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Geotechnical Soil Infiltration Investigation 2610 Cal Young Road, Eugene, Oregon 4 | P a g e CORE GeoEngineering, Inc. Project No. 25-1127 Version 1.0, January 23, 2026 5.0 FIELD EXPLORATION AND SUBSURFACE CONDITIONS Subsurface exploration for this report was conducted on December 5, 2025. The approximate exploration locations are shown on Figure 2. The client retained an excavation contractor with a Bobcat E48 mini- excavator to excavate five test pits (TP-1 through TP-5) at locations selected by the client and civil engineer across the subject property. Test pits were excavated to depths ranging from 5.5 to 8 feet below ground surface (bgs). A CORE engineering geologist examined and logged the exposed soil profiles, recording key data such as soil consistency, stratigraphy, soil engineering characteristics, and groundwater occurrence. Soils were classified according to the Unified Soil Classification System (USCS). Bulk soil samples were collected from selected test pits and stored in relatively air-tight plastic bags for laboratory testing. We conducted soil infiltration testing within the test pits at various depths using the open -pit falling-head testing method in accordance with the City of Eugene Stormwater Management Manual. After testing, the explorations were backfilled by the client's excavation contractor. Test pit logs are presented in the appendix of this report. It is important to note that the exploration locations were determined in the field by pacing or measuring distances from visible property corners and other site features indicated on the provided plans. Therefore, the exploration locations should be considered approximate. Summary exploration logs are attached. The stratigraphic contacts shown on the individual subsurface logs represent approximate boundaries between different soil types, but actual transitions may be more gradual. The soil and groundwater conditions described are specific to the dates and locations of the explorations and may not be representative of other areas or times. A summary of the soil and groundwater conditions encountered during the explorations is provided below. 5.1 Soil Descriptions Topsoil/Fill: At the exploration locations, the ground surface was typically vegetated with grass, scattered trees, shrubs, and blackberries. A topsoil horizon consisting of dark brown to black, organic Lean CLAY (OL-CL) with fine roots and remnant tree roots, and gravels was typically observed from ground surface to approximately 18 inches below ground surface (bgs). At the location of test pit TP-1 a fill layer consisting of brown, medium stiff to stiff, moist to wet Lean CLAY (CL) was observed beneath the topsoil, extending to a depth of approximately 4.5 feet bgs. Lean CLAY (CL): Underlying the topsoil/fill, native soils typically consisted of brown to dark brown, medium stiff to stiff, very moist to wet, moderate to high plasticity Lean CLAY (CL). This soil unit was observed to extend to depths ranging from approximately 4.5 to 8 feet bgs. Soil moisture content testing conducted in accordance with ASTM D2216 on representative samples collected from a depth of 8 feet bgs within test pit TP-1 indicated an in-situ moisture content of 41.6 percent. Sieve analysis conducted in accordance with ASTM D6913 and D1140 indicated 93.4 percent passing the No. 200 sieve. Lean CLAY with Gravel (CL): Underlying the Lean CLAY, soils typically consisted of brown, medium stiff, very moist to wet, moderately plastic Lean CLAY with Gravel (CL). This soil unit was observed to extend to the maximum depth of exploration within test pits TP-2 through TP-5 and was not encountered within test pit TP-1. The soil contained subrounded gravel-sized rock within the clay matrix. Soil moisture content testing conducted in accordance with ASTM D2216 on a representative sample collected from a depth of