1329 MADRONA AVE Geotech Report 2022-10-25

Subsurface Exploration,Geologic Hazard,and lanowicz Property Geotechnical Engineering Report Everett,Washington Preliminary Design Recommendations accurately recorded throughout the test. The test anchors should be capable of holding the ultimate load without excessive yield or creep so that a factor of safety of at least 2.0 is achieved. A linear or near-linear relationship between the unit anchor stresses and related movement would indicate a successful anchor test. The other component of the anchor tests for the project would be proof-loading each of the production anchors to 130 percent of the design load. Each anchor should withstand this load for at least 5 minutes. If the creep in the first 10 minutes is less than 0.04 inches, then the anchor is considered acceptable. If the • elongation is greater than 0.04 inches, the load is held for an additional 50 minutes, and the movement readings are recorded at 10-minute intervals. If the creep rate in this additional period does not exceed 0.08 inches and is decreasing, the anchor is acceptable. The anchor should then be locked-off at the design load. The anchors should also be provided with secondary grout tubes in the event that anchor failure occurs during pullout proof-testing. After secondary grouting,the anchor can then be re-tested. • Subsequent to locking-off the tiebacks at the design load, all of the tieback holes should be backfilled to prevent possible collapse of the holes and any related consequences. Typically, CDF is used as backfill material; however, most non-cohesive mixtures are suitable (subject to approval by the geotechnical engineer)provided there is no bonding to the tierods. Since completion of the piling takes place below ground, the judgment and experience of the geotechnical engineer or their field representative must be used for determining the acceptability of each pile. Consequently,the use of the presented design information requires that all piles be inspected by a qualified geotechnical engineer or engineering geologist from our firm who can interpret and collect the installation data and observe the contractor's operations. AESI, acting as the owner's field representative, would keep records of pertinent installation data. A final summary report would then be distributed following completion of pile installation. 12.0 FOUNDATIONS We recommend that areas of proposed new foundations are supported by the native non-glacial sediments underlying the existing colluvium and landslide deposits. Based on the explorations performed for this study, we anticipate that suitable soils for foundation support are present below a depth of approximately 20 to 28 feet below the existing ground surface at the locations of our explorations,and must be capable of resisting a lateral load. Therefore,we recommend the use of a drilled pier or augercast pile foundation system for the proposed new foundations. 12.1 Augercast Piles We recommend cast-in-place concrete piles (augercast) be used for foundation support. The depth to the bearing stratum is in excess of 20 feet and therefore will preclude the use of May 10,2018 ASSOCIATED EARTH SCIENCES,INC. NSfta-170649E002-2-Projects}201706491KEIWP Page 17