Controlled Burns : The Prescription for Fighting Fire Disaster

Controlled burning of wildland brush is often misunderstood by present-day Southern Californians, who can’t see past the smoke it creates and the land it blackens. Native Americans burned land to improve hunting, create travel routes and rejuvenate succulent vegetation.

Firefighters today closely-monitored prescribed burns to renew plant growth, enhance wildlife and prevent huge fires. Prescribed burns also are used to train firefighters and study fire behavior.

The Los Angeles County Fire Department currently has 13 sites that are under study for controlled burns. But because of weather restrictions, only eight burns have been conducted this year-all on a site in the Santa Clarita Valley-totaling a mere 100 acres. More than a dozen controlled burn days have been cancelled because of high temperatures and / or low humidity, a dangerous combination for keeping a fire under control.

Controlled burn specialist Don Pierpont, a county fire battalion chief, calls the burns complex, “choreographed” events. They require months of detailed planning. Each controlled burn project ha its own “prescription” listing ideal conditions for burning and a burn plan detailing how the burn will be conducted.

From Proposal to Action Recommendations for a controlled burning site come from area fire stations, as well as residents. Then the site must get approval.

Area homeowners are sent a map drawn by fire department vegetation management officials.

Environmental impact studies are done to ensure the safety of endangered or threatened species, and archaeological research determines the existence of any important areas such as ancient burial grounds.

Fire officials then write a “burn plan” detailing how the burn will be done-- including the number of acres to be burned and personnel needed. Final approval comes from the California Department of Forestry.

The burn contract is good for three years--a controlled burn can occur there within that time, dependent on the right conditions.

Preparing A Burn Site

Containment lines are cut by hand crews or bulldozed

Samples of vegetation are taken and analyzed for moisture content

IDEAL CONDITIONS

Once a burn plan is OK’d, fire officials must wait for a window of opportunity when weather and vegetation conditions are optimal for burning. High temperature and wind, coupled with low humidity can cause a fire to get out of control. The best times for controlled burns are in the spring and immediately after winter rains.

* Temperature: 70-75 degrees

* Wind: 7-10 m.p.h.

* Humidity: 35%

* Fuel moisture: 90%

The Day of A Burn

Pre-planning: The fire department obtains the following day’s weather and air quality forecasts. If acceptable, all divisions involved are notified, as well as area residents.

7 a.m.: Supervisors meet to review plan, go over topographical maps. Spot forecast is obtained from weather service. Weather balloon is launched and tracked to determine wind speed. Small corner of area is ignited to test how it will burn.

9 a.m.-noon: Various sections of burn area are lighted in sequence.

Noon-5 p.m.: Fire is allowed to burn within limits--usually 30-foot flame lengths. Smolders are doused by engines or helicopters to prevent spot fires.

Overnight: Several firefighters keep watch to make sure embers don’t start spot fires.

Next day: Two crews put out any remaining smolders.

Before and during burn, weather balloons are released and tracked to determine wind speed and direction of smoke. *

Setting Headfires Once backfire has burned about 150 feet, smaller headfires are set, which are pushed by wind to meet main backfire.

*

Controlling the Direction Firefighters armed with hand tools are stationed at fire’s perimeter to keep fire from jumping prescribed line. Engines are nearby in case fire jumps containment line. *

Setting A Backfire A backfire is set downwind from a firebreak such as a road or creek. It is intended to burn slowly and creates a “blackline” at which headfires will stop.

Sources: AQMD; Los Angeles County Fire Department; National Park Service; “Fire: A Force of Nature”

Fires are started using drip torches-the principal method-a canister from which gasoline is squirted; terra torches, which shoot flaming gel up to 100 feet; helitorches, aerialtanks attached to helicopters that pump jelled gas from the air; or small plastic balls filled with a flammable substance dropped from helicopters.

Sources: Los Angeles County Fire Department; National Park Service; Nature Conservancy; * “Fire: A Force of Nature”; Researched by JULIE SHEER / Los Angeles Times