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Background
Clyde Agriculture proposed irrigating 1820 hectares
under cotton cultivation; this proposal included the provision
of water storage reservoirs of up to 10,800 ML capacity.
Concerns were raised by the authorities managing Barwon
River water quality that mounding of the underlying water
table could result in additional seepage of saline groundwater
to the river.
Hoynes Wheeler & Thorne and subsequently Terra Sciences
Ltd commissioned C. M. Jewell & Associates Pty Ltd to
undertake EM geophysical surveys, soil mapping, soil profile
logging, extensive drilling of boreholes, groundwater sampling
and integrated data analysis, which included groundwater
flow modelling.
Hydrogeological Environment
The alluvial profile beneath the 'Beemery' site comprises
a clay/ironstone unsaturated zone to depths of 6-16 metres
overlying a saturated zone dominated by fine sands with
accessory silty and clayey layers. Flow of the native, saline
groundwater is hosted within the fine sand, which is about
10 metres thick. This, in turn, is underlain by clays and
siltstone that do not host any significant groundwater flow.
Native groundwater beneath the site has an electrical conductivity
range of 30-50 mS/cm.
Scope
Following a review of existing data, thematic mapping, aerial
photogrammetry and EM geophysical surveying, an in-depth
assessment of site hydrogeology using backhoe pits and borehole
logging was undertaken to confirm the distribution and properties
of various alluvial materials. C. M. Jewell & Associates
Pty Ltd prepared a series of reports from 1995 to 1998,
which detailed:
- planning and costing analyses
- initial drilling, geophysics and mapping
- modelling using Intersat
- advanced modelling using Visual MODFLOW
- impact assessment.
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Projects
