Mark
My view is that on many sites within 250m of a landfill monitoring and
investigation may not be required because the risk of gas migration can
shown to be negligible just from simple desk study information. Equally I
have seen landfill gas migrate 400m and enter a building!
Personally I would take a staged approach and first insist on a desk study.
If the consultant cannot justify a negligible risk of gas migration, a site
investigation and monitoring can be asked for.
The three critical aspects are likely gas generation rates in the landfill,
geology and topography. Is there a credible potential pollutant linkage?
If not then monitoring is not required.
This approach does assume that there is no on site source of gas, which is
rare these days.
Steve Wilson, Technical Director
EPG Limited
Tel 07971 277869
www.epg-ltd.co.uk
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EPG Limited
Tel 07971 277869
www.epg-ltd.co.uk
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-----Original Message-----
From: Contaminated Land Management Discussion List
[mailto:[log in to unmask]] On Behalf Of Mark
Newman
Sent: 14 August 2007 10:50
To: [log in to unmask]
Subject: Extensions within 250m of landfill.....
Hello All,
I asked a similar question a while back, but didn't get much of a response.
I am getting a lot of planning applciations for extensions/conservatories
within 250m of closed landfill sites. I have recently started using the
condition:
"Prior to commencement of development, a site investigation shall be
carried out to include monitoring for methane gas. Monitoring should
include sampling for methane, oxygen and carbon dioxide and should be
carried out over a period of at least 2 months with a minimum of 8
readings taken - spike testing will not be accepted. The report, together
with any recommendations for remedial works, must be submitted to and
agreed in writing by the local planning authority. Such remedial works
must be carried out prior to commencement of construction works. Prior to
the discharge of this condition, details of any remedial measures used
shall be submitted to the Local Planning Authority."
Am i justified in asking for this, or would the condition below be
suitable for these types of applcation:
"A gas impermeable membrane should be incorporated within the structure.
Any services entering/leaving the structure should be located above the
gas impermeable membrane or adequate seals will have to be provided if the
membrane has to be breached. Prior to the works commencing, details of the
gas impermeable membrane should be submitted to and approved by the LPA."
We have very little information regarding gas monitoring in the past, and
what we do have is about 15 years old. So i cannot make a reliable
judgement about whether or not the site is gassing. It is this uncertainty
that makes me want to request gas monitoring each time....
Any input on this would be very gratefully appreciated.
Many thanks,
Mark
(Dover DC)
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