METHOD STATEMENT
FOR HYDRO-VACUUM EXCAVATION (HYDRO-VAC)
TABLE OF CONTENTS
1.
PURPOSE----------------------------------------------------------------------------------------------------------------------------------------------------------------- 4
2. SCOPE OF WORK ----------------------------------------------------------------------------------------------------------------- 4
2 .1. SEQUENCING OF THE ACTIVITIES -----------------------------------------------------------------------------------------------------------4
3.
TERMS, DEFINITIONS AND ABBREVIATIONS ------------------------------------------------------------------------------------ 4
4.
REFERENCE DOCUM ENTS---------------------------------------------------------------------------------------------------------------------------- 5
5.
DUTIES AND RESPONSIBlLITIES -------------------------------------------------------------------------------------------------------------------- 6
6.
TOOLS & EQUIPMENT -----------------------------------------------------------------------------------------------------------------------------8
7.
HYDRO-VAC OPERATIONAL METHODOLOGY -------------------------------------------------------------------------------------------8
7.1. CORRECT OPERATl ON OF WATER JET ----------------------------------------------------------------------------------------------------------- 9
7.2. VACUUM HOSE AND ATTACHM ENTS --------------------------------------------------------------------------------------------------------- 10
7.3. EMPTYING THE SPOILS TANK --------------------------------------------------------------------------------------------------------------------- 11
7.4. CLEARING BLOCKAGES FROM THE VACUUM PlPE ---------------------------------------------------------------------------------------- 11
8.
QUALITY CONTROL REQUIREME NTS ----------------------------------------------------------------------------------------------------- 12
9.
SIGNIFICANT HEALTH, SAFETY AND ENVIRONMENT (HSE) HAZARDS --------------------------------------------------------- 13
10. HSE REQUIREME NTS---------------------------------------------------------------------------------------------------------------------------- 13
11. ATTACHM ENTS ------------------------------------------------------------------------------------------------------------------------- 14
1. PURPOSE
The purpose of this procedure is to provide guidelines to carry out all the activities in a systematic way
pertaining to the execution of Hydro-Vacuum Excavation (Hydro-Vac) in order to comply with the Project
Specifications. The Hydrovac will be executed by the specialized company who are authorized by ROO with
the support of the SUBCONTRACTOR Construction Organization.
2. SCOPE OF WORK
Hydro-Vac activities are needed to uncover all the existing undergrounds in the DS2 prior to proceed to
excavations. Hydrovac is a non-destructive activity for the existing pipes, cables, foundations, etc. and will not
damage any underground utilities during the water jetting and the vacuum of soil.
Hydrovac Methodology will be used to perform partially or totally the perimeters and/or the diagonals of the
excavations and/or to expose partially or totally the underground facilities in case them should be detected
during the underground scanning.
Hydro-Vac utilizes a high-pressure water jet of 3000 psi and 15 L / min, directed at the ground, to mix water
with in-situ soils and create a slurry. The slurry is then removed through a lightweight suction pipe connected
to the Hydro-Vac unit and contained in the storage tank.
This method statement outlines the prerequisites for Hydro-Vac operation and provides a summary
methodology for field operations..
.
2.1. SEQUENCING OF THE ACTIVITIES
Sequencing of the activities by using hydrovac methodology will anticipate the excavations and will follow with
the construction schedule level 4 and 3 week look ahead for civil activities.
3. TERMS, DEFINITIONS AND ABBREVIATIONS
PROJECT
DS2
COMPANY
ROO
CONTRACTOR
WOOD
SUBCONTRACTOR
TSI
CONTRACTOR/COMPANY to satisfy ITP obligations pursuant to the
Contract undertaken with the COMPANY.
ITP
Inspection and Test Plan: Specific Section(s) of QCP that identify and
define Inspection sequences. It is prepared in accordance with the
corresponding ITP(s) of QCR and with all the applicable contractual,
engineering and Supplier's requirements. The ITP(s) provide
references
to
applicable
procedures,
acceptance
criteria,
documentation, quality records and inspection attendance to be
performed, in chronological order, from initial inspection, throughout
final inspections and mechanical completion. The ITP(s) provide
reference for the Inspection Forms to be used.
QCP
Project Quality Control Plan: Project document to manage inspection
activities, derived from CONTRACTORQCR and integrated with all
specific contract/COMPANYobligations.
QCR
Quality Control Requirements: CONTRACTOR standard documents
containing minimum requirements for Quality Control activities at Site
regardless of specific contract/client obligations, the QCR include ITP
and inspection FORMs to be customized and improved with
contractual obligations when QCR is transformedinto Project QCP.
Inspection Form
One or more Specific Forms, identified for each QC codes and to be
compiled during the Inspection, once signed by the involved parties it
becomes Certificate. It includes also the traceability versus the
inspected Item.
IN
Inspection
Notification: Written communication issued by the
Construction organization to allow the involved parties to carry out
their own inspection or attend, as planned in the applicable ITP.
QA
Quality Assurance: Part of quality management focused on providing
confidence that quality requirements will be fulfilled
QC
Quality Control), Process to verify that the product complies with
requirements. It is ensured by an organization not directly involved in
Product realization.
4. DUTIES AND RESPONSIBILITIES
5.1 PROJECT MANGER
• Overall responsible for the implementation of this method statement.
• Ensure that all required submittal is made in timely manner
• Responsible for ensuring that the work is performed in accordance with the specification and within
the time and cost constraints.
• Coordination with the CONTRACTOR,COMPANY, Other Subcontractors and Civil Personnel for
the safety and quality during the execution of the project.
• Co-ordinate with the CONTRACTOR'S Coordinator for obtaining the necessary resources for the
project and deployment as required.
5.2 CONSTRUCTION MANAGER
• CM manages the construction and erection work, ensuring that the time, cost, quality, safety and
environmental protection requirements of the construction activities are met.
• Checking that the procedures defined for site activities are applied.
• Ensuring the achievement of the mechanical completion objective.
• Construction Manager shall ensure that every work activity is executed in a safe and controlled
manner and ensuring that:
•
All JSA"s mitigation measures shall be implemented before work commences.
•
The Foremen and other related Supervisory staffs are familiar with the works and are fully
aware and trained with safety requirements for this activity. Planning,directs and monitor the
activitiesof the project team.
•
Required resources (personnel, equipment and material) are on site and are in the right
quantity and condition.
•
Adequate provision of fire and medical equipment.
•
Fire-fighting equipment is located in the correct position.
5.3 PROJECT ENGINEER
• Ensure that the activities are carried out according to the Specifications, drawing and approved
Method statement.
• Ensure that all required submittal is made in a timely manner.
• Arrange all materials and tools required for installation as per agreed project schedule.
• Provide all necessary information and distribute the responsibilities to his unit installation team.
• Monitoring that all in process test are carried out and obtained approval from Company's
Representative.
• Monitoring and ensuring that the work is performed in accordance within the time and cost
constraints.
5.4 SITE SUPERVISOR
• Site supervisor shall be responsible for proper execution of work as per specification and drawings.
• He shall also be responsible for raising the inspection notification to QC at each stage as per
QCP/ITP requirements.
5.5 FOREMAN
• Carrying out the work and the proper distribution of all the available resources in coordination with
the Site Supervisor & Site Engineer on daily basis
• Continuous coordination and following Site Engineer/Supervisor's instructions to meet quality
requirement during the job execution.
• Incorporate all the QC and Safety requirements as requested by the Company's representative.
• Report to Site Engineer the accomplishments and problem encountered on daily basis.
5.6 QA/QC MANAGER
• QA/QC Manager is responsible for the implementation of all required Quality Control activities such
as test and inspection for this job and keeps record of its necessary documentation.
5.7 QC INSPECTOR
• The QC Inspector shall be responsible for conducting surveillance and inspection duties for work
defined here in and efficient recording and reporting of the results as required.
• The QC Inspector shall functionally report to the QA/QC Manager and shall review all relevant
documentation, material certificates and non-conformances.
• The QC Inspector shall raise all Requests for Inspection (RFI) Forms from the Construction Department
• The QC Inspector shall carry out Planned Inspections, Surveillance Inspections and release hold
points by signing various QC Inspector records as proof of Inspection conforming to specifications.
5.8 SAFETY MANAGER, SPV, OFFICER
• The Safety Manager/Supervisor/Officer shall review all the relevant documentation prior to the start
the activities and the compliance with Safe Work Plan and Permit to Work.
• Provide appropriate Safety and Health, accident prevention and investigation
• Ensure that the Provisions of the Project HSE Plan are applied on the project by regular
monitoring and reporting.
• Assist with the implementation of Job Safety Analysis and inspect job site activities during
particularly difficult or hazardous work situations.
• Coordinate with Project Manager
5.9 OPERATORS QUALIFICATION
• All operators of Hydro-Vac equipment are to be in possession of an ADP training record. This record
will act as proof of competency and training in the use of Hydro-Vac units.
5. TOOLS & EQUIPMENT
•
Hydro-Vac excavation unit (<95db within 5 m of machine)
•
Various hand operated tools
•
Vacuum & water pressure hose
•
Mains water supply hose
•
Barriers / signs / cones / barrier tape
•
Drainage rods
•
Environmental spill kits
6. HYDRO-VAC OPERATIONAL METHODOLOGY
Hydro-Vac excavation utilizes a high pressure water jet of 3000 psi and 15 L / min, directed at the ground to
mix water with in-situ soils and create a slurry. It should be noted that during the removal of blanketing soil,
the pressure of water will be reduced from 3000psi as appropriate so not to potentially damage any
underground utilities. The slurry is then removed through a lightweight suction pipe connected to the Hydro-
Vac unit. Disposal of the recovered material is done safely, by draining the water from the vessel through
a 4" gate valve and then tipping the spoil through the fully opening rear door.
For safe operation of the vacuum system, the lance should be held in two hands below waist level and
gently directed toward the loosened material.. An equally balanced feed of material and air should flow into
the end of the vacuum pipe, ensuring that objects too large for clear passage are not allowed to enter. In
case the pipe become blocked, the vacuum release valve must be opened, and all systems shut down. If
the blockage is easily cleared by gently tapping the end of the pipe, then the system can be restarted. If the
blockage remains, then the vacuum pipe should be detached from the tank and reversed so the material
can flow in the opposite direction.
Should a build-up of sticky soil reduce performance of the pipe, then water can be induced at low pressure
with the system running at idle speed. Operator hands must not enter the vacuum pipe at any time during
these maintenance processes.
6.1. CORRECT OPERATION OF WATER JET
The water jet is best suited for use in cohesive soils, although non-cohesive soils can also be
accommodated
. When directed at the target area, the water reduces the ground structure into a slurry which
can easily be recovered by vacuum extraction. The correct and safe operation for this system is outlined
below:
•
Prior to operating the water jet, the correct PPE must be worn.
•
Secure the working area using the proper barricades and signs.
•
Check the water tank has sufficient clean water for operation and fill from a clean supply as required. Water
tank is filled via removal of the lid and utilization of a hose from the clean water supply. Once the water tank
is full (water level will reach the top) the clean water hose is removed.
•
Check that the filter is not blocked. Unscrew, remove and rinse clean if necessary.
•
Uncoil the pressure hose to allow sufficient length of untangled hose to reach the target location, ensuring
the hose is laid out safely and will not create a trip hazard.
•
Before connecting the hose to the water lance, check that the connector is clean, and the 0 -ring is securely
in place inside the female connector. Only then connect the lance to the hose.
•
With the engine running, turn the tap to allow water to flow to the pump, then engage the water pump via
the on / off toggle switch, increasing the engine revs to a maximum of 2000 rpm.
•
Take the water lance in hand and direct the nozzle through a shield toward the target area. Squeeze the
trigger (dead man-handle) and keep the tip approximately 100 mm from the ground. For best results rotate
the lance in a circular motion within a 150 mm to 200 mm circumference. After maintaining this process for
approximately 15 to 20 seconds, release the trigger, remove the lance from the excavation and inspect the
target area.
•
It is recommended that at this stage the vacuum should be used to recover the fragmented material and
slurry. Study safe use of vacuum first.
•
After completion of the excavation, turn the tap off. The pump should be disengaged at the switch, the
engine switched off and the pressure released from the trigger by directing the nozzle into the ground and
squeezing the trigger. The connector can then be released, and the hose recovered to ensure that all
components are clean before storage.
•
The water jet can be used for cleaning the machine and vacuum hoses. It is recommended that no more
that 25% of the power is used; this will reduce the impact of splatter and misguided jetting.
•
If at any stage during operation performance is reduced or water flow stops, check the water level in the
tank is not below the cut off float switch or that there is no obstruction inside the inline filter.
6.2. VACUUM HOSE AND ATTACHMENTS
The vacuum recovery system built into the unit is designed to remove solids and liquids from sensitive
locations, and as a complement to pneumatic or hydraulic excavators. Start the operations by following the
steps:
•
Prior to operating the vacuum hose, the correct PPE must be worn.
•
Before start-up check that the filters are clean and installed correctly. Then lay out sufficient hose between
the excavator and the target area in a manner that does not create a trip hazard.
•
Connect one end of the vacuum pipe to the inlet port on the spoils tank and ensure the connection is
secure.
•
Connect the other end of the vacuum pipe securely to the reduction tool.
•
Perform checks to ensure that the integrity of the plant is correct and safe to use.
•
Make sure that there are no obstructions or loose material around the mouth of the reduction tool.
•
Start the engine and engage the drive belt to the blower if required to do so.
•
Increase the engine speed to 25%, then in stages to 50%, 75% and finally 100%.
•
For optimum performance of the vacuum system it is important that the reduction tool is not thrust into the
loosened material but engaged slowly, allowing an even amount of spoil and air to flow into the pipe. If too
much spoil enters the pipe it may cause the material to stall and cause a blockage. After all loose material
has been recovered the suction hose must be withdrawn from the excavation before commencing water or
air jetting.
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Issue Date: 31-July-2019
•
It is important to focus on material size entering the pipe as oversized material (more than 60% diameter of
the pipe) may cause a blockage. See Section 7.4 if this occurs.
•
If at any stage of operation, the vacuum pipe becomes blocked, the vacuum release lever must be
quickly opened. Under no circumstances should a limb or hand enter the pipe.
•
After completing the excavation, the vacuum hose and attachment should be cleaned with water or
compressed air before being returned to storage.
•
The spoils tank must be emptied before taking the unit onto a public highway, see Section 7.3.
6.3. EMPTYING THE SPOILS TANK
All arisings are stored in the spoils tank. When emptying is required, the following procedures shall be
followed:
•
Vacuum excavator to be maneuvered to a suitable location as directed by CONTRACTOR/COMPANY.
Such locations could be waste land, a spoil heap, a bunded area or a skip. Maneuvering shall be done with
the help of an assistant.
•
Once the Hydro-Vac is at the tipping location, the lower sluice gate should be opened, and the water
drained from the spoil.
•
After all the water has been drained the back door should be opened; either via the hydraulic or manual
system, depending on machine type.
•
Once the initial spoil has emptied from the rear door the tank system can be tipped slowly, in increments of
approximately 200 mm, ensuring that the spoil is decanted at a steady pace and not all at once.
•
After the tank has completely emptied it can be cleaned with the hydro jet on a lower power setting before
the above steps are reversedand the tank lowered prior to shutting the rear door.
6.4. CLEARING BLOCKAGES FROM THE VACUUM PIPE
When the vacuum pipe becomes blocked, the following procedure shall be followed:
•
The vacuum release valve located at the rear of the spoils tank must be opened to release pressure.
•
The engine must be switched off and the key removed. The key is to be retained by the person clearing the
blockage.
•
The vacuum pipe can then be removed from the spoils tank cam lock connector. Any other inline connectors
can also be disconnected. A visual check can then be made at each connection to find where the blockage
has occurred.
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Issue Date: 31-July-2019
•
The pipe with the blocked area should be tapped lightly onto the ground to loosen the obstruction, and any
material removed.
•
The system can be reassembled and run to test. If the blockage has been cleared, then work can
recommence.
•
If the blockage remains, then steps 1 to 3 must be repeated.
•
Take the vacuum pipe and reverse the direction of the pipe so opposite ends are at the inlet port.
•
Start the system and run up to half speed, manually offer the end of the pipe to the inlet port and listen for
the blockage being pulled through the pipe, if this is successful the system should be shutdown,
reassembled and then restarted and work recommenced.
•
If the blockage remains, steps 1 to 3 should again be followed.
•
The disconnected pipe shall be flushed with water, or drainage rods shall be used to loosen the obstruction.
Once the system has been cleared it can be reassembled and work can resume.
•
If the performance of the system is reduced due to build-up of mud, then the engine must be reduced to idle
speed, water from the lance induced into the working end of the pipe and allowed to run clear for
approximately 5 minutes. Further clearing may be required, and this procedure may be repeated.
•
Strictly, at no stage during operation or maintenance should an operator reach inside any part of the
vacuum port or pipe to clear blockages. The vacuum is powerful enough to trap hands and arms.
•
At no time during any of these procedures should untrained personnel be involved. In addition, ensure that
full PPE is worn at all times.
•
If an operator is unclear about what to do they should contact a competent person for guidance.
7. QUALITY CONTROL REQUIREMENTS
•
All necessary inspections shall be carried out as per ITP approved by CONTRACTOR / COMPANY.
•
Prior to start any inspection activity, the Quality Inspector shall raise the RFI sending a written
Inspection Notification to CONTRACTOR 24 Hrs. in advance. Related request for inspection (RFI) must
be approved by CONTRACTOR/ COMPANY in order to proceed for the inspection.
•
RFI shall be issued during and or after the Hydrovac activities to ascertain the status of the
underground uncovered or under uncovering g, to report any non-conformity of them found during the
activities, and any possible damage could occur.
•
Quality shall be maintained by ensuring the systematic implementation of this procedure and ensure that
necessary quality records are generated as appended formats.
•
All records relevant to the above procedure shall be retained by the Quality Control department at site office,
for the duration of the project, before being handed over to CONTRACTOR in accordance with the
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Issue Date: 31-July-2019
requirements of the contract documents. Copies of all records shall be made and transferred to the
CONTRACTOR Office where they shall be retained for the guarantee period of the contract.
8.
SIGNIFICANT HEALTH, SAFETY AND ENVIRONMENT (HSE) HAZARDS
The following are common HSE hazards encountered during Hydro-Vac operations. The list is not exhaustive
and should be reviewed on a site by site basis.
•
Overhead electricity lines
•
All buried services (e.g. low or high voltage electricity, oil, gas and water)
•
Manual handling injuries, strains / sprains - all manual handling tasks should be reduced to a minimum and
performed in accordance with Project Specifications
9.
•
Slips, trips and falls
•
Lifting the vacuum pipe from vehicle and connecting to the Hydro-Vac system
•
Operating the vacuum lance
•
Operating hydro / pneumatic digging tools
•
Vacuum excavation operations
•
Other contractors within the work area
HSE REQUIREMENTS
•
SUBCONTRACTOR safety supervisor shall carry out the site inspections to ensure that safety requirements
are followed prior to start work.
•
SUBCONTRACTOR Safety manager shall review safety action plan and ensure the implementation of JSA.
•
Ensure that the work permit is valid and present on workplace.
•
All equipment and tools shall be inspected, color coded and certified by SUBCONTRACTOR, according
to CONTRACTOR inspection program.
•
All personnel shall undertake site induction (where required) and participate in the toolbox talk (mandatory)
prior to any work commencing.
•
All operators are to be in possession of an ADP training record. This record will act as proof of competency
and training in the use of Hydro-Vac units.
•
Task specific PPE shall be provided and worn by personnel.
•
Ensure that proper barricading system is installed where required.
•
Ensure all manifold fittings are as per required rating and suitable for work.
•
Provide sufficient safety sign boards nearby working area during equipment installation activity.
•
Ensure that only authorized personnel are within the work area.
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•
Access and egress restrictions shall be determined on a site specific basis, with any restriction requirements
recorded as part of the site induction and toolbox talks.
•
Regular housekeeping shall be maintained.
•
Non contaminated waste materials shall be disposed in a location agreed with CONTRACTOR/COMPANY.
Contaminated spoil shall be disposed into CONTRACTOR/COMPANY provided skips or at a designated
location. Waste shall not be disposed of via drains, waterways or tributary.
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Issue Date: 31-July-2019