// CODE SNIPPET
H601.0 Disposal Fields
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Distribution lines shall be
constructed of clay tile laid with open joints, perforated clay
pipe. perforated bituminous fiber pipe. perforated high-density
polyethylene pipe, perforated ABS pipe, perforated
PVC pipe, or other approved materials, provided that
approved openings are available for distribution of the
effluent into the trench area.
Before placing filter material or
drain lines in a prepared excavation, smeared or compacted
surfaces shall be removed from trenches by raking to a
depth of 1 inch (25.4 mm) and the loose material removed.
Clean stone, gravel, slag, or similar filter material acceptable
to the Authority Having Jurisdiction, varying in size
from 3/4 of an inch to 21/2 inches (19.1 mm to 64 mm), shall
be placed in the trench to the depth and grade required by
this section. Drain pipe shall be placed on filter material in
an approved manner. The drain lines shall then be covered
with filter material to the minimum depth required by this
section, and this material covered with untreated building
paper, straw, or similar porous material to prevent closure
of voids with earth backfill. No earth backfill shall be
placed over the filter material cover until after inspection
and acceptance.
Exception: Listed or approved plastic leaching chambers and bundled expanded polystyrene synthetic aggregate units shall be permitted to be used in lieu of pipe and filter material. Chamber and bundled expanded polystyrene synthetic aggregate unit installations shall follow the rules for disposal fields, where applicable, and shall be in accordance with the manufacturer's instructions.
Exception: Listed or approved plastic leaching chambers and bundled expanded polystyrene synthetic aggregate units shall be permitted to be used in lieu of pipe and filter material. Chamber and bundled expanded polystyrene synthetic aggregate unit installations shall follow the rules for disposal fields, where applicable, and shall be in accordance with the manufacturer's instructions.
Where seepage pits are used in combination
with disposal fields, the filter material in the
trenches shall terminate not less than 5 feet (1524 mm)
from the pit excavation, and the line extending from such
points to the seepage pit shall be approved pipe with watertight
joints.
Where two or more drain
lines are installed, an approved distribution box of sufficient
size to receive lateral lines shall be installed at the
head of each disposal field. The inverts of outlets shall be
level, and the invert of the inlet shall be not less than 1 inch
(25.4 mm) above the outlets. Distribution boxes shall be
designed to ensure equal flow and shall be installed on a
level concrete slab in natural or compacted soil.
Laterals from a distribution box to the
disposal field shall be approved pipe with watertight joints.
Multiple disposal field laterals, where practicable, shall be
of uniform length.
Connections between a septic tank
and a distribution box shall be laid with approved pipe with
watertight joints on natural ground or compacted fill.
Where the quantity of sewage
exceeds the amount that is permitted to be disposed in 500
lineal feet (152.4 m) of leach line, a dosing tank shall be
used. Dosing tanks shall be equipped with an automatic
siphon or pump that discharges the tank once every 3 or 4
hours. The tank shall have a capacity equal to 60 to 75
percent of the interior capacity of the pipe to be dosed at
one time. Where the total length of pipe exceeds 1000 lineal
feet (304.8 m), the dosing tank shall be provided with two
siphons or pumps dosing alternately and each serving one-half
of the leach field.
Disposal fields shall be constructed
in accordance with Table H 601.9.
Minimum spacing between trenches or leaching beds shall be not less than 4 feet (1219 mm) plus 2 feet (610 mm) for each additional foot (305 mm) of depth in excess of 1 foot (305 mm) below the bottom of the drain line. Distribution drain lines in leaching beds shall be not more than 6 feet (1829 mm) apart on centers, and no part of the perimeter of the leaching bed shall exceed 3 feet (914 mm) from a distribution drain line. Disposal fields, trenches, and leaching beds shall not be paved over or covered by concrete or a material that is capable of reducing or inhibiting a possible evaporation of sewer effluent.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 inch per foot = 83.3 mm/m
Minimum spacing between trenches or leaching beds shall be not less than 4 feet (1219 mm) plus 2 feet (610 mm) for each additional foot (305 mm) of depth in excess of 1 foot (305 mm) below the bottom of the drain line. Distribution drain lines in leaching beds shall be not more than 6 feet (1829 mm) apart on centers, and no part of the perimeter of the leaching bed shall exceed 3 feet (914 mm) from a distribution drain line. Disposal fields, trenches, and leaching beds shall not be paved over or covered by concrete or a material that is capable of reducing or inhibiting a possible evaporation of sewer effluent.
MINIMUM | MAXIMUM | |
---|---|---|
Number of drain lines per field | 1 | - |
Length of each line | - | 100 feet |
Bottom width of trench | 18 inches |
36 inches |
Spacing of lines, center-to-center | 6 feet |
- |
Depth of earth cover of lines (preferred -18 inches) |
12 inches |
- |
Grade of lines | Level | 3 inches per 100 feet |
Filter material under drain lines | 12 inches | - |
Filter material over drain lines | 2 inches | - |
Where necessary on sloping ground to
prevent excessive line slope, leach lines or leach beds shall
be stepped. The lines between each horizontal section shall
be made with watertight joints and shall be designed so each
horizontal leaching trench or bed shall be utilized to the
maximum capacity before the effluent shall pass to the next
lower leach line or bed. The lines between each horizontal
leaching section shall be made with approved watertight
joints and installed on natural or unfilled ground.
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