We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

--
Algernon

On 30/06/20 18:14, Algernon Goss-Custard wrote:
We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

You don't just put the butyl liner in the excavated earth. You need make
sure you've removed any sharp objects - particularly stones - which
could pierce the butyl liner. Then you need to line the "hole" with sand
or layers of something else several cm thick. That guards against any
sharp objects you have missed. More information he
http://www.pondexpert.co.uk/fittingandfillingaliner.html

So you will have to pump out the pond anyway before fitting the liner.
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will be
equal.

--

Jeff

Yes indeed, you use sand cos it helps with the passage of water as well of
course. I think maybe the pond is a little shallow, but I guess it depends
on what you are going to do with it.
Brian

--
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"Jeff Layman" wrote in message
...
On 30/06/20 18:14, Algernon Goss-Custard wrote:
We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

You don't just put the butyl liner in the excavated earth. You need make
sure you've removed any sharp objects - particularly stones - which could
pierce the butyl liner. Then you need to line the "hole" with sand or
layers of something else several cm thick. That guards against any sharp
objects you have missed. More information he
http://www.pondexpert.co.uk/fittingandfillingaliner.html

So you will have to pump out the pond anyway before fitting the liner.
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will be
equal.

--

Jeff

On Tue, 30 Jun 2020 18:31:18 +0100, Jeff Layman wrote:

On 30/06/20 18:14, Algernon Goss-Custard wrote:
snip

You don't just put the butyl liner in the excavated earth. You need make
sure you've removed any sharp objects - particularly stones - which
could pierce the butyl liner. Then you need to line the "hole" with sand
or layers of something else several cm thick. That guards against any
sharp objects you have missed. More information he
http://www.pondexpert.co.uk/fittingandfillingaliner.html

So you will have to pump out the pond anyway before fitting the liner.
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will be
equal.

Old carpet is a good way to line a pond and protect the butyl liner.

As Brian has already said, 1 metre isn't that deep but with luck it will
be deep enough to prevent the water freezing all the way to the bottom in
a harsh winter.

Cheers


Dave R


--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 30/06/2020 18:31, Jeff Layman wrote:
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will be
equal.

Our rather badly made pond gets water behind the liner. On occasion
there have been big bulges, which is a PITA because once the ground
water has dropped - which doesn't usually take more than a few weeks -
the pond is only half full. Despite all the rain.

Andy
--
Redoing it is on the must do that one day list.

On 30/06/2020 22:01, Vir Campestris wrote:
On 30/06/2020 18:31, Jeff Layman wrote:
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will be
equal.

Our rather badly made pond gets water behind the liner. On occasion
there have been big bulges, which is a PITA because once the ground
water has dropped - which doesn't usually take more than a few weeks -
the pond is only half full. Despite all the rain.

Andy

If the subsoil is heavy clay then the trick is to 'wipe' some of
the excess clay up the sides to cover the topsoil and don't use
a manmade liner. This is how reservoirs and canals were lined
by the Victorians. Just keep it topped up in hot weather to
prevent exposed clay drying out and shrinking. Planting the
usual bog plants around the edges helps to keep sun off the
clay just above water line.

Putting a liner on top of heavy clay runs the risk of water
getting betwen the liner and the clay.

On 05/07/2020 12:44, Andrew wrote:
On 30/06/2020 22:01, Vir Campestris wrote:
On 30/06/2020 18:31, Jeff Layman wrote:
Once the lined pond is full of water, it won't make any difference if
rainwater gets behind the liner as the pressure inside and out will
be equal.

Our rather badly made pond gets water behind the liner. On occasion
there have been big bulges, which is a PITA because once the ground
water has dropped - which doesn't usually take more than a few weeks -
the pond is only half full. Despite all the rain.

Andy

If the subsoil is heavy clay then the trick is to 'wipe' some of
the excess clay up the sides to cover the topsoil and don't use
a manmade liner. This is how reservoirs and canals were lined
by the Victorians. Just keep it topped up in hot weather to
prevent exposed clay drying out and shrinking. Planting the
usual bog plants around the edges helps to keep sun off the
clay just above water line.

Putting a liner on top of heavy clay runs the risk of water
getting betwen the liner and the clay.

On my job list is to remove the liner and dig it deeper.

As we have four species of amphibian breeding in it timing is a bit
interesting...

Andy

On Tuesday, 30 June 2020 18:14:32 UTC+1, Algernon Goss-Custard wrote:
We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

Many ponds are clay lined. The use of plastic/rubber liners is a modernish phenomenon


NT

In message ,
writes
On Tuesday, 30 June 2020 18:14:32 UTC+1, Algernon Goss-Custard wrote:
We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

Many ponds are clay lined. The use of plastic/rubber liners is a
modernish phenomenon

My *no cross posts* rule has wiped most of this thread...

We created a pond in similar circumstances some 25 years back. Dry, low
lying drainage ditch, Summer.

Deepened to around 1m, it had collected about 100mm of water. Cheap PVC
liner on top of old carpets for *softening* and pumped full of water.

All was fine until the Autumn. Curious bulges appeared in the liner as
the water table rose and pond water was displaced through the overflow.

Mitigation attempts with bags of sand were only partially successful. A
more permanent cure was to raise the pond fill height by a further
150mm. Still not 100% but gradually the pond lily roots created a rigid
base and accumulated silt helps.

Basic rules... don't use a lightweight liner unless the planned surface
level is well above the Winter water table, don't allow PVC liners to be
exposed to sunshine, don't allow *water soldier* plants anywhere near,
if planting pond lilies...expect they will fill the pond in a few
years...


NT

--
Tim Lamb

On Tuesday, 30 June 2020 18:14:32 UTC+1, Algernon Goss-Custard wrote:
We have a low-lying, boggy garden with a stream running through it. Come
the lockdown and Lady Goss-Custard decided to have a pond. So we got a
guy in with a mini JCB and he dug a hole about 5.5m by 3.3m by 1m deep.
There is about nine inches depth of topsoil, below that it is all solid
yellow clay.

Having dug the pond, we ordered the butyl liner, only to find it would
take a couple of weeks to arrive. A few days after the digging, and
before the liner arrived, the rain absolutely chucked it down for a
couple of days, so that the surface run-off filled the pond almost to
the top. The level has stayed steady ever since, two weeks now.

In the meantime the liner has arrived. The dilemma is now: Do we leave
the pond as it is, without a liner, on the assumption that it will stay
full of water and the walls will not collapse? Or should we pump all the
water out, put the liner in and pump water back in to fill it up again -
which we foresee will be a very dirty and unpleasant job now that
everything is sodden? If we do put the liner in and refill, what will
happen in the next downpour - will rainwater get in behind the liner and
balloon it inwards into the pond?

If there is ground water, it may need to be drained away ie a permanent drain under the liner. Water under the liner causes it to lift away from the ground.

You need to make sure there are no sharp object to pierce the liner plus you need a "woolly" subliner to protect the liner. Some people use old carpets.

It's a good ie to position any off cuts round the edge above the water level to protect the liner from UV. Esp the South facing edge ie the bit that catches the sun.

Our liner is about 20 yrs old but there is now a slight leak somewhere close to the waterline. Can't find it.