Puketutu Island Rehabilitation Proposal

Watercare Services Limited is seeking to rehabilitate a former quarry on Puketutu Island with treated biosolids over a 35-year period. As part of the proposal, the island will be progressively opened to the public as a regional park.

About Puketutu Island
The island’s rich Maori and European heritage has shaped the landscape. It was the location of one of Auckland’s longest Maori settlements and has sites of significance to local iwi. In 1938 it was purchased by Sir Henry Kelliher and since then it has been used as a racing stud, sheep farm and functions venue.

Over the past 60 years the island has also been used extensively for quarrying and the disposal of clean-fill. During this time the original volcanic cones have been considerably modified and removed.

Watercare plans to rehabilitate part of the quarried area using treated biosolids over a 35-year period. An agreement has been reached with the Sir Henry Kelliher Charitable Trust to grant Watercare a long-term lease of the island – subject to Watercare obtaining all necessary approvals. Under this arrangement, ownership of the island will be gifted to the Auckland Regional Council or a new charitable trust for development as a regional park. They will progressively receive land not required for rehabilitation from Watercare until the entire island is a regional park.

Rehabilitation Using Treated Biosolids
Biosolids are a treated solid by-product of the wastewater treatment process. They can be safely and beneficially applied to land. Watercare is currently using biosolids from the Mangere Wastewater Treatment Plant to rehabilitate a 44-hectare area of former oxidation pond across the causeway from Puketutu Island.

Each day Watercare produces around 300 tonnes of treated biosolids at the Mangere Wastewater Treatment Plant. That equals around 30 truck-loads. The former quarry on Puketutu Island has the capacity for around 35 years’ production.

Under Watercare’s proposal, treated biosolids will be placed as a series of layers and contained within an embankment on the island. Over time these layers will create an elevated central landform next to the existing volcanic cone.

The treated biosolids placement area will be constructed using modern engineering techniques that will avoid adverse environmental effects. These techniques include the construction of a lining-layer on the inside of the quarry, the development of a leachate collection system, appropriate stormwater treatment and diversion systems, and a landscaped cover on completed areas.

The footprint of the completed landform will be approximately 46-hectares, while the footprint of the treated biosolids placement area inside the embankment will be approximately 28-hectares.

The height of the final landform will vary from approximately 40-metres in the north-east of the rehabilitation area to approximately 25-metres in the west. The upper surface will be gently sloped with a series of steps of steeper grades.

The rehabilitated site will be landscaped and progressively released to the Auckland Regional Council or a charitable trust as a regional park.

Subject to obtaining the necessary approvals for the development, rehabilitation is expected to start around 2012.

Benefits of the proposal
Watercare evaluated 26 sites and concluded that the Puketutu Island rehabilitation proposal offers the most benefits, including:

• the largest capacity site
• the longest lifetime of operation
• the lowest cost
• close proximity to the treatment plant – reducing truck movements.

In addition, the people of Auckland will be able to enjoy a new regional park on the island, developed and operated by the Auckland Regional Council or a new charitable trust.

 Recent Interflow coverage regarding the project

	Interflow Spring 2009 (108KB)	Watercare continues to support vision for Puketutu Island
	Interflow Summer 2008 (125KB)	Public notification of the Puketutu Island proposal
	Interflow August 2008 (331KB)	Puketutu proposal passes to next stage
	Interflow May 2008 (236KB)	Next stage nears on Puketutu proposal