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Pond liners
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 |
Pond liners
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 |
Pond liners
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 |
Pond liners
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. |
Pond liners
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 |
Pond liners
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. |
Pond liners
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Pond liners
Chris Hogg posted
On Tue, 30 Jun 2020 17:17:41 -0700 (PDT), Phil wrote: Clay used to be used before there were butyl liners of course. Leave as is & see how it goes? If it's in boggy ground and has a stream, the hole is probably at or below the water table and will be self sustaining, except perhaps in periods of very dry weather when it may dry up and need topping up from a tap. But that happens to ponds even with a liner. If the stream isn't actually running through it now, you could encourage at least a portion of the flow into and then back out of the pond, either by buried pipes, or by an attractive and landscaped wiggly 'stream', with rocks, slate etc to make it look not like a simple trench. We have pretty much decided to leave it as is without the liner. The level still hasn't gone down - it drops by maybe half an inch after a few sunny days and then rises back up to the topsoil level after rain. We get quite a lot of rain here in Devon so it should be ok. The main drawback is that the clay makes the water cloudy. It is clearing gradually, but I expect the next heavy downpour will stir it up again. At least the dragonflies are now attending regularly. So we now have an unused liner in the shed - too late to return it now. -- Algernon |
Pond liners
On Sun, 5 Jul 2020 07:14:57 +0100, Algernon Goss-Custard
wrote: snip We have pretty much decided to leave it as is without the liner. The level still hasn't gone down - it drops by maybe half an inch after a few sunny days and then rises back up to the topsoil level after rain. We get quite a lot of rain here in Devon so it should be ok. My Uncle used to work for a water authority and specifically used to be responsible for the maintenance of the New River. They would regularly use a long chain with interlinked blades and a handle both ends and 'walk' the river (working upstream I believe) cutting any vegetation that was growing from the bottom. This would float downstream and get caught in the grills and they would have to clear that as well before the water level got too high upstream. I understand that's lined with clay and carries millions of gallons of drinking water from various sources in Hertfordshire down to Stoke Newington. Walking it with the dog it's amazing to think they were able to engineer something like that in the early 1600's and for it to have a fall of only 5" / mile. Uncle would turn in his grave if he saw the lack of upkeep on bits of it now. I think the biggest issue for him were water voles, digging though the clay and that allowing the water to run out, washing away the supporting soil with it. ;-( Cheers, T i m |
Pond liners
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. |
Pond liners
On 05/07/2020 07:14, Algernon Goss-Custard wrote:
Chris Hogg posted On Tue, 30 Jun 2020 17:17:41 -0700 (PDT), Phil wrote: Clay used to be used before there were butyl liners of course. Leave as is & see how it goes? If it's in boggy ground and has a stream, the hole is probably at or below the water table and will be self sustaining, except perhaps in periods of very dry weather when it may dry up and need topping up from a tap. But that happens to ponds even with a liner. If the stream isn't actually running through it now, you could encourage at least a portion of the flow into and then back out of the pond, either by buried pipes, or by an attractive and landscaped wiggly 'stream', with rocks, slate etc to make it look not like a simple trench. We have pretty much decided to leave it as is without the liner. The level still hasn't gone down - it drops by maybe half an inch after a few sunny days and then rises back up to the topsoil level after rain. We get quite a lot of rain here in Devon so it should be ok. Red clay + straw = cob. Many Devon houses built with it, including a new one, as seen on Grand Designs about 10 years ago. The main drawback is that the clay makes the water cloudy. It is clearing gradually, but I expect the next heavy downpour will stir it up again. At least the dragonflies are now attending regularly. So we now have an unused liner in the shed - too late to return it now. |
Pond liners
On 05/07/2020 12:47, Andrew wrote:
On 05/07/2020 07:14, Algernon Goss-Custard wrote: Chris Hogg posted On Tue, 30 Jun 2020 17:17:41 -0700 (PDT), Phil wrote: Clay used to be used before there were butyl liners of course. Leave as is & see how it goes? If it's in boggy ground and has a stream, the hole is probably at or below the water table and will be self sustaining, except perhaps in periods of very dry weather when it may dry up and need topping up from a tap. But that happens to ponds even with a liner. If the stream isn't actually running through it now, you could encourage at least a portion of the flow into and then back out of the pond, either by buried pipes, or by an attractive and landscaped wiggly 'stream', with rocks, slate etc to make it look not like a simple trench. We have pretty much decided to leave it as is without the liner. The level still hasn't gone down - it drops by maybe half an inch after a few sunny days and then rises back up to the topsoil level after rain. We get quite a lot of rain here in Devon so it should be ok. Red clay + straw = cob. Many Devon houses built with it, including a new one, as seen onĀ* Grand Designs about 10 years ago. The main drawback is that the clay makes the water cloudy. It is clearing gradually, but I expect the next heavy downpour will stir it up again. At least the dragonflies are now attending regularly. So we now have an unused liner in the shed - too late to return it now. You may find this of interest http://www.rexresearch.com/dewpond/dewpond.htm |
Pond liners
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 |
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