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A percolation test may be required to be performed in the presence of the Building Committee or its designated nominee. This test shall be used as the criterion to determine subsurface seepage. The following procedure shall be used to perform the percolation test.
(A) Size of test holes. Not less than two holes should be tested, each to be dug to the depth of the proposed disposal trenches. One test hole per bedroom to be served is generally adequate. The holes may be dug with an eight-inch posthole digger if desired.
(B) Test procedure. Place two inches of coarse gravel in the bottom of the hole to prevent scouring. Fill hole with clean water to a depth of 12 inches to 18 inches; maintain this level of water in the hole for a period of six to 24 hours; during dry periods, the latter will be necessary. To accomplish this, an automatic syphon from a water container should be provided.
(C) Absorption area needed. Calculate the average time in minutes for the water to fall one inch. Average the results from the holes tested. If the average time is greater than 60 minutes, a seepage field cannot be expected to function satisfactorily, and a sand filter should be considered. The effective absorption area required should then be determined from § 53.075(B).
(D) Special soils. Tests should not be made on filled or frozen ground.
(1975 Code, § 38.39)