ARCHIVED REPORTS_1994_1 - Laserfiche WebLink

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l (b) The stability of landfill slopes located in areas subject to liquefaction or unstable areas with poor foundation conditions as defined by the Seismic Safety Element of the County General Plan shall be substantiated by a foundation stability report. Flatter, vegetated slopes are recommended for surfaces which face residential property, roads and other property frequented by the public. The enforcement agency or Board may require flatter slopes or additional benches where necessary to ensure preservation of the integrity of the final cover and environmental control systems under static and dynamic conditions, for successful establishment cf ground cover, or erosion control. Slope stability reports may also be required by the local enforcement agency or the Board in areas subject to liquefaction, unstable areas with poor foundation conditions, or when geomembranes are used in site design. (c) A slope or foundation stability report shall be prepared by a registered civil engineer or certified engineering geologist. The report must indicate a factor of safety for the critical slope of at least 1. 5 under dynamic conditions. The report shall include, but is not limited to, the following elements: (1) Report preparation shall be in accordance with California Division of Mines and Geology (CDMG) Note Number 42, "Guidelines for Geologic/Seismic Reports, " May 1986, and Note Number 44 , "Guidelines for Preparing Engineering Geologic Reports, " April 1986, which are both incorporated by reference, and shall include the following seismicity elements: (A) a review of earthquakes during historic time; (B) location of active major faults; and (C) surface investigation of the site and surrounding area. (2) The location of the critical slope and other slopes analyzed to determine the critical slope shall be shown in map view. (3) Calculations used to determine the critical slope shall be included. (4) A profile of the critical slope geometry showing the various layers including the proposed fill surface, final cover, mitigation berms, lifts or cells of waste, fluid levels, or any feature that may serve to reduce the stability of the slope or may represent a potential failure surface; and the proposed ground surface, soil or rock layers and structural features. (5) The engineering properties of the refuse and other layers making up the site, shall be analyzed when determining the critical slope. These properties shall include a site-specific assessment of the strength parameters, the unit weight and, if using Subsection (c) (11) of this Section, the shear wave velocity of each of these layers. (6) An assessment of the engineering properties of the underlying foundation materials under both static and dynamic conditions based on field and laboratory tests as determined necessary by a registered civil engineer or certified engineering geologist. (7) The maximum expected horizontal acceleration in rock at the site determined for the Maximum Probable Earthquake (MPE) as defined in CDMG Note Number 43 , "Recommended guidelines for determining the Maximum Credible and the Maximum Probable Earthquakes, " February 1975, which is incorporated by reference. III 7 .8-20 (6/18/90)