2505 PACIFIC AVE 2018-01-01 MF Import

Sierra Constructio� Services , Inc. JN 92276 July 1 , 1992 Page 4 CONCLUSIONS AND RECOMMENDATIONS r.FwFa�i eased on the soil conditions observed in the test bori �gs, it ' is our opinion that the building may be constructed using conventional foundations and a slab-on-grade floor. eecause of extensive past development on the site end the presence of � 2 to 7 feet of fill and topsoil on the site, considerable effort will be required to strip the site of all old foundations , debris , utilities , and loose soils . We recommend that the building area be stripped down to the native stiff silt soils and then imported clean pit-run sand and gravel be placed as structural fill over the silt to final grade. If extensive fill is required, it may be possible to sandwich a lesser quality fill between e clean gravel layer placed on the silt and a clean sand and gravel layer which would serve as the sleb-on-grade subgrade. The feasibility of using lesser , quality fill will be dependent on weather conditions. The parking lnt subgrade preparation requirements will depend � on the proposed grades . In general , we recommend that the existing pavement be removed or broken into small pieces and left on site. Where there will be existing topsoil or fill within 18 inches of the final grade, the topsoil or fill should be stripped and removed . Some of the existing paving appears to have been placed over topsoil . The upper 12 inches of the subgrade should consist of structural fill compacted to 95 percent of the meximum density as determined by the Modified Proctor procedure. The on-site soils are silty and moisture sensitive. Earthwork will be most economical in the normally drY summer end early � fall months . If earthwork tekes place during wet weather, it wiil be necessary to use all imported clean, granular fill for , parking and building.areas and additional gravel would be required for the paving subgrade. The foundation bearing surfaces would also need to be protected from disturbence using lean concrete, clean gravel or crushed rock . The native silt soils are not acceptable for reuse as structural fill or retaining wall backfill . GEOTECH CONSULTANTS, INC.