Laying concrete in water - Can i tank with dpc?

[michael e]

I`ve dug footings for a retaining wall but hit bedrock at 250mm deep. And there is a small stream from an old land drain which appears half way along the 6 metre trench. I cant divert the stream and although there is a good run off, there is about 1 inch of water

2 questions:

Can I 'tank' the trench with DPC membrane and pour the concrete in?

I want to put a land drain on the foundation, behind the wall. Can I get away with 150mm deep concrete, sitting on the bedrock? The new foundation will abutt the existing foundations for a garage so there shouldnt be any forward movement.

thanks

Michael

[lutonlagerlout]

dont see the need for membrane in the footing,and yes 150mm of crete on top of rock is fine
is it just a land drain or a real stream?
LLL ???

[michael e]

thanks. i`ve got a roll of membrane anyway and it was more to avoid having to lay the concrete into an inch of running water. I was concerned whether it would cause any problems I hadnt thought of. Cant tell whether its a stream or old land/field drain, but the aim is it either runs off behind the foundations and away at each end or the level rises up to the land drain Im putting in on top of the foundations behind the wall i`m going to build. The wall will be about a metre back from the rear wall of my garage.

The foundations will abutt the garage concrete base, and this whole project is to stop water entering the garage (the whole area at the rear of the garage was backfilled with earth and rubbish and water built up and then came through into the garage. Do I need to make sure the new land drain behind the new wall is completely below the level of the garage concrete base, or can I get away with it being half way below - which will allow me to make the foundations a little thicker?