Stream Clean-Up in Pipeline

By WOODD, Richard

WORK on an $8.5 million pipeline to rescue the Mangawhero Stream from wastewater pollution starts on September 1.

The pipeline will transport Eltham effluent 22km to Hawera and has a target completion date of next June.

Currently the Eltham wastewater treatment plant discharges into the Mangawhero Stream. The plant is overloaded by industrial waste from three factories, which are paying nearly half the project costs. It is said to be the last Taranaki stream subjected to such pollution. New Plymouth companies have won the main contracts issued by the South Taranaki District Council.

The pipeline contract has gone to Hurlstone Earthmoving at a price of $2.3 million.

Whittaker Civil Engineering secured the Hawera and Eltham wastewater treatment plant upgrades ($1.080 million) and the Hawera pumping station upgrade ($570,000). The latter has already been started and both are due for completion by December.

The total cost of the project, including internal, design, supervision, and works already done, is $8.465 million.

This is being shared by the STDC (51%) and three Eltham "wet" export industries (49%): The two Fonterra cheese factories at Bridge and Collingwood streets and Renco NZ, on London St. The same apportionment will apply to ongoing operational costs.

The industries’ costs include $1 million on pre-treatment to remove fats and solids from the waste stream.

The parties have an agreement that runs to 2015 before any cost review.

The Riverlands meat processing works is not involved: It has its own treatment plant and discharges its residual wastewater by irrigation.

Viv Eyberg, project manager for the STDC, says the pipeline timetable is fairly tight in order to meet a Taranaki Regional Council consent deadline of July, "but Hurlstones plan to do it with one team. If they run into unexpected difficulties with terrain, geology or weather delays, they are prepared to bring in a second team."

The line will comprise 200mm plastic pipe. It will follow public road reserves for most of the route, so very little easements or land purchases are required. The route from Eltham is: Mountain Rd (SH3), bypasses Normanby on Ngarongo Rd, rejoins SH3 at Ohangai Rd (Normanby south), travels along Waihi Rd into Hawera and joins the existing western trunk sewer at Maire St, which heads out to Whareroa and ultimately discharges through the Fonterra ocean outfall.

The pipeline life is 75 years and on current population growth projections, there should be no capacity problems over that time, says Mr Eyberg.

* WORK has started on a new 100mm pipeline to carry wastewater from the Silver Fern Farms (ex-PPCS) Hawera meat works to the Whareroa treatment plant, along with some residential effluent. Currently the meat works discharges to the town’s western trunk sewer. This will take pressure off the sewer and free up capacity for the Eltham flow.

Because two-thirds of this 4.5km line goes through the urban area (Tawhiti Rd, Collins St, Fairfield Rd), the successful tenderer, Downer EDI Works, convinced the STDC to support longitudinal road under-boring rather than open cut.

"Under-boring, while more costly, is less disruptive to householders and road users, and less messy," company manager Richard Moody said.

"It will require access shafts every 100-150 metres but there will be significant savings on pavement reinstatement works."

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