The following standards shall apply in the installation, alteration,
repair or extension of individual sewage disposal systems in the Township
of Palmer.
A.
No raw sewage, septic tank effluent or seepage from a
soil absorption system shall be discharged to the surface of the ground or
ground surface water, nor shall it be discharged, except as hereinafter provided,
into any rock formation, the structure of which is not conducive to purification
of water by filtration.
B.
No installations of individual sewage disposal systems
shall be made in low areas or areas which may be subject to flooding.
C.
In areas with a high groundwater table or where limestone
or any geological formation similarly faulty is covered by less than 50 feet
of earth, the final disposal unit shall be a tile field. The bottom of the
trenches shall be above the water table and at least two feet above the surface
of the faulty rock formation.
D.
No bulldozers, trucks or other heavy machinery shall
be driven over the system after installation.
A.
No buried or concealed portion of the building sewer
or building drain or branch thereof serving any premises shall be located
less than the following minimum distances:
|
TABLE I
Sewer and Septic Tank Minimum Distances
| ||
|---|---|---|
|
Requirement
|
Distance
(feet)
| |
|
Property line
|
10
| |
|
Occupied buildings
|
10
| |
|
Buried water pipe under pressure
|
10
| |
|
Domestic water supply
|
50
| |
|
Buried water pipe under suction
|
50
| |
B.
The portions of any buried sewer more than 50 feet from
a well or buried suction line shall be of adequate size and constructed of
cast-iron, vitrified clay, cement-asbestos or bituminized fiber pipe. Any
building drain or building sewer constructed of cast iron or cement and asbestos
shall be not less than four inches in diameter, and any building sewer constructed
of material other than cast iron or cement-asbestos shall be not less than
six inches in diameter.
C.
Bell and spigot of vitrified clay pipe shall be prepared
to form a concentric opening uniform in width around the pipe, of which the
opening shall be filled with an acceptable sewer joint compound. Cement joints
shall be painted on the outside and left smooth on the inside by drawing a
swab or scraper through the joint. The line shall have a grade of not less
than 1/8 inch per foot. The 10 feet of sewer immediately preceding the septic
tank shall slope not more than 1/4 inch per foot. No ninety-degree ells shall
be permitted, and where the direction of the sewer is changed in excess of
45º, accessible cleanouts shall be provided.
A.
No septic tank shall be located to provide less than
the minimum distances as stated in Table I.
B.
The liquid capacity of a septic tank serving a dwelling
shall be based on the number of bedrooms contemplated in the dwelling, which
is listed in the following Table II.
|
TABLE II
Minimum Capacities for Septic Tanks
(Provides for use of garbage grinders, automatic washers and other
household appliances)
| ||
|---|---|---|
|
Number of Bedrooms
|
Minimum Tank Capacity
(gallons)
| |
|
3
|
900
| |
|
4
|
1,000
| |
|
Each additional
|
250
| |
|
The liquid capacity of a septic tank shall provide a sewage detention
period of not less than 24 hours in the tank. Sewage flow shall be computed
according to types of establishment and water use. With sewage flows greater
than 1,500 gallons per day, the liquid tank capacity shall equal 1,125 gallons
plus 75% of the daily anticipated sewage flow.
| ||
C.
The liquid depth of any septic tank or compartment thereof
shall be not less than 30 inches nor greater than six feet.
D.
No tank or compartment thereof shall have an inside horizontal
dimension less than 36 inches.
E.
Inlet and outlet connections of the tank and of each
compartment thereof shall be submerged by means of vented tees or baffles.
F.
The space in the tank between the liquid surface and
the top of the tank shall be not less than 20% of the total required liquid
capacity, except that in horizontal cylindrical tanks this space shall be
not less than 15% of the total required liquid capacity.
G.
The inlet baffle or submerged pipe shall extend below
liquid level at least six inches. In no case shall this penetration be greater
than that allowed for the outlet device. The inlet baffle must extend at least
one inch above the crown of the inlet sewer.
H.
The outlet baffles or submerged pipe and the baffles
or submerged pipes between compartments shall extend below the liquid surface
not less than 12 inches or a distance equal to 40% of the liquid depth. The
penetration of the outlet baffles or submerged pipes of a horizontal cylindrical
tank shall be 35% of the total liquid depth.
I.
There shall be at least one inch between the underside
of the top of the tank and the highest point of the inlet and outlet devices
and partitions, to provide the required ventilation of the system through
the main building stack.
J.
The inlet invert shall be a minimum of three inches above
the level of the outlet invert.
K.
The tank shall be watertight, constructed of sound and
durable material and not subject to excessive corrosion or decay.
L.
Access to each compartment of the tank for inspection
and sludge removal shall be provided by a manhole of at least twenty-inch
dimension or removable cover. Where the top of the tank is located more than
18 inches below the finished grade, manholes and inspection holes shall extend
to approximately eight inches below the finished grade.
M.
If the septic tank has more than one compartment, the
first compartment shall have a liquid capacity equal to at least 1/2 of the
total liquid capacity.
A.
The disposal field shall be located in an unobstructed
and unshaded area. The distance given below shall be the minimum horizontal
separations between the disposal field and the following:
|
TABLE III
Location of Subsurface Disposal Field
| ||
|---|---|---|
|
Requirement
|
Distance
(feet)
| |
|
Any water supply or buried water suction pipe
|
100
| |
|
Streams
|
50
| |
|
Occupied buildings
|
10
| |
|
Large trees
|
10
| |
|
Property lines or buried pipe distributing water under pressure
|
10
| |
B.
When coarse soil formations are encountered, the 100
feet distance specified in the first item of Table III may be increased by
the Department.
C.
Effluent from the septic tank shall be discharged to
the absorption field through a watertight line with a grade of at least 1/4
inch per foot. Serial distribution of, effluent may be required where the
grade of the ground surface exceeds six inches in any direction within the
area utilized for the absorption field.
D.
When a distribution box is used, it shall have a removable
cover and ensure equal distribution of effluent to tile field lateral lines.
At least two lateral lines shall lead from the box.
(1)
Each tile field lateral line shall be connected separately
to the distribution box and shall not be subdivided.
(2)
The inverts of all outlets shall be at the same elevation,
and the inlet invert shall be at least one inch above the outlet inverts.
(3)
The outlet inverts shall be at least four inches above
the bottom of the distribution box for the purpose of securing equal distribution
of the septic tank effluent to each tile lateral.
(4)
In the event that septic tank effluent is discharged
to the distribution box by pump or siphon a baffle shall be installed in the
distribution box. The baffle shall be secured to the bottom of the box and
shall extend vertically to a point at level with the crown of the inlet pipe.
The plane surface of the baffle shall be perpendicular to the inlet floor
line.
E.
Minimum seepage area of the disposal field shall be determined
by a stabilized percolation rate. The soil shall have an acceptable percolation
rate, without interference from groundwater or impervious strata below the
level of the absorption system. The following conditions shall be met:
(1)
The maximum elevation of the groundwater table shall
be at least four feet below the surface. Rock formations or other impervious
strata shall be at a depth greater than four feet below the bottom of the
trench.
(2)
The percolation time shall be within the range of those
indicated in the following table.
|
TABLE IV
Absorption Area Requirements for Private Residences
(Provides for garbage grinder and automatic-sequence washing machines)
| ||
|---|---|---|
|
Required Absorption Percolation Rate
(time required for water to fall 1 inch)
(in minutes)
|
Area
(per bedroom; standard trench and seepage pits)
(in square feet)
| |
|
1 or less
|
70
| |
|
2
|
85
| |
|
3
|
100
| |
|
4
|
115
| |
|
5
|
125
| |
|
10
|
165
| |
|
15
|
190
| |
|
30
|
250
| |
|
45
|
300
| |
|
60
|
330
| |
|
NOTES:
| |
|---|---|
|
1.
|
In every case, sufficient area shall be provided for at least two bedrooms.
|
|
2.
|
Absorption area for standard trenches is computed as trench-bottom area.
|
|
3.
|
Absorption area for seepage pits is computed as effective sidewall area
beneath the inlet.
|
|
4.
|
Soils are unsuitable for seepage pits if the percolation rate is 30
minutes or more, and are unsuitable for any subsurface leaching system if
the percolation rate is 60 minutes or more.
|
|
TABLE V
Absorption Area Requirements for Other Establishments
| ||
|---|---|---|
|
Percolation Rate
(Time required for water to fall 1 inch)
(in minutes)
|
Maximum Rate of Sewage Application for Standard Trenches and Seepage
Pits
(gallons per square foot per day)
| |
|
1 or less
|
5.0
| |
|
2
|
3.5
| |
|
3
|
2.9
| |
|
4
|
2.5
| |
|
5
|
2.2
| |
|
10
|
1.6
| |
|
15
|
1.3
| |
|
30
|
0.9
| |
|
45
|
0.8
| |
|
60
|
0.6
| |
|
NOTES:
| |
|---|---|
|
1.
|
These figures do not include effluents from septic tanks that receive
wastes from garbage grinders and automatic washing machines.
|
|
2.
|
Absorption area for standard trench is computed as trench-bottom area.
|
|
3.
|
Absorption area for seepage pits is computed as effective sidewall area
beneath the inlet.
|
|
4.
|
Soils are unsuitable for seepage pits or leaching systems if the percolation
rate is 30 minutes or more.
|
F.
Construction of disposal trenches.
(1)
Trenches in a disposal field shall be constructed in
accordance with the following standards:
(a)
Minimum number of lines per field: two.
(b)
Maximum length of individual lines: 100 feet.
(c)
Minimum bottom width of trench: 12 inches.
(d)
Maximum bottom width of trench: 36 inches.
(e)
Minimum depth of tile lines (bottom): 18 inches.
(f)
Maximum depth of tile lines (bottom): 36 inches.
(g)
Uniform grade of tile trench: two to four inches per
100 feet.
(h)
Uniform grade of tile lines: two to four inches per 100
feet.
(i)
Minimum aggregate material under tile: six inches.
(j)
Minimum aggregate material over tile: two inches.
(k)
Spacing of trenches:
|
TABLE VI
Distances Between Trenches
| ||
|---|---|---|
|
Minimum Distance Trench Width
(inches)
|
Between Center Line of Trenches
(feet)
| |
|
12 to 18
|
6
| |
|
18 to 24
|
6.5
| |
|
24 to 30
|
7.0
| |
|
30 to 36
|
7.5
| |
(2)
Pipe used for the line between the septic tank and distribution
box and between the distribution box and tile laterals to the point when the
laterals are separated shall have watertight joints. Pipes used under driveways
or other areas subject to heavy loads shall be bell-and-spigot cast iron with
leaded caulked joints or equal.
(3)
Field tile used in the disposal field shall be four-inch
agricultural drain tile 12 inches in length and shall be laid with one-fourth-inch
open joints. Alternate materials may be used if equivalent performance is
indicated.
(4)
Aggregate materials shall be crushed stone, gravel or
similar insoluble, durable and acceptable material 1/2 to 2 1/2 inches in
size. The filter materials shall completely encase the tile.
(5)
The top of the aggregate material shall be covered with
untreated building paper or a two-inch layer of hay or straw to prevent settling
of backfill material into the filter material.
(6)
The trench above the aggregate material shall be filled
over and hand-tamped with four to six inches of earth.
G.
Seepage pits.
(1)
Seepage pits shall be used for disposal of septic tank
effluent only when the installation of tile disposal trenches is due to unfavorable
soil absorption in topsoil mantle, groundwater level, topography, and will
not reduce the safety of surrounding water supplies. The pit excavation shall
terminate at least four feet above the highest known or calculated water table.
(2)
The location of seepage pits shall be not less than the
stated minimum distances from the following:
(3)
Effective absorption area of a seepage pit is the vertical-wall
area (based on dug diameter) of the impervious strata below the inlet.
(a)
Required seepage area shall be determined by the percolation
test made in each vertical stratum penetrated. The weighted average of the
results shall be computed to obtain a design figure. Soil strata in which
the percolation rates are in excess of 30 minutes per inch shall not be included
in computing the absorption area. No allowance shall be made for impervious
strata or bottom area.
(b)
All pits shall have a diameter of at least four feet.
(4)
Construction of all seepage pits shall conform to the
following requirements:
(a)
To prevent cave-in, the pit shall be lined with brick,
stone or block at least four inches thick, laid in a radial arch to support
the pit walls.
(b)
The brick, stone or block shall be laid watertight above
the inlet and with open joints below the inlet to provide adequate passage
of liquids.
(c)
A minimum annular space of six inches between the lining
and excavation wall shall be filled with crushed rock or gravel.
(d)
The top of the seepage pit shall be constructed to be
capable of supporting the overburden of earth and any reasonable load to which
it is subjected. Access to the pit shall be provided by means of a manhole
or inspection hole equipped with a watertight cover. The seepage pit may terminate
in a conventional manhole top, frame and cover. The top of the seepage pit
shall be not less than 12 inches below the ground surface. Where the top is
more than 18 inches below the ground surface, there shall be provided an inspection
pipe of not less than four-inch diameter extending through the cover to a
point above the tank not more than six inches below finished ground level.
The top of the inspection pipe shall be provided with a removable watertight
cap and its location shall be marked at the ground surface.
