One Million Gallon Gasoline Release: Des Moines, Iowa
An underground piping failure at a large bulk storage terminal resulted in an estimated release of over one million gallons of gasoline, which at the time was among the largest single land releases of refined petroleum products in U.S. history. Up to 5 feet of free-phase gasoline was floating on the ground water over portions of a 20-acre area. An immense 60-acre dissolved-phase benzene plume with concentrations more than three orders of magnitude above regulatory drinking-water limits originated from the spill and threatened a nearby protected recreational waterway.
SCOPE OF WORK
Leggette, Brashears & Graham, Inc. (LGB) responded with an intensive remediation effort that included numerous technologies and approaches suited to each phase of the project. Initial emergency response included the installation of recovery trenches and recovery sumps. Remediation of the free-phase gasoline over such a large area required the installation of a multi-phase extraction (MPE) system that included 115 recovery wells, 3 separate buildings, 7 individual MPE units, 2 different types of air treatment technologies, 4 integrated PLC control panels, and over 10 miles of underground piping installed on an active terminal with literally hundreds of utilities over the remediation area.
The MPE system was pre-designed to be easily converted to an air sparge / soil vapor extraction (AS/SVE) system. This conversion was implemented during the project life-cycle process where recoverable free product was no longer present and focus was shifted to recover residual free product. The carefully engineered pre-design made for an easy transition and saved the client significant funds.
A massive benzene plume was addressed using an LBG developed and award winning technology coined the Air Lift Re-infiltration Trench (ALT) system. The ALT is an creative combination of five traditional technologies (air lift pumping, in-situ air stripping, oxygenation, groundwater re-infiltration, and in-situ bioremediation) that can rapidly and cost-effectively treat large dissolved-phase plumes.
In all, over 1.35 million gallons of gasoline were recovered. The MPE system effectively eliminated recoverable free-phase product, the AS/SVE system effectively removed residual product, and the ALT system rapidly remediated the downgradient dissolved-phase benzene plume prior to impact to a protected recreational river.