Management of Groundwater System for Citylink Tunnels, Melbourne

The management of the groundwater system in the vicinity of the Citylink Tunnels is concerned with protecting private and public assets above the tunnels.

The regional geology consists of the Yarra Delta Sediments and basalt flows overlying the Melbourne Mudstone bedrock. The Yarra Delta sediments comprise a number of alluvial and marine sedimentary deposits. The alluvial deposits are typically granular in nature and produce important aquifers. The marine deposits are more recent in age and are susceptible to consolidation settlement.

The groundwater management includes monitoring of over 100 standpipes and vibrating wire piezometers, monitoring of over 500 survey pins, and monitoring and control of the groundwater recharge system. The groundwater recharge system consists of 5 permanent recharge wells, 10 passive recharge wells and a Water Treatment Plant. The monitoring data is stored in Microsoft® Access 2000 and GIS software package. ArcView is used to assist in assessing the behavior of the aquifers and settlement rates. The use of a database and GIS software tools allow rapid and easy review of a vast volume of data to show groundwater and ground surface trends.