Historic note
 Front Cover

Group Title: Circular - University of Florida Institute of Food and Agricultural Sciences ; 661
Title: A guide for plastic tile drainage in Florida citrus groves
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067076/00001
 Material Information
Title: A guide for plastic tile drainage in Florida citrus groves
Series Title: Circular Florida Cooperative Extension Service
Physical Description: 8 p. : ; 23 cm.
Language: English
Creator: Ford, Harry W., 1922-
Belville, Bishop Carlton, 1924-
Carlisle, V.W ( Victor Walter ), 1922-
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville
Publication Date: 1985
Subject: Drain-tiles   ( lcsh )
Drainage -- Florida   ( lcsh )
Citrus -- Irrigation -- Florida   ( lcsh )
Citrus fruits -- Soils -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: Harry W. Ford, Bishop C. Beville and Victor W. Carlisle.
General Note: Cover title.
General Note: "June 1985."
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00067076
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 15172375

Table of Contents
    Historic note
        Historic note
    Front Cover
        Front cover
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
Full Text


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

June 1985 Circular 661

Scuilde for plastic
Tile rainage in
Harry W. Ford, Bishop C. Beville and Victor W. Carlisle
Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
John T. Woeste, Dean for Extension

A Guide for Plastic Tile Drainage
in Florida Citrus Groves
Harry W. Ford, Bishop C. Beville, and Victor W. Carlisle*


Grove sites subject to periodic or frequent high water table conditions
are potential candidates for drainage. Drainage can increase tree size,
longevity, yields, and reduce irrigation requirements. Adequate drainage
involves both surface and subsurface (commonly called profile drainage).
It is most important that surface drainage should be designed to remove
at least 50% of the rainfall through the use of shallow surface bedding,
swales, or other techniques, unless there is a minimum of 0.5% (6 inches
per 100 ft) natural slope to the land. Surface infiltration from excessive
rainfall can contribute to drain failures and high water tables. To prevent
erosion, which can be severe in Florida sands, all surface waters should
enter ditches via spillways or drop pipes.
Profile drainage maintained throughout the life of the tree is necessary
to prevent serious root injury and tree damage from perched groundwater
levels. Profile drainage requires the use of buried plastic pipes or open
field ditches. Very high beds (greater than 24 inches) restrict lateral root
growth and complicate grove operations. The beds eventually serve as a
combination surface and shallow profile drainage system.
There is an important relationship between drain depth and spacing.
Restrictions in the profile such as clay subhorizons or spodic (brown san-
dy organic) layers as well as the natural hydraulic conductivity of the soil
must be considered. A common false assumption in providing profile
drainage is that an open ditch is more efficient than a drain line. A plastic
drain line with low entry resistance and a ditch where the bottom is in-
stalled to the same depth and spacing have equal 24-hour drawdown rates
and flow nets. In other words, the groundwater will not flow faster into
the open ditch. The ditch has more flow depth carrying capacity and can
usually be dug deeper which may increase spacing. Past experience has
shown that most ditches are poorly maintained. Erosion may cause the
ditches to become several feet shallower than required for the original depth
and spacing design. The net result could be a grove site with inadequate
profile drainage. Ditches, if spaced correctly according to soil type, re-
quire a considerable amount of land that could be used for the growing
of citrus trees.

*Professor, Citrus Research and Education Center, IFAS, University of Florida
- Lake Alfred, Florida; Professional Drainage Engineer, Gainesville, Florida;
Professor, Soil Science Department, IFAS, University of Florida, Gainesville,

Corrugated plastic tubing is now installed with chain machines (tren-
chers) or trenchless plows using lasers for critical grade control. The wheel
machine is still in use and has been adapted to the laser. Outlets of solid
PVC pipe extend directly into open ditches. In some designs the laterals
empty into buried mains of larger pipe sizes. Most poorly drained soils
used for citrus are unstable sands which will flow into the drain unless
an envelope (filter) surrounds the drain. A variable grade gravel would
be preferred but it is no longer cost effective and most contractors are
not equipped to install gravel pack envelopes in agricultural drainage situa-
tions. The new envelopes are thin synthetic wraps installed at the factory.
They fall into two main categories: the spun bonded fibers such as nylon,
polypropylene, and polyethylene; and woven stretchable materials such
as the polyester sock. Wrapped tubing is transported to the site in large
rolls and may be laid out on the ground or installed from spindles mounted
on the trenching machine. Installation can be quite rapid with the equip-
ment employed today.

An Introduction to Subsurface
Drainage Design

Soils that are satisfactory for citrus in Florida but need profile subsur-
face drainage are listed in Table 1. The order classification of each soil
indicates the general characteristics of the profile. The Series names are
often being changed and updated with additional names. A list of former
names has been included. A general description of the soils together with
recent soil surveys can be obtained from your local Soil Conservation Ser-
vice District Office. Characteristics of soil profiles have pronounced ef-
fects on depth and spacing of drains. The installation trench depth and
drain spacing data in Table 1 were calculated for each soil using formulas
accepted by drainage engineers for gravel envelopes and then corrected
for the use of synthetic drain envelopes and ochre clogging potentials. It
is common to find several different soil types in the same field so that
adjustments in drain spacing may be necessary. The depth and spacing
information are for 4-inch diameter tubing although larger sizes are
available. There is also a column in Table 1 to aid in changing depth and
spacing between the minimum and the maximum values presented.
The depth-spacing data are based on a drainage removal coefficient of
3/4 inches of water passing through the profile each 24 hours and should
result in a water table drawdown of 6 inches per day. Approximately one
inch of rainfall entering the soil can raise the water table as much as one
foot. The minimum depth in Table 1 is based on research for a good
rooting volume for the trees located midway between drain lines. If
drawdown is 6 inches per day, the trees located midway between drains
should be able to tolerate extended temporary high water tables without

significant root injury. It is economically not feasible to design a drainage
system that will completely prevent flooding and water table rise under
severe weather conditions.
Trenching depth corrected for 4-inch diameter tubing is shown with the
assumption that the drain line will be placed on the bottom of the trench.
It is possible to place drains at shallower depths than the minimums shown
(which is often done for vegetable and ornamental fields) but the spacing
adjustment values may be somewhat in error and the rooting volume may
be restricted. The drains should have a minimum of 24 inches of cover
to prevent collapse from traffic and heavy equipment.
The drain clogging potential for iron deposits (ochre) were determined
by laboratory evaluation of soil samples and are discussed in more detail
under "ochre clogging problems".
Outfall from the grove site is a first priority. Sufficient engineering
surveys must be conducted to determine the existence of a natural water
outlet from the grove site before considering a drainage system. Is there
sufficient elevation and canal capacity to remove the water during flood
stage? Permits will be required by Water Management Districts before
large quantities of water can be removed rapidly from poorly drained
wetlands.* The drainage system will be of little value if everything is under
water for long periods of time. A sump-and-lift-pump type outlet may
be necessary for subsurface drainage which could materially increase
drainage costs.
Natural slope of the site or slopes constructed by grading (less than 6
inches per 100 ft) will establish whether shallow bedding may be required
for surface water removal as well as the length of drains that can be used.
Maximum length for 4-inch diameter tubing should not exceed 1200 ft.
On flat land where an installation grade of 2 1/2 inches per 100 ft is
employed, unless there are drain outlets on both ends and the high point
is in the middle, the length of the drain should not be greater than 500
ft. The 500 ft of drain will change depth by 11 inches and, as noted in
Table 1, will seriously affect spacing. Longer lines up to 1000 ft may be
used with flat grades but a slight error during installation or shifting in
the trench bottom could result in a condition known as reverse grade con-
tributing to physical and biological clogging within the drain.
Slopes greater than 2% may require the use of interceptor drains runn-
ing across the slope to intercept underground seepage. Some fields have

*Drainage outfalls/outlets discharging into state waters are considered point source
discharges by local and state pollution control authorities, and approval to outlet
into such waters should be obtained during the planning stage of a drainage or
water management system. Such a system usually requires some type of water
quality monitoring of the discharge water for a few months until the system shows
no degradation of state waters.

knolls and ridges and it is important that they not be used as the points
of reference for establishing depths of drain lines. The reverse grade pro-
blem can also be a problem when installing a drain through a knoll.

Examples of Drain Spacing and Depth

First, know the basic soil type and then the tree spacing so that the drain
trench will fall between rows and also in the middles of double beds rather
than in furrows or swales. Use Table 1 to determine trench depths, being
certain that collector ditches and outfalls will permit the use of the selected
CLOSER THE SPACING. The following assumptions and calculations
for Adamsville fine sand will serve as an illustration. In Table 1 the
mininium spacing for Adamsville is listed as 71 ft and the increment of
spacing that is equivalent to lowering the trench depth one inch is 6 ft.
For this example, you selected a spacing of 100 ft based on bedding and
25 ft tree rows. The selected spacing is 29 ft wider than the minimum of
71 ft. Divide 29 ft by 6 ft. The trench would have to be lowered 5 inches
making the trench depth 51 inches. The trench depth figure should be ap-
plied closer to the upper end rather than near the drain outlet. It is better
to be too deep than too shallow. Clay subhorizons could limit effective
depth and drains placed directly in spodic horizons increase the risk of
increased hydraulic entry resistance and biological clogging potential.

The Ochre Clogging Problem

Ochre deposits in drain lines can be a serious issue for certain soil types
in Florida. It is important to understand the problem and make ad-
justments in design and maintenance. Table 1 can be used as a guide. Ochre
is formed as a combination of bacterial slimes, organic materials, and ox-
idized iron. Ochre is a highly visible, red, gelatinous, iron sludge. It is
often found in the valleys of the corrugations of the tubing rather than
at the drain outlet. The amounts of iron in groundwater that can stimulate
bacteria to produce ochre can be as low as 0.2 ppm. There are laboratory
and field methods available to estimate the potential for a given site. Ex-
perienced personnel are required for interpretation of the measurements
because of the many complex factors that can contribute to the problem.
Of particular importance is whether ochre may be permanent or temporary.
Temporary ochre occurs rapidly and usually during the first few months
after drain installation. If the drains can be cleaned or maintained in func-
tional order, the ochre problem may gradually disappear as the iron con-
tent flowing to the drains is reduced. Such soil environments must be low
in residual organic energy sources to prevent the continual release of iron
during short-term flooding. Permanent ochre problems have been found

Table 1. Soils that need subsurface drainage for citrus plantings in Florida
Four inch dia tube plus Increasing depth
synthetic envelope by one inch Potential
Min. trench Max. trench changes spacing for ochre
Order Series Former names Depth-Spacing Depth-Spacing as listed formation

inches ft. inches ft. ft.
Entisol Adamsville Adamsville 46 71 58 149 6 slight
Ultisol Blichton Blichton 40 53 52 99 4 severe"
Alfisol Bradenton Bradenton 40 40 52 79 3 slight
Entisol Broward Broward 28 57 34 90 5 slight
Spodosol Charlotte Charlotte 46 71 58 149 6 moderate
Spodosol Delks Leon 40 56 52 102 4 moderate
Mollisol Delray Delray 46 71 58 149 6 slight
Spodosol EauGallie Leon 46 60 58 130 6 severe
Spodosol Elred Charlotte 46 54 58 112 5 moderate
Spodosol Farmton Immokalee 46 63 58 115 4 severe'
Alfisol Felda Felda, Sunniland 46 61 58 133 6 slight
Mollisol Floridana Manatee 46 60 58 108 4 severe"
Inceptisol Ft. Drum Keri 46 60 58 125 5 slight
Alfisol Hilolo Parkwood 46 32 58 64 3 severe-
Alfisol Holopaw Pompano 46 71 58 146 6 moderate
Spodosol Immokalee Immokalee 46 67 58 116 4 severe
Ultisol Jumper Blanton (shallow) 46 55 58 101 4 slight
Ultisol Kanapaha Kanapaha 46 71 58 112 3 moderate
Spodosol Lawnwood Leon 46 43 58 78 3 severea
Ultisol Lochloosa Kanapaha (shallow) 46 56 58 104 4 slight

Table 1. continued
Four inch dia tube plus Increasing depth
synthetic envelope by one inch Potential
Min. trench Max. trench changes spacing for ochre
Order Series Former names Depth-Spacing Depth-Spacing as listed formation
Alfisol Malabar Pompano 46 101 58 162 5 severe'
Alfisol Micanopy Zuber 40 45 52 80 3 severe'
Spodosol Myakka Leon 46 56 58 120 5 severe
Spodosol Narcoosee Leon 46 69 58 134 5 severe
Spodosol Nettles Immokalee 46 66 58 125 5 severe'
Ultisol Nobleton Lynchburg 40 61 52 124 5 slight
Spodosol Oldsmar Immokalee 46 85 58 142 5 severe
Spodosol Ona Ona 46 85 58 142 5 severe'
Alfisol Parkwood Parkwood 46 98 58 169 6 slight
Spodosol Pendarvis Pomello 46 67 58 112 4 severea
Spodosol Pepper Immokalee 46 67 58 112 4 severea
Alfisol Pineda Charlotte, Elred 46 89 58 117 2 moderate
Alfisol Pinellas Keri 46 108 58 178 6 slight
Inceptisol Placid Rutlege 46 108 58 178 6 moderate
Entisol Pompano Arzell, Plummer, 46 71 58 147 6 slight
Alfisol Riviera Felda 46 86 58 129 4 slight
Entisol Seffner Scranton 46 72 58 126 4 moderate
Ultisol Sparr Arredondo, 46 71 58 146 6 slight
Spodosol St. Johns St. Johns 46 74 58 125 4 severea

Table 1. continued
Four inch dia tube plus Increasing depth
synthetic envelope by one inch Potential
Min. trench Max. trench changes spacing for ochre
Order Series Former names Depth-Spacing Depth-Spacing as listed formation
Spodosol Susanna Leon 46 73 58 110 3 severe
Spodosol Tantile Leon 46 86 58 131 4 severe"
Alfisol Tuscawilla Bradenton 46 56 58 112 5 severe"
Entisol Valkaria Charlotte 46 71 58 145 6 moderate
Spodosol Vero Leon 46 68 58 102 3 severe
Spodosol Wabasso Leon 46 70 58 115 4 severea
Ultisol Wacahoota Blichton 46 91 58 121 2 severe
Spodosol Wauchula Leon 46 85 58 128 4 severe"
Spodosol Waveland Immokalee 46 56 58 86 2 severe'
Alfisol Winder Felda 46 54 58 99 4 slight
-Drainage design is critical. Knitted polyester sock the preferred synthetic envelope.
Alfisols Low in organic matter; high in exchangeable bases; clay subhorizon; alkaline pH.
Entisols No distinct horizon development.
Inceptisols -Weak horizon development.
Mollisols Thick dark surface; high base saturation in subhorizons.
Spodosols Distinct organic stain layer in subhorizon; variable iron content; acidic pH.
Ultisols A clay subhorizon present; profile low in exchangeable bases; acidic pH.

in profiles with extensive residual iron such as cemented iron subhorizons
or rocks and from iron flowing in from surrounding areas. A knowledge
of terrain features is necessary to make the interpretation. Drains should
not be installed in sites having permanent ochre potential without some
means of maintenance for frequent jet cleaning. Drains in ochre prone
areas should outlet directly into ditches and should have a means to per-
mit dumping large quantities of water into the upper ends as a flushing
procedure. Jet cleaning under high water pressure is the only environmen-
tally safe method to clean drain lines. Cleaning the drains will prevent
a temporary ochre problem from becoming a permanent ochre problem.
Installation of drains particularly in ochreous areas should, if possible,
be during the dry season when the water table is low. The iron will be
in the insoluble form and stabilization of the drain and surrounding soil
will help to minimize ochre becoming a serious problem.
Subsurface Irrigation Systems

There has been considerable interest in using the drainage system for
subsurface irrigation. One important criterion applies to subirrigation.
There should be a somewhat impervious subhorizon present and within
48 inches of the surface to prevent water from going out of the 'bottom'
while an attempt is being made to raise the water table.
Based on research in Hendry County, spacing of drains in sandy pro-
files with an impervious subhorizon should be reduced to 50 5 ft. Lateral
movement of water from the drain line was rapid. Upward movement,
being against gravity, involved a moist capillary fringe of 7 to 15 inches
after three weekly irrigation cycles. The fringe zone was not permitted
to dry out between irrigation cycles. There was also a slight moist zone
of about 6 inches just above the moist capillary fringe, but it was not deter-
mined whether this moisture was available to the tree. The top 6 to 10
inches remained dry and did not become wet during 48 to 72 hour irriga-
tion cycles. It was concluded that roots should be present to a depth of
18 inches and that the water table should be raised as high as physically
possible. Water table observation wells were helpful in detecting lateral
water movement and an open faced auger such as the 2-1/2 inch diameter
"Dutch" Edelman type soil auger was an effective instrument for detec-
ting the capillary fringe and depth of rooting.
If ditch water is used to raise the water table, then the drains may be
subjected to a high organic load from yellow-colored organic and algal
filaments containing iron. Such deposits could enhance slime growths but,
at present, there are no data on the subject for subirrigation in citrus


No drainage system, whether ditches or underdrains, is maintenance
must be kept open, outlets must be checked, and erosion must be cor-
rected. Following a survey in 1979, it was estimated that 95% of drainage
systems were not being maintained properly so that the efficiency of the
systems diminished from good to poor. Maintenance should be part of
the cost of a drainage system.

This publication was promulgated at a cost of $874.33, or 18.4 cents
per copy, to provide information about plastic tile drainage in Florida
citrus groves. 07-4700-85

K. R. Tefertiller, director, In cooperation with the United States IFAB
Department of Agriculture, publishes this Information to further the
purpose of the May 8 and June 30, 1914 Acts of Congress; and is
authorized to provide research, educational information and other
services only to individuals and institutions that function without regard to race, color,
sex or national origin. Single copies of Extension publications (excluding 4 -H and Youth
publications) are available free to Florida residents from County Extension Offices.
Information on bulk rates or copies for out-of-state purchasers Is available from C. M.
Hlnton, Publications Distribution Center, IFAS Building 664, University of Florida,
Gainesville, Florida 32611. Before publicizing this publication, editors should contact
this address to determine availability.

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