Iluka Aquifer Injection Scheme
Client: GHD Pty Ltd
Year: 2004-2005
Project Reference: 05025
WRL Technical Reports: Iluka Sewerage Scheme - Detailed Concept Design of an Aquifer Injection Scheme (2005/27); Iluka Aquifer Injection Scheme - Plan of Management (2005/31)
With the advent of a new sewerage scheme for the township of Iluka, WRL was engaged to develop a detailed concept design for an aquifer injection system. Located on a narrow peninsula on the northern banks of the Clarence River, the site is bounded by the Pacific Ocean to the east and the Clarence River to the south and west. To design the system appropriately, WRL completed investigations to characterise the stratigraphy and determine the physical and chemical properties of the aquifer.
In 2001, WRL had installed multi-level piezometers for a prior study; these were supplemented by the installation of additional multi-level piezometers and a production bore in 2004. Borehole logging, slug testing of piezometers and an aquifer pump test were completed to determine the hydraulic conductivity of the aquifer. Water level data and water quality samples were collected from the piezometers on eight occasions over the course of the year.
Using this data, potential concerns regarding clogging of the bore screens and aquifer by processes such as injection of suspended solids, iron biofouling and precipitation, carbonate and sulphate scaling, and mobilisation of clay, could be assessed. With the acquisition of further tide, river, wave and meteorological data, a conceptual model of the site was developed, which was used as the basis of 2D and 3D numerical models. Using the FEFLOW finite element modelling program, the importance of density-dependant flow to the model was able to be considered. WRL used the model to test a wide range of scenarios and thereby optimise the design of the injection system.
WRL complimented this scope of works by producing a detailed plan of management for the injection scheme. This described management responses to reduced injection efficiency, protocols for groundwater monitoring, trigger levels at which management responses are required, and the corresponding corrective actions to be taken. Requirements for ongoing reporting and review of the program completed the plan. WRL’s scope of works was completed with the concept design.
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