Projects

Dempsey Street

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This project is the first stage of Auckland City Council’s programme to reduce stormwater flooding problems in the Meadowbank Catchment by providing additional capacity for the conveyance of storm flows.

To achieve this objective, it was proposed to upgrade the existing stormwater systems with the installation of new stormwater lines (and abandonment of some of the existing lines) to provide the additional conveyance capacity.

The alignment of the new pipeline commenced at the outlet in Martyn Wilson Reserve, up Orakei Road, turning into Dell Avenue and terminating approximately 100 metres up Dempsey Street.

The construction works commenced in November 2004 with the pipeline installed in four drives using Harker Underground Construction’s Akkerman 2000H open face wheel machine, modified to operate in the perceived sandstone and clay ground conditions.

Drive 1 commenced from a 4.2 metre deep jacking shaft (upstream of the outlet in Martyn Wilson Reserve) and proceeded upstream for a distance of 72 metres under the carriageway of Orakei Road before terminating in a receiving shaft approximately 7.2 metres deep. Ground conditions encountered included soft clays at commencement, followed by sandstone for the remainder of the drive.

Drive 2 commenced from the terminating shaft for Drive 1 for a distance upstream of 307 metres under the carriageway of Orakei Road, terminating in a recovery shaft 24 metres deep at the corner of Orakei Road and Dell Avenue. The recovery shaft allowed for the retrieval of the TBM and installation of a pre-fabricated 90o lobster back bend.

Drive 2 encountered mainly sandstone ground conditions.

Drive 3 commenced from a bi-directional jacking shaft (10 metres by 10 metres, 8 metres deep) located at the intersection of Dell Avenue and Dempsey Street and was driven downstream to the recovery shaft at the corner of Orakei Road and Dell Avenue, a distance of approximately 190 metres. The first 65 metres was in soft clays, with the remainder of the drive in sandstone.

Drive 4 was an upstream drive of approximately 100 metres, in soft clays, from the bi-directional jacking shaft to a recovery shaft approximately 8 metres deep.

Ancillary works included the upgrade of the existing outlet and open channel to cater for the increased storm flows. The works involved the excavation of the open channel to provide the required conveyance capacity, scour protection, landscaping and planting of the channel banks.

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