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Rosedale Wastewater Treatment Plant (WWTP) Upgrade

Volume of Wastewater Treated

19.7m m³/y

Activated Sludge Tank Capacity

7,000m³ each

Secondary Clarifiers

Four x 48m diameter

Secondary Treatment BOD Removal

75% to 80%

Secondary Effluent BOD Load


Polishing Lakes Detention Period

Up to 35 days

New Faecal Coliform Standard

1,000cfu per 100ml (median value)

Final UV Treatment System (after expansion)

Six-channel system (1,296 lamps)

UV Treatment Full Peak Flow

3m³/s to 4m³/s

UV Treatment System Cost


Total Estimated Cost (Stage 4)


Estimated Cost of the New Outfall


Stage 5 Cost


Rosedale Tunnel and Outfall Cost


Resource Consent Approval

April 2001

Stage 4 Upgrade Completion


New Faecal Coliform Standard Effective from

1 January 2004

Foreshore Sewer Upgrade Phase I Completed

November 2003

Foreshore Sewer Upgrade Phase II Commenced

May 2004

Deadline for Reuse / Composting of Biosolids


New Sea Outfall Completion Required by

1 July 2008

Stage 5 Completion

May 2008

Rosedale Tunnel and Outfall Completion

August 2010

Project Sponsor / Finance

North Shore City Council

Regulatory Body

Auckland Regional Council

Consulting Engineers

Sinclair Knight Merz

Environmental Planning Consultants

Simpson Grierson

Nutrient Removal System Design


UV System


Maintenance Contractor


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