In article ,
says...

Because the grass wouldn't grow very well in a part of my back lawn (and
area which looked like a rather ugly 'hump'), I decided to excavate.
Having found concrete about 10cm under the turf I eventually found a
concealed manhole cover.

On investigation I seem to have found a disused cesspit made of
concrete, with iron supports inside, measuring about 5 metres long, 3
metres wide and 3+ metres deep. It seems to be totally empty albeit
there is 30cm or so of water at the bottom. I do know that my house was
connected to mains sewage about 15 years ago, and I had assumed the cess
tank would have been filled in or removed. I can not see any outlets,
which has led me to conclude this is not a septic tank. There is one
inlet pipe which is not connected to anything as far as I can tell, I
suspect the water seeps in through this pipe from the garden above.

Does anyone have any advice as to what to do with this, and who can do
it without spending £000s? It looks horribly dangerous as well as being
an eyesore over which grass will not grow properly.

The options seem to be:

1. Fill it in, which would take many, many tons of rubble, and would
not solve the eyesore/grass problem;
2. Remove it, which would probably be very expensive and would still
leave an enormous hole needing to be filled in anyway;
3. Knock it in on itself and then bring it up to ground level with more
rubble as needed, then cover the final 30cm or so in ballast/topsoil.
Trouble is, that looks incredibly dangerous and difficult to achieve.

Thanks in advance for any advice





As Mike says use it, or take the top off and turn it into a pond (line it
don't rely on the concrete)
See the thread on grass not growing and you will see its not a good idea
to fill it with rubble as the grass will never grow properly
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea