The Mark at Eugene January 6, 2026 <br />Geotechnical Investigation and Seismic Hazard Study 15 Project No.: 2251077 <br />Eugene, Oregon Landmark Construction, LLC <br />Because the depth of overexcavation may vary, we recommend the bid <br />documents include a line item for a unit cost of overexcavation and <br />replacement with imported granular fill. The need for and depth of the <br />required excavation and replacement will need to be determined in the field <br />at the time of construction by FE. <br />17. Place and compact imported granular fill within the finished excavation as <br />specified above. The granular fill may consist of 18 inches of Base Aggregate <br />or approved Granular Structural Fill capped with a minimum of 12 inches of <br />Base Aggregate. <br />18. Backfill utility trenches within the building pad entirely using Base Aggregate. <br />19. Grade the finished ground surface surrounding the building to promote runoff <br />away from the building area and foundations. <br />20. Prior to the placement of rebar for the floor slab, proof-roll the completed <br />area using a loaded truck (or other heavy equipment approved by FE) to <br />identify any soft, pumping, or disturbed areas that may have developed over <br />the construction period. Overexcavate any pumping base rock or subgrade <br />and replace it with compacted Base Aggregate. <br />21. Excavate the foundations to the required elevations. The excavation should <br />terminate in approved existing granular fill or stiff fine-grained alluvium. The <br />excavation should accommodate a minimum of 12 inches of compacted Base <br />Aggregate beneath the foundations and extend a minimum of 12 inches <br />beyond the outside edges of the foundations. Use of earth-formed <br />foundations will require the foundation areas to be prepared with compacted <br />granular fill as recommended and excavated after the materials are <br />compacted in place. <br />All foundation excavations should be observed by a representative of FE to <br />confirm the soil and need for additional excavation, if required. <br />22. Provide a minimum perimeter footing embedment of 18 inches below finished <br />grades. Continuous footings should have a minimum width of 1.5 feet and <br />isolated spread footing should have a minimum dimension of 2 feet. <br />23. A perimeter foundation drain, if provided, should consist of a 3 or 4-inch <br />diameter perorated or slotted PVC pipe. The pipe should be bedded and <br />backfilled with Drain Rock that is wrapped in a Subsurface Drainage <br />Geotextile. The perimeter foundation drain should be provided around the <br />structure and for any below-grade portions of the building (i.e., elevator pits). <br />Additional design considerations will be required for the shallow groundwater <br />level observed at the site if drainage is not practical for the foundations. The <br />absence of drainage and shallow groundwater will require design <br />consideration and coordination with the architect, civil engineer and <br />structural engineer for the project.