11-Division 2-Section 02300 Sewage Works-Version 2.0

ADSSC/GSCW Division 02 Section 02300

Sewage Works Rev: 02 Jan. 2011 Page 1 of 24

ABU DHABI SEWERAGE SERVICES COMPANY (ADSSC)

GENERAL SPECIFICATION FOR CIVIL WORKS

DIVISION 2 SITEWORK

SECTION 02300 SEWAGE WORKS

General Specification for Civil Works Abu Dhabi Sewerage Services Company

(ADSSC)



DOCUMENT CONTROL SHEET

Revision No. Date Revision Description / Purpose of Issue

01 April 2008 First Issue.

02 Jan. 2011 ADSSC new logo

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TABLE OF CONTENTS

1 GENERAL ....................................................................................................... 5 1.1 SCOPE ................................................................................................ 5 1.2 RELATED DOCUMENTS ..................................................................... 5 1.3 STANDARDS ....................................................................................... 5 1.4 SUBMITTALS ....................................................................................... 6 1.4.1 PRODUCTS AND MATERIALS APPROVAL. ....................................... 6 1.4.2 METHOD STATEMENTS ..................................................................... 6 1.4.3 DRAWINGS. ........................................................................................ 7 1.4.4 SAMPLES. ........................................................................................... 7 1.5 QUALITY CONTROL............................................................................ 7 1.6 DELIVERY STORAGE AND HANDLING.............................................. 8

2 PRODUCTS ..................................................................................................... 8 2.1 CONCRETE ......................................................................................... 8 2.2 CONCRETE PROTECTION AND WATERPROOFING SYSTEMS ...... 8 2.3 COVERS, GRATINGS. FRAMES AND SURFACE BOXES.................. 9 2.4 COATINGS TO COVERS, GRATINGS. FRAMES AND SURFACE

BOXES ............................................................................................... 10 2.5 GRP PRODUCTS .............................................................................. 10 2.5.1 RAW MATERIALS .............................................................................. 10 2.6 GRP SEALING PLATES FOR SEWAGE MANHOLES AND

CHAMBERS ....................................................................................... 12 2.7 GRP LADDERS AND SAFETY CAGES ............................................. 12 2.8 GRP HANDRAILING .......................................................................... 13 2.9 GRP LINERS ..................................................................................... 14 2.10 GRAB HANDLES ............................................................................... 14 2.11 STAINLESS STEEL GRAB HANDLES ............................................... 14 2.12 STEP IRONS ..................................................................................... 14 2.13 SAFETY CHAINS ............................................................................... 14

3 EXECUTION .................................................................................................. 15 3.1 CONSTRUCTION OF APPURTENANT STRUCTURES .................... 15 3.2 INSTALLING PIPES THROUGH STRUCTURES ............................... 16 3.2.1 GRP AND PVC-U PIPELINES ............................................................ 16 3.2.2. RC PIPELINES................................................................................... 17 3.3 THRUST BLOCKS ............................................................................. 17 3.4 GRP LADDERS .................................................................................. 18 3.5 GRP HANDRAILING .......................................................................... 18 3.6 GRAB HANDLES ............................................................................... 18

4 MAKING CONNECTIONS TO EXISTING DRAINAGE SYSTEMS ................ 18 4.1 PROPERTY CONNECTION SEWERAGE LATERALS ...................... 18 4.2 CONNECTIONS TO EXISTING MANHOLES/CHAMBERS/PIPELINES

........................................................................................................... 20 4.3 CONTINUITY OF FLOWS .................................................................. 21 4.4 SEWER FLOW CONTROL................................................................. 22 4.4.1 GENERAL .......................................................................................... 22 4.4.2 PIPE STOPPERS ............................................................................... 22 4.4.3 PUMPING AND BYPASSING OF FLOW ............................................ 22


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4.4.4 TEMPORARY DIVERSION OF FLOW ............................................... 23 4.4.5 ENTRANCES TO PRIVATE PROPERTIES ....................................... 24 4.4.6 ODOUR CONTROL DURING PUMPING AND BYPASSING OR

DIVERTING OF FLOW ....................................................................... 24 4.4.7 GENERAL CLEANLINESS OF AREAS .............................................. 24


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1 GENERAL

1.1 SCOPE

This section of the specification gives the requirements for the construction of appurtenant structures such as manholes, chambers, inlet structures and catch basins etc together with all associated fittings, covers, gratings, ladders etc, on sewerage systems.

1.2 RELATED DOCUMENTS

The following sections of the specification shall be read in conjunction with this section.

Section 01000-07 Submittals Section 01000-08 Quality control Section 01000-09 Materials and equipment Section 02120 Utility excavation, surround and backfill Section 03300 Cast in place concrete Section 03400 Precast concrete Section 03600 Concrete protection and waterproofing systems

1.3 STANDARDS

All activities relating to this section shall comply with the following or approved equal standards.

ASTM D570 Standard test method for water absorption of plastics. ASTM D2583 Standard test method for indentation hardness of rigid

plastics by means of a barcol impressor. ASTM E84 Standard test method for surface burning

characteristics of building materials. . BS 3396 Woven glass fabrics for plastics reinforcement. BS 3532 Method of specifying unsaturated polyester resin

systems. BS 5400-2 Steel, concrete and composite bridges. Specification for

loads. BS 5834-2 Surface boxes, guards and underground chambers for

gas and waterworks purposes. Specification for small surface boxes.

BS EN 124 Gully tops and manhole tops for vehicular and pedestrian areas. Design requirements, type testing, marking, quality control.

BS EN 681-1 Elastomeric seals. Material requirements for pipe joint seals used in water and drainage applications. Vulcanised rubber.

BS EN 10088-1 Stainless steels. List of stainless steels. BS EN 13101 Steps for underground man-entry chambers –

Requirements, marking, testing and evaluation of conformity


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BS EN 14020-1 Reinforcements. Specification for textile glass rovings. Designation.

BS EN 14020-2 Reinforcements. Specification for textile glass rovings. Methods of test and general requirements.

BS EN 14020-3 Reinforcements. Specification for textile glass rovings. Specific requirements.

BS EN 14118-1 Reinforcement. Specifications for textile glass mats (chopped strand and continuous filament mats). Designation.

BS EN 14118-2 Reinforcement. Specifications for textile glass mats (chopped strand and continuous filament mats). Methods of test and general requirements.

BS EN 14118-3 Reinforcement. Specifications for textile glass mats (chopped strand and continuous filament mats). Specific requirements.

BS EN 14364 Plastics piping system for drainage and sewerage with or without pressure. Glass reinforced-thermosetting plastics (GRP) based on unsaturated polyester resin (UP). Specifications for pipes and fittings

ISO 1083 Spheroidal graphite cast iron - classification. ISO 9000 Quality management systems.

1.4 SUBMITTALS

1.4.1 PRODUCTS AND MATERIALS APPROVAL.

a) In order to verify compliance with the specification the Contractor shall submit information for all products and materials used in the Works to the Engineer for approval sufficiently in advance of their use in accordance with the Contract programme allowing for ordering and approval times. Reference should also be made to Section 01000-09 of the specification on products and materials approval. Information to be submitted for each proposed production shall comprise but not necessarily be limited to:

i. Manufacturer’s name. ii. Supplier’s name. iii. Product name, if applicable. iv. Product description. v. Manufacturer’s technical data. vi. Test results or certificates. vii. Storage instructions. viii. Installation instructions.

1.4.2 METHOD STATEMENTS

a) The Contractor shall submit method statements to the Engineer for approval 4 weeks in advance of commencing the site activity in accordance with Section 01000-07 of the specification. These shall comprise but not necessarily be limited to:


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i. Excavation and backfilling in accordance with Section 02120 of the specification.

ii. Construction of cast in place and/or precast manholes, chambers and structures in accordance with Sections 03300 and 03400 of the specification.

iii. Protection to concrete structures in accordance with Section 03600 of the specification.

iv. General fabrication methods for Glass Reinforced Plastic (GRP) products.

v. Procedures for making connections to existing drainage systems. 1.4.3 DRAWINGS.

a) The Contractor shall submit drawings to the Engineer for approval in advance of commencing the site activity in accordance with Section 01000-07 of the specification. These shall comprise but not necessarily be limited to:

i. Excavation drawings in accordance with Section 02120 of the

specification. ii. Precast concrete manhole, chamber and structure drawings in

accordance with section 03400 of the specification. iii. Concrete protection and waterproofing systems drawings in

accordance with Section 03600 of the specification. iv. Product fabrication and erection drawings including plans,

elevations, sections and connection and anchorage details. 1.4.4 SAMPLES.

a) Representative samples, as agreed with the Engineer, must be submitted for at least the following items at the same time as the particulars are submitted:

i. Samples of each type of GRP product.

1.5 QUALITY CONTROL

a) Prior to dispatch of any product and/or material from source the Contractor shall notify the Engineer in writing in sufficient time to allow the Engineer the opportunity to inspect and test the product and/or material prior to delivery in accordance with Section 01000-08 of the specification.

b) Products and materials shall be from a manufacture/supplier who

operates a quality system which is registered to ISO 9000 series or approved equal.

c) To allow the Engineer to inspect the works the Contractor shall give the

Engineer a minimum of 24 hours notice of carrying out the following activities on site:


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i. Commencement of excavation. ii. Casting of blinding concrete. iii. Pouring of cast in place concrete. iv. Manufacturing of precast concrete units. v. Installation of precast concrete units. vi. Installation of concrete protective coatings and linings and concrete

waterproofing. vii. Placement of backfill. viii. Installation of fittings, covers, gratings, ladders etc. ix. Making connections to existing drainage systems.

1.6 DELIVERY STORAGE AND HANDLING

a) Delivery, storage and handling of products and materials shall be in accordance with the manufacturer’s recommendations, Section 01000-09 of the specification and the following provisions.

i. Delivery, storage and handling shall at all times be performed in a

manner to avoid product damage. ii. Only nylon slings shall be allowed for lifting products. iii. Products shall be stored off the ground on timber blocks of

sufficient size and spacing to provide adequate support. iv. Products shall be stored at site in a temperature, humidity etc.

environment as recommended by the manufacturer. v. Products that are stored outside at site shall be stored under cover

to prevent ultra violet deterioration and as recommended by the manufacturer.

vi. The Contractor shall visually inspect all products upon delivery to site and report any damage to the Engineer.

Any products damaged during delivery, storage and handling

shall be marked by the Contractor and set aside. Proposals for repair of any damaged products shall be

submitted in writing to the Engineer for approval. Any damaged products deemed unsuitable for repair by the

Engineer shall be removed from site and replaced. 2 PRODUCTS

2.1 CONCRETE

Cast in place and precast concrete shall comply with the requirements of Section 03300 and 03400 of the specification respectively.

2.2 CONCRETE PROTECTION AND WATERPROOFING SYSTEMS

Concrete protection and waterproofing systems shall comply with the requirements of Section 03600 of the specification.


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2.3 COVERS, GRATINGS. FRAMES AND SURFACE BOXES

a) Covers and frames for access to manholes, chambers and wet wells on storm water and sewerage systems shall comply with BS EN 124.

b) Covers, gratings and frames for catch basins and inlet structures shall

comply with BS EN 124.

c) Covers and frames shall be unvented and shall be made of spheroidal graphite cast iron, ductile iron, to ISO 1083. They shall be supplied in one piece, unless specified otherwise, to suit the clear openings shown on the drawings.

d) Unless otherwise shown on the drawings or instructed by the Engineer

the class of covers, gratings and frames shall be as follows:

i. Class D400 in areas subject to vehicular traffic. ii. Class C250 in areas accessible to traffic. iii. Class B125 in areas not subject to vehicular traffic. iv. Class D400 to wet wells and similar chambers within pumping

station sites.

e) Class D400 covers shall be non-rocking. This shall be achieved by either machining the contact surfaces or by incorporating an EPDM seal with a minimum contact width of 10 mm in the frame or both frame and cover.

f) Unless otherwise indicated on the drawings manhole and chamber cover

sizes shall be as stipulated below:

i. 600mm x 750mm or 750mm diameter for pipeline diameter not greater that 800mm.

ii. 900mm diameter for pipeline diameter greater than 800mm.

g) Cover face badging shall be in Arabic and English and as a minimum shall include the following:

i. Manufacturers name. ii. Standard of manufacture. iii. Loading class. iv. SEWERAGE as appropriate in Arabic and English. v. ABU DHABI SEWERAGE SERVICES COMPANY in Arabic and

English.

h) Multiple duct covers and frames shall be ductile iron to ISO 1083, water proof and non-rocking. They shall be of the type incorporating integral removable intermediate beams to give the required clear opening shown on the drawings.

i. All covers, frames and supporting metal work shall be designed for

loading to BS 5400-2.


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i) Covers and gratings shall be equipped with cast in lifting eyes, holes or other handling facilities.

j) Surface boxes shall be ductile iron conforming to BS 5834, Grade A

loading and shall have a 150mm square clear opening.

k) One prying and lifting bar of approved design shall be provided with each 20 covers supplied with a minimum of one for each type of cover.

l) Covers and gratings shall be sampled at random by the Engineer and

load tested under his supervision according to BS EN 124 procedures. The sampling and testing rate shall be 2%.

2.4 COATINGS TO COVERS, GRATINGS. FRAMES AND SURFACE BOXES

a) All castings such as covers, gratings, frames and surface boxes shall be imported to Abu Dhabi without a permanent coating. Machined faces shall be greased to prevent corrosion.

b) All castings shall be inspected for defects. Castings with unacceptable

defects shall be rejected.

c) Minor blowholes and surface imperfections shall be filled in and repaired with an approved two component epoxy amine solvent free filler.

d) All castings shall be coated in an approved coating yard in the Emirate of

Abu Dhabi under the Engineer’s supervision. All castings shall be degreased, grit blasted to SA 2.5, near white metal condition, primed with a metallic zinc primer and then coated with a black two component solvent free epoxy polyamine cured coating material applied in two coats, each coat having a minimum dry film thickness of 200 microns.

e) Coated castings shall not be handled and transported until full cure has

been achieved. An original of the approved coating specialist's quality control report for each itemised component shall be provided with each delivery. The report shall bear an original company stamp and signature.

f) Coatings to castings to be used within public roads and parking areas

shall be to the requirements of the Road Section of the Abu Dhabi Municipality.

2.5 GRP PRODUCTS

2.5.1 RAW MATERIALS

a) Materials used in the manufacture of GRP products shall be new stock and of the best quality.

b) Materials shall be free from all defects and imperfections that might

affect the performance of the finished product.


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c) Resins shall comply with the relevant provisions of BS 3532 Type B,

unless otherwise approved by the Engineer. Vinylester resins shall have an elongation at break of 3 to 6%.

d) Glass shall comply with the relevant provisions of the following

standards unless otherwise approved by the Engineer. Surface tissues shall also comply with one of the following standards:

i. BS EN 14020-1, BS EN 14020-2 and BS EN 14020-3 for rovings. ii. BS 3396 for woven fabric. iii. BS EN 14118-1, BS EN 14118-2 and BS EN 14118-3 for chopped

strand mat.

e) All glass shall be ECR or other corrosion resistant glass, unless otherwise approved by the Engineer.

f) Roving size shall not exceed 2400 Tex.

g) Chopped strand mat shall not exceed 450g/m².

h) Sand aggregate used for non slip surfaces shall be a clean graded silica

sand, nominal size 3mm.

i) General properties of GRP products shall be as given in Table 2.5.1 below.

Table 2.5.1 - GRP Products General Properties

Property Test Method Value

Axial tensile strength ISO 527 100N/mm2

Water absorption maximum

ASTM D570 0.15% not short term boiling method

Barcol hardness ASTM D2583 Min 35 prior to dispatch

j) The frequency of testing of GRP products for dimensional accuracy, the

properties given in Table 1 above and the load and deformation criteria given below shall be as agreed with the Engineer.

k) GRP products exposed to a sewage environment shall be corrosion

resistant to raw sewage and associated gases.

l) GRP products exposed to weather shall contain an ultraviolet inhibitor and shall additionally receive a 500 microns thick gel coat to shield the exposed surface from ultra violet light.


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2.6 GRP SEALING PLATES FOR SEWAGE MANHOLES AND CHAMBERS

a) The sealing plate thickness shall be a minimum of 7mm and shall be designed to support a minimum load of 7.5kN/m².

b) The sealing plate shall be manufactured from the required number of

layers of chopped strand mat 450g/m², “Advantex” powder bound corrosion resistance or equivalent approved, impregnated with isophthalic or vinylester resin of approved type. Resin to glass ratio shall be 75% to 25% by weight with a tolerance of ± 5%. Fillers and aggregates shall not be used. The underside of the plate shall be protected with a resin rich vinylester liner 1.5mm thick reinforced with one layer of “C” glass tissue and two layers of chopped strand mat 300g/m² .

c) The sealing plate shall be in the form of a plug with a flange to prevent

the plate dropping through the access opening.

d) The sealing plate shall incorporate a peripheral retained rubber ring such that when the cover is closed a gas tight seal is formed. The rubber ring shall be made from nitrile rubber, EPDM formulation, in compliance with BS EN 681 and with joints vulcanised and not glued.

e) The plate shall be designed such that a gas tight seal is obtained without the use of bolts.

f) The sealing plates shall have two securely laminated GRP lifting handles.

g) Cuts and/or drilled faces shall be sealed with resin only.

h) GRP sealing plates shall be seated on the lips of the frames without

causing any reduction to the dimensions of the specified openings.

2.7 GRP LADDERS AND SAFETY CAGES

a) GRP ladders shall be of an approved pattern, dimension and duty to suit the location and shall be installed as shown on the drawings.

b) GRP ladders shall be hand laminated mouldings composed of seven

layers of chopped strand mat 450g/m² and one layer of glass surface veil 30g/m, “Advantex” powder bound corrosion resistance or equivalent approved, impregnated with vinylester resin of approved type. Resin to glass ratio shall be 75% to 25% by weight with a tolerance of ± 5%. Fillers and aggregates shall not be used.

c) Hardwood stiffeners are to be provided inside both the rungs and the

rails as a former, and shall be fully encased in the GRP laminate which shall have a minimum thickness of 5mm and there shall be no sharp edges.


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d) The structural components shall possess Class I fire retardance, with an

ASTM E84 maximum flame spread rating of 25.

e) Fixing brackets shall be GRP integrally moulded into the ladder laminations and they shall be not more than 500mm apart. The fixing brackets shall be designed to be anchored securely in concrete having a roughened surface to provide a good bond and shall project a minimum of 100mm into the concrete.

f) The rungs shall be 250mm apart with the upper faces finished to a non-

slip surface.

g) Intermediate landing shall be provided where the rise exceeds 6m.

h) Nuts and bolts shall not be used either in the construction, assembly or fixing of the ladder.

i) Each rung shall be able to withstand a point load of 5000N when applied

at the centre of the rung and when applied close to one end.

j) When supported horizontally over a span of 1m with the climbing face uppermost and with a load of 1000N applied at the centre of the span there shall not be a deflection greater than 10mm at the point of application of the load and there shall be no permanent deformation after removal of the load. The loads shall remain in place for 24hours

k) after which the ladder shall be inspected for defects.

l) Each ladder fixing shall be capable of withstanding shear and pullout loads of 5000N.

m) GRP safety cages shall be as shown on the drawings and shall be

manufactured in the same manner as GRP ladders but without the hardwood core.

n) Safety cages shall be provided where the distance between the ladder

landings exceeds 4.5m.

o) Safety cages shall be constructed of three flat vertical members supported by flat hoops with diameter of 750mm. The hoops shall be at a maximum of 700mm centres and the first hoop shall be 2.4m above ground or platform level.

p) Each hoop shall be able to withstand a tangential point load of 740N and

a vertical point load of 1200N applied at any point on the hoop. The maximum allowable deflection at the point of application of the load shall not exceed 25mm and there shall be no permanent deformation of the hoops after removal of the load after 24 hrs.

2.8 GRP HANDRAILING

a) GRP handrailing shall be as shown on the drawings and shall be


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manufactured in the same manner as GRP ladders.

b) GRP handrailing shall be in prefabricated lengths complete with fittings. The Contractor shall ensure that unless otherwise specified, all handrailing shall be of uniform appearance and manufacture.

c) GRP handrailing shall be 1000mm high and be provided with an

intermediate rail 500mm high. Standards shall be set at not more than 1.50m centres.

d) Handrailing and fixings shall be designed to withstand a lateral horizontal

force at upper handrail level of 740N/m run. The deflection of rails shall not exceed 0.8% of their span between standards and the deflection of standards shall not exceed 0.8% of their height.

2.9 GRP LINERS

a) GRP liners shall be minimum 6.5mm thick or as shown on the drawings.

b) Raw materials and properties of the final product shall be as in Section 2.5

c) Site lamination shall start only after concrete reach its 28 day strength.

2.10 GRAB HANDLES

Grab handles shall be constructed from 20mm diameter formed mild steel bars and coated with a vinylester resin rich GRP laminate. Handles shall have 150mm x 150mm square openings in their final position.

2.11 STAINLESS STEEL GRAB HANDLES

Form the grab handles from a 20mm stainless steel bar Grade 316 to BS EN 10088.

2.12 STEP IRONS

Step irons shall be plastic encapsulated and shall comply with BS EN 13101 and be of the general purpose or precast concrete manhole pattern as applicable.

2.13 SAFETY CHAINS

Safety chains shall be high density polyethylene or stainless steel of accepted size and strength with suitable hooks at one end to permit removal for access.


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3 EXECUTION

3.1 CONSTRUCTION OF APPURTENANT STRUCTURES

a) Manholes, chambers, inlet structures, catch basins etc shall be constructed in accordance with the drawings in the positions indicated thereon or wherever else instructed by the Engineer. Manholes, chambers, inlet structures, catch basins etc shall be watertight.

b) Unless otherwise directed, cut-off walls shall be constructed adjacent to

manholes, chambers, inlet structures, catch basins etc to prevent the formation of drainage paths within the pipe bedding. They shall be keyed into the native soil to a depth of 150mm. They shall be constructed 300mm above the top of the pipe bedding as detailed on the drawings.

c) Pipes entering and leaving manholes and chambers shall be laid soffit to

soffit unless otherwise shown on the drawings.

d) Holes shall not be made through shaft rings and liners.

e) GRP ladders shall be used to access all areas exposed to sewage or sewage gasses and where shown on the drawings.

f) GRP sealing plates shall be provided to access openings in sewage

manholes, chambers and wet wells. GRP sealing plates shall also be provided to access openings in structures in permanently irrigated areas.

g) All internal surfaces of manholes, chambers, inlet structures, catch

basins etc shall be protected in accordance with Section 03600 of the specification.

h) All external surfaces of manholes, chambers, inlet structures, catch

basins etc shall be waterproofed and protected in accordance with Section 03600 of the specification.

i) Covers in paved areas shall be set accurately on a course of concrete

blockwork to the level and slopes of the surrounding surface. The blockwork, cover and frame shall have a bed of 15mm thick cement mortar and shall be surrounded by concrete Grade C20 up to the underside of the base course of the paved area and to the extent indicated on the drawings.

j) Covers in unpaved areas shall be set accurately on a course of concrete

blockwork. The blockwork, cover and frame shall have a bed of 15mm thick cement mortar and shall be surrounded by concrete Grade C20 to 100mm above the level of the surrounding surfaces and to the extent indicated on the drawings or as instructed by the Engineer.

k) Covers and gratings for catch basins and inlet structures shall be of the

type and size as shown on the drawings. The frames shall be fitted in


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place at the time of the structure construction such that covers and gratings are level with the top of the adjacent surface.

l) Side inlet grates shall be of the sizes and configuration as shown on the

drawings. Side inlet grates shall be fixed in place with the concrete wall installation such that the face of the grate is flush with the face of the kerb.

3.2 INSTALLING PIPES THROUGH STRUCTURES

a) The Contractor is deemed to have covered for any method of installation in his rates.

b) Ensure that pipes and pipe specials through concrete walls and floors

are as far as possible located and built in during construction. Locate the pipes exactly in the positions shown in the drawings. Ensure that the pipes are true to line and level. Ensure that fully compacted concrete is in contact with the pipes at all points.

c) Where it is impracticable to cast pipes and specials in the concrete, form

boxholes in the shuttering. Form boxes of six or eight sides, depending on the pipe diameter. Form boxes no larger in size than will give adequate clearance for the subsequent positioning and grouting in of the pipe. Provide the sides of the boxholes with a tapered central annular recess to provide a positive key. Provide the boxholes with a grout hole and, at the top of the central annular recesses with vent holes. Strip the boxholes from the main shuttering and thoroughly clean and roughen the concrete surface.

d) When the pipe or special to be installed is cast in, a suitable bonding

agent and non-shrink grout shall be used.

e) Unless otherwise shown on the drawings, protect the pipes passing through a concrete wall or structure with a surround of concrete Grade C20 integral with the external faces of the structure.

i. For pipes of less than 500mm diameter, extend the surround from

the wall or structure by 300mm, and extend the width and depth of the surround beyond the outside face of the pipe at its horizontal and vertical diameters by a minimum of 300mm or as otherwise indicated on the drawings.

ii. For pipes of 500mm diameter or greater, extend the surround from the wall or structure by 500mm, and extend the width and depth of the surround beyond the outside face of the pipe at its horizontal and vertical diameters by 500mm or as otherwise indicated on the drawings.

3.2.1 GRP AND PVC-U PIPELINES

a) On spigot and socket GRP and PVC-u pipelines extend the socket surround. A protective synthetic rubber strip 6mm thick and 150mm


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wide shall be provided around the pipe at the limit of the concrete surround as shown on the drawings.

b) Use a short length of either spigot and socket or double spigot pipe to

suit the flow direction, as the first pipe that is clear of concrete surround beyond the external face of a concrete wall or structure. The effective length of this pipe shall be 1.5 times the nominal diameter or 600mm whichever is the greater.

3.2.2. RC PIPELINES

a) The length of the RC spigot and socket pipe passing through the wall shall be 1500mm measured from the inside face of the wall. A flexible neoprene rubber or mastic filler shall be provided around the pipe at the limit of the concrete surround as shown on the drawings.

b) Use a short length of either spigot and socket or double spigot pipe to

suit the flow direction, as the first pipe that is clear of concrete surround beyond the external face of a concrete wall or structure. The effective length of this pipe shall be 1500mm for pipes smaller than or equal to 1200mm diameter and 3000mm for pipes larger than 1200mm diameter.

c) Backfill with concrete Grade C20 to the formation level of the pipe trench

any over-excavation adjacent to a structure and beneath the formation level of a pipe trench to be constructed by the Contractor or by others to make a connection to a plugged or capped pipe laid by the Contractor. Extend this concrete to the limit of the over excavation along the line of the pipe trench and across the full width of the pipe trench shown on the drawings or the limit of the excavation whichever is least.

3.3 THRUST BLOCKS

a) The Contractor shall construct thrust blocks at every bend, tee and wye junction on pressure pipelines, except as noted in Clause 3.3 g) below and at locations as shown on the drawings or ordered by the Engineer.

b) Thrust blocks shall be constructed to the dimensions shown on the

drawings using concrete Grade C40/20, unless otherwise approved by the Engineer.

c) Thrust blocks are designed for the soil parameters designated in the

applicable soil report.

i. If actual ground conditions differ from the soil reports, the Engineer shall be notified.

ii. Where actual ground conditions do not meet anticipated soil conditions, the Engineer may redesign the thrust block.

iii. Where considerably better ground conditions, such as rock, are encountered, the dimensions of a particular thrust block may be reduced, with the Engineer’s approval.

iv. Supporting calculations for any reduced size thrust blocks must be


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submitted to the Engineer at least 72 hours before construction of that particular thrust block commences.

d) Concrete shall extend to undisturbed ground on thrust faces of thrust

blocks and on both faces of anchor blocks.

e) Ensure that the thrust block has been tanked before additional excavation is made to obtain a firm thrust face against undisturbed ground. Place the concrete backfill to the excavation the same day as the additional excavation is carried out.

f) No pressure is to be applied to thrust blocks until the concrete has

matured in accordance with Section 03300 of the specification.

g) Polyethylene piping systems with fusion welded joints and/or end-load resistant fittings form a continuous string of pipe and there is normally no need for thrust blocks and anchorages. However, where individual non-end resistant fittings are used, or when connections are made to non end-load resistant pipe systems, local anchor blocks must be provided as described above.

3.4 GRP LADDERS

GRP ladders shall be mechanically bonded into the concrete structure by means of suitable fixing brackets and also bonded to the internal GRP lining of sewerage manholes and wet wells.

3.5 GRP HANDRAILING

a) Fixings used for anchoring GRP handrailing shall be approved stainless steel anchors. All fixing holes shall be grouted with a two component epoxy mortar. Expansion bolts may be used instead of anchors at locations designated and approved by the Engineer.

b) Horizontal mounting flanges shall be drilled for not less than three bolts

with two bolts on a line parallel to and on the walkway side of the handrailing. Vertical mounting flanges shall be drilled for not less than two bolts the line through the bolts being vertical. Fittings shall be screwed or secured with stainless steel grub screws.

3.6 GRAB HANDLES

Grab handles shall be positioned 400mm apart and centrally over the ladder as directed by the Engineer and securely anchored into the concrete or blockwork.

4 MAKING CONNECTIONS TO EXISTING DRAINAGE SYSTEMS

4.1 PROPERTY CONNECTION SEWERAGE LATERALS

a) Connect existing drainage from individual property or properties to the


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sewer manhole or as may be directed by the Engineer including the construction of any inspection chambers etc along its length.

b) The position and other details of individual connection laterals, which are

not generally shown on the drawings, will be determined by the Engineer as the work proceeds.

c) The Contractor shall prepare a 1:500 scale sketch plan for each plot into

which a connection is required, establishing the locations of existing services, including septic tanks and shall submit this to the Engineer.

d) Do not proceed with the connection work until the Engineer has

approved the proposed layout.

e) Consult with the Engineer to prepare a detailed programme of work for any connections within the boundary of private lands in order that any necessary notices may be given by ADSSC to the owners or tenants before the Contractor's entry on to such private lands.

f) Proceed with the property connection works in an upstream direction

from an existing manhole or sewer. Do not connect the house drainage until all pipework and chamber bases have been constructed downstream of any individual connection. Do not disconnect or breakout existing septic tanks or soakaways until downstream pipework and chambers have been constructed or until alternative temporary arrangements for dealing with flows have been provided to the satisfaction of the Engineer.

g) Use property connection laterals of 150mm internal diameter unless

shown otherwise. Lay pipes at such gradients as may be directed by the Engineer.

h) Use concrete Grade C20 surround, 150mm thick for tee junctions and

vertical pipes located on connections as shown on the drawings.

j) Break out or seal off existing drain pipes, which have been made redundant in accordance with procedures and requirements specified below.

i. Request information from the Engineer for the existing sewer house

connection or pumping main to be abandoned. ii. Inform the Engineer in writing of the intention to abandon. Obtain

the Engineer’s approval prior to proceeding. iii. Flush out completely all pipes to be abandoned. iv. Unless otherwise shown on the drawings or instructed by the

Engineer, fill completely all existing sewers and house connections to be abandoned with a cement slurry or similar material using a method approved by the Engineer by which the discharge slurry can be forced into the pipeline under pressure.

v. Ensure that all existing connections into the sewer to be abandoned have been either plugged or disconnected before filling proceeds.


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vi. Upon completion of this work, ensure that the manholes or chambers are abandoned to the satisfaction of the Engineer.

vii. Where a sewer or house connection to be abandoned connects into a manhole or chamber to be retained, plug the connection at the chamber wall. Thoroughly clean and fill with an approved cement mortar, the associated channel in the benching of the manhole or chambers.

viii. Unless otherwise shown on the drawings or instructed by the Engineer, flush out and seal either end of the existing pumping main to be abandoned with a removable expanding stopper to the approval of the Engineer. Where chambers occur on the pipeline to be abandoned, demolish to the approval of the Engineer and seal the pipeline ends as detailed above. Demolition material shall be removed to an approved location.

ix. Replace existing drain pipes which are to remain in use by similar diameter pipes if found to be faulty. Remove and dispose off site the faulty pipes to an approved location.

k) Apply a pressure test to the property connection laterals between

chambers or to 1m from their termination points whichever is applicable. Testing shall be carried out in accordance with the requirements of the applicable sections of the specification. Provide physical evidence, eg by passing a ball or water or light, to satisfy the Engineer that every property connection lateral is completely clear and that it contains no foreign matter which may cause a blockage.

l) Do not connect property into the connection lateral until the lateral or

connection has been thoroughly tested and backfilled and the Engineer has given his written approval for the final connection.

m) Arrange the operations of the connection lateral so that the interval

between opening up and backfilling of laterals does not normally exceed 5 working days and never exceeds 10 working days.

4.2 CONNECTIONS TO EXISTING MANHOLES/CHAMBERS/PIPELINES

a) The Contractor may be required to make connections to chambers, manholes and pipelines that have been constructed by others.

b) Existing chambers and manholes may not be provided with ports for

connection or may have glass reinforced plastic (GRP), unplasticised polyvinyl chloride (PVC-u) or vitrified clay (VC) spigots or sockets of varying diameter plugged or capped for future connections. Upon commencing work at these manholes the Contractor shall excavate to locate the point of connection, remove the plug or cap if provided and start laying and jointing pipes from the manhole. Should the Contractor's proposed pipe material or his proposed pipe joint detail differ from that of the built-in pipe he shall submit details of the connection for the Engineer's approval before commencing work.

c) The Contractor shall take adequate precautions to ensure that no


(ADSSC)



constructional debris or groundwater from his working area enters any existing manhole or chamber or pipe.

d) The Contractor shall take adequate precautions to ensure continued

support to existing installations.

e) For manholes which are located within recently improved paved areas, approval to cut these paved surfaces may not be granted. It is the responsibility of the Contractor to seek the necessary permissions for his proposed method of working for the connections to these manholes.

f) When a connection is to be made to a manhole or chamber on an

existing pipeline or when new manholes/chambers are to be constructed either on existing pipelines or to replace existing manholes the following work shall be undertaken.

i. The conditions of the pipeline should be identified before any

connection work locally is carried out. ii. Dewatering shall not result in the flow of water along the pipe zone

material. The Contractor shall submit for the Engineer's approval, details of his proposed method of working and temporary works installations to achieve this. The Contractor shall also propose and adopt a method approved by the Engineer to monitor the ground water level over the existing sewers within 30m of the connection.

iii. Before commencing any dewatering works in the vicinity the Contractor shall undertake a closed circuit television survey (CCTV) of the existing sewer from the point of connection to the next upstream and downstream manhole. For GRP and PVC-u pipelines the Contractor shall also undertake a deflection survey. The deflection surveys shall measure vertical and horizontal pipe deflections at 2m intervals and at each side of a joint. He shall repeat the CCTV survey and deflection survey for GRP and PVC-u pipelines on completion of the connection and removal of the dewatering installation and at the end of the maintenance period. Should the Contractor's method of working cause a change in the condition of the existing pipeline or adversely affect the pipeline in any way, then he will be required to reinstate it at his own cost to a condition acceptable to the Engineer. The maximum deflection of the reinstated pipe shall be 3%.

4.3 CONTINUITY OF FLOWS

a) The construction of the new works may necessitate the replacement of some existing pipelines and pumping mains and the abandonment of facilities such as septic tanks. In order to ensure the continuity of the service to each and every property or area, the Contractor will be responsible for providing adequate temporary facilities to achieve this end, and maintain such, until all downstream works on the system have been completed, commissioned and taken over by ADSSC.

b) The Contractor shall obtain from ADSSC prior permission in writing


(ADSSC)



before carrying out any work on the existing system.

c) Such temporary facilities provided by the Contractor shall be in accordance with the requirements of Clause 4.4 below.

4.4 SEWER FLOW CONTROL

4.4.1 GENERAL

a) The Contractor should be aware of social and climatic conditions pertaining to Abu Dhabi particularly in dealing with sewage and consequential pumping and bypassing or diverting of sewage flows. All works shall be carried out in such manner as to cause minimum disruption, noise or any nuisance to the public.

b) Manholes and sewers being worked on shall be completely isolated and

bypassed such that they do not contain any sewage. This shall be achieved by plugging, pumping and bypassing or diverting the flow.

c) When flow in a sewer line is plugged, pumped and bypassed or diverted

sufficient precautions must be taken to protect the sewer lines from damage that might result from sewer surcharging. Further, precautions must be taken to ensure that sewer flow control operations do not cause flooding or damage to public or private property being served by the sewers involved.

4.4.2 PIPE STOPPERS

a) The flow shall be stoppered off using an approved type of pipe stopper. Stoppers shall be suitable for the sizes and classes of pipe in which they are used and must not cause damage to existing pipes. Stoppers must be able to withstand the maximum possible differential head at each location and shall be fully restrained in accordance with the manufacturers recommendations.

b) The Contractor shall be solely responsible for maintaining such stoppers

in good working condition and for the consequences of any failure thereof.

c) Where a section of the sewerage system is isolated for work involving

man-entry to the isolated area, a minimum of two stoppers shall be used at each boundary location isolating the area from the main sewer and subsidiary sewers. At least one of these stoppers at each location should be of an approved pneumatic type.

4.4.3 PUMPING AND BYPASSING OF FLOW

a) Pumping shall be carried out using suitable mobile pumpsets to the approval of the Engineer.

b) The pumps shall be controlled by suitable level controls installed to


(ADSSC)



operate at levels to be approved by the Engineer and shall be capable of dealing with the flow in the sewer and any material likely to be transported in it without being blocked.

c) The Contractor must provide enough temporary pumps of sufficient

pumping capacity or where approved, a temporary sump to avoid surcharging upstream sewers.

d) Constant full time attendance shall be provided by the Contractor at

each pumping location such that in the event of mechanical breakdown, flooding or blockage, immediate assistance will be summoned.

e) Discharge of pumped sewage shall be made to a manhole downstream

of the sewer length being surveyed. The open end of the pump discharge pipe shall be laid so as to minimise turbulence of the pumped flow.

f) The pump discharge pipe shall be of suitable armoured material which in

all locations subject to traffic flow shall be suitably protected with steel preformed plates bridging the pipe or by other approved means. Such protection shall be adequate to allow passage of vehicular traffic over the pipe without undue inconvenience.

g) The Contractor shall restrict the sewage residence time in bypass hoses

to not more than 10 minutes or as approved by the Engineer and shall provide adequate standby facilities of both suitable pumps and generators for use at short notice in the event of failure of either piece of equipment.

h) For main streets, non disruptive road crossings may be required and the

Contractor shall include the cost of constructing such crossings in his rates. It is possible that ducts or storm water sewers are available in the vicinity of the diversion which can be used by the Contractor to install his temporary bypass pipes after taking approval of the relevant authority.

i) On completion of pumping, the Contractor shall carry out sewer cleaning

by jetting, flushing or any other means required to return the sewer surcharged during pumping operations to a serviceable condition to the satisfaction of the Engineer.

4.4.4 TEMPORARY DIVERSION OF FLOW

a) If the Contractor considers it necessary for temporary diversion of sewers to be carried out to enable him to execute his work then he should notify the Engineer accordingly and submit his proposals for implementation of such diversion.

b) The Contractor shall give full details of pipe diameter, route, levels etc. In

such proposals, and subject to the Engineer’s approval, the Contractor shall be solely responsible for obtaining all other permissions and approvals relevant to the execution of such temporary works. On


(ADSSC)



completion of temporary diversionary works the relevant pipework shall be removed or be adequately sealed and inlet and outlet manholes returned to a condition suitable for their subsequent re-use, all to the approval of the Engineer. All diversionary work shall be subject to the requirements of the Contract as if they formed part of the Permanent Works.

4.4.5 ENTRANCES TO PRIVATE PROPERTIES

No pumps or equipment shall be fixed in front of private properties unless it is unavoidable and this shall be with the approval of the Engineer. When it is essential to close any access, the Contractor shall provide suitable alternative access at no extra cost to the Department. Vehicle access for emergency services shall be available at all times.

4.4.6 ODOUR CONTROL DURING PUMPING AND BYPASSING OR

DIVERTING OF FLOW

a) The Contractor shall take necessary arrangements for controlling odour and prevent any nuisance and inconvenience to the local residents and the public generally as a result of pumping and bypassing or diverting of flow.

b) The Contractor shall include in his proposed method the equipment and

chemicals he is proposing to use to contain the odour release for approval by the Engineer.

c) The Contractor shall install temporary chemical dosing system to contain

the odour release if other measures fail.

d) For odour control, the measurement of hydrogen sulphide shall not be more than 1ppm measured at a distance of 5m from the point of discharge.

4.4.7 GENERAL CLEANLINESS OF AREAS

a) The Contractor shall ensure that while removing manhole covers and subsequent cleaning operations there is no spillage of sewage, debris and other particles onto the streets, near manholes and other areas causing nuisance to the local residents and the public.

b) The Contractor shall clear all spillages, wash and clean affected

surfaces with water as and when spillage occurs.

END OF SECTION

Documents

11-Division 2-Section 02300 Sewage Works-Version 2.0