Construction Contracts

Bees and fish and pipes

... a suburban tale

What do you get when you take an upmarket residential neighbourhood, an embassy, the odd bee and fish, and an old sewer pipe? For Lower Hutt’s Construction Contracts at least – a challenge!

2CONSTRUCTION EXCELLENCE AWARDS 2015 HIGHLY COMMENDED CATEGORY 2

PROJECT: Sewer & Stormwater Renewal, Wellington CONTRACTOR: Construction Contracts F or a number of years Wellington City Council had long known that the public sewer that serviced properties between Homewood Avenue and Nottingham Street in Karori required renovation. However, with many of the 1920s’ houses having been constructed over the public main, updating it would be no easy task.

Many solutions had been considered over the years, but none were given the green light; that is until Construction Contracts’ (CCL) proposal won the tender in late 2014.

David Howard of CCL says a realignment clear of all structures was designed and the opportunity was also taken to renew parts of the local stormwater system.

“This project involved renewing approximately 260 metres of 160 OD HDPE SDR 17 sewer pipe and some stormwater improvements. The value of the project was approximately $700,000,” he says.

Sounds easy enough, but with the work effectively having to take place in local residents’ yards (one of whom happened to be the Thai Embassy), strong project management and excellent stakeholder engagement skills were essential.

“A difficult project like this doesn’t get done by accident. It tested all of our technical skills in pipe laying, including pipe ramming, pipe bursting, directional drilling and open trenching,” says David.

“We held many individual meetings with residents, some of whom were staunch in their opposition to the project. We eventually managed to gain their confidence and negotiate suitable working arrangements to get the job done.”

By all accounts, CCL went above and beyond when it came to keeping everyone happy.

Some of the more notable stories around maintaining good relationships included monitoring the health of a resident’s pet fish in a fishpond during pipe ramming, calling bee keepers when a swarm descended near a property, and watering one of the resident’s plants while he was out of town.

Wherever possible, CCL also had a professional gardener remove plants and stored them so they could be reinstated later on. Where this wasn’t possible, it replaced them.

In addition to face-to-face meetings, CCL also used its company website to alert residents about project progress.

As for the build itself, David says one of the major risks for the project was the underpinning of the house and structure foundations at six different locations prior to installing pipe.

“This was done to prevent movement in the houses as we were to install the new HDPE pipe close to existing dwellings. The underpinning design was prepared by consulting engineers CHP,” explains David.

“The underpinning at 120 Karori Road, SSMH3, was the most technically difficult as support to existing retaining walls was needed. The pile was to a depth of 3.4 metres, in rock with no machine access.

“We had to hand excavate this pile which required hand tools to break rock and tested our manual handling skills.”

Other build innovations included pipe ramming short sections of earth and doing some DIY on the Smythe drilling head. A grinder was used to reshape it, so as to improve rock cutting.

All in all, not an easy job, but a satisfying one. And considering it was completed in 16 weeks, it proves CCL is the ‘go-to’ specialist for complex and unique drainage projects, especially if there are fish involved. l