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(A) The following leaching areas are required for the seepage rates indicated:
Minimum uniform seepage rate time to drop one inch | Square feet of effective seepage area required per bedroom | |||
1 | 2 | 3 | 4 | |
(1) 5 minutes or less | 125 | 250 | 375 | 500 |
(2) 6 to 10 minutes | 165 | 330 | 495 | 660 |
(3) 11 to 20 minutes | 225 | 450 | 675 | 900 |
(4) 21 to 30 minutes | 250 | 500 | 750 | 1000 |
(5) More than 30 minutes | Special consideration needed to avoid nuisance conditions. In some soils it may be impracticable or impossible to use subsurface disposal. | |||
(6) Where a seepage rate slower than one inch in 30 minutes or high ground water is found, no sewage disposal system shall be built. In impervious soil, swamp or rock it may not be feasible to provide subsurface sewage disposal.
(B) All trenches shall follow contours with the bottoms of the individual trenches level. Depth of trenches should normally be not more than 30 to 36 inches, but depths up to 48 inches or greater may be used if warranted by conditions of topography or more favorable absorption capacity of soil at that depth. The width of the trench shall not exceed 36 inches and the spacing between adjacent sides of trenches shall be at least 3 times the width of the trench. The length of individual trenches shall not exceed 75 feet except that in installations where dosing apparatus is used, a maximum length of 100 feet may be used. Distributing pipe shall be laid near the top of a layer of one inch screened gravel or one inch broken stone placed to a depth of at least 18 inches in the trenches. The depth of stone under the pipe invert shall be at least 12 inches. Distributing pipes may be unglazed drain tile, at least 4 inches in diameter, laid with open joints. Pipe of vitrified tile or other acceptable material with suitable perforations or adequate spacing may also be used. The upper portions of joint openings shall be protected by strips of tar paper or other suitable material. Tile lines shall be laid on a grade not exceeding 2 to 4 inches per 100 feet. A layer of salt hay or tar paper shall be placed over the gravel before backfilling the trenches.
(C) Construction shall be such as to provide for proper distribution of settled sewage to trenches. Better distribution, particularly for large systems with several trenches, is secured in tile fields by using siphon dosing apparatus to apply the septic tank effluent. Diverting boxes with several outlets of the same elevation to individual trenches may be used to distribute the sewage. Where trenches are at different levels, serial distribution may be used with high-level overflows from upper to lower trenches.
(D) In seepage beds where space between trenches is also excavated and .backfilled with one inch stone or one inch screened gravel, only 1/3 of the total bottom area shall be considered effective. Distributing pipe shall be laid 6 feet to 8 feet on centers. Installation of stone and distributing pipe shall be the same as that required for leaching trenches. The bottom of the entire bed shall be at the same elevation.
(E) Leaching cesspools shall be spaced 3 times the diameter between sides of adjacent cesspools. Cesspool walls shall be constructed with masonry laid with open joints below the maximum liquid level. The walls shall be surrounded by 12 inches of screened gravel or broken stone.
('66 Code, § 57-17)
No discharges from systems of sewage disposal for commercial building into watercourses shall be made unless provided with treatment as approved by the state department of health and the state water resources commission. No sewage disposal system shall, after the effective date of the regulation, be constructed or rebuilt for any commercial buildings without compliance with the following subdivisions, unless otherwise approved by the director of health. Connections shall be made to public sewers if available.
(A) The location of the disposal system shall comply with the same requirements as those listed above, except that in the case of discharges from laundromats or other commercial or industrial establishments discharging substantial quantities of detergents, the disposal system shall not be permitted, unless special plans are prepared and carried out in accordance with requirements of the local director of health with due regard to the seepage quality of the soil and location of wells. Disposal systems receiving substantial quantities of detergents shall be located at least 200 feet away from any well used as a source of drinking water.
(B) The septic tank shall comply with § 50.12 with regard to construction details and shall have a minimum liquid capacity of 2 cubic feet per employee or equal to the average 24 hour flow, whichever is greater. In no case shall a septic tank be installed with a liquid capacity less than 100 cubic feet. For very large commercial buildings, special arrangements may be required by the director of health. In the case of restaurants, laundromats, toilets for public use, or other types of establishments where water use and sewage flows will depend on the extent of public use or employment of water uses especially pertinent to the type of establishment in question, special allowances for capacities of disposal units and area for future expansion shall be provided as approved by the director of health.
(C) Seepage systems for commercial buildings other than restaurants* and laundries* shall be designed in accordance with the following table:
Minimum uniform seepage rate minutes to drop one inch | Sewage application in gallons to one square foot of effective seepage area; bottom area of trenches, bottom area plus side area of leaching wells below inlet, or 1/3 of gross bottom area of seepage bed |
3 | 3.0 |
5 | 2.5 |
10 | 1.75 |
15 | 1.4 |
20 | 1.1 |
25 | .9 |
30 | .8 |
More than 30 | Special consideration needed to avoid nuisance conditions. In some soils it may be impracticable or impossible to use subsurface disposal. |
(D) Sewage disposal facilities such as privies and other than of the water-carriage type shall be installed only with the permission of the director of health and in accordance with his requirements.
(E) No ground water drainage or drainage from roofs, roads, cellars or yards, or flow of industrial wastes or other liquids that will adversely affect the operation of a system for domestic sewage disposal or cause an overload on the system, shall be discharged into or near a sewage disposal system for a commercial building. The drainage or liquid shall be disposed of separately subject to any requirements considered necessary by the director of health.
('66 Code, § 57-18)
*Editor's Note:
Additional seepage area shall be provided due to clogging characteristics of waste.
Privies shall be constructed with adequate storage space for excreta, with self-closing seat covers and flytight vaults, and with screened vent from the vault to the atmosphere. Privies shall be constructed so as to permit ready cleaning. Separate distances, shall comply with § 19-13-B8, state public health code.
('66 Code, § 57-19)
(A) The application and permit issued for the installation of an individual sewage disposal system expires 6 months from the date of issue if construction of the building has not begun.
(B) A permit for the installation of an individual sewage disposal system is not transferable to a new owner.
('66 Code, § 57-22)