Large Scale Terminal Remediation: Kansas City, Kansas
Leggette, Brashears & Graham, Inc. (LBG) successfully investigated and addressed over half of a large, active petroleum bulk storage terminal that was significantly impacted by numerous historic releases of free-phase product including diesel fuel and gasoline. It was estimated that nearly 1½ million gallons of released products had impacted soil and groundwater over 50% of the 57-acre site. The terminal is located on alluvial deposits adjacent to a major U.S. river with resulting large water-table fluctuations in excess of 14 feet, which, combined with the variable thickness of a surficial clay layer, results in difficult and rapidly changing remediation conditions. Petroleum impacts have resulted in indoor air quality issues at the site (a previous explosion on the facility was attributed to subsurface vapor migration to an existing structure).
SCOPE OF WORK
LBG proposed and implemented engineering controls, including sub-slab ventilation systems and positive pressure HVAC to eliminate vapor migration and exposure in affected occupied structures. At the client’s request, LBG implemented continuous vapor monitoring devices and partnered with an industrial hygiene firm to prepare draft vapor monitoring and response procedures for terminal personnel.
LBG completed a site-wide remedial investigation to delineate the horizontal and vertical extents and magnitudes of petroleum and fertilizer impacts per specific regulatory requirements. A detailed feasibility study and cost-benefit analysis was completed to determine the most cost-effective approach to mitigate the site. Pilot tests were conducted on selected remedial options to establish design criteria. A complete remedial design considering the hydrogeologic setting, remedial goals, regulatory drivers, facility infrastructure, and total project budget was prepared. A phased and integrated approach was implemented to reduce overall costs. The designs included multi-phase extraction, air-sparging, soil-vapor extraction, groundwater treatment, and state-of-the-art air treatment systems. The initial phase of the design removed the equivalent of approximately 112,000 gallons of petroleum in the first 5½ months of operation.