A Special Edition of the SWEIS Yearbook Wildfire 2000

Los Alamos National Laboratory

A Comparison of the LANL Site-Wide Environmental Impact Statement Wildfire Accident Analysis with the Cerro Grande Fire The US Department of Energy (DOE) issued a Site-Wide Environmental Impact Statement (SWEIS) for continued operation of Los Alamos National Laboratory (LANL) (DOE 1999a) and a Record of Decision (ROD) in 1999 identifying how DOE would operate LANL in the future (DOE 1999b). The SWEIS included analyses of accident scenarios, both facility specific and site-wide. Accident analyses are necessary for making a reasoned choice among alternatives and for appropriate consideration of mitigation measures. The SWEIS for LANL included a wildfire accident scenario entitled "Site Vvildfire Consuming Combustible Structures and Vegetation," coded as SITE-04. This accident scenario was added to the SWEIS as a result of public comments and concerns expressed by a US Forest Service (USFS) employee assigned to the nearby Santa Fe National Forest. The accident is described in detail in Appendix G of the SWEIS. SITE-04 had the highest return frequency of all accidents analyzed in the SWEIS, with a probability of occurrence of once in ten years. S ITE-04 had two cases: a wildfire without mitigation that resulted in burning seven facilities with hazardous and chemical inventories and a wildfire with mitigation (tree thinning and brush clearing) that resulted in no burning of facilities with inventories. The latter scenario was very closely paralleled by the Cerro Grande fire of May 2000. The Laboratory publishes an annual SWEIS Yearbook (LANL 1999a), comparing actual LANL operations, effluents, and impacts to those projected in the SWEIS ROD. This Special Yearbook Edition-Wildfire 2000--compares the postulated accident with the Cerro Grande fire. The purpose of this analysis is to do a direct comparison of a 'real life' accident to that postulated in the LANL SWElS as a practical evaluation of the accuracy of the SWEIS analysis. The comparison of the Cerro Grande fire and the SWEIS wildfire scenario will allow DOE to better assess the usefulness and approach of accident analyses. As time progresses and detailed field surveys are conducted, the data reported here for the Cerro Grande fire will be refined and are expected to change (i.e., acreage burned, damage lists of facilities, maps of the fire, etc.). The information presented here was collected immediately following the fire and represents data available in mid-July 2000.