Hi Steve
Not sure by what you mean by 'very low allowable concentrations', as the allowable 'CLEA' indoor vapour concentration for speciated TPH fractions and TEX are actually (what I would consider) quite high ranging from 0.1 to 9.8 mg/m3, although additivity may need to be considered for TPH.
As a guide to put these TPH levels in context, the odour threshold for diesel is around 0.06 mg/m3. The odour threshold for toluene and xylenes are around 0.5 and 0.06 mg/m3 respectively.
Naphthalene, benzene & TMBs are much lower at 0.002, 0.003 and 0.002 mg/m3 (though the AQS for benzene of 0.005 mg/m3 might be more applicable). BaP should be considered non-volatile.
Chlorinated solvents are also low (<0.001 to 0.2 mg/m3).
Some of the membrane producers will now provide an assessment of site specific suitability of their membranes based on identified contaminant concentrations.
Chris Dainton
Peak Environmental Solutions
|