A Threat to Wildlife
Columbia Pipeline Group found measurable levels of light non-aqueous phase liquid (LNAPL) at the former location of one of its compressor stations, located within the floodplain of a small river. The situation was complicated by the fact that contaminated soil surrounded active gas lines – one of them a 20-inch diameter line, pressurized to 200 psi.
Stopping the Offender in its Tracks
HCS recommended the soft excavation and off-site disposal of surface soil, with in situ stabilization and solidification of the contaminated soil near and beneath the gas lines. The project involved unearthing short, 15-foot sections of the active gas lines to a depth as much as 25 feet. Bentonite slurry supported the gas pipes while the soil beneath them was removed for treatment.
Altogether, 1,182 cubic yards of soil were stabilized inside the gas line corridor and another 3,827 cubic yards stabilized outside the corridor, totaling 5,009 cubic yards. A laboratory-designed cement mixture was used to permanently bond the contaminated soil and render the LNAPL immobile. The cement specifications also ensured low permeability, to further reduce the potential of vapor leaching into the soil and groundwater.
Maximizing Value to the Client
HCS successfully completed the project, excavating around and under the gas lines without impact to existing operations. HCS fine-tuned the cement formula recommended by the lab, reducing the client’s cost of materials by $12,000.
For more information on this project, contact Walter Kurzeja