New Zealand Steel’s Environmental Management System places great importance on its commitment to minimise any effects of taking or discharging water, as well as controlling the use of water. In order to fulfill this commitment, the company employs a rigorous monitoring programme with regular reports to the Auckland Council, as well as the involvement of independent environmental consultants.
A rigorous monitoring programme has been established by the water quality and the receiving environment and includes:
Each day New Zealand Steel laboratory staff take samples of the wastewater before the discharge enters the Waiuku Estuary. The onsite laboratory tests these samples and the results are reviewed to ensure that discharges continue to comply with resource consent conditions. The results are reported to the Auckland Council each month, and the Community Environmental Committee four monthly.
That means at the Northside Outfall, for every 100 tonnes of water discharged from the steel mill a sample of water is abstracted into the day's sample container. After 24 hours, these samples are taken to the laboratory for analysis. The results are electronically transmitted to operations and environmental staff who compare the results with the conditions set by the resource consent.
On the northside and southside outfalls, the elements which are analysed in the laboratory and the frequency of sampling are listed below. These are specified in the resource consents held by New Zealand Steel.
In addition a continuous turbidity (clarity) meter operates on the separate ironsand dewatering plant discharge, where the only potential contaminants are clay minerals derived from the ironsand deposit.
Independent biological consultants sample in the mixing zone to ensure that marine life is not being adversely affected. Following a review of the substantial amount of data gathered from 1985 to 2003, which shows a continuous decline in metals, the ARC reduced the monitoring requirement to biannually from 2003.
The water quality standards set for the wastewater discharge to the Waiuku Estuary were derived following consideration of the potential for adverse effects on marine organisms and possible accumulation of metals in sediments within the mixing zone. Monitoring of metals in sediment and shellfish provides a sensitive indicator of the degree of contamination by metals in the marine ecosystem. The monitoring results for shellfish and sediments within the mixing zone are forwarded to the Auckland Council. The Council also conducts surveys in the Waiuku Estuary and wider Manukau Harbour.
Air quality monitoring equipment is stationed around the outskirts of the mill to measure the quantity of dust particles in the air. Samples are collected weekly for evaluation by the company's environmental staff and are compared with nationally accepted standards. The air emissions discharged via stacks are also monitored regularly. Sampling equipment is inserted inside the stack and a sample is taken to measure the volume of dust emitted from the stack, or hydrogen chloride levels in the case of the pickling line, where acid is used in the process.
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