Foes of the stalled Thirty Meter Telescope are appealing to Hawaii’s appellate court in hopes of overturning a lower court rejection of their argument that the project requires a substantial security bond before starting construction.

The Mauna Kea Hui’s lawsuit was dismissed in August by Hilo Circuit Judge Greg Nakamura, saying the performance bond issue was essentially litigated already during the project’s lengthy contested case hearing.

Mauna Kea Hui leader Kea­loha Pisciotta said the group decided to appeal, in part, because the issue was never “litigated” at the contested case hearing. Hearing officer Riki May Amano unilaterally dismissed the topic without allowing any arguments, she said.

The appeal, filed last month by Big Island attorney Gary Zamber for Pisciotta and others who have battled the TMT in court for years, asserts that the Mauna Kea Plan of 1977 requires every development to have a security bond in the amount of the full cost of the project.

The original claim sought an injunction and asked the court to rescind the project’s right to commence construction, arguing that the failure to post a bond would impose onerous financial liability on the people of Hawaii.

“The rules clearly state that a bond is required,” Pisciotta said Tuesday.

Pisciotta said the requirement is especially important because the TMT International Observatory (TIO) board doesn’t have all the funding it needs to finish the project, now estimated to cost $2.4 billion following more than five years of controversy, protest and delays.

TMT officials acknowledged before a National Academy of Sciences committee last week that they are hundreds of millions of dollars short of the money needed to pay for construction.

To help deal with that, the TMT’s international consortium has formed a partnership with another proposed mega-observatory, the Giant Magellan Telescope, which is planned for Chile, and together they are asking the National Science Foundation for $850 million for each project. The plan would guarantee American astronomers about a third of the viewing time on each of the landmark telescopes.

Pisciotta said a bond would also help to ensure that the land near Mauna Kea’s summit is returned to its original state if the project goes bankrupt during construction. Returning the land to its original state is a decommissioning requirement of TMT’s conservation district use permit.

When the lawsuit was originally filed, state Attorney General Clare Connors said the claim had no merit, and TMT attorney Douglas Ing bluntly described the claim as weak.

“Judge Nakamura quickly and summarily dismissed the hui’s complaint and claims based on TIO’s motion,” Ing said in a statement Tuesday.

In the contested case hearing’s findings of fact, Amano wrote that the 1977 Mauna Kea Plan was intended as a “conceptual” policy guide intended for review and updating over time.

“Circumstances change,” the findings said. “It was the first ‘master plan’ for Mauna Kea and consists of 17 pages. It has obviously been superseded by the much more detailed and extensive planning efforts that are described elsewhere in these findings of fact.”

A bond requirement is not in the latest iteration of the Mauna Kea Science Reserve Master Plan adopted in 2000.

The claim names as defendants Gov. David Ige, state Attorney General Clare Connors, state Land Board Chairwoman Suzanne Case and other members of the state Board of Land and Natural Resources, plus Hawaii County Mayor Harry Kim, University of Hawaii President David Lassner and the Thirty Meter Telescope International Observatory.