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Soil Suitability Nitrate Loading Study Manteca Unified School District 14600 Austin Rd.,Manteca,California Page 5 Agriculture, Natural Resource Conservation Service (MRCS) as Delhi loamy sand, whose general properties are 0 to 2 percent slope,well drained,with negligible runoff. Soils from approximately 15 to 50 feet bgs are primarily silts and sands. Shallow groundwater was encountered at a depth of approximately 45 feet bgs during drilling in February 2019. Pertinent information from the NRCS soil survey report and Site borings are included in Appendix E. 1.5.4 Discussion of Soil Lithology as Related to Future Onsite Septic Uses In general, the relatively sandy soil and expected fast percolation rates from the ground surface to approximately 15 feet bgs could result in unfavorable shallow septic disposal areas. However,groundwater beneath the Site is currently approximately 45 feet bgs within a significant clay layer appears to be laterally continuous beginning at approximately 15 to 17.5 feet bgs. The school has already been permitted for and operates two septic tanks and associated leach lines and leach lines additions(summarized in Section 1.3.2 above). 1.6 PERCOLATION TEST INFORMATION SECTION 1.6.1 Site Map Showing the Percolation Test Holes on the Parcel See Section 1.5.2 and Figure 2(Appendix A). 1.6.2 Number of Shallow and Deep Percolation Tests was Performed for Each Parcel One percolation test was performed on Site at 3 feet bgs in the area of the proposed leach field. 1.6.3 Description of the Date,Time and Protocol Used to Prepare the Test Hole On October 13, 2019, one percolation test hole was hand augered 4 inches in diameter to depth of 3 feet bgs.The sides of the holes were scored and two inches of pea sized gravel was placed at the bottom of hole. A perforated 2 inch diameter by 3 feet long PVC pipe was inserted into the hole and the annular space was filled with pea gravel. Prior to conducting the percolation test, the test hole was presaturated for 24 hours with 6 inches of standing water from the bottom of the test hole. 1.6.4 Description of the Date,Time and Condition of the Test Hole After the 24-Hour Soak Period On October 3, 2019, approximately 9:00 a.m. the test hole was observed to be intact with no remaining water. 1.6.5 Compliance with SJC Policy EHD 02-02 Based on the test hole condition after the 24 hour soak period it was determined per EHD requirements that the 1 hour procedure would be conducted.A Solinst Model 101 P7 Water Level Meter was used to measure depth to water. 1.6.6 Percolation Test Form with REHS Verification Signature The completed percolation test form signed by county inspector Daria Afonkaia is included in Appendix D of this report. 1.6.7 Discussion of Any Potential Problems Predicted and/or the Need for an Engineered or Alternative Septic System The subsurface soils encountered at the Site consist of unconsolidated alluvium and percolation rates of 2.77 minutes per inch (MPI) are accepted rates for the proposed design and are not expected to generate potential issues. EHD standards for the percolation rate in the disposal field shall be no greater than sixty ;�j� CONDOR