5900 36TH AVE W PRE APP 015 - 032 - SOUNDVIEW BUSINESS CAMPUS - VERITAS Geotech Report 2025-04-22

Veritas Construction Inc ES-4011.03 June 17, 2016 Page 9 Revised June 22, 2016 ' Stripping Topsoil was encountered generally within the upper 4 to 14 inches of existing grades at the test pit locations. We estimate topsoil will be encountered with an average thickness of 10 to 12 inches (locally deeper areas, however, may be encountered). ESNW should be retained to observe site stripping activities at the time of construction so as to thoroughly assess the degree of required stripping. Over-stripping should be avoided as it is unnecessary and may result in increased project development costs. Topsoil and organic-rich soil is neither suitable for foundation support nor for use as structural fill. Topsoil and organic-rich soil may be used in non-structural areas if desired. Insitu and Imported Soils The moisture sensitivity of the on-site soils is characterized as moderate. Successful use of native soils as structural fill will largely be dictated by in-situ moisture contents at the time of placement and compaction. At the time of our investigation, in-situ moistures at-depth were generally near the optimum level. In general, soil that is at (or slightly above) the optimum moisture content at the time of placement and compaction may be used as structural fill. Conversely, soil that is found to be dry at the time of installation will likely require moisture conditioning (typically achieved through the application of water) prior to soil compaction. Soil encountered during site excavations that is excessively over the optimum moisture content will likewise require moisture conditioning (typically achieved through soil aeration) prior to placement and compaction. It should be emphasized native material should never be placed and compacted dry of the optimum moisture content, especially in site utility trench applications. If the on-site soils cannot be successfully compacted, the use of an imported soil may be 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. During wet weather conditions, 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 111 percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). 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 also considered structural fill. Soils placed in structural areas should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 90 percent, based on the laboratory maximum dry density as determined by the Modified Proctor Method (ASTM D1557). Soil placed in the upper 12 inches of slab-on-grade, utility trench, and pavement areas should be compacted to a relative compaction of at least 95 percent. Additionally, more stringent compaction specifications may be required for utility trench backfill zones depending on the responsible utility district or jurisdiction. ' Earth Solutions NW, LLC