A scarcity of high quality aggregate for road bases and building lots will probably ease in the coming weeks as soaked quarry operations dry out, said quarry operator Buddy Wood.
However, the continuing demand for land fill to meet development needs has the Department of Environment ready to test the environmental impact of deeper excavation of current quarries as a medium-term strategy, and to explore the feasibility of the commercial importation of aggregate as the long-term approach.
Deputy managing director of the National Road Authority Edward Howard noted recently that obtaining supplies of good land fill was a factor in estimating how far the $3 million budgeted for the extension of the Esterley Tibbetts Highway would take the road.
‘Fill is increasing in price and getting scarce,’ he said. ‘Everyone wants to build 10 feet above sea level because of Ivan.’
Mr. Wood, who said there was ample supply of rough fill, admitted that the high quality, finer aggregate known as crusher run was getting scarce.
‘(Crusher run) takes longer to make,’ he said, noting that when it is wet, as it has been in recent weeks, it is difficult to sift the fill.
‘Once it dries out, we should catch up,’ he said.
Mr. Wood said high quality crusher run can cost as much as $24 a cubic yard, while shot rock, a lower quality fill with larger chunks of rock, is running about $16 cubic yard right now.
Mr. Wood said there has definitely been increased demand since Hurricane Ivan as people try to raise the elevation of their property to avoid storm surge flooding.
‘I’d say (the demand) is 35 to 40 per cent higher,’ he said.
Stanley Scott of Scott’s Equipment, which operates another of Grand Cayman’s active quarries, thinks that figure could be even higher.
‘I would say demand is getting close to 50 per cent more since Ivan,’ he said. ‘It’s putting pressure on all the pits.’
Adding to the demand has been the large scale development Camana Bay, which has needed considerable land fill in its first phase.
While the immediate problem of a scarcity of good land fill might be alleviated with drier weather, organisations like the National Roads Authority, the Department of Environment and the Water Authority are all concerned about creating too many quarry sites on Grand Cayman.
Mr. Howard said most of Cayman’s quarries, including inactive ones, are in the Eastern districts, and that the large numbers of quarries will make it more difficult for the placement of future roads.
DoE assistant director Scott Slaybaugh is concerned about how much of Grand Cayman will be sacrificed to quarries.
‘We need to decrease the number of [quarry] footprints we create,’ he said.
Mr. Slaybaugh said an extensive study – called the CH2MHill report – about managing aggregate resources to meet development needs was completed in September of 2002.
While the report was comprehensive, it did not account for the increased demand caused by Hurricane Ivan, Mr. Slaybaugh said.
‘It’s a very professional study, but it was a bit short-sighted in that it didn’t expect the unexpected.’
It was estimated in the report that Grand Cayman had a demand of one million cubic yards of aggregate each year. That figure has gone up since Ivan.
Mr. Slaybaugh said there is about a seven million cubic yard reserve of aggregate on Grand Cayman.
The CH2MHill report recommended, among other things, a pilot study to determine the environmental impacts of excavated quarries deeper than the allowed 12 to 14 feet below the surface.
For a variety of reasons, that pilot study had been delayed for several years.
Late last year, the Aggregate Advisory Committee, a multi-agency governmental technical group, agreed to allow excavation of Cayman’s active quarries to a depth of 20 feet.
Mr. Slaybaugh said it is hoped a pilot study could commence the early part of next year excavating three half-acre plots on one quarry to 30, 40 and 50 feet below the surface to determine the environmental impacts.
Quarry owner Buddy Wood said he thinks the Government should have allowed deeper excavation a long time ago.
‘I’ve been saying that for years, but no one listened,’ he said. ‘It’s a good step. We can get more (aggregate) in a smaller area.’
Hendrik van Genderen, a water resources engineer with the Water Authority, a member of the AAC, said there are several reasons precautions have to be taken if quarries are to be excavated deeper.
One of the chief concerns is whether excavating quarries deeper could possibly bring an incursion of brackish into Grand Cayman’s fresh water lenses.
The Water Authority never supports having a quarry over a fresh water lens, but even if it is only near a fresh water lens, a quarry could have a negative impact, Mr. van Genderen said.
‘The lenses depend on rainfall that seeps through the rock,’ he said. ‘When you create a (quarry) lake, you have a high amount of evaporation, so the lens could start losing water.
Mr. van Genderen said the Water Authority generally knows where Cayman’s fresh water lenses are, but there is a margin of error because the exact location of the lenses can not be defined above the ground.
A quarry could also affect ground water levels on agricultural land, Mr van Genderen said.
Another potential concern about excavating quarries deeper is the odour.
‘The deeper you go, the more you are faced with a lack of oxygen,’ Mr. van Genderen said. ‘When waste gets into a lake and starts to rot, it smells bad.’
Even if the pilot study shows it is safe to excavate quarries somewhere between 30 and 50 feet deep, the CH2MHill report only recommended deeper quarries as the medium term strategy to supplying Grand Cayman’s aggregate needs.
For the long term, the report recommended developing the infrastructure to facilitate the large-scale importation of aggregate products.
To make it economically feasible to import aggregate, Grand Cayman would have to construct a permanent offloading dock removed from the George Town area that would accept large aggregate-hauling barges.
The CH2MHill report recommended a complete feasibility evaluation to be done for such a facility by 2004, and that the facility be functional between 2007 and 2012.
Mr. Slaybaugh said that study was never done; however, some private enterprises have expressed some interest in undertaking the project.
In the interim, Mr. Slaybaugh pointed out that there are other ways Grand Cayman can reduce its demand for aggregate.
‘We’re talking to the developers all the time,’ he said, noting that one way developers can reduce their needs for land fill is by only raising the level of the building foundation area, rather than the whole property, to promote water drainage.
The DoE also recommends erecting buildings of the ground on pilings.