Skip navigation

Marine Parade

Introduction | Options

Options

Based on a review of previous work and suggestions raised by the community, the council has undertaken a detailed investigation of five options. Please note that Options two to five will satisfactorily address the flooding issue, while Option one would address road flooding but would not directly reduce flooding along Marine Parade.

Option 1

Send as much stormwater as possible to the outfall at the end of Bella Vista Road, to minimise the flow to the outfall at Marine Parade. This would involve:

  • building a new stormwater system to redirect stormwater to the outfall at the end of Bella Vista Road
  • upgrading the existing outfall pipe at a private address on Marine Parade. Due to potential damage to the house, the new pipe would need to be laid between two properties on Marine Parade, and an address on Bella Vista Road.
  • enlarging or re-lining existing pipes leading to outfall at Marine Parade

Considerations

  • This option will not directly relieve the flooding.
  • There are stability issues along the cliff face where the new outfall pipe would exit.
  • This is an expensive option, but will improve water quality by separating stormwater and wastewater systems, avoiding the need for future separation works.

Option 1 (151 kb PDF)

Option 2

Keep the existing outfall along Marine Parade and send excess stormwater to a new minor outfall in Short Street reserve. This would involve:

  • building a new stormwater system along Annan Street (to pick up the existing stormwater flows), connected to a new manhole on Marine Parade, then discharge via the existing outfall along Marine Parade
  • re-line the existing line running down to the outfall at Marine Parade
  • redirecting additional stormwater during extreme storms from the new manhole to a new outfall in Short Street reserve
  • a new pipe will be installed via drilling methods to a disguised outfall structure at Short Street reserve.`

Considerations

  • A new outfall in Short Street reserve would require careful design to ensure erosion does not occur and to minimise visual impact.
  • There has been opposition to works within a private property on Marine Parade due to ground conditions, but re-lining would not pose a risk and would reduce the risk of pipe collapse.
  • This is a cost effective option that both relieves flooding and allows for the future separation of stormwater and wastewater systems.

Option 2 (279 kb PDF)

Option 3

Upgrade the existing outfall along Marine Parade, making the Short Street Reserve outfall (as proposed under Option two) redundant. This would involve:

  • building a new stormwater system for Annan Street to pick-up the existing stormwater flows, while deepening of the existing manhole in Marine Parade
  • installing a new pipeline under Marine Parade down to the existing outfall.

Considerations

  • This option is similar to Option two, but without the new overflow weir and outfall at Short Street reserve.
  • The main risk is installing the new pipe close to houses on Marine Parade through ground that shows signs of movement.
  • This is a cost-effective option.

Option 3 (300 kb PDF)

Option 4

Abandon the existing outfall at Marine Parade and send stormwater to a new outfall at Sloanes Beach. This would involve:

  • building a new stormwater system for Marine Parade and Annan Street, with a new pipe down Short Street reserve to a new disguised outfall around the base of the cliff.
  • the pipe would be drilled beneath Short Street Reserve with minimal impact.

Considerations

  • This is the original option that was proposed through public notification.
  • The new outfall would be away from the main part of the beach and partially screened by the existing boat house. The exact location of the outfall is yet to be determined.
  • The new outfall would be carefully designed to avoid erosion of the beach and to blend into the surrounding environment. This is a similar approach to the new outfall and artificial rock grove at St Heliers beach.
  • This is a cost-effective option.

Option 4 (343kb PDF)

Option 5

Send all stormwater to a new outfall at the bottom of Bella Vista Road. This would involve:

  • building a new stormwater system for Annan Street by drilling methods, to pick up the existing stormwater flows, with a new outfall discharging to the harbour from Marine Parade.
  • the existing outfall along Marine Parade would be abandoned.
  • the existing stormwater pipe that is discharging directly on to Sloanes Beach would be retained.

Considerations

  • There are some stability issues along the cliff face where the new outfall pipe exits.
  • The pipeline will need to be very deep, requiring excavations to between 9m and 18m depth. This poses various construction and future maintenance difficulties.
  • A new Resource Consent will need to be sought for the new outfall.
  • This is a very costly option.

Option 5 (266 kb PDF)