Petroleum Cut-Off Wall Installation

ONE has worked with an industrial client in Blue Ridge region of Virginia to design and install a petroleum cut-off wall on the bank of a major regional river.

The cut-off wall was designed, using hydrogeologic modeling, to stop a historic diesel plume from migrating into the river while still allowing groundwater to flow under the wall to recharge the river. The installation trench, and pre-installed recovery sumps, also serve as a product accumulation and recovery system.

A brief synopsis of the project is as follows:

• Pre-Installation Design Tasks
  • Analysis of historic groundwater elevations trends
  • Hydrogeologic modeling of the impact of the wall on groundwater flow
  • Selection of a hydrogeolocially appropriate backfill for the cut-off wall trench
• Petroleum Cut-off Wall Installation Tasks
  • Demolition of unused infrastructure in the project area
  • Excavation and backfilling of the wall trench and installation of recovery sumps
  • Precision installation of the cut-off wall panels. Terminal depth of the wall panels could not deviate more than ±0.05-foot from the design specifications
• Post-Installation Tasks
  • Installation of a clay cap over the over the trench to prevent water infiltration
  • Final grading and surface restoration to prevent scouring
  • Vacuum development of recovery sumps
  • Long term monitoring and product recovery in the trench