BEGINNER'S GUIDE TO BUILDING STREAMS AND WATERFALLS: PART 3 The constructive stuff

HOW To Build NATURAL LOOKING WATERFALLS INTO COMPACTED SOIL USING A POND LINER (Definitely DIY method)

This is an extended version of the article The Quickfire Guide to Building Waterfalls (click on the title to go there)

The secret of getting it right is the same as with most building projects. It is in the preparation, that is, in all the work that goes unseen. But you must have a vision in your mind as to what it will look like in the end. Then using the techniques you have decided to employ, you must be able to envisage each individual stage of the construction. There are people that are excellent builders that can build immaculate brick walls and even construct complete houses according to a plan, but give them a project in which they have to copy nature with raw materials then they are stuck. Other people have the fortunate gift of being able to create a natural looking feature that seems like an accident of nature, who may never have put mortar to stone in their lives. So when it comes embarking on a project like this, do what some of the great landscapers of recent times did, take time to go up into the wilds, like the Yorkshire Moors, the Lake District, the Pennines and Scotland, and look to see how things evolve in the real world. Some the waterfalls that have been inspired by places like this can be seen in the Gallery particularly from the likes of Dougie Knight, Brian Aughton and Paul Dyer.

A simple waterfall made from natural stone using a flexible liner: This is the waterfall we are going to buildMATERIALS:

This stream was going to be created using a liner. The pictures show me using a cheap light coloured (and now obsolete) brand that can easily be seen in the photographs, besides which it was given to me (so never look a gift horse….etc). I would normally use Butyl or Rubber which are much tougher and easier to hide.
Get the liner after you have done the excavation. Drape a tape measure through from well down into the pool, to right over the top, to get the length of liner required taking the line of longest travel i.e. the outside line on the curves and right down into any troughs. Take a width measurement at the widest point, once more dwn into the trough and right up the sides of the excavation. Liners come in standard widths and so for economy’s sake it is wise to keep within one of these, but at the same time you must allow for plenty of overlap.
You will need a considerable amount of stone for even a small feature. The stone I have used has all been dug up in the garden since we have lived here. Otherwise this would have been the major expense of the project. For a steep waterfall like this, think in terms of 100kg of stone for every square metre visible face (include the flat). By the time Cutting the stream or waterfall: It should enter at the outward curve of the pool shapethis is landscaped into a rockery, you are using much more. This project probably used the best part of 2 tonnes of stone.
Liner Underlay (I used damp newspaper, but that rots away in less than a year) and sand are necessary for cushioning the liner.
Cement will be needed to seal the stonework to the liner. Overall I have used 200kg of sand and a 25kg bag of cement.
A submersible pump to go in the pool that will be connected to the mains through a conduit under the pool edging, to a waterproof junction box. Allow a performance that relates to the height of the inlet to your topmost header that will give you 300 litres per hour for every 25mm of sill width (i.e. outflow width from the header pool).
The pump requires a flexible hose of the maximum bore that can fit onto it, through which to supply water to the head of the waterfall.

TOOLS: Spade, thumper, stone hammer, cement trowel, shovel for mixing cement, scissors or sharp knife.

SITE and SITE PREPARATION

The position at which a waterfall or stream enters a pool should be on an outward curve of the pool shape. This gives it immediate visual credibility as it looks as though it has helped to shape the pool by wearing into it over a long period of time.
Clear the area of any weeds. This is something you may observe I have been very remiss about. This was to my continual frustration at the time of construction and, without doubt, will be for the future.
In loose soil areas, or where the ground has been made up, I would build up the waterfall or stream shape using concrete blocks. However since the soil was well compacted I was happy to work with shape dug out of the soil.

PLAN OF ATTACK

Forming the outlets from the individual header pools with a mortar reinforced sill: Note the shape of the sill. Deigned to shed the water in a wider flow as the flow increases.Creating dished header pools that will run one into the other and still contain the water as it falls. Dig out the steps for the waterfall. The soil is fairly stable and holds the shape cut into it.
Dig a dish shape to the base so that the waterfall will hold water. This makes for an even and consistent flow. Using a cement mortar mix (3 parts sand to one of cement), reinforce the outlet from the pools in a scooped shape.
Sweep out the dished header pools and brush the mortar smooth and consolidate the soil in the base of the headers. Render them if the base is particularly stony.

Flatten and consolidate the base of the pools.

Consolidating the soil in the base of the pool 'header pools'.
Smooth out a smooth layer of ‘pit’ sand with a trowel over the header pool bases, 25mm deep. Also smear a thin cushion over the outlets. Line out the whole excavation with a geomembrane or underlay.

Putting underlay and sand in the bed of the pools

Lining the waterfall bed

Lay a footing of cement mortar for the facing stones of the bottom waterfall

Laying the bottom waterfall wall facing stones

Lay the liner in place, gathering up the folds into larger folds, ensuring there is plenty of excess material all round, including down into the pool.
Large folds on the flat should be lapped in towards the centre of the waterfall. Large upright folds should be folded flat at the point farthest from the flow and faced away from it.
Try placing stones that you will see, i.e. the facing-stones, in position before cementing them in place.
RULE. Work from the bottom to the top.

Mortar bed for the 'sill stone' by backfilling behind the base stones and building upLay down a good bed of mortar for these first stones and bed them in, backfilling well behind the base stone. Be generous with the mortar on this inside face, as this will hold'Sill Stone' in position back the water. Excess mortar can be cleaned up later as it ‘goes off’. Beware that it does not go into the pool if there is water in it.
Try a flat sill stone in place on the outflow. This will give the water a fall rather than a stream effect.

Bed it in place, filling in around the edges. Make sure it is level or at least the outside edges are and that they are above the middle.
Continue to work up the visible face of the feature.

The base stone to a waterfall needs to be cemented into place on a bed of mortar. The rest of the base of the stream can be filled in with gravel
After backfilling behind the back of the base stone, carry on upwards. To keep it simpler, if not quite as realistic as true nature, keep the stonework level. You find your ‘eye’ for spotting stone develops as the project proceeds – it is like doing a jigsaw puzzle. ‘Africa’ and ‘India’ shapes are particularly useful.

Checking the level of the sill stone

Base-stone for the large facing stone of one of the waterfalls laid on a bed of cement mortar

Facing stone and another sill stone in place

Dont forget the hose.

Before you get too carried away with the stonework, don’t forget the hose that will feed your water supply from your submersible pump to the back of the top header pool. This will unobtrusively emerge from the water near the fall and disappear under the rockery to emerge at the back of the header pool. Also ensure there is a little ‘way out’ or conduit ( a piece of hosepipe is adequate) for the power cable for the pump.

Place flanking stones in position

Working upwards an outwards ensure the level of the liner above and infront of the water flow and held in place by stone

Having bed them on and against a layer of mortar, backfill behind them.

Detail showing the liner at the top of the waterfall backfilled and pinched into place by mortar.

Having gone upwards, work out. Try the flanking stones for the main waterfall in position.
Bed them on mortar and backfill behind.

The liner must be supported up to a level at which it will contain the water flow. Backfill behind the liner, so that it is permanently fixed at this level.

Use small stone to infill gaps and help divert water to the centre of the stream.

Gravel is trailed into the gaps between the stones.

Cutting off the excess liner material

Where water is likely to find an outlet along the liner by 'Capillary reaction, fold theliner back on itself to prevent this: The fold effective acts as a little drain pipe, feeding the water back towards the waterfall

As the side stones go into place like a jigsaw, infill and support with smaller stones.
Gravel is trailed into any exposed mortar joints to disguise them and all of a sudden things look as though they are coming together.
Now is the time to cut off the excess liner material.
At the final outlet of the waterfall, fold the side edge of the liner back in on itself to catch any seepage of water under the stonework and to channel it back into the pool.

Cut of the liner that comes into the pond leaving enough to shed water right into the pond: Later I will hide the remaining liner down into the pool with some facing stones that are supported by the marginal shelf.

Move out from the waterfalls in strata of stone. Also face the inside of he header pools.

Fine adjustments needed

As you work out and up, ensure you stillhave some good sized stone to finish with: It always looks pathetic if the rockery peters out into rubble.

Cut off the bottom of the liner, leaving enough to shed any seeping water well into the pool. Placed stones, built up from the pool marginal shelf, will eventually hide this.
Now the insides of the header pool and around the top need careful landscaping. Whilst keeping the liner well up at the back, the hose needs to be obscured. Strata or terraces of rocks can be laid by cutting into the bank, laying a stone a filling in behind. They look most convincing if the strata move out from each drop in level.
Towards the end some stones needed a bit of judicious adjustment in order to get them to fit. Also, make sure you save some good bits for the end as it will be obvious if the rockery or the stream peters out into rubble at the top or sides.
With the outlet hose now hidden, ensure that end is not too low in the pool otherwise when the pump is turned off it siphons the pool empty often sucking small pieces of gravel back down into the pump
Fit the pump to the hose at the pool end. For the initial trial a clamp wont be necessary.
The only things left to do now are to turn it on and to plant up the rockery.)
The ducks were not sure that they approved.The finished article just planted up.