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Soil Suitability&Nitrate Loading Evaluation CTE Job #25-1084G New Septic Leech Lines 21850 East Liberty Rd Clements, California January 30, 2021 Paize 8.1 Percolation Testing Procedure Upon completion of the percolation test hole drilling, sides were scored to remove any smeared soil surfaces. Loose material was removed from the hole, 2 inches of coarse sand was added then a 3-inch diameter open-ended slotted drain pipe was installed to control potential sidewall caving of the hole. Pre-saturation of the soils to be tested was accomplished by adding water to 12-inches above the base each test hole the day preceding the test. Percolation testing was performed the following day. After the 24-hr pre-saturation period a 6-inches column of water was added to (P-I through P-3) above the top of the 2 inches of clean coarse sand placed at the base of the test hole. Recordings were made of the change (drop) in water level at regular 30 minute time intervals for four hours. Water level was refilled to 6 inches above the clean coarse sand after each interval. The smallest reading of the four-hour period was used to calculate percolation rate. Specific details are included on the attached percolation test data sheets located in Appendix-A. 8.2 Percolation and Infiltration Rates The soil percolation rate is defined by the average time in minutes for a 1-inch column of water to "seep" into the soil. Percolation rate was calculated in minutes per inch (MPI) by dividing the time (in minutes) by the change (drop) in water level (in inches). No correction factor was used in the calculation for the 4-inch boring diameter. Percolation test "P-1" achieved a generally steady percolation rate of 30 minutes/inch at 36-inches begs, percolation tests "P-2" and "P-3" achieved a steady percolation rate of 60 minutes/inch . The percolation rate obtained from testing is moderate and consistent with the above USDA soil survey descriptions. Based on our experience these soils and corresponding percolation rates are not inconsistent with those typical of the soil types encountered in the vicinity. Owing to variations in material type and depth, percolation rates would typically be expected to fluctuate somewhat across a site and are also dependent upon actual construction, depth, size, location, and workmanship of the drainage element. Based on percolation test results, the soil in % TCZQIF