The executive director of the Thirty Meter Telescope said Monday that the TMT International Observatory board is closing in on the execution of a backup agreement to allow construction of the $1.4 billion project on a mountain in the Canary Islands.

Ed Stone, a physics professor at the California Institute of Technology, said the agreement would allow the cutting-edge telescope to go forward if permission cannot be obtained to build on Mauna Kea by the spring of 2018.

Stung by delays to its planned construction start in 2015, the TMT board in February set the 2018 timeline and vowed to find a backup site. They found it in October, choosing the Observatorio del Roque de los Muchachos site on La Palma island. (The Canary Islands are a Spanish archipelago off the northwest coast of Africa.)

Stone testified in Hilo on Monday at the replay of the contested case hearing for the project’s conservation district use permit.

In December 2015 the state Supreme Court ruled that the state Board of Land and Natural Resources failed to follow the correct procedure and should have held the hearing before voting to grant the permit. It ordered the board to hold a new contested case hearing.

Testimony in the current hearing is scheduled to continue into January.

Hearings officer Riki May Amano on Friday denied a request by TMT foes to put the hearing on hold in response to a new ruling on the project’s sublease.

Circuit Judge Greg Nakamura ruled Thursday that the BLNR should have held a contested case hearing before it consented to a sublease between the University of Hawaii at Hilo and the TMT.

The ruling, issued orally Thursday, left many wondering what effect, if any, it will have on the case or the project’s timeline.

In an interview after his testimony, Stone said TMT officials aren’t sure what Nakamura’s ruling means, either. He said they would have to analyze the written order once it is issued.

In any case, he said, the board remains committed to a construction schedule that would begin by April 2018.

Stone added that completing the negotiations for the backup site is only a couple of months away and that he sees no obstacle to getting that accomplished.

“We won’t exercise our option (on the Canary Islands site) until a decision is made,” he said. “The board still feels Hawaii is the No. 1 choice, and we are making progress in the contested case.”

But there’s still one other issue that might trip up the deal. The Mauna Kea master lease held by UH is set to expire in 2033, but there have been no assurances that the lease for the 11,000-acre Mauna Kea Science Reserve at the summit will be renewed.

Stone said the TMT board knew about the expiration date when it applied for the permit the first time. He said officials knew the risk and were hoping an extension could be negotiated to allow the TMT to operate over its expected 50-year lifetime.

With the issue still hanging, the board will have to take another look at that question, he said.

If construction begins in 2018, completion of the TMT enclosure and telescope structure would be expected in 2024, and initial operations would start three years later.

If the master lease isn’t extended, he said, that would give the TMT only six years to operate before the project — and all of the other observatories on Mauna Kea — would have to shut down.

“It’s up to the board if that’s an acceptable lease,” Stone said.

Project partners include government agencies of Canada, China, Japan and India, and the University of California and the California Institute of Technology.

In his testimony Monday, Stone said TMT’s members have spent more than $327 million and have agreements, budget and plans for funding of the construction phase. Already the government of Japan has initiated procurement of telescope mirror blanks in Japan, he said.

Stone testified that the project, if it is built in Hawaii, is committed to decommissioning and dismantling the observatory whenever it has to. He said the site will be restored as required by the Mauna Kea Comprehensive Management Plan.

Stone said the TMT will be a “much more advanced and powerful ground-based observatory than currently exists, one that will enable discoveries about the nature and origins of the physical world, from the first formation of galaxies in the distant past and remote regions of the universe to the formation of planets and planetary systems today in our Milky Way galaxy.”