Hydrogeological Assessment – Whitemark Waste Depot, Flinders Island

Flinders Council provides many services and facilities to enhance the quality of life of local residents and, where possible, to add value to their properties, businesses and investments.

The Environment Protection Authority Tasmania (EPA) completed a compliance assessment pursuant to the Monitoring and Reporting conditions of Permit No.3394 as varied by Environment Protection Notice (EPN) No.7191/2, at the Whitemark waste depot on 12 July 2018. The EPA identified several non-compliances, most of them relating to an absence of surface water and leachate chemistry data, and groundwater quality trend analysis.

Work Scope

EHS Support were engaged and addressed the challenges by undertaking a staged Hydrogeological Assessment. This included:

  • A site walkover and groundwater well inspection.
  • A detailed desktop assessment and Hydrogeological Assessment report.

Stage 1 –Site Walkover and Groundwater Well Inspection

EHS Support met with Flinders Council in September 2018 and discussed the key aspects of the project and completed the site walkover. The purpose of the site walkover was to:

  • Inspect the current operating putrescible waste cell, location of the proposed putrescible waste cell (Cell 1) and proposed leachate pond;
  • Identify environmental receptors and protected environmental values;
  • Inspect all three existing groundwater monitoring wells and record total well depth and depth to groundwater;
  • Assess existing groundwater and surface water monitoring locations; and
  • Assist in determining future surface water monitoring locations and groundwater monitoring wells, based on the proposed landfill design, to ensure that any impacts are captured and that protected environmental values are monitored.

Stage 2 – Desktop Assessment

A comprehensive assessment of available information was undertaken, including collating historical groundwater quality results. The desktop assessment included:

  • Reviewing relevant geology maps, hydrogeology reports and other publicly available information to assess groundwater systems, watertable elevation (depth to groundwater), groundwater quality, expected aquifer parameters and aquifer yield;
  • Interrogating State groundwater databases (Land Information System Tasmania – LIST) to identify surrounding users of groundwater, groundwater dependent ecosystems and other sensitive receptors;
  • Interrogating State databases to identify surrounding surface water systems, sensitive land use and protected environmental values;
  • Determining the adequacy of the current groundwater monitoring program, including contaminants of potential concern, and discussion of groundwater quality trends over time; and
  • Making recommendations on target aquifers, drilling depths and well construction for additional monitoring wells.

The desktop assessment was undertaken in general accordance with the recommended structure of a Hydrogeological Assessment as detailed in Section 2.4 and Section 3.3 of the Landfill Sustainability Guide (DPIWE, 2004) and the conditions set out in the EPN No 7191/2.

Based on the outcomes of the Hydrogeological Assessment, and a review of the expansion of the waste depot, recommendations for improvements across the groundwater well network, data analysis parameters and data collection procedures were made to ensure that potential impacts are captured and protected environmental values monitored.

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