Brief

At an active bulk fuel storage facility in a city located in Eastern Saudi Arabia, about 60km inland from the Persian Gulf, historical spills and leaks had resulted in up to 3.0m of gasoline floating on an unconfined, saline aquifer. The urban location required a secure, explosion-proof, low-impact solution that could adjust to seasonal water table fluctuations, withstand corrosion, and function without interfering with the facility’s daily operations.

Process

To capture and recover the gasoline from the surface of the water table, IRSL and their partner installed specialized pneumatic skimmers within 10 wells, in an area extending approximately 60m2. The chosen system was based on a series of tests, including NAPL transmissivity tests, in select wells. They enhanced the recovery of LNAPL from each 10cm diameter well using a low-vacuum system, which increased both the rate of recovery and area of influence.

Intensive testing comparing the effect of the vacuum versus no vacuum indicatedthat the radii of influence increased from approximately 1m to greater than 7m under the vacuum conditions and increased the rate of recovery by 5-fold.

Results

As a result of continuous optimization, the percentage of gasoline within the fluid recovered has been greater than 99.999% over the recovery period.

The NAPL plume has been contained and over 2,500L of gasoline have been recovered from a 100m2 area in less than two years.

Free product thickness in monitoring wells has decreased by over 90%.

System operation and maintenance costs have decreased relative to inflation over time.

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