Building a pond

by Richard Jones

I've been building, not so much a garden pond, as a playground pond. And the first problem with playgrounds is that they are all-over tarmac.

Completed new pondI've been building, not so much a garden pond, as a playground pond. And the first problem with playgrounds is that they are all-over tarmac. The obvious site for Ivydale Primary School's new pond was a sunny, but extremely bleak corner next to the electricity sub-station building. Digging up the hard-standing was never a possibility: too much effort, too much time, too much money, too much noise, and too many pipes and cables running who knows where. So we opted for above-ground construction instead.

First stages of pondFirst, we laid out four sleepers in a square, then stacked the others on top like a game of giant Jenga. Simply screwed together at the corners, they sit in place quite happily. Next we piled in a cubic metre of gravel for drainage, and sat the fibreglass liner on top of it. The raised pond in our garden at home is a similar construction. Ours is triangular, so we had to borrow a chainsaw (it's remarkable the number of people in south-east London who just happen to have a chainsaw). We used a butyl liner, but discovered our mistake when it sprung a leak (or was it punctured by small child with stick? We shall never know). At the school, toughness is all, so a robust, moulded fibreglass insert is perfect, and hopefully damage-proof, when it comes to pond dipping later in the year.

Nearly completed pondNext we filled in the area around the fibreglass with topsoil, logs, rocks and pot shards to give the pond edges texture, sheltering crevices and support. We landscaped the soil between the liner and sleeper frame, and filled the pond with water.

We're not quite all the way there. The pond is full of water and has already taken on a deep green bloom as the algae and microbes start to establish an ecological balance, but the pond surround needs to be planted up and after the soil has settled we'll need to back fill a bit more.

We're going to have to put up a sign explaining that the pond will not have fish in it. It's a wildlife pond, and in my book fish and wildlife do not mix. And it's unlikely that frogs or toads will find their way across the barren and exposed playground tarmac to colonise it. It will be an invertebrate-friendly pond. It's already home to some daphnia (water fleas) brought in with the water lilies and some water skaters that have flown in from some pond or other further down the road. It will not be long, though, before it is crawling with life.

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Gardeners' World Web User 07/07/2010 at 19:28

just the article i want to read about,could you give me some ideas how i could create a rectangle pond..should i do a concrete one or liner,the reason for this is i have managed to buy some land at the side of my property and im going to put up a large pergola and i wish to put in another pond but i was hoping size wise::::about 5ft long and pos 1ft wide depth prob 2ft with some shelf areas in pond...i just wanted it to look long and elegant im then gonna put lots of grasses etc in and around unsure how to go about this as i back onto woods and there are very large oak trees rather close and im worried about there roots damageing the pond if i do a liner and if concrete im worried about movement and the concrete you know anywhere i could get a plastic one made up with my own measurements..

Gardeners' World Web User 11/07/2010 at 16:15

Very wise. My concrete pond, put in in 2008, by professionals, leaked last year. It was repaired by the people who put it in and is now leaking again. As for wildlife it has been very successful with many frogs and newts. I am now wondering what to do as the water level is very low!

Gardeners' World Web User 12/07/2010 at 20:20

Reply to Sarah's Pondlife Sarah, fibreglass inserts are probably the toughest and easiest option. Not sure whether you can find one the right shape though, most are sculpted into kidney shapes to make them look more natural. You could always try and make a frame using wooden sleepers, then the butyl liner. The inside of the pond need not be so right-angular, since the wooden frame would give the architectural effect you are after.

Gardeners' World Web User 17/07/2010 at 12:51

I built a pond in my terraced house garden, probably a bit smaller than that in the article, but it is square and I used a pond liner. I achieved the shape by simply folding over the edges like if you were wrapping a present, only the edges are on the inside. as long as all of the the liner reaches above the water line it doesn't matter how many folds and creases you have, it all flattens out when you put the water in, you can hardly make them out now the pond is fully established. I used sharp sand to ensure the liner doesn't get punctured, make the sand a little wet so you can paste it to the sides of where your pond liner will go. I also suggest you put a couple of shelves in, 5-7 inches deep for border plants and 2-4 inches deep for birds to bathe and drink from. Our pond is now 3 years old, and although we have koi and gold fish, there are also a large number of invertabrates living in the water, sheltering between the plants. We have included a water fall in the pond, and the lillies dont seem to mind, but no fountain, I think that detracts from the natural look.

Gardeners' World Web User 18/07/2010 at 17:43

In a previous house our pond was created using a clay and sand base, with concrete walls. I'd like to do the same again, but need advice. The lilies were able to grow naturally without the need for pots, but there was an annual task of clearing out the bottom of tangled vegetation and mulch. The clay base made the job difficult and you'd often loose a welly in the process. Overall I liked the design as it encouraged newts, water boatmen and all manner of other pond wildlife to get established naturally - and fish had a plentiful supply of worms. I preferred it to using a plastic liner as the ecology seemed very balanced. Due to the level of mulch, the fountain had to be strong and the filter cleaned regularly. Now to my question, instead of running a mains powered pump, I would like a solar water fountain but I don't know if it is strong enough to pump in this type of pond ie one with a lot of mulch?

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