Thanks Chris
Yes we came to same conclusion that the allotments were not Part 2A contaminated land.
Regards
Christopher Taylor
Enforcement Officer
Regulatory Services
Brent Council
Tel: 020 8937 5159
www.brent.gov.uk
-----Original Message-----
From: Contaminated Land Management Discussion List [mailto:[log in to unmask]] On Behalf Of Chris Dainton
Sent: 23 April 2015 09:54
To: [log in to unmask]
Subject: Re: Wood ash / Allotment BaP
Hi Chris
Thanks for the data set. Interesting numbers for sure.
To add to the debate - I've done a quick and dirty data crunch using our screening tool.
Apologies for the pasting of the data - the JISCMail System doesn't like tabs or tables! Hope the data renders OK in the message.
Allot Data Set NO C4SL Av UCL Max >C4SL Outl
Allotment-1 10 5.7 12 22 26 8 0
Allotment-2 10 5.7 2.8 5.9 7.1 2 0
Allotment-3 10 5.7 1.9 5.6 8.7 1 0
Allotment-4 14 5.7 4.2 8.4 12 3 0
Allotment-5 28 5.7 5.9 8.7 14 14 0
Allotment-6 5 5.7 4.2 6.1 5.3 0 0
Allotment-7 8 5.7 1.8 3.1 3.2 0 0
All Allot Data 85 5.7 5.0 7.1 26 28 0
No = sample count
C4SL = same for all standard SOM (1% to 6%) Av = Average UCL = Upper Confidence Limit on the Mean (non-normal data) Out = Outliers test (0= no outliers detected)
Clearly BaP is being detected at 'elevated' levels in some of these samples (by elevated, I mean compared to typically encountered ranges I see in garden/imported top soils .... dare I say).
Some of these top soils probably wouldn't get through planning if these were new allotments requiring planning permission, especially if you apply the (lower) S4ULs first....
But is there a Part 2A Problem? To me, based on this data, most look Cat-4 (using average values), perhaps some lower end Cat-3 at worst?.
Based on the data, Allotment-1 clearly isn't ideal compared with the C4SL, into Cat-3 (being bold) I would think, but surely not Cat-1 or Cat-2 determinable with an average of just 12 mg/kg (c. 2xC4SL)?
Out of 85 samples:
28 (33%) are >1xC4SL
8 (9%) are >2xC4SL
2 (2.5%) are >3xC4SL
1 (1%) is >4xC4SL
0 are >5xC4SL
No Outliers identified in the data set as a whole
All interesting stuff. Cheers for starting the thread.
Chris Dainton
Peak Environmental Solutions
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