Safety Assessment Program Evaluator Student Manual

CA Emergency Mgmt. Agency Safety Assessment Program Evaluator Manual April 2011Photo courtesy Dave Karina, ACIAFigure 2-36 – Water tower undergoing demolition to abate collapse hazardThe previous photos illustrate how a collapse hazard was identified in the 2010 Baja Earthquake,the safety assessment response to it, and the abatement of the hazard.The landmark El Centro water tower was 150 feet high, and held only a small quantity of waterat the time of the earthquake. As shown in Figures 2-32 through 2-34, the earthquake damagedthe concrete footings of the water tower, snapped one anchor bolt, and resulted in anotherconnection being drawn out and broken as well. With the ongoing strong aftershocks, or evenwith the winds found in the area at times, there was a serious danger of the water towercollapsing in an unknown direction. As shown in Figure 2-35, the tower was tagged UNSAFE.Within the collapse zone of the water tower were two residences and an 8-unit apartmentbuilding. These were all tagged UNSAFE and evacuated due to the clear and present dangerfrom the potential collapse of the neighboring water tower. Within a very short time, the City ofEl Centro acted to demolish the water tower and remove the hazard (Figure 2-36). Then theUNSAFE tagging of the neighboring residences in the collapse zone could be reassessed andreversed. (Note that, if the neighboring residences had their own safety issues beyond the oneposed by the collapse hazard, the new assessments would reflect that in the posting of thoseresidences.)60