Project:
Active Bulk Fuel Storage Terminal
Bottom Line: Evaluated candidate technologies, conducted pilot study, and designed full-scale oxygen injection system to remediate LNAPL and expedite site closure.
Summary of Project
The bulk fuel storage terminal site is at a busy commercial port and contains seven aboveground storage tanks that have been used to store diesel fuel and fuel oils custom-blended for various maritime customers. Free-phase diesel fuel was present as LNAPL floating on the shallow groundwater at 5 to 10 feet below grade. Remediation was required to remove recoverable LNAPL and reduce dissolved-phase hydrocarbon concentrations to below site-specific risk-based cleanup levels for TPHd and naphthalene. Orion conducted the following remedial actions:
- Operated an LNAPL recovery system using multiple pneumatic pumping skimmers to remove the recoverable portion of LNAPL.
- Evaluated technologies for remediating residual LNAPL and dissolved-phase petroleum hydrocarbons including excavation, DPE, ISCO, and aerobic bioremediation.
- Conducted a 3-month pilot study to evaluate the effectiveness and feasibility of oxygen gas injection to remediate groundwater and meet site closure objectives. Injected atmospheric air and high-purity oxygen at various flow rates and durations to evaluate the optimal oxygen mass loading rate for full-scale remediation.
- Developed and monitored multiple performance metrics during the pilot study including water levels, geochemical indicators, presence and activity of microorganisms, and LNAPL recovery rates. Observed increased LNAPL recoverability from mobilization of submerged LNAPL and decreased hydrocarbon-impacted groundwater concentrations caused by a reduction in mass flux within the treatment area.
- Prepared a remedial action plan for groundwater remediation using oxygen gas injection. Designed an injection system consisting of 34 injection wells across an approximately 22,000-square-foot portion of the LNAPL plume downgradient of the bulk storage terminal. Expanded the LNAPL recovery system to include five wells within the oxygen injection treatment area to remove submerged LNAPL mobilized during injection activities.
- Prepared bid documents and specifications and coordinated with property owner and stakeholders for installation of the remediation system. Provided construction oversight and field engineering during 10-week system installation.
- Performed full-scale start-up; currently conducting weekly performance monitoring to evaluate overall remediation effectiveness.