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PUBLIC HEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> Q: <br /> JOGI KHANNA M.D.,M.P.H. <br /> Health Officer <br /> P.O. Box 2009 . (1601 East Hazelton Avenue) . Stockton, California 95201 c'tlF6 r <br /> (209) 468-3400 <br /> PERCOLATION TEST PROCEDURE <br /> I . Measurements 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 24 hours before test by adding water a minimum <br /> of 12" over gravel. <br /> IV. Procedure 91 - if water remains in the test hole overnight. <br /> A. 24 hours after water is first added to the hole, add clear water <br /> to approximately 6 inches over the gravel. <br /> B. From a fixed reference point, measure the percolation rate over <br /> a thirty (30) minute Period. <br /> C. Calculate the percolation rate in minutes per inch. <br /> V. Procedure it2 - 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 at <br /> approximately 30 minute intervals for four (4) hours, refilling <br /> 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 /> VI . Procedure it3 - 9.n sandy soils (or other soils) in which the first 6 <br /> Inches of water seeps away in less than 30 minutes after the overnight <br /> swelling period. <br /> A. Refill the hole to approximately 6 inches above the gravel. <br /> B. Take 'the readings 10 mi-TLUtes apart over a one hour period. <br /> C. Use the reading obtained during the last 10 minutes to calculate <br /> percolation rate in minutes per inch. <br /> Source: Manual of Septic Tank Practice, U. S. Dept. of H.E.W. ( 1967) <br /> EH 05 10 9/84(90) - Procedure <br /> A Di,sion of San Joaquin County Health Care Services 40 <br />