USACE Levee Screening Tool application guide and user s manual: Levee Safety Action Classification (LSAC)

Transcription

1 USACE Levee Screening Tool application guide and user s manual: Levee Safety Action Classification (LSAC) (Attachment 1 to the USACE LST application guide with user s manual)

2 Chapter 14 Attachment 1. Levee Safety Action Classification (LSAC) 2

3 Contents The LSAC system and its role in USACE levee portfolio management... 5 Overview... 5 Levee screening... 5 Assignment of an LSAC to a levee system... 6 Review and vetting

4 Tables Table 1. Levee Safety Action Classification (LSAC) (updated 29 December 2011)

5 The LSAC system and its role in USACE levee portfolio management Overview The Levee Safety Action Classification (LSAC) system is used to guide decisions in the portfolio management process. All levee systems are assigned an LSAC informed by the most recent risk assessment available. Initially, LSAC assignments are informed by screening-level assessments, but as the process advances, more rigorous risk assessments will be conducted on selected systems and the LSAC for those systems will be updated accordingly. The LSAC of a levee system may change as a levee system is modified or more refined information becomes available that affects any of the risk determinants. The five classes used in the USACE levee safety portfolio risk management process are: Class I Very high risk warranting urgent and compelling actions to reduce risk. Class II High risk warranting urgent actions to reduce risk. Class III Moderate risk warranting high priority actions to reduce risk. Class IV Low risk warranting priority actions to reduce risk. Class V Normal risk considered tolerable, requiring only that normal levee safety activities continue. The process by which an LSAC is assigned to a levee system is as follows: 1. A relative risk assessment is done at the district level. 2. A roll-up, consistency review, and proposed LSAC assignment is completed at the national level. 3. A review and development of a recommended LSAC for each system is done by a group of senior-level USACE levee safety officials. 4. That recommendation is forwarded to the USACE levee safety officer for approval, action, and dissemination. Vetting of data, relative risk assessment estimates, and proposed LSAC assignments occur at each stage of the screening process, involving sponsors, stakeholders, district, division, laboratories, and HQUSACE staff and experts from the USACE Risk Management Center (RMC). Further details are provided below. Levee screening The relative risk assessment in support of the screening is performed by district staff and led by a qualified risk assessment facilitator. The risk assessment makes use of available data and information from completed inspection reports, design and construction records, and other studies and observations regarding performance of the levee. Much of this information is catalogued in the National Levee Database (NLD). The Levee Screening Tool (LST) retrieves data from the NLD, accepts limited engineering assessment input from the screening team, performs computations that result in screening-level risk assessments, stores the results, and generates displays and reports for review and documentation. The LST provides a preliminary quantitative assessment of the general condition and relative risks associated with 5

6 individual levee segments. Results from the LST are used to inform the screening process. The screening process is used to evaluate all levee systems in the USACE portfolio. The LST helps to inform the judgment of levee experts who ultimately must synthesize the available information and make credible risk management decisions. Assignment of an LSAC to a levee system An LSAC is assigned separately for each levee segment within a levee system. A levee system will receive an LSAC based on the highest risk segment of the system. When determining an LSAC for a levee system, additional consideration will be given to features that make up the levee system but do not have an LSAC assigned at the segment level because they are not associated with any particular segment and are not part of the authorized project (e.g., highway abutments and railroad embankments). The task for USACE experts is to interpret the LST relative risk results, other available data, and information about the system, and assign an LSAC. The assignment of an LSAC is intended to reflect the descriptors for each class indicated in Table 1. Translating the descriptors in Table 1 is a key and challenging aspect of assigning an LSAC. These examples illustrate application of the highest-risk and lowest-risk descriptors: Extremely high A levee system breach that would very likely result in multiple fatalities in the levee area with the occurrence of the next flood event of 2% annual chance exceedance (the 50-year flood). A levee system expected to breach from a moderately rare flood event of 1% annual chance exceedance (100-year) or 0.5% annual chance exceedance (500-year), with likely fatalities in the hundreds. Low to moderate or very low A levee system that is expected to be resistant to breaching for a 0.01% annual chance exceedance event in which several fatalities are estimated but for which there is good floodplain egress infrastructure, very good emergency warning and evacuation plans, and for which a well-trained and staffed emergency response capability exists. Ultimately, the justification for the final recommended LSAC will be narrative, not numerical. The LSAC is informed by the estimated risk (life-safety risk is paramount; economic and environmental risk is secondary). Typically, risk for breach prior to overtopping of the levee system will be a strong driver of potential life loss, but there are other considerations, including characteristics of the threatened population, critical infrastructure present in the floodplain, uncertainty in data and information, and relative risk estimates for the levee system s segments. The proposed LSAC is reviewed by the senior level USACE levee safety officials as to whether it should be adjusted up or down based on all available information. This includes LST inputs and outputs, inspection findings and reports, past performance, facilitator presentations, fact sheets, summary reports, and discussion among safety officials. Consideration is given to such matters as past flood fighting, confidence in various components of the risk assessment, age of the levee system, presence of critical infrastructure, urbanization history and trends, scope of potential impact of breach (local, regional, national), environmental consequences, and presence of 6

7 items of national significance such as military facilities and armaments, national/international heritage sites, and so forth. Review and vetting The levee screening relative risk assessment and information compilation is developed by a district team, led by a qualified facilitator, and advised by staff from the USACE Risk Management Center (RMC). The risk assessment is validated by the national quality assurance (QA) cadres. The risk assessment inputs and results (breach likelihood and life loss and economic consequences) go through several levels of review. Review is performed at the district level and further review is completed during a regionally grouped national roll-up. This national roll-up review is for consistency of data and analysis among district assessments and proposed LSAC assignments, and ensures proper documentation is prepared and is in order. The next level of review is completed by the Levee Safety Senior Oversight Group (SOG). The SOG is chaired by the Special Assistant for Dam and Levee Safety, with members drawn from HQUSACE, division, RMC, laboratories, and district experts. Representatives of the local sponsor for federally authorized, local sponsor operated and maintained levee systems and representatives of non-federal levee owners are invited to participate in the screening and vetting process. The summary presentation is made by the appropriate staff, most likely the USACE district facilitator or national USACE QA cadre lead. SOG members have access to the district presentation, LST report, the summary presentation, and information stored in the NLD. Following the SOG meeting, any needed changes to LST reports are made. The final LSAC recommendation is included in the Levee Safety Screening report that is forwarded to the USACE Levee Safety Officer for final approval. Upon approval, the LSAC assignments are transmitted by the USACE Levee Safety Officer to the local district. The district then works with the levee system sponsor to understand the action classification assignment and its implications, to assist the local sponsor and community officials in publicizing the risk, urgency and recommended actions, and to plan the way forward. 7

8 Table 1. Levee Safety Action Classification (LSAC) (updated 17 October 2012) Levee Safety Action Class (LSAC) (1) Actions for Levee Systems in this Class Additional actions in 1) apply to USACE Operated and Maintained Levee Systems; and actions in 2) apply to Levee Systems Operated and Maintained by Others in USACE Program I Immediately inspect levee system. Assure O&M is up to date. Communicate risk findings to sponsor; state, federal, Tribe, and local officials; and public Stress improved floodplain management to include: verification that warning, evacuation and emergency action plans are viable; flood inundation maps are current; there is an active community hazard awareness program; recommend purchase of flood insurance; and vigilant levee monitoring program is in place. Support portfolio priorities for risk reduction actions. 1) Take urgent action to reduce the likelihood of a breach and mitigate consequences through implementation of interim risk reduction measures. 2) Responsible entity to implement interim risk reduction measures. II Inspect levee system. Assure O&M is up to date. Communicate risk findings to sponsor; state, federal, Tribe, and local officials; and public Stress improved floodplain management to include: verification that warning, evacuation and emergency action plans are viable; flood inundation maps are current; there is an active community hazard awareness program; recommend purchase of flood insurance; and vigilant levee monitoring program is in place. Support portfolio priorities for risk reduction actions. 1) Take immediate action to implement interim risk reduction measures. 2) Responsible entity to implement interim risk reduction measures. III Verify inspection is current. Assure O&M is up to date. Communicate risk findings to sponsor; state, federal, Tribe, and local Characteristics of this Class Probability of inundation due to breach and/or system component failure in combination with loss of life, economic, or environmental consequences results in extremely high risk. USACE considers this level of life-risk to be unacceptable except in extraordinary circumstances. Probability of inundation due to breach and/or system component failure in combination with loss of life, economic, or environmental consequences results in very high risk. USACE considers this level of life-risk to be unacceptable except in extraordinary circumstances. Probability of inundation due to breach and/or system component failure in combination with loss of life, 8

9 officials; and public Stress improved floodplain management to include: verification that warning, evacuation and emergency action plans are viable; flood inundation maps are current; there is an active community hazard awareness program; and routine levee monitoring program is in place. Recommend purchase of flood insurance. Develop and execute levee monitoring program. Support portfolio priorities for risk reduction actions. 1) Implement interim risk reduction measures; schedule development of risk reduction studies. 2) Responsible entity to develop interim risk reduction and risk remediation plans. IV Verify inspection is current. V Assure O&M is up to date. Communicate risk findings to sponsor; state, federal, Tribe, and local officials; and public Stress improved floodplain management to include: verification that warning, evacuation and emergency action plans are viable; flood inundation maps are current; there is an active community hazard awareness program; and routine levee monitoring program is in place. Recommend purchase of flood insurance. Develop and execute levee monitoring program. Support portfolio priorities for risk reduction actions. 2) Responsible entity to develop interim risk reduction and risk remediation plans. Continue routine levee safety activities, operation and maintenance, normal inspections, stress improved floodplain management to include: annually ensure that warning, evacuation and emergency action plan are functionally tested; recommend purchase of flood insurance; maintain levee monitoring program. economic, or environmental consequences results in moderate to high risk. USACE considers this level of life-risk to be unacceptable except in unusual circumstances. Probability of inundation due to breach and/or system component failure in combination with loss of life, economic, or environmental consequences results in low to moderate risk. USACE considers this level of life-risk to be unacceptable except in the range of tolerability but does not meet all essential USACE guidelines. There is a very low probability of inundation due to breach and system component failure and/or consequences are low. USACE considers this level of life-safety risk to be tolerable and meets essential USACE guidelines. Note: At any time, a levee system from any action class can become an emergency requiring activation of the emergency action plan. 9