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i <br /> TO: ENVIRONMENTAL HEALTH STAFF <br /> FROM: C. LELAND HALL , R.S. , Director <br /> RE: PERCOLATION TEST PROCEDURE <br /> DATE: February 27, 1931 <br /> I. Measurements of the Percolation Test Dole. <br /> A. Diameter = 4 inche' 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. 1 - if water remains in the test hole overnight. <br /> A. 24 hours after water is first added to the hole, add clear <br /> water to approximately 6 inches over the caravel . <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. Pr dllrP � 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 dro in water level at <br /> approximately 30 minute intervals for four (4� hours , refilling <br /> 6 inches over the gravel as necessary. C3 � ff,t <br /> C. Use the reading during the last 30 minutes of the four hour period <br /> to calculate percolation rate in minutes per inch. <br /> VI. , .- in sandy soils (or other soils) in which the first 6 inches <br /> o water <br /> period. seeps away in less than 30 minutes after the overnight swelling <br /> A. Refill the hole to approximafe-ly 6 inches above the gravel . <br /> B. Take the readings 10 minV_tes apart oyer 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 />