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Stormwater improvements in Garden Street

We are planning on upgrading the infrastructure on the eastern side of Garden Street at Mullet Creek due to damage caused to the structure over the years by storms.

The proposed work includes:

  • renewing the headwall and wingwalls
  • upgrading the existing undersized apron and scour protection
  • upsizing the existing stormwater pipe connection to the southern wingwall
  • installing new pedestrian fence.

Comments on the proposal were invited between 19 July and 8 August 2021. Comments are now closed and we are reviewing feedback prior to finalising the design.

Once works are complete, the improvements will provide benefits for stormwater management and safety including:

  • preventing further deterioration of the headwall structure
  • securing the embankment on the eastern side
  • increasing the life and integrity of the structure
  • improving energy dissipation and scour protection to reduce impacts on Mullet Creek
  • improving traffic and pedestrian safety.

We have undertaken an environmental assessment for the proposed works, in accordance with statutory guidelines.

A mature tree that is located near the damaged culvert wingwall conflicts with the new wall structure and will need to be removed. The removal of this mature tree will not significantly reduce the foraging habitat availability within the locality. Three fast growing native replacement trees will be planted once the works are completed.

Any potential impacts have been identified and will be carefully managed through appropriate control measures.

During the construction activities, care will be taken to ensure there is no adverse impact on water quality and marine habitats/ vegetation.

Appropriate sediment and erosion control measures will also be installed and maintained during the works.

Overall, the proposed works will have a positive impact on the environment and on public safety by reducing the potential for further deterioration of the embankment and road collapse.

A copy of the Environmental Assessment Report is available upon request by contacting the project manager, Edward Shum at Council@northernbeaches.nsw.gov.au

The proposed works will not address any flooding issues however will significantly improve the structural integrity of the existing outlet.

The Ingleside, Elanora and Warriewood Overland Flow Flood Study was completed in June 2019 and will provide the basis of future investigations for flood mitigation in this area.

We anticipate commencing planned work in Spring 2021. We will notify local residents at least two weeks before starting any work.

Traffic and pedestrian management will be in place during the proposed works as necessary to minimise any impact on road users.

It is anticipated that the existing pedestrian median island in Garden Street above the stormwater culverts will need to be temporarily relocated to facilitate adequate access for the construction works.

The site will be temporarily fenced off and pedestrians will be diverted around the work site. Fencing will also be in place on the western side of the culvert crossing to restrict access to the work site via the upstream end of the culvert.

Temporary relocation of the existing bus stop on the eastern side of Garden Street will be required. The bus stop will likely be relocated to the intersection of Garden Street and Irrawong Road approximately 50 metres to the south, pending approval from Transport for NSW.

Construction works will generally occur Monday to Friday between 7am and 5pm.


Have an enquiry?

Have questions or want to learn more about this project, contact:

Name Edward Shum
Phone 1300 434 434
Email council@northernbeaches.nsw.gov.au
Website www.northernbeaches.nsw.gov.au
In writing

'Stormwater renewal: Garden Street, North Narrabeen', Northern Beaches Council, PO Box 82, Manly NSW 1655.

Photo credit: Royal HaskoningDHV