The Brew Cabin

Hi all..

I am considering block paving my front drive, an area of approximately 111sq metres. In front of the garage are two cast iron pipes running underground to a soakaway. I have tested the drainage ability of the soakaway and it seems fine (garden hose running overnight, etc). The house way built in about 1930.

If I pave the drive it would seem logical to put in a 300x300mm type grating on the top of the soakaway as I have no other drainage apart from surrounding grassed areas.
I estimate the top of the soakaway is approx 400mm below the surface and therefore excavating the existing surface to prepare the sub-base would probably lead to me encountering it anyway.

My questions are:

1.What type of soakaway construction was employed in 1930?
2.Would digging down to it and putting a drainage grate on the top be sensible/logical?
3.What would the possible diameter of the soakaway be?
4.Supposing that the soakaway might be 4-5 foot in diameter, what could you cap it with?



Many thanks in anticipation.

You asked...

1.What type of soakaway construction was employed in 1930?

Whatever they thought would work. A big hole filled with inert rubble and/or gravel was popular, whereas we now use plastic attenuation systems or specially designed chambers.


2.Would digging down to it and putting a drainage grate on the top be sensible/logical?

I'd probably avoid disturbing it as much as poss. I'd dig off for the paving, and then put a layer of permeable mebrane (say Terram 1000) over the top of the soakway, with a metre or so of spread all around, and then use something like a 300x300mm grating or even a single length of linear channel drain to form a drainage point over it.


3.What would the possible diameter of the soakaway be?

Think of a number: double it: add 15: take away the number you first thought of: subtract the age of your milkman's dog and multiply by the Planck constant....that's as good a method of estimating the possible diameter as any other!

There are no set rules for soakaway sizes on properties of that age. It could be a simple sand drain that's only, say, 225mm in diameter, or it could be a whacking great 'ole of 3, 4 or even 5m diameter.


4.Supposing that the soakaway might be 4-5 foot in diameter, what could you cap it with?

A cover slab would be easiest, but, if it is a rubble-filled hole that is stable, then the Terram sheet, with a simple bottomless brick chamber as a 'gully' would be fine.