1318 37TH ST 2018-01-02 MF Import

James Pirie JN 97072 March 19, 1997 Page 3 Groundwater Neither groundwater seepage nor %'et soils were observed in our explorations. Since the test pits were conducted following a wet winter, ..his indicates that substantial groundwater seepaya would likely not be encountered on most portions of the site during excavation. It should be noted that groundwater levels vary seasonally with rainfall and other factors. We anticipate that groundwater could be found between the near -surface, weathered soil and the underlying dense sands, and in more permeable soil layers withir, the dense sands. This is most likely to occur in low areas of the property. CONCLUSIONS AND RECOMMENDATIONS General Based on our observations and the results of our explorations, the proposed site development appears feasible from a geotechnical engineering standpoint. The presence of silty, moisture - sensitive soils and the extensive grading that is planned appear to be the most significant geotechnical concerns. Conventional foundations can be used to support the buildings and retaining walls. Cut portions of the buildings should bear on medium -dense to dense, native soils. No more than 5 feet of structural fill placed above the medium -dense to dense, native soils should underlie footings. This reduces the potential for excessive differential settlement throughout the buildings. It will also likely be necessary to extend columns and foundation walls beneath portions of the building to limit differential settlement. Floors and garage slabs c.ii be supported on native soils or structural fill. All topsoil and existing `II should be removed from slab or pavement areas before placing structural fill. Slabs over deep fills should be reinforced with steel bars. This will limit, but not prevent, differential slab settlement and cracking. Flexible fill walls, such as geogrid-reinforced rockeries or modular block walls, should be considered for parking areas where new deep fills will be placed. These walls can tolerate more settlement than conventional concrete walls without structural damage. The on -site soils are silty and fine-grained, making them moisture -sensitive. Reuse of the native silty sands as structural fill will only be possible during dry weather and if the excavated soils are prevented from becoming wet prior to placement and compaction. No wet soils were observed in our explorations. If very moist to wet soils are encountered during earthwork, they will need to be dried prior to compaction. This is generally only possible during hot, dry weather. Adequate compaction of all fill, including utility backfill, for structural areas must be completed in accordance with our recommendations to limit the potential for settlement. Erosion control measures will be necessary at this site during wet weather. As a minimum, rock construction entrances should be provided and silt fences should be installed along the downslope sides of the property. Subgrades for footings and slabs should be protected with a 2- to 4-inch layer of gravel. This reduces subgrade disturbance due to foot traffic. Additional erosion and subgrade protection measures may be necessary, depending on the conditions encountered during construction. GEOTECH CONSULTANTS, INC. �/�