1600 121ST ST SE 2016-01-01 MF Import

Test pits excavated on the hillside on the western portion of the property did not indicate any or at most very thin deposits of unsuitable materials. Therefore, we recortmend that the upper unsultable soils be excavated and buildings be supported on conventional spread footings founded either on the natural Glacial T111 (Unit 4) or compacted structural fill. In the central and eastern portions of the site, the unsuitable soils arc much deeper and any excavation to remove them may encounter groundwater. Therefore, it is recortmended that buildings 1n these areas be supported on driven piles. At this time, design site grades are not known; however, the placement of fill in the central and easterly portion of the site will most likely cause settlement of the underlying Fill and Peat. Such mavements may cause distress of pavements and utilities. Filling should be placed as early as possible so that some of the mavement will accur prior to utility installation and paving. A temporary surcharge fill (fill placed higher than the design site grades) may be placed at critical locations to reduce post-construction movements. Typically, a surcharge must remain in-place for at least one to two months to be effective. Even so, some post-construction settlement may still occur, depending on design grades. In the easterly portion of the site, differential movements should be expected between the pile-supported structures and the adjacent ground surface which will settle relative to the buildings. If possible, utilities should be designed to be relatively settlement-tolerant, and provisions should be made to accept some movement where the utilities enter the buildings. Further recommendations regarding both conventional spread footings and pile faundations are discussed in more detail in the following paragraphs. 5.2 Foundations t .. 5.2.1 Spread Footings Footings may be used throughout the site if they are founded in the native Glacial Till (Unit 4) or on structural fill founded on the native Glacial Till -' (Un1t 4) and compacted to at least 95 percent of ASTM D 1557 78. Spread footings should be designed based on the following recommended values: Maximum Allowable Bearina Pressures: 3000 psf 2500 psf Glacial Till (Unit 4) Compacted Fill, (95 percent of ASTM D 1557) These values may be increased by 1/3 for short term wi�d and seismic loadings. Minimum Embedment: Perimeter footings: 18 inches below adjacent grades Interior footings: 12 inches below adjacent grades Golder Assoclates