LANL - New Mexico30 April 2001
The Cerro Grande Fire began as a prescribed burn and ended up as a worst-case scenario for Los Alamos National Laboratory (LANL).
Over 7600acres within LANL and an additional 35,500acres in neighbouring areas were burned in last year’s Cerro Grande Fire. On 4 May employees of the National Park Service of the Bandelier National Monument ignited a prescribed burn in a forested area along a slope of the Cerro Grande. On 5 May the National Park Service declared the fire to be a wildfire after it had been pushed outside the prescription area by winds.
Shrubs and trees were cut and back fires ignited in an attempt to hold the fire line at New Mexico State Road 501 located at the northwestern side of LANL. On 10 May the wind speed increased dramatically, reaching speeds of up to 100km/h, and spread embers well beyond the fire lines, igniting forested areas within the heart of LANL.
The fire burned within LANL and the nearby town until 22 May, when it was considered to be contained. In addition to the 43,000acres of forest, over 200 residential units within the Los Alamos townsite had burned.
LANL itself suffered considerable damage and disruption. Some infrastructure, especially its electrical utilities, as well as over 100 structures were damaged. The fire caused an unprecedented suspension of operations as its 12,000 staff were unable to work for a two week period. Despite the intensity of the fire no major facilities were damaged, nor was there any release of hazardous materials. Also surprising for this scale of event – the second largest recorded wildfire in New Mexico – there were no serious injuries or lives lost.
As a result of the wildfire the DoE, who administer LANL, took emergency protective and post-fire recovery action. The DoE emergency action was aimed at protecting not only the lives of its employees, contractors, and subcontractors, but also the lives of all people living and working in the LANL region. This meant that the 20,000 residents of the town had to be evacuated. The action also aimed to protect properties of neighbouring and downstream landowners and residents, as well as that belonging to the US government.
At the peak of the firefighting efforts, a total of about 1600 firefighters and 100 pieces of firefighting equipment were present in the LANL vicinity. Trees close to buildings, structures and access roadways were felled to remove the fire’s fuel sources near these areas. To control the fire’s advance, firefighters constructed numerous narrow fuel breaks. Once these had been established several back fires were ignited where conditions were favourable. Helicopters were used to drop water on the fire, and airplanes dropped fire-retardant slurry on the forest ahead of the fire front.
After the fire
Once the fire had been brought under control the extent of the damage was not fully understood. At the same time there was still a high danger of isolated fires breaking out. Post-fire actions included monitoring and assessment; establishment of staging areas; removal and stabilisation of contaminants and other hazardous wastes and materials; erosion control; and storm water control.
The priority for site managers was to bring LANL facilities to a safe working condition. For all structures they carried out safety reviews and condition assessments, implementing repairs where appropriate. Unless more extensive work was needed, structures were declared “facility ready”. Actions were carried out while working closely with the DoE and all steps were systematically documented.
A total of 40 structures were damaged beyond reasonable repair. These were removed using conventional heavy equipment, such as front-end loaders, which resulted in some soil disturbance. If recyclable materials could not be segregated, all waste was disposed of according to standard LANL waste management practices.
Various flood damage control measures were installed and work to re-establish vegetation to reduce soil erosion was carried out. This included contour tree felling over about 750acres, installation of on-grade rock and log check dams, placement of erosion control jute matting, and placement of straw bales and wattles. Silt fences were installed to protect the site from storm water runon and runoff until seedlings were established. Moderately and severely burned areas were contour raked to break up the soil surface and to redirect and reduce water flow. About 1000acres were raked, seeded and mulched, a third of which was carried out by hand and the rest by aircraft. This work was begun in early June and completed in August by professional recovery teams, assisted by LANL worker volunteers.
In an area above the criticality facility US Army Corps of Engineers put up a 120,000t roller-compacted concrete flood and sediment retention structure. An area of about 250m by 150m was cleared for the 21m high and 117m long structure. Constructed erosion and water control structures are expected to remain in place for three to perhaps as many as ten years.
Other measures aimed at reducing risk included moving containers with radioactive and hazardous materials and waste to higher ground. To reduce the threat posed by a future fire approximately 8000acres of forested LANL land are being thinned.
Of the more than 2000 structures at LANL, more than 80% were made facility ready within two weeks of chartering the LANL Facility Recovery Centre (FRC). The FRC carried out verification of facility authorisation status, condition assessment, and recovery planning. The FRC staff, including DoE, developed processes for a graded approach for approvals based on facility type and hazard. This allowed very rapid safety reconnaissance, condition assessment and declaration of readiness for almost all of the undamaged office and low hazard facilities. This is the only example of facility recovery from a site emergency condition within the DoE complex.
The Cerro Grande Fire had a number of far-reaching consequences. The most immediate effect can be seen around the forests and LANL. The burned area will have lasting effects on vegetation and habitat. Although a tragic event, we have learned from the Cerro Grande Fire that fuel load reduction in the past few years at LANL, was effective in controlling the damage that occurred during the event.