When contaminated soil is identified for removal from remote locations, traditional dig-and-haul remediation techniques can create logistical and costly difficulties for these off-the-grid sites, not to mention a variety of associated environmental impacts.
This challenge for the oil and gas industry inspired a non-traditional technique developed by WSP USA, that is emerging as a practical, environmentally beneficial alternative to dig-and-haul operations.
The innovative process is known as solar-powered soil vapor extraction (SVE). It was designed for small-scale cleanups at a former northwestern Colorado natural gas compressor station where power infrastructure limitations made dig and haul an impractical option.
“Dig and haul has always been the selected remedy for these types of sites,” said Rob Rebel, senior engineer for WSP. “However, these rural oil and gas facility locations did not allow for the deployment of traditional remediation equipment.”
The natural gas compressor station was investigated and identified to contain more than 3,000 cubic yards of soil, some as much as 35 feet below the surface. The closest landfill was more than 60 miles away.
The long hauling distance would require significant fuel consumption and the large amount of soil transported would significantly reduce the capacity of the landfill where it would be disposed. The economic and environmental impact of this option would be substantial.
The solar SVE system reduces or eliminates many of the negative elements associated with typical dig-and-haul operations: increased truck traffic that can pose safety hazards and degrade roads, nuisance dust and odor, greenhouse gas emissions, increased landfill waste, and higher cost.
Known as the VariSun Mobile Solar System, developed by Sustainable Technologies in Alameda, California, the innovative system not only addressed the power problem for the remote location, but eliminated the need to haul contaminated soil from the site and resulted in no loss of topsoil. The change resulted in a savings of about $50,000.
WSP provided design, operation and maintenance, installation, assessment, reporting, with closure expected in 2021 for the northwestern Colorado oil and gas remediation project.