Dewatering Management Plan
Summary
A Dewatering Management Plan (DMP) is a site-specific document that sets out how groundwater or surface water will be managed during excavation, construction or remediation works. The purpose of a DMP is to control water extraction, treatment and discharge in a manner that protects the environment, surrounding infrastructure and regulatory compliance.
DMPs are commonly required for projects involving deep excavations, basements, contaminated land remediation or works below the groundwater table, particularly where water quality or off-site impacts are a concern.
Definition
A Dewatering Management Plan is a technical management document that identifies dewatering requirements and defines control measures for groundwater extraction, handling, treatment, monitoring and discharge during site works.
A DMP is typically informed by groundwater investigations and considers both quantity and quality of water to ensure that dewatering activities do not cause unacceptable environmental or structural impacts.
Why Dewatering Management Plans Matter
From an environmental and risk management perspective, dewatering can have significant impacts if not properly controlled.
Unmanaged dewatering may result in the mobilisation of contaminated groundwater, discharge of polluted water to stormwater systems or waterways, ground settlement, impacts to neighbouring properties or changes to local groundwater regimes.
Where contamination is present, dewatering can also spread contaminants beyond the excavation area if water quality is not adequately assessed and managed. A DMP provides a framework for identifying these risks early and implementing appropriate controls.
From a compliance perspective, regulators and councils commonly require a DMP to demonstrate that dewatering will be undertaken in accordance with environmental protection requirements and approval conditions.
When a Dewatering Management Plan Is Typically Required
A Dewatering Management Plan is commonly required where:
Excavations extend below the groundwater table
Basements, service trenches or deep foundations are proposed
Contaminated groundwater may be encountered
Groundwater discharge to stormwater or surface water is proposed
Development consent or environmental approvals require dewatering controls
Construction works may affect surrounding groundwater conditions
The level of detail required depends on the scale of dewatering and the sensitivity of surrounding receptors.
Typical Contents of a DMP
While scope varies by site, a Dewatering Management Plan commonly includes:
Summary of site conditions and groundwater investigation findings
Dewatering methodology and expected volumes
Groundwater quality assessment and treatment requirements
Discharge locations and approval pathways
Monitoring and inspection requirements
Trigger levels and contingency measures
Roles, responsibilities and reporting requirements
The plan is intended to guide practical implementation during works.
Legislative and Regulatory Context
Dewatering is regulated through a combination of environmental protection legislation, planning approvals and water management requirements.
In New South Wales, dewatering activities may be subject to EPA requirements, council conditions and water authority approvals, particularly where contaminated groundwater or off-site discharge is involved. Similar regulatory frameworks apply in other Australian jurisdictions.
Regulators expect dewatering to be planned, monitored and documented in a manner that prevents environmental harm.
How We Can Help
Confluence Environmental prepares Dewatering Management Plans as part of broader contaminated land, groundwater and construction support services.
Our services typically include:
Review of groundwater investigations and site conditions
Assessment of groundwater quality and dewatering risks
Preparation of site-specific Dewatering Management Plans
Integration with remediation, CEMP and construction workflows
Ongoing advisory support during implementation and monitoring
We focus on producing DMPs that are practical, proportionate and aligned with approval conditions.
Related Terms and Concepts
Groundwater Investigation
Contaminated Land
Detailed Site Investigation
Remediation Action Plan
Construction Environmental Management Plan
Acid Sulfate Soil Management Plan
Site Validation