PUBLIC HEALTH ASSESSMENT
EL DORADO, UNION COUNTY, ARKANSAS
This section of the public health assessment describes environmental sampling conducted previously at the site andidentifies contaminants of concern found in specific environmental media. The selected contaminants are evaluated insubsequent sections of the health assessment to determine whether exposure to them has public health significance.
ATSDR selects contaminants for further evaluation based upon the following factors:
- concentrations of contaminants on and off the site;
- sampling locations and frequency, field data quality, and laboratory data quality;
- comparison of on-site and off-site concentrations with health assessment comparison values for noncarcinogenic and/or carcinogenic endpoints (see Appendix B for a discussion of ATSDR comparison values); and
- community health concerns.
It is emphasized that identification of a contaminant of concern in this section does not mean that exposure to it willcause adverse health effects. As mentioned above, the potential for adverse health effects resulting from exposure tocontaminants of concern will be evaluated in subsequent sections of the health assessment.
Sampling data have been collected from various environmental media on and around the Popile, Inc. site on severaloccasions. The following discussion summarizes four previous investigations involving environmental sampling ofthe site. Relevant contaminant data from these and other past sampling efforts are tabulated and evaluated under the"On-Site Contamination" and "Off-Site Contamination" subsections below. (Note: Acronyms and abbreviations usedin the contaminant tables that follow are defined in Appendix B.) For the purpose of this health assessment, "on-site"includes the main site area bordered by South West Avenue on the west, the railroad tracks on the east, Bayou deLoutre on the north, and the woods on the south, as well as the clearing northeast of the main site area (and east of therailroad tracks). All other areas are designated as "off-site". However, ATSDR acknowledges that EPA considers allareas of contamination as "on-site", that is, within the Superfund site boundaries, since they will all be addressed bythe remedial action for the site.
The first investigation at the Popile site was a Site Assessment conducted by an EPA Technical Assistance Teamduring October 10-16, 1989. This assessment included a field topographic survey; a geophysical survey; soil gassampling; and soil, sediment, groundwater, and surface water sampling. The investigation included the old woodtreatment facility area and site drainage area but excluded the impoundment area.
The second investigation was conducted in August 1990, and included collection of ambient air samples at sevenlocations on the site and along the site perimeter (Figure 5); installation of eight shallow piezometers; measurement ofwater levels in the piezometers and five existing shallow monitoring wells; and completion of a field topographic sitesurvey.
The third investigation occurred in conjunction with the Removal Action that was conducted from September 1990through August 1991. Investigation activities included the collection and analysis of soil samples from 12 locationsnortheast of the impoundment area and east of the railroad tracks for semivolatile organics and dioxins/furans. Anadditional 24 soil and sludge samples were collected around the perimeter of the site and analyzed for metals,semivolatile organics, and dioxins/furans. The locations of the soil and sludge samples collected during the RemovalAction are shown in Figure 4.
The fourth and most recent investigation -- the EPA Remedial Investigation (RI) -- was conducted in February andMarch 1992. RI activities included the following: (1) digging of shallow trenches and visual observation of thetrenches for evidence of contamination; (2) drilling of boreholes and monitoring wells; (3) sampling of subsurfacesoil during the drilling of the boreholes and monitoring wells; (4) collection of three surface soil samples from the olddrainage ditch area, the old impoundment area, and the clearing east of the railroad tracks; (5) groundwater samplingof the 14 monitoring wells and 3 piezometers; and (6) collection of five surface water and sediment samples from theon-site drainage ditch and an area of standing water and from Bayou de Loutre off-site. The RI sampling locations areshown in Figures 6 and 7. Most of the samples were analyzed for volatile organic compounds (VOCs), polycyclicaromatic hydrocarbons (PAHs), and phenols. Selected samples were also analyzed for VOCs, PAHs, and phenols aswell as metals and dioxins/furans.
In May 1991, samples of waste sludges from areas east of the railroad track were collected and analyzed for metals,semivolatile organics, and dioxins/furans. The sludge sampling locations are shown in Figure 4. The sludges werelater removed in conjunction with the 1990-1991 Removal Action.
As indicated in Table 1, the sludge solids contained several PAHs, including benz(a)anthracene, chrysene,benzo(b)fluoranthene, and benzo(k)fluoranthene, and metals, such as arsenic, cadmium, chromium, and lead. However, the metals were present at levels similar to background soil concentrations for the eastern U.S. (7), exceptfor lead, which was slightly elevated. The sludge arsenic levels exceeded the applicable ATSDR comparison value. (Note: B(a)P equivalent concentrations are discussed in Appendix C.)
|Benz(a)anthracene||ND - 8.9||5/91||1||None|
|Chrysene||ND - 15||5/91||1||None|
|Benzo(b)fluoranthene||ND - 13||5/91||1||None|
|Benzo(k)fluoranthene||ND - 13||5/91||1||None|
|Total PAHs||ND - 100.4||5/91||1||None|
|B(a)P Equivalents||ND - 3.6||5/91||1||0.1||CREG|
|Arsenic||1.1 - 9.2||5/91||1||0.4||CREG|
|Cadmium||0.29 - 0.41||5/91||1||10||EMEG|
|Chromium||5.6 - 24.5||5/91||1||300||RMEG|
|Lead||206 - 362||5/91||1||None|
On-site surface soil samples were collected in October 1989 during the Site Assessment (SA); in March and May1991 during the 1990-1991 Removal Action (RA); and in February and March 1992 during the RemedialInvestigation (RI). The locations of the RA, SA, and RI samples, which were generally taken at a depth of 0 to 6inches, are shown in Figures 4, 5, and 6, respectively.
The range of contaminant concentrations measured in the October 1989 and March/May 1991 surface soil samples arepresented in Table 2a. In general, high levels of PAHs, pentachlorophenol, and dibenzofuran were present in the1989 samples. Several metals, such as arsenic, chromium, copper, lead, and thallium, were also detected, but theconcentrations were similar to background concentrations for the eastern U.S. (7), except for lead which was elevated. Overall, the contaminant levels found in the 1991 samples were significantly lower than the 1989 levels.
As shown in Table 2b, the contaminant concentrations in the February/March 1992 surface soil samples were muchlower than in the 1989 and 1991 samples. This is most likely due to the 1990-1991 removal action during whichmuch of the site was covered with a one to two foot layer of clean soil. Based on the February/March 1992 samplingresults and observations from the September 1992 ATSDR site visit, it appears that little surface soil contaminationremains at the site.
|Sample Date||Reference||Comparison Value|
|Naphthalene||0.44 - 3,900||10/89; 3/91, 5/91||1,3||None|
|Acenaphthylene||ND - 35||10/89; 3/91, 5/91||1,3||None|
|Phenanthrene||0.23 - 27,000||10/89; 3/91, 5/91||1,3||None|
|Benz(a)anthracene||0.46 - 2,000||10/89; 3/91, 5/91||1,3||None|
|Chrysene||0.56 - 2,400||10/89; 3/91, 5/91||1,3||None|
|Benzo(b)fluoranthene||ND - 1,000||10/89; 3/91, 5/91||1,3||None|
|Benzo(k)fluoranthene||ND - 1,100||10/89; 3/91, 5/91||1,3||None|
|Benzo(a)pyrene||0.3 - 730||10/89; 3/91, 5/91||1,3||0.1||CREG|
|Indeno(1,2,3-cd)pyrene||0.13 - 83||10/89; 3/91, 5/91||1,3||None|
|Dibenzo(a,h)anthracene||0.13 - 37||10/89||1,3||None|
|Benzo(g,h,i)perylene||0.15 - 49||10/89; 3/91, 5/91||1,3||None|
|Total PAHs||0.0 - 74,430||10/89; 3/91, 5/91||1,3||None|
|B(a)P Equivalents||0.0 - 1,134||10/89; 3/91, 5/91||1,3||0.1||CREG|
|Pentachlorophenol||1.1 - 5,700||10/89; 3/91, 5/91||1,3||6||CREG|
|Dibenzofuran||ND - 3,600||10/89; 3/91, 5/91||1,3||None|
|TCDD Equivalents||0.0001 - 0.019||10/89; 3/91, 5/91||1,3||0.00005||EMEG|
|Arsenic||0.57 - 7.0||10/89; 3/91, 5/91||1,3||0.4||CREG|
|Beryllium||ND - 1.0||10/89||1,3||0.2||CREG|
|Cadmium||0.24 - 3||10/89; 3/91, 5/91||1,3||10||EMEG|
|Chromium||1.0 - 57||10/89; 3/91, 5/91||1,3||300||RMEG|
|Copper||1.0 - 65||10/89||1,3||None|
|Lead||1.9 - 300||10/89; 3/91, 5/91||1,3||None|
|Thallium||ND - 1.0||10/89||1||4||RMEG|
Table 2b. Post-Removal Contaminant Concentrations in On-Site Surface Soil
|Total PAHs||0.0||2/92, 3/92||1||None|
|B(a)P Equivalents||0.0||2/92, 3/92||1||0.1||CREG|
|TCDD Equivalents||0.000010 -0.000018||2/92, 3/92||1||0.00005||EMEG|
|Beryllium||0.56B - 0.58||2/92, 3/92||1||0.2||CREG|
|Cadmium||0.75B - 0.78||2/92, 3/92||1||10||EMEG|
|Chromium||5.1 - 6.0||2/92, 3/92||1||300||RMEG|
|Copper||3.7 - 3.9||2/92, 3/92||1||None|
|Lead||10.1 - 18.3||2/92, 3/92||1||None|
|Thallium||15 - 16.7B||2/92, 3/92||1||4||RMEG|
On-site subsurface soil samples were collected in March 1991 during the EPA removal action. These sevencomposite samples were taken at a depth of 12"-18" from the northeast area between the railroad tracks and Bayou deLoutre (see Figure 4). Subsurface soils were also sampled in February and March 1992 during the RI. The sampleswere collected during the drilling of the 15 on-site boreholes and the 14 monitoring wells, generally at 5 foot intervalsfrom a depth of 0 feet to 50 feet (maximum). Samples were obtained from 12 of the boreholes and all 13 on-sitemonitoring wells. Figure 7 shows the monitoring well soil sampling locations.
The analytical results from the 1991 and 1992 sampling events are presented in Tables 3a and 3b, respectively. Thesedata indicate the presence of various PAHs, phenols, metals, dibenzofuran, and dioxins in the subsurface soils. (SeeAppendix C for a discussion of 2,3,7,8-TCDD equivalent concentrations.) The contaminant levels were generallymuch lower those reported in the 1989 surface soil samples. Also, the metal concentrations found in the 1992samples were similar to background concentrations for soils in the eastern U.S. (7), except for thallium which waselevated. No data for metals were reported from the 1991 subsurface soil samples.
The estimated areas of subsurface soil contamination at the site, based on the results of the RI, are shown in Figure 8. The most heavily contaminated areas were the soil disposal cell (Area 6), the old impoundment area (Area 4), and theold treatment facility area (Areas 2 and 3). Other areas of lesser subsurface contamination were the area near theformer drainage ditch north of the old impoundment area (Area 1) and the area northeast of the old impoundment andeast of the railroad track (Area 5).
|Acenaphthylene||56 - 23J||3/91||1||None|
|Phenanthrene||1.3 - 140||3/91||1||None|
|Chrysene||ND - 21||3/91||1||None|
|Benzo(b)fluoranthene||ND - 15||3/91||1||None|
|Benzo(k)fluoranthene||ND - 15||3/91||1||None|
|Benzo(a)pyrene||1.6 - 9.2||3/91||1||0.1||CREG|
|Indeno(1,2,3-cd)pyrene||ND - 7.6||3/91||1||None|
|Benzo(g,h,i)perylene||ND - 6.6||3/91||1||None|
|Total PAHs||4.9 - 479||3/91||1||None|
|B(a)P Equivalents||1.7 - 10.2||3/91||1||0.1||CREG|
|Dibenzofuran||ND - 29||3/91||1||None|
|Total TCDD||ND - 0.0106||3/91||1||None|
|Naphthalene||0.023 - 130J||2/92, 3/92||1||None|
|Acenaphthylene||ND - 23J||2/92, 3/92||1||None|
|Phenanthrene||0.0022 - 104||2/92, 3/92||1||None|
|Benz(a)anthracene||ND - 42J||2/92, 3/92||1||None|
|Chrysene||0.066 - 41J||2/92, 3/92||1||None|
|Benzo(b/k)fluoranthene||ND - 100||2/92, 3/92||1||None|
|Benzo(a)pyrene||ND - 14J||2/92, 3/92||1||0.1||CREG|
|Indeno(1,2,3-cd)pyrene||ND - 8.3J||2/92, 3/92||1||None|
|Dibenzo(a,h)anthracene||ND - 4.1J||2/92, 3/92||1||None|
|Benzo(g,h,i)perylene||ND - 5.1||2/92, 3/92||1||None|
|Total PAHs||0.022 - 570||2/92, 3/92||1||None|
|B(a)P Equivalents||0.003 - 32.8||2/92, 3/92||1||0.1||CREG|
|2-Nitrophenol||0.047J - 0.085J||2/92, 3/92||1||None|
|4-Chloro-3-Methylphenol||0.003J - 15||2/92, 3/92||1||None|
|4-Nitrophenol||0.052J - 11J||2/92, 3/92||1||None|
|4,6-Dinitro-2-methylphenol||0.97J - 5.7J||2/92, 3/92||1||None|
|Pentachlorophenol||0.042J - 200J||2/92, 3/92||1||6||CREG|
|HxCDD (total)||ND - 0.00184||2/92, 3/92||1||0.00011||CREG|
|2,3,7,8-TCDD||ND - 0.00167||2/92, 3/92||1||0.00005||EMEG|
|TCDD Equivalents||ND - 0.00303||2/92, 3/92||1||0.00005||EMEG|
|Arsenic||20.2 - 34.4B||2/92, 3/92||1||0.4||CREG|
|Beryllium||0.21B - 0.84B||2/92, 3/92||1||0.2||CREG|
|Cadmium||ND - 0.98B||2/92, 3/92||1||10||EMEG|
|Chromium||2.6 - 26||2/92, 3/92||1||300||RMEG|
|Copper||1.5B - 43.6||2/92, 3/92||1||None|
|Lead||10B - 13.3B||2/92, 3/92||1||None|
|Thallium||17.6B - 1,650||2/92, 3/92||1||4||RMEG|
Groundwater samples were collected from five on-site wells and three piezometers during the October 1989 SiteAssessment. The five wells sampled were monitoring wells installed in 1983 by Popile, Inc. as part of the surfaceimpoundment closure plan (8). Figure 5 shows the locations of these groundwater samples.
In addition, groundwater samples were collected in Feb. and March 1992 from the 13 on-site monitoring wells thatwere installed during the RI field activities. Ten of these wells were considered to be "shallow" wells since they werescreened at a depth of less than 28 feet below ground surface; the remainder are referred to as "deep" wells. Thedeepest well, monitoring well number 9 (MW-9), is 51 feet deep. Groundwater samples were also collected fromthree piezometers (PZ-2. PZ-8, and PZ-9) during the RI. The locations of the monitoring wells and piezometers areshown in Figure 7 (1).
As shown in Table 4, high levels of contaminants were found in the 1989 and 1992 groundwater samples, includingVOCs (benzene and toluene), PAHs, pentachlorophenol, and dibenzofuran. Lead was also measured at highconcentrations while several other metals, including arsenic, chromium, thallium, and vanadium, were detected atsignificantly lower levels.
The highest levels of groundwater contamination at the site were found in the vicinity of the old impoundment areaand the old treatment facility area, as indicated by the sampling results from Monitoring Well 7 (MW-7) andPiezometer 8 (PZ-8). Concentrations of several PAHs in a sample from MW-7 were well above their respectivesolubility limits, indicating a mixture of free-phase (undissolved) liquids and water. Analytical results for the samplefrom PZ-8 were similar. Contaminant concentrations in samples collected downgradient of the old impoundment(MW-6, MW-13, MW-4, MW-5, and PZ-2) and the old treatment facility (MW-1, MW-2,and MW-3) weresignificantly lower than those from MW-7 and PZ-8. Low to moderate levels of PAHs, PCP, and toluene were alsofound in samples from PZ-9, immediately downgradient of the east side of the soil disposal cell (1).
No contaminants (VOCs, phenols, or PAHs) were detected in MW-11 on the south side of the site, and only a few,low-level contaminants were found in MW-8 and MW-9 on the southwest end. (Samples were not analyzed formetals.) This suggests that contaminants are not currently a threat to the residences southwest of the site along SouthWest Avenue.
Observations and analytical results from the RI groundwater sampling effort indicated an area of light (floating) non-aqueous phase liquids (LNAPLs) and heavily contaminated groundwater in the vicinity of the old impoundment areaand old treatment facility area. A plume of dissolved contaminants in the groundwater extends downgradient fromthese presumed source areas towards Bayou de Loutre at the extreme northern and northeastern boundaries of the site. (Note: Contaminants from the soil disposal cell also contribute to this groundwater plume.) However, results fromgroundwater samples from the northern and eastern perimeter of the site indicated that contaminant concentrationsdecreased significantly with increasing distance from the impoundment area (1).
Figure 9 shows the estimated areal extent of groundwater contamination at the site. The free-phase liquids zone isestimated to extend 10 to 20 feet below the surface of the water table, and is probably underlain by a zone of dissolvedcontamination extending to the clay layer at 45 feet below ground surface. This clay layer is believed to be the top tothe Cook Mountain Formation, a 150 foot thick bed of clay/silty clay that is thought to serve as an effective barrier tothe downward movement of groundwater contaminants at the site. Drilling activities conducted during the RIstrongly suggest that the clay layer is continuous beneath the site (1).
No evidence of dense non-aqueous phase liquids (DNAPLs) was observed in two monitoring wells, MW-3 and MW-6, screened immediately above the top of the deep clay layer. However, neither of these wells is located in the area ofgreatest groundwater contamination. Therefore, DNAPLs may be present at the top of the clay layer near the oldimpoundment area, but no wells are screened at the right depth in this location to investigate the possibility (1).
At the remainder of the site, the dissolved contaminant plume is estimated to extend from the surface of the watertable to the top of the clay layer located 40 to 60 feet below ground surface (1).
|Sample Date||Reference||Comparison Value|
|Benzene||2 - 81J||10/89; 2/92, 3/92||1||1.2||CREG|
|Toluene||11 - 3,100J||10/89; 2/92, 3/92||1||1,000||LTHA|
|Naphthalene||3 - 7,800||10/89; 2/92, 3/92||1,3||20||LTHA|
|Acenaphthylene||120 - 270J||10/89; 2/92, 3/92||1||None|
|Acenaphthene||3 - 3,000||10/89; 2/92, 3/92||1,3||600||RMEG|
|Fluorene||2.2D - 2,400||10/89; 2/92, 3/92||1,3||400||RMEG|
|Phenanthrene||1.9D - 8,000||10/89; 2/92, 3/92||1,3||None|
|Fluoranthene||4.2D - 4,700||10/89; 2/92, 3/92||1,3||400||RMEG|
|Pyrene||2.5J - 3,000||10/89; 2/92, 3/92||1,3||300||RMEG|
|Benz(a)anthracene||2.95D - 700||10/89; 2/92, 3/92||1,3||None|
|Chrysene||1.5D - 690||10/89; 2/92, 3/92||1,3||None|
|Benzo(b)fluoranthene||2.25D - 360||10/89; 2/92, 3/92||1,3||None|
|Benzo(k)fluoranthene||2.20D - 310||10/89; 2/92, 3/92||1,3||None|
|Benzo(a)pyrene||1.04D - 290||10/89; 2/92, 3/92||1,3||0.005||CREG|
|Indeno(1,2,3-cd)pyrene||2.10D - 180J||10/89; 2/92, 3/92||1||None|
|Dibenzo(a,h)anthracene||3.98D - 96J||10/89; 2/92, 3/92||1||None|
|Benzo(g,h,i)perylene||2.56D - 100J||10/89; 2/92, 3/92||1,3||None|
|Total PAHs||8 - 37,100||10/89; 2/92, 3/92||1,3||None|
|B(a)P Equivalents||6 - 841||10/89; 2/92, 3/92||1||0.005||CREG|
|2,4-Dichlorophenol||6.8J - 89||10/89; 2/92, 3/92||1,3||20||LTHA|
|4,6-Dinitro-2-methylphenol||3.0J - 5.0J||2/92, 3/92||1||None|
|Pentachlorophenol||3.0J - 26,000||10/89; 2/92, 3/92||1,3||0.3||CREG|
|Dibenzofuran||13 - 2,100||10/89||1,3||None|
|Arsenic||ND - 11||10/89; 2/92, 3/92||1,3||0.02||CREG|
|Beryllium||3 - 7||10/89; 2/92, 3/92||1||0.008||CREG|
|Cadmium||4B - 6||2/92, 3/92||1||2||EMEG|
|Chromium||14 - 99||10/89; 2/92, 3/92||1,3||50||RMEG|
|Lead||2 - 2,640||10/89; 2/92, 3/92||1,3||None|
|Thallium||3 - 184||10/89; 2/92, 3/92||1||0.4||LTHA|
|Vanadium||41B - 203||10/89; 2/92, 3/92||1,3||20||LTHA|
On-site surface water samples were collected in October 1989 during the SA from the old surface impoundment("sludge pit") in the facility area (see Figure 5). Surface water samples were also taken on site in Feb. and Mar. 1992during the RI from the northwest drainage ditch, and an area of standing water near the railroad tracks on the easternside of the site (SW-4 and SW-5, respectively). The locations of the RI surface water samples are shown in Figure 6.
As shown in Table 5a, low levels of several PAHs, arsenic, and lead, and moderate levels of pentachlorophenol weremeasured in the surface water samples from the old surface impoundment which was subsequently excavated andfilled during the 1990-1991 removal action. Few contaminants, however, were detected in the 1992 samples (Table5b) which better represent current site conditions.
|Phenanthrene||ND - 2.0J||2/92, 3/92||1||None|
|Benzo(a)pyrene||ND - 17.0J||2/92, 3/92||1||0.005||CREG|
|Total PAHs||2 - 20||2/92, 3/92||1||None|
|B(a)P Equivalents||0 - 17||2/92, 3/92||1||0.005||CREG|
|Pentachlorophenol||ND - 44J||2/92, 3/92||1||0.3||CREG|