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Biscuits?! Or other way to sort out concrete manholes/covers?

Discussion in 'Building' started by kingandy2nd, 27 Aug 2019.

  1. kingandy2nd

    kingandy2nd

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    Hey all,

    Or 70s build house has (unsurprisingly) 70s style concrete manholes with matching covers. Example here:

    49327E87-AEC4-4835-8DB3-5F1EE6A2F9F6.jpeg

    The manhole covers aren’t in great condition, and ideally I like to fit recessed manhole covers for paving. However, due to the sizes the only way I can figure out how to do it is to remove at least one of the concrete rings, install a concrete biscuit and then build a suitable frame for the manhole over in bricks.

    Unless anyone has any alternative suggestions?

    I’ve had to dig one of these manholes out for our upcoming extension, and without exaggerating, it was encased in about 18inchs of concrete all round, and the fragile clay pipes were also encased in concrete. Therefore, while digging the whole thing out and replacing in plastic would be an alternative option, my preference would be to leave the original bases and pipes in place if possible.

    Thanks in advance for your feedback.
     
  2. Tigercubrider

    Tigercubrider

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    What is the question?
    This looks weird on my iPad
     
  3. bobasd

    bobasd

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    is your intention to lower the top of the manhole set a new cover - a "Biscuit" cover?
    or, preferably, to drop or lower concrete lozenge chamber section?
    your future proposition is to cover the area with a brick "patio" including a recessed metal manhole cover to fill with brick?

    you must start with a benchmark for the whole brick patio, and work any levels or falls from your benchmark.
    why dont you clear away around the m/h all soil and loose pieces - dont drop stuff down the hole.
    and then post a new pic of the cleared area.
     
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  4. cdbe

    cdbe

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    I had a similar (ish) situation with my driveway, I flattened the slope which meant I had to take all the corbelling courses off the top of the manhole, leaving a large opening. I used some precast concrete lintels to span this and reduce the size of the opening so I could fit a smaller block paving style cover on top. I can't physically get in anymore but as it's now 2' deep instead of 4' I can rod it from outside.
     
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  5. kingandy2nd

    kingandy2nd

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    Yes, that’s the idea to reduce the level in order to accommodate a recessed manhole.

    Will dig out at the weekend, but it’s likely to just be a concrete ring encased in more concrete!

    Thanks - I did consider lintels, but could work out how to support more than two sides of a new cover with them. Did you get yours signed off by building control - I’ll have to, so I’m thinking they might object...especially as two of the manholes are on a driveway.
     
  6. bobasd

    bobasd

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    OP, you would do better if you post pics of all the manholes and the context/area of the extension/driveway?

    without seeing where your finished levels will be then dig out all around the top sections, and then remove the top sections, and build up with brickwork to accept a new sealed cover. although you can get the concrete sections in various heights that might suit better..
    it might need two of you to prise up the top sections using a spade and wedges.
    thats if its a loose fit - if it wont budge then clean away all debris and come back here.

    the lintel idea wont fly for a couple of reasons not least that all manhole or IC's must be fully lined - no access to soil for rats
     
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  7. kingandy2nd

    kingandy2nd

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    Apologies for the slow reply. Not had a chance to take any more photos yet to be honest, but all the manholes are the same.

    I’m ok with the process to get everything level with the ground etc, but I was wondering if there was an alternative way to approach other thank using biscuits.

    I’ve actually found a local company that fabricates recessed manholes to custom sizes, so I think I might just cut down the concrete riser sections to the right height and then have custom made manholes to fit on top without having the biscuit...which won’t probably save much cost but will save on effort.

    Thanks again :)
     
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