Designation: C 478M – 09

Standard Specification for

Precast Reinforced Concrete Manhole Sections (Metric)1
This standard is issued under the fixed designation C 478M; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.

PART I—GENERAL A 82/A 82M Specification for Steel Wire, Plain, for Con-
crete Reinforcement
1. Scope A 185/A 185M Specification for Steel Welded Wire Rein-
1.1 This specification covers the manufacture and purchase forcement, Plain, for Concrete
requirements of products used for the assembly and construc- A 496/A 496M Specification for Steel Wire, Deformed, for
tion of circular vertical precast reinforced concrete manholes Concrete Reinforcement
and structures used in sewer, drainage, and water works. A 497/A 497M Specification for Steel Welded Wire Rein-
1.2 Part I, Sections 1-11, of this specification presents forcement, Deformed, for Concrete
general requirements and requirements which are common to A 615/A 615M Specification for Deformed and Plain
each precast concrete product covered by this specification. Carbon-Steel Bars for Concrete Reinforcement
1.3 Part II of this specification presents specific require- A 706/A 706M Specification for Low-Alloy Steel De-
ments for each manhole product in the following sections: formed and Plain Bars for Concrete Reinforcement
Product Section C 33 Specification for Concrete Aggregates
Grade Rings 12 C 39/C 39M Test Method for Compressive Strength of Cy-
Flat Slab Tops 13
Risers and Conical Tops 14 lindrical Concrete Specimens
Base Sections 15 C 150 Specification for Portland Cement
Steps and Ladders 16 C 260 Specification for Air-Entraining Admixtures for Con-
NOTE 1—Future products will be included in Part II in a future revision crete
of this specification. C 309 Specification for Liquid Membrane-Forming Com-
1.4 This specification is the SI companion to C 478. pounds for Curing Concrete
C 494/C 494M Specification for Chemical Admixtures for
NOTE 2—This specification is a manufacturing and purchase specifica- Concrete
tion only, and does not include requirements for backfill, or the relation-
ship between field load conditions and the strength requirements of the
C 497 Test Methods for Concrete Pipe, Manhole Sections,
manhole products and appurtenances. Experience has shown, however, or Tile
that the successful performance of this product depends upon the proper C 595 Specification for Blended Hydraulic Cements
selection of the product strength, type of foundation and backfill, and care C 618 Specification for Coal Fly Ash and Raw or Calcined
in the field installation of the manhole products and connecting pipes. The Natural Pozzolan for Use in Concrete
owner of the project for which these products are specified herein is C 822 Terminology Relating to Concrete Pipe and Related
cautioned to require inspection at the construction site.
Products
2. Referenced Documents C 989 Specification for Slag Cement for Use in Concrete
and Mortars
2.1 ASTM Standards:2
C 1017/C 1017M Specification for Chemical Admixtures
for Use in Producing Flowing Concrete
1
This specification is under the jurisdiction of ASTM Committee C13 on
Concrete Pipe and is the direct responsibility of Subcommittee C13.06 on Manholes
and Specials.
Current edition approved Feb. 1, 2009. Published February 2009. Originally
approved in 1980. Last previous edition approved in 2008 as C 478M – 08´1.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.

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 C 478M – 09
2.2 ACI Standard: 4.1.5.4 Chemical admixture or blend approved by the
ACI 318 Building Code, Requirements for Reinforced Con- owner.
crete3 4.1.6 Steel Reinforcement—Reinforcement shall consist of
wire conforming to Specification A 82/A 82M or Specification
3. Terminology A 496/A 496M, of wire fabric conforming to Specification
3.1 Definitions—For definitions of terms relating to con- A 185/A 185M or Specification A 497/A 497M, or of bars of
crete pipe, see Terminology C 822. Grade 40 steel conforming to Specification A 615/A 615M or
of bars conforming to Specification A 706/A 706M.
4. Materials and Manufacture 4.1.7 Secondary Synthetic Fiber—Collated fibrillated
4.1 General material requirements for precast reinforced polypropylene virgin fibers shall not be prohibited when used
concrete manhole products are presented in 4.1.1-4.1.8. Other in steel reinforced concrete manholes as a non-structural
materials or additional requirements for a product, if any, are manufacturing enhancement. Only fibers designed and manu-
covered in the Part II section for that specific product. factured specifically for use in concrete and so certified by the
4.1.1 Reinforced Concrete—Reinforced concrete shall con- manufacturer shall be accepted.
sist of cementitious materials, mineral aggregates, and water, in 4.1.8 Other Materials—Other materials required for a prod-
which steel reinforcement has been embedded in such a uct and not covered in Section 4 will be covered in the Part II
manner so that the steel reinforcement and concrete act section for that specific product.
together.
5. Design
4.1.2 Cementitious Materials:
4.1.2.1 Cement—Cement shall conform to the requirements 5.1 Design requirements for a product are prescribed in the
for portland cement of Specification C 150, or shall be portland specific Part II section for that product.
blast-furnace slag cement or portland-pozzolan cement con- 5.1.1 The minimum compressive strength of concrete man-
forming to Specification C 595, except that the pozzolan hole products covered by this specification shall be 27.6 MPa
constituent of the Type IP portland-pozzolan cement shall be unless specified otherwise in Part II of this specification.
fly ash. 5.2 Modified or Special Design:
4.1.2.2 Fly Ash—Fly ash shall conform to the requirements 5.2.1 Manufacturers are not prohibited from submitting to
of Class F or Class C of Specification C 618. the owner, for approval prior to manufacture, designs other
4.1.2.3 Ground Granulated Blast-Furnace Slag (GGBFS)— than those prescribed in the specific section for a product. If
GGBFS shall conform to the requirements of Grade 100 or 120 such approval is obtained, then the product shall meet all the
of Specification C 989. tests and performance requirements specified by the owner in
4.1.3 Allowable Combinations of Cementitious Materials— accordance with the appropriate sections on manufacture and
The combination of cementitious materials used in the concrete physical requirements.
shall be one of the following: 5.2.2 If permitted by the owner, the manufacturer is not
4.1.3.1 Portland cement only, prohibited from requesting approval of designs of special
4.1.3.2 Portland blast-furnace slag cement only, sections, such as reducers, tees, and bases.
4.1.3.3 Slag modified Portland cement only,
6. Reinforcement
4.1.3.4 Portland pozzolan cement only,
4.1.3.5 A combination of Portland cement and ground 6.1 This section presents requirements for reinforcement
granulated blast-furnace slag, cover, continuity, laps, welds and splices. Other reinforcement
4.1.3.6 A combination of Portland cement and fly ash, or requirements are presented in Section 4 and any additional
4.1.3.7 A combination of Portland cement, ground granu- requirements are given in the Part II section for a specific
lated blast-furnace slag (not to exceed 25 % of the total product.
cementitious weight) and fly ash (not to exceed 25 % of the 6.2 Cover—The exposure of the ends of reinforcement,
total cementitious weight). stirrups or spacers used to position the reinforcement during
4.1.4 Aggregates—Aggregates shall conform to Specifica- placement of the concrete shall not be cause for rejection.
tion C 33, except that the requirements for gradation shall not 6.3 Continuity—The continuity of the circumferential rein-
apply. forcement shall not be destroyed during the manufacture of the
4.1.5 Admixtures and Blends—The following admixtures product, except when lift holes or pipe openings are provided
and blends are allowable: in the product.
4.1.5.1 Air-entraining admixture conforming to Specifica- 6.4 Welded Steel Cage Laps, Welds, and Splices:
tion C 260; 6.4.1 If splices are not welded, the reinforcement shall be
4.1.5.2 Chemical admixture conforming to Specification lapped not less than 20 diameters for deformed bars, and 40
C 494/C 494M; diameters for plain bars and cold-drawn wire. In addition,
4.1.5.3 Chemical admixture for use in producing flowing where lapped cages of welded wire fabric are used without
concrete conforming to Specification C 1017/C 1017M; welding, the lap shall contain a longitudinal wire.
6.4.2 When splices are welded and are not lapped to the
minimum requirements in 6.4.1, pull tests of representative
3
Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington specimens shall develop at least 50 % of the minimum speci-
Hills, MI 48333-9094, http://www.aci-int.org. fied strength of the steel, and there shall be a minimum lap of

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 C 478M – 09
50 mm. For butt welded splices in bars or wire, permitted only 8.1.1.1 Acceptance of a product on the basis of tests of
with helically wound cages, pull tests of representative speci- materials, including concrete compressive strength and absorp-
mens shall develop at least 75 % of the minimum specified tion.
strength of the steel. 8.1.1.2 Acceptance of a product on the basis of inspection of
6.5 Steel Hoop Splices—A representative sample steel hoop the finished product, including amount and placement of
with welded splices shall develop at least 50 % of the mini- reinforcement to determine conformance with the design
mum specified strength of the steel, and there shall be a prescribed under this specification, and freedom from defects.
minimum lap of 50 mm. For butt welded splices, the represen- 8.2 Test Methods:
tative steel hoop sample shall develop at least 75 % of the 8.2.1 Concrete Compressive Strength Test:
minimum specified strength of the steel. 8.2.1.1 Type of Specimen—Compression tests for satisfying
7. Precast Concrete Manufacture the minimum specified concrete strength requirement shall be
made on either concrete cylinders or, at the option of the
7.1 Mixture—The aggregates shall be sized, graded, propor-
manufacturer, on cores cut from the concrete manhole product.
tioned, and mixed with such proportions of cementitious
8.2.1.2 Compression Testing of Cylinders—Cylinders shall
materials and water as will produce a homogeneous concrete
be made in accordance with Test Methods C 497, and shall be
mixture of such quality that the products will conform to the
tested in accordance with Test Method C 39. For manhole
test and design requirements of this specification. All concrete
products, an owner shall not be prohibited from requiring
shall have a water-cementitious ratio not exceeding 0.53 by
concrete compressive tests on cylinder specimens numbering
mass. Cementitious materials shall be as specified in 4.1.2 and
in the amount of 5 % of the total order of a manhole product,
shall be added to the mix in a proportion not less than 280
but not to exceed two cylinders for each day’s production. The
kg/m3, unless mix designs with a lower cementitious materials
average compressive strength of all cylinders tested shall be
content demonstrate that the quality and performance of the
equal to or greater than the specified strength of the concrete.
product meet the requirements of this specification.
Not more than 10 % of the cylinders tested shall fall below the
7.2 Curing—Concrete products shall be subjected to any
specified strength of the concrete. In no case shall any cylinder
one of the methods of curing prescribed in 7.2.1-7.2.4 or to any
tested fall below 80 % of the specified strength of the concrete.
other method or combination of methods approved by the
owner that will give satisfactory results. 8.2.1.3 Compression Testing of Cores—Cores shall be cut
7.2.1 Steam Curing—Concrete products are placed in a from the concrete manhole product and tested in accordance
curing chamber, free of outside drafts, and cured in a moist with Test Methods C 497, except that the requirements for
atmosphere maintained by the injection of steam for such time moisture conditioning shall not apply. One core shall be taken
and such temperatures as may be needed to enable the products from a manhole product selected at random from each day’s
to meet the strength requirements. The curing chamber shall be production run of a single concrete strength. When the concrete
so constructed as to allow full circulation of the steam around compressive strength of the core is equal to or greater than
the entire product. 80 % of the specified strength of the concrete, the concrete
7.2.2 Water Curing—Concrete products are water-cured by strength of the production run is acceptable. If the core does
covering with water-saturated material, or by a system of not meet the preceding concrete strength requirement, another
perforated pipes, mechanical sprinklers, porous hose, or by any core from the same manhole product may be taken and tested.
other approved method that will keep the products moist during 8.2.1.4 If the concrete compressive strength of the recore is
the curing period. equal to or greater than 80 % of the specified strength of the
7.2.3 Sealing Membrane—A sealing membrane conforming concrete, the concrete strength of the production run is accept-
to the requirements of Specification C 309 is applied and shall able. If the recore does not meet the preceding concrete
be left intact until the required concrete strength requirements strength requirement, that manhole product shall be rejected.
are met. The concrete at the time of application of the Two manhole products from the remainder of the day’s
membrane shall be within 6°C of the atmospheric temperature. production run shall be selected at random and one core taken
All concrete surfaces shall be kept moist prior to the applica- from each manhole product and tested. When the average
tion of the membrane and shall be damp when the membrane concrete strength of the two cores is equal to or greater than
is applied. 80 % of the specified strength of the concrete with no core
7.2.4 The manufacturer is not prohibited from combining below 75 % of the specified strength of the concrete, the
methods prescribed in 7.2.1-7.2.3 provided the required con- concrete strength of the day’s production run shall be accept-
crete compressive strength is attained. able.
8.2.1.5 If the concrete strength of the two cores does not
8. Acceptance meet the preceding concrete strength requirement, then the
8.1 Acceptance Procedures: remainder of the day’s production run shall be either rejected,
8.1.1 Unless otherwise designated by the owner at the time or, at the option of the manufacturer, each manhole product of
of, or before, placing an order, acceptance procedures for the remainder of the day’s production run is not prohibited
precast reinforced concrete manhole products shall be as from being cored and accepted individually.
specified in the Part II section for a particular product, and shall 8.2.1.6 Plugging Core Holes—Core holes on accepted man-
not be prohibited from consisting of one or more of the hole sections shall be plugged and sealed by the manufacturer
following: in a manner such that the manhole products will meet all of the

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 C 478M – 09
requirements of this specification. Manhole sections so sealed 12.2 Acceptance—Acceptability of grade rings covered by
shall be considered as satisfactory for use. this specification shall be determined by the results of such
8.2.2 Absorption Test: tests of materials as are required by Section 4; by compressive
8.2.2.1 The absorption of a specimen from a concrete strength tests on concrete cores or concrete cylinders required
product, as determined in Test Methods C 497, shall not exceed by Section 8; and by inspection of the finished product,
9 % of the dry mass for Test Method A procedure or 8.5 % for including amount and placement of reinforcement as pre-
Test Method B procedure. All specimens shall be free of visible scribed by 12.4, 12.5 and 12.6, to determine its conformance
cracks and shall represent the full thickness of the product. with the design prescribed under this specification and its
8.2.2.2 Specimens for Test Method B shall meet the require- freedom from defects.
ments of Test Methods C 497. 12.3 Design —The minimum wall thickness shall be one
8.2.2.3 Each specimen tested by Test Method A shall have a twelfth of the internal diameter of the grade ring or 100 mm,
minimum mass of 1.0 kg.
whichever is greater.
8.2.2.4 When the initial absorption specimen from a con-
crete product fails to conform to this specification, the absorp- 12.3.1 Joints—Grade rings are not required to have the joint
tion test shall be made on another specimen from the same formed with male and female ends.
product and the results of the retest shall be substituted for the 12.4 Circumferential Reinforcement:
original test results. 12.4.1 The circumferential reinforcement shall have an
8.2.3 Retests—When not more than 20 % of the concrete equivalent area of not less than 150 mm2/vertical m, but not
test specimens tested under either 8.2.2.1 or 8.2.2.2 fail to pass less than 15 mm2 in any one grade ring.
the requirements of this specification, the manufacturer is not 12.4.2 The circumferential reinforcement shall be one line
prohibited from culling his stock and eliminating whatever in the center third of the wall of the grade ring.
quantity of product he desires and shall so mark the culled
12.5 Permissible Variations:
product that they will not be shipped for the order. The required
tests shall be made on the balance of the order and the products 12.5.1 Internal Diameter—The internal diameter of grade
shall be accepted if in conformance with the requirements of rings shall not vary more than 61 %.
this specification. 12.5.2 Wall Thickness—The wall thickness of grade rings
8.3 Test Equipment—Every manufacturer furnishing man- shall be not less than that prescribed in the design by more than
hole products under this specification shall furnish all facilities 5 % or 65 mm, whichever is greater. A wall thickness greater
and personnel necessary to carry out the tests required for than that prescribed in the design shall not be cause for
acceptance. rejection.
12.5.3 Height of Two Opposite Sides—Variations in laying
9. Repairs
heights of two opposite sides of grade rings shall be not more
9.1 Repair of manhole products shall not be prohibited, if than 6 mm.
necessary, because of imperfections in manufacture or damage
12.5.4 Height of Grade Ring—The underrun in height of a
during handling, and will be acceptable if, in the opinion of the
grade ring shall be not more than 20 mm/m of height.
owner, the repaired products conform to the requirements of
this specification. 12.5.5 Position of Reinforcement—For grade rings with a
100-mm wall thickness, the maximum variation in the design
10. Inspection position of circumferential reinforcement from that described
10.1 The quality of materials, the process of manufacture, in 12.4.1 shall be 610 % of the wall thickness or 66 mm,
and the finished manhole products shall be subject to inspec- whichever is greater. For grade rings with a wall thickness
tion and approval by the owner. greater than 100-mm, the maximum variation from the design
position of reinforcement shall be 610 % of the wall thickness
11. Product Marking or 616 mm, whichever is the lesser. In no case, however, shall
11.1 The following information shall be legibly marked on the cover over the reinforcement be less than 19 mm. The
each precast concrete product: preceding minimum cover limitation does not apply to the
11.1.1 Specification and product designation: MH for man- mating surfaces of the joint.
hole base, riser, conical tops, and grade rings, 12.5.6 Area of Reinforcement—Steel reinforcement areas
11.1.2 Date of manufacture, and that are 10 mm2/linear m less than called for by design shall be
11.1.3 Name or trademark of the manufacturer. considered as meeting the required steel reinforcement area.
11.2 Marking shall be indented into the concrete or shall be 12.6 Rejection
painted thereon with waterproof paint.
12.6.1 Grade rings shall be subject to rejection for failure to
PART II—PRODUCTS conform to any of the specification requirements. In addition,
an individual grade ring shall be subject to rejection because of
12. Grade Rings any of the following:
12.1 Scope—This section covers precast reinforced con- 12.6.1.1 Fractures or cracks passing through the wall, ex-
crete grade rings used for final adjustment of manholes to cept for a single end crack that does not exceed the depth of the
grade. joint.

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 C 478M – 09
12.6.1.2 Defects that indicate mixing and molding not in 13.4.2 Flat slab tops manufactured without a joint or with-
compliance with 7.1 or surface defects indicating honey- out other indication of the top or bottom of the slab shall be
combed or open texture that would adversely affect the manufactured with two layers of steel reinforcement, one
function of the grade ring. located near the bottom surface and one near the top surface so
12.6.1.3 The planes of the ends are not perpendicular to the that the protective cover over each layer is 25 mm.
longitudinal axis of the grade ring, within the limits of 13.4.3 A layer of reinforcement shall have a minimum area
permissible variations prescribed in 12.5. of 250 mm2/linear m in both directions.
12.6.1.4 Damaged or cracked ends, where such damage 13.4.4 Openings in flat slab tops shall be additionally
would prevent making a satisfactory joint. reinforced with a minimum of the equivalent of 130 mm2 of
12.6.1.5 Any continuous crack having a surface width of 0.3 steel at 90°. Straight rods used to reinforce openings shall have
mm, or more and extending for a length of 300 mm or more, a minimum length equal to the diameter of the opening plus 50
regardless of position in the wall. mm.
13.5 Physical Requirements :
13. Flat Slab Tops
Physical requirements for tests shall conform to the require-
13.1 Scope—This section covers precast reinforced con- ments of Section 8.
crete flat slab tops used in the construction of manholes for use 13.5.1 Proof-of-Design Test:
in sewer, drainage, and water works. 13.5.1.1 If 13.2.2.2 has been designated as the basis of
13.2 Acceptance: acceptance, one flat slab top for each design shall be tested
13.2.1 Acceptability of flat slab tops shall be determined by unless the owner has indicated otherwise.
the results of such tests of materials as are required by Section
13.5.1.2 The flat slab top proof-of-design test procedures
4; by compressive strength tests on concrete cores or concrete
shall be in accordance with Test Methods C 497.
cylinders required by Section 8; and by inspection of the
13.5.1.3 The ultimate test load shall be the sum of at least
finished product, including amount and placement of reinforce-
130 % of the dead load on the slab plus at least 217 % of the
ment as prescribed by 13.4 and 13.6, to determine its conform-
live-plus impact load on the slab. Dead load is the mass of the
ance with the design prescribed under this specification and its
column of earth over the slab plus the mass of the riser
freedom from defects.
supported by the slab. Live load is the maximum anticipated
13.2.2 Unless otherwise designated by the owner at the time
wheel load that may be transmitted through the riser to the slab.
of, or before, placing an order, two separate and alternative
methods of acceptance are permitted for flat slab top manufac- 13.5.1.4 The flat slab top shall be acceptable if it supports
turer designs, in addition to tests of materials and inspection the required ultimate test load without failure. Ultimate
required in 13.2.1. strength failure is defined as the inability of the slab to resist an
13.2.2.1 Acceptance on the Basis of Proof-of-Design Test— increase in the applied load.
Acceptance of flat slab tops on the basis of the results of a 13.5.1.5 When agreed upon by the owner and manufacturer,
proof-of-design test performed in accordance with 13.5 in lieu the flat slab top shall be acceptable based on certified copies of
of submission of design calculations and detailed drawings. the results of tests performed on identical flat slab tops instead
13.2.2.2 Acceptance on the Basis of Rational Design— of requiring new proof-of-design acceptance tests.
Acceptance of flat slab tops on the basis of design calculations 13.6 Permissible Variations:
by a rational method and detailed drawings. 13.6.1 Internal Diameter—The internal diameter of the flat
13.3 Design: slab tops entrance hole shall not vary more than 61 %.
13.3.1 The basis of flat slab top designs shall be the 13.6.2 Thickness—The thickness of flat slab tops shall be
appropriate sections of the latest edition of ACI 318. not less than that prescribed in the design by more than 5 % or
13.3.2 Flat slab tops shall have a minimum thickness of 150 65 mm, whichever is greater. A thickness greater than that
mm for risers up to and including 1200 mm in diameter and prescribed in the design shall not be cause for rejection.
200 mm for larger diameters. 13.6.3 Length of Two Opposite Sides—Variations in lengths
13.3.3 The flat slab top access opening shall be a minimum of two opposite sides of flat slab tops shall be not more than 6
of 600 mm in diameter. mm.
13.3.4 Joint—The reinforced concrete flat slab top shall be 13.6.4 Length—The underrun in length of a flat slab top
formed with or without a male or female end so that when the shall be not more than 20 mm/m of length.
manhole base, riser and top section are assembled, they will 13.6.5 Position of Reinforcement—For flat slab tops with
make a continuous and uniform manhole compatible with the less than a 150-mm thickness, the maximum variation in the
tolerances given in Section 13.6. position of reinforcement from that prescribed in 13.5 shall be
13.3.4.1 Joints are designed to perform in axial compres- 610 % of the thickness or 66 mm, whichever is greater. For
sion; therefore, shear or load testing of the joint is not required. flat slab tops with a thickness greater than 150-mm, the
13.4 Reinforcement: maximum variation shall be 610 % of the thickness or 616
13.4.1 Flat slab tops manufactured with a joint or with other mm, whichever is the lesser. In no case, however, shall the
indication of the top or bottom of the slab shall be manufac- cover over the reinforcement be less than 19 mm.
tured with one layer of reinforcement placed near the bottom 13.6.6 Area of Reinforcement—Steel reinforcement areas
surface so that the protective cover over the reinforcement shall that are 10 mm2/linear m less than called for by design shall be
be 25 mm. considered as meeting the required steel reinforcement area.

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 C 478M – 09
13.7 Rejection: 14.4.1.4 Where two lines of circumferential reinforcement
13.7.1 Flat slab tops shall be subject to rejection for failure are used, each line shall be so placed that the protective
to conform to any of the specification requirements. In addi- covering over the circumferential reinforcement in the wall
tion, an individual flat slab top shall be subject to rejection shall be 25 mm.
because of any of the following: 14.4.1.5 The location of the reinforcement shall be subject
13.7.1.1 Fractures or cracks passing through the wall, ex- to the permissible variations in dimensions prescribed in 14.7.
cept for a single end crack that does not exceed the depth of the 14.4.1.6 The spacing center to center of circumferential
joint. reinforcement in a cage shall not exceed 150 mm.
13.7.1.2 Defects that indicate mixing and molding not in 14.4.2 Longitudinal Members—Each line of circumferential
compliance with 7.1 or surface defects indicating honey- reinforcement shall be assembled into a cage that shall contain
combed or open texture that would adversely affect the sufficient longitudinal bars or members to maintain the rein-
function of the flat slab top. forcement in shape and position within the form to comply
13.7.1.3 The planes of the ends are not perpendicular to the with permissible variations in 14.7.
longitudinal axis of the flat slab top, within the limits of 14.4.3 Joint Reinforcement—The tongue or groove of the
permissible variations prescribed in 13.6. joint is not required to contain circumferential reinforcement.
13.7.1.4 Damaged or cracked ends, where such damage 14.5 Steel Hoop Reinforcement:
would prevent making a satisfactory joint. 14.5.1 Continuous Steel Hoop Reinforcement for Risers and
13.7.1.5 Any continuous crack having a surface width of 0.3 Conical Tops up to and Including 1200 mm Diameter:
mm, or more and extending for a length of 300 mm or more, NOTE 3—Care shall be taken to ensure that none of the steel hoop
regardless of position in the slab. reinforcement is cut prior to installation of the riser or conical top.

14. Risers and Conical Tops 14.5.1.1 Circumferential reinforcement for manhole risers
and conical tops up to and including 600 mm in height shall
14.1 Scope—This section covers precast reinforced con- consist of no less than two hoops of steel wire or reinforcing
crete risers and conical tops used in construction of manholes bars. The steel hoop shall have a minimum cross-sectional
for use in sewer, drainage, and water works. diameter of 6 mm and shall be located in each end quarter of
14.2 Acceptance—Acceptability of risers and conical tops the riser or conical top, with a minimum distance of 25 mm
covered by this specification shall be determined by the results from the shoulder of the riser or conical top.
of such tests of materials as are required by Section 4; by 14.5.1.2 Circumferential reinforcement for manhole risers
compressive strength tests on concrete cores or concrete and conical tops greater in height than 600 mm and up to and
cylinders required by Section 8; and by inspection of the including 1200 mm in height shall consist of no less than three
finished product, including amount and placement of reinforce- hoops of steel wire or reinforcing bars. The steel hoops shall
ment as prescribed by either 14.4 or 14.5 and meeting have a minimum cross-sectional diameter of 6 mm, and shall
permissible variations as prescribed by 14.7, to determine its have a hoop located in each end quarter of the riser or conical
conformance with the design prescribed under this specifica- top with a minimum distance of 25 mm from the shoulder of
tion and its freedom from defects. the riser or conical top. The third, or middle, hoop shall be
14.3 Design—The minimum wall thickness shall be one located from the shoulder of the riser or conical top a distance
twelfth of the largest internal diameter of the riser or conical equal to one-half the section height 6150 mm.
top. 14.5.1.3 Circumferential reinforcement for manhole risers
14.4 Welded Steel Cage Reinforcement: and conical tops greater in height than 1200 mm. and up to and
14.4.1 Circumferential Reinforcement for Risers and Coni- including 1800 mm in height shall consist of no less than four
cal Tops: hoops of steel wire or reinforcing bars spaced equally 675
14.4.1.1 Circumferential reinforcement may consist of ei- mm. throughout the height of the riser or conical top. The steel
ther one or two lines of steel. The total area of reinforcement hoops shall have a minimum cross-sectional diameter of 6 mm
per vertical metre shall be not less than 0.21 times the internal and shall have a hoop located in each end quarter of the riser
diameter in millimetres. or conical top with a minimum distance of 25 mm from the
14.4.1.2 A line of circumferential reinforcement for any shoulder of the riser or conical top.
given total area may be composed of two layers if the layers are 14.5.1.4 The hoop reinforcement shall be placed in the
not separated by more than the thickness of one cross member center third of the riser wall or conical top. The concrete cover
plus 6 mm. The two layers shall be tied together to form a over the hoop reinforcement in the wall of the section shall be
single cage. All other specification requirements such as laps, no less than 19 mm in accordance with 14.7.
welds, and tolerances of placement in the wall of the riser or 14.5.2 Joint Reinforcement—The tongue or groove of the
conical top shall apply to this method of fabricating a line of joint need not contain circumferential reinforcement.
reinforcement. 14.6 Joints—Precast reinforced concrete risers and conical
14.4.1.3 Where one line of circumferential reinforcement is tops shall be designed and manufactured with male and female
used, it shall be placed in the center third of the wall. The ends, so that the assembled manhole base, riser and conical top
protective cover over the circumferential reinforcement in the shall make a continuous and uniform manhole, compatible
wall shall be no less than 19 mm in accordance with 14.7. with the tolerances given in 14.7.

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14.6.1 Joints are designed to perform in axial compression; slab and a riser section with a sealed joint between the two. The
therefore, shear or load testing of the joint is not required. riser portions of the base section shall meet all the requirements
14.7 Permissible Variations: of Section 14.
14.7.1 Internal Diameter—The internal diameter of risers 15.2 Acceptance—Acceptability of base sections covered
and conical tops shall not vary more than 1 %. by this specification shall be determined by the results of such
14.7.2 Wall Thickness—The wall thickness of risers and tests of materials as are required by Section 4; by compressive
conical tops shall be not less than that prescribed in the design strength tests on concrete cores or concrete cylinders required
by more than 5 % or 65 mm, whichever is greater. A wall by Section 8; and by inspection of the finished product,
thickness greater than that prescribed in the design shall not be including amount and placement of reinforcement as pre-
cause for rejection. scribed by 15.4 and 15.6, to determine conformance with the
14.7.3 Height of Two Opposite Sides—Variations in laying design prescribed under this specification and its freedom from
heights of two opposite sides of risers or conical tops shall be defects.
not more than 16 mm. 15.3 Design:
14.7.4 Height of Section—The underrun in height of a riser 15.3.1 The basis of base slab designs shall be the appropri-
or conical top shall be not more than 20 mm/m of height with ate sections of the latest edition of ACI 318.
a maximum of 13 mm in any one section. 15.3.2 Base slabs or integral floors shall have a minimum
14.7.5 Position of Reinforcement—For risers or conical tops thickness of 150 mm for risers up to and including 1200 mm in
with a 100-mm wall thickness or less, the maximum variation diameter and 200 mm for larger diameters.
in the position of reinforcement from that prescribed in 14.5 15.3.2.1 When a base section is precast monolithically with
and 14.6 shall be 610 % of the wall thickness or 66 mm, a benched invert, the minimum concrete thickness from the
whichever is greater. For sections with a wall thickness greater invert to the bottom of the integral base section shall be 100
than 100 mm, the maximum variation in shall be 610 % of the mm.
wall thickness or 616 mm, whichever is the lesser. In no case,
15.3.3 Benched inverts cast either monolithically with the
however, shall the cover over the reinforcement be less than 19
base section or as a secondary casting in a cured base section
mm. The preceding minimum cover limitation does not apply
shall have the following minimum dimensions:
to the mating surfaces of the joint.
15.3.3.1 Minimum slope of 40 mm/m from the channel to
14.7.6 Area of Reinforcement—Steel reinforcement areas
the inside diameter (ID) of manhole wall for the benching.
that are 0.1 mm2/linear m less than called for by design shall be
considered as meeting the required steel reinforcement area. 15.3.3.2 Minimum channel invert depth of one-half the pipe
14.8 Rejection ID.
14.8.1 Risers and conical tops shall be subject to rejection 15.3.3.3 When a channel is cast in a cured base section, the
for failure to conform to any of the specification requirements. minimum concrete thickness under the invert shall be 50 mm.
In addition, an individual riser or conical top shall be subject to 15.3.3.4 Width of channel at top of benching shall be a
rejection because of any of the following: minimum of the pipe ID.
14.8.1.1 Fractures or cracks passing through the wall, ex- 15.3.3.5 Invert shall provide a positive flow between inlet to
cept for a single end crack that does not exceed the depth of the outlet pipes.
joint. 15.3.3.6 The minimum channel centerline radius shall be
14.8.1.2 Defects that indicate mixing and molding not in the pipe ID.
compliance with 7.1 or surface defects indicating honey- 15.4 Reinforcement:
combed or open texture that would adversely affect the 15.4.1 Base Section Circumferential Reinforcement—
function of the riser or conical top. Circumferential reinforcement shall meet all the requirements
14.8.1.3 The planes of the ends are not perpendicular to the of Section 14, except that Paragraph 14.5 is not permitted.
longitudinal axis of the riser or conical top, within the limits of 15.4.2 Base Slab Reinforcement:
permissible variations prescribed in 14.7. 15.4.2.1 A layer of reinforcement shall be placed above the
14.8.1.4 Damaged or cracked ends, where such damage midpoint, and shall have a minimum area of 250 mm2/linear m
would prevent making a satisfactory joint. in both directions.
14.8.1.5 Any continuous crack having a surface width of 0.3 15.4.2.2 The minimum protective cover over the reinforce-
mm, or more and extending for a length of 300 mm or more, ment shall be 25 mm.
regardless of position in the wall.
15.4.3 Longitudinal Members—Longitudinal bars or mem-
15. Base Sections bers used to maintain a cage of circumferential reinforcement
15.1 Scope—This section covers three types of precast in shape and position within the form shall meet all the
concrete base sections manufactured for use in the construction requirements of Section 14.
of manholes used in sewer, drainage, and water works. The 15.4.4 Joint Reinforcement—The mating surface of the base
three types of base sections are (1) a base with riser wall and section joint is not required to contain circumferential rein-
base slab cast monolithically as a single unit with or without forcement.
benching, (2) a base consisting of a riser section with a NOTE 4—(Advisory) Base sections with multiple openings, large open-
secondary poured integral base slab, with or without benching, ings, or both may require special consideration of their handling rein-
and (3) a two-piece base consisting of a separate precast base forcement.

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 C 478M – 09
15.5 Joints—Precast reinforced base sections shall be de- 16.1.2 The user of this specification is advised that access
signed and manufactured with a male or female ends, so that through manholes may be by steps that are cast, mortared, or
the assembled manhole base, riser and top will make a attached by mechanical means into the walls of base, riser, or
continuous and uniform manhole, compatible with the toler- conical top sections or by ladder.
ances given in 15.6. 16.2 Acceptance—Unless otherwise designated by the
15.5.1 Joints are designed to perform in axial compression; owner at the time of, or before, placing an order, acceptance of
therefore, shear or load testing of the joint is not required. steps and ladders installed in manholes will be on the basis of
15.6 Permissible Variations: tests and inspection of the completed product.
15.6.1 Internal Diameter—The internal diameter of base 16.3 Materials:
sections shall not vary more than 1 %. 16.3.1 Except as required by Section 16, manhole steps and
15.6.2 Thickness—The thickness of a base slabs with or ladders shall conform to the requirements of the Occupational
without benching shall be not less than that prescribed in the Safety and Health Standards, U.S. Department of Labor.
design by more than 5 %. A thickness greater than that
16.3.2 Manhole steps that are cast, mortared, or attached by
prescribed in the design shall not be cause for rejection.
mechanical means into the walls of base, riser or conical top
15.6.3 Height of Two Opposite Sides—Variations in laying
sections shall meet the requirements of 16.4 and 16.5 in
heights of two opposite sides of base sections shall be not more
addition to the following:
than 16 mm.
16.3.2.1 When dissimilar types of materials are used in the
15.6.4 Height of Sections—The underrun in height of a base
steps, appurtenances and fastenings, the materials shall be
section shall be not more than 20 mm/m of height with a
treated to prevent deleterious effects.
maximum of 13 mm in any one base section.
15.6.5 Position of Reinforcement—For base slabs with 16.3.2.2 That portion of the step projecting into the base
monolithic benched inverts with a 100 mm thickness, the section, riser or conical top opening shall be free of splinters,
maximum variation in the position of reinforcement from that sharp edges, burrs, or projections which may be a hazard.
prescribed in 15.4 shall be 610 % of the thickness or 66 mm, 16.4 Design:
whichever is greater. For base slabs with a thickness greater 16.4.1 Steps in base section, riser and conical top sections
than 100-mm, the maximum variation shall be 610 % of the shall be aligned in each section so as to form a continuous
thickness or 616 mm, whichever is the lesser. In no case, ladder with rungs equally spaced vertically in the assembled
however, shall the cover over the reinforcement be less than 19 manhole at a maximum design distance of 400 mm apart.
mm. The preceding minimum cover limitation does not apply 16.4.2 Steps shall be embedded in the base section, riser or
to the mating surfaces of base section joints. conical top section wall a minimum distance of 75 mm.
15.6.6 Area of Reinforcement—Steel reinforcement areas 16.5 Dimensions:
that are 10 mm2/linear m less than called for by design shall be 16.5.1 Ferrous metal steps not painted or treated to resist
considered as meeting the required steel reinforcement area. corrosion shall have a minimum cross sectional dimension of
15.7 Rejection: 25 mm.
15.7.1 Base sections shall be subject to rejection for failure 16.5.2 The minimum width of rungs or cleats shall be 250
to conform to any of the specification requirements. In addi- mm.
tion, an individual base section shall be subject to rejection
16.5.3 The rung or cleat shall project a uniform clear
because of any of the following:
distance of 100 mm (minimum) to 150 mm (maximum) 6 6
15.7.1.1 Fractures or cracks passing through the riser wall,
mm from the wall of the base, riser, or conical top section
except or a single end crack that does not exceed the depth of
measured from the point of embedment to the embedment side
the joint.
of the rung.
15.7.1.2 Defects that indicate mixing and molding not in
compliance with 7.1 or surface defects indicating honey- NOTE 5—Embedment point is considered the junction of the centerline
combed or open texture that would adversely affect the of the step leg and the wall of the base, riser or conical top section.
function of the base section. 16.5.4 The minimum clear distance between the rung or
15.7.1.3 The planes of the ends are not perpendicular to the cleat and the opposite wall of the base, riser, or conical top
longitudinal axis of the base section, within the limits of shall be 450 mm measured at the center face of the rung or
permissible variations prescribed in 15.6. cleat.
15.7.1.4 Damaged or cracked ends, where such damage
16.5.5 The vertical spacing and vertical alignment between
would prevent making a satisfactory joint.
adjacent manhole steps and horizontal distance from the inside
15.7.1.5 Any continuous crack having a surface width of 0.3
wall to the centerline of a manhole step may vary 25 mm from
mm, or more and extending for a length of 300 mm or more,
the design dimension.
regardless of position in the base section.
16.6 Physical Requirements:
16. Steps and Ladders 16.6.1 Testing:
16.1 Scope: 16.6.1.1 The manufacturer furnishing manhole sections
16.1.1 This section covers manhole steps and ladders used with steps under this specification shall furnish all facilities and
for providing access through manholes for use in sewer and personnel necessary to carry out the tests required in the
water works. Manhole Step Test section of Test Methods C 497.

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 C 478M – 09
16.6.1.2 One installed manhole step of the type to be used 16.6.2.3 No cracking or fracture of the step nor spalling of
on a project shall be tested unless certified test results are the concrete is evident.
available. 16.6.2.4 If certified test results are not available and the step
16.6.1.3 Vertical and horizontal load test procedures for selected fails to conform to the test requirements, the manu-
manhole steps shall be in accordance with Test Methods C 497. facturer may select two other steps for retests. If either of these
16.6.1.4 The horizontal pull out load shall be 1800 N. steps fail the retest, the steps shall be rejected.
16.6.1.5 The vertical load shall be 3600 N.
16.6.2 Acceptance—The step shall be acceptable if the 17. Keywords
following requirements are met:
16.6.2.1 The step remains solidly embedded after applica- 17.1 absorption; acceptance criteria; base sections; com-
tion of the horizontal load test. pressive strength; concrete; cone tops; design; flat slab tops;
16.6.2.2 The step sustains a permanent set of 13 mm or less grade rings; ladders; manhole; manufacture; reinforced; riser
after application of the vertical load test. sections; sewer; steps; tests; water

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