DURHAM – Concrete used in the construction of wind turbines won’t cause environmental damage or affect drinking water quality, according to experts testifying on behalf of Ministry of Environment and NextEra Energy Canada during an Environmental Review Tribunal hearing.
“We’re just not seeing that at all. There is concrete throughout our environment; concrete is breaking down throughout the world, we’re not seeing any impacts whatsoever,” said Bruce Harman, regional hydrogeologist and groundwater expert with the MOE during hearings last week.
Harman said according to a 10-year-old MOE database more than 38,000 decommissioned wells in Ontario have concrete well casings.
Materials contained in the cement in the wind turbine bases are bound up with the other ingredients and there is no evidence that they leach out as alleged by Leonard Van Den Bosch.
Van Den Bosch has appealed the Ministry of Environment’s Jan. 20 approval of the East Durham Wind project. He claims toxic chemicals in the concrete bases of three of the 14 wind turbines to be located near his home will leach into the groundwater sources that feed the nearby Saugeen River near his home in the former Glenelg Township.
His appeal also alleges that the same chemicals, along with construction and operation of some of the turbines, will harm the Redside Dace, an endangered fish species found in streams that cross his property just a few hundred metres from three of the turbines.
Harman noted that tests Van Den Bosch had conducted on his property show that the aquifer Van Den Bosch relies on for his drinking water is more than 100 feet below the surface and is not connected to surface water or the shallow groundwater layer near the surface. The aquifer is separated from the surface by 50 feet of highly impermeable clay.
“It is actually isolated from any issues that go on from above,” Harman said.
Dan Bunner, a hydrogeologist with expertise in the movement of and mediation of contaminants in the environment, testified that he’s seen projects much larger than a concrete wind turbine base made of concrete and he’s not heard or seen reports of contaminants leaching from these structures into the water table.
He too noted that concrete is used in construction of drinking water facilities, dams, bridges, and fish holding tanks without adverse environmental effects.
He gave the example of the fish hatchery near Chatsworth with 34 concrete tanks used to raise fish.
“There are no massive death of fish at (concrete) fish ladders,” Bunner said “It’s just not an issue.”
He said concrete has been used for centuries to build structuress over aquifers without contaminating the water table below.
Van Den Bosch alleged that toxic materials could enter cement during the process of making it.
Bunner noted the only chemicals that he knows of that might be added to the basic concrete mixture of sand, crushed rock, Portland cement and water are traces of calcium, alumina, iron and silica contained in the cement mixture to help strengthen the concrete and decrease permeability.
Bunner said manufacturers were denied a request to use alternative materials including tires and pulp and paper byproduct.
Bunner said as concrete ages it increases in strength and decreases in permeability. He cautioned against confusing permeability and being porous. Concrete may be porous but not permeable.
And even if something were to leach out in very small quantities during the decommissioning of the turbines, it would diffuse in all directions and if it passes through soil it would adhere to clay particles.
Bunner assured Van Den Bosch that construction companies have strict procedures to follow when washing out the left over concrete from the quick mix cement trucks after pouring wind turbine foundation so that the wash doesn’t damage the environment or spill into nearby streams.
He described a process that involves the wash water and residual cement being poured into a container, letting the concrete dry for a few days and then disposing of it off site.
The hearing was adjourned until May 5 when it will resume to hear evidence from experts regarding the concern raised by Van Den Bosch over effects of the wind turbines on the Redside Dace found in streams on his property.
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