Wellington Water announced without warning this afternoon that The Terrace from Salamanca Road to Ghuznee St has been closed, because of efforts to stop the CBD sewage spill.
And tonight, Vivian St will be also closing between Victoria Street and Marion Street. This will take effect until Friday 27 December, 8pm-8am each night to allow further investigation work.
The council-owned water company advised:
Southbound traffic should use Aotea Quay, Waterloo Quay, Jervois Quay, Cable Street, and right on to Kent Terrace as alternative routes during this time.
Due to the urgent works at Dixon Street, the following road closures are still in place:
-Willis St remains closed between Vivian St and Manners St
-Ghuznee St remains closed between The Terrace and Victoria St
Wellington.Scoop – December 21
Upper Willis Street between Manners and Vivian Streets remained closed today as Wellington Water continued trying to fix the sewage tunnel collapse  and the consequent sewage spillage into the harbour. Ghuznee Street also remained closed between Victoria Street and the Terrace. And tonight the NZTA said part of Vivian Street would be closed for 12 hours from 8pm, to allow “more investigation works.”
The closure of Vivian Street will be between Victoria St and Marion St and it will be for the next eight nights – 12 hours each night.
Earlier today Wellington Water, acting like a Transport Agency, advised:
Please expect significant delays through the CBD, particularly on Vivian Street. SH1 traffic should use Cambridge Tce, Wakefield St, Jervois Quay, Waterloo Quay and Aotea Quay as alternative routes during this time.
News from Wellington City Council – December 20
Urgent work to stop sewage overflowing into Wellington Harbour means upper Willis Street will be closed to through traffic from 3pm today until late tonight.
Willis Street will be closed between Vivian Street and Manners Street. Ghuznee Street will be closed between The Terrace and Victoria Street.
The closures are required so Wellington Water can install a temporary wastewater diversion at the intersection of Willis and Ghuznee streets. This requires urgent trenching work and installation of temporary pumps at the intersection.
Buses heading into the central city from Brooklyn will be diverted along Vivian Street and into Taranaki Street.
We urge motorists to avoid the Willis Street area as much as possible to avoid delays and congestion.
Local traffic will still be able to access properties in the Willis Street area.
A number of road closures in the city are currently causing queues out to the airport. If you're catching a flight this afternoon, please allow more time to get here. pic.twitter.com/d0wZZDNCEH 
— Wellington Airport (@WLGAirport) December 20, 2019