Michael McLaughlin

LATELY, there has been considerable interest in reclaiming real estate across the country formerly occupied by municipal landfills. Until recently, closed landfill sites were used primarily for passive recreation — if at all. Now, an increasing number of closed landfills have been reclaimed for a variety of industrial, commercial and residential uses, leaving landfill redevelopers with many challenges, including legal and technical issues. What follows is one example of how environmental engineers met the challenge of turning a burning landfill into a hot retail development.

In 2005, retail developer North American Properties hired SCS Engineers, an environmental engineering and construction firm, to perform several tasks at a closed 40-acre landfill in Acworth, Ga. The landfill was being redeveloped into a planned 330,000-square-foot shopping center named Lakeside MarketPlace, featuring a number of nationally prominent retail and dining brands. Consisting mostly of vegetative and construction and demolition debris, the landfill measured approximately 65 feet thick at the deepest point.

The team found this redevelopment project to be particularly challenging due to extreme conditions throughout the site. Approximately 40,000 cubic yards of the buried waste were smoldering, and other sections of the site revealed extensive areas of exposed waste debris and visible venting of smoke. The engineering firm was charged with controlling the subsurface fire and mitigating the effects of landfill gas at the site.

The plan needed to be cautiously executed because the work coincided with the construction of major buildings, installation of all underground utilities and traffic areas, dynamic deep compaction of much of the surface of the former dump and installation of steel piles to support the largest buildings.

The company implemented an overall site health and safety plan, monitoring landfill gas and the combustion aspects of construction activities for five months without any injuries. SCS Field Services, the firm's construction group, installed about 300,000 square feet of sub-floor landfill gas migration control systems for the buildings, including both active and passive venting systems that were covered with spray-applied membranes manufactured by Liquid Boot.

Additionally, fire probes were installed to delineate the extent of the subsurface fire and to monitor temperature, carbon monoxide, hydrogen sulfide and carbon dioxide. A method for controlling and extinguishing the fire also was designed. The subsurface fire was controlled using a combination of sealing sideslopes exposed to air and the injection of carbon dioxide to displace oxygen and cool the smoldering waste. Some 44,000 pounds of carbon dioxide were injected into the landfill.

A single contractor was used to investigate landfill gas conditions, design and install mitigation measures and monitor system performance. The developer did not want the engineer blaming the contractor, or the contractor blaming the engineer, if the methane mitigation systems failed to function properly.

The project also was aided by a creative public/private financing approach. Cobb County and the local school district established a Tax Allocation District (TAD) to be funded by future real estate taxes on the shopping center. As a result, the TAD provided nearly $6 million in financing for the remediation aspects of the project (e.g., methane mitigation, fire control and deep foundations).

The Georgia Environmental Protection Division (EPD) also played a key role in the project, accepting construction of the shopping center as an alternative cap under its permit rule. The consent agreement was itself a model of brevity, covering only a handful of pages.

Between February and July 2006, various stores, including Circuit City, Books-a-Million, Ross, Petco and Target, opened for business. Prior to its July opening, Target held its annual meeting of shareholders in May at the Lakeside MarketPlace store, the first time the corporation had ever held its annual meeting outside of its home city of Minneapolis. The company thought the new SuperTarget in Acworth would provide an excellent showcase of the company's progressive environmental stance.

However, there was a problem with holding the meeting at an unfinished store. To allow the meeting to take place, the Cobb County Fire Marshal required an active methane mitigation system with ventilation of the sub-slab vent layer using a large roof-mounted blower. But, the blower for the system would not be fabricated and delivered until just before the store opened. Fortunately, the engineering firm's construction group had a suitable blower in Florida that they hauled to Georgia to serve as a temporary blower, and the meeting was held without incident.

As a result of expert knowledge and progressive thinking of the parties involved, and the cooperation of several government departments, North American Properties was able to take the Lakeside MarketPlace project from inception to completion in just 18 months.

Michael McLaughlin is a senior vice president with SCS Engineers.