SECTION 5.

TILE DRAIN INSTALLATION AND REPAIR

Overview

Practice 201 Tile Drain Installation

Practice 202 Tile Drain Repair/Replacement

Practice 203 Breather Pipe

Practice 204 Tile Drain Inlet

 SECTION 5.2
TILE DRAIN INSTALLATION AND REPAIR

Headwater areas for many of the streams and ditches in Indiana are in the form of closed tile
drains. The upper portion of these drains is usually located within agricultural fields where water
is collected through the use of perforated drains installed below the ground surface. This section
concentrates on these types of drains. It should be noted that in general, these systems are
installed and maintained by private landowners. These systems then discharge water to a
regulated drain which may either be a larger tile or an open drain.

Stream enclosures, in the form of a long culvert or an unperforated tile drain, are often used in
the headwater areas to convey drainage water without disruption to the above-ground land use.
Principles provided in this section, as well as those presented in Practice 901, should be
consulted when such usage of tile drains is being considered.

Subsurface tile drains consist of a conduit installed beneath the ground surface to collect and/or
convey drainage water. Tiles may be constructed of corrugated plastic tubing, clay, or concrete.
The choice of tile material depends on the cost, resiliency, strength, and conveyance.

Subsurface drains are often installed in agricultural fields employing one of four systems of layout:
parallel, herringbone, double main, or random (Exhibit 201b). The type of system used depends
on site topography, land drainage patterns, and other factors. A double main, for example,
intercepts runoff on either side of a stream. A random system is useful for draining irregularly
dispersed wet pockets in the landscape.

Breather pipes, or pressure relief vents, are recommended where the drain grade changes from
steep to flat. The purpose of breather pipes is to allow air entry, and to relieve pressure that
otherwise may cause blowouts. Breather pipes may also be replaced or modified as slotted risers
which serve as inlets for areas prone to surface ponding.

Installation of surface inlets to tile systems can help remove surface water more quickly.
However, surface inlets can also provide a direct conduit to receiving streams for herbicides,
pesticides, and other chemicals used in agricultural fields. Buffer strips of permanent grass
around inlets should be considered to reduce impact of pollutants.

Subsurface drains that are properly installed require little maintenance to keep operational.
However, periodic inspections will help keep drains operating at capacity. Particular attention
should be paid to outlets, water-surface inlets, traps and catch basins, and tiles located near
trees. To reduce the chance of damage by various activities along roads, markers may be used
to signal the location of tile crossings.

Tiles, by their nature, can dramatically alter the hydrology of areas where they are located, as well
as the hydrology of adjacent properties. Care should be taken that tiles do not negatively impact
valuable wildlife habitat (especially for wetland and stream dependent species), or cause
detrimental water level impacts to adjacent property owners. Non-perforated or sealed joint tile
should be used in these areas.

Last Print/Revision Date: October 13, 1996

5.2-1
 PRACTICE 201
TILE DRAIN INSTALLATION

DESCRIPTION ! A conduit, such as corrugated plastic tubing, clay tile, or pipe,

installed beneath the ground surface to collect and/or convey
drainage water in headwater areas.

Exhibit 201a: Tile Drain Installation (Source: NRCS Files)

PURPOSE ! Convey watershed's headwater flow with minimal disruption to

agricultural fields.
! Improve soil environment for vegetation growth.
! Collect ground water.
! Remove water from heavy use areas.
! Regulate water to control hydrophytic pests such as liver flukes, flies,
or mosquitos.
WHERE ! Areas with a high water table where the benefits of lowering
APPLICABLE the table would justify installing such a system.
ADVANTAGES ! Relieves artesian pressures.
! Removes surface runoff.
! May enhance crop growing potential.
CONSTRAINTS ! May be relatively expensive to install.
! May drain valuable wetland habitat.
! May negatively affect water levels of adjacent land owners.
! May transport contaminants.
! May outfall into valuable stream habitat that may be negatively
impacted by potentially cool, subsurface water.
DESIGN AND Materials
CONSTRUCTION ! Clay, concrete, or perforated and non-perforated plastic tubing.
GUIDELINES ! Conduit should meet strength and durability requirements of the site.
! Filter material, if necessary.

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 Installation
! Begin digging the trench at the outlet end continue upgrade.
! Trench width should at least equal the outside diameter of the drain,
up to 0.5' wider than the drain.
! Round the bottom of the trench so that the drain will be embedded
in undisturbed soil for the last 60 degrees of its circumference.
! For corrugated plastic tubing, installation criteria are listed in ASTM
Standard F449: "Recommended Practice for Subsurface Installation
of Corrugated Thermoplastic Tubing for Agricultural Drainage or
Water Table Control".
! Laying of the tile should begin at the lower end of the line and
progress up-grade.
! Backfill in a manner that will not displace the conduit.

Exhibit 201b: Types of drainage collection systems (Source: NRCS

National Engineering Handbook)

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Special Considerations
! When the tile drain path is adjacent to or through a wetland area that
is designated to be preserved, sealed or non-perforated tile/tubing
must be used with sufficient distance before and after the limits of
the wetland to protect it against being drained.
! Drainage easements should be considered when installing mutual
drains. These easements should be recorded with the county
recorder's offices.

Capacity - Determine by one or more of the following:

! Application of drainage coefficients as recommended by the NRCS
Indiana Drainage Guide or NRCS Chapter 14, Part II of the
Engineering Field Manual, to the area drained, including added
capacity required to dispose of surface water entering through
surface inlets.
! Comparison of the site with other similar sites where subsurface
drain yields have been measured.
! yield of ground water based on the expected deep percolation of
irrigated water from the overlying fields, including the leaching
requirement.
! Measurement of the rate of subsurface flow at the site during a
period of adverse weather and ground water conditions.
! Calculations using Darcy's law or estimation of lateral or artesian
subsurface flow.

Size
! Compute by applying Manning's formula.
! Drain tiles should be designed in such a way that pressure flow does
not occur in the tile.
Depth, Spacing, and Location
! Should be based on site conditions such as soils, topography,
ground water conditions, crops, land use, and outlets.
! Minimum depth should be 2' in mineral soils and 2.5' in organic soils.
! Calculate equipment loads when the depth is less than 6'.

Velocity and Grade

! In areas where sedimentation is not a hazard, the minimum grades
shall be based on site conditions and a velocity of at least 0.5' per
second.

Soil Texture Velocity (ft/s)

Sand and sandy loam 3.5
Silt and silt loam 5.0
Silty clay loam 6.0
Clay and clay loam 7.0
Coarse sand or gravel 9.0
Exhibit 201c: Maximum Velocity by Soil Texture

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 ! Filters and filter material, and envelopes and envelope material may
be necessary depending on site conditions.
MAINTENANCE ! Keep inlets, trash guards, collection boxes, and structures clean and
free of materials that can reduce the flow.
! Repair all broken or crushed lines to insure proper functioning of the
drain.
! Repair or replace broken or damaged inlets and breathers damaged
by livestock and machinery.
! Periodically inspect outlet conduit and animal guards for proper
functioning.
REFERENCES Related Practices
! Practice 202 Tile Drain Repair/Replacement.
! Practice 203 Breather Pipe.
! Practice 204 Tile Drain Inlet.
! Practice 1001 Tile Drain Outlet Extension.

Other Sources of Information

! NRCS Engineering Field Handbook.
! Illinois Urban Manual.
! ASTM Standard F449.
! Davis' Handbook.
! North Carolina Erosion Control Manual.
Last Print/Revision Date: October 13, 1996

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 PRACTICE 202
TILE DRAIN REPAIR/REPLACEMENT

DESCRIPTION ! Maintenance, repair, and replacement of tile drains.

Exhibit 202a: Tile Drain Repair/Replacement (Source: NRCS Files)

PURPOSE ! To reestablish drain function by restoring tile segment.

WHERE ! All subsurface drains.
APPLICABLE
ADVANTAGES ! Regular repairs and maintenance help avoid future costly repairs
and damages.
CONSTRAINTS ! All drains should be maintained.
DESIGN AND Materials
CONSTRUCTION ! Varies with project.
GUIDELINES ! Properly-sized segments should match hydraulic capacity of
adjoining pipes (upstream and downstream).
Installation
! Outlets should be kept free of debris. They should be protected from
animals by a flap gate or a grating.
! Water surface inlets may require frequent repairs. Erosion around
inlets should be repaired, and the inlet grating should be kept free of
debris.
! Traps must be kept clean in order to maintain drainage capabilities.
Cleanout of the trap may be less frequent as the drain ages.
! Blowouts occur when the tile is subjected to pressure flow. When
the tile is subjected to pressure flow, water is forced out of the tile
saturating the surrounding soil. As the flow drops, the saturated soil
is sucked into the tile. To correct, replace with solid tile or correct
the pressure flow problem.

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 ! Tree roots may plug drains. To repair the line, dig it up, clean it, and
re-lay it. Please note that this is only a temporary measure that may
have to be repeated periodically. One way to prevent recurrence,
short of killing the trees, would be to replace the part of the drain
near the trees with sewer pipe.
! Drains laid under waterways may carry soil and cause holes. Drains
under waterways should be inspected regularly, and the holes
repaired as necessary.
! Mineral deposits can sometimes plug the perforations in drains.
Indication of the presence of deposits may be seen at the outlets or
at junction boxes and inspection holes. Sulphur dioxide gas injected
into the upper end of the drain from tanks of compressed gas can
open the drain. The gas should be held in the line for 24 hours after
the air has been replaced by gas. High pressure hydraulic cleaners
are also used.

Special Considerations
! Failure of drains to operate as expected may result from a variety of
reasons including: insufficient capacity, drains placed too shallow,
lack of auxiliary structures, insufficient drain strength, improper
spacing between joints, improper bedding, poor grade and
alignment, improper backfilling, and substandard materials.
! Drainage easements should be considered when installing or
repairing mutual drains. These easements should be recorded at
the County Recorder's Offices.
MAINTENANCE ! Periodically inspect the required area for signs of blowout at the
repair site or adjacent to it.
REFERENCES Related Practices
! Practice 201 Tile Drain Installation.
! Practice 203 Breather Pipe.
! Practice 204 Tile Drain Inlet.

Other Sources of Information

! NRCS Engineering Field Handbook.
Last Print/Revision Date: October 13, 1996

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 PRACTICE 203
BREATHER PIPE (Pressure Relief Vent)

DESCRIPTION ! Vertical vents that relieve air pressure in subsurface drains.

Exhibit 203a: Breather Pipe (Source:

NRCS Files)

PURPOSE ! Relieve pressure in the line.

! Provide air entry into the line.
WHERE ! Where the drain grade changes from steep to flat.
APPLICABLE ! Where future inspection may be needed.
ADVANTAGES ! Relieves pressure that might otherwise cause blowouts.
! Provides air entry to a drain for the purposes of venting a line.
! Allows access for inspection and cleanout.
! May also act as a marker.
CONSTRAINTS ! Additional expense.
! May be minor obstacle to farm machinery when installed in
agricultural fields.
DESIGN AND Materials
CONSTRUCTION ! Riser Pipe.
GUIDELINES ! Screen or perforated cap.
! T-joint, or other appropriate joint.

5.203-1
 Installation
! Place T-connection in line and cement riser pipe to the joint.
! Riser pipe should extend at least 3' above the ground.
! Cover the opening with a perforated cap, or heavy wire mesh.

Exhibit 203b: Installation of breather pipe (Source: NRCS Files)

Special Considerations
! Vents should be located at points where the drain grade changes
from a steep grade to a flat grade (where the difference in grade
exceeds 0.5% or at key locations where future inspections are to
occur).
MAINTENANCE ! Keep breathers free of debris.
REFERENCES Related Practices
! Practice 201 Tile Drain Installation.
! Practice 204 Tile Drain Inlet.
! Practice 202 Tile Drain Repair/Replacement.
! Practice 1001 Tile Drain Outlet Extension.

Other Sources of Information

! NRCS Engineering Field Handbook.
Last Print/Revision Date: October 13, 1996

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 PRACTICE 204
TILE DRAIN INLET

DESCRIPTION ! Vertical riser with round holes or slots to provide an inlet for surface
water.

Exhibit 204a: Typical Tile Drain Inlet (Source: NRCS

Files)

PURPOSE ! Provide a direct inlet for surface water in a field.

! May also provide air entry into the line or relieve pressure in the line.
WHERE ! Areas prone to surface ponding.
APPLICABLE
ADVANTAGES ! Reduces surface ponding.
! Also acts as a breather pipe when no ponding is occurring next to
the riser.
! Allows access for inspection and clean-out.
! Also acts as a marker for underground drain location.

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CONSTRAINTS ! Additional expense.
! May be minor obstacle to farm machinery when installed in
agricultural fields.
! Surface inlets can provide a direct conduit to receiving streams for
herbicides, pesticides, and other chemicals used in agricultural
fields.
DESIGN AND Materials
CONSTRUCTION ! Riser pipe made of aluminum, iron, P.V.C., smooth polyethylene,
GUIDELINES or steel. (Prefabricated slotted/round-hole intakes may also be
available)
! Trash guard or prefabricated perforated cap.
! T-joint, or other appropriate joint.

Installation
! Place T-connection in line and cement riser pipe to the joint.
! Riser pipe should extend at least 3' above the ground.
! The conduit trench from the toe of the backslope to the riser, must
be excavated with 1:1 (1V:1H) side slopes and backfield with
compacted fill. The backfill around the riser shall be hand tamped.
! Follow installation details shown in Exhibit 204b.

Exhibit 204b: Typical Tile Drain Inlet Installation Details (Source: NRCS Files)

! To make a Slotted Intake, cut ¾" by 4" slots in four (4) rows around
the pipe (90 degree spacing). Do not space closer than 2" to the
seams or end of pipe. (See Exhibit 204c for details). Slotted intake
capacity is about 20 acre-inches per day.

! To make a Round-Hole Intake, Fabricate 24 holes per linear foot, ¾"

diameter. Alternate fabrication approximately 12 inches per foot of
1" diameter. (See Exhibit 204c for details). Round-Hole intake
capacity is about 8 acre-inches per day.

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 Exhibit 204c: Typical Tile Drain Riser Intake Details (Source:
NRCS Files)

! Trash Guard: Top of the riser must be protected by a standard trash

guard (Exhibit 204d). Prefabricated trash guards/caps may also be
used.

Exhibit 204d: Typical Trash Guard Details

(Source: NRCS Files)

Special Considerations
! To protect the water quality and prevent chemicals used in the
agricultural farms to get into the intake, a permanent grass buffer
zone around the riser must be provided. The size of the buffer
depends on the intake size and topography with a minimum
diameter of 30 feet.
MAINTENANCE ! Inspect frequently, especially after each storm to insure that the
intake remains in working conditions..
REFERENCES Related Practices
! Practice 201 Tile Drain Installation.
! Practice 202 Tile Drain Repair/Replacement.
! Practice 203 Breather Pipe.
! Practice 1001 Tile Drain Outlet Protection.

Other Sources of Information

! NRCS Engineering Field Handbook.
Last Print/Revision Date: October 13, 1996

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