By Barry Justus
Most people have had the pleasure of walking in the woods and enjoying the beauty of a natural stream, meandering river or magnificent waterfall. These natural water features share a number of common traits.
Water is very much affected by gravity, always running downhill; both subtle and more abrupt changes in grade in a natural setting can result in a waterfall. Of course, in nature, the ‘building materials’ are local, blending in with the surrounding environment and often including aquatic life, such as fish, moss, algae and a whole range of creatures, such as butterflies, birds and mammals.
There are also a number of elements not found in nature’s water features. Mortar joints are not visible between the rocks of a natural waterfall. In a forest, it is rare to see a waterfall without a visible source for its cascading volumes of water. And there is certainly no fibreglass, concrete or plastic in a natural setting.
A pale imitation
It is easy to see why the stunning natural beauty of a water feature is difficult to represent in landscaping and aquatic projects. While many pool and landscape contractors include waterfalls as part of their designs, they often fall short of truly replicating nature. In fact, many waterfalls constructed around residential pools can be accurately described as a ‘pile of rocks.’ These features share few of the traits that make naturally occurring waterfalls beautiful. There are several common drawbacks to the traditional ‘pile of rocks’ waterfall:
- esthetically challenging (do not look remotely like a natural waterfall);
- often poorly built, leaking a great deal of water;
- enormous amounts of heated water are ‘dumped’ into the atmosphere;
- poor design results in noise pollution, especially on large or indoor waterfalls;
- efflorescence, especially when the waterfall is turned off;
- leaching rocks affect water quality; and
- an obvious source of water (e.g. pipes) is typically visible.
While these waterfalls fail to inspire with their natural beauty, they also often fail clients in a number of ways. Leaks are a common problem in poorly designed, inadequately constructed water features. Depending on the size of the water feature, an engineered design may be required, taking into account the prevailing soil conditions. Also, there is often no consideration given to the massive amount of weight placed on the pool deck adjacent to the pool wall.
A waterfall is normally constructed of stone weighing upwards of 878.8 kg/m2 (180 lbs/cf). This massive weight must be supported by substantial concrete footings and deck supports. An ‘A’ frame, doubled up on the side of a panel pool, is not a substitute for proper design. Some of these waterfalls leak so much they can only operate for a limited time before there is a noticeable drop in the pool’s water level. The leaking water can also wreak havoc on the underground structure of the pool and surrounding areas.
There are various methods of preventing leaks in these waterfalls. By starting with a proper foundation shifting can be prevented. Structural concrete with various types of waterproofing admixes such (e.g. Xypex, Aquafin) will result in minimal water loss, while steel or aluminium pans can prevent water from leaking into the surrounding ground.
In these waterfalls, giant boulders are typically just carefully stacked on a rubber liner to avoid any damage. However, the normal method of positioning the boulders used is to mortar the rocks together, often resulting in large, highly visible mortar joints. To remedy this, builders can colour the mortar in an attempt to help them blend in the rocks. Spray foam can be used to control leaking in joints, but only when used in conjunction with a structural leak prevention system.
A common problem occurs in the industry when the pool contractor ‘prepares’ for a waterfall by installing a single, 51-mm (2-in.) line to the location of the water feature. At this point, a separate landscaping company takes over the project. Often there is little or no communication between the two companies with regards to hydraulic requirements and the desired esthetic qualities of the water feature. Project management and proper design will eliminate these types of problems.