1809 HOLBROOK AVE 2018-01-02 MF Import

Terhune Homes, Inc. JN 99028 February 25, i999 Page 2 The final logs represent our interpretations of the field logs. The stratification lines on the logs represent the approximate boundaries between soil types at the exploration locations. The actual transition between soil types may be gradual, and subsurface conditions can vary between exploration locations. The logs provide specific subsurface information only at the locations tested. The relative densities and moisture descriptions indicated on the test pit logs are interpretive descriptions based on the conditions observed during excavation. The compaction of backfill was not in the scope of our services. Loose soil will therefore be found in the area of the test pits. If this presents a problem, the backfill will need to be removed and replaced with structural fill during construction. Groundwater Groundwater seepage was observed in the two upslope test pits at depths of and 10 feet. The test pits were Ic`t open for only a short time period. Therefore, the seepage levels on the logs represent the location of transient water seepage and may not indicate the static, groundwater level. It should be noted that groundwater levels vary seasonally with rainfall and other factors. The absence of groundwater in our downslope explorations does not eliminate the possibility that groundwater could be encountered in future excavations. CONCLUSIONS AND RECOMMENDATIONS General Based on the observations made during our site visit, it is our opinion that construction of the proposed single-family residence is feasible from a geotechnical engineering standpoint. The house may be supported on conventional foundations bearing directly on the native, medium -dense to dense silty sand undcrlying the site. Some overexcavation will likely be required to expose competent, native soils for the downslope footings. We recommend that footings on the downslope perimeter and any deck footings be placed at least 5 feet below the existing c rounl surface. Permanent fill slopes benched into the existing grade should be inclined no steeper than a 2.5:1 (Horizontal: Vertical) inclination. Slopes over 4 feet hi in the crawl space should be covered with a skim -coat of concrete or shotcrete to prevent sloughing. Even a 2.5:1 (H:V) slope is subject to sloughing if the soil were to become dry. The erosion control measures needed during the site development will depend heavily on the weather conditions that are encountered. The existing slope consists of highly erodable, granular soils. Site clearing will expose a large area; surface water must be directed away from the slope, and bare areas should be covered with plastic and? revegetated as quickly as possible. We anticipate that a sil' fence will be needed around the downslope side of any cleared areas. Rocked construction access roads should be extended into the site to reduce the amount of mud carried off the property by trucks and equipment. 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. Geotech Consultants, Inc. should be allowed to review the final development plans to verify that the recommendations presented in this report are adequately addressed in the design. Such a plan GEOTECH CONSULTANTS, INC. //6