BTEX contamination

[zweifel@nexus.chapman.edu]

Posting from "Don Zweifel" <zweifel@nexus.chapman.edu>

To whom it may concern:

The USEPA has determined that benzene and toluene are both priority
pollutants, with the former being a carcinogen. Benzene and toluene are 
chemical constituents in gasoline, JP-5 jetfuel and also found in industrial
cleaning solvents. 

The water quality criteria for the above is expressed in "permissible
exceedence, with the acute toxicity criteria being a one-hour average
concentration, not to be exceeded more than once in three years on the
average. 

The chronic toxocity criteria for all priority classified pollutants is
indicated by a four-day concentration, not to be exceeded more than once
in three years on the average.

The maximum concentration for benzene in contaminated sediments is 0.5
milligrams/liter or 0.5 ppm as per the USEPA reg.

Benzene is a monocyclic aromatic as is toluene. The are both moderately
volatile. With benzene being little/slowly biodegradable. Benzene and
toluene are highly soluble in water, with the former having more than 3x
the solubility.

Molecularly they are not heavier than their primary constituent, if it is
gasoline or jetfuel. 

Benzene unfortunately has a slow biochemical decay coefficient which means
its residence time could conceivably take over 20 years to attenuate
naturally.

If you have further queries pls contact the USEPA.

 Don Zweifel