PROJECT  QUATTRO

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MARTHA OPEN PIT PHASE 5

 

OVERVIEW

The Martha open pit has been successfully operated since 1987. A slip on the North Wall halted production in 2015. Recent exploration work has identified additional ore reserves in and below the pit that may provide the opportunity for mining to return to the Martha open pit. The understanding of this opportunity has advanced to a point where the Company is ready to share the proposed project with interested and impacted stakeholders and seek their feedback prior to lodging resource consent applications.

Martha Open Pit Phase 5, or MOP5, is a component of the overarching Project Quattro.

 

ABOUT MARTHA OPEN PIT PHASE 5

The development of Martha Open Pit Phase 5 involves cutting back the Martha pit around its full circumference. The pit will generally be about 40 m deeper, 160 m longer and 80 m wider than the existing Martha pit. Surface mining operations will be by conventional drill, blast, load, and haul methods.

Rock from the Martha pit will be conveyed, using the existing conveyor, to the rock and tailings loadout for construction of TSF3, the Northern Rock Stack or backfilling underground.

If approved, our construction and mining operations will be subject to strict consent conditions that will cover noise, dust, vibration, blasting times, and hours of operation.

HOURS OF OPERATION

OceanaGold Waihi is proposing that the Martha pit will operate as follows:

• Monday to Friday: 7 am – 7 pm.
• Saturday: 7 am – 12 pm.

We are proposing that Monday to Friday, where urgent works are required, hours of operation in the Martha pit may be extended to 9 pm. Details of operations between 7 pm and 9 pm would be recorded and made available to Hauraki District Council on request. The pit would not operate on Sundays or Public Holidays.


BLASTING

Drilling and blasting in the pit will be required for the removal of ore and rock, although some of the upper areas may be excavated without blasting.
OceanaGold Waihi is proposing that blasting occur daily in the pit between:

• Monday to Friday: 10 am 3 pm.
• Saturday: 10 am – 12 pm.


ROADING CHANGES

There will need to be some realignments of a number of urban streets, and these have been designed to cause the least possible impact to traffic flow and road users. The Cambridge Road / Bulltown Road junction will need to be realigned, as will a section of Moresby Avenue and Savage Road. The top end of Martha and Haszard Streets will be closed.


RELOCATIONS

The Martha Open Pit Phase 5 extensions will require the relocation of several existing town features, for example, the Cornish Pumphouse will require a further relocation. Other infrastructure would include the Hauraki District Council ‘housing for the elderly’ flats, the 777C dump truck, ‘Stargate’ girth gear, the Pit Rim Walkway, Rangatira statue, plus some OceanaGold Waihi-owned residential properties and the Education Centre.


REMOVALS

A number of features will need to be removed to accommodate the pit extension. These include part of the PYE building (OceanaGold office), a number of trees around the pit perimeter, including ‘Judge’s Kauri’, and the Grand Junction Powerhouse foundations.


CENTRAL SCHOOL

Martha Open Pit Phase 5 will bring our operations closer to Waihi Central School. We will work with the school community to ensure that the effects from the construction and operation of the mine will have as little impact on the school as possible.


NOISE BUNDS AND SCREENS

Our noise assessment has identified the need for a noise bund in the vicinity of Grey Street and Slevin Street to mitigate the impact of noise on residents near the open pit. While the size of the bund will be greater than the current bund (as its base will be at a lower elevation), it will be about the same height.

The work to construct this bund will necessitate the diversion of a small section of the Eastern Stream and the loss of a wetland within the Slevin Street park area.

In order to comply with noise limits, it will also be necessary to construct noise bunds or screens around other sections of the pit perimeter. Investigations into the height, length and form of this noise mitigation is ongoing. As the technical studies progress, we will consult with the community and their feedback will contribute to the final project design.

REHABILITATION

Rehabilitation of the pit surrounds will be progressive and ongoing to minimise the disruption of existing spaces used by the public. At the completion of mining activities, the Martha pit area will be rehabilitated into parkland suitable for recreational use by the public. The pit will be filled with water to form a lake.


KEY EFFECTS

HERITAGE

The main heritage items identified as being impacted by Martha Open Pit Phase 5 are the Cornish Pumphouse, the PYE building, and the Grand Junction mine relics. These impacts have been assessed against the level or severity of the effect. Where impacts are unavoidable, management measures will be put in place to mitigate the effects so as to maintain or enhance the archaeological and heritage value of the Waihi area.


AIR QUALITY

If Project Quattro is approved, we will be required to comply with consent conditions for air quality through a regional consent from the Waikato Regional Council. This will require OceanaGold Waihi to produce an Air Quality Management Plan for approval by the Regional Council.

There are a range of air quality management measures that may be implemented to meet these requirements, including:

• Watering haul roads and using sprinkler systems and water sprays where required.

• Dust collectors and filters on drill rigs.

• Applying dust suppression product.

• Keeping stockpiles low so wind is less likely to spread dust.

• Planting grass to cover long-term stockpiles.

• Planting pasture, shrubs and trees as soon as rehabilitation areas are available.

• Washing vehicles before leaving site to travel on public roads.


NOISE

If Project Quattro is approved, we will be required to manage our activities so that we comply with strict noise limits in line with the Hauraki District Plan.

There are a range of noise management measures that may be implemented to meet these requirements, including:

• Equipment selection and maintenance.

• Construction and vegetation of noise bunds.

• Cladding to reduce conveyor noise.

• Limiting the height of stockpiles.

• Acoustic cladding around potentially noisy machinery.

• Closed board fencing.

• Acoustic noise wall on some sections of perimeter noise bund.


VIBRATION

OceanaGold Waihi will propose a compliance level of 5 mm/s for 95% of the monitored events. This is set to be protective of amenity and well below levels capable of causing property damage.

We recognise that some residents close to the Martha mine may, from time to time, experience a perceived reduction in amenity due to mining activities. For this reason, we will continue to make Amenity Effect Payments to qualifying residents in an effort to offset this perceived loss of amenity.


LIGHTING

To provide for mining outside of daylight hours, lighting will need to be established in the pit. The lighting will be designed and located so that the amount of light is protective of the amenity of nearby residents.


DEWATERING

The Martha pit is already dewatered as part of the current underground operations. No additional dewatering will be required in order to facilitate Martha Open Pit Phase 5.


GROUND SETTLEMENT

The settlement effects associated with Project Quattro are expected to be very small and pose little risk of damage to buildings or infrastructure.

The existing network of survey markers and piezometers may be extended for Project Quattro. They will continue to be monitored and, in the event of an anomaly, investigated and addressed as appropriate.

In the very unlikely event that property damage does occur due to settlement, OceanaGold Waihi will mitigate any adverse outcome by applying its ‘We Break, We Pay’ policy.

PROPERTY EFFECTS

DAMAGE

Consent conditions for vibration will be set well below the level where cosmetic property damage could occur. We know from the community, that there can be concern around what we would do if mine-related activity caused property damage. In recognition of this, we have a procedure in place to assist owners if they believe their property may have been damaged. If it is determined that property damage is attributable to our activities, OceanaGold Waihi will remedy the damage at our cost.

VALUES

The extension of the mine life to 2037, if approved, will continue the positive impact on property values that have been experienced in Waihi since modern mining commenced. Our property value assessment has identified the potential for the proposed Project Quattro to have a minor impact on the values of a small number of properties near Martha Open Pit Phase 5. This is not expected to be long-lasting.

The properties identified in the assessment would be eligible for our Top Up management measure in accordance with the criteria of our property programme.