The contaminated site consultancy

Kopeopeo Canal Remediation Project

Kopeopeo Canal Remediation Project

The $21.3M project involved removing dioxin-contaminated sediment from a 5.1 km reach of the Kopeopeo Canal, in the Rangitaiki Plains west of Whakatane, eastern Bay of Plenty. Tuna (eel) living in the canal accumulated hazardous levels of dioxins, preventing local iwi Ngati Awa from making use of their highly prized traditional food source. Moreover, the contamination prevented regular canal maintenance dredging being carried out, threatening the regional flood management network and risking discharge of contamination onto surrounding farmland in a major flood. The sediment was safely removed into two containment cells, where it is securely contained while being bioremediated. A detailed description of the project can be found here on the Bay of Plenty Regional Council's website.

Remediation challenges on a sacred mountain

A helicopter delivers equipment to a high-altitude remediation site on Mount Ruapehu
The Whakapapa and Turoa skifields on Mount Ruapehu are set in very sensitive environments; they are located within Tongariro National Park, a UNESCO dual World Heritage Area, taonga tapu to Ngati Tuwharetoa and Ngati Rangi. They are the headwaters for streams providing a variety of ecosystem services.

There are many fuel storage sites within the ski field boundaries that are used to provide fuel for ski field plant and machinery. During 2013 an aboveground storage tank leaked diesel into a tributary of the Makotuku River and subsequently contaminated the Raetihi township drinking water supply. Subsequent investigations revealed a number of legacy issues involving fuel spillage; and more recently, an electrical transformer was damaged by an avalanche, resulting in an oil leak. Remediating these sites posed some interesting issues. Disturbance to fragile alpine flora and fauna must be minimised. For cultural reasons, soil must remain on the mountain, and any soil treatment must be by natural methods.

Moreover, the skifields are very challenging environments to work in; high-altitude, volcanically active, exposed sites, subject to sudden changes of weather and snow-covered for much of the year. On the upper mountain, anything that cannot readily be carried up, must be flown in by helicopter. This is a high-risk activity, as is working in lahar paths. More prosaically there are ever-present health and safety risks from exposure, slips, trips and falls.

HAIL Environmental has been working with the skifield operator to excavate hydrocarbon-impacted soils, move them down the mountain, and remediate them by enhanced natural degradation. For the transformer spillage, soil was heli-lifted out in one-tonne pods; in another case, for a snow-cat refuelling area, soil was hauled down to a purpose-built cell at a site on the skifield access road. Soils are amended with fertiliser, wetted and actively aerated through an extraction system, which provides an opportunity to track biological activity via CO2 monitoring. Soil analysis has shown substantial decreases in hydrocarbon concentrations, especially the lighter molecular weight fractions. As acceptable levels are reached, the soil is reused as fill in skifield works.

Central Otago – Assessment of health risks associated with naturally occurring arsenic

mount rosa1HAIL Environmental has joined forces with e3Scientific to tackle an Otago developer’s unwelcome surprise. Soil testing across the 30-lot lifestyle subdivision revealed arsenic levels were consistently above the national Soil Contaminant Standard – even though there was no visible manmade source. The arsenic turned out to be natural. “Natural arsenic minerals are occasionally found across Otago,” explained local consultant Glenn Davis, “They’re part of the same process that gave the region its gold – they’re part of our history, really.”

He obtained specialist support from HAIL Environmental, to find out whether the problem was as much as it seemed. “Arsenic from a natural source may be effectively locked up in mineral grains – we then say it has low ‘bioavailability’” said heavy metal expert Dr. Dave Bull. “We run the soil through a complex suite of laboratory tests to work out what’s going on geochemically. The key test mimics conditions in the human stomach. With this information we can calculate bioavailability and assess whether the land’s fit for purpose or whether some form of management will be needed.” This subdivision will be only the second site in New Zealand where this cutting-edge approach is applied – but we are sure it won’t be the last.

mount rosa2Do you have arsenic contamination on your land?
Contact Dave on 021 036 7764 to find out how we can help.




Hawke's Bay