Well my comments should provoke some debate... Over the years I have
found that with very few exceptions (plating shops and metal processing
mainly) the percentage of Cr6 in any given sample will generally lie
between 1 and 10% of total Cr and rarely above 15% even in exceptional
cases. Therefore I usually suggest to clients a Cr6 dependant option
based on the intended use. I generally suggest a value approximately 10
times the SGV as the value at which the dependant option for Cr6 testing
kicks in for most sites. Being based in the Midlands I come across Cr
with great regularity on contaminated sites and have found this the best
option for saving clients money, undertaking less testing and being more
sustainable in my testing schedules in line with the guidance. I
regularly check our lab results and my overall average for Cr6 to total
Cr is usually around 3-4% for general industrial areas and ash/clinker
fill. However if I know it is a plating shop or similar, I generally cut
this down to 5 times the SGV. As noted in the previous post, it is a
case of knowing your site history...
Chris Swainston BSc. FGS
Principal Geoenvironmental Engineer
For: Geotechnics Limited - Head Office
Tel: 02476 694664
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