H i g h w a y
R iv e r
H e l e n a
Road
Bellevue
N
Mixed contaminant
groundwater plume
B Former waste
control
TCE groundwater
Industrial
plume
area
Native
A'
vegetation
Permeable reactive
barriers (PRB)
A
Seasonal pond
B'
Damplands
Section location
Native
meters
vegetation
0
50 100
112
Permeable Reactive Barrier
initial investigations focused predominantly on characterizing the type,
mass, and distribution of contaminants in the subsurface. It was found that
the contamination in both soil and groundwater beneath the WCS consisted
predominantly of hydrocarbons with some concentrations of chlorinated
and brominated solvents. The chlorinated solvents identified at the WCS
included tetrachloroethene (PCE), TCE, dichloroethene (DCE), trichloroethane (TCA), and 1,2-dichloroethane (DCA). The WCS source area is referred
to as the primary source of contamination.
Groundwater investigations downgradient of the WCS in the Southwest
Industrial Area (SIA) and the Damplands identified concentrations of TCE at
concentrations greater than those identified at and immediately downgradient of the WCS.
In 2008, a drilling campaign using in-line sampling with a ColorTec kit was
used to screen samples for chlorinated compounds. This resulted in a secondary source of contamination being identified downgradient. This source
area is referred to as the secondary source and was found to consist of only
TCE with no degradation products. The secondary source is located at the
end of a cul-de-sac approximately 100 m to the south-east (downgradient) of
the WCS site. A site plan view is presented as Figure 7.1.
FIGURE 7.1
Plan view of site.