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Evans & Mitchell McCotter Reports
Précis Summary


Summary of an appraisal by M R Evans, B.Sc., - Principal Hydrologist, Salient Solutions Australia Pty Ltd, Consultant to the Australian Coal Alliance - on the impact of longwall coal mining on the Wyong Water Catchment.

  • The water balance within the coal seams has not been defined.

  • Pertubations in the system caused by development (longwall coal mining) altering the hydraulic state of aquifers. There is every possibility this project will impact upon the existing groundwater flow system and coal seam hydrology.

  • A conclusion (Faiz drawn from the period of uplift in the Cretacious-Tertiary Period, where tectonic activity opened up overlying Strata “. . . the escape route opened up in this period to the possibility of groundwater connectivity, between the coal seams and the shallow aquifers . . .” (Evans, R.)

  • The valleys have a complex water system that is being developed to support current and future developments. A multi-land use cannot be made in isolation.

  • The role of meteoric water migration through coal seams in the enhancement of methanogenesia process (Faiz “Meteoric water carrying bacteria and nutrients have ready access to flow through the coal seams”.

  Ray Evans, B.Sc - CV in brief

Over 28 years experience in Australian hydrogeology and environmental science, ranging across regional aquifers, fractured rock hydrology, hydrochemistry and isotope hydrology, dryland salinity and catchment management.

REPORT: Groundwater Studies for the Wyong Coal Development Project. (ERM Mitchell McCotter Pty. Ltd. March 1999)


Report 96093. 08RP Briefing Paper

This Report indicates four types* of aquifers in the proposed Coal development Areas Within the Yarramalong and Dooralong Valleys - A Proclaimed Water Catchment.

* Alluvial, Coastal Dune, Estuarine Backswamp, Porous and Fractured Rock aquifers

Silt and clay lenses separating in identified boreholes were not anticipated to impede the transmission of bulk water (pl. l -1.4, 2.2-2.6. Report 96093. 08RP).


Summary - Ron Sokolowski B.Sc.
Scientific Member Australian Coal Alliance (ACA) 29/08/06



There is no evidence in this report which illustrates "aquicludes" and/or confined aquifers preventing water movement. Subsidence, arising in the valleys in the Hawkesbury Sandstone, conglomerates and unconsolidated alluvial soils, will facilitate drainage flow from these unconfined aquifers and to surface groundwater. These unconfined aquifers, which are below the water table, satisfy the following:

Quote . . . "the water table expresses a dynamic balance between natural recharge and discharge. It is dynamic because normal seasonal variations in temperature (affects infiltration, evaporation and transpiration) and precipitation( affects infiltration) causes the water table to fluctuate and influence the discharge rate. Engineered discharge (and recharge) disturbs the natural dynamic balance.” . . . Unquote

Marshall, B., A.R.CS., B.Sc. Hon.(London), Ph.D. (Bristol), Grad.Dip. Mgt.(CIAE). Adjunct Professor of Geology, University of Sydney. GROUNDWATER lifeblood of the environment. Blue Mountains Conservation Society. April 2005.

Longwall coal mining can be likened to an "engineered discharge" of the coal aquifer destroying the natural dynamic water balance arising from standing water, creeks, rivers, floodplains and wetlands. It is an unacceptable serious threat to our public water resources, will cause environmental degradation in perpetuity and some swamps may also dry out. Two critical riparian corridors are threatened in this Proclaimed Public Water Catchment which provide transit, refuge, food and habitat areas for terrestrial fauna in transit from the coastal plains up into the inland Wattagan Mountains.


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