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 serves 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 helps 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, integrated developments allow key WaterNSW requirements to be integrated into the DA requirements through 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.
Additional permits and approvals for dewatering may also be a part of post-DA Council requirements, and can influence reporting and assessment requirements.
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, groundwater impact and dewatering assessment and approvals are generally integrated into the Secretary’s environmental assessment requirements (SEARs) and authority approval. Where significant dewatering is required, appropriate entitlements (see WAL, below) may need to be held by the proponent before State Significant Development or Infrastructure (SSD/SSI) approval is granted.
Typical Approvals and Licences
Typical approvals and licences include:
Water Supply Works Approval (from WaterNSW or NSW DCCEEW): 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 is a detailed process integrating geotechnical and contamination assessments together with key development and construction elements.
Water Access Licence (WAL) – (From WaterNSW or NSW DCCEEW): This licence 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 (also known as ‘water share’), obtained from a water broker or via a Controlled Allocation process, must be held on the WAL 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 are 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.
These are discussed in further detail in later sections.
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 DMP 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 hydraulic conductivity (sometimes referred to as 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. Groundwater inflows and dewatering rates are generally estimated using analytical or numerical modelling.
- Groundwater Impact Assessment (GIA) also known as a Hydrogeological Impact Assessment (HIA) given the results of the above, including potential for impacts on neighbouring structures, nearby groundwater users 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 GIA/HIA or preliminary DMP may be suitable and necessary to allow the project to advance through some early Council approval stages (ie DA), when key design decisions have been made (such as the adoption of a long-term drained basement). Information from contractors may be required (eg duration of dewatering), depending on the project.
A more detailed DMP would generally be required for the Water Supply Works Approval. The level of detail required in this DMP may depend on the details of the project and/or Council and other regulatory requirements. In some cases, detailed plans and information from the building or dewatering contractor may be required for submission with a final DMP, or for Council permits. The estimated inflow volumes and management requirements would generally form a part of the resulting Water Supply Works Approval.
The DMP, Water Supply Work Approvals or development conditions may also require:
- A separate Groundwater or 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, and the expiry date of the approval should be reviewed.
For integrated developments, provided that the original GTAs and DA approval were 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. Revision of the existing DMP into an Operational-Phase DMP may be required to reflect the different methods and equipment used for the operational phase of the project.
Water Access Licence (WAL)
The WAL concerns only the volume(s) of water directly or indirectly ‘taken’ from water sources affected by dewatering – typically groundwater in the case of basement dewatering. This volume is estimated in the DMP.
Unless an exemption applies, a WAL with sufficient water entitlements from the relevant water sources 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 WAL. 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 every 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, although an exemption would generally apply for works subject to development consent.
Provided that the (treated) groundwater meets the requirements of the relevant authority and agreement has been obtained from that authority, the Water Use Approval can be 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.
Council Permits and Approvals
Some Councils (eg City of Sydney Council) have additional dewatering permit or approval processes that may need to be considered in the development of the DMP.
For further details and personalised assistance, consult with Douglas Partners, your trusted advisor in basement dewatering projects.
