3A Public Hearing 2007 0507 - Laserfiche WebLink

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SCOPE - The scope of this consultation is to provide a feasibility evaluation of the proposed development, with a geologic hazards evaluation and preliminary engineering design for probable site grading and foundation types. BACKGROUND - The site is located at the junction of MacArthur and Broadmoor Boulevards and Herma Court, as shown on the Vicinity Map, Figure 1. The site consists of six contiguous lots, with current development consisting of single-story, wood-frame buildings and paved lots, as shown on the Site Plans, Figures 2a and 2b. There is no known contamination of the soils, no known prior use of the site other than the existing residential and commercial development, and no known underground structure(s) on the property. PROPOSED CONSTRUCTION - The proposed development consists of 4 mixed use buildings and paved parking areas, as shown on the Proposed Development Plan, Figure 3. The proposed buildings are to be one to three-story wood-frame buildings, with relatively light foundation loads, typical of this type of construction. No significant grading will be needed for development. SITE CONDITIONS - The property is nearly level. Soil is probably quite deep, with bedrock found at shallow depth only on the nearby hills east of the property. Vegetation consists of numerous trees of various sizes and grasses, plus landscaping plants. Site grading is expected to be relatively minor, with grade changes of no more than 2 feet in depth, probably limited to the building pads plus driveways and roads. SOILS - According to the Soil Survey, the site soils are a complex of urban land and Danville silty clay loam. The urban land is developed property, with surface soil changes associated with development. The typical Danville soil consists of various clay layers. The soil is described as having a high shrink-swell potential, with a Plasticity Index of 10 to 30 and silt and clay fines (soil finer than a number 200 sieve) content of 50 to 75 percent. Corrosivity to uncoated steel is probably very high. The deposit contains minor amounts of other soils. BEDROCK MAPPING - The cited geologic maps indicate that the site is on the outwash alluvium from the nearby hills to the east. The alluvium probably includes all of the normal types of sediments. The bedrock under the alluvium is probably part of the melange of rock types shown on the hills to the east of the site (Crane 1988). A portion of the mapping by Crane is shown on Figure 4. Proposed Mixed Use Development 311 MacAtthur Boulevard, San Leandro, CA GU, Gf pn 9451706002 May 10. 2005 Page 2