The Thirty Meter Telescope, set to be placed atop Mauna Kea, has long been a controversial topic. Construction was supposed to begin this month, but as yet has not started. When complete, the telescope and it's supporting structure will span 1.4 acres, with another 5 acres being used for roadways leading to the site and parking spaces. It's possible that larger dormitory space made me needed as well.
An environmental impact statement was approved by the state of Hawaii in 2010, but the opposition group Mauna Kea Anaina Hou believes the statement is not accurate and more damage will be done to the environment than the statement covers.
Legal appeals are still pending in several lawsuits, however while the TMT group believes they are entitled to proceed until those matters are settled, the partners have decided not to take the risk and construction remains at a standstill.