We often get asked by commercial clients about the most common stormwater devices. These normally include GPT’s, Filter Cartridges and OSDs.

Gross pollutant traps (GPTs)

Gross pollutant traps (GPTs) capture litter, sediment and debris that is washed into the stormwater system. Most GPTs are proprietary products that vary in exact form and function but are comprised of similar components. We have 4 approved GPT products, including CDS, HumeGard, Stormceptor, and HumeCeptor.

HumeGuard Gross Pollutant Trap (GPT)
HumeGuard Gross Pollutant Trap

Proprietary GPTs require specialised equipment such as cranes, tip trucks, clamshell grab excavators and educator or vacuum trucks. Stormwater Sydney are experienced in maintaining GPTs and licensed to transport GPT waste.

Our specialised workforce is also covered for sites that may require access for specialised maintenance and monitoring vehicles, specialised equipment for opening manholes and lids, and confined spaces certification for access to conduct some maintenance and monitoring tasks.

Filter cartridges

Filter cartridges include sand filters and proprietary products that operate in a similar way to GPTs but are designed to filter finer pollutants, such as fine solids, soluble heavy metals, oils, and nutrients.

Filter cartridges

Filter cartridges may require a GPT upstream or may include pre-treatment within the unit to prevent clogging from larger solids and litter. They typically need to be located offline with a high flow bypass, as they are designed to treat a limited flow rate.

Material removed from filter cartridges will need to be transported and disposed of at an appropriate waste facility that is licensed to accept such waste. Some devices can only be maintained by their manufacturer as the filter media must be replaced with the same product. The site may require access for specialised maintenance and monitoring vehicles, and specialised equipment for opening manholes and lids. Confined spaces certification and equipment are required for access to conduct some maintenance and monitoring tasks.

On-site Stormwater Detention (OSD)

On-site stormwater detention (OSDs) with above-ground storage
OSD with above-ground storage.

On-site Stormwater Detention (OSD) is the temporary storage and controlled release of stormwater generated on-site. OSD temporarily stores and slows down the rate of stormwater runoff from a property so that it does not worsen flooding downstream, whereas a rainwater tank stores rainwater.

OSD systems can be located above ground or below ground. They should remain empty except during periods of rainfall and shortly after the rainfall ceases. Ponding of water should not last for more than 2 hours in most rain events. If ponding persists, it is likely that maintenance attention is required.

Stormwater Sydney provides Inspection, Cleaning, Maintenance, Repairs, Construction, and Advisory on stormwater systems across Sydney. Ensuring you comply with Council and EPA requirements.


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