7010 COLBY AVE 2023-06-01 - Laserfiche WebLink

Mr. Paul Korenovsky ES-6067 June 20, 2018 Page 6 In-situ and Imported Soils From a geotechnical standpoint, it is our opinion in-situ soils may be suitable for use in structural fill applications, provided the moisture content of the soil is at (or slightly above) the optimum moisture content at the time of placement and compaction. Successful use of native soils as structural fill will largely be dictated by in-situ moisture contents during construction. The on-site soil deposits should be considered moisture sensitive. Where necessary, imported soil intended for use as structural fill should consist of a well- graded, granular soil with a moisture content that is at (or slightly above) the optimum level. Imported soil intended for use as structural fill should consist of a well-graded, granular soil with a fines content of 5 percent or less (where the fines content is defined as the percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). Sub grade Preparation g p Following site stripping, cuts and fills will be completed to establish proposed subgrade elevations across the site. ESNW should observe the subgrade areas during initial site preparation activities to confirm soil conditions are as anticipated and to provide supplementary recommendations for subgrade preparation. Complete restoration of voids resulting from current demolition and grading activities must be executed as part of overall subgrade and building pad preparation activities. The following guidelines for preparing building subgrade areas should be incorporated into the final design: • Where voids and current demolition disturbances extend below planned subgrade elevations, restoration of these areas should be completed. Structural fill should be used to restore voids or unstable areas resulting from the removal of existing structural elements. • Recompact, or overexcavate and replace, areas of existing fill exposed at building subgrade elevations. Overexcavations should extend into competent native soils, and structural fill should be utilized to restore subgrade elevations as necessary. • ESNW should confirm subgrade conditions, as well as the required level of recompaction and/or overexcavation and replacement, during site preparation activities. ESNW should also evaluate the overall suitability of prepared subgrade areas following site preparation activities. Structural Fill Structural fill is defined as compacted soil placed in foundation, slab-on-grade, and roadway areas. Fill placed to construct permanent slopes and throughout retaining wall and utility trench backfill areas is considered structural fill as well. Soils placed in structural areas, including slab- on-grade, utility trench, and pavement areas, should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 95 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D1557). Earth Solutions NW.LLC