Larry Collins reports on the hazards faced by Southern California firefighters when floods and mud and debris flows follow wildfires. Four years after deadly fire storms swept across Southern California and burned thousands of homes, it happened again. In October and November 2007, an unprecedented...
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On the same day, another large mud and debris flow struck a KOA campground near Devore, stranding 54 people and killing two victims. This area had also was below the "Old" and "Grand Prix" fires' burn areas, and the steep slopes were deep in ash and debris. At least one would-be rescuer (an insurance company claims adjuster who was in Southern California to help assess losses from the firestorms) died while attempting to help children he thought were in a trailer that slid down a hill.
Ironically, a multi-agency Burned Area Emergency Response (BAER) team, assembled to survey slope damage and potential for floods and other problems after the 2003 firestorms, had identified 30 main trouble spots where drainages were almost certain to produce significant mud and debris flows. The Devore campsite and Waterman Canyon had been noted as locations posing a high risk to life and property. At some of those sites, the BAER team had suggested ways to reduce flood danger, such as placing sandbags and digging ditches. But the danger at the Devore campsite was so severe that the team recommended evacuation during storms.
At the same time San Bernardino County firefighters were fighting their way into the disasters in Waterman Canyon and Devore, the storm was hitting the San Gabriel Mountains in Los Angeles County and a similar mud and debris flow emergency was developing in the foothills of Clairemont, which marked the western end of the Grand Prix Fire burn area. Fortunately, this one was less deadly. As part of the Los Angeles County Fire Department (LACoFD) augmented Storm Deployment, a combination of swiftwater rescue teams and urban search and rescue (USAR) units strategically located across the county during major storms, USAR Task Force 103 (USAR-TF103) had already been dispatched on a Code R move-up to Fire Station 62 in Clairemont because the storm was causing mud and debris flows to occur in multiple locations, including mudflows that inundated the interior of that fire station.
In the midst of a number of simultaneous water rescue and mud-and-debris flow emergencies that began breaking out with the heavy downpours, LACoFD Engine 101 Captain Bill Masten radioed "Emergency Traffic" and reported people trapped by mud and debris flows in homes and at least one vehicle where Clairemont meets the steep mountain slopes. He requested USAR-TF103 to assist with the rescue of the motorist, which was conducted by personnel wearing swiftwater personal protective equipment (PPE), including dry suits. Then the two units worked with a unit from the U.S. Forest Service to rescue a pregnant woman and her young son from a vehicle trapped by another mud and debris flow.
At this point, USAR-TF103 was assigned to the "Baldy Branch" of the rapidly expanding incident where residents were being evacuated with assistance through mud and debris coming down from the mountains, with direction to establish a rescue plan, assign upstream lookouts to warn of additional mud and debris flows coming down-canyon, and to have a rapid intervention plan in place for all department personnel working in the danger zone. Citizens were safely evacuated from impacted neighborhoods, and LACoFD personnel, including the Heavy Equipment Section and several camp crews, attempted to divert the flows with sandbags and front-end loaders, and used jackhammers to breach retaining walls to let water and mud drain from homes and properties.
These are just samples of the havoc that mud and debris flows can wreak. And then there are the deadly mudslides that are closely related to mud and debris flows because they often happen under similar weather conditions and under similar circumstances of steep unstable slopes, saturated soil, and sometimes after large wildfires. The history of Southern California and other mountainous wildland zones is replete with major mud- and water-related events that help define the terrain and the places people choose to live.
One infamous town familiar to many readers is La Conchita along the 101 Freeway in Ventura County. In 1889 and 1909, parts of the 600-foot-high cliffs overlooking La Conchita collapsed, burying the Southern Pacific rail line that ran along the old Pacific Coast Highway. The later collapse buried an entire train.