Chlorinated solvent contaminated soils and groundwater: field application of the solvent extraction residual biotreatment technology - Bioremediation of Recalcitrant Compounds - page 124

~25 Months Post-Flush

~28 Months Post-Flush

C7 C7

C3

C3

C4 C4

160 mg/L

MW-512 MW-512

MW-513 MW-513

MW-514

MW-514

C2 MW-505 C2 MW-505

C1 C1

140 mg/L

MW-506 MW-506

MW-509
MW-510
MW-511

MW-509
MW-510
MW-511

120 mg/L

MW-507

MW-507

100 mg/L

80 mg/L

60 mg/L

~31 Months Post-Flush

40 mg/L

20 mg/L

0 mg/L

C7

C3

C4

MW-512

MW-513

MW-514

C2 MW-505

C1

MW-506

MW-509
MW-510
MW-511

MW-507

Figure 5.37 Acetic acid contour plots over the groundwater monitoring period (120
mg/l = 2.0 m M ).

N

MW-512

MW-513

5 nM

MW-505

18 nM

156 nM

DNAPL Source Area
Ta r g e t Z o n e 2 uM

MW-510

RW-007

MW-511

33 nM

MW-507

4.7 uM 24.8 uM

0 20 40 60 80 ft.

Figure 5.38 Hydrogen gas concentrations measured 1 year following the cosolvent
flushing test.

indication that sulfate-reducing bacteria are becoming active and creating
conditions conducive to the reductive dechlorination process.
Along with the removal of sulfate, there was a production of methane,
which indicates that methanogenesis has been enhanced. Methane produc-
tion began after approximately 6 months and was measured in all wells
(Figure 5.43). As with the sulfate removal, methane production began in the
area near the cosolvent flushing test and concentrations downgradient
increased after 14 to 19 months (Figure 5.44 to Figure 5.46).