A PCC subcommittee heard submissions for two weeks in March and April with particular emphasis on the proposed 50-turbine Puketiro development above Pauatahanui.

The hearings were adjourned after the committee asked for evidence on the health effects of vibration and low-frequency noise to be investigated.

Last Wednesday council resolved to extend the timeframe. A decision must now be made by December 18.

A report to councillors from PCC environmental policy analyst Peter Matich says the delayed start to hearings was because the "large number and technical nature of submissions received" and the request for additional information has meant an extension is needed.

"The ability to consider the matters raised in these submissions and to have time to research and prepare a reasoned response is not unreasonable."

Subcommittee chair Liz Kelly said they will be likely to reconvene in early September.

From there it will take about a month to finish deliberations.

"The indication I got is that it's going to take a while to get the information we need [on low frequency noise and vibration from turbines] as it was not available at that time [in April].

"It's taken longer than we were originally told but it is important we do a thorough job and look at all the options.

"To make an informed decision on such a massive issue like this, you need to have all the information."

The proposed plan change was originally notified in September 2007.

More than 100 submissions were received by closing date in December 2007.

The main sticking point heard by the subcommittee was the proposed 700 metre buffer zone between a turbine and a property's boundary. Puketiro developer RES and the NZ Wind Energy Association say it's too restrictive, while opponents say the buffer isn't big enough.