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13 certerra.com 4660 Main Street, Suite 100, Springfield, Oregon 97478 T: 541.393.6340 2.2 Subsurface Materials As mentioned above, the subsurface conditions at the site were explored with eight (8) exploratory test pits (TP-1 through TP-8) for the proposed development. The approximate locations of the test pits are shown on the Exploration Location Plan (see Figure 4 below). The terminal depth of the test pits was approximately 3 feet to 7-1/2 feet bgs. All of the explorations, TP-1 through TP-8, terminated within the hard, native, weathered siltstone stratum, locally known as Eugene Formation. Disturbed “grab” soil samples were obtained in the test pit locations during our subsurface exploration. Each sample was marked and identified by date sampled, project name, project number, test pit number, and sample depth. The samples were transported to our laboratory for visual identification and laboratory testing. Samples not altered by laboratory testing will be retained for 90 days from the date of this report. Select soil samples were tested in the laboratory to determine material properties for our evaluation. Laboratory testing was accomplished in general accordance with ASTM procedures. The testing performed included moisture content tests (ASTM D2216), an Atterberg Limits test (D4318), The Amount of Material in the Soils Finer than the #200 Sieve (ASTM D1140), and an Expansion Index Test (ASTM D4829). The test results have been included on the Test Pit Logs in Appendix A. The soils encountered in the explorations, beneath the site ground surface, may be divided into three (3) general strata, as described below: Topsoil: The surficial layer in test pits TP-1 through TP-8 was an 8 to 16-inch-thick layer of dark brown/black, moist, silty clay topsoil that contained tree roots up to about 1 inch in diameter. Fat Clay (CH): The layer beneath the topsoil in all of our test pits, TP-1 through TP-8, classified as Fat Clay (CH) in accordance with the Unified Soil Classification System (USCS). Based on observed digging effort and pocket penetrometer test results (unconfined compressive strength) of 1.0 to greater than 4.5 tons per square foot, the clay was stiff to hard at the exploration locations. Note that based on our Expansion Index testing result on a sample obtained at the subject site on March 30, 2026, the clay at this site has a high shrink/swell potential (i.e. potentially highly expansive). Weathered Siltstone: The terminal layer beneath the clay in all of our test pits, TP-1 through TP-8, appeared to be moist, yellow-brown and gray, weathered siltstone, locally known as Eugene Formation. Based on observed digging effort, the Eugene Formation was very stiff to hard at the exploration locations. The above subsurface description is of a generalized nature to highlight the major subsurface stratification features and material characteristics. The Test Pit Logs included in Appendix A should be reviewed for specific information at specific locations. These records include sample locations, soil and rock descriptions, stratifications, pocket penetrometer (unconfined compression) test results, and results of laboratory tests. The stratifications shown on the