A southern Californian home packed with explosives, bomb making equipment and ammunition is to be deliberately burned to the ground this week.

Firefighters, police and safety authorities have concluded that the controlled burn is the least risky way of dealing with the stash, which is believed be the largest amount of homemade explosives ever found in one location in the US.

Residents within a half-mile radius of the house in the Escondido district – around 30 miles from San Diego – have been put on 24-hours notice to evacuate their homes, with those further away being given instructions on how to shelter in their homes. The burn is tentatively set for tomorrow (8 December), Thursday or Friday and is subject to favourable weather and wind conditions.

The Governor of California, Arnold Shwarzenegger, has declared a state of emergency for San Diego county.

Meanwhile in a San Diego federal courtroom yesterday, the man who rented the house, George Djura Jakubec, 54, pleaded not guilty to eight charges relating to bomb making and bank robbery.

While firefighters are optimistic that the fire will not spread to other homes, they have positioned hose lines as a precaution. Surrounding trees and brush have been cleared and a wall erected to help protect neighbouring homes from radiated heat. The wall and surrounding houses will also be sprayed with a protective gel.

Experts believe that most of the materials in the house will burn and decompose within half an hour, and that ammunition is unlikely to strike any potential hazards, but residents have been told to plan for an evacuation lasting a whole day.

“This is a truly unknown situation,” Neal Langerman of San Diego safety consulting firm, Advanced Chemical Safety, told the Independent newspaper. “They've got a very good inventory of what's in there. Do I anticipate something going wrong? No. But even in a controlled burn, things occasionally go wrong.”

Authorities were alerted to the hazard last month, when a landscape worker was hurt in an explosion at the house. During a subsequent search of the premises, more than nine pounds of HMTD (hexamethylene triperoxide diamine) was discovered and secured. Many additional solvents, acids and precursor to explosives were also found.

Recovery efforts were then halted due to the large scale of hazardous materials. Because of the large amount of clutter in the house, using a remote controlled robot to make the site safe was also ruled out.

As part of guidance to local residents, a statement on the San Diego County government emergency website said:

“There is so much clutter in the house, the Sheriff’s bomb/arson unit robot can’t go in. There’s also residue on the floor so bomb/arson technicians with heavy gear can’t safely operate. It is the consensus of all the bomb technicians on scene, experts from the FBI Laboratory, explosives unit and Hazmat technicians on scene to render the hazardous materials by burning it in place.”

San Diego County government emergency website