An Environment Court appeal hearing for Meridian Energy's proposed $1.5 billion Project Hayes wind farm was told yesterday the earthworks planned were considered to be at a low level of development.
Cardno TCB Ltd director Ray O'Callaghan, of Wellington, gave evidence for Meridian Energy on the management of erosion and sediment control associated with the proposed earthworks of Project Hayes.
Creating roads and turbine foundation platforms for such a project is expected to require the excavation of up to 1.5 million cubic metres of soil on the Lammermoor Range.
Such earthworks are required to alter or form about 150km of access roads to, and within, the 92sq km site, which is proposed to comprise 176 turbines.
Additionally,the modification of Old Dunstan Rd and Pylon Rd will involve substantial cut and fill operations.
Mr O'Callaghan said it was common to move between 2000cu m and 3000cu m of land material per house site when forming residential development on rolling or steep land.
On flat land about 500cu m was commonly moved, he said.
"Based on my experience, the earthworks required for Project Hayes are therefore reasonably low," he said.
Up to 10m cuts would be made in the land during the construction of roads, with 3m-4m cuts expected on less steep ground.
When cross-examined by Upland Landscape Protection Society counsel Ewan Carr, Mr O'Callaghan said about 40% of the modified or constructed roads would not require such channels to be cut.
In total between 250ha and 300ha of the site would be disturbed to a degree, of which about 90ha was where turbines would be created, between 100ha and 110ha where roads would be created, and between 70 and 80ha where fill sites would be created.
Mr O'Callaghan said of the quoted disturbed areas 50% of the roading would be revegetated, as well as 100% of the fill sites and turbine sites.
He said although the proposed project was on a large site, it would be developed in stages and earthworks would occur at different times and would be contained within certain areas.
This was intended to minimise the amount of sediment run-off and erosion, he said.
"We won't end up with all fill sites or grit tracks being managed at any one time.
Getting closer to winter I also envisage a preparing of the site for shut-down mode," he said.
In his written evidence, Mr O'Callaghan said there would likely be limited soil erosion generated by earthworks, as the predominant surface material on the Lammermoor Range was thin topsoil overlaying weak and weathered schist rock.
He said faces of easily erodible material exposed by excavation of the new road sites would also be limited.
In some low lying areas where the depth of topsoil and sediment was greater, excavation itself would be limited as it was expected filling would be used to level the ground.
Mr O'Callaghan said topsoil stripped from the excavation and filling areas would be stockpiled and re-spread on fill areas to assist with revegetation.
Other mitigation methods for the reduction of soil erosion included the watering of dusty roads, reduced speed on roads, or sealing of roads.
"From an environmental management of earthworks perspective, there is no reason to decline consent [for Project Hayes], and no amendments to the proposed conditions are necessary," Mr O'Callaghan said.
