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j . . Cadman,Inc. August 31,2018 Page 3 PILOT INFILTRATION TESTING One small-scale PIT was conducted in test pit PIT-1 in July 2017 and described in our previously issued geotechnical report dated August 10, 2017. The following is a summary of test methods, field measured infiltration rates, and design infiltration rates for the two additional small-scale PITs conducted as verification for the Hardeson Pond. Test Method Test pits PIT-2 and PIT-3 were initially excavated with a trackhoe to depths of approximately 21/2 and 41/2 feet, or Elevation 421.5 and 419.5, respectively, into the native advance outwash sand and gravel deposits. The bottom of each test pit was approximately 4 feet wide by 41/2 feet long. The soil in PIT-2 generally consisted of fine to coarse gravel with sand (advance outwash)at the depth tested. The soil in PIT-3 generally consisted of fine to medium sand with occasional gravel (advance outwash) at the depth tested. Groundwater seepage was not observed in the excavations during testing. Hydrograph showing the measured water levels in PIT-2 and PIT-3 throughout all stages of the small-scale PITs are shown on Figures 3 and 5,respectively. Plots of the measured infiltration rates calculated during each stage of the small- scale PITs are shown on Figures 4 and 6, respectively. Rapid infiltration was observed in PIT-2, whereas low infiltration was observed in PIT-3. During the PITs, a graduated yard stick was driven into the floor of the test pit as a visual reference for monitoring water levels during testing.A piezoelectric pressure transducer was secured to the bottom of the yard stick to provide accurate water level records in 10-second intervals throughout the duration of the tests. Water for infiltration was provided by Aero Construction using a 4,000-gallon water truck. Initial filling and maintaining of the water level in each test pit was done by monitoring the declining water level in a series of stages.The test pits were filled to a predetermined depth(approximately 14 inches)for the 6-hour pre-soaking period. During the pre-soaking,the water level was allowed to drain approximately 2 inches before the pit was refilled to the initial level again to maintain a constant minimum depth of 1 foot.This draining and refilling process was repeated a number of times(stages)in succession.At the end of the 6-hour pre-soaking period,the successive filling and draining was repeated at the same 12 and 14 inches of water depth for an additional hour, which is considered the testing period. Following this testing period,the water was turned off and the water level was recorded for an additional hour or until the test pit was drained. By periodically refilling the pit to the starting level, then allowing the water level drop between two pre-determined levels, the apparent infiltration rate for each cycle was determined accurately using measurements from the pressure transducer.The rate of decline in the falling water levels recorded after each filling cycle was used to calculate the apparent infiltration rate for each stage of the test. The overall testing process for each PIT took about 8 hours with water levels measured continuously(every 10 seconds). After each test pit was drained, it was excavated an additional 2 feet to observe and sample the soils below the level of the PITs. We did not observe hydraulically resistive layers, standing water, or seepage in the excavations below the elevation where the PITs were performed. Measured Infiltration Rate Plots of the apparent short-term infiltration rates calculated during each stage of the PITs are presented in Figures 4 and 6. Field measured infiltration rates were higher during the initial stages of the test as additional water was required to fill the pore space of the initially unsaturated soils until it approaches full saturation toward the end of the test. GEOENGINEERS� File No.7087-026-02