Townley, L.R. (1996), Review of previous studies of seepage
from Ranger tailings dam, CSIRO Minesite Rehabilitation Research
Program, 68pp., February. [Confidential]
This report provides a comprehensive review of all available studies to date which provide
information relevant to the assessment of seepage from the Ranger tailings dam. Sources of
information include reports on:
the geology of the site (including inferences about aquifers and aquitards,
mapping during excavation of trenches etc.)
construction details (including the use of low-grade ore during lifts and the
use of water from RP1 and RP4 for dust suppression and compaction during Stages III and IV)
the seepage collector system (including attempts to reduce flows of water into the system)
the physical and chemical nature of the tailings (including densities,
hydraulic conductivities, and mineralogical and pore water compositions)
geotechnical investigations (including in situ permeabilities and
observed head gradients at the base of the tailings)
hydrogeological investigations (including data from water level monitoring bores)
hydrogeochemical and isotope investigations (including measurements of
sulphate, Mg/SO4 and Mg/Ca ratios, S isotopes, radiogenic Pb isotopes and Ra isotopes)
geophysical investigations (including seismic, resistivity and electromagnetic surveys)
hydrological investigations (including water balance studies of the
seepage collector trench, lysimeter studies, and a tritium tracer experiment)
hodelling studies (including predictions of seepage and solute transport before,
during and after construction)
Most available information supports the view that seepage is indeed occurring from the tailings dam,
as predicted during design. Seepage appears to be entering the seepage collector trench, as intended,
where it is mixing with water which infiltrates through the embankment of the dam.
Suggestions are made for a number of possible additional studies, to confirm the connections between
different parts of the tailings dam, the seepage collector system and the surrounding aquifer, and to
underpin future planning and management by ERA of solute movement near the tailings dam. The report
contains an annotated bibliography of existing reports, and a brief description of a tritium tracer test.