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Soil Suitability/ Nitrate Loading Study 1rerracon <br /> Souza Property Tracy, CA <br /> February 28, 2020 Terracon Project No. NA207011 <br /> or equal to 60 minutes per inch drop in water level within the existing septic system disposal field <br /> of a parcel to utilize a standard septic system and 30 minutes per inch or less for septic pits. <br /> Details of the percolation tests are summarized in the table below. <br /> Table 8. <br /> Summary of Percolation Test. <br /> Test No. Percolation Test Percolation Rate Test Duration Comments <br /> Date Tested Depth(feet) (minutes/inch) (see notes) <br /> 131 <br /> 02/13/2020 3.0 8.33 4 hours Satisfactory Percolation Rate <br /> B2 10.0 20.83 4 hours Satisfactory Percolation Rate <br /> 02/13/2020 <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 SJEHD,Onsite Wastewater Disposal Standards,October 2003. <br /> The completed percolation test form with Ms. Kaur verification signature is included in Appendix <br /> E of this report. <br /> 1.6.7 Discussion of Percolation Test Results <br /> Based on the percolation tests results, Boring B1 at 3.0 feet bgs and Boring B2 at 10.0 feet bgs <br /> achieved a passing percolation rate of less than 60 minutes per inch and greater than 1.0 minute <br /> per inch required for standard leach fields. <br /> 1.6.8 Discussion of Septic System Sizing <br /> In general, septic system construction should follow the San Joaquin County On-Site Wastewater <br /> Disposal Standards (OWTS)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 /> convenient and simplified method to estimate long-term groundwater nitrate impacts on an area- <br /> wide basis. <br /> Hantzsche and Finnemore found that over a long period of time, water quality in the upper <br /> saturated groundwater zone closely approximates the quality of percolating recharge waters. <br /> Responsive■ Resourceful ■ Reliable 11 <br />