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Published: 2006-04-18 00:00:00

The application by Higgins Contractors Ltd for an air discharge consent for a proposed asphalt manufacturing plant in Melville has been granted - but subject to an extensive set of conditions.

A Hearings Committee appointed by the Waikato Regional Council (Environment Waikato) has found that the impact of the proposed asphalt plant on air quality around Melville would be “no more than minor" – and that risks to human health would be “low”.

In reaching their decision, the committee found that: “The predicted peak off-site concentrations of the various contaminants are low when compared to the relevant air quality guidelines. The risk to human health as a result of the proposed discharge is therefore low.”

As part of their deliberations, the committee (comprising two independent commissioners, and one Environment Waikato councillor) made a visit to the vacant site, which is located approximately 550 metres south of State Highway 1 (Kahikatea Drive) along the alignment of Gallagher Drive, and on its western boundary abutting the main trunk rail line.

In reaching its decision, the committee found that the possible incremental additions to the ambient air in and around Melville from the applicant's plant were “at the lower end of significance.” The committee also found that:

  • There may be odour detectable beyond the site boundary at times. However, with reference to the guidance provided in the proposed Waikato Regional Plan, adverse effects due to “objectionable odour” are not likely.
  • Adverse effects on people’s amenity values due to dust are not likely, given the distance to neighbours - as long as good site management practices are adhered to.

The committee heard evidence that the largest contribution to PM10 emissions (small fine dust particles in the air) in Hamilton is domestic home heating – representing around 70% of the total winter emissions, with garden waste fires, motor vehicle emissions and industrial emissions making up the remainder. Industry is reported to contribute approximately four per cent of the winter emissions.

The committee noted that there were 137 submissions received, predominantly from residents of Melville, and that evidence was also heard from a number of technical experts.

After hearing the evidence, the committee found that “the contribution to particulate and odour effects in and around the Melville area occasioned by the operation of the proposed asphalt plant will be no more than minor.”

As regards the issue of the proposed asphalt plant’s potential for “tainting” the products produced in the nearby Dairy Goat Cooperative Ltd factory, the committee found little evidence to support this scenario.

Conditions imposed

In granting the consent for 15 years, the committee decided that further strengthening of some of the proposed conditions was also required. These include:

  • prohibiting the manufacture of cut-back asphalt
  • prohibiting the processing of recycled asphalt paving
  • requiring the use of carbon adsorbers to control the source of fugitive emissions
  • provide enhanced sensing of broken bags at the bag filter unit to prevent excessive emissions of particulate matter from the asphalt plant chimney.

In response to various evidence and submissions made to the committee about the scale of operation of the plant, and the related issue of the practicability of alternative asphalt manufacturing processes, the committee decided to require that the applicant keeps abreast of technological advances in asphalt manufacturing processes. Once the asphalt production rate exceeds 50,000 tonnes per year, a formal review of the technology will be required.

As a further practical measure to minimise nuisance effects on sensitive land uses, the committee has added a condition requiring Environment Waikato approval prior to construction of the plant and buildings of the layout of the site. The objective of this approval is to achieve maximum separation distances from nearby sensitive land users.