A DESERT FLOWERS
THE MIRACULOUS RECLAMATION AND REHABILITATION OF THE WADI HANIFAH RIVER VALLEY IN SAUDI ARABIA IS EXPLAINED.
PROJECT Wadi Hanifah Restoration Project, Riyadh, Kingdom of Saudi Arabia
LANDSCAPE ARCHITECTS Moriyama & Teshima Planners in joint venture with Buro Happold
TEXT Elsa Lam
PHOTOS Arriyadh Development Authority, George Stockton
Inside the intimate lobby of Moriyama & Teshima's offices on the edge of the upscale Rosedale neighbourhood in downtown Toronto, visitors cross a stone bridge over a shallow pool that contains a dozen swishing koi fish. The sound of trickling water carries down the hall to a boardroom adorned with a horizontal tapestry that resembles abstract waves from a flowing stream.
The decor is fitting for an office that's starting to see the fruits of a decade spent on a project centred on water. In November of 2010, Moriyama & Teshima Planners (MTP)--the landscape design branch of the firm--garnered a well-deserved Aga Khan Award for Architecture for their restoration of the Wadi Hanifah, a river valley in Saudi Arabia. The prestigious prize recognizes ecological and restoration-minded work in the Islamic world. With a site 120 kilometres long, and additional work extending through a 4,032-square-kilometre catchment basin, it's the largest project that MTP has taken on since its inception as an affiliate to the architecture firm 30 years ago.
The once lush Wadi Hanifah--literally the Hanifah Valley--runs from sand dune-covered desert, through agricultural lands and palm groves, before crossing the Saudi Kingdom's largest metropolis, the city of Riyadh. Some of the city's senior citizens remember playing in the Wadi Hanifah as children. That was back when Riyadh was a relatively small town--in 1952, it had 80,000 residents. Since that time, it's developed in leaps and bounds, more than doubling its population every decade. Today, 7 million people call Riyadh home.
As the city expanded, it used the Hanifah Valley as a throughway for utility lines and a dumping ground for construction waste. The river that carved out the valley had centuries ago been diverted into an underground aquifer, remaining easily tapped for fresh water. Now, a new kind of waterway has made its way through the Wadi Hanifah--a foul stream of industrial effluent from a tannery on the outskirts of town, and discharge from the city's overcapacity sewage treatment plant. "It had become Riyadh's sewer and dump," summarizes MTP president George Stockton.
Stockton is no stranger to the region. MTP worked hand in hand with Moriyama & Teshima Architects on the National Museum of Saudi Arabia, developing the urban design and landscaping for the 83-acre site in Riyadh, which opened in 1999. That year, Stockton was asked to participate in a three-week charrette on the future of the city. He focused on open space and the environment. "I identified the Wadi as the opportunity," he recalls. His paper on the subject became the terms of reference for the project, headed by the Arriyadh Development Authority (ADA). In partnership with UK engineering firm Buro Happold, MTP won a proposal to redevelop the Wadi Hanifah. At MTP, Stockton and landscape architect Drew Wensley headed up the project. Soon after the master plan was completed, the team was commissioned to develop detailed designs, and on the heels of that phase, the first pilot projects.
The central idea in Stockton and Wensley's vision was to use native plants and natural processes to restore the riverbed. They proposed regreening the valley with indigenous flora that would mitigate the area's violent flash floods while doubling as the basis for naturalized parks. Then, they envisaged cleaning the urban wastewater stream to a level where it could provide public amenity within those parks.
Before construction could begin, the riverbed needed to be cleared: a step where working in a nation with top-down governance proved a precious asset. The tannery that poured hazardous chromium down the Wadi was shut down in two days. Utilities including water mains, sewage spur lines, overhead phone wires, power cables, and irrigation pipes were relocated. 1.5 million cubic metres of debris--a volume equal to the Toronto SkyDome (now the Rogers Centre)--was removed from the riverbed, comprised of everything from construction waste to dead animals.
Once the area was cleared, the team built stone walls along the edges of the Wadi to set it off from private property, and began revegetating the ancient riverbed with the indigenous species that had once inhabited it. The ADA and its contractors collected seeds and cuttings from the least damaged parts of the valley, and used them to propagate thousands of trees, shrubs, and grasses in greenhouses. "All of these plants have incredible strategies for survival in hot, low-water conditions," explains Stockton. Moreover, the selected species would help temper the Wadi's periodic floods, which have worsened with the asphalt sprawl of urban development. "The shrubs and plant material that are genetically intrinsic to the Wadi would have slowed down flood flows historically," reasons Wensley, noting that over millennia, these plants adapted to absorb rapidly moving floodwaters and retain sediments.
The use of native flora was not without controversy, since the locals viewed them as weeds. Although the plan to employ indigenous species was laid out early on, the ADA remained concerned about whether the public would use a naturalized system, as opposed to a series of formal parks. Yet Stockton and Wensley resisted the pressure to bring in imported plants, which would have required constant care and irrigation. To justify their decision, they tapped their landscape design skills to showcase the beauty they readily perceived in native grasses, by massing them together and highlighting them in composed groups. "It became like a garden," says Wensley.
The team arranged the new plants in thousands of clusters called planting cells, designed in over 150 different shapes and species groupings, according to both aesthetic criteria and the varying conditions along the Wadi Hanifah. Interspersed along a 70-kilometre stretch of the Wadi, the cells acted as miniature plant nurseries, and within three years had begun to grow out to meet each other, as well as spreading seeds downstream. Now, a textured green carpet is starting to cover the valley floor. The restored habitat attracts huge numbers of birds, along with small mammals and some reptiles--like the foot-and-a-half-long lizard that greeted Stockton on a recent visit.
A new road running the length of the Wadi allows for easy access to park areas designed by the team. In some sections, simple limestone walls delineate picnic areas and provide families with visual privacy. Other areas are left open as play fields for children. A recreational path used for jogging and walking runs along the edge of the riverbed. Along select sections, palm-lined promenades add to the oasis-like feel of the valley.
Meanwhile, in the urban core of Riyadh, the team sought to transform the discharge from the municipal sewage treatment plant--technically greywater, but which often approached blackwater--into something beautiful. This strategy had two phases. The first was to divert part of the plant's effluent through a man-made channel, lined with loose rock and equipped with waterfalls that help to introduce oxygen and mix the water column. The size of the rocks was calibrated to maximize the quantities of aquatic organisms that could live in the channel bed and digest organic material from the wastewater.
The channel leads to the main bio-remediation facility: a large-scale open-air living machine that, from the air, looks like a family of three fossil trilobites. Water enters from the top of the facility--the tail end of the baby trilobite--and makes its way through herringbone channels, or bio-cells, in each of the three successive systems.
A series of operations progressively cleans the water. At the mouth of the facility, powerful air pumps blast dissolved oxygen into the water, creating an environment lethal to coliform bacteria. Each bio-cell's front compartment houses a 3-D layered textile mat--a vast, cave-like maze on which colonies of algae and other micro-fauna thrive, digesting nutrients from the water. Finally, tilapia feast on the algae. Recent autopsies have shown the fish to be in perfect health, with no toxins or parasites. By the time the water exits, it's clear through to the bottom--making the fish easy to spot for opportunistic herons, egrets and hawks that have begun to nest in the area.
The success of the facility has been astounding. As Stockton describes, "it came alive in just a few months rather than a whole year, which is what we were anticipating." The water that emerges doesn't smell, and is close to 100 percent clear of coliform and suspended solids. Although it's not drinking calibre, further treatment could render it so. The remediated wastewater--350,000 cubic metres of it each day--is especially precious in a city that normally relies on desalinated seawater, a costly and energy-intensive source. Aside from four air blowers, the Wadi facility uses no machinery, and its capital cost was a third of a conventional wastewater treatment plant.
Instead of being immediately extracted as recycled greywater for the city, the remediated water is allowed to flow for another 28 kilometres, becoming the lifeblood of a new series of urban parks. In one area, the water snakes over the rock outcroppings from a 500-year-old stone dam. Cut-stone steps ending in a gravel beach reach out into the water. Downstream, the water pools into a string of artificial lakes, stocked for fishing with surplus tilapia from the bio-remediation facility. "It's a very unique experience to have open bodies of water within the desert environment," affirms Wensley. Riyadh's public agrees--they began picnicking in the Wadi while it was under construction, and now patronize the parks by the tens of thousands each weekend.
While the Wadi Hanifah has shown remarkable progress, for MTP, this is just the beginning. Remediation of additional effluent from the municipal plant continues, and another series of parks is under construction, connecting side valleys into the main Wadi system. They're also working on establishing a Wadi Hanifah Directorate that would ensure the ongoing protection, management and enhancement of the river valley. An educational centre and program are another critical component. "This project will probably still be under construction in a hundred years, there's just so much to do," opines Stockton. "It's got enough scope to evolve, and respond to new needs, and that's the hallmark of a very good project."
Meanwhile, the firm is at work on master plans for Mecca and Medina--Saudi cities that also have sick watersheds--and their approach is garnering international interest. Wensley has been asked to present the Wadi Hanifah twice at the United Nations, and the firm is excited about applying the process and lessons they've learned to situations elsewhere. The bio-remediation facility in particular--built with basic materials and unskilled labour--holds enormous potential as an adaptable tool for tackling the globally ubiquitous problem of urban wastewater.
At its core, the success of the project and its future potential is a quintessentially Canadian story, built on strong experience with diverse natural environments and cultures at home, and a long-term, consensus-building approach. "Canadian consultants can go to challenging areas around the world, and with the right attitudes and eyes wide open, do superb work," concludes Stockton. "Better than almost anybody else." CA
Elsa Lam is a freelance writer and scholar. She studied architecture at the University of Waterloo and McGill, and is completing a PhD in architecture and landscape history at Columbia University.
CLIENT Arriyadh Development Authority