My view would be that if you wish to consider the gardens individually
on this basis you do not have enough data to make an assessment and you
should have the consultant recover 3-4 samples per garden this will give
you enough data to have an averaging area for each individual garden.
-----Original Message-----
From: Contaminated Land Management Discussion List
[mailto:[log in to unmask]] On Behalf Of Wendy
Lilico
Sent: Thursday, December 22, 2005 9:18 AM
To: [log in to unmask]
Subject: CLR7 and averaging areas
I have asked this question a while ago and got some useful answers but
can I be a bit more specific this time....
I have a large housing development subject to a remediation scheme which
includes testing soils prior to importation and again once the material
is in-situ (on the basis of one sample every 2-3 plots). This is my
preferred system as it guarantees that the material is the same, or at
least as 'clean', as the material tested at source but source testing
avoids importing clearly unacceptable material in the first instance.
Anyway there have been a number of in-situ samples which have come back
with results over the SSTLs for one or two determinands (usually zinc,
boron or nickel). The consultant originally proposed that the whole
volume of soil imported from a single source should be considered a data
set for the mean and maximum value tests and, whilst that may appear
reasonable in theory, in practice it involves a large area of the site
with discontinuous plots often at considerable distance from the
'failed' sample. It is my opinion that once the material is placed it is
academic if the material at distance from the individual plot is
acceptable - it is the exposure of the receptor at that particular plot
which is important ("an averaging area (or area of
interest) is that area (together with a consideration of depth) of soil
to which the receptor is exposed or which otherwise contributes to the
creation of hazardous conditions" CLR7)
The question then is what is a reasonable 'averaging area' in these
circumstances?? I draw a clear distinction between a planning assessment
and a Part IIA assessment where it will usually be necessary to test
each area of ownership to a sufficient extent to make a definite
determination of whether it is 'contaminated land'.
Any comments would be much appreciated as usual.
Meanwhile may I take this opportunity of wishing you a very happy
Christmas and thanking you for all the help and advice throughout the
year. I personally find this forum invaluable - and even entertaining on
occasions - what more could you want for Christmas !!
Cheers
Wendy Lilico
Principal Environmental Health Officer (Pollution) Development and
Environment Darlington Borough Council
11 Houndgate
Darlington DL1 5RF
Directline (01325) 388570
Mobile 0779 088 4198
Fax (01325) 388555
email: [log in to unmask]
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