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Soil Suitability I Nitrate Loading Study Irerracon Vacant Commercial Property m Stockton, California December 7, 2018 ® Terracon Project No. NA187056 The deep soil boring B2 was 8 inches in diameter. Approximately six 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. Pre-saturation consisted of a water column approximately 3 foot over gravel. 1.6.4 Condition of Borings after Pre-saturation October 25, 2018, after the initial 24-hour pre-saturation period, boring B1 was found to be dry and intact on the day of testing. On November 1, 2018 boring B2 water remained in the bottom of the boring. 1.6.5 Percolation Test Procedure A shallow percolation test was conducted on October 25, 2018 at a depth of 3.5 feet bgs and had a duration of four hours with readings taken every 30 minutes; however, the shallow percolation test had an unsatisfactory percolation rate of 125 minutes per inch at the end of the testing period. A second percolation test was conducted on November 1, 2018 at a depth of 25.0 feet bgs over a four hour period. The final 30 minutes of the test was observed by EHD representative Mr. Jeff Wong who signed the percolation test form; however, the deep percolation test had an unsatisfactory percolation rate of 125 minutes per inch at the end of the testing 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. A copy of the field data is included in Appendix F. 1.6.6 Percolation Test Forms and Results The completed percolation test forms are included in Appendix F of this report. 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 percolation test must demonstrate a satisfactory percolation rate (less than or equal to 60 minutes per inch drop for shallow leach lines and 30 minutes per inch or less for septic pits per SJEHD) within the existing septic system disposal field of a parcel to utilize a standard septic system. Details of the percolation test is summarized in the table on the following page. Responsive ■ Resourceful ■ Reliable 13