The lines of the tile field shall be constructed so as to fall more than one inch (1") in fifty feet (50') of tile, and no single line shall exceed one hundred feet (100') in length. A minimum spacing of six feet (6') between seepage lines should be provided. Trenches shall be not less than two feet (2') nor more than three feet (3') wide, and of sufficient depth to accommodate the purpose for which they are designed. Tile shall be laid on at least a six inch (6") bed of gravel or crushed rock, from which material smaller than one-half inch (1/2") has been screened out. From type tile, at least four inches (4"), laid with the ends between one-eighth inch (1/8") to one-fourth inch (1/4") apart, shall be used. Tarred paper or roofing cut in strips shall be placed over the top half of the tile, and gravel of the same consistency previously described, shall be filled until at least two inches (2") level above the top of the tile is maintained. (Ord. 267, 9-27-1961)