Darren we are going through a similar traumas on two sites- and are having the same problem. One of them is a former tip.
My comments would be as follows.
1. you need to ensure that you have an accurate measure of the 95th percentile on the site
2. the next problem is that any DQRA is never really going to be a way forward as the low TDI for BAP means that the modelled value is always going to be very low.
3. the question then is what level of risk have you modelled and as you say 1 in 100,000 seems to be the default.
this is the position we are in except our measured US95 is 14mg for BAP, yours must be much lower than that if the plant uptake makes the difference between pass and fail. Obviously you also need to consider the issue of what concentration would represent an "unacceptable intake" par 12 CLAN 02/05
Personally I would not hesitate to put on the record that I thought a site contaminated by BAP was safe where addition or subtraction of the plant pathway made the difference n the assessment.
We have formed a provisional view that a relaxation of a factor of 3-5 and possibly even 10 would be acceptable for BAP... but it is still work in progress.
If anyone is interested we are also working on a set of screening values to screen in risk of harm rather than screening out.
i.e. a breach of the values in the table would be considered likely to cause significant harm.. thus warranting enforcement action. Any one interested give us a bell.
PS I don't know if many people have replied privately may be you could share a distillation of the comments later
So much to read.
So Little Time
Rob Ivens MVDC- 01306 879232
-----Original Message-----
From: Contaminated Land Management Discussion List
[mailto:[log in to unmask]]On Behalf Of Darren
Detheridge
Sent: 02 May 2006 13:30
To: [log in to unmask]
Subject: Would you make the determination?
I am unsure how to proceed with a Part IIA investigation and am writing to ask for advice.
In one of our Part IIA investigations we have identified PAH contamination in a residential back garden. Based on a risk assessment (BaP) the site only poses a risk to the residents if they were to grow vegetables. The risk is from excess lifetime cancer risk exceeding the threshold of 1 in 100,000 not from non carcinogenic risk. My problem is that the residents are not growing vegetables and do not intend to do, so based on this theoretical significant pollutant linkage should I determine the site as contaminated land?
After review of the guidance 02/2000 circular I note that the definition of 'current use' Section A26 includes any use permitted through planning and includes future uses or developments that do not require a new grant of planning permission. So veg uptake should be considered.
However, the 3rd requirements for significant possibility of significant harm B45 requires that there should be;
'no suitable and sufficient risk management arrangements in place to prevent such harm'. Could the commitment of the residents to not grow vegetables be considered as a suitable risk management arrangement? Or could the SI reports and correspondence being available in the file be considered to be a sufficient management arrangements as house buyer searches would reveal the information and make future residents aware. The residents have also been provided with all the relevant information and have been informed of the risks from contamination. Being made aware of the risks they have a duty to pass this on to future house purchasers. Again could this be a suitable risk management arrangement.
I have spoken with DEFRA regarding this issue and whether veg uptake pathways should be considered for this scenario and their response was that this is a decision that the Local Authority should make.
This is proving to be a difficult situation as management team are of the opinion that we have to assume vegetables could be grown at some point in the future and the site must be remediated. I am not sure whether undertaking remediation of this site would be reasonable given that there are currently no significant pollutant linkages (veg are not being grown) and consider that the cost would far outweigh the benefit (which at the moment would be minimal as veg are not being grown).
Would anyone determine such a site? If not what justification would you use for not undertaking any action? It just seems that sites such as this are not really what the contaminated land regime was designed for and that resources could be spent better elsewhere.
One last point is that through planning we always assume that where there is a residential garden that veg could be grown and we ensure that the land is remediated to this standard. Given this, could we then use a different standard for Part IIA by allowing assessment for veg without plant uptake in a residential garden.
All opinions/ advice would be appreciated
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