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Soil Suitability/ Nitrate Loading Study Irerracon <br /> Schuler Property Tracy, California <br /> May 30, 2019 Terracon Project No. NA197026 <br /> Table 5. <br /> Summary of Percolation Tests. <br /> Percolation Percolation <br /> Test No. Comments <br /> Test Rate Test Duration <br /> Date Tested Depth (inch) (minutes/inch) (see notes) <br /> B1 42 6.76 4 hours Satisfactory Percolation <br /> May 10, 2019 Rate <br /> Note: A satisfactory percolation rate is 60 minute _ 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. Afonskaia verification signature is included in <br /> Appendix E of this report. <br /> 1.6.7 Discussion of Percolation Test Results <br /> The sil sandy soils encountered in the shallow boring demonstrated a satisfactory percolation <br /> rate shallow leach lines. <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 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 /> They believe that their method is a good planning tool and provides useful information to planners <br /> and local officials but with some real limitations. In their article published in Ground Water, <br /> Hantzsche and Finnemore mention that "...the equation ignores dispersion, lateral flow, and <br /> mixing with groundwater flow from up-gradient areas. These processes would generally <br /> Responsive ■ Resourceful ■ Reliable 11 <br />