Measures to control sediment run off from Transmission Gully are the most comprehensive and rigorous ever seen for a project of this scale, a board of inquiry has heard.
Sediment-laden run off flowing into Porirua Harbour, including the nationally significant Pauatahanui Inlet, is a contentious issue and will be central to the board of inquiry's final decision on the $1 billion alternative inland route.
The hearing wrapped up yesterday after three weeks of lawyers and experts attempting to convince the board on the long-debated projects's merits and flaws.
First floated in 1919 as an answer to the region's traffic woes, the 27km road linking Linden to McKays Crossing aims to ease congestion on State Highway 1, shave travel times, boost the region's economy and provide a secure connection to the capital should a natural disaster strike.
Transpower, the New Zealand Transport Agency and Porirua City Council, which lodged 5000 pages of resource consent applications and notices of requirements, summed up their cases yesterday.
NZTA legal representative John Hassan said proposed consent conditions were described by an ecologist as more comprehensive and rigorous than he had seen elsewhere in relation to sediment controls.
Mitigation, such as planting and retirement of farm land, to make up for losses during construction and use of the highway go further than necessary under the Resource Management Act by aiming for a no net loss to ecology.
He described the Conservation Department's suggested conditions as "excessive" and urged the board to reject them in its final decision, should it approve the project.
Kapiti Coast District Council's proposed condition for a local road between Paekakariki and McKays Crossing to be investigated would be inappropriate as NZTA had already considered it, Mr Hassan said.
The proximity of the Gully road to three Paekakariki Hill Rd neighbours, who told the board the road would carve through their backyards, was not as close as suggested, he said.
Should NZTA shift the road as far as Eberhard Deuss, David Christensen and Philip Poppe want, it would be steeper than the maximum recommended gradient, which is the same as Ngauranga Gorge.
Suggestions by the Rational Transport Society that NZTA did not call relevant evidence on cycling and walking matters were "blatantly incorrect", Mr Hassan said.
Transpower legal representative Morgan Slyfield said Transmission Gully could be scuppered if approval to shift 24 power pylons was denied.