Authorities in the seaside resort city of Atami where a landslide in July killed at least 26 people were fully aware of the risk of landfill on a steep mountainside collapsing in torrential rain but inexplicably deferred a decision in ordering urgent construction work to fix the problem.

This is the picture that emerges from reams of internal documents obtained by The Asahi Shimbun from the Shizuoka prefectural and Atami city governments.

The trigger for the disaster was the massive amount of landfill used so houses and buildings could be constructed on the mountainside overlooking the ocean in Shizuoka Prefecture.

The total volume of landfill came to about 74,000 cubic meters, twice what the construction operator said was needed when it submitted its development plan to the city. The earthen mound was 50 meters high, three times more than the blueprint seeking authorization to proceed with the work.

The July 3 landslide occurred after days of heavy rains and destroyed or damaged 132 homes and buildings. Aside from the 26 fatalities, one person remains unaccounted for.

According to multiple administrative internal documents, prefectural and city officials were aware that all sorts of procedures related to development work were being ignored during the period between 2007 and 2010.

For example, a business operator based in Odawara, Kanagawa Prefecture, that initially purchased the site flouted the Forest Law by developing forested land across a wider area than it had agreed to do.

It also ignored a local ordinance by repeatedly trucking in tons of dirt and other landfill comprising industrial and trade waste to create the massive earthen mound.

Local officials issued administrative directives to the business operator on multiple occasions, requesting that it stop bringing in the dirt. But it did not comply.

Prefectural and city officials concluded in October 2010 that the mound had grown so huge “it will likely pose a risk to the lives and fortunes of residents if it collapses.”

In February 2011, ownership of the land changed hands.

During a meeting on March 17, 2011, local officials decided to adopt administrative steps with more bite than administrative directives against the business operator.

They concluded the earthen mound was “at risk of washout and collapse” and that the operator “needs to correct the (situation) immediately.”

The administrative measure was based on a prefectural ordinance related to restrictions on the way soil for development is collected.

As such, local officials were able to order the operator to take preventive steps within a given time frame based on a risk assessment of a natural disaster occurring.

Some of the officials also insisted they should resort to a legal step known as administrative subrogation if the operator did not comply, thereby enabling local governments to remove the mound on behalf of the company and have it shoulder the cost of the work.

Based on a meeting between prefectural and city officials, it was decided to issue the order in June 2011.

The mayor of Atami made the final decision, so officials formally requested an explanation from the operator.

By after the notification, the company started building a drain to channel heavy rain and other disaster prevention work at the site.

As a result, no further action was taken against the operator, which promptly abandoned the work that November. After that, the Atami authorities experienced difficulties contacting the operator.

In October 2012, they called on the new landowner to rectify the problem but the request went unheeded.

Officials had no recourse and were unable to take legal action because the ordinance does not have a stipulation that targets a landowner.

They regularly checked the earthen mound to gauge whether it was still stable.

But the officials never took administrative subrogation after all.

The result of the investigation into the disaster by the prefectural and city governments was released on Oct. 18.

Officials disclosed 860 or so administrative documents that show the prefectural and city governments were aware of the risk of a landfill washout and collapse.

Atami Mayor Sakae Saito, explaining the decision not to issue the order, said: “I was told that (the governments) decided to forgo it because the (operator) had carried out disaster prevention work, even though it was inadequate. And it promised to carry out additional work. In hindsight, I have to say it was a clever trick to avoid a severe reaction from the governments, and it is frustrating.”

Family members of those who perished in the landslide filed a lawsuit against the landowner and other parties in September on grounds of negligence in implementing appropriate safety measures. They are seeking 3.2 billion yen ($28 million) in damage compensation.

They are also weighing whether to sue the prefectural and city governments.

(This article was written by Hiroyoshi Itabashi and Kae Kawashima.)