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Soil Suitability /Nitrate Loading Study Irerracon <br />Thornton Road Trailer Parking Facility ■ Lodi, California <br />December 15, 2021 ■ Terracon Project No. NA217079 <br />1.6.3 Boring Preparation and Presaturation <br />The percolation test borings were excavated on November 21, 2021. Approximately two inches <br />of "pea gravel" was placed in the bottom of P1-3'; P2-3.5' and P3-6.3'. A 2.0 -inch diameter PVC <br />pipe with perforations towards the bottom was installed on top of the gravel and the annular space <br />was backfilled with "pea gravel". Presaturation of the percolation test holes occurred the same <br />day approximately 24 hours prior to the day of testing. The depth of water used to pre-soak the <br />borings was approximately 1.0 foot above the top of the gravel. <br />1.6.4 Condition of Borings after Presaturation <br />All borings were dry and intact after the 24-hour pre-soak period. <br />1.6.5 Percolation Test Procedure <br />Percolation tests were conducted for the borings on November 22, 2021 in accordance with the <br />requirements of the San Joaquin County EHD. Each percolation test had a duration of four hours. <br />The last half an hour of the test was observed by Mr. Naseem Ahmed from the EHD. <br />Measurement of the water level during the percolation tests was from a fixed reference point on <br />the PVC casing using a calibrated Solinst electric water level detector with a depth accuracy of <br />0.01 feet. All tabulated values on the field data sheet (Appendix E) are in decimal feet. After water <br />drop was observed, the holes were checked and refilled as necessary to maintain approximately <br />0.5 feet (6 inches) of water above the top of gravel. The readings were recorded every 30 minutes <br />for a period of four (4) hours." <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 5. <br />Summary of Percolation Test. <br />Test No. <br />Percolation Test <br />Percolation Rate <br />Test Duration <br />Comments <br />Date Tested <br />Depth feet <br />min/in <br />hours <br />see note <br />P1 <br />3 <br />8.32 <br />4 <br />11-22-2021 <br />Satisfactory <br />P2 <br />3.5 <br />14.7 <br />4 <br />Percolation Rate <br />11-22-2021 <br />P3 <br />6.3 <br />17.85 <br />4 <br />Responsive ■ Resourceful ■ Reliable 10 <br />