As he started to deal with the leaky valve, he noticed that below him were several open vats of molten glass.
Although he wanted to have the fires doused before he tried to shut off the valves, company officials told him it would cost $1 million to clean each vat as the glass solidified.
So Lopez, dressed in a body suit that protected him from the toxic chlorine but not the open vats below him, did what he does for a living -- he shut off the broken valve and stopped the chlorine leak.
Then there was the time about a year ago, when Lopez had to dispose of two containers filled with an Agent Orange-like substance found on a road between Lodi and Stockton.
Those kinds of situations are just part of Lopez's job as a specialist with the county's hazmat team.
While Lopez and a team work with hazardous materials in the county's unincorporated areas, other teams deal with the same dangerous substances inside city limits.
Those teams are part of the county's efforts to address possible terror threats -- a direction partly born from the events of Sept. 11, 2001, but also started before that day, said Tim Hall, an engineer with the Stockton Fire Department.
Hall and Lopez were members of county and city agencies that showcased their ability to protect county residents on Wednesday at the Lodi Grape Festival grounds.
From the central command area operated by the Lodi Police Department to Woodbridge Fire Department's decontamination showers, the display showcased a variety of equipment either purchased through Office of Homeland Security grants or by individual cities, said Ronald Baldwin, director of the county's Office Emergency Services.
There are only two decontamination showers in the county, one in Woodbridge, and the other in Ripon, said Capt. Steve Butler of the Woodbridge Fire Department.
Although the shower hasn't been tested yet, Butler said the self-contained units can clean up to more than 400 people per hour that have been exposed to some type of chemical agent.
Unlike a home shower, the portable decontamination unit emits a spray of what Butler called a "decon" solution, and a spray of water.
While most of the equipment displayed Wednesday had been purchased through the Homeland Security grant program, Butler said the residents of Victor, Lodi, Clements and Woodbridge raised enough money to buy the decontamination equipment.
Hall said his camera is designed to read a hot zone, such as a plant leaking deadly chemicals. The real-time camera allows the plant manager to see what's going on below and to direct a crew on what valves to turn or not turn in case of an emergency, Hill said.
Plant engineers can also use the camera to get a better view of any structural damage in the case of a building collapse, Hill said.
When Officer Dale Miller of the Lodi Police Department gets called in, it's usually to defuse a bomb, check a suspicious package or deal with some kind of chemical.
Miller said that with his lightweight bomb-checking suit and his disruptor, a water cannon, he can open an end cap on a potential pipe bomb with a burst of water.
The disruptor, which looks innocent enough with its long, silver pipe, is on loan from the FBI, Miller said.
The nerve center of all this is the command center, operated by the Lodi Police Department, said Stan Sogti, a five-year volunteer with the department.
What looks like a large, white horse trailer is really the place where all communication and coordination comes together in the event of a countywide emergency, Miller said.
The trailer is equipped with a communication center that allows discussions between any fire or police department in the county, and allows emergency personnel to know what's going on at any time.
There's even an interrogation room for use during hostage crisis negotiations, Miller said. The room is padded enough to keep out most outside noise, he said.