Landscape Architect Articles

LASN Focus Feature July 200407-01-04 | News

Water Feature Safety

Proactive Designs Anticipate and Minimize the Risk of Injury

By Amy L. Johnson, P.E, Aqua Engineering, Inc. and Jodie Carter, LASN regional editor

Interactive features require detailed mechanical system design including safety components and water treatment. High water quality is maintained in this interactive spray feature in Henderson, NV, which includes two separate pump systems, filter systems and water quality treatment systems. One system maintains water quality in the ?EUR??,,????'??ground spray?EUR??,,????'?? area and another maintains the ?EUR??,,????'??toy?EUR??,,????'?? area. Pour-in-place rubberized safety surfacing minimizes slip and fall injuries. Interactive water sprinklers must be regulated at low pressures for human safety, including eliminating potential eye injury.

Remember those sultry summers you spent as a kid running barefoot through hardscaped sprinklers or jumping in the oversized fountain at the neighborhood park. It?EUR??,,????'???s a fact, whether you?EUR??,,????'???re six or 60, people have always been drawn to water features and it?EUR??,,????'???s not long before most of us want to touch the water or?EUR??,,????'??+if it?EUR??,,????'???s hot enough?EUR??,,????'??+jump right in.

This interaction between people and/or pets and the water feature affects the quality of water needed in the system and will determine the type of water treatment and filtration required.

Dangerous Surfaces

Finished surface areas that will be exposed to the water and accessible to people should be non-slip. These areas may be the main water feature itself in the example of an interactive surface. For interactive fountains, non-slip and flexible (rubberized) surface designs are both important. Fountains that may spray water onto walking areas should be reviewed carefully to determine if precautions should be included in the design of the hardscape around the water areas. Open areas such as grates or nozzle orifices may pose a hazard for ?EUR??,,????'??stubbing toes?EUR??,,????'?? or tripping. For these areas, careful consideration of the size and location of the opening will help determine the acceptable design criteria. For interactive fountains, as an example, a high velocity nozzle can be dangerous when a child looks directly at the nozzle and is surprised when it turns on. Other safety concerns exist and are dependent upon the nature of the water feature.

Water Treatment

The quality of the water is important not only for appearances, but also for safety. Human and animal interactions introduce debris and new chemistry parameters to the water. Typically, a high rate sand filter or cartridge filter is included in any water feature mechanical system to help catch debris prior to entering the pump system and recirculating to the fountain.

The pond grading detail shows the following critical design considerations. A maximum water depth of 18 inches at the lake edge is designated in case a pedestrian accidently steps into the pond. If a pedestrian does stumble into the pond, a 4:1 ?EUR??,,????'??safety ledge?EUR??,,????'?? gradually slopes to the bottom of the pond, instead of presenting a harsh drop-off that would increase the hazard of drowning. Also shown: anchor trench for lining system, sidewalk curb at lake, and shotcrete surface for aesthetics with fluctuating lake level.

Interactive fountains should be treated similar to swimming pools?EUR??,,????'??+automatic monitoring and dosing of chemicals should be included in the mechanical system. The water basin, or wet well, should be continuously treated so clean water is always being pumped through the system for interaction. Local health codes may mandate the extent of the water quality treatment for these types of features.

If additional treatment is desired for non-interactive fountains, several other alternatives exist: ultraviolet lamps, ozone generators, and biological filters. The type of treatment chosen will depend on the expected type of debris (leaves and twigs versus algae and fish waste) and the desired overall water quality and appearance.

Water Depth

Water depth is a very serious safety consideration. Many fountains with permanent pools have depths of 16 to 18 inches and are considered ?EUR??,,????'??normal?EUR??,,????'??. Large natural ponds that may be deeper need to be designed with a side slope of 4:1 for at least 12 horizontal feet to provide a ?EUR??,,????'??safety ledge?EUR??,,????'?? and allow anyone in the pond to realize the slope is decreasing and the water depth is increasing. Many interactive features are ?EUR??,,????'??zero depth?EUR??,,????'?? pools. These fountains don?EUR??,,????'???t have a permanent pool. As the water contacts the surface, it immediately drains away from the play area and back into a buried or hidden holding chamber (wet well), which virtually eliminates drowning dangers.