How to build a garden fish pond using pond liner: part 2.

WHEN THINGS ARE NOT SO SIMPLE.

Building a pond in unlevel or uneven ground using flexible liners

Here is how to build a pool with a flexible liner when part of the pool edge emerges above the level of the surrounding landscape, or if the pool is in loose soil or made up ground.

The kit you will need - pegs, level and straight edge are essential along with the obvious pick and shovelThe site for the pond is weed killed in advance with glysophate to make clearance easier: As you can see the site is steeply sloping away from the house.Mark the shape of the pool on the ground and clear a level surface.

1. Mark out the shape of the pool on the ground. You do this with a hose or rope. I often did it with the tape. It would beExcavate to the level of the margial shelf: The marginal shelf is 9inches down from the water level. At least 1 foot in, continue on the second dig there to measure the size of the excavation all round and give me a clue as to how many concrete blocks I would need later

Mark at least one of the pegs with the depth to which to dig

The datum peg and alll the other outside pegs mark the final water level: The excavation is nearly complete2.Establish a datum peg at some point that will mark the water level of the pool. Normally this will be a piece of 2x2 driven into where the pool will be deepest. There will also be an indelible mark on it at the bottom end that will mark the final depth of the excavation.

3. Excavate the pool area as much as necessary to make a level space in which you can drive in several more pegs to the same level as your datum peg. Lay blockwork level with the datum pegThese can roughly mark the deeper area inside the marginal shelf.

4. Several more can be driven in to mark the level of the marginal shelf area and the rough shape of the pool. If you are intending to face the inside of the pool with stone work orThe pool skeleton in place, it doesn't matter that it is exposed on the downward face.: Continue cleanining up the inside in preparation for sand, underlay and liner. brickwork ensure your marginal shelf area is wide enough to support this whilst leaving enough room for plants to sit in baskets.

5. Use the datum peg and several intermediary ones level with it around the excavation as reference in laying a blockwork framework. In loose soil or made up ground, this blockwork will need a footing into consolidated soil.

Where the whole depth of the pool is exposed above ground level...

5a. The shape of the pool must be marked on the ground. From this line outwards by at least 4 inches (10cm), a small 4 inch (10cm) deep trench for a footing must be excavated and filled with a semi-dry concrete 5:1 mix of ‘All-in’ ballast and cement powder. The width of this footing depends ultimately on the thickness of the facing stone or brick that the water feature is intended to have on the inside of the pool or the outside.

5b. Where the pool emerges from the ground to its full depth, the marginal shelf needs to be constructed from blockwork too and backfilled with sub soil.

This will be the skeletal structure for your pool, which will be lined with sand and underlay (particularly on the upright blockwork) and can be faced outside and inside with your choice of materials.

For more information on the basics of 'raised ponds', look out for forthcoming articles. Email us if you want information NOW!

ANOTHER TIP OR TRICK: To have a pool brimming with water
Formal pool with edging of setts This simple pool has a skeleton of blockwork laid onto a thick mortar mix straight onto soil.
A granite set edge is supported by the blockwork whilst the liner comes up behind the sets. In this way, the water level in the pool can be maintained almost flush with the top of the edging stones.

The project featured in the pictures is covered in detail in the book Designing and Creating Water Gardens by Peter J. May and is available from this website. Just click on the name.