A torrential downpour flooded streets and highways with mud, rocks and debris throughout the San Bernardino Mountains late in the day on Monday, Sept. 12. One such mud flow triggered by a burst drainpipe resulted in as much as four feet of mud and debris at the site where Highway 18 caved in last Christmas Eve in lower Bonnie Canyon.

Asked how such an event could happen following a months-long closure of the downbound lanes of Highway 18, Caltrans Public Information Officer Emily Leinen said, “There was a large amount of debris and boulders tumbling down a very steep slope above the roadway and water coming from all directions and rushing beneath the pipe. It snapped, possibly after being struck by a large boulder,” she said, adding that flooding and mud flows were occurring all over the mountain, in the Narrows and on Highway 138.

When asked whether an underground pipeline would be more effective, Leinen replied, “We do our best, but an underground pipe would still experience erosion. This was an unprecedented summer storm and you can’t stop Mother Nature.”

Leinen added that Skanska, the original contractor on the project, is responsible for fixing the problem. “Skanska said the work would be completed in the next few weeks. The repair should be quick, but we will likely have to close one lane and have flagging like before.”

Repeated attempts to contact a Skanska spokesperson to find out when repairs would be started and completed were unsuccessful. However, one employee told The Alpine Mountaineer on Sept. 15 that employees are not permitted to talk to the media.