Dewatering is the process of removing groundwater which ensures construction work can occur safely, keeps water from seeping into the site which could affect engineering, and protects the ongoing integrity of the structure and surrounding area.
Groundwater is a complex and often very fragile resource which plays an important role in natural ecosystems and sub-surface hydrogeology. Also known as aquifers, groundwater sources can be accessed or interfered by different works such as basements, tanks, tunnels, trenches, and excavations.
If there is groundwater on a construction site, it needs to be removed before work can begin. The method required to dewater is determined by the geological conditions and characteristics of the soil, and the level, size and depth of excavation.
To undertake construction dewatering, the following approvals must be obtained from WaterNSW.
- water supply work approval
- water access licence (WAL) - unless the project qualifies for an exemption
- water use approval - unless there is a development application from a local government authority.
If the construction project will involve dewatering, the integrated development assessment process can be initiated by the local council at the time of the development application (DA).
What are the steps in the dewatering process?
- Submit the following applications as required, noting that exemptions are in place for some approvals:
- water supply works approval for construction dewatering – check requirements to see if a dewatering management plan is needed
- water access licence (WAL) and source water if needed
- assign share components between water access licences
- WaterNSW issues approval(s)/licences with conditions.
- Ensure metering is in place as per the dewatering management plan.
- Track water take and maintain records for the completion report.
- If approved water take likely to be exceeded, contact WaterNSW immediately.
- Any suspected breaches of water law will be referred to the Natural Resources Access Regulator (NRAR)
- Notify WaterNSW when dewatering is complete.
- If dewatering is not completed in two years, an application is needed for an extension (12 months).
- If planning to extend, an interim report is required in similar format to the completion report.
- WaterNSW notifies applicants 60 & 30 days ahead of the expiry date.
- On completion, prepare and submit completion report to WaterNSW.
- WaterNSW certifies that the completion report satisfies all conditions.
- Use the WaterNSW acceptance of the completion report to obtain an occupancy certificate.
- Application for a water supply works approval for construction dewatering (PDF form) (Guide)
- Application for a water use approval for construction dewatering (PDF form) (Guide)
- Application for a water access licence with zero share component (PDF form)
- Apply and pay online to assign share components between water access licences
(PDF form) (Guide)