British Columbia Premier John Horgan says technical challenges developing on the slopes of the Site C dam construction site could tip the balance against completing the province's partially-built megaproject.

"The new revelations about more geotechnical problems make it increasingly difficult to look at this project as one that will be in the best interests of British Columbia," the premier told reporters at the B.C. NDP's convention on Saturday.

The NDP ordered a regulatory review of the project — nearly $2-billion has already been spent on its construction — shortly after it formed a minority government in July. That review by the B.C. Utilities Commission, the province's independent utilities regulator, was completed on Nov. 1. In its final report, the BCUC concluded Site C is already over budget and will cost at least $10-billion to complete. Initial estimates indicated that the project would cost around $8-billion. The regulator also raised doubts in its report about whether the power generated by the dam will be needed.

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But Mr. Horgan said those financial matters are not the only consideration as he and his cabinet are weighing in their decision to either complete or terminate the project – consultations with Indigenous communities will begin next week.

The project began under the former BC Liberal government and then-premier Christy Clark, who vowed to get the project "past the point of no return" before the election.

Mr. Horgan said his cabinet will also consider the construction delays that have been caused by geotechnical challenges — specifically, two tension cracks that have developed on the north side of the riverbank where the dam is being built.

A leading critic of the project, Arthur Hadland, released a photograph on Saturday that he said shows a new, third, tension crack has recently opened up. A BC Hydro spokesperson said Saturday there are no new tension cracks on the north bank. The points referenced by Mr. Hadland as as new cracks are in fact access roads, spokesman David Conroy said, adding that there is "some localized erosion which is typical during excavation activities of this size and nature."

Officials in Mr. Horgan's office said the premier is seeking a briefing from BC Hydro to find out if there are new problems that have not yet been reported by the Crown corporation.

The premier has said his primary consideration in weighing the Site C project will be the impact it will have on BC Hydro's ratepayers.

Mr. Horgan said Saturday that "bad decisions" by the BC Liberals have already hurt BC Hydro's ratepayers. "Now they are not in government, and it falls to me to fix the mess they created. At the centre of that mess is a decision around how to proceed with Site C," he said.

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In his speech to delegates, the premier said the decision on the project will be "one of the toughest our government will make."

The BC NDP's influential labour allies are pressing for the government to continue with construction – albeit with new contracts that will ensure better terms for workers. But members of the party's strong environmental faction are deeply opposed to the project, as are some of the Treaty 8 First Nations in the region where the dam is being built. The hydroelectric dam would be built on the Peace River seven km southwest of Fort St. John in the province's northeast.

In early October, BC Hydro President Chris O'Riley revealed to the BCUC's review panel that the two tension cracks have already contributed to a $610-million cost-overrun. "BC Hydro has encountered some geotechnical and construction challenges on the project and the risk to the river diversion timeline has now materialized," he wrote in a letter to the commission.

In accompanying documents, BC Hydro explained those tension cracks "placed pressure" on the construction schedule, pushing back a key target to divert the river by one year.

The pressure to meet the deadline has triggered a battle between BC Hydro and one of its main contractors, a BC Hydro submission to the regulatory review stated: "The parties were unable to reach agreement on the schedule, options and allocation of cost. The parties are in dispute over the causes of the delays."

Some of the leading critics of the Site C dam have been independent power producers, who argued during the regulatory review that there are cheaper alternatives for additional electricity supply than building Site C.

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While in opposition, Mr. Horgan was a fierce critic of BC Hydro's contracts with independent power producers, and he continued on Saturday to rail against the cost of those deals. However, he said there is room for new private power production in B.C.

"We are going to have to figure out how we build new supply, using the private sector to be sure, but they have to be smart investments. Buying run-of-river power, for example, when we are rich in hydro power doesn't make as much sense as investing in wind or solar as complements to our hydro power."