Soil remediation at former gas site saves thousands of dollars

Columbia Pipeline Group Langley, KY

Project Highlights

Client Challenge:
Columbia Pipeline Group (CPG) needed to remediate soil at the former site of a compressor station. The task was complicated by the fact that the contaminated soil surrounded active gas lines – one of them a 20-inch line, pressurized to 200 psi.

Our Approach
H&A Construction Services (HCS) provided excavation, stabilization and in situ solidification of the contaminated soil near and beneath the gas lines. In total, 5,009 cubic yards of soil were permanently bonded, rendering the contaminant (LNAPL) immobile. The custom-designed, low permeability cement mix also protected against further outgassing.

Value Delivered

  • HCS completed the remediation on schedule, without impact to existing operations.
  • Columbia realized $12,000 in cost savings as a result of HCS fine tuning the amendments used to bond and solidify the contaminated soil.

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