75C - PH - BRISTOL EIR FROM WARNER TO ST. ANDREW

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results in a low potential for large area or focal ground subsidence due _ to earthquakes. Soil liquefaction is the phenomenon in which water - saturated, cohesion - less soil temporarily loses its strength when subjected to dynamic forces. Soils most vulnerable to liquefaction are those that are composed of saturated sands, in a loose to medium -dense condition, in areas where the water table is less than 20 feet deep. The probability of Liquefaction occurring in Santa Ana is relatively low, given the type of earthquake expected and the distance to active faults. Moderate to high potential subsidence and liquefaction areas within the subject segment of Bristol Street are shown on Figure 10, following. _ Only the extreme northerly portion is considered subject to a potential subsidence hazard. Most of the south half of the study area, between McFadden Avenue and Warner Avenue, is in an area classified as r within the highest potential liquefaction area. Between McFadden Avenue and First Street, the liquefaction hazard potential is considered ° moderate. From First Street north to Memory Lane, liquefaction potential is considered slight. 3. S_ oils Within the project area, there are no instances of undisturbed, natural soils. All surface areas have been modified or covered, due to construction activities or due to the planting of urban landscape materials. The soil types found throughout the project area are — importaut in terms of their characteristics which would support or ,r constrain further urban development and redevelopment, including the proposed street widening. The distribution of soil types found within the study area is shown on Figure 11, following. As described in the Soil Survey for this area, prepared by the U.S. Soil Conservation Service, these soils have the following characteristics: Chino Silty Clay Loam. Drained. Nearly level, on large alluvial fan. Moderately alkaline and calcareous throughout. If soil is bare, runoff is slow and erosion hazard slight. This soil is drained and the water table is more than 60 inches below the surface. The effective rooting depth is 60 inches or more. Depth to bedrock exceeds 60 inches. Moderate shrink -swell potential. Low risk of corrosion to concrete; moderate - high risk of corrosion to uncoated steel, depending on depth. 111 -4 75C -75