DUAL-PHASE EXTRACTION PROCESS

The Chemviron "dual-phase" extraction system uses highly adaptable vacuum
technology to simultaneously extract contaminants in both the liquid and vapor
phases from the subsurface. The same system can be used to extract contaminants
from monitoring wells, extraction wells and tank pit sumps.

This is a proven technology that is unsurpassed in removing volatile organic
compounds from soil, rock and groundwater at commercial and industrial sites.
Typical applications include service stations, truck stops, petroleum and chemical
bulk plant terminals, refineries and manufacturing facilities wherever soil or
groundwater is contaminated with volatile organic compounds or non-aqueous
phase liquids. A list of such materials would include, but not be limited to,
benzene, ethylbenzene, toluene and xylene isomers and multi-compound
mixtures such as gasoline, jet fuel and diesel fuel in liquid or vapor phases.

The techniques used for soil vapor extraction and liquid phase extraction of volatile
materials are similar, but distinct. Both are applied simultaneously with the
Chemviron system. Hence the term "dual-phase extraction."

As a low magnitude vacuum is created beneath the surface in the unsaturated
zone, contaminants in the vapor phase are "stripped" from the soil as they are
drawn toward the vacuum source, where they combine with air that is rich in
oxygen. At that point, they volatize, or evaporate. Air from outside of the
impacted zone, which contains higher concentrations of oxygen, is drawn
through the contaminated area as it moves toward the extraction point and
assists in the volatilization process.

Similarly, a vacuum introduced into the earth below the water table pulls
groundwater containing dissolved volatile organic compounds toward the
source of the vacuum, or the extraction point. As this groundwater is removed,
it is replaced through natural recharge by fresh water from outside the impact zone.
In a fashion similar to vapor phase extraction, such water contains higher
concentrations of dissolved oxygen. Normal fluctuations in groundwater levels
typically create a "smear" zone that can be attacked with dual-phase technology
regardless of water table levels.

In addition to the removal of volatile compounds in the vapor and liquid phases,
the Chemviron systems effectively remove non-aqueous phase liquids,
regardless of their volatility. It is highly successful in removing both light and
dense non-aqueous materials, ranging from gasoline to heavy  motor oil.


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