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Resolution No. 983 <br />Page 2 <br />2. Cont. <br />Percolation Test Procedure <br />1. Type of Test Hole <br />A hole with horizontal dimensions of 6" and vertical sides <br />shall be dug or bored to the depth of the proposed absorption <br />trench. <br />2. Preparation of Test Hole <br />The bottom and sides of the hole shall be carefully scratched <br />With a knife blade or sharp pointed instrument to remove any <br />smeared soil surfaces and to provide a natural soil interface <br />into which water may percolate. All loose material shall be <br />removed from the hole and two (2) inches of coarse sand or <br />fine gravel shall be added to protect the bottom from scouring <br />and sediment. , <br />.3. Saturation and Swelling of the Soil <br />. The hole shall be carefully filled with clear water to a minimum <br />depth of 12" over, the gravel. Water shall be kept in the hole <br />for at least four (4) hours., and preferably overnight by refilling <br />if necessary, or by supplying a surplus reservoir of water, such <br />as in an automatic siphon. In sandy soils containing little or <br />no clay, the swelling procedure shall not be required and the <br />test may be made after the water from one filling of the hole <br />_ has completely seeped away. <br />4. Percolation Rate Measurement <br />With the exception of sandy soils, percolation rate measurements <br />shall be made on the day following the procedure described under <br />Items 1 - 3 above. <br />A. If water remains in the hole after the overnight swelling <br />period, bail out all but 6" of the water above the fine <br />gravel (8" if measured from the bottom of the hole). <br />Then measure the drop in water level 'to the nearest 1/16" <br />approximately every 30 minutes. Use a measuring stick <br />with the top of a level batter board as a reference point.. <br />Continue the test until the extremes of three consecutive <br />measurements vary by a range of no more than 10%. <br />