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Soil Suitability/ Nitrate Loading Study Irerracon Ernst Property ■ Tracy, CA February 21, 2019 revised April 9, 2019 ■ Terracon Project No. NA197000 1.6.3 Boring Preparation and Presaturation The shallow soil boring (B1) was excavated on February 5, 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 3.0 feet bgs) was conducted in accordance with the requirements of the San Joaquin County EHD on February 6, 2019. As there was no water remaining in the test hole overnight, Terracon conducted the percolation test 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 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 Mr. Naseem Ahmed, 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. Table 5. Summary of Percolation Tests. Percolation Percolation Test No. Test Rate Test Duration Comments Date Tested (see notes) Depth (inch) (minutes/inch) B1 36 35.71 4 hours Satisfactory Percolation 02/06/2019 Rate Responsive■ Resourceful ■ Reliable 10