Making a Difference 1 Making a Difference Hand Crew Utilization on a Wildland Urban Interface Fire Tim Walsh-Marin County Fire Department Valley Fire-Introduction Often we work our entire careers hoping we will be at the right spot to make a difference. To make a rescue or be at the right place at the right time to save a structure from the devastation of fire happens only if you are at the intersection of opportunity and luck. Many of those that experienced the Valley Fire were not lucky. The fire burned 76,067 acres with 1958 structures destroyed within its perimeter. There were four civilian fatalities and four firefighters badly injured. For those individuals and family members that suffered, we are truly sorry. The Marin County Fire Department’s Tamampais Fire Crew found themselves at the intersection of opportunity and luck that made a difference for a few homeowners during some of the worst wildland fire behavior ever experienced. Marin County Fire Department’s Tamalpais Fire Crew performs a firing operation at the Valley Fire on September 13. Picture by Stephen Lam-used by permission under copyright. Valley Fire-Exposition Prior to the fire’s ignition, conditions were ripe devastation. Conditions reached a critical point of dryness that is seldom seen. The relative humidity plummeted into single digits during the week prior to the fire and on September 11, the day before the fire, the average relative humidity was only 10 percent over a 24-hour period (Figure 1). Figure 1: Chart of 24-Hour Average Relative Humidity from the Konocti Remote Automated Weather Station days leading up to the Valley Fire. The red circle represents the day the fire started. High temperatures were also part of the drying process peaking at 101 degrees on September 11. The combination of high temperatures and very low humidity created critical fuel moistures throughout a 24-hour period. There was no decrease in fire behavior with nightfall due to the lack of overnight humidity recovery and lower temperatures (Figure 2). Figure 2: Chart of 24-Hour Average Temperature from the Konocti Remote Automated Weather Station days leading up to the Valley Fire. The red circle represents the day the fire started. Making a Difference 3 Fuel moisture drives the fire behavior outside of wind. When fuels are critically dry, the fire will burn at such high intensity that it will create its own weather. As rising currents from a convective column draws air inward and upward, they can produce significantly powerful winds. Critically dry fuel moisture will also allow spot fires to ignite and grow rapidly based on the probability of ignition. The probability of ignition is a ratio of the number of embers that will fall out of the convective column and ignite spot fires. From September 8 through September 12, the probability of ignition averaged 90 percent in unshaded fuels. This means that 90 out of 100 embers that landed in a receptive fuelbed ignite and continue to burn, allowing the fire to expand at an accelerated rate. As aforementioned, the temperature was high, the relative humidity was low, and the probability of ignition was at a critical level. The missing ingredient for a fire to grow at a level that will escape control is wind. The winds surfaced during the afternoon of September 12 allowing the fire to expand and grow at an explosive rate. At 1300 hours, the ten-minute average wind speed was 14 mph. By 1700, they peaked at 24 mph and only slowed to 8 mph by 2300 hours. During the same time period, wind gust were 22 mph at 1300, peaked at 36 mph at 1700 and slowed to 17 mph at 2300 (Figure 3). These conditions allowed the fire to escape initial attack and become the third worst fire based on structure loss in the history of the State of California. September 12 Wind Speeds 40 34 36 30 27 30 30 22 28 20 20 24 25 18 20 21 14 18 19 10 Avg Wind 15 15 17 Wind Gust 0 9 10 8 Figure 3. Chart of the average and gust wind speeds for September 12, 2015. Data is from the Konocti Remote Automated Weather Station. Valley Fire-Development The Valley Fire started on September 12, 2015 at 1324 hours1 near the community of Cobb in Lake County, California. The initial report stated that the fire was approximately 2 acres in size burning with a moderate rate of spread. According to a CALFIRE Press Release, by 1350 hours, the fire was 50 acres in size. By 1359 hours, the community of Cobb is under evacuation orders. At 1410 hours, there is a report that four firefighters from CALFIRE Helicopter 104 have been burned and were being flown to a burn center. At 1427 hours, a very large air tanker capable of dropping 12,000 gallons of fire retardant was dispatched to the fire indicating that the fire was burning faster than a moderate rate of spread. By 1456 hours, the fire had grown to 200 acres as reported by the air attack supervisor resulting in a rate of spread of nearly two and a quarter acres per minute giving an indication of what was to follow. At 1503 hours, the fire had grown to 400 acres resulting in a rate of spread of over 4 acres per minute2. At 1648 hours, the fire has reached the community of Harbin Hot Springs 7 miles from the point of origin. At 1715, the Air Attack Supervisor recommends evacuating the community of Middletown, which is eight miles away. An updated CALFIRE press release states that the fire is 10,000 acres by 19:30 hours, which would equate to a rate of spread of 42 acres per minute. By 2221 hours, the fire is reported to be approximately 25,000 acres equating to over 46 acres per minute of fire growth. By 0125 hours the next morning, the fire was flown using an infrared sensor with an unbelievable growth of 45,000 acres since the time of ignition 11 hours previous. This would equate to 68 acres per minute of fire growth! 1 All times were provided by CALFIRE Division Chief Linda Green Sonoma-Lake- Napa Unit 2 This information was obtained from the website www.wildlandfire.com. Making a Difference 5 Valley Fire-Recapitulation Marin County Fire Department’s Tamalpais Fire Crew (TFC) was dispatched to the Valley Fire on September 12, 2015 at 1530 hours. The TFC is a 14-person hand crew that responds to several initial attack fires throughout the Bay Area and other parts of the state under agreement with CALFIRE and the United States Forest Service (USFS). Although this is the 11th year of operation of the TFC, this fire would place them in harm’s way and provide an opportunity for growth like no other. The smoke column could be seen like many others that were visible from Marin as Lake County experienced a very long summer of large fire activity. As the crew vehicles dropped down the grade east of Calistoga, pine needles were pelting the vehicles from the gusting winds funneled up Highway 29. At the bottom of the grade, the smoke column made you want to stop and take note. It was two distinct columns coming from the same place. One of the columns was laid over as if pushed by a strong wind, the other stood straight up as if it was not influenced by the same wind (Figure 4). The TFC reported that they were entering the Sonoma- Lake-Napa Unit and the Saint Helena Emergency Command Center told them to report to staging at Jellystone Park off of Bottle Rock Road. The drive would take them down Highway 175 paralleling the fire that was now burning along a ridgeline with reckless abandon. Trees standing alone were torching while stands of trees were burning through the crowns consuming the ridge. The brush was burning with 40-60 foot flame lengths consuming acres in seconds. Figure 4: The smoke column from the Valley Fire as seen from Spot fires could be seen the intersection of Highway 175 and Highway 29. Note the two different influences as part of the column is being pushed by everywhere as embers were the wind while the smoke in the background is standing flying in every direction. This straight up. was not going to be an everyday fire! As the crew vehicles reached Whispering Pines, it was obvious that this fire was going to affect several communities in a negative way. Fire engines were parked in yards as flames were coming off the ridge and into the community. It was difficult to follow directions and not stop at an unprotected home and try to help out. The crew continued to the staging area trying to focus on the road and not the life-altering firestorm that was building before their eyes. As the TFC pulled into the staging area, they were very much alone. There were two USFS bulldozer transports and nothing else. At this point, it felt like we should have just found a house to protect rather than wasting time sitting in a staging area. Several minutes later, a CALFIRE Strike Team from the Mendocino Unit pulled into the staging area followed by another one from the Santa Clara Unit. Everyone was antsy as no one likes to sit around when you know structures are burning. Radio traffic was nonstop and frustration was building as everyone was trying to talk at the same time. Finally, there was a request that everything in staging should head to the community of Hidden Valley Lake.