Diversification is often the key selling point of a project. Developers and investors not only want their projects to be different than those around it, but they also want them to be better. Differentiation is achieved through original and unique architecture, site planning and land use. All of these must be maintained within the budget of the investor.

As discussed in previous issues, water features will give the desired effect and the unique image sought by an investor. Because of the expensive nature of water features, Landscape Architects and designers must keep the client informed of the cost of the feature, from the initial design outlay to the final working feature. This is good, but not complete. Equipment, operations and water maintenance costs are often not figured into the cost of the water feature because they are not part of the original design and installation cost. Maintenance of the equipment and water, depending on the size of the feature, can be extremely expensive. If these costs were not properly evaluated in the initial stages of the design process, a water feature is very likely to end up a stagnant eye sore or a planter.

Water features can attract people like no other single site feature. But, and here is the catch, that same water feature can also be the one thing that turns people (and potential investors or tenants) away from the site. There is nothing attractive about a water feature – no matter how beautiful the design – that has brackish, discolored, smelly water going through the system. Not only is this revolting to the viewer, but it would also drastically change a persons attitude about the whole project.

There are several specialists who can make out maintenance plans and estimate the costs for any design if they are provided with all the design information. If the maintenance and operation costs are properly considered in the design phase, it may drastically affect the design of the feature. You cannot expect the client to be aware of the expense or even the need of the maintenance program. Someone in the design chain must be responsible (specifically) for this part of the feature.

Operations and Equipment

One of the most important factors of the maintenance is the equipment used in the actual operation of the water feature. The equipment is comprised of the water display systems, support systems, filtering systems, drainage systems, and piping systems.

The water system includes all the fixtures involved in the display itself. This system is made up primarily of fittings, valves and strainers. The hardware is generally the same size and same material as the piping. Gate valves are suitable for shut-off only, while butterfly valves, globe valves and ball valves and cocks may be used for shut off and throttling. All strainers should be fitted with brass or stainless steel baskets.

Support Systems

As a group, the support systems are subsystems used to help maintain the quality and level of the water in the pool and to facilitate cleaning. The filter system uses a circulating pump, a line strainer, and shutoff, check, and throttling valves in the same way as the display system. One of the most common systems returns the water to the pool through a filter medium consisting of fine silica sand supported on the base of heavier sand and gravel. This medium is contained in a steel or fiberglass tank and is generally considered a permanent fixture.

The next system involved is the fill system which establishes the static water level (in conjunction with overflow) and maintains the operating water level. The water supply is usually hooked up to the domestic water supply on which a backflow preventor is attached. This prevents back siphoning of potentially contaminated fountain or feature water into the domestic water supply. Generally installed in the equipment space, below grade and/or below the water level, it requires a reduced pressure type device (see figure 1).

Working in conjunction with the fill system is the overflow and drainage systems. These systems establish the static water level and provide for draining of the pools, piping and equipment. Cleaning and for shutting down the feature to prevent damage from freezing pipes is also a function of these two important systems.

Pump Selection

Pump selection and data for other than aerated types and for sculpted jets may be derived from a manufacturer’s catalog. There are three conditions that must be optimized when selecting a pump: flowrate, head, and minimum net positive suction head. All flowrate data and requirements must be totaled. The required flow at any weir may be reduced by the amount that the jets or other weirs contribute to the source of the water. The head is the total pressure required to accomodate the differences in elevation between the highest and lowest pool levels (static level differential, see figure 2), and all total calculated pressure required for the desired water affect. To create the desired pressure, after all natural pressure factors have been considered, the proper size pump must be selected to put out the correct amount of pressure for efficient and effective water cycle. In general, efficiencies of 70-90 percent (increasing with the flow rate) should be attainable. You must determine the pump manufacturer, the model, the suction and the discharge sizes and the horsepower and speed (rpm) that will maximize the efficiency of the water cycle.

The Considerations

It is essential, first of all, to specify the correct type of equipment. Without the correct equipment, maintenance is impossible. If all the equipment is correct for the water feature, equipment maintenance will be minimized. Other factors involved in water maintenance include water stagnation, algae growth and garbage from the outside the water environment.

There are essentially two ways to clean the water in a water feature: drain clean and replace the water or aerate and add chemicals. In a water feature more than 100 square feet, clean draining is usually not the most efficient means to clean the water. It may be necessary in the actual pool cleaning to consider the cost of the water and the length of down time when deciding whether or not to go with a filter system.

Aeration

Aeration may be achieved either through natural means, if there is enough natural agitation in the body of water, or through mechanical means. Flowing water generally provides enough aeration to keep the water supply clean. Falling debris from outside the water environment are usually caught up in the filter system. Mechanical aeration is very effective in still bodies of water. Floating aerators or water jets are the most effective means.

Chemicals

Aeration is a very effective way to maintain water quality, but in most cases, it is not efficient enough to be the only maintenance tool. In addition to aeration, chemicals such as copper sulfate, herbicides and algaecides can be mixed into the water to control algae. However, some of these products can harm or kill turfgrass or other planting material that run through the irrigation system. In the past few years chemicals have been developed that will, reportedly, control the growth of algae and prevent algae slime, and not adversely affect most common fresh water fish or burn planting materials. (Special thanks to Dick Chaix of CMS Consultants, Doug Aurand, author of Fountains and Pools, Charlie Garridy and Jon Mitovich of Roman Fountains, Kerry Freidman of HydroDramatics and Harry Beckwith of Lake Consultants and Construction for their contributions to this series on specifying water features.)