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Mapua Contaminated Site, New Zealand Kayleigh Cradock Andrew Pickup Chris Thompson.

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Presentation on theme: "Mapua Contaminated Site, New Zealand Kayleigh Cradock Andrew Pickup Chris Thompson."— Presentation transcript:

1 Mapua Contaminated Site, New Zealand Kayleigh Cradock Andrew Pickup Chris Thompson

2 Site Description and History  Previously New Zealand’s worst contaminated site

3 Site Description and History  Previously New Zealand’s worst contaminated site  Decades of pesticide pollution by the Fruitgrowers Chemical Company (FCC)

4 Site Description and History  Previously New Zealand’s worst contaminated site  Decades of pesticide pollution by the Fruitgrowers Chemical Company (FCC)  FCC opened factory in 1932, manufacture of organochloride pesticides began in 1945  During this time, houses developed to south of site and commercial properties developed to the north.

5 Site Description and History  Previously New Zealand’s worst contaminated site  Decades of pesticide pollution by the Fruitgrowers Chemical Company (FCC)  FCC opened factory in 1932, manufacture of organochloride pesticides began in 1945  During this time, houses developed to south of site and commercial properties developed to the north.  FCC ceased operations in 1988 and by 1996 most of the site was owned by Tasman District Council

6 Site Description and History  Early 1990’s onwards, site subject to a number of environmental assessments.  Remediation or management required.

7 Site Description and History  Early 1990’s onwards, site subject to a number of environmental assessments.  Remediation or management required.  Major contaminants of concern: ORGANOCHLORINE PESTICIDES

8 Site Description and History  Early 1990’s onwards, site subject to a number of environmental assessments.  Remediation or management required.  Major contaminants of concern: ORGANOCHLORINE PESTICIDES Heavy metals

9 Site Description and History  Early 1990’s onwards, site subject to a number of environmental assessments.  Remediation or management required.  Major contaminants of concern: ORGANOCHLORINE PESTICIDES Heavy metals Other pesticides

10 Site Description and History  Early 1990’s onwards, site subject to a number of environmental assessments.  Remediation or management required.  Major contaminants of concern: ORGANOCHLORINE PESTICIDES Heavy metals Other pesticides Herbicides

11 Site Remediation  October early 2008  9 sections site and foreshore  3D “jigsaw” of excavation 65,000m individual cells

12 On-site Soil Treatment  Pre-treatment soil drying  Mechano-Chemical Dehalogenation (MCD) Base metal reagent → Chlorine ‘stripping’ Vibratory ball-mill 15mins at o C  Soil Acceptance Criteria (SAC)

13 Difficulties in Remediation  Large scale  Uneven contaminant spread  Discoveries of buried chemicals  Inexperience, untried technologies Greater risk No policies/ regulations  Unknown effects to groundwater  Residential area at risk to exposure

14 Impacts of Treatment  Poor management and control of process Secondary contamination of copper, mercury  Improper disposal of cleaning reagents and by-products Pollution of water courses  Excessive soil drying Organochlorine converted to harmful dioxins Released to air due to inadequate emission filtration

15 Alternative Solution (1)  Containment of contaminated ground Clay capping and subterranean bund wall  Advantages Cheaper than soil treatment Often safer as contaminants not disturbed → no risk of release  Disadvantages Prevents any further use of site → open space, commercial or residential Groundwater flow and tidal movement interactions causing contamination of the foreshore and marine areas

16 Alternative Solution (2)  Off-site soil treatment  Advantages No need to install own treatment plant → cheaper Any mistakes in processing impact on the facility not the land targeted for improvement  Disadvantages Residential area at greater risk of exposure due to excessive disturbance Continual “trucking” of large quantities of material causes residential/traffic disturbance

17 Any Questions? Thank you for listening


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