To manage the response, ARCO implemented the incident command system utilizing unified command. Originally, the unified commanders were from ARCO and the California Department of Fish and Game (CDFG). Representatives of ARCO filled the operations, logistics and finance section chief positions with CDFG fulfilling the primary planning section chief role. On the 18th a representative of the US Environmental Protection Agency arrived on scene and the EPA OSC became a member of the unified command.

There was concern related to the structural integrity of the upstream water impoundment dams, in particular due to continuing aftershocks, and rumours about the dams having been damaged. Flooding of the entire riverbed due to dam failure would have posed a major threat to responders. An investigation showed, however, that no structural problems existed, but much time and effort was spent resolving this and similar issues in the early stages.

Regional / national hazmat teams

The spill was initially discovered by ARCO at 05:35 am. ARCO notified the National Response Center at 07:41 am and California Office of Emergency Services at 07:50 am. Reports of the spill reached the US Environmental Protection Agency (EPA) at approximately 12:28 pm, but as a 150 barrel spill. It was not until the morning of the 18th that EPA received information on the true magnitude of the spill. EPA then mobilized federal resources to the spill site.

The first cleanup steps consisted of constructing a containment berm across the drainage ditch to prevent additional oil from entering the Santa Clara River, and construction of two underflow dams at sites farther downriver. The containment berm successfully impounded over 1,600 barrels of spilled oil, which was recovered by vacuum trucks over the first two days.

Difficulties were encountered in building the underflow dams. Due to the shallowness of the river, and its extended riverbed, it was hard to develop sufficient water in depth behind the dams for them to be effective. The flow into the underflow pipes created whirlpools that would suck the pooled oil down with the water and carry it through. Eventually deflection booms were installed at both underflow dams. The reduced current and marginally increased river depth behind the dam then allowed the oil to be diverted into collection pockets, where it was recovered using vacuum trucks and dams skimmers.

Approximately 12 miles from the point where the oil first entered the Santa Clara River, the surface water of the river dried up as the water percolated into the porous gravel riverbed. A terminus dike was constructed at this site on day two. This formed a pond to recover oil from, and prevented the further downstream migration of the oil.

At one oil spill location, response efforts had to wait for the repair of a ruptured natural gas pipeline that constituted a hazard to the responders.

Initial response efforts were hampered by several earthquake-related problems. Logistics was complicated by closed roads, power outages, lack of available lodging (due to locals unable to stay in their homes), disruption to the communications infrastructure, and the lack of potable water due to disruptions in the distribution systems. There was also competition for resources with the higher priority public health and safety concerns in the Los Angeles Basin. Interstate 5 and State Highway 126 from Ventura were both closed. Interstate 5 was the primary access to the region from Long Beach from where most of the spill response resources were mobilized. Highway 126 was the only road that followed the general course of the river from the spill site to the sea, and the primary access for responders coming inland from Santa Barbara and Ventura. Highway 126 was reopened on the 18th.

The release of oil and the cleanup operations impacted ca. 100 acres of woody and herbaceous vegetation, ca. 150 acres of river sediments, as well as fish including the arroyo chub and the federally endangered unarmored three-spine stickleback, a number of bird and other wildlife species, and riparian vegetation including critical habitat for the federally-listed endangered least Bell’s vireo.

ARCO settled to pay $8,125,000 to the United States and State agencies for the earthquake-related spills, as well as response and damage assessment costs of $854,966.

Over the days following the earthquake, more than 500 people vacuumed crude oil out of the Santa Clara river and catalogued dead animals. Subsequently, 100 acres of contaminated vegetation along the riverbank were dug out.

Cleanup of the oiled vegetation continued for several days; however, on 24 January it started raining and site operations had to be suspended. Unfortunately, the increased river flow washed out the containment that had been installed along the river, and even breached the first terminus dike. Cleanup operations were suspended on 25 January due to the water level and the fact that all access points were impassible. On 26 January the collection and containment sites that had been washed out were re-established. A large amount of oil was now pooled at the terminus dike and recovery of this oil began.

Cleanup operations removing the oiled vegetation continued for several weeks after this, but most of the free oil was recovered immediately after the rains of the 24th. Buried oil was discovered in several locations afterwards and more substantial removals were necessitated, particularly in the lower reaches of the affected area. One successful method for dealing with the buried oil was dewatering sections of the river and mechanically disking the soil. This was followed by water flushing, which moved the free oil downstream to excelsior collection dams.

With over 450 people involved in the spill directly, ARCO had developed a well-thought-out contingency plan in case of rain; and this plan worked extremely well when implemented. It was an important part of the planning operation for this event, and inclement weather contingencies should almost certainly be considered in every major response.