Killer Currents : LOS ANGELES RIVER CHALLENGES SWIFT-WATER RESCUE TEAM

The deluge that dumped as much as two inches of rain in an hour on parts of Los Angeles in the last week also led to several dramatic rescues from floodwaters, recalling the 1992 death of 15-year-old Adam Bischoff in the raging Los Angeles River. Since the death of the Woodland Hills youth, swift-water rescue procedures have improved, and ongoing training in Los Angeles city and county fire departments has intensified.

Gear

Swift-water rescuers are outfited to deal with slippery concrete surfaces and cold water.

Saving a life

The rescue depends on the situation--a victim injured or weak from hypothermia can’t grab a thrown flotation device, making the rescue more difficult.

About 85% of Los Angeles River rescues are shore-based, which requires rescuers to either go into the water to grab a victim, throw a flotation device or use a rescue net. Helicopters are used only as a last resort. Both fire departments are testing the use of fast, small water craft like jet skis

Curtain Rescue:

Rescue curtain is strung across river at about a 60-degree angle to prevent drag. At least two rescuers stand on each shore, holding ropes attached to curtain bottom. Curtain slides on top rope, which is anchored to shore, as rescuers pull bottom ropes to position curtain near victim. Curtain acts as net, entangling victim who may be too weak to grab.

Curtain: Made of 1-inch nylon webbing with 2-inch border, strength to 4,000 pounds. Size is about 6x20 feet, with 12-inch diameter holes.

Bridge rescue: Spotter stands on upstream side of bridge, tells whether victim is moving “river right� or “river left.� Two rescuers on downstream side hold 25 feet of inflated fire hose by two ropes, dropping hose into water as victim approaches.

Mapping a Rescue

Dispatchers with the L.A. City Fire Department have a Los Angeles River map programmed into their computers giving width, depth and length of the river along certain stretches. Given the victim’s location and speed of the river’s flow, rescue units are deployed to points downstream from the victim.

Specifics from a section of map from Calabasas Creek to Sepulveda Flood Control Basin, a distance of 5.5 miles:

Channel width: 70 feet to 120 feet

Channel depth: 18 feet to 27 feet

From Reseda Boulevard to flood basin: Would take victim 9 minutes, 27 seconds to float 1.75- mile distance at average peak flow of 11 m.p.h.

Obstacles

Strainers: Firefighters call river obstructions “strainers.� Strainers--rocs, trees, furniture or fencing--are dangerous in rescues because a victim or rescuer can get caught in them and drown.

Force of Water: Fast-moving water can quickly sap a victim’s strength. It takes 300 pounds of pressure for a victim to extract himself from a strainer in water moving 9 m.p.h. The force of water moving 30 m.p.h. is about 1,600 pounds per square inch.

River Dynamics

For most of its 58-mile length, the Los Angeles River is concrete with sloped walls. The most dangerous spots are where there are drop in elevation and vertical walls

Sloping walls: Angle of river walls varies from 30 degrees to 90 degrees. Small parts of the river bottom are natural but for most of tis length the bottom is concrete, which is difficult for victim or rescuer to hold onto.

Vertical walls: There are spots where the river drops in elevation, forming a small waterfall that leads to a narrow channel. Water passing through this channel churns rapidly, causing a “hydraulic effect,� where the current reverses and recirculates over the same area. Firefighters call this area a “death trap� or “drowning machine� because it is nearly impossible for a victim to escape.

Hypothermia

Hypothermia can occur even during warm months, but it is hastened with cooler air and water temperatures. Hypothermia weakens muscles and slows heart rate, which may stop if body temperature falls below 90 degrees. The L.A. River averages about 50 degrees in the winter. Below is a chart estimating how much useful work a rescuer can accomplish at varying temperatures and how long it takes to become unconscious:

Temperature: Useful Work: Unconscious

40 degrees: 7.5 minutes: 30 minutes

50 degrees: 15 minutes: 1 hour

60 degrees: 30 minutes: 2 hours

* Sources: Los Angeles City and County Fire Departments, The American Medical Assn. Encyclopedia of Medicine; Research by JULIE SHEER / Los Angeles Times