Dam as Defense
FEATURES
INCIDENT REPORT
Intercepting the flow of half a million gallons of gasoline was one part of the strategy for mitigating a California pipeline spill.
(All photos by Edward G. Fleming)
The very different defenses of two Orange County, Calif., areas weren’t the kind of protection needed when 465,000 gallons of gasoline spilled from a ruptured pipeline.
The military arms of Tustin Marine Corps Helicopter Air Station wouldn’t have protected the base from the fire hazard, nor would the legal status of Upper Newport Bay have protected that state ecological reserve from the toxicity hazard.
It took the intervention of fire departments and many other agencies to keep them safe.
A 10-inch petroleum transmission line runs from Los Angeles to San Diego, buried alongside the Atchison, Topeka & Santa Fe Railway right-of-way and passing through densely populated residential regions, industrial areas, and open wildlands. Twelve hundred gallons of gasoline, diesel, or jet fuel are pumped through the common carrier pipeline each minute at 1,466 psi.
At 12:30 p.m. November 22, 1986, a rupture occurred along a three-foot-long welded seam of the pipeline in an industrial area 30 miles southeast of downtown Los Angeles. Seven minutes later, a workman called fire dispatchers to say that his building was being showered by a 90-foot lateral stream of liquid.
The Orange County Fire Department dispatched three engines, a truck, a haz-mat unit, and a battalion chief, and put the incident on what’s known as the Los Angeles Basin Leak Notification Wheel. This telephone network simultaneously notifies all major pipeline companies in southern California through a single phone call over a dedicated hotline. A fire department dispatcher can alert any one of the pipeline operators, who will then relay the information to the others. Each pipeline operator immediately checks pressure readings and stops pumping, if that’s warranted.
Emergency vehicles staged upwind, since the responders hadn’t yet identified the product or determined its flammability. The officer of the first engine to arrive assumed incident command. Seeing an as-yet-unidentified petroleum product leaking into a nearby storm channel, the incident commander took the first step in what would become a three-pronged strategy: eliminating ignition sources. The officer asked City of Tustin police to divert street traffic, while Santa Fe authorities halted all Amtrak and freight train traffic. As a back-up, firefighters “shortcircuited” the tracks to generate a red railway signal. Most industrial plants in the area were already shut down, because it was a Saturday.
When the Orange County Fire Department’s haz-mat team arrived—equipped with proximity suits and self-contained breathing apparatus—it got a sample of the bluish liquid. A check with combustibility meters indicated the liquid was gasoline.
(It would later become clear that the familiarity of the product caused responders to let their guard down. The gasoline was treated only as a flammable fuel, instead of a highly flammable haz mat, 14 percent of which is toxic benzene derivatives. Without regard for that mindset, gasoline vapors become toxic at their threshold-limit value [TLV] of 300 parts per million, less than one eighth of the 2,600 ppm that constitutes 20 percent of gasoline’s lower explosive limit [LEL].
(Firefighters in the first-arriving engine companies didn’t wear selfcontained breathing apparatus, and 14 of them suffered respiratory problems. Eight were hospitalized. There also was no emergency decontamination area established.)
A battalion chief assumed command at 1 p.m. and assigned another as operations section chief, establishing geographical sectors—Division A near the rupture site and Division B in the adjacent industrial area. Four thousand gallons of product were flowing into nearby San Diego Creek each minute, and Division B indicated that “if it finds an ignition source, we will have a major problem.”
Fire dispatchers notified the state fire marshal’s pipeline division, as required by state code, and the incident commander requested additional resources. Two ad hoc strike teams—comprising five similar units (in this case, engines) from scattered fire stations with a battalion chief as their leader—responded, along with a department-owned bulldozer and a mutual aid haz-mat team from the Anaheim Fire Department. Four more strike teams from nearby cities were put on standby in case of ignition.
San Diego Pipeline Co. received leak notification through the pipeline wheel six minutes after the fire dispatchers called, and the operator at the company’s Orange pumping station (11 miles upstream from the rupture) confirmed an extreme drop in pressure. In another four minutes, the pump station valves were closed and pumping had ceased. At 1:16, the pipeline company contacted the fire department and confirmed that the product was unleaded, high-grade gasoline.
As soon as they’d established the incident command’s two divisions, the battalion chiefs had initiated the other two prongs of the strategic plan: controlling the flow of product from the pipeline, and intercepting the leading edge of the spill before it reached Upper Newport Bay, the terminus of the San Diego Creek—Flood Control Channel.
Of more immediate concern was the Marine Corps helicopter station, which borders San Diego Creek a quarter mile downstream from where the pipe ruptured. The uncontrolled, volatile liquid floated atop a small flow of creekwater, while flammable vapors engulfed the family housing area of the base. The Marine base fire chief was assigned Division C, and base firefighters evacuated 2,500 residents.
When a fire department division chief assumed the role of incident commander at 1:45, he moved the command post to the Marine Corps fire station. He ordered that 2,000 gallons of AFFF (aqueous film-forming foam) be placed on standby at John Wayne Airport nearby, and requested vacuum trucks from International Technologies Corp., a private environmental contractor from Torrance, Calif.
Although the San Diego Pipeline Co.’s Orange station had stopped pumping within minutes of notification, it took nearly two hours from when the leak began to actually stop the flow. The rupture occurred at one of the lowest points in the 135-mile pipeline, so once the pumps stopped, gravity drew the gasoline back down to that point. The State Fire Marshal’s Office calculated that the head pressure there was 118 psi.
No remote-controlled, motoroperated valves had been installed along the line. (None was required by law.) So to prevent backflow, a skeleton, weekend pipeline crew had to close valves by hand about a mile upstream and downstream. By the time they’d finished at 2:25 p.m., 465,000 gallons of gasoline had discharged into the San Diego Creek channel, according to State Fire Marshal’s Office calculations.
To intercept the approaching fuel atop the water in the creek, the operations chief had established Division D at creekside about 2½ miles downstream from the rupture. Its job was to build a 4-foot-tall, 200-foot-wide dam across the creek channel to retain the gasoline, with its specific gravity of 0.74, while allowing water to continue downstream. Fire department and state Emergency Management Agency bulldozers built the earthen dam. The Irvine Ranch Water District delivered 14-inchdiameter pipes which, incorporated into the dam, would carry the water to the other side.
An hour and a half after the initial rupture, Anaheim’s haz-mat team had injected dye marker into the flowing gasoline to allow visual reconnaissance in the streambed. The underflow dam was completed just 10 minutes ahead of the gasoline, and when the product arrived, the dam quickly became saturated with both gasoline and water. It began to fail within an hour.
In that time, the gasoline pooled three feet deep for a quarter mile behind the dam, generating a white, hydrocarbon fog which registered at more than its lower explosive limit (LEL). The California Occupational Safety and Health Administration prohibits exposure to vapor concentrations above 20 percent of the LEL, so firefighters couldn’t reinforce the structure and IT Corp. personnel couldn’t vacuum the pooled gasoline into a waiting tanker truck.
Marine Corps crash trucks and the Shell Oil Fire Brigade (summoned from a refinery in Carson, 30 miles to the north) assisted the county firefighters in applying 1,500 gallons of AFFF to the pool. This suppressed vapor production, but a blanket of explosive fog lingered in the 30-foot-deep streambed, causing combustible gas readings of 75 percent of the LEL.
The Shell Oil fire crews tackled this problem with 2,500-gpm water monitors directed into the channel slightly downstream of the dam. By creating air turbulence this way, they dropped the vapor concentration to 20 percent of the LEL. Bulldozer operators then reentered the channel to stabilize the five-hour-old dam, while IT Corp. began an around-the-clock vacuum operation.
During the night, one bulldozer operator, in trying to move a pipe manually, fell into the pooled gasoline. He was hospitalized for several days with chemical pneumonia, an illness that might have been less severe if a decontamination unit had been set up in anticipation of such events.
Even when reinforced, the underflow dam couldn’t retain both gasoline and water indefinitely. Therefore, Division D constructed a second dam about a mile upstream from the first. The upper dam intercepted the flowing streamwater, which reduced hydraulic pressure on the lower dam and allowed for better containment of the pooled gasoline.
Some water-soluble gasoline components, along with 200 gallons of bulk gasoline, did escape beyond the underflow dam during the evening. Haz-mat crews and personnel from state and county water quality agencies placed booms and absorbent pads downstream throughout the night to remove these residual hydrocarbons from the creek water.
Combustible gas readings taken outside the Irvine Hilton Hotel, several blocks from the retaining pond, indicated that gasoline vapors within tributary storm drains were at 100 percent of the LEL. Inside the 550-room high-rise hotel, however, the vapors weren’t sufficiently concentrated to justify evacuating the guests.
At 5 a.m. on November 23, the fire department incident commander released the incident to the Orange County Environmental Management Agency, which would oversee the $2 million clean-up for the next several months.
Personnel from San Diego Pipeline Co. installed a pump near the upper dam to protect both dams from water saturation failure. And to avoid further pollution over the following days, 3,500 gpm of water were pumped from the upper pond, through a mile of 12-inchdiameter, above-ground pipe laid for the purpose, past the lower pond, and back into the creek. IT Corp. crews removed the half million gallons of gasoline from the retaining pond, washed creekside vegetation with high-pressure water streams, and removed all contaminated soil.
The State Fire Marshal’s Office pinned the sudden failure of the 24-year-old pipe to a manufacturing defect in the weld seam, and has issued safety recommendations that will cost the company $10 million to implement. The San Diego Pipeline Co. has been fined $100 for a criminal misdemeanor under the state Fish and Game Code. Civil actions have resulted in judgments requiring the pipeline operator to reimburse the Orange County Fire Department $25,000 for its costs and all other agencies a total of $30,000.
Since the accident, San Diego Pipeline has installed two 16-inch automatic checkvalves to prevent backflow in the event of a future rupture. A new state law requires pipeline companies to provide local fire departments with clear, plastic overlays showing the location on their underground pipelines. The State Fire Marshal’s Office estimates that if these had been available at the time, the pipeline operator would have received notification 27 minutes sooner.
The same office provides a pipeline guidebook to each fire department in the state, identifying flammable characteristics of every piped commodity in the state, listing the emergency phone numbers of all the pipeline operators, and describing the U.S. Department of Transportation guidelines for managing leaks, spills, and fires.
Although federal law requires pipeline operators to establish a liaison with emergency officials, it doesn’t specify how often they must train together—and those involved in the Orange County incident hadn’t in quite a while.
Despite that problem, all parties concerned, including San Diego Pipeline, were extremely cooperative, and as a result, the environment is now rapidly returning to its original, natural state.
Lessons Learned
Reexamined:
Gasoline is no less hazardous for being familiar. The usual precautions are necessary, such as SCBA and decontamination.
Fire departments should plan ahead for pipeline spills by having map overlays and telephone contact numbers, and by training with pipeline personnel. Prompt notification of pipeline operators can prevent thousands of gallons of product from entering the environment.
Whenever practical, a simple impoundment dam is the preferred method for containing gasoline, which may have water-soluble benzene derivatives, within a stream bed. An underflow dam is acceptable when an impoundment dam isn’t practical and for containing spills of insoluble paraffin compounds (crude oil, for example).
Reinforced:
A fire department can respond together with the military, police, other public agencies, and private industries in a unified command.
A spill of gasoline into a waterway usually requires a threepronged strategy: eliminating ignition sources, controlling the flow of product from the pipeline, and intercepting the leading edge of the spill. Evacuation may also be required.
When vapor concentrations become a problem, foam can suppress production of vapors, and water monitors directed slightly downstream may be able to create enough air turbulence to disperse them.
Firefighters should leave haz-mat clean-up to professionals in that field. It’s the responsibility of the owner or shipper of the product spilled.
