The Navy has three cleanup programs at Alameda Point: Superfund, Petroleum, and Radiological. The Petroleum Program takes care of underground concentrations of petroleum, mostly jet fuel, and is organized by corrective action areas. One such area outside Building 5 made it onto the calendar this year.
Dumping jet fuel – Building 5, the largest hangar at the Point, was a busy aircraft maintenance facility. Petroleum products like jet fuel were often disposed of down a drain, which in this case would have gone to an underground oil/water separator. A Navy contractor concluded that jet fuel detected in test wells outside of Building 5 on the south side could have leaked either from the oil/water separator, or the drain line, or both. The area has been designated Corrective Action Area 5B (CAA 5B).
Even a small cleanup area like this requires extensive testing and factoring in a host of variables before cleanup can begin. First, the petroleum test samples are analyzed by counting the carbon atoms, which will give a profile as to whether it is gasoline, jet fuel, or diesel.
Then, groundwater flow must be determined. If remediation methods cause the jet fuel to be pushed out of the treatment zone and on a flow path toward the Seaplane Lagoon, it would create a problem for marine life. A 2008 study found that although groundwater is flowing northwest and away from the lagoon, farther to the northwest the shallow groundwater flow direction curves back toward the lagoon.
Then, what will the area be used for? This area could be zoned for either residential or commercial. Groundwater needs to be evaluated for non-drinking water use and vapor intrusion in buildings. Drinking water does not need to be considered here because the solids content is too high for drinking water use west of Saratoga Street.
How is the jet fuel cleaned up?
This cleanup area will employ two systems – vapor extraction and chemical oxidizers. After the concrete is cut and pipes inserted into the ground, the vapor extraction system comes first.
Vapor Extraction– These systems can be fixed pumping stations or mobile. At Building 5, it was easier to use tanker trucks, which power electric vacuum pumps. The pumps create vacuum underground through a large hose hooked to a manifold that has small hoses going to the various holes, or wells, in the pavement. The vacuum draws fuel, water, and air up to the tanker, which will haul away the fuel/water mixture. The air is diverted to a carbon filter system in 55-gallon drums before venting to the atmosphere. While this is an important beginning, the vacuum only gets about 20% of the fuel. The vapor extraction phase is now finished at Building 5. Next comes the chemical phase.
Chemical Oxidation – The process of injecting oxidizing chemicals into the ground is called in-situ chemical oxidation (ISCO). Here at CAA 5B they will use a special combination of two chemicals designed to raise the soil temperature and stir up the jet fuel with gas bubbles so that it is released from the soil. As the fuel comes loose from the soil particles it is easily turned into carbon dioxide and water. This chemical combo, developed in recent years, is catalyzed hydrogen peroxide and activated sodium persulfate.
Not making the problem worse
This chemical oxidation treatment phase is where the groundwater flow, previously mentioned, takes on importance. The contamination at this corrective action area is at shallow depth. Therefore, injection pressures have to be low to avoid fracturing the soil and sending jet fuel drifting out of the treatment zone and on toward the lagoon. But lower injection pressures mean more time to complete the job. To compensate, more wells are drilled to get more product to the treatment area in a timely fashion.
The chemical treatment phase at Building 5 is expected to commence at the same time as several other petroleum areas in the near future.
Is the Old Oil/Water Separator Still in the Ground? – No one knows for sure if the oil/water separator mentioned above, which is a problem in itself, was ever removed. A recent attempt at drilling a test well in the area where the separator was thought to be located ran into something solid, suggesting infrastructure of some kind. If it is the old oil/water separator, it should be removed, but it won’t be removed under the current jet fuel cleanup action. It is unknown whether it will be made the focus of future action.