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APPENDIX F
REVIEW OF CHEMICAL DATA FOR
SOIL AND GROUNDWATER SAMPLES PARCELS I AND II
Foster Wheeler Environmental Corporation (Foster Wheeler) reviewed tables (Tables 4, 5, 6A, and 6B from Earth Tech. 1997, attached) summarizing chemical data from soil and ground water samples collected dining the months of February and March 1997 firom Parcels 1 and II at the NASA Industrial Plant, Downey, California. The soil and groundwater sampling program was performed by Earth Tech on behalf of Boeing Aerospace and NASA. In addition, Foster Wheeler reviewed the soil boring logs produced from the field effort. Table 4 identifies the chemical analyses performed on soil
and groundwater samples. Identified below are our observations based on our review of these tables and soil boring logs.
PARCEL 1
Soil samples from twelve soil borings had detectable concentrations of volatile organic compounds (VOCs). Detectable concentrations of VOCs were also identified in groundwater at four Hydropunch borings. Table 6A identifies the borings and analyte concentrations. Figure 1 attached shows the location of the soil borings.
1. Soil sample data obtained from Parcel 1 suggests that shallow soil samples [about 5 to10 feet below ground surface (bgs)] across the area are impacted with low concentrations of chlorinated solvents, such as methylene chloride (MC), acetone, and tetrachloroethene (PCE). Except for two locations (SB-6 and SB-11)VOC concentrations did not exceed their respective Preliminary Remediation Goals (PRGs) for residential and industrial soils that have been developed by the United States Enviromnental Protection Agency (USEPA, 1996, August). In another area (SB-13), VOC concentrations were below the PRGs but exceeded the Soil Cleanup Screening Level (SCSL) of49.9 micrograms per kilogram (ug/kg) for PCE, estimated using the criteria developed by the California Regional Water Quality Control Board, Los Angeles Region (RWQCB, l996, May). Soil remediation is typically required for sites where analytes exceed their respective PRGs and/or SCSLs.
2. Soil borings SB-6 was drilled north of Building 25 in an area where a 1942 Vultee drawing identifies four underground storage tanks (USTs), three, 1000 gallon waste oil USTs and an existing, larger UST that was used to store wastewater and possibly solvents. Building 25 was used at that time for paint and solvent storage. Sometime thereafter, the building was used for miscellaneous equipment storage. Information on the use and ultimate disposition of the USTs was not located through the record review. Based on verbal communication with Earth Tech a geophysical investigation performed in the area did not locate the USTs.
Three soil samples were obtained from soil boring SE-6 at depths of about 4-6 feet,11-13 feet, and 13-15 feet bgs. Soils beneath the area are described as silts with thin layer of silty sand. A clay layer was encountered at a depth of 15 feet bgs in boring SB-5, located about 10 feet north of SB-6. The 4 to 6 feet bgs sample from SB-6 only had detectable VOC concentrations of acetone at 65 ug/kg. The 11-13 feet bgs soil sample had detectable concentrations of eight VOCs with the analyte of interest being benzene at 120 ug/kg. PCE and acetone were not detected at or above their respective detection limits of 5 ug/kg and 50 ug/kg, respectively. Elevated VOC concentrations were identified in the 13-15 feet bgs soil sample ranging fiom greater than 6,000 ug/kg (sec-butylbenzene) to 489,000 ug/kg (total xylenes) (Table 6). Benzene was detected in this sample at 11,500 ug/kg. Acetone was not detected at or above its detection limit of 25,000 ug/kg. PCE was originally identified by Advanced Technology Laboratories at 40,200 ug/kg in this sample. The analytical laboratory has subsequently indicated that the PCE concentration was a result of laboratory contamination, and represented residual PCE in the column that was carried over from analyzing the 8-l0 feet bgs sample from SB-11. The laboratory has subsequently indicated that PCE was not detected at or above a detection limit of 2,500 ug/kg. Total extractable petroleum hydrocarbons were detected in SB-6 at 8, 100 milligrams per kilogram at an unspecified depth.
Excluding PCE, the analytes detected in the 13 to 15 feet bgs soil sample from SB-6, are common constituents in high octane gasoline fuels, however, the ratio of benzene to toluene, ethylbenzene and total xylenes does not appear to be representative of a typical gasoline fuel. Analytes, such as naphthalene, isopropylbenzene,
n-prapylbenzene, 1.,2,4-benzene, n-butylbenzene, and sec-butyibenzene, are identified as being used as solvents in the "Handbook of Environmental Data on Organic Chemicals" (Verschueren, 1983). Interviews with Rockwell personnel and our record review indicate that naphthalene, acetone, PCE, methylethyl ketone, and other solvents, have been used at the site. Elevated VOC concentrations at depth and not at shallower depths appear to suggest that the source of these elevated VOCs are nearby and that they have migrated laterally on a less permeable layer, i.e. a clay.
Soil boring SB-5, located about 10 feet north of boring SB-6, also had three soil samples collected (4-6 feet, 9-11 feet and 13-15 feet bgs). Except for low concentrations of PCE (9.2 ug/kg) at 4-6 feet bgs, the VOCs were not detected above
their respective detection limits. This suggests that the VOC plume at SB-6 does not extend northward to SB-5. Additional horizontal and vertical delineation of VOC impacted soils in the area of SB-6 are needed.
3. Soil Boring SB-II was drilled immediately adjacent to a sump (about 3 feet square) located inside the western half of Building 244. This portion of the building was used at one time for chem mill operations in the late 1950s and early 1960s. Numerous aboveground chemical processing tanks were located in the area and overflow from these tanks discharged to a floor ditch that ultimately drained to the sump. These operations were removed in the mid-1970s. The area is currently vacant, except for the sump which is filled with sediment and covered with a metal plate.
Two soil samples (about 4-6 feet and 8-10 feet bgs) were obtained fiom SB11. Soils encountered were described by Earth Tech as a silt (fine grained sediment that typically has a low permeability). PCE concentrations in the 5 foot and 10 foot sample were identified at 2,676,000 ug/kg and 11,000 ug/kg, respectively. Initial analytical laboratory data had indicated that the 10 foot sample did not have detectable concentrations of VOCs. Upon further examination, these data were revised by the laboratory to the 11,000 ug/kg PCE. The horizontal andvertical distribution of these impacted soils has not been identified.
4. Soil Boring SB-13 was drilled adjacent to Sump 30, located east of Building 277. This sump consists of five compartments that received overflow from chemical processing operetions in Buildings 276 and 277. Discharges from this sump were eventually treated at the wastewater treatment unit, Building 299.
Two soil samples were collected from SB-13 at depths of 4-6 feet and &10 feet bgs. Soil beneath this area is described using visual estimates as a silt with clay that has about 15 to 30% clay in the soil (actual percentage of silt and clay would require a hydrometer test for verification). PCE was detected in the soil samples at 110 ug/kg and 140 ug/kg, respectively. Estimates for SCSL for PCE in these soil samples was estimated by using a 70% silt and 30% clay mixture that is located about 35 feet from groundwater (estimated at 45 feet bgs). An attenuation factor for PCE was calculated at 49.9 ug/kg for soils in this boring. This just means that soils at or below this concentration can be left in place without posing a significant threat to groundwater beneath the site. The horizontal and vertical extent of PCE in the soils beneath the area of SB-13 have not been identified.
5. Groundwater beneath Parcel 1 was identified at about 45 feet bgs. Rockwell data collected south of Parcel 1 suggest that groundwater flows toward the south to southwest. Four Hydropunch groundwater samples were collected beneath Parcel 1, based on the groundwater flow direction Soil Boring SB-35 was located at the northeastern conner of Parcel 1 in the presumed upgradient direction, and Borings SB-19, SB-20, and SE-24 were located south of Building 001, in the presumed downgradient direction (Table 6B). Chemical processing and degreasing sumps were identified in Building 001 during the record review. Borings SB-19 and SB-20 were located downgradient of these sumps. Boring SB-24 was located nearby a drywell that was used as part of the Navaho missile program Boring SE-35 was located in an area that appeared to be vacant throughout most of the historical operations at the NASA Downey facility. Periodically the area was used to park vehicles and possibly to store equipment.
Low concentrations of solvents, namely acetone and methylene chloride were identified in soil samples from 20 to 40 feet bgs in borings SB-19 and 20 and trichloroethylene (TCE) at 54 feet bgs in boring SB-35. Soil samples from SB-24 did
not contain detectable concentrations of VOCs. Groundwater samples from all four borings had detectable concentrations of VOCs, namely TCE. TCE in the presumed upgradient boring, SB-35 was at 240 micrograms per liter(ug/L). TCE was identified in the presumed downgradient groundwater samples from SB-19 at 250 ug/L, SB-20 at 150 ug/L, and SB-24 at 48 ug/L. Based on the presumed groundwater gradient and the absence of TCE in shallow soil samples beneath the site, it appears that the TCE may originate from an off-site, upgradient source. Additional data describing the direction of groundwater how and the distribution of VOCs in the groundwater would be needed to confirm this hypothesis. Other VOC concentrations in groundwater were relatively low, except for cis-1,2-dichloroethene (cis-1,2-DCE) concentrations in
borings SB-19 (22 ug/L), SB-20 (24 ug/L), and SB-24 (6.5 ug/L). TCE and cis-l, 2-DCE concentrations in groundwater exceeded California Primary Drinking Water Standards, Maximum Contaminant Levels (MCLs) of5 ug/L and 6 ug/L, respectively, as provided in Title 22, California Code of Regulations (CCR). It is our understanding that the first water bearing zone beneath Parcels 1 and Il is not being used for drinking water. However, under the California Water Code this shallow groundwater is still considered to have a beneficial use and contaminants in the groundwater have the potential to impact deeper, aquifers that are used for drinking water sources.
Parcel II
1. Soil samples from four soil borings had detectable concentrations of VOCs. Detectable concentrations of VOCs were also identified in groundwater at two Hydropunch borings. Table 6A identifies the borings and analyte concentrations.
Figure 1 shows the location of the soil borings.
2. Soil sample data from soil borings in Parcel II did not exceed the USEPA PRGs and the RWQCB SCSLs. Low concentrations of PCE were identified in soil samples from borings SB-21 (13 ug/kg and 16 ug/kg) and SB-22 (9.3ug/kg and 11 ug/kg) at 4-6 feet and 8-10 feet bgs. Soil Borings SB-21 was located east of Building 6, just east of sump 10. Soils underlying this are comprised of silts. Boring SB-22 was located near the vicinity of a former incinerator, that appeared to be in operation from the 1930s to early 1960s. Soils beneath this area are described as clayey silts/silty clays
(about 50:50 ratio of silt and clay).
Acetone was identified in the 35 feet bgs sample in SB-34 (62 ug/kg). Boring 34 is located south of Buildings 6 and 290. TCE was detected in soil samples from SB-25 just above groundwater at depths of 40 feet bgs (17 ug/kg) and 43 feet bgs (95 ug/kg). Boring SB-25 is located southwest of Building 280.
Based on the soil data reviewed and the locations investigated, additional characterization of soils within Parcel II does not appear to be needed at this time.
3. Hydropunch groundwater samples obtained from downgradient soil bofings SB-25 and SB-34 had detectable VOC concentrations; TCE and cis-1,2-DCE concentrations exceeded their respective MCLs. The groundwater sample from SB-25 had concentrations of TCE at 320 ug/L and cis-1,2-DCE at 11 ug/L. The groundwater sample at boring SB-34 had concentrations of TCE at 29 ug/L. Cis-1,2-DCE was not detected in boring SB-34; however, low concentrations of other VOCs were detected, such as, ethylbenzene (55 ug/l), isopropylbenzene (280 ug/L), naphthalene (7.7 ug/L),
n-propylbenzene (8.0 ug/L), 1,2,4-trimethylbenzene (42 ug/L) and total xylenes (72 ug/L). These compounds may have been used as solvents during the course of operations in Buildings 6 and 290. Additional information on the direction of flow and the distribution of VOCs is needed for groundwater beneath Parcel II.
Conclusions
Low concentrations ofVOCs were identified in Soils beneath Parcels 1 and II, except in a few areas, as discussed below. PCE was identified in soil samples beneath Parcels 1 and II; however, PCE was not detected in the six groundwater samples obtained through this investigation. TCE was not identified in soil samples from the 34 soil borings drilled for
this investigation. The TCE concentrations detected in the soil sample collected at 54 feet bgs from boring SB-35, appears to have been impacted by TCE in the groundwater. Anaerobic degradation of PCE results in TCE and subsequently in cis- 1,2 DCE. Insufficient data exists to verify that anaerobic degradation is occurring in the
groundwater beneath the site. A more plausible source for the TCE beneath the site is an upgradient, off-site regional source for the TCE. A better understanding of the hydrogeologic flow regime and the distribution of VOCs beneath the site is needed to assess the potential off-site and on-site sources to impacted groundwater.
1. Additional information is needed on the vertical and horizontal extent of VOC impacted soils in the areas of SB-6, SB-11 and SB-13. Geophysical data for the possible USTs near boring SB-6 were not reviewed. The status of these USTs needs to be better defined.
An interim source removal action may be considered to mitigate VOC impacted soils in the area of SB-6 and SB-11, however, without proper delineation of the impacted soils and the volume of impacted soils, the level of effort and costs associated with accomplishing the removal action cannot be estimated. In addition, excavations that occur adjacent to the structural footing of buildings may require costly shoring.
2. Elevated VOC concentrations in soils beneath the areas of SB-6 and SB-11 may have migrated vertically to groundwater. The groundwater in these areas needs to be evaluated for the presence of VOCs.
3. A better understanding is needed on the hydrogeologic flow regime and the distribution of VOCs in the groundwater beneath Parcels 1 and II. Monitoring wells are needed to better characterize the site. At least two upgradient wells are needed to identify potential off-site VOC contributions to groundwater beneath Parcels 1 and II.At least three downgradient monitoring wells are needed to assess the distribution of VOCs in the groundwater beneath Parcels 1 and II and the potential contribution to off-site contamination. Additional monitoring well within Parcel 1 will further facilitate the understanding of the distribution of VOCs beneath Parcels 1 and II. Groundwater monitoring data (elevation and chemical data) obtained fiom these wells should be coordinated with monitoring well information obtained by Rockwell south of Parcel III from the remediation program being performed at former USTs 11 and 22. Future monitoring wells that are installed at Parcel 1 and II for this project should be surveyed to a common benchmark and datum, such as the California statewide coordinate system and mean sea level. Rockwell's monitoring wells should be tied in with these survey coordinates so that their data can be tied in with Parcel 1 and II.
4. We recommend that RWQCB protocol for collecting samples and for analyzing and reporting chemical data be adhered to for future soil and groundwater investigations performed at Parcels 1 and II. We recommend that a workplan be prepared which identifies acceptable field protocol and laboratory detection limits for samples so that the objectives for the fieid investigation are accomplished. We also recommend that sufficient review time for the analytical data be provided to the environmental consultant and the analytical laboratory so that reporting errors and laboratory
inconsistencies are caught and eliminated, prior to the dissemination and distribution of the data. We recommend that the analytical laboratory used for this project be on the RWQCB approved list and that Foster Wheeler personnel assist in confirming the laboratory selected.