Environmental Engineering and Remediation
Remedial Design and Remediation

Northern Operable Unit (NOU) Sites 2, 3, and 4 Remedial Action

Naval Air Station (NAS) Fallon, NV

The overall scope of this project was the completion of a remedial action (RA) for the NOU Sites 2, 3 and 4 at NAS Fallon, NV. The NOU encompasses more than 81 acres in the west-central portion of the base. The NOU is made up of three Installation Restoration Program (IRP) sites: IRP Site 2 (New Fuel Farm), IRP Site 3 (Hangar 1 Area), and IRP Site 4 (Transportation Yard). These sites were grouped together based on geographic proximity, similar geology and hydrogeology, similar types of contaminants, and commingling of groundwater plumes. The remedial action conducted at IRP Sites 2, 3, and 4 was consistent with the final remedy documented in the Record of Decision (ROD) for these sites.

  • IRP Site 2 -- New Fuel Farm. The New Fuel Farm, constructed in 1957, stores about 3.3 million gallons of fuel in three aboveground storage tanks (ASTs). A dissolved and fuel product plume extends across the main portion of IRP Site 2. In 2008, the apparent free product thickness exceeded 0.5 inch beneath several main areas. IRP Site 2 is within the active operations area of NAS Fallon and remains an active fuel farm.
  • IRP Site 3 -- Hangar 1 Area. IRP Site 3, approximately 26 acres, is located in the general vicinity of Hangar 1. IRP Site 3 includes two primary, unpaved source areas: one to the north of Hangar 1, and one to the south of Hangar 1. The northern source area contains the northern aircraft fluid disposal area, the bowser disposal area, and an oil-water separator. The southern source area contains the southern aircraft fluid disposal area, the ground support equipment area, and the wells air facility area. IRP Site 3 is within the active operations area of NAS Fallon and is currently used for active aircraft operations.
  • IRP Site 4 -- Transportation Yard. IRP Site 4 is located in the west-central portion of NAS Fallon, immediately south of IRP Site 2. The site encompasses approximately 7 acres and consists of buildings and a maintenance yard used for general maintenance of public works vehicles and small equipment, such as compressors and generators. The area previously contained a 5,000-gallon AST near Building 333 that stored diesel fuel for a boiler. The source of petroleum contamination in soil is presumed to be the AST and the transfer piping. IRP Site 4 is within the active operations area of NAS Fallon and is currently used for maintenance of public works vehicles and small equipment.

GCE was subcontracted to provide support on several work elements: 1) Project Management and Support, 2) Planning Documents, 3) Fieldwork, and 4) Remedial Action Completion Reports (RACRs).

GCE assisted with the preparation of the Work Plan (WP), Site Safety and Health Plan (SSHP), and the Sampling and Analysis Plan (SAP). The SSHP included an Accident Prevention Plan (APP) and an activity hazard analysis (AHA). The SAP consisted of a Field Sampling Plan (FSP) and Quality Assurance Project Plan (QAPP).

Following the Navy approval of the WP, SAP/FSP/QAPP, and SSHP/APP/AHA, GCE provided task management and technical/logistical support for the following field activities.

  • Annual Gauging of Wells. Annual gauging of existing monitoring wells in IRP Sites 2 and 4 was performed to identify wells where free product persists. Free product was recovered from the wells and trenches containing free product greater than 0.5 inches thick.
  • Free Product Recovery. Recovery of free product at IRP Sites 2 and 4 was conducted on a biweekly basis from wells identified to contain sufficient product. Wells targeted for recovery were selected considering results from previous recovery events and biannual gauging. During recovery efforts, wells were identified as high-producing (>10 gallons recovered quarterly) or low-producing (<10 gallons recovered quarterly). Wells identified as high-producing were targeted for continued recovery efforts, while wells deemed low-producing were monitored for future recovery efforts or elimination from the recovery program.
  • Long Term Monitoring. Monitoring wells at IRP Site 3 were sampled semiannually during the contract period of performance and analyzed for TCE and TCE biodegradation daughter products.

GCE was tasked to prepare the Quarterly Monitoring Reports and Interim RACRs. The Quarterly reports were prepared to identify the progress of remedial action activities at the NOU. A RACR was completed for each year of the contract period of performance. The RACR formally documented the achievement of cleanup objectives.