4920 EVERGREEN WAY STAPLES Geotech Report 2022-10-25

Geotechnical Engineering Report Staples Rockery Failure ■ Everett,Washington lierracon March 8, 2019 • Terracon Project No. 81175122 removed and replaced with structural fill. We recommend that proof-rolling of the subgrade be observed by a representative of our firm to assess the adequacy of the subgrade conditions and identify areas needing remedial work.We recommend that this procedure not be performed during wet weather. During wet conditions, systematic probing should be used to evaluate the subgrade. 4.2.2 Temporary Cut Slopes The contractor may elect to perform temporary cuts and/or trenches to support retaining wall construction. Based on the available information, the temporary excavations could be expected to occur in loose fill or loose to medium dense, cohesionless soil. Temporary slope stability is a function of many factors, including the following: • The presence and abundance of groundwater • The type and density of the various soil strata • The depth of cut ■ Surcharge loading adjacent to the excavation • The length of time the excavation remains open It is exceedingly difficult under the variable circumstances to pre-establish a safe and "maintenance-free" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. It may be necessary to drape temporary slopes with plastic or to otherwise protect the slopes from the elements and minimize sloughing and erosion. We do not recommend vertical slopes or cuts deeper than 4 feet if worker access is necessary.The cuts should be adequately sloped or supported to prevent injury to personnel from local sloughing and spalling. Construction site safety is the sole responsibility of the contractor who controls the means, methods and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean that Terracon is assuming any responsibility for construction site safety or the contractor's activities;such responsibility shall neither be implied nor inferred. 4.2.3 Material Requirements Compacted structural fill should meet the following material property requirements: 1 Responsive • Resourceful • Reliable 7