Changes in Groundwater Contamination
Why do we monitor Groundwater
How do we monitor Groundwater Contaminants?
Why do we monitor the Groundwater Treatment System
Groundwater Treatment Monitoring Results
Groundwater Treatment System Monitoring Results

• Changes in Groundwater Contamination

Prior to any groundwater treatment, groundwater monitoring results from 1997 indicated contamination extending beyond site boundaries to the east, west and south. In particular groundwater contamination was interpreted to extend approximately 500m beneath the adjacent Qenos Plastics site almost as far as the Melbourne to Geelong railway line.

Recent groundwater monitoring has indicated that contaminant concentrations in wells around the edge of the plume are decreasing and that the plume appears to be contracting. In particular the plume is now interpreted to have divided into two smaller plumes.

Whilst contaminant concentrations can fluctuate from one monitoring event to another, overall decreasing trends or stable contaminant concentrations can be shown for most monitoring wells.

• Why do we monitor Groundwater?

Groundwater monitoring on a regular basis allows the assessment of the treatment process directly on the groundwater. This facilitates comparison of contaminant levels over time and thus assessment of plume shape and movement.

• How do we monitor Groundwater Contaminants?

Seventy-seven wells are used for monitoring contaminants in both the upper and lower aquifers.

Well locations
(PDF; 280KB)


Groundwater enters each well through a slotted section. The positioning of the slotted section determines which aquifer or part of an aquifer is monitored. The seventy-seven wells used for monitoring are divided into four categories as shown below. A fifth category, comprising twenty-seven wells, are positioned in the rock above the upper aquifer. These wells have been installed as part of treatment plans.


Click here to view diagram
(17kb)

The table below provides detail of the number of wells in each category and the general depths to which they are installed.


Well Category Installed Depth Number of wells Total
On-site Off-Site
1 < 10m 19 0 19
2 10 - 15m 14 27 41
3 15 - 20m 14 1 15
4 20 -25m 3 1 4
5 35 - 40m 6 1 7

Monitoring of wells occurs on both an annual and "routine" basis. Annual monitoring involves a full analysis of samples from all wells.

Routine monitoring involves analysis of samples from a reduced set of wells targeted over the area of greatest contamination. Routine monitoring carried out since 1997 has indicated that the distribution of main contaminants is not changing over time. The frequency of routine monitoring has therefore been reduced from quarterly to half-yearly.

All monitoring is carried out in accordance with ISO 9000 quality procedures.

A breakdown on the analyses undertaken during annual and routine monitoring is shown in the table below.

Annual monitoring Routine monitoring
  • volatile chlorinated compounds;
  • total petroleum compounds;
  • benzene, toluene, ethyl benzene, xylenes;
  • polycyclic aromatic hydrocarbons (PAHs);
  • pH (in field);
  • electrical conductivity (in field);
  • temperature (in field);
  • dissolved oxygen (in field); and
  • Redox potential (in field).
  • Vinyl Chloride Monomer (VCM);
  • 1,2-dichloroethane (EDC);
  • benzene, toluene, ethyl benzene + xylenes;
  • pH (in field);
  • electrical conductivity (in field);
  • temperature (in field);
  • dissolved oxygen (in field); and
  • Redox potential (in field).

• Why do we monitor the Groundwater Treatment System?

Monitoring of the groundwater treatment system ensures that treatment is undertaken in accordance with the operating licenses which dictate air emission limits (reviewed by the EPA) and waste water effluent quality (reviewed by City West Water). Monitoring of the treatment system also allows the system to be fine-tuned during operation so that the equipment is run in an efficient manner.

• Groundwater Treatment Monitoring Results

The data presented below represents results of routine and annual groundwater monitoring. Previous quarterly groundwater monitoring comprised the sampling of 16 targeted wells which were located in close proximity to the treatment system and are thus the most likely to exhibit effects of the treatment system's operation. The half-yearly groundwater monitoring routine beginning in May 2004 follows the same sampling program as the previous quarterly events. Annual groundwater monitoring comprises the sampling of sixty-four wells located both within the Altona Properties site and in neighbouring properties owned by Dow, Qenos and Salta.
From November 2006, annual groundwater monitoring will comprise sampling of seventy-six wells.

Maps of the following groundwater monitoring results can be viewed:

Groundwater levels

Groundwater levels, Catergory 2 wells, July 2010 (PDF; 214KB)

 

EDC groundwater concentrations

VCM groundwater concentrations

• Groundwater Treatment System Monitoring Results

The data presented below represents updates to groundwater treatment system results. Note that all graphs indicate cumulative results and are updated to this web site following review by the community consultation group. The data presented below reflects data to the end of January 2007.

Graphs of the following results can be viewed:

 

Altona Properties Pty Ltd.
Copyright © 2011 Altona Properties, except where indicated.
URL: www.altonagroundwater.info
last modified:07-05-2007 | next update due May 2011
Send comments or suggestions to Mark Wloch, mwloch@pb.com.au