Soil and Groundwater Remediation and Validation Services

Contaminated Land Remediation and Site Validation

Confluence Environmental provides soil and groundwater remediation, contaminated land remediation and site validation services for development, infrastructure, industrial and government projects across NSW.

We work with clients from the point contamination has been identified through to completion of remediation works and final validation.

Our role can include developing the remediation strategy, implementing an existing Remediation Action Plan, supervising remediation contractors, managing contaminated soil and groundwater, undertaking validation sampling and preparing the final Site Validation Report.

Where remediation forms part of a broader construction project, we work with the project team to integrate environmental requirements with excavation, demolition, earthworks, services and construction sequencing.

Our remediation and validation services include:

• soil remediation and contaminated soil removal;

• groundwater remediation and monitoring;

• remediation planning and implementation support;

• remediation supervision;

• contaminated soil and waste management;

• asbestos in soil remediation support;

• validation sampling and assessment;

• imported soil and material verification;

• Environmental Management Plans; and

• Site Validation Reports.

Where additional investigation is required before remediation can proceed, our Detailed Site Investigation services can be used to resolve the remaining data gaps and define the remediation requirements.

Soil Remediation

Our soil remediation services are developed around the contamination present, the proposed land use and the way the site will be developed.

Depending on the site, remediation may involve removing contaminated soil, treating affected material, containing contamination beneath engineered barriers or managing suitable material in place.

Common soil remediation strategies can include:

• excavation and off-site disposal;

• targeted contaminated soil removal;

• capping and containment;

• stabilisation or immobilisation;

• treatment of hydrocarbon-impacted soil;

• management of contaminated fill;

• asbestos-impacted soil remediation;

• controlled on-site management of suitable material; and

• long-term management of residual contamination.

The appropriate strategy depends on the source, contaminant concentrations, affected area and depth, exposure pathways, groundwater conditions and development requirements.

The objective is not simply to excavate everything that exceeds an investigation criterion.

It is to develop a practical site remediation strategy that manages the identified risk, can be implemented efficiently and can ultimately be validated.

Where a remediation strategy has not yet been prepared, Confluence can develop a Remediation Action Plan setting out the remediation objectives, methodology, criteria, environmental controls and validation requirements.

Groundwater Remediation

Contamination is not always limited to soil.

Former fuel storage, industrial activities, spills, waste disposal and other historical land uses can result in contaminants migrating into groundwater.

Confluence provides groundwater remediation and contaminated groundwater management services as part of broader contaminated land remediation programs.

The appropriate approach depends on the contaminant source, groundwater conditions, plume characteristics, potential receptors and whether the source remains active.

Groundwater remediation and management may include:

• source removal;

• groundwater monitoring;

• delineation of dissolved-phase contamination;

• assessment of groundwater migration;

• recovery or treatment of contaminated groundwater;

• monitored remediation approaches;

• management of petroleum hydrocarbon impacts;

• integration of soil and groundwater remediation; and

• post-remediation groundwater monitoring.

Where both soil and groundwater are affected, the remediation strategy should consider them together.

Removing contaminated soil without addressing an ongoing groundwater source — or treating groundwater while leaving the primary source in place — may not provide an effective long-term solution.

Our soil and groundwater remediation strategies are therefore developed around the complete Conceptual Site Model rather than treating each environmental medium in isolation.

Remediation Implementation and Supervision

A Remediation Action Plan establishes what needs to be done.

Successful remediation depends on how those requirements are implemented on site.

Confluence can provide environmental supervision and technical support during remediation works to ensure the remediation strategy is followed and unexpected conditions are appropriately managed.

Our role may include:

• pre-start review of the remediation requirements;

• liaison with remediation and civil contractors;

• supervision of contaminated soil excavation;

• identification and segregation of different material types;

• field screening and inspection;

• stockpile management;

• waste classification and disposal support;

• monitoring of remediation boundaries;

• management of unexpected contamination;

• asbestos in soil controls;

• groundwater monitoring;

• validation sampling; and

• documentation of completed remediation works.

This allows environmental decisions to be made while works are progressing rather than after material has already been excavated, mixed or removed from the site.

For projects where remediation occurs alongside demolition, bulk earthworks or civil construction, early involvement can also help reduce unnecessary handling and disposal of soil.

Contaminated Soil Removal and Waste Management

Where contaminated soil must be removed from a site, the remediation process needs to consider both the environmental requirements and the legal requirements applying to the excavated material.

Contaminated soil may require assessment and classification before it can be transported to an appropriate receiving facility.

Confluence can coordinate contaminated soil assessment with our waste classification services, allowing remediation and disposal requirements to be considered together.

This can include:

• classification of excavated soil;

• targeted assessment of stockpiles;

• segregation of different waste streams;

• assessment of contaminated fill;

• asbestos-containing soil;

• review of disposal documentation; and

• verification of material movements during remediation.

Where large volumes are involved, appropriate characterisation and segregation can have a significant effect on disposal costs.

A well-planned remediation strategy therefore considers material management before excavation starts.

Validation of Remediation Works

Remediation is not complete simply because contaminated material has been excavated or treated.

The completed works need to be assessed against the remediation objectives established for the project.

Confluence provides remediation validation to demonstrate whether the required outcome has been achieved.

Depending on the remediation strategy, validation may include:

• sampling of excavation walls and bases;

• confirmation of contaminant removal;

• assessment of residual soil;

• verification of treatment outcomes;

• inspection and verification of capped areas;

• confirmation of clean cover thickness;

• verification of imported material;

• groundwater monitoring;

• review of waste disposal records;

• photographic and field documentation; and

• confirmation that remediation has been completed in accordance with the Remediation Action Plan.

Validation requirements should be established before remediation commences wherever practicable.

This allows remediation contractors, consultants and project managers to understand what evidence will ultimately be required to demonstrate successful completion.

Site Validation Reports

Following completion of the remediation and validation program, Confluence can prepare a Site Validation Report documenting the works undertaken and the final condition of the site.

The report typically brings together the remediation history, field observations, validation results, waste documentation, imported material records and any remaining management requirements.

Depending on the project, the Site Validation Report may address:

• works completed under the Remediation Action Plan;

• final remediation extents;

• validation sampling and laboratory results;

• groundwater validation or monitoring;

• disposal of contaminated soil;

• imported material;

• unexpected finds;

• residual contamination;

• compliance with remediation criteria;

• departures from the original remediation strategy; and

• suitability of the site for the intended land use.

Where residual contamination remains, the final outcome may also include an Environmental Management Plan or other ongoing controls.

For developments requiring independent review, remediation and validation documentation can also be prepared for consideration under the NSW EPA Site Auditor Scheme.

Remediation Designed Around the Site

There is no single remediation method that is appropriate for every contaminated site.

A small localised hotspot may be best addressed through targeted excavation.

Widespread low-level contamination may be better managed through containment or integration with the development.

Petroleum contamination may require combined soil and groundwater remediation.

Asbestos-impacted soil may require a different remediation and validation approach again.

For this reason, our contaminated land remediation work is based on the site's Conceptual Site Model and the specific decisions the project needs to make.

We consider:

• the contamination source;

• contaminant type and concentration;

• horizontal and vertical extent;

• soil and groundwater conditions;

• potential exposure pathways;

• proposed land use;

• excavation and earthworks;

• buildings and infrastructure;

• waste disposal requirements;

• remediation cost and constructability;

• long-term management requirements; and

• the validation evidence needed at completion.

This allows the remediation strategy to be integrated with the project rather than treated as a standalone environmental exercise.

From Investigation to Validation

Confluence can support a contaminated land project through the full assessment and remediation process.

Where contamination is suspected, a Preliminary Site Investigation establishes the site history and potential contamination risks.

Where further assessment is required, a Detailed Site Investigation characterises the contamination and refines the Conceptual Site Model.

Where remediation is required, a Remediation Action Plan establishes how the contamination will be managed.

Confluence can then provide support through:

Investigation → Remediation Planning → Remediation Works → Validation → Site Validation Report

This continuity helps maintain the link between the investigation findings, remediation objectives and final site outcome.

Whether Confluence has completed the earlier investigation or has been engaged to implement an existing remediation strategy prepared by another consultant, we can review the available information and establish the practical steps required to progress the project.