The only thing that a PID should be used for on site as a screening tool to inform lab analysis for VOCs, BTEX or volatile hydrocarbon fractions.  That was all it was designed for and all it should be used for.



A PID is useful in targeting soil samples for laboratory analysis and also can be ONE component of an investigation of known sources in HELPING to determine the extent of impact within soils and underlying strata.



However it should NEVER be used as a definitive tool for demonstrating absence of volatiles, BTEX or lighter hydrocarbon fractions or as the only component of demonstrating they are present.  Any use of a PID should be backed up by a properly designed program of laboratory analysis and also the observations of a trained and competent consultant supervising an investigation.



Similarly with verification it is an aid to determining the extent of remediation works but should be backed up with robust laboratory analysis, site photographs and observations.



It should always be recognised that a PID is a SCREENING tool which is prone to interference effects and only one tool in the kit albeit a useful one if used appropriately and correctly.



Brad.



Brad Balmer,   BSc(Hons), FRSC

Associate Director, Land & Development

ATKINS

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-----Original Message-----

From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Marc Fawcett

Sent: 16 May 2014 10:59

To: [log in to unmask]

Subject: Re: Soil vapour assessment of stockpiles



agreed 5 star post!



I hate the things - too many variables and so much guess work. Very limited use in my opinion.



Probably only really useful if you know the product your looking for and it hasn't had time to decompose.



Best Regards



Marc Fawcett

Director

Betts Geo Environmental



http://uk.linkedin.com/in/marcfawcett



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