(A) Disposal field construction:
Disposal Field Construction | Minimum Standard |
Disposal Field Construction | Minimum Standard |
Lines per field, minimum number | 2 |
Individual lines, maximum length | 100 feet |
Trench bottom, minimum width | 18 inches |
Trench bottom, maximum width | 36 inches |
Field tile, minimum diameter | 4 inches |
Field tile, lines, maximum slope | 6 inches/100 feet |
Field trenches, minimum separation (see schedule; division (D) below) | |
Effective absorption area, minimum per dwelling unit (division (B) below) | 200 square feet |
(B) Absorption areas for individual residences or apartment unit:
Time Required for Water to Fall 1 Inch (Minutes) | Effective Absorption Area Required in Bottom of Disposal Trenches (Square Feet per Bedroom) |
2 or less | 70 |
Over 60 | Install sand filter |
(C) When an automatic washing machine is installed or contemplated, the effective total absorption area shall be increased 25%. Where garbage disposal units are installed, the effective absorption area shall be increased 50%.
(D) Size and spacing for disposal field:
Width of Trench At Bottom (inches) | Depth of Trench (inches) | Spacing Tile Lines (feet) | Effective Absorption Area per lineal foot (sq. ft.) |
18 | 18 to 30 | 6.0 | 1.5 |
24 | 18 to 30 | 6.0 | 2.0 |
30 | 18 to 36 | 7.6 | 2.5 |
36 | 24 to 35 | 9.0 | 3.0 |
(E) Absorption lines should be constructed of farm tile laid with open joints. The tile sections should be spaced not more than one-fourth inch apart, and the upper-half of the joint should be protected by asphalt treated paper while the tile is being covered. 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.
(F) The bedding material shall extend the full width of the trench and shall be not less than six inches deep beneath the bottom of the tile. After the tile has been laid, the bedding material shall be brought up to a level two inches above the top of the tile. The bedding material may be washed gravel, crushed stone, slag or clean bank-run gravel, ranging in size from one-half inch to two and one-half inches. The bedding material should be covered by a two-inch layer of pea gravel or straw to support the backfill as the laying of the tile drain proceeds.
(1975 Code, § 38.36)