Understanding Council’s erosion control requirements before you dewater a construction site.
Dewatering refers to the removal of accumulated water from any hole, excavation or sediment trap on a construction site.
Excavations can fill with stormwater or groundwater. These must be emptied before work can continue.
Under the Protection of the Environment Operations Act 1997 (POEO Act), owner-builders, builders and landscapers are responsible and accountable for preventing sediment and construction wastewater from leaving a building site.
Depending on the size of your development, your Development Application will require either an Erosion and Sediment Control Plan (ESCP) or a Soil and Water Management Plan (SWMP).
Find out more about improving erosion and sediment control on building sites.
1. Tanker truck
Water pumped into a tanker truck must be disposed of at an EPA-licensed waste facility. You must retain all your receipts and provide them to Council officers if requested.
2. Council’s stormwater network
If water is to be pumped into the stormwater network, it MUST be filtered.
The water to be discharged must also meet the following criteria:
- The concentration of suspended solids in the accumulated water must not exceed 50mg/L
- The pH of the water must be between 6.5 and 8.5
- The water must contain no visible oil or grease
- The water must not contain any substance known to be toxic to aquatic life
- A copy of the sample test results for pH and suspended solids from a NATA-accredited laboratory must be provided to Council upon request
You must also comply with any specific requirements in your development consent.
- Larger developments
Sediment tanks and silt stoppers with internal baffles or similarly designed sediment settling systems are required from the commencement of excavation.
These systems reduce sediment settling time, allow continuous pumping and can accommodate chemical dosing. They are available from most hire companies.
- Smaller Developments
Products that trap or filter suspended sediments from the water column are required.
Options include silt socks, pump seep bags, GeoBags and dewatering bags (or similar) that attach to the ends of hoses and submersible inlets.
These methods should be used in conjunction with the requirements outlined in your Erosion and Sediment Control Plan (ESCP) or your Soil and Water Management Plan (SWMP).