Agenda Packets - 1983/06/27 - Laserfiche WebLink

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Mr Willard Hama May 3, 1976 n Page two r excavate the fill and organic soils from within the building areas at the time construction commences. A granular fill could then be placed in the excavation in a controlled manner (compacted and tested in thin lifts) to specified grades. The building foundations could then be placed directly on the controlled fill or underlying natural silty sand soils. Caution should be taken to be certain that an appropriate lateral excavation oversize is maintained outside the foundation. That is, the excavation should extend laterally 1' out- side the edge of the footings for every foot of fill to be placed below bottom of footing elevation. Utilizing this method will also provide adequate support for the floor slab. A less desirable approach would be to place the fill soils over the existing fill and organic materials and thentrench excavate the founda- tions down to the underlying silty sand at the time of construction. This procedure would provide for adequate frost protection of the foundation (assuming 3' of fill was placed above the organic soils). Again, caution will be necessary to assure the foundations are de- finitely carried to the natural silty sand soils and the organic soils have undergone sufficient consolidation under the weight of the added fill to provide support for the floor slabs. Consolidation of organic soils can continue to occur for a considerable length of time. Therefore, a settlement monitoring program would be necessary to determine the .magnitude of settlement already experienced before placing on -grade slabs. We would recommend that any fill placed within the house area be surface compacted. Regardless of which plan of foundation construction is utilized, we would recommend that a soils engineer be contacted to inspect the foundation excavations to assure the foundation system (compacted fill or footings) is placed on the underlying natural silty sand. Also, compaction tests should be taken in any fill utilized for any portion of the structure. As the water level appears to be very high in this area, we would recommend that a minimum of 6" of free draining sand be placed below any floor slab and a drain tile system be constructed to control any fluctuations in the ground water table. As deep penetration borings were not placed within the building con- fines, we cannot warrant the soil conditions below our shallow hand auger borings. However,. according to our available geological data, the likelihood of encountering inferior soils at depth is quite remote. If we can be of further assistance to you, please contact us ruly yours W1_L4a A-,� Phillip Me sner Soils Engigi�neering Inspector Thomas K Smith E.l%► S Phl/TKS/rs CZ it W