The cost of a synthetic football field in Sydney's north has blown out to $20 million, five years after it was estimated to cost ratepayers $3.3 million.

In late 2021 Ku-ring-gai Council appointed TurfOne to replace the grass field at Norman Griffiths Oval in West Pymble with a synthetic pitch.

Costs for the project blew out to $6.9 million in May last year before the council fired the contractor for what it said was "environmental risk exposure" and "performance deficiencies".

The council has since been managing the site and voted to increase the project budget to $12.4 million in September last year.

The council has been ordered by an adjudicator to pay the contractor $4.4 million over terminating the contract, which is considering legal options in response.

The cost of the stormwater detention system has also increased because the council is moving to reverse the contractor's decision, with the council's approval, to build an aggregated-based detention system.

At a meeting next week the council will vote on whether to increase the budget to $20 million to cover the termination payout and the concrete stormwater detention system.

A spokesperson for Ku-ring-gai Council said the $20 million estimate did not take into account a potential recovery of costs against the former contractor.

"Increased costs for the new stormwater detention system, environmental and site management costs, plus legal costs associated with the termination of the previous contractor have contributed to the increased project costs," the spokesperson said.

"Funding is available in the council's internal infrastructure and facilities reserve for this additional expenditure.

ABC Sydney has contacted TurfOne's parent company BildGroup for comment.

Ku-ring-gai Mayor Christine Kay did not comment on the cost increase, instead saying she wanted to hear from the community at the council's public forum on Tuesday evening.

The council's spokesperson said the field was expected to be finish between February and May next year depending on the availability of suitable contractors.

Work is progressing on the field with the additional oversight of NSW Public Works.

'Muddy bog hole' never should've used artificial turf: critic

Public policy specialist and longtime critic of the project, Bronwen Hanna, said the Norman Griffiths project was likely "Australia's most expensive soccer pitch".

Ms Hanna said the natural field needed an upgrade but was too flood-prone to suit an artificial field.

"It was a muddy bog hole," Ms Hanna said.

"It's surrounded by a critically endangered plant community and it's above a creek that flows into national park.

Football club left languishing

Norman Griffiths Oval is home to West Pymble FC which has been "flung to the four corners of the Ku-ring-gai Council area" to play their home games, according to the club's president Kieron Fitzpatrick.

The construction project has also locked off the clubhouse, which Mr Fitzpatrick said was impacting the clubs ability to grow, bring in players and build their community.

"I would've thought it was a minimum a $1,000 a week if you think of all we could [have] raised through barbecues," Mr Fitzpatrick said.

"The bigger question people keep saying, slightly mockingly, is "so when is this going to get finished?

"Is it going to be [another] North Sydney Pool issue?"

Mr Fitzpatrick said the club wanted to see the synthetic field finished because the previous grass field would often be unusable due to rain and slow drainage.

"Washouts were a regular feature. It's not just games, it's training, its other participation activities."