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r 1% 0 Attachment A Title 27, Section 21090(a)(6) Stability Analysis — For any portions of the final cover installed after July 18, 1997, for which the RWQCB has not approved a slope and foundation stability report on or before that date, the discharger shall meet the requirements of section 21750(f)(5). Title 27, Section 21750(f)(5) Stability Analysis — A stability analysis, including a determination of the expected peak ground acceleration at the Unit associated with the maximum credible earthquake (for Class II waste management units) or the maximum probable earthquake (for Class III landfills). This stability analysis shall be included as part of the ROWD (or JTD) for the proposed Unit, and an updated stability analysis (if the original analysis no longer reflects the conditions at the Unit) shall be included as part of the final closure and post -closure maintenance plan. The methodology used in the stability analysis shall consider regional and local seismic conditions and faulting. Data and procedures shall be consistent with current practice and shall be based on an identified procedure or publication. The stability analyses shall include modifications to allow for site specific surface and subsurface conditions. The peak ground acceleration so determined shall be the stability and factors of safety for all embankments, cut slopes, and associated landfills during the design life of the unit. For landfills and for waste piles and surface impoundments closed as landfills, final cover slopes shall be designed in compliance with the slope requirements of section 21090. (A) The stability analysis shall ensure the integrity of the Unit, including its foundation, final slopes, and containment systems under both static and dynamic conditions throughout the Unit's life, closure period, and post -closure maintenance period. The stability analysis shall include: 1. the method used to calculate the factors of safety (e.g., Bishop's modified method of slices, Fellinius circle method, etc.); 2. the name of any computer program used to determine the factors of safety; and 3. a description of the various assumptions used in the stability analyses (height of fill, slope and bench configuration, etc.). (B) The stability analysis shall address all portions of the Unit and its immediate surroundings that are located in areas subject to liquefaction or unstable areas with poor foundation conditions, as identified either in the ROWD or in the Seismic Safety Element of the County General Plan; and shall address all portions of the Unit that incorporate geomembranes as part of the Unit foundation or containment system (including the final cover). (C) The stability analysis shall be prepared by a registered civil engineer or certified engineering geologist. Except as otherwise provided in (f)(5)(D), the report must indicate a factor of safety for the critical slope of at least 1.5 under dynamic conditions. Regardless of the analysis method used, the stability analysis report shall include at least the following elements: 1. report preparation shall be in accordance with CDMG Note Number 42, "Guidelines for Geologic/ Seismic Reports," May 1986, and CDMG Note Number 44, "Guidelines for Preparing Engineering Geologic Reports," April 1986, [both available from the California Division of Mines and Geology (CDMG), 801 K Street, MS14-34, Sacramento, CA 95814-3532, phone 916-445-5716] which are both incorporated by reference, and shall include the following seismicity elements: Page 1 of 2