in haste...

an averaging area was the term used by CLR 7 to refer to the areain which the receptor of concern is being exposed to the contaminants being considered. So in a planning context the garden - or the curtilage of the site - IS the relevant piece of real estate to be considering.

If arguments want to be made for larger areas to be considered then they are being looked at from a source (rather than receptor) perspective and the term averaging zone is one that I have used in both peer review papers and in reports.

kind regards


Paul

PS 20m2 grids implies samples every 4.5ish m; 60m2 grids implies samples every 7.5ish m
PPS CLR 4 discusses hotspots; most SI is not looking for hotspots;
PPPS the statistical or other validity of any SI depends on the aim and objectives - if it is to inform a US95 determination then CLR 4 does not apply


Paul Nathanail CGeol EuroGeol SiLC
Professor of Engineering Geology
Director, eMasters in Contaminated Land Management

---------------------------------------------------------------------------
follow me on twitter: @cpnathanail
join the contaminated-land-management group on linkedin
________________________________________
From: Contaminated Land Management Discussion List [[log in to unmask]] On Behalf Of Ivens, Rob [[log in to unmask]]
Sent: 26 January 2012 10:49
To: [log in to unmask]
Subject: Re: Statistics : The Mean Value Test - Colliery Spoil

I am going to follow up with being difficult.


 1. the data has to be un biased.
 2. the collection points have to represent the strata of interest in the soil.
 3. there needs to be enough data to be representative of an potentially contaminated starta

On the good news I would absolutely agree that a garden is not a reasonable averaging area for planning… but for that to be the case the above have to be covered.

Ah finally to find a thread that’s interesting..

Cheers chaps.
Ps the American DQO stuff gives more…. A good starting point is often grid based

60, 40 or 20m2 grids depending on size of site, and the size of hot spot you wish to hit.

Rob Ivens
So much to read so little time.
01306 879232

________________________________
From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of F J Westcott
Sent: 25 January 2012 17:48
To: [log in to unmask]
Subject: Re: Statistics : The Mean Value Test - Colliery Spoil

Without wishing to add to the statistical debate, I would hesitate to describe colliery spoil as a "relatively homogeneous made ground type". Quite apart from the range of rock types in a typical cyclothemic Coal Measures sequence, it has frequently been subject to varying degrees of combustion, and may also have been reprocessed by coal washing. In terms of arsenic content, I have experienced wide fluctuations associated with the presence or absence of arsenic-rich ironstone within the spoil, which was traceable to an ironstone horizon situated just above one of the several coal seams extracted at the mine. Therefore, if that seam was being worked at the time the spoil was deposited, it would contain high arsenic.

Needless to say this would have been a statistical nightmare, had our old friend the PBET test not come to our aid...


Regards

Frank Westcott
BSc MBA CEng CEnv CWEM MICE MCIWEM SiLC
Independent Brownfield Development Consultant

01726 891453
07973 616197

On 25 Jan 2012, at 13:22, Reg wrote:


In our opinion, prior to undertaking any statistical analysis, the issue of the averaging area requires further consideration. The CL:AIRE\CIEH document still refers to CLR 7, which suggests averaging area should reflect receptor behaviour and therefore might be a single garden, or an open area used by the local community as a play area. This approach to averaging areas is considered applicable within the context of Part IIA, say where an existing residential development is to be investigated.

However, we consider the concept of a single garden as an averaging area to be inappropriate in the context of brownfield redevelopment, which is regulated by the planning regime. In this context, contamination across the entire site should be characterised by reference to the CSM. Consequently, we analyse sample results by fill type before undertaking statistical analysis; ie the averaging area is related to the extent of a particular fill type.

Analysis by soil\fill type is appropriate for essentially immobile contaminants associated with a particular fill type, for example arsenic in colliery spoil, metals in ash & clinker, sulphate in plaster-rich demolition rubble etc.

Obviously, for this approach to work we need plenty of samples from each fill type; an absolute minimum of 6 and often many more. Some interesting work by Prof Mike Ramsey at the University of Sussex highlights the importance of plenty of samples, even in relatively homogenous made ground types such as colliery spoil. See their website for more: Ramsey<http://www.sussex.ac.uk/lifesci/ramseylab/research/soil-application>

Mark Perrin
Lithos Consulting Ltd

M 07703 396635
DD 01977 684 801

www.lithos.co.uk<http://www.lithos.co.uk/>



From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Anthony Luke
Sent: 24 January 2012 14:25
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Statistics : The Mean Value Test

Good afternoon everyone. I hope that I may draw upon your expertise and experience in relation to the statistical analysis of real environmental datasets for Part IIA. I hope that the following scenario and suggestion make sense.

CLR7 included the mean value test, whereby the 95% lower confidence limit of the mean was compared to an assessment criterion. CLAIRE published a paper in 2006 expressing concern that the mean value test could in some circumstances be non-conservative. Following the withdrawal of CLR7 the updated CLAIRE guidance does not include the mean value test.

My suggestion is this: Given that GACs are in themselves conservative, the mean value test may still be safely applied to real datasets where the GAC is used as the assessment criterion.

All thoughts and comments welcome.

Anthony

Dr. Anthony Luke
Principal Officer (Contaminated Land)
Transport, Environmental and Community Services
The Highland Council
Environmental Health and Trading Standards
38 Harbour Road
Inverness IV1 1UF

telephone 01463 228703
mobile 07766 298104


Unless related to the business of the Highland Council, the views or opinions expressed within this e-mail are those of the sender and do not necessarily reflect those of The Highland Council, or associated bodies, nor does this e-mail form part of any contract unless so stated.
Mura h-eil na beachdan a tha air an cur an cèill sa phost-d seo a' buntainn ri gnothachas Chomhairle na Gàidhealtachd, 's ann leis an neach fhèin a chuir air falbh e a tha iad, is chan eil iad an-còmhnaidh a' riochdachadh beachdan na Comhairle, no buidhnean buntainneach, agus chan eil am post-d seo na phàirt de chunnradh sam bith mura h-eil sin air innse.


Have you tried www.molevalley.gov.uk<http://www.molevalley.gov.uk/>? Our easy to use, accessible website allows you to access our services at any time. You can look at planning applications, pay bills online or find out more about where you live using the Mole Valley and Me feature.

Please note that calls to the Council may be recorded and monitored for training purposes. The computer system may also be monitored and recorded to secure the effective operation of the system and for other lawful purposes. This email and any files transmitted with it are intended solely for the use of the individual or entity to which they are addressed. If you are not the intended recipient, the E-mail and any files have been transmitted to you in error and any copying, distribution or other use of the information contained in them is strictly prohibited.

This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham.

This message has been checked for viruses but the contents of an attachment
may still contain software viruses which could damage your computer system:
you are advised to perform your own checks. Email communications with the
University of Nottingham may be monitored as permitted by UK legislation.