44 Library, MC-522
1408 West Gregory Dr.
Urbana, IL 61801
Oak St. Library Facility
OSLF, 2nd Floor
809 South Oak Street
Mail Code 527
Champaign, IL 61820
Risk Assessment of Disasters
Based on data from the National Weather Service over the past 60 years, on average a tornado develops in Champaign County once every year. Champaign city is 17 square miles whereas Champaign County is 1008 square miles. This proportion leads to a 2% chance a tornado will affect Champaign city. The average tornado is 500 feet wide and travels for 5 miles (after touchdown) causing 0.47 square miles of damage1. Assuming that a tornado affected Champaign city, on average it would damage 2.76% of the city. Most tornadoes (57%) caused little to no damage and were categorized as F0’s under the original Fujita scale, which ranges from F0 to F52. Tornadoes that occur in Champaign city are randomly distributed across the city. Figure 4.1 shows the damage probability in the event a tornado occurs near the Oak St. Facility and the average maximum damages for each category tornado. The figure assumes a tornado has occurred and the maximum damage percentages correspond to the chance of each tornado category. A tornado causing more than 71,000 materials to be damaged would be classified as an F5. Such a tornado is so rare and catastrophic that it is difficult to assign a maximum amount of damage, if any.
The New Madrid fault line is located along the border of Illinois, Missouri, and Kentucky approximately 250 miles from Champaign. Due to the distance, the damaged caused by an earthquake would be significantly less (about 2.0 fewer Richter scale units, or 1000 times less energy) in Champaign than it would be at the fault’s epicenter. An earthquake of magnitude 6.0-7.6 (90% chance of occurrence by 2040) along the fault would result in rattling objects, notable but not destructive ground tremors, and the displacement of unstable objects (such as vases) in Champaign3. The shelving units are designed to withstand an earthquake of magnitude of 4.0 without experiencing damage. Given that an earthquake greater than a magnitude 8.0 occurs every 200-300 years, it is not economically justifiable to design the shelving units to withstand a force this large. The greatest concern for the Oak St. Facility would be books falling off of the shelves, and it may be necessary to develop safeguards to ensure that books do not fall.
The sprinkler system at the facility is a wet pipe system, leaving the possibility that the sprinklers will discharge accidentally. In testing, this probability has been shown to be extremely small, with less than 1 per one million accidental sprinkler head discharges occurring4. Though small, the potential damage that can result from an accidental discharge should not be overlooked. Since the sprinklers are independent of one another (i.e. a sprinkler that goes off will not cause other sprinklers to go off) the likelihood of another sprinkler head malfunctioning is still 1 per one million. Considering the spray radius, shelving layout, and flow rate it is estimated that one sprinkler has the capability of damaging an average of 30,000 materials4. Figure 4.2 displays the probability vs. damage if a sprinkler malfunctions.
Twenty-eight flood events have occurred in Champaign County over the last 58 years with 78% of these events only affecting low lying property such as fields or backyards. These floods caused no recordable property damage to people’s homes or businesses, but six floods have brought at least $50,000 worth of damage to the area since 1993 alone. Overall, 21% of flood disasters caused over $50,000 in damage, while two events in 1994 each caused approximately $50 million in damage. The high risk of flooding in Champaign (48% in any given year), coupled with the fact that water damage due to leaks and broken pipes can occur with nearly any natural disaster, emphasizes the need for a disaster plan that gives high priority to water disasters.
The Oak Street Facility lies above the Third Street Boneyard Tributary. The data recorded by FEMA (Figure 4.3) does not provide extensive flood data specific to Oak Street but it does to streets within two blocks. The shaded zone represents the “100 year flood zone” boundary and the narrow contour lines surrounding that represent the “500 year flood zone”. These regions represent the average time intervals in between catastrophic floods, and by extending the tributaries shown in Figure 4.3, Oak Street would most likely fall under the “500 year category.” This means that a catastrophic flood would effect this location once every 500 years due to the contours of the land. Also, since the materials in the facility are elevated 3 inches from the floor, a minor flood would not have significant impact on the materials.
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