Guam Hazard Mitigation Plan - Western States Seismic Policy Council

SECTIONFIVERisk Assessmentequal to the percentage exposed in the 2008 Guam HMP. This exposure analysis assumes arelease from all of the known hardfill facilities on Guam, which is an unlikely event. Because ofthe unknown characteristics and magnitude of the potentially released HAZMAT, this analysisassumes a conservative 1-mile radius around each hardfill site as the potentially affected area.This assumption tends to overemphasize the vulnerability of Guam to this hazard.At the village level, as shown in Tables F-15 and F-16, the population exposed to an atmosphericrelease of HAZMAT from hardfill facilities is as follows: Yigo has the most people exposed tothis hazard (13,948 people, or 61.4 percent of the village population), Chalan Pago-Ordot has thesecond highest number of people exposed (4,385 people, or 63.4 percent of the villagepopulation), and Mangilao has the next highest, with 4,305 people exposed (27.7 percent of thevillage population).The portion of EFMUTS and the GBS that could be exposed to a release from these facilities isnot included in this discussion. A HAZMAT release into the atmosphere would not affect thephysical structure or function of these buildings and facilities. The people occupying thesebuildings and facilities would be affected, but the best available data do not include anyinformation on the number of people (e.g., average number of people, maximum number ofpeople) occupying these buildings and facilities. It is likely that some of these people have beenconsidered because they live in the exposed area. Therefore, it is impractical to accuratelydetermine or estimate the number of people occupying all of the facilities. That being said, thetotal exposed EFMUTS and GBS and the value of these exposed buildings and facilities areshown in Tables 5-20 and 5-21 and Tables F-15 and F-16.HAZMAT: Pre-CERCLIS FacilitiesSimilar to results in the 2008 Guam HMP, this 2011 analysis found that a large number of peoplecould be exposed to hazardous release from all of the Pre-CERCLIS facilities. Assuming a 1-mileradius around each Pre-CERCLIS facility as the area of exposure, 136,446 people (75.5 percent ofthe population of Guam) would be exposed to releases, as shown in Tables 5-20 and 5-21.The exposed EFMUTS include 301 Essential Facilities (worth $852.3 million), 251 MajorUtilities (worth $707.2 million), and 124 Transportation Systems (worth $108.5 million).Similar to earlier versions of the Guam HMP, because of the large number of Pre-CERCLISfacilities (409) on Guam and the general lack of information available for these facilities, theexposure analysis of releases from these facilities overemphasizes and exaggerates the hazard.Because of the lack of information, a large area of exposure (i.e., a 1-mile radius around eachknown facility) was chosen as a conservative and worst-case exposure scenario. The vulnerabilityanalysis examines the exposure resulting from releases at all the sites with a known location (142facilities) at one time. This scenario is highly unlikely to occur. Therefore, this type of exposureanalysis, which is the best available analysis that can be conducted with the available resources,overemphasizes the hazard.Like the earlier versions of the Guam HMP, Dededo has the most exposed people, with 25,554people (50.9 percent of the village population), as shown in Tables F-17 and F-18 (Appendix F[Vulnerability and Potential Loss Results by Village]). All of Tamuning’s 21,138 people are atrisk of being exposed to a hazardous release from all of the Pre-CERCLIS facilities. Yigo has thethird-highest number of exposed people, with 17,997 people (79.2 percent of the villagepopulation).5-67