Problem with creating a pond

[Rick Hughes]

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.

[Andrew Mawson]

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

[Tim Lamb]

In message , Andrew Mawson writes

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.

[Nightjar]

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

[Chris Hogg]

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.

[The Natural Philosopher]

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

[Rick Hughes]

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.

[Rick Hughes]

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

[Vir Campestris]

+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

[Chris Hogg]

I would also recommend you use a purpose-made pond liner underlay to stop stones in the soil from puncturing the liner from below. Old carpet is sometimes recommended, but it eventually rots away. I wouldn't put large rocks into the pond unless they're very smooth rounded ones, otherwise they too will puncture the liner eventually. Pea gravel should be OK. If you still want to put rocks in there, e.g. for decorative purposes, stand them on a several thicknesses of either off-cuts of the underlay, or off-cuts 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.

The best book I have found for pond advice is The Stapeley Book of Water Gardening, by Stanley Russell, published by David and Charles,

1985. Long out of print, but you may find a s/h copy somewhere.

[harryagain]

Consider using puddled clay instead of a liner.

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.

[Chris Hogg]

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.

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.

[nobody]

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.

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

:)

[Tim Lamb]

In message , Chris Hogg writes

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

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.

[Chris Hogg]

Of course, if the water table outside the pond is higher than the water level in the pond, the liner may rise just like a floating boat. But if the pond is sufficiently full, that won't happen (boats full of water don't tend to float!), and I was taking into account that OP said he was planning to raise the edge of the pond by 6".

[Rick Hughes]

uts of the butyl liner itself, both

Pond is roughly kidney shaped with a shelf 12" wide and 9" deep all round perimeter. see sketch -

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

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

[Rick Hughes]

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.

[Chris Hogg]

:-)

[Rick Hughes]

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 :-(

[Tim Lamb]

In message , Chris Hogg writes

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.

>