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ATSDR has evaluated contaminants discussed in subsequent sections of this public healthassessment to determine whether exposure to them has public health significance. To selectcontaminants for discussion, ATSDR considers several factors: sampling design, field andlaboratory data quality, contaminant concentrations compared with health-based values, andcommunity health concerns.

Evaluating sampling design included reviewing the base's approach to locating contamination. Spatial distribution of sampling locations, sampling frequency, concentration changes over time,medium-to-medium differences, and correlation between the selected list of analytic parametersand suspected environmental contaminants are the factors ATSDR considered when determiningthe contaminants to which people might be exposed.

ATSDR's review of sampling field quality control procedures included interpreting data onbackground (or regional) concentrations of contaminants. Additionally, the adequacy andnumber of replicate, spiked, and blank samples were checked to verify detection of contaminants. To assess laboratory quality control, ATSDR reviewed procedures used to verify instrumentreliability.

Chemical concentrations detected on and off site were compared to values representingexposures believed to be without adverse health effects. Those comparison values are typicallyderived from data from animal studies and occupational exposures. The severity of health effectsdepends not only on exposure dose, but on the route of exposure (entry into the body) and on theamount of chemical absorbed by the body. For those reasons, comparison values used in publichealth assessments are contaminant concentrations in specific media and for specific exposureroutes. Several comparison values may be developed for a specific contaminant.

The following assumptions were used to calculate comparison values (EMEG, CREG, iEMEG,RMEG, and RfDC) used in this public health assessment:

Child -Body weight = 16 kg
Water ingestion rate = 1 liter/day
Soil ingestion rate = 200 mg/day
Pica soil ingestion rate = 5000 mg/day
Adult -Body weight = 70 kg
Water ingestion rate = 2 liters/day
Soil ingestion rate = 100 mg/day
Occupational Soil ingestion rate = 500 mg/day

To protect the most sensitive segments of exposed populations, ATSDR generally selects thecomparison value calculated from the most protective exposure assumptions. The potential forpeople to experience adverse health effects following exposure to contaminants at levels ofhealth concern is discussed in the Public Health Implications section of this document.

Background levels in local soil and water may be greatly influenced by high levels of chemicalsfrom native mineral deposits or other natural sources. Background levels could be anthropogenic(e.g., gravel for a road or parking lot) substances in the environment due to human-made,non-site sources. If the concentrations of contaminants exceed background levels, ATSDR willevaluate if exposure to those contaminants is of public health concern.

ATSDR also evaluates radioactive contamination. The Agency's approach to evaluatingradionuclides and other radioactive materials differs from its evaluation of nonradioactivehazardous materials. Because of the additive effects of radiation on the human body, the dosefrom radionuclide or radioactive materials is calculated for all exposure routes. Once the dosesby various routes are determined; a total dose is calculated.

The annual limit on intake, as defined by the International Commission on Radiation Protection(ICRP), is the amount of a single radionuclide and its progeny that delivers the occupationaleffective-dose limit by way of ingestion or inhalation. Occupational annual limit of intake arecalculated using the average career span of an occupationally exposed person -- 50 years. Toaddress public exposures, ICRP recommends using the average lifetime of an individual (70years), and the public's effective-dose limit, 1 mSv (100 mrem) per year, to determine the public'slimit of intake. A glossary of the terms describing the contaminants of concern, healthcomparison values, and the radiological terms used in this section of the public health assessmentare in Appendix A.

In the data tables describing the contaminants of concern at HPA, the listing of a contaminantdoes not mean that exposure to it will cause adverse health effects. Rather, the list indicateswhich contaminants exceeded comparison values and its presence in all media will be discussed. Multiple routes and multiple chemical effects will be evaluated. Most of the comparison valuesin this document are calculated using adult ingestion rates and body weights because most of theareas under investigation are visited by adults. Comparison values for children are lower thanthose for adults. ATSDR uses the lower comparison values when children at a site could beexposed to contaminants in a specific medium.

A. On-Site Contamination

Contamination in soil, sediment, air, groundwater, surface water, and food chain as well as otherhazards will be discussed in this section. All on-site sampling has been conducted by the Navy.


Historically, many HPA areas have received shipyard and repair wastes such as discarded radiumdials and sandblast wastes. A preliminary radiation survey was conducted in 1988 to determineif there was elevated radioactivity at HPA. The Industrial Landfill, Bay Fill Area, OilReclamation Ponds and the Sub-Base Area were surveyed for evidence of gross gammaradioactivity. That information was not evaluated during preparation of this public healthassessment because more recent and more comprehensive data were available. A radiationoverview can be found in Appendix E.

In 1992, the Surface Confirmation Radiation Survey (SCRS) was conducted to evaluate sourcesof possible radioactive contamination at the Industrial Landfill, Bay Fill Area, Oil ReclamationPonds, the Officers Club, the Oily Liquid Waste Disposal Area, the Oily Waste Pond andIncineration Tank, and the Sub-Base Area (Figure B-2). Low-level radioactive waste which isdefined in 10 CFR 61.2 was primarily disposed of at the landfill areas. Potential sources ofradiation at the Industrial Landfill and Bay Fill areas include crushed radium sources and blacksand (Black Beauty) non-indigenous to HPA containing elevated natural radiation. The radiumsources are in the form of:

    dime-sized, sealed, glass discs with a spot of radium in the middle (51);
    ceramic/glass wafers;
    hollow ferrous discs with a glass covers;
    quarter-sized metal sources with back plates;
    disintegrated radium sources.

Those components and parts, containing radioactive radium, were not designed or made toprevent the release of the radioactive material. The radium was incorporated into luminous dials,numbers and pointers of watches and compasses. Other radium parts were made into markers,lines, and spots that glowed in the dark (52). Those radium sources were deposited at theIndustrial Landfill and Bay Fill areas after WWII. Some of the sources at the landfills werecrushed or decomposed, allowing radioactive materials to escape into the environment (4). Aradium/radon fact sheet is in Appendix F.

Radionuclides in Soil

Soil samples were collected to establish the amount and type of radionuclides at areas on baseand to establish background levels. Soil samples were taken in areas with elevated gamma levelsand in non-anomalous locations. Non-anomalous soil samples were taken to determinebackground levels of radionuclides.

The Navy performed a gamma radiation meter survey to locate gamma-emitting point sources onthe soil surface and up to 12 inches below the ground surface. Up to 500 radium sources weredetected at or near the surface, i.e., within the first 12 inches of the soil at IR-1 and IR-2. Once agamma source or an anomaly (higher than the expected background gamma reading) was found,the location was marked in the field.

Figure B-4 shows the locations used for the establishment of background gamma activity. Background samples were collected at non-disposal sites.

Ten percent of the samples collected were analyzed for plutonium. A total of 120 soil samples(not including background samples) were collected during the SCRS. Soil sample analysisindicated the presence of americium-241 (Am-241), cesium-137 (Cs-137), potassium-40 (K-40),radium-226 (Ra-226), radium-228 (Ra-228), thorium-228 (Th-228), plutonium-238 (Pu-238),plutonium-239 (Pu-239), and plutonium-240 (Pu-240).

Figure 1 shows soil background ranges for Am-241, Cs-137, Ra-226, Ra-228, and Th-228 found at HPA.

figure 1.

The probability and severity of health effects increases as exposure to radiation increases,although exposure to background levels of radiation (i.e., those levels naturally occurring in theenvironment) are thought not to produce noticeable health effects in humans (54). Thus forradiation protection purposes, the dose due to radiation exposures above background iscalculated as an indicator of potential health effects.

Because exposures to radiation levels above background are indicators of potential health effects,the natural background concentrations in nearby, representative soils are first established andthen compared to soil concentrations found in contaminated areas. To accomplish that, ATSDRconstructed a histogram of the radiation levels found in HPA soils. The histogram (Figure 2)shows the distribution of radiation levels found in HPA soils relative to background.

Figure 2 shows the number of soil samples from anomalous areas which were within the rangesof background, between one and two times background, between two and three timesbackground, between three and four times background, between four and five times background,and more than five times background.

Figure 2.

A comparison between background radium concentrations and concentrations in anomalous areassuggest that, for some areas (e.g., IR-1/21 and IR-2) anomalous area radium concentrationsexceeded those of background. Background concentration for Ra-226 ranged from 0.11 to 1.13pCi/gram, with an average of 0.64 pCi/gram. For the isotope of greatest concern, Ra-226, mostof the contamination was found at IR-2, the Bay Fill Area (Figures B-5 and B-6). A large area600 feet by 600 feet with numerous point source anomalies was identified within the area. Thehighest concentration of Ra-226 detected at IR-2 was 3,905 pCi/gram, which was associateddirectly with a dial face. Several radium sources were also found at the IR-1/21 (Figure B-7), theIndustrial Landfill, which is located next to IR-2.

The EPA National Air and Radiation Environmental Laboratory (NAREL) has proposed usingvolume reduction/chemical extraction (VORCE) technology to remediate IR-1/21 and IR-2. OnOctober 4, 1993, EPA discussed preliminary results of Phase I of the pilot remediation project. During the first phase, three soil samples were collected from HPA for petrographic analysis. Analysis was performed to determine which soil fraction was associated with the Ra-226. Of thethree samples that were collected, one of the samples had 100 percent recovery, which meansthat no Ra-226 was found in the soil sample when the point source was physically removed fromthe sample. The two other samples yielded an approximate 30 percent recovery; most of theRa-226 remained in the sample after the source was removed. This remaining activity isconsidered to be diffuse contamination. Therefore, NAREL still needs to determine the amountof diffuse material that may remain in the landfill after a point source is removed (53).

The Navy is conducting a phase II and a phase III radiation investigation. Additional trenchingand sampling of soil within IR-1, IR-2, IR-7, and IR-18 have taken place to determine thesubsurface extent of radioactive contamination. Air permeability of soils has been tested at IR-1,IR-2, and IR-7. A surface radiation contamination survey of buildings previously used by NRDLand of other buildings suspected of having been used for radiologic operations will be conducted. Gamma logging was conducted inside the casings of existing monitoring wells. Gamma loggingwas used to evaluate the vertical extent of the gamma-emitting Ra-226 contamination in thesurrounding soil. Investigation-derived cuttings and archived soil samples in Buildings 810 and414 are being screened for field gamma radioactivity (5).

Radiation in Air

The Navy tested IR-1, IR-2, and IR-5, and in the surrounding areas, on and off site, for grossalpha and beta radiation in air. The investigation indicated that the amount of alpha and betaradiation in the air at these areas were typical of background levels in the area. Therefore, theamericium, radium, thorium, cesium, and plutonium in undisturbed soils at those areas do notappear to be escaping into the ambient air (55).

Because Ra-226 may be a problem, ATSDR evaluated radon, the decay product of Ra-226. TheSCRS tested radium contaminated areas for release of radon into the air. Radon fluxes(measurements of the radon release rates over an area) were measured at the soil/air boundary toaccurately determine the boundaries of radium contaminated areas. Radon release rates weredetermined using carbon filled radon flux canisters. Canisters were placed at random locations,and at locations directly over point sources of gamma activity to identify the boundaries of areaswhich contained the elevated gamma readings. A total of 371 radon flux canisters were placedaround the site.

Background radon emission rates ranged from 0.00 to 1.12 pCi/m2/sec while radon emissionrates in anomalous areas ranged from 0.00 to 74.96 pCi/m2/sec. A comparison betweenbackground radon emission rates and anomalous area radon emission rates suggest that, ingeneral, anomalous area radon release rates are the same as background release rates (Figure 3).

Figure 3.

Data from Figure 3 shows that 0.3% of the radon samples taken in anomalous areas were abovethe background range. Even though the highest emission rate was 74.96 pCi/m2/sec, the averagerelease rate over the disposal area is less than the Health and Environmental Protection Standardfor Uranium and Thorium Mill Tailings (40 CFR 192), 20 pCi/m2/sec. This standard is based onradon released in buildings or homes with children living in them (56). The release rates of thesite are not large enough to raise the ambient concentration of radon by measurable amounts inareas where people are present. Overall, radon release rates are the same as background releaserates.

Radiation in Ground and Surface Waters

Groundwater was tested for gross alpha and beta radiation. Nine groundwater and two bay watersamples were taken. The results of the testing were inconclusive (57).

During the SCRS, downhole gamma radiation surveys were performed in nine monitoring wellsto determine the depth of radium contamination (58). The wells were chosen based on theirproximity to anomalies and previous sampling results which showed evidence of elevated alpharadiation in water. Results of the survey did not indicate the depth of the contamination andanalyses are currently being repeated.

Other Radiological Hazards

Table C-2 lists the NRDL buildings that will be investigated in phase II and III of the radiationinvestigation (5). During the Navy Fence-to-Fence Radiation Survey, several radiationmeasurements above normal background were detected on HPA. During a radiation survey,Navy contractors detected a radiation measurement higher than normal background at Building364, a former NRDL site. The interior of Building 364 was decontaminated, but contaminationwas detected at the exterior of the building. The area was fenced to limit unauthorized access. The exterior or Building 364 is to be investigated as a part of the phase III radiologicalinvestigation. Building 364 was accepted by the NRC for unrestricted use and is presently leased(6). Sampling was conducted inside Building 364; no radiation levels greater than backgroundwas found. According to the Navy, the tenant is aware of the elevated radiation levels on theoutside foundation. Building 364, has two abandoned, concrete lined utility trenches leadingfrom the rear eastern wall to a nearby covered sump. One of the trenches has a small area that iscontaminated with alpha and gamma emitters. The area behind Building 364 is fenced. Remnantradiation was also detected on a portion of the asphalt-covered parking lot area adjacent toBuilding 364. The radioisotope has been identified as Cs-137.

A combination safe measuring 18 inches by 18 inches located within the fenced Building 414(IR-14), the low-level radiation waste storage area, contains alpha and gamma activity aboverelease guidelines established by the NRC. The combination safe dial and handle have fixedalpha activity 59,000 dpm/100 cm2 . The contents of the safe, previous location, and use areunknown. The safe has remained unopened; the combination is unknown. Tritium was used as aparticle accelerator target at Building 816 in Parcel A (59). Sampling for tritium has beencompleted and none was found (35, 36).

Surface Soil

Industrial Landfill (IR-1/21) and Bay Fill (IR-2)/OU I

In 1993, additional soil sampling took place at OU I (60). VOCs, SVOCs, oil and grease,petroleum hydrocarbons, PCBs, and pesticides were detected sporadically in the artificial fill anddisplayed non-point source-related characteristics. Antimony, arsenic, copper, lead, and zincwere detected above the interim ambient levels for sepentinite fill and may be point sourcerelated (Tables 3 and 4). Interim ambient levels were developed by the Navy, and agreed uponby the agencies, as field screening criteria to identify "hot spots" or high levels of chemicalconstituents (40).

At IR-1/21, organic compounds and metals were found mostly in a debris zone, which is an areaapproximately 900 by 1100 feet and found in the central part of IR-1/21 (61). The debris zone isheterogenic in it makes up. According to the Navy, there is no vertical or lateral consistency orpattern to the distribution of these compounds in the debris zone and high concentrations werecommon. There are three other areas with elevated concentrations of contaminants: along thesouthwest boundary of the site between 4 and 18 feet; along the east and southeast sides of thelandfill to a depth of 5 feet; and in the western central portion of the site adjacent to the bay,highest concentrations generally occurred in soil shallower than 6 feet below ground surface. Triple A reportedly disposed of sandblast waste in this area.

IR-2 was divided into six areas corresponding with Triple A use areas:

Triple A Sites 2 and 14/IR-2. Organic contaminants and metals were detected in shallow anddeep soils in an area extending approximately 600 feet to the southeast and 200 feet to the northand northeast for some compounds. Aroclor-1260 and carcinogenic PAHs were observed in soilabove 4 feet and appear to be continuous with similar contaminants observed in the southeastcorner of IR-1/21. Maximum concentrations were higher in deeper soils. Elevatedconcentrations extend to a depth of 6 to 12 feet, depending on the bay mud (i.e., 6 to 7 feet).

Triple A Site 19/IR-2. Organic contaminants were detected in a shallow and deep soils. Allorganic contamination was restricted to the artificial fill layer. Most metals were detected indeep soil between 6 and 11 feet. Approximately 200 feet southeast of Triple A Site 19, elevatedlevels of metals were detected near Building 600. Boring logs indicate that the elevatedconcentrations are in a zone of fill that appears to be dredge materials.

Triple A Site 18/IR-2. Aroclor-1260 and petroleum products were detected from the groundsurface to a depth of about 6 feet at the east end of Triple A Site 18. At the west end of the area,petroleum products and PAHs were observed in a test pit sample. In two surface soil grabsamples, taken behind the backstop of the pistol range in debris piles Aroclor-1260 andcarcinogenic PAHs, arsenic, copper, lead, and zinc were detected. Metals were found acrossTriple A Site 18 in shallow soils.

Triple A Sites 17/IR-2 and IR-3. Organic compounds and metals were detected in both shallowand deep soils. Organic contaminants include xylenes, ethylbenzene, Aroclor-1260, oil,petroleum, and carcinogenic PAHs. Metals include arsenic, copper, lead, and zinc. Organiccontamination was significantly higher, as much as one to two orders of magnitude in deep soilthan in shallow soil. The difference may be the result of free phase petroleum product floatingon the groundwater and residual product present in the soil between 6 and 25 feet bgs (60). Metals were widely distributed across Triple A Site 17.

Triple A Site 13/IR-2. Within the area adjacent to Tank S-505, petroleum products and oil weredetected in shallow soil at one location, and in deep soil up to 6 feet bgs at two locations. Leadwas detected in shallow soil; copper, lead, and zinc were detected in deep soils. In the area ofTriple A Site 13, Aroclor-1260 and carcinogenic PAHs were detected in deep soil. Metalcontamination was wide spread.

Southeast End/IR-2. This area may correspond to a burn area, or it may be that this land area ofIR-2 was created by pushing the remains of the burned debris into the bay (60). PAHs andmetals were found in shallow soil. Carcinogenic PAH contamination is widespread. Metals indeep soil generally appear to be limited to a smaller area than in shallow soil. Dredge spoils mayhave been deposited of in this area (60). The source of the dredge spoils are assumed to be theSan Francisco Bay, location was not specified in Navy documentation.

Table 3. Maximum Contaminant Concentrations in IR-1/21 Soil

ContaminantMaximumConcentration (ppm)95% UpperConfidenceLimit of theArithmeticMean (ppm)InterimAmbientLevel forSepentiniteFillComparison Value(ppm)ComparisonValue
Phenanthrene (PAH)1,200146.8NoneNoneNone
Naphthalene (PAH)1,400173.2NoneNoneNone
2-Methylnaphthalene (PAH)65080.5NoneNoneNone
Benzo(a)anthracene (PAH)*8012.9NoneNoneNone
Benzo(b)fluoranthene (PAH)*439.7NoneNoneNone
Benzo(a)pyrene (PAH)*168.1None0.1CREG
Benzo(k)fluoranthene (PAH)*137.9NoneNoneNone
Chrysene (PAH)*7712NoneNoneNone
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from Harding Lawson Associates. Data Submittal for IR-1/21. Naval Station Treasure Island,Hunters Point Annex, San Francisco. February 24, 1994.

Table 4. Maximum Contaminant Concentrations in IR-2 Soil

ContaminantMaximumConc.(ppm)MeanConc.(ppm)InterimAmbientLevel forSepentiniteFillComparison Value(ppm)ComparisonValueReference
Phenanthrene (PAH)110N/ANoneNoneNone
Naphthalene (PAH)88N/ANoneNoneNone
2-Methylnaphthalene (PAH)210N/ANoneNoneNone
Benzo(a)anthracene (PAH)*36N/ANoneNoneNone
Benzo(b)fluoranthene (PAH)*12N/ANoneNoneNone
Benzo(k)fluoranthene (PAH)*10N/ANoneNoneNone
Benzo(a)pyrene (PAH)*14N/ANone0.1CREG
Indeno(1,2,3-cd)pyrene (PAH)*4N/ANoneNoneNone
Dibenzo(a,h)anthracene (PAH)*1.5N/ANoneNoneNone
Benzo(g,h,i)perylene (PAH)*5N/ANoneNoneNone
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from Harding Lawson Associates. Preliminary Draft Operable Unit I, Summary of RemedialInvestigation. Naval Station Treasure Island, Hunters Point Annex, San Francisco. September 1, 1993.

Off-Site Surface Soil

Railroad Right-Of-Way (PA-52)

Lead (14,267 ppm), copper (24,373.5 ppm), and zinc (580.2 ppm) were detected in off-sitesurface soil along the railroad right-of-way. Aroclor-1260 (0.180 ppm) and several tentativelyidentified compounds were also detected (25).


Ambient Air

In 1984, during the Initial Assessment Study, 400 to 500 pounds of discarded waste asbestoswere found on the ground immediately outside of Building 521 in Parcel E. Friable asbestosfrom deteriorating insulation on boilers and other equipment was also found. Some of thisasbestos may have been washed away with rainwater (62). Two 8-hour, ambient air sampleswere taken downwind of Building 521. Samples were analyzed for asbestos fibers; however,asbestos was not detected. Wind speeds during sampling were from 5 to 10 miles per hour.

The Navy conducted a risk assessment in 1987 for the proposed Housing Sites 1 and 2 in ParcelA because they were considering home porting the USS Missouri at HPA. Air samples collectedover 8 hours were analyzed for metals, asbestos, and organic compounds at areas which includethe following: an area north of Crisp Ave, adjacent to the Industrial Landfill; an area southeast ofDonahue Street near the main gate; and an upwind background area. Several VOCs weredetected at all sampling locations and asbestos at 0.018 fiber/m3 was detected at only onesampling location. An average of 2-300 fibers/m3 are usually present in urban air. Theseasbestos levels are sufficiently low that they are not likely to be of significant health concern. Allof the Navy's asbestos samples were analyzed by the transmission electron microscopy method.

Most recently, an air sampling screening study for volatile organic compounds (VOCs),semi-volatile organic compounds (SVOCs), formaldehyde, and asbestos was conducted as part ofthe RI/FS between July 8-18, 1991. Results of this study were used to develop furtherrecommendations for subsequent base air sampling (62). Ambient air sampling conducted thusfar was based on the 11 original IR areas designated in the Confirmation Study (Figure B-8) plusfive additional areas.

Sample locations were chosen based on observed prevailing wind conditions on the day ofsampling. Prevailing winds would transport emissions and airborne particles predominately tothe east-southeast out across the base to the bay (62). Twelve sampling stations were placeddirectly over, adjacent to, or downwind of the original 11 IR areas (Figure B-8). Table 5 showslocation number and the description of were the air sampling stations were located. Station A8was placed on the downwind perimeter of the base to intercept any airborne contaminants thatmight originate from other on-site sources. Stations 11 and 12 were placed upwind of HPA todetermine background concentrations. According to the Navy, although not within an IRboundary, the area on which Station 11 was located is suspected of containing contaminantssimilar to those found at IR-1/21 (62). Station 9, located east of the Pickling and Plating Yard,was not placed downwind of interfering sources. The Navy thought that base tenants (artists)near IR-9 may release various airborne contaminants, thereby interfering with the ambient airmonitoring. All other samplers were placed downwind of potentially interfering sources (62).

Table 5. Location of Air Sampling Stations
1Within IR-1/21
2Downwind of IR-2 and IR-3
3Within IR-2 and downwind of IR-3,IR-11, IR-14, and IR-1/21
4Downwind of IR-4 and IR-1/21
5Within IR-5 and downwind of IR-4,IR-5, IR-12, and IR-1/21
6Downwind of IR-7
7Downwind of IR-6 and IR-10
8Downwind perimeter sampler
9Downwind of IR-9
10Downwind perimeter samplerwithin IR-22
11 and 12Upwind background locations
Adapted from Draft Final Air Sampling Reportand Work Plan. Naval Station Treasure Island,Hunters Point Annex San Francisco, California. July 31, 1992.

Four samples were taken at each air sampling station (Figure B-8) over a 5-day period and wereanalyzed for VOCs, SVOCs, PCBs, metals, asbestos, and formaldehyde. Samples were collectedfor 8 hours. VOCs and SVOCs were monitored at 3 to 6 feet above ground surface. Metals weremonitored approximately 3 feet above the ground. Formaldehyde and asbestos were monitoredat 5 feet (62). Table 6 shows the contaminants found in air. Sampling procedures are describedin the Draft Final Air Sampling Report (62).

Pesticides and metals were detected in air samples (Table 6). Pesticides were detected atconcentrations above comparison values at the western boundary of the base at a designatedupwind background air monitoring station. The source of the pesticides is unknown. Asbestoswas detected at low levels (0.000002 fibers/m3).

Table 6. Maximum Contaminant Concentrations in Installation Air
ContaminantMaximum Conc.
ComparisonValue (µg/m3)Comparison ValueReferenceAirStation
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from Draft Final Air Sampling Report and Work Plan. Naval Station TreasureIsland, Hunters Point Annex San Francisco, California. July 31, 1992.

During the installation air monitoring study, some of the ambient air samplers were not located inareas that were directly downwind of suspected emission sources associated with the IR areas. Inaddition, some sites of concern had not been identified at the time the initial study wasconducted. To better characterize HPA air quality, the Navy is planning additional air sampling. Three tasks are planned: conducting ambient air monitoring at additional locations, conductingflux chamber measurements (to measure VOC emission rates at the ground surface), andevaluating the wind erosion potential of particles (62). Figure B-8 shows the location of theprevious air monitoring stations and the proposed air monitoring stations.

Indoor Air

Many of the HPA buildings are leased to artists and other small business owners. Appendix Ddescribes the PA areas by building number, historical use, current use, and possiblecontamination. Little indoor air sampling has been conducted at HPA. The PA area samplingplan does not include indoor air sampling (9, 10, 11).

During the PA area reconnaissance conducted in 1991, each PA building or area was visited byNavy contractors. They inferred historical chemical use from visual observations, assessedcurrent chemical use, and assessed the evidence of actual or potential releases of chemicals to theenvironment (Appendix D). Navy contractors mapped, photographed, and recorded observationsat each area. The focus of the survey was to document potential hazards such as sumps,pipelines, tanks, trenches, treatment equipment, and storage areas and assess evidence ofchemical releases to flooring pavement, or soil. In addition, contractors observed possibleasbestos-containing material in most buildings, transformers potentially containing PCBs, fiveadditional USTs, metal based paints in many buildings, and possible past use of radioactivematerials (9, 10, 11). It is possible that waste from past use of those buildings could behazardous to the present base tenants. Tenants have occupied HPA buildings since the late 1970swhen Triple A Machine Shop leased the base from the Navy.

Scrap Yard Old (IR-4) and Transformer Storage Area (IR-5)

In 1992, surface soil sampling took place at OU III. Several metals and Aroclor-1260 weredetected at IR-4, the Scrap Yard, and at IR-5, the Old Transformer Storage Area. Metals andAroclor-1260 were detected above comparison levels (Tables 7 and 8). Lead was found at thehighest levels of the metals identified. Aroclor-1260 was found at five shallow areas (up to 3feet) (21). Low levels of PAHs, VOCs, and SVOCs were also detected. The source of themetals is most likely past area activities; a wide variety of machinery, metal, and other itemswere taken to IR-4, disassembled, and sorted for disposal (21). Transformers were stored at IR-5and are most likely the source of Aroclor-1260 (20). Figure B-9 shows the contaminated areas atIR-4 and IR-5.

Table 7. Maximum Contaminant Concentrations in IR-4 Surface Soil

ContaminantMaximumConc. (ppm)Mean Conc.(ppm)ComparisonValue (ppm)ComparisonValueReference
Antimony409.443.30.8RMEG picachild1
Cadmium15.43.40.4EMEG picachild
Manganese1,814768.610RMEG picachild
Mercury46.73.14iEMEGpica child
Molybdenum46.83.610RMEG picachild
Vanadium13657.56iEMEGpica child
Zinc4,105495.3100RMEG picachild
Aroclor-126025.13.40.01EMEG picachild
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
1 Presently there are no children on base, since future land use has not yet beendetermined for HPA, ATSDR considers the possibility of pica children at this IR site.
Adapted from Harding Lawson Associates. Draft Final Interim-Action Operable UnitIII Alternative Selection Report. Naval Station Treasure Island, Hunters Point Annex,San Francisco. May 12, 1993.

Table 8. Maximum Contaminant Concentrations in IR-5 Surface Soil

ContaminantMaximum Conc.(ppm)MeanConc.(ppm)ComparisonValue (ppm)Comparison ValueReference
Antimony12.840.8RMEGpica child1
Cadmium12.91.70.4EMEGpica child
Manganese1,94984410RMEGpica child
Mercury4.80.44iEMEGpica child
Vanadium15353.46iEMEGpica child
Zinc1,400214.3100RMEGpica child
Aroclor-12604.80.40.01EMEGpica child
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
1 Presently there are no children on base, since future land use has not yet been determinedfor HPA, ATSDR considers the possibility of pica children at this IR site.
Adapted from Harding Lawson Associates. Draft Final Interim-Action Operable Unit IIIAlternative Selection Report. Naval Station Treasure Island, Hunters Point Annex, SanFrancisco. May 12, 1993.


Groundwater IR-6 and IR-10

Underneath the Tank Farm, IR-6, and the Battery and Electroplating Shop, IR-10, there are twogroundwater contamination plumes in the shallow aquifer (Figure B-10). The plumes are fromtwo different sources, one migrating from each of the IR areas (26). In 1992, benzene, at 72 ppb,was detected 150 feet downgradient from IR-6. Chlorinated solvents, trichloroethene (TCE),1,2-dichloroethene (1,2-DCE), and vinyl chloride, were detected at both IR-6 and IR-10. TCEand vinyl chloride were identified in wells near the Tank Farm. TCE was the compound mostconsistently detected around Building 123, IR-10. Concentrations of chlorinated solvents weredetected in two areas, 200 feet down gradient of Building 123 and near the Tank Farm. 1,2-DCEconcentrations were below comparison values. Hexavalent chromium, molybdenum, vanadium,manganese, cobalt, cadmium, arsenic, antimony, and beryllium were above comparison values atboth areas (Tables 9 and 10).

Two aquifers have been defined at IR-6 and IR-10, the shallow aquifer and the bedrock Aquifer. Groundwater sampling took place in the shallow and bedrock aquifers. Groundwater flow in the shallow aquifer is generally to the northeast, towards the bay. The bedrock aquifer in placesappears to be in hydraulic connection with the shallow aquifer (26).

Table 9. Maximum Contaminant Concentrations in On-Site Groundwater Samples IR-6 Tank Farm
ContaminantMinimum and MaximumConc. (ppb)ComparisonValue
Comparison ValueReference
Phenanthrene2 - 160NoneNone
Dibenzofuran2.2 - 140NoneNone
Naphthalene20 - 1800**NoneNone
2-Methylnaphthalene2 - 240NoneNone
Vinyl Chloride*5.2 - 380.2EMEG-child
Trichloroethene1.4 - 53CREG
Benzene*1 - 721CREG
Arsenic*2 - 12.50.02CREG
Lead*1.9 - 2.4**NoneNone
Antimony14.4 - 40.1**4RMEG
Barium11.9 - 929700RMEG
Beryllium*0.37 - 0.560.008CREG
Cadmium4 - 6.42EMEG-child
Cobalt5.3 - 16.7**NoneNone
Manganese0.69 - 886050RMEG-child
Nickel17.3 - 117NoneNone
Vanadium1.7 - 56.720LTHA
Chromium(VI)100 - 12050RMEG
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
** Indicates numerical value is an estimated quantity
Adapted from Draft OU II Remedial Investigation Report. Naval Station Treasure Island, Hunters PointAnnex San Francisco, California. June 12, 1992.

Table 10. Maximum Contaminant Concentrations in On-Site Groundwater Samples IR-10 Battery andElectroplating Shop
ContaminantMinimum and MaximumConc. (ppb)ComparisonValue
Comparison ValueReference
Vinyl Chloride*3**0.2Chronic OralEMEG
Trichloroethene2 - 383CREG
Arsenic*1.7 - 9.9**0.02CREG
Antimony31.7 - 46.6**4RMEG
Beryllium*0.27 - 1.4**0.008CREG
Cobalt10.6 - 15.5**NoneNone
Manganese20.1 - 1790**50RMEG
Vanadium1.5 - 83.120LTHA
Molybdenum7.6 - 6350RMEG
Chromium(VI)160 - 40050RMEG
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
** Indicates numerical value is an estimated quantity
Adapted from Draft OU II Remedial Investigation Report. Naval Station Treasure Island, Hunters PointAnnex San Francisco, California. June 12, 1992.

Food Chain

In the past, an abundance of liquid wastes including solvents and plating wastes were poureddown drains at many of the HPA industrial buildings, for instance at the Battery andElectroplating Shop (16) and at the Pickling and Plating Yard (28). Those waste materials wentinto the combined storm drain system and out into the bay. Appendix D describes past uses andactivities at PA and IR areas. At times Triple A washed sandblast grit out of the dry docks andinto the bay (7).

Sampling and testing data indicate that disposal practices have contaminated soil, sediment,groundwater and surface water It is not known what effect those practices may have had on thefood chain.

Environmental Sampling and Analysis Plan (ESAP) Mussel Analysis

The first portion of the ESAP was an evaluation of whether persistent and bioaccumulativehazardous substances may be entering the San Francisco Bay from HPA (see Quality Assurance and Quality Control section for data validity). To evaluate that, the Navy conducted a musseltransplantation study. Mussels were collected from an uncontaminated area in Bodega Head andtransplanted in the waters surrounding HPA. Two, 30 day mussel deployments were conducted. Bioaccumulative effects testing included the following: 1) radioactivity screening; 2) inorganicsand metals; 3) pesticides and PCBs; 4) SVOCs; 5) and tributyltin.

Tributyltin compounds are one of the organotins and are used in antifouling paints. Tributyltincompounds are particularly toxic to aquatic organisms (64). Background concentration oforganotin compounds are frequently elevated in aquatic organisms collected near marinas andother locales where organotin-based antifouling paints are extensively used (65). Since organotincompounds are toxic to aquatic wildlife, the Navy analyzed sediments for the presence oforganotins to determine if aquatic species were being impacted. The ability of microorganisms,algae, and higher organisms to reduce tributyltin and other organotins into less toxic metabolitesthat can be rapidly excreted seems to preclude food chain biomagnification (65). They would beof little concern to people eating fish exposed to tributyltin.

During the two deployments which took place, in 1992, bags containing 50 mussels were placedat 17 sampling stations which corresponded with each of the 17 sediment stations (Figure B-11);a listing of the mussel transplant stations and associated sites are in Table C-6. Entire musselsminus the gonads, were homogenized and tested for metals and organics. Data on controls werenot provided. Cadmium was detected at 9.1 ppm at M-1 and M-2, manganese (21 ppm) andnickel (8 ppm) were also detected at mussel transplant station M-2. Similar contaminants weredetected at M-3. Manganese was detected at 26 ppm at M-17. PCBs were detected in musseltissues at M-9, at 0.65 ppm, and at M-10, 0.93 ppm. Most of the mussels deployed containedelevated levels of contaminants. ESAP mussel tissue results suggest that though Bay watersamples do not contain contaminants at levels of initial concern, the levels are sufficient to causebioaccumulation in organisms (66).

The EPA risk-based screening value (edible fish tissue, ppm wet weight) for cadmium is 11 (67). While cadmium levels detected in HPA deployed mussels were below the EPA level, cadmiumlevels at HPA may still be of concern if sensitive populations (e.g., pregnant women, lactatingmothers, or young children) are consuming shellfish caught on or near HPA. In generalpopulation, exposure to cadmium occurs primarily by eating crops grown in contaminated soiland seafood (68). Young children may be particularly sensitive to manganese in fish (69).

The Food and Drug Administration (FDA) tolerance level for PCBs is 2 ppm and the EPAscreening value for PCBs is 0.01 ppm. PCBs levels ranged from 0.17 ppm to 0.93 ppm. PCBsalso may be of health concern if sensitive populations are consuming shellfish caught on or nearHPA. Manganese levels were also elevated.

California has a state mussel watch program (SMW). The SMW is the State Water ResourcesControl Board's long-term marine water quality monitoring program. Actual field and laboratorywork is done by the Department of Fish and Game. The SMW program monitors long-termtrends in pollutant concentration in marine organisms, identifies locations where higher thanexcepted concentrations of pollutants exist, and provides the evidence needed to initiatefollow-up studies and actions to detect, correct, and clean-up sources of pollution (70, 71).

For the SMW program, California mussels (Mytilus californianus) are deployed for 4 to 6months at stations across the state and then analyzed for trace elements, pesticides, and PCBs(70, 71). There are numerous state mussel watch stations in the San Francisco Bay including astation at Hunters Point Naval Shipyard. Several areas around the bay have mussels withconsistently elevated PCBs, i.e., over 0.1 ppm. During 1988 and 1989, SMW PCB values at theHunters Point station were the highest in the bay, 272 ppb Aroclor-1254.

While the EPA screening values are preliminary indicators of human health risk and are designedto be flexible so that susceptible populations can easily be considered, the screening values EPAderives do not account for the most sensitive populations. EPA's screening value for PCBsassumes a very low consumption rate of 6.5 grams per day. This level is equal to a single 7ounce meal per month. Subsistence fishers may consume 20 times this level (72). EPA's valuesassume a body weight of 70 kg. Children and some adults, particularly Asians, are considerablysmaller. The screening value would need to be lowered even further to estimate a comparablelevel of risk for these people. EPA screening values are typically applied to fillet concentrationsand do not take into account consumption practices that may be practiced by some populationgroups such as consumption of fish livers.

PCBs are the only substances for which FDA has issued a tolerance level in fish (73). Fish abovethe tolerance level are deemed to be injurious to people's health and FDA may remove it fromcommerce. FDA action levels provide prosecutorial guidance to FDA but do not establish aproduct as injurious to health. The tolerance level for PCBs is not based solely on the protectionof health and levels even lower than 2 ppm may be unsafe for certain populations.

ESAP Sediment Analysis

In the second portion of the ESAP, surfical sediment analyses were evaluated. Toxicity testingon composited sediment samples was conducted on samples from 17 sediment stations (FigureB-12). Sediment sampling stations were selected to be representative of near shore sub-tidalareas of HPA. The stations were placed along the coastal perimeter of HPA from north to south,in proximity to the HPA areas of known and potential contamination Figure B-12 (30).

Surface sediments were collected as 10 separate grab samples across the sampling station surfaceall of which were later composited in the field (75). Subsurface sediments were collected as asingle core sample from each sediment station from which a discrete sample from between 30inches and 36 inches was collected for chemical analysis (66). The sediment toxicity samplingand analysis included the following: 1) toxicity testing of sediment samples; 2) physical testingwhich includes determination of grain size; 3) radioactivity testing of samples exhibitingradioactivity above background levels as determined for screening; 4) total organic carbon; 5)inorganics and metals; 6) pesticides and PCBs; 7) SVOCs; 8) VOCs; 9) and tributyltin.

During the off-shore sediment ESAP sampling that took place from April 8-16, 1992, mercury,lead, zinc, pesticides, PAHs, and Aroclor-1260 were detected (74). The higher values of metalswere encountered at S-4, S-12, S-13, and S-14. A listing of the areas associated with the 17sediment sampling stations is in Appendix C, Table C-6. Levels of mercury (5.6 ppm), lead (379ppm), and copper (851 ppm) above comparison values were detected during the off-shoresediment sampling (74). Low levels of organotins were detected (monobutyltin at 0.01 ppm,dibutyltin at 0.250 ppm, and tributyltin at 1.10 ppm).

Intertidal sediment sampling was conducted at IR-1/21, IR-2, IR-3, and IR-7 as part of the RI(61). Ten samples were collected randomly within each of the designated areas and thencomposited for analysis. Several metals and low levels of VOCs, SVOCs, PCBs, and pesticideswere detected at all the sampling areas. The highest lead levels were detected at IR-1/21. Contamination appears to decrease eastward with increasing distance from IR-1/21. Lead wasdetected as high as 42,400 ppm in IR-1/21 sediments, at 9,030 ppm at IR-2, at 99.4 ppm at IR-3,and at 1,300 ppm at IR-7. Cadmium was detected at IR-2 at 32.9 ppm; the comparison value is0.4 ppm (Figure B-12). Antimony was detected at 4,704 ppm at IR-3. PCBS were detected atboth IR-1/21 and IR-2 at 8.4 and 1.6 ppm respectively (74).

ESAP Bioassays

The third portion of the ESAP is an evaluation of HPA storm water runoff. Chronic bioassaytechniques were used on appropriate species. Chronic bioassay testing is more sensitive thanacute toxicity testing and addressed potential toxic side effects of exposure to HPA storm waterrunoff (75). In addition, contaminant concentrations in stormwater were determined by chemicalanalysis. Storm water toxicity testing included the following: 1) storm and bay water bioassaysinvolving a five dilution series; 2) inorganics and metals; 3) pesticides and PCBs; 4) VOCs; 5)SVOCs; 6) and tributyltin (76).

Tables C-7, C-8, and C-9 summarize the results of the stormwater, sediment elutriate, andsediment bioassays. The storm water runoff sampling points were the same as those used for thestorm water quality investigation. Many of the tests were inconclusive due to laboratoryproblems with controls and high oxygen demand (38).

Surface Water and Sediment

As part of the Stormwater Quality Investigation, storm drain sediment samples were collectedfrom each of the four stations on November 17, 1990. Pre-storm drain water samples werecollected from the four stations on November 16, 1990. Storm event samples were collected onDecember 15, 1990. A total of 44 water samples and 4 sediment samples were collected and anadditional 13 for QA/QC purposes (30).

There are a total of ten drainage areas, but only four drainage areas where sampled (drainageareas A, D, H, and E) for the ESAP. Stormwater sampling station SW1 is found within drainagearea D, a 35-acre area, and collects runoff from the Tank Farm and Building 901. Stormwatersampling station SW2 is found within drainage area H, a 33-acre area, which collects runoff fromthe Pickling and Plating Yard, the PCB Spill Area, IR-33, PA-37, and PA-44. Stormwatersampling station SW3 is found within drainage area A, which encompasses 200 acres, collectsstormwater from the Bay Fill area, the Scrap Yard, the Old Transformer Storage Yard, the PCBSpill Area, the Disposal Trench, the Old Commissary, PA-41, and PA-56. Stormwater samplingstation SW4, a 30-acre area, found in drainage area E collects runoff from areas PA-58, PA-28,and PA-29.

VOCs were detected at SW4 during all sampling phases. Sediment samples taken at SW4contained vinyl chloride at 14 ppm and PCB 1260 at 24 ppm; both were above comparisonvalues. PCB 1260 was detected at SW2 above the comparison value, but not at SW3 or SW1. Metals were detected above comparison values at SW1 and SW2 (Tables 11, 12, and 13).

During March 1992, nine stormwater/bay water samples were taken during the ESAPinvestigation (74). Lead at 247 ppb was the only contaminant found above a comparison value.


Table 11. Maximum Contaminant Concentrations in On-Site Stormwater Sediment

Comparison Value
Vinyl Chloride*140.04EMEGSW4
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from the Water Quality Investigation of Stormwater Drainage. Naval Station Treasure Island, Hunters Point Annex, San Francisco, California. June 13, 1991.

Table 12. Maximum Contaminant Concentrations in Pre-Storm Event Water

Comparison Value
Vinyl Chloride*20.2EMEGSW4
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from the Water Quality Investigation of Stormwater Drainage. Naval StationTreasure Island, Hunters Point Annex, San Francisco, California. June 13, 1991.

Table 13. Maximum Contaminant Concentrations During Storm Event Runoff and inStorm Drain Waters

Comparison Value
None - Comparison values not available
* Contaminants are Class A or B2 carcinogens per EPA IRIS database
Adapted from the Water Quality Investigation of Stormwater Drainage. Naval Station TreasureIsland, Hunters Point Annex, San Francisco, California. June 13, 1991.

Food Chain Summary

The limited sediment sampling conducted to date does not provide enough information to definethe extent of contamination. Until further sediment sampling has been conducted (specifically inareas were people may be subsistence fishing), ATSDR can not fully assess the sedimentcontamination at HPA and the potential for bioaccumulation of metals and PCBs.

The Navy's stormwater toxicity tests, bioassays and sediment analyses were inconclusive, butmany of the analyses indicate that several HPA areas appear to be toxic to the test organismsexposed to different environmental media. IR-1 and IR-2 sediments had higher levels ofcontamination than other areas. More toxicity tests and tissue and sediment analyses wouldbetter clarify the extent of contamination at or near HPA. Fish and shellfish tissue analyseswould help to indicate whether or not edible fish and shellfish are bioaccumulating contaminants.

The NOAA study of the San Francisco Bay for the area near Hunters Point, found that only a fewof the biological measures of effects were elevated relative to other areas studied, whichsuggested that conditions were only moderately toxic (50). Some of the biological measures ofeffects observed off Hunters Point were low prevalences of liver and kidney lesions in whitecroaker and liver lesions in starry flounder off Hunters Point, very high prevalences of kidneylesions of starry flounder off Hunters Point, significantly depressed scope of growth in residentmussels for Hunters Point, sediments throughout the area are moderately toxic to amiphods inhistorical tests, and some background ambient water samples are toxic to sea urchin sperm cells.

B. Off-Site Contamination

During the assessment of HPA, ATSDR searched the Toxic Chemical Release Inventory (TRI) todetermine if other potential chemical releases into the environment in the areas near HPA couldadversely affect the people at or near HPA. The TRI is an on-line database, maintained by EPA,that contains information (self-reported by chemical manufacturers and other industries) aboutmore than 320 different chemicals released into the environment. Data has been compiled for theperiod between 1987 and 1991.

A search of the TRI database was made to help determine if the contaminants of concern at HPAcould be coming from other industrial sources. There were no reports of pesticide containingchemicals released into the environment within the zip code areas of the Hunters Point District orthe Bayview area. There were releases of 1,1,1-trichloroethane, sodium hydroxide, sulfuric acid,aluminum oxide, hydrochloric acid, chlorine, styrene, and acetone into the air in the HuntersPoint/Bayview industrial area.

C. Quality Assurance and Quality Control

In preparing the public health assessment, ATSDR relies on the information provided in thereferenced documents. The Agency assumes that adequate quality assurance and quality controlmeasures were followed with regard to chain-of-custody, laboratory procedures, and datareporting. The validity of the analysis and conclusions drawn for this public health assessmentare determined by the reliability of the referenced information.

A portion of soil and groundwater samples taken at OUs I, III, and IV were invalidated due to aproblem with two state of California certified laboratories (77). Holding times for 1,100 sampleswere exceeded. Additional samples were taken and used in the IR investigation of OUs I, III, andIV. The Navy rejected all the formaldehyde samples for the air sampling study due to problemswith the cartridge media.

For the SCRS, soil samples were sent to TMA/Eberline in Albuquerque, New Mexico forradiological analysis. TMA/Eberline is accredited by the American Association for LaboratoryAccreditation in the field of testing and environmental sample analysis. EPA conducted aninter-laboratory analysis for 15 HPA soil samples. NAREL conducted the gamma spectroscopyon July 13, 1992. Ra-226 was the only radionuclide detected. Samples ranged from 0.57 to19,400 pCi/gram dry weight (79). There were discrepancies between NAREL's and Eberline'sreported values for two soil samples due to a laboratory reporting error and non-heterogeneoussamples matrices.

Six out of 11 of the ESAP bioassays were invalidated due to problems with controls, mortalityeffects from the diluents, and the use of bubbled oxygen to makeup for the lack of dissolvedoxygen. As a result of high ammonia and biological demand in the offshore sediments, theaddition of oxygen was required to run the bioassays (38). Test acceptability criterion forcontrols were not met for several of the bioassays.

D. Physical Hazards

Methane has been detected at several areas on base (Table 14). Methane represents a physicalhazard because it may cause explosions and it may displace air and cause asphyxiation.

The Navy follows site safety plans, uses gas monitoring equipment (e.g., organic vapor analyzers,oxygen meters, and explosimeters) and equipment certified (e.g., non-sparking) for an explosiveatmosphere when drilling in areas where the presence of methane is suspected. In 1989, as partof the solid waste air quality assessment test, the presence of landfill gases were tested for usingthree different methods: landfill gas migration monitoring, integrated surface sampling, andinternal landfill gas sampling.

For the landfill gas migration evaluation, three monitoring probes were installed around theperimeter of HPA to evaluate the possible off-site subsurface migration of land fill gas. Locations were choosen because of the proximity of the Industrial Landfill to the site boundary. Probes were used to collect samples of subsurface gas and obtain pressure measurements at theHPA perimeter. The sample from probe PP-02 located at the northern perimeter of the IndustrialLandfill, indicated the presence of methane at 56 percent. Methane was not detected in the othertwo samples. This may indicate migration of landfill gas. Subsurface pressure was 0.0 inches ofmercury for all the landfill gas migration probes.

Five SWAQAT locations were selected for the integrated surface sampling. The integratedsurface sampling technique measures gases immediately above the landfill surface and is used asan indicator of gases escaping from the landfill (78). Separate 50,000-square-foot grids wereplotted at each of the five SWAQAT areas. One continuous air sample was collected 3 inchesabove the ground surface along a standard sampling pattern. Methane was not detected in anysample.

Internal landfill gas sampling was performed to evaluate the composition of the landfill gaswithin the fill areas. Thirteen landfill gas characterization wells were installed throughout thefive SWAQAT areas at HPA. The wells were used to collect both subsurface gas samples andpressure measurements within the soils. Methane was detected in 7 samples at concentrationsranging from 0.5 to 83 percent (Table 14). A duplicate was taken of sample IG-7, sample IG-7D,which was lower than the initial sample possibly due to dilution of the duplicate sample with airduring sample collection (24).

Table 14. Internal Landfill Gas Measurements

Disposal TrenchAreaIG-41146
Bay Fill AreaIG-50.75
Oil ReclamationPondIG-7883
Oil ReclamationPondIG-7D659
Sub-Base AreaIG-13150.5
Harding Lawson Associates. Solid Waste Air QualityAssessment Test. Naval Station Treasure Island, HuntersPoint Annex. August 4, 1989.

During an ATSDR site visit, workers drilling monitoring wells detected methane gas and ceaseddrilling. Methane was detected at a concentration of 46% at IR-12 (Parcel E) when a shallowvadose zone well was installed (22). The lower explosive limit for methane is 5% and the upperexplosive limit is 15% (80). IR-1/21 and IR-12 are nearly contiguous to each other. The Navybelieves that the methane occurs in scattered pockets (81).

According to the Navy, methane occurrence is associated with the presence of the subsurfacedebris. Methane is natural byproduct of the degradation of solid waste landfills containing paper,wood, household trash, and other organic debris. Figure B-13 shows some of the areas where theNavy has detected methane. Methane was not observed in areas where there are no debris, withthe exception of one boring in the western part of IR-1/21 (Parcel E). Methane concentrationsmeasured at the time methane was encountered during drilling dissipated rapidly tonon-detectable concentrations, generally within minutes or hours (82).

The lateral extent of debris, and therefore potential methane pockets, is not defined on the northedge of IR-1/21 or on the north edge of IR-18 (Parcel B). At IR-1/21, the lateral extent of debriscan be estimated based on the history of filling at HPA. Debris was not used for fill at IR-1/21until 1958. The shoreline in 1948 is shown on Figure B-13; areas north of the 1948 shorelinewere filled with rock material from the bedrock ridge (as opposed to debris). The 1948 shorelineis estimated to represent the maximum northern extent of possible debris areas at IR-1/21 (82).

Physical hazards in the form of shipyard debris were observed by ATSDR at the Drum Storageand Disposal Yard and outside of the Power Plant. Crumbling seawalls were also observed byATSDR. This could present a physical hazard, from falling pieces of concrete, to future HPAoccupants using areas near the seawalls.

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