Designing Sustainably for Elephants

September 10, 2014

How do you design a zoo to be sustainable? What does "sustainable" mean in this context? Our team began design work on the Oregon Zoo's new elephant habitat after completing a comprehensive 20 year Master Plan. 'Elephant Lands' is the largest project in the first phase of that Master Plan, and a significant piece of both the proposed campus energy loop and the campus stormwater management facilities. Because of the already-funded $125 million bond project scope, there was an amazing opportunity to conceive of district-scale efficiencies that could be realized within the next decade. Metro's impressive Sustainability Plan goals guided water and energy savings targets, and the zoo committed to LEED Silver or better on all habitat improvements. We also tracked sustainability as an item critical to the mission of the zoo, including less typical project metrics like animal welfare, choices for animals, and conservation education.

Elephant Lands is four times the size of the old habitat, growing from 1.5 acres to 6 acres, all new construction. The habitats are diverse in topography and environmental characteristics, meadows of rolling grassy knolls, sandy areas to dig and roll, a ravine area with a deep plunge pool, mud wallows, and a meandering area with a wading pool and large trees to push and climb. The new building consists of two major areas: the Elephant Building is a holding facility and welfare center for the elephants, as well as a back-of-house keeper and animal management space.

© Oregon Zoo

Forest Hall is a large open area that allows the maternal herd to circulate freely between indoors and outdoors. The design follows a strong zoo commitment to give the elephants choice in how they spend their day.

A small part of the new habitat has been open since early this year, as we transition their habitats to allow for new construction to take place. I've been going out to the Oregon Zoo at least once a week for the last 4 years, and it is already amazing to see the variation in activity and behavior of the elephants in their new area. They run, climb on the trees and sand mounds, roll around, tease each other, play in the water misters and search for food in the randomly timed feeders. Elephants are also the ultimate quality control check - since they are both incredibly strong and remarkably dexterous, we know right away if there is an area that needs a little more attention.

Ever thought about how to build an insulated, elephant-proof wall? We landed on a 20" thick design, sandwiching rigid insulation between cast-in-place reinforced concrete on both sides. The need for free movement of animals between an energy-efficient indoor environment and the outdoor habitats lead to defining a large acceptable temperature range in Forest Hall, combined with an air curtain that blows over the elephant door during certain temperatures.

© Oregon Zoo

A geothermal slinky well field below the North Habitat kicks off the creation of the campus energy loop, and will be balanced in a few years by the opposing loads of the new Polar Bear exhibit. Because it is a horizontal installation right below the elephant's feet, there were concerns about elephants digging, exposing and damaging the wells. Though the area has some challenging contours and soil conditions, we were able to design in a top layer of sand over four feet deep (the depth an elephant can dig in one day) with intermediate drainage pipes to relieve hydrostatic buildup in the sand layers. The sand is not only an ideal material for the elephants' sensitive feet, the increased total soil depth improves the performance of the geothermal system, a win all around!

The two elephant pools are supported by a fantastic underground network of basins, pipes, pumps and filters required for maintaining sanitary conditions for the elephants. The designed system conserves about 70% of the potable water a traditional "dump-and fill" design would use.

Because the zoo wants to eventually disconnect from the city combined storm/sewer system, considerable thought went into stormwater conveyance and detention. A new 70,000 gallon basin beneath the South Habitat can handle runoff volume from the majority of the zoo - imagine 4 school buses lined up and filled with water. A master plan bioswale and surface treatment concept will add dimension, beauty, seating and greenery all along the main "Zoo Street" that runs through campus and around the concert lawn by the elephant's South Habitat. The design creates a strong visual and tangible connection to the site's topography and to one of Oregon's most abundant resources, rain.

To all involved, from the senior designers, project managers and superintendents, this is one of the most unique and complex jobs we've ever seen. But that is also what makes it one of the best. Together we manage the creation of a world-class project in the midst of challenging environmental zones, geologic slide areas, saturated soils, powerful and sensitive animals, and creative construction techniques. All the while ensuring the visitor experience is not compromised at Oregon's top attraction, still open 364 days a year. We get to share the satisfaction of solving intricate and unusual problems every day with an extremely talented group of people for some of the most inspiring occupants we will ever work with.