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CHAPTER9ReinstatementofPitsandTrencheswithin

RoadsCorridors

MaterialsEngineeringDirectorate

AsApprovedon1332008

Ref. : Dr Walaa E.I. Khogali

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Preface This document is prepared by the Materials Engineering Directorate (MED) in response to a request made by Roads Projects and Maintenance Directorate (RPMD) and Sanitary Engineering, Planning and Projects Directorate (SEPPD) to modify current specifications used for reinstatement of pits and trenches in roads corridors. The Specifications contained herein represents an updated version of chapter 9 of the Code of Practice for Service Installation (COPSI), which was first produced in May 1986. Although the format and much of the content of the old chapter 9 was kept, significant additions from a number of the Ministry of Works standards and other sources were utilized in updating the specifications. The list of references include: General Specifications for Roadworks (revised September 1997), Section B: Earthworks (1987), Ministerial Decree 194 (issued 2006), and the Restoration Guide for Road Utility Cuts Project (issued by the National Research Council of Canada in 2004). Beside the information gathered from these references, the task also involved a series of brainstorming sessions with members from RPMD, SEPPD and RPDD (Roads Planning and Design Directorate) to identify current reinstatement problems and to address them using a unified approach. The objectives of the new specifications were to update/modify current procedures used in the reinstatement process and to consolidate the large number of specification documents currently in use by various consultants/contractors into one universal specifications document. This is intended to facilitate the role of the Ministry in administering projects and also to eliminate future confusion among consultants/contractors related to use of the Ministrys specifications for reinstatement works. The specifications document is organized into two parts: a main body text and three appendixes. The main text consists of four sections: general, materials, workmanship and maintenance. The general section states the scope of the chapter with some definitions. The materials section, together with Appendix I, lists all types of materials that are used in backfilling and asphalt concrete reinstatement operations, while the workmanship section provides all construction details related to restoring the road to its original condition. The workmanship section is structured in order of work-flow, with activities appearing in several places that correspond to the progression of the construction process. In this regard, the workmanship section is divided into four sub-sections dealing with cutting and excavation, backfilling, reinstatement of asphalt concrete layers and restoration of road furniture. The maintenance section identifies responsibilities of consultants/contractors upon completion of works. Appendix II contains two standard forms that are used by the Damage Prevention Control Unit (DPCU) of RPMD to document reinstatement work. Appendix III contains information related to restoring traffic devices that are disturbed during the excavation process. It should be noted that as the new document represents only one chapter of the COPSI, the implementation and interpretation of the specifications contained herein must be carried out in conjunction with the remaining chapters of the COPSI. To further the adoption of the new specifications for on-going and future projects, MED will submit the current draft to H.E. the Minister for his approval. It is also planned that as the Ministrys STANDARD SPECIFICATIONS FOR CONSTRUCTION WORKS, currently undertaken by Halcraw, is completed, the newly developed reinstatement specifications will be incorporated as part of these Standards. As part of the implementation phase of the new specifications, MED in conjunction with other directorates of the Ministry of Works will organize educational seminars/workshops, which will be directed towards the various professionals/stakeholders involved with the reinstatement process. As a final note, MED would like to acknowledge the significant contributions made by all team members from RPMD, RPDD and SEPPD towards reviewing this document and towards providing good insights and constructive feedback during all stages of the specifications development process.

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Table of Contents Preface 2 Table of Contents 3

9.1 GENERAL ................................................................................................................................. 5 9.1.1 Purpose .................................................................................................................................... 5 9.1.2 Definitions ................................................................................................................................ 5 9.1.3 Scope ........................................................................................................................................ 6 9.1.4 Quality control/Quality Assurance ......................................................................................... 6

9.2 MATERIALS .............................................................................................................................. 6 9.2.1 General ..................................................................................................................................... 6 9.2.2 Backfill Materials .................................................................................................................... 6 9.2.3 Tack Coat and Prime Coat ...................................................................................................... 6 9.2.4 Asphalt Concrete Surfacing Materials ................................................................................... 6 9.2.5 Portland Cement Concrete (PCC) Materials .......................................................................... 7

9.3 WORKMANSHIP ....................................................................................................................... 7 9.3.1 General ..................................................................................................................................... 7 9.3.2 Traffic Safety ............................................................................................................................ 7 9.3.3 Pavement Cutting and Excavation ......................................................................................... 7 9.3.3.1 General ..................................................................................................................................... 7 9.3.3.2 Support to Excavations ........................................................................................................... 8 9.3.3.3 Dealing with Ground Water ..................................................................................................... 8 9.3.3.4 Pavement Cutting Guidelines ................................................................................................. 9 9.3.3.5 Excavation Guidelines ............................................................................................................ 9 9.3.3.6 Trench/pit Inspection Prior to Backfilling ............................................................................ 10 9.3.4 Backfilling .............................................................................................................................. 12 9.3.4.1 General ................................................................................................................................... 12 9.3.4.2 Bedding, Laying and Surrounding of Pipes and Cables ..................................................... 12 9.3.4.3 Backfilling Procedure for Trenches in Major Roads (carriageways, hard shoulders and

street car parking) ................................................................................................................. 13 9.3.4.4 Backfilling Procedure for Trenches in Minor Roads .......................................................... 13 9.3.4.5 Testing of Backfill .................................................................................................................. 14 9.3.4.6 Special clause: Backfilling below Formation level ............................................................. 14 9.3.4.7 Surface preparation prior to asphalting ........................................................................ 14 9.3.5 Reinstatement of Asphalt Concrete surface ....................................................................... 15 9.3.5.1 General ................................................................................................................................... 15 9.3.5.2 Laying and Compaction ........................................................................................................ 16 9.3.5.3 Joints ...................................................................................................................................... 17 9.3.5.4 Opening Road to Traffic ........................................................................................................ 17 9.3.5.5 Surface Finish ........................................................................................................................ 17 9.3.6 Reinstatement of Concrete Paving Blocks used in Footways, Medians and other Block

Paved Areas ........................................................................................................................... 17 9.3.7 Reinstatement of Kerb lines, Edging Kerbs, etc. ................................................................ 18 9.3.8 Reinstatement of Medians, Verges, Parks, Un-surfaced Graded Roads etc. ................... 19 9.3.9 Reinstatement of Embankment Side Slopes ........................................................................ 19 9.3.10 Reinstatement of Affected Traffic Signal Devices, Sensors, Chambers etc. ..................... 20 9.3.11 Completion of works ............................................................................................................. 20

9.4 NOTIFICATION OF COMPLETION TO ROADS DPCU ......................................................... 20

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9.5 MAINTENANCE ...................................................................................................................... 21

APPENDIX I: SPECIFICATIONS FOR REINSTATEMENT MATERIALS ............................................ 22

1. General ................................................................................................................................... 23 2. Backfill Materials ................................................................................................................... 23 2.1 Clean sand ............................................................................................................................. 23 2.2 Type A Fill (unbound road base material) ........................................................................... 23 2.3 Type B Fill .............................................................................................................................. 23 2.4 Excavated materials .............................................................................................................. 24 2.5 Geotextiles ............................................................................................................................. 24 2.6 Lean mix concrete ................................................................................................................. 26 3. Tack Coat and Prime Coat .................................................................................................... 27 4. Asphalt Concrete Surfacing Materials ................................................................................. 27 4.1 Aggregates General ............................................................................................................... 28 4.2 Coarse Aggregates (imported aggregates) ......................................................................... 28 4.3 Fine Aggregates .................................................................................................................... 28 4.4 Filler ........................................................................................................................................ 29 4.5 Bitumen .................................................................................................................................. 29 4.6 Asphalt Surfacing Mixtures .................................................................................................. 29 4.7 Permitted Variation from Job Standard Mix ........................................................................ 30 4.8 Temperatures for Mixing and Laying ................................................................................... 31 4.9 Density of Compacted Materials .......................................................................................... 31 4.10 Sampling and Testing ........................................................................................................... 32 4.11 Transporting Mixed Materials ............................................................................................... 32 5. Portland Cement Concrete (PCC) Materials ........................................................................ 32 5.1 Cement ................................................................................................................................... 32 5.2 Aggregates for concrete ....................................................................................................... 33 5.3 Sand for concrete .................................................................................................................. 33 5.4 Sand for mortar ...................................................................................................................... 33 5.5 Concrete mixes ...................................................................................................................... 33 5.6 Cement mortar ....................................................................................................................... 33 5.7 Water for mixing and curing concrete ................................................................................. 34 5.8 Admixtures ............................................................................................................................. 34 5.9 Reinforcement ....................................................................................................................... 34 5.10 Pre-cast Concrete Kerbs and Edgings ................................................................................ 35 5.11 Concrete Paving Blocks ........................................................................................................ 35 APPENDIX II: DPCU STANDARD REINSTATEMENT WORK FORMS .............................................. 36 APPENDIX III: REINSTATEMENT OF TRAFFIC DEVICES ................................................................ 40

1. Specifications for Installation of Traffic Signal Vehicle Detection Loops ......................... 41 2. Removal and Replacement of Traffic Signal Pole and Crash Barriers, Telephone Pillars,

Controller bases etc. .............................................................................................................. 46 3. Reinstatement of Traffic Signal Chambers and Joint Boxes .............................................. 48

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9.1 GENERAL 9.1.1 Purpose

The purpose of this chapter of the Code of Practice is to regulate the processes of excavation, backfilling and reinstatement/resurfacing of pits and trenches within roadway corridors.

9.1.2 Definitions

The following definitions shall apply throughout this chapter. Terms not explicitly defined under this clause would be ascribed the meanings common in Civil Engineering Practice.

Roadway: The full extent of the road reservation including carriageways, shoulders, footways, verges, medians, on-street car parking, embankment of elevated roads, approaches to bridge structures and landscaped areas as defined by Royal Decree, by Roads and Highways Code, by other relevant ordinances that may be adopted from time to time, or as limited by existing property boundaries.

Major Road: Major Roads are classified as those roads (Highways and Avenues) included in the most updated version of the List of Roads not to be excavated without permission of H.E. The Minister of Works. This list, which is amended regularly by Roads Projects and Maintenance Directorate, also contains minor roads that are less than 5 years old.

Minor Road: Any road not defined as a major road. It also includes un-surfaced graded roads. Formation: Formation refers to the existing natural sub-grade layer. In the current specifications, the top level of formation represents the interface that separates the road structure from the natural ground. Road Structure: Road structure refers to the total depth of the combined pavement layers that constitute the road. In general, road structure is composed of one, or more, asphalt concrete layer, which is underlain by an unbound road base layer and sometimes a sub-base layer. Narrow Cuts: Any pit or trench that has width of less than 350mm is considered to be a narrow cut. Narrow cuts require special reinstatement procedure as will be tackled in the current specifications. Reinstatement: The refilling and resurfacing of pits and trenches, carried out immediately on completion of works for which they were excavated. Wayleave: Authority to proceed with works in the roadway, on receipt of approval from all the service authorities through a procedure established by the Central Planning Unit of the Ministry of Works. Throughout this specification the term "wayleave" would also mean GSN (General Service Notifications) and/or EWN (Emergency Works Notifications).

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Roads Engineer: The Director of the Roads Projects and Maintenance Directorate or his representative on site. The Roads Engineer shall be responsible for clarification/interpretation of terms appearing in this specification and also for approving/adopting works carried out during the reinstatement of pits, trenches and roads furniture.

9.1.3 Scope

The scope of this chapter shall include all works carried out in the pit or trench, involving cutting and excavation, backfilling and asphalt concrete resurfacing to restore the road to its original condition. Reinstatement of roads furniture (e.g. pavement markings, kerb-line, concrete paving blocks used in footways and other areas) also constitutes part of this scope. Procedures and specifications provided herein shall exclude the method of installation of any plant or utility. The promoter of excavation shall produce a detailed specification for the excluded works, which shall cover all aspects affecting the structural integrity and operational safety of the roadway. No part of the works at the site shall commence until that specification has been approved by the Roads Engineer.

9.1.4 Quality control/Quality Assurance

It shall be noted that the successful implementation of the specifications set herein is contingent upon exercising good quality control and quality assurance practices during construction operations at site. Without this, the specifications will be rendered ineffective in producing the desired performance of the completed works.

9.2 MATERIALS 9.2.1 General

Unless otherwise stated, material specification clauses refer to Appendix I Specifications for Reinstatement Materials (attached). Specifications contained in Appendix I, include materials' definitions, their physical, chemical and engineering properties, and special handling requirements related to their use/placement during construction.

9.2.2 Backfill Materials

In accordance with Clauses 2.1, 2.2, 2.3, 2.4, 2.5, and 2.6 Backfill materials are used in bedding and surround of the installed utility and also for filling trenches/pits up to the level of the underside of the asphalt concrete surface.

9.2.3 Tack Coat and Prime Coat

In accordance with Clauses 3.1 & 3.2 Tack coat is applied between successive asphalt concrete surface layers to ensure proper bondage between these layers. It is also applied to exposed asphalt concrete cut faces, kerb surfaces and concrete surfaces receiving asphalt. Prime coat is applied at the interface between the unbound road base layer and the first asphalt concrete layer overlying the road base.

9.2.4 Asphalt Concrete Surfacing Materials In accordance with Clauses 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 4.10 and 4.11 Asphalt concrete materials include material constituents and mixes made out of these constituents that are used to restore the asphalt concrete surface to its original condition.

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9.2.5 Portland Cement Concrete (PCC) Materials In accordance with Clauses 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 5.10 and 5.11 PCC materials include material components that are used in manufacturing pre-cast concrete kerbs and edging and concrete paving blocks. These elements, and others of the like, constitute part of the road furniture that need be restored upon completion of the road reinstatement work.

9.3 WORKMANSHIP 9.3.1 General

Workmanship referred to in this chapter includes the set of procedures that must be followed during cutting and excavation, backfilling, and reinstatement of pits and trenches that are made in both paved and unpaved surfaces. No work shall commence unless a valid "wayleave" approval exists and a copy is present on site. The "wayleave" must be approved by all service authorities (this should also include agencies that are not explicitly listed in the wayleave, such as Bapco, BDF, etc.) and must be endorsed by both General Directorate for Traffic and Municipality, and all conditions must have been met.

9.3.2 Traffic Safety

Work shall not commence until appropriate steps have been taken to warn and safeguard vehicular and pedestrian traffic. Temporary signs, barriers etc. shall be in accordance with the booklet Traffic Control at Roadworks published and regularly amended by the Ministry of Works. All traffic Diversion schemes shall comply with clauses in Chapter 8 of COPSI. Traffic signs, barriers etc. shall be maintained in good and clean condition throughout the works. If continuing works require amended or extended signing, this shall be subject to the provisions of this clause. In the case of deep excavations, concrete barriers or a double set of plastic barriers shall be placed in front of the sheet piles that are used to support the sides of the excavation. Permanent road signs shall not be removed or covered without the specific permission of Traffic Engineering Section of Roads Planning and Design Directorate (RPDD). Where such permission is granted, the road signs shall, if required by RPDD, be temporarily re-sited in an approved manner. On completion of the works, any temporarily re-sited signs shall be restored to their original location unless the works render this impossible and is agreed to by RPDD.

9.3.3 Pavement Cutting and Excavation 9.3.3.1 General

(i) Before an excavation is commenced, the Contractor shall prepare a record of the state of the surface, which shall detail ground levels, all features that may require reinstatement such as speed humps/tables, studs, bollards, sign boards, kerbs alignment, and as much information as possible about surface and underground drainage. This record shall be kept and updated as the excavation process progresses and hidden features unveiled. A DPCU standard form, which shall be used to record this information, is attached in Appendix II. Digital photographic records shall be taken where so required by the Roads Engineer, especially to record any existing pre-excavation damages.

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(ii) Excavation may be carried out manually or, where services permit, mechanically. Where mechanical excavators are used, precautions shall be taken to avoid damage to adjacent asphalt surfaces by tracks, jacking plates, bucket teeth or any other means. Pits and trenches should only be large enough to accommodate the installation under construction together with adequate working space for backfilling/reinstatement operations. They should not, however, have a width less than 500mm to allow for mechanical compaction of backfill.

(iii) For underground structures, there shall be a minimum clearance of 500mm all-around the subject structure to allow for mechanical compaction of backfill.

(iv) Sides of excavation must be made and kept vertical; battering of sides would not be permitted without the written permission of the Roads Engineer.

(v) Turf, topsoil, paving and other surfacing materials shall be stripped separately from the subsoil and stored separately for re-use or disposal, as directed by the Roads Engineer.

(vi) Excavated subsoil materials required for re-use shall be stored, in such a manner, so as not to interfere with the safe passage or amenity of the General Public. Excavated subsoil materials not required for re-use must be removed from the site and disposed off immediately.

(vii) Laying of services across major roads would not be permitted by open excavation (unless technically judged as safe and endorsed by the Roads engineer). Non disruptive tunneling, thrust boring or other suitable non destructive methods, as approved by the Roads Engineer must be used in such cases.

(viii) Use of explosives for any purposes will not be permitted. 9.3.3.2 Support to Excavations

(i) Excavations shall be adequately supported at all times to the satisfaction of the Roads Engineer to prevent any ground movement, which could diminish the width of the trench, cause injury or delay or endanger adjacent services, structures or road surfaces.

(ii) Supports shall be properly maintained until the permanent work is sufficiently advanced to permit their removal and shall be left in if specified or instructed by the Roads Engineer.

(iii) Trench supports shall be so arranged to permit withdrawal during the placing of the pipe bedding so as to prevent voids.

9.3.3.3 Dealing with Ground Water

(i) All excavations shall be kept free from water. In this respect, the Contractor's attention is drawn to the very high water table throughout much of Bahrain and the relatively high permeability of much of the strata.

(ii) Arrangement for the disposal of water shall not jeopardize the stability of any structures. (iii) Pumping of water into drainage or sewerage systems either directly or indirectly shall not be

carried out without the appropriate permit as described in Chapter 3 of the Code of Practice for Service Installation. All procedures proposed by the Contractor to dispose of ground water must be approved by the Roads Engineer prior to their use.

(iv) Dewatering methods may include temporary drains, intercepting ditches, cut-off drains, sub-drains, sumps, wells pumps, well-points or other dewatering equipment and shall include all other materials and equipment necessary to keep surface water and ground water out of the excavation. The water table shall be maintained at least 300mm below formation level continuously until construction therein has been completed to ensure that no damage due to floatation, hydrostatic uplift or other causes.

(v) All necessary precautions shall be taken to prevent any adjacent ground from being adversely affected by loss of fines through any dewatering process. Silt traps shall be provided on pumped ground water discharges where directed by the Roads Engineer.

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(vi) Unless otherwise agreed by the Roads Engineer, all well-points, sub-drains, sumps and similar temporary works shall be kept clear from the permanent works and when they cease to be used shall be finally filled with compacted load bearing fill material, grout, or sealed with concrete at intervals to the level of the underside of the permanent works. Particular care should be taken to avoid undermining any part of the new or existing works due to the method adopted for the removal and disposal of water.

(vii) No pipes or culverts in the new or existing works shall be used for the removal and disposal of water without the written permission from the Roads Engineer. Should such permission be given, the Contractor shall be responsible for cleaning out and removing all silt, etc. and for making good any damage whatsoever resulting from such use.

(viii) The Contractor shall not allow water arising from his works to discharge on to areas of open ground.

9.3.3.4 Pavement Cutting Guidelines

The objective of pavement cutting guidelines is to produce an aesthetic and sound cutting procedure that will not adversely affect adjacent roadway sections. Cutting process shall follow the guidelines given below:

(i) Pavement cutting shall be performed in straight lines whenever possible. (ii) The approximate asphalt cutting area is to be demarcated and cut by saw cutter to unbound

base course level to prevent damage to adjacent asphalt during asphalt excavation and lifting. In the case where such equipment is not available, cutting can be performed using a pneumatic pavement breaker (jackhammer). In such case, however, extreme care should be exercised in order to prevent damage to adjacent existing asphalt.

(iii) Saw cutting shall be stopped at or just short of the corners of the demarcated cut area to avoid over-cutting, which may lead to propagating cracks in the future.

(iv) After cutting the edges of the trench, removal of asphalt concrete pieces from within the cut area shall be performed with care to avoid lifting and breaking the roadway pavement beyond the cut borders.

(v) Unless judged unfeasible, the excavated area shall have a maximum of four sides that are parallel and perpendicular to the direction of traffic.

(vi) Whenever a side of a cut is parallel to and coincides with a wheel path, the pavement should be cut back 300mm beyond the originally planned cut edge. Determination of the location of the wheel path is left to the judgment of the Roads Engineer.

(vii) Whenever a side of a cut falls within 450mm of an existing joint, an isolated crack or an enclosure (e.g. manhole) and the wheel path falls in between, the pavement cutting shall be extended to that joint, crack or enclosure.

(viii) Whenever a side of a cut falls within 500mm from a kerb line/edge line of asphalt, pavement cutting shall be extended to the kerb line.

9.3.3.5 Excavation Guidelines

(i) Excavation shall begin only after satisfying all pavement-cutting requirements (Clause 9.3.3.4).

(ii) Excavation shall be conducted in a manner so as to avoid lifting and damaging road sections adjacent to the trench/pit. In the event lifting occurs, cutbacks shall be performed to remove affected areas.

(iii) Pavement protection measures shall be properly deployed when excavating using mechanical equipment such as backhoes. Wood or rubber shall be placed on the road under stabilizers to prevent breaking or chipping of the road surface. The use of equipment supported on steel tracks shall be avoided to prevent damage to the road caused by movement of this type of equipment.

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Figure 1b: Stage 1 Backfill below undercut

Figure 1c: Stage 2 Remove hanging AC part above undercut & continue backfill

(v) When the extent of sloughed area (dimension "e" shown in Figure 2a) exceeds 300mm, a

corrective measure is required depending on the depth of sloughed area (dimension "d" in Figure 2a) below the road surface. If sloughing is at a shallow depth (d 450mm), one of two alternatives is considered:

i. Alternative 1: Extend excavation to the road surface to remove material above the sloughed location as shown in Figure 2b.

ii. Alternative 2: Use wet lean concrete mix to occupy the sloughed location following the two steps shown in Figure 2c.

If sloughing is at a deep location (d > 450mm), no special action is required. However, special attention shall be given to compaction of the material used to fill the sloughed area.

Figure 2a: Sloughing

Figure 2b: Alternative 1 for rectifying sloughing

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Figure 2c: Alternative 2 for rectifying sloughing

9.3.4 Backfilling 9.3.4.1 General

(i) For verges, medians and graded (unpaved) roads, backfilling of trenches shall be brought up to ground level. Where the ground surface on the line of the trench consists of sweet soil, the upper section of the backfill shall be sweet soil of the thickness described, or the same thickness and quality of soil as the surrounding ground.

(ii) For trenching in carriageways or other paved areas, backfilling operations involve the refilling of the excavated cut from the level of pipe/cable bedding and surround to just below the underside of the most bottom asphalt concrete layer (in the case of multi AC layers).

(iii) Backfilling, shall, wherever practical be undertaken immediately after the specified operations preceding it have been completed. The materials specified in Appendix I (clauses 2.1 to 2.6), shall be deposited in layers and compacted in accordance with the procedures of refilling excavations detailed below. Care should be taken to compact the material evenly without dislodging or damaging the installed pipes.

(iv) Procedures that govern backfilling of pits and trenches in roadway corridors are dictated by two factors:

a. Category of road in which trenching was performed (major versus minor roads). b. Size of cut/trench (wide versus narrow).

9.3.4.2 Bedding, Laying and Surrounding of Pipes and Cables

(i) Immediately following the inspection of the excavated trench/pit (as described in Clause 9.3.3.6), bedding material conforming to the specifications set in Appendix I: Clause 2.1 shall be laid and compacted to 95% maximum dry density (MDD) as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(ii) After the pipe/cable is being laid on the bed and the pipeline is tested, the completion of bedding and surrounding of the pipe is to be carried out immediately. The bedding and surround shall be brought up equally on both sides of the pipe, ensuring that it is in contact with the underside of the pipe barrel, and be carefully compacted in layers not exceeding 150mm thickness. The material used in pipe/cable surround should comply with the specifications set in Appendix I: Clause 2.1.

(iii) For rigid pipes, the compacted surround backfill shall be taken up to a height of 300mm above the top of the pipe barrel. For flexible pipes, the surround shall extend to 150mm above the top of the pipe barrel.

Step1 Backfill

Step 2 Wet Lean

Concrete mix

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9.3.4.3 Backfilling Procedure for Trenches in Major Roads (carriageways, hard shoulders and street car parking) Backfilling of trenches made in roads designated as major roads (see Clause 9.1.2: Definitions) shall adhere to the following procedure:

(i) The first 600mm depth immediately below the underside of the asphalt surface shall be backfilled with Dry Lean Mixed Concrete (as specified in Appendix I: Clause 2.6) placed in layers not exceeding 150mm per layer and compacted to 95% of the Standard Wet Density (as defined in clause 2.6.11 of Appendix I).

(ii) The next 300mm depth shall be backfilled with Type A Fill (as specified in Appendix I: Clause 2.2) watered to its optimum water content and compacted in layers not exceeding 150mm per layer to achieve 98% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(iii) The remaining depth up to the pipe/cable surround shall be backfilled with approved Type B Fill (as specified in Appendix I: Clause 2.3), placed in layers not exceeding 200mm loose lift thickness and compacted to achieve a final thickness of 150mm. Each compacted layer shall achieve a field density equal to or greater than 95% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(iv) Compaction of all backfill layers shall be certified by a representative of the Utility Authority originating the works. A copy of this certificate shall be presented to the inspecting Roads Engineer prior to asphalt reinstatement.

(v) When working around manhole structures, adequate working space of a minimum 500mm must be maintained at all times for ease of compaction operations. In the case when this is not feasible, the whole area shall be backfilled with Wet Lean Mixed Concrete, which should be watered to its optimum water content and then discharged at site as slurry that compact under its own weight.

9.3.4.4 Backfilling Procedure for Trenches in Minor Roads

Backfilling of excavated pits and trenches in minor roads (see Clause 9.1.2: Definitions) shall proceed as follows:

(i) The first 300mm depth immediately after the underside of asphalt surface shall be backfilled with Type A Fill (Appendix I: Clause 2.2) watered to its optimum water content, placed in layers not exceeding 200mm loose lift thickness and compacted to achieve a final thickness of 150mm. Each compacted layer shall achieve a field density equal to or greater than 98% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(ii) The remaining depth up to the pipe/cable surround shall be backfilled with approved Type B Fill (Appendix I: Clause 2.3) watered to its optimum water content, placed in layers not exceeding 200mm loose lift thickness and compacted to achieve a final thickness of 150mm. Each compacted layer shall achieve a field density equal to or greater than 95% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(iii) Use of excavated materials in backfill operations will only be permitted as a substitute for Type B Fill if the excavated material is tested and found to conform to the specifications set for Type B Fill (Appendix I: Clause 2.3). In such case, the Contractor should submit to the Roads Engineer records of test results showing conformance prior to the use of the material.

(iv) Compaction of all backfill layers shall be certified by a representative of the Utility Authority originating the works. A copy of this certificate shall be presented to the inspecting Roads Engineer prior to asphalt reinstatement.

(v) When working around manhole structures, adequate working space of a minimum 500mm must be maintained at all times for ease of compaction operations. In the case when this is not feasible, the whole area shall be backfilled with Wet Lean Mixed Concrete, which should

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be watered to its optimum water content and then discharged at site as slurry that compact under its own weight.

(vi) For narrow trenches (width 350mm), the full depth of the trench shall be backfilled with Wet Lean Mixed Concrete.

9.3.4.5 Testing of Backfill

(i) The Contractor shall provide testing apparatus and carry out tests as is necessary for the monitoring of backfilled soil properties. He shall maintain a daily log of tests carried out and provide the Roads Engineer with a copy of the log to be countersigned by the Roads Engineer.

(ii) Tests to determine the dry density/moisture content relationship (as per method 3 of BS 1377: Part 4:1990) and in-situ density and moisture content (as per method 2.2 or 2.5 of BS 1377: Part 9: 1990) shall be carried out as directed on site by the Engineer. The frequency of testing will depend on the consistency of material and test results but unless otherwise instructed or agreed to shall be as follows: (a) dry density/moisture content relationship - one test per 150m of trench (b) dry density and moisture content of compacted soil - 10 tests per 150m of trench

per compacted layer of 150mm (iii) When testing for field density for each compacted layer, at least 9 out of every 10 locations

tested shall achieve the target density (whether 98% or 95% MDD). (iv) Prior to the commencement of excavation, the Contractor shall submit to the Roads

Engineer for approval a method statement for testing backfill. This statement shall include details of: (a) the methods and equipment proposed for measuring density/moisture content

relationship, in-situ density and moisture content (including sources of pouring sand where required for the sand replacement method);

(b) the name and address of any proposed independent testing laboratory. 9.3.4.6 Special clause: Backfilling below Formation level

(i) When excavation work extends below the top level of formation (i.e. bottom of road structure), a geotextile filter fabric shall be used to separate the new backfilled material from the material that naturally exists at that level.

(ii) The depth through which the use of the filter fabric is deployed shall extend from the bottom of the trench and up to 300mm above the top level of formation.

(iii) The required physical, mechanical and hydraulic properties of filter fabrics shall be as specified in Appendix I: Clause 2.5.

(iv) The geotextile material shall be supplied in roles to widths to suit the work. (v) After excavation and trimming to the required profile, the filter fabric shall be unrolled over

the prepared formation and care should be taken to ensure that the material is dressed well into the sides and bottom of the trench so that subsequent placement of the backfill material does not impose a strain on the fabric or cause it either to tear of pull away from the trench sides leaving voids. Joints or laps between successive sheets of the geotextile shall be formed in accordance with the manufacturers instructions.

(vi) Continuation of backfilling above the depth at which the fabric filter is installed shall then follow the procedures described in Clause 9.3.4.3 or Clause 9.3.4.4 as appropriate.

9.3.4.7 Surface preparation prior to asphalting

(i) Prior to reinstating the asphalt concrete surface, the edges of the existing surface shall be cut back to give a regular shaped, straight sided area free of deformed or cracked surfacing that was affected by trenching work. The cut back shall be at least 150mm outside all edges of the excavation. The surfacing shall be cut by a saw or by pneumatic or hydraulic breaker

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to give a vertical clean edge. The edges of reinstated areas are required to be either parallel or perpendicular to the direction of traffic flow.

(ii) The area to be reinstated shall then be shaped and compacted to 98% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990. Any excess fines, loose materials and windblown dust shall be removed and the surface be made clean.

(iii) The prepared surface shall be treated with a prime coat of Road Oil (see Clause 3.2 in Appendix I), sprayed at a rate of between 0.7 1.0 l/m2. The Road oil is to be applied uniformly by the use of a hand operated pump spray apparatus unless the use of vehicular tank-spraying pressure unit complying with BS 1707 is specifically instructed by the Roads Engineer in writing.

(iv) Care shall be taken to protect the surfaces of all structures such as kerbs from being marred or defaced during the application of the prime coat.

(v) On completion of the spraying operation, the area primed shall be closed to traffic for a period sufficient to allow for proper penetration and curing.

(vi) Exposed faces of existing asphalt surfacing and all exposed concrete surface within the excavated trench shall be painted with hot bitumen or tack coat.

9.3.5 Reinstatement of Asphalt Concrete surface 9.3.5.1 General

(i) The asphalt pavement is to be reinstated to its original thickness as per the guidelines given in Table 1 below and would include one layer of 50mm thick wearing course of TM5 and appropriate number of base course layers of B28 mix (see Appendix I: Clause 4.6). Asphalt should be obtained only from Ministry of Work's approved supplier(s). Mix type is subjected to regular amendment and up to date mix design must be obtained from Roads Engineer before start/tendering of projects.

Table 1: Reinstated asphalt concrete thicknesses Original Thickness Reinstated thickness Less than 50mm 50mm Between 50mm to 75mm 75mm Above 75mm (for major roads) Original thickness. Above 75mm ( for minor roads) Original thickness to a maximum of 125mm

(ii) For major roads and minor roads less than five years old, the laying of the asphalt concrete

wearing course shall extend over the full width of all affected traffic lanes by cold milling the additional pavement areas and placing asphalt using a mechanical paver.

(iii) For minor roads older than five years, irregular shaped (stepped or L-shaped) reinstatement is not permitted unless the length of each step is not less than 15 meters and offset of each step is not less than 300mm (except around manhole structures).

(iv) For minor roads older than five years, the reinstatement area should be located at a minimum clearance of 500mm from the edge of kerb line/asphalt edge, building line, or adjacent reinstatement. If minimum clearance cannot be maintained then the reinstatement should be extended to the edge. All manholes to be constructed in the carriageway are required to be reinstated full lane width or if the trench affects both lanes full road width reinstatement is required. Manhole levels shall be kept flush with the road level.

(v) Trenches made in car park areas of major roads and minor roads less than 5 years old shall be reinstated over the full width of the affected area and asphalt is required to be placed using a mechanical paver machine only.

(vi) Trenches in footways shall be reinstated over the full width of the affected length of the footway and by using paving blocks only if the length of excavation exceeds 10 meter. For

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length less than 10 meters, full width reinstatement with asphaltic concrete matching with existing thickness is required. Procedure for reinstating footways using paving blocks is described in Clause 9.3.6.

(vii) All street furniture, including road marking and studs etc. removed during the course of works are required to be replaced immediately following completion of the reinstatement.

(viii) Disturbed kerb-lines, edging kerbs etc. shall be reinstated using the procedure described in Clause 9.3.7.

(ix) Disturbed medians, verges etc. shall be reinstated using the procedure outlined in Clause 9.3.8.

9.3.5.2 Laying and Compaction

(i) Asphalt surfacing shall be laid at a temperature in accordance with Clause 4.8.2 as specified in Appendix I.

(ii) Asphalt mixes, prepared as per the specifications given in Clause 4 in Appendix I, shall be placed in layers of thickness not exceeding those given in Table A-8 and shall be spread using a mechanical paver. The use of manual methods (heated shovels and rakes) will only be permitted for trenches made in minor roads older than five years and where the width of the reinstatement is less than the full width of the traffic lane.

(iii) Where manual (hand) spreading and tamping is allowed in accordance with the foregoing clause, the mixed material is to be dumped on delivery upon an existing hard clean surface or on approved metal sheets outside the area where it is to be spread and it is to be distributed into place immediately by means of a hot shovel. It is to be spread with hot rakes in a uniformly loose layer to the full depth required. Raking shall be minimized to avoid segregation of the asphalt mix constituents.

(iv) Each course of bituminous material is to be adequately and uniformly compacted at temperatures not less than those specified in Clause 4.8.2 in Appendix I.

(v) Compaction of asphalt concrete layer courses shall be carried out using approved compaction equipment which has been shown capable of obtaining density of not less than 98% of the "Job Standard Mix Density" defined as described in Clause 4.6 (Appendix I). The use of Nuclear Density gauges (as per Method 2, Clause 2.5 in BS 1377: Part 9: 1990) shall be adopted to ensure the achievement of the required density.

(vi) In multi-layer construction of asphalt concrete surfacing, tack coat is to be applied uniformly by vehicular, mechanical, tank-spraying pressure units complying with BS 1707 as appropriate, at a spread rate of 0.2 0.5 l/m2. Tack coat shall not form ponds in hollows and shall be allowed to break before next layer of asphalt is laid. Where the shape or size of the area of the reinstated trench precludes vehicular access then, with the approval of the Roads Engineer, hand pressure spraying equipment will be permitted.

(vii) With the exception of necessary construction vehicles, traffic is not to be allowed on the tack coat.

(viii) Care shall be taken to protect the surfaces of all structures such as kerbs from being marred or defaced during the application of the tack coat.

(ix) If instructed by the Roads Engineer, the Contractor shall submit for approval, a certificate of test from an independent test authority not more than three months old, showing that the uniformity of distribution from the spray bar of each vehicular mechanical tank-spraying unit meets the requirements of the appropriate British Standard. If instructed by the Roads Engineer, the distributor shall be checked at least once in every month to ensure consistent rates of spread, and the certificates submitted to the Roads Engineer.

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9.3.5.3 Joints In reinstating trenches over the full-width of one or more traffic lane(s), treatment of longitudinal and transverse joints should follow the procedure described below:

(i) The width of spread shall be such as to provide for the off-setting of longitudinal joints in multi-layer construction by a minimum of 300mm.

(ii) Longitudinal joints of asphalt concrete base and wearing courses shall be trimmed as vertical as possible by mechanical or manual means to be approved by the Engineer.

(iii) Transverse joints of both asphalt concrete base and wearing courses shall be cut back sufficiently to ensure correct profile, thickness and compaction of the joint. This will also apply to joints to existing pavements. Bases courses and wearing courses are to be laid to break transverse joints by at least 600mm.

(iv) The exposed edges of the frames of manhole covers, gully gratings, kerbs and similar projections against which the new pavement will abut, are to be thoroughly cleaned and coated with bitumen. The new pavement is then to be tamped around and against the projection to such a depth that, on completion of compaction, the finished surface of the wearing course is level with the top of the projection. Paved areas are to be dished to the frames of gully gratings, etc. with the dishing being formed in both courses of two-course construction.

9.3.5.4 Opening Road to Traffic

(i) Asphalt layers shall not be opened to traffic until the asphalt temperature of the final layer, measured at the surface is 400 C.

(ii) Traffic shall not be permitted on final layer of asphalt until the reinstallation of all road markings that was disturbed due to trenching works, has been completed at the expense of the promoter of the excavation.

9.3.5.5 Surface Finish The completed surface of the asphalt reinstatement shall not deviate by more than 5mm from a straight line between the edges of the adjacent existing asphalt.

9.3.6 Reinstatement of Concrete Paving Blocks used in Footways, Medians and other Block Paved Areas Where excavations are made in footways, medians and other block paved areas, reinstatement of the affected paving blocks area shall be carried out as per the following procedure (this is to be implemented after backfilling the trench as per clause 9.3.4.4, while keeping the compacted thickness of Type A material as 150mm instead of 300mm):

(i) Care should be exercised not to damage any blocks while removing and any damaged one is to be replaced with a new one of matching pattern, quality, size and color. The blocks shall be removed by hand.

(ii) Each paving block shall be cleaned individually to remove sand and other foreign materials deposited on its surface especially at the bottom surface before reusing. Sides of the existing block paved surface at edges shall be cleaned thoroughly of any foreign materials, sand etc.

(iii) Immediately prior to preparing the sand bed for the reinstatement of the blocks, two additional rows of blocks shall be removed from the edge of the excavated area. The remaining existing sand bed shall be cut back and carefully removed and the caked sand shall be scraped from the exposed blocks' edges.

(iv) Fresh sand shall be laid to approximately two thirds of the target finished thickness and fully compacted with a plate compactor to a level, which is below the adjacent existing compacted sand. The plate compactor shall have a plate area of not less than 0.25m2 and

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be capable of transmitting an effective force of 75 kN/m of plate at a frequency of vibration in the range 75 100 Hz. Additional un-compacted sand shall then be spread over the area and trimmed to stand slightly proud of the underside of the adjacent existing blocks. A notched screed board may be used for this purpose. Where the blocks lie in the carriageway, a slightly cambered profile shall be formed to counter any tendency for the laying course to settle with trafficking. Generally, the loose sand will be higher by 6mm at the edges and 12mm at its centre where a cambered profile is used.

(v) The blocks shall then be put into place in the bond pattern of the surrounding area ensuring that the joints remain wide enough for sand filling. As a guideline, a space of 2mm between each two adjacent blocks is to be left to enable penetration of the joint filling sand. The blocks will be placed in position and not tamped down in any way except when the final blocks are laid, when a rubber hammer may be used to lightly tap them into place. Only whole blocks may be used. Cut blocks will not be permitted except adjacent to obstructions or projections.

(vi) Where pavement areas abut to kerbs, edge restraints, iron works, road signs etc. the blocks shall be cut to fit any resultant spaces. Any residual gap less than one third the plan area of a whole block may be filled with matching masons mortar of matching color and with chamfers shaped to suit. Cut edges of blocks shall have appropriate matching chamfers formed prior to incorporation in the works.

(vii) When the blocks have been re-laid and bonded to the existing pavement on either side of the trench, the surface course shall be fully compacted using a plate compactor as described in Clause 9.3.6.iv above. The compaction must be carried out as soon as possible after laying but not within one meter of any unrestrained edge of the pavement. Apart from this edge strip, no paving block will remain un-compacted at the end of any day's work.

(viii) After compaction of the surface course, dry silica sand complying with the grading for jointing sand shall be spread over the surface and brushed into the joints. A material which would stain the block must not be used. The block paving area shall then be re-vibrated using the plate compactor and the surface sanding and vibration repeated until complete filling of the block to block joints is achieved. Surplus sand shall only be removed prior to trafficking.

(ix) The final surface shall be within 5mm of the true surface level when measured under a 3m straight edge and the surface of the adjacent blocks shall not show any difference in level in excess of 2mm.

(x) At suitable intervals during contract period, to be decided upon by the supervising engineer, and also at the end of the defects liability period, extra sands shall be spread on the surface and shall be vibrated so that the joints shall remain filled.

9.3.7 Reinstatement of Kerb lines, Edging Kerbs, etc.

Where excavations cross kerb lines the following procedures should be observed: (i) Kerbs shall be removed carefully and stored for reuse. (ii) Concrete backing and foundation shall be broken out over the extent of the works. (iii) On completion of backfilling, the kerb foundation shall be recast using concrete class

C45/20 (see Appendix I: Clause 5.5), and incorporating 12 mm diameter dowel bars 200 mm long, equally spaced, two behind each kerb.

(iv) Kerbs shall be re-laid and bedded in a layer of Class 1 mortar, not less than 10mm and not more than 40mm thick.

(v) Any expansion joint encountered should be made good as found and all other joints should be pointed with Class 1 mortar if the existing kerbs were so pointed.

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(vi) Kerbs shall be backed with concrete class C45/20. (vii) For radii of 12m or less, precast radius kerbs as per BS7263 shall be used. i.e. 1m, 2m, 3m

, 4.5m, 6m, 7.5m, 9m, 10.5m & 12m. Use of half kerbs shall be at the discretion of Roads Engineer if existing radius is non-standard or the pre-cast radius kerbs are unavailable.

(viii) Any unit of kerbs and edging deviating more than 3mm in 3m length from line and level shall be made good by lifting and relaying correctly.

(ix) On completion of reinstatement of kerbs, all exposed rear surfaces shall be treated with two coats of approved bituminous paint.

(x) Overall, the kerb reinstatement shall comply with the Standard Road Construction Drawings SRCD 10.02 and 10.03.

9.3.8 Reinstatement of Medians, Verges, Parks, Un-surfaced Graded Roads etc.

(i) When part of the trenching work involves medians, verges, un-surfaced graded roads and/or park areas, the excavation shall be backfilled up to the surface level/underside of sweet soil level.

(ii) Each backfilled layer shall achieve a compacted field density equal to or greater than 95% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990.

(iii) Where verges, medians etc. are cultivated, no plants, shrubs or trees shall be removed without explicit permission of the Ministry of Municipalities and Agriculture.

(iv) In cultivated areas and parks, topsoil and sweet sand dug during excavation shall be carefully laid aside to be reused upon completion of the reinstatement work. The surface to be top soiled shall be loosened to a depth of 200mm and topsoil replaced on it to the specified depth without compaction. The Contractor shall import additional topsoil required to make up any deficiency.

(v) Areas where grass is to be sown, shall be worked to a fine tilt, leveled, graded and rolled with a light roller. The seed shall be sown evenly at the specified rate of application in the proper season and in suitable weather conditions. Restoration and re-seeding of any areas where the new grass in unsatisfactory or inadequate shall be carried out by the Contractor as instructed. Newly sown grass shall be regularly watered and shall receive at least one cutting.

9.3.9 Reinstatement of Embankment Side Slopes

(i) Steep embankments are defined as those having side height equal or greater than 1.50 meters and side slope of more than 450.

(ii) Excavation on the side slope of steep embankment is generally not permitted. However, where such situation is unavoidable, prior approval from the Roads Engineer must be obtained in writing. The Roads Engineer, at his discretion, may approve the excavation based on analyzing the risk factor that the excavation may pose to the stability of the embankment.

(iii) During backfilling of the approved excavation, the surface width of each backfilled layer is required to be widened to provide a surface width on top of filled layers of not less than the width of the compacting equipment or 350mm, whichever is greater. After completion of backfilling of all layers, the surface of the embankment side slope is required to be trimmed to match with that of the existing embankment slope. Each compacted layer shall achieve a field density equal to or greater than 95% MDD as determined in accordance with method 3 of BS 1377: Part 4: 1990. The most top layer shall achieve 98% MDD or greater.

(iv) The top most compacted layer of the reinstated surface of the side slope is required to be protected by rock armor protection/cement sand mortared stone pitching as specified in Clause 622 of the General Specification for Roadworks issued by the Ministry of Works (revised September 1997).

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9.3.10 Reinstatement of Affected Traffic Signal Devices, Sensors, Chambers etc. (i) When part of the trenching work affects existing traffic signal loops and sensors, the

affected items shall be removed and replaced as per the specifications given in Clause 1 in Appendix III.

(ii) When part of the trenching work affects existing traffic signal poles and surrounding crash barriers etc., the affected items shall be removed and replaced as per the specifications given in Clause 2 in Appendix III.

(iii) When part of the trenching work affects existing traffic signal chambers and joint boxes, they shall be rebuilt as per the standard drawing given in Clause 3 in Appendix III.

9.3.11 Completion of works

(i) All reinstatement works shall proceed expeditiously and immediately upon completion of service installation. All reinstatement works including backfilling and final layer surfacing must be completed within the time limits indicated in the following table:

Table 2: Permitted time for completion of reinstatement work Length of the excavation Maximum time to be taken for

reinstatement 1 to 10 Meters One day 11 t0 50 Meters Three days Above 50 Meters In stages with prior approval from Roads

DPCU (ii) No part of the trench would be opened to traffic without completing final layer reinstatement.

Where this is unavoidable due to traffic movement, it may be opened to traffic provided that the trench section would be covered with steel plates of sufficient thickness to safely bear the traffic load. Steel plates shall firmly be fixed to the ground to prevent movement under wheels and final layer reinstatement shall be completed within the time limits specified in 9.3.9. i.

(iii) Written permission from Roads Damage Prevention Control Unit (DPCU) would be required for temporary opening of un-surfaced trenches to traffic.

(iv) The time limits listed in clause 9.3.9.i must be complied with for all excavation works in public roads. The following punitive measures will be taken against violators of these requirements:

a. Issuance of warning letter upon first violation. b. Temporary suspension for a month from doing any excavation in public roads if

violation is repeated. c. Recommendation to the concerned Utility to permanently suspend the contractor if

repeated violations are observed. 9.4 NOTIFICATION OF COMPLETION TO ROADS DPCU

(i) On completion of entire reinstatement work under a project, the promoter Utility shall notify Roads Damage Prevention Control Unit by submitting a standard asphalt/block paved area reinstatement form (Form 2 in Appendix II).

(ii) On submission of asphalt inspection form, work on that project would be deemed to be complete and no further excavation/reinstatement work would be allowed under this wayleave. Any further work including rectification would be presumed as a new work and hence a new inspection form has to be issued.

(iii) No final payment shall be made without satisfactory initial inspection of the reinstatement by the Roads Engineer.

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9.5 MAINTENANCE

(v) The reinstatement work described in this Specification shall be placed under a defects liability period as stated in Promoter Utility specifications starting from the day of completion of the reinstatement. During this period, the Consultant/Contractor who performed the original work will be retained as the sole party responsible for carrying out all maintenance activities (at his own cost) related to the completed work. Upon satisfactory completion of the defects liability period, Roads Projects and Maintenance Directorate would adopt the reinstatement work and will take over any future maintenance responsibilities except for large scale failures due to non adherence to specification in relation to materials and workmanship.

(vi) No retention money at the end of the defects liability period shall be released without final adoption of the reinstatement work by Roads Engineer.

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Appendix I: Specifications for Reinstatement Materials

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1. General Reinstatement materials referred to in this appendix include all materials used in backfilling

operations as well as materials used to restore the asphalt concrete road surface. Specifications for these materials together with special handling requirements related to their use/placement during construction are given in various sections of this appendix.

2. Backfill Materials

Backfill materials include materials used as bedding and surround to the installed utility and materials used in filling trenches/pits up to the level of the underside of the asphalt concrete surface/paved blocks surface. Various material types that are permitted for use in backfilling are described in this appendix. The use of a particular material type depends on the road category, in which the excavation is made, the depth of the excavated layer and constraints existing on site. Specifications for backfill materials are contained in Clauses 2.1 to 2.6.

2.1 Clean sand Clean sand shall be used as bedding and surround material around the installed utility. When placed, this material should be properly compacted to specified field density. The material can either be desert or marine sand and shall be thoroughly washed and screened to be free from organic and other deleterious materials. The material shall be non-plastic, of maximum size 5mm and contains no more than 10% fines passing the 75 micron sieve. The soluble sulphate content in the material shall not exceed 2 g of sulphate (as SO3) per litre when tested in accordance with Method 5 (clause 5.3) of BS 1377: Part 3: 1990.

2.2 Type A Fill (unbound road base material) 2.2.1 Granular Type A fill material shall be good hard well graded material, screened and crushed

as necessary to lie within the grading envelope given in Table A-1 when tested in accordance with Method 9 (clause 9.2) of BS 1377: Part 2: 1990. The material shall not have a plasticity index (PI) of more than 6%. Table A-1: Gradation specifications for Type A Fill BS Sieve Size 37.5 mm 20 mm 5 mm 600

micron 75 micron

Percentage passing by weight

95 100

50 75

25 50

8 30

0 10

2.2.2 The CBR of the material when tested at field density and in accordance with Method 7 of BS 1377: Part 4: 1990 shall not be less than 80%.

2.2.3 The water soluble salt content shall not exceed 2% (or 2 g of sulphate per litre). 2.2.4 The material shall be delivered in trucks covered by heavy tarpaulin or other suitable covers

and must be securely fastened to prevent dust nuisance in transit. 2.3 Type B Fill 2.3.1 Type B fill shall be clean, hard, granular material free from clay and deleterious substances.

The total soluble salts shall not exceed 2% and the grading of the fill shall lie within the envelope given in Table A-2 when tested in accordance with Method 9 (clause 9.2) of BS 1377: Part 2: 1990. The fine portion of the material passing the 75 micron sieve shall not have PI of more than 8%.

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Table A-2: Gradation specifications for Type B Fill BS Sieve Size 10 mm 5 mm 75 micron Percentage passing by weight

100

15 50

0 15

2.3.2 The material shall have a CBR of not less than 20% when tested at field density and in accordance with Method 7 of BS 1377: Part 4: 1990.

2.4 Excavated materials 2.4.1 Excavated materials dug out from trenches/pits are categorized as either suitable or

unsuitable for use as backfill materials. 2.4.2 Suitable excavated materials shall lie within the gradation envelope of Table A-2 and shall be

sorted out during digging operations to be free from asphalt chunks, concrete chunks, building debris and/or organic matter.

2.4.3 Unsuitable excavated materials shall include, but not limited to: (a) Materials from swamps, running silt, dark organic materials, logs, stumps, perishable

materials, slurry or mud; or (b) Materials that are highly plastic clays; or (c) Materials that are highly organic clay or silt; or (d) Materials that contain an unacceptable quantity of soluble salts (> 2%); or (e) Materials that have high moisture content (> 3% of material optimum moisture content).

2.4.4 All unsuitable excavated materials i.e. soft materials, asphaltic chunks, stones larger than 37.5mm, organic materials, metals, debris and plastic materials etc. shall not be used for backfilling and shall be promptly removed from site.

2.5 Geotextiles 2.5.1 Geotextiles required as part of permanent works to separate unbound materials shall be

manufactured from synthetic fibers or other fibers as required therein and be in the form of thin permeable membrane.

2.5.2 The Consultant/Contractor shall provide evidence to the Roads Engineer before the geotextiles are incorporated in the permanent works, that the geotextiles will be sufficiently durable, when installed in contact with the materials to be separated, as to maintain its integrity.

2.5.3 Geotextiles shall be protected at all times against mechanical or chemical damages. Those susceptible to damage by exposure to light shall not be uncovered before incorporated in the permanent works at site.

2.5.4 Samples and test cut pieces shall be taken from delivered consignments of geotextiles, jointly selected by the Roads Engineer and the Consultant/Contractor. Samples and test pieces cut from geotextiles shall comply with Clause 2.5.7 of this Specification. Test pieces shall be tested in a laboratory approved by the Roads Engineer to prove that the geotextiles meet the following criteria: (a) Sustain a tensile load of not less than 2.5kN/m at 5% axial strain determined in a "Wide

Strip" tensile test carried out in accordance with Clause 2.5.8; (b) Allow water to flow through it, at right angle to its principal plane, in either direction, at a

rate of not less than 10 l/m/s under a constant head of water of 100mm, determined in accordance with Clause 2.5.9;

(c) Have a size distribution of pore openings such that O90, as defined in Clause 2.5.10, is between 100 m and 300 m, determined in accordance with Clause 2.5.10.

2.5.5 The geotextiles shall be laid and lapped as described in this clause and where lapping is employed adjacent sheets or strips of geotextiles shall be overlapped by at least 300mm.

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2.5.6 The layer of material on which the geotextiles is to be placed shall not have protrusions or sharp projections, which are likely to damage the geotextiles during installation or while in service. The method of installation shall ensure that the geotextiles is in continuous contact with the surface on which it is to be placed and the geotextiles shall not be stretched or bridged over hollows or humps. Operation of constructions plant directly on the installed geotextiles will not be permitted and its covering with fill material shall take place immediately after its laying.

2.5.7 All samples and test pieces cut from geotextiles shall be maintained in a clean and dry condition, except for normal contamination and wetting during testing, and shall be retained by the Contractor until the completion of the defects liability period when they shall be delivered to the Roads Engineer. Prior to determination of pore size and tensile strength, test pieces shall be conditioned and brought into equilibrium to a temperature of 20C 2C, and a relative humidity of 65% 5%. The dry weight of the geotextiles tested shall be quoted in g/m2.

2.5.8 The 'wide strip' tensile strength test shall be carried out as follows by a method approved by the Roads Engineer: (a) The test pieces shall be 200mm wide and have a gauge length of 100mm (b) A minimum of five test specimens shall be taken and tested in each of the two principal

directions within the geotextiles relating to its mode of manufacture, in order to determine the characteristic strength of the geotextiles.

(c) The rate of strain shall be 10% 3% per minute. (d) The characteristic strength shall be taken as the value of the strength of the material

below which not more than 5% of the test result may be expected to fall. This represents the strength at 1.64 standard deviations below the mean strength.

2.5.9 Flow rate of water shall be determined as follows: (a) Geotextiles shall be tested in an unloaded condition under 100mm constant head water. (b) Flow shall be in a single direction. (c) The area to be tested shall be circular and of between 50mm and l00mm diameter. (d) Before testing, the test piece shall be conditioned in clean water for one hour. (e) The water used in the test shall:

(i) be as free of air as possible and the apparatus shall be supplied from still tank and not directly from a mains supply;

(ii) not be contaminated with detergents or other substances and there shall be no recycling of the water;

(iii) have a temperature not less than 10C or in excess of 25C. The flow rate determined in the test shall be corrected to that applicable to a temperature of 15C using published data on variation in viscosity of water with temperature.

(f) The quantity of flow to be collected shall be not less than 2 liters or alternatively the flow shall be collected for a period of time in excess of 15 s.

(g) The number of test pieces shall be a minimum of 4 and the number of flow runs per test piece shall be a minimum of 4.

(h) The flow shall be quoted in l/m/s. The standard deviation of the flow results shall be stated together with the mean.

2.5.10 Pore size distribution and determination of O90 shall be as follows: (a) The pore size distribution shall be obtained by determining the percentages of each of a

number of different designated sizes of glass spheres complying with BS 6088 (chosen so as to cover the range of pore sizes) which are retained on the geotextiles when shaken through it employing the geotextiles as sieve.

(b) A cumulative frequency graph of percentage of spheres retained against designated size shall be plotted and the size corresponding to 90% retained is the required O90.

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(c) For each sieving, at least l00g of the glass spheres shall be shaken for 10 minutes on a test piece of geotextiles supported and clamped in place on a sieve of frame diameter 300mm and aperture size greater than 10mm.

(d) The sieve apparatus shall have a vibration frequency of 50Hz and maximum vertical amplitude of 0.75mm.

(e) Five test pieces having dimensions exceeding the dimensions of the sieve shall be taken to provide a mean of O90 pore size.

2.5.11 The maximum hole size determined by the Fall Cone test shall not be more 50mm. 2.6 Lean mix concrete 2.6.1 Lean mix concrete shall be supplied by an approved ready mixed concrete company. Site

mixing will not be permitted without the specific written permission from the Roads Engineer. 2.6.2 Batching and mixing of lean mix concrete shall be carried out in a static plant. The solid

materials shall be batched by mass. Liquid materials may be batched by volume. 2.6.3 When transporting lean mix concrete, the material shall be transported directly to the point of

use. It shall be properly protected from weather and against drying out during transport and while awaiting discharge.

2.6.4 Aggregates: Aggregates for lean mix concrete shall consist of coarse aggregates, having maximum

nominal size of 40mm, and sand batched separately. The overall grading shall be within the limits established in Table A-3 Table A-3: Aggregate gradation for Lean Mix Concrete B.S. Sieve size Percentage passing by weight

37.5 mm 95 100 20 mm 45 80 5 mm 30 40 600 micron 8 30 150 micron 0 6

2.6.5 Cement content: Cement content shall be in the range of 85 kg/m3 to 125 kg/m3. The ratio of cement to aggregate by mass shall be sufficient to produce average 7-day strength of 3.5 N/mm2 for each batch of five test specimens.

2.6.6 Placement: Lean concrete backfill shall be placed and spread evenly in such a way as to avoid segregation or drying. Spreading shall take place without delay and sufficient surcharge shall be allowed so that the final compacted thickness of any one layer shall not exceed 150mm. Transverse joints shall be staggered by at least one meter. The material shall be placed at optimum moisture content.

2.6.7 Compaction: Compaction shall take place immediately after spreading is completed and shall be finished within two hours of the addition of water to the mix. In no circumstances shall additional water be added to the mix. Material which has dried out or has exceeded the time limitation before compaction is completed shall be removed from the works and replaced with fresh material. Compaction of lean mix concrete shall be carried out using suitable mechanical vibrating plant (vibrating plates and/or rollers) and shall be continued until a density of 95% of the Standard Wet Density is achieved.

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2.6.8 Surface Finish: The surface of the lean mix concrete after compaction shall be free from ridges, cracks, loose material, potholes or other defects. It shall be well closed and free from movement under the action of the compaction plant. All loose, segregated or otherwise defective areas shall be removed to the full depth of the layer and new material laid and compacted.

2.6.9 Curing: Immediately after completion of compaction and in no circumstances later than three hours from mixing, curing of the lean mix concrete layer shall commence. Curing shall be achieved by covering the exposed surface of the lean mix concrete with impermeable sheeting, such as polythene. This sheeting shall have joints overlapping by at least 300mm and shall be weighted at the edges and ends to prohibit the access of wind. This method of curing shall be maintained until one of the following conditions has been met: (a) The completion of the seven day curing period; or (b) The placing of an additional layer of lean mix concrete; or (c) The application of a prime coat or a tack coat prior to the laying of the asphalt surfacing.

2.6.10 Testing for Strength: A sample shall be taken in accordance with the requirements of BS 1881: Part 108, from a delivery of lean mix concrete. Five cubes shall be prepared from this sample by the method described in BS 1881: Part 108 except that the cubes shall be compacted by means of a vibrating hammer with the moulds placed on a level, rigid base. The vibrating hammer shall have a square or rectangular foot having an area between 7500mm2 and 14000mm2. The compaction shall be uniformly applied for 60 5 seconds with a downward force of 300N to 400N onto each of the three layers of lean mix concrete placed into the mould. The surface of each compacted layer shall be scarified before the addition of any subsequent layer. The cubes shall be cured immediately after compaction and shall be tested at an age of seven days.

2.6.11 Standard Wet Density: The supplier shall prepare five moulds from a sample taken from the first truck supplied on each and every day of supply. The moulds shall be weighed empty prior to making the cube and reweighed immediately after completion of the compaction of the third layer of the cube. These masses together with the nominal volume of the mould shall be used to calculate the Standard Wet Density of the mix. The test results shall be supplied to the Contractor and the Roads Engineer with the truck transporting the first load delivered.

2.6.12 In Situ Density: In situ density testing shall be carried out using a nuclear densitometer or the Sand Replacement Method described in Method 2 (Clauses 2.5 and 2.2, respectively) of BS 1377: Part 9: 1990, at the rate instructed by the Roads Engineer.

3. Tack Coat and Prime Coat 3.1 Tack coat shall be bituminous emulsion complying with BS: 434, either anionic class A1-40 or

cationic class K1-40, or rapid curing cut back bitumen confirming to BS: 434 (Road Oil is not to be used as tack coat).

3.2 Prime coat (or Road Oil) shall be medium cut back bitumen confirming to BS: 3690. All references to M.C.I on any drawing shall mean Road Oil

4. Asphalt Concrete Surfacing Materials

Asphalt concrete surfacing materials include all material constituents and mixes made out of these constituents that are used to reinstate the asphalt surface layer(s) to its original condition prior to cutting and excavation. These materials and their placement/testing requirements are specified in clauses 4.1 to 4.11 below.

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4.1 Aggregates General 4.1.1 Aggregates are to be obtained from a source approved by the Roads Engineer. 4.1.2 Aggregates are to be free from vegetable or organic matter and are to be non plastic. They

are to be substantially free from dust or other materials which would prevent thorough coating with binder or which would adversely affect the strength or durability of the asphalt concrete mix.

4.1.3 Aggregates are to be substantially free from sulphates, chlorides and other materials which would break down in the dryer during mixing or subsequently when exposed to the weather.

4.1.4 For all ASTM tests specified in this specification, the ASTM E11 sieves will be replaced by the stated BS 410 sieves as listed in Table A-4 below. Table A-4: BS 410 Sieves Equivalent to ASTM E11 ASTM E11 Replaced by BS 410 No. 4 (4.75 mm) 5 mm 3/8 (9.5 mm) 10 mm (12.5 mm) 14 mm (19 mm) 20 mm 1 (25 mm) 28 mm

4.1.5 Aggregates shall be hard, durable, crushed and pre-screened rock, clean and free from dust. All samples will be taken from cold feed to asphalt plant and shall be assessed as individual cold bin samples.

4.2 Coarse Aggregates (imported aggregates) 4.2.1 Coarse aggregates shall be retained on 5mm sieve and shall have the following properties

when tested in accordance with BS: 812 (Table A-5): Table A-5: Properties of Coarse Aggregates Property Value (%) Aggregate crushing value (ACV) 25 Flakiness index 30 Water absorption 2.5 Polished stone value (applicable for wearing course only) 48

4.2.2 When tested in accordance with ASTM D1664, the estimated coated area shall be above 95%.

4.2.3 When tested in accordance with ASTM C 88, the loss of weight determined after 5 cycles shall not exceed 4% using sodium sulphate solution or 6% using magnesium sulphate solution.

4.2.4 When tested in accordance with ASTM C 142, the clay lumps and friable particles content shall not exceed 0.5% for any individual sieve size fraction.

4.2.5 At least 90% by weight of the aggregate in individual size fractions shall have three or more crushed faces. Each crushed face shall have an area equal to or greater than 75% of the area of the smallest mid-sectional area of the piece, and the angle between adjacent faces shall not be less than 30.

4.3 Fine Aggregates 4.3.1 Fine aggregates shall constitute the fraction of aggregates passing the 5mm BS sieve and

retained on the 75 micron sieve. Fine aggregates shall consist of natural sand, quarry sand or crushed rock produced in a secondary plant. It shall be non plastic and free from loosely bonded aggregations, organic and other foreign matter. When tested in accordance with BS: 812 it shall have maximum water absorption of 3%. All samples will be taken from the cold feed to asphalt plant and shall be assessed as individual cold bin samples.

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4.3.2 The content of clay lumps and friable particles determined in accordance with ASTM C142 shall not exceed 3%.

4.3.3 When specified in the Contract, fine aggregates shall consist partially or totally of crushed particles.

4.4 Filler 4.4.1 At least 60% of the amount of fines passing the 75 micron BS sieve, shown in Table A-8 in

Clause 4.6.6, is to be added to the asphalt concrete mix separately as filler. 4.4.2 Filler is to be either Portland cement complying with BS: 12 or rock flour having the grading

shown in Table A-6: Table A-6: Gradation specifications for rock flour used as filler in asphalt concrete mix B.S. Sieve size Percentage passing by weight 600 micron 100 300 micron 95 100 75 micron 70 100

4.4.3 The bulk density of filler in benzene shall be between 0.5 and 0.95 g/ml. 4.5 Bitumen 4.5.1 Bitumen supplied as binder shall meet the requirements shown in Table A-7.

Table A-7: Properties