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Soil Suitability Nitrate Loading Study Manteca Unified School District 5700 East Nile Ave.,Manteca,CA Page 6 1.6.2 Number of Shallow and Deep Percolation Tests was Performed for Each Parcel Two percolation tests were performed on the Site, at 2 feet bgs and 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 April 18, 2019 two percolation test holes were hand augered 4 inches in diameter to depth of 2 feet bgs and one at 3 feet bgs. The sides of the holes were scored and two inches of pea sized gravel was placed at the bottom of each hole. Perforated 2 inch diameter PVC pipe was inserted into each hole and the annular space was filled with "pea gravel". Prior to conducting the percolation test the holes were presaturated for 24 hours with 6 inches of water from the bottom. 1.6.4 Description of the Date,Time and Condition of the Test Hole After the 24-Hour Soak Period On April 19, 2019, at approximately 2:00 p.m. both holes were observed to be intact with no remaining water after the 24-hour soak period. 1.6.5 Compliance with SJC Policy EHD 02-02 Based on the test hole conditions after the 24-hour soak period it was determined, per EHD requirements, that the 1 hour procedure(#3)would be conducted. A Solinst Model 101 P7 water level meter was used to measure depth to water during the tests. 1.6.6 Percolation Test Form with REHS Verification Signature The completed percolation test form signed by EHD inspector Jeffery Wong is included in Appendix D. 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 Nile Garden Elementary School site consist of unconsolidated alluvium and percolation rates of 5.71 minutes per inch (MPI) and 10.0 MPI were accepted rates for the proposed design and are not expected to generate potential issues. San Joaquin County standards for the percolation rate in the disposal field shall be no greater than sixty(60)minutes per inch or less than one(1) minute per inch. Percolation rates for seepage pits shall be no greater than thirty (30) minutes per inch. 1.6.8 Discussion of Percolation Rates in Relation to the Type, Size and Location of Future Leach Fields Needed at the Site In general, septic system construction should follow the San Joaquin County On-Site Wastewater Disposal Standards where applicable. A copy of the engineered septic design can be found in Appendix D. 2.0 NITRATE LOADING STUDY EHD recognizes nitrate contamination as a significant potential threat to the surface and groundwaters of the County. Groundwater quality may be impacted by nitrate contamination where percolating effluent leaches into the ground, should this effluent reach groundwater. Due to EHD's concerns regarding nitrate leaching into the surface and groundwaters from septic systems, a soil suitability and nitrate loading study is required by EHD for the proposed development to measure the potential concentration of percolating effluent and rain fall over a long period of time. This report has been prepared to meet the requirements of the San Joaquin County EHD's Soil Suitability Study Requirement Checklist (dated 9/25/07) and Nitrate Loading Study Requirement Checklist(dated 7/14/03). rs il? CONDOR