The information provided in this article is accurate as of the publication date. While we strive to ensure the content remains relevant and up to date, industry standards, regulations, and best practices may evolve over time. Readers are encouraged to verify details with current sources or consult a professional for specific guidance.
This guide is intended to demystify the regulations around basement dewatering and outline the approval processes.
Douglas Partners has been working in geotechnical and groundwater services for decades, and our team serve as both service provider and trusted advisor in the sector. The current regulatory requirements around basement dewatering are incorporated into project reports and client discussions. Our experience with past practice and with new and evolving processes help us guide projects and clients through the current regulatory environment.
Regulatory compliance matters. The changes in dewatering approval processes stem from the integration of regulatory requirements with urban developments, including issues of sustainable groundwater usage, environmental preservation, and societal needs. Multiple authorities enforce these regulations at both specific project sites and broader regional aquifer levels. The authorities ensure not only compliance but also the preservation of this vital resource.
Navigating the Approval Process for Basement Dewatering
The key processes for approval for basement dewatering can vary depending on the approval process.
For Council DAs, WaterNSW requirements may be integrated into the DA requirements through the General Terms of Approval (GTAs). Reporting requirements at each stage will depend on dewatering requirements, but may be streamlined where only temporary dewatering is proposed.
Older projects, or projects that are not identified as integrated projects may receive more limited guidance through Council conditions. The regulations still apply, however, and the appropriate approvals and licences for dewatering are still required by law.
For Major Projects, dewatering assessment and approvals are generally integrated into the SEARS and authority approval. Where significant dewatering is required, appropriate entitlements (see WAL, below) may need to be held by the proponent before SSD/SSI approval is granted.
Typical Approvals and Licences
Typical approvals and licences include:
Water supply works approval: This approval (replacing the “aquifer interference approval”) requires site and project-level assessment, focusing on the impact of dewatering and estimates of the volume of water to be extracted. It’s a detailed process integrating geotechnical and contamination assessments together with key development and construction elements.
Water access licence (WAL): This license is linked to a given allocation or entitlement in the groundwater source. It is crucial for regulating water extraction from the water source. Appropriate and sufficient entitlements, obtained from a water broker or via a Controlled Allocation Process, must be held on the Water Access Licence linked to the project site.
Water use approvals: These approvals relate to the methods of water disposal such as through stormwater or sewer systems.
Exemptions to some of the above approvals and licences may apply to your project, depending on the proposed works, site location, dewatering requirements and approval framework. Mandatory monitoring and reporting is generally still required, even if an exemption is used on your project.
Additional approvals may also be relevant to your project works, such as for special use of water (eg re-injection to the aquifer).
If granted, conditions apply to approvals and licences. These conditions limit the volumes that may be legally extracted and include monitoring requirements, reporting to the regulator and other compliance measures.
Steps towards Dewatering Approvals and Licences
Water Supply Works Approval
Successful applications for dewatering approval require information on impacts and dewatering volumes, appropriate to the site and aquifer conditions.
Typically, a Dewatering Management Plan (DMP) – suitable to the complexity of groundwater conditions, risk of adverse impacts and the stage of project planning – will be required to support an approval.
The DMP requires a thorough understanding of site-specific conditions, local aquifer characteristics, and potential environmental impacts as relevant to the project works. Guidelines and documents serve as essential tools in achieving compliance. Douglas Partners is familiar with considering assessments for approvals through the lens of project risks, subsurface uncertainty and the key concerns of the various regulators. Our recommendations are usually shaped by our past experiences with approvals on similar projects and/or similar approval pathways.
The various components of the Dewatering Management Plan are often developed in a staged approach, to suit the timing of design decisions and the project budget. This staged approach may include:
- Initial investigation to assess the ground conditions and aquifer (eg Geotechnical Investigation with groundwater measurements) for initial assessment of ground conditions, and potential dewatering requirements;
- As groundwater levels (and potential inflows) may vary over time, Groundwater Level Monitoring records are generally required, and are key to managing risks to the developer, builder, owners and operators of a site. Limited monitoring data may result in delays to approvals, the need for further monitoring and a need to revise dewatering assessments. Generally, 3 months continuous monitoring will be required when dewatering is proposed.
- Further Hydrogeology Testing to characterise groundwater and groundwater flow, such as by permeability testing, water quality testing and contamination assessment (eg preliminary or detailed site contamination investigations – if not already undertaken).
- Inflow assessment for the proposed development, during construction and in the long-term, given the proposed design.
- Impact assessment given the results of the above, including potential for impacts on neighbouring structures and sensitive ecology in the region.
- Finally, integration of the above information with the final adopted design and construction information, in a DMP, together with appropriate management and general monitoring requirements.
A preliminary DMP may be suitable to allow the project to advance through some early Council approval stages, when key design decisions have been made, but information from contractors will still be outstanding (eg duration of dewatering, when high inflows are anticipated).
The final DMP, submitted with the approval application, will include the estimated inflow volumes and management requirements that will then form part of the limits and requirements of the Water Supply Works approval.
The Dewatering Management Plan, Water Supply Work Approvals or development conditions may also require:
- A separate Hydrogeological Monitoring Plan for construction, often integrated with the geotechnical monitoring plan, and providing additional detail on monitoring requirements, and simplified information to support compliance during construction stages; and,
- A completion report at the end of construction and prior to issue of an occupancy certificate, to demonstrate compliance with monitoring and measurement conditions. This would generally include the results of ongoing groundwater level monitoring, inflow volumes and water quality testing.
Groundwater monitoring before and during the project work can be key to informing dewatering assessments and to project compliance. Longer, and continuous monitoring periods can also effectively reduce project risks.
A short-term water supply works approval may be provided during construction stage.
Provided that the original approval was undertaken on the basis of a long-term drained basement, that dewatering has been in accordance with the DMP (for that basement) and the requirements of the relevant approvals and licences have been satisfied, a long-term approval may be obtained on the completion of construction.
Water Access Licence
The Water Access Licence concerns only the volume of groundwater ‘taken’ from the common groundwater source by dewatering. This volume is estimated in the DMP.
Unless an exemption applies, a Water Access Licence (WAL) with sufficient water entitlements from the relevant groundwater source, will be required and allocated to the subject site.
The entitlements (also known as allocation or shares) are generally the limiting factor for using a water access licence. Entitlements can be obtained through a water broker or from a periodic Controlled Allocation through the relevant department (DCCEEW at the time of writing, but still accessed through the DPIE website). The time required to obtain entitlements can be significant to project timeframes, particularly in urban areas, as controlled allocations may only be released each 1 to 2 years.
The entitlements, rather than the WAL, control timing. A WAL is granted with entitlement from a Controlled Allocation, or entitlements can be traded on to a (readily obtained) zero-allocation WAL.
For basement dewatering, exemptions generally apply where inflows of less than 3ML/year occur and subject to ongoing monitoring, measuring and reporting in accordance with the exemption requirements. Given the time required to obtain entitlements, it may be desirable to obtain an early assessment of potential inflows to a site and likelihood of getting a WAL exemption. Limiting inflows to 3ML/year may be unachievable on some sites or require costly additional works – which would likely be reflected in the requirements of the relevant Approvals. In contrast, for small volumes the cost of entitlements is small.
Water Use Approval
A Water Use Approval may be required for disposal of the water obtained from dewatering, unless an exemption applies.
Provided that the (treated) groundwater meets the requirements of the relevant authority, the Water Use Approval is relatively straightforward. A trade waste agreement, or written agreement from Council may be useful.
Ongoing water quality assessment is generally appropriate, and incorporated into DMP requirements, as quality may change over time.
For further details and personalised assistance, consult with Douglas Partners, your trusted advisor in basement dewatering projects.
