from Probe International backgrounder
Canadian power company, Fortis Inc., is set to build a hydro dam in
Belize's Macal River Valley, an area with extensive bedrock fractures
and faults that could prove unstable, geologists warn.
"No responsible company would build a dam at this site without first
mapping it very carefully," says geologist Brian Holland, technical
director of Belize Minerals Limited.
Holland recently advised Belize authorities that the geological
assessment prepared by Montreal-based AMEC is wrong and should
not be used as a basis for the dam's design and construction. [see
Fortis, a Newfoundland-based billion-dollar corporation, started
clearing the dam site last month but AMEC's assessment -- funded by
the Canadian government -- is flawed, according to Holland. The
assessment, he says:
- wrongly identifies bedrock at the dam site as granite.
- fails to report geological faults and fractures in the project area, including the 30-kilometre long Comma Cairn Fault which is large enough to be visible from satellite images of Belize;
- fails to include a geological map of the area to be flooded by the dam,
an area known for its extensive network of limestone caverns that could drain water out of the dam's reservoir and render it useless.
Without an accurate geological assessment, Fortis can expect problems
and increased costs during the design and construction phases, according to Holland. A dam failure could flood residents downstream causing potentially life-threatening damage.
"The weight of the proposed 50-metre high dam could compress the
soft shales and potentially lead to structural damage or dam failure if
there is bedrock subsidence or seismic activity triggered. The implications of that, economically, environmentally, and with potential cost [to] human life in villages downstream, are immeasurable."
Last November, Holland and a second geologist were hired by Fortis
subsidiary, Belize Electricity Limited, to examine rock samples taken at
the dam site by AMEC's geotechnical consultants, Swiss Boring. No
granite was found in any of the samples so Holland recommended that
the geological maps and bedrock testing be redone before proceeding
with the dam's construction.
This isn't the first time AMEC has failed to accurately assess geological
conditions before constructing a dam in Belize, says Gráinne Ryder of
Probe International. AMEC's studies for the Mollejon dam, situated
downstream of the proposed Chalillo site, geological and hydrological studies failed to predict rains that nearly washed the dam away after torrential rains eroded the highly fractured bedrock under the dam and powerhouse. When outside engineers were brought in to repair the dam in 1995, they discovered that it had been lifted eight inches off its foundation and had to be completely re-anchored.
Holland finds AMEC's claim that the dam site is granite an "inconceivable" mistake, since geologists and mining companies have mapped the area since the 1950s and all maps indicate sandstones,
shales, and limestone.
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