PART G – DRAINAGE AND SLOPE PROTECTION STRUCTURES

ITEM 500 – PIPE CULVERTS AND STORM DRAINS

500.1 Description

This item shall consist of the construction or reconstruction of pipe culverts

and storm drains, hereinafter referred to as “conduit” in accordance with this
Specification and in conformity with the lines and grades shown on the Plans or
as established by the Engineer.

500.2 Material Requirements

Material shall meet the requirements specified in the following

specifications:

Zinc coated (galvanized) corrugated iron or steel

culverts and underdrains AASHTO M 36

Cast iron culvert pipe AASHTO M 64

Concrete sewer, storm drain and culvert pipe AASHTO M 86

Reinforced concrete culvert, storm drain and

sewer pipe AASHTO M 170

Bituminous coated corrugated metal culvert pipe

and pipe arches AASHTO M 190

Reinforced concrete arch culvert, storm drain

and sewer pipe AASHTO M 206

Reinforced concrete elliptical culvert, storm drain

and sewer pipe AASHTO M 207

Asbestos cement pipe for culverts and storm drains AASHTO M 217

Joint Mortar – Joint mortar for concrete pipes shall consist of 1 part, by
volume of Portland Cement and two (2) parts of approved sand with water as
necessary to obtain the required consistency.

Portland Cement and sand shall conform to the requirements of Item 405,
Structural Concrete. Mortar shall be used within 30 minutes after its preparation.

Rubber gaskets AASHTO M 198

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 Oakum – Oakum for joints in bell and spigot pipes shall be made from
hemp (Cannavis Sativa) line or Benares Sunn fiber or from a combination of
these fibers. The oakum shall be thoroughly corded and finished and practically
free from lumps, dirt and extraneous matter.

Hot poured joint sealing compound AASHTO M 173

Bedding material shall conform to the requirements of Subsection 500.3.2,

Bedding.

Backfill material shall conform to the requirements of Subsection 500.3.6,

Backfilling.

When the location of manufacturing plants allow, the plants will be

inspected periodically for compliance with specified manufacturing methods, and
material samples will be obtained for laboratory testing for compliance with
materials quality requirements. This shall be the basis for acceptance of
manufacturing lots as to quality.

Prior to and during incorporation of materials in the work, these materials

will be subjected to the latest inspection and approval of the Engineer.

500.3 Construction Requirements

500.3.1 Trenches Excavation

Trenches shall be excavated in accordance with the requirement of Item

103, Structure Excavation, to a width sufficient to allow for proper jointing of the
conduit and thorough compaction of the bedding and backfill materials under and
around the conduit. Where feasible, trench wall shall be vertical.

The completed trench bottom shall be firm for its full length and width.
Where required, in the case of crop drains, the trench shall have a longitudinal
camber of the magnitude specified.

When so specified on the Plans, the excavation for conduits placed in

embankment fill, shall be made after the embankment has been completed to the
specified or directed height above the designed grade of the conduit.

500.3.2 Bedding

The bedding shall conform to one of the classes specified. When no

bedding class is specified, the requirements for Class C bedding shall apply.

Class A bedding shall consist of a continuous concrete cradle conforming

to the plan details.

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 Class B bedding shall consist of bedding the conduit to a depth of not
less than 30 percent of the vertical outside diameter of the conduit. The minimum
thickness of bedding material beneath the pipe shall be 100 mm. The bedding
material shall be sand or selected sandy soil all of which passes a 9.5 mm sieve
and not more than 10 percent of which passes a 0.075 mm sieve. The layer of
the bedding material shall be shaped to fit the conduit for at least 15 percent of
its total height. Recesses in the trench bottom shall be shaped to accommodate
the bell when bell and spigot type conduit is used.

Class C bedding shall consist of bedding the conduit to a depth of not

less than 10 percent of its total height. The foundation surface, completed in
accordance with Item 103, Structure Excavation, shall be shaped to fit the
conduit and shall have recesses shaped to receive the bells, if any.

For flexible pipe, the bed shall be roughly shaped and a bedding
blanket of sand or fine granular material as specified above shall be provided as
follows:

Pipe Corrugation Depth Minimum Bedding Depth

10 mm 25 mm
25 mm 50 mm
50 mm 75 mm

For large diameter structural plate pipes the shaped bed need not
exceed the width of bottom plate.

500.3.3 Laying Conduit

The conduit laying shall begin at the downstream end of the conduit line.
The lower segment of the conduit shall be in contact with the shaped bedding
throughout its full length. Bell or groove ends of rigid conduits and outside
circumferential laps of flexible conduits shall be placed facing upstream. Flexible
conduit shall be placed with longitudinal laps or seams at the sides.

Paved or partially-lined conduit shall be laid such that the longitudinal

center line of the paved segment coincides with the flow line. Elliptical and
elliptically reinforced conduits shall be placed with the major axis within 5
degrees of a vertical plane through the longitudinal axis of the conduit.

500.3.4 Jointing Conduit

Rigid conduits may either be of bell and spigot or tongue and groove
design unless another type is specified. The method of joining conduit sections
shall be such that the ends are fully entered and the inner surfaces are
reasonably flush and even.

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 Joints shall be made with (a) Portland Cement mortar, (b) Portland
Cement grout, (c) rubber gaskets, (d) oakum and mortar, (e) oakum and joint
compound, (f) plastic sealing compound, or by a combination of these types, or
any other type, as may be specified. Mortar joints shall be made with an excess
of mortar to form a continuous bead around the outside of the conduit and
finished smooth on the inside. For grouted joints, molds or runners shall be used
to retain the poured grout. Rubber ring gaskets shall be installed so as to form a
flexible water-tight seal. Where oakum is used, the joint shall be called with this
material and then sealed with the specified material.

When Portland Cement mixtures are used, the completed joints shall be
protected against rapid drying by any suitable covering material.

Flexible conduits shall be firmly joined by coupling bands.

Conduits shall be inspected before any backfill is placed. Any pipe found
to be out of alignment, unduly settled, or damaged shall be taken up and relaid or
replaced.

500.3.5 Field Strutting

When required by the Plans, vertical diameter of round flexible conduit

shall be increased 5 percent by shop elongation or by means of jacks applied
after the entire line of conduit has been installed on the bending but before
backfilling. The vertical elongation shall be maintained by means of sills and
struts or by horizontal ties shall be used on paved invert pipe.

Ties and struts shall be 300 mm in place until the embankment is

completed and compacted, unless otherwise shown on the Plans.

These construction specifications shall also apply in the case of relaid

conduits. In addition, all conduits salvaged for relaying shall be cleaned of all
foreign materials prior to reinstallation.

500.3.6 Backfilling

Materials for backfilling on each side of the conduit for the full trench width
and to an elevation of 300 mm above the top of the conduit shall be fine, readily
compactible soil or granular material selected from excavation or from a source
of the Contractor’s choice, and shall not contain stones that would be retained on
a 50 mm sieve, chunks of highly plastic clay, or other objectionable material.
Granular backfill material shall have not less than 95 percent passing a 12.5 mm
sieve and not less than 95 percent retained on a 4.75 mm sieve. Oversized
material, if present, shall be removed at the source of the material, except as
directed by the Engineer.

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 When the top of the conduit is flushed with or below the top of the trench,
backfill material shall be placed at or near optimum moisture content and
compacted in layers not exceeding 150 mm (compacted) on both sides to an
elevation 300 mm above the top of the conduit. Care shall be exercised to
thoroughly compact the backfill under the haunches of the conduit. The backfill
shall be brought up evenly on both sides of the conduit for the full required
length. Except where negative projecting embankment-type installation is
specified, the backfill material shall be placed and compacted for the full depth of
the trench.

When the top of the conduit is above the top of the trench, backfill shall be
placed at or near optimum moisture content and compacted in layers not
exceeding 300 mm (compacted) and shall be brought up evenly on both sides of
the conduit for its full length to an elevation 300 mm above the top of the conduit.
The width of the backfill on each side of the conduit for the portion above the top
of the trench shall be equal to twice the diameter of the conduit or 3.5 m,
whichever is less. The backfill material used in the trench section and the portion
above the top of the trench for a distance on each side of the conduit equal to the
horizontal inside diameter and to 300 mm above the top of the conduit shall
conform to the requirements for backfill materials in this Subsection. The
remainder of the backfill shall consist of materials from excavation and borrow
that is suitable for embankment construction.

Compaction to the density specified in Item 104, Embankment, shall be

achieved by use of mechanical tampers or by rolling.

All conduits after being bedded and backfill as specified in this Subsection
shall be protected by one metre cover of fill before heavy equipment is permitted
to cross during construction of the roadway.

500.3.7 Imperfect Trench

Under this method, for rigid conduit, the embankment shall be completed
as described in Subsection 500.3.6, Backfilling, to a height above the conduit
equal to the vertical outside diameter of the conduit plus 300 mm. A trench equal
in width to the outside horizontal diameter of the conduit and to the length shown
on the plans or as directed by the Engineer shall then be excavated to within 300
mm of the top of the conduit, trench walls being as nearly vertical as possible.
The trench shall be loosely filled with highly compressible soil. Construction of
embankment above shall then proceed in a normal manner.

500.4 Method of Measurement

Conduit of the different types and sizes, both new and relaid, will be
measured by the linear metre in place. Conduit with sloped or skewed ends will
be measured along the invert.

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 Each section will be measured by the number of units installed.

Branch connection and elbows will be included in the length measurement

for conduit, or they may be measured by the number of units installed.

Class B bedding material placed and approved shall be measured by the

cubic metre in place.

When the Bid Schedule contains an estimated quantity for “Furnishing and
Placing Backfill Material, Pipe Culvert”, the quantity to be paid for will be the
number of cubic metre complete in place and accepted, measured in final
position between limits as follows:

1. Measurement shall include backfill material in the trench up to

the top of the original ground line but will not include any material
placed outside of vertical planes 450 mm up outside of and
parallel to the inside wall of pipe at its widest horizontal
dimension.

2. When the original ground line is less than 300 mm above the top
of the pipe, the measurement will also include the placing of all
backfill materials, above the original ground line adjacent to the
pipe for a height of 300 mm above the top of pipe and for a
distance on each side of the pipe not greater than the widest
horizontal dimension of the pipe.

3. The measurement shall include the placing of backfill material in

all trenches of the imperfect trench method. Materials re-
excavated for imperfect trench construction will be measured for
payment under Item 103, Structure Excavation.

500.5 Basis of Payment

The accepted quantities of conduit, determined as provided in Section

500.4, Method of Measurement, shall be paid for at the contract unit price per
linear meter for the conduit of the types and sizes specified complete in place.
End sections and, when so specified, branch connections and elbows, shall be
paid for at the contract unit price per piece for the kind and size specified
complete in place.

Excavation for culverts and storm drains, including excavation below flow
line grade and for imperfect trench, shall be measured and paid for as provided
in Item 103, Structure Excavation.

Concrete for Class A bedding will be paid for under Item 405,
Structural Concrete.

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 When the Bid Schedule does not contain as estimated quantity for
“Furnishing and Placing Backfill Material, Pipe Culvert” payment for placing
backfill material around pipe culverts will be considered as included in the
payment for excavation of the backfill material.

Payment will be made under:

Payment Item Number Description Unit of Measurement

500 (1) Pipe Culverts, - mm Linear Meter

Class -

500 (2) Storm Drain, - mm Linear Meter

Class -

ITEM 501- UNDERDRAINS

501.1 Description

This item shall consist of constructing underdrains, using pipe and

granular filter materials, underdrain pipe outlets, and blind drains using granular
material in accordance with this Specification and in reasonably close conformity
with the lines and grades shown on the Plans or as established by the Engineer.

501.2 Material Requirements

Material shall meet the requirements specified in the following

specifications:

Zinc coated (galvanized) corrugated iron or steel

Culverts and underdrains AASHTO M 36

Extra strength and standard strength clay pipe

and perforated clay pipe AASHTO M 65

Perforated concrete pipe AASHTO M 175

Porous concrete pipe AASHTO M 176

Bituminized-fiber non-pressure sewer drain and

underdrainage pipe systems AASHTO M 177

Asbestos-cement perforated underdrain pipe AASHTO M 189

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 Granular Backfill Filter Material – Granular backfill filter material shall be
permeable and shall meet the requirements of AASHTO M 6, except that
soundness tests will not be required and minor variation in grading and content of
deleterious substances may be approved by the Engineer.

When the location of manufacturing plants allows, the plants will be

inspected periodically by compliance with specified manufacturing methods, and
material sample will be obtained for laboratory testing for compliance with
material quality requirements. This shall be the basis for acceptance of
manufacturing lots as to quality.

All material shall be subjected to inspection for acceptance as to condition

at the latest practicable time.

501.3 Construction Requirements

501.3.1 Pipe Installation

Trenches shall be excavated to the dimensions and grades required by

the Plans or as directed by the Engineer. A minimum of 150 mm bedding layer of
granular backfill material shall be placed and compacted at the bottom of the
trench for its full width and length.

Subdrainage pipe of the type and size specified shall be embedded firmly
in the bedding material.

Perforated pipe shall normally, be placed with the perforations down and
the pipe sections shall be joined securely with the appropriate coupling fittings or
bands.

Non-perforated pipe shall be laid with the bell end upgrade and with open
joints wrapped with suitable material to permit entry of water, or unwrapped as
may be specified. Upgrade end sections of all subdrainage pipe installations shall
be closed with suitable plugs to prevent entry of soil materials.

After the pipe installation has been inspected and approved, granular
backfill material shall be placed to a height of 300 mm above the top of pipe.
Care shall be taken not to displace the pipe or the covering at open joints. The
remainder of the granular backfill material shall then be placed and compacted in
150 mm maximum layers to the required height. Any remaining portion of trench
above the granular backfill shall be filled with either granular or impervious
material, as may be specified, and thoroughly compacted.

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501.3.2 Underdrain Outlets

Trenches for underdrain outlets shall be excavated to the width and depth
shown on the Plans or as otherwise directed. Pipes shall be laid in the trench
with all ends firmly joined by the applicable methods and means. After inspection
and approval of the pipe installation, the trench shall be backfilled in accordance
with Item 103, Structure Excavation.

501.3.3 Blind Drain

Trenches for blind drains shall be excavated to the width and depth shown
on the Plans. The trench shall be filled with granular backfill material to the depth
required by the Plans. Any remaining upper portion of trench shall be filled with
either granular or impervious material in accordance with Item 103, Structure
Excavation.

501.4 Method of Measurement

Underdrains and outlets shall be measured by the linear meter for pipe of
the type and size specified. Blind drains shall be measured by the linear meter
including all excavation and backfill materials required.

Granular backfill filter material, when specified in the Contract as a pay

item shall be measured in place by the cubic meter, completed and accepted.
Cross-sectional measurements will not exceed the net dimensions shown on the
Plans or as directed by the Engineer.

Excavation for underdrain pipe will be measured and paid for as provided
in Item 103, Structure Excavation.

501.5 Basis of Payment

The accepted quantities determined as provided in Section 501.4, Method

of Measurement, shall be paid for at the contract unit prices.

Payment will be made under:

Payment Item Number Description Unit of Measurement

501 (1) Underdrain - mm Linear Meter

501 (2) Blind drain Linear Meter

501 (3) Granular Backfill

filter material for underdrains Cubic Meter

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ITEM 502 – MANHOLES, INLETS AND CATCH BASINS

502.1 Description

This item shall consist of the construction, reconstruction or adjustment of

manholes, inlets and catch basins in accordance with this Specification and in
reasonably close conformity with the lines and grades shown on the Plans or as
established by the Engineer.

502.2 Material Requirements

Concrete for these structures shall meet the requirements of Item 405,
Structural Concrete. Other materials shall meet the following specifications:

Corrugated Metal Units – The units shall conform to Plan dimensions and
the metal to AASHTO M 36. Bituminous coating, when specified, shall conform to
ASTM D 1187, Asphalt-base Emulsion for use as Protective Coating for Metal.

Sewer and manhole brick

(Made from clay or shale) AASHTO M 91

Building brick (Solid masonry units made

from clay or shale) AASHTO M 114

Joint Mortar- Unless otherwise indicated on the Plans, joints mortar shall
be composed of one part Portland Cement and two parts fine aggregate by
volume to which hydrated lime has been added in an amount equal to 10 percent
of the cement by weight. All materials for mortar shall meet the requirements of
Item 405, Structural Concrete.

Frames, Gratings, Covers and Ladder Rungs – Metal units shall conform
to the plan dimensions and to the following specification requirements for the
designated materials.

Metal gratings and covers which are to rest on frames shall bear on them
evenly. They shall be assembled before shipment and so marked that the same
pieces may be reassembled readily in the same position when installed.
Inaccuracy of bearings shall be corrected by machining, if necessary. A frame
and a grating or cover to be used with it shall constitute one pair.

All castings shall be uniformly coated with asphalt-based emulsion

meeting the requirements of ASTM D 1187, Asphalt-base Emulsion for use as
Protective Coating for Metal.

Samples of the material in casting shall be taken during the casting of the

35
units and shall be separate casting poured from the same material as the casting
they represent.

Gray iron casting AASHTO M 105

Mild to medium-strength carbon steel castings

for general application AASHTO M 103

Structural steel AASHTO M 183

Galvanizing, where specified for these units,

shall conform to the requirements of AASHTO M 111

Reinforcing Steel AASHTO M 31

Pre-cast Concrete Units – These units shall be cast in substantial

permanent steel forms. Structural concrete used shall attain a minimum 28-day
compressive strength of 20.682 MPa (3000 psi). The pre-cast units shall be
cured in accordance with AASHTO M 171. Water absorption of individual cores
taken from such units shall not exceed 7 percent. Additional reinforcement shall
be provided as necessary to provide for handling of the pre-cast units.

A sufficient number of cylinders shall be cast from the concrete for each
unit permit compression tests at 7, 14 and 28 days, and to allow for at least 3
cylinders for each test. If the strength requirement is met at 7 or 14 days, the
units shall be certified for use 14 days from the date of casting. If the strength is
not met at 28 days, all units made from that batch or load will be rejected.

Cracks in units, honeycombed or patched areas in excess of 2,000 square

millimeters, excessive water absorption and failure to meet strength requirements
shall be the causes for rejection. Pre-cast reinforced concrete manhole risers and
tops shall conform to the requirements of AASHTO M 199.

The plants will be inspected periodically for compliance with specified

manufacturing methods, and material samples will be obtained for laboratory
testing for compliance with material quality requirements. This may be the basis
for acceptance of manufacturing lots as the quality.

All materials shall be subjected to inspection for acceptance as to

condition at the latest practicable time the Engineer has the opportunity to check
for compliance prior to or during incorporation of materials into the work.

502.3 Construction Requirements

Concrete construction shall conform to the requirements for Item 405,

Structural Concrete.

36
 Metal frames shall be set in full mortar bed. Pipe sections shall be flushed
on the inside of the structure wall and projected outside sufficiently for proper
connection with next pipe section. Masonry shall fit neatly and tightly around the
pipe.

When grade adjustment or existing structures is specified, the frames,

covers and gratings shall be removed and the walls reconstructed as required.
The cleaned frames shall be reset at the required elevation. Upon completion,
each structure shall be cleaned of any accumulation of silt, debris, or foreign
matter of any kind and shall be kept clear of such accumulation until final
acceptance of the work.

Excavation and backfill shall be done in accordance with Item 103,

Structure Excavation.

502.4 Method of Measurement

Standard manholes, inlets and catch basins, both new and reconstructed
as applicable, will be measured by the unit. Any additional concrete, reinforcing
steel, or masonry required for authorized increases in heights of structures paid
of under this Item and in excess of the standard height shown on the Plans will
be measured and paid for under Item 405, Structural Concrete and Item 404,
Reinforcing Steel, as applicable. Structures noted on the Plans as “junction
boxes” will be measured for payment as manholes.

The number of concrete covers, pairs of metal frames and gratings, and
pairs of metal frames and covers will be measured as acceptably completed.

The number of existing manholes, inlets and catch basins adjusted as

directed will be measured as acceptably completed.

502.5 Basis of Payment

The accepted quantities, determined as provided in Section 502.4, Method

of Measurement of the Pay Items in the Bill of Quantities will be paid for at the
contract unit prices, which shall constitute full compensation for furnishing and
placing all materials and for all labor, equipment, tools and incidentals necessary
to complete the Item.

Excavation and backfill will be measured and paid for as provided in Item
103, Structure Excavation.

37
 Payment will be made under:

Pay Item Number Description Unit of Measurement

502 (1) Manholes Each

502 (2) Inlets, type Each

502 (3) Catch basins Each

502 (4) Concrete covers Each

502 (5) Metal frames and gratings, type Pair

502 (6) Metal frames and covers Pair

502 (7) Adjusting manholes Each

502 (8) Adjusting inlets Each

502 (9) Adjusting catch basin Each

ITEM 503 – DRAINAGE STEEL GRATING WITH FRAME

503.1 Description

This item shall consist of furnishing all materials, tools, and equipment
including labor required in undertaking the proper application of steel grating with
frame as shown on the plans and in accordance with this specification.

503.2 Classes and Uses of Road Grates and Frames

Classes of grates that are commonly use in drainage work are sump,
trench and box.

Sump grates shall be used to create a trafficable ground level entry area
for surface rainwater to flow into the underground stormwater drainage system.
Sump grates shall be used in paved or grassed areas that are graded to direct
the surface water to a single pit or to a series of pits. Sump grates shall be plain
or hinged.

38
 Trench grates shall be used to collect surface rainwater run off from areas
that cannot be graded to direct flow into a single pit.

Box grates or road drainage shall be used to transfer road surface storm
water into an underground drainage system. Normally used in conjunction with
kerb entry, the addition of the grate significantly increases the hydraulic capacity
of the inlet, particularly on steep slopes.

503.3 Strength Classifications and the Loading Conditions for Sump,

Trench and Box grates

Class A – Test Load 10kN

For locations trafficked only by pedestrians, wheelchairs and cyclists –

inaccessible to motor vehicles by virtue of barriers, narrow passages or
stepped or unpaved approaches.

Class B – Test Load 80kN

For locations normally trafficked by pedestrians and slow moving

passenger cars or light agricultural tractors. These locations include areas
accessible to infrequent slow moving heavy trucks. Typical locations
include footpaths, ground level and multistoried car parks, suburban
driveways and back yards.

Class C – Test Load 150kN

For locations trafficked by slow moving fully laden trucks such as

pedestrians, malls and industrial or commercial areas.

Class D – Test Load 210kN

For locations trafficked by fast moving fully laden trucks and forklifts with
wheel loads to 5.0T. This includes all public roads from residential to
freeway.

Class E, F or G – Test Load 400kN, 600kN or 900kN

For locations subject to vehicles such as large forklifts, earthmoving or

container handling equipment and aircraft. Typical locations include
wharves, container storage areas, heavy industry or construction sites and
domestic or international airports.

All loading conditions specified above are applicable to the three classes of
grates depending on their specific uses and locations.

39
503.4 Materials Requirement

503.4.1 Steel Grating

The steel grating shall be made of fabricated mild steel provided with hot
dip galvanized in accordance with ASTM A153/AASHTO M 232 for superior
corrosion protection. Steel grating shall be machine-made grating comprised of
steel flat bars standing on edge equispaced from each other. To prevent them
from falling over and to provide restraint in buckling, a twisted cross rod (6mm) is
forge-welded1 into the top of the flat bars.

503.4.2 Steel Frame

The steel frame clear openings of drainage grates shall be 15mm larger
than nominal sizes of industry standard sized pits. These pits increase in size in
increments of 150mm. This shall be done to allow frames to be placed over
standard panel formwork and cast in while pouring the pit walls, to speeds up
installation and ensure the frame is fully embedded in the concrete.

503.4.3 Drainage Grate Sizes

The drainage grates shall be identified by their internal clear opening

dimensions of the frame. For square and rectangular grates, the normal
convention shall be the width x length. Metal units shall conform to the approved
plan dimensions and specifications requirement for the designated materials.

Grates shall consist of 25mm to 65mm x 3mm, 4.5mm or 5mm thick flat
bars with length of not more than 6.1m spaced at 30mm o.c. with 6mm twisted
rod spaced at 100mm o.c.. Angular frame (L 75mm x 75mm x 9mm thick) shall
be coated with hot dipped galvanized for superior corrosion protection finish and
extended life. If required, I-Beam support shall be provided in the grates in
accordance with the approved plan. It shall also conform to the requirements of
ASTM A 153 or its equivalents AASHTO M 232.

503.4.4 The metal unit shall conform to ASTM A 36 / AASHTO M 183.

Dimension
Tolerances: Thickness = ± 0.20mm
Width = ± 0.80mm
Length = + 50mm/NIL mm
Straightness = 6mm in each 1.5m length

1
Forge-welding is a process of metal fusion using a combination of high temperature and high pressure.

40
503.4.5 Joint Mortar

Unless otherwise indicated on the Plans, joint mortar shall be composed

of one part Portland Cement and two parts fine aggregate by volume to which
hydrated lime has been added in an amount equal to 10 percent of the cement
by weight. All materials for mortar shall meet the requirements of Item 405,
Structural Concrete. Structural concrete used shall attain a minimum 28-day
compressive strength of 20.682 MPa (3000 psi).

503.5 Construction Requirements

Concrete construction shall conform to the requirements for Item 405,

Structural Concrete.

Metal gratings which are to rest on frames shall bear on them evenly. They
shall be assembled before shipment and so marked that the same pieces may be
reassembled readily in the same position when installed. Inaccuracy of bearings
shall be corrected by machining, if necessary. The steel grating and its
corresponding frame shall constitute one pair.

When grade adjustment or existing drainage grates is specified, the

frames and steel gratings shall be removed and the walls shall be reconstructed
as required. The cleaned frames shall be reset at the required elevation. Upon
completion, each drainage grates shall be cleaned of any accumulations of silt,
debris, or foreign matter of any kind and shall be kept clear of such accumulation
until final acceptance of the work.

Excavation and backfill shall be done in accordance with Item 102,

Excavation.

503.6 Acceptance Requirement

A sufficient number of cylinders for concrete construction shall be cast

from the concrete for each unit for compression tests at 7, 14 and 28 days, and
to allow for at least 3 cylinders for each test. If the strength requirement is met at
7 or 14 days, the units shall be certified for use 14 days from the date of casting.
If the strength is not met at 28 days, all units made from that batch or load will be
rejected.

The steel grating plants will be inspected periodically for compliance with
specified manufacturing and fabricating methods and bars samples will be
obtained for laboratory testing for compliance with material quality requirements.

All draining grates materials shall be subjected to inspection for

acceptance as to condition at the latest practicable time the Engineer has the

41
opportunity to check for compliance prior to or during incorporation of materials
into the work.

503.7 Method of Measurement

The quantity to be measured and paid for will be the number of pairs of
metal frames and gratings completed and accepted. Concrete and reinforcing
steel (AASHTO M 31) will be measured and paid for under Item 405, Structural
Concrete and Item 404, Reinforcing Steel, respectively.

Excavation and backfill will be measured and paid for as provided in Item
102, Excavation.

503.8 Basis of Payment

The accepted quantities, determined as provided in Section 503.7, Method

of Measurement of the Pay Items in the Bill of Quantities will be paid for at the
contract unit prices, which shall constitute full compensation for furnishing and
placing all materials and for all labor, equipment, tools and incidentals necessary
to complete the item.

Payment will be made under:

Pay Item No. Description Unit Of Measurement

503 Metal frames and grating Set

ITEM 504 - CLEANING AND RECONDITIONING EXISTING DRAINAGE

STRUCTURES

504.1 Description

This item shall consist of cleaning and reconditioning existing pipes and
appurtenant structures in reasonably close conformity with this Specification and
as shown on the Plans.

504.2 Material Requirements

Materials used for repair or replacement under the various Pay Items shall
conform the requirements of the applicable Items of this Specification.

42
504.3 Construction Requirements

Pipe Removed and Cleaned – The pipe shall be carefully removed and
cleaned of foreign material both within the barrel and at the jointed ends.

Pipe Cleaned in Place – All foreign materials within the barrel shall be
removed and disposed off by methods which will prevent damage to the pipe.

If approved by the Engineer, all or part of the pipe designated to be

cleaned in place may be removed, cleaned, and relaid in accordance with the
applicable Items. In such cases, the Contractor shall furnish all materials required
to replace damaged pipes and joints, perform all excavation and backfill, and re-
lay the pipe, all at the contract bid price for this Item.

Re-laying or Stockpiling Salvaged Pipe - Relaying of pipe selected by the

Engineer to be removed and cleaned shall be done as shown on the Plans, in
accordance with the appropriate Item for the kind of pipe involved. The
Contractor shall furnish all jointing materials and shall replace the pipe broken by
him, in sufficient lengths to complete the designated length to be relaid without
added compensation. Salvaged pipe to be stockpiled shall be placed as shown
on the Plans and as directed by the Engineer. No pipe which has sustained
structural damage shall be placed in stockpiles. The Contractor shall dispose off
such damaged pipes at an approved locations.

Reconditioning Drainage Structures – Structures such as manholes, inlets,

and the likes, designated on the Plans or as directed by the Engineer to be
reconditioned shall have all debris removed, leaks repaired, missing or broken
metalwork replaced, and each structure left in operating condition.

504.4 Method of Measurement

Measurement will be made by the linear meter of pipe acceptably cleaned,

removed, re-laid or stockpile as designated in the Bill of Quantities, irrespective
of the kind or size involved.

Pipe removed, cleaned, and re-laid will be measured in their final position.

Pipe removed, cleaned, and stockpiled will be measured by totaling the

nominal laying lengths of all pipe units acceptably removed, cleaned, and placed
in the stockpile.

Pipe cleaned in place will be measured along the flow line of the pipe line
acceptably cleaned a directed.

Measurement of drainage structures reconditioned will be made by actual

count of the total number of units of each type acceptably completed.

43
504.5 Basis of Payment

The quantities as provided in Section 504.4, Method of Measurement,

shall be paid for at the contract price bid per unit of measurement for each of the
Pay Items listed below that appear in the Bid Schedule, which price and payment
shall be full compensation for the work of this item except excavation and backfill
which is paid for under Item 103, Structure Excavation.

Excavation and backfill necessary for pipe removal operations shall be

done as part of the work of this Item.

The Contractor shall remove and replace without added compensation

any pipe damaged by this operations and which cannot be acceptably repaired in
place.

Payment will be made under:

Pay Item Number Description Unit of Measurement

504 (1) Removing, cleaning, stockpiling

Salvaged culvert pipe Linear Meter

504 (2) Removing, cleaning, and re-laying

Salvaged culvert pipe Linear Meter

504 (3) Cleaning culvert pipe in place Linear Meter

504 (4) Reconditioning drainage structures Each

If more than one type of drainage structure is described for an Item in the
Bid Schedule, letter suffixes shall be added to the item Number differentiate
between such structures.

If no Pay Item from the list above appears in Bid Schedule, the pipe
removed will be considered as included in the work of Item 101, Removal of
Structures and Obstructions.

ITEM 505 – RIPRAP AND GROUTED RIPRAP

505.1 Description

This Item shall consist of the furnishing and placing of riprap with or
without grout as the case may be, with or without filter backing, furnished and

44
constructed in accordance with this Specification and to the lines and grades and
dimensions shown on the Plans.

505.2 Material Requirements

505.2.1 Stones

Stones for riprap shall consist of rock as nearly as rectangular in section

as is practical, except that riprap of Class A may consist of round natural stones.
The stones shall be sound, tough, durable, dense, resistant to the action of air
and water, and suitable in all respects for the purpose intended.

Stones for riprap shall be one of the following classes as shown on the
Plans or determined by the Engineer.

Class A - Stones ranging from a minimum of 15kg to a

maximum of 25kg with at least 50 percent of the
stones weighing more than 20kg

Class B - Stones ranging from minimum of 30kg to a

maximum of 70kg with at least 50 percent of the
stones weighing more than 50kg

Class C - Stones ranging from minimum of 60kg to a

maximum of 100kg with at least 50 percent of the
stones weighing more than 80kg

Class D - Stones ranging from minimum of 100kg to a

maximum of 200kg with at least 50 percent of the
stones weighing more than 150kg
Sound pieces of broken concrete obtained from the removal of bridges,
culverts and other structures may be substituted for stone with the approval of
the Engineer.

505.2.2 Filter Materials

When required, the riprap shall be placed on a filter layer to prevent fine
embankment materials to be washed out through the voids of the face stones.
The grading of the filter material shall be as specified on the Plans, or in the
Special Provisions. If not so specified, it will be required that D 15 of the filter is at
least 4 times the size D85 for the embankment material, where D 15 percent and
85 percent, respectively, passing (by mass) in a grain size analysis. Fine
aggregate passing grading requirements for Item 405, Structural Concrete, will
satisfy foregoing requirements.

45
505.2.3 Mortar

Mortar for grouted riprap shall consist of sand, cement and water
conforming to the requirements given under Item 405, Structural Concrete, mixed
in the proportion of one part cement to three parts sand by volume, and sufficient
water to obtain the required consistency.

The horizontal and vertical contact surface between stones shall be

embedded by cement mortar having a minimum thickness of 20 mm. Sufficient
mortar shall be used to completely fill all voids leaving the face of the stones
exposed.

505.3 Construction Requirements

505.3.1 Excavation

The bed for riprap shall be excavated to the required depths and properly
compacted, trimmed and shaped.

The riprap shall be founded in a toe trench dug below the depth of scour
as shown on the Plans or as ordered by the Engineer. The toe trench shall be
filled with stone of the same class as that specified for the riprap, unless
otherwise specified.

505.3.2 Placing

Stones placed below the water line shall be distributed so that the
minimum thickness of the riprap is not less than that specified.

Stones above the water line shall be placed by hand or individually by

machines. They shall be laid with close, broken joints and shall be firmly bedded
into the slope and against the adjoining stones. Each stone shall be laid with its
longest axis perpendicular to the slope in close contact with each adjacent stone.
The riprap shall be thoroughly rammed into place as construction progresses and
the finished surface shall present an even, tight surface. Interstices between
stones shall be filled with small broken fragments firmly rammed into place.

Unless otherwise provided, riprap shall have the following minimum

thickness, measured perpendicular to the slope:

Class A – 300 mm
Class B – 500 mm
Class C – 600 mm
Class D – 800 mm

46
 The surface of riprap shall not vary from the theoretical surface by more
than 100 mm at any point.

505.3.3 Grouting

When grouted riprap is specified, stones shall be placed by hand, or

individually by machine as specified for riprap placed above the water line. The
spaces between the stones shall then be filled with cement mortar throughout the
thickness of the riprap as specified in Subsection 504.2.3, mortar. Sufficient
mortar shall be used to completely fill all voids, except that the face surface of the
stones shall be left exposed.

Grout shall be placed from bottom to top of the surface swept with a stiff
broom. After grouting is completed, the surface shall be cured as specified in
Item 405, Structural Concrete for a period of at least three days.

The stones shall also be laid in a manner that the vertical and horizontal
alignments of the exposed face shall, as possible be maintained in a straight line.

505.3.4 Weepholes

All walls and abutments shall be provided with weepholes. Unless

otherwise shown on the Plans or directed by the Engineer, the weepholes shall
be placed horizontally at the lowest points where free outlets for water can be
obtained and shall be spaced at not more than 2 m center to center in a
staggered manner . The length of the weepholes shall not be less than the
thickness of the walls of the abutment and shall be at least 50 mm diameter PVC
or other pipe materials accepted by the Engineer. Weepholes must be provided
with filter bags as specified in special provision or as directed by the Engineer,
and shall be incidental to Pay Item 505.

505.4 Method of Measurement

The quantities to be measured for payment shall be the number of cubic

meters of riprap or grouted riprap, as the case may be, including stones placed in
the toe trench laid in position and accepted.

Filter layer of granular material, when required, shall be measured

separately by the cubic meter in place and accepted.

The computation of the quantities will be based on the volume within the
limiting dimensions designated on the Plans or as determined by the Engineer.

47
505.5 Basis of Payment

The quantities measured as provided under Subsection 505.4 shall be

paid for at the contract unit price, respectively, for each of the Pay Items listed
below and shown in the Bid Schedule, which price and payment shall be full
compensation for excavation and preparation of the bed, for furnishing and
placing all materials including backfill and all additional fill to bring the riprap bed
up to the lines, grades and dimensions shown on the plans, and all labor,
equipment, tools and incidentals necessary to complete the Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

505 (1) Riprap, Class A Cubic Meter

505 (2) Riprap, Class B Cubic Meter

505 (3) Riprap, Class C Cubic Meter

505 (4) Riprap, Class D Cubic Meter

505 (5) Grouted Riprap, Class A Cubic Meter

505 (6) Grouted Riprap, Class B Cubic Meter

505 (7) Grouted Riprap, Class C Cubic Meter

505 (8) Grouted Riprap, Class D Cubic Meter

505 (9) Filter layer of granular material Cubic Meter

ITEM 506 – STONE MASONRY

506.1 Description

This Item shall consist of stone masonry in minor structures, in headwalls

for culverts, in retaining walls at the toes of slopes, and at other places called for
on the Plans, constructed on the prepared foundation bed, in accordance with
this Specification and in conformity with the lines, grades, sections, and
dimensions shown on the Plans or as ordered in writing by the Engineer.

48
506.2 Material Requirements

506.2.1 Stone

The stone shall be clean, hard, and durable and shall be subject to the
Engineer’s approval. Adobe stone shall not be used unless otherwise specified.

Sizes and Shapes – Unless other sizes are shown on the Plans, stones
have a thickness of not less than 150 mm, and widths of not less than one and
one-half times their respective thickness, and lengths of not less than one and
one half times their respective widths. Each stone shall be of good shape and be
free of depressions and projections that might weaken or prevent it from being
properly bedded.

Dressing – The stone shall be dressed to remove any thin or weak

portions. Face stones shall be dressed to provide bed and joint lines that do not
vary more than 20 mm from the true lines and to ensure the meeting of bed and
joint lines without the rounding of corners of the stones in excess of 30 mm in
radius. Bed surfaces of the face stones shall be approximately normal to the
face of the stones for about 80 mm and from this point may depart from a normal
plane not to exceed 50 mm in 300 mm.

Finish for Exposed Faces – Face stones shall be pitched to the line along
the beds and joints. The maximum projection of rock faces beyond the pitch lines
shall not be more than 50 mm.

506.2.2 Mortar

Cement, fine aggregate, and water shall conform to the respective

requirements for those materials as specified under Item 405, Structural
Concrete, except as to the grading of fine aggregate which shall all pass the 2.36
mm (No. 8) sieve, not less than 15 nor more than 40 percent shall pass the 0.3
mm (No. 50 ) sieve, and not more than 10 percent shall pass the 0.15 mm
(No.100) sieve.

The mortar for the masonry shall be composed of one part of Portland
Cement and two parts of fine aggregate by volume and sufficient water to make
the mortar of such consistency that it can be handled easily and spread with a
trowel. Mortar shall be mixed only in those quantities required for immediate use.
Unless an approved mortar mixing machine is used, the fine aggregate and
cement shall be mixed dry in a tight box until the mixture assumes a uniform
color, after which, water shall be added as the mixing continues until the mortar
attains the proper consistency. Mortar that is not used within 90 minutes after the
water has been added shall be discarded. Retempering of mortar will not be
permitted.

49
506.3 Construction Requirement

506.3.1 Selection and Placing

When the masonry is to be placed on a prepared foundation bed, the bed

shall be firm and normal to, or in steps normal to, the face of the wall, and shall
have been approved by the Engineer before any stone is placed.

Care shall be taken to prevent the bunching of small stone or stones of the
same size. Large stones shall be used in the corners.

All stones shall be cleaned thoroughly and wetted immediately before

being set, and the bed which is to receive them shall be cleaned and moistened
before the mortar is spread. They shall be laid with their longest faces horizontal
in full beds of mortar, and the joints shall be flushed with mortar.

The exposed faces of individual stones shall be parallel to the faces of the
walls in which the stones are set.

The stones shall be so handled as not to jar displace the stones already
set. Suitable equipment shall be provided for setting stones larger than those that
can be handled by two men. The rolling or turning of stones on the walls will not
be permitted. If a stone is loosened after the mortar has taken initial set, it shall
be removed, the mortar cleaned off, and the stone relaid with fresh mortar.

506.3.2 Bed and Joints

Beds for face stones may vary from 20 mm to 50 mm in thickness. They

shall not extend an unbroken line through more than 5 stones. Joints may vary
from 20 mm to 50 mm in thickness. They shall not extend in an unbroken line
through more than two stones. They may be at angles with the vertical from 0 0 to
450. Face stone shall bond at least 150 mm longitudinally and 50 mm vertically.
At no place shall corners of four stones be adjacent to each other.

Cross beds for vertical faced walls shall be level, and for battered walls
may vary from level to normal to the batter line of the face of the wall.

506.3.3 Headers

Headers shall be distributed uniformly throughout the walls of the

structures so as to form at least one-fifth of the exposed faces. They shall be of
such lengths as to extend from the front face of the wall into the backing of at
least 300 mm. When a wall is 450 mm or less in thickness, the headers shall
extend entirely from front to back face.

50
506.3.4 Backing.

Backing shall be built mostly of large stones as shown in the approved

Plans or as directed by the Engineer. The individual stones composing the
backing and hearting shall be well bonded with the stones in the face wall and
with each other. All openings and interstices in the backing shall be filled
completely with mortar or with spalls surrounded completely by mortar.

506.3.5 Pointing

Both bed and vertical joints shall be finished as shown on the Plans or as
directed by the Engineer. The mortar in joints on top of surface of masonry shall
be crowned slightly at the center of the masonry to provide drainage.

506.3.6 Coping

Copings, if called for, shall be finished as shown on the Plans. Where

copings are not called for, the top of the wall shall be finished with stones wide
enough to cover the top of the wall from 450 mm to 1000 mm in length, and of
random heights, with a minimum height of 150 mm. Stone shall be laid in such a
manner that the top course is an integral part of the wall. The tops of top course
of stone shall be pitched to line, in both vertical and horizontal planes.

506.3.7 Weepholes

It shall conform to the requirements of Item 504, Riprap and Grouted

Riprap under Subsection 504.3.4, Weepholes.

506.3.8 Cleaning Exposed Faces

Immediately after being laid, and while the mortar is fresh, all face stones
shall be thoroughly cleaned of mortar stains and shall be kept clean until the
work is completed.

506.3.9 Curing

In hot or dry weather, the masonry shall be satisfactory protected from the
sun and shall be kept wet for a period of at least three days after completion.

506.4 Method of Measurement

The quantity to be paid for shall be the number of cubic meters of stone
masonry complete in place and accepted. Projections extending beyond the
faces of the walls shall not be included. In computing the quantity for payment,
the dimensions used shall be those shown on the Plans or ordered in writing by

51
the Engineer. No deductions shall be made for weepholes, drain pipes or other
openings of less than one square meter in area.

506.5 Basis of Payment

The quantity of masonry, determined as provided in Section 506.4,

Method of Measurement, shall be paid for at the contract unit price per cubic
meter for Stone Masonry, which price and payment shall be full compensation for
furnishing and placing all materials, including mortar for masonry, for all
necessary excavations, and for all labor, equipment, tools and incidentals
necessary to complete the Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

506 Stone Masonry Cubic Meter

ITEM 507 – RUBBLE CONCRETE

507.1 Description

This item shall consist of the construction of rubble concrete in

accordance with this specification and in conformity with the lines, grades, slopes
and dimensions shown in the Plans or established by the Engineer.

507.2 Material Requirements

507.2.1 Stone

The stone shall be cleaned, hard, and durable and shall be subject to the
Engineer’s approval. Adobe stone shall not be used unless otherwise specified.
Stones to be used shall be more than 0.015 cubic metre in volume and not less
than 75 percent of the total volume of rock embankment and shall consist of
stones 0.03 cubic metre in volume as described in Item 506.2. Stones obtained
from excavation performed under this contract may be used.

507.2.2 Concrete Class “B”

Concrete shall be Class “B” in accordance with Item 405, Structural

Concrete.

52
507.3 Construction Requirements

507.3.1 Preparation of Foundation Bed

The foundation bed shall be excavated to the lines and grades as shown
in the plans as directed by the Engineer, and shall be thoroughly compacted in
accordance with Item 104.3.3.

507.3.2 Falsework and Formwork Construction

Falsework/formwork shall be constructed so as to withstand the stresses

imposed.

Formwork used shall be constructed with sufficient strength, rigidity and

shape as to leave the finished works true to the dimensions shown on the Plans
and with the surface finished as specified.

The inside surface of the forms shall be cleaned of all dirt, water and
foreign materials. Forms shall be thoroughly coated with form oil prior to use. The
form oil shall be commercial quality form oil or other approved coating which will
permit the ready release of forms and will not discolor the concrete.

507.3.3 Placing

One layer of concrete Class “B” shall be placed at the prepared bed prior
to placing of stones. Clearance between stones shall not be less than 2-1/2
inches or the maximum size of concrete aggregate for Class “B”.

Concrete Class “B” shall be placed after each layer of stone and shall be
thoroughly consolidated by means of a vibrator inserted in each layer of
concrete. In no case shall the vibrator be operated longer than 10 seconds in any
location.

After removal of forms, any cavities, voids and honeycomb spots shall be
filled up with mortar composed of one part cement and two parts sand.

All debris and refuse resulting from work shall be removed and the site
left in a neat and presentable condition.

507.3.4 Weepholes

It shall conform to the requirements of Item 504, Riprap and Grouted

Riprap under Subsection 504.3.4, Weepholes.

53
507.4 Method of Measurement

The quantity to be paid for shall be the number of cubic meters of rubble
concrete complete in place and accepted. In computing the quantity of payment
the dimension used shall be those shown on the plans or ordered in writing by
the Engineer. No reduction shall be made for weepholes.

507.5 Basis of Payment

The quantity of rubble concrete determined as provided in the preceding

section 507.4, Method of Measurement, shall be paid for at the contract unit price
per cubic meter for rubble concrete, which price and payment shall be full
compensation for the preparation of the bed, furnishing, necessary excavations,
falsework, and for all labor, equipment, tools and incidentals necessary to
complete the Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

507 Rubble Concrete Cubic Meter

ITEM 508 – HAND-LAID ROCK EMBANKMENT

508.1 Description

This Item shall consist of hand-laid rock embankment, as designated in

the Bid Schedule, constructed in accordance with this Specification and in
conformity with the lines and grades shown on the Plans or established by the
Engineer.

508.2 Material Requirements

Stones shall be sound and durable and furnished in a well-balanced

ranged of sizes meeting the requirements herein.

Unless otherwise provided by the Plans or Special provisions, all stones shall be
more than 0.015 cubic meter in volume and not less than 75 percent of the total
volume of rock embankment and shall consist of stones 0.03 cubic meter in

54
volume. Stones obtained from excavation performed under this contract may be
used. Adobe stone shall not be used, unless otherwise specified.

508.3 Construction Requirements

Sufficient excavation shall be made to expose a foundation bed that is

satisfactory to the Engineer. The stones shall be founded on this bed and laid to
the lines and dimensions required.

Stones shall be laid flat and securely placed with broken joint lines. The
larger stones shall generally be located in the lower part of the structure and
voids shall be eliminated to the extent possible. Spalls smaller than the minimum
stone size specified in Section 506.2, Material Requirements, shall be used to
check the larger stones solidly in position and to substantially fill voids between
the major stones as laid in the embankment. The exposed face of the rock mass
shall be reasonably uniform, with no projections of more than 150 mm, beyond
the neat lines shown on the Plans or as directed by the Engineer.

Backfill adjacent to the hand-laid rock embankment shall be filled entirely

with acceptable material coming from excavation items and compacted.

508.4 Method of Measurement

The quantity to be paid for will be the number of cubic meter of hand-laid
rock embankment measured in place, completed and accepted.

508.5 Basis of Payment

The quantity determined, as provided in Section 508.4, Method of

Measurement , will be paid for at the contract price per cubic meter for Hand-
Laid Rock Embankment, which price and payment shall constitute full
compensation for furnishing, selecting, and transporting stones, for placing
stones by hand, for backfilling, and for all labor, equipment, tools and incidentals
necessary to complete the Item including foundation excavation.

Payment will be made under:

Pay Item Number Description Unit of Measurement

508 Hand-Laid Rock Embankment Cubic Meter

55
ITEM 509 – SHEET PILES

509.1 Description

This shall consist of furnishing, driving and cutting off of sheet piling
covered by this Specification.

509.2 Material Requirements

509.2.1 Timber Sheet Piles

The timber, unless otherwise definitely noted on the Plans or in the

Special Provisions, may consist of any species which will satisfactorily stand
driving. It shall be sawn or hewn with square corners and shall be free from worm
holes, loose knots, wing shakes, decay or unsound portions or other defects
which might impair its strength or tightness.

509.2.2 Concrete Sheet Piles

Concrete, reinforcement, and manufacture of concrete sheet piles shall

conform to the requirements of Item 400, Piling, Subsection 400.2.3, Concrete
Piles.

509.2.3 Steel Sheet Piles

Steel sheet piles shall be of the type, weight and Section Modulus
indicated on the Plans or Special Provisions, and shall conform to the
requirement of Item 400, Piling, Subsection 400.2.7, Sheet Piles, Painting shall
conform to the requirements for Item 411, Paint, Subsection 411.6.2, Painting
Structural Steel.

509.3 Construction Requirements

Sheet piles shall be driven to elevation shown on the Plans or as

directed by the Engineer. Where impractical to drive to plan elevation due to
subsurface conditions, the driving of piles may be stopped at a higher elevation
with the written permission of the Engineer. However, before granting such
permission, the Engineer shall ascertain that the Contractor has adequate
equipment for the required driving and that the piles can be driven to the plan
elevation with the proper use of this equipment.

The top of the piling shall be driven or cut-off to a straight line at the
elevation indicated on the Plans.

The requirements governing the installation of sheet piling shall conform in

general to those governing bearing piles as set forth under Item 400, Piling.

56
509.4 Method of Measurement

Sheet piling will be measured by the linear meter of sheet piling as shown
on the Plans or as directed in writing by the Engineer, complete in place and
accepted. However, measurement of piling which has been delivered to plan
length and cannot be driven according to plan or directed elevation because of
subsurface condition shall be measured as if driven to that elevations.

509.5 Basis of Payment

Payment of steel piles as determined in Section 509.4, Method of

Measurement, shall be made at the contract unit price per linear meter. Such
payment shall be considered full compensation for furnishing all materials, labor,
equipment, tools, paint, bolts, wales and incidentals necessary to complete the
Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

509 (a) Sheet Piles (Timber) Linear Meter

509 (b) Sheet Piles (Steel) Linear Meter

509 (c) Sheet Piles (Concrete) Linear Meter

ITEM 510 – CONCRETE SLOPE PROTECTION

510.1 Description

This Item shall consist of the furnishing and placing of concrete slope
protection including all necessary excavation, a bed course and reinforced
concrete to the required thickness and extent to protect slopes against erosion.
Construction details shall be as shown on the Plans.

510.2 Material Requirements

510.2.1 Bed Course

A bed course, where required, shall be granular material which satisfies

the requirements for Item 200, Aggregate Sub-base, Grading A.

57
510.2.2 Formwork

Formwork, where necessary, shall be as specified in Item 407, Concrete

Structures.

510.2.3 Steel Reinforcement

Steel reinforcement shall be as specified in Item 404, Reinforcing Steel.

510.2.4 Concrete

Concrete shall be Class B as specified in Item 405, Structural Concrete,

unless otherwise specified or required by the Engineer.

510.3 Construction Requirements

510.3.1 Excavation

The ground shall be excavated where necessary in accordance with the

dimensions, lines and grades shown on the Plans.

510.3.2 Bed Course

Where shown on the Plans or ordered by the Engineer, the Contractor

shall provide and lay a bed course, to the depth required, and as specified in
Item 200, Aggregate Subbase Course, compacted at least 100 percent of the
maximum dry density as determined by AASHTO T 180, Method D.

510.3.3 Concrete

The Contractor shall provide and place concrete in accordance with the
requirements of Item 405, Structural Concrete, to the required depths in the
positions and to the grades and elevations shown on the Plans. Unless otherwise
specified, the concrete slabs shall not be greater than 4m by 4m and shall have
between slabs, plain vertical straight joints with no joint filler or sealer.

The toe of the concrete slope protection shall be constructed and

protected a shown on the Plans.

510.3.4 Drainage

Drainage of the bed course or backfill shall be provided as shown on the

Plans or as required by the Engineer.

58
510.4 Method of Measurement

The quantity of granular material in the bed course to be paid for shall be
measured by the cubic meter in-place and accepted as shown on the Plans.

The quantity of concrete to be paid for shall be measured by the cubic

meter in-place and accepted as shown on the Plans.

510.5 Basis of Payment

The accepted quantities as provided in Section 510.4, Method of

Measurement, shall be paid for at the contract unit price according to the Pay
Item in the Bid Schedule which price and payment shall constitute full
compensation for the necessary excavation, for all labor, equipment, tools, all
materials including formwork and reinforcing steel, and incidentals necessary to
complete this Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

510 (1) Bed Course Cubic meter in-place

Granular Material

510 (2) Concrete Cubic meter in-place

ITEM 511 – GABIONS AND MATTRESSES

511.1 Description

This Item shall consist of furnishing, forming wire mesh baskets, and
placing rocks installed at the locations designated, in accordance with this
Specification and in conformity with the lines, grades, dimensions, and
arrangements shown on the Plans or as directed by the Engineer.

511.2 Material Requirements

511.2.1General

Gabions shall be constructed of wire mesh and shall be supplied in

various lengths and heights. A double twisted wire mesh container of variable

59
sizes, uniformly partitioned into internal cells, interconnected with other similar
units, and filled with stones at the project site to form flexible, permeable,
monolithic structures such as retaining walls, sea walls, channel linings,
revetments and weirs for erosion control. The lengths shall be multiples of 2, 3
or 4 times the width of the gabion and heights shall be 0.50 m to 1.00 m or as
shown on the plans. The horizontal width shall not be less than one meter.
Gabion furnished shall be of uniform width.

The width, height and length of the gabion as manufactured shall not differ
more than 5% from the ordered size prior to filling.

Mattresses are double twisted wire mesh container uniformly partitioned

into internal cells with relatively small height in relation to other dimensions,
having smaller mesh openings than the mesh used for gabions. Mattresses are
generally used for riverbank protection and channel linings. The length shall be
3.00 m to 6.00 m, the width shall be 2.00 m and the height shall be 0.17 m, 0.23
m or 0.30 m or as shown on the Plans.

The width and length of the revet mattress as manufactured shall not differ
more than 5%, and the height shall not differ more than 10% from the ordered
size prior to filling.

511.2.2 Wire

The wire used in the manufactured of double-twisted mesh for use in

gabions and mattresses shall conform to the specifications as shown below as
appropriate for the style ordered.

511.2.2.1 Style 1 double-twisted mesh shall be manufactured from zinc-coated

steel wire conforming to Specification ASTM A 641, Class 3 coating,
soft temper.

511.2.2.2 Style 2 double-twisted mesh shall be manufactured from Zn-5A1-MM-

coated steel wire conforming to Specification ASTM A 856/A 856 M,
Class 3 coating, soft temper.

511.2.2.3 Style 3 double-twisted mesh shall be manufactured from the same type
of metallic-coated steel wire as style 1 with an additional PVC coating
extruded into the metallic-coated steel wire. The PVC coating shall
conform to the following requirements:

Test Method

1. Specific Gravity 1.30 to 1.35 D 792

2. Tensile Strength, min 20.6 MPa D 412
3. Modulus of Elasticity, min 18.6 MPa D 412

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 4. Hardness, shore “D” between 50 & D 2240
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5. Brittleness Temp, max 90C (150F) or D 746
lower temp.
6. Resistance to Abrasion, % 12% D 1242
weight loss, max.

The PVC coating shall not show cracks or breaks after the wires are
twisted in the fabrication of the mesh.

511.2.2.4 Style 4 double-twisted mesh shall be manufactured from aluminum-

coated steel wire conforming to Specification ASTM A 809, soft temper.

511.2.3Lacing Wire and Stiffener

Lacing wire and stiffeners shall be made of wire having the same
coating material as the double-twisted wire mesh conforming to
Specification ASTM A 641, A 856/A 856 M or A 809 with a tensile
strength in accordance with subsection 509.2.7.

511.2.4 Fasteners made from zinc-coated steel wire, zinc - 5% aluminum

mischmetal alloy-coated steel wire and aluminum-coated steel shall
conform to specification A 764, Type A, B, or C, Table 2 or Table 3.

511.2.5Gabion and mattresses shall be manufactured with all components

mechanically connected at the production facility with the exception of
the mattresses lid which is produced separately from the base. All
gabions and mattresses shall be supplied in the collapsed form, either
folded and bundled or rolled, for shipping.

511.2.6Dimensions

The minimum size of the galvanized and PVC coated wire to be used in
the fabrication of the gabion and mattresses shall be as follows:

Diameter, mm
Gabion Mattresses
Metallic PVC Metallic PVC
Coated Coated Coated Coated
Body Wire 3.05 2.70 2.20 2.20
Selvedge or Perimeter Wire 3.80 3.40 2.70 2.70
Tying and Connecting Wire 2.20 2.20 2.20 2.20

Diameter Tolerances for Galvanized Wire to be used in the

fabrication of gabion and mattress shall be  .10.

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 The nominal and the minimum thickness of PVC coating shall be
0.50 mm and 0.38 mm, respectively.

511.2.7Mechanical Properties

Tensile Strength – The tensile strength of Zinc-coated wire used in the

fabrication of gabion and mattresses when tested in accordance with Test
Methods ASTM A 370, shall be as follows:

Strength, max, Mpa

Gabion Mattresses
Body Wire 485 515
Selvedge or Perimeter Wire 485 485
Tying and Connecting Wire 515 515

511.2.8 Weight of Coating

The minimum weight of zinc per unit area of uncoated wire surface shall
be in accordance with ASTM A 975 or as follows:

Wire Diameter, mm Class 3 or A Coating, g/m2, ASTM A 641

Over 1.90 to 2.30 220
Over 2.30 to 2.70 230
Over 2.70 to 3.10 240
Over 3.10 to 3.50 260
Over 3.50 to 3.90 270

511.2. 9 Rock Fill

Rock used in the gabions and mattresses shall consist of hard, durable
rock pieces that will not deteriorate when submerged in water or exposed to
severe weather conditions. Rock pieces shall be generally uniformly graded in
sizes ranging from 100 mm to 200 mm. Filled gabions shall have a minimum
density of 1,400 kg/m3. Voids shall be evenly distributed.

No rock size shall exceed 2/3 the mattress depth and at least 85% by
weight of the stone shall have a size greater than 80 mm. No stones shall be
able to pass through the mesh.

The rock shall meet the requirements of AASHTO M 63 except that the
sodium sulphate soundness loss shall not exceed 9% after 5 cycles.

511.2.10 Filter Fabric

Filter cloth shall consist of 70% polypropylene and 30% polyethylene.

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511.3 Construction Requirements

511.3.1Fabrication

1. Gabions and mattresses shall be in the form of rectangular baskets of

the required dimensions and shall be manufactured from wire as
specified in Subsection 509.2.2. Gabions shall be made of steel wire
double twisted forming a uniform hexagonal mesh type 8 x 10 having
a nominal mesh openings of 83 by 114 mm. Mattresses shall be
made of steel wire double twisted forming a uniform hexagonal mesh
type 6 x 8 having a nominal mesh openings of 64 by 83 mm.
Tolerances on the hexagonal, double-twisted wire mesh opening shall
not exceed 10% on the nominal dimension D values, 64 mm for
mattresses and 83 mm for gabions. The edges shall be formed into a
securely connected selvedge adequate to prevent raveling.

Individual basket ties and connections shall be made by using a

quantity of wire not less than 8% of the weight of each basket.

2. When the gabion length exceeds its width, it shall have securely tied
diaphragms connected at all edges to form individual cells of equal
length and width.

Gabions shall be fabricated in such a manner that the sides, ends,

lids and diaphragms can be assembled at the construction site into
rectangular baskets of the specified sizes. Gabions shall be of single
unit construction, base, lids, ends and sides shall be either woven into
a single unit or one edge of these members connected to the base
section of the gabion in such a manner that the strength and flexibility
at the point of connection is at least equal to that of the mesh.

The gabion shall be equally divided by diaphragms, placed at not

more than 1.0 m intervals, and of the same mesh and gauge as the
body of the gabions, into cells the length of which does not exceed
the horizontal width. The gabion shall be furnished with the necessary
diaphragms secured in proper position on the base in such a manner
that no additional tying at this junction will be necessary.

3. Four cross-connecting wires shall be provided in each cell having a

height of one half the width or less, and eight cross-connecting wires
shall be provided in each cell having a height greater than one half
the width.

All perimeter edge of the mesh forming the gabion shall be securely
selvedged so that the joints, by tying the selvedges, have at least the
same strength as the body of the mesh.

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 Selvedge wire used through all the edges (perimeter wire) shall not
be less than 3.80 mm diameter and shall meet the same
specifications as the wire mesh.

511.3.2 Assembly and Construction:

1. Gabions shall be installed in a workmanlike manner. The gabions

shall be placed on a smooth foundation. Final line and grade shall be
approved by the Engineer.

Each gabion unit shall be assembled by binding together all vertical

edges with wire ties on approximately 152 mm (6 inches) spacing or
by a continuous piece of connecting wire stitched around the vertical
edges with a coil every 102 mm ( 4 inches). Empty gabion units shall
be set to line and grade as shown on the Plans or as described by
the Engineer. Wire ties or connecting wires shall be used to join the
units together in the same manner as described above for
assembling. Internal tie wires shall be uniformly spaced and securely
fastened in each cell of the structure.

A standard fence stretcher, chain fall, or iron rod may be used to

stretch the wire baskets and hold alignment.

2. When possible the subgrade of the mattress and gabion shall be

properly compacted to a depth of 150 mm. The Contractor shall
consider the cost of subgrade preparation in the unit prices. Filter
fabric as beds of gabions and mattresses forming the structure shall
be suitably leveled and shall be securely connected along the
complete length of all contact edges by means of the above specified
tying and connecting wire.

3. Before the filling material is placed, the gabions and mattresses shall
be carefully selected for uniformity of size, and the pieces shall be
handplaced to provide a neat appearance as approved by the
Engineer.

The gabions shall be filled with stone carefully placed by hand or

machine to assure alignment and avoid bulges with a minimum voids.
Alternate placing of rock and connection wires shall be performed
until the gabion is filled. After a gabion has been filled, the lid shall be
bent over until it meets the sides and edges. The lid shall then be
secured to the sides, ends and diaphragms with the wire ties or
connecting wire in the manner described for assembling.

The vertical joints of gabions and mattress baskets shall be

staggered as in running bond in brickwork.

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 4. The cells in any row shall be filled in stage so that local deformation
may be avoided. That is at no time shall the cell be filled to a depth
exceeding 30 cm more than the adjoining cell.

5. Filter fabric shall be placed between earth surface and gabion or

mattress structures. Filter fabric shall be rolled out into a flat non-
rutted surface free from sharp objects, weighing down the edges.
Construction equipment shall not be allowed into unprotected fabric.
Jointing is normally affected by overlapping not less than 300 mm,
but it is preferable to joint by sewing or industrial stapling. Joint edges
should be facing downwards to avoid protruding through the surface
material.

511.4 Method of Measurement

The quantities to be paid for shall be the number of cubic meter of

gabions and mattresses and the area of filter cloth completed and accepted.

511.5 Basis of Payment

Quantities determined as provided above shall be paid for at the

appropriate contract unit price per unit of measurement for the Pay Item shown
in the Bid Schedule, which price and payment shall constitute full compensation
for all necessary excavation, subgrade preparation, for furnishing, placing wire
baskets and fill materials and for all labor, equipment accessories, tools, and
incidentals necessary to complete the Item.

Payment will be made under:

Pay Item Number Description Unit of Measurement

511 (1) Gabions Cubic Meter

511 (2) Mattresses Cubic Meter
511 (3) Filter Cloth Square Meter

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