Formatted Title
Proactive Combined Remedy for Remediation of Jet Fuel Release: Sequencing a Phased Approach
Background/Objectives
A release of jet fuel occurred at a facility, with an estimate of 2,600 gallons released based on inventory records. The release occurred over several days and the pattern of the release was complicated by structures and runoff across a roof top. Emergency response activities recovered approximately 25 gallons of fuel, and 45 tons of contaminated soil was removed. Numerous underground utilities are present within the release area, and proximity to a building foundation complicated additional emergency soil removal. The release occurred at a busy area of the facility, including fueling operations for aircraft. Soils at the site consist primarily of dense, fine to medium grained sands. Groundwater is encountered at approximately 35 feet below ground surface (bgs).
Approach/Activities
A sequenced approach for investigation and remediation was required to minimize spread of petroleum carbon impacts, protection of human health, and limiting disturbance to site operations. Initial activities included delineation of light non-aqueous phase liquid (LNAPL) impacts, soil borings, and installation of monitoring wells, including sentinel wells downgradient of the impacted area. An early remediation step was installation of an in situ chemical oxidation (ISCO) permeable reactive barrier (PRB) utilizing predominantly potassium persulfate with a lower quantity sodium persulfate downgradient of the release to minimize migration of contaminants during delineation and the LNAPL removal phase. Solar-powered skimmer pumps were installed in three wells and operated for approximately one year, which removed more than 230 gallons of LNAPL. Soil vapor extraction (SVE) was used to remove residual LNAPL in the vadose zone. ISCO injections using activated sodium persulfate were selected for the source area. The decision on when to perform source area ISCO injections was determined using a matrix of LNAPL and petroleum hydrocarbon monitoring observations.
Results/Lessons Learned
Remediation of LNAPL sites is most effective with multiple remediation activities performed in series and in parallel. Through a series of sequenced activities LNAPL mass and volume has been reduced, petroleum hydrocarbons have not migrated to the downgradient sentinel wells, and site operations have been minimally disturbed. Dense sands beneath the site were challenging for direct push drilling and injection. Based on the experience with the ISCO PRB, the injection program for the source area ISCO was designed to mobilize two direct-push rigs which reduced more than seven on-site injection days. Future activities are anticipated to include additional LNAPL removal, SVE, and polishing ISCO injections