Marine Corps Air Station (MCAS) Yuma, AZ
In response to an approximately 75,000-gallon JP-8 fuel spill from a pipeline, GCE was contracted to provide repair activities which included lock out/tag out procedures on all associated fuel lines and excavation to locate and repair the leak. The MCAS Yuma Hot Pit site is located within the airfield of MCAS Yuma on the east side of the Rotary Wing Hot Pit fueling area and adjacent to the intersection of Taxiway's Alpha and Charlie.
The JP-8 fuel release resulted from a leak from an airport hydrant system which fell outside of the Arizona Department of Environmental Quality (ADEQ) underground storage tank (UST) site requirements at the time. Subsequently, airport hydrant systems were added to the UST program and the site progressed under the UST requirements. The MCAS Yuma Environmental Department policy discourages land use controls, so the Hot Pit investigation was planned based on a cleanup goal of residential soil remediation levels and aquifer water quality standards.
Initial activities included the development of Site-Specific Health and Safety Plan and Accident Prevention Plan, Work Plan, and Sampling and Analysis Plan which were submitted for approval by Navy and MCAS Yuma personnel. GCE coordinated with the ADEQ to determine the regulatory path throughout initial stages of the investigation.
GCE completed pipeline repair activities including permitted hot work overseen by base fire and rescue, and installation of a new manway/sump. As part of the initial investigation activities, GCE excavated, characterized, and disposed of 670 tons of impacted soil. During this course of this work, GCE worked with base liaison officers to distribute information to interest local agencies and provided site details during a site visit by these parties.
As part of this contract, GCE conducted field activities to evaluate site specific geology, groundwater conditions, contaminant concentrations, contaminant migration and geotechnical characteristics to develop a Conceptual Site Model. Investigation activities included collection of lithologic and analytical data using hollow stem auger split spoon sampling and direct push with Laser Induced Fluorescence (LIF)/Ultra-Violet Optical Screening Tool (UVOST) from 45 borings, and conversion of 19 borings to monitoring wells. Field screening and laboratory analysis of soil samples were completed throughout the drilling process.
GCE conducted initial groundwater sampling at the newly installed wells along with existing vicinity monitoring wells associated with other remedial investigation. GCE also utilized the monitoring wells to conduct downhole geophysics and compiled all subsurface information to develop a model of subsurface contaminant migration. GCE conducted a topographic survey of the entire site including elevations of all newly installed wells to develop a Navy Surfer model of local groundwater flow characteristics. GIS data were obtained and combined with a basewide geographic information system (GIS) database developed by GCE under separate contract.
GCE subsequently designed and installed a free product recovery (FPR) system and soil vapor extraction (SVE) system with a catalytic oxidizer to target all identified areas of need. The system was designed to fall within the requirements of MCAS Yuma's Class II air permit. The remedial system utilized seven FPR groundwater wells and 13 SVE wells with 21 independently screened intervals. GCE performed multiple years of operation and maintenance activities which included, periodic disposal of recovered JP-8 fuel, air permit compliance sampling of the SVE discharge, semi-annual groundwater sampling, condensate water disposal, system maintenance, and periodic reporting.
Following completion of the multi-year remediation program, GCE was subcontracted for the removal of the SVE and FPR system components which were disconnected and removed from the site. All waste was disposed of in accordance with all local, state, and federal regulations. All in-ground conduit, including SVE plumbing and electrical wiring, was excavated and removed, and all site wells, including 19 groundwater wells and 13 SVE wells, were abandoned in accordance with Arizona Department of Water Resources (ADWR) procedures. Concrete pad and site security fencing were removed and disposed of properly. Upon removal of all remedial system items, the site was graded flat and wetted to aid compaction and vegetative growth. All field activities were documented in a Closure Report.