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Soil Suitability/ Nitrate Loading Study 1rerracon Souza Property - Tracy, CA February 28, 2020 Terracon Project No. NA207011 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 Two percolation tests (B1 and B2) were performed. 1.6.3 Boring Preparation and Presaturation The percolation test borings(B1 and B2)were hand augered on February 11,2020 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 on February 12, 2020 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 at boring B1 and 0.5 feet above boring B2. 1.6.4 Condition of Borings after Presaturation Boring B1 and B2 were dry and intact after the 24-hour pre-soak period. 1.6.5 Percolation Test Procedure On February 13, 2020, 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 holes 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 period. Measurement of the water level during the percolation test was from a fixed reference point on the PVC casing using a calibrated Solinst electric water level detector with a depth accuracy of 0.01 feet. All tabulated values on the field data sheet are in decimal feet. The percolation test was observed by Ms.Sukhreet Kaur, Registered Environmental Health Specialist. 1.6.6 Percolation Test Forms and Results A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth. While a deep percolation test is defined by the EHD as being between 42 inches and 25 feet in depth. The shallow percolation test must demonstrate a satisfactory percolation rate of less than Responsive ■ Resourceful ■ Reliable 10