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Pacific Ridge — DRH, LLC ES-8528.01 <br /> July 18, 2022 Page 8 <br /> Wet-Season Grading <br /> Earthwork activities that occur during the wet season may require additional measures to protect <br /> both structural subgrades and soil intended for use as structural fill. Site-specific <br /> recommendations can be provided at the time of construction and may include leaving cut areas <br /> several inches above design subgrade elevations, covering working surfaces with crushed rock, <br /> protecting structural fill soil from adverse moisture conditions, and additional TESC <br /> recommendations. ESNW can assist in obtaining a wet season grading permit if required by the <br /> governing jurisdiction. <br /> Void Space Restoration <br /> The process of removing the existing structure may produce voids where old foundations are <br /> removed and where crawl space areas may have been present. Complete restoration of voids <br /> from old foundation areas must be executed as part of the subgrade preparation activities. The <br /> following guidelines for preparing subgrade areas should be incorporated into the final design: <br /> • Where voids and related demolition disturbances extend below planned subgrade <br /> elevations, restoration of these areas should be completed. Structural fill should be used <br /> to restore voids or unstable areas resulting from the removal of existing structural <br /> elements. <br /> • Recompact, or overexcavate and replace, areas of existing fill exposed at the design <br /> subgrade elevations. Overexcavations should extend into competent native soils and <br /> structural fill should be utilized to restore subgrade elevations, as necessary. <br /> • ESNW should confirm subgrade conditions, as well as the required level of recompaction <br /> and/or overexcavation and replacement, during site preparation activities. ESNW should <br /> also evaluate the overall suitability of prepared subgrade areas following site preparation <br /> activities. <br /> Foundations <br /> After completing earthwork activities in accordance with recommendations in this report, the <br /> proposed structures can be supported on conventional spread and continuous foundations <br /> bearing on undisturbed, competent native soil, recompacted native soil, or new structural fill. <br /> Where loose or unsuitable soil conditions are encountered at foundation subgrade elevations, <br /> compaction of the soils to the specifications of structural fill, or overexcavation and replacement <br /> with suitable structural fill will likely be necessary. A representative of ESNW should confirm <br /> suitability of foundation subgrades at the time of construction. <br /> Due to the high moisture sensitivity of the site soils, foundation subgrade areas should be <br /> protected from wet weather or areas of remediation should be anticipated; a layer of crushed rock <br /> can be considered to protect foundation subgrade areas. If structural building pads are disturbed <br /> during wet weather, remediation measures such as cement treatment or overexcavation and <br /> replacement with rock may be necessary in some areas. Additionally, perched groundwater <br /> seepage may create unsuitable soil conditions above the hardpan which would require aeration, <br /> cement treatment, or replacement with crushed rock. <br /> Earth Solutions NW, LLC <br />