A septic tank shall have an effective liquid
capacity of not less than 150% of the design flow estimated, but in
no case less than 1,000 gallons.
Garbage grinders are not allowed.
The liquid depth of the tank shall be a minimum
of four feet. The tank may be oval, circular, rectangular or square
in plan provided that the distance between outlet and inlet of the
tank is at least equal to the liquid depth of the tank.
Multicompartment tanks with transverse baffles
may be used, provided that:
Tanks in series may be approved, provided that the capacity of the first tank is at least equal to the required capacity pursuant to § 223-54 and provided that the number of tanks does not exceed two.
Septic tanks shall not be installed in such
a manner that the sewage flow from a single sewer is divided, with
one portion being discharged to one tank and the remaining portion
being discharged to a second tank.
Septic tanks shall be watertight and constructed
of sound and durable material not subject to excessive corrosion,
decay or frost damage or to cracking and buckling due to settlement
or backfilling. Tanks and covers shall be designed and constructed
so as to withstand anticipated loadings. Any tank installed in a location
where there is high groundwater shall be weighted to prevent the tank
from floating when it is emptied.
Inlet and outlet shall be of cast iron. Schedule
40 PVC or cast-in-place concrete and shall extend a minimum of six
inches above the flow line of the septic tank and be on the center
line of the septic tank located directly under the cleanout manhole.
There shall be an air space of at least three inches between the tops
of the tees and the inside of the tank cover, and the tops of the
tees shall be left open to provide ventilation, or separate ventilation
shall be provided.
The inlet tee (baffles are not acceptable) shall
extend a minimum of 10 inches below the flow line. The outlet shall
be provided with a fee extending below the flow line in accordance
with the following table:
|
Liquid Depth in Tank
(feet)
|
Depth of Outlet Tee Below Low Line
(inches)
|
|---|---|
|
4
|
14
|
|
5
|
19
|
|
6
|
24
|
|
7
|
29
|
|
8
|
34
|
Septic tanks shall be installed on a level,
stable base that will not settle.
Septic tanks may be constructed of poured reinforced
concrete, precast reinforced concrete or prefabricated materials acceptable
to the approving authority.
At least one twenty-four-inch manhole with readily
removable cover of durable material shall be provided for each compartment.
Inlet and outlet tees shall be made accessible for cleaning by providing
manholes over the tees. Manhole covers for septic tanks serving single-family
dwellings shall not be more than 12 inches below finished grade and
may, at the discretion of the approving authority, be required to
be brought to finished grade. Septic tanks serving other establishments
with flows under 2,000 gallons per day shall be provided with at least
one twenty-four-inch diameter manhole located over the inlet tee and
a metal frame and cover to finished grade. Septic systems designed
for flows in excess of 2,000 gallons per day shall be provided with
at least two twenty-four-inch diameter manholes (over inlet and outlet
tees), with metal frames and covers at finished grade. Distance between
access manholes shall not exceed 18 feet on center.
Septic tanks shall be located on the lot so
as to be accessible for servicing and cleaning.
The invert elevation of the inlet of a septic
tank shall be at least two inches above the invert elevation of the
outlet.
Backfill around the septic tank shall be placed
in such a manner as to prevent damage to the tank.
Septic tanks should be inspected and cleaned
annually.
The invert elevation of the septic tank outlet
shall be at least one foot above the maximum groundwater elevation.
Pumping of sewage to a septic tank shall not
be allowed without the written approval of the Department of Environmental
Quality Engineering.
