It is the latest in a $4 million series of infrastructure and road safety projects being undertaken in the Constable Street area.
A 300mm-diameter stormwater main running under private properties between Hiropi and Owen streets is to be shut down and replaced by a much larger 750mm main that will be laid along Hiropi Street and then down Constable Street.
Wellington City Council Infrastructure Planning Manager Maria Archer says the work is needed because the existing 119-year-old stormwater main is too small to deal with water flows in heavy rainstorms.
"The pipe drains a catchment leading up the hill to Coromandel Street and runs through a natural 'dip' in Hiropi Street. In recent years the properties in the low-lying area have suffered substantial surface flooding when the main has overflowed," says Maria.
"Our plan is to instead dig a deep trench along Hiropi Street and then down Constable Street to the Owen Street intersection so we can link the new and bigger pipe to the Constable Street stormwater main."
The Constable Street trench will also accommodate a section of upgraded sewer main.
The work will mean further disruption for residents and businesses in Constable Street - which has been the subject of major infrastructure upgrade work over the past year.
"We apologise for the inconvenience to people living and working in the area, but the work is in a good cause," says Maria. "A lot of the infrastructure in Newtown is old and so we're getting on with the job of upgrading and replacing it as part of the City Council's ongoing asset management programme.
"At the same time we're investing in traffic lights and other infrastructure to make Constable Street - one of the city's busiest - safer for motorists and pedestrians and to give local people a better chance of getting in and out of the side streets."
Council infrastructure work completed, underway and planned in the area (totalling $4.1 million) includes:
- Installation of new traffic signals at the Constable Street intersections with Daniell, Owen and Coromandel streets as part of the local SaferRoads project - $620,000
- Installation of new speed humps and other 'traffic-calming' infrastructure works in local side streets as part of the SaferRoads project - $400,000
- Upgrade of the water main, stormwater and sewer mains running up Constable Street from Riddiford Street to Coromandel Street - $1.3 million
- Repair of an existing 150mm sewer main running under private properties between Hiropi Street and Owen Street. Cast-in-place-pipe methodology will be used to avoid the need for trenching - $90,000
- Upgrade of the water main from Wellington Road and Crawford Road to Coromandel Street - $1.5 million
- Upgrade of the water main running down from the Carmichael Reservoir in the Town Belt to Coromandel Street - $90,000
- A complete resealing of Constable Street in the next financial year.
Maria says Council contractors who have to dig trenches in Constable Street face a big challenge - a thick slab of reinforced-concrete that runs all the way up the middle of the roadway, but which is hidden under the surface.
The concrete dates back to the days (1904 - 1961) when trams ran up and down the centre of Constable Street - the slab was used as a secure base for the steel tramlines.
While it is frustrating for contractors, who have to cut and hammer their way through the concrete, Maria says it would cost an enormous sum of money and an enormous amount of time and disruption to permanently remove all of the concrete. "And it actually serves as a very stable road base - so it's best left alone."
The Hiropi-Constable street project has been contracted to Levin Bobcats Ltd. The hours of work will be 9.00am - 4.00pm weekdays - with two both traffic lanes open at all times.