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Pacific Ridge — DRH, LLC ES-8528.01 July 18, 2022 Page 7 Structural Fill Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway, permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and compacted during site grading activities should meet the following specifications and guidelines: • Structural fill material Granular soil* • Moisture Content At or slightly above optimum** • Relative compaction (minimum) 95 percent (Modified Proctor)*** • Loose lift thickness (maximum) 12 inches * Existing soil may not be suitable for use as structural fill unless at(or slightly above)the optimum moisture content at the time of placement and compaction. ** Soil shall not be placed dry of optimum and should be evaluated by ESNW during construction. ***Minimum relative compaction of 90 percent may be feasible for mass grading activities (from a geotechnical standpoint) and should be evaluated by ESNW during construction. With respect to underground utility installations and backfill, local jurisdictions may dictate the soil type(s) and compaction requirements. Unsuitable material or debris must be removed from structural areas, if encountered. In-situ and Imported Soil The in-situ soils observed at the subject site have a high sensitivity to moisture and were generally in a moist to wet condition at the time of exploration. Soils anticipated to be exposed on site will degrade rapidly if exposed to wet weather and construction traffic. Compaction of the soils to the levels necessary for use as structural fill may be difficult or impossible during wet weather conditions. Soils may be encountered during site excavations that are excessively over the optimum moisture content and will likely require aeration or treatment prior to placement and compaction. Conversely, soils that are substantially below the optimum moisture content will require moisture conditioning through the addition of water prior to use as structural fill. An ESNW representative should determine the suitability of in-situ soils for use as structural fill at the time of construction. Imported soil intended for use as structural fill should be evaluated by ESNW during construction. The imported soil must be workable to the optimum moisture content, as determined by the Modified Proctor Method (ASTM D1557), at the time of placement and compaction. 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 percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction). Earth Solutions NW, LLC