September-October 2008

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Walking the Tightrope

Zoo officials face a serious balancing act: How do you conserve water without endangering the animals that rely so much upon it?

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Photo: The Oregon Zoo

By Dan Rafter

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The new facility, designed to serve more than 500,000 visitors every year, boasts composting toilets and greywater irrigation systems. The Eco-Restroom is not connected to the New York City sewer system. Instead, the facility collects toilet waste in a compost system, while water from sinks and drinking fountains—known as greywater—are used to irrigate plants outside the structure. This not only conserves water, it eases the burden on New York City’s already-overworked sewage infrastructure.

Photo: El Paso Zoo

The El Paso Zoo has earned a grant to upgrade its water filtration and treatment systems, in order to reuse more water.

The facility’s Clivus Multrum Compost Toilet Systems feature 14 foam-flush toilet fixtures, four waterless urinals, and 10 composters. The Clivus Multrum Greywater Irrigation System collects water from the restrooms’ other fixtures into a small tank in its basement. It then sends the water into a nearby flower garden. The foam-flush toilets use just 3 ounces of water, saving an enormous amount of water when compared to traditional systems. The composting feature is unique. In the composter, natural biological decomposition separates solid and liquid wastes and then transforms these into solid compost that resembles topsoil. Zoo officials estimate that the system can save more than 1 million gallons of water every year when compared to traditional low-flow toilets.

More water conservation methods can be found at The Lion House, a 20,000-square foot French Beaux Arts-style structure, designated a historic district by the New York City Landmarks Commission in 2000. Over the last six years, the building has been re-imagined and remodeled in order to lower the Zoo’s “carbon footprint” and reduce water consumption. The building recently became New York City’s first Leadership in Energy and Environmental Design (LEED)-certified Gold-landmarked building.

In order to meet LEED certification requirements, entire portions of the building were modified, including an expanded crawlspace to allow for additional plumping, heating, and electrical needs. Although water conservation was not an integral part of the LEED certification process, several changes made to the Lion House were designed to help the zoo reduce water consumption. For example, the new space created underneath the building accommodates a new geothermal system that includes five deep wells with running water (at a consistent 55˚F) that can cool the building year-round.

Additional water conservation efforts incorporated into the Lion House include waterless urinals and low fixtures. The sinks and the toilets also use reclaimed water supplied by a graywater system that saves the zoo approximately 150,000 gallons per year. Finally, a water-filtration system adjacent to the Sea Lion pool has reduced the need for regular dumping and filling of the seal’s pool, thereby saving an additional 160,000 gallons per week. Ultimately, the combined water conservation efforts have reduced the zoo’s consumption of water by over 50%.

Reusing Water in El Paso
The El Paso Zoo has worked with its local water utility to discover ways in which to recycle and reuse the facility’s water. Today, the zoo uses this recycled water for a number of non-drinking uses, including irrigation and cleaning its outdoor exhibits.

The zoo has also earned a grant to upgrade its water filtration and treatment systems, so that it can reuse even more water. Zoo officials also rely on ozone treatments to clean facility water so that the same water can be used more often.

“It’s a matter of looking at our animals and how they use water, and then trying to figure out how we can get them that water in the most efficient and least-wasteful way possible,” says Scott Gilliland, operations manager with the El Paso Zoo.

The way zoos use water greatly impacts the way they can conserve it. Water used as a barrier between facility guests and animals, for example, can be treated, filtered, and recirculated without worry about how it would have an impact on animals.

But zoos also water to duplicate animal habitats. For instance, South American tapirs use the water in their exhibit at the El Paso Zoo as a bathroom. That way must be treated in a different way than water used mainly as an aesthetic feature or barrier.

“Zoos use water in so many different ways,” says Gilliland. “Some zoos may be very dry; they don’t rely as much on water. A lot is based on their location and what type of animal collection they have put together. All those elements figure into water usage and how much water a zoo uses on a daily or yearly basis.”

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The El Paso Zoo features a large sea lion exhibit, one that’s extremely popular among Southwest visitors not used to seeing a lot of marine animals. This exhibit boasts a sophisticated filtration and treatment system that allows zoo officials to treat the water and use it over again. The exhibit includes ozone treatments, sand filters, and ultraviolet sterilizers.

“We do have to occasionally change out the water,” adds Gilliland. “But with the treatment systems we have in place, we reduce the amount of changeover as much as we can.”

Author's Bio: Dan Rafter is a technical writer in IL.

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