abridged construction execution plan · managed on site through safe work method statements, risk...

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Long Beach Sewer Rising Main Horizontal Directional Drilling (HDD) Project

ABRIDGED CONSTRUCTION EXECUTION PLAN

Dunstans 12 Newman Street

Wangaratta VIC 3677

Phone: 0357 221 515 ABN: 63 081 478 828

www.dunstans.com.au

Long Beach Sewer Rising Main Horizontal Directional Drilling (HDD) Project Abridged Construction Execution Plan (CEP)

DUN-C0118-PLN-007 | Rev 1 Page i

TABLE OF CONTENTS 1 INTRODUCTION ........................................................................................................................... 1

1.1 Scope of Work 11.2 Project Locations 21.3 Project Objectives 31.4 Abbreviations 3

2 HEALTH, SAFETY, ENVIRONMENTAL AND QUALITY (HSEQ) MANAGEMENT ................................. 52.1 Risk Management 52.2 Safety Management 52.3 Environmental Management 52.4 Quality Management 52.5 Emergency Management 52.6 Work Procedures, SWMS & ITP’s 5

3 CONSTRUCTION METHODOLOGY ................................................................................................ 63.1 Working Hours 63.2 Site Preparation Works 6

3.2.1 Site Condition Surveys 63.2.2 Site Establishment and Survey 6

3.3 Mobilisation 73.4 Installation of 30 inch Casing 73.5 Equipment Set Up for Drilling 83.6 Drilling 10

3.6.1 Pilot Hole Drilling 103.6.2 Reaming Assembly 113.6.3 Cleaning Pass 11

3.7 Drilling Fluids 113.7.1 Drill Fluid Makeup and Mixing 113.7.2 Drill Cuttings Disposal 12

3.8 Pipe String Fabrication 133.9 Pipe Insertion 143.10 Pipeline Testing 153.11 Tie-ins 153.12 Removal of Exposed Sections of Existing Sewer Main 153.13 Site Reinstatement 16


DUN-C0118-PLN-007 | Rev 1 Page 1

1 INTRODUCTION

Eurobodalla Shire Council (ESC) is proposing to replace the existing sewer main running from Surfside to Long Beach NSW and address exposure of the existing sewer main from ongoing erosion.

Dunstans have been contracted to install a new 300mm internal diameter sewer rising main further inland using horizontal directional drilling (HDD) technology. The works also involve the tie-in to the existing two pipelines at either end of the HDD crossing and removal of sections of the existing pipeline on the beach as required.

Horizontal directional drilling (HDD) is a method of construction where a tunnel is drilled through the ground to enable the installation of pipelines, conduits or cables without digging trenches. HDD is a minimal impact installation method and is commonly used where ground disturbance is not acceptable e.g. for crossing roads, rivers, wetlands, shore crossings.

The HDD method is being used for this project to install the new sewer rising main under the Cullendulla Creek Nature Reserve and Cullendulla Creek without disturbance to the Nature Reserve or Creek.

This document provides a brief description of the management framework to be implemented during the planning and execution of the project and the proposed construction methodology/procedures.

1.1 Scope of Work

Dunstans Scope of Works includes:

• Establishment of the work sites for the HDD and pipe fabrication works.

• Mobilisation of plant and equipment.

• Installation of steel casing on the exit side of the bore using an air hammer to prevent frac-out (inadvertent loss of drilling fluids).

• Drilling of the HDD bore from Myamba Parade, Surfside to the eastern side of Cullendulla Creek, Long Beach (total crossing length of 1,150m).

• Fabrication, stringing and testing of the 450mm HDPE product pipe string (3 x 400m long strings).

• Installation of pipe into the bore.

• Tie-in to the existing sewer pipeline and capping of the existing pipe.

• Disconnection, removal and disposal of exposed sections of the existing sewer line and plugging and burial of exposed ends of remaining sewer line.

• Demobilisation of plant and equipment.

• Reinstatement of work areas.



1.2 Project Locations

The HDD works shall be carried out at two locations:

• HDD Entry Site at the existing council depot area at the end of Myamba Parade, Surfside at the entrance to Cullendulla Nature Reserve.

• The HDD Exit Side and pipe stringing and welding area at the Council owned land and public reserve adjacent to the Long Beach Sewerage Pump Station in Long Beach, on the eastern side of Cullendulla Creek with access off Courtenay Crescent Long Beach.

Figure 1 Locality Map – HDD Works

Figure 2 HDD Works Location Plan



Figure 3 Existing Pipeline Location Plan

1.3 Project Objectives

Dunstans objectives for the project include:

• Ensuring that any site works are undertaken in a manner that:

• provides a safe work environment.

• minimises the impact on the environment.

• minimises the impact on the local community.

• To provide a quality service that conforms to the project specification and Contract requirements.

• Compliance with relevant legislation, Eurobodalla Shire Council requirements and Dunstans management systems.

• To complete the project on time and within budget.

1.4 Abbreviations

BHA Bore Hole Assembly

CEMP Construction Environmental Management Plan

EPA Environmental Protection Authority

ESC Eurobodalla Shire Council

HDD Horizontal Directional Drilling

HDPE High Density Polyethylene

HSEQ Health, Safety, Environment and Quality



ITP Inspection and Test Plan

QMP Quality Management Plan

SMP Safety Management Plan

SMWS Safe Work Method Statement



2 HEALTH, SAFETY, ENVIRONMENTAL AND QUALITY (HSEQ) MANAGEMENT

2.1 Risk Management

A Risk Assessment was undertaken in the planning phase to identify the major risks associated with all aspects of the work. This was to ensure that the risks associated with the project were minimised where possible during the planning phase. Dunstans ensured that control measures are taken to eliminate or reduce the likelihood of harm to persons (including the public), property or the environment from the works undertaken at the project site.

2.2 Safety Management

Dunstans are committed to conducting activities associated with the project in a safe manner and in accordance with the relevant safety legislation and regulatory requirements. Safety is managed on site through Safe Work Method Statements, risk assessments and compliance with safe work procedures.

2.3 Environmental Management

Dunstans understand how important the environmental issues are on this project, in particular the environmental significance of the Cullendulla Creek Nature Reserve and Cullendulla Creek. This has driven the project design and methodology and we continue to look for ways to reduce our impact on the environment and local community as the project progresses.

2.4 Quality Management

Quality will be managed through compliance with the developed plans, procedures and Inspection and Test records and through the use of experienced personnel.

2.5 Emergency Management

A Project Specific Emergency Response Plan addresses the emergency response and management procedures associated with the scope of work.

2.6 Work Procedures, SWMS & ITP’s

Work procedures, Safe Work Method Statements (SWMS) and Inspection and Test Plans (ITPs) are utilised for the project to ensure that the activities comply with the relevant Plans and HSEQ requirements.



3 CONSTRUCTION METHODOLOGY

3.1 Working Hours

The approved working hours for the project are 7:00am to 6:00pm Monday to Friday. Some minor maintenance/housekeeping works is undertaken between 8.00am to 1.00pm Saturday (no engines running or deliveries/trucks). For January 2019, the work hours will be 8:00am to 6:00pm Monday to Friday. There is no work on Saturday afternoons, Sundays and public holidays.

The proposed works commenced in September 2018 and will take approximately 6 months to complete.

3.2 Site Preparation Works

3.2.1 Site Condition Surveys

Prior to commencing any construction work within each HDD site, a pre-construction site condition survey document was prepared that includes photographs. The Condition Survey will provide a benchmark for final restoration of the construction sites.

3.2.2 Site Establishment and Survey

The entry and exit sites are established as per the HDD Site layouts and involve the following:

• Survey and peg out the work sites on each side of the alignment and for any other works to determine any existing conflicts and advise the Principal for resolution.

• Establishment of Safety controls and signage, such as Emergency Muster points, first aid and emergency response equipment.

• Enclosure with temporary fencing creating a secure area to prevent unauthorised access both during and after hours.

• Establishment of erosion and sediment control measures as per the Erosion and Sediment Control Plans

• Mowing/slashing of the pipe welding alignment on the exit side if required.

Dunstans shall ensure that access to the ESC Dosing Facility compound at the end of Myamba Parade and the Sewage Pumping Station at Nuyen Place shall be maintained at all times. Public access to the track that leads to Cullendulla Creek at the HDD Exit Site shall also be maintained and kept open, where possible.

A surface (centreline survey) of the proposed HDD crossings and entry and exit points is undertaken by a registered surveyor. This survey will be registered as the baseline data and used to set out the rig and for steering baseline data.

All identified underground services assets in the vicinity of the project works will be marked and/or pegged by the survey team and physically located, where required.



It shall also be ensured that the design plans and proposed layout of the pipeline are coherent and any unique site conditions which require specific solutions are identified.

3.3 Mobilisation

The equipment required for undertaking the crossings will be mobilised to each site and set up ready for drilling as required.

Table 3.1 HDD Equipment Details

PLANT TITLE

Maxi Drill Rig

Drilling Fluid Cleaning System

High Pressure Mud Pumps [x2]

Midi Drill Rig

Mud Cleaning System

High Pressure Mud Pumps [x1]

Drill Pipe and Tooling

Excavators

Generators

Cutting Bins

Pipe Rollers

Vacuum Truck

Air Hammer

Air Compressor

Heavy vehicle route planning will be undertaken to determine the best routes and any heavy vehicle movement permits will be obtained as required.

Access into the HDD site will be assessed prior to mobilisation to ensure that the plant and equipment can be bought in safely.

3.4 Installation of 30 inch Casing

Due to the proximity of the entry location to the Cullendulla Nature Reserve and the exit location to the Cullendulla Creek, Dunstans methodology includes the installation of 30 inch diameter steel casing on both sides. This casing will significantly reduce the risks associated with any drill fluid release into the Cullendulla Nature Reserve or Cullendulla Creek.



The air hammer is attached to the first length of 30 inch diameter casing, each length of casing will be 12.0m. This first length of casing has a cutting shoe at the front of the casing to assist in the air hammer installation and reinforce the edge of the casing.

A frame is set-up on the pipeline alignment to allow correct alignment of the 30 inch casing and support the steel pipe. An excavator supporting the air hammer at the rear of the casing is utilised to control the end of the casing and prevent any sideways movement.

The frame is set-up at the correct angle of the drill alignment and checked periodically during the installation of this first length of casing.

Figure 4 Installation of Casing

After the first casing has been installed completely, the air hammer is removed from the rear of this casing. The second casing is positioned on the frame and welded to the first casing, the air hammer is then set-up at the rear of the second casing and installation of this casing will take place.

This process is repeated until the 30 inch diameter casing is installed into the harder formation below the alluvial layer.

3.5 Equipment Set Up for Drilling

The drilling equipment is mobilised and set up at each site as per approved site layout plans and the methodology below. It is proposed to commence drilling with the Midi Rig on entry side so this equipment will be mobilised and set up first.

Pressure hoses are connected from the cleaning system to the drill rig and cleaning system to the entry pit to allow control of the drill fluids.



The drill pipe is placed within reach of the drill rig and positioned such that they can be easily lifted onto the drill rig without lifting over any personnel. Additional drill pipe is positioned nearby to allow for access when additional drill pipe is required.

Water is sourced for the mud mixing from a nearby water hydrant via a standpipe. A temporary supply pipe is run to the works, which is connected each morning and removed each evening.

Site power is provided by on-site generators.

Screw piles are installed to create a “rig anchor” for the Maxi drill rig. The rig is secured to the screw piles and steel plate. The steel plate is used to distribute the forces equally across the screw piles to ensure the designed load limits are achieved. If the rock formation is too shallow to permit the installation of screw piles a concrete thrust block will be installed in-lieu of screw piles to anchor the drill rig.

Figure 5 Midi Drill Rig

Figure 6 Maxi Drill Rig



3.6 Drilling

The HDD process is usually undertaken in three distinct stages:

1. Pilot hole drilling

2. Reaming or hole opening

3. Pipe installation

The first stage consists of directionally drilling a small diameter pilot hole along the pre-determined pathway. In the second stage, the pilot hole is enlarged by successive reaming and cleaning passes. When the hole is of the suitable diameter and condition, the pipe is pulled back or thrust into the fluid filled bore.

Drilling of this bore is proposed to be completed in the following stages:

• Drilling of the first 250m of the entry and exit (Intersect Hole) with a smaller HDD Rig (this stage is to alleviate any potential risks from drilling into the casing with the big rig).

• Main Pilot Hole drilled from the HDD Entry Side to the Intersect Hole conducted with the Maxi HDD Rig (the smaller rig is not capable of drilling this distance).

• Reaming pass and cleaning passes of the entire hole length conducted with the Maxi HDD Rig from the HDD Entry Side.

• Installation of the pipe into the bore by pulling with the drill rig from the HDD Entry Side.

3.6.1 Pilot Hole Drilling

A small diameter pilot hole is drilled along the pre-determined pathway.

Directional control while drilling the pilot hole will be provided using the ParaTrack steering tool or Gyro system. The survey probe measures the survey information required for the measuring of the position and the steering of the drill tool (i.e. azimuth “horizontal plane”, inclination “vertical plane” and tool face “orientation”). The steering tool or survey probe is placed at the front of the bore head (in the Bore Hole Assembly) and this tracks the bore head location.

Survey data is gathered continuously as the drilling progresses by way of a waterproof 6mm cable connected to the rear of the survey probe. The 6mm wire is remade at the surface as each drill pipe is drilled which ensures a continuous signal wire, irrespective of drilled length, from the survey probe to the surface.

A profile plot is made as drilling progresses with each survey point or drilled pipe clearly shown following the proposed design criteria for the works. As the measuring is executed continuously, the real position can be checked against the design position on the design profile drawing. A full survey will be conducted for every joint drilled (i.e. approx. 9.8m) with interim survey checks made if required. This will enable the downhole surveyor to ensure the design profile is achieved during pilot drilling. The data captured during drilling of the pilot hole.



An example of a pilot hole Bore Hole Assembly (BHA) is shown below.

Figure 7 Pilot Hole Assembly

3.6.2 Reaming Assembly

After completion of the pilot hole to the required location, the borehole is enlarged using a reamer. The BHA layout for the proposed 14” reaming tool is shown below.

Figure 8 Reaming Assembly

The reaming direction will be from the entry side towards exit side or forward reaming.

Drill fluid during reaming is anticipated to return to the entry side of the crossing where it will be collected, cleaned and re-used.

3.6.3 Cleaning Pass

At the conclusion of forward reaming, a cleaning pass is completed to ensure there are no impediments to product pipe installation in the borehole. The cleaning pass will be conducted with a multi-directional 24” inch barrel reamer.

3.7 Drilling Fluids

A drilling fluid is used to lubricate the bit, suspend and transport the cuttings away from the face and create a filter cake to promote borehole stability. Drilling fluids are mixed with water in mixing tanks in the mud cleaning system (located near the drill rig) and pumped to the drill rig. The drilling fluid is then pumped through the drill pipe to the drill bit where high pressure jets and the bit grind the soils. The drilling fluid also carries the cuttings back to the entry pit at the drill rig.

The drill fluid with cuttings is pumped from the entry pit into the mud cleaning system. The cleaning system removes solids from the drill fluid to allow for it to be recycled and pumped back down hole.

3.7.1 Drill Fluid Makeup and Mixing

The information received from the investigative boreholes indicates that the majority of the HDD crossing will be completed through fresh and moderately weathered metasiltstone. The geotechnical report also indicates the risk of encountering some of the fractured siltstone and possibility of some voids.



A bentonite based system is in use for completion of the borehole through the rock formation as this provides ideal cutting carrying capacity to optimise removal from the borehole, as well as forming a stable borehole with a filtercake.

This system involves the use of the following products:

• Soda Ash which will reduce hardness of the mixing water and level pH of the water.

• Bentonite will provide encapsulation and flocculation of drilled cuttings, allowing easier removal by the solids control equipment.

• Drillplex provides a gel structure when fluid is static to suspend cuttings and limit settling on the bottom of the borehole.

• Loss Circulation Materials products will be maintained onsite as a contingency if required to help plug any fractures and prevent downhole losses into the formation.

Pump pressures and flow rates will be constantly monitored during completion of the pilot section.

Figure 9 Dunstans Mud Cleaning System

3.7.2 Drill Cuttings Disposal

The collected drill cuttings are stored in steel cuttings bins onsite. The cuttings are tested for Acid Sulphate Soils, treated with lime if required and removed from site and for disposal.

Dunstans will dispose of cuttings in two ways:

• Slurry/wet cuttings: A vacuum truck is utilised to collect and remove the cuttings from site to an approved facility in accordance with regulatory requirements; and/or



• Dry cuttings/clean fill: The cuttings are dried onsite to a “spade-able” composition and tested to ensure that there are no contaminants within the cuttings removed from the borehole. The cuttings are then removed from site and disposed of as clean fill in accordance with the NSW EPA requirements.

3.8 Pipe String Fabrication

Due to the limited space available for pipe stringing, Dunstans will complete the welding in three pipe strings.

The HDPE pipe strings will be welded together using butt welding at the welding station on the eastern side of the dam at the exit location.

Figure 10 Example of a Pipe Butt Weld

Figure 11 Example of a Pipe Butt Welding Machine



The strings will be fabricated on a weld and pull methodology, with the pipe being pulled up the hill towards the water tank. Dunstans will string the pipe out on rollers as it is welded. Pipe will be delivered to site via the storm water drain off Broomfield Cres per the traffic plans.

Figure 12 Example of a Pipe String

3.9 Pipe Insertion

When the borehole is completed and the pipe strings are welded, the pipeline will be strung along the bore alignment on rollers on the exit side. The pipeline will be connected to the drill string with the pulling assembly shown below

Figure 13 Pipe Insertion Assembly

Prior to installation of the pipeline, a Pre Pipe Installation Checklist will be completed to ensure all elements required to complete the pullback successfully are prepared or finalised.

The pipeline set-up for pullback shall be inspected by Dunstans to ensure that it is in line with the agreed plan and overbend design and there will be no issues on the day of installation.

The drill rig will then pull the pipeline back into the borehole.



Figure 14 Example of a Pipe being pulled in the borehole

A Pipe Stress Analysis has been undertaken to ensure that there will be no damage to the pipeline during installation. Dunstans shall ensure that the pipeline is not stretched or overloaded during installation to minimise the risk of damage by ensuring the pull forces of the rig does not exceed the safe axial pull loads of the product pipe.

3.10 Pipeline Testing

After completion of the welding a strength test and visual leak test of each pipe string will be completed. Flanges that will be welded to both ends of the pipe will be used for filling and testing of the pipeline.

During the installation of the pipeline, the pre-prepared pipe strings will need to be welded together as the pipe is installed.

3.11 Tie-ins

The new sewer rising main pipeline shall be tied-into the existing sewerage infrastructure at either end of the alignment.

3.12 Removal of Exposed Sections of Existing Sewer Main

The old sewer rising main shall be decommissioned and the exposed sections of pipe removed. It is estimated that there is approx. 500m of sewer line to remove from along Cullendulla beach foreshore.

The old sewer main shall be completely emptied into the existing infrastructure or into a septic tanker, flushed and decontaminated to protect the sensitive marine park waters. This will be completed by pigging the pipeline with a foam pig to remove any remaining contents.



3.13 Site Reinstatement

Upon completion of project works, the site will be restored to the condition as detailed in the pre-commencement site condition survey. Restoration will include the removal of all debris and excess materials and hardstand materials, backfill and compaction of excavations and reinstatement of the topsoil that was windrowed at the commencement of setup. The reinstatement will recreate the pre-existing natural grades to promote the regrowth of natural cover.

This will also include the reinstatement of the stringing alignment to ensure that natural cover growth is promoted in this area and the reinstatement of roads, footpaths, structures, vegetation or other facilities that have been disturbed during, and because of the Works.

abridged construction execution plan · managed on site through safe work method statements, risk...

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