DOE/ORO/2327 Oak Ridge Reservation Annual Site Environmental ...

Annual Site Environmental Report
well 1191. No other radionuclides exceeded reference standards in the WOC Discharge Area wells. A
statistically significant downward trend exists for all three radiological constituents at both sampling
locations. Aside from the radionuclides that were detected above reference standard concentrations, the
following radionuclides were detected at low levels in WOC Discharge Area wells: gross beta activity,
214 3 40 214 214
Bi, and H in well 857; gross beta activity and K in well 858; Bi and Pb in well 1190; and gross
alpha activity, 214 Bi, and 214 Pb in well 1191.
As in past years, iron, manganese, and aluminum exceeded reference standards in WOC Discharge
Area wells during 2009. Aluminum was found to exceed its reference standard in well 857 in addition to
iron and manganese in wells 1190 and 1191. Statistical trend analyses of metals data for these wells show
a statistically significant historical increase in aluminum and manganese in wells 857 and 1191,
respectively and a statistically significant historical decrease in manganese and iron in wells 1190 and
1191, respectively. Further statistical analyses of historical iron, manganese, and aluminum data from
these wells indicate the 95% UTLs are within the range or below those estimated for the transition
limestone-shale/shale-dominated groundwater clusters established for ORNL (Wolf et al. 1996). The
transition limestone-shale/shale-dominated groundwater clusters were used for comparison because the
WOC Discharge Area wells are screened in strata dominated by shale but interbedded with limestones.
Table 5.24 provides a comparison for these UTLs.
Table 5.24. Comparison of WOC discharge area groundwater and shale-dominated
groundwater upper tolerance limits (UTLs)
Metal
WOC discharge area
estimated 95 th UTL
(mg/L)
Transition limestone-shale
groundwater
estimated 95 th UTL (mg/L)
Shale-dominated
groundwater
estimated 95 th UTL (mg/L)
Iron 9.19 8.0 50
Manganese 0.35 2.6 16
Aluminum 1.11 3.2 2.8
It is likely that the metals are sorbed onto suspended solids in the groundwater samples collected
contributing to the exceedance of the reference standards used for comparison. Other metals were
detected at low concentrations in groundwater samples collected from WOC Discharge Area wells; these
results can be found in the 2009 Environmental Monitoring Results (DOE 2009).
Detection limits for several semi-volatile organic compounds (atrazine, benzo(a)pyrene,
hexachlorobenzene, and pentachlorophenol) exceeded reference standards in samples collected from
WOC Discharge Area monitoring points. No other organic compounds were present in concentrations
above reference standards in samples collected from WOC Discharge Area wells; however, a common
plasticizer [bis(2-ethylhexyl) phthalate] was detected at low, estimated concentrations in wells 858, 1190,
and 1191 and was detected in well 1239. Bis(2-ethylhexyl) phthalate was also found in laboratory blank
samples from wells 857, 858, and 1239. Given its presence in laboratory blanks, the source of bis(2ethylhexyl)
phthalate may have been due to laboratory cross-contamination of sample aliquots collected
from wells 1190, 1191, and 1239. Departing from past year observations, diethyl phthalate was not
detected in samples collected from WOC Discharge Area wells in 2009.
Low concentrations of volatile organics were also detected in WOC Area Discharge wells in 2009.
Low levels of acetone were detected in wells 1190 and 1191, while a low estimated concentration of
carbon disulfide was reported for a sample collected from well 1190. Subsequent to collection of the 2009
groundwater samples, acetone was found to be present in the deionized water used in preparing blank
samples. This source of deionized water is no longer used for blank samples or for decontamination of
sampling equipment.
7000/Bearden Creek Watershed Discharge Area Exit Pathway Results
Wells 1198 and 1199 were not sampled during 2009 because detailed geotechnical and environmental
characterization of the Multiprogram Computational and Data Center site located east of the 7000 area
Oak Ridge National Laboratory 5-77