The visual impact of two of the 111-metre tall turbines, at the southern end of the site, on nearby farms and properties was the principal reason why the commissioners turned them down.
The 200-page decision report by independent commissioners David Hill (Chair), David McMahon and Pamela Peters has been released today.
The commissioners have imposed a comprehensive raft of consent conditions that relate to turbine noise, visual impact and construction and earthworks.
Construction and earthworks conditions are designed to minimise the adverse effects to streams in the area and the Makara Estuary.
These include conditions around proper treatment of sediment runoff, ongoing monitoring of water quality, aquatic ecosystems and sediment levels, and provision of fish passage in streams affected by stream crossings and diversions.
The commissioners were appointed by Wellington and Porirua city councils and Greater Wellington Regional Council to hear and decide Meridian's application.
A total of 776 submissions to the proposal were received by the close of submissions last June. A total of 364 submissions supported the application, 408 submissions were opposed and four submissions were neutral.
The hearing was held in August and September.
Meridian's proposal was for a wind farm with 31 wind turbines and a total capacity of up to 71.3 megawatts (MW). The wind farm would use Siemens wind turbines, each 111m tall with a rotor diameter of 82.4m - similar to the machinery being installed on the Project West Wind site to the south.
More than 800,000m3 of earthworks is proposed for the Mill Creek complex to create turbine platforms and access tracks and roads.
Aviation lighting is proposed to be installed on up to 11 turbines as the site is near the flight path approaches to Wellington Airport. The flashing lights, required by the Civil Aviation Authority, would be shielded so they are not directly visible below the 'horizontal plane'.
Though the proposed wind farm is within the boundaries of Wellington City, Porirua City is also involved because the project calls for the construction of a private road from Spicer Valley - in Porirua City. The road would be used for the delivery of turbines and other equipment and by assorted construction traffic.
The full 204-page decision is available as a PDF file on the Notified Resource Consent section on the website as well as the Wind Farms web page from 4.00pm today.
Submitters to the consent application process have 15 working days to appeal the decision to the Environment Court.