The Cayman Islands Government will immediately begin collecting between 14,000 cubic yards and 18,000 cubic yards of arsenic-contaminated ash created by the burning of Hurricane Ivan debris, Cabinet Minister Arden McLean said on Friday.
The tainted ash, which will come from six debris-burning sites, will be taken to the George Town Landfill and put into a covered pit containing a polyurethane liner to prevent leaching into groundwater.
Mr. McLean said members of the Department of Environmental Health, Department of Environment and the Water Authority have studied the problem.
‘They have concluded, along with other scientists, that we need to act on (removing the ash from the burn sites) immediately,’ Mr. McLean said.
The situation poses no immediate health threat.
‘There’s no need for the public to panic,’ Mr. McLean said.
The process of removing the ash could cost millions, Leader of Government Business Kurt Tibbetts said.
The ash pit, which will take up approximately one acre of the landfill, is only a medium-term solution to the problem.
In the long term, Mr. McLean said government is exploring sealing the ash into a concrete structure.
‘It’s the easiest way to deal with it, but it’s also the most expensive way,’ he said. ‘We’re looking into other alternatives.’
Other solutions include mixing the ash with mulch and other debris materials and then using it as a daily cover at the landfill.
The ash could also be sifted of impurities and donated to cement plants, which use the material to make concrete.
Mr. McLean said the trucks used to haul the ash will be sealed to ensure the public is not put at risk.
The arsenic in the ash most likely came from the burning of what is called pressure-treated wood.
Chromated Copper Arsenate (CCA) was commonly used as a preservative for lumber produced in the United States until it was banned for residential use in January, 2004.
If burned, pressure-treated wood creates a toxic ash containing arsenic and chromium.
Arsenic is the more dangerous of the two metal elements because it is a known carcinogen.
Water Authority water resources engineer Hendrik van Genderen said tests showed all six hurricane debris-burning sites contained varying levels of arsenic.
Mr. van Genderen said, however, that the levels posed no immediate health risk.
Because other woods were also burned at the sites, arsenic levels were are not too concentrated.
‘The ash is not the worst of the worst. The risks of short-term exposure are negligible,’ he said.
‘Two, three or four years down the line, we would have a problem though. Long-term exposure can cause cancer.’
Mr. van Genderen explained that the Water Authority has a regulatory role, and is charged with the protection of groundwater.
Of particular concern at the burn sites is the possibility of rain leaching the arsenic into the groundwater.
With rainy season under way, the government had made the decision to act immediately on relocation of the ash.
‘I think this shows good governance,’ Mr. van Genderen said.
It is estimated the job will take two months to complete.
‘The good news is we tested the groundwater and, to date, we did not detect any arsenic,’ he said.
Mr. van Genderen was quick not to lay the blame for the burning of pressure-treated wood on MC Restoration, the company that eventually wrote the debris-processing contract.
‘MC Restoration was not responsible for all the burning,’ he said. ‘Some of the burning was by citizens and families, and in the case of the Spotts Newlands site, it appears to have happened spontaneously.’
Tom Moffitt of MC. Restoration said burning had taken place prior to his company’s arrival at five of the six sites.
As for the sixth site in Frank Sound, Mr. Moffitt said he does not know why arsenic levels were found there.
‘We didn’t burn any pressure-treated wood,’ he said.
Mr. Moffitt said MC Restoration took soil samplings at the Frank Sound site before burning, and found background levels of arsenic.
He said the natural arsenic levels were almost twice as high as what is found in the natural habitat in Florida.
Mr. van Genderen said the Water Authority conducted similar testing.
‘We have some samplings from soil sources and I can confirm there are low levels of arsenic in it,’ he said.
Mr. van Genderen said he did not know if the arsenic levels were naturally occurring or something caused by man.
Arsenic was commonly used in a variety of pesticides until the United States Environmental Protection Agency banned most inorganic arsenic pesticides in 1986.
Vegetation can absorb metals through root uptake.
Mr. van Genderen said wood chips from local trees were also tested to see if they contained arsenic, but no detectable amounts were found.
However, ash from local trees has not yet been tested for arsenic, Mr. van Genderen said.
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