"Andrew Mawson" wrote in message
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"JimG" wrote in message
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Our garden is near the base of an incline where the subsoil is clay. When
there is heavy rain, the lawn becomes sodden and often there is surface
water. Currently considering putting in perforated pipe land drains and
collecting the water in a large underground tank.
The plan then is to automatically pump out the tank when it is full and
here is where I would appreciate some advice.
Should I go for a submersible pump or an above ground pump that will work
with a negative head ie a lift of about 4 feet? Alternatively should I
put a pump in the pit alongside the tank?
Any advice would be appreciated. Thanks.
Whatever you choose make sure that it is 'solids capable' - you'll be
amazed what will end up in it 
However if you have somewhere lower to
pump it why don't you lead your underground drain there and avoid the tank
and pump altogether. (I'm sure that you're not considering dumping it into
the public sewer !!)
are you planning to feed the collected water to your bogs, washing machine
or similar? as that may affect the type of pump you choose,
or were you just hoping to pump it out on a dry day onto next doors lawn
Do you know the depth of the clay layer in your garden?
my garden has about a foot of soil over about a 4 foot layer of clay, so is
a bog a lot of the time, with the exception of the area near my neighbors
conservatory, and that is because when he had it put in, they had to dig
down 6 feet to get the footings through the clay, and as a result that
corner of both our gardens drains nicely.
I keep thinking about renting one of those engines with a big drill bit on
them about a foot wide, and drilling a few 6 foot holes in the lawn, then
either some of that perforated pipe and gravel fill back in the holes,
hoping the rain water would be able drain away down the pipes through the
clay that is stopping it draining in a reasonable time,
But it'd be just my luck i drill into the coal mines that are below us, or
my idea would not work at all.