This project was assisted by the NSW Government through its Stormwater Trust

Ukerebagh Passage on the Tweed River contains regionally important seagrass and mangrove communities. The passage passes through Ukerebagh Nature Reserve and receives stormwater influent from adjacent urban, commercial and industrial areas. Recent studies have shown a decline in the total area of seagrass beds in the Ukerebagh Passage. This decline of seagrass may be attributed in part to excessive nutrients, pollutants and turbidity from stormwater entering the passage.

There are two major stormwater outfalls into Ukerebagh Passage; Duffy Street and Water Street. A study commissioned by Tweed Shire Council recommended, for the Water Street outfall, a combination of a Gross Pollutant Trap upstream, complimented by a litter boom downstream as this stormwater line has a long section of open drain.

Council installed a floating stormwater litter boom on the downstream end of the Water Street drain to remove floating litter and other pollutants such as oil and hydrocarbon slicks.

This Project saw the construction of an Ecosol RSF 4000 in-line solid pollutants and oil and grease arrester in the upstream section of the open drain, close to the major pollution source. This unit will remove a high proportion of sediment, organic material, debris, oils and greases from the Water Street stormwater drain prior to it discharging into the sensitive environment of Ukerebagh Passage.

The Ecosol RSF 4000 unit is being monitored to determine the efficacy of this particular type of technology under the specific conditions and constraints of the site. Some of the site constraints include; a diverse range of pollutants including heavy metals, tidal situation, flat grades upstream of unit, and ability to cope with local rainfall and runoff conditions.

This Project has been subject to an ongoing monitoring program that will seek to assess amounts and types of pollutants trapped and monitor improvements in water quality and habitat, particularly seagrass. Water quality monitoring was commenced in this drain in January 1996 and will continue until at least August 1999.

The trap contents have not been categorised as the Unit has not yet been cleaned due to high water levels in the drain. Modifications to the unit are required before maintenance and monitoring of trap contents can be carried out.

The data collected from trap monitoring will be used in the Stormwater Awareness Campaign of Tweed Shire Council as a "graphic" example of the potential impact of stormwater on our waterways. This Campaign was commenced in March 1998 and will be continued for several years.

Back to top

1.0 Introduction

1.1 Background

The Tweed River estuary headlined in recent years when pollution contamination fears severely impacted on the local oyster industry. Recent reports (Patterson Britton and Partners, 1995; Tweed Laboratory Centre, 1997) have highlighted the poor water quality within Ukerebagh Passage as compared with nearby sites within the lower Tweed River estuary.

Ukerebagh Passage passes through Ukerebagh Nature Reserve and receives stormwater influent from adjacent urban, commercial and industrial areas of South Tweed Heads. The passage is tidal and shallow and supports large seagrass beds as well as unique mangrove communities. Recent research (Patterson Britton and Partners, 1995) has shown a significant decrease in the total area of the seagrass beds in Ukerebagh Passage. The importance of seagrass communities to marine life has been well established and the decline of the seagrass beds can only lead to a reduction in bio-diversity and viability of this important habitat.

Pollutants from stormwater runoff are a significant contributing factor for the decline of water quality in urban waterways. Two major stormwater drains enter Ukerebagh Passage. The catchment for these drains includes urban, commercial and industrial areas. The main objective of this project was to alleviate some of the pollutant load on the ecosystem through installation of a stormwater quality improvement device to remove a major portion of pollutants without impeding the flow of stormwater in low lying, flood prone land.

1.2 Project Objectives

The objectives of this Project are:

• To remove a major portion of sediment and adsorbed nutrients and heavy metals, vegetation, litter, debris, oils and greases from the stormwater entering Ukerebagh Passage from the Water Street stormwater drain.

• To improve the habitat values of the local estuarine communities by excluding harmful pollutants from stormwater that may damage or inhibit ecological processes.

• To increase public awareness about stormwater by documenting and publishing the findings of our stormwater monitoring program.

• To improve the aesthetic qualities and amenity of Ukerebagh Passage by reducing the amount of litter and floating pollutants that enter the waterway.

• To collate amounts and types of pollutants trapped and monitor improvements in water quality and habitat values through an ongoing monitoring program.

• To contribute to the holistic management of water quality throughout Tweed Shire.

Ukerebagh Passage is a vital fisheries habitat which is suffering from polluted stormwater input. This stormwater quality improvement device was placed on one of two major stormwater drains that flow into Ukerebagh Passage. Reducing this source of pollutants will help increase the viability of this important estuarine habitat.

Back to top

2.0 Project Description

The Water Street stormwater drain and outfall was identified in the Lower Tweed Estuary Stormwater Influent Study (Martin Findlater and Associates, 1995) and the Ukerebagh Passage Management Plan (Patterson Britton and Partners, 1995) as a high priority site for installation of stormwater quality improvement device (SQID).

Water quality monitoring has been undertaken in this particular drain since January 1996 in anticipation of a SQID being installed. An auto-sampler was installed downstream of the site which is triggered by rainfall to collect up to 24 samples.

The Stormwater Treatment Facilities (Maunsell, 1996) report identified this site as a potential site for installation of a gross pollutant trap that would also collect sediments, oils and greases. This was based on the catchment size, type and the sensitive nature of the receiving waters.

Subsequent investigations by Council officers into Gross Pollutant Trap technologies led to selection of the Ecosol RSF 4000 In-line Solid Pollutant Filter / Oil and Grease Arrester for installation on the 1500 x 1500 RCBC outlet.

The land uses within the catchment of this stormwater line are industrial and commercial and the outfall flows into Ukerebagh Passage, a section of the Tweed River estuary.

The Project also includes water quality monitoring and education and awareness components. Tweed Shire Council commenced a Stormwater Awareness Campaign in March 1998. This Project, specifically the data collected from monitoring of water quality and trapped pollutants, will be an important component of this ongoing Awareness Campaign. Media releases and information disseminated to the community add to the overall awareness of the issues and reinforce advertising being undertaken as part of the campaign.

For more information contact:

Project Manager: Jane Lofthouse
Position: River Management Co-ordinator
Telephone: (02) 66702743
E-mail: jlofthouse@tweed.nsw.gov.au