Mapua Contaminated Site,

New ZealandKayleigh Cradock

Andrew PickupChris Thompson

Site Description and History Previously New Zealand’s worst

contaminated site

Site Description and History Previously New Zealand’s worst

contaminated site Decades of pesticide pollution by

the Fruitgrowers Chemical Company (FCC)

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.

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

Site Description and History Early 1990’s onwards, site subject to a number of

environmental assessments. Remediation or management required.

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

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

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

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

Site Remediation October 2004-

early 2008 9 sections

site and foreshore

3D “jigsaw” of excavation 65,000m3

200+ individual cells

On-site Soil Treatment Pre-treatment soil

drying Mechano-Chemical

Dehalogenation (MCD) Base metal reagent →

Chlorine ‘stripping’ Vibratory ball-mill 15mins at 70-100oC

Soil Acceptance Criteria (SAC)

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

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

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

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

Any Questions?

Thank you for listening