Tim and Karen Hixon Visitor Center
Cool Water: A visitor center doubles as an aquifer, collecting and conserving water in a region suffering from drought.
After driving a mile or so from the Government Canyon State Natural Area’s entrance, which is itself about 25 miles northwest of downtown San Antonio in the suburb of Helotes, I reached its new visitor center. Along the way, I passed mesquite and oak trees, Mexican buckeye, and lots of wispy Lindheimer’s silk tassel along the way. At one point, a suburban residential subdivision came into view just outside the park, its conventional, semi-Colonial homes standing in stark contrast to my mental image of how a natural area in Texas should appear.
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But then Government Canyon is on the front lines of the environmental movement. Its Tim and Karen Hixon Visitor Center straddles the Balcones Escarpment, the topographical line that separates everyday land from that overlying the Edwards Aquifer the lifeblood of this arid region’s economic vitality. The real purpose of the 8,000-acre Government Canyon is not to provide land for mountain biking or day hikes, but to conserve a watershed ecosystem that allows those subdivisions across the street to exist. The design for the visitor center largely arose from this ecological condition.
“The way the visitor center works is analogous to the way the aquifer works,” says Robert Harris, AIA, the project architect with San Antonio-based Lake|Flato Architects. “The differently shaped roofs of the three buildings act as catchment basins. They collect the water, take it through gutters, down rain chains, and into open spouts leading to underground concrete cisterns the water disappears into the land.” Lake|Flato designed the 4,224-square-foot project for the Texas Parks and Wildlife Department, as both an office for park officials as well as a place for classrooms and a meeting space, where issues of water conservation could be promoted to the community. The program is divided among three buildings the office/gift shop, classrooms, and a screened-in pavilion on two acres, all tied together by the extensive rainwater collection system distinguished by a water tower with two corrugated metal tanks.
On a rainy day, it’s hard not to view the facility as a series of filters: from the cisterns that receive rainwater to the pervious paved parking lot where visitors leave their cars to the natural recharge of the fragile watershed beyond the threshold of the buildings. Along the Balcones Escarpment, where low limestone walls extend to reinforce the “edge” condition of the recharge zone, the buildings fan out as if with wings. Harris says the line of this wall, which stretches to the northeast and the southwest, was shifted in plan to provide a clearing like a joint in the middle, or what he calls “the crux,” for the entrance and main pavilion. This architectural device works to frame the view to the north the sensitive aquifer recharge zone as hallowed ground, with sidewalks leading off to the east and west to connect to hiking paths. Has another building ever so carefully deferred, in both section and plan, to the needs of a natural water system?
Many of the buildings’ structural members were originally intended for a liquid of another type oil as the rusted steel pipes framing the main pavilion and the center’s porches were sourced from the region’s oil-pumping facilities, as well as cattle-fence suppliers. Lake|Flato made similar structural moves at its World Birding Center, completed in 2004 in Mission, Texas. As at that project, the architects worked with the structural engineer Chuck Naeve, PE, from Austin-based Architectural Engineers Collaborative. Naeve likes the unadorned simplicity of the steel pipe, which was specified with a 75-percent recycled content requirement. “From an engineering standpoint, an honest detail or connection is one that visually describes the flow of force through the connection, so that whether you are a structural engineer or not, you have this intuitive knowledge of how things fit together and take load,” he explains. Government Canyon’s exposed connections and framing, particularly in the central pavilion, express this approach to engineering most explicitly.
The project’s tight budget was stretched by some key decisions: making the exhibition pavilion naturally ventilated, which shaved 35 percent off the center’s mechanical system demands, and moving all circulation space to the exterior. The two conventionally enclosed buildings each have standard split systems for heating and cooling, with the compressor outside, the fan inside. The project was also oriented along an east-west axis, allowing effective use of daylighting. A comprehensive lighting control system with photocells, occupancy sensors, and a solar photovoltaic power source for the water tower’s pumping system further reduce energy use. The material palette was also minimal, with locally sourced eastern red-cedar siding and flooring, fly-ash concrete floors for interiors, local limestone finishes for some walls, and a corrugated-metal roofing system.
Budget and design issues delayed completion of Government Canyon, a common occurrence among public projects involving multiple stakeholders. Also, plans for the structure and water systems weren’t straightforward, at least for Tom Page, the project’s San Antonio-based contractor. “It’s judicious of me not to discuss this,” says Page, echoing the complaint of many contractors who decry field changes on projects with little financial wiggle room. The water tower’s pumps weren’t functional when Page left the job site, but they are now. Differences aside, the project team notes the buildings’ ambitions were mostly fulfilled. Government Canyon won a 2007 Top Ten Green Project award from the American Institute of Architects’ Committee on the Environment.
What set this project apart from many of the other winners was its poetic approach to water issues, an approach that characterizes a number of Lake|Flato’s projects. The firm is among many in the west that are particularly sensitive to the dry conditions that seem to be getting worse. Unlike other, even drier parts of Texas, the San Antonio area receives nearly 32 inches a year of rainfall, which at the Hixon center collects in the cisterns before being pumped to the tower to take advantage of gravity-induced pressure. For extremely wet periods, each cistern is designed to allow water to overflow like a natural spring. Otherwise, this water is filtered and then used for some minimal irrigation and for nonpotable purposes, such as flushing toilets. Wastewater goes into a traditional septic system; Harris says the state rejected the use of a proposed constructed wetland. Lake|Flato estimates the rainwater system offsets between 92,000 and 137,000 gallons of potable water use a year.
While the building does its share of collecting water, it also allows water to flow underneath the complex’s central pavilion, which is raised on its steel-pipe structure 18 inches above grade (visitors enter the center on a wooden-plank sidewalk). The ground under the other two slab-on-grade buildings was raised 18 inches as well in order to minimize the potential for flooding. William McDonald, a landscape architect with the Texas Parks and Wildlife Department, coordinated his design for native plantings around the berms that were created to facilitate run-off throughout the site. McDonald rooted the new landscape in existing field surveys from 1992 and 1997, incorporating some native plants like bluestem and buffalo grasses, as well as cheerful and ubiquitous black-eyed Susans to attract butterflies and hummingbirds. “We try to use native plants and to clear the exotic ones, but the area was already fairly pristine,” McDonald says. “There’s more of an interpretative component to the landscape, if anything, to help homeowners understand how to landscape and irrigate efficiently.” A drip irrigation system was installed to get the plants started, but the need for it will decrease as the plants mature.
In planning the site, Lake|Flato’s design team worked from a survey provided by the Texas Parks and Wildlife Department. Little is understood about how surrounding development has affected the watershed for the Edwards Aquifer. In Texas, Harris says, you have the “right of capture,” in that water that falls on your site belongs to you. “Capturing water helps slow the flow and limits erosion downstream, which can swell streams and cause floods,” he says, noting that you don’t want to rob the system of too much water since it could deplete the aquifer over time. Government Canyon is proof that architecture can embody this lesson as well as any anything.
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