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Soil Suitability/ Nitrate Loading Study 1rerracon Manteca Farm Improvement Manteca, California October 29, 2019 Terracon Project No. NA197073 1.6.5 Percolation Test Procedure On September 19, 2019, 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 after the 24-hour presoak and the first 0.5 foot of water drained away in less than 30 minutes; therefore, Terracon conducted the percolation test by following Procedure #3. Terracon added clear water approximately 0.5 feet above the top of the gravel and recorded the drop in water level over a one hour period. Due to the rapid percolation rate reading were recorded in 5 minute intervals. 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 tests were observed by Ms. Daria Afonskaia, EHD representative. 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 test are summarized in the table below. Table 7. Summary of Percolation Tests. Percolation Percolation Test No. Comments Date Tested Test Rate Test Duration (see notes) Depth (feet) (minutes/inch) 61 Satisfactory Percolation 09/19/2019 3.5 2.77 1 hours Rate Note: A satisfactory percolation rate is 60 minutes per inch or less for shallow leach lines and 30 minutes per inch or less for septic pits per SJEHD,Onsite Wastewater Disposal Standards,October 2003. The completed percolation test form with Ms. Afonskaia's verification signature is included in Appendix E of this report. 1.6.7 Discussion of Percolation Test Results Based on the percolation tests results, Boring B1 at 3.5 feet bgs achieved a passing percolation rate of 2.77 minutes per inch or less for standard leachfields. 1.6.8 Discussion of Septic System Sizing Responsive ■ Resourceful ■ Reliable 12