(a) Disposal Trenches; Design. Disposal trenches shall be designed and
constructed on the basis of the required area.
(b) Filter Material. The filter material shall cover the tile to a depth of not less than three inches and extend the full width of the trench, and shall 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 onehalf layer of straw.
(c) Disposal Field. A disposal field shall have an area of at least 250 square feet and shall be constructed with distribution lines laid on thirty inch centers. Depth of trenches shall be the minimum consistent with subsection (b) hereof.
(d) Distribution. Distribution lines shall tee 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 insure an even flow line. In the case of agricultural tile, the sections shall be spaced not more than one-fourth inch apart. Perforated clay tile or 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 center to be constructed of vitrified sewer crock laid with one-half inch open joints using four inch crock if used to drain filter alone and six inch crock when storm lines are connected to it. The drain shall be laid with minimum grade of one-eighth inch per foot.
(1973 Code Sec. 51.36 to 51.40)
(1973 Code Sec. 51.36 to 51.40)