Treat­ment plant be­ing ex­panded


About 15,000 cu­bic me­tres of con­crete, 80 kilo­me­tres of ca­bles, and more than 200 work­ers a day.

Those are some of the fig­ures go­ing into a $141 mil­lion ex­pan­sion of the bi­o­log­i­cal nu­tri­ent re­moval fa­cil­ity at Water­care’s Man­gere waste­water treat­ment plant.

The en­larged fa­cil­ity uses bac­te­ria to re­move ni­tro­gen from the waste­water stream.

It will in­crease Man­gere’s bi­o­log­i­cal nu­tri­ent re­moval ca­pac­ity as Auck­land’s pop­u­la­tion grows by an es­ti­mated one mil­lion peo­ple over the next 30 years.

Project man­ager Sven Har­los is over­see­ing the de­sign and con­struc­tion. He says earth­works be­gan at the site in late 2013 and the project is ex­pected to be com­pleted by the end of 2017.

The project in­cludes con­struc­tion of a new four-stage treat­ment re­ac­tor, two new 52 me­tre di­ame­tre clar­i­fiers and as­so­ci­ated pump sta­tions, and pipes and blower fa­cil­i­ties.

Har­los says the fo­cus now is on in­stalling about 80 kilo­me­tres of data and power ca­bles.

‘‘Con­struc­tion ac­tiv­ity will ta­per off in Septem­ber and then comm- is­sion­ing will be­gin. That will be fol­lowed by per­for­mance test­ing.’’

The in­creased ca­pac­ity means the treat­ment plant can bet­ter man­age large vol­umes of di­luted waste­water caused by heavy rain­fall.

Har­los says the ex­ten­sion will in­crease its bi­o­log­i­cal treat­ment ca­pac­ity from nine to 11 cu­bic me­tres per sec­ond.

‘‘It helps to pro­tect wa­ter qual­ity in the [Manukau] har­bour and gives us much bet­ter treat­ment qual­ity. The ex­ten­sion will be com­pleted in about two months’ time. We’re putting in the fi­nal ca­bles.’’

Water­care says the pub­lic is also ben­e­fit­ting from the project through cre­ation of a new path­way be­tween its pop­u­lar Coastal Walk­way and Green­wood Road Park.

The or­gan­i­sa­tion car­ried out ex­ten­sive plant­ing in the area as part of coastal restora­tion work.

More land­scap­ing and plant­ing of 100,000 na­tive plants was done to shield the fa­cil­ity, which is south of the ex­ist­ing treat­ment plant.

The Man­gere waste­water treat­ment plant uses a three-step process that in­volves me­chan­i­cal, bi­o­log­i­cal and fil­tra­tion and ul­tra­vi­o­let ra­di­a­tion meth­ods to treat waste­water be­fore it’s dis­charged into the Manukau Har­bour.

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