PUBLIC HEALTH ASSESSMENT
MCCHORD AIR FORCE BASE
PIERCE COUNTY, TACOMA, WASHINGTON
Figure 1. McChord AFB and Vicinity
Figure 2. Hazardous Waste Disposal Sites
at McChord AFB
Figure 3. Environmental Contamination
Study Areas at McChord AFB
Figure 4. On-Base Housing and
Off-Base Residential Areas
Figure 5. On-Base Drinking Water Wells
Figure 6. Area A
Estimated Extent of
Figure 7. WTA - Areas of
Figure 8. WTA - Approximate Extent
of Floating Fuel and Locations of
Figure 9. WTA - Surface Water and
Sediment Sampling Locations
Figure 10. Area D/ALGT -
TCE Contamination Plume
and Waste Sites
Background and Information on
(65 Sites by Area)
Sites 1, 2, 34, and 46
Study Area A is currently used for bulk jet fuel (JP-4) storage. That storage area, which is on thenorth-central part of the base, is bounded by the base property line and McChord Avenue to thenorth. It is bounded on the east by the Burlington Northern Railroad tracks. Major activities inArea A are currently limited to liquid fuels bulk storage and liquid fuels distribution using truckfilling stands immediately east of the railroad tracks. Figure 3 in Appendix A shows the sitelocations; Table B-1 lists information about the types of wastes disposed or spilled at Area A.
|1||Burial pit||Boiler Ash, industrial waste||1946-1956?|
|2||Milburn Pond landfill||Boiler Ash, industrial, domestic, construction, demolition||1957-1976|
|34||Tank farm area||Fuel tank sludge, fuel (JP-4 and leaded fuel) disposal; fuel spills||1956-?|
|46||Fuel (JP-4) spill||50,000-gallon JP-4 fuel spill; no remediation||late 1960s|
Site 1, a burial pit, and Site 2, Milburn Pond landfill, may have received large quantities ofindustrial wastes. The fuel storage in Area A (Site 34) consists of four aboveground JP-4 storagetanks with capacities ranging from 210,000 to 840,000 gallons. A 20,000- to 30,000-gallon drypit is outside the northwestern corner of the tank farm. According to the Phase I investigation,this pit has probably received waste fuel (Hazardous Waste Remedial Actions Program[HAZWRAP] 1989). Tank sludges have also been dumped on unlined ground outside the tankfarm fence. The practice of draining and drying aircraft fuel filters on a gravel pad west of andoutside of the tank farm was stopped in 1982. An oil/water separator and dry well dischargesystem in the northwestern corner of the storage facility have received discharge from stormdrainage within the bermed area of the tank farm. Water with an oily sheen was noted in the drywell during one investigation (Dames and Moore 1987). Waste fuels were not always separatedfrom the storm drainage before discharge into the dry well; those fuels may have infiltrated intothe soils (HAZWRAP 1989; CH2M-Hill 1982). The tank farm was upgraded in 1984; animpermeable liner was installed on all berms and on the floors of the containment cells.
Fuel spills have taken place at the tank farm, including a spill of 15,000 gallons of aviation gas(AVGAS) in 1973 and a reported spill of 50,000 gallons of JP-4 fuel in the railroad yard east ofthe tank farm in the late 1960s. Fuel was also spilled at the railroad yard (Site 46) during the late1960s; apparently, all of the spilled fuel infiltrated the ground.
Groundwater at Area A was monitored during five different studies. One study (HAZWRAP1989) also analyzed soil samples for contamination. During site hazard assessment (EBASCOServices Incorporated 1993), surface water and sediment samples within Milburn Pond weresampled.
During an investigation by Dames and Moore in 1987, subsurface conditions at Area A werefound to be highly complex and variable, causing concern about the possible movement off baseof the fuel contamination floating on the water table.
During the IRP Phase II, Stage 1 investigations, analysis of samples from three newly constructedmonitoring wells at Area A found that petroleum hydrocarbons were floating on the water tableimmediately west of the bulk fuel storage tanks. The main text of this public health assessmentcontains additional information about the Phase II, Stage I and 2 Studies. ATSDR has excludedthe Phase II data for Area A from this public health assessment because more recentenvironmental data are available from two other studies.
In February 1987, Dames and Moore published "Report on Restoration of Contaminated Area AFuel-Contaminated Groundwater at McChord AFB." The purposes of that investigation were tocollect and analyze data to define alternatives for cleanup of the floating hydrocarbons and toestimate the costs of the cleanup. Five monitoring wells installed during previous investigationsand seven wells installed in 1986 were sampled in June 1986 to determine the presence orabsence of hydrocarbons floating on the water-table surface. The samples were analyzed forbenzene, toluene, and xylene.
HAZWRAP published "Characterization of JP-4 Fuel Spill in Area A" in November 1989. Thepurpose of that investigation was to assess the nature and extent of fuel contamination at Area A. Four additional monitoring wells were installed at the northern end of Area A. Samples fromboth previously built and new monitoring wells were analyzed for volatile organic compounds(VOCs), total petroleum hydrocarbons (TPHs), and metals. All groundwater samples for metalsanalysis were filtered. Figure 6, Appendix A, shows the estimated extent of floating hydrocarbons during the summer of 1988.
Four additional monitoring wells were installed during site hazard assessment in February 1993at Sites 1 and 2. At Site 1, one well was installed upgradient (depth: 36 feet) and the otherdowngradient (depth: 44 feet). At Site 2, one well was installed upgradient (depth: 23 feet) andthe other downgradient (depth: 27 feet). Groundwater sampling was conducted in March 1993. Samples were analyzed for volatile and semi-volatile organic compounds, pesticides andpolychlorinated biphenyls (PCBs), inorganics, and total petroleum hydrocarbon (TPH)compounds. The concentrations of groundwater contaminants exceeding comparison valuesduring the three most recent investigations at Area A are summarized in Table B-2.
|Groundwater Contaminant|| Range of Levels|
|Dames and Moore|
BDL: Below detection limit.
Subsurface soil samples were collected at selected intervals from the borings for the newmonitoring wells installed during the HAZWRAP investigation. No VOCs were detected inthose samples, and the concentrations of metals were less than their respective comparisonvalues, except for arsenic. The concentration for lead at Area A is included in Table B-3 because no comparison values for that metal are currently available. The concentration of lead in the soil at Area A is similar to background concentrations found in other soil from the Western United States (ATSDR 1992).
Surface Water and Sediment
Surface water and sediment samples were collected at two locations within Milburn Pond(EBASCO 1993). Those samples were analyzed for volatile and semi-volatile organiccompounds, pesticides and polychlorinated biphenyls (PCBs), inorganics, and total petroleumhydrocarbon (TPH) compounds. Metals were detected at naturally-occurring concentrations. Comparison values are not available for surface water.
Sites 38, 40, 41, 47, 52, 53, and 55
Area B, which is the northern part of the industrial area at McCAFB, consists of seven liquidwaste disposal sites behind and along the aircraft maintenance facilities. Waste petroleum, oil,and other lubricants; spent solvents; and waste or spilled fuels are sources of contamination inthe area. Most of Area B has a cement cover; a few grassy areas exist. Currently, storm runoffdrains into Clover Creek after passing through industrial separating units (Air ForceOccupational and Environmental Health Laboratory [AFOEHL] 1990). Drainage of industrialwaste runoff into Clover Creek was untreated until 1948. Figure 3, Appendix A, shows the sitelocations; Table B-4 lists information about the types of wastes disposed or spilled at Area B.
|38||Liquid disposal/spill sitealong C ramp||Waste fuels and petroleum, oil, and lubricants (POL) disposal; 900 gallonsof 1,500-gallon spill in 1980 were recovered||1940s-1960s|
|40||Liquid disposal site||Waste POL; motor pool solvents||1951-1960s|
|41||Fuel (AVGAS) spill||Reported fuel-line leak undetected for up to 6 months; quantity unknown;no recovery||1965|
|47||Fuel spill at C ramp||Reported 25,000 gallons fuel (type unknown) leaked from undergroundpipe; no recovery||Unknown|
|52||Spill site, Bldg. 1173||Oil, synthetic lubricants, and hydraulic fluids||Unknown|
|53||Spill site, Bldgs.|
1147 to 1159
|Waste fuels, POL, and solvents; drainage through skimmer into stormdrainage ditch connecting to Clover Creek||Unknown|
|55||Spill area between Bldgs.1170 and 1164||Fuels, POL, and solvents||Unknown|
Groundwater at Area B has been analyzed during Stages 1 and 2 of the IRP Phase II Studies. Site hazard assessment of Sites 38, 40, 41, 53, and 55 in Area B was completed in June 1993.
During the IRP Phase II, Stage 1 investigations, five monitoring wells were installed that were completed in the surficial aquifer (maximum depth 102 feet). One well cluster, of which the deepest well was completed in the deeper aquifer, was also installed. The main report contains additional information about the Phase II, Stage I Study.
During Stage 2 of Phase II, no additional monitoring wells were built in Area A, but watersamples from the wells installed during the Stage 1 investigations were analyzed. Refer to themain text of this public health assessment for additional information about the Phase II, Stage 2 Study.
VOCs and metals detected in the groundwater exceeded comparison values during both stages ofthe Phase II studies; pesticides were detected at levels exceeding comparison values during theStage 2 study.
Two new monitoring wells were installed and sampled at Area B during the site hazardassessment. At Site 38, one new well (depth: 23 ft) was installed downgradient. Groundwaterwas sampled from the new well and from two existing upgradient wells. Samples were analyzedfor total petroleum hydrocarbons compounds and volatile and semivolatile organic compounds. No contaminants that were detected exceeded the comparison values.
At Site 55, one new monitoring well was installed downgradient. Groundwater was sampledfrom the new well and from an existing upgradient well. Samples were analyzed for totalpetroleum hydrocarbon compounds and volatile and semivolatile organic compounds. Nocontaminants exceeded the comparison values.
During site hazard assessment in 1993, three test pits were excavated to depths varying from 5 to10 ft for each of four sites (Sites 38, 40, 41, and 53). One soil sample was collected from thebase of each test pit. The samples were analyzed for total petroleum hydrocarbon compoundsand volatile and semivolatile organic compounds. No contaminants that were detected exceededthe comparison values.
Also, during site hazard assessment, three soil borings were completed to depths of 8 to 15 ft atSite 55. One soil sample was collected from each soil boring and analyzed for total petroleumhydrocarbon compounds and volatile and semivolatile organic compounds. No contaminantsthat were detected exceeded the comparison values.
Sites 12, 33, 37, 42, 45, 57, 58, 61, and 62
Area C, the middle portion of the industrial area at McCAFB, includes seven sites where wastepetroleum, oils, lubricants, solvents, and fuels were either spilled or disposed. Another site (Site33) was a former fire training area. In this public health assessment, Site 33 is also included inArea C because of geographic location and similar contamination. Most of Area C has a cementcover; a few grassy areas exist. Currently, storm runoff drains into Clover Creek after passingthrough industrial separating units (AFOEHL 1990). Drainage of industrial waste runoff intoClover Creek was untreated until 1948. Figure 3, Appendix A, shows site locations; Table B-5lists information about the types of wastes disposed or spilled at Area C.
|12||Landfill||Industrial and construction wastes, coal ash||1939-1952|
|33||Former fire fighter trainingarea||Waste fuel (AVGAS)||1940s-1950|
|37||Liquid disposal site|
along "D" ramp
|Waste fuels and POL||1940s-1960s|
|42||Liquid waste spill |
at refueling docks
|Waste POL and fuels||Unknown|
|45||Fuel spill between Hangars 1and 2||AVGAS spill of 2,000 gallons||1950s|
|57||Leach pit near Hangar 1||Industrial wastes, including POL, degreasers, other solvents, andelectroplating wastes||Early 1980s|
|58||Leach pit (acid dry well)||Industrial wastes||1950s-1970s|
|61||Leach pit between Bldg. 745and Clover Creek||Electroplating wastes||1953-1960|
|62||Dump pad and infiltrationarea||Plating tank sludges; drainage to Clover Creek||Unknown|
Groundwater at Area C has been analyzed during both Stages 1 and 2 of the IRP Phase II Studies. Site hazard assessment of Sites 12, 42, 57, 58, 61, and 62 was completed in June 1993. Twosites within Area C are included on the NPL as the Washrack/Treatment Area (WTA) Site. Contaminant information from the remedial investigation completed for that NPL site isaddressed separately (WTA Site).
During the IRP Phase II, Stage 1 investigations, four monitoring wells were installed that werecompleted in the surficial aquifer (maximum depth 103 feet). One well cluster, of which thedeepest well was completed in the deeper aquifer, was also installed. Refer to the main text of this public health assessment for additional information about the Phase II, Stage 1 Study.
During Stage 2 of Phase II, one additional monitoring well and four observation/recovery wellswere installed in Area A. Water samples from the wells installed during both Phase IIinvestigations were analyzed. Refer to the main text of this public health assessment foradditional information about the Phase II, Stage 2 Study. Pesticides, VOCs, and metals weredetected in the groundwater at levels exceeding comparison values during both stages of thePhase II studies.
Two new monitoring wells were installed and sampled at Area C during the site hazardassessment completed in June 1993. One well was installed upgradient (depth: 25 ft) and theother (depth: 33 ft) was installed downgradient of Site 12. None of the contaminants detectedexceeded the comparison values.
Subsurface soil samples were analyzed at Sites 42, 58, 61, and 62.
At Site 42, three test pits were excavated to a depth of 9 ft. One soil sample was collected fromthe base of each test pit; the three samples plus one duplicate were analyzed for total petroleumhydrocarbon compounds. No contaminants detected exceeded the comparison values.
At Site 58, one test pit was excavated to a depth of 6 ft in the acid leach pit. One soil sample wascollected from the base of the test pit and analyzed for total petroleum hydrocarbon compounds,and priority pollutant metals. No contaminant concentrations exceeded the comparison values.
At Site 61, one near-surface soil sample was collected from the base of the leach pit from 0 to 6in and analyzed for volatile and semivolatile organic compounds and priority pollutant metals. (ATSDR defines surface soil as soil 0-3 inches below the ground surface.) The concentrations ofcontaminants exceeding comparison values (or else not having comparison values) aresummarized in Table B-7.
At Site 62, one test pit was excavated to a depth of 4.8 ft. One soil sample was collected fromthe base of the test pit and then analyzed for volatile and semivolatile organic compounds andpriority pollutant metals. The concentrations of contaminant exceeding comparison values aresummarized in Table B-6.
At Site 57, a leach pit, the manhole cover was removed and one sample was collected from thebase of the leach pit which contained about three feet of wet sludge. The sludge sample wasanalyzed by the Toxicity Characteristic Leaching Procedure to determine characteristics forpotential disposal. Comparison values for sludge are not available. These metals were detected: cadmium (67 ppb), chromium (14 ppb), lead (190 ppb), and mercury (0.35 ppb).
Washrack Treatment Area (WTA)
NPL Site In Area C
Sites 54 and 60
The WTA site is in the industrial and operational activity areas associated with aircraftmaintenance and flight operation. The WTA was listed on the NPL in 1987. That site is thelocation of a washrack operation and includes the storm drainage infiltration ditches. Two IRPsites are in the vicinity of the WTA: Site 54, the washrack rinsate disposal area (two leach pits)where organic solvents used to clean airplanes were disposed; and Site 60, a plume of floatingproduct. Groundwater studies in the immediate WTA area have documented a layer of fuelfloating on top of the water table. That fuel layer is either diesel fuel or aviation fuel (AVGAS). Figure 3, Appendix A, shows the locations of the sites; Table B-8 lists information about the types of wastes disposed or spilled at WTA.
adjacent to washrack andincluding Industrial WasteWater Treatment Plant
|Solvents, alkaline-base detergents, paint removers, corrosion-removingcompounds, degreasers, waste oils, and solvents; drainage of wastes intoClover Creek untreated until 1948; in 1968, total flow to leach pit was8,000 gallons per day; problems with skimmer||1940s-?|
|60||Leach pit and storm drainageinfiltration ditches||Petroleum, oil, and lubricants||1950s-?|
Sites 54 and 60 were included as part of Area C in the two IRP Phase II investigations (Stage 1and 2) that were conducted in 1983 and 1984. Therefore, the environmental samplinginformation obtained from those investigations is included with Area C sampling information. Only the sampling information obtained during the Shannon and Wilson ConceptualHydrocarbon Recovery Plan (CHRP) for Area C (specifically, Site 60) and the WTA RI study forSites 54 and 60 is included here. Soil samples from two sites in the drainfield were analyzed bythe AFOEHL in 1983 for metals; those data are referred to in the IRP Phase II study, but theoriginal report was unavailable. Some of the non-NPL sites within Areas B and C were sampledfor environmental contaminants during site hazard assessment to determine whether remediationor additional investigation is needed.
The selected remediation described in the record of decision for this site includes extracting,collecting, and removing the floating fuel in the unconfined aquifer. Site 54 is included in thelong-term groundwater monitoring plan for the base.
Two separate investigations have been conducted specifically at WTA: CHRP study (Shannonand Wilson Inc. 1986) and the RI (EBASCO Services Incorporated 1992a). One of the purposesof the CHRP study was to define the location and extent of the hydrocarbon layer floating on thewater table at Area C (specifically, Site 60). Ten groundwater monitoring wells were installed tothe lowest point of the surficial aquifer. Three groundwater samples were analyzed for priority pollutants.
During the RI, the WTA area was investigated using geophysical techniques, groundwatersamples, surface soil samples, and subsurface samples. Field activities for the RI began in Julyand were completed in August 1991. Geophysical surveys (electromagnetic andground-penetrating radar) were part of the RI investigation of suspected source areas. Areas of suspected contamination are shown in Figure 7, Appendix A.
Three groundwater samples from the surficial aquifer were analyzed during the CHRPinvestigation for VOCs, base neutral/acid extractable organic compounds (BNAs), and metals.
During the RI, groundwater under the WTA was investigated by sampling the shallow and deepgroundwater wells (Figure 8, Appendix A). Three new shallow wells were installed near theleach pits; nine deeper wells were installed at three other locations. Samples of groundwaterwere collected from the 12 new and 14 existing wells during four quarterly sampling rounds. Samples taken during Rounds 1, 3, and 4 were analyzed for VOCs, TPHs, BNAs, pesticides,polychlorinated biphenyls (PCBs), and metals. During Round 2, all well samples were analyzedfor VOCs and metals; some were analyzed for TPHs, semi-volatile compounds, and polycyclicaromatic hydrocarbons (PAHs). Wells in the WTA area are screened in three of the fourdesignated aquifers.
|Groundwater Contaminants||Range of Levels |
|Total noncarcinogenic PAHs||394-9,280 |
|Total carcinogenic PAHs||BDL-1.70||1990-1991||EBASCO RI||None||EPA-Carcinogens|
- BDL: Below detection limit.
|Groundwater Contaminants||Range of Levels |
- BDL: Below detection limit.
Near-Surface Soil (0-6 inches)
No soil samples were analyzed during the CHRP investigation, but hydrocarbon-stained soilabove the water table was encountered during installation of six of the monitoring wells duringthis study.
The 14 soil locations sampled at WTA during the RI were chosen because of previous aerialphoto data, information on past waste disposal practices, results of geophysical surveys, and fieldreconnaissance of the site. Twelve samples were collected (at depths from 0-6 inches)representing the 14 locations (two were composite samples). (ATSDR defines surface soil assoil 0-3 inches below the ground surface.) The soil samples were analyzed for VOCs, TPH,semi-volatile compounds (including PAHs), pesticides, PCBs, and metals. None of the detectedcontaminants, except arsenic, were at levels exceeding their respective comparison values. Theconcentration for lead is included in Table B-11 because comparison values for lead are notcurrently available.
|Arsenic||1-110||0-6 inches||1990-1991||EBASCO RI||0.4||CREG|
|Lead||3.3-439||0-6 inches||1990-1991||EBASCO RI||None||EPA-Carcinogen|
Subsurface soil samples from two sites in the drainfield were analyzed in 1983 by the AFOEHLfor metals. The original data were not available, but were referred to in the Phase II, Stage 1study. High levels of some heavy metals were detected in soils one foot below the groundsurface during the AFOEHL study, but those levels were not duplicated during the RI. Sixsubsurface soil samples were collected during the RI for chemical analysis in and around thesuspected source areas at WTA. The soil samples were analyzed for VOCs, TPHs, semi-volatilecompounds (including PAHs), pesticides, PCBs, and metal. None of the detected contaminants,except arsenic and cadmium, were at levels exceeding their respective comparison values. Leachpit samples accounted for 39 of a total of 40 detections. The total concentrations ofnoncarcinogenic PAHs are shown in Table B-12. The concentration of lead in the soil is alsoincluded in Table B-12 because comparison values for the metal currently are not available.
|Arsenic||up to 2.7||6||1990-1991||EBASCO RI||0.4||CREG|
|Cadmium||up to 23.8||6||1990-1991||EBASCO RI||0.4||EMEG-Pica Child|
|Total Noncarcinogenic PAHs||BDL-19,700||6||1990-1991||EBASCO RI||None||None|
- BDL: Below detection limit.
Surface Water and Sediment Samples
During the RI, surface water and associated sediment samples were collected from threelocations in Clover Creek, the surface water body associated with the site. Clover Creek is aperennial stream just west of WTA that provides the only surface water drainage for McCAFB. Samples were collected during three of the four sampling rounds. Three surface water samplesand three sediment samples were collected for each water and sediment sampling round at thelocations shown in Figure 9, Appendix A. The surface water samples were collected from theapproximate center of the drainage route and as close to the bottom as could physically bereached. Surface water sediment samples were collected at the same locations as the surfacewater samples. Both types of samples were analyzed for VOCs, TPHs, semi-volatile compounds,PAHs, and metals (antimony, arsenic, beryllium, cadmium, chromium, cobalt, and manganese). Surface water and sediment sampling results are included in Tables B-13 and B-14.
|Contaminant||Range of Levels|
|Total carcinogenic PAHs||BDL-0.2||1990-1991||EBASCO RI||4||RMEG-Child|
- BDL: Below detection limit.
|Contaminant||Range of Levels |
|Total carcinogenic PAHs||BDL-14.5||1990-1991||EBASCO RI||None||EPA-Carcinogen|
|Total noncarcinogenic PAHs||0.38-11.57||1990-1991||EBASCO RI||None||None|
- BDL: Below detection limit.
(Although several metals were detected in the groundwater at WTA at levels exceeding theirrespective comparison values, only antimony and arsenic were detected in the surface water atClover Creek at levels exceeding comparison values for drinking water.)
Area D/American Lake Garden Tract (ALGT) Site
Sites 4, 5, 6, 7, 26, 35, 39
The Area D/American Lake Garden Tract (Area D/ALGT) site includes the off-base ALGT, aresidential area, and the southwestern part of McCAFB, designated Area D. The residential arealies southwest and immediately adjacent to Area D. Area D is bounded by Interstate 5 and PorterHills on the northwest and north; by the McChord AFB ammunition storage area, "A" Street, andBurlington Northern Railroad tracks on the east; and the Fort Lewis Logistics Center on the southand southwest. The total site area comprises approximately 1,280 acres, of which about 940acres is part of McChord AFB and about 340 acres is in the adjoining ALGT. The WhisperingFirs Golf Course was built over the landfills in Area D. The first nine holes of the golf coursewere built in the 1950s; the second nine holes were added, east of the first nine, in the early1970s.
Seven of the potential sources of contamination identified in the IRP Phase I records search wereinvestigated as part of the Area D/ALGT NPL site in the RI. Figure 3, Appendix A, shows thesite locations; Table B-15 lists information about the types of wastes disposed or spilled in this area.
|4||Gravel pit||Rubbish, garbage, and industrial wastes||1941-1978|
|5||Landfill under golf course||Large quantities of hazardous wastes, including waste oil and fuel||1951-1967|
|7||Landfill under golf course||Industrial, domestic, and construction wastes||1967-1972|
|26||Ordnance disposal||Residue from ordnance deactivation; 500 live grenades were reported tohave been buried in area||1943-1956|
|35||Liquid radioactive disposalwell (depth unknown)||Washwater from decontamination of radar components, fluorescent dials,possibly medical waste liquids; all disposed down a well||1950s|
|39||Liquid waste disposal siteadjacent to golf course||Waste fuel (JP-4), solvents, and POL were burned||1956-1960|
Contamination in the McChord ALGT area was first identified in April 1983. A local residenthad complained of contaminated groundwater from her domestic well; water from the well wasfound to be contaminated with TCE and trans-1,2-DCE. In 1983, EPA determined that severalother private wells in ALGT also were contaminated with TCE and trans-1,2-DCE (ATSDR1992e). Although the trans isomer was believed to be the 1,2-DCE isomer in the early 1980sstudies, the DCE contamination later was determined to be cis-1,2-DCE (EBASCOEnvironmental 1991a). Neither isomer is classified as a carcinogen; the cis isomer is slightlymore toxic than the trans isomer. Another study conducted by EPA indicated the presence ofTCE and cis-1,2-DCE in groundwater samples from monitoring wells installed in that portion ofthe ALGT (Ecology and Environment Inc. 1984). The contamination was later confirmed byadditional monitoring well installation and sampling during studies under the IRP. The off-baseinformation described here is discussed more fully in the off-base contamination section of themain text of this public health assessment.
The Area D/ALGT site was proposed for the NPL in September 1983 and was placed on the listin September 1984. The Air Force, EPA, and the Washington State Department of Ecologyentered into a federal facility agreement in August 1989, which governs the conduct of theinvestigation of NPL sites on McChord AFB.
Soil contamination still exists at Sites 5 and 39 and 7; all are former landfills under the golfcourse (EBASCO Environmental 1991a). (Because of proximity, Sites 5 and 39 are addressed asone site in the RI.) The RI reported that secondary sources of TCE and cis-1,2-DCEcontamination appear to be acting as a continuing source of groundwater contamination. None ofthe RI investigations located any of the secondary sources, but higher contaminant concentrationsin some of the wells indicated their presence.
The ROD states that the seven IRP sites within Area D do not require source control. Site 5 will remain active to track the remediation of the aquifer; the six other IRP sites have been proposed for "no further action" (NFA).
One of those NFA-proposed sites is Site 26, the Ordnance Disposal Area. Site 26 is near the golfcourse and, although part of it is fenced as a part of the active and patrolled ammunition storagearea, most of it is not. In 1972, a metal detector survey was conducted at the site for residualdebris remaining from historic ordnance disposal (EMB 1991b). Another metal detector surveythat was conducted during the RI addressed only areas that were readily accessible; most of thesite is covered with dense vegetation (EBASCO Environmental 1991a). Many items weredetected, uncovered, and identified for appropriate disposal. Among the items detected werethree nose fuses for 2.75-inch-high explosive fragmentation bombs and several grams ofexplosive material loose in the soil within some fusing. The results of the survey indicated thatperhaps one pile of 2.75-inch-high explosive ordnance was improperly detonated from thebottom, resulting in spread of the material. The area undoubtedly contains additional unexplodedordnance and explosive material not located at the time of this survey (EBASCO Environmental1991a). McCAFB believes that Site 26 has been comprehensively surveyed and that nearbyBaxter Lake remains the only location within the site that has not been traversed with metaldetectors (EMB 1991b). McCAFB has proposed this site for no further action and inclusionwithin the Area D/ALGT long-term groundwater monitoring program.
Chemical analyses of groundwater were conducted for Area D during both stages of the IRPPhase II Study. During the RI for Area D/ALGT, groundwater sampling was conducted both onbase (Area D) and off base (ALGT). The on-base environmental sampling results are discussedhere; the off-base sampling results are discussed in the main text of this public health assessment. In addition to the groundwater data, sampling data are also available in the RI for soil, surfacewater, sediment, and soil gas. In January 1992, some of the wells used during the RI wereresampled and analyzed for VOCs as part of the first round of the continuing monitoring process.
Soil gas surveys were performed during the RI to help characterize the types and extent ofcontamination in the soil. A total of 256 environmental samples from seven suspected sourceareas (Sites 4, 6, 7, 5&39, and three places at Site 26) were analyzed in the field for sixcontaminants (TCE, trans-1,2-DCE, cis-1,2-DCE, PCE, benzene, and toluene). TCE andcis-1,2-DCE contamination is listed by site in Table B-16.
|Site||Number of Locations|
|No. of Detections||(ppb)||No. of Detections||(ppb)|
- BDL: Below detection limit.
A methane screening also was performed at the Site 6 landfill during the RI. OVA andexplosimeter results suggested that methane might be migrating from the landfill at Site 6 easttowards a day care center; northeast towards the eastern side of another building (SAGE) next tothe gas fuel tanks; and south towards the Fort Lewis (EBASCO Environmental 1991a). Additional field investigations were conducted as part of the RI to further characterize anymethane migration from this landfill. These results were discussed in an RI addendum reportbecause they were not available when the RI was made final (EBASCO Environmental 1991f). In May 1990, two sets of double gas migration probes were installed on the margins of the SAGELandfill. The gas migration probes were sampled twice in 1991 for methane and other VOCs. No methane was detected in any of the probe samples during either sampling round; VOCs didnot exceed 1 ppm in any samples.
The on-base (Area D) groundwater contamination in the Area D/ALGT Site is discussed here;the off-base (ALGT) contamination is discussed in the main text of this public health assessment. The IRP Phase II, Stages 1 and 2 base-wide groundwater studies have been described in the mainreport. In Area D, two monitoring wells were sampled during Phase I, Stage 1; three additionalmonitoring wells were installed and sampled during Phase I, Stage 2. ATSDR has excluded thePhase II groundwater contaminant data for Area D/ALGT from the public health assessmentbecause more recent environmental data are available in the RI and in a 1992 technicalmemorandum.
During the RI, 45 previously installed monitoring wells, 73 newly installed monitoring wells, andsix base water supply wells were sampled. No private wells in ALGT were sampled during theRI. Fifty-seven of the 73 new wells were installed as shallow wells to investigate thecontamination in the unconfined aquifer. All groundwater samples were analyzed for TCE andthe cis- and trans-isomers of cis-1,2-DCE. A subset of the samples were also analyzed for thefull set of VOCs. Besides VOCs, 17 groundwater samples were analyzed for metals and cyanide,acid/base/neutral extractable compounds, pesticides, and PCBs. A subset of the 17 samples wasanalyzed for organophosphorus pesticides. One sample from the monitoring well closest to theradioactive disposal well (Site 35) was also scanned for gross alpha, gross beta, Cs 137, Ra 226,K 40, Th 228, and Th 232. When duplicate samples were taken from a well during a samplinground, the results were averaged. The monitoring well samples from the ALGT residential areawere tested only for TCE and cis-1,2-DCE.
The final groundwater sampling for the RI was completed in September 1990. Twenty of themonitoring wells sampled during the RI were resampled for full-range VOC analysis in January1992 to determine if the TCE and cis-1,2-DCE plumes had changed or spread. Two of the 20wells are in the ALGT. Groundwater contaminant concentrations in Area D exceedingcomparison values are shown in Table B-17. Almost always, the 1,2-DCE detected was found tobe the cis-isomer. Figure 10 shows the TCE contamination plume and waste sites. Site-specificconcentrations of TCE and cis-1,2-DCE in groundwater are listed in Table B-18.
|Groundwater Contaminants||Range of Levels|
|Vinyl Chloride||BDL-1.8||1990-1991||EBASCO RI||0.2||EMEG-Child|
- BDL: Below detection limit.
- BDL: Below detection limit.
Background Near-Surface Soil Samples
Background soils were sampled at 27 locations around McCAFB and analyzed for metals. Background samples were taken from the surface to 6 inches below, except for one boring forwhich five samples were analyzed at varying depths to 19.5 feet. (ATSDR defines surface soil assoil 0-3 inches below the ground surface.) The locations were selected where there appeared tohave been no disturbances during the past several decades that might contaminate the samples. The concentration of arsenic in all 25 samples (ranging from 2.6-18 ppm) exceeded thecomparison value (0.4 ppm, CREG). No other comparison values were exceeded. Themaximum concentration of lead was 214 ppm; no comparison value is available for lead.
Thirty hollow-stem auger boreholes were drilled and sampled. The locations selected wereprimarily from areas with high contaminant concentrations during the soil gas survey.
All 86 subsurface soil samples were analyzed for TCE, cis-1,2-DCE, and trans-1,2-DCE. Nosurface samples were analyzed. Samples were analyzed for full volatile gaschromatography/mass spectroscopy (GC/MS) analysis whenever field investigations indicatedthe existence of possible contamination, such as visible staining and detection of organic vapor emissions.
No VOCs were found at concentrations exceeding their respective comparison values. Althoughseveral semi-volatile compounds and pesticides were detected, the concentrations did not exceedtheir respective comparison values.
Eight source area subsurface soil samples were analyzed for metals. The concentrations ofmetals in those samples were less than the maximum values determined for the backgroundsamples, except for cadmium, mercury, and zinc. The concentrations of those analytes were notabove their respective comparison values. All source area samples were taken at various depths, ranging from 12.5 to 20.0 feet below the surface.
Radioactive parameters (gross alpha, gross beta, Cs 137, Ra 226, K 40, Th 228, and Th 232) forsoil samples from five depths of a boring at Site 35 were checked for possible residualcontamination remaining from disposal of low-level radioactive waste. Radioactivitymeasurements made during drilling and the results of the analyses do not indicate anyradioactivity other than that occurring naturally.
Surface Water and Sediment
Surface water and sediment samples from seven water bodies in Area D were analyzed for TCE,cis-1,2-DCE, metals, and pesticides. No comparison values are available for surface water. Metals were detected at naturally-occurring levels. The concentrations of lead in sedimentranged between 2.8 and 318 ppm.