1、Designation: F449 02 (Reapproved 2014) An American National StandardStandard Practice forSubsurface Installation of Corrugated Polyethylene Pipe forAgricultural Drainage or Water Table Control1This standard is issued under the fixed designation F449; the number immediately following the designation
2、indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is recommended for and l
3、imited to gravityflow subsurface drainage systems or water table control, butnot recommended for sanitary or storm sewer applications.Procedures are outlined to minimize pipe deflection or struc-tural damage during and after the installation process. Theseinstallation procedures are in accordance wi
4、th “flexible con-duit” principles.1.2 This practice applies to all agricultural subsurface drain-age or water table control installations using SpecificationF405, F667 or other plastic pipe.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are m
5、athematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and
6、 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2412 Test Method for Determination of External LoadingCharacteristics of Plastic Pipe by Parallel-Plate Lo
7、adingF405 Specification for Corrugated Polyethylene (PE) Pipeand FittingsF412 Terminology Relating to Plastic Piping SystemsF667 Specification for 3 through 24 in. Corrugated Polyeth-ylene Pipe and Fittings3. Terminology3.1 Definitions are in accordance with Terminology F412and abbreviations are in
8、accordance with Terminology D1600,unless otherwise specified.3.2 backfillmaterials used to fill the trench followinginstallation of the pipe and bedding.3.3 beddingmaterial which provides stable bottom sup-port for the pipe including the trench bottom groove supportangle or select material placed ar
9、ound the pipe, and envelopeor filter materials where used during installation.3.4 blindingthe placement of soil, bedding material overand on the sides of the pipe or envelope to ensure proper grade,alignment, support, and protection of pipe during backfillingand after installation.3.5 boot (also shi
10、eld)the protecting apparatus linked tothe rear of the installation machine in a manner which allowsplacement of the pipe on the trench bottom, protection of theworkman, or placement of envelope or filter material, or both.3.6 cradlea prefabricated rigid structure designed to pro-vide trench bottom s
11、upport for the pipe when soil support isinadequate.3.7 envelopeporous material placed around the pipe toprovide bedding, improve the flow of ground water into thedrain, or function as a filter.3.8 filteran envelope of natural or synthetic materialsplaced completely around a drain to permit free wate
12、r move-ment into the drain, provide stabilizing support at the soil-filterinterface, and restrict movement of silt and sand into the drain.3.9 gradethe slope of the pipe invert.3.10 groove support angleangle between the radii of thepipe at points of contact with the formed groove of undisturbedsoil
13、or a cradle.3.11 mineral soilssoil containing (1) less than 30 % or-ganic matter by weight provided the mineral fraction is 60 % ormore clay, or (2) less than 20 % organic matter by weightprovided the mineral fraction has no clay, or (3) less than aproportional content of organic matter between 20 a
14、nd 30 % ifthe clay content of the mineral fraction is between 0 and 60 %.1This practice is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.65 on LandDrainage.Current edition approved March 1, 2014. Published September 2014. O
15、riginallyapproved in 1976. Last previous edition approved in 2008 as F449 02(2008). DOI:10.1520/F0449-02R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan
16、dards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.12 natural granular envelopean envelope of granularmaterial, usually highly permeable well-graded sand andgravel.3.13 organic soilsoil co
17、ntaining (1) 30 % or more organicmatter provided the mineral fraction is 60 % or more clay, or (2) 20 % or more organic matter provided the mineral fractionhas no clay, or (3) a proportional content of organic matterbetween 20 and 30 % if the clay content of mineral fraction isbetween 0 and 60 %. (I
18、t is a general rule that a soil is classedas an organic soil (histosol) either if more than one half ofupper 32 in. (80 mm) of soil is organic or if organic soilmaterial of any thickness rests on rock or on fragmentalmaterial having voids filled with organic material.)3.14 pipe stiffnessforce per un
19、it length, per unit deflectionas defined in Test Method D2412.3.15 power feedermechanism that applies force to thepipe as it passes through the boot or shield to reduce stretchduring installation.3.16 pre-rippingthe practice of making a pass with theplow without installing pipe to locate rocks and t
20、o reduce draft.3.17 start holea trench sufficiently long and wide to allowworking room for placing the boot or shield, blade or cuttingmechanism on grade to start the trench and to install connec-tions or pipe.3.17.1 DiscussionStart holes are usually dug with a back-hoe with a flat-bottom trench.3.1
21、8 stretchthe increase in length of the pipe caused bytension forces during installation. It is expressed as a percentincrease of the length prior to installation. Stretch differs fromelongation in that elongation is a material test and stretch is aninstallation test.3.19 synthetic envelopean envelop
22、e made of syntheticgeotextiles, usually thin synthetic fabrics or thicker fibrousmaterial, or both, often selected to function as a filter.3.20 trench depththe depth of the trench measured fromthe bottom of the pipe.3.21 trench widththe width of the trench measured at thetop of the pipe.3.22 Fig. 1
23、illustrates the terms bedding, vertical deflection,backfill material, cover, groove support angle, horizontaldeflection, trench width, and trench depth.Fig. 2 illustrates various support grooves or trench bottomshapes.Fig. 3 illustrates envelope and filter.Fig. 4 illustrates rodent protection device
24、s.Fig. 5 illustrates boot or shield.4. General Requirements4.1 BurialThe maximum and minimum burial depth areaffected by the following factors, groove support angle of thetrench bottom, bedding, blinding backfill soil density, envelopedensity, envelope placement, pipe stiffness, the live loadexpecte
25、d, desired water table depth, and width of trench.4.1.1 Minimum Depth:4.1.1.1 Mineral SoilsThe minimum recommended coverneeded to protect the pipe from crushing under live loads is 2ft (0.6 m). Granular bedding or special construction techniquesmay be used to reduce the cover. The time for consolida
26、tion ofbackfill may be a factor (see 8.1). The minimum cover mayhave limiting factors other than crushing such as clearance forsubsoiling and utility crossing.4.1.1.2 Organic SoilsSubsurface drains should be in-stalled in these soils only after initial subsidence has occurred.To produce initial subs
27、idence open ditches should be con-structed in deep organic soils to carry off free water, and thearea should be allowed to stand or be partially cultivated for aperiod of 3 to 5 years before installing pipe. The recommendedminimum cover for the pipe in organic soils is 2.5 ft (0.7 m).If water level
28、controls are not provided in the drainage systemFIG. 1 Terminology for Installation of Plastic Drain PipeFIG. 2 Support GroovesF449 02 (2014)2to hold subsidence to a minimum, the depth of cover should beincreased to 3 ft (0.9 m).NOTE 1These minimum depths are recommended to prevent crushingof the pi
29、pe by normal agricultural vehicle loads. Other drainage factorssuch as those encountered with salinity control in arid irrigated lands mayrequire minimum depths of 6 ft (1.8 m).4.1.2 Maximum DepthThe maximum burial depth is in-fluenced by such factors as degree of compaction, type ofbedding, support
30、 from the trench bottom, trench width, size ofpipe, pipe stiffness, weight of backfill, and live loads imposed.Without an engineering design, maximum buried depths shouldbe limited to those listed in Table 1. For installation at depthsgreater than those listed in Table 1, specifications of andengine
31、ering design should be followed.4.1.3 Trench WidthIncreasing the trench width increasesthe soil load on the pipe. Side clearances of more than 150 mm(6 in.) on each side should only be used with an engineeringdesign and special construction (see Table 1). Trench widthmust be at least 50 mm (2 in.) w
32、ider than the pipe on each sidefor plow installation and 75 to 150 mm (3 to 6 in.) on each sidefor open trench installation to allow sufficient bedding tosupport the pipe. If fine material cannot be placed alongsideand over the pipe, a wider trench should be considered orspecial bedding material sup
33、plied.4.2 Design ItemsIt is particularly important that blinding,bedding, or envelope material be placed as the pipe is installed,to ensure uniform continuous support, so that the bedding,blinding, or envelope material can provide lateral restraintagainst pipe deflection as the backfill settles on t
34、he bedding,blinding, or envelope material.4.3 EnvelopesMust be designed to provide adequate sup-port for the pipe, improve the flow of ground water into thepipe, and in some installations, filter flow into the pipe.4.3.1 Natural Granular EnvelopesMinimum thickness of75 mm (3 in.) around the pipe.4.3
35、.2 Synthetic EnvelopesBlinding or bedding is neededto support and hold the envelope and pipe in place.4.4 FiltersAre required when ground water can developvelocities sufficient to move sand or silt, or both, into the drain.Filters must be able to restrict the movement of these particlesinto the pipe
36、 so that the hydraulic capacity of the pipe ismaintained.4.4.1 Granular FiltersDesign of a graded sand and finegravel filter should match the gradation of the specific soilfollowing criteria developed by the Natural Resource Conser-vation Service, the U.S. Bureau of Reclamation, or the U.S.Army Corp
37、s of Engineers.4.4.2 Synthetic FiltersThin synthetic fabric material orgeotextiles may be used where bedding, soil, and hydraulicconditions permit. The openings in synthetic filters must becompatible with the soil that surrounds the drain to preventexcessive movement of soil that otherwise could plu
38、g the drainor filter (see 5.3).NOTE 2These filters must be specified to be compatible with the soiltype that encompasses the conduit since protective filters can plug anddecrease the inflow capability. Where fiberglass filter material is used, itshall be manufactured from borosilicate-type glass and
39、 the manufacturershall certify that it is suitable for underground use. The fibers should be ofvariable size, with some larger fibers intertwined in the mat in a randommanner.NOTE 3Vegetative filter material such as straw, hay, corn-cobs,woodchips, sawdust, and coconut fiber are not recommended for
40、use withflexible conduits because such conduits depend on the development oflateral support and these soft materials may not provide the necessarylateral support.4.5 GradeShall be as specified in the plan or guide.Deviations greater than the following shall not be allowed.Vertical deviations of more
41、 than 0.1 ft (30.5 mm) in 10 ft (3.05m). Negative grade that would fill the pipe more than 10 %.Due to the speed of installation with the plow, automatic gradecontrol is recommended. The pipe feeding system shall holdthe pipe in place in the bottom of the trench until secured by thebedding, blinding
42、, or envelope material.4.6 Material RequirementsPipe and fittings shall meet therequirements of the applicable ASTM standards referenced inSection 2 and Table 1.5. Significant Factors in Pipe/Soil Interactions5.1 ConnectionsIn start holes and adjacent open trenches,the pipe shall be aligned both ver
43、tically and horizontally,blinded and hand tamped along the sides of the pipe to preventexcessive deflection.5.2 DeflectionThe deflection of corrugated plastic pipe isrelated to installation practice, bedding, groove support angle,blinding, gradation and density of soil, depth of installation,trench
44、width in relation to pipe size, live loads imposed,stretch, and pipe stiffness of pipe. Maximum pipe deflectionshould be specified and not exceed 10 % of its nominaldiameter.FIG. 3 Pipe Encased in Bedding for Support (left) and Pipe En-cased in Sand and Gravel Envelope Designed as Filter (right)F449
45、 02 (2014)35.3 FiltersSynthetic materials should never be used whenthe soil has a silt content greater than 40 %.5.4 Trench DepthSee 4.1.5.5 Trench WidthThe width of the trench or blade belowthe top of the pipe should be adequate to allow placing pipe,reducers, and connectors in the bottom of the tr
46、ench and shouldconform to 4.1.3.6. Construction6.1 AlignmentShould be as smooth as possible with acurve radius larger than five times the pipe diameter.6.2 BackfillingPlace the backfill material so that displace-ment or deflection of the pipe will not occur. This is preferablyon an angle, so the mat
47、erial flows down the front slope. Avoidlarge stones, frozen material, and dry clods that cause concen-trated direct loads on the pipe. The trench should be backfilledas soon as possible after blinding. When installing the pipe ona hot day back-filling should be delayed until pipe temperaturecools to
48、 the soil temperature (see 8.1).FIG. 4 Suggested Methods of Providing Rodent Protection for Outlet PipesF449 02 (2014)46.3 BeddingNecessary for the support and protection ofthe pipe. If adequate support is not provided by the soil andtrench bottom shape as shown in Fig. 2, envelopes or specialconstr
49、uction should be used.6.4 BlindingMaterial used for this process should notcontain any hard object larger than 38 mm (112 in.) in diameterand should cover the pipe to a depth of 150 mm (6 in.). See Fig.5 for possible boot and shield configuration.6.5 Bottom ShapeThe bottom should be one of the shapesshown in Fig. 2. The 90 “V” bottom of Fig. 2 works well onnominal sizes less than 200 mm (8 in.). The pipe is pressed intothe void, which reduces horizontal deflection in the completedinstallation. For pipe 200 mm (8 in.) or greater,
