Transmission Gully's Wainui Saddle. Photo / Supplied
A scathing report identified 88 "issues" with the beleaguered Transmission Gully highway build, ranging from fears part of the construction might collapse onto motorists and workers after the road opened, to concerns that fish might not be able to pass underneath the structure as promised.
Concerns raised in a monthly project report from Stantec last November add to fears the already delayed road may struggle to open soon. It listed longstanding shortages of concrete and workers as ongoing problems.
Just 26 of the 88 issues had been resolved as of November, and two were partly resolved. The rest were outstanding.
A Waka Kotahi spokesman noted that the "construction quality issues identified by Waka Kotahi's site monitors Stantec are not necessarily the same as the issues required to be addressed to meet the safety and quality assurance tests, but there will be some crossover".
The issues are rated green, amber and red, depending on seriousness.
Among the "red" problems identified was a large crack Stantec became aware of last February.
Stantec said in the middle of 2020 a crack appeared in one of the "bench cuts along the eastern side of the saddle earthworks" - a massive cut through a hill that forms one of the most significant parts of the road.
"Photographic evidence indicates that the crack is opening up and allowing water to infiltrate into the sublayer," the report said.
It warned this could be "serious as the underlying material is fault crush and is very susceptible to water".
"There is a risk the cut bench could fall and collapse onto workers below, or later, when the road is open, onto the public."
When the report was handed over, road builder CPB-HEB was still to answer further questions about whether concerns on that part of the road had been adequately resolved. Stantec was concerned that only a small section of the crack had been stabilised and recommended further monitoring of that part of the road.
"This cut consists of highly disturbed material due to the presence of the Ohariu fault zone nearby," the report warned.
Another issue, identified in January 2019, was that "mesh reinforcement" had been proposed in parts of the road. However, use of this reinforcement is deemed non-compliant in New Zealand, and could raise seismic concerns.
The report said discussions were under way to determine the ramifications of the use of this type of reinforcement, particularly on the seismic performance of structures that might have it. The report noted it might be in a number of bridges on the road.
An additional note, added later, warned that the extent of the problem might be worse, with that sort of reinforcement being potentially project wide.
As of November, the issue was unresolved.
Red-level fears that raw material shortages and difficulties in getting labour would delay the project were raised as early as 2018.
An "amber" grade problem was that parts of the road had been laid improperly so water had seeped into parts of the road where it should not be, and that layers of the road had separated.
Stantec wrote that if this were not remediated before the road opened to traffic, potholes would likely develop. Indeed, the builder had already been required to remediate a "large pothole" that was threatening to form.
The report noted an inspection of the road on October 5 last year found "a number of potholes" on the northbound section of the road.
The reviewer found parts of the road had bonded so badly they "could easily be removed with the heel of your boot".
The report said that 38 culverts on the road were supposed to allow fish to navigate the environment disrupted by the road.
However the inspector found that only a "few" of the culverts actually complied with the design.
Fish passage works could be completed after the road opens but allowing them to get through is part of the consent requirement and, as of November, "it is considered that this condition has not been complied with".
The report also noted that as the road neared completion "a lack of concentration" seem to be growing among the team, as the number of health and safety incidents increased. There were eleven incidents in November, up from five in October, and eight in September.
"I would expect this to be decreasing as less work is being carried out," the reviewer said.
The road is not finished and not open to the public.
Transmission Gully is a Public-Private Partnership being built and later, run, by private companies for Waka Kotahi.
A different company is building it than will later run and maintain it. The opening of the road is contingent on the contractor, Wellington Gateway Partnership, and its subcontractor CPB-HEB meeting "all contractually agreed safety and quality assurance tests".
Assessing whether those goals have been met is the responsibility of an independent reviewer.
There is tension between the firms building the road, and the firm that will later run it and be responsible for its maintenance over whether some tasks can be completed after the road has opened.
A spokesman for Waka Kotahi said that "57 out of 100 final safety and quality assurance test submissions had been received from CPB-HEB, of which 45 have now been accepted by the independent reviewer as meeting the required standards".
The road also needs to meet all its consent tasks, which is determined by the Greater Wellington Regional Council. As of February 11, all of those tasks had been submitted to the council.
Last year, the Herald revealed two other reports from Stantec. These showed concerns with "flushing" - a phenomenon caused by bitumen seeping up through a layer of chipseal on top of it, causing the road to be slipperier than it would otherwise be, and compromising its safety.
They allege the Crown ignored Treaty obligations by not engaging with them.