Three of the screened sites were carried forward into this study, and one new site was added.

Ten years ago, the site was added to the Superfund list and cleanup began.

A further 165 sites were added on September 12, 2012, all of them designated by codes only.

The site was added to the National Register in 2005.

About 50 sites will be added annually to that list.

The current site has been considerably added to in the 1980s, 90s and recently, with further plans to develop (see below).

The site was added to the National Register on 1976-06-17.

Along with the original buildings, which were built in 1955, the site has been added to many times since.

However, due to pressure from influential politicians, additional sites were later added.

The new site was added to continue the school's mission of teaching in a natural setting.