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PERCOLATION TEST PROCEDURE FOR SAN JOAQUIN COUNTY <br />1. Measurments of the Percolation test Hole. <br />A. Diameter = 4 inches to 12 inches. <br />B. Depth = of leach field - 36 inches. <br />II. Preparation of the Test Hole. <br />A. Scratch or Score sides to remove any smeared soil surfaces. <br />B. Remove loose material from hole <br />C. Add 2 inches of course sand or fine gravel. <br />III. Saturation. <br />A. Presoak Test Hole for 24 hours. <br />IV. Procedure #1 - If water remains in the hole overnight. <br />A. 24 hours after water is first added to the hole, add clear <br />water to approximately 6 inches over the gravel. <br />B. From a fixed reference point, measure the percolation rate <br />over a thirty (30) minute period. <br />C. Calculate the percolation rate in minutes per inch: <br />V. Procedure #2 - if no water remains in test hole overnight. <br />A. Add clear water to bring depth of water in the hole to <br />approximately 6 inches over gravel. <br />B. From a fixed reference point, measure the drop in water level <br />at approximately 30 minute intervals for four (4) hours, <br />refilling 6 inches over the gravel as necessary. <br />C. Use the reading during the last 30 minutes of the four hour <br />period to calculate percolation rate in minutes per inch. <br />IV. Procedure #3 - in sandy soils (or other soils) in which the first <br />6 inches of water seeps away in less that 30 minutes after the <br />overnight swelling period. <br />A. Refill the hole to approximately 6 inches above the gravel. <br />B. Take the readings 10 minutes apart over a one hour period. <br />C. Use the reading obtained during the last minutes to calculate <br />percolation rate in minutes per inche. <br />Source: Manual of Septic Tank Practices, U.S. Dept. of H.E_W. (1967) <br />QCI �ualih� �ontrol Ixspation <br />