3723 RUCKER AVE Geotech Report 2018-01-02 MF Import

� Floor Slaba Building slab areae placed over the old fill should be overexcavated at least � one foo[ and replaced with structural fill. We recommend [hat at least four inchea of a free-draining gravel, such as 1/4 to 3/8-inch pea gravel be pleced beneath the ala6 to act as a capillery break. In areas where dsmp „ floora are undesireble, a plastic membrane with a thickness of ten to txelve �� mils ahould be placed above the gravel to uct as a vapor barrier. The membrene may be covered by an inch or so �' sand to protect it from damage during construction. We also suggest thac the slab be struc[urally separated � from the building walls and allowed to "float". -� , � Norizontal Loads Horizontal structural loads carried [o the foundations may be resisted by � fric:ion forcea on the base of foundations and hy passive resistance acting againa[ rhe sides of footings. A coefficient c�f friction of 0.3 may be used � between concrete and soil. Reais[ance to lateral loads may also be computed � as passive earth pressures exerted by the soils adjacent to the foundations. { To represent these passive pressures, we recommend using an equivalent fluid � weight of 250 pounds per cubic foot where the footings are poured "neat" against undisturbed soil, or where the backfill is compacted in accordance ^ vith rhe requirements for structural fill. &etaininQ Walls Retaining walls, including the foundation walls along the north nnd east aides of the building, should be designed to resist active lateral earth pressurea imposed on them hy the soils behind them. We recommend that this design pressure be taken as that imposed by an equivalent fluid weighing 45 pounda per cubic foot. It is assumed that walls will be free to deflect at ttie top and will behnve as cantilever wa11s. If this is not the case, the walls ahould be designed for an additional uniform pressure of 75 pounds pe: square foot. The active lateral pressures discussed here may be resisted by [he design pressures give in the preceding section of this report. Retaining walls must be provided with adequa[e drainage to prevent buildup of hydrostatic pressures Uehind them. Surface and Subsurface Drainafte Surface gradien[s should be created to direcl runoff away from the building and towards suitable dischsrge facili[ies. Water should not be allowed to pond at any location on the site. We recommend perimeter drains be constructed around all footings. Roof gutter lines should be separa[ely tightlined and discharged in[o adequa[e drainage facilities. Prniorr Nn T_�'34 P•�..� f.