Methods of Soil Environmental Remediation - Environmental Geomechanics - page 433

Factor Parameter Desired limits Notes

Contaminant Volatility

Solubility
Biodegradability

> 5 mm of Hg
<20,000 mg/l
BOD 5 >0.1 mg/l

Geology Heterogenity No impermeable

layer above
sparging

If there is stratification in
the saturated zone, there is a
strong possibility that the
air could be retained below
an impermeable barrier and
thus move sideways

> 10 -7 m/s if
horizontal
vertical is <2:1

Permeability The permeability should be

sufficient to allow the air to
move horizontally and
vertically through the
aquifer

> 10 -6 m/s if
horizontal
vertical is >3:1

If the flow is prevented in
either direction due to low
permeability, air sparging
will no longer be applicable

Physical Depth sparging > 1.5 m, < 9m The minimal depth (1.5 m)

is the thickness of the
saturated zone required to
create a depression cone
around the injection point.
The maximum depth (9 m)
gives better control of the
technique

Depth of the pool > 1.5m Unsaturated zone necessary

for vapor extraction

Table 15.8. Limitations of air sparging or biosparging

15.5.2.4. Stripping in situ/in column

This process, often coupled with “venting” of the ground, consists of making
buller air within the nappe to support desorption of the dissolved pollutants. The
latter are involved in the airflow that will be recovered at the exit. By stripping in
column, the process is carried out on site after having pumped water (see Figure
15.12). This process allows the treatment of the volatile and semi-volatile pollutants.