GCC Wildlife Area - Construct a Pond

Construction of a Pond

Picture of pond with Chuckie pond diping

A pond in a wildlife area is a must. It will be the centre of attraction and will stimulate interest in the other habitats. There is nothing like water to enliven a garden. Even a small area of water will support all manner of interesting pond life and plants. Frogs, toads and newts will use the water for breeding. Hedgehogs and foxes will use the pond as a place from which to drink and birds will use it as a bathing area. Dragonflies and damselflies will be the most appealing of all the insects which will use the water. The pond will be a breeding ground for midges etc. which are an important source of food for bats and a number of birds too.

Preparation

The site of the pond is very important. It should be kept away from trees where a large leaf-fall may cause problems. Leaves fall and rot in the water generating gases and thereby causing a depletion of oxygen. If this is more than is natural for the size of pond, then the balance of the habitat will be upset, i.e. fish will not be able to breathe! On the other hand some shade at the edge of the water, is required to provide shelter to water creatures. It is vital that some allowance is made for excess water to drain away if and when the pond overflows. Access to the pond needs to be safe and easy to allow for viewing and maintenance. A gated fence may be required to control the access of visitors. Remember, children love water and it does not have to be deep to be an accident risk. An associated habitat is that of a bog garden or marsh area, which can be positioned alongside the pond. This needs to be considered at the design stage of the pond, but its construction is dealt with under Bog Garden. Another consideration is that of access for all the creatures which will readily take up residence in your pond. Some parts of the bank need to be constructed so that there are shallow "beaches" for these creatures to climb into and out of the water easily. Close by, there should be planted areas , without access to visitors, so that the creatures can make their journeys safely. The size of the pond will depend on the total size of your wildlife area and could be from just a few metres to tens of metres in length and width. This may governed by budget and digging resources available. Minimum dimensions should be 3m. square and 75cm. deep. It is important that some part of the pond should be this depth to prevent complete freezing, thus providing creatures with deep water protection in winter . If the pond is to be a small one, say , then a pre-formed fibre-glass or plastictype may be the best option. If it is to be of a larger size, say , then it is possible, with a butyl rubber liner to achieve an irregular shape and varying depths. However, the construction of a pond using a butyl liner will be detailed here, since this method can be adopted for any size of pond.

Materials

Flexible Rubber Butyl liner - this is usually bought by the metre and should have a guarantee of at least 10 years' life. The size of this can be determined as follows: Liner width = Pond width + (2 x max. pond depth) + 30cm. Liner length = Pond length + (2 x max. pond depth) + 30cm.

Flexible hose-pipe or rope - to mark out the shape of the pond.

Builders' sand to give protection to the liner - quantity will depend on pond size, but 1 tonne of damp sand will probably cover 10 square meters. Old carpet may be used instead, but this will rot away in time. Fibre-glass insulation could also be used, but beware of the fibres given off whilst handling; they are an irritant.

Plank of wood and spirit level to establish that the pond banks are level.

Polyester matting for protecting the inside of the liner - size as for the liner. Sold in Garden Centres as an under-layer.

Stones to anchor the outside edge of the liner whilst positioning.

Poor garden soil for the rooting medium - this should be sieved to remove stones etc. - do not use compost or enriched soil.

Water - there needs to be a source of tap water nearby to fill up initially and for later topping up. An ordinary hose-pipe is sufficient for most ponds up to a few metres in length and width and with the minimum depth of 75cm. However, if the pond is as large as here, at Garforth(14m. long, 8m. wide and 2m. deep), then consider asking the local Fire Brigade to help fill the pond.

Click on the image to see a large-scale cross section of how a pond is constructed

Construction

1. Mark out the shape of the pond using a hose-pipe or rope. Curves will give a natural look e.g. kidney-shaped, figure-of-eight or pear-shaped.

2. Remove a strip of turf or soil from around the outside edge of the marked shape. This should be at least 30cm. wide and 5 to 8 cm. deep. Save the turf's or soil for later use when edging the pond.

3. Start to dig the pond within the marked area. Decide where there are to be "beaches", where an adjacent Bog Garden is to be situated and where the deep water is to be. Form shelves 23cm. wide and 23cm. deep, as shown in the cross-section diagram, around as much of the pond as possible to provide planting areas. Remove turf, soil and stones for later use.

4. When all digging inside the pond is complete, remove any projecting or loose stones which may damage the liner.

5. Use the plank of wood (laid lengthways and widthways) and the spirit level to check that the sides are level. Adjust as necessary to prevent water leaking away and maybe putting the Bog Garden at risk of drying out.

6. Use the damp builders' sand to form a protective layer 5 - 8cm. thick over the soil sides. Compact it firmly over the contours.

7. Enlist the help of a number of assistants to unfold the liner over the hole. Gently position it and lower into the hole trying to avoid creasing it. The edges of the liner can be anchored with a number of rounded stones or carefully laid bricks.

8. Cover the Butyl liner with some polyester matting as further protection for the liner. Also at this stage, add a layer of poor garden soil or a sand and gravel mix to form a rooting medium on the matting. Do not use compost or rich soil which will contain too many nutrients.

9. Fill the pond with tap-water, easing the liner edges further into the hole as the weight of water increases, taking care not to let the stones fall into the pond.

10. Finally turn back the surplus edges of the liner, trimming off excess material if necessary. The folded liner can then be buried beneath the edging of turf's and or rocks.

11. The water should be left to settle for 2 or 3 weeks before beginning the planting. Early Spring (March) is a good time to start but planting can take place throughout the Summer and into early Autumn (September).

12. Planting. Aim to plant as many native species as possible and select a range of plants which have different habits of growth. Oxygenating plants generally grow underwater and are known as "floaters". They help to keep the water clean, support a variety of microscopic creatures and provide food for water snails. Aquatic plants which grow with floating leaves in varying depths of water, like water lilies for instance, provide shade fron the sun, and so control algal growth. Marginal plants grow in the shallows and in the edges of the pond where it may become a Bog Garden. Such plants generally have taller stems with their leaves and flowers well out of the water. They provide cover for amphibians and places for dragonflies and damselflies to lay their eggs.

Things to avoid:
Overplanting, a balanced pool needs some open water as well as margins of dense planting. Aim to have 2/3 to 3/4 of the water surface planted. Canadian Pondweed (Elodea canadensis) - eventually takes over all other vegetation and is difficult to control. Donations from well meaning supporters - there will be non-native species, some of which will be very invasive.

Native Oxygenators:

Curled Pondweed (Potamogeton crispus)

Hornwort (Ceratophyllum demersum)

Spiked Water Milfoil (Myriophyllum spicatum)

Water Starwort (Callitriche stagnalis)
Native Aquatics (Floating-Leaved):

Amphibious Bistort (Polygonum amphibium)

Common Water Crowfoot (Ranunculus aquatills)

Fringed Water Lily (Nymphoides peltata)

Frogbit (Hydrocharis morsus-ranae)

White Water Lily (Nymphaea alba)
Native Marginals:

Bog Bean (Menyanthes trifoliata) pd = 15-45cm.

Flowering Rush (Butomus umbellatus) pd = 8-15cm.