Handbook of Solvents - George Wypych - ChemTech - Ventech!

23.2 Remediation technologies 1629
Figure 23.2.7. Schematic of a permeable reactive barrier. [From Permeable Reactive Barrier Technologies for
Contaminant Remediation, EPA/600/R-98/125, 1998].
mary groundwater contaminants were TCE, PCE and cis-1,2-DCE (cDCE). The lithology
of the site has been characterized as alluvial-fluvial clay, silt, sand and gravel, with an aquifer
extending 5 to 60 ft below ground surface. The lithology is complex in this region and
separates the aquifer into two zones with a discontinuous semi-confining aquitard. The
mixed TCE, PCE, cDCE plume was ca. 10,000 ft by 5,000 ft extending along the direction
of groundwater flow. Prior to installation of the permeable barrier system, TCE levels exceeded
5,000 μg/L, PCE 1,000 μg/L. A permeable reactive barrier was constructed with the
dimensions 10 ft wide, 6 ft long, and 25 ft deep witha2ftpeagravel layer in front of and behind
the cell. The cell was filled with granular zero-valent iron and a steel corrugate wall
was constructed on each of the sides of the cell to form a funnel redirecting groundwater
flow in that area through the iron cell. After nearly 4 years of operation, monitoring wells
down gradient of the permeable barrier continue to shown non-detect for CHCs.
23.2.4 CONCLUSIONS
There are a number of technologies and strategies for managing hydrocarbon remediation.
We have reviewed a number of the more promising, simple, and perhaps higher-technology
solutions. However, a number of other demonstrated (pump and treat, air sparging) and
emerging technologies do exist. 34 The basic themes of preventing migration passively, and
removal of contaminant via degradation (biotic and abiotic) are seen in all the technologies.
The proper use of particular technologies and strategies is very dependent on the extent and
type of contamination, the site characteristics (hydrology, lithology, etc), the cleanup goals,
and applicable regulations to name a few. Unfortunately, there are no hard and fast rules for
the use of a particular technology; past experience suggests that the more that is known
about site characteristics the greater the success of technology application.