APPENDIX B: SEISMIC ASSESSMENT GUIDELINES

Transcription

1 APPENDIX B: SEISMIC ASSESSMENT GUIDELINES PURPOSE Appendix B The following provide guidance for performing seismic assessments of stationary sources subject to the California Accidental Release Prevention (CalARP) Program within Contra Costa County. A seismic assessment identifies seismic vulnerabilities that could result in an accidental release of a regulated substance, or other extremely hazardous substance, following an earthquake. BACKGROUND AND APPLICABILITY The CalARP regulations require that stationary sources with Program 2 and Program 3 covered processes consider seismic events as part of the hazard reviews and process hazard analyses of their stationary sources that contain regulated substances [Title 19 CCR (d) and Title 19 CCR (c)(8)]. These guidelines have been developed by the Technical Subcommittee of the CAER RMP Task Group to assist industry in preparing the required seismic assessment(s). These guidelines apply to all stationary sources with Program 2 and Program 3 covered processes. GUIDELINES Rather than prescribe a specific methodology to cover every type of regulated stationary source and structure or type of equipment, the Technical Subcommittee (TSC) has chosen to establish the following guidelines. This is intended to allow the seismic reviewer(s) performing the assessment to choose the most appropriate assessment method(s) for each stationary source or covered process within a stationary source. 1. The results and recommendations from the seismic assessment should be prioritized with the hazard review or process hazards analysis to maximize the effectiveness of the recommended mitigations. The seismic assessment could be performed prior to the Program 2 hazard review and/or the Program 3 process hazard analysis so that the results would be readily available for consideration. 2. Stationary sources that contain regulated substances above the threshold quantity shall be physically inspected by a qualified civil/structural/mechanical engineer or other qualified person that is knowledgeable about the applicable types of failures that may occur to structures and equipment during moderate to strong ground shaking. The B-1

2 physical inspection should take the form of a methodical, on-site, walkdown review. Although this review may include a review of structural drawings, a drawing review alone is considered to be insufficient for existing and new stationary sources. The purpose of the walkdown review is to visually identify items that may be vulnerable to seismic damage or may damage other items. The walkdown review should be supplemented by more detailed evaluations where necessary. Qualifications that the owner should consider for the seismic reviewer(s) include: a. Familiarity with potential seismic vulnerabilities for the types of systems being reviewed; b. Ability to apply information contained in geotechnical reports; c. Ability to perform detailed engineering evaluation of structural response to ground motion; and d. Previous applicable seismic evaluation experience. 3. The overall performance objective that a stationary source should meet during moderate to strong ground shaking in Contra Costa County is primary containment of regulated substances. To achieve the overall performance objective, individual equipment items, structures, and systems (e.g., power, water, etc.) may need to achieve varied performance criteria. These criteria may include one or more of the following: a. Maintain structural integrity; b. Maintain position; c. Maintain containment of material; d. Function during the earthquake; and/or e. Function after the earthquake. Note that a stationary source owner may choose to set more stringent performance requirements dealing with continued function of the stationary sources both during and after an earthquake. These are individual business decisions and are not required for compliance with CalARP. 4. The qualified seismic reviewer shall review appropriate references to identify the specific seismic hazards that may apply to the stationary source under review, such as: a. Proximity to known active faults as defined by the State Geologist; b. Potential for liquefaction; c. Ground shaking, including local site amplification effects; B-2

3 d. Seismic settlement; and/or e. Landslide, etc. A list of publicly available geotechnical references may be found in the reference list at the end of these guidelines. Several of these references are available for review at the CCCHSD Hazardous Materials Office at 4333 Pacheco Boulevard in Martinez. The geotechnical reference list is offered to assist the stationary source in preparing the required seismic assessment, but is neither necessarily complete nor sufficient. The stationary source might also benefit by considering site-specific soils analysis which may have previously been conducted. 5. As part of the stationary source walkdown, the seismic reviewer shall identify and document vulnerabilities that may result in failure to meet the performance criteria during moderate to strong ground shaking, considering any identified site-specific seismic hazards. Examples of vulnerabilities that could lead to accidental releases for various systems are listed in Table Some items identified as vulnerabilities during the stationary source walkdown may be determined by additional quantitative analysis to be adequately designed and installed. Also, calculations or further technical analysis may be necessary in order for the seismic reviewer to quantify the expected performance and determine whether failure is a concern. CCCHSD has historically referenced the Proposed Guidance for RMPP Seismic Assessments, developed for the Southern California Fire Chiefs Association, for quantifying the expected performance of specific equipment or structures. This document is particularly applicable to the types of equipment that are found in the petrochemical industry. It is also applicable to the types of noncode-conforming conditions that are likely to be found in older existing stationary sources. Several recent documents have been developed which may also be useful to seismic reviewers that are performing inspections or detailed seismic evaluations for CalARP regulated stationary sources. These documents are included in the reference list at the end of this section. 7. Documentation of the entire seismic assessment should be maintained on-site by the stationary source. An example of this documentation is shown in Chapter 9 for both the Hazard Review and Process Hazard Analysis. B-3

4 TABLE 1 Examples of Seismic Vulnerabilities (This list is not all-inclusive) Equipment Movement Unanchored Equipment Improperly Anchored Equipment, etc. Structural Failure Deteriorated foundations or structures Inadequate bracing Poor overall three-dimensional stability Presence of non-ductile materials, etc. Piping Systems Overly restrained piping Improperly supported piping Unrestrained piping that could slide off supports Systems Interactions Damage to branch connections during movement Short insulation shoes, etc. Presence of non-ductile materials, etc. Systems Interactions Building collapse Falling objects, etc. B-4

5 REFERENCES GEOTECHNICAL: Fault-Rupture Hazard Zones in California Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zones Maps, Special Publication 42, Revised 1994, California Department of Conservation, Division of Mines and Geology. (This report indexes the maps, which identify the Earthquake Fault (Special Studies) Zones Maps, which will aid in identifying the known faults in the vicinity of the stationary source). Earthquake Planning Scenario for a Magnitude 7.5 Earthquake on the Hayward Fault in the San Francisco Bay Area, Special Publication 78, 1987, California Department of Conservation, Division of Mines and Geology. (This report provides maps referencing more detailed maps showing those areas impacted by the Hayward Fault). Bay Area Liquefaction Maps Association of Bay Area Governments. See the SEISMIC ASSESSMENT: Proposed Guidance for RMPP Seismic Assessments, prepared for the RMPP Sub-Committee of the Southern California Fire Chiefs Association. Addresses process equipment evaluation. This document is included in this appendix. Guidelines for Seismic Evaluation and Design of Petrochemical Facilities, Task Committee on Seismic Evaluation and Design of Petrochemical Facilities, American Society of Civil Engineers, This includes a chapter on walkdown considerations. This book may be ordered from (Stock Number 40264). National Earthquake Hazard Reduction Program (NEHRP) Handbook for the Seismic Evaluation of Existing Buildings. FEMA 178. Specifically developed for application to existing structures for the Building Seismic Safety Council (BSSC). NEHRP Recommended Provisions for Seismic Regulations for New Buildings, Part 1:Provisions. FEMA 222A. For use with FEMA 178. Addresses process components, such as tanks, pipes, etc. NEHRP Recommended Provisions for Seismic Regulations for New Buildings, Part 2:Commentary. FEMA 223A. For use with FEMA 178. Addresses process components, such as tanks, pipes, etc. NEHRP Guidelines for the Seismic Rehabilitation of Buildings. FEMA 273. Uses a performance-based approach, where a higher level of seismic performance, such as (Immediate Occupancy), may be specified. Commentary on FEMA 273. FEMA 274. Manual of Techniques for Preventing or Controlling Toxic Gas Releases in Earthquakes, November, Association of Bay Area Governments (ABAG), and other related documents. B-5