...continued from Part 1
But Rigbey did say that ground motions from fracking operations could cause slight alterations to “weak bedrock” near the dams and that in turn could change the way that water naturally seeps through earth-filled dams. Ground motions could also knock some electrical control equipment offline, Rigbey added.
If either happened, BC Hydro would be faced with high repair and maintenance costs.
“Would it [fracking] bring the dam down? Not a hope. Would it do damage and cost me a lot of money? Absolutely. It would cost me a lot of time and a lot of money and that’s what I don’t want to occur,” Rigbey said.
Rigbey said that’s why BC Hydro has sought to exclude fracking from zones near the Bennett and Peace Canyon dams and around the construction zone of the Site C dam.
The current unwritten “understanding” between the OGC and BC Hydro is that no new tenures will be awarded to companies allowing them access to natural gas deposits in a zone within five kilometres of the three dam sites.
Companies already holding such rights will, however, be allowed to drill and frack for gas. In the event that happens, BC Hydro says it will work with the OGC “to effectively manage any risk.”
“This is a work in progress,” Rigbey said. “We are working toward strengthening the current understanding.”
Graham Currie, the Oil and Gas Commission’s executive director of corporate affairs, confirmed the five-kilometre buffer zones in an emailed response to questions. He said the buffer zone around Site C will “prevent the sale of oil and gas rights within the buffer area.”
Currie added that the proposed Site C dam falls within the Montney shale gas zone, one of the most actively drilled and fracked zones in the province.
“Site C falls within the Montney play and will be built to a high seismic safety standard,” Currie wrote. “During construction, permit conditions on a well in the Montney may be used to control the timing of hydraulic fracturing operations. All wells in the Montney are double-lined with cement and steel to a depth of 600 metres for further protection.”
The email does not mention that such protective measures do not prevent fracking-induced earthquakes. Cement casings, which are often imperfectly poured and prone to fail, are intended to prevent groundwater from being contaminated – a different issue.
The “understanding” between BC Hydro and the OGC applies only to the dams and not the lands around the reservoirs themselves, Currie said.
That includes lands around what could one day be the Site C reservoir, which could experience up to 4,000 landslides as the reservoir fills and after, according to a document prepared for BC Hydro. Whether fracking could further destabilize those lands, damaging the reservoir and dam itself, remains unknown.
What is known, however, is that earthquakes induced by fracking behave entirely differently than naturally occurring earthquakes.
Gail Atkinson is a professor in earth sciences and leading expert on the effects of induced earthquakes who holds the Industrial Chair in Hazards from Induced Seismicity at the University of Western Ontario. The chair is funded, in part, by TransAlta, a privately owned electricity provider in Alberta.
In response to written questions, Atkinson said most people would agree with the proposition that “precluding oil and gas activity such as fracking... within some radius of dams and reservoirs would prevent the possibility of induced seismicity that could damage such facilities.”
Atkinson said the big concern with earthquakes triggered by events such as fracking is that they occur much closer to the earth’s surface than natural earthquakes. A fracking-induced tremor might be as close to the surface as two kilometres, while a natural earthquake might occur 10 kilometres down.
The shaking caused by a fracking-induced earthquake may be short, but it is a stronger and different kind of shaking. The potentially “strong ground motions” generated by such shaking occur “closer to infrastructure on the surface.”
“The concern is that the potential for induced earthquakes to generate strong motions makes it difficult to satisfy the high safety requirements for critical infrastructure, if earthquakes can be induced by operations in very close proximity [to dams and reservoirs],” Atkinson said.
While there is “no consensus” about what constitutes a reasonable size for no-frack zones, buffer zones do make sense, Atkinson said.
“A zone of monitoring beyond the buffer zone is also a good precautionary measure in my view, as it would allow low-level induced seismicity from disposal or fracking beyond the buffer to be detected quickly and any necessary measures to be taken,” Atkinson said. “Enhanced monitoring would also provide valuable research data to improve our understanding of the issue.”
In a telephone interview, Hydro’s Rigbey said he agreed that both firm no-fracking buffer zones and wider special management zones made sense.
Atkinson’s thinking is consistent with TransAlta’s efforts to protect some of its hydro facilities in Alberta from fracking operations. Those efforts appear to have effectively shut down fracking in a buffer zone around one of TransAlta’s dams and the dam’s reservoir. Special operating guidelines are also in place beyond the buffer zones that can force companies to cease fracking.
But, as is the case in B.C., negotiations between TransAlta and Alberta’s energy industry regulator have happened behind closed doors.
Members of the public at direct risk should a catastrophic dam failure occur are kept in the dark when it comes to negotiations that could have a direct impact on their lives.http://thetyee.ca/Opinion/2016/08/16/Fracking-Threat-Peace-River-Dams/