1310 SE EVERETT MALL WAY Geotech Report 2022-10-25

Darden Restaurants, Inc. September 15,2011 Proposed Olive Garden—Everett,Washington Page 5 of 12 3.2 Site Preparation The planned building area should be stripped of asphalt and any other unsuitable near-surface material. Up to about 6 feet of fill was encountered in our subsurface explorations and thicker areas of fill could exist within the site. In our opinion the fill material may remain in-place within the building pad provided it is densified as recommended below. However, leaving the fill in-place does represent an increased risk for additional settlement of the building, given the uncertainty of the fill thickness throughout the building area. Although we believe that the increased risk of additional settlement is minimal, if such risk is not acceptable, the fill should be removed and replaced with Structural Fill. Vegetation should be removed from the existing landscaping islands. Removal of the landscaping islands will likely disturb the upper few feet of material, possibly requiring replacement with imported granular structural fill. The existing asphalt pavement within new pavement areas should also be removed and disposed off-site. However, we recommend that the existing pavement remain in place as long as possible to help protect the underlying moisture and disturbance sensitive soil. Existing utilities should also be located. Utilities to be abandoned should be properly capped off at the property boundary and removed. Utilities to remain should be re-routed around the new development as needed. Stripped material should be transported off-site for disposal or stockpiled for later use as fill in landscaped areas, as approved by the project landscape architect. Our test borings revealed silty soils that are sensitive to moisture. When such moisture sensitive soils are exposed to construction traffic, a loss of soil strength may result. After disturbance and when wet, these silty soils will rut and deflect significantly and do not provide adequate subgrade support and require remediation or moisture conditioning. It is not uncommon for construction equipment to severely disturb the upper six inches or more of the subgrade if site preparation work is performed while the soils are wet. This may result in the need for either undercutting and replacement of the disturbed soils or drying and re-compaction of the affected soils. Treatment of soft or excessively moist soils will be time consuming and will increase the project budget. Grading operations may involve handling these soils more than once in order to achieve proper placement and compaction. If unit prices for earthwork operations are established, they should be examined closely before the contract is executed. The construction budget should provide an allowance for stabilizing, re-compacting, or undercutting and replacing soft or loose subgrade soils. If undercutting is a pay item, then undercut volumes should be determined by field measurement. Methods such as counting trucks should not be used for determination of undercut volume, as they are less accurate. Following asphalt removal, site stripping, and lowering of site grades where necessary and prior to placing any new fill, we recommend that the building pad soils be surface-compacted with a smooth drum vibratory roller. The roller should possess a minimum static weight of 15 tons and make six passes across the building pad area (three in both perpendicular directions). The intent of this recommendation is to densified the soils within the upper three feet of finished or existing grade (whichever is deeper) to at least 95 percent of the soil's maximum dry density per ASTM D698. Following densification, test pits and compaction testing should be performed by the geotechnical engineering representative to confirm that the soil's within the upper three feet of finished grade have been adequately compacted. All test pits should be backfilled with soil compacted to at least 95 percent of the soil's maximum dry density (ASTM D698). Dependent