COMPLIANCE INFO_1993-1994 - Laserfiche WebLink

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Mr. Mike Niblock January 7, 1993 Page 6 report which indicate a factor of safety for the critical slopes of at least 1 . 5 under dynamic conditions . In addition, the CIWMB should receive all documentation relating to slope and foundation stability studies and design. What is the potential for significant subsidence during substantial earth shaking? Page III .J. 11 of the DEIR states, "It is possible that, over the life of the project the on-site soil supply would be insufficient in quality or quantity to meet cover requirements and off-site import would be required. In the event soil is required to be imported from off-site, further CEQA documentation may be necessary. Hydrology, Geohydrology, and Water Quality Page III .K. 12, 13 indicates that the net effect of realigning the North *Branch of the South Fork of Little Johns Creek "has not been quantified, but would not be expected to cause significant impacts to erosion and deposition on the site or in receiving waters . The new creek channel would have a geomembrane liner, covered with dirt and rip rap. The proposed conceptual channel geometry has side slopes of 1 : 1 with a bottom of 20 feet . " The realignment of the creek could alter the potential erosive action and deposition on the site . Improper design could result in stream stability problems . CIWMB staff are especially concerned about slope stability of the proposed channel banks . Side slopes of 45 degrees could result in slope failure and subsequent erosion into the landfilled waste. CIWMB staff request that the net effect of realigning the creek be quantified through appropriate modelling. The interface between the liner and native soil should be analyzed. Grading of the side slopes should be based on site-specific factors to guarantee slope stability. { How will the project proponent ensure that the side slopes won' t fail, resulting in erosion into the landfill? Will the liner be anchored to the side slopes? What type of geomembrane and thickness will be used for the creek channel liner? Additional mitigation measures should be adopted which x _nsure the protection of the landfill . q Page III .K. 4 states, "portions of the project site are subject . flooding during the 100-year storm. " Mitigation .Measure .. 2 states, "The project includes channel reconfiguration and _ --calized flood protcti eon berms to isolate the la _ fill s=a faces from floodwaters . " Where will the flood protection