Workers With A License to Blast
District 7 maintenance workers who specialize in blasting rocks
[Click on photos to read captions.]
The target has been identified, the holes have been bored, the charges are set, and the area has been cleared. Now it’s time for the rock to come down. The blast alarm is sounded and finally the blaster yells, “Fire in the hole!” The blasting caps begin to explode in sequence, and down comes a boulder or several pieces of rock along the roadside.
Now this might sound like something you have seen on a television special about mining or in a Hollywood war movie, but no, it is District 7’s blasters at work.
Maintenance Superintendents Patrick Porteus and Ed Toledo, and Supervisors Don Niles, Eric Jakab, and Mark Morris are Caltrans trained and licensed blasters.
Each of the blasters have had numerous experiences helping to remove rocks that posed a threat to the safety of motorists on highways and freeways throughout the District.
The most recent blasting operation took place at post mile marker 55 along the Antelope Valley Freeway (SR-14) on January 30, 2010. The southbound side of SR-14 was shut down early in the morning for the operation.
To see a video of the SR-14 blasting operation, click here.
As with all things at Caltrans, safety is the top priority. After the rock climbers (Jakab and Porteus) scaled the hillside to bore holes and set charges, the blasters and shot guards (blasting assistants) ensured that there were no unsuspecting individuals in the area, then the countdown began. As with all blasting operations, alarms are sounded at five minutes, then one minute, 20 seconds, at 10 seconds total radio silence, with 3 seconds left then the person holding the shocker (detonator) yells “Fire in the hole” and holds the button down for three seconds and releases.
“There are many ways that we can set the charges to help us get the best bang for our buck,” said Jakab, a 10-year blaster, and a 17-year Caltrans employee. “We can place the charges in different patterns and use delay charges to direct where the rocks will fall and we can use charges that can crack the rock or heave the rock off the hillside.”
In 1998 a 75-foot-tall, 250-foot-long, and 35-foot-wide hill near the Mount Waterman Ski Resort was identified for blasting because water runoff was creating six-inch-thick ice on Angeles Crest Highway (SR-2). The ice created a slipping hazard for both skiers and motorists. Engineers said it would cost an estimated $1 million to remove.
“We purchased $10,000 worth of explosives and were able to solve the water runoff problem by flattening the hillside,” said Toledo, a 15 year blaster and 29-year Caltrans employee. “We were able to complete the job for a total of $80,000.”
To accomplish their duties, blasters use an arsenal of shock tubes filled with ammonium nitrate mixed with nitromethane, also known as blasting caps that weigh about a third of pound. “TNT is no longer used because of its short shelf-life, toxic fumes, and instability,” said Jakab. “Some of the explosives we use depends on the type of rock in the area, but we do not want rock flying everywhere.”
Obviously those performing blasting operations have to be very cautious and responsible people. Generally those who want to become blasters have to work as assistants for two to three years by performing flagging operations and working as shock guards. Once interested candidates have logged all of the prerequisite experience, they can then apply to go to blaster training in Kingvale, California in District 3.
“It is a blast, we have lots fun doing what we do,” said Toledo, fittingly summing up his blasting experiences.