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Soil Suitability/Nitrate Loading Study Schuler Property Tracy, California Irerracon May 30, 2019 Terracon Project No. NA197026 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 (61)was performed. 1.6.3 Boring Preparation and Presaturation The shallow soil boring (B1) was excavated on May 9, 2019. 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 hole occurred approximately 24 hours prior to the day of testing. The depth of water used to pre-soak was approximately 1.0 foot above the top of the gravel. 1.6.4 Condition of Borings after Presaturation Boring B1 was found to be dry and intact after the 24-hour pre-soak period. 1.6.5 Percolation Test Procedure The percolation test (B1 at 3.5 feet bgs) was conducted in accordance with the requirements of the San Joaquin County EHD on May 10, 2019. As there was no water remaining in the test hole overnight, Terracon conducted the percolation test by following Procedure #2. Terracon added potable water approximately 0.5 feet above the top of the gravel and recorded the drop in water level at thirty 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. Daria Afonskaia, EHD representative. A copy of the field data is included in Appendix E. 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 or equal to 60 minutes per inch drop in water level within the existing septic system disposal field of a parcel to utilize a standard septic system and 30 minutes per inch or less for septic pits. Details of the percolation tests are summarized in the table below. Responsive ■ Resourceful ■ Reliable 10