4808 BELVEDERE AVE 2016-01-01 MF Import

Timberbuild Homes JN 05357 September 20, 2005 Page 3 The test pits conducted for this study and the previous test boring generally revealed native, mcdium-dense, slightly silty sand at depths ranging from approximately 4 to 6 feet below the grcund surface. This soil became denser below approximately 10 feet. The proposed residence can be founded on conventional foc�tings that bear on the medium-dense or denser sand or on structural fill placed over this competent soil. Some overexcavation may be needed to remove the upper loose soils in the residence area. One signiflcant geotechnical engineering aspect of this project is the significant depth of the excavation on the eastern side of the residence. Cuts of up to about 15 feet are proposed within about 5 feet of the eastern property line. The site soils should be temporarily exc2vated no steeper than approximately 1:1 (Horizontal:Vertical), therefore cuts that are taller than approximately 5 feet cannot be made within the property. One option for the taller cuts is to obtain a temporary excavation easement fr;,m the eastem propeRy owner te extend the excavation farther to the east. If this easement cannot be obtained, then temporary shoring would be needed. Details regarding excavation shorin�; are given in a later section of this report. The site soils below the existing fill soil and upper, organic soil is slightly silty, gravelly sar�d. This soil can readily be compacted as structural fill provided the moisture content of the sand is near its optimum moisture condition and vibratery equipment is used. The moisture content will likely only be over the optimum moisture content during extended periods of wet weather or if the sand is left exposed during periods of precipitation. The sand will likely became dry during the normally dry summer and early spring months. Water may have to be added to the sand to achieve a better moisture condition for compaction during e�ctended dry weather. A rockery that is up to approximately 8 feet in height and placed against er.cavated soils is proposed on the southem side of the driveway, while a rockery that will be placed against as much as 8 feet of fill is proposed on the westem side of the driveway where it crosses the existing ravine. We believe that both oi these cases are suita5le. We have included details for both a cut rockery situation and a fill rockery situation at the end of this report as Plates 5 and 6. The erosion control measures needed during the site development will depend heavily on the weather conditions that are encountered. While site clearing will expose a large area of bare soil, the erosion potential on the site is relatively low due to the gentle slope of the ground. We anticipate that a silt fence will be needed around the downslope sides oi any cleared areas. Rocked construction access roads should be extended into the site to reduce the amount of soil or mud carried off the property by trucks and equipment. Wherever possible, these roads should follow the alignment of planned pavements, and trucks should not be allowed to drive off of the rock-covered areas. Existing catch basins in, and immediately downslope of, the planned work areas should be protected with pre-manufactured silt socks. Cut slopes and soil stockpiles should be covered with plastic during wet weather. Following rough grading, it may be necessary to mulch or hydroseed bare areas that will not be immediately covered with landscaping or an impervious surface. The drainage and/or waterproofing recommendations presented in this report are intended only to prevent active seepage from flowing through concrete walls or slabs. Even in the absence of active seepage into and beneath structures, water vapor can migrate through walls, slabs, and floors from the surrounding soil, and can even be transmitted from slabs and foundation walls due to the concrete curing process. Water vapor also resulls from occupant uses, such as cooking and bathing. E.•cessive water vapor trapped within structures can result in a varietY of u�desirable conditions, including, but not limited to, moisture problems with floonng systems, excessively moist air within occupied areas, and the growth of molds, fungi, and other biological organisms that may GEOTECH CONSULTANTS. INC.