Homemade Bomb Found at Ariz. Power Plant
A make-shift explosive device found last week at a power plant south of Tucson, Ariz., caused a small, temporary fuel leak in a 50,000-gallon distillate oil tank—not a large explosion as previously reported in initial accounts.
However, the incident has triggered investigations by the FBI, the U.S. Bureau of Alcohol, Tobacco, Firearms, and Explosives, and the Arizona Department of Public Safety.
Nogales police Lt. Carlos Jimenez told reporters the “crude incendiary device that could fit in a person’s hand” was placed under the valve of the diesel tank and ignited, but “failed to compromise the tank.” UniSource confirmed that the plant continued to be functional and no services were affected.
No injuries resulted from the incident, and there are currently no suspects. But “they were able to gain access to the facility illegally,” Jimenez said. “They had some working knowledge of what that tank is or how it works.”
UniSource Energy Services’ 63-MW Valencia Generating Station in Nogales, Ariz., is a 1988-built peaking facility. The plant comprises three Hitachi MS 5001 M-series combustion turbines rated at 13.5 MW each and one General Electric LM2500 rated at 23 MW. Each of the combustion turbines can be fired with piped natural gas or distillate oil, which is stored onsite in two 50,000-gallon storage tanks.
According to Nogales police, the plant is considered “critical infrastructure.” If the incident had resulted in a catastrophic explosion, as many as 30,000 customers could have lost power, Jimenez said.
The FBI is meanwhile reportedly also investigating past incidents in the region, including one in which “someone was reported to be trying to cut power lines,” the Arizona Daily Star reported last week, citing law enforcement officials.
In April 2013, 17 transformers were knocked out in a much more sophisticated attack on Pacific Gas and Electric’s Metcalf substation in south San Jose, Calif., in which multiple attackers fired as many as 150 rounds from high-powered rifles at the facility. Repairs at the substation took almost a month, and no arrests have been made in connection to the incident.
But since that attack, Congress has increasingly pressured the Federal Energy Regulatory Commission (FERC) and North American Electric Reliability Corporation (NERC) to act on risks posed to the bulk power system by physical security threats and vulnerabilities.
On March 7, FERC directed NERC to develop standards to require owners and operators of the bulk power system to take at least three steps to protect physical security: To perform risk assessments of their systems, evaluate potential threats, and develop and implement security plans to address potential threats.
NERC is expected to propose those standards this month.
—Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)