Guam Hazard Mitigation Plan - Western States Seismic Policy Council

SECTIONFIVERisk AssessmentRepetitive loss (RL) properties are properties that suffer from repeated flooding. FEMA defines aRL property as a property with at least two $1,000 claims within any 10-year period since 1978.Table 5-22 and Figure D-29 show that 14 RL properties are on Guam (as of February 2011).Addresses for these properties are not included in this Guam HMP, but are kept on file at DPW.Table 5-22Repetitive Loss PropertiesProperty Location Property Type Flood Insurance Number of Losses SFHAAgat Single-family Yes 2 YesAgat Single-family Yes 2 NoAgat Single-family No 2 UnknownAgat Single-family No 2 YesAgat 2 – 4 family home No 2 YesInarajan Single-family Yes 2 YesMerizo Single-family No 2 YesPiti Nonresidential No 2 YesPiti Single-family No 3 YesTamuning Single-family No 2 YesTamuning Single-family Yes 2 YesTamuning Single-family Yes 2 YesTamuning Single-family Yes 2 YesUmatac Single-family No 2 YesSource: FEMA SQANet 2011.HAZMAT: NPDES-Air Permitted FacilitiesA moderate number of people, 59,073 people (32.7 percent of Guam’s population), could beexposed to HAZMAT releases into the atmosphere by a facility with an NPDES permit, as shownin Tables 5-20 and 5-21. Due to an increased number of these facilities, an additional 20 percent(approximate) of the population is exposed to this hazard, as compared to the 2008 Guam HMP.This analysis makes the worst-case and, therefore, highly unlikely, assumption that HAZMATwould be released into the atmosphere at the same time from all of the permitted facilities andhave catastrophic effects. The best available data for these facilities do not include anycharacterization of the substances that could be released into the atmosphere. The characteristicsof a released gas and the magnitude of a release are unknown and undetermined for thesefacilities. It is unknown if a release would consist of an Extremely Hazardous Substance or a lessharmful HAZMAT that quickly dissipates, like carbon monoxide. Therefore, a worst-case (andhighly unlikely) scenario of an atmospheric release that could affect a 1-mile radius around eachfacility was assumed. For this reason, this exposure analysis inherently overemphasizes thehazard.In terms of village-level population exposure, as shown in Tables F-11 and F-12 (Appendix F[Vulnerability and Potential Loss Results by Village]), Dededo has the highest exposure with23,611 people (47.1 percent of the village population), followed by Tamuning with 11,937 people(56.5 percent of the village population), and Yigo with 6,831 people (30.1 percent of the villagepopulation).5-65