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DAVID L. NELSON AND ASSOCIATES, INC. <br />Conculting Engincering Geology <br />February 18, 1986 <br />Project No. 1A86 <br />— Page two <br />— shallow hand-excavated test holes east of the site. Artificial fill was <br />�bserved in excavations within the proposed footing areas and within a steep <br />_ fill slope area to the south. This f911 material appears to consist of mixed <br />silt, sand, gravel, organics and some debris, !n a generally non-uniform state. <br />The fill appears to occur within the majority of the soutl�easterly portion <br />of the proposed building area, and appears to thin toward *he north and west. <br />An existing steep fill slope occurs along the south side of the proposed <br />— residence area, which extends into a lower elevation swale area. No apparent <br />water was observed flowing within the swale area. Some surface saturation <br />- of the fill areas was observed, thought derived from recent precipitation. <br />inions <br />Since no exploration was performed by us, we cannot a��equately determine <br />stability of the fill areas. Assuming that the fill material has been on <br />- site for several years, some relative stability could be expected. However, <br />the occurrance of the fill body upon a relatively steep slope area leads us <br />- to believe that instability within the fill body could occur at any time, <br />. and could be negatively enhanced with increased precipitation periods, any <br />moderate to severe seismic event and/or conditions not presently known. <br />Placement of the proposed residence within the existing fill area may create <br />future conditions where remedial repair to complete reconstruction of the <br />a�fected foundation areas.may be necessary. <br />__ Recomnendations <br />,-- We believe the most effective means of achieving foundation support and <br />�, reducing potential settlement beneath the footing areas would be to place <br />�, the proposed foundations within the underlying natural soils, located at <br />some depth below existing grade. This would require excavations through the <br />surficial artificial fill and at least 24" into the underlying dense natural <br />,r soils. In doing so, maximum allowable soil pressures of 3000 pounds per <br />'� square foot (psr) could be expected. This may necessitate stepped type <br />