Assessing a remediation study

​​​​​​After a decision has been made to remediate some aspect of a waterway, you can use the Water Quality Management Framework to assess the effectiveness of a remediation program. Important components of applying the framework in this way include:

  • setting management goals (remediation targets)
  • monitoring the effectiveness of meeting those goals through appropriate water/sediment quality objectives set for relevant indicators.

The objectives may be incremental to allow for continual improvement from a highly modified state.

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When making the decision to remediate, you would have used a conceptual model based on current understanding from background or baseline knowledge of the waterway, potentially having already applied the Water Quality Management Framework.

This decision may have included stakeholder involvement.

The current understanding would have included a weight-of-evidence assessment indicating a biological impairment of the waterway (water and/or sediment). Specifically, it would have identified the sources, nature and spatial extent of contamination for which remediation is required (e.g. removal or treatment).

Update and refine the current understanding as further data become available.

You can use the conceptual model to later refine (at Step 3) the suite of key indicators required for a weight-of-evidence process to assess the progress and effectiveness of the remediation.

Community values and more specific management goals (including level of protection) for the remediation need to be established, if not already established. (In this context, management goals are comparable to remediation targets.)

You would normally complete Step 2 in parallel with the development or refinement of the conceptual models at Step 1.

Typically, the key community values and management goals for relevant catchment waterways will need to be defined or refined with technical and stakeholder involvement.

In severely contaminated sites, management goals may be stepped to reflect incremental response to improved water/sediment quality.

Key concepts:

Indicators are selected for the relevant pressure identified for the waterway (e.g. sources of contamination), their associated stressors and anticipated ecosystem receptors.

We provide use-specific quality of evidence tables to assist with the selection of different lines of evidence (multiple lines of evidence) and their indicators.

Your indicator selection should be based on the development and refinement of conceptual models, community values and management goals at Steps 1 and 2.

Select a mix of indicators — consistent with a weight-of-evidence process — to enable the most accurate assessment of the effectiveness of the remediation program. This could include reassessment of indicators used to inform Step 1.

At this step, you may need to use monitoring to:

  • ​test and validate relevant indicators
  • refine or develop sampling methodologies.

Initial monitoring data may cause you to further refine the list of selected indicators, such as where monitoring for one or more indicators at the required level of sensitivity is found to be impractical.

Key concepts:

Determine the water/sediment quality guideline values for each of the relevant biological, chemical and physical indicators that will provide desired level of protection (if applicable) for your management goals and protect the community values.

To provide the desired level of protection for your management goals, you will need to determine the water/sediment quality guideline values for each of the relevant biological, chemical and physical indicators required.

Where possible, derive or use locally relevant (e.g. site-specific, catchment) guideline values. These may already exist for the remediation area. For example, guideline values may have been derived in the weight-of-evidence assessment described in Step 1.

If these are not available, establish or continue monitoring programs or appropriate laboratory or field studies to derive locally relevant guidelines. You may use the existing contaminant gradient to derive biological-effects guideline values.

Where local guideline values are not available, use the default guideline values (DGVs) in the interim but be aware that they may not represent your local system.

In severely contaminated sites where management goals may reflect incremental improvement in water/sediment quality, you may initially apply (spatially and/or temporally) guideline values appropriate to highly modified ecosystems.

Key concepts:

To define the draft water quality objectives (or sediment quality objectives), select the guideline values and/or narrative statements at Step 4 for each indicator selected at Step 3 that should ensure the protection of all identified community values and their management goals (Step 2). Choose the most stringent of the guideline values for the water/sediment quality objectives (W/SQOs).

These objectives may already exist for the remediation area (e.g. as derived from previous application of the Water Quality Management Framework described in Step 1).

Key concept:

This is the first step in the Water Quality Management Framework that evaluates progress towards achieving the water/sediment quality objectives (W/SQOs) and remediation targets.

Compare the water/sediment quality monitoring data for each relevant indicator with the W/SQOs, together with the evidence from any additional lines of evidence.

Use the results to assess water/sediment quality, including:

  • whether or not the W/SQOs have been met
  • the cause and spatial extent of any change observed.

Use a weight-of-evidence process to evaluate the various lines of evidence. This process assesses results from multiple lines of evidence across the pressures, stressors and ecosystem receptors included in the monitoring program. It is the key process by which the protection or status of the aquatic ecosystem is assessed.

Multiple potential outcomes are possible from a weight-of-evidence assessment. We provide guidance on their interpretation for this use of the Water Quality Management Framework in use​-specific evaluation tables.

The W/SQOs are deemed to be met when:

  • those lines of evidence considered as essential for informing acceptable water/sediment quality are met
  • results for other supporting lines of evidence are consistent with no compromise to current or future water/sediment quality.

If water/sediment quality is acceptable, then management should focus on maintaining or improving that quality. This will require a check of any possible improvements to management strategies at Step 8, and then implementation at Step 10.

Where incremental W/SQOs are met, the focus will be on continuing to improve the existing water/sediment quality to meet the next increment of the objectives.

A weight-of-evidence evaluation will otherwise conclude that:

  • W/SQOs are not met
  • adverse trends are evident
  • result is inconclusive (e.g. due to difficulties in obtaining good quality monitoring data or if there is conflicting evidence from separate lines of evidence).

In these cases, up to 3 options are available:

  • formulate, assess and prioritise management strategies to improve water/sediment quality (Steps 8 to 10), and/or
  • reassess the appropriateness of the water/sediment quality guideline values (Step 7), and/or
  • consider selection of additional or alternative indicators or lines of evidence (Step 7).

Where incremental W/SQOs (remediation targets) are in place, a weight-of-evidence evaluation may require multiple cycles of the Water Quality Management Framework before clear outcomes are identified, and before one or more of the 3 options can be implemented.

Key concepts:

You may want to refine the water/sediment quality objectives (W/SQOs) if the assessment at Step 6 indicates:

  • W/SQOs have not been met (including any incremental objectives), or
  • the assessment is equivocal (e.g. there is uncertainty that draft or existing W/SQOs can be met in the future).

Use the better-quality system data gathered throughout the process (Steps 3 to 6) or specific biological-effects studies to make any refinements.

Alternatively — or in addition — you could include additional relevant lines of evidence and associated indicators (via Step 3) if the weight-of-evidence assessment at Step 6 showed:

  • insufficient lines of evidence to make a suitable assessment of the effectiveness of remediation, or
  • one or more of the selected indicators proved impractical to implement or failed to provide evidence of sufficient certainty or sensitivity.

Studies required to refine water/sediment quality objectives or include additional lines of evidence at this step may not necessarily be lengthy, and may include:

  • implementing additional monitoring
  • continuation or refinement of existing monitoring
  • dedicated laboratory or field effects studies, to establish more relevant indicators or water/sediment quality guideline values.
  • In practice, Steps 7 and 8 are likely to be conducted in parallel.

Key concepts:

Even if the water/sediment quality objectives (W/SQOs) were met, before progressing to Step 10 you can consider refinement of management activities to further improve water/sediment quality.

You may need to consider alternative management strategies for the remediation if the assessment at Step 6 indicated:

  • draft or existing W/SQOs have not been met, or
  • water/sediment quality is unexpectedly trending towards increased risk to community values.

Formulate, assess and prioritise alternative management strategies on the basis of environmental considerations, as well as cultural, economic and social considerations (quadruple bottom line).

Use monitoring data or appropriate water/sediment quality predictive models to demonstrate that alternative management strategies for the remediation (e.g. further source reduction), together with any revised W/SQOs, achieve the required water/sediment quality.

Agreement on final management strategies will require stakeholder involvement.

In practice, Step 7 and 8 are likely to be conducted in parallel.

Key concepts:

The assessment of whether or not the water/sediment quality objectives are achievable is based on the information gained from Steps 6 to 8.

If the remediation has been assessed to be performing as expected, or is expected to achieve the remediation objectives via implementation of alternative management strategies, then the focus should move to Step 10 and the required management/remediation strategies continued or altered as agreed.

If the assessment is that the remediation objectives are not considered currently achievable, then the focus should shift back to Step 2 and reconsideration of the management goals (remediation targets), most likely with technical and stakeholder involvement.

Key concept:

You have reached Step 10 because acceptable water/sediment quality has been or can be achieved.

Implications for the monitoring program may have arisen from the considerations at Steps 6 to 8, and these should be fed into revision of the ongoing monitoring programs.

Alternative management or remediation actions from Step 8 need to be incorporated into the management or remediation plans, which should also include a suitable and agreed adaptive management process.

Continual improvement of both management and monitoring activities should be considered at this step, regardless of how you reached Step 10.

If the remediation program is ongoing, then continuation of monitoring and management will lead to continued cycling through the Water Quality Management Framework.

If the remediation program has been completed and the water/sediment quality objectives have been met, continue monitoring (for the agreed post-remediation period) to ensure the required level of protection is maintained.

Reporting of the progressive or final results of the remediation program will form an important part of communication with stakeholders (stakeholder involvement).

Key concepts: