11419 19TH AVE SE Geotech Report 2018-01-02 MF Import

t� :ry 9.0 Poundations ;� Sprcad fooiings may be uscd for buildin�� siq�•port when founded on the dense, native sediments or stnictural fili placed as previously discussed, or on Cooting trenches as discusse�l in Section 9.1 for � footings requiring overezcavation. Footin�s will require overexcavation of approsimately siz feet down to native dense soils in the vicinity of EP-6 at the west end of proposed building A, The Site and Exploration Plan, Figure l, shows the approximate limit ofoverexcavation in this area. � Footings requiring overexcavation may be extendr.d down to native soils, or structural fill should be placed in 8 inch thick lifts compacted to 95% of ASTM: D1557 over the native soils up to footing � elevations. Based on the finished tloor elevations shown on the preliminary site plan, footings for buildings B, C, D, and the east end of building A can be founded on near surface dense native soil or structtual fill placed on dense soils. It is possibic [hat additional isolated areas of fill and soft soils � exist, that were not found during our investigation, due ro past grading and existing structures. Therefore, it is imperative that all footing excava[ions be evaluated by a representative of our firm, to deter.mine if additional overexcavation is required. � We recommend that an allowable foundation soil bearing pressure of 2,500 pounds oer square foot (ps� be utilized for design purposes, inciuding botlt dead and live loads. An increase of one-third � may be used For sliort-term wind cr seismic loading. Perimeter footings should be buried at least IS inches into the surrounding soil for frost protection; interior f::otings require only 12 inches burial. However, all footings must penetrate to the prescribed bearins;stratum(ur structural fil]) and � no footing should be founded in or above loose or highly organic material. r111 footings should have a minimum width of 18 inches for the one-story struchtre. iAnticipated settlement of footines founded on the approved bearing st:atum should be on the order of one inch or less. Ho�vever, loose soii not removed from beneath the footing excavations or � recompacted prior to footing placement could result in increased settlement. .411 footing areas should be inspected by a represen[ative of our firm prior to placing concre[e to verify that the soil conditions are as assumed in this report and that construction confom�s to the recommendations contained in � this report. Such ir_spections may be required by the governin� municipality. Perimeter footing drains should be provided, as discussed under the section on Drainage Consideratio�.s. t9.1 Footing Trenches As a�t altemative to backfilling overexcavated foo[ing trenches with structural fill, footing trenches � backfilled with controlled density filUlean mix concrete(CDF) that extend down to ''�e glacial till may be used for foundation support. � The trenches should have a minimum width equa( to the width of the footings plus at le:ut 6 inches on each side of the footing (or as designated by the Pield EngineedEngineering Geologist) and be excavated down to the dense natural soils. Because of the potential for caving, the actual trench ' width may be greater than specified. The use of a larger, track-mounted backhoe will geatly speed _, trench excava[ion over the use of a conventional, rubber-tired backhoe. In order to reduce disturbance of the bearing soils exposed in the trench, it is strongly recommended that the teeth of ' the backhue bucket be co��ered with a smoodi cutting edge. � �� ' MAYES :ESTING ENG/NEERS