ongoing during the 1940s, the current site boundaries lay within the land area only. The materials that may have been used to fill this site are unknown. The site was identified on a single archival map dated 1941.

A 2009 preliminary assessment that included Disposal Area South characterized the site as a suspected munitions and explosives of concern (MEC) area because the dredge material used at the site periodically contained munitions, although no munitions debris, evidence of MEC, or evidence of munitions constituents (MC) were identified.

A 2015 site inspection report indicated that MC identified during 2011 and 2012 intrusive investigations of the undeveloped portions of the site did not result in contaminant impact or an unacceptable level of risk because of historic site activities. Because of uncertainty associated with the MEC investigation and the residential military housing community and elementary school that comprises the developed areas of the AOC, an extended site inspection of the open and undeveloped areas was recommended.

The 2020 extended site inspection at MRP Site 13, previously known as Disposal Area South, found no MEC in the undeveloped AOC at the site identified as the Bayside area. Sampling results for MC indicated that no releases or significant risks to human and environmental receptors from MEC or MC were present, and that potential risk is very low. The 2021 extended site inspection report recommended no further action for MRP Site 13.

The former Rifle/ Pistol Range is on the southern coastline on the bayside of the NAB Coronado main base. The approximately 0.87-acre site was identified on archival maps dating from 1944 through 1953. It was labeled as a rifle range from 1944 to 1945 and as a pistol range from 1946 to 1953. The construction and closure dates of the former range are unknown. The site is currently occupied by two buildings that include a car wash and a military working dog facility.

The site was characterized in a 2009 NAB Coronado preliminary assessment as an area not suspected to contain munitions and explosives of concern because no historical evidence of explosives use exists but also concluded that a potential for munitions constituents to be present existed because of historical use of the site as a small arms range.

A 2015 site inspection at the former Rifle/ Pistol Range, also known as MRP Site 14, found concentrations of lead in soil above background and screening levels. A 2015 extended site inspection followed, and the 2018 technical memorandum reported that no further evaluation for ecological risk was necessary, but that lead remains a contaminant of potential concern based on risk to human health.

The 2021 report from a 2019 removal site evaluation divided MRP Site 14 into three exposure units (EU) based on spatial locations of samples that represent potential human exposure conditions. Additional investigations were recommended to delineate antimony, lead, and other metals concentrations in soil at EU-2 within the fenced site and at EU-3 outside the fence line.

EU-1, which encompasses most of the removal site evaluation investigation area, was found to have unacceptable concentrations of antimony and lead, potentially posing a risk to human receptors. The Navy recommended an interim soil removal action to reduce the overall risk at the site for lead and antimony and documented this decision in a 2022 action memorandum. The time-critical removal action at MRP Site 14 EU-1 was completed in February 2023 and will be documented in a removal action completion report. An offshore remedial investigation is underway at MRP Site 14.

The former Fuel Farm is in the western portion of NAB Coronado along Rendova Road, bordered by Glorietta Bay to the north. The Navy has identified the former Fuel Farm as one of four Underground Storage Tank (UST) Site 2 release sites, all located within 0.5 miles of each other. Based on the available data, six 1,000-gallon steel UST which stored gasoline were installed at the former Fuel Farm in 1944, and one 28,000-gallon concrete UST, which stored diesel fuel, was installed sometime after 1944. The use of the USTs was discontinued between 1974 and 1984.

Contamination from the USTs was discovered in 1985 southwest of the Former Fuel Farm as part of an investigation prior to construction of a building. Because elevated levels of total petroleum hydrocarbons had been detected in soil borings, the tanks were removed in 1991. A site assessment following tank removal and additional 1994 and 1995 investigations found that soil and groundwater contamination were limited in extent to the area immediately below the fuel farm. Approximately 6,000 tons of diesel-contaminated 6,000 cubic yards of contaminated soil were excavated from accessible areas by the Navy and removed from the site. Soil and groundwater sampling conducted from locations during a 1999 follow-up investigation indicated that the extent of contamination was limited to the areas just beyond where the excavations were stopped.

A 2013 internal background research report produced for the Navy assessed the status of UST Site 2 sites, including the former Fuel Farm, which was identified as requiring further assessment. A site assessment conducted in 2017 and 2018 identified residual soil contamination in the vicinity of the former Fuel Farm extending down to Glorietta Bay. A dissolved groundwater plume containing petroleum constituents that may be discharging into the waters of bay was also identified. Additional soil sampling and groundwater monitoring were recommended.

In 2020, additional site assessment activities found that potential impacts to Glorietta Bay from impacted groundwater in the northern portion of the Former Fuel Farm are unlikely. The 2021 final report identified no concentrations of contaminants of concern and concluded that former Fuel Farm at UST Site 2 currently meets all the media-specific criteria established in the State Water Resources Control Board low-threat UST case closure policy. A recommendation was made that the site be considered for closure with no further action. The Water Board concurred with the recommendation, and the site has been closed with no further action required.

The Building 18 UST site is near the southern corner of Building 18, which is close to the intersection of Guadalcanal and Rio Roads. The Navy has identified the Building 18 UST site as one of four UST Site 2 release sites, all located within 0.5 miles of each other. The diesel UST was a 1,000- to 1,500-gallon capacity steel tank at Building 18 that was removed in 2002.

A 1993 removal investigation conducted at Building 18 failed to locate the suspected UST and it was assumed that the tank was removed prior to 1990. Because contaminated soil was encountered, site assessment activities were conducted in 1996 and 1999, including collection of soil and groundwater samples in the vicinity of Building 18. Based on the results of investigations, the site was recommended for closure.

During 2002 construction of a Building 18 parking area, diesel fuel was detected. The source of the release was the Building 18 UST, although the cause, date, and amount of the release are unknown. The UST and associated piping were located and removed.

A 2013 internal background research report produced for the Navy assessed the status of UST Site 2 sites, including the Building 18 UST site, which was identified as requiring further assessment. A site assessment conducted in 2017 found that concentrations of petroleum constituents in soil and groundwater were below the screening levels. Based on results, the site meets the UST low threat case closure policy requirements. The site was closed in 2020 with Water Board concurrence.

The former Building 299 UST was located near the intersection of Guadalcanal and Kwajalein Roads northeast of Building 299. The Navy has identified the Building 299 UST site as one of four UST Site 2 release sites, all located within 0.5 miles of each other. Building 299 was formerly used as a boiler room. A 30,000-gallon, single-walled steel UST was installed in 1957 directly adjacent to the building, and reportedly held diesel fuel for the boilers. A leak was discovered in the tank in November 1991, and the UST and piping were removed. The source of hydrocarbon releases at the site are assumed to be from leaks in the tank, piping, and historical spills during the life of the UST.

A 1993 site assessment report included analytical results identifying petroleum hydrocarbons and constituents and trace lead in both soil and groundwater. The California Department of Environmental Health recommended further remediation of impacted soil and groundwater as well as quarterly sampling of the surrounding wells.

A 2013 internal background research report produced for the Navy assessed the status of UST Site 2 sites, including the Building 299 UST site, which was identified as requiring further assessment. A site assessment conducted in 2017 found that residual petroleum contamination related to past diesel fuel storage and transfer activities remained in the subsurface at Building 299. Additional activities were recommended to delineate contaminants in soil and the groundwater plume beneath the site, and to implement groundwater monitoring in existing and new site monitoring wells.

A 2021 corrective action plan proposed three alternatives as possible strategies for addressing remaining petroleum contamination at the site in support of case closure through the low-threat UST case closure policy. The alternatives all included a data gaps investigation, which was conducted 2021. A 2022 report of the investigation recommended no further action for soil at the Building 299 UST site because residual petroleum constituents in soil do not currently present an unacceptable risk to site receptors. Additional investigation to adequately characterize the presence or absence of free product in groundwater and implementation of a quarterly groundwater monitoring program to confirm groundwater plume stability and extent of impact were also recommended.

A monitoring program was implemented in April 2023 to determine if Building 299 UST site meets the criteria for closure under the low-threat UST case closure policy. Groundwater is monitored quarterly, new soil vapor wells will undergo one round of sampling, and a tidal influence study is being conducted to determine the impact of tidal changes on groundwater flow direction and levels.

Aboveground storage tank (AST) 1022 and the Building 346 Sump and associated piping were components of the same oily waste system. AST 1022 was approximately 100 feet southwest of current Building 149 and held approximately 28,000 gallons of oily water waste. Sump 346 was immediately adjacent to Building 346 and consisted of a concrete cylinder with a volume of approximately 1,000 gallons. The associated piping was approximately 2,000 feet long. The AST and the sump were removed in 1997. Soil samples were collected, and petroleum hydrocarbons were detected in the removal area.

In 2017 a site investigation found that residual petroleum contamination related to past waste oil storage and transfer activities remained in soil and groundwater at levels that do not pose an unacceptable risk to human health or the environment under the current and proposed future use scenarios for the site. Based on the findings, this site meets criteria for the low threat underground storage tank case closure policy requirements for closure. This site was closed with Water Board concurrence in September 2020.

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