1 - paducah environmental information center

Annual Site Environmental Report for 1999
Abstract
The primary ob~ectives of groundwater ,monitoring at the Paducah Site are to detect contamination and
provid~ the basIs for ground~ater quality assessments if contamination is detected. Monitoring includes
the ~Xlt pathways at t~e pe,,'!"eter of th~ plant and off-site water wells. Primary off-site contaminants
contmue to be TeE, an mdustflal degreasmg solvent, and 99 Tc, a fission by-product. Evidence suggests the
presence of dense nonaqueous phase liquids (DNAPL) on-site.
Introduction
Monitoring and protection of groundwater
resources at the Paducah Site are required by
federal and state regulations and by DOE orders.
Federal groundwater regulations generally are
enacted and enforced by EPA. The Paducah Site
lies within EPA Region N jurisdiction. EPA
Region N encompasses the southeastern United
States and maintains headquarters in Atlanta,
Georgia. Many state groundwater regulations
are enacted and enforced by KDWM in
Frankfort, Kentucky. A KDWM field office for
western Kentucky is located in Paducah.
When Offsite contamination from the
Paducah Site was discovered in 1988, the -EPA
and DGE,entered i into 'an ACO. DOE provided
an alternate water supply to affected· residences.
Under CERCLA, IDOE is also required to
determine the nature and extent of offsite
contamination through sampling of potentially
affected wells and a comprehensive site
investigation.
A CERCLAI ACO site investigation,
completed in 1991, determined offsite
contaminants in the RGA to be TCE, used as an
industrial degreasing solvent, and 99'fc, a fission
byproduct contained in nuclear power reactor
returns that were brought on-site several years
ago for reenrichment. Such reactor returns are
no longer enriched. Known or suspected
sources of TCE and 99'fc include burial grounds,
former test areas and other facilities, spills, leaks,
and leachate derived from contaminated scrap
metal.
Investigations into the onsite source areas
of TCEat the Paducah Site are ongoing. A
common degreasing agent, TCE is considered a
dense non~aqueous phase liquid (DNAPL).
DNAPLs typically have low solubilities in water
and sink to the bottom of aquifers or come to rest
upon a less permeable layer within an aquifer,
fomiingpools. These DNAPL pools form a
continuing source for dissolved-phase
contamination (plumes) that are migrating
offsite toward the Ohio River (Figure 9.1).
DNAPL pools are extremely difficult to clean up
and currently only the highest concentrations of
dissolved TCE are controlled by pump-and-treat
Groundwater
9-1