In-situ technologies for groundwater treatment: the case of arsenic - In-Situ Remediation of Arsenic-Contaminated Sites - page 2

Figure 1.1. Conceptual structure of a PRB (USEPA, 2001).

Figure 1.2. Permeable reactive barrier. Continuous configuration (USEPA, 1998).

into an innocuous form. Materials used in the construction should obey to the following criteria
(Bhumbla et al ., 1994; Gubert et al ., 2004; Younger et al ., 2002):

• to have enough reactivity in order to reduce the aqueous concentration of the pollutant;

• to have enough permeability to allow diverse type of waters joining the normal flux of water

(in the order of 1 m per day);

• to have capacity of keeping the permeability for a long time (in order of several years);

• to have acceptable costs.

The purpose of the barrier design is to allow the complete capture of the contamination plume
using the minimum of the reactive material. There are two basic types of configuration: the
continuous configuration ( Fig. 1.2 ) and the funnel-and-gate configuration ( Fig. 1.3 ). Choosing
the correct configuration depends on the size of the plume, accessibility and groundwater pattern.