The old SGV of 130 mg/kg was also based on all the Cr being present as CrVI.
But at least 130 mg/kg was workable on most sites (usually).
I think the major reason in the reduction in the GAC is probably due to the
Indoor Air 'Killer Dust' pathway (via the Indoor Dust Loading Factor of 50ug/m3
and Transport Factor of 0.5) added to the SR3 model.
Take this pathway out and the GAC should much higher (in the 100s of mg/kg).
(I know the numbers I get out of CLEA for Chromium, but I can't comment on
how the GAC of 14.7 has been arrived at without seeing the paperwork, so not
giving any actual numbers from my calcs!)
Cheers
Chris Dainton
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