22 Environmental Geoscience; Geology and Health; Public Policy I: Environmental Health, Natural Hazard Assessment, and Environmental Remediation and Water Management (Posters)

THE ROTOITIPAKU WASTE DISPOSAL AREA, A NEW ZEALAND ENVIRONMENTAL, POLITICAL, AND CULTURAL MESS

Paper number: 22-23
Program: Technical Sessions
Time: 8:00 AM – 12:00 PM

Authors

Abstract

The Lake Rotoitipaku waste disposal area serves as one of New Zealand's most complex environmental waste sites. Located in Kawerau, Bay of Plenty, the site was originally a scenic lake, surrounded by sacred Maori land and thermal sinter terraces. In 1964, with the goals of increasing industry in the Bay of Plenty, an act of New Zealand Legislation (the Tasman Act) forced the original Maori landowners to either lease or sell the land to establish a waste disposal site for the newly created Tasman Pulp and Paper Mill. As a result Lake Rotoitipaku became the Tasman Pulp and Paper's general mill waste disposal area. Today the lake and thermal features are buried by more than 20 meters of waste.

Geologically, the unlined waste site overlies permeable unconsolidated sediment within a faulted and geothermally active basin. Hydro-geologically, the site is located between a productive spring and the Tarawera River, and overlies a high groundwater surface. The waste site is elevated approximately 30 meters above the Tarawera River which is 100 meters away and separated from the site by a constructed (non-engineered) embankment. In the 1980's the embankment failed three times sending solid waste into the Tarawera River. Initial analysis performed by environmental consultants indicates the site's groundwater has elevated values (exceeding national and international drinking standards) of dioxins, arsenic, zinc, boron, and manganese. Sediment samples exceeded international guideline for dioxins, mercury, and arsenic.

The Lake Rotoitipaku waste disposal area is set to close in 2013 when the lease expires and the land is returned to the original Maori trustees. To complement the previous work and aid in the preparation of the closure plan, our study will characterize the site geology and hydrology, identify geothermal and anthropogenic contaminant plumes, identify future contaminant migration pathways, and present mitigation and/or remediation options.