Browsing by Author "Anderson, D"

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    Estimates of site-scale groundwater recharge variability across a legacy low-level radioactive waste disposal facility in the Sydney Basin
    (National Centre for Groundwater Research And Training, 2017-07-12) Anderson, D; Hughes, CE; Rowling, B
    The Little Forest Legacy Site (LFLS) is a legacy, low-level radioactive waste disposal facility located at Lucas Heights in eastern NSW, Australia. The site was operated by the Australian Atomic Energy Commission between 1960 and 1968. Landfilling of wastes was to a maximum depth of three (3) metres into clay and shale material of the Hawkesbury Sandstone Formation. Monitoring of radionuclide containment at LFLS has been ongoing since the emplacement of waste. In recent decades the level of characterisation at LFLS has intensified to develop a more comprehensive understanding of the site geology, hydrogeology and hydro-geochemistry. This additional work is being undertaken to support detailed plans for site management. Recent site characterisation activity has included coring and geological logging, a range of geophysical surveys, monthly monitoring of groundwater and surface water quality and various laboratory analyses. Groundwater levels have also been recorded every 15 to 30 minutes since mid-2007 at twenty-three (23) locations about the site. This paper reports the results of our preliminary analysis of the comprehensive groundwater level monitoring data at the LFLS. This includes an analysis of the data with the episodic master recession (EMR) tool recently published by USGS. The EMR program provides a largely automated workflow to estimate groundwater recharge as a function of individual groundwater recharge events. When coupled with historical and/or synthetic rainfall time-series data the output of the tool can also be used to support simple but rapid simulation of past and/or future site groundwater levels. The data analysis techniques trialled in this study will be of interest to most hydrogeologists routinely involved in site characterisation studies. Our estimates of groundwater recharge rates into the clays and shales of the Hawkesbury Sandstone Formation at the LFLS may also be of interest to many practitioners working in the Sydney Basin.
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    Installation of a pilot experimental trench at the Little Forest legacy site
    (Australian Nuclear Science and Technology Organisation, 2018-07-30) Payne, TE; Kinsela, AS; Rowling, B; Hankin, SI; Cendón, DI; Comarmond, MJ; Bligh, MW; Hughes, CE; Anderson, D; Wilsher, KL
    During 2017, a pilot experimental trench was constructed at the Little Forest Legacy Site (LFLS). 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 (3 metres) and extends 6 m in length. However, unlike the disposal trenches, the experimental trench contains no waste materials of any kind. 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. It is intended that the pilot trench will be followed by other trenches with specific experimental objectives. The purposes of this report are to discuss the background, rationale for, and implementation of the facility; to provide a detailed description of the pilot trench; and to compile information and photographs documenting the excavation process. Although some preliminary hydrological data and comparisons with the legacy trenches are presented, the scientific data will be fully discussed and interpreted in future scientific reports.
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    Installation of an experimental trench at the Little Forest Legacy Site
    (South Pacific Environmental Radioactivity Association, 2018-11-06) Payne, TE; Kinsela, AS; Bligh, M; Anderson, D; Rowling, B; Hughes, CE; Hankin, SI; Cendón, DI; Wilsher, KL; Comarmond, MJ
    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.