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American Society of Landscape Architects


May 2008 Issue

To the Dogs
In Arizona, a highway retention basin is transformed into a multiuse park that celebrates the playfulness of dogs.

By Rachel Hill, Student ASLA

To the Dogs

Highways don’t often give birth to parks, but in the Phoenix suburb of Gilbert, one did. The Arizona Department of Transportation’s plan for a highway through Gilbert included retention basins to handle stormwater from the new road. At the town’s initiative, a series of three of these stormwater basins now double as parks: Zanjero Park, Discovery Park, and the easternmost of these, Cosmo Dog Park.

Although only 16 acres in size (of which about two and a half are dedicated to dogs), Cosmo Dog Park has amenities not found even in other dog parks—ramadas, an amphitheater, a stage, a hydrant-shaped water fountain, and a dog-play lake. Dog owners from around the region visit the park, making it so crowded on weekends that the parking is often full and the park must occasionally close down for turf repair. rated it 2007’s “Number One Dog Park in America.”

Cosmo Dog Park, Discovery Park, and Zanjero Park will be connected by a trail system that is currently in development. Each park retains an individual identity as each has a particular focus—Zanjero has an equestrian focus and Discovery contains traditional park amenities such as ball fields. Cosmo’s focus on dogs is a relatively new use of recreation space compared to traditional baseball fields and basketball courts.

Water for recreation or aesthetics is rare and valuable in the desert. The dog lake in the center of the park is often packed with people and dogs. It appeals not only to a variety of dog owners coming from all over the metro area but also to a variety of dogs and was designed with dogs in mind. Park user Al Rausch usually takes Coco to a dog park closer to his home in Mesa, another Phoenix suburb, but the variety of enclosed spaces at Cosmo allows Coco to play uninhibited. Two and a half acres of turf are divided into two fenced dog run areas that allow for a variety of dog psychologies—one more placid and docile, the other more dynamic. Agility equipment such as a window to jump through is used for training by the police canine unit.

Cosmo Dog Park may be a “stepping-stone” to a more extensive park system throughout the Phoenix metro area. Although public parks are dotted throughout the metro area, green connections are lacking. Few corridors support a citywide green infrastructure. The “Valley Forward” organization has planned the “Valley’s Pedestrian Freeway—a Priceless Necklace of Trails and Gems” that proposes trail links throughout Phoenix and its suburbs, but that is still just a proposal. As Phoenix grows into the small towns that form a ring around it, the issue topples onto them. How does the development support open, green spaces? The suburb of Gilbert saw its opportunity to create open space by organizing the elements in its landscape. Cosmo Park is one piece.

As the bones for the highway were being laid, the town of Gilbert saw the potential to use the drainage basins in a multifunctional way. Tami Ryall, assistant town manager of Gilbert, says the town approached the Arizona Department of Transportation (ADOT) with the idea of making the proposed basins into parks.

ADOT supported the town’s idea. As it happened, J2 Engineering and Environmental Design had already been working with ADOT on the engineering of other retention basins in the area. The firm, based in Phoenix, blends a strength in water resources with a focus on public projects, parks, and environmental restoration. Its landscape architecture team, led by Aaron Allan, ASLA, took on the design of Cosmo Park.

ADOT’s original plans for the Cosmo Park site had involved excavating a basin 20 feet below grade. Its only purpose was to retain the overflow during major storms. During minor storms, stormwater would travel in the channel past the park, but in major storms, water would pass over the spillway and into the basin. A pump station across the road would then pump the water out of the basin and back into the channel to continue on its way. This is the original reason that Cosmo Park came into being.

The original engineering for the retention basin changed little as the park idea developed alongside. The stormwater function remains practically the same, except that the basins are now permanently full and are used as a source for irrigation and, of course, for the dogs. Most of the water for the basins is supplied from a perched aquifer. A soil treatment bonded and sealed the basins, and they have a concrete lining to a depth of approximately five feet from the surface to endure the traffic and erosion that occur with the water fluctuations as irrigation water is drained and refilled. They are impermeable.

The landscape architects capitalized on the expensive earthmoving conducted by ADOT. As the ADOT bulldozers extracted one and a half million cubic yards of dirt, Gilbert only spent $1.5 million on Cosmo Park. The Maricopa Association of Governments partnered with ADOT on the acquisition of property and the construction of the weir.

The entrance to the park from the parking lot brings visitors past a children’s playground and ramada, which are, as one would expect, designed with a dog theme. On each “toe” of a large paw print in the playground sits an individual piece of playground equipment. The picnic ramada is placed in the “heel” of the paw. (These nuances may only be noticed in plan.) The decision was made to use “off-the-shelf” equipment arranged into the dog theme rather than create custom pieces and spend the money saved on integrating the playground into the rest of the park. Regardless, the playground is well used by neighborhood children. By contrast, the dog play equipment, including a window jump, pyramid, catwalk, tunnel, and water dock, were custom designed by the Gilbert K-9 police unit. J2 was charged with detailing and creating each piece. The dog dock and tunnel were designed from scratch. The pieces are made from concrete block and concrete, which simulate real environments for the training dogs and stand up to repeated use at the park.

The sense of enclosure gained as you descend into the park, especially as the vegetation is young and the canopy is not mature overhead, makes it inviting in the typical vastness of sprawling suburbia. Yet like much of the “newness” spreading out of Phoenix, it feels incongruous with its surroundings—the Sonoran Desert.

Very few parks in suburban Phoenix look “grown up,” and Cosmo Dog Park is no exception. Cosmo has a lot of turf, which is tough to maintain with the beating it gets from running dogs, but, even without dogs, turf requires much upkeep and water in the Sonoran Desert. Unfortunately, some people living in the region take turf for granted. Many come from other regions of the country where grass is assumed to be the ground cover of choice for parks. Others may say that turf is needed to keep down the dust churned up by running dogs or that cacti would be dangerous to people or animals.

The pond plants were chosen to deal with the confinements of underwater planters, as the basins are impermeable. The ponds were not designed to be urban fishing lakes, but people are fishing there. The water is recycled through the irrigation system regularly and thus relatively clean, but how the fish got there, nobody knows. The basins are not stocked or maintained for fish, and the water must cook under the summer sun.

Cosmo is a distinctive park fit into a small space that would normally be considered undesirable. Design mitigations for stormwater that are normally seen as a nuisance have created a loved place. The park’s use of groundwater is also judicious, a necessary consideration in the desert. The opportunity to expose stormwater, however, seems one of the few lost opportunities in Cosmo Park. Stormwater bypasses the park in most situations, allowing it only rarely to cascade down the high steps of the amphitheater and into the basin. Phoenix is a city where many inhabitants have lost the intimate connection to their environment. Air-conditioning assuages the desert heat, while irrigation makes it possible to live in a lush—but unrealistic—environment. The reality is a harsh but beautiful desert ecosystem that has a distinct process and set cycles. Rain events come in bursts during the summer “monsoons,” bringing high winds and quick and thorough dousings of water. They are invigorating, cooling down the air for a short time and turning the desert green. However, when stormwater is channeled and masked, the opportunity to educate on water, weather, and the environment is lost.

In contrast, Portland, Oregon, is one city that has made exposing water runoff chic and interpretive. Koch Landscape Architecture designed the 10th @ Hoyt Apartments with water features that activate during storm events, mitigating stormwater on site (see “Art for Rain’s Sake,” Landscape Architecture, September 2006). This expression of nature pulls people from their apartments with umbrellas, lasts for up to 30 hours after a storm, and educates the public about their environment, tying them closer to the place where they live. In contrast, Cosmo Park pulls water out of the aquifer and keeps stormwater from ever inundating the park.

Cosmo Park is only two years old, thus its success and limitations in the future are still hard to predict. The constant lack of parking spaces is an indicator of its popularity. As development continues and the park’s popularity rises, it will surely have new maintenance issues, and the expansion of the dog park may have to be considered.

Rachel Hill, Student ASLA, is a graduate student at the University of Arizona focusing her studies on landscape planning and arid lands.


Landscape architecture/civil engineering/hydraulic– hydrologic engineering: J2 Engineering and Environmental Design, Phoenix.
Civil engineering: Aztec Engineering, Phoenix.
Lake/pump system/well design: Aqua Engineering, Fort Collins, Colorado.
Electrical engineering: Wright Engineering, Chandler, Arizona.
Irrigation design: Corral Dybas, Phoenix.
Geotechnical engineering: RAMM Engineering, Tempe, Arizona.
estroom/mechanical enclosure architecture: HDA Architects, Gilbert, Arizona.
Park contractor: Valley Rain Construction, Tempe, Arizona.
Owner: Town of Gilbert, Arizona.
Partners: Arizona Department of Transportation, Maricopa Association of Governments.

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