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12 inches of water (measured vertically) and the water level was maintained for at least 4 hours to presoak the soil. After the soaking period was complete, the infiltration rate was measured by adjusting the water depth in the casing to ±12 inches above the test depth and monitoring the water level for ±1 to 2 hours, depending on the observed infiltration rate. This step was repeated 2 to 3 additional times for a total of 3 to 4 observations per test location. The testing was completed over a period of two days. We noted little variation in the infiltration rates between observations during the last test, indicating adequate saturation of the test soils. Table 1 provides a summary of the test depths, soil conditions, and infiltration rates at each test location. The reported infiltration rate in Table 1 is the lowest cumulative rate measured from an individual test or the lowest rate observed over a period of measurements from a single test. Raw test data is provided in Appendix C. Table 1. Summary of Falling Head Infiltration Tests Test Test Depth Soil Description Average Location (feet) at Test Depth Infiltration Rate (inches/hour) P-1 2.4 ±1.5 Brown, low to medium plasticity clayey SILT (ML to MH) P-2 4 ±2 Brown, low plasticity SILT, some clay (ML) Brown, low to medium plasticity SILT, some clay (ML) P-3 4 ±9 over sandy GRAVEL, trace silt and cobbles (GW) P-4 3.5 ±2.8 Brown, low plasticity SILT (ML) P-5 8 ±2.8 Brown, low plasticity SILT, trace sand (ML) Notes: 1. Test procedures followed the City of Eugene 2014 Rsnqlv`sdqL`m`fdldmsL`mt`k, Appendix G. The reported results are the lowest cumulative rate measured at the test location from an individual test. 2. Tests were conducted between July 13 and 14, 2017 for P-1 through P-3, and between September 28 and 29, 2017 for P-4 and P-5. 3. See Figure 2A for test locations. We observed relatively consistent infiltration rates of ±2.8 inches/hour at P-4 and P-5, which have been identified as possible locations for new stormwater infiltration systems. The 2014 Rsnqlv`sdqL`m`fdldmsL`mt`krecommends applying a factor of safety of 2 to the observed test results, which corresponds to a design infiltration rate of 1.4 inches/hour. More variable rates were documented at the other test locations. We attribute the variation to the variable clay and sand content of the predominantly silty soils encountered at shallow depths across the property. The measured infiltration rate was significantly higher at P-3 relative to the other tests. We attribute this higher infiltration rate to the presence of relatively shallow gravels River Road Multi-Family Development April 30, 2018 Preliminary Geotechnical Investigation 5. Project 2171066 Eugene, Oregon Evergreen Housing Development Group, LLC