(a) Design and Construction. Disposal trenches shall be designed and constructed on the basis of the required area.
(b) Filter Material. Filter material shall cover the tile to a depth of not less than three inches, extend the full width of the trench and be not less than twenty-four inches deep beneath the bottom of the tile and the top of the filter drain. The filter material may be washed gravel, crushed stone, slag or clean bank-run gravel ranging in size from one-half to two and one-half inches. The surface of the filter material shall be covered by untreated paper or by a two-inch layer of straw.
(c) Disposal Fields. Disposal fields shall have an area of at least 250 square feet and be constructed with distribution lines laid on thirty-inch centers. The depth of trenches shall be the minimum consistent with subsection (b) hereof.
(d) Distribution Lines. Distribution lines shall be constructed of tile laid with open joints. In the case of bell and spigot tile, it should be laid with one-half inch open joints at two-foot intervals with sufficient cement mortar at the bottom of the joint to ensure an even flow line. In the case of agricultural tile, the sections shall be spaced not more than one-fourth of an inch apart. Perforated clay tile, perforated bituminized-fiber pipe or asbestos cement pipe may be used, provided that sufficient openings are available for distribution of the effluent into the trench area.
(e) Filter Drain. One filter drain shall be laid at the bottom of the trench at the center. It shall be constructed of vitrified sewer crock laid with one-half inch open joints using four inch crock if used to drain the filter alone and six-inch crock when storm lines are connected to it. Such drain shall be laid with a minimum grade of one-eighth of an inch per foot.
(Ord. 1967-29. Passed 9-6-67.)