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Soil Suitability/Nitrate Loading Study Irerracon Pickens Property ■ Tracy, California May 12, 2020 ® Terracon Project No. NA207032 1.5.4 Discussion of Soil Lithology The soils encountered in our percolation test boring and soil profile consisted primarily of silty fine sand to sandy silt with clay. Generally speaking, coarse-grained soil has a greater potential for percolation than fine-grained or cemented soil. Terracon searched the DWR online Well Completion Records for additional information regarding soil lithology within 0.14 miles of the site. A well record located at 33247 S. Chrisman Road was identified. Based on a review of the record, the well was advanced to 480 feet bgs and consisted consisted of clay, sandy clay in the upper 180 feet bgs and coarse sand, clay and/or gravel between 180 and 480 feet bgs. Groundwater was encountered at 180 feet bgs in the year 2016. 1.6 Percolation Test Information 1.6.1 Percolation Test Locations Refer to Section 1.5.1 and Appendix A, Exhibit 2. 1.6.2 Number of Percolation Tests One percolation test (B3.5) was performed. 1.6.3 Boring Preparation and Presaturation The percolation test boring (B3.5) and soil profile (B10) were hand augered on August 8, 2018. Approximately two inches of"pea gravel'was placed in the bottom of the open boring. A 2.0-inch diameter PVC pipe with perforations towards the bottom was installed on top of the gravel and the annular space was backfilled with "pea gravel". Presaturation of the percolation test holes occurred the same day approximately 24 hours prior to the day of testing. The depth of water used to pre-soak the shallow borings was approximately 1.0 foot above the top of the gravel. 1.6.4 Condition of Borings after Presaturation Boring B3.5 was dry and intact after the 24-hour pre-soak period. 1.6.5 Percolation Test Procedure On August 9, 2018, the percolation test was conducted in accordance with the requirements of the San Joaquin County Percolation Test Procedure (Form: EHD 42-01-002 Revised 08-23- 2011). There was no water remaining in the test hole and less than 0.5 feet of water drained from the test hole within the first 30 minutes of the test; therefore, Terracon conducted the percolation tests by following Procedure #2. Terracon added clear water approximately 0.5 feet above the top of the gravel and recorded the drop in water level in 30-minute intervals over a four-hour Responsive ■ Resourceful ■ Reliable 10