Remediation: Techniques and Cost - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 397

750
700
650

Completed
Not completed

73

250
200
150
100
50
0

106

Number of
projects

652

20

136

10

19 6

142 28

9

95

5

2 5

56

34

52 60

22

26 40 21

37 10 15 2 40 16

34 15

30

Ex situ
source control

In situ
source control

In situ
groundwater

Groundwater
pump and treat

FIGURE 11.22
Selected remedies at Superfund sites. (From United States Environmental Protection Agency (USEPA),
Treatment Technologies for Site Cleanup: Annual Status Report , 12th edn., EPA-542-R-07-012, Office of Solid Waste
and Emergency Response, Washington, DC, 2007.)

In-well
airstripping (8)
3%
Flushing (1)
<1%
Permeable
reactive
barrier (24)
9%
Multi-phase
extraction (26)
10%
Chemical
treatment (39)
15%

Phytoremediation (14)
6%

Air sparging (72)
29%

Bioremediation (70)
28%

FIGURE 11.23
Breakdown of Superfund sites using in situ technologies. (From United States Environmental Protection
Agency (USEPA), Treatment Technologies for Site Cleanup: Annual Status Report , 12th edn., EPA-542-R-07-012, Office
of Solid Waste and Emergency Response, Washington, DC, 2007.)

11.7 Sediment Remediation
Remediating contaminated sediment presents difficulties not encountered when remedi-
ating soil. These difficulties include the location of the contamination beneath the surface
of water bodies and within sensitive ecosystems. Remediating contaminated sediment
therefore requires careful study and planning.