Nambucca Heads to Urunga Pacific Highway upgrade

may 2014

Nambucca Heads to Urunga Pacific Highway upgrade: Blasting at Tower Road, Urunga

Controlled open cut blasting will be used to remove hard rock with explosives where traditional mechanical methods such as rock hammers are not feasible due to the strength of the rock, volume of material to be removed and significant associated noise and vibration impact to nearby residents. The broken rock will then be removed for crushing or re-use on the project.

What’s happening?

Trial controlled blasts were carried out at Tower Road, Urunga,in mid-April to establish the properties of the rock. The trial controlled blasts were monitored and the data used to further refine the design, and to ensure the full controlled production blasts comply with the vibration and over pressure limits approved under the Minister’s Conditions of Approval for the project.

Following the trial controlled blasts, the project team is planning to carry out controlled open cut production blasting at Tower Road from May2014 for about eight months, between 9am-5pm Monday to Friday and 9am-1pm Saturday, weather permitting. The first blast is now scheduled for Thursday 8 May 2014. Typically only one blast per week will be required, however it may be split into two or three smaller blasts. Residents will be notified up to 48 hours in advance of each controlled blast.

Traffic delays of up to 15 minutes may be expected on Ainsworth Road, Urunga,between Back Paddock and Moyles roads with traffic control in placeduring the controlled blast.

Restricted access will also be in place around the worksite. Traffic control measures and advanced signage will be in place throughout the works, and residents are asked to observe and obey any directions given by traffic controllers to ensure the safety of motorists and workers.

The controlled open cut production blasting is not anticipated to cause any traffic delays to the Pacific Highway.

What you need to do

As a precautionary measure only, residents within close proximity to the controlled blasts are asked to remain indoors during the controlled blast or can be temporarily relocated to a ‘safe zone’ during blast periods. Residents will be contacted 48 hours before each blast takes place. If you would like to be escorted to a safe zone, please contact the Community Relations Team on 1800 800 612.

Controlled blasting will take about 15 minutes and nearby residents will be advised when each controlled blast is planned to occur.

Pet and animal care

For residents in close proximity to the controlled blast, it is advisable to keep smaller pets inside the house or shed during controlled blasting for their safety and well-being. Animals in paddocks should be checked before and after blasting.

Noise and vibration

The project is subject to strict environmental controls, including managing construction noise and vibration impacts. Noise and vibration outside the vicinity of the blast zone will be minimal for each controlled blast. Local exclusion zones will be established and enforced by safety spotters.

Noise, vibration, and airblast overpressure will be monitored as part of the controlled blasting operations in accordance with the project’s approved Noise and Vibration Management Plan. Controlled blasting and vibration monitors will be established to capture and analyse data.

The project team appreciates your patience and understanding during the controlled blasts and apologises for any inconvenience this work may cause.

If you require any more information or would like to talk to a member of the project team, please contact us calling 1800 800 612 (toll free), writing to PO Box 506, Nambucca Heads NSW 2448 or email

A factsheet on controlled blasting accompanies this letter to help answer your questions.

Yours faithfully

Paul Leonard

Senior Project Manager, Nambucca Heads to Urunga upgrade

Pacific Highway Office

Roads and Maritime Services

Controlled blasting fact sheet

Frequently asked questions

Background

Controlled blasting will be required to break up about 400,000 cubic metres of rock across the project. At this stage of the project there is only one location planned for controlled blast which is atTower Road, Urunga. There may be some smaller blasts required in other cuttings across the project where boulders are found to protrude through the road surface. Controlled blasting is expected to be carried out between 9am and 5pm Monday to Friday and 9am-1pm Saturday, once a week until February 2015, weather permitting.

Why is controlled blasting required?

The alignment of the upgrade has been designed to have a balance between cut and fill material while providing the most level road grade possible for drivers. A level road grade provides many benefits including safety, reduces fuel consumption as well as noise levels associated with motor vehicle engines and truck breaking.

To achieve these flatter (vertical) grades on the Nambucca Heads to Urunga Pacific Highway upgrade, cuttings will be constructed up to 30metres deep through some of the hills. Geotechnical investigation and testing has determined that the rock in some of these cuts is of a high strength and cannot be excavated using machinery alone.

Rock gathered during the controlled blastingcan be used on the project, reducing the volume of imported rock required and number of gravel trucks using Waterfall Way.

Where is controlled blasting required?

Controlled blasting is required on the new alignment at Tower Road, Urunga which is south of Martells Road (see attached map for locations). Controlled blasting may also be required in the other cuttings along the project should rock outcrops be found during construction.

When is controlled blasting likely to start?

Blasting on Tower Road, Urunga is expected to start Thursday 8 May 2014, weather permitting. All blasting for the project is expected to be complete by February 2015, weather permitting.

How often will controlled blasting occur?

The project team has planned to minimise the controlled blasts to one per week at Tower Road, Urunga. Controlled blasting are currently not planned to take place on weekends or public holidays unless otherwise advised in advance.

What time will each controlled blast occur?

Controlled blasting will take about 15 minutes and nearby residents will be advised when each controlled blast will occur. Typically blasts will occur during the middle of the day.

How do we manage the impacts of controlled blasting?

Significant blast design and modelling work considering the geology of the area, the location and condition of sensitive receivers and vibration and air blast overpressure limits is undertaken. In addition, the project team will prepare a project specific Blast Management Plan and associated work method statements.

Vibration is controlled by adjusting the size and timing of the maximum instantaneous charge (MIC), which is the amount of explosive detonated at any particular instant. The size of the MIC is adjusted so that the limits for ground vibration and air blast overpressure for each sensitive receiver are not exceeded. The size of the MIC is managed by using delays on the detonators so that the controlled blast is set off in a predetermined sequence and by reducing or extending the length of each controlled blast.

The data recovered from the monitoring of each controlled blast, including an initial trial blast, is compared to the predicted effects, to enable the project team to further refine and optimise each blast design.

Monitoring of noise, vibration and airblast overpressure will be carried out for each controlled blast. Flashing warning lights attached to vibration monitors, triggered by vibrations in excess of the component Peak Particle Velocity limit for the relevant building type will provide a “real time” visual warning of vibration exceedances. This information will be regularly uploaded to the project website.

Where there is the potential for fly rock, ‘blast mats’ (made of thick shock absorbing rubber) may be used or alternatively the overburden earth material may be kept in place.

What are the blasting mitigation measures?

Affected residents will be informed prior to any controlled blast. Public safety and government guidelines require that all people, vehicles and livestock are a safe distance away from the blast zone. To ensure people are at a safe distance from each blast, mitigation measures may include:

  • Temporary closure of access locations to local roads, and property accesses (residents will be notified in advance).
  • Stopping of traffic on Ainsworth Road, Urunga, for up to 10 minutes. This measure will be coordinated to ensure it has a minimal impact on the local community. Provision will be made to ensure that emergency access is maintained during any road closures.
  • For safety reasons, some residents within close proximity to controlled blasts may be asked to remain indoors or be temporarily relocated during controlled blasting (open cut blasting only). The community relations team will be in contact with affected residents in advance.

What should I do if I have valuables and antiques in my house?

While there should be no discernable impact for most residents from the blasting operations, it may be advisable, as a precautionary measure, to remove any valuables and antiques from shelves or walls during the controlled blasting works. The project team will be available to inspect individual properties and provide additional guidance on this matter on a case by case basis.

What should I do if I think my house has been damaged?

In the unlikely event any damage is caused to your property during the blasting process please contact the Community Relations Manager immediately on 1800 800 612 (toll free). The project team will organise to have the damage inspected and will monitor your dwelling during future blasts to determine if the controlled blasting has caused the damage.The project team will rectify any damage found to have been caused by the controlled blasting work.

Roads and Maritime

I 1800 800 612 I