16 ATTACHMENTS - Laserfiche WebLink

Project No. JB-569 20 June 2006 Page 3 3.2 Subsurface Undocumented fill was encountered in Boring B-1 to a depth 4 feet below existing grade at the time of drilling. We assume that fill was placed over the existing slope at the time of grading for the existing residence. Approximately 5 feet of fill was also encountered in Boring B-3. This area appears to have been graded to provide a level pad in the area of Lot 3. Based on the topography, it appears up to 8 feet of fill may have been placed in the area. There may be varying depths of fill in areas beyond or between our exploratory borings. In general, the native soils consisted of stiff to very stiff silty clay and gravelly clay and medium dense to very dense clayey sand and silty sand. Laboratory testing indicates that the near-surface soils have a moderate expansion potential. Groundwater was encountered not encountered below existing grade in borings at the time of drilling. We expect groundwater levels to fluctuate due to variations in rainfall, groundwater recharge, and site conditions. 4.0 SEISMIC/GEOLOGIC CONSIDERATIONS 4.1 Seismic Geologic references indicate that no fault trace designated active or potentially active passes through the subject property. Table 1 lists the distance from the fault, the maximum moment magnitude, the slip rate, and fault type for local faults. The subject site is located in Zone 4 as defined by the Uniform Building Code (1997 edition) on Figure 16-3, Seismic Zone Map of the United States. Based on the soils encountered in the borings the most appropriate Soil Profile Type would be S~. Table 1 ACTIVE FAULTS AND CHARACTERISTICS Fault Distance' MEZ Slip RateZ Fault Type' Ikm) (mm/yrl Calaveras (north) 6 6.8 6.00 B Greenville 14 6.9 2.00 B Hayward (south) 15 6.9 9.00 A San Andreas (peninsula) 45 7.1 17.00 A San Gregorio 57 7.3 5.00 A 1. CDMG, Maps of Known Active Fault, Near-Source Zones in California and Adjacent Portions of Nevada, 1997. 2. CDMG, Probabilistic Seismic Hazard Assessment for the State of California, 1996. ~Korbmacher Engineering, Inc.