Hello,
I have two problems related to a sewer manhole.
The first is relatively easy. The manhole cover is cast iron, really heavy, has lost its little lifting bars / rods that used to lie on top of semi-circular "recesses". The manhole cover has cracked and is really, really difficult to lift using an old screwdriver that keeps on slipping out from the "lip" of the cover. For all these reasons I want to replace the cover. The cover is in a small, paved front garden and nothing heavier than a full dustbin passes over it. Can I replace the cast iron cover with a galvanised steel one?
The second problem is related to the first. All of the front garden is paved with some incredibly horrible slabs. I remember when a couple of slabs were lifted years ago that they are laid on tarmac - don't ask me why. The slabs have been down for at least 30 years. The problem is the slabs around the manhole have "heaved". Think of the edges of the slabs next to the manhole have all been "lifted" so that water on them would run away from the sewer manhole. Now the slabs are not moving at all when you stand on them, they feel completely secure. I lifted the manhole cover (with difficulty, see above). I inspected the brick lining of the "sewer access". There the bricks seem all intact and that nothing seems to have moved. However, the bricks just below the manhole cover "frame" are of a different type to those lining the "sewer access pit". The mortar is very rough and bits of slate acting as "shims" are in there too. I am guessing that when the paving slabs were laid the whole level of the front garden was lifted so the manhole cover frame had to be lifted too and it was just bodged up when it was relaid. Now .... I can't see any reason from inspecting the lining of the "sewer pit" why this "heave" is happening. Hence, when I replace the manhole cover and the slabs what is the possibility this "heave" will happen again?
Thanks
Clive