Great Lakes Council

The Great Lakes region on the mid-north coast of New South Wales includes the seven townships of Forster, Bulahdelah Hawks Nest" Nabiac, Stroud, Tuncurry and 'Lea Gardens" The region has very diverse catchments that include a large lake.

Stormwater Quality Improvement Project
Monitoring Report June 2001 - January 2002 for At-Source RSF 100 Solid Pollutant Filters
at - Forster - Bulahdelah - Hawks Nest - Nabiac - Stroud - Tuncurry - Tea Gardens

Introduction

The Great Lakes region on the mid-north coast of New South Wales includes the seven townships of Forster, Bulahdelah, Hawks Nest, Nabiac, Stroud, Tuncurry and Tea Gardens. The region has very diverse catchments that include a large lake system, extensive stretches of coastline, and state forests in the hinterland areas.

The Great Lakes Council identified the need to address the quality of stormwater discharges from the central business districts of each of the seven townships and decided that at-source stormwater filtration was the most appropriate and cost-effective solution. Other forms of treatment, such as gross pollutant traps, were not considered appropriate owing to the difficulties presented by tidal influences at many of the proposed locations. The capital costs were also prohibitive.

In 2001, Council successfully applied for a NSW Stormwater Trust grant to carry out the necessary works. It considered various at-source filtration systems and decided to install The EcosolTM At-Source RSF 100 Solid Pollutant Filter in all seven townships.

The EcosolTM RSF 100 Solid Pollutant Filter

The EcosolTM RSF 100 offers a cost-effective means of removing gross pollutants from stormwater flows. The ability to fit the units to existing systems means that drainage lines serving pollutant-generating catchments such as schools, shopping precincts and central business districts, can be effectively targeted for treatment at significantly reduced cost.

The unit is fitted into existing gully pits and will treat all flows entering the pit either through the grate or kerb lintel until the collection basket is full. All subsequent flows pass through the pit via the patented by-pass flaps with no reduction in the inlet capture performance of the pit.

EcosolTM has now fitted 114 of the RSF 100 units to pits throughout the seven townships in the Great Lakes region.

Choosing The EcosolTM RSF 100

Several factors were considered by Council in its decision to use the RSF 100 Solid Pollutant Filter. Whilst cost was a major factor, it was the following key benefits that proved to be of greatest value:

Customised fitting

Each RSF 100 unit is manufactured to suit the configuration of each specific pit. This proved to be a significant feature as there is a wide range of pit dimensions and depths across the seven townships.

Patented By-Pass Overflow

Council had concerns that the installation of other type of devices may cause blockages that would result in localised
flooding. The RSF 100 unit’s unique design includes a patented by-pass flap that ensures inflows can continue to
pass through the pit even when its collection bag is full.

Ease of Cleaning and Maintenance

It was important that the system did not impose on Council a major cleaning and maintenance burden and could be managed by its own cleaning crews. The RSF 100 units can be easily and quickly cleaned by either suction from a street sweeper style vehicle or manually removing the collection bag liner.

Reduced Pipeline Maintenance

Certain catchments within the Great Lakes region generate significant quantities of silt and sediment run-off. Trapping these pollutants at-source reduces the sedimentation build-up and also on-going maintenance costs in down stream pipelines.

Data Collection

Since installation of The EcosolTM RSF 100 at-source units in June 2001, Council has been collating performance data as part of the requirements of the Stormwater Trust Grant. The information was collected by Council staff, who, at each clean, recorded the weights and composition of the captured material.

The following tables detail the collection performance in each of the seven townships - Attachment 1 has more detail, including monthly rainfall intensities for each township:

Great Lakes Council Great Lakes Pollutants

Data Collection (cont)

The following tables and graphs highlight two of the townships’ data detailing monthly pollutant capture performance and rainfall intensities:

Great Lakes Council Great Lakes Forster

Great Lakes Council Great Lakes Bulahdelah

The above graphs clearly highlight the variation in pollutant types generated by different catchments. Pollutant loading in the Forster catchment is predominantly litter whereas sediments and organics are the major pollutants in Bulahdelah.

1 Please note that there were two cleans in December 2001

Summary

The EcosolTM RSF 100 units installed in the seven townships captured more than 7,178 kgs in the eight-month period from June 2001 to January 2002 that was monitored by the Great Lakes Council. This damaging material would otherwise have entered the surrounding waterways causing significant degradation to water quality in the region.

The project also had other positive outcomes including:

  • It is likely that without the RSF 100 system, much of the 7,178 kgs collected to date would otherwise have become trapped within the pipe system and would have required costly removal. This trapped material can also greatly reduce the hydraulic performance of the drainage system.
  • Since installation of the RSF 100 units, Council now has a greater understanding of the pollutants generated within each catchment and can actively set about tracing the pollution sources. For example, the Forster CBD is an alcohol-free zone but significant quantities of mixed-spirit cans are regularly removed from the pit baskets.
  • The data collection exercise has provided Council with a valuable resource for use in awareness campaigns to communicate to the public the extent of pollution generated in each area. The data can also be used to support policies or any other intervention strategies Council may consider appropriate in the future.

Further Information

Information relating specifically to the Great Lakes Project can be obtained by contacting Council’s Drainage Engineer, Mr Ian Jackson on 02 6591 7273.

Great Lakes Council Great Lakes Volume Composition

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