2721 WETMORE AVE MARQUEE APARTMENTS 2023-06-28

Subsurface Exploration, Geologic Hazard, and 2721 Wetmore Preliminary Geotechnical Engineering Report Everett, Washington Preliminary Design Recommendations recorded during the verification test, where the load is generally held for an hour and any nail movement is measured. The creep measurements are commonly performed at either the 150-percent or the 200-percent point. Verification nails should be constructed exactly as the production nails will be constructed, including the same drilling equipment, driller, inclination, grout, etc. Verification test nails are commonly sacrificial nails that do not become incorporated in the shoring wall. As construction of the wall proceeds, proof-tests are conducted on approximately one of every 20 nails to verify that the soil conditions and installation methods have not changed. Proof-test procedures are similar to the verification procedures except that the final load is less (130 percent) and the creep measurements usually last only 10 minutes. Proof-test nails remain in the wall following testing and are an integral part of the shoring. We recommend that AESI monitor installation and testing of both the verification and proof nails. For design purposes, we recommend the following soil parameters be utilized: Moist Unit Weight: 130 pcf Friction Angle: 35 degrees Cohesion: 500 psf For design of soil nail anchors used in the shoring system, the anchor loads are transmitted to the surrounding soil by side friction or adhesion with the soil. For tiebacks installed with an air-rotary drill or hollow-stem auger in the glacial sediments, an allowable shaft friction of 1,200 psf can be assumed. For 6-inch-diameter pressure-grouted anchors, installed fully within glacially consolidated sediments, a shaft friction of 2,000 psf can be assumed. Figure 3 of this report presents lateral earth pressure values that can be used for design of the soil nail system. It should be noted that in calculating lateral earth pressures for the shoring system, the base of the wall should be considered to be at the foundation subgrade elevation. We do not anticipate that significant excavations below foundation subgrade elevation will be planned. The competence of the glacially overridden soils encountered at the site indicates that it is likely the soil nail anchor holes can generally be drilled and the anchors installed without the use of casing. However, caving should be expected in areas of groundwater seepage, and the contractor should be prepared to use casing, where necessary, to maintain open borings. The anchor holes should be drilled without the use of drilling fluids or water so that the optimum allowable adhesion between the grouted anchor and the soil can be developed. The holes should be grouted immediately after drilling or re-drilled prior to grouting, if left open for a period of more than 2 hours. Anchors should be installed such that they avoid conflict with all underground utilities, and a minimum separation of 10 feet should be maintained between all anchors and any nearby utilities. May 28, 2019 ASSOCIATED EARTH SCIENCES,INC. FSM/Id-190168F001-2-Projects\201901681K£\WP Page 15 18185B Page 10 of 180