Installation of an experimental trench at the Little Forest Legacy Site

Abstract

During 2017, a pilot experimental trench was constructed at the Little Forest Legacy Site (LFLS), a 1960s era disposal site for low-level radioactive waste. The objective of installing this trench was to facilitate experimental field-work aimed at further characterising the site, in particular the hydrology of the excavated trenches and of the near-surface layers in which the trenches are located. The test trench is of similar depth to the waste disposal trenches at the legacy site (8 metres) and extends 6 m in length. However, unlike the disposal trenches, the experimental trench does not contain waste materials. instead, the trench contains a number of sampling points and other instrumentation, and is back filled with river gravel to provide a uniform composition and maintain structural stability. in this paper, the excavation of the trench is described, together with observations made during the excavation. in addition, some preliminary hydrological data and comparisons with the legacy trenches are presented.