The grounding of the oil tanker Exxon Valdez on Bligh Reef in Prince William Sound, Alaska, on March 24, 1989, spilled approximately 11 million gallons of crude oil into the pristine waters of the sound. The remote location complicated immediate containment and recovery efforts. The spill eventually affected 1,300 miles of coastline, requiring a complex cleanup effort in the rugged Alaskan environment.
Immediate Response and Containment Strategies
The initial response focused on mechanical containment and removal of floating oil. Floating barriers known as booms were deployed to corral the oil and prevent its spread to sensitive areas, such as salmon hatcheries. Skimmer vessels were then used to collect the concentrated oil. However, recovery was hampered by delays in equipment availability and the heavy, thick oil frequently clogged the skimmers.
A limited thermal technique, in-situ burning, was also employed early in the response. This involved surrounding a section of the oil slick with a fire-resistant boom, towing it away, and intentionally igniting the oil. A controlled test burn successfully removed an estimated 15,000 to 30,000 gallons of crude oil. This method was only feasible when the oil was fresh and the weather was calm.
Shoreline Oil Removal Techniques
Once the oil reached the shorelines, the cleanup became a massive, multi-year effort utilizing labor-intensive methods. The most widely used technique was high-pressure hot water washing, applied to remove oil from the rocky and cobble shorelines. This aggressive method used high-pressure hoses and steam to blast the weathered oil off the rocks. The hot water would flush the oil back into the water for collection, as cold water was ineffective against the thickened crude.
While the hot water washing was effective at physically removing oil from hard surfaces, it caused significant ecological damage. The high heat and pressure killed many intertidal organisms, such as invertebrates, that formed the base of the shoreline ecosystem. Scientists determined that treated sites suffered more severe declines and took longer to recover than oiled but untreated sites. Furthermore, the water pressure sometimes drove oil deeper into beach sediments, trapping it beneath the surface.
Thousands of workers engaged in manual and mechanical removal of oiled material. This involved physically scraping oil from beaches and using absorbent materials to wipe down individual rocks. Vacuuming equipment was deployed in some areas to suck up oil and debris. Despite the sheer scale of the human effort, the overall percentage of oil recovered through all methods was relatively low.
The Role of Bioremediation
As physical cleanup progressed, scientists introduced bioremediation, a biological method to accelerate the degradation of remaining oil. This technique involved applying nutrient-rich fertilizers directly to oiled beaches. Indigenous oil-eating microorganisms were naturally present but limited by a lack of nitrogen and phosphorus.
The addition of these nutrients, such as the liquid oleophilic fertilizer Inipol EAP22, stimulated the bacteria to break down petroleum hydrocarbons at a significantly faster rate. Field studies demonstrated that fertilization could increase the natural biodegradation rate by two to three times. Bioremediation proved a useful supplemental strategy for treating residual oil.
Long-Term Environmental Assessment
Despite the massive, multi-year cleanup effort, residual oil remained trapped in the subsurface sediments of the shorelines. Surveys conducted years after the active cleanup ceased confirmed the persistence of this “lingering oil,” particularly in low-energy environments. This trapped, weathered oil was isolated from natural weathering processes and was not readily accessible for degradation.
Over time, natural attenuation—the breakdown and dispersal of contaminants by natural processes like wave action and microbial activity—became the primary mechanism for recovery. However, the aggressive use of high-pressure hot water washing delayed the recovery of certain marine life in the intertidal zone, demonstrating that the cleanup itself introduced a separate long-term impact. Long-term monitoring programs continue to track the fate of the remaining oil and the recovery of injured species.