Water feature experts are learning more every day about the dynamic effect of water on landscape design. Design, engineering and material quantification of water features differs from any other type specification in the field.

Engineering, including structural and electrical, along with plumbing, maintenance and operations are all considerations which must be made well in advance of the final design phase. Because of the unforeseen complexities involved it is advised that if you are not completely familiar with the processes involved in specifying water amenities, you should seek the advice of a consultant or a specialist in the field. Water amenities are oftentimes the highest budget item on a project.

There are a handful of very good consultants and specialists available to the market, and the expense of working with a specialist can be easily compensated through streamlined water cycles, operations and maintenance. Also, it is important to become informed as soon as possible because of the expensive nature of water features. Keeping the client informed as to the final cost of the working water feature can ease the shock to an unsuspecting and inexperienced investor.

The remainder of this article will deal with some of the materials commonly used in the construction of water features, detail some potential problem areas in design and discuss some considerations in generating a materials list.

Concrete is the most commonly used material utilized for urban installations. It is durable, economical, reasonably waterproof, and amenable to a wide range of configurations, finishes and construction techniques.

Cast in place, concrete can be enhanced by the addition of integral color or finished with a variety of textures, including exposed aggregate. Or it could be coated or veneered, using epoxy paint, tile or stone. Precast concrete may be used for display structures or for the pool itself where precise control of the configuration, dimension or surface is required.

Stone is another wisely used material which imparts a richness and permanence difficult to achieve with concrete. Granite is by far the most common natural stone used in water features. Where possible, the stone should be dark to enhance the reading of the moving water and the reflectivity of still water.

Wood, metal and fiberglass are generally used for smaller installations and structures within the water feature itself. Each of these materials offers inherent advantages. Wood absorbs water, sealing joints as it expands, and is inexpensive and simple to construct. Metal, either cast or fabricated from sheets, is water proof and offers a richness and permanence equivalent to that of stone. Fiberglass is waterproof and may be integrally colored or filled with ground or crushed stone to create a natural setting not otherwise available. Artificial rock is gaining in popularity and may be used in almost any application calling for natural stone.

Operating Systems

There are two basic ways commonly used to operate decorative water features. The oldest, and in some cases the most cost effective and reliable method, is to use natural sources of water and let the water flow through the system.

The second way is through the use of mechanical motors and pumps, and typically involves the recirculation of the water. There are two types of mechanical systems?EUR??,,????'??+the submersible pump (located within the pool below the water level) and the remote pump (located outside the feature and water).

The submersible system is generally limited to installations of 100 ft2 or less in an area that is drained clean, and filled every few days in lieu of filtering. Other optional applications include larger, biologically balanced features with minimal displays or temporary, portable or seasonal displays. The primary concerns with submersible pumps are maintenance and electrical safety.

The remote system is somewhat more complex but is actually comprised of sub-systems which are more basic and understandable. Each system has a different task depending on the application and is generally custom built to fill a specific need (see figure 1).

Elevation is the single most important consideration with regard to the equipment space. If at all possible, the floor elevation of the space should be at least two feet below the lowest water level in the pool in order to provide a flooded suction for the pump. If no viable space can be found, a vertical pump inserted into a large pipe or pump below the floor should be considered. If a pump is started automatically each day, any location above the water level (suction lift) will be an ongoing maintenance nightmare, since the pump will periodically airlock and must, at the very least, be protected with a flow switch or a similar device. If at all possible, the equipment space should be located within a building or structure that has horizontal access for maintenance personnel and equipment removal. The location should be as close as possible to the pool or to the lowest pool in a multi-level situation. The dimensions of the equipment space must be adequate to provide access to all equipment and valves. They must also provide code-required clearances around the electrical equipment, as established by local building requirements.

Compiling A Materials List

The hardware involved in a water feature is quite involved and a complete list should be generated during the initial design phase for costing and material list generation. The mechanical system itself can account for a good portion of the feature price. The materials list must be as complete as possible, and usually will not be unless you are familiar with what water features require or you have sought an outside consultant.

Now that materials, components and design factors have been discussed, the specific detailing of water features can be addressed.

Some Potential Problem Areas

Because adjacent concrete pieces are poured at separate times, it is necessary to create good bonding between adjacent concrete and prevent water from seeping through the joint which is created.

Properly located construction joints can act as stress relief joints. Stress relief joints are utilized in pool construction to create a predetermined cracking point. The stress relief joint will permit a natural concrete contraction during the first 24 to 48 hours after casting.

In most construction joints the steel reinforcing is extended through to the adjacent pour. This prevents shear at the joint. Water which enters this joint can attack the corrosive steel reinforcing and can cause joint failure. The steel reinforcing is protected and watertightness is increased by installing a waterstop at the construction joint. This material should be appropriately located to prevent water from attacking the re-bar (see figures 3 and 4).

Expansion joints may be necessary in walls and floors of large fountains or pools. Water contained in the fountain basin will expand 9 percent when it freezes. Also, concrete will expand or contract with temperature fluctuations. In hot weather, water retained in a fountain acts as a coolant and reduces the typical expansion of the concrete. (In some cases, the fountain may be drained for cleaning or repair in the summer.) For this reason, provisions should be made for the maximum expansion of concrete. Large concrete pours can crack due to thermal contraction. Small pours will require expansion or construction joints at slab splices. Large pours can be labor intensive. Larger crews are necessary to ensure quality when pouring large sections of concrete. Installing expansion or construction joints will allow for smaller and better quality concrete panels.

Expansion joints can be classified into two types: full movement and partial movement joints. Full movement joints allow displacement in all directions. These joints should not be located in areas subjected to shearing. Shearing of the joint will lead to rupture of the waterstop. Partial movement joints will allow for movement in one direction only. By inserting a smooth dowel that is bonded to the concrete on one side and debounded on the other, a moveable and shear resistant joint can be created.

Combining some creative genius with technical data should create an exciting and well-constructed water feature. Special attention to material selection and construction techniques will ensure a water feature of lasting value, instead of a maintenance nightmare. An upcoming issue of LASN will examine water feature maintenance programs.

(Special thanks to Dick Chaix of CMS Consultants, Harry Beckwith of Lake Consultants and Construction, Doug Aurand, author of Fountains and Pools, Lee Phillips of Simrock and the staff at Rock and Waterscape Systems for their contributions.)