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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Pickens Property■ Tracy, California <br /> May 12, 2020 ■Terracon Project No. NA207032 <br /> period. Measurement of the water level during the percolation test was from a fixed reference <br /> point on the PVC casing using a calibrated Solinst electric water level detector with a depth <br /> accuracy of 0.01 feet. All tabulated values on the field data sheet are in decimal feet. The <br /> percolation test was observed by Ms. Betty Ho, Registered Environmental Health Specialist. <br /> 1.6.6 Percolation Test Forms and Results <br /> A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth. <br /> While a deep percolation test is defined by the EHD as being between 42 inches and 25 feet in <br /> depth. The shallow percolation test must demonstrate a satisfactory percolation rate of less than <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 6. <br /> Summary of Percolation Test. <br /> Test No., Date Percolation Test Percolation Rate Test Duration Comments <br /> Tested Depth feet min/in hours see note <br /> B3.5—8/8/18 3.5 5 4 Satisfactory <br /> Percolation Rate <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 /> The completed percolation test form with Ms. Ho's signature is included in Appendix E of this <br /> report. <br /> 1.6.7 Discussion of Percolation Test Results <br /> Based on the percolation tests results, Boring B3.5 achieved a satisfactory percolation rate of 5.0 <br /> minutes per inch suitable 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 /> Responsive■ Resourceful ■ Reliable 11 <br />