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f JAVID L. NELSON AND ASSOCIATES, INC. <br />Consulting Engineering Geology <br />July 13, 1990 <br />-- Project No. 9490 <br />Page 3 <br />orange -brown, loose, silty sand with roots. Where fill is not present, this <br />root tons is covered with about 0.1 to 1.0 feet of topsoil. The areas of <br />fill were generally found to vary from at least 2 to 2.5 feet thick, and to <br />consist of brown and grey to black, loose, mixed silty fine send, silty sand, <br />organics and some debris. It appears that this fill was placed during past <br />grading and clearing operations within the site, and possibly some of the fill <br />was debris hauled in from off site. <br />HYDROLOGIC CONDITIONS <br />Ground water was encountered within most of the test pits as perched water <br />conditions. We found seepage and wet conditions within the more permeable <br />soils perched a'�ove the finer grained Whidbey Formation. This perched ground <br />water is expected to flow down gradient to the north and east. This type of <br />ground water condition is common for upland areas underlain by relatively <br />impermeable soils, and tends to be somewhat seasonal. We expect this seepage <br />to decline markedly during the drier summer months; however, since we have not <br />monitored the site through the summer months, the year round presence of <br />groundwater could exist. We did not encounter any evidence of outcropping <br />ground water within the easterly slope area, but some evidence of seepage <br />along the norther steep cut slope was noted. <br />CONCLUDING OPINIONS <br />General <br />In general, we conclude that the evaluated site area should be compatible <br />with,the proposed residential development. The existing fill placed on the <br />steep slopes is considered unsuitable for support of structure foundations, <br />and is only marginally stable. Additional fill should not be placed on the <br />slope, unless designed and placed under direction of the geotechnical <br />consultant. Foundations for the sirvctures should extend through the fill and <br />loose weathered soils to the medium dense to dense and stiff to hard sands and <br />silts, or glacial till, that underlies the site. Where the foundations are <br />founded on the moderately steep slope, they should extend a minimum of 1 foot <br />into these soils. This would mean excavation depths on the slope on the order <br />