Chem­i­cal kill-off

Kapi-Mana News - - NEWS - By AN­DREA O’NEIL

Il­le­gal drugs cause harm in many ways, in­clud­ing killing Porirua’s sewage treat­ment plant two years ago.

In 2011 chem­i­cals from a Tawa P lab were dumped into the sewage sys­tem about the time of a po­lice raid, says Peter Bai­ley, Porirua City Coun­cil’s gen­eral man­ager of as­set man­age­ment and op­er­a­tions.

The chem­i­cals ended up in the coun­cil’s Ti­tahi Bay sewage treat­ment plant, where they killed much of the ben­e­fi­cial bac­te­ria that breaks sewage down.

‘‘It’s like us­ing Roundup on your vege garden, in a way.’’

As a re­sult, both the harm­ful chem­i­cal and un­treated sewage flowed into the sea, Mr Bai­ley says.

There was no way to con­tain the un­treated sewage. ‘‘The vol­ume is so great there’s noth­ing we can do. It would be a mas­sive job to store it in hold­ing tanks.’’

The plant treats all of Porirua’s sewage and much of north Welling­ton’s, ser­vic­ing 70,000 peo­ple in all.

Its size works in its favour when il­le­gal chem­i­cals are dumped – the huge vol­ume of water flow­ing through the plant di­lutes the chem­i­cals, mak­ing them less harm­ful both to the ocean and to waste plant staff, Mr Bai­ley says.

Smaller cities are not so lucky and un­wanted chem­i­cal buildup in small plants can cause ex­plo­sions.

The P lab in­ci­dent was the third chem­i­cal kill-off in a decade, but usu­ally the cul­prit is a busi­ness il­le­gally dump­ing in­dus­trial chem­i­cals into the sys­tem.

Firms can legally dump chem­i­cals in Seav­iew, Lower Hutt, but there is a steep fee to do so, Mr Bai­ley says.

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