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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Buddhist Temple Proposed Dormitory ■ Stockton, California <br /> July 11, 2019 ■Terracon Project No. NA177056 <br /> 1.6.6 Percolation Test Forms and Results <br /> The completed percolation test forms are included in Appendix E of this report. A shallow <br /> percolation test is defined by the EHD as being between 36 and 42 inches in depth. While a deep <br /> percolation test is defined by the EHD as being between 42 inches and 25 feet in depth. The <br /> percolation test must demonstrate a satisfactory percolation rate (less than or equal to 60 minutes <br /> per inch drop for shallow leach lines and 30 minutes per inch or less for septic pits per SJEHD) <br /> within the existing septic system disposal field of a parcel to utilize a standard septic system. <br /> Details of the percolation test is summarized in the table on the following page. <br /> Table 6. <br /> Summary of Percolation Tests. <br /> Test No. Percolation Percolation Test Duration Comments <br /> Date Tested Test Rate (minutes) (see notes) <br /> Depth (feet) (minutes/inch) <br /> B1 (05/10/2019) 3.5 2.74 4torSatisfactory <br /> B2 (05/10/2019) 3.5 50 4 613 Satisfactory <br /> 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 <br /> pits per San Joaquin County Onsite Wastewater Treatment Systems Standards(EHD 42-014),January 2017. <br /> 1.6.7 Discussion of Percolation Test Results <br /> Both percolation tests demonstrated satisfactory percolation rates of 2.74 minutes per inch at <br /> boring B1 and 50 minutes per inch at boring B2. <br /> 1.6.8 Discussion of Septic System Sizing <br /> Based on the favorable percolation results, the site soils appear suitable for a standard septic <br /> system. In general, septic system construction should follow the San Joaquin County On-Site <br /> Wastewater Treatment Systems Standards where applicable. <br /> 2.0 NITRATE LOADING STUDY <br /> Because of concern regarding nitrate leaching into groundwater from septic systems, a nitrate <br /> loading analysis is required by the EHD for the proposed development to determine the potential <br /> concentration of percolating effluent and rain fall over the long term. Where percolating effluent <br /> leaches into the ground, groundwater quality may be impacted to some degree should the effluent <br /> reach groundwater. <br /> The method utilized for the nitrate loading analysis is based on a simple mass balance formula, <br /> discussed in a published article by Hantzsche and Finnemore (1992), which provides a <br /> Responsive ■Resourceful ■Reliable 13 <br />