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Mapua clean-up site validation report

Explanation of the Mapua clean-up site validation report

Report purpose

The Site Validation Report is an independent analysis of test results of the almost 2500 soil samples taken during the clean-up at the former Fruitgrowers Chemical Company (FCC) site at Mapua, near Nelson. The report indicates whether the clean-up met targets specified in the project's resource consents.

This report was prepared by consultants Sinclair Knight Merz Ltd (SKM) in accordance with guidelines for contaminated site clean-ups in New Zealand and Australia. The consultants analysed data from soil sampling undertaken by the Ministry for the Environment during the project.

Tasman District Council's resource consents required various areas of the site to be cleaned to specified standards, depending on their future use. For example, the minimum contamination allowed for marine sediments in the estuary was many times lower than the minimum for areas which will be used for housing or parks, and many, many times lower than the minimum for parts of the site which will have commercial buildings on them.

The Site Auditor has the key role of deciding whether the site is fit for its intended purposes. Along with reports of results from the monitoring of groundwater and sediments, the Site Auditor will use information in the Site Validation Report in drawing their overall conclusion. The Site Auditor will also decide what future monitoring or management is needed.

The report structure

The early sections of the 162-page report cover its objectives, historical and background information about the clean-up, remediation methodology, and explanations of sampling protocol.

The report then moves into analysis of sample data of the various categories of material type across the site - for example, residential material, marine sediments, and commercial material. This includes detailed graphs and maps.

At page 145, SKM's Discussion Summary begins, summing up the detailed findings.

Points to note from SKM's discussion summary

As mentioned, it is for the Site Auditor to conclude what the data in the report means for the future of the site, but SKM's report shows:

  • The FCC East commercial area has been remediated to the clean-up standard required.
  • The FCC Landfill has been remediated to the standard required for recreation.
  • The FCC West area mostly meets the residential standard, however there are several isolated contamination hotspots which the Site Auditor will need to address.
  • The soil samples for the neighbouring residential properties met the criteria, except for two of four boron samples taken on one property. Due to incorrect laboratory analysis, it cannot be determined whether these met the criteria. The Ministry has asked for these two samples to be re-tested.
  • As already publicly acknowledged by the Ministry for the Environment, the marine sediment area does not meet the resource consent standard, despite being re-excavated. The Site Auditor will give guidance on how this issue can be remedied.

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