What's it going to take ?, page-16

Taken from page 4 of the Resource upgrade, February 2017. Cheers.


Groundwater Flow and Recharge v. Brine Abstraction

1. The application of first principles to determine groundwater inflow into LD indicates that recharge will be at most 2GL/yr, but most likely below 1Gl/yr. This first principal conceptualisation indicates that recharge into the lake is dominated by direct rainfall which in an average year is approximately 240GL and a component of surface water runoff (10 – 13GL/year). This recharge is then offset by the evaporation which concentrates the salts.
   The relationship between recharge and evaporation is one that exists in a form of equilibrium as evidenced by the consistent water levels below the surface. Groundwater inflows to the lake represent a small portion of the overall hydrogeological cycle.
   The intended abstraction of 2000L/s (63GL/year) is far less than the average annual recharge potential (240GL/year), therefore it is unlikely that abstraction will impact lake brine levels beyond the immediate cone of depression for each trench or extraction bore. Grade will be continuously maintained by the addition of brines pumped from the deep wells into the trenches
   The Company is now in the process of expanding the knowledge base around the deeper aquifer by reviewing the regional structural geology and 2015-2016 core results to target potential high yield zones. Once these new bores have been tested the Company will provide an update on the resource model. Four boreholes with 200mm slotted casing have been installed on LD and are ready for pumping trials (see RWD December 2016 Quarterly Report).