ASTM F449-02(2008)
(Practice)Standard Practice for Subsurface Installation of Corrugated Polyethylene Pipe for Agricultural Drainage or Water Table Control
Standard Practice for Subsurface Installation of Corrugated Polyethylene Pipe for Agricultural Drainage or Water Table Control
ABSTRACT
This practice covers the procedures for subsurface installation of corrugated polyethylene pipe, in accordance with the flexible conduit principles, intended for agricultural drainage or water table control. It is not however recommended for sanitary and storm sewer applications. General requirements for installation include: maximum and minimum burial depth; trench width; design of blinding, bedding, or envelope materials that are to be placed as the pipe is installed to ensure uniform continuous support; and granular or synthetic filters that are used to restrict the movement of particles into the pipe so as to maintain its hydraulic capacity. The pipe shall be aligned as smooth as possible with a curve radius larger than five times the pipe diameter while the backfill material shall be placed preferably on an angle to prevent pipe displacement or deflection. Stony trenches shall be avoided and any over-excavation or rock excavation shall be treated with proper bedding material. Factors that affect the proper handling of the pipe such as temperature; stretch caused by tension and bending forces; synthetic envelopes and filters that are subject to abrasion and tearing; and protection from fire hazards, livestock, heavy wheel traffic, and rodents or other animals shall also be considered during installation.
SCOPE
1.1 This practice is recommended for and limited to gravity flow subsurface drainage systems or water table control, but not recommended for sanitary or storm sewer applications. Procedures are outlined to minimize pipe deflection or structural damage during and after the installation process. These installation procedures are in accordance with “flexible conduit” principles.
1.2 This practice applies to all agricultural subsurface drainage or water table control installations using Specification F405, F667 or other plastic pipe.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: F449 − 02(Reapproved 2008) An American National Standard
Standard Practice for
Subsurface Installation of Corrugated Polyethylene Pipe for
Agricultural Drainage or Water Table Control
ThisstandardisissuedunderthefixeddesignationF449;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 backfill—materials used to fill the trench following
installation of the pipe and bedding.
1.1 This practice is recommended for and limited to gravity
3.3 bedding—material which provides stable bottom sup-
flow subsurface drainage systems or water table control, but
not recommended for sanitary or storm sewer applications. port for the pipe including the trench bottom groove support
angle or select material placed around the pipe, and envelope
Procedures are outlined to minimize pipe deflection or struc-
or filter materials where used during installation.
tural damage during and after the installation process. These
installation procedures are in accordance with “flexible con-
3.4 blinding—the placement of soil, bedding material over
duit” principles.
and on the sides of the pipe or envelope to ensure proper grade,
alignment, support, and protection of pipe during backfilling
1.2 This practice applies to all agricultural subsurface drain-
and after installation.
age or water table control installations using Specification
F405, F667 or other plastic pipe.
3.5 boot (also shield)— the protecting apparatus linked to
the rear of the installation machine in a manner which allows
1.3 This standard does not purport to address all of the
placement of the pipe on the trench bottom, protection of the
safety concerns, if any, associated with its use. It is the
workman, or placement of envelope or filter material, or both.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.6 cradle—a prefabricated rigid structure designed to pro-
bility of regulatory limitations prior to use.
vide trench bottom support for the pipe when soil support is
inadequate.
2. Referenced Documents
3.7 envelope—porous material placed around the pipe to
2.1 ASTM Standards:
provide bedding, improve the flow of ground water into the
D1600 Terminology forAbbreviatedTerms Relating to Plas-
drain, or function as a filter.
tics
3.8 filter—an envelope of natural or synthetic materials
D2412 Test Method for Determination of External Loading
placed completely around a drain to permit free water move-
Characteristics of Plastic Pipe by Parallel-Plate Loading
ment into the drain, provide stabilizing support at the soil-filter
F405 Specification for Corrugated Polyethylene (PE) Pipe
interface, and restrict movement of silt and sand into the drain.
and Fittings
F412 Terminology Relating to Plastic Piping Systems 3.9 grade—the slope of the pipe invert.
F667 Specification for 3 through 24 in. Corrugated Polyeth-
3.10 groove support angle— angle between the radii of the
ylene Pipe and Fittings
pipe at points of contact with the formed groove of undisturbed
soil or a cradle.
3. Terminology
3.11 mineral soils—soil containing (1) less than 30 % or-
3.1 Definitions are in accordance with Terminology F412
ganicmatterbyweightprovidedthemineralfractionis60 %or
and abbreviations are in accordance with Terminology D1600,
more clay, or (2) less than 20 % organic matter by weight
unless otherwise specified.
provided the mineral fraction has no clay, or (3) less than a
proportional content of organic matter between 20 and 30 % if
This practice is under the jurisdiction of ASTM Committee F17 on Plastic
the clay content of the mineral fraction is between 0 and 60 %.
Piping Systems and is the direct responsibility of Subcommittee F17.65 on Land
Drainage.
3.12 natural granular envelope—an envelope of granular
Current edition approved Nov. 1, 2008. Published November 2009. Originally
material, usually highly permeable well-graded sand and
ϵ1
approved in 1976. Last previous edition approved in 2002 as F449 – 02 . DOI:
gravel.
10.1520/F0449-02R08.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.13 organic soil—soil containing (1) 30 % or more organic
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
matterprovidedthemineralfractionis60 %ormoreclay,or(2
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ) 20 % or more organic matter provided the mineral fraction
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F449 − 02 (2008)
has no clay, or (3) a proportional content of organic matter
between 20 and 30 % if the clay content of mineral fraction is
between 0 and 60 %. (It is a general rule that a soil is classed
as an organic soil (histosol) either if more than one half of
upper 80 mm (32 in.) of soil is organic or if organic soil
material of any thickness rests on rock or on fragmental
material having voids filled with organic material.)
3.14 pipe stiffness—force per unit length, per unit deflection
as defined in Test Method D2412.
3.15 power feeder—mechanism that applies force to the
pipe as it passes through the boot or shield to reduce stretch
during installation.
3.16 pre-ripping—the practice of making a pass with the
plow without installing pipe to locate rocks and to reduce draft.
3.17 start hole—a trench sufficiently long and wide to allow
working room for placing the boot or shield, blade or cutting
mechanism on grade to start the trench and to install connec-
tions or pipe.
3.17.1 Discussion—Start holes are usually dug with a back-
hoe with a flat-bottom trench.
3.18 stretch—the increase in length of the pipe caused by
tension forces during installation. It is expressed as a percent
increase of the length prior to installation. Stretch differs from
FIG. 1 Terminology for Installation of Plastic Drain Pipe
elongation in that elongation is a material test and stretch is an
installation test.
3.19 synthetic envelope— an envelope made of synthetic
geotextiles, usually thin synthetic fabrics or thicker fibrous
material, or both, often selected to function as a filter.
3.20 trench depth—the depth of the trench measured from
the bottom of the pipe.
3.21 trench width—the width of the trench measured at the
top of the pipe.
3.22 Fig. 1 illustrates the terms bedding, vertical deflection,
backfill material, cover, groove support angle, horizontal de-
flection, trench width, and trench depth.
Fig. 2 illustrates various support grooves or trench bottom
shapes.
Fig. 3 illustrates envelope and filter.
Fig. 4 illustrates rodent protection devices.
Fig. 5 illustrates boot or shield.
FIG. 2 Support Grooves
4. General Requirements
4.1 Burial—The maximum and minimum burial depth are
4.1.1.2 Organic Soils—Subsurface drains should be in-
affected by the following factors, groove support angle of the
stalled in these soils only after initial subsidence has occurred.
trench bottom, bedding, blinding backfill soil density, envelope
To produce initial subsidence open ditches should be con-
density, envelope placement, pipe stiffness, the live load
structed in deep organic soils to carry off free water, and the
expected, desired water table depth, and width of trench.
area should be allowed to stand or be partially cultivated for a
4.1.1 Minimum Depth:
period of 3 to 5 years before installing pipe.The recommended
4.1.1.1 Mineral Soils—The minimum recommended cover
minimum cover for the pipe in organic soils is 0.7 m (2.5 ft).
needed to protect the pipe from crushing under live loads is 0.6
If water level controls are not provided in the drainage system
m (2 ft). Granular bedding or special construction techniques
to hold subsidence to a minimum, the depth of cover should be
may be used to reduce the cover. The time for consolidation of
increased to 0.9 m (3 ft).
backfill may be a factor (see 8.1). The minimum cover may
have limiting factors other than crushing such as clearance for
NOTE 1—These minimum depths are recommended to prevent crushing
subsoiling and utility crossing. of the pipe by normal agricultural vehicle loads. Other drainage factors
F449 − 02 (2008)
4.3.2 Synthetic Envelopes—Blinding or bedding is needed
to support and hold the envelope and pipe in place.
4.4 Filters—Are required when ground water can develop
velocities sufficient to move sand or silt, or both, into the drain.
Filters must be able to restrict the movement of these particles
into the pipe so that the hydraulic capacity of the pipe is
maintained.
4.4.1 Granular Filters—Design of a graded sand and fine
gravel filter should match the gradation of the specific soil
following criteria developed by the Natural Resource Conser-
vation Service, the U.S. Bureau of Reclamation, or the U.S.
Army Corps of Engineers.
4.4.2 Synthetic Filters—Thin synthetic fabric material or
geotextiles may be used where bedding, soil, and hydraulic
conditions permit. The openings in synthetic filters must be
compatible with the soil that surrounds the drain to prevent
excessive movement of soil that otherwise could plug the drain
or filter (see 5.3).
NOTE 2—These filters must be specified to be compatible with the soil
type that encompasses the conduit since protective filters can plug and
decrease the inflow capability. Where fiberglass filter material is used, it
shall be manufactured from borosilicate-type glass and the manufacturer
shall certify that it is suitable for underground use.The fibers should be of
variable size, with some larger fibers intertwined in the mat in a random
FIG. 3 Pipe Encased in Bedding for Support (left) and Pipe En-
manner.
cased in Sand and Gravel Envelope Designed as Filter (right)
NOTE 3—Vegetative filter material such as straw, hay, corn-cobs,
woodchips, sawdust, and coconut fiber are not recommended for use with
flexible conduits because such conduits depend on the development of
such as those encountered with salinity control in arid irrigated lands may
lateral support and these soft materials may not provide the necessary
require minimum depths of 1.8 m (6 ft).
lateral support.
4.1.2 Maximum Depth—The maximum burial depth is in-
4.5 Grade—Shall be as specified in the plan or guide.
fluenced by such factors as degree of compaction, type of
Deviations greater than the following shall not be allowed.
bedding, support from the trench bottom, trench width, size of
Vertical deviations of more than 0.1 ft (30.5 mm) in 10 ft (3.05
pipe, pipe stiffness, weight of backfill, and live loads imposed.
m). Negative grade that would fill the pipe more than 10 %.
Withoutanengineeringdesign,maximumburieddepthsshould
Due to the speed of installation with the plow, automatic grade
be limited to those listed in Table 1. For installation at depths
control is recommended. The pipe feeding system shall hold
greater than those listed in Table 1, specifications of and
thepipeinplaceinthebottomofthetrenchuntilsecuredbythe
engineering design should be followed.
bedding, blinding, or envelope material.
4.1.3 Trench Width—Increasing the trench width increases
4.6 Material Requirements—Pipe and fittings shall meet the
the soil load on the pipe. Side clearances of more than 150 mm
requirements of the applicable ASTM standards referenced in
(6 in.) on each side should only be used with an engineering
Section 2 and Table 1.
design and special construction (see Table 1). Trench width
must be at least 50 mm (2 in.) wider than the pipe on each side
for plow installation and 75 to 150 mm (3 to 6 in.) on each side 5. Significant Factors in Pipe/Soil Interactions
for open trench installation to allow sufficient bedding to
5.1 Connections—In start holes and adjacent open trenches,
support the pipe. If fine material cannot be placed alongside
the pipe shall be aligned both vertically and horizontally,
and over the pipe, a wider trench should be considered or
blinded and hand tamped along the sides of the pipe to prevent
special bedding material supplied.
excessive deflection.
4.2 Design Items—It is particularly important that blinding,
5.2 Deflection—The deflection of corrugated plastic pipe is
bedding, or envelope material be placed as the pipe is installed,
related to installation practice, bedding, groove support angle,
to ensure uniform continuous support, so that the bedding,
blinding, gradation and density of soil, depth of installation,
blinding, or envelope material can provide lateral restraint
trench width in relation to pipe size, live loads imposed,
against pipe deflection as the backfill settles on the bedding,
stretch, and pipe stiffness of pipe. Maximum pipe deflection
blinding, or envelope material.
should be specified and not exceed 10 % of its nominal
4.3 Envelopes—Must be designed to provide adequate sup-
diameter.
port for the pipe, improve the flow of ground water into the
5.3 Filters—Synthetic materials should never be used when
pipe, and in some installations, filter flow into the pipe.
the soil has a silt content greater than 40 %.
4.3.1 Natural Granular Envelopes—Minimum thickness of
75 mm (3 in.) around the pipe. 5.4 Trench Depth—See 4.1.
F449 − 02 (2008)
FIG. 4 Suggested Methods of Providing Rodent Protection for Outlet Pipes
5.5 Trench Width—The width of the trench or blade below a hot day back-filling should be delayed until pipe temperature
the top of the pipe should be adequate to allow placing pipe, cools to the soil temperature (see 8.1).
reducers,andconnectorsinthebottomofthetrenchandshould
6.3 Bedding—Necessary for the support and protection of
conform to 4.1.3.
the pipe. If adequate support is not provided by the soil and
trench bottom shape as shown in Fig. 2, envelopes or special
6. Construction
construction should be used.
6.1 Alignment—Should be as smooth as possible with a
6.4 Blinding—Material used for this process should not
curve radius larger than five times the pipe diameter.
contain any hard object larger than 38 mm (1 ⁄2 in.) in diameter
6.2 Backfilling—Place the backfill material so that displace-
andshouldcoverthepipetoadepthof150mm(6in.).SeeFig.
ment or deflection of the pipe will not occur. This is preferably
5 for possible boot and shield configuration.
on an angle, so the material flows down the front slope.Avoid
large stones, frozen material, and dry clods that cause concen- 6.5 Bottom Shape—The bottom should be one of the shapes
trated direct loads on the pipe. The trench should be backfilled shown in Fig. 2. The 90° “V” bottom of Fig. 2 works well on
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