ENSR cover Model supposed to be released shortly as a BRE digest, but
without Environment Agency backing. If DEFRA/EA do not endorse the
document, where does that leave LA's?
Ray
-----Original Message-----
From: Ivens, Rob [mailto:[log in to unmask]]
Sent: 23 July 2003 17:35
To: [log in to unmask]
Subject: Re: CLEA Exposure duration...
Isn't the key receptor generally regarded as the 1-6 year old female and
isnt the duration of exposure normally taken to be over those first 6 year
of the infants life.
I just ran the calcs twice
1-6 year old female = 19mg
lifetime adult= 61mg.
so personally I think this consultant is not going to do terribly well
unless he can guarrantee having sterile occupants. Otherwise I dont think it
is unreasonable for people to occupy a house for 6 years and I assume CLEA
takes into account seasonal variations of activity otherwise there wouldnt
be much point in having a standard conceptual model.
in a case like this eg where arsnic is present above the guidline value up
to ~ 60-70mg we would ask for a minimum of 300mm but I am advised by people
who know better that we ought to ask for 1m but this would be a hell of a
fight.
ps does anyone know anything more about the BRE/ENSR capping model?
-----Original Message-----
From: Dr Kevin Privett [mailto:[log in to unmask]]
Sent: 23 July 2003 16:16
To: [log in to unmask]
Subject: Re: CLEA Exposure duration...
As I understand it, the CLEA model is based on generic exposure conditions.
These assume exposure through various routes for 70 years of life and these
were chosen by the authors of the model for a reason. It is unlikely that
somebody would live in the same house for 70 years. However, if they choose
to, they can be sure that CLEA has protected them. In this way, it is a
worst-case scenario but one which is not over the top like some worst cases.
The model can be run for any different exposure conditions, such as a lower
occupancy as suggested. This will derive exposure-specific values. We are
advised to do this except in the cases where we consider the generic
conditions do not apply. The process must be transparent and justified. The
key here is to justify the assumption that people only use a garden for 4
months. I would want to know why this development should be different from
those envisaged by the authors where the generic 365 days applies. A
house and garden is a house and garden. Can the consultants be sure that
nobody will use the gardens for the full 365 days? If so, OK.
Regards,
Kevin.
Written: 23 July 2003 16:05
Dr Kevin Privett
Principal Engineering Geologist
SRK Consulting
Windsor Court
1-3 Windsor Place
Cardiff
CF10 3BX, UK
tel: +44 (0)29 2034 8150
direct line 2034 8156
fax: +44 (0)29 2034 8199
e-mail:[log in to unmask]
url:http://www.srk.co.uk/
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-----Original Message-----
From: Contaminated Land Regime Discussion List
[mailto:[log in to unmask]]On Behalf Of Charlie
Packham
Sent: Wednesday, July 23, 2003 3:56 PM
To: [log in to unmask]
Subject: Re: CLEA Exposure duration...
I see the consultants point that people don't necessarily use their gardens
all year round but apart from this presumption no justification has been
provided except that the guidelines are derived from an exposure equation -
where the target value is in a linear relationship with the exposure
duration in days/years and the summer season is 4months.
The development includes private gardens and an area of proposed paving
which would in effect break the pathway within this area. However any future
owner of the property might change this area eg. into a veg. patch in effect
recreating the pathway.
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