Tuesday’s seven-hour hazmat response to a chlorine spill in downtown San Mateo may have been cleaned up more quickly and officials — including San Mateo County Supervisor Jerry Hill — are looking into ways to prevent another time-consuming traffic backup.

“[County health officials] did say it took longer than expected,” said San Mateo Fire Chief Dan Belville.

On Tuesday, four containers of highly concentrated chlorine were spotted on Delaware Street between Ninth and Fourth avenues. Two of the unmarked containers leaked their contents onto the street, forcing a complete closure of the area until hazardous materials team could neutralize and dispose of the chlorine. The street closure caused the complete closure of the Delaware Street and Fourth Avenue intersection, causing traffic backups into downtown.

The cleanup process was delayed because the hazmat team did not have enough citric acid powder available to dilute the chlorine and because there were multiple spills in the area. Each spill requires team members to enter and exit under special precautions.

San Mateo Fire Chief Dan Belville is looking into the situation while Hill asks the County Manager’s Office to do an internal investigation of what took so long.

Hill, who described himself as “incensed” calls the incident “an extraordinary inconvenience.”

Hill said he “understands there were some problems” related to why the incident took so long to clear, but is not clear on what those problems were.

Belville, a former battalion chief in charge of the hazmat team, made a suggestion that a vacuum truck or absorbent be used in the future. A vacuum truck from the city’s Department of Public Works is commonly used to clear out clogged sewers and can also be used to suck up and contain spilled chlorine. Responders could also dilute or use an absorbent and then vacuum the chlorine, Belville said.

Regardless, the team acted by the books, said Jeff Norris, district coordinator for the San Mateo County Office of Emergency Services.

“The team did everything that is safely allowed,” Norris said. “It followed all proper procedures.”

The team had “a couple of factors working against” it, Norris said.

The chlorine has a 12.5 concentration, more than 10 times what would be used in the average pool. The chlorine is used to digest organic waste and it cannot be washed down a storm drain, Norris said.

The hazmat team neutralized the chlorine with citric acid. However, it initially did not have enough on hand to neutralize the highly concentrated chlorine and the team was forced to wait until additional citric acid was located, Norris said.

Once the citric acid is applied, it takes time to neutralize the chlorine, Norris said.

County officials and Belville are set to re-evaluate the incident again sometime next week.

Reporter Michelle Durand contributed to this report.

Dana Yates can be reached by e-mail: dana@smdailyjournal.com or by phone: (650) 344-5200 ext. 106.