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Just a note as no one has asked and I see it so often, Have you used non targeted sampling with a herringbone layout? If you havn't the use of clr7 is inappropriate anyway I have had so many arguments with consultants about this it is unbelievable. cheers Gareth Rees Contaminated Land Officer, Harborough District Council, Tel: 01858 821174 -----Original Message----- From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Tammy Sullivan Sent: 06 September 2007 20:49 To: [log in to unmask] Subject: Re: CLR7 Test Adam - I would look at your averaging areas and see if you don't have samples from 2 or more populations. Are your outliers near each other spatially? If so, you need to redefine your averaging areas and recalculate your statistics. Additionally, have you looked to see if your sample population has a distribution other than a normal distribution - log normal, etc.? Regards, Tammy -----Original Message----- >From: Adam Czarnecki <[log in to unmask]> >Sent: Sep 6, 2007 4:47 PM >To: [log in to unmask] >Subject: CLR7 Test > >A simple one for you... > >If you perform a CLR7 test and determine that for example the upper 95%ile >estimate of the population mean for arsenic is below the site specific >remedial rarget of 20mg/kg (residential end use) what would you report if >five(out of a dataset of 50) of the sampled concentrations are outliers? >Assume that the development is part of a planning application, not a Part >IIa determination and that all samples are from a topsoil material at 0.5m >depth. > >Would you: > >a) Determine that there is a need to investigate the outliers as they >represent contamination hot-spots; or > >b) Determine that there is no need for any further assessment. > >We (as consultants) are facing different interpretations of the CLR7 test >from local authorities and have also peer reviewed a fair number of other >consultants reports which also have varying opinions. > >Adam <HTML> ** The contents of this message do not necessarily represent the opinions, views, policy or procedures of Harborough District Council. http://www.harborough.gov.uk - Council Website http://www.harboroughonline.co.uk - Community Portal http://www.lutterworthonline.co.uk - Community Portal ** </HTML>