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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