Laserfiche WebLink
Soil Suitability l Nitrate Loading Study 1rerracon <br /> Proposed Global Carrier Inc. ■ Manteca, California <br /> August 8, 2018 ■ Terracon Project No. NA187034 <br /> 1.6.6 Percolation Test Forms and Results <br /> The completed percolation test form with the EHD representative signature is included in <br /> Appendix F of this report. A shallow percolation test is defined by the EHD as being between 36 <br /> and 42 inches in depth. While a deep percolation test is defined by the EHD as being between <br /> 42 inches and 25 feet in depth. The percolation test must demonstrate a satisfactory percolation <br /> rate (less than or equal to 60 minutes per inch drop for shallow leach lines and 30 minutes per <br /> inch or less for septic pits per SJEHD) within the existing septic system disposal field of a parcel <br /> to utilize a standard septic system. Details of the percolation test is summarized in the table <br /> below. <br /> Table 5. <br /> Summary of Percolation Tests. <br /> Percolation Percolation <br /> Test No. Test Rate Test Duration Comments <br /> Date Tested Depth (feet) (minutes/inch) (minutes) (see notes) <br /> 131 (7-27-18) 3.5 62.5 240 Unsatisfactory <br /> percolation rate <br /> B1 (8-1-18) 3.5 22.7 240 Satisfactory percolation <br /> 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 /> 1.6.7 Discussion of Percolation Test Results <br /> The shallow soils between 0 to 3.5 feet bgs at boring B1 demonstrated a satisfactory percolation <br /> rate for a standard septic system per EHD requirements. <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. The foregoing investigation and percolation test results <br /> indicate the site consists of surface silty sandy soils which appear suitable for a standard septic <br /> system. <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 12 <br />