Industry-Submitted Notification

What Happened?

• A third-party combo unit operator and assistant began offloading mixed oilfield waste into a 400-barrel tank.
• The operator did not connect the vent line or grounding cable and parked within 7.5 m of an adjacent “Hot Oil” tank.
• As the tank approached capacity, 57 m³ (60 m³ capacity), the truck operator began to hear air rushing through the transfer hose.
• The operator stopped the transfer pump; however, fluid was released from the temporary tank vent line and relief hatch.
• An abrupt loss of primary containment (LOPC) occurred at the temporary slop tank, releasing approximately 2.5 m³ of product.
• Personal gas monitors alarmed on high LEL
• Combo truck engine began to “runaway” (Engine runaway = flammable gases or vapors mixed with air are drawn into the engine; increased fuel source causes engine speed to increase with the potential for explosion).
• The truck operator activated the positive air shut off, to shut down the engine.

What Could Have Happened?

• Multiple fatalities or life-altering injuries due to fire or explosion
• Significant equipment damage
• Regulatory investigation, delays, and potential enforcement actions

Learnings / Causes:

Worker Inexperience and Training:

• The combo unit operator had experience operating vac trucks but not previously performed this type of fluid transfer and was not trained on the task.
• Company procedures for fluid transfer were not reviewed.

Pumping Pressure:

• Normal off-loading pump pressure is 5 psi. At the time of the overflow, the pump was operating at 10 psi, increasing the transfer pressure and rate.

Air Ingress:

• Air was pushed from the combo unit tank to the slop tank.
• The 45° angle of the combo unit, combined with the location of the high-point take-off valve above the fluid level, caused the pump to lose fluid suction.

Corrective Actions:

• Ensure service providers train workers on fluid transfer to tankage, including safe operating pressures.
• Develop organizational guidance for temporary tank use, including:
  • Bonding and grounding requirements
  • Use of environmental liners
  • Vent line use and workplace labeling
  • Fill limits
  • Tank placement and staging
  • Prevention of air ingress
• Conduct targeted inspections of fluid transfer operations.
• Conduct expectation review meetings with service providers.
• Implement the Green Hand Program for new and young workers.