Method statement for earthworks – Batu sewerage treatment plant

project at Batu, Jinjang Kepong.

WANG HUI

POWER CHINA RESOURCES LIMITED

BEI JING 100048

CONTENT

1. Introduction

2. Programme Reference

3. Construction Machinery/ Equipment Used

4. Manpower

5. Construction / Operation Procedure

6. Health & Safety

7. Appendix

1. Introduction

This method statement describes the earthworks operations for the construction of

underground sewerage treatment plant and the scope of work including deep excavation

varying from 18m to 22.5m from the existing ground level, rock blasting and hacking

works for limestone and disposal of excavated materials to dumping site by licensed

trucks.

i ) Excavation Works

The deep excavation requires much attention to structural and geotechnical expertise

as well as contractor itself. The consideration involved in design and planning of

contiguous bore pile, skin wall, temporary steel strutting, dewatering of ground water,

temporary access road and temporary drainage system contributed to safety and

economic aspect which should be emphasized during early stage of underground deep

excavation works. In engineering aspect, the deep excavation will induce stresses in the

ground mass around the excavation changes. The most common changes in stresses in the

retained side are the stresses relieved on the excavation face resulting in the horizontal

ground movement and being followed by vertical movement for equilibrium. It increases

vertical stress due to lowering water table resulting in both immediate and consolidated

settlement of the ground. Improper sequence of excavation will contribute damage to

surrounding or adjacent building and property..

ii) Rock Blasting Works

This method statement describes the rock blasting works below existing ground

level within the project site. Blasting is performed to loosen rock in order that it may be

excavated or removed from its existing position. Blasting is accomplished by discharging

on an explosive that has been placed in a hole especially provided for this purpose. The

energy associated with an explosion is the result of the pressure produced in the gases

that are formed by the explosive.

1. Programme Reference

• Master Construction Programme is referred.

3. List of Construction Machinery / Equipment Used

NO DESCRIPTION CAPACITY/SPEC QUANTITY

UNITS

1 Hydraulic Excavator EX 300 3

EX 200 (Long Arm) 2

EX 100 (Long Arm) 2

2 Licensed Truck 10 Wheelers 30

3 Back pusher New Holland 1

4 Hydraulic Crawler Drill Tamrock / Furukawa 1

5 Hydraulic Breaker Atlas Copco 20 tons to 40 tons 3

6 Water Pump Electric Submersible Pump 6”to 12” 3

7 Air Compressor Airman 1

4. Manpower

5. Construction / Operation Procedure

i ) Excavation Works

• The commencement of actual earthworks will be carried out after obtaining

approved earthwork permit from DBKL and PTG.

No. Description No. Remarks

1 Site Agent 1

2 Site Supervisor 1

3 Land Surveyor 1

4 Blasting Supervisor 1

5 Shot Firer 1

6 Site Foreman 1

7 Machine Operator 9

8 Lorry Driver 30

9 General Worker 10

• Joint survey for original ground level for excavation areas will be jointly carried

out and verified by consultant engineer before commencement of actual excavation

works.

• Upon earthwork machineries and licensed lorry mobilized to project site, the first

layer of excavation works will commence at the completed perimeter contiguous bore

pile installation area once the request to excavate first layer of 4.5 m without cement sand

(mortar) column between contiguous bore pile (CBP) approved by consultant engineer

and the installation of first stage of temporary steel strutting works will commence once

the first layer reached 4.5 m. After completion of first layer temporary steel strutting, the

second layer of excavation works will continue at the completed first stage temporary

steel strutting area. The excavation works and temporary steel strutting works will repeat

until reaching the final stage of temporary steel strutting installation and formation level.

• The excavated material will be transported by licensed lorry and dispose of

dumping ground as stated in the attached plan showing the route from CSTP Batu to

Gamuda project site dumping ground located at Kota Kemuning, Selangor. Before

leaving the project site, all the licensed trucks will go through wash trough, tyre washing

and properly be covered with plastic sheet to avoid spillage problem.

• During execution of underground earthworks operation, temporary access road

should be properly constructed in a gentle slope to enable earth transportation to carry out

without disruption. The excavation area and access road always are free from standing

water especially rain water and ground water. Temporary earth drains are adjusted to suit

ground water condition to flow the water to pumping sump. The permanent water pump

is full-time station at the pumping sump to ensure the underground working platform in a

dry condition at all time.

• The final two layers of excavated materials will be transferred from lower level to

higher level by long arm excavators due to steep gradient of access road condition.

• Once the excavation area reached final or formation level, joint inspection and

survey will be carried out together with consultant engineer, and the completed formation

area will be handed over to third-party contractor for subsequence micro pile and

structure works.

ii) Rock Blasting Works

• In case of rock formation encountered during excavation, control blasting work has

been carried out to loosen rock before excavation and disposal of rock to the approved

dumping ground.

• Demarcation of rock and joint survey for existing ground level for rock formation

areas will be jointly carried out and verified by consultant engineer before the

commencement of actual rock blasting works.

• Blasting permit must be approved by relevant authorities before the

commencement of blasting works.

• Upon completion of drilling works by pneumatic crawler drill machine at the

blasting site, the explosive charging and stemming of drill holes will be carried out. The

low explosive used for the blasting work is Ammonium Nitrate Fuel Oil (ANFO). ANFO

is the most widely used explosive in blasting works. It is considered a blasting agent and

has to be initiated by a high explosive or primer such as Dynamite or Emulate. Prior to

the explosive charging, the site mixing of prilled Ammonium Nitrate and diesel at a ratio

of 94: 6 will be carried out to produce Ammonium Nitrate Fuel Oil (ANFO). Ammonium

Nitrate is not water-resistant. If the drill holes are wet, the drill holes are either flushed

out by an air compressor or the ANFO should be enclosed in sealed plastic bags to avoid

the ANFO dissolving by water. After priming the explosive cartridge with the detonators,

the primed explosive cartridge attached together with the ANFO will be placed into the

drill hole at required depth, the balance of the hole should be filled with stemming

materials, which may consist of suitable insert material such as drill fine or chipping,

sand, dust and etc, stemming may be placed between charges at predetermined intervals.

When charges are separated with stemming, a separate primer should be provided for

each charge.

• After the completion of stemming and connection of shot holes, the firing circuits

will be tested before the final connecting to the source of electric current to eliminate

misfire and open break. When the explosive charges in two or more rows of drill holes

parallels to a blasting face are fired at the same time, it is desirable to fire the charges in

the drill holes nearest to the blasting face a short time ahead of those in the second row.

This procedure will reduce the burden on the drill holes in the second row and allow the

second row to break the rock more effectively. If there are more than two rows of drill

holes. The detonations may progress in the order 1, 2, 3, 4 etc. For the shortest delay

intervals the cap are called millisecond delay caps and are designated as MS - 25, MS -

50, MS - 200 etc. The number indicates the period of delay in thousandths of a second.

Blasting will commence after the completion of firing circuits testing and final

connection. Upon completion of each blast, excavation and disposal of blasted rock to

dumping ground by licensed lorry will be carried out.

• Before general blasting operations commence on site, the trial blasting will be

carried out to demonstrate the satisfaction and blasting procedures are being followed.

• The oversize blasted rock will be hacked to a smaller size by hydraulic excavator

mounted with hydraulic breaker before being transferred to a higher level by long arm

excavator.

• Rock area not allowed for blasting due to certain constrain shall be hacked by

hydraulic excavator breaker.

• The permanent water pump is a full-time station at the pumping sump to ensure the

underground working platform in a dry condition at all time.

• Upon completion of excavation work and reaching final formation level, all the

equipment and machine will be demobilized and lifted up by 50 tons crane.

6. Health & Safety

i ) Excavation Works

• All workers are equipped with appropriate Personal Protection Equipment (P.P.E).

• All workers shall attend a safety induction course

• Traffic warden shall be provided to guide the traffic whenever the heavy vehicle

enters and exits from the site.

• All machinery shall be inspected prior to work commencement to ensure that they

are in good working conditions.

• All machinery shall be maintained regularly.

• To place adequate warning signs and to barricade dangerous work zone.

• All licensed lorry leaving the work site shall be cleaned at the washing facility to

avoid dirtying the public road.

• All personnel shall be familiarised with the Emergency Respond Plan.

ii) Rock Blasting Works

• An accident involving the use of explosive is normally prevented by the correct

use and strict compliance with the manufacturer’s instructions. Over and above correct

planning are appreciated of the blast site must be conducted prior to the use of explosives.

As we are aware that help in construction if employed correctly or can result in

destruction if wrongly employed.

• In general, all explosives are dangerous and must be handled by experienced and

trained personnel. All personnel involved in the use of explosives are expected to follow

all rules and regulations laid down by the manufacturers.

• For the prevention of ground vibrations, fly rock and air blast at the blasting site,

the following safety precautions will be taken.

(i) Employment of millisecond delay electrical delay detonators with a minimum

delay of 25-millisecond delay between each shot hole.

(ii) Usage of minimum charge / delay during blasting.

(iii) Deck loading of explosive on bore holes to reduce the explosive charge action.

(iv) Accurate positioning of boreholes so that the optimum amount of explosives

will be utilized.

(v) Slightly undercharging the first row of shot holes on the free face of the trench.

(vi) Usage of 76 mm series drill steel for drilling purposes.

(vii) Usage of steel plate, earth of overburden etc, to cover the top of the free face of

the rock to be blasted.

The following additional safety requirements will also be implemented to ensure

that the blasting operation is conducted safety.

(i) Evacuation of all personnel in the immediate vicinity.

(ii) Posting of signboards and red flags to indicate blasting works.

(iii) Usage of siren to indicate the commencement and completion of each blast.

(iv) Informing the surrounding personnel of our intentions, blasting times and dates.

(v) Observation of all explosives regulations which is employing the explosives at

project site.

7. Appendix

• Master Construction Programme

• Site layout plan

• Drawing shown route from project site to dumping site

Standard Operating Procedure (SOP) For Rock Blasting –

Batu Sewerage Treatment Plant Project at Batu, Jinjang

Kepong.

1. Purpose

The purpose of this procedure is to identify and explain the tasks and considerations

necessary to perform safe, legal and successful blasting operations at Batu Sewerage

Treatment Plant Project, Jinjang, Kepong

2. Scope

This procedure applies to all personnel involved in the blasting operations of the

project.

3. Responsibilities

Skill Status Sdn Bhd is appointed as an earthwork sub-contractor and responsible to

carry out proper and successful rock blasting operations for the project.

4. Procedure

• Pre-study on the rock blasting site and surrounding area will be carried out to

determine the design of drill holes diameter and depth, spacing, burden, stemming and

direction of blasting while determining the number of drill holes to be drilled and blasted.

The blasting supervisor should develop a blasting plan prior to conducting drilling and

blasting operation. The blast plan is a blasting design which graphically depicts the blast

holes layout, load factors and timing sequence of a blasting operation. The blast plan

should include the information such as date, shot time, location, purpose of shot, number

of holes, hole diameter, average depth of hole, number of rows, spacing, burden, design

powder factor, type of powder, initiation method, total caps, depth per hole, powder per

hole and estimate volume of rock to be shot. A trial blasting will be carried out at the

beginning stage to reconfirm the suitability of the blast design.

• The location and distance of the blasting area towards the structure such as CBP

wall and surrounding building have to take into consideration of fly rock, noise and

ground vibration control. Prior to the initiation of blast, the blasting area will be covered

up with blasting mats such as overburden, sand beg, wire mesh or steel plate to avoid fly

rock damaging the CBP wall and surrounding structure or building..

• The name and contact number of nearest hospital, fire department, police station

and key personnel involved in the blasting works such as project manager, safety officer,

blasting supervisor and shot firer need to be written down in the project Emergency

Response Plan (ERP) for an incident or emergency case action plan.

The blasting supervisor is required to notify all relevant personnel or party involved

in the project regarding the “notice of intent to conduct blasting operation” 24 hours in

advance and the notice should include the following information;

(i) Date of planned blasting,

(ii) Location of blasting operations,

(iii) Estimate shot time,

(iv) Affected buildings and areas.

(v) Any relevant restrictions (access or others).

• The blasting supervisor needs to communicate closely with the project manager

and safety officer in carrying out each blasting work. Before carrying out each blasting

works, the blasting supervisor will carry out blast site checking according to blasting

checklist for all the drilled holes to avoid deviation and to clear any blockage before

charging the drilled holes with a detonator, explosive and stemming works.After

completion of charging works, the blasting supervisor has to ensure all the surface

nonelectric initiation systems are correctly and properly installed. All the blasting details

such as number and depth of drilled holes and amount of explosive used will be recorded

in the blast diary for each blast.

• The delivery of explosive to the project blasting site for each blast will be

transported from Tenaga Kimia explosive magazine located in Batu Arang, Selangor and

the delivery of explosives will be accompanied by a police officer for each blast, and the

balance of explosive will be returned to Tenaga Kimia explosives magazine immediately.

The used quantity of explosives shall be properly recorded for each blast.

• All entrance to the project site will be temporarily blocked and closed to avoid

unauthorized person entering the blasting site before blasting operation.

• The blasting supervisor will signal by showing his green flag and call upon the

attention of shot firer through. During this time, the blasting supervisor should have

connected all the circuits to ensure that blasting can be initiated.

• The shot firer will then signal their green flags in response to their blasting

supervisor.

• The siren will be switched on and then flag signal will be shown to shot firer for

simultaneous ignition.

• During this time, there will be at least two minutes given to allow the workers to

clear the blasting site.

• The blasting supervisor at this point must ensure that all site personnel has reached

safe shelter and no outsiders can enter the blasting area. The blasting supervisor should

then inform the shot firer to initiate the blasting operation.

• Actual blasting of rock will take a matter of few seconds. Shot firer will make an

effort to count the number of drilled holes blasted. The shot firer will then stop the siren

after ensuring that the blasting is over. At least 30 minutes after the blasting, the shot firer

will return to blasting site to check for any misfire, hanging unfallen loosen rock pieces

occurred.

• After the blasting supervisor is satisfied with the blasting, he will then signal to the

siren operator to switch off the siren to indicate the completion of the blast. All road

block shall then be removed.

• Blasting supervisor has to ensure the following items are checked before

commencing the blasting operation;

(i) Two sets of red and green flags.

(ii) Siren to be in good working condition.

(iii) Sufficient safety helmet and safety shoes for site personnel.

(iv) Instruction is given to the safety officer to avoid unauthorized personnel

entering the blasting site.

(v) Blasting shall be carried out at a suitable time (before 4 pm)

(vi) Walkie talkie or hand phone in good working condition.

(vii) Shot firer needs to ensure all the blasting accessories are in proper working

order.

(viii) Blasting supervisor should do the final checking of the drill hole to ensure

correct connecting series and properly charged.

(ix) Blasting supervisor has to ensure no hanging and loosen rocks at the blasting

site.

5. Definition

• Blast Area

The area is close to a blast, which may be influenced by flyrock.

• Blast Holes.

A hole drilled in rock for the placement of explosives.

• Blasting Agent

An explosive that meets prescribed criteria for insensitivity to initiation.

• Blasting Cap

A device used to initiate explosives.

• Blasting Circuit

The electric circuit used to fire one or more electric detonators.

• Blasting Diary

Diary is kept at work site containing all information about each blast.

• Blasting Mat

A covering such as steel plate, wire mesh or sand bags placed over a blast to hold

down fly rock.

• Burden

The distance in feet from an explosive charge, in the direction of relief, to the

nearest free or open space.

• Detonator

Devise containing a detonating charge that is used to initiate an explosive.

• Fly Rock

Rock material is forcefully displaced and sent hurling through the air by an

explosive detonation.

• Magazine

An approved facility for the storage of explosives

• Misfire

The unsuccessful or incomplete detonation of an explosive charge.

•Shot

Common technical term for a planned explosive detonation.

• Shot Firer

A Person who actually fires the blast.

• Shot Time

The time when an explosive detonation is scheduled to take place.

• Stemming

An insert material used to confine or separate explosives in a borehole.

• Spacing

The distance between blast holes in a row.