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Annual Site Environmental Report for 1999
surface and subsurface soils at WAG 28 are
metals. This contrasts with the overwhelming
and well-documented contamination in RGA
and McNairy groundwater that is characterized
by the presence of chlorinated alkenes and
radionuclides (predominantly TCE and 99'fc,
respectively). These. differences in the suites
between the soil and groundwater-borne
contaminants suggest that the areas investigated
during the WAG 28 RIare not significant
sources of the existing groundwater
contamination. However, a range of
contaminants, including metals, volatile organic
compounds, and radionuclides, was detected in
the soils at WAG 28, some of which appear to
have the capacity to migrate to groundwater in
the future.
SWMV 99 does not contain significant
contaminant concentrations in either the VCRS
soils or VCRS groundwater that would suggest
the site is currently or will in the future become
a significant contributor of contaminants to the
Northeast Plume. However, elevated levels of
radionuclides were discovered in shallow soils
surrounding a broken drainpipe that drains the
SWMV 99 area. This migration pathway, which
feeds Outfall 010, may be a contributing source
to contamination observed in· the Northeast
Plume in the underlying RGA.
Sampling of the VCRS soils during the
WAG 28 RI indicates that the primary source of
the contamination in the RGAgroundwater at
SWMV 193 does not exist at the former location
of the Millwright Shop as originally believed.
Moreover, TCE concentrations currently in the
RGAgroundwater beneath the site have
decreased significantly during the last four
years. This decrease in TCE concentrations in
the RGA ,at ,the Millwright Shop is best attributed
to migration and dispersion of ,the contaminated
groundwater plume.
. At AOC 204, relatively minor
trichloroethene concentrations « 100 Ilg/kg)
weteobserved in the near surface soils adjacent
to Outfall ,011, but higher concentrations were
observed .at· greater . depths . in the· borings located
in the interior of the site. This evidence indicates
that contaminants detected in the VCRS soils are
related to the downward percolation of surface
water flow in Outfall OIl. This infiltration of
contaminants from a losing surface water stream
would appear to represent one potential. source
for the contaminants present in the Northeast
Plume.
The results of the WAG 28 RI show that
widespread contamination is not present in
either the VCRS soil or the VCRS groundwater at
any of the areas investigated. None of the WAG
28 sites sampled for the RI has been identified as
a significant contributor of contaminants to the
underlying RGA groundwater. This conclusion
is based on the evaluation of the nature, extent,
and concentration of contaminants found during
the WAG 28 investigation, taking into account
the data obtained from both previous and current
rounds of sampling.
The Remedial Investigation Report for
Waste Area Grouping 28 at the Paducah
Gaseous Diffusion Plant, Paducah, KentuckY.
(DOE 2000a) provides conclusions and
additional information on the WAG 28 RI
activities.
WAGS
In 1999, the WAG 8 SE was initiated with
90% of the work being completed at the year's
end. The goals of the WAG 8 SE were to confirm
or deny the presence of contaminants at each of
the WAG 8 sites, evaluate migration pathways to
determine if the sites are presently sources of offsite
contamination, and to determine risk from
each site to on~site receptors. The focus of the SE
was . to collect sufficient information. .about
surface water, surface soil, subsurface soil, and
shallow groundwater contamination to support
the evaluation process. The results of the SE
were· used to formulate recommendations
concerning further actions for each site.
Environmental .Program : Information
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