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Soil Suitability / Nitrate Loading Study Irerracon Thor Property w Stockton, CA July 19, 2018 a Terracon Project No. NA187029 Boring P2 was found to be intact after the 24-hour soak period; however, a viscous clay layer was present at the bottom 1.0 foot of the boring. 1.6.5 Percolation Test Procedure The percolation tests were conducted in accordance with the requirements of the San Joaquin County EHD. The shallow percolation test (P1 at 3.5 feet bgs)was conducted on June 12, 2018. As water remained in the bottom of the boring, Terracon conducted the percolation test by following Procedure #1. Terracon added clear water approximately 0.5 feet above the gravel bottom and after the 30 minute period there was no drop in the water level. A deep percolation test (P2 at 25.0 feet bgs) was conducted on July 6, 2018. As a viscous clay layer of fluid was present at the bottom the boring. Terracon contacted Mr. Steven Shih at the EHD who recommended adding clear water above the clay fluid to run the percolation test. Terracon added approximately 1.5 feet of water above the clay fluid and performed the percolation test per Procedure #2 as instructed by Mr. Shih. The deep percolation test had a duration of four hours and was observed by Mr. Naseem Ahmed, EHD representative. Measurement of the water level during the percolation tests 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 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