A $6.76 million remediation project at an urban Auckland park is being hailed as an environmental triumph.

Newmarket Park, a 6ha reserve nestled between the suburbs of Newmarket, Parnell and Remuera and with sweeping views across Hobson Bay, reopens officially with a public family open day on Sunday 15 July.

The celebration will mark the completion of two and a half years of capital works, during which time much of the park was closed.

The works included stabilising a 350 metre slope to stop subsidence, removing landfill material, improving the drainage systems and planting 10,000 native trees.

Waitemata Local Board chair Shale Chambers, who will open the park at the family day, says welcoming children and families back into the space is a powerful testament to the success of the project.

"A number of risks and dangers have been fixed to make the park fit for public use. Additional restoration work also gives people an attractive environmental haven to enjoy," says Mr Chambers. "As growth in our region puts more and more pressure on available recreational space, this is a fantastic result for all Aucklanders."

Auckland Council environmental services manager Janis McArdle says from the 200 plus sites listed on the council's closed landfills asset management plan, Newmarket Park was the highest priority to address.

"This was not the first closed landfill we've tackled, with Phyllis Street Reserve in Mt Albert, Seddon Fields in Pt Chevalier and Seaside Park in Otahuhu completed in the past decade. However, Newmarket Park is our largest and most complex project to date, and I am immensely pleased by the work that has been done to bring this park to the standard we see today. I believe it will mature into something spectacular in coming years."

The council is now scoping a $4 million project at Waikowhai Park, once known as the Blockhouse Bay tip.