Suppression Strategy on Corral Complex Changes to Direct Attack
Incident: Corral Complex Wildfire
Since Monday, there has been a shift in fire suppression tactics on the Corral Complex. Incident Commander Jeanne Pincha-Tulley said, “We have a chance right now to contain this fire quickly and keep it about 6,000 acres smaller thanks to the excellent work done by California Team 5. The indirect line they put in place gives us a contingency plan if our plan doesn’t work, but if the weather pattern holds, we have a very high probability of success with direct attack.”
During the two previous weeks, firefighters completed indirect fire line to the west and south of the fire by developing a system of cleared roads connected to bulldozer lines which were tied into the north containment line in order to hold the oncoming fire. This indirect strategy was chosen when the fire was moving rapidly in steep terrain under conditions that were too hazardous for direct attack. The next step using the indirect strategy would be firing operations to remove unburned fuel between the indirect line and the main fire.
However, with the indirect line completed, and mild weather forecasted until Friday, California Team 3 recognized a window of opportunity to use an alternative strategy which is likely to contain the fire sooner, limit firefighter exposure, increase public safety and reduce final cost. This alternative direct attack strategy will use hotshot crews, mass-delivery of water by air, and medical response contingency resources to mitigate the risk of working in the complex terrain of the Trinity Alps Wilderness.
On Monday, firefighters began an aggressive attack on the 26 miles of open line along the fire’s edge, while the last four miles of indirect line were still being completed. Type 1 helicopters dropped 250,000 gallons of water along the fire perimeter, reducing the fire’s heat and creating areas that firefighters can now safely enter to construct direct handline or mop up hot spots. Seven hotshot crews hiked into the northwest and west sides of the fire and are camping out near the fireline during this multi-day campaign.
On Tuesday, two airtankers began dropping loads of clean water along the perimeter; particularly on the south side where near vertical terrain continues to prevent the use of handcrews. Aerial water delivery along the fire perimeter is typically done to support crews working on the ground. Intensive use of water along an inaccessible fire perimeter without crews is not typical. In this case, aircraft will systematically deliver mass-loads of water along the perimeter, targeting pockets of heat, burning snags, and other areas of concern. Both water drops to support handcrews and spot-cooling along the perimeter are being used on the Corral Complex.
All firefighting strategies involve some level of risk which must be carefully weighed with risk mitigations and benefits.
The risks and mitigations associated with California Team 3’s current plan of direct attack are:
The use of fixed winged aircraft and helicopters increases exposure to aircraft hazards, but is mitigated through the short duration of use, limiting pilot flight hours, and other aspects of the aviation safety plan.
Trace amounts of retardant in airtankers could impact sensitive aquatic species, but is mitigated by doing initial drops on the ridge tops to avoid riparian areas and human drinking water supplies. Retardant is not being used in the wilderness, or on sensitive watersheds or cultural resources in the fire area.
Use of handcrews in steep terrain is mitigated by using highly experienced hotshot crews with short term exposure, cooling the fire’s perimeter with mass-delivery of water, and providing support with Rapid Extraction Modules and a hoist capable helicopter for emergency medical response.
A change in weather to hot dry conditions with a possible increase in wind or fire behavior, particularly an offshore east wind event which is more frequent in Northern California at this time of year, is mitigated by the contingency plan of using the indirect line and firing operations to contain the fire.
The benefits associated with California Team 3’s current plan of direct attack are:
Fire containment will be achieved more quickly.
A shorter duration fire will reduce firefighters exposure to risks associated with heat, smoke, hazardous mountain roads, snags, fatigue, and steep terrain.
Smoke impacts to communities will be reduced.
Fire suppression costs will be reduced.
The number of acres burned will be reduced.
Fire repair and rehabilitation costs will be reduced.
Using water without retardant will allow aerial attack both in drainages and on ridges, limiting fire spread from rolling burned material which has been a major contributor to fire growth.
Negative impacts to local traffic caused by fire equipment on the roads will be reduced.
Use of water rather than fire retardant will eliminate ecological concerns in riparian areas and protect wilderness values.
Use of water rather than fire retardant will protect the drinking water supply for the Hoopa Valley community.
Use of water rather than fire retardant will ensure effective firing operations if tactics must be changed in response to weather, since fire retardant makes it more difficult for vegetation to burn.