Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

My issue is I have not yet put a liner in, as it keeps filling with
water ......... this is a combination of water 'run-in' and the hole in
the ground is the lowest point in garden, so is - I think providing a
sump where my garden in draining into.

I can't prove it, but there is more water there than be accounted just
by rainfall. Over 12" after just last nights rain.

The base of the 'pond' does not drain, the ground simply holds the water
... I pump it down to about 4" depth but remainder never drains away,
even after 4 weeks of no rain and hottest summer in 20 years. The whole
site is like this, it does not drain.

Obviously I can go in an manually remove water with bucket, to get it
dry enough to add liner.

My concern is, once the liner is fitted, and pond filled, will that be
OK ..... or will the hole still fill and possibly end up with Liner
floating ?

I can't dig a hole under base of pond to act as drain as that would just
fill up the same as ' current hole', if I fitted a pump in there, it
would be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.

"Rick Hughes" wrote in message
...

Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I will
raise the edge by about 6" all round to avoid water 'run in', and have a
sump with float operated pumped overflow to prevent overfill.

My issue is I have not yet put a liner in, as it keeps filling with water
......... this is a combination of water 'run-in' and the hole in the
ground is the lowest point in garden, so is - I think providing a sump
where my garden in draining into.

I can't prove it, but there is more water there than be accounted just by
rainfall. Over 12" after just last nights rain.

The base of the 'pond' does not drain, the ground simply holds the water
... I pump it down to about 4" depth but remainder never drains away, even
after 4 weeks of no rain and hottest summer in 20 years. The whole site is
like this, it does not drain.

Obviously I can go in an manually remove water with bucket, to get it dry
enough to add liner.

My concern is, once the liner is fitted, and pond filled, will that be OK
..... or will the hole still fill and possibly end up with Liner floating ?

I can't dig a hole under base of pond to act as drain as that would just
fill up the same as ' current hole', if I fitted a pump in there, it would
be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.


On the contrary it sounds as though you have chosen the ideal spot for a
naturally filling pond - no need for a liner. We dug one a couple of years
ago in our field that stays filled naturally - only going down about a foot
in dry spells.

AWEM

In message , Andrew Mawson
writes
"Rick Hughes" wrote in message
...

Goal is to create a pond with small pumped water flow over rockery
into pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

My issue is I have not yet put a liner in, as it keeps filling with
water ......... this is a combination of water 'run-in' and the hole
in the ground is the lowest point in garden, so is - I think providing
a sump where my garden in draining into.

I can't prove it, but there is more water there than be accounted just
by rainfall. Over 12" after just last nights rain.

The base of the 'pond' does not drain, the ground simply holds the
water ... I pump it down to about 4" depth but remainder never drains
away, even after 4 weeks of no rain and hottest summer in 20 years.
The whole site is like this, it does not drain.

Obviously I can go in an manually remove water with bucket, to get it
dry enough to add liner.

My concern is, once the liner is fitted, and pond filled, will that
be OK ..... or will the hole still fill and possibly end up with Liner
floating ?

I can't dig a hole under base of pond to act as drain as that would
just fill up the same as ' current hole', if I fitted a pump in there,
would be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.


On the contrary it sounds as though you have chosen the ideal spot for
a naturally filling pond - no need for a liner. We dug one a couple of
years ago in our field that stays filled naturally - only going down
about a foot in dry spells.

I think a liner will be OK provided the maintained water level is always
well above your water table. I had to raise the edge of our liner after
seeing the sand bags I put in to stop the *emptying* surrounded by
bulges in the liner:-)

Over in Herts. the WT is currently exceptionally high. Most years, when
I use a submersible pump to top up the pond from a shallow well, the
pump empties the well and I have to restrict the flow rate. This year
the level only dropped about 1'0" and I was able to pump at the full
output over 24 hours.


--
Tim Lamb

On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill....

IME, overfill is almost never a problem with a pond, short of the whole
garden flooding. My problem is keeping it filled up, even with all the
run off from a large shed roof going into it.

Colin Bignell

On 05/08/13 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery
into pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

My issue is I have not yet put a liner in, as it keeps filling with
water ......... this is a combination of water 'run-in' and the hole
in the ground is the lowest point in garden, so is - I think providing
a sump where my garden in draining into.

I can't prove it, but there is more water there than be accounted just
by rainfall. Over 12" after just last nights rain.

The base of the 'pond' does not drain, the ground simply holds the
water ... I pump it down to about 4" depth but remainder never drains
away, even after 4 weeks of no rain and hottest summer in 20 years.
The whole site is like this, it does not drain.

Obviously I can go in an manually remove water with bucket, to get it
dry enough to add liner.

My concern is, once the liner is fitted, and pond filled, will that
be OK ..... or will the hole still fill and possibly end up with Liner
floating ?

think about the weight of water pressing it down and stop worrying.


I can't dig a hole under base of pond to act as drain as that would
just fill up the same as ' current hole', if I fitted a pump in there,
it would be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On 05/08/2013 20:19, Chris Hogg wrote:
On Mon, 05 Aug 2013 18:15:27 +0100, Rick Hughes
wrote:


My concern is, once the liner is fitted, and pond filled, will that be
OK ..... or will the hole still fill and possibly end up with Liner
floating ?


When it's full, the weight of the water in the pond will counter the
upthrust from the 'coming water' on the liner. Assuming you go for a
butyl liner, and they're by far the best and longest lasting if a
little more expensive, it won't float naturally as butyl rubber is
denser than water IIRC. Presumably you'll be having a variety of water
plants in your pond, in some form of planters or baskets. These will
further hold down the liner and stop it from lifting.


Yep .. deffo on a Butyly rubber liner.
Was thinking of layer of pea gravel at base on pond and on which one or
two large rocks to keep it down.

On 05/08/2013 20:42, The Natural Philosopher wrote:


My concern is, once the liner is fitted, and pond filled, will that
be OK ..... or will the hole still fill and possibly end up with Liner
floating ?

think about the weight of water pressing it down and stop worrying.


I can't dig a hole under base of pond to act as drain as that would
just fill up the same as ' current hole', if I fitted a pump in there,
it would be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.



Just looked no, 36" of water in pond in past 24 Hrs .... then again
next village up has floods - been a tad wet.

On 05/08/2013 18:33, Andrew Mawson wrote:
On the contrary it sounds as though you have chosen the ideal spot for a
naturally filling pond - no need for a liner. We dug one a couple of
years ago in our field that stays filled naturally - only going down
about a foot in dry spells.

+1

If you do want a liner I suggest you build a drain in the bottom, and
stick a hose down there. It's possible that in dry spells you could pump
water from under the liner to on top to keep it full - which is normally
the pod problem.

The 10 tons or so of water you are going to put in it should hold the
liner down

Andy

"Rick Hughes" wrote in message
...
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

My issue is I have not yet put a liner in, as it keeps filling with water
......... this is a combination of water 'run-in' and the hole in the
ground is the lowest point in garden, so is - I think providing a sump
where my garden in draining into.

I can't prove it, but there is more water there than be accounted just by
rainfall. Over 12" after just last nights rain.

The base of the 'pond' does not drain, the ground simply holds the water
... I pump it down to about 4" depth but remainder never drains away, even
after 4 weeks of no rain and hottest summer in 20 years. The whole site
is like this, it does not drain.

Obviously I can go in an manually remove water with bucket, to get it dry
enough to add liner.

My concern is, once the liner is fitted, and pond filled, will that be OK
..... or will the hole still fill and possibly end up with Liner floating
?

I can't dig a hole under base of pond to act as drain as that would just
fill up the same as ' current hole', if I fitted a pump in there, it would
be a maintenance issue, how could I ever get at it ?

Am I wasting my time, and should I give up idea of a pond.

Consider using puddled clay instead of a liner.
http://en.wikipedia.org/wiki/Puddle_clay

Be sure to build your embankment high, it will settle.
I had this problem with my pond.

If you want some large koi I have some surplus BTW.

The liner can float so don't have one.

Use a submersilbe pump. You can just drag it out for
maintenence/replacement.

On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

As others have said, the liner won't float. the water will apply far
more pressure holding it down than the few inches from the water table
pushing it up.

What you could do is put a sump close to the pond with a sump-pump with
float valve and a timer switch. If there is that much water even during
the rally hot spell you could use pumped sump water to top-up the pond.

You'll have loads of evaporation during hot weather which will be
increased more by water flowing over a rokery. Not to mention all the
wild life that'll delight in your kind and thoughtful offering.

If you're planning on putting fish in it then keeping the bottom clean
of gravel, stones etc etc is the best idea. Also feeding additional air
through air stones will help keep the water fresh and moving.

Am I wasting my time, and should I give up idea of a pond.

No. Ponds are awesome. There's not enough of them. Every garden should
have one.

In message , Chris Hogg
writes
On Tue, 6 Aug 2013 08:49:13 +0100, "harryagain"
wrote:


Consider using puddled clay instead of a liner.
http://en.wikipedia.org/wiki/Puddle_clay

I wouldn't. A significant thickness of clay is needed; to quote the
wiki article "The puddle is laid about 10 inches (25 cm) thick at the
sides and nearly 3 ft (0.91 m) thick at the bottom of a canal". That's
overkill for a domestic pond, but it still needs to be several inches
thick. A lot of hard work to put it in place, including dealing with
the delivery of a lorry-load of clay, and there's a real danger of it
drying out and cracking in dry weather, and being penetrated by plant
roots and ceasing to be watertight.

You are supposed to pen a flock of sheep to do the puddling:-)

Be sure to build your embankment high, it will settle.
I had this problem with my pond.

If you want some large koi I have some surplus BTW.

The liner can float so don't have one.

It won't float if it's density is greater that of water (butyl rubber
is 1.3 - 1.5 g/cc depending on grade) and if the pond is full of
water.

Umm.. The issue is not the density of the liner but, if the local water
table rises above that of the pond surface, water can be displaced over
the edge. The pond liner is pushed up by water underneath.

I tried weighting ours down but the proper solution was to raise the
sides and increase the depth of the pond.

Use a submersilbe pump. You can just drag it out for
maintenence/replacement.

--
Tim Lamb

"Pet @ www.gymratz.co.uk ;¬)" wrote:
On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)
I have dug out pond aprox 25' x 5' x 3'.... the garden is one level, I
will raise the edge by about 6" all round to avoid water 'run in', and
have a sump with float operated pumped overflow to prevent overfill.

As others have said, the liner won't float. the water will apply far
more pressure holding it down than the few inches from the water table
pushing it up.

Well actually it will be the *same* pressure as it's water displacing
water. If the lining material is denser than water (I think it usually
is, just) then it will 'sink' and sit where you want it at the bottom of
the hole.

--
Chris Green
·

On 06/08/2013 08:32, Chris Hogg wrote:
On Mon, 05 Aug 2013 21:26:57 +0100, Rick Hughes
wrote:

uts of the butyl liner itself, both
of which you're bound to have.

I know you've already dug the hole, but before you proceed with a
liner, profile it a bit to make some 'shelves' that will be about 6 to
8 inches below the eventual water surface, for containers of marginal
plants to stand on. Not all water plants are suitable for deep water;
a great many like to be just at the surface.





Pond is roughly kidney shaped with a shelf 12" wide and 9" deep all
round perimeter.
see sketch - http://tinyurl.com/o46d7uk
At one end bottom is at 18" below shelf, at the other about 36"
So pretty much as you advise.

Thought about lining 'hole' with underlay, before I put in liner ...
then put in 2-3" of pea gravel at base maybe over a second off cut of
liner"... because of sloping sides actual base is probably only 3' wide
at widest part.
Then a few large rock on the gravel

To allow for overfill, intend digging a small sump outside of pond and
and arrange a pipe at max pond level (hidden under edging) such that if
level rises it will siphon into sump
see sketch http://tinyurl.com/c5reu4r

Will put a float operated 12V boat bilge pump in sump to pump water to
drain ... which is higher than pond

On 06/08/2013 09:49, "Pet @ www.gymratz.co.uk ;¬)" wrote:
On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)

Am I wasting my time, and should I give up idea of a pond.

No. Ponds are awesome. There's not enough of them. Every garden should
have one.



Issue is this is nothing to do with water table ... water table is many
feet lower (below road level) and this pond is at least 6' above road level.

Just looked this morning and pond is now almost full ....
There is some run off from surrounding land.... but as pond keeps
filling even after rain .... I think it's osmotic pressure.

Land drains work by having a pipe (i.e. air space) that has lower
osmotic pressure and water flows into it.
I think having such a damn big hole it is acting as a land drain ... but
with nowhere to drain it to.

I'm hoping (by applying my logic - which may be flawed) that once pond
is lined and filled with water, there will be no osmotic pressure, as
either side of liner it will be water ....... so it should stop draining.

On 06/08/2013 08:49, harryagain wrote:


Be sure to build your embankment high, it will settle.
I had this problem with my pond.

If you want some large koi I have some surplus BTW.

The liner can float so don't have one.



The pond when full of water that has drained in is awful brown mud
colour .... certainly not clean water.
The ground on the site is a brownfield ex industrial (1930's) ... no
earth so and water seeping in would be toxic.

In message , Rick Hughes
writes
On 06/08/2013 09:49, "Pet @ www.gymratz.co.uk ;¬)" wrote:
On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)

Am I wasting my time, and should I give up idea of a pond.

No. Ponds are awesome. There's not enough of them. Every garden should
have one.



Issue is this is nothing to do with water table ... water table is many
feet lower (below road level) and this pond is at least 6' above road
level.

Just looked this morning and pond is now almost full ....
There is some run off from surrounding land.... but as pond keeps
filling even after rain .... I think it's osmotic pressure.

I'll leave others to discuss osmosis:-)

If the natural water level ever exceeds the top of your pond liner you
will have trouble. Initially the liner will bulge upward as the external
water displaces that inside. If the internal water reaches the pond brim
it will overflow.

Land drains work by having a pipe (i.e. air space) that has lower
osmotic pressure and water flows into it.
I think having such a damn big hole it is acting as a land drain ...
but with nowhere to drain it to.

Agricultural land drains are porous and have a gravity fall to the
outlet or to a collector pipe.

I'm hoping (by applying my logic - which may be flawed) that once pond
is lined and filled with water, there will be no osmotic pressure, as
either side of liner it will be water ....... so it should stop draining.

I think from your original post, you said the land drained naturally to
where you want to put your pond and that the only suitable drain was at
a higher level. Pumping from a sump is one solution but you might want
to establish the volume involved. Otherwise concrete tanking might turn
out to be cheaper. Last time I looked, Butyl liner is an arm and half a
leg:-)

I fully concur with the *every garden should have a pond*.




--
Tim Lamb

On 06/08/2013 12:24, Tim Lamb wrote:
In message , Rick Hughes
writes
On 06/08/2013 09:49, "Pet @ www.gymratz.co.uk ;¬)" wrote:
On 05/08/2013 18:15, Rick Hughes wrote:
Goal is to create a pond with small pumped water flow over rockery into
pond (no fish)

Am I wasting my time, and should I give up idea of a pond.

No. Ponds are awesome. There's not enough of them. Every garden should
have one.



Issue is this is nothing to do with water table ... water table is
many feet lower (below road level) and this pond is at least 6' above
road level.

Just looked this morning and pond is now almost full ....
There is some run off from surrounding land.... but as pond keeps
filling even after rain .... I think it's osmotic pressure.

I'll leave others to discuss osmosis:-)

If the natural water level ever exceeds the top of your pond liner you
will have trouble. Initially the liner will bulge upward as the external
water displaces that inside. If the internal water reaches the pond brim
it will overflow.

Land drains work by having a pipe (i.e. air space) that has lower
osmotic pressure and water flows into it.
I think having such a damn big hole it is acting as a land drain ...
but with nowhere to drain it to.

Agricultural land drains are porous and have a gravity fall to the
outlet or to a collector pipe.

I'm hoping (by applying my logic - which may be flawed) that once pond
is lined and filled with water, there will be no osmotic pressure, as
either side of liner it will be water ....... so it should stop draining.

I think from your original post, you said the land drained naturally to
where you want to put your pond and that the only suitable drain was at
a higher level. Pumping from a sump is one solution but you might want
to establish the volume involved. Otherwise concrete tanking might turn
out to be cheaper. Last time I looked, Butyl liner is an arm and half a
leg:-)

I fully concur with the *every garden should have a pond*.





The land where pond is, flat .... so some run-off does end up in the
'hole' but not enough to account for 36" in one day.
Probably only surrounding 200 m2 is possible to run in.
The rest is getting in there by hole filling up from water in
surrounding soil percolating (I assume by osmosis) to the least pressure
point ... i.e the hole.

I have put land drains in elsewhere on this plot, they work by Osmotic
pressure, the fall is to allow it to get away, but it is for 100% sure
Osmotic pressure differnce causes water to go into pipes ... that is how
you can have perfrotaed pipes surrounder by 200mm stone and they drain
....(or be no point in stone underneath) .... I put in 150m of these
connected to a 2m deep soakaway cage system.

Not an option at this part of land.

On 06/08/2013 13:33, Chris Hogg wrote:
On Tue, 6 Aug 2013 12:24:30 +0100, Tim Lamb
wrote:

In message , Rick Hughes
writes

Just looked this morning and pond is now almost full ....
There is some run off from surrounding land.... but as pond keeps
filling even after rain .... I think it's osmotic pressure.

I'll leave others to discuss osmosis:-)

:-) http://en.wikipedia.org/wiki/Osmosis



Dig a hole ... the void has lower relative osmotic pressure than soil
.... water is sucked into it ... if you have good ground it will then
soakaway ... I don't .... so my pond fills :-(

In message , Chris Hogg
writes
On Tue, 6 Aug 2013 12:24:30 +0100, Tim Lamb
wrote:

In message , Rick Hughes
writes

Just looked this morning and pond is now almost full ....
There is some run off from surrounding land.... but as pond keeps
filling even after rain .... I think it's osmotic pressure.

I'll leave others to discuss osmosis:-)

:-) http://en.wikipedia.org/wiki/Osmosis

In between napping over lunch:-) I was trying to think of a simple
experiment to demonstrate the principles involved.

Suppose you borrowed a colander and trapped inside it a section of
plastic bag: perhaps with a Post Office elastic band.

Part fill with water and you have your pond. Now lowering the *pond*
gently into a larger, water filled bowl nothing much happens until the
water levels coincide. However, once the bowl water is higher than the
*pond* water the plastic bag will begin to bulge away from the colander.
Eventually the two levels will coincide and the water mix freely. This
is the point at which a *floating liner* may be relevant as the pond
water may be gently ejected.

My pond liner is PVC (I think) but I don't think floating was the real
problem. My pond is on river gravel where water is free to *spring*
under the liner (much as your situation). The liner prevents the spring
from overtopping the pond bank so water is displaced from the pond
itself.


--
Tim Lamb

On Tuesday, August 6, 2013 2:24:22 PM UTC+1, Rick Hughes wrote:
Dig a hole ... the void has lower relative osmotic pressure than soil

It's not "osmotic pressure", it's "pressure". Osmotic pressure is about
water flowing through a semi-permeable membrane (eg cell-wall) from
a more dilute solution into a more concentrated solution.

/me remembers Mr Ford's biology lessons from 40 years ago.

"Chris Hogg" wrote in message
...
On Tue, 6 Aug 2013 08:49:13 +0100, "harryagain"
wrote:


Consider using puddled clay instead of a liner.
http://en.wikipedia.org/wiki/Puddle_clay

I wouldn't. A significant thickness of clay is needed; to quote the
wiki article "The puddle is laid about 10 inches (25 cm) thick at the
sides and nearly 3 ft (0.91 m) thick at the bottom of a canal". That's
overkill for a domestic pond, but it still needs to be several inches
thick. A lot of hard work to put it in place, including dealing with
the delivery of a lorry-load of clay, and there's a real danger of it
drying out and cracking in dry weather, and being penetrated by plant
roots and ceasing to be watertight.

Be sure to build your embankment high, it will settle.
I had this problem with my pond.

If you want some large koi I have some surplus BTW.

The liner can float so don't have one.

It won't float if it's density is greater that of water (butyl rubber
is 1.3 - 1.5 g/cc depending on grade) and if the pond is full of
water.

It doesn't actually "float" it is water pressure below the liner raises
it.

On 06/08/2013 16:47, harryagain wrote:
"Chris Hogg" wrote in message


The liner can float so don't have one.

It won't float if it's density is greater that of water (butyl rubber
is 1.3 - 1.5 g/cc depending on grade) and if the pond is full of
water.

It doesn't actually "float" it is water pressure below the liner raises
it.


That is my worry.
I know a few large rocks will stop it floating fully, but if it starts
bulging & bubbling in could be a problem

On 06/08/2013 14:58, Martin Bonner wrote:
On Tuesday, August 6, 2013 2:24:22 PM UTC+1, Rick Hughes wrote:
Dig a hole ... the void has lower relative osmotic pressure than soil

It's not "osmotic pressure", it's "pressure". Osmotic pressure is about
water flowing through a semi-permeable membrane (eg cell-wall) from
a more dilute solution into a more concentrated solution.

/me remembers Mr Ford's biology lessons from 40 years ago.



It's also about solution pressure differential ... if you have a 'dry'
area with zero water pressure then that is low osmotic pressure, and the
ground around has a high water pressure, the pressure differential will
cause water to flow across the ground to hole transition point..........
it's the science behind land drains.

On 06/08/2013 14:52, Tim Lamb wrote:


My pond liner is PVC (I think) but I don't think floating was the real
problem. My pond is on river gravel where water is free to *spring*
under the liner (much as your situation). The liner prevents the spring
from overtopping the pond bank so water is displaced from the pond itself.


If that works (with a few large boulders to help) then I'll be happy.

Otherwise I have dug a damn big hole I have to fill in. :-(

On 06/08/2013 16:47, harryagain wrote:
"Chris Hogg" wrote in message
...
On Tue, 6 Aug 2013 08:49:13 +0100, "harryagain"
wrote:


Consider using puddled clay instead of a liner.
http://en.wikipedia.org/wiki/Puddle_clay

I wouldn't. A significant thickness of clay is needed; to quote the
wiki article "The puddle is laid about 10 inches (25 cm) thick at the
sides and nearly 3 ft (0.91 m) thick at the bottom of a canal". That's
overkill for a domestic pond, but it still needs to be several inches
thick. A lot of hard work to put it in place, including dealing with
the delivery of a lorry-load of clay, and there's a real danger of it
drying out and cracking in dry weather, and being penetrated by plant
roots and ceasing to be watertight.

Be sure to build your embankment high, it will settle.
I had this problem with my pond.

If you want some large koi I have some surplus BTW.

The liner can float so don't have one.

It won't float if it's density is greater that of water (butyl rubber
is 1.3 - 1.5 g/cc depending on grade) and if the pond is full of
water.

It doesn't actually "float" it is water pressure below the liner raises
it.




I can assure you it can float.
The big pond that was at marconi had several large bubbles in the liner,
to the extent they looked like whales trying to get out.

All sorts were tried to get rid of them including chucking something
like fifty concrete fence posts on the bottom and drilling holes in to
let the air/gas out but nothing worked for long.

On Tue, 06 Aug 2013 17:12:18 +0100
Rick Hughes wrote:

It's also about solution pressure differential ... if you have a
'dry' area with zero water pressure then that is low osmotic
pressure, and the ground around has a high water pressure, the
pressure differential will cause water to flow across the ground to
hole transition point.......... it's the science behind land drains.

No, it's not osmosis, it's just a pressure differential. Apart from
requiring a semi-permeable membrane (we're talking on a molecular level
here, not a 4 inch pipe with holes in) osmosis needs two solutions, one
with a higher concentration of solute than the other. In your example
the dry side isn't a higher concentration of anything, it's just dryer
(and downhill).

On 06/08/2013 16:47, harryagain wrote:
It doesn't actually "float" it is water pressure below the liner raises
it.

That is floating.

Andy

"Vir Campestris" wrote in message
...
On 06/08/2013 16:47, harryagain wrote:
It doesn't actually "float" it is water pressure below the liner raises
it.

That is floating.

Andy

The liner is denser then water so it can't float in the conventional sense.
It is is hydrostatic pressure raises it from the bed. Or gas as someone else
suggested.

On 06/08/2013 17:53, Chris Hogg wrote:
On Tue, 06 Aug 2013 17:12:18 +0100, Rick Hughes
wrote:



Your use of the term 'osmotic pressure' is incorrect. Osmosis, and the



This 'term' features in exactly this context in several Building text
books ... on Ground works, so maybe it has more than one use ?

That is how they describe the design & action of land drains ...
The perforated pipe as the semi-permeable boundary between water laden
soil and the void within the pipe .... and how the pipes will also draw
water from below the pipe as well as from above.

On 06/08/2013 21:24, Rob Morley wrote:
On Tue, 06 Aug 2013 17:12:18 +0100
Rick Hughes wrote:

It's also about solution pressure differential ... if you have a
'dry' area with zero water pressure then that is low osmotic
pressure, and the ground around has a high water pressure, the
pressure differential will cause water to flow across the ground to
hole transition point.......... it's the science behind land drains.

No, it's not osmosis, it's just a pressure differential. Apart from
requiring a semi-permeable membrane (we're talking on a molecular level
here, not a 4 inch pipe with holes in) osmosis needs two solutions, one
with a higher concentration of solute than the other. In your example
the dry side isn't a higher concentration of anything, it's just dryer
(and downhill).



I'm not a scientist .... but the reference texts on ground drainage
specifically state movement of water into perforated pipes in land
drains is due to Osmotic pressure.

On 07/08/2013 18:26, Rick Hughes wrote:

I'm not a scientist .... but the reference texts on ground drainage
specifically state movement of water into perforated pipes in land
drains is due to Osmotic pressure.

Fascinating. AFAIK Osmosis only has one meaning, and that isn't it.

Andy

In message , Chris Hogg
writes
On Fri, 09 Aug 2013 00:21:13 +0100, Vir Campestris
wrote:

On 07/08/2013 18:26, Rick Hughes wrote:

I'm not a scientist .... but the reference texts on ground drainage
specifically state movement of water into perforated pipes in land
drains is due to Osmotic pressure.

Fascinating. AFAIK Osmosis only has one meaning, and that isn't it.

Andy

IMO the OP means 'hydrostatic pressure', but he's mis-remembered it
from somewhere. The Wiki entry on land drains makes no mention of
osmotic pressure, nor would one expect it to. See
http://en.wikipedia.org/wiki/Land_drains

I knew I was right to stay away from osmosis:-)

I was warned by the supplier of my liner that *sub-surface* water will
share space with that contained in a flexible liner. Apparently they had
a lot of complaints from owners of swimming pools dug in Thames Valley
gravels.

For a flat bottomed pond, laying a few inches of pebbles on top of the
liner might help but the sides can still bulge inward.


--
Tim Lamb