The number of consent breaches, failures/incidents, and unconsented activities at the troubled Transmission Gully site has ballooned to 223 incidents, with a further 44 still under investigation.
Greater Wellington Regional Council (GWRC), the regulator, says its resources have been stretched responding to the "significant" number of breaches.
The offences include sediment discharges into local streams, unapproved works, and slips.
The 27km Wellington road is now set to cost $1.25 billion after two massive bailouts.
It's due to finally open in September, more than a year after originally scheduled.
A review undertaken by Te Waihanga, the Infrastructure Commission, found the price of the road was set far too low to begin with, as well as what Infrastructure Minister Grant Robertson called "less than ideal consenting risk management".
GWRC regulatory records reveal the project's environmental performance has gone from bad to worse.
Over the first five years of the build there were 167 issues recorded, which one resource and environmental planning expert said was astonishing.
But in the past year since the Herald first revealed those figures the council has confirmed 56 additional incidents.
The four-lane motorway is being built through a public-private partnership (PPP), the Wellington Gateway Partnership (WGP), with CPB Contractors and HEB Construction sub-contracted to carry out the design and construction.
Between them, these parties and Waka Kotahi NZ Transport Agency have been slapped with $37,500 worth of fines over Transmission Gully to date.
They have been issued 50 infringement notices along with 41 formal warnings.
The CPB HEB JV has been the subject of the most infringement notices and warnings.
CPB has previously declined to comment on this issue and HEB has said it was contractually prohibited from commenting, referring any media queries to NZTA.
GWRC environment management general manager Al Cross said the council's regulatory approach was focused from the outset on educating and enabling teams to meet the condition of the consents, ahead of more traditional enforcement such as fines.
"However, it's our role to preserve the bottom lines of the integrity of the consenting process and get the consent holder to ensure the management of environmental impacts as set out in the conditions of their consent.
"Our graduated approach to regulation has progressively changed in response to significant numbers of breaches by the consent holder that resulted in one prosecution."
An internal team of three people are working on Transmission Gully as well as expert consultants, Cross said.
"Our resources have been stretched but we have appropriately reallocated resource as required throughout the duration of the project."
GWRC chairman Daran Ponter said Transmission Gully was a large project involving the movement of a lot of soil.
"The alliance has to work hard to ensure those movements don't result in sedimentation going into streams, rivers, and Porirua Harbour in particular.
"The regional council has been on the case but the measures that we have, the levers we have, are not sufficient enough to send a message to big projects like this.
The additional incidents at Transmission Gully have happened even after Waka Kotahi supported CPB HEB JV with additional training for staff, attendance at an environmental compliance workshop, and an increased on-site presence.
NZTA national infrastructure delivery manager Andrew Thackwray said environment inspections have been conducted weekly since environmental and site monitors were brought on board in September last year.
"Waka Kotahi is disappointed the level of environmental performance declined late last year, despite the additional assistance we have provided."
NZTA has reminded the partnership and the builder of their obligations to avoid, remedy, or mitigate potential adverse effects upon the environment, Thackwray said.
"The level of intervention by the Waka Kotahi team to lift the builder's performance is evidence of how seriously we take these matters, within the constraints of the PPP contract."
The fact incidents were reported did not necessarily mean there was a discharge and many were self-reported engineering issues and mitigated prior to rain or stormwater runoff, Thackwray said.
"Where there was a discharge, the builder's ecologist has confirmed that there has been little or no adverse environmental impacts as a result of these individual incidents."
Waka Kotahi has noticed an improvement in performance this month and will continue to closely monitor this on a weekly basis, he said.
A recent review of the Transmission Gully project, released last month, found consenting risk could have been better managed by all parties involved.
In fact, Transmission Gully's detailed business case only contained a one-page statement outlining the "consenting strategy".
Several interviewees confirmed the consenting strategy and designation for Transmission Gully was developed with a traditional non-PPP procurement in mind.
This is one of many examples in the review of the inevitable problems created by using a non-PPP scheme to procure a PPP project.
One interviewee said it became obvious in the early stages that the project parties were struggling to meet consent requirements.
They said local government regulators provided significant effort and resource to work alongside partners to address ongoing compliance and approvals performance issues.
These efforts failed and regulators were forced to resort to more traditional enforcement tools in an effort to encourage improved compliance performance.