Dredging underway in the Bluff Harbour entrance channel

Heron Construction Company Ltd recently began dredging operations in the Bluff Harbour entrance channel.

The operations – being carried out under a deemed coastal permit issued under the Resource Management Act – include removal of fractured or fragmented rock that remained in the port entrance channel from previous dredging campaigns.

Under this project, Heron’s backhoe dredge will remove all material from the Bluff entrance that does not require blasting. The six-week dredging project is not part of the capital dredging proposal currently going through the resource consent process.

Blasting of the channel completed in the 1980s saw some fragmented rock unable to be retrieved due to the engineering limitations of dredging machinery available at the time. This fractured rock is a potential impediment to planned future capital dredging operations.

The Bluff Harbour entrance is renowned as one of the most challenging port entrance channels in New Zealand. Currently South Port New Zealand Ltd (South Port) is at the limit of its capacity for larger vessels to safely navigate in and out of the harbour.

In order to future-proof the port, allow for ongoing shipping services from Bluff, and increase the safety of the shipping vessels, South Port is proposing to increase the depth of the existing Bluff Harbour entrance channel to between 9.45 m and 9.7 m target depths.

According to the South Port, the capital dredging operation, which is likely to include rock breaking and blasting, is scheduled to commence within the next 24 months (subject to resource consent being obtained and contractor availability). This includes dredging works within the harbour entrance, the berth pockets and swinging basin, and disposing of sediment and rock to sea.