Josh Miller/CNET

Google's mysterious barges were dismantled after being deemed a fire hazard, documents reveal.

The tech giant's floating showrooms, sent to the scrapheap in August this year, appeared in Portland, Maine, and in San Francisco a year ago. While little was known about the purpose of Google's 250-foot barges -- containing over 60 shipping containers to create four-story buildings -- the $4 million constructions captured the media's attention as invite-only showrooms for new Google products.

The company only admitted the barges were being explored as "an interactive space where people can learn about new technology." CNET was the first to make the connection between Google and the barges.

The buzz turned to confusion as the barges later sailed away, to be dismantled and sold for scrap.

It was originally thought that the reason for the disappearance of the barges was down to money -- the expensive construction and subsequent mooring. However, documents obtained under the Freedom of Information Act by the Wall Street Journal show otherwise.

The documents reveal that Google's contractor stopped the projects after the Coast Guard doggedly raised fire safety concerns which went unresolved. Robert Gauvin, the organization's acting chief of commercial vessel compliance, said in a March 2013 email: "These vessels will have over 5,000 gallons of fuel on the main deck and a substantial amount of combustible material on board."

Furthermore, a visiting Coast Guard inspector said in September 2013 that additional safety measures were needed in case "people are forced to jump overboard on the waterside (like a fire)."

The Coast Guard officials, who were required to sign nondisclosure agreements (NDAs), also raised questions about the safety of visitors with disabilities, and despite Google's assurances no more than 150 people would be on board at any time, the Coast Guard was not reassured.

Gauvin said in the March 2013 email that he was "unaware of any measures you [Google] plan to use to actually limit the number of passengers," and "while I understand there is a sense of urgency, I am concerned that significant work has already been performed without full consent of the Coast Guard."

The barges went under construction in 2011, and the tech giant originally considered using them as floating retail stores. In 2012, the company began the process of gaining approval from the Coast Guard, National Park Service and an agency for the construction, mooring and safety of the barges -- but the fire issue remained an obstacle.

In August, the Coast Guard told Google "the vessel's design doesn't incorporate certain fire safety features typically required," and in September, the project was finally disbanded.

Portland would have profited from the area's barge had it remained in operation, and despite collecting $400,000 in property tax as the construct whiled away its time in harbor, there will be lost revenue in tourism.

Google did not reply to a request for comment.

This story originally appeared at ZDNet under the headline "Google's mystery barges scrapped as fire hazard."