AUTOMATIC SPRINKLER EFFECTIVENESS EVIDENT IN MINNESOTA SCHOOL FIRES
BY JON NISJA
Three large Minnesota high school buildings were damaged by arson fires during the last week of April 1994. All three schools were located in suburban Minneapolis/St. Paul communities. The first and most damaging of these fires occurred on Monday, April 25, 1994, at Burnsville High School. Four days later, on April 29, fires were reported during the early morning hours at two other high schools–Edina and Minnetonka. Fires at these schools, which are approximately 10 miles apart, occurred within minutes of each other.
All the fires demonstrated the effectiveness of automatic sprinkler protection. Although retrofitting existing school buildings with automatic sprinkler protection appears to be relatively uncommon nationally, our experience with these fires has shown that retrofitting is a good policy and an extremely effective defense against fire.
BURNSVILLE HIGH SCHOOL
The Burnsville High School is a sprawling two-story building and one of the largest high schools in the state of Minnesota. Constructed in 1955, major additions were made in 1977, 1978, and 1979. At the time of the fire, the building was approximately 413,000 square feet and housed about 2,200 students. Preliminary investigation revealed multiple points of fire origin, the most severe of which was the common area near the auditorium lobby and inside adjacent locker bays.
This area of the school was built of fire-resistive, noncombustible construction. Interior walls were primarily of brick construction; floors and floor-ceiling separations of the main story were concrete and prestressed concrete, respectively. The interior ceiling was finished with a decorative redwood material, which appeared to have a Class II (or Class B) flame spread rating as required by the code.
An additional fire appeared to have been ignited in a rear exit system adjacent to the auditorium stage; no communication between the fires was observable. Some form of liquid accelerant, which contributed to the rapid fire spread, appeared to have been used in all areas of fire origin. Once ignited, the fire spread to the decorative ceiling material, which contributed to the spread of the fire.
Initial notification was made to the police at 11:49 p.m. (April 25) through the transmission of an intrusion alarm to a central station-monitoring service. On arrival two minutes later, police officers observed extensive fire involvement and requested fire department response. Captain James Thune of the Burnsville Fire Department was the initial responding incident commander. En route, he observed a heavy plume of smoke from approximately one-half mile away. Thune provided the following description of fire conditions: “Upon arrival, flames were showing through the doors and windows of the single-story performing arts wing. The flames had already shattered the glass in the doors and windows, and flames were seen rolling up over the roof of the adjacent two-story section. We observed that the flames appeared to be totally charged deep inside the building and burning in a sizable, agitated manner.” The bulk of the fire was extinguished by an aggressive interior attack; however, high heat conditions were noted in the building following extinguishment. Salvage and overhaul operations took several hours to complete. Firefighting operations ultimately involved 90 firefighters from four other departments.
The majority of the building was not equipped with automatic sprinkler protection; however, sprinklers had been installed to protect the auditorium stage and the southern section (gymnasium area) as part of a remodeling project. The fire burned up to and activated the first four sprinkler heads in this section along with an additional seven sprinkler heads on the stage, activated by heat buildup within the higher stage area. The fire was stopped at the sprinklers and did not spread beyond these points. Total fire loss, virtually limited to the unsprinklered portions of the building, was estimated at from $7 to $8 million. The damage was extensive enough to cause the building to be out of service for the remainder of the school year. Classes had to be moved to other school buildings on split-shift scheduling (morning classes for some students, afternoon classes for others). Ironically, a bond referendum for facility upgrades, including a retrofit sprinkler project for this building, had been scheduled for a public vote the next month. The fire damage at this school was repaired in time for the September 1994 school opening; automatic sprinkler systems were installed.
EDINA HIGH SCHOOL
At 5:47 a.m. on April 29, maintenance personnel arriving for work discovered a fire in progress at Edina High School. This building recently had been upgraded with automatic sprinklers and a complete, fully addressable fire alarm system. The installation of the sprinklers was completed in 1993, and the fire alarm installation was in progress when the fire occurred (at the time of the fire, the digital alarm communicating portion of the system was not yet in service, although the internal detection portions were operational).
The fire originated in an assistant principal`s office, located in the administrative section of the building, and also involved a liquid accelerant. Two sprinkler heads in the office extinguished the fire. Very little smoke or fire damage occurred outside the room of origin. Particularly impressive in this fire was that the school`s switchboard and computers, located in the adjacent office space, were not damaged and were fully operational following the preliminary investigation. There was some water damage in the building due to the sprinkler system`s flowing with no remote alarm transmission.
“The fire could have quickly spread to involve the main north/south corridor, including all adjoining rooms and spaces on the upper level,” explains Edina Fire Department Chief Ted Paulfranz. “Fortunately, the two sprinklers in the office immediately operated, controlling and extinguishing the fire. Clearly, automatic sprinklers made the difference in this fire, and we avoided a most serious loss. If this protection had not been in place, our community would have suffered a tragic loss,” Paulfranz adds.
MINNETONKA HIGH SCHOOL
At about the same time as the Edina High School fire, a fire was discovered at Minnetonka High School. This fire was simultaneously reported by the school`s janitor and the alarm-monitoring company in response to a sprinkler water flow alarm. Multiple fires appeared to have been started in the administrative offices and a staff mail room. Once again, the use of a liquid accelerant was suspected. In this incident, 11 sprinkler heads, including two in the exit corridor, activated and quickly extinguished the fire. The corridor sprinklers were activated when the fire spread from one of the rooms of origin into the corridor as a result of a fire door that had been “wedged” open.
The sprinkler system had been retrofitted into this school in 1986 at the time of response to a major remodeling project and structural addition. Minnetonka Fire Marshal Steven Anderson explains: “This system originally was installed based on building code requirements to protect the structure, although we also recognized the benefit of sprinklers as a life-safety feature. Even at the height of these fires, with enough heat to set off 12 sprinkler heads, conditions in the building were never untenable due to smoke or heat. In addition, we realized another benefit of sprinklers, which we did not envision, and that`s the fact that they did an excellent job of preserving evidence, which we feel will assist us in the prosecution of this case.”
Based on the quick actions of the Minnetonka High School janitor, a partial license number was obtained from a fleeing vehicle, which resulted in the identification and arrest of a 24-year-old suspect, who is awaiting trial on arson and burglary charges.
The quick and effective activation of the sprinkler systems in the Edina and Minnetonka schools made it possible for the schools to proceed with scheduled school plays in their buildings only 12 hours after the fires. Total fire loss for these two fires was only $150,000 (compared with $7 to $8 million at Burnsville High School). Neither the Edina nor Minnetonka school building was able to hold classes the day of the fires, although Edina had a scheduled day off for the students anyway. Both buildings were operational the following school day.
“We have been on an aggressive program of fire and life-safety upgrades to the schools in Minnesota, based on legislation passed in 1990 mandating state fire marshal inspection of existing school buildings,” reports Minnesota State Fire Marshal Tom Brace, a former president of the International Association of Arson Investigators. “We have been encouraging schools to install automatic sprinkler protection rather than what we consider more costly and less effective construction modifications to their buildings. We have learned a great deal about the effectiveness of sprinkler systems in schools based on these recent fires. We are also concerned about the more violent nature and large-scale use of accelerants by arsonists. We cannot depend strictly on the building`s construction features to protect the building, its contents, or occupants from fire. So far, sprinklers are the only method we have seen which can substantially minimize these types of violent incidents,” Brace further explains. “We salute the wisdom and foresight of the Edina and Minnetonka school districts and fire departments in their efforts to retroactively install automatic sprinklers. Their decisions saved their buildings and potentially millions of dollars worth of damage,” Brace concludes.
Although many would characterize the Burnsville fire as a major loss, sprinklers played a definitive role in saving large portions of the building. “Even though millions of dollars of damage occurred, the sprinklers saved approximately 43,000 square feet of property, conservatively estimated to be valued at $3 million. In other words, we had a multimillion-dollar save,” notes Burnsville Fire Marshal James Schwab. “We have been working with the school district to get this building sprinklered, which they intended to do; unfortunately, the fire happened before the sprinklers could be installed.” (As noted above, the sprinklers were installed at the time the fire damages were repaired.)
Sprinkler protection played a significant role in extinguishing two of these three school fires and prevented the further spread of the fire in the partially sprinklered Burnsville school. Even though other factors–such as interior flame spread, accelerated fires, and fire doors being propped open– contributed to these fires, the automatic sprinklers overcame these obstacles and allowed the schools–investments of the communities–to continue to operate. n
JON NISJA is supervisor of the Minnesota State Fire Marshal Division.
