2930 MAPLE ST KAISER PERMANENTE Geotech Report 2025-03-07

Geotechnical Engineering Report-Revised lrerracon Kaiser Everett Medical Center Everett,Washington -- s--- y� December 18, 2019 Terracon Project No. 81195071 GeoReport Grading and Drainage All grades must provide effective drainage away from the building during and after construction and should be maintained throughout the life of the structure. Water retained next to the building can result in soil movements greater than those discussed in this report. Greater movements can result in unacceptable differential floor slab and/or foundation movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with downspouts that discharge onto splash blocks at a distance of at least 10 feet from the building. Gutters and downspouts should be routed into tightline pipes that discharge either directly into a municipal storm drain or to an alternative drainage facility. Splash-blocks should also be considered below hose bibs and water spigots. Site grades should be established such that surface water is directed away from foundation and pavement subgrades to prevent an increase in the water content of the soils. Adequate positive drainage diverting water from structures, open cuts, and slopes should be established to prevent erosion, ground loss, and instability. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. After building construction and landscaping have been completed, final grades should be verified to document effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted, as necessary, as part of the structure's maintenance program. Where paving or flatwork abuts the structure, a maintenance program should be established to effectively seal and maintain joints and prevent surface water infiltration. Earthwork Construction Considerations Primarily, we expect that shallow excavations for the proposed structure are anticipated to be accomplished with conventional construction equipment. Where glacial till is encountered at shallower depth, excavation progress is likely to be slower and may require heavy duty excavators. The contractor should be prepared to encounter cobbles and boulders. Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of floor slabs. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over or adjacent to construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted prior to floor slab and pavement construction. Shallow, perched groundwater observed on the site will likely affect excavation efforts, especially for utility trenches. Site development should avoid or limit trenching and excavation depths to the extent practical unless diversion of the groundwater can be accomplished.We anticipate that the contractor may be able to control groundwater seepage with conventional cutoff trenches, sumps, and pumps. Responsive ■ Resourceful ■ Reliable 9