Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020)

No water shall be pumped into an existing or new drainage system, or to a environmentally sensitive
area (as defined by the environmental authority or by the Engineer) unless discharge is equipped
with a suitable sediment trap, filter or sedimentation tank, as approved by the Engineer.

Where necessary, the Contractor shall divert natural and artificial waterways encountered at the site,
until the works have been completed.

Route of the dewatering discharge main shall be approved by the Engineer.

g. Removal of Dewatering Systems

No dewatering system shall be removed without the approval of the Engineer. Release of
groundwater back to its static level shall be performed in a manner to prevent disturbance of natural
foundation soils, compacted fill or backfill and to prevent flotation or movement of structures,
pipelines and sewers.

Equipment shall only be removed when no longer required. Monitoring and settlement measurement
systems shall be maintained in operation as required by the Engineer.

If approved by the Engineer, well-points and like items may be abandoned in place.

Drainage provisions:

Drainage ditches, diversions and temporary pipes shall be constructed as required to
maintain proper drainage in the work areas

Drainage ditches shall be constructed with cross-sectional area and gradient at least equal
to that of the intercepted watercourses or as approved by the Engineer

Berms shall be provided to prevent surface water from draining into excavations

Earth banks shall be suitably protected from erosion during excavation work.

2.4.2.4

Rock Cuts

Contractor shall excavate rock cuts to 150 mm below subgrade level within the roadbed limits,
backfill to the subgrade with embankment materials that meet the requirements of Section
2.5.2.2 and compact the materials in accordance with Section 2.6.

Rock excavation using blasting shall meet the following requirements:

a. Rock Blasting

1. Description

Rock blasting consists of fracturing rock and constructing stable final rock-cut faces using
controlled and production blasting techniques.

Controlled blasting uses explosives to form a shear plane in the rock along a specified back
slope. Controlled blasting includes pre-splitting and cushion blasting.

Production blasting uses explosives to fracture rock.

Contractor shall be able to demonstrate suitable past experience and qualifications in the art of
construction blasting. Otherwise, a qualified Subcontractor shall be used. Experience and
qualifications, whether of the Contractor or a Subcontractor shall be submitted to the Engineer
for review and acceptance. No blasting work shall be started until written approval of the
Contractor’s qualifications and method statements have been approved by the Engineer.

2. Materials

Explosives and initiating devices less than one year old shall be used by the Contractor. These
include, but are not limited to, dynamite and other high explosives, slurries, water gels,
emulsions, blasting agents, initiating explosives, detonators, and detonating cord.

ARTHWORKS

3. Construction Requirements

I. Regulations

Furnish copies or other proof of all applicable permits and licenses that comply

with the requirements of the relevant government ministries. Upon Owner approval, the
Contractor shall comply with any additional requirements.

II. Safety and health. Comply with the requirements of Section 1.16.7 of Chapter 1, General

Requirements, and when required by the Engineer OSHA, Standard No. 1926, Subpart U.

III. Storage, security, and accountability. Provide proper buildings or magazines in suitable

locations for storage of explosives, in a manner as approved by the Engineer. All storage
shall be secure with locked access and guarded by security personnel 24 hours a day.
Provide for a detailed method of controlling and inventorying of all explosive materials, as
approved by the Engineer. All unused explosive materials shall be disposed of in a manner
approved by the Engineer and the approving governmental Owner.

IV. Blaster-in-charge. Designate, in writing, a blaster-in-charge, and submit evidence that the

blaster-in-

charge has specific and related experience, as well as a valid blaster’s license

issued by a recognized licensing body for the type of blasting required.

V. Blasting plans. Blasting plans are for quality control and record-keeping purposes, and are

to be signed by the blaster-in-charge. Review and acceptance of blasting plans does not
relieve the Contractor of the responsibility for using existing drilling and blasting technology,
and for obtaining the required results. Do not deliver explosives to the project until the
general blasting plan is accepted.

•

General blasting plan.

Submit a general blasting plan for acceptance before drilling

operations begin, which includes, at a minimum, the following safety and procedural
details:

•

Working procedures and safety precautions for storing, transporting, handling, and

detonating explosives

•

Proposed product selection for both dry and wet holes and furnished manufacturer’s
material safety data sheets for all explosives, primers, initiators, and other blasting
devices

•

Typical plan and section views for both production and controlled blasting, including

maximum length of the shot, burden, hole spacing, hole inclination, hole depth, hole
diameter, subdrill depth, and powder factor

•

Proposed initiation and delay methods and times

•

Proposed format for providing all the required information for the site-specific blasting

plans

•

Site-specific blasting plans. After the general blasting plan is accepted, the Contractor

shall submit site-specific blasting plans for acceptance before drilling operations
begin. The plan shall include the following information:

•

Site drawings showing a scaled map of the blast area and cross-sectional views that

indicate beginning and ending stations; free-face locations; hole spacing, diameter,
depth, burden, and inclination; and subdrill depth. Include any significant joints or
bedding planes within the blast zone and incorporate this geology into the blast
design.

•

Where blasting may affect nearby structures or utilities, the Contractor shall provide

the method of monitoring and controlling blast vibrations.

•

Provide a loading pattern diagram showing the location and amount of each type of

explosive to be used in the holes, including primer and initiators and the location, type,
and depth of stemming, column heights, and overall powder factor for each type of
loading.

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•

Provide a delay and initiation diagram showing the delay pattern, sequence, and delay

times.

•

Preblast condition survey and vibration monitoring and control. When blasting near

buildings, structures, or utilities that may be subject to damage from ground or air-
blast vibrations, the Contractor shall provide a blast vibration specialist with at least
five consecutive years of experience in vibration monitoring for at least three projects.
Fourteen days before blasting, the Contractor shall submit to the Engineer the name
and qualifications of the blast vibration specialist including the following information:

•

Project names, locations, and services performed

•

Name and phone number of an owner or agency contact who can verify the

experience of the specialist

•

Relevant qualifications and licences

Before blasting, the Contractor shall arrange for a pre-blast condition survey of nearby
buildings, structures, or utilities that may be at risk from blasting damage, and shall use a
survey method acceptable to its insurance company. Damage resulting from blasting is the
Contractor’s responsibility. All pre-blast condition survey records shall be made available to
the Engineer and the Contractor shall notify the Engineer and occupants of nearby buildings
at least 24 hours before blasting.

Vibrations shall be controlled by a blast vibration specialist using properly designed delay
sequences and allowable charge weights per delay when blasting near buildings, structures,
or utilities that may be subject to damage from blast-induced vibrations. Trial blasts shall be
conducted to measure vibration levels and base allowable charge weights per delay. Test
blasts shall be conducted with blast plan modifications that limit ground and air-blast
vibrations to a level that will not cause damage to nearby buildings, structures, or utilities, as
determined by the blast vibration specialist.

When  vibration  damage  to  buildings,  structures,  or  utilities  is  possible,  the  blast  vibration
specialist  shall  monitor  each  blast  with  approved  seismographs  and  air-blast  monitoring
equipment  located  at  acceptable  locations.  Seismographs  capable  of  recording  particle
velocity for three mutually  perpendicular  components  of  vibration shall  be  used.  The  blast
vibration specialist shall interpret the seismograph and air-blast records to ensure that the
data is effectively used in the control of blasting operations.

VI. Test Blasting. Before full-scale drilling and blasting, the Contractor shall drill, blast, and

excavate one or more test sections as proposed in the blasting plan. Test blasts may be
made away from or at the final slope line.

For the cushion, or trim, method of controlled blasting, the Contractor shall space blast holes
no more than 1.5 m apart for the initial test blast. For the pre-splitting method of controlled
blasting, the Contractor shall space blast holes no more than 750 mm apart for the initial
test blast. Spacing shall be adjusted as approved. Contractor shall use the approved
spacing in the full-scale blasting or subsequent test blasts.

A test blast is unacceptable when it results in fragmentation beyond the final rock face, fly
rock, excessive vibration, air blast, over break, damage to the final rock face, or overhang.
When a test blast is unacceptable, the Contractor shall revise the blasting plan and make
an additional test blast.

VII. Blasting.

a. General. Drill and blast according to the blasting plan.

Before drilling, the Contractor shall remove overburdened soil and loose rock along
the top of the excavation for at least 10 m beyond the hole drilling limits, or to the end
of the cut.

All holes shall be capped to prevent unwanted backfill. Place a stake next to each
hole that numbers each hole and displays the total depth drilled.

Use the types of explosives and blasting accessories necessary to obtain the required
results. A bottom charge may be larger than the line charges if no over break results.

After blasting, the hole shall be free of obstructions for its entire depth. Charges shall
be placed without caving the blast hole walls. The upper portion of all blast holes shall
be stemmed with dry sand or other granular material passing the 9.5-mm sieve. Do
not stem the hole with drill cuttings.

Following a blast, the Contractor shall stop work in the entire blast area and check for
misfires before allowing workers to excavate the rock.

Workers shall remove or stabilise all cut face rock that is loose, hanging, or potentially
dangerous. They shall scale by hand or machine methods, as approved by the
Engineer. Minor irregularities or surface variations shall be left in place, if they do not
create a hazard. Drill the next lift only after the cleanup and stabilisation work is
complete.

If blasting operations trigger fracturing of the final rock face, the Contractor shall repair
or stabilise it in an approved manner at no cost to the Owner. Repairs or stabilisation
may include removal, rock bolting, rock dowels, or other techniques.

When any of the following occur, the Contractor shall halt blasting operations to
perform additional test blasts:

▪

Slopes are unstable

▪

Slopes exceed tolerances or overhangs are created

▪

Back slope damage occurs

▪

Safety of the public is jeopardized

▪

Property or natural features are endangered

▪

Fly rock is generated

▪

Excessive ground or air-blast vibrations occur in an area where damage to

buildings, structures, or utilities is possible

b. Drill logs. Drill logs submitted by the Contractor shall include the following:

▪

A blast plan map showing designated hole numbers

▪

Individual hole logs completed and signed by the driller that show total depth

drilled; depths and descriptions of significant conditions encountered during
drilling that may affect loading, such as water or voids; and the date drilled

c. Controlled blasting. When test blasts indicate the need for controlled blasting, the

Contractor shall use controlled blasting methods to form the final rock cut faces when the
rock height is more than 3 m above ditch grade and the staked slope has a ratio of 2:1 or
steeper.

Controlled blasting includes only those holes drilled on the row furthest from the free-face
and that are drilled on the design slope.

Down-hole angles or fan drill blast holes shall be used for pioneering the tops of rock cuts
or preparing a working platform for controlled blasting. Use the diameter of the blast hole
and spacing established for controlled blasting during the test blasts.

Drill controlled blast holes no larger than 100 mm in diameter along the final rock face
line; within 75 mm of the proposed surface location; and at least 10 m beyond the
production holes to be detonated or to the end of the cut.

Drilling equipment with mechanical or electrical-mechanical devices that accurately
control the angle the drill enters the rock shall be used. Select a lift height and conduct
drilling operations so the blast hole spacing and down-hole alignment does not vary more
than 225 mm from the proposed spacing and alignment. When more than 5 percent of
the holes exceed the variance, reduce the lift height and modify the drilling operations
until the blast holes are within the allowable variance. The maximum lift height is 15 m.

A 600 mm offset is allowed for a working bench at the bottom of each lift for drilling the
next lower controlled blasting hole pattern. Adjust the drill inclination angle or the initial
drill collar location so the required ditch cross-section is obtained when the bench is used.

Drilling 500 mm below the ditch bottom is allowed for removing the toe.

Do not use bulk ammonium nitrate and fuel oil for controlled blasting.

Pre-splitting delays the nearest production blast row at least 25 milliseconds after blasting
the presplit line. Pre-split a minimum of 10 m ahead of the production blasting zone.

Cushion, or trim, blasting can delay the cushion blast row from 25 milliseconds to 75
milliseconds after blasting the nearest production row.

d. Production blasting. Drill the row of production blast holes closest to the controlled blast

line parallel and no closer than 2 m to the controlled blast line. Do not drill production
blast holes lower than the bottom of the controlled blast holes.

Detonate production holes on a delay sequence toward a free-face.

VIII. After blast reports.

Within three days after a blast and before the next blast, the Contractor shall submit an
after-blast report that includes the following:

a. Results of the blast and whether or not blasting objectives were met. If blasting objectives

were not met, the Contractor shall submit proposed changes to future site-specific
blasting plans that shall produce acceptable results and proposed repair or stabilisation
plans for unstable or blast-damaged back slopes.

b. Blasting logs that include the following:

All actual dimensions of the shot, including blast hole depths, hole diameter, burden,
spacing, subdrilling, stemming, powder loads, and timing

ii.

A drawing or sketch showing the direction of the face, or faces, and the physical
shot layout

iii.

If a seismograph was used, the Contractor shall provide the following:

(1)

Identification of instrument used

(2)

Name of qualified observer and interpreter

(3)

Distance and direction of recording station from blast area

(4)

Type of ground recording station and material on which the instrument is sitting

(5)

Maximum particle velocity in each direction

(6)

A dated and signed copy of the seismograph readings

(7)

Post-blast condition survey

(8)

Results of air-blast monitoring

(9)

Results of the post-blast condition survey

2.4.2.5

Subexcavation

Unsuitable material, including soft, muck, or vegetative material, shall be excavated by the
Contractor to the limits designated by the Engineer. Cross-sections shall be taken in accordance

with Section 2.1. Prevent unsuitable material from becoming mixed with the backfill. Unsuitable
material shall be disposed of in accordance with Section 2.4.2.7 Sub-excavated limits shall be
backfilled with suitable load bearing material in accordance with Section 2.5.3.

When water fills an area after the removal of unsuitable materials, the Contractor shall drain the site
so  that  any  backfill  may  be  compacted.  If  drainage  is  not  possible,  the  Contractor  shall  use  free
drainage material which can be hydraulically compacted for backfilling in water.  Backfill method and
materials shall be approved by the Engineer, and shall be carried out on the Contractor’s expense.

2.4.2.6

Slope Treatment

Earth slopes shall be finished to reasonably smooth surfaces and shall be free of all debris and loose
material. All shattered or loosened material shall be removed from rock cut slopes.

Tops of all roadway cut slopes, except solid rock cuts, shall be rounded in accordance with the
Contract plans.

Surfaces of earth slopes shall be left in a uniform and smooth condition, trimmed, and graded to no
more than ±50 mm of the neat lines shown on the Contract plans. Where the slopes of earth
excavations are to be covered with topsoil or other agricultural planting soil, the excavated surface
shall be caterpillar tread-walked in a vertical direction, or similar measure, to roughen the surface
and help hold the upper topsoil layers.

If a layer of earth covers a rock cut, the slope shall be rounded above the rock as if it were an earth
slope. All work required to complete slope treatment, including excavation, haul, and slope rounding,
shall be included in the unit price for roadway excavation.

2.4.2.7

Disposal of Unsuitable or Excess Material

Unsuitable or excess material shall be disposed of off-site at disposal sites furnished by the
Contractor and approved by the Engineer. Waste material shall be shaped and compacted in its final
location.

If  the  Contractor  or  Engineer  finds  any  evidence  of  petroleum  or  other  hazardous  products
contamination  of  any  excavated  material  by  visual,  olfactory,  or  other  means,  the  potentially
contaminated  material  shall  be  stockpiled  separately  and  sampled  and  analysed  to  determine
disposal options.

Material that is excavated and deemed unsuitable or as excess material shall be placed in a covered
transport and hauled to the disposal site. Excavated material shall not spill, overflow, or release
during transport to the disposal site.

Soil that is designated for landfill disposal and contains free water shall be stabilised using lime,
cement, or fly ash, where required by the disposal facility.

Soil shall not be transported off-site in containers with water draining from the container.

2.4.2.8

Wasting Material

If the Contractor wastes excavated material needed for the embankment or other fill, it shall be
replaced at no expense to the Owner with material the Engineer approves.

2.4.2.9

Roadway Ditch and Pond Excavation

a. Description

This work consists of excavating permanent open ditches and ponds to the required lines, grades,
and cross-sections as shown on the Contract plans. It also includes disposing of all excavated
material regardless of its nature or type; unless excavated material is approved as borrow material.

ARTHWORKS

b. Construction requirements

Before excavating any open ditch or pond, the Contractor shall clear and grub the area in accordance
with Section 2.2.

Where  the  excavated  ditch  or  pond  material  is  approved  for  use  as  embankment  material  in
accordance  with  the requirements  of  Section 2.5.2.2,  the  material  shall  be  used  to  build  dikes  or
berms  as  shown  on  the  plans.  Dikes  and  berms  shall  be  constructed  in  accordance  with  the
requirements for roadway embankment compaction in Section 2.5.3.

Excess excavated material may be disposed of by dressing or spreading above the back slopes of
ditches and outside of dikes and berms, as approved by the Engineer. Otherwise, the Contractor
shall dispose of excess excavation material in accordance with Section 2.4.2.7.

At each transition from cut to fill, the Contractor shall divert any roadway ditch away from the
embankment in natural ground. Ditches shall never permit water to flow into or upon embankment
material.

2.4.2.10

Borrow Excavation

All suitable roadway excavation shall be used by the Contractor in embankment construction, and
borrow excavation shall not be used when it results in excess roadway fill material.

Borrow sources shall be preapproved by the concerned authorities and the Engineer. Approval shall
be based on the Contractor’s submittal of location, sample testing, estimation of quantities, written
approval of the borrow source owner and/or regulating authority, and restoration of borrow source
upon completion as shown on the shop drawings. For borrow sources to be accepted, the material
shall meet the requirements for the applicable load-bearing or non-load-bearing material
requirements in Section 2.5.2.

Develop and restore borrow sources in accordance with the Engineer-approved methods. Do not
excavate beyond the established limits. When applicable, the Contractor shall shape the borrow
source to permit accurate measurements when excavation is complete. Borrow sources shall be left
in a manner that is pleasing to the eye, with excavated slopes and surfaces left in a smooth and
uniform shape at geotechnical stable angles. No extra payment will be made for restoration and
final grading of the borrow source.

2.4.2.11

Structural Excavation

a. General

Contractor shall include all operations necessary to excavate, as required for the construction of the
structures, and as indicated on the Contract plans.

This  work  shall  consist of  the  necessary  excavation for  construction  of minor  structures  including
storm  drain  and  utility  structures  and  wall  items  as  otherwise  specified  in  these  general
specifications. Contractor will not be paid for excavation of any minor structures or portions of minor
structures  that  are  constructed  within  the  volume  of  the  roadway  embankment  excavation  or  fill
prism.  This  work  shall  include  necessary  dewatering,  sheeting,  bracing, construction  of  cribs  and
cofferdams, furnishing materials, and the subsequent removal of cribs and cofferdams.

Excavation to remove and replace unsuitable material encountered below the structure foundation
elevation shall meet the requirements of Section 2.4.2.5. Depending on conditions, the Engineer
may require the use of alternative materials as replacement fill for sufficient foundation strength. This
may include one of the following materials:

1. Load-bearing embankment material meeting the requirements of Section 2.5.2.2

2. Structural backfill material meeting the requirements of Section 2.5.2.4

3. Pervious backfill material meeting the requirements of Section 2.5.2.5

4. Controlled density fill meeting the requirements of Section 4.3.10.3 of Chapter 4, Concrete

Works, of these Standards Specification.

b. Excavation Support

All excavations measuring 1.5 m or more in depth, trench or otherwise, shall be laid back to a stable
slope or supported. Excavation support systems are subject to the approval of the Engineer. Prior to
commencing any structure excavation work 1.5 m or more in depth, the Contractor shall design and
submit detailed shop drawings of the structure excavation support systems and proposed methods
to the Engineer. These submissions shall show support member materials, sizes, spacing, and
Engineering calculations to validate the design of the above, including the maximum theoretical
deflections of the support members.

Support systems shall be designed in such a manner that no sheeting, struts, or any other support
members extend through surfaces exposed in the finished construction, and no shoring or bracing
is placed under permanent structures.

Engineering  calculations  shall  be  in  English  and  shall  show  lateral  earth  pressures  for  the  full
excavation  depths;  forces  at  various  stages  of  support  during  installation,  removal,  and  concrete
placement;  anticipated  equipment  loads;  surcharge  loads  of  any  description;  and  the  maximum
design loads carried by various members of the support system and strut pre-load forces.

In  the  event  the  proposed  structure  excavation  support  system  includes  tieback  anchors,  the
Contractor's  submittal  drawings  shall  show  the  profile  of  the  soil  in  which  each  anchor  is  to  be
installed,  the  design  load  for  the  full  depth  of  excavation,  the  maximum  design  and  proof  loads,
surcharge  loads  of  any  description,  equipment  loads,  forces  at  various  stages  of  support  during
installation and removal, and the criteria proposed for deformations under proof loads.

Where a proposed system of tieback anchors projects beyond the vertical projection of the Contract
limit lines indicated on the Contract plans onto the adjoining property, the Contractor shall obtain the
permission of the owner in writing, and submit such permission to the Engineer at the time the shop
drawings of the support system are submitted.

c. Excavation Limits

So that cross-sectional elevations and measurements may be taken of the undisturbed ground, the
Contractor shall notify the Engineer sufficiently in advance of any structure excavation. Natural
ground adjacent to the structure shall not be disturbed without the Engineer’s permission.

Structures shall be excavated to the lines and grades or elevations indicated on the Contract plans,
or as described in the bill of quantities. Excavations shall be of sufficient size to permit the placing of
structures or structure footings of the full width and length indicated.

Unless otherwise specified, the excavation limits for structural excavation shall be from the bottom
level (formation level) of the roadway excavation which falls within the roadway excavation width.

Boulders, rocks, and any other objectionable material encountered during excavation shall be
removed.

After each excavation is completed, the Contractor shall notify the Engineer. No footing, bedding
material, or structure shall be placed until the Engineer has approved the depth of excavation and
the character of the material on which the foundations shall bear.

d. Disposal of Excavated Materials

All excavated material at structures shall be loaded and hauled away to an approved disposal area
in accordance with Section 2.4.2.7, unless the excavated materials are approved by the Engineer
for use as borrow material meeting the applicable requirements of Section 2.5.2.

2.4.2.12

Manual Excavation

General

All manual or hand excavation and other required work to locate existing utilities or services within
the limits of the Contract or at off-site locations shall be performed by the Contractor in accordance
with the requirements of these general specifications and as directed by the Engineer.

ARTHWORKS

Existing utilities and services to be located by manual excavation shall include, but not be limited to,
all water mains and electric lines, both power and lighting; telephone; and others that may be
encountered under the Contract or at off-site locations.

Coordination with Utility Departments

Purpose of manual excavation is to determine the existence and location, including depth, size,
shape, composition, and condition, of all existing utilities and services. Immediately after uncovering
existing utilities, the Contractor shall coordinate with the respective utility departments and agencies
to obtain their assistance, if necessary, for the accurate identification of each uncovered utility line.

Information obtained during this process shall be recorded and shown on working or shop drawings
that the Contractor shall submit to the Engineer and the relevant utility agencies. Utility agencies
shall require this information to finalise relocation or protection plans.

Procedure

Before commencing manual excavation, the Contractor shall obtain the Enginee

r’s approval and

obtain specific work permits from respective utility agencies for manual excavation in close proximity
to important utility lines such as, but not limited to, 11 kV, 33 kV circuits, 132 kV circuits, water
transmission and distribution main lines, and telephone and gas lines.

Contractor shall furnish the Engineer with copies of all work permits, field notes, and shop drawings
with the details of all utilities and services located by manual excavation, as recorded by the
Contractor.

Width of manually excavated trenches shall be such that a workman can excavate safely and
efficiently to a depth determined as reasonable by the Engineer in consideration of existing utilities
information.

Manual excavations shall be carried out in the presence of the Engineer, taking all precautions to
prevent damages to services, properties, and persons. Any damage resulting from the negligence
of the Contractor shall be repaired at the Contractor’s expense. This is in addition to any indemnities
stipulated in these specifications dealing with public utilities and safety.

Contractor shall provide all tools, labour, equipment, and accessories required to complete the
manual excavation. Further, the Contractor shall provide all the materials, labour, and equipment
necessary to protect the existing utilities, as well as any shoring, sheeting, dewatering, and any other
means required for protection during manual excavation.

All materials removed shall be disposed of by the Contractor in accordance with Section 2.4.2.7,
unless the excavated materials are approved by the Engineer as material meeting the applicable
requirements of Section 2.5.2.

All  manually  excavated  trenches  within  traffic  and  pedestrian  pavement  areas,  other  structure
foundation areas, and where necessary for adjacent structure or utility lateral and vertical bearing
support  shall  be  backfilled  with  load-bearing  embankment  material  in  accordance  with  the
requirements  of  Article  c  of  Section  2.5.3.1.  Trenches  within  non-load-bearing  areas  shall  be
backfilled in accordance with Section 2.5.3.3.

Contractor shall place and compact material with care so as not to damage existing utilities.

2.4.2.13

Unclassified Excavation

Unclassified excavation shall include any and all materials encountered during the construction of
the Work. This classification shall not apply to any material, which has been classified and bid upon
under any of the foregoing classifications, "Borrow Excavation", "Rock Cut", "Structure Excavation"
or “Manual Excavation”.

2.5

Embankments and Backfill

2.5.1

Description

Embankment  and  backfill  requirements  shall  apply  to  the  construction  of  roadway  embankments,
including  the  widening  of  embankment  sections  and  the  preparation  of  the  areas  upon  which
embankment  material  is  to  be  placed;  the  construction  of  dikes  and  berms;  the  placing  and
compacting of material where unsuitable material has been removed; backfill for structures and the
placing of non-load-bearing, topsoil and sweet sand materials in landscaping areas; and other areas
not under roadway and pedestrian pavements.

Before the start of construction, the Contractor shall submit plans showing the proposed method of
work, the selection of materials, the method of compaction, and any other matter that may affect the
construction of the embankment or sequence of operations.

2.5.2

Materials

2.5.2.1

Unsuitable Material

Unsuitable material includes but not limited to

•

Topsoil,

•

Organic soils,

•

Vegetative material,

•

Trash,

•

Contaminated soil,

•

Soluble material such as gypsum and salt, very fine sand, non-cohesive silt, organic clay

and highly dispersive soils.

Dispersivity potential of soil shall be determined by test ASTM D4647. Any material classified other
than ND1 or ND2 (non dispersive) will be considered as unsuitable.

Materials with soluble substances more than 3% (by test method ASTM D4542) and organic content
more than 5% (by test method ASTM D2974) by weight of dry material are all considered as
unsuitable and shall not be used for construction of embankment.

Collapsible soils are also considered as unsuitable material and shall be treated before construction
of embankment. Collapse index is determined according to ASTM D5333.

2.5.2.2

Embankment Material (Load-Bearing)

Load-bearing embankment material shall consist of suitable material taken from the roadway
excavation or the borrow source. Load-bearing embankment material shall consist of granular
material free of excess moisture and other unsuitable material conforming to the following:

1. Maximum particle size: not to exceed one-third of placement layer thickness

2. Materials shall be classified according to AASHTO M 145. In general, suitable materials shall

meet soil classification: A-1, A-3, or A-2-4.

3. Material that can be compacted to 95 percent of the maximum density as required in Article

b of Section 2.5.3.4

4. Material shall have a maximum plasticity index of 6 and a soaked CBR after 4 days soaking

is not less than 20% when compacted to 95% of MDD.

Suitability tests including material gradation, plasticity and CBR tests shall be done in accordance
with Table 2-12. All suitability testing will be done with one test each per 1000 m

of embankment

material.

Embankment material placed adjacent to bridge abutments, retaining and wing walls, and other
minor structures, as shown on the Contract plans or as directed by the Engineer, shall be classified
as structure backfill and shall conform to the requirements in Section 2.5.2.4, except for drainage
layer backfills when shown on the Contract plans, which shall conform to the requirements of Section
2.5.2.5 for pervious backfill.

2.5.2.3

Rock Fill Material

Rock fill material shall be made of strong, hard, durable, and clean pieces of sound rock, having the
following requirements:

1. Point load strength index (I

s50

) (per ASTM D5731) greater than 1 mPa

2. Maximum wet/dry strength variation of 35 %

3. Maximum and minimum dimensions are determined based on the application, however the

maximum dimension for embankment construction shall be 600 mm.

Rock fill material borrow source(s) shall be pre-identified and submitted with samples and test results
meeting the above requirements for review and approval by the Engineer prior to delivery of the
material to the site.

Typically, rock fill material excavated from within the roadway excavation prism will be incorporated
within the embankment fill, if meeting the requirements as specified herein. Otherwise it will be
disposed of by the Contractor at the sites and locations as approved by the Engineer.

2.5.2.4

Structural Backfill

Structural backfill shall be a uniform mixture of gravel and/or stone fragments with sand, silt and clay,
conforming to the following requirements:

1. A maximum particle size of 53 mm

2. Material gradation meeting the requirements in Table 2-3

3. Liquid limit: 25 maximum

4. Uniformity coefficient: >10

5. Plasticity index: 4 maximum

6. Sand equivalent (AASHTO T 176): 25 Minimum

7. Loss by abrasion (AASHTO T 96): 40 Maximum

8. Material that can be compacted to 95 percent of the maximum density as required in Article

b of Section 2.5.3.4 with a maximum dry density: minimum 20 kN/m

9. Minimum soaked CBR (remoulded sample after 4-days soaking, AASHTO T193: 60%

minimum at 95% compaction

Material gradation, liquid limit and plasticity tests shall be done in accordance with Table 2-12. All
suitability testing will be done with three tests each per 1000 m3 of select material except for
gradation testing which shall be one test per 1000 m

Table 2-3: Structural backfill gradation

Sieve size

Percent by mass passing designated sieve

(AASHTO T 27 and T 11)

53 mm

100

37.5 mm

75-100

ARTHWORKS

Sieve size

Percent by mass passing designated sieve

(AASHTO T 27 and T 11)

25.0 mm

55 -85

19.0 mm

50 - 80

9.5 mm

40 - 70

4.75 mm

30 - 60

2.0 mm

20 - 50

425 µm

10 - 30

75 µm

5 - 15

2.5.2.5

Pervious Backfill

Pervious backfill material shall be clean, hard, durable sand, gravel or crushed stone free from
organic material, clay balls or other deleterious substances conforming to the gradation requirements
in Table 2-4 Pervious backfill material used as a drainage layer against soil retaining structures (such
as bridge abutments and cut or fill retaining walls) shall meet the gradation requirements of Table
2-5

Table 2-4: Pervious backfill gradation

Sieve size

Percent by mass passing designated

sieve (AASHTO T 27 and T 11)

53 mm

100

37.5 mm

95 - 100

19 mm

50 to 100

9.5 mm

15 - 55

2.36 mm

0 - 5

75 µm

0 - 3

Table 2-5 Pervious backfill material for use as drainage layer against soil retaining

structures such as bridge abutments and retaining walls

Sieve size

Percent by mass passing designated sieve

(AASHTO T 27 and T 11)

75 mm

100

53 mm

90 - 100

37.5 mm

35 - 70

25.0 mm

0 - 15

ARTHWORKS

Sieve size

Percent by mass passing designated sieve

(AASHTO T 27 and T 11)

12.5 mm

0 - 5

2.5.2.6

Material for Free-Draining Blankets

Material for free draining blankets, used for constructing vertical drains or as a base layer for
embankments constructed over soft foundations, shall consist of either a clean processed aggregate
material meeting the gradation requirements of Table 2-6 or natural dune sand obtained from a
clean, uniformly open graded and non-contaminated source.

Table 2-6: Gradation for free-draining blanket material

Sieve size

Percent by mass passing designated

sieve (AASHTO T 27 and T 11)

75 mm

100

19 mm

95 - 100

4.75 mm

50 - 100

1.18 mm

20 - 85

0.3 mm

3 -30

0.15 mm

0 - 7

0.075 mm

0 - 3

2.5.2.7

Non-Load-Bearing Material

Non-load-bearing material shall include topsoil and sweet sand material in accordance with the
requirements of Article a of Section 2.5.2.7

Non-load-bearing material shall also consist of roadway excavation or other borrow material
approved by the Engineer and deemed suitable for use as fill material for raising existing areas not
located under roadway pavements, roadway embankments, pedestrian pavements, or other
structures, and to grades shown on the Contract plans. This material may also fill low-lying natural
areas to grades suitable for placing upper topsoil or sweet sand courses within landscaped areas,
in accordance with the Contract plans or as directed by the Engineer.

Material shall be reasonably free from salts, refuse, roots, heavy or stiff clay, stones or rocks larger
than 30 mm in size, sticks, brush, litter, or other deleterious materials or substances.

Topsoil and Sweet Sand Material

Topsoil shall consist of the material excavated and stockpiled in accordance with Section 2.2.2.5.

Sweet sand shall consist of borrow material supplied from sources approved by the Engineer, which
has been analysed by the Contractor as being suitable for agricultural purposes. Sweet sand shall
be obtained from well-drained inland dunes and shall be reasonably free from salts, refuse, roots,
heavy or stiff clay, stones or rocks larger than 30 mm in size, noxious seeds, sticks, brush, litter,
debris, or other deleterious materials or substances.

Topsoil and sweet sand borrow material destined for placement on the surface of vegetated
landscape areas and existing soil surfaces to remain in place within project constructed vegetated
landscape areas shall be tested and amended, as necessary, to comply with the requirements of

planting soil described in Section 13.1.2.1 of Chapter 13, Landscaping and Irrigation of these
Standard Specifications.

2.5.2.8

Prefabricated Vertical Drains

Prefabricated vertical drains (PVD) for embankment foundation water pressure relief shall consist of
a continuous plastic drainage core wrapped in a non-woven geotextile material, as approved by the
Engineer.

PVDs shall be of newly manufactured materials from an approved manufacturer, and shall comply
with the requirements as indicated in Table 2-7. For each type of drain to be used, the manufactured
PVD to be used on site shall be subjected to all the tests in the table. The types of PVD to be used
at site shall be approved by the Engineer.

Geotextile  shall  be  capable  of  resisting  all  bending,  puncturing  and  tensioning  subjected  during
installation and design life of the drain.  Core shall be made of continuous plastic material fabricated
to facilitate drainage along the axis of the vertical drain.  Core shall be a profiled strip with or without
perforation or a profiled mat with an open or closed structure.

Contractor shall indicate the proposed source of the materials prior to delivery to site. Contractor
shall also submit samples

and manufacturer’s certificates to verify the physical, mechanical and

hydraulic properties of the drain to be used for the Engineer’s approval.

Prior to installation and at the discretion of the Engineer, an individual test sample shall be cut from
at least one roll selected at random to represent each batch or every 100,000 meters, whichever is
less.  Individual sample shall be not less than 3 m in length and shall be full width.  Samples shall
be  tested  for  the  properties  listed  in  the  following  table.    Should  any  individual  sample  randomly
selected  fail  to  meet the  specification,  then  that roll  shall  be  rejected  and  two  additional  samples
taken at random from two other rolls.  If either of these two additional samples fail, then the entire
batch of vertical drains represented by the samples will be rejected by the Engineer.

Table 2-7: Vertical filter drain properties

Properties

Required value

Test

designation

Drain properties

Width (mm)

100 ± 2

Thickness (mm)

3 to 4

Discharge capacity for straight drain at hydraulic gradient
i = 0.1 and 250 kPa* (m

/s)

≥ 50x10

-6

ASTM D4716

Discharge capacity for buckled drain at hydraulic gradient
I = 0.1 and 150 kPa* (m

/s)

≥ 15 x10

-6

ASTM D4716

Tensile strength (kN)

1.5 @ 10 %

strain

ASTM D4595

Elongation at break (%)

≥ 2

Elongation at 0.5 kN (%)

≤ 10

ASTM D4362

Geotextile (Class 1 as per AASHTO M 288)

Grab tensile strength (N)

> 950

ASTM D4632

ARTHWORKS

Properties

Required value

Test

designation

Elongation at break

>70 %

ASTM D4632

Trapezoidal tear strength (N)

375

ASTM D4533

Puncture resistance (N)

> 2000

ASTM D6241

Burst strength (kN/m

)

> 900

ASTM D3786

Permeability at 100 mm head (m/s)

≥ 1x10

-4

ASTM D4491

Permitivity (s

-1

)

> 0.4

ASTM D4491

Apparent pore size, O

(micron)**

> 80

ASTM D4751

Fabric Weight (g/m

)

180

Manufacturer

*If (drain depth + 2 x fill height ) > 25 m but < 50 m, pressure shall be 500 kPa for straight drain
and 350 kPa for buckled drain.

**Alternatively, O

shall be < 90 micron

Drains shall be free of defects, rips, holes, or flaws. During shipment and storage, drains shall be
wrapped in a heavy-duty protective covering, and the storage area shall protect the drain material
from sunlight, mud, dirt, dust, debris, and detrimental substances.

2.5.2.9

Construction Geotextile

Geotextile fabrics shall consist only of long-chain polymeric fibers or yarns formed into a non-woven,
needle-punched  stable  network  such  that  the  fibers  or  yarns  retain  their  position  relative  to  each
other  during  handling,  placement,  and  design  service  life.  At  least  95% by  weight  of  the material
shall be polypropylene, polyolefin or polyesters. These materials shall be free from defects or tears.
Materials  shall  also  be  free  of  any  treatment  or coating  that  might  adversely  alter  its  hydraulic  or
physical properties after installation.

Thread  used  for  sewing  geotextile  shall  consist  of  high-strength  polypropylene,  polyester,  or
polyamide.  Nylon  threads  shall  not  be  allowed.  Thread  used  to  sew  permanent  erosion-control
geotextile,  and  to  sew  geotextile  seams  in  exposed  faces  of  temporary  or  permanent  geotextile
retaining  walls,  shall  also  be  resistant  to  ultraviolet  (UV)  radiation.  Thread  shall  be  of  contrasting
colour to that of the geotextile itself.

Geotextile shall meet the application requirements of AASHTO M 288 and the specific requirements
included in Table 2-8 through Table 2-12, in accordance with its intended use.

All geotextiles used in construction which are to receive an overlying layer of rock fill such as, but
not limited to, pervious backfill, rip rap, boulders or other similar covering material shall be protected
from damage due to the rock fill by placement of 50 mm thick layer of natural screened sand with a
nominal size between 3 mm and 5 mm, as approved by the Engineer.

Contractor shall submit the following information regarding each geotextile

material’s proposed use

to the Engineer:

Manufacturer’s name and current address

2. Full product name

3. Geotextile structure, including fiber or yarn type

4. Geotextile polymer types

5. Proposed Geotextile uses

6. Certified test results for minimum average roll values

Table 2-8: Geotextile for underground drainage

Geotextile property

ASTM

test method

Geotextile property

requirements

Non-woven

Fabric weight

D5261

180 g/m

minimum

Grab tensile strength, in
machine and x-machine
direction

D4632

700 N minimum

Grab failure strain, in
machine and x-machine
direction

D4632

≥ 50 percent

Puncture resistance

D6241

1375 N minimum

Tear strength, in machine
and x-machine direction

D4533

250 N minimum

UV radiation stability

D4355

50 percent strength retained

minimum, after 500 hours in a

xenon arc device

Table 2-9: Geotextile for underground drainage-opening size properties

Geotextile

property

ASTM test

method

Geotextile property requirements

Percent in situ Soil Passing 0.075 mm

<15

15 to 50

>50

AOS

D4751

< 425 µm

< 212 µm

standard sieve

< 150 µm

Water

permittivity

D4491

0.5 sec

-1

minimum

0.2 sec

-1

minimum

0.1 sec

-1

minimum

Table 2-10: Geotextile for separation or soil stabilization

Geotextile property

ASTM test method

Geotextile property requirements

Separation

Soil stabilization

Weight

D5261

180 g/m

minimum

200 g/m

minimum

Thickness

D5199

1.7 mm minimum

AOS

D4751

Standard sieve 212

µm max.

Standard sieve 212

µm max.

Water permittivity

D4491

0.02 sec

-1

minimum

0.05 sec

-1

minimum

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 1 - ROADS, Second Edition 2020) - page 20