Current through all regulations passed and filed through September 16, 2024
(A)
When siting a
STS, existing drain tile, or other artificial subsurface drainage present on
the lot shall comply with the following:
(1)
Shall be avoided
whenever possible and shall maintain at least eight feet of horizontal
separation from the soil absorption component of a STS;
(2)
Existing
drainage tile that intersects the soil absorption area shall be rerouted where
possible. When tile is re-routed, the abandoned section of tile shall either be
plugged with bentonite, cement or concrete, or removed to at least ten feet
from the soil absorption component of the sewage treatment system, or broken up
in place to prevent movement of water;
(3)
Where existing
sites may have close drain spacing and removal of the drainage is not
practical, the design shall prevent migration of effluent to the drain;
and
(4)
Existing drainage on the lot may be used if necessary
to facilitate drainage as long as isolation distances and VSDs are
met.
(B)
When surface water runoff will infiltrate or cause
ponding in, on or around STS components, diversion swales or other grading
shall be designed to intercept and divert surface water with specifications
indicated in the design plan. STS components shall not be sited in depressions
or concave topographic features where surface water runoff cannot be properly
managed through diversion. Diversion of surface water associated with a STS
shall not negatively impact drainage of or onto other properties or storm water
management.
(C)
An interceptor drain shall be sited no closer than six
feet upslope of a soil absorption component, and shall prevent effluent from
entering the interceptor drain. The specifications for the interceptor drain
shall comply with paragraphs (D) and (E) of this rule, and shall be included in
the design plan.
(D)
A perimeter drain intended to create a gradient to
improve the drainage of a site with seasonal saturation or an engineered
drainage system designed in accordance with appendix A to this rule shall meet
the following:
(1)
Be sited no closer than six feet on the upslope side
of the soil absorption component and eight feet from the outermost extent of
the other sides of the soil absorption component and shall not cross any
portion of the soil absorption component;
(2)
Where a flow
restrictive layer is present, the bottom elevation of the perimeter drain must
be installed no deeper than two inches into the flow restrictive horizon except
when the bottom elevation must be deeper to allow for proper drainage at the
outfall;
(3)
The bottom elevation of the perimeter drain shall
maintain sufficient vertical distance between the bottom of the perimeter
drain, and the bottom of the soil absorption component to induce flow to the
drain;
(4)
Be designed and constructed to ensure subsurface flow
of water to the drain;
(5)
Be limited to sites with at least six inches of
unsaturated soil beneath the bottom of the infiltrative surface of the soil
absorption component of the STS unless the STS design uses a pretreatment
component approved for meeting the one-thousand fecal coliform CFU per one
hundred milliliters standard prior to dispersal to the soil;
and
(6)
Be sited not less than eight feet from a mound lateral
or one foot from the toe of the mound.
(E)
Subsurface
drainage shall comply with the following:
(1)
The drainage
pipe shall be slotted pipe four inches in diameter;
(2)
Drainage pipe
wrapped with a geotextile fabric shall not be used when the soil has a silt
content greater than forty per cent;
(3)
The subsurface
drain trench shall have a positive slope of at least one-tenth foot per one
hundred feet;
(4)
The drainage pipe shall be backfilled with a minimum
of ten inches of coarse aggregate. As determined by the designer or the local
board of health, a subsurface drain trench may be backfilled to final grade or
to within six inches of final grade with coarse aggregate, and the final six
inches, if applicable, to final grade with cover soil material. When ground
water can develop velocities sufficient to move sand or silt or both into the
drain, filter or drain envelopes may be required in lieu of the coarse
aggregate envelope. Filter or drain envelopes must be able to restrict the
movement of sand and/or silt into the drain pipe so that the hydraulic capacity
of the drain pipe is maintained. Filter or drain envelopes should be installed
according to the manufacturers specifications, or in accordance with part 650,
chapter 14 of the NRCS, national engineering handbook; and
(5)
The subsurface
drain trench and the associated discharge piping shall be designed to have
water flow by gravity from the drain when possible.
(F)
Engineered
drainage shall be designed in accordance with appendix A to this rule to lower
seasonal saturation in the soil across the soil absorption area throughout the
year to provide a sufficient thickness of unsaturated soil to meet the vertical
separation distance requirements. Engineered drains shall meet the following
requirements:
(1)
Water discharged from engineered drainage systems
shall not create a public health nuisance as defined in section
3718.011 of the Revised
Code;
(2)
Engineered drainage systems shall be properly
installed and maintained to ensure consistent operation during the life of the
STS;
(3)
A STS design that proposes to use an engineered
drainage system shall identify the depth to the seasonal water table with no
drainage and the depth to which the seasonal water table will be lowered with
drainage to demonstrate that the vertical separation distance required is met;
and
(4)
The engineered drainage design shall demonstrate that
the proposed drain spacing and depth can lower the seasonal water table to the
desired depth to achieve a thickness of unsaturated soil to meet the vertical
separation distance required at least three hundred and thirty days each year,
with no more than thirty days of continuous saturation above the desired depth,
at a recurrence frequency of thirty per cent (an average of at least nine years
in thirty).
(G)
A drainage outlet for interceptor, perimeter, or
engineered drain shall comply with the following:
(1)
The drainage
outlet must be accessible, include rigid solid wall pipe and animal guard, and
shall be designed to allow for free flow from the invert of the pipe for the
purpose of sampling. Where the drainage outlet is not accessible a sampling
port may be required;
(2)
The drainage outlet shall be designed and installed to
prevent clogging by siltation or vegetative growth and accessibility shall be
maintained for cleaning;
(3)
The drainage outlet must have sufficient freeboard
above typical annual maximum flow to ensure the drain flows in all seasons. The
invert of the pipe for a gravity flow outlet shall be at least four inches
above the water level of the receiving stream or ground surface, whichever is
closer;
(4)
If a gravity flow outlet cannot be achieved the drain
shall include a pump vault accessible for sampling and of sufficient size and
dose volume to maximize pump life. A pumped drain may include a check valve and
an alarm in compliance with paragraph (M) of rule
3701-29-12 of the Administrative
Code;
(5)
The receiving area for a drainage outlet shall not
pond and shall allow free flow away from the outlet during both dry and wet
weather conditions to an established drainage feature. Drainage designs may
need to consider other models for surface water drainage for the area;
and
(6)
Written permission shall be obtained from the owner,
agency, or other controlling entity for placement of a drain outlet within a
right-of-way or legally established public drainage improvement. A drain outlet
associated with a STS shall be subject to the easement provisions of paragraph
(G) of rule
3701-29-06 of the Administrative
Code.
Replaces: 3701-29-11, 3701-29-12
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