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4 ENVIRONMENTAL ANALYSIS bw 4.7 GEOLOGY,SOILS,AND SEISMICrrY we from landslide hazards. Rather,failure of permanent reclamation slopes would adversely affect successful reclamation efforts and could lead to future maintenance challenges and excessive erosion initiated by the slope failure. r. The Geomatrix slope stability analysis conducted for the proposed quarry project did not rely on site-specific subsurface soils engineering data and therefore does not necessarily represent the .� actual site conditions. Although the analysis did include a sensitivity analysis to account for some inherent uncertainties in the input data,there remains a need to further assess site geologic conditions,especially considering the potential for instability during the seismic ground shaking condition over the short and long term. In order to achieve a greater level of certainty that the temporary slopes and the permanent slopes remain stable and do not adversely impact workers, ' quarry operations,or reclamation efforts under proposed temporary and permanent ` configurations,the following mitigation measures ensure that impacts associated with static and dynamic slope instability hazards remain less-than-significant. 4- Mitigation Measure 4.7.1a: Site-Specific GeotechnicaUSlope Stability Investigation Prior to implementation of the proposed mining project,the applicant shall conduct a site-specific geotechnical/slope stability investigation to verify and update findings in the preliminary study prepared by Geomatrix in 2002: The geotechnical/soil stability investigation shall include r appropriate, site-specific geologic exploration and engineering soil testing to adequately assess the soil properties and the soil strength characteristics beneath the proposed site. The geotechnical/slope stability investigation shall use soil data collected on the proposed site from �. the proposed mining area to perform a slope stability analysis. The slope analysis shall consider the stability of the proposed temporary and permanent slopes and determine site-specific values for factors of safety under static and seismic loading conditions. The geotechnical/slope stability analysis shall be conducted,reviewed, and stamped by a California registered geotechnical engineer and California certified engineering geologist. The slope stability analysis shall be adequate to demonstrate that the proposed slopes would be maintained with factors of safety ` required by Chapter 9-1415-3 of the San Joaquin County Development Title,Ordinance for Quarry Excavations. If the results of the slope stability analysis indicates potential slope instability or if the factor of safety values are below those required by Chapter 9-1415-3 of the San Joaquin County Development Title, Ordinance for Quarry Excavations,the applicant shall develop a feasible and cost effective slope engineering alternative to increase the factor of safety .. and thereby reduce the potential for slope failure.Feasible engineering alternatives may include, but are not limited to,reduction of slope, intermediate terraces, increased drainage, or buttressed fill at the slope toe. As required,the completed geotechnical/slope stability investigation and ., recommendations shall be submitted to the San Joaquin County Development Department and engineering recommendations shall become part of the project specifications. Mitigation Measure 4.7.1b: Safety Program for Activities Near Steep Temporary Slopes Prior to project implementation,the applicant shall prepare for inclusion into the site Health and Safety Plan,a safety plan element to address worker safety near unsupported,non-engineered RMC Pacific ve,nnes Quarry Mining arid Reclamation»nJect 4.7-21 ESA i 203015 Ada n,smut a Draft EIR Mamh 2004