Ground level Drain Vents

In the yard of my flat are two what I take to be air admittance valves for the drain. Very close to this is a roof level vent pipe for the soil pipe. What are these two ground level vents (Side by Side) doing and can they be removed. I ask this as one is damage and they are in the way? Forgot to say there are no man holes to see what is going on!
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In the yard of my flat are two what I take to be air admittance valves for the drain. Very close to this is a roof level vent pipe for the soil pipe. What are these two ground level vents (Side by Side) doing and can they be removed. I ask this as one is damage and they are in the way?
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In article

I have one too on this Victorian house - right beside a manhole. I've a feeling it's rather more than a plain chamber underneath - but can't remember what it's called.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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valves

doing
Then I suspect that you have a manhole chamber (or chambers) that has been covered over. The low level vents were to get air circulating in the drain from low level and up to the 'stench pipe' or stack that was conventionally placed at the head of a drain run. The vents usually start from an inspection chamber placed close to the property boundry.
AWEM
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On Thu, 11 Aug 2011 16:28:36 +0100 Andrew Mawson wrote :

Some older properties have what is called a Buchan trap (qv Google) - effectively an inline U-trap near the back of the pavement with a vertical shaft for rodding. But on the rodding shaft you'd have a cover of some sort, not a grille.
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Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com
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Yes, they are exactly like the vents you get to vent manholes, however there is no manhole, and the house next door is the same, unless someone has buried the manholes?
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I think a photo might be useful. Simon.
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On 11/08/2011 11:39, snipped-for-privacy@scannex.co.uk wrote:

Very unlikely to be AAVs at the *bottom* of a stack - more likely rodding points. What shape are they? As someone else has said, any chance of a photo?
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Cheers,
Roger
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Yes, perhaps rodding points as they are at the back of the house. Not sure how to do a photo though?
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wrote:

valves
the
doing
in
seldom
Yes, perhaps rodding points as they are at the back of the house. Not sure how to do a photo though?
Upload it to a photo hosting site (Flicker , Photobucket etc) and post a link here to where it is. Compressed link from Tinyurl also would be a good idea as long links often get split across lines in newsposts
AWEM
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A rodding point usually has a screw on cover which seals it. A ventilator, a grill.
--
*If tennis elbow is painful, imagine suffering with tennis balls *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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