Culverts,Drainage and Protection Works

SECTION 600 – CULVERTS, DRAINAGE AND PROTECTION WORKS

601 SCOPE OF SECTION 2 PART A. CULVERTS AND DRAINAGE 2602 ORDER OF WORKS603 CLASSIFICATION OF EXCAVATION604 EXCAVATION FOR CULVERTS AND DRAINAGE STRUCTURES605 EXCAVATION IN ROCK606 FOUNDATIONS AND ABUTMENTS CAST AGAINST EXCAVATED SURFACES 4607 BACKFILLING FOR CULVERTS AND DRAINAGE STRUCTURES608 PRECAST STEEL REINFORCED CULVERT UNITS609 BEDDING AND LAYING OF CULVERTS 7A Bedding and Laying of Concrete Culverts on In-situ or Imported Fill or Imported Granular Material 7B Bedding and Laying of Concrete Units on a Concrete Bed 7610 JOINTING CONCRETE CULVERTS 7A Rigid JointsB Protective Bituminous Coating and TapingC Culvert Ends611 CONCRETE BEDS, SURROUNDS AND HAUNCHES612 DRAINAGE STRUCTURES613 OUTFALL CHANNELS, DAMS AND SCOUR CHECKS614 CLEANING AND MAINTENANCE615 CONCRETE EDGE KERBS CHANNELLING AND LINING 10A MaterialsB ConstructionC Tolerances and Surface FinishPART B. RIVER TRAINING AND PROTECTION WORK 12

616 BANKS AND DYKES 14617 RIPRAP 14618 IN-SITU OR PRECAST REINFORCED CONCRETE SCOUR PROTECTION 16619 STONE PITCHING 16620 SCOUR CHECKS 17621 PRECAST REINFORCED CONCRETE GRID SLOPE PROTECTION WITH STONE INFILL 17

600-1

601 SCOPE OF SECTION

This section covers the following:

1. excavation and backfilling for culverts and drainage structures,2. provision, installation and repair of Precast Concrete Pipe culverts;3. provision, installation and repair of Concrete Box Culverts;4. construction of drainage structures including pipe culvert inlet and outlet structures, scour

checks, catch pits, lined channels, cascades and the like in in-situ or precast concrete as instructed;

5. construction of drainage protection works.

PART A - CULVERTS AND DRAINAGE

Existing pipe culverts shall be extended or lengths of existing pipe culvert replaced as shown on the drawings and remedial works schedules. All existing culverts shall be cleaned and their inlet and outfall channels shall be reinstated such that existing culverts are free of draining prior to the submission of longitudinal sections, cross-sections and other information pursuant to Section 300 of these specifications.

602 ORDER OF WORKS

Based on longitudinal and cross sections for designated culvert locations, as to be submitted by the Contractor, precise details of Culverts length, skew and invert levels will be issued to the Engineer from time to time as construction proceeds. The Contractor shall allow in his programme a period of 21 days between submission of longitudinal and cross-sections in accordance with Section 300 above and the issue of precise culvert details.

The Contractor shall normally construct culverts and drainage works prior to constructing embankments above or adjacent to culverts or drainage works unless permitted otherwise by the Engineer, and he shall programme the Works accordingly.

Where the Contractor considers that drainage conditions are such that it is not necessary to construct a culvert ahead of the embankment, the Engineer at his discretion may consent to its installation after construction of the embankment on the following conditions:

The Contractor will be responsible for any damage or delay to the culvert or to the embankment earthworks; and the construction of the culvert shall follow immediately after embankment earthworks.

Where culverts are to be constructed under a road in cutting, excavation and backfill shall be carried out after the bulk earthworks are completed but before the processing of the 300 mm layer below formation level in cuttings. The Engineer at his discretion may consent to the excavation for these culverts being carried out before the earthworks are completed but payment for the excavation of the trench will only be made for the volume excavated below formation level.

600-2

603 CLASSIFICATION OF EXCAVATION

All excavation for culverts and drainage structures shall be classified as follows:

Rock excavation is material which can be excavated only after blasting with explosives or barring and wedging or the use of a mechanical breaker fitted with a rock point in good condition and operated correctly. Single boulders of size more than 0.30m3 shall be classified as rock excavation.

Common excavation is all material other than rock excavation, including that which is suitable and unsuitable for reuse.

604 EXCAVATION FOR CULVERTS AND DRAINAGE STRUCTURES

The Contractor shall carry out all excavations for culverts and structures to the lines, levels, inclinations, and dimensions shown on the Drawings or instructed by the Engineer.

In the event that the Contractor excavates to a greater depth or width than is necessary, then he shall at his own cost backfill the excess excavation with approved materials, compacted to the density of the adjacent ground, all to the correct levels and dimensions and to the approval of the Engineer.

The Contractor shall carefully set aside the various suitable materials encountered so that they may be reused for backfilling. If excavated materials are unsuitable, the Contractor may remove the material to tip after approval by the Engineer.

The Contractor shall keep all excavations clean and free from water, and he shall dig diversion channels, erect cofferdams, pump or otherwise de-water the excavation.

Where, in the opinion of the Engineer, the surface of the excavation has become soft or unsuitable due to the Contractor’s method of working, the Contractor shall at his own cost remove and replace the unsuitable material with approved granular material or non-structural concrete as instructed by the Engineer.

The Contractor shall compact the final excavated surface on which culverts or structures are to be constructed to a dry density of at least 95% MDD (ST RK 1285-2004) to a depth of 150 mm. All particles larger than 20 mm shall be removed prior to compaction.

For culverts which are to be constructed approximately on the existing ground after the removal of topsoil, the Contractor shall level the existing ground by excavating and/or filling in layers. He shall then compact the ground for 150 mm below invert or underside of bedding material to a dry density of 95% MDD (ST RK 1285-2004) such that the foundation for the culvert or bedding is true to Class and of uniform density over the whole length of the culvert.

The Engineer’s approval to the final excavated and prepared soil/rock foundation below the culvert shall be obtained prior to the installation of culverts and associated structures.

600-3

The sides of pits, trenches and other excavations shall, where required, be adequately timbered and supported, and all such excavations shall be of sufficient size to enable the culvert units and concrete to be laid accurately, and proper refilling and compaction to be carried out.

All shoring and timbering shall be kept in trenches and other excavations as the Engineer instructs.

Where ground conditions are such that a satisfactory foundation cannot be achieved, the Contractor shall, if instructed by the Engineer, remove the unsuitable material either until suitable material is encountered or to the depth and width instructed by the Engineer. The Contractor shall backfill the resultant excavation with approved material compacted to dry density of 95% MDD (ST RK 1285-2004). Approved material shall be selected backfill /suitable fill material in accordance Clause 510.

Before any drainage channel, culvert or other drainage structure is brought into use, the Contractor shall ensure that such channel or structure is free from all silt and extraneous material to the satisfaction of the Engineer, and the removal and disposal of all such material shall be at the Contractor's expense.

605 EXCAVATION IN ROCK

Where rock or similar hard material is encountered in trenches for concrete pipe culverts, the Contractor shall excavate it so that no hard material protrudes within 50 mm of the pipe barrel. He shall place and compact a regulating layer of non-structural concrete of minimum thickness 50 mm on the excavated hard material surface, the top of which shall be at the level of the underside of the pipe barrel. The maximum thickness of regulating layer shall be 150 mm. Where both soft and hard material are encountered in the trench either the soft material shall be removed to a depth of 300 mm or to such depth as instructed by the Engineer, or if directed by the Engineer the hard material shall be removed to a depth of 300 mm or to such depth as instructed by the Engineer and backfilled to 95% MDD (ST RK 1285-2004) with material similar to that in the remainder of the trench invert.

606 FOUNDATIONS AND ABUTMENTS CAST AGAINST EXCAVATED SURFACES

Where the Drawings show or the Engineer instructs that a foundation and/or abutment shall be cast against an excavated surface, the Contractor shall carry out the excavation neatly to the specified slope and shape. Should any over-excavation occur the Contractor shall backfill the space between

600-4

the foundations and/or abutment and the excavated surface with cement concrete Class B15. Such backfill shall be placed at the Contractor’s expense.

607 BACKFILLING FOR CULVERTS AND DRAINAGE STRUCTURES

The Contractor shall obtain the Engineer’s approval prior to commencing any filling around a structure or backfilling a trench or excavation, or to loading any structure.

The Contractor shall obtain the Engineer’s approval to his proposed sequence of filling and backfilling behind and around a structure and to the height of fill at any time between fill levels.

The Contractor shall obtain backfill for concrete culverts and minor drainage structures from suitable material from the excavation. In the event of there being insufficient excavated material or the culvert is laid close to or above existing ground level then he shall obtain selected backfill/suitable fill material (in accordance with the Section 500) from borrow pits. All backfill whether from excavated material or borrow pits shall be as approved by the Engineer.

For culverts which have been placed and where no concrete haunch or surround is specified, the Contractor shall place selected fill/suitable fill material (in accordance with the Section 500). He shall mix in water or dry the material, such that the moisture content at the time of compaction shall be within the range of 1% above or 2% below the Optimum Moisture Content (ST RK 1285-2004), and compact it thoroughly along the remainder of the underside of the barrel of the pipe and in the joint holes. He shall lay and compact similar selected/ suitable fill material in layers not exceeding 150 mm loose thickness, mixed, dried or watered as necessary, and bring it up uniformly on both sides of the culvert to a height of not less than 300 mm over the crown.

The Contractor shall backfill the remainder of the trench with selected fill/suitable fill material, placed in layers not exceeding 150 mm loose thickness, mixed, watered or dried as necessary, and compacted.

The Contractor shall compact all backfilling material to a minimum dry density of 95% MDD (ST RK 1285-2004).

Where timbering or sheeting have been installed for the purposes of supporting the excavation the Contractor shall, unless approved otherwise by the Engineer, remove them by easing them up 150 mm at a time in step with the backfill layer, and he shall compact backfill under and behind such timber or sheeting.

For culverts which have been constructed close to or above the existing ground or where the culvert protrudes above the existing ground the Contractor shall place and compact the backfill material under the sides and alongside and over the culverts in layers not exceeding 150 mm after compaction to a density of at least the density required for the material in adjoining layers of fill. The width of backfilling along the flanks of the culvert shall be at least (2 + 1.5h) metres from each side of the culvert (where ‘h’ is the height from the underside of the layer being compacted to the crown of the pipe in metres).

All existing ground under this backfill shall be compacted to 95% MDD (ST RK 1285-2004) to a depth of 150 mm.

600-5

The material used for filling alongside the culvert above existing ground shall be the same material as will be used for the adjacent fill and no additional payment will be made other than provided for the fill in Section 500 above.

The Contractor shall carry out backfilling simultaneously and equally on both sides of the culvert to avoid unequal lateral forces.

The Contractor shall not drive any construction equipment over culverts under construction and where it is absolutely necessary to do so, he shall obtain advance permission from and provide protection measures as approved by the Engineer.

Where shown on the Drawings or instructed by the Engineer, the Contractor shall place selected granular fill material (in accordance with Clause 510) and/or porous filter material approved by the Engineer. The Contractor shall use a sliding form or other means approved by the Engineer during backfilling such that the porous layer is brought up and compacted at least 150 mm ahead of the selected granular fill material, and that the selected granular fill material is brought up and compacted at least 150 mm ahead of the adjacent earthworks fill. The interface between selected granular fill material conforming to this Section 700 and the adjacent earthworks carried out in accordance with Section 500 above shall be as shown on the Drawings or instructed by the Engineer. Where selected granular fill is not specified or instructed, the Contractor shall backfill behind and around the structure and up to ground level using suitable excavated material. Above ground level the Contractor shall use the same material as that being used for the adjacent embankment.

608 PRECAST STEEL REINFORCED CULVERT UNITS

Concrete pipes shall be manufactured and tested in accordance with the Technical Conditions OST ОSТ 35-27.0-85, typical project «Pipe and box pipe chains for road load А14, НК-120 and НК-180». Issue 1. Round chains. Request № 04-08. «Kazdorproject» LLP, 2008, and the section 900 below and details shown in the drawings. Structures and dimensions of the culverts shall comply to OST 35-27.1-85 and typical «Pipe and box pipe chains for road load А14, НК-120 and НК-180». Issue 1. Round chains. Request № 04-08. «Kazdorproject» LLP.

Rectangular Precast Concrete culvert and other structural units shall comply with the requirements of the Technical Conditions OST 35-27.0-85, typical project «Pipe and box pipe chains for road load А14, НК-120 and НК-180». Issue 1. Box chains. Request № 04-08. «Kazdorproject» LLP, 2008, and the section 900 below and details shown in the drawings. Structures and dimensions of the culverts shall comply to OST 35-27.1-85 and typical «Pipe and box pipe chains for road load А14, НК-120 and НК-180». Issue 1. Box chains. Request № 04-08. «Kazdorproject» LLP.

600-6

Звенья железобетонные

круглые с плоскими операнием по

типовому проекту серии 3.501.1-144

РIPE SEGMENT Design series 3.501.1-144

Марка звена Вrand Name

ЗКП 2.100 ZKP 2.100

ЗКП 2.200 ZKP 2.200

ЗКП 6.100 ZKP 6.100

ЗКП 6.200 ZKP 6.200

  Габаритные размеры , мм

Overall dimensions, mm        

1 Длина Length 1000 2000 1000 2 000

2 Внутренный диаметр Internal diameter 1000 1000 1500 1 500

3 Толщина стенки Wall thickness 120 120 160 160

4 Класс бетона Concrete class В 30 В 30 В 30 В 30

600-7

КРУГЛЫЕ ЗВЕНЬЯ PIPE SEGMENTS

№ п.п. Марка звена по Т.П.

Brand name accordingДлина Length

Наружный диаметр External Diameter

Внутренный диаметр Internal

Diameter

Толщина стенки, мм Thickness

1Бл №10 ВI№10

1000 700 500 100

2Бл №11 ВI№11

1000 910 750 80

3Бл №13 ВI№13

1000 1240 1000 120

5Бл №14 ВI№14

1000 1490 1250 120

600-8

ПОРТАЛЬНЫЕ СТЕНКИ ОГОЛОВКОВ КРУГЛЫХ ВОДОПРОВОДНЫХ ТРУБ PORTAL STRUCTURE FOR THE CULVERT PIPES

№

Марка изделия Brand name

Габаритные изделия, мм

Длина Length

Ширина Width

Высота Нeight

1CT-8 ST-8

1850 1500 350

2CT-9 ST-9

2350 2260 350

3CT-10 ST-10

2720 1220 680

4CT-11 ST-11

2930 1420 680

5CT-12 ST-12

3250 1760 680

6CT-13 ST-13

3570 2100 680

7Блок №17 Block №17

4200 2740 680

600-9

ХАРАКТЕРИСТИКИ ИЗДЕЛИЙ PRODUCT CHARACTERISTICS

№Класс бетона

Concrete class

Марка звена

Segment brand

Габаритные изделия, мм Размер отверстия Size of mouthof pipe,

mДлина Length

Ширина Width

Высота Нeight

1 В 30ЗП 2100 RS 2100

1000 1220 1780 1,0x1,5

2 В 30ЗП 8.100 RS 8.100

1000 1740 2430 1,5x2,8

3 В 30ЗП 10.100 RS 10.100

1000 2260 2380 2,0x2,0

4 В 30ЗП 11.100 RS 11.100

1000 2260 2500 2,0x2,0

5 В 30ЗП 12.100 RS 12.100

1000 2320 2680 2,0x2,0

6 В 35ЗП 13.100 RS 13.100

1000 2760 2450 2,5x2,0

7 В 35ЗП 14.100 RS 14.100

1000 2840 2570 2,5x2,0

8 В 35ЗП 19.100 RS 19.100

1000 4300 3130 4x2,5

600-10

9 В 35ЗП 20.100 RS 20.100

1000 4420 3170 1,0x1,13

10 В 35ЗП 21.100 RS 21.100

1000 4600 3370 1,0x1,13

ОГОЛОВКИ ТРУБ CULVERT HEADS

11 В 30 ЗП М 32 1000 1220 2120 1,0x1,512 В 30 ЗП 34 1000 1740 2700 1,5x2,013 В 30 ЗП 35 1000 2260 2740 2,0x2,014 В 35 ЗП 36 1000 2750 2800 2,5x2,015 В 35 ЗП 38 1000 4360 3400 4x2,5

ЛЕКАЛЬНЫЕ БЛОКИ CURVED BLOKS

№

Марка изделия Brand name

Габаритные изделия, мм

Длина Length

Ширина Width

Высота Нeight

1Лек. Блок №4

Curved block №4 2010 1190 430

600-11

2Лек. Блок №5

Curved block №51500 1190 430

3Лек. Блок №8

Curved block №82010 1600 520

4Лек. Блок №9

Curved block №91500 1600 520

5Лек. Блок №24

Curved block №241320 1300 460

6Лек. Блок №26

Curved block №261320 1780 560

7Лек. Блок №6

Curved block №62010 1390 480

8Лек. Блок №7

Curved block № 71500 1390 480

600-12

609 BEDDING AND LAYING OF CULVERTS

Culverts shall be bedded directly above soil material. Where the soil conditions are unsuitable, the Contractor shall excavate the invert and backfill it as specified in the Section 600.

A BEDDING AND LAYING OF CONCRETE CULVERTS ON EXISTING OR IMPORTED FILL MATERIAL OR IMPORTED GRANULAR MATERIAL

The Contractor shall compact the bottom of the excavation to 95% MDD (ST RK 1285-2004).

Where the pipe is to be laid directly on the in-situ foundation, the foundation shall be accurately shaped so that the barrel of the pipe rests uniformly on the foundation over at least one-third of its diameter and for the full length of the barrel.

Where the pipe is to be bedded on pipe bedding material, well graded granular material shall be used with a maximum stone size of 20 mm and a maximum 10% passing the 75m sieve. The material shall be compacted to 95% M.D.D. (ST RK 1285-2004).

In both cases, the Contractor shall form voids under the sockets to allow pipe jointing. When the pipe joint has been completed, the void shall be rammed with well graded granular pipe bedding material.

B BEDDING AND LAYING OF CONCRETE UNITS ON A CONCRETE BED

1) Where units are required to be laid on a concrete bed, the Contractor shall bed the units on 1:3 cement mortar: sand mortar at least 50 mm thick, 150 mm wide and extending the full length of the barrel.

2) After the joints have been formed, the Contractor shall pack concrete Class B15 hard under the barrel and sockets of the culvert and extend it upwards on each side of the culvert to the height shown on the Drawings.

610 JOINTING CONCRETE CULVERTS

A RIGID JOINTS

1) Contractor shall clean spigots and sockets of rigid-jointed concrete pipes with integral sockets to remove all mud, oil, grease or other deleterious matter before entering a pipe spigot into its socket. He shall wrap a gasket of tarred hemp yarn, cut to length so that it forms a butt joint at the crown of the pipe, round the spigot which shall then be fully entered into the socket and the gasket caulked up hard into the joint.

600-13

He shall then fill the joint completely with a plastic mortar composed of one part of cement to two parts of sand and finished off with a fillet at an angle of 45.

2) Rigid jointed sleeves used to join two spigots shall be jointed in the same manner as integral sockets.

3) If the Engineer requires ogee jointed pipes to be laid with a mortar joint, the Contractor shall make the joint at the time of laying. He shall apply mortar as described above to the lower semi-circumference of the socket and to the upper semi-circumference of the spigot, and draw the pipe hard into the socket. The outside of the joint shall be pointed up with a fillet of 1:2 cement : sand mortar, 75 mm wide and 25 mm thick, all the way round and central over the joint.

4) The Contractor shall saturate all pipes with water before jointing and scrape clean inside and finish off the joint with 1:2 cement : sand mortar.

5) The Contractor shall protect all joints from the wind, sun and rain by a covering approved by the Engineer, and shall keep them constantly damp for a period of at least three days.

6) The Contractor shall ensure that the pipes are not disturbed in any way for at least 48 hours after jointing.

B PROTECTIVE BITUMINOUS COATING AND TAPING

Where directed by the Engineer a protective bituminous coating shall be applied to the outside surfaces of the culvert barrel to provide a water-proof membrane seal. The paint shall be a mastic asphalt or similar propriety product approved by the Engineer.

Where directed by the Engineer the joints between culvert units shall be taped on the outside using two layers of DENSA sealing tape or equivalent approved by the Engineer.

C CULVERT ENDS

Unless otherwise specified pipe ends shall be left normal.

Portal and rectangular units shall not be provided with skewed ends. These culvert units shall be supplied square and the portion that would otherwise be cut off shall project outside the culvert head walls.

611 CONCRETE BEDS, SURROUNDS AND HAUNCHES

The Contractor shall clean, trim and compact the floor of the trench before any bed, surround or haunch is placed and obtain the approval of the Engineer before commencing concreting.

All concrete for beds, surrounds and haunches shall be Class B15 complying with Section 900 below, formed to the dimensions shown on the Drawings or instructed by the Engineer.

600-14

Unless otherwise instructed by the Engineer, the Contractor shall place 150 mm of concrete surround to concrete pipes in the following circumstances:

a) concrete pipes up to and including 600 mm with cover less than 600 mm or more than 3.0m;

b) concrete pipes over 600 mm diameter and not exceeding 900 mm diameter with cover less than 1.0m or more than 3.0m;

c) concrete pipes over 900 mm diameter, at any depth.

612 DRAINAGE STRUCTURES

Drainage structures shall include headwalls, wing walls and apron slabs in culvert inlet and outlet structures. They shall also include minor structures such as catch pits, cascades, chutes, channels, spillways and the like, working details for which will be issued by the Engineer from time to time during the Contract.

Culvert inlet and outlet structures shall be in accordance with typical highway project No 3.501-1-156 Lengipritransmost, 1989.

In-situ or pre cast concrete for drainage structures shall be Class B20 in accordance with Section 900 below unless otherwise shown on the Drawings. The surface finish shall comply with the requirements of the typical highway project.Unless otherwise specified or shown on the Drawings concrete shall be reinforced in the back and front faces of all walls and the top and bottom of all slabs, as directed by the Engineer, both horizontally and vertically to form a mesh. The reinforcement shall be fixed in accordance with, and shall comply with, the requirements of Section 900.

613 OUTFALL CHANNELS, DAMS AND SCOUR CHECKS

Outfall channels, earth dams and scour checks shall be formed at the locations and to the lines and levels shown on the Drainage or as instructed by the Engineer.

Where shown on the Drawings or instructed by the Engineer the Contractor shall construct earth dams in side drains, cut-off drains, catch water drains, mitre and outfall drains to prevent the flow overshooting the drainage works or to direct flows into culvert inlets. Similar earth structures may also be used as erosion checks.

Earth dams shall be formed in selected/suitable fill material compacted to a minimum dry density of 95% MDD (ST RK 1285-2004). Where stone pitching is instructed it shall be in accordance with the Section 600. Where top soiling is instructed it shall be in accordance with Section 500 above.

The Contractor may also excavate in the invert of drains for scour checks to be located as shown on the Drawings or directed by the Engineer. The width and the depth of the scour check will be determined by the drain and scour check dimensions and shall be as directed by the Engineer.

600-15

Concrete for scour checks shall be Class B20 which shall comply with the requirements of Section 900 below.

614 CLEANING AND MAINTENANCE

The Contractor shall be responsible for maintaining the existing and new including temporary drainage systems during construction of culverts and all other drainage works such that water is passed along and across the Works without damage to the Works and all cofferdams, diversions, pumping, temporary drainage works or other works necessary shall be provided and maintained at the Contractor’s cost. Any damage caused to the Works by the Contractor’s failure to make adequate provision for drainage of the Works shall be repaired at the Contractor’s cost.

615 CONCRETE EDGE KERBS CHANNELLING AND LINING

This section covers the construction of concrete edge kerbing and channelling, open concrete chutes and concrete lining of open drains in accordance with typical highway project 503-09-7.84 Souzdorproject, 1984 y, and to the details shown on the Drawings or as directed by the Engineer. Precast elements of drainage structures are accepted in accordance with the typical highway project of the No. 3.503.1-66, Souzdorproject, 1984 y.

A MATERIALS

All concrete work shall be carried out in accordance with the requirements of Section 900 of these Specifications.

1) Edge Kerbs Edge kerbs include barrier kerbs, mountable and semi-mountable kerbs which may be constructed in Class B20 pre-cast concrete to the dimensions shown on the Drawings

2) Chutes (Cascades)

Chutes shall be manufactured in Class B20 pre-cast concrete to the dimensions shown on the Drawings, and the units shall fit neatly into each other.

3) Channels

Channels shall be constructed from Class B20 concrete and reinforced with high yield steel mesh reinforcement in both faces as indicated in the drawings or directed by the Engineer.

4) Joint Sealant

Cold-poured joint sealant shall be a two-part polysulphide sealing compound.

5) Bedding Material

600-16

The material on which concrete kerbs and channels are to be bedded shall consist of crushed stone, cinders, slag, sand or other approved porous material with a maximum particle size of 15 mm.

Where concrete bedding material is shown on the drawings, it shall comply with the requirements of non-structural concrete of Section 900.

B CONSTRUCTION

1) Excavation and Bedding

Trenches for kerbs and channels shall be excavated to the required depth and all unsuitable material shall be removed and replaced with a layer of selected bedding material at least 75 mm thick. The bedding shall be compacted and accurately shaped to the required grade. No concrete shall be placed on uncompacted or disturbed material. Excavation for channel drains shall be constructed and paid for in accordance with the provisions of this Section. All loose material shall be compacted to a density of not less than 95% MDD (ST RK 1285-2004).

Where channel excavation is in rock the conditions of the Section 600 shall be applied.

Excavations for chutes shall be neatly trimmed. All loose material shall be compacted and where overbreak occurs in hard material it shall be backfilled with non-structural concrete.

2) Precast concrete edge Kerbs

Pre-cast concrete kerbing shall be laid and bedded in Class B15 concrete with close joints of 3:1 sand: cement mortar at the ends. The joints may not exceed 10 mm in thickness and must be neatly pointed with a pointing trowel. Guide lines and straight-edges shall be used to ensure that the exposed faces of kerbs and edgings are set true to line and elevation. Kerbing around curves shall be laid along the full curve length before the joints are made, unless otherwise allowed by the Engineer.

3) Concrete Channels

Concrete channels shall be cast in alternate sections. The lengths of sections shall be uniform throughout and shall be equal to 2 m for every 100 mm average thickness or depth of concrete measured perpendicular to the bed, except where shorter sections are necessary for closures or where otherwise shown on the Drawings or required by the Engineer. The exposed surfaces of the concrete shall be finished in accordance with Section 900 below. The concrete shall be cured in accordance with the requirements of Section 900 below.

Abutting joints shall be painted with mastic asphalt coating before intermediate sections are cast.

Guidelines and straight-edges shall be used to ensure that the exposed are formed to line and elevation.

When curing is complete the joints shall be sealed with an application of joint sealant as specified.

600-17

4) Concrete Chutes in cascades on side slopes of fills and cuts

The units shall be neatly laid to line and grade from the bottom upwards so that each consecutive unit fits neatly into the previous one, with the bottom unit resting against the outlet structure.

A transition section shall be constructed at the inlet to lead the water into the chute as shown on the Drawings.

5) Concrete-Lined Open Drains

Concrete lining shall be constructed from Class B20 concrete and shall be laid to the shape and levels indicated on the Drawings and directed by the Engineer. The surface of the excavation against which the lining is to be placed shall be covered by polythene sheet 0.15 mm thick and all joints in the sheeting shall overlap by at least 150 mm. The concrete lining shall be cast in alternate panels and cold joints shall be painted as specified before adjoining slabs are cast.

6) Transition Sections

Transition sections for chutes shall be constructed in situ in Class 20/20 concrete to the dimensions indicated on the drawings or as directed by the Engineer. They shall be built to the same standards as described for the edge kerbing.

Where kerbs and channels are laid after construction of the base, the spaces between the concrete and adjoining base shall be filled with compacted pre-mixed bituminous material and the cost shall be included in the rates for the items.

C TOLERANCES AND SURFACE FINISH

1) Concrete Edge Kerbs and Channelling

Concrete kerbing and channelling shall be constructed to within the following dimensional and alignment tolerances:

(i) Horizontal Alignment

The maximum deviation of edges, centre line or vertical surfaces from the specified position shall be 25 mm.

Maximum deviation of edges, centre line or vertical surfaces from the specified alignment shall be 1:500 when taken over any section more than 10 m in length.

(ii) Vertical Alignment and Level

The inside edge of channelling shall nowhere be above the finished road level nor more than 10 mm below the finished road surface. The invert level of channels and drains and the top of kerbing shall nowhere deviate more than 10 mm from the required level and nowhere shall channels or drains have any adverse grade.

600-18

(iii) Trueness of exposed surfaces

When tested with a 3 m straight-edge, no surface irregularities shall exceed 6 mm.

(iv) Cross-Sectional Dimensions

All cross-sectional dimensions shall be within 6 mm of the specified dimensions, except that the underside of channelling may extend up to 25 mm below the level at which it would have the required thickness.

2) Concrete Chutes and Concrete-Lined Open Drains

Concrete-lined open drains and concrete chutes shall be constructed to within the following tolerances:

(i) Horizontal AlignmentThe maximum deviation from the true position of the edges or centre line shall be 25 mm.

Maximum deviation of edges, centre line or vertical surfaces from the specified alignment shall be 1:500 when taken over any section more than 10 m in length.

(ii) Vertical AlignmentThe invert level of concrete-lined open channels shall nowhere deviate more than 25 mm from the required level and nowhere shall the open-drain inverts have an adverse grade.

(iii) Trueness of Exposed SurfacesWhen tested with a 3 m straight-edge, no exposed surface shall show surface irregularities of more than 10 mm.

(iv) Cross-Sectional DimensionsAll cross-sectional dimensions shall be within 10 mm of the specified dimensions and the average thickness of any invert of side slab shall not be less than the specified thickness when considering any complete slab or any slab section having a surface area of 10 m2 or more and disregarding any thickness of more than 10 mm in excess of the specified thickness.

PART B - RIVER TRAINING AND PROTECTION WORK

616 BANKS AND DYKES

The alignment and layout of dykes shall be as indicated on the drawings or as directed by the Engineer. The construction of embankments for dykes shall conform to provisions of Section 500 above and shall be measured and paid for accordingly.

Pitching, filter underneath pitching, rip-rap in apron, toe protection etc. shall be as per these specifications.

600-19

617 RIPRAP

Stone for rip-rap shall consist of well shaped hard dense durable rock. At least 50 per cent of the pieces shall have a volume greater than 0.03 m3 and not more than 5 per cent shall have a volume of less than 0.01 m3. The stone for rip-rap shall consist of two sizes:

a) Primary stones shall consist of hard angular pieces with no dimension less than 65 mm nor any dimension more than 250 mm. The specific gravity of the stone material shall not be less than 2.50 and the individual pieces of stone shall weigh not less than 20 kg and not more than 35 kg.

b) Choke stones shall consist of fragments or spalls smaller than the primary stones and properly sized to wedge satisfactorily between the primary stones.

The aggregate for filter underlay shall consist of hard durable particles or fragments of crushed stone or natural gravel, screened or crushed to meet the following grading requirements:

Sieve size Percent passing70 mm 1005 mm 20-500.071 mm 0-10

The ground surface to be protected shall be shaped to the correct lines and profiles within a tolerance of +25 mm. Protection shall begin in a ditch excavated at the toe of the slope, having depth up to 0.6 mm and the side of the ditch next to the fill or cut shall have the same slope. The toe trench shall be backfilled after the slope protection has been placed.

Filter underlay shall be placed on the prepared ground to the required thickness with a thickness tolerance of +10 mm. The thickness of the filter underlay shall be one-third the thickness of the stone rip-rap as shown on the drawings or as directed by the Engineer. The filter underlay shall be compacted to the extent necessary to hold it in place during the placement of the stone rip-rap protection.

Stone rip-rap protection shall be placed to the specified thickness and limits with a thickness tolerance of +15 mm. Stones shall be hand placed and fitted to each other to form a neat, uniform, reasonably continuous and compact layer.

The stones shall be laid with close joints from the bottom of the slope of embankment or existing ground. Larger stones shall be placed first with their longitudinal axis normal to the slope face and so arranged that each stone above the foundation course has a three point bearing on underlying stones. The foundation course is placed on the slope in contact with the filter layer. Stones shall not be placed by dumping. Interstices between larger stones shall be tightly hand-packed with choke stones upward. The surface shall be hand packed, carefully bedded and tightly wedged with suitable spalls to form an even surface.

600-20

Stone rip rap shall be laid so that the line and level of the finished surface does not vary by more than +20mm from the drawings or as otherwise instructed by the Engineer. The thickness shall not vary by more than +15mm or –0mm from that shown on the drawings.

618 IN-SITU OR PRECAST STEEL REINFORCED CONCRETE SCOUR PROTECTION

In-situ or precast steel reinforced concrete scour protection shall be class 20/20 in accordance with Section 900. The surface finish shall be U1 for unformed finishes and F1 for formed finishes. Reinforcement shall be 10mm diameter, 200mm x 200mm square

619 STONE PITCHING

The work consists of providing protection to the sides and bottoms of open drains at selected locations using hand-placed stone pitching backed by filter underlay and grouted from top. Lined drains shall be constructed to Drawings or as instructed by the Engineer and subject to the requirements further indicated herein.

The stone for pitching shall consist of two sizes:

Primary stones shall consist of hard angular pieces with no dimensions less than 75 mm nor any dimension more than 250 mm. In one of the directions, the stone shall measure between 125 to 165 mm. The specific gravity of the stone material shall not be less than 2.50. Choke stones shall consist of fragments or spalls smaller than the primary stones and properly sized to wedge satisfactorily between the primary stones.

The aggregate for filter underlay shall consist of hard durable particles or fragments of crushed stone or natural gravel, screened or crushed to meet the following gradations requirements:

Sieve size Percent passing50 mm 10020 mm 85-1005 mm 20-500.071 mm 0-10

The sides and bottom of drain to be lined shall be excavated to the correct line and level within a tolerance of +15 mm. Placement of filter underlay and stones shall begin at the bottom of the drain and be extended upwards along the sides of the drain.

Filter underlay shall be placed on the prepared ground to a thickness of 75 mm with a thickness tolerance of +10 mm. The filter underlay shall be compacted to the extent necessary to hold it in place during the placement of the stone pitching.

Stone pitching shall be placed to a thickness of 150 mm with a thickness tolerance of +15 mm. Stone shall be hand placed and fitted to each other to form a neat uniform, reasonably continuous

600-21

and compact layer. Larger stones shall be placed first with their longitudinal axis normal to the slope face and interstices between larger stones shall be tightly hand-packed with choke stones.

Stone pitching shall be laid so that the line and level of the finished surface does not vary by more than +20mm from the drawings or as otherwise instructed by the Engineer. The thickness shall not vary by more than +15mm or –0mm from that shown on the drawings.

The grout shall be prepared using one part of Portland cement and three parts of sand (70 to 100 % passing 1.18 mm sieve and not more than 10% passing 0.075 mm sieve) thoroughly mixed with water to produce a workable mix. Before grouting, stones shall be well moistened with water after placement. The grout shall be applied while the stone is moist and worked into the interstices to fill the voids completely. Grout shall not placed in rainy weather and when the temperature is below 2oC.

620 SCOUR CHECKS

Steel reinforced concrete for scour checks shall be Class B20 and shall comply with the requirements of Section 900 of this Specification. Formwork, complying with the requirements of Section 900 of this Specification, shall be provided for all concrete placed above the level of the drain profile. Unless otherwise specified or shown on the Drawings, concrete for scour checks shall be reinforced in the back and front faces with 10 mm diameter high yield stress deformed bars placed at 200 mm centres both horizontally and vertically to form a mesh. The reinforcement shall be fixed in accordance with, and shall comply with, the requirements of Section 900 of this Specification.

621 PRECAST REINFORCED CONCRETE GRID SLOPE PROTECTION WITH STONE INFILL

Reinforced concrete precast grids will be placed on the embankment slopes, tied with steel embedded into the embankment as shown in the drawings or as directed by Engineer.

Crushed stones of 10-40 mm size, 100 mm thick shall be laid and compacted within the reinforced precast concrete grids. All crushed stones shall be hard, tough, frost-resistant and shall have Abrasion value under ST RK 1213-2003 not less than 30 and frost resistance ST RK 1284-2004 not more than 10% (F25).

Concrete shall be of Class B20 and shall comply with the requirements of Section 900 of this Specification. Steel/reinforcement shall meet the requirements of Section 900 as detailed in the drawings.

600-22