Oscar W. Larson is now a part of OWL Services (owlservices.com). Oscar W. Larson values its customers, suppliers and employees and is committed to maintaining strong relationships with all by delivering the best quality service in the industry.
(800) 482-1200


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Compliance Testing & Inspections

Our team combats Petroleum Loss Control through monitoring and industry-leading inspections.


Compliance Testing

Oscar W. Larson Co. offers compliance testing and inspections for Spill Containers, Overfill Prevention Devices, Under Dispenser, and Containment Sumps in accordance with EPA’s 2015 Underground Storage Tank Regulations.

We offer the EPA certified DPleak® (Deferential Pressure Technology) patented testing method to test your containment sumps using a seal and constant vacuum to find leaks. This allows us to pinpoint leaks and does not generate hazardous contaminated water to perform the testing.



  • Custody Transfer Audit
  • Offshore Ship to Ship Discharge
  • Bunker & Draft Surveys
  • Reporting
  • Inspection Company Evaluations
  • Tank Inspections
  • Vessel Owner Representation
  • Contamination Investigations
  • Analysis Consultations
  • Loss Investigations
  • OBQ and ROB Surveys
  • Blending Consultation
  • Terminal Inventories
  • Equipment Calibration
  • Shore Tank Gauging
  • Marine Vessel Gauging
  • Temperature Measurement
  • Vessel Loading & Discharge
  • General Vessel Operations
  • Atmospheric Monitoring
  • Product Sampling
  • Investigation of Cargo Discrepancies
  • Sample Quality Laboratory Testing and Retain
  • Crude Oil Rail Car Services
  • Cargo Additive Treatment