Loading...
(A) A septic tank shall be provided for water-carriage sewage disposal where no public sewer is available. The septic tank shall be constructed with watertight walls and bottom, with inlet baffled or submerged for a depth of 12 to 18 inches and outlet baffled or submerged to a depth of at least 18 inches below the surface of liquid in the tank but not more than half the liquid depth. Baffles shall extend 6 inches above the liquid level. The outlet invert shall be 3 inches lower than the inlet invert. With a 2 compartment tank there shall be adequate connections at mid-depth, and 2/3 or more of the required capacity shall be in the first compartment. A septic tank shall have a removable cover, or manhole, so as to provide access to the tank for purposes of inspection and cleaning. At least 2 manholes shall be provided for a tank more than 10 feet long and at least one manhole per compartment. If a manhole is not located over the inlet, an inspection opening shall be provided at that point. No septic tank shall have a liquid capacity of less than 750 gallons below the outlet invert. The minimum liquid depth of septic tanks shall be 36 inches, measured from the bottom of the invert to the outlet. There shall be a minimum of 8 inches between the liquid level and the underside of the tank cover.
(B) The minimum liquid capacities are as follows:
(1) Two bedrooms, 750 gallons;
(2) Three bedrooms, 900 gallons;
(3) Four bedrooms, 1,200 gallons;
(4) Larger sizes, add 250 gallons per bedroom.
(5) Where additional capacity is needed, 2 tanks may be used in series for one installation. No more than 2 tanks shall be installed in series but larger tanks shall be used to make up the required capacity.
(C) If a garbage disposal system is used in connection with a septic tank, 50% more liquid volume shall be required for the septic tank.
(D) Sink drainage or laundry water systems, where no water-flush toilet fixtures are connected, shall be constructed with a septic tank and seepage system at least 1/2 the capacity specified for usual house sewerage systems.
('66 Code, § 57-13)
Distribution box of sufficient size to accommodate the necessary field lateral lines shall be constructed at the head of each disposal field:
(A) Each field lateral line shall be connected separately to the distribution box and shall not be subdivided.
(B) The invert of all outlets shall be level, and the inlet invert shall be at least one inch above the outlets.
(C) If the level of the outlet inverts is less than 4 inches above the floor of the box, distribution baffles shall be provided. Note: If the level of the outlet inverts is from 4 to 6 inches above the floor of the box, permitting water retention to act in lieu of a baffle, the baffles will not be required. The level of the outlet inverts should not be more than 6 inches above the floor of the distribution box.
('66 Code, § 57-14)
(A) Disposal of septic tank effluent may be by means of tile or other accepted distributing pipe laid in screened gravel or broken stone, or by means of leaching cesspools. Seepage systems shall not be located in fill placed over impervious soil.
(B) Leaching cesspools may be preferable where the amount of area is limited or where porous soil is at a greater depth than can be secured by tile fields. They are not recommended where ground water may interfere with their operation, or where soil of better seepage quality is found at shallow depth. Leaching cesspools shall not extend to rock.
('66 Code, § 57-15)
The classification of soil, at the proposed location of a seepage system, shall be determined by soil tests made as follows:
(A) For cesspools, a hole 4 inches to 12 inches in diameter shall be dug, extending to the depth of the proposed cesspool. For tile field, a hole 4 inches to 12 inches in diameter shall be dug, extending to the depth of the proposed trenches.
(B) Before observations are made, the pit shall be thoroughly wet down by filling it to a depth of at least 12 inches. The pit shall then be refilled with water to a depth of 12 inches or more and the rate of drop of water measured at intervals for a period of 30 to 60 minutes under normal conditions. The minimum or slowest uniform rate of drop shall be used in calculating seepage areas. When tests are made, consideration shall be given to the finished grade of building sites so that results will correspond to the absorptive value of the soil in which the leaching systems will be constructed. In investigating soil conditions for a large area, one test pit per acre or even one per lot may be required. Also, in investigating soil conditions, deep test pits may be required to check for ground water, ledge rock, or available good seepage soil below normal depths.
('66 Code, § 57-16)
(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)
Loading...