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By Nancy B. Solomon, AIA

 

Case Study Heifer International Center, Little Rock, Arkansas. Estimated date of completion: 2005 A nonprofit organization, Heifer International facilitates donations of farm animals to poor families in undeveloped countries to foster self-reliance. Consistent with its global mission of sustainability, it is building an environmentally sensitive headquarters on a 30-acre urban site that includes remnants of an abandoned trucking company and a railroad switching yard. The property is near the Clinton Presidential Library site and the Arkansas River. The Heifer’s site (above) was once bisected by a railroad switching yard. Photography: © Rick Musticchi of Arkansas Aerial Photography   According to Gerald Cound, Heifer’s director of facilities, “This is a great location for us: near the river, the city, the library. Once we got into the site and understood its problems, we decided it would be part of the story we tell, so that we can encourage others to do the same elsewhere.” Heifer started its cleanup by removing underground diesel supply lines from the trucking area, in keeping with state regulations. Much of the excavated, diesel-contaminated soil, however, still sits on the site. They also began demolishing existing structures and crushing the concrete into gravel, to be reused on site as the base for a new parking lot.Heifer hired Ecologic, an environmental consulting firm in Little Rock, to undertake an initial assessment of the property. In the subsurface soils of the switching yard, which bisects the property, they found a residual amount of polycyclic aromatic hydrocarbons (PAHs)—probably from the deterioration of railroad ties, which had been removed by a previous owner. In the southwest corner, around the site of the trucking company, they found a layer of asphalt about 3 feet below the surface. Here, they also found an inconsistent mixture of low-level contaminants—probably due to unclean fill delivered to the site to level the area.   Anne Woker, president of Ecologic, recommended that Heifer conduct a more thorough site assessment and remediation plan only after design development was complete. “When you have the time, you should target the comprehensive site assessment to the planned use. Otherwise, you can waste a lot of money pin-cushioning the entire site,” she says. So the ball went into the architect’s court: Polk Stanley Yeary Architects of Little Rock developed the master plan. The old rail yard became a logical buffer between a more formal, industrialized headquarters to the southwest and exterior exhibits of underdeveloped nations, to be designed by Cambridge Seven Associates in Cambridge, Massachusetts, on the northeast. Straddling the two worlds will be a visitor center. The old rail yard will include constructed wetlands to filter storm-water runoff—thereby cleaning the site of future pollutants—and provide habitat for native flora and fauna. The architects phased construction so that the headquarters could be built on what is thought to be relatively clean ground while the truck and rail yard sites are remediated. The visitor center will be built after remediation is complete. Ecologic will now undertake a comprehensive site assessment, which Heifer will submit to the Arkansas Department of Environmental Quality (ADEQ). Following ADEQ’s approval, Ecologic will provide the department with a property development plan, which will present the compatibility of Heifer’s planned use of the site to its existing environmental conditions and will propose specific remedial actions if needed. Once ADEQ accepts this plan, remediation and construction may begin. In all likelihood, predicts Woker, some of the shallow soils will be excavated and tested to determine their final destination. The diesel-contaminated soil already excavated may be landfarmed on-site—in other words, aerated so that volatile hydrocarbons will be released—before being disposed of off-site. The layer of asphalt and miscellaneous, low-level contaminants in the old trucking area will probably remain in situ, safely capped below several feet of clean fill and a new parking surface. “It will be a risk-based assessment,” notes Woker. “This process supports development in a way that is crucial for revitalizing downtown areas.” N.B.S.