Environmental Engineering Reference
In-Depth Information
the sites were treated using SVE, bioremediation, and solidiication/stabilization in
descending order. The majority of ex situ remediation technologies were by S/S, incin-
eration, thermal desorption, and bioremediation in descending order. Over the years,
in situ remediation has been increased from 31% (in 1985 to 1989) to 49% (1998 to 2002).
The reasons included cost-effectiveness, decreased exposure to contaminants, as no
excavation is required, and willingness by professionals to use this approach. In iscal
year (FY) 2009-2011, 300 decisions were made for Superfund source materials. About
half were in situ treatment, SVE, chemical treatment, bioremediation, S/S, multiphase
extraction, bioremediation, and in situ thermal treatment were common. Off-site meth-
ods included physical separation, S/S, off-site treatment, and recycling. Physical sepa-
ration includes sieving, sifting, removal of solid media, dewatering (for sediments), and
decontamination. A variety of technologies are utilized as summarized in Table 11.3.
TABLE 11.3
Soil Treatment Technologies Utilized for Superfund Sites
% decision documents
(FY 2005-2008)
% decision documents
(FY 2009-2011)
Technology
In situ
Chemical treatment
21
21
SVE
7
14
S/S
9
9
Thermal treatment
9
6
Multiple phase extraction
7
3
4
3
Constructed wetland
0
2
Reactive cap
0
2
Flushing
1
1
Fracturing
1
1
Phytoremediation
1
0
Total
48
80
Ex situ
Physical separation
21
28
S/S
19
13
Pump and treat
12
11
Off-site treatment
7
9
Recycling
10
8
On-site treatment
1
5
Phytoremediation
0
4
Chemical treatment
3
3
Bioremediation
3
3
NAPL recovery
1
1
Thermal desorption
2
1
Other
9
0
Total
65
67
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