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1 <br /> 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 /> Q_hty G..roi <br />